[Feature]add MT2731_MP2_MR2_SVN388 baseline version
Change-Id: Ief04314834b31e27effab435d3ca8ba33b499059
diff --git a/src/kernel/linux/v4.14/fs/namei.c b/src/kernel/linux/v4.14/fs/namei.c
new file mode 100644
index 0000000..6c7beee
--- /dev/null
+++ b/src/kernel/linux/v4.14/fs/namei.c
@@ -0,0 +1,4962 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * linux/fs/namei.c
+ *
+ * Copyright (C) 1991, 1992 Linus Torvalds
+ */
+
+/*
+ * Some corrections by tytso.
+ */
+
+/* [Feb 1997 T. Schoebel-Theuer] Complete rewrite of the pathname
+ * lookup logic.
+ */
+/* [Feb-Apr 2000, AV] Rewrite to the new namespace architecture.
+ */
+
+#include <linux/init.h>
+#include <linux/export.h>
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/fs.h>
+#include <linux/namei.h>
+#include <linux/pagemap.h>
+#include <linux/fsnotify.h>
+#include <linux/personality.h>
+#include <linux/security.h>
+#include <linux/ima.h>
+#include <linux/syscalls.h>
+#include <linux/mount.h>
+#include <linux/audit.h>
+#include <linux/capability.h>
+#include <linux/file.h>
+#include <linux/fcntl.h>
+#include <linux/device_cgroup.h>
+#include <linux/fs_struct.h>
+#include <linux/posix_acl.h>
+#include <linux/hash.h>
+#include <linux/bitops.h>
+#include <linux/init_task.h>
+#include <linux/uaccess.h>
+
+#include "internal.h"
+#include "mount.h"
+
+/* [Feb-1997 T. Schoebel-Theuer]
+ * Fundamental changes in the pathname lookup mechanisms (namei)
+ * were necessary because of omirr. The reason is that omirr needs
+ * to know the _real_ pathname, not the user-supplied one, in case
+ * of symlinks (and also when transname replacements occur).
+ *
+ * The new code replaces the old recursive symlink resolution with
+ * an iterative one (in case of non-nested symlink chains). It does
+ * this with calls to <fs>_follow_link().
+ * As a side effect, dir_namei(), _namei() and follow_link() are now
+ * replaced with a single function lookup_dentry() that can handle all
+ * the special cases of the former code.
+ *
+ * With the new dcache, the pathname is stored at each inode, at least as
+ * long as the refcount of the inode is positive. As a side effect, the
+ * size of the dcache depends on the inode cache and thus is dynamic.
+ *
+ * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink
+ * resolution to correspond with current state of the code.
+ *
+ * Note that the symlink resolution is not *completely* iterative.
+ * There is still a significant amount of tail- and mid- recursion in
+ * the algorithm. Also, note that <fs>_readlink() is not used in
+ * lookup_dentry(): lookup_dentry() on the result of <fs>_readlink()
+ * may return different results than <fs>_follow_link(). Many virtual
+ * filesystems (including /proc) exhibit this behavior.
+ */
+
+/* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation:
+ * New symlink semantics: when open() is called with flags O_CREAT | O_EXCL
+ * and the name already exists in form of a symlink, try to create the new
+ * name indicated by the symlink. The old code always complained that the
+ * name already exists, due to not following the symlink even if its target
+ * is nonexistent. The new semantics affects also mknod() and link() when
+ * the name is a symlink pointing to a non-existent name.
+ *
+ * I don't know which semantics is the right one, since I have no access
+ * to standards. But I found by trial that HP-UX 9.0 has the full "new"
+ * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the
+ * "old" one. Personally, I think the new semantics is much more logical.
+ * Note that "ln old new" where "new" is a symlink pointing to a non-existing
+ * file does succeed in both HP-UX and SunOs, but not in Solaris
+ * and in the old Linux semantics.
+ */
+
+/* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink
+ * semantics. See the comments in "open_namei" and "do_link" below.
+ *
+ * [10-Sep-98 Alan Modra] Another symlink change.
+ */
+
+/* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks:
+ * inside the path - always follow.
+ * in the last component in creation/removal/renaming - never follow.
+ * if LOOKUP_FOLLOW passed - follow.
+ * if the pathname has trailing slashes - follow.
+ * otherwise - don't follow.
+ * (applied in that order).
+ *
+ * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT
+ * restored for 2.4. This is the last surviving part of old 4.2BSD bug.
+ * During the 2.4 we need to fix the userland stuff depending on it -
+ * hopefully we will be able to get rid of that wart in 2.5. So far only
+ * XEmacs seems to be relying on it...
+ */
+/*
+ * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland)
+ * implemented. Let's see if raised priority of ->s_vfs_rename_mutex gives
+ * any extra contention...
+ */
+
+/* In order to reduce some races, while at the same time doing additional
+ * checking and hopefully speeding things up, we copy filenames to the
+ * kernel data space before using them..
+ *
+ * POSIX.1 2.4: an empty pathname is invalid (ENOENT).
+ * PATH_MAX includes the nul terminator --RR.
+ */
+
+#define EMBEDDED_NAME_MAX (PATH_MAX - offsetof(struct filename, iname))
+
+struct filename *
+getname_flags(const char __user *filename, int flags, int *empty)
+{
+ struct filename *result;
+ char *kname;
+ int len;
+
+ result = audit_reusename(filename);
+ if (result)
+ return result;
+
+ result = __getname();
+ if (unlikely(!result))
+ return ERR_PTR(-ENOMEM);
+
+ /*
+ * First, try to embed the struct filename inside the names_cache
+ * allocation
+ */
+ kname = (char *)result->iname;
+ result->name = kname;
+
+ len = strncpy_from_user(kname, filename, EMBEDDED_NAME_MAX);
+ if (unlikely(len < 0)) {
+ __putname(result);
+ return ERR_PTR(len);
+ }
+
+ /*
+ * Uh-oh. We have a name that's approaching PATH_MAX. Allocate a
+ * separate struct filename so we can dedicate the entire
+ * names_cache allocation for the pathname, and re-do the copy from
+ * userland.
+ */
+ if (unlikely(len == EMBEDDED_NAME_MAX)) {
+ const size_t size = offsetof(struct filename, iname[1]);
+ kname = (char *)result;
+
+ /*
+ * size is chosen that way we to guarantee that
+ * result->iname[0] is within the same object and that
+ * kname can't be equal to result->iname, no matter what.
+ */
+ result = kzalloc(size, GFP_KERNEL);
+ if (unlikely(!result)) {
+ __putname(kname);
+ return ERR_PTR(-ENOMEM);
+ }
+ result->name = kname;
+ len = strncpy_from_user(kname, filename, PATH_MAX);
+ if (unlikely(len < 0)) {
+ __putname(kname);
+ kfree(result);
+ return ERR_PTR(len);
+ }
+ if (unlikely(len == PATH_MAX)) {
+ __putname(kname);
+ kfree(result);
+ return ERR_PTR(-ENAMETOOLONG);
+ }
+ }
+
+ result->refcnt = 1;
+ /* The empty path is special. */
+ if (unlikely(!len)) {
+ if (empty)
+ *empty = 1;
+ if (!(flags & LOOKUP_EMPTY)) {
+ putname(result);
+ return ERR_PTR(-ENOENT);
+ }
+ }
+
+ result->uptr = filename;
+ result->aname = NULL;
+ audit_getname(result);
+ return result;
+}
+
+struct filename *
+getname(const char __user * filename)
+{
+ return getname_flags(filename, 0, NULL);
+}
+
+struct filename *
+getname_kernel(const char * filename)
+{
+ struct filename *result;
+ int len = strlen(filename) + 1;
+
+ result = __getname();
+ if (unlikely(!result))
+ return ERR_PTR(-ENOMEM);
+
+ if (len <= EMBEDDED_NAME_MAX) {
+ result->name = (char *)result->iname;
+ } else if (len <= PATH_MAX) {
+ const size_t size = offsetof(struct filename, iname[1]);
+ struct filename *tmp;
+
+ tmp = kmalloc(size, GFP_KERNEL);
+ if (unlikely(!tmp)) {
+ __putname(result);
+ return ERR_PTR(-ENOMEM);
+ }
+ tmp->name = (char *)result;
+ result = tmp;
+ } else {
+ __putname(result);
+ return ERR_PTR(-ENAMETOOLONG);
+ }
+ memcpy((char *)result->name, filename, len);
+ result->uptr = NULL;
+ result->aname = NULL;
+ result->refcnt = 1;
+ audit_getname(result);
+
+ return result;
+}
+
+void putname(struct filename *name)
+{
+ BUG_ON(name->refcnt <= 0);
+
+ if (--name->refcnt > 0)
+ return;
+
+ if (name->name != name->iname) {
+ __putname(name->name);
+ kfree(name);
+ } else
+ __putname(name);
+}
+
+static int check_acl(struct inode *inode, int mask)
+{
+#ifdef CONFIG_FS_POSIX_ACL
+ struct posix_acl *acl;
+
+ if (mask & MAY_NOT_BLOCK) {
+ acl = get_cached_acl_rcu(inode, ACL_TYPE_ACCESS);
+ if (!acl)
+ return -EAGAIN;
+ /* no ->get_acl() calls in RCU mode... */
+ if (is_uncached_acl(acl))
+ return -ECHILD;
+ return posix_acl_permission(inode, acl, mask & ~MAY_NOT_BLOCK);
+ }
+
+ acl = get_acl(inode, ACL_TYPE_ACCESS);
+ if (IS_ERR(acl))
+ return PTR_ERR(acl);
+ if (acl) {
+ int error = posix_acl_permission(inode, acl, mask);
+ posix_acl_release(acl);
+ return error;
+ }
+#endif
+
+ return -EAGAIN;
+}
+
+/*
+ * This does the basic permission checking
+ */
+static int acl_permission_check(struct inode *inode, int mask)
+{
+ unsigned int mode = inode->i_mode;
+
+ if (likely(uid_eq(current_fsuid(), inode->i_uid)))
+ mode >>= 6;
+ else {
+ if (IS_POSIXACL(inode) && (mode & S_IRWXG)) {
+ int error = check_acl(inode, mask);
+ if (error != -EAGAIN)
+ return error;
+ }
+
+ if (in_group_p(inode->i_gid))
+ mode >>= 3;
+ }
+
+ /*
+ * If the DACs are ok we don't need any capability check.
+ */
+ if ((mask & ~mode & (MAY_READ | MAY_WRITE | MAY_EXEC)) == 0)
+ return 0;
+ return -EACCES;
+}
+
+/**
+ * generic_permission - check for access rights on a Posix-like filesystem
+ * @inode: inode to check access rights for
+ * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC, ...)
+ *
+ * Used to check for read/write/execute permissions on a file.
+ * We use "fsuid" for this, letting us set arbitrary permissions
+ * for filesystem access without changing the "normal" uids which
+ * are used for other things.
+ *
+ * generic_permission is rcu-walk aware. It returns -ECHILD in case an rcu-walk
+ * request cannot be satisfied (eg. requires blocking or too much complexity).
+ * It would then be called again in ref-walk mode.
+ */
+int generic_permission(struct inode *inode, int mask)
+{
+ int ret;
+
+ /*
+ * Do the basic permission checks.
+ */
+ ret = acl_permission_check(inode, mask);
+ if (ret != -EACCES)
+ return ret;
+
+ if (S_ISDIR(inode->i_mode)) {
+ /* DACs are overridable for directories */
+ if (!(mask & MAY_WRITE))
+ if (capable_wrt_inode_uidgid(inode,
+ CAP_DAC_READ_SEARCH))
+ return 0;
+ if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE))
+ return 0;
+ return -EACCES;
+ }
+
+ /*
+ * Searching includes executable on directories, else just read.
+ */
+ mask &= MAY_READ | MAY_WRITE | MAY_EXEC;
+ if (mask == MAY_READ)
+ if (capable_wrt_inode_uidgid(inode, CAP_DAC_READ_SEARCH))
+ return 0;
+ /*
+ * Read/write DACs are always overridable.
+ * Executable DACs are overridable when there is
+ * at least one exec bit set.
+ */
+ if (!(mask & MAY_EXEC) || (inode->i_mode & S_IXUGO))
+ if (capable_wrt_inode_uidgid(inode, CAP_DAC_OVERRIDE))
+ return 0;
+
+ return -EACCES;
+}
+EXPORT_SYMBOL(generic_permission);
+
+/*
+ * We _really_ want to just do "generic_permission()" without
+ * even looking at the inode->i_op values. So we keep a cache
+ * flag in inode->i_opflags, that says "this has not special
+ * permission function, use the fast case".
+ */
+static inline int do_inode_permission(struct vfsmount *mnt, struct inode *inode, int mask)
+{
+ if (unlikely(!(inode->i_opflags & IOP_FASTPERM))) {
+ if (likely(mnt && inode->i_op->permission2))
+ return inode->i_op->permission2(mnt, inode, mask);
+ if (likely(inode->i_op->permission))
+ return inode->i_op->permission(inode, mask);
+
+ /* This gets set once for the inode lifetime */
+ spin_lock(&inode->i_lock);
+ inode->i_opflags |= IOP_FASTPERM;
+ spin_unlock(&inode->i_lock);
+ }
+ return generic_permission(inode, mask);
+}
+
+/**
+ * __inode_permission - Check for access rights to a given inode
+ * @inode: Inode to check permission on
+ * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
+ *
+ * Check for read/write/execute permissions on an inode.
+ *
+ * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask.
+ *
+ * This does not check for a read-only file system. You probably want
+ * inode_permission().
+ */
+int __inode_permission2(struct vfsmount *mnt, struct inode *inode, int mask)
+{
+ int retval;
+
+ if (unlikely(mask & MAY_WRITE)) {
+ /*
+ * Nobody gets write access to an immutable file.
+ */
+ if (IS_IMMUTABLE(inode))
+ return -EPERM;
+
+ /*
+ * Updating mtime will likely cause i_uid and i_gid to be
+ * written back improperly if their true value is unknown
+ * to the vfs.
+ */
+ if (HAS_UNMAPPED_ID(inode))
+ return -EACCES;
+ }
+
+ retval = do_inode_permission(mnt, inode, mask);
+ if (retval)
+ return retval;
+
+ retval = devcgroup_inode_permission(inode, mask);
+ if (retval)
+ return retval;
+
+ retval = security_inode_permission(inode, mask);
+ return retval;
+}
+EXPORT_SYMBOL(__inode_permission2);
+
+int __inode_permission(struct inode *inode, int mask)
+{
+ return __inode_permission2(NULL, inode, mask);
+}
+EXPORT_SYMBOL(__inode_permission);
+
+/**
+ * sb_permission - Check superblock-level permissions
+ * @sb: Superblock of inode to check permission on
+ * @inode: Inode to check permission on
+ * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
+ *
+ * Separate out file-system wide checks from inode-specific permission checks.
+ */
+static int sb_permission(struct super_block *sb, struct inode *inode, int mask)
+{
+ if (unlikely(mask & MAY_WRITE)) {
+ umode_t mode = inode->i_mode;
+
+ /* Nobody gets write access to a read-only fs. */
+ if (sb_rdonly(sb) && (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode)))
+ return -EROFS;
+ }
+ return 0;
+}
+
+/**
+ * inode_permission - Check for access rights to a given inode
+ * @inode: Inode to check permission on
+ * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
+ *
+ * Check for read/write/execute permissions on an inode. We use fs[ug]id for
+ * this, letting us set arbitrary permissions for filesystem access without
+ * changing the "normal" UIDs which are used for other things.
+ *
+ * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask.
+ */
+int inode_permission2(struct vfsmount *mnt, struct inode *inode, int mask)
+{
+ int retval;
+
+ retval = sb_permission(inode->i_sb, inode, mask);
+ if (retval)
+ return retval;
+ return __inode_permission2(mnt, inode, mask);
+}
+EXPORT_SYMBOL(inode_permission2);
+
+int inode_permission(struct inode *inode, int mask)
+{
+ return inode_permission2(NULL, inode, mask);
+}
+EXPORT_SYMBOL(inode_permission);
+
+/**
+ * path_get - get a reference to a path
+ * @path: path to get the reference to
+ *
+ * Given a path increment the reference count to the dentry and the vfsmount.
+ */
+void path_get(const struct path *path)
+{
+ mntget(path->mnt);
+ dget(path->dentry);
+}
+EXPORT_SYMBOL(path_get);
+
+/**
+ * path_put - put a reference to a path
+ * @path: path to put the reference to
+ *
+ * Given a path decrement the reference count to the dentry and the vfsmount.
+ */
+void path_put(const struct path *path)
+{
+ dput(path->dentry);
+ mntput(path->mnt);
+}
+EXPORT_SYMBOL(path_put);
+
+#define EMBEDDED_LEVELS 2
+struct nameidata {
+ struct path path;
+ struct qstr last;
+ struct path root;
+ struct inode *inode; /* path.dentry.d_inode */
+ unsigned int flags;
+ unsigned seq, m_seq;
+ int last_type;
+ unsigned depth;
+ int total_link_count;
+ struct saved {
+ struct path link;
+ struct delayed_call done;
+ const char *name;
+ unsigned seq;
+ } *stack, internal[EMBEDDED_LEVELS];
+ struct filename *name;
+ struct nameidata *saved;
+ struct inode *link_inode;
+ unsigned root_seq;
+ int dfd;
+} __randomize_layout;
+
+static void set_nameidata(struct nameidata *p, int dfd, struct filename *name)
+{
+ struct nameidata *old = current->nameidata;
+ p->stack = p->internal;
+ p->dfd = dfd;
+ p->name = name;
+ p->total_link_count = old ? old->total_link_count : 0;
+ p->saved = old;
+ current->nameidata = p;
+}
+
+static void restore_nameidata(void)
+{
+ struct nameidata *now = current->nameidata, *old = now->saved;
+
+ current->nameidata = old;
+ if (old)
+ old->total_link_count = now->total_link_count;
+ if (now->stack != now->internal)
+ kfree(now->stack);
+}
+
+static int __nd_alloc_stack(struct nameidata *nd)
+{
+ struct saved *p;
+
+ if (nd->flags & LOOKUP_RCU) {
+ p= kmalloc(MAXSYMLINKS * sizeof(struct saved),
+ GFP_ATOMIC);
+ if (unlikely(!p))
+ return -ECHILD;
+ } else {
+ p= kmalloc(MAXSYMLINKS * sizeof(struct saved),
+ GFP_KERNEL);
+ if (unlikely(!p))
+ return -ENOMEM;
+ }
+ memcpy(p, nd->internal, sizeof(nd->internal));
+ nd->stack = p;
+ return 0;
+}
+
+/**
+ * path_connected - Verify that a path->dentry is below path->mnt.mnt_root
+ * @path: nameidate to verify
+ *
+ * Rename can sometimes move a file or directory outside of a bind
+ * mount, path_connected allows those cases to be detected.
+ */
+static bool path_connected(const struct path *path)
+{
+ struct vfsmount *mnt = path->mnt;
+ struct super_block *sb = mnt->mnt_sb;
+
+ /* Bind mounts and multi-root filesystems can have disconnected paths */
+ if (!(sb->s_iflags & SB_I_MULTIROOT) && (mnt->mnt_root == sb->s_root))
+ return true;
+
+ return is_subdir(path->dentry, mnt->mnt_root);
+}
+
+static inline int nd_alloc_stack(struct nameidata *nd)
+{
+ if (likely(nd->depth != EMBEDDED_LEVELS))
+ return 0;
+ if (likely(nd->stack != nd->internal))
+ return 0;
+ return __nd_alloc_stack(nd);
+}
+
+static void drop_links(struct nameidata *nd)
+{
+ int i = nd->depth;
+ while (i--) {
+ struct saved *last = nd->stack + i;
+ do_delayed_call(&last->done);
+ clear_delayed_call(&last->done);
+ }
+}
+
+static void terminate_walk(struct nameidata *nd)
+{
+ drop_links(nd);
+ if (!(nd->flags & LOOKUP_RCU)) {
+ int i;
+ path_put(&nd->path);
+ for (i = 0; i < nd->depth; i++)
+ path_put(&nd->stack[i].link);
+ if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) {
+ path_put(&nd->root);
+ nd->root.mnt = NULL;
+ }
+ } else {
+ nd->flags &= ~LOOKUP_RCU;
+ if (!(nd->flags & LOOKUP_ROOT))
+ nd->root.mnt = NULL;
+ rcu_read_unlock();
+ }
+ nd->depth = 0;
+}
+
+/* path_put is needed afterwards regardless of success or failure */
+static bool legitimize_path(struct nameidata *nd,
+ struct path *path, unsigned seq)
+{
+ int res = __legitimize_mnt(path->mnt, nd->m_seq);
+ if (unlikely(res)) {
+ if (res > 0)
+ path->mnt = NULL;
+ path->dentry = NULL;
+ return false;
+ }
+ if (unlikely(!lockref_get_not_dead(&path->dentry->d_lockref))) {
+ path->dentry = NULL;
+ return false;
+ }
+ return !read_seqcount_retry(&path->dentry->d_seq, seq);
+}
+
+static bool legitimize_links(struct nameidata *nd)
+{
+ int i;
+ for (i = 0; i < nd->depth; i++) {
+ struct saved *last = nd->stack + i;
+ if (unlikely(!legitimize_path(nd, &last->link, last->seq))) {
+ drop_links(nd);
+ nd->depth = i + 1;
+ return false;
+ }
+ }
+ return true;
+}
+
+/*
+ * Path walking has 2 modes, rcu-walk and ref-walk (see
+ * Documentation/filesystems/path-lookup.txt). In situations when we can't
+ * continue in RCU mode, we attempt to drop out of rcu-walk mode and grab
+ * normal reference counts on dentries and vfsmounts to transition to ref-walk
+ * mode. Refcounts are grabbed at the last known good point before rcu-walk
+ * got stuck, so ref-walk may continue from there. If this is not successful
+ * (eg. a seqcount has changed), then failure is returned and it's up to caller
+ * to restart the path walk from the beginning in ref-walk mode.
+ */
+
+/**
+ * unlazy_walk - try to switch to ref-walk mode.
+ * @nd: nameidata pathwalk data
+ * Returns: 0 on success, -ECHILD on failure
+ *
+ * unlazy_walk attempts to legitimize the current nd->path and nd->root
+ * for ref-walk mode.
+ * Must be called from rcu-walk context.
+ * Nothing should touch nameidata between unlazy_walk() failure and
+ * terminate_walk().
+ */
+static int unlazy_walk(struct nameidata *nd)
+{
+ struct dentry *parent = nd->path.dentry;
+
+ BUG_ON(!(nd->flags & LOOKUP_RCU));
+
+ nd->flags &= ~LOOKUP_RCU;
+ if (unlikely(!legitimize_links(nd)))
+ goto out2;
+ if (unlikely(!legitimize_path(nd, &nd->path, nd->seq)))
+ goto out1;
+ if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) {
+ if (unlikely(!legitimize_path(nd, &nd->root, nd->root_seq)))
+ goto out;
+ }
+ rcu_read_unlock();
+ BUG_ON(nd->inode != parent->d_inode);
+ return 0;
+
+out2:
+ nd->path.mnt = NULL;
+ nd->path.dentry = NULL;
+out1:
+ if (!(nd->flags & LOOKUP_ROOT))
+ nd->root.mnt = NULL;
+out:
+ rcu_read_unlock();
+ return -ECHILD;
+}
+
+/**
+ * unlazy_child - try to switch to ref-walk mode.
+ * @nd: nameidata pathwalk data
+ * @dentry: child of nd->path.dentry
+ * @seq: seq number to check dentry against
+ * Returns: 0 on success, -ECHILD on failure
+ *
+ * unlazy_child attempts to legitimize the current nd->path, nd->root and dentry
+ * for ref-walk mode. @dentry must be a path found by a do_lookup call on
+ * @nd. Must be called from rcu-walk context.
+ * Nothing should touch nameidata between unlazy_child() failure and
+ * terminate_walk().
+ */
+static int unlazy_child(struct nameidata *nd, struct dentry *dentry, unsigned seq)
+{
+ BUG_ON(!(nd->flags & LOOKUP_RCU));
+
+ nd->flags &= ~LOOKUP_RCU;
+ if (unlikely(!legitimize_links(nd)))
+ goto out2;
+ if (unlikely(!legitimize_mnt(nd->path.mnt, nd->m_seq)))
+ goto out2;
+ if (unlikely(!lockref_get_not_dead(&nd->path.dentry->d_lockref)))
+ goto out1;
+
+ /*
+ * We need to move both the parent and the dentry from the RCU domain
+ * to be properly refcounted. And the sequence number in the dentry
+ * validates *both* dentry counters, since we checked the sequence
+ * number of the parent after we got the child sequence number. So we
+ * know the parent must still be valid if the child sequence number is
+ */
+ if (unlikely(!lockref_get_not_dead(&dentry->d_lockref)))
+ goto out;
+ if (unlikely(read_seqcount_retry(&dentry->d_seq, seq))) {
+ rcu_read_unlock();
+ dput(dentry);
+ goto drop_root_mnt;
+ }
+ /*
+ * Sequence counts matched. Now make sure that the root is
+ * still valid and get it if required.
+ */
+ if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) {
+ if (unlikely(!legitimize_path(nd, &nd->root, nd->root_seq))) {
+ rcu_read_unlock();
+ dput(dentry);
+ return -ECHILD;
+ }
+ }
+
+ rcu_read_unlock();
+ return 0;
+
+out2:
+ nd->path.mnt = NULL;
+out1:
+ nd->path.dentry = NULL;
+out:
+ rcu_read_unlock();
+drop_root_mnt:
+ if (!(nd->flags & LOOKUP_ROOT))
+ nd->root.mnt = NULL;
+ return -ECHILD;
+}
+
+static inline int d_revalidate(struct dentry *dentry, unsigned int flags)
+{
+ if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE))
+ return dentry->d_op->d_revalidate(dentry, flags);
+ else
+ return 1;
+}
+
+/**
+ * complete_walk - successful completion of path walk
+ * @nd: pointer nameidata
+ *
+ * If we had been in RCU mode, drop out of it and legitimize nd->path.
+ * Revalidate the final result, unless we'd already done that during
+ * the path walk or the filesystem doesn't ask for it. Return 0 on
+ * success, -error on failure. In case of failure caller does not
+ * need to drop nd->path.
+ */
+static int complete_walk(struct nameidata *nd)
+{
+ struct dentry *dentry = nd->path.dentry;
+ int status;
+
+ if (nd->flags & LOOKUP_RCU) {
+ if (!(nd->flags & LOOKUP_ROOT))
+ nd->root.mnt = NULL;
+ if (unlikely(unlazy_walk(nd)))
+ return -ECHILD;
+ }
+
+ if (likely(!(nd->flags & LOOKUP_JUMPED)))
+ return 0;
+
+ if (likely(!(dentry->d_flags & DCACHE_OP_WEAK_REVALIDATE)))
+ return 0;
+
+ status = dentry->d_op->d_weak_revalidate(dentry, nd->flags);
+ if (status > 0)
+ return 0;
+
+ if (!status)
+ status = -ESTALE;
+
+ return status;
+}
+
+static void set_root(struct nameidata *nd)
+{
+ struct fs_struct *fs = current->fs;
+
+ if (nd->flags & LOOKUP_RCU) {
+ unsigned seq;
+
+ do {
+ seq = read_seqcount_begin(&fs->seq);
+ nd->root = fs->root;
+ nd->root_seq = __read_seqcount_begin(&nd->root.dentry->d_seq);
+ } while (read_seqcount_retry(&fs->seq, seq));
+ } else {
+ get_fs_root(fs, &nd->root);
+ }
+}
+
+static void path_put_conditional(struct path *path, struct nameidata *nd)
+{
+ dput(path->dentry);
+ if (path->mnt != nd->path.mnt)
+ mntput(path->mnt);
+}
+
+static inline void path_to_nameidata(const struct path *path,
+ struct nameidata *nd)
+{
+ if (!(nd->flags & LOOKUP_RCU)) {
+ dput(nd->path.dentry);
+ if (nd->path.mnt != path->mnt)
+ mntput(nd->path.mnt);
+ }
+ nd->path.mnt = path->mnt;
+ nd->path.dentry = path->dentry;
+}
+
+static int nd_jump_root(struct nameidata *nd)
+{
+ if (nd->flags & LOOKUP_RCU) {
+ struct dentry *d;
+ nd->path = nd->root;
+ d = nd->path.dentry;
+ nd->inode = d->d_inode;
+ nd->seq = nd->root_seq;
+ if (unlikely(read_seqcount_retry(&d->d_seq, nd->seq)))
+ return -ECHILD;
+ } else {
+ path_put(&nd->path);
+ nd->path = nd->root;
+ path_get(&nd->path);
+ nd->inode = nd->path.dentry->d_inode;
+ }
+ nd->flags |= LOOKUP_JUMPED;
+ return 0;
+}
+
+/*
+ * Helper to directly jump to a known parsed path from ->get_link,
+ * caller must have taken a reference to path beforehand.
+ */
+void nd_jump_link(struct path *path)
+{
+ struct nameidata *nd = current->nameidata;
+ path_put(&nd->path);
+
+ nd->path = *path;
+ nd->inode = nd->path.dentry->d_inode;
+ nd->flags |= LOOKUP_JUMPED;
+}
+
+static inline void put_link(struct nameidata *nd)
+{
+ struct saved *last = nd->stack + --nd->depth;
+ do_delayed_call(&last->done);
+ if (!(nd->flags & LOOKUP_RCU))
+ path_put(&last->link);
+}
+
+int sysctl_protected_symlinks __read_mostly = 0;
+int sysctl_protected_hardlinks __read_mostly = 0;
+int sysctl_protected_fifos __read_mostly;
+int sysctl_protected_regular __read_mostly;
+
+/**
+ * may_follow_link - Check symlink following for unsafe situations
+ * @nd: nameidata pathwalk data
+ *
+ * In the case of the sysctl_protected_symlinks sysctl being enabled,
+ * CAP_DAC_OVERRIDE needs to be specifically ignored if the symlink is
+ * in a sticky world-writable directory. This is to protect privileged
+ * processes from failing races against path names that may change out
+ * from under them by way of other users creating malicious symlinks.
+ * It will permit symlinks to be followed only when outside a sticky
+ * world-writable directory, or when the uid of the symlink and follower
+ * match, or when the directory owner matches the symlink's owner.
+ *
+ * Returns 0 if following the symlink is allowed, -ve on error.
+ */
+static inline int may_follow_link(struct nameidata *nd)
+{
+ const struct inode *inode;
+ const struct inode *parent;
+ kuid_t puid;
+
+ if (!sysctl_protected_symlinks)
+ return 0;
+
+ /* Allowed if owner and follower match. */
+ inode = nd->link_inode;
+ if (uid_eq(current_cred()->fsuid, inode->i_uid))
+ return 0;
+
+ /* Allowed if parent directory not sticky and world-writable. */
+ parent = nd->inode;
+ if ((parent->i_mode & (S_ISVTX|S_IWOTH)) != (S_ISVTX|S_IWOTH))
+ return 0;
+
+ /* Allowed if parent directory and link owner match. */
+ puid = parent->i_uid;
+ if (uid_valid(puid) && uid_eq(puid, inode->i_uid))
+ return 0;
+
+ if (nd->flags & LOOKUP_RCU)
+ return -ECHILD;
+
+ audit_log_link_denied("follow_link", &nd->stack[0].link);
+ return -EACCES;
+}
+
+/**
+ * safe_hardlink_source - Check for safe hardlink conditions
+ * @inode: the source inode to hardlink from
+ *
+ * Return false if at least one of the following conditions:
+ * - inode is not a regular file
+ * - inode is setuid
+ * - inode is setgid and group-exec
+ * - access failure for read and write
+ *
+ * Otherwise returns true.
+ */
+static bool safe_hardlink_source(struct inode *inode)
+{
+ umode_t mode = inode->i_mode;
+
+ /* Special files should not get pinned to the filesystem. */
+ if (!S_ISREG(mode))
+ return false;
+
+ /* Setuid files should not get pinned to the filesystem. */
+ if (mode & S_ISUID)
+ return false;
+
+ /* Executable setgid files should not get pinned to the filesystem. */
+ if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP))
+ return false;
+
+ /* Hardlinking to unreadable or unwritable sources is dangerous. */
+ if (inode_permission(inode, MAY_READ | MAY_WRITE))
+ return false;
+
+ return true;
+}
+
+/**
+ * may_linkat - Check permissions for creating a hardlink
+ * @link: the source to hardlink from
+ *
+ * Block hardlink when all of:
+ * - sysctl_protected_hardlinks enabled
+ * - fsuid does not match inode
+ * - hardlink source is unsafe (see safe_hardlink_source() above)
+ * - not CAP_FOWNER in a namespace with the inode owner uid mapped
+ *
+ * Returns 0 if successful, -ve on error.
+ */
+static int may_linkat(struct path *link)
+{
+ struct inode *inode;
+
+ if (!sysctl_protected_hardlinks)
+ return 0;
+
+ inode = link->dentry->d_inode;
+
+ /* Source inode owner (or CAP_FOWNER) can hardlink all they like,
+ * otherwise, it must be a safe source.
+ */
+ if (safe_hardlink_source(inode) || inode_owner_or_capable(inode))
+ return 0;
+
+ audit_log_link_denied("linkat", link);
+ return -EPERM;
+}
+
+/**
+ * may_create_in_sticky - Check whether an O_CREAT open in a sticky directory
+ * should be allowed, or not, on files that already
+ * exist.
+ * @dir_mode: mode bits of directory
+ * @dir_uid: owner of directory
+ * @inode: the inode of the file to open
+ *
+ * Block an O_CREAT open of a FIFO (or a regular file) when:
+ * - sysctl_protected_fifos (or sysctl_protected_regular) is enabled
+ * - the file already exists
+ * - we are in a sticky directory
+ * - we don't own the file
+ * - the owner of the directory doesn't own the file
+ * - the directory is world writable
+ * If the sysctl_protected_fifos (or sysctl_protected_regular) is set to 2
+ * the directory doesn't have to be world writable: being group writable will
+ * be enough.
+ *
+ * Returns 0 if the open is allowed, -ve on error.
+ */
+static int may_create_in_sticky(umode_t dir_mode, kuid_t dir_uid,
+ struct inode * const inode)
+{
+ if ((!sysctl_protected_fifos && S_ISFIFO(inode->i_mode)) ||
+ (!sysctl_protected_regular && S_ISREG(inode->i_mode)) ||
+ likely(!(dir_mode & S_ISVTX)) ||
+ uid_eq(inode->i_uid, dir_uid) ||
+ uid_eq(current_fsuid(), inode->i_uid))
+ return 0;
+
+ if (likely(dir_mode & 0002) ||
+ (dir_mode & 0020 &&
+ ((sysctl_protected_fifos >= 2 && S_ISFIFO(inode->i_mode)) ||
+ (sysctl_protected_regular >= 2 && S_ISREG(inode->i_mode))))) {
+ return -EACCES;
+ }
+ return 0;
+}
+
+static __always_inline
+const char *get_link(struct nameidata *nd)
+{
+ struct saved *last = nd->stack + nd->depth - 1;
+ struct dentry *dentry = last->link.dentry;
+ struct inode *inode = nd->link_inode;
+ int error;
+ const char *res;
+
+ if (!(nd->flags & LOOKUP_RCU)) {
+ touch_atime(&last->link);
+ cond_resched();
+ } else if (atime_needs_update_rcu(&last->link, inode)) {
+ if (unlikely(unlazy_walk(nd)))
+ return ERR_PTR(-ECHILD);
+ touch_atime(&last->link);
+ }
+
+ error = security_inode_follow_link(dentry, inode,
+ nd->flags & LOOKUP_RCU);
+ if (unlikely(error))
+ return ERR_PTR(error);
+
+ nd->last_type = LAST_BIND;
+ res = inode->i_link;
+ if (!res) {
+ const char * (*get)(struct dentry *, struct inode *,
+ struct delayed_call *);
+ get = inode->i_op->get_link;
+ if (nd->flags & LOOKUP_RCU) {
+ res = get(NULL, inode, &last->done);
+ if (res == ERR_PTR(-ECHILD)) {
+ if (unlikely(unlazy_walk(nd)))
+ return ERR_PTR(-ECHILD);
+ res = get(dentry, inode, &last->done);
+ }
+ } else {
+ res = get(dentry, inode, &last->done);
+ }
+ if (IS_ERR_OR_NULL(res))
+ return res;
+ }
+ if (*res == '/') {
+ if (!nd->root.mnt)
+ set_root(nd);
+ if (unlikely(nd_jump_root(nd)))
+ return ERR_PTR(-ECHILD);
+ while (unlikely(*++res == '/'))
+ ;
+ }
+ if (!*res)
+ res = NULL;
+ return res;
+}
+
+/*
+ * follow_up - Find the mountpoint of path's vfsmount
+ *
+ * Given a path, find the mountpoint of its source file system.
+ * Replace @path with the path of the mountpoint in the parent mount.
+ * Up is towards /.
+ *
+ * Return 1 if we went up a level and 0 if we were already at the
+ * root.
+ */
+int follow_up(struct path *path)
+{
+ struct mount *mnt = real_mount(path->mnt);
+ struct mount *parent;
+ struct dentry *mountpoint;
+
+ read_seqlock_excl(&mount_lock);
+ parent = mnt->mnt_parent;
+ if (parent == mnt) {
+ read_sequnlock_excl(&mount_lock);
+ return 0;
+ }
+ mntget(&parent->mnt);
+ mountpoint = dget(mnt->mnt_mountpoint);
+ read_sequnlock_excl(&mount_lock);
+ dput(path->dentry);
+ path->dentry = mountpoint;
+ mntput(path->mnt);
+ path->mnt = &parent->mnt;
+ return 1;
+}
+EXPORT_SYMBOL(follow_up);
+
+/*
+ * Perform an automount
+ * - return -EISDIR to tell follow_managed() to stop and return the path we
+ * were called with.
+ */
+static int follow_automount(struct path *path, struct nameidata *nd,
+ bool *need_mntput)
+{
+ struct vfsmount *mnt;
+ int err;
+
+ if (!path->dentry->d_op || !path->dentry->d_op->d_automount)
+ return -EREMOTE;
+
+ /* We don't want to mount if someone's just doing a stat -
+ * unless they're stat'ing a directory and appended a '/' to
+ * the name.
+ *
+ * We do, however, want to mount if someone wants to open or
+ * create a file of any type under the mountpoint, wants to
+ * traverse through the mountpoint or wants to open the
+ * mounted directory. Also, autofs may mark negative dentries
+ * as being automount points. These will need the attentions
+ * of the daemon to instantiate them before they can be used.
+ */
+ if (!(nd->flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY |
+ LOOKUP_OPEN | LOOKUP_CREATE | LOOKUP_AUTOMOUNT)) &&
+ path->dentry->d_inode)
+ return -EISDIR;
+
+ nd->total_link_count++;
+ if (nd->total_link_count >= 40)
+ return -ELOOP;
+
+ mnt = path->dentry->d_op->d_automount(path);
+ if (IS_ERR(mnt)) {
+ /*
+ * The filesystem is allowed to return -EISDIR here to indicate
+ * it doesn't want to automount. For instance, autofs would do
+ * this so that its userspace daemon can mount on this dentry.
+ *
+ * However, we can only permit this if it's a terminal point in
+ * the path being looked up; if it wasn't then the remainder of
+ * the path is inaccessible and we should say so.
+ */
+ if (PTR_ERR(mnt) == -EISDIR && (nd->flags & LOOKUP_PARENT))
+ return -EREMOTE;
+ return PTR_ERR(mnt);
+ }
+
+ if (!mnt) /* mount collision */
+ return 0;
+
+ if (!*need_mntput) {
+ /* lock_mount() may release path->mnt on error */
+ mntget(path->mnt);
+ *need_mntput = true;
+ }
+ err = finish_automount(mnt, path);
+
+ switch (err) {
+ case -EBUSY:
+ /* Someone else made a mount here whilst we were busy */
+ return 0;
+ case 0:
+ path_put(path);
+ path->mnt = mnt;
+ path->dentry = dget(mnt->mnt_root);
+ return 0;
+ default:
+ return err;
+ }
+
+}
+
+/*
+ * Handle a dentry that is managed in some way.
+ * - Flagged for transit management (autofs)
+ * - Flagged as mountpoint
+ * - Flagged as automount point
+ *
+ * This may only be called in refwalk mode.
+ *
+ * Serialization is taken care of in namespace.c
+ */
+static int follow_managed(struct path *path, struct nameidata *nd)
+{
+ struct vfsmount *mnt = path->mnt; /* held by caller, must be left alone */
+ unsigned managed;
+ bool need_mntput = false;
+ int ret = 0;
+
+ /* Given that we're not holding a lock here, we retain the value in a
+ * local variable for each dentry as we look at it so that we don't see
+ * the components of that value change under us */
+ while (managed = ACCESS_ONCE(path->dentry->d_flags),
+ managed &= DCACHE_MANAGED_DENTRY,
+ unlikely(managed != 0)) {
+ /* Allow the filesystem to manage the transit without i_mutex
+ * being held. */
+ if (managed & DCACHE_MANAGE_TRANSIT) {
+ BUG_ON(!path->dentry->d_op);
+ BUG_ON(!path->dentry->d_op->d_manage);
+ ret = path->dentry->d_op->d_manage(path, false);
+ if (ret < 0)
+ break;
+ }
+
+ /* Transit to a mounted filesystem. */
+ if (managed & DCACHE_MOUNTED) {
+ struct vfsmount *mounted = lookup_mnt(path);
+ if (mounted) {
+ dput(path->dentry);
+ if (need_mntput)
+ mntput(path->mnt);
+ path->mnt = mounted;
+ path->dentry = dget(mounted->mnt_root);
+ need_mntput = true;
+ continue;
+ }
+
+ /* Something is mounted on this dentry in another
+ * namespace and/or whatever was mounted there in this
+ * namespace got unmounted before lookup_mnt() could
+ * get it */
+ }
+
+ /* Handle an automount point */
+ if (managed & DCACHE_NEED_AUTOMOUNT) {
+ ret = follow_automount(path, nd, &need_mntput);
+ if (ret < 0)
+ break;
+ continue;
+ }
+
+ /* We didn't change the current path point */
+ break;
+ }
+
+ if (need_mntput && path->mnt == mnt)
+ mntput(path->mnt);
+ if (ret == -EISDIR || !ret)
+ ret = 1;
+ if (need_mntput)
+ nd->flags |= LOOKUP_JUMPED;
+ if (unlikely(ret < 0))
+ path_put_conditional(path, nd);
+ return ret;
+}
+
+int follow_down_one(struct path *path)
+{
+ struct vfsmount *mounted;
+
+ mounted = lookup_mnt(path);
+ if (mounted) {
+ dput(path->dentry);
+ mntput(path->mnt);
+ path->mnt = mounted;
+ path->dentry = dget(mounted->mnt_root);
+ return 1;
+ }
+ return 0;
+}
+EXPORT_SYMBOL(follow_down_one);
+
+static inline int managed_dentry_rcu(const struct path *path)
+{
+ return (path->dentry->d_flags & DCACHE_MANAGE_TRANSIT) ?
+ path->dentry->d_op->d_manage(path, true) : 0;
+}
+
+/*
+ * Try to skip to top of mountpoint pile in rcuwalk mode. Fail if
+ * we meet a managed dentry that would need blocking.
+ */
+static bool __follow_mount_rcu(struct nameidata *nd, struct path *path,
+ struct inode **inode, unsigned *seqp)
+{
+ for (;;) {
+ struct mount *mounted;
+ /*
+ * Don't forget we might have a non-mountpoint managed dentry
+ * that wants to block transit.
+ */
+ switch (managed_dentry_rcu(path)) {
+ case -ECHILD:
+ default:
+ return false;
+ case -EISDIR:
+ return true;
+ case 0:
+ break;
+ }
+
+ if (!d_mountpoint(path->dentry))
+ return !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT);
+
+ mounted = __lookup_mnt(path->mnt, path->dentry);
+ if (!mounted)
+ break;
+ path->mnt = &mounted->mnt;
+ path->dentry = mounted->mnt.mnt_root;
+ nd->flags |= LOOKUP_JUMPED;
+ *seqp = read_seqcount_begin(&path->dentry->d_seq);
+ /*
+ * Update the inode too. We don't need to re-check the
+ * dentry sequence number here after this d_inode read,
+ * because a mount-point is always pinned.
+ */
+ *inode = path->dentry->d_inode;
+ }
+ return !read_seqretry(&mount_lock, nd->m_seq) &&
+ !(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT);
+}
+
+static int follow_dotdot_rcu(struct nameidata *nd)
+{
+ struct inode *inode = nd->inode;
+
+ while (1) {
+ if (path_equal(&nd->path, &nd->root))
+ break;
+ if (nd->path.dentry != nd->path.mnt->mnt_root) {
+ struct dentry *old = nd->path.dentry;
+ struct dentry *parent = old->d_parent;
+ unsigned seq;
+
+ inode = parent->d_inode;
+ seq = read_seqcount_begin(&parent->d_seq);
+ if (unlikely(read_seqcount_retry(&old->d_seq, nd->seq)))
+ return -ECHILD;
+ nd->path.dentry = parent;
+ nd->seq = seq;
+ if (unlikely(!path_connected(&nd->path)))
+ return -ECHILD;
+ break;
+ } else {
+ struct mount *mnt = real_mount(nd->path.mnt);
+ struct mount *mparent = mnt->mnt_parent;
+ struct dentry *mountpoint = mnt->mnt_mountpoint;
+ struct inode *inode2 = mountpoint->d_inode;
+ unsigned seq = read_seqcount_begin(&mountpoint->d_seq);
+ if (unlikely(read_seqretry(&mount_lock, nd->m_seq)))
+ return -ECHILD;
+ if (&mparent->mnt == nd->path.mnt)
+ break;
+ /* we know that mountpoint was pinned */
+ nd->path.dentry = mountpoint;
+ nd->path.mnt = &mparent->mnt;
+ inode = inode2;
+ nd->seq = seq;
+ }
+ }
+ while (unlikely(d_mountpoint(nd->path.dentry))) {
+ struct mount *mounted;
+ mounted = __lookup_mnt(nd->path.mnt, nd->path.dentry);
+ if (unlikely(read_seqretry(&mount_lock, nd->m_seq)))
+ return -ECHILD;
+ if (!mounted)
+ break;
+ nd->path.mnt = &mounted->mnt;
+ nd->path.dentry = mounted->mnt.mnt_root;
+ inode = nd->path.dentry->d_inode;
+ nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq);
+ }
+ nd->inode = inode;
+ return 0;
+}
+
+/*
+ * Follow down to the covering mount currently visible to userspace. At each
+ * point, the filesystem owning that dentry may be queried as to whether the
+ * caller is permitted to proceed or not.
+ */
+int follow_down(struct path *path)
+{
+ unsigned managed;
+ int ret;
+
+ while (managed = ACCESS_ONCE(path->dentry->d_flags),
+ unlikely(managed & DCACHE_MANAGED_DENTRY)) {
+ /* Allow the filesystem to manage the transit without i_mutex
+ * being held.
+ *
+ * We indicate to the filesystem if someone is trying to mount
+ * something here. This gives autofs the chance to deny anyone
+ * other than its daemon the right to mount on its
+ * superstructure.
+ *
+ * The filesystem may sleep at this point.
+ */
+ if (managed & DCACHE_MANAGE_TRANSIT) {
+ BUG_ON(!path->dentry->d_op);
+ BUG_ON(!path->dentry->d_op->d_manage);
+ ret = path->dentry->d_op->d_manage(path, false);
+ if (ret < 0)
+ return ret == -EISDIR ? 0 : ret;
+ }
+
+ /* Transit to a mounted filesystem. */
+ if (managed & DCACHE_MOUNTED) {
+ struct vfsmount *mounted = lookup_mnt(path);
+ if (!mounted)
+ break;
+ dput(path->dentry);
+ mntput(path->mnt);
+ path->mnt = mounted;
+ path->dentry = dget(mounted->mnt_root);
+ continue;
+ }
+
+ /* Don't handle automount points here */
+ break;
+ }
+ return 0;
+}
+EXPORT_SYMBOL(follow_down);
+
+/*
+ * Skip to top of mountpoint pile in refwalk mode for follow_dotdot()
+ */
+static void follow_mount(struct path *path)
+{
+ while (d_mountpoint(path->dentry)) {
+ struct vfsmount *mounted = lookup_mnt(path);
+ if (!mounted)
+ break;
+ dput(path->dentry);
+ mntput(path->mnt);
+ path->mnt = mounted;
+ path->dentry = dget(mounted->mnt_root);
+ }
+}
+
+static int path_parent_directory(struct path *path)
+{
+ struct dentry *old = path->dentry;
+ /* rare case of legitimate dget_parent()... */
+ path->dentry = dget_parent(path->dentry);
+ dput(old);
+ if (unlikely(!path_connected(path)))
+ return -ENOENT;
+ return 0;
+}
+
+static int follow_dotdot(struct nameidata *nd)
+{
+ while(1) {
+ if (nd->path.dentry == nd->root.dentry &&
+ nd->path.mnt == nd->root.mnt) {
+ break;
+ }
+ if (nd->path.dentry != nd->path.mnt->mnt_root) {
+ int ret = path_parent_directory(&nd->path);
+ if (ret)
+ return ret;
+ break;
+ }
+ if (!follow_up(&nd->path))
+ break;
+ }
+ follow_mount(&nd->path);
+ nd->inode = nd->path.dentry->d_inode;
+ return 0;
+}
+
+/*
+ * This looks up the name in dcache and possibly revalidates the found dentry.
+ * NULL is returned if the dentry does not exist in the cache.
+ */
+static struct dentry *lookup_dcache(const struct qstr *name,
+ struct dentry *dir,
+ unsigned int flags)
+{
+ struct dentry *dentry = d_lookup(dir, name);
+ if (dentry) {
+ int error = d_revalidate(dentry, flags);
+ if (unlikely(error <= 0)) {
+ if (!error)
+ d_invalidate(dentry);
+ dput(dentry);
+ return ERR_PTR(error);
+ }
+ }
+ return dentry;
+}
+
+/*
+ * Call i_op->lookup on the dentry. The dentry must be negative and
+ * unhashed.
+ *
+ * dir->d_inode->i_mutex must be held
+ */
+static struct dentry *lookup_real(struct inode *dir, struct dentry *dentry,
+ unsigned int flags)
+{
+ struct dentry *old;
+
+ /* Don't create child dentry for a dead directory. */
+ if (unlikely(IS_DEADDIR(dir))) {
+ dput(dentry);
+ return ERR_PTR(-ENOENT);
+ }
+
+ old = dir->i_op->lookup(dir, dentry, flags);
+ if (unlikely(old)) {
+ dput(dentry);
+ dentry = old;
+ }
+ return dentry;
+}
+
+static struct dentry *__lookup_hash(const struct qstr *name,
+ struct dentry *base, unsigned int flags)
+{
+ struct dentry *dentry = lookup_dcache(name, base, flags);
+
+ if (dentry)
+ return dentry;
+
+ dentry = d_alloc(base, name);
+ if (unlikely(!dentry))
+ return ERR_PTR(-ENOMEM);
+
+ return lookup_real(base->d_inode, dentry, flags);
+}
+
+static int lookup_fast(struct nameidata *nd,
+ struct path *path, struct inode **inode,
+ unsigned *seqp)
+{
+ struct vfsmount *mnt = nd->path.mnt;
+ struct dentry *dentry, *parent = nd->path.dentry;
+ int status = 1;
+ int err;
+
+ /*
+ * Rename seqlock is not required here because in the off chance
+ * of a false negative due to a concurrent rename, the caller is
+ * going to fall back to non-racy lookup.
+ */
+ if (nd->flags & LOOKUP_RCU) {
+ unsigned seq;
+ bool negative;
+ dentry = __d_lookup_rcu(parent, &nd->last, &seq);
+ if (unlikely(!dentry)) {
+ if (unlazy_walk(nd))
+ return -ECHILD;
+ return 0;
+ }
+
+ /*
+ * This sequence count validates that the inode matches
+ * the dentry name information from lookup.
+ */
+ *inode = d_backing_inode(dentry);
+ negative = d_is_negative(dentry);
+ if (unlikely(read_seqcount_retry(&dentry->d_seq, seq)))
+ return -ECHILD;
+
+ /*
+ * This sequence count validates that the parent had no
+ * changes while we did the lookup of the dentry above.
+ *
+ * The memory barrier in read_seqcount_begin of child is
+ * enough, we can use __read_seqcount_retry here.
+ */
+ if (unlikely(__read_seqcount_retry(&parent->d_seq, nd->seq)))
+ return -ECHILD;
+
+ *seqp = seq;
+ status = d_revalidate(dentry, nd->flags);
+ if (likely(status > 0)) {
+ /*
+ * Note: do negative dentry check after revalidation in
+ * case that drops it.
+ */
+ if (unlikely(negative))
+ return -ENOENT;
+ path->mnt = mnt;
+ path->dentry = dentry;
+ if (likely(__follow_mount_rcu(nd, path, inode, seqp)))
+ return 1;
+ }
+ if (unlazy_child(nd, dentry, seq))
+ return -ECHILD;
+ if (unlikely(status == -ECHILD))
+ /* we'd been told to redo it in non-rcu mode */
+ status = d_revalidate(dentry, nd->flags);
+ } else {
+ dentry = __d_lookup(parent, &nd->last);
+ if (unlikely(!dentry))
+ return 0;
+ status = d_revalidate(dentry, nd->flags);
+ }
+ if (unlikely(status <= 0)) {
+ if (!status)
+ d_invalidate(dentry);
+ dput(dentry);
+ return status;
+ }
+ if (unlikely(d_is_negative(dentry))) {
+ dput(dentry);
+ return -ENOENT;
+ }
+
+ path->mnt = mnt;
+ path->dentry = dentry;
+ err = follow_managed(path, nd);
+ if (likely(err > 0))
+ *inode = d_backing_inode(path->dentry);
+ return err;
+}
+
+/* Fast lookup failed, do it the slow way */
+static struct dentry *lookup_slow(const struct qstr *name,
+ struct dentry *dir,
+ unsigned int flags)
+{
+ struct dentry *dentry = ERR_PTR(-ENOENT), *old;
+ struct inode *inode = dir->d_inode;
+ DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq);
+
+ inode_lock_shared(inode);
+ /* Don't go there if it's already dead */
+ if (unlikely(IS_DEADDIR(inode)))
+ goto out;
+again:
+ dentry = d_alloc_parallel(dir, name, &wq);
+ if (IS_ERR(dentry))
+ goto out;
+ if (unlikely(!d_in_lookup(dentry))) {
+ if (!(flags & LOOKUP_NO_REVAL)) {
+ int error = d_revalidate(dentry, flags);
+ if (unlikely(error <= 0)) {
+ if (!error) {
+ d_invalidate(dentry);
+ dput(dentry);
+ goto again;
+ }
+ dput(dentry);
+ dentry = ERR_PTR(error);
+ }
+ }
+ } else {
+ old = inode->i_op->lookup(inode, dentry, flags);
+ d_lookup_done(dentry);
+ if (unlikely(old)) {
+ dput(dentry);
+ dentry = old;
+ }
+ }
+out:
+ inode_unlock_shared(inode);
+ return dentry;
+}
+
+static inline int may_lookup(struct nameidata *nd)
+{
+ if (nd->flags & LOOKUP_RCU) {
+ int err = inode_permission2(nd->path.mnt, nd->inode, MAY_EXEC|MAY_NOT_BLOCK);
+ if (err != -ECHILD)
+ return err;
+ if (unlazy_walk(nd))
+ return -ECHILD;
+ }
+ return inode_permission2(nd->path.mnt, nd->inode, MAY_EXEC);
+}
+
+static inline int handle_dots(struct nameidata *nd, int type)
+{
+ if (type == LAST_DOTDOT) {
+ if (!nd->root.mnt)
+ set_root(nd);
+ if (nd->flags & LOOKUP_RCU) {
+ return follow_dotdot_rcu(nd);
+ } else
+ return follow_dotdot(nd);
+ }
+ return 0;
+}
+
+static int pick_link(struct nameidata *nd, struct path *link,
+ struct inode *inode, unsigned seq)
+{
+ int error;
+ struct saved *last;
+ if (unlikely(nd->total_link_count++ >= MAXSYMLINKS)) {
+ path_to_nameidata(link, nd);
+ return -ELOOP;
+ }
+ if (!(nd->flags & LOOKUP_RCU)) {
+ if (link->mnt == nd->path.mnt)
+ mntget(link->mnt);
+ }
+ error = nd_alloc_stack(nd);
+ if (unlikely(error)) {
+ if (error == -ECHILD) {
+ if (unlikely(!legitimize_path(nd, link, seq))) {
+ drop_links(nd);
+ nd->depth = 0;
+ nd->flags &= ~LOOKUP_RCU;
+ nd->path.mnt = NULL;
+ nd->path.dentry = NULL;
+ if (!(nd->flags & LOOKUP_ROOT))
+ nd->root.mnt = NULL;
+ rcu_read_unlock();
+ } else if (likely(unlazy_walk(nd)) == 0)
+ error = nd_alloc_stack(nd);
+ }
+ if (error) {
+ path_put(link);
+ return error;
+ }
+ }
+
+ last = nd->stack + nd->depth++;
+ last->link = *link;
+ clear_delayed_call(&last->done);
+ nd->link_inode = inode;
+ last->seq = seq;
+ return 1;
+}
+
+enum {WALK_FOLLOW = 1, WALK_MORE = 2};
+
+/*
+ * Do we need to follow links? We _really_ want to be able
+ * to do this check without having to look at inode->i_op,
+ * so we keep a cache of "no, this doesn't need follow_link"
+ * for the common case.
+ */
+static inline int step_into(struct nameidata *nd, struct path *path,
+ int flags, struct inode *inode, unsigned seq)
+{
+ if (!(flags & WALK_MORE) && nd->depth)
+ put_link(nd);
+ if (likely(!d_is_symlink(path->dentry)) ||
+ !(flags & WALK_FOLLOW || nd->flags & LOOKUP_FOLLOW)) {
+ /* not a symlink or should not follow */
+ path_to_nameidata(path, nd);
+ nd->inode = inode;
+ nd->seq = seq;
+ return 0;
+ }
+ /* make sure that d_is_symlink above matches inode */
+ if (nd->flags & LOOKUP_RCU) {
+ if (read_seqcount_retry(&path->dentry->d_seq, seq))
+ return -ECHILD;
+ }
+ return pick_link(nd, path, inode, seq);
+}
+
+static int walk_component(struct nameidata *nd, int flags)
+{
+ struct path path;
+ struct inode *inode;
+ unsigned seq;
+ int err;
+ /*
+ * "." and ".." are special - ".." especially so because it has
+ * to be able to know about the current root directory and
+ * parent relationships.
+ */
+ if (unlikely(nd->last_type != LAST_NORM)) {
+ err = handle_dots(nd, nd->last_type);
+ if (!(flags & WALK_MORE) && nd->depth)
+ put_link(nd);
+ return err;
+ }
+ err = lookup_fast(nd, &path, &inode, &seq);
+ if (unlikely(err <= 0)) {
+ if (err < 0)
+ return err;
+ path.dentry = lookup_slow(&nd->last, nd->path.dentry,
+ nd->flags);
+ if (IS_ERR(path.dentry))
+ return PTR_ERR(path.dentry);
+
+ path.mnt = nd->path.mnt;
+ err = follow_managed(&path, nd);
+ if (unlikely(err < 0))
+ return err;
+
+ if (unlikely(d_is_negative(path.dentry))) {
+ path_to_nameidata(&path, nd);
+ return -ENOENT;
+ }
+
+ seq = 0; /* we are already out of RCU mode */
+ inode = d_backing_inode(path.dentry);
+ }
+
+ return step_into(nd, &path, flags, inode, seq);
+}
+
+/*
+ * We can do the critical dentry name comparison and hashing
+ * operations one word at a time, but we are limited to:
+ *
+ * - Architectures with fast unaligned word accesses. We could
+ * do a "get_unaligned()" if this helps and is sufficiently
+ * fast.
+ *
+ * - non-CONFIG_DEBUG_PAGEALLOC configurations (so that we
+ * do not trap on the (extremely unlikely) case of a page
+ * crossing operation.
+ *
+ * - Furthermore, we need an efficient 64-bit compile for the
+ * 64-bit case in order to generate the "number of bytes in
+ * the final mask". Again, that could be replaced with a
+ * efficient population count instruction or similar.
+ */
+#ifdef CONFIG_DCACHE_WORD_ACCESS
+
+#include <asm/word-at-a-time.h>
+
+#ifdef HASH_MIX
+
+/* Architecture provides HASH_MIX and fold_hash() in <asm/hash.h> */
+
+#elif defined(CONFIG_64BIT)
+/*
+ * Register pressure in the mixing function is an issue, particularly
+ * on 32-bit x86, but almost any function requires one state value and
+ * one temporary. Instead, use a function designed for two state values
+ * and no temporaries.
+ *
+ * This function cannot create a collision in only two iterations, so
+ * we have two iterations to achieve avalanche. In those two iterations,
+ * we have six layers of mixing, which is enough to spread one bit's
+ * influence out to 2^6 = 64 state bits.
+ *
+ * Rotate constants are scored by considering either 64 one-bit input
+ * deltas or 64*63/2 = 2016 two-bit input deltas, and finding the
+ * probability of that delta causing a change to each of the 128 output
+ * bits, using a sample of random initial states.
+ *
+ * The Shannon entropy of the computed probabilities is then summed
+ * to produce a score. Ideally, any input change has a 50% chance of
+ * toggling any given output bit.
+ *
+ * Mixing scores (in bits) for (12,45):
+ * Input delta: 1-bit 2-bit
+ * 1 round: 713.3 42542.6
+ * 2 rounds: 2753.7 140389.8
+ * 3 rounds: 5954.1 233458.2
+ * 4 rounds: 7862.6 256672.2
+ * Perfect: 8192 258048
+ * (64*128) (64*63/2 * 128)
+ */
+#define HASH_MIX(x, y, a) \
+ ( x ^= (a), \
+ y ^= x, x = rol64(x,12),\
+ x += y, y = rol64(y,45),\
+ y *= 9 )
+
+/*
+ * Fold two longs into one 32-bit hash value. This must be fast, but
+ * latency isn't quite as critical, as there is a fair bit of additional
+ * work done before the hash value is used.
+ */
+static inline unsigned int fold_hash(unsigned long x, unsigned long y)
+{
+ y ^= x * GOLDEN_RATIO_64;
+ y *= GOLDEN_RATIO_64;
+ return y >> 32;
+}
+
+#else /* 32-bit case */
+
+/*
+ * Mixing scores (in bits) for (7,20):
+ * Input delta: 1-bit 2-bit
+ * 1 round: 330.3 9201.6
+ * 2 rounds: 1246.4 25475.4
+ * 3 rounds: 1907.1 31295.1
+ * 4 rounds: 2042.3 31718.6
+ * Perfect: 2048 31744
+ * (32*64) (32*31/2 * 64)
+ */
+#define HASH_MIX(x, y, a) \
+ ( x ^= (a), \
+ y ^= x, x = rol32(x, 7),\
+ x += y, y = rol32(y,20),\
+ y *= 9 )
+
+static inline unsigned int fold_hash(unsigned long x, unsigned long y)
+{
+ /* Use arch-optimized multiply if one exists */
+ return __hash_32(y ^ __hash_32(x));
+}
+
+#endif
+
+/*
+ * Return the hash of a string of known length. This is carfully
+ * designed to match hash_name(), which is the more critical function.
+ * In particular, we must end by hashing a final word containing 0..7
+ * payload bytes, to match the way that hash_name() iterates until it
+ * finds the delimiter after the name.
+ */
+unsigned int full_name_hash(const void *salt, const char *name, unsigned int len)
+{
+ unsigned long a, x = 0, y = (unsigned long)salt;
+
+ for (;;) {
+ if (!len)
+ goto done;
+ a = load_unaligned_zeropad(name);
+ if (len < sizeof(unsigned long))
+ break;
+ HASH_MIX(x, y, a);
+ name += sizeof(unsigned long);
+ len -= sizeof(unsigned long);
+ }
+ x ^= a & bytemask_from_count(len);
+done:
+ return fold_hash(x, y);
+}
+EXPORT_SYMBOL(full_name_hash);
+
+/* Return the "hash_len" (hash and length) of a null-terminated string */
+u64 hashlen_string(const void *salt, const char *name)
+{
+ unsigned long a = 0, x = 0, y = (unsigned long)salt;
+ unsigned long adata, mask, len;
+ const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS;
+
+ len = 0;
+ goto inside;
+
+ do {
+ HASH_MIX(x, y, a);
+ len += sizeof(unsigned long);
+inside:
+ a = load_unaligned_zeropad(name+len);
+ } while (!has_zero(a, &adata, &constants));
+
+ adata = prep_zero_mask(a, adata, &constants);
+ mask = create_zero_mask(adata);
+ x ^= a & zero_bytemask(mask);
+
+ return hashlen_create(fold_hash(x, y), len + find_zero(mask));
+}
+EXPORT_SYMBOL(hashlen_string);
+
+/*
+ * Calculate the length and hash of the path component, and
+ * return the "hash_len" as the result.
+ */
+static inline u64 hash_name(const void *salt, const char *name)
+{
+ unsigned long a = 0, b, x = 0, y = (unsigned long)salt;
+ unsigned long adata, bdata, mask, len;
+ const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS;
+
+ len = 0;
+ goto inside;
+
+ do {
+ HASH_MIX(x, y, a);
+ len += sizeof(unsigned long);
+inside:
+ a = load_unaligned_zeropad(name+len);
+ b = a ^ REPEAT_BYTE('/');
+ } while (!(has_zero(a, &adata, &constants) | has_zero(b, &bdata, &constants)));
+
+ adata = prep_zero_mask(a, adata, &constants);
+ bdata = prep_zero_mask(b, bdata, &constants);
+ mask = create_zero_mask(adata | bdata);
+ x ^= a & zero_bytemask(mask);
+
+ return hashlen_create(fold_hash(x, y), len + find_zero(mask));
+}
+
+#else /* !CONFIG_DCACHE_WORD_ACCESS: Slow, byte-at-a-time version */
+
+/* Return the hash of a string of known length */
+unsigned int full_name_hash(const void *salt, const char *name, unsigned int len)
+{
+ unsigned long hash = init_name_hash(salt);
+ while (len--)
+ hash = partial_name_hash((unsigned char)*name++, hash);
+ return end_name_hash(hash);
+}
+EXPORT_SYMBOL(full_name_hash);
+
+/* Return the "hash_len" (hash and length) of a null-terminated string */
+u64 hashlen_string(const void *salt, const char *name)
+{
+ unsigned long hash = init_name_hash(salt);
+ unsigned long len = 0, c;
+
+ c = (unsigned char)*name;
+ while (c) {
+ len++;
+ hash = partial_name_hash(c, hash);
+ c = (unsigned char)name[len];
+ }
+ return hashlen_create(end_name_hash(hash), len);
+}
+EXPORT_SYMBOL(hashlen_string);
+
+/*
+ * We know there's a real path component here of at least
+ * one character.
+ */
+static inline u64 hash_name(const void *salt, const char *name)
+{
+ unsigned long hash = init_name_hash(salt);
+ unsigned long len = 0, c;
+
+ c = (unsigned char)*name;
+ do {
+ len++;
+ hash = partial_name_hash(c, hash);
+ c = (unsigned char)name[len];
+ } while (c && c != '/');
+ return hashlen_create(end_name_hash(hash), len);
+}
+
+#endif
+
+/*
+ * Name resolution.
+ * This is the basic name resolution function, turning a pathname into
+ * the final dentry. We expect 'base' to be positive and a directory.
+ *
+ * Returns 0 and nd will have valid dentry and mnt on success.
+ * Returns error and drops reference to input namei data on failure.
+ */
+static int link_path_walk(const char *name, struct nameidata *nd)
+{
+ int err;
+
+ while (*name=='/')
+ name++;
+ if (!*name)
+ return 0;
+
+ /* At this point we know we have a real path component. */
+ for(;;) {
+ u64 hash_len;
+ int type;
+
+ err = may_lookup(nd);
+ if (err)
+ return err;
+
+ hash_len = hash_name(nd->path.dentry, name);
+
+ type = LAST_NORM;
+ if (name[0] == '.') switch (hashlen_len(hash_len)) {
+ case 2:
+ if (name[1] == '.') {
+ type = LAST_DOTDOT;
+ nd->flags |= LOOKUP_JUMPED;
+ }
+ break;
+ case 1:
+ type = LAST_DOT;
+ }
+ if (likely(type == LAST_NORM)) {
+ struct dentry *parent = nd->path.dentry;
+ nd->flags &= ~LOOKUP_JUMPED;
+ if (unlikely(parent->d_flags & DCACHE_OP_HASH)) {
+ struct qstr this = { { .hash_len = hash_len }, .name = name };
+ err = parent->d_op->d_hash(parent, &this);
+ if (err < 0)
+ return err;
+ hash_len = this.hash_len;
+ name = this.name;
+ }
+ }
+
+ nd->last.hash_len = hash_len;
+ nd->last.name = name;
+ nd->last_type = type;
+
+ name += hashlen_len(hash_len);
+ if (!*name)
+ goto OK;
+ /*
+ * If it wasn't NUL, we know it was '/'. Skip that
+ * slash, and continue until no more slashes.
+ */
+ do {
+ name++;
+ } while (unlikely(*name == '/'));
+ if (unlikely(!*name)) {
+OK:
+ /* pathname body, done */
+ if (!nd->depth)
+ return 0;
+ name = nd->stack[nd->depth - 1].name;
+ /* trailing symlink, done */
+ if (!name)
+ return 0;
+ /* last component of nested symlink */
+ err = walk_component(nd, WALK_FOLLOW);
+ } else {
+ /* not the last component */
+ err = walk_component(nd, WALK_FOLLOW | WALK_MORE);
+ }
+ if (err < 0)
+ return err;
+
+ if (err) {
+ const char *s = get_link(nd);
+
+ if (IS_ERR(s))
+ return PTR_ERR(s);
+ err = 0;
+ if (unlikely(!s)) {
+ /* jumped */
+ put_link(nd);
+ } else {
+ nd->stack[nd->depth - 1].name = name;
+ name = s;
+ continue;
+ }
+ }
+ if (unlikely(!d_can_lookup(nd->path.dentry))) {
+ if (nd->flags & LOOKUP_RCU) {
+ if (unlazy_walk(nd))
+ return -ECHILD;
+ }
+ return -ENOTDIR;
+ }
+ }
+}
+
+static const char *path_init(struct nameidata *nd, unsigned flags)
+{
+ const char *s = nd->name->name;
+
+ if (!*s)
+ flags &= ~LOOKUP_RCU;
+
+ nd->last_type = LAST_ROOT; /* if there are only slashes... */
+ nd->flags = flags | LOOKUP_JUMPED | LOOKUP_PARENT;
+ nd->depth = 0;
+ if (flags & LOOKUP_ROOT) {
+ struct dentry *root = nd->root.dentry;
+ struct inode *inode = root->d_inode;
+ if (*s && unlikely(!d_can_lookup(root)))
+ return ERR_PTR(-ENOTDIR);
+ nd->path = nd->root;
+ nd->inode = inode;
+ if (flags & LOOKUP_RCU) {
+ rcu_read_lock();
+ nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq);
+ nd->root_seq = nd->seq;
+ nd->m_seq = read_seqbegin(&mount_lock);
+ } else {
+ path_get(&nd->path);
+ }
+ return s;
+ }
+
+ nd->root.mnt = NULL;
+ nd->path.mnt = NULL;
+ nd->path.dentry = NULL;
+
+ nd->m_seq = read_seqbegin(&mount_lock);
+ if (*s == '/') {
+ if (flags & LOOKUP_RCU)
+ rcu_read_lock();
+ set_root(nd);
+ if (likely(!nd_jump_root(nd)))
+ return s;
+ nd->root.mnt = NULL;
+ rcu_read_unlock();
+ return ERR_PTR(-ECHILD);
+ } else if (nd->dfd == AT_FDCWD) {
+ if (flags & LOOKUP_RCU) {
+ struct fs_struct *fs = current->fs;
+ unsigned seq;
+
+ rcu_read_lock();
+
+ do {
+ seq = read_seqcount_begin(&fs->seq);
+ nd->path = fs->pwd;
+ nd->inode = nd->path.dentry->d_inode;
+ nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq);
+ } while (read_seqcount_retry(&fs->seq, seq));
+ } else {
+ get_fs_pwd(current->fs, &nd->path);
+ nd->inode = nd->path.dentry->d_inode;
+ }
+ return s;
+ } else {
+ /* Caller must check execute permissions on the starting path component */
+ struct fd f = fdget_raw(nd->dfd);
+ struct dentry *dentry;
+
+ if (!f.file)
+ return ERR_PTR(-EBADF);
+
+ dentry = f.file->f_path.dentry;
+
+ if (*s) {
+ if (!d_can_lookup(dentry)) {
+ fdput(f);
+ return ERR_PTR(-ENOTDIR);
+ }
+ }
+
+ nd->path = f.file->f_path;
+ if (flags & LOOKUP_RCU) {
+ rcu_read_lock();
+ nd->inode = nd->path.dentry->d_inode;
+ nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq);
+ } else {
+ path_get(&nd->path);
+ nd->inode = nd->path.dentry->d_inode;
+ }
+ fdput(f);
+ return s;
+ }
+}
+
+static const char *trailing_symlink(struct nameidata *nd)
+{
+ const char *s;
+ int error = may_follow_link(nd);
+ if (unlikely(error))
+ return ERR_PTR(error);
+ nd->flags |= LOOKUP_PARENT;
+ nd->stack[0].name = NULL;
+ s = get_link(nd);
+ return s ? s : "";
+}
+
+static inline int lookup_last(struct nameidata *nd)
+{
+ if (nd->last_type == LAST_NORM && nd->last.name[nd->last.len])
+ nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
+
+ nd->flags &= ~LOOKUP_PARENT;
+ return walk_component(nd, 0);
+}
+
+static int handle_lookup_down(struct nameidata *nd)
+{
+ struct path path = nd->path;
+ struct inode *inode = nd->inode;
+ unsigned seq = nd->seq;
+ int err;
+
+ if (nd->flags & LOOKUP_RCU) {
+ /*
+ * don't bother with unlazy_walk on failure - we are
+ * at the very beginning of walk, so we lose nothing
+ * if we simply redo everything in non-RCU mode
+ */
+ if (unlikely(!__follow_mount_rcu(nd, &path, &inode, &seq)))
+ return -ECHILD;
+ } else {
+ dget(path.dentry);
+ err = follow_managed(&path, nd);
+ if (unlikely(err < 0))
+ return err;
+ inode = d_backing_inode(path.dentry);
+ seq = 0;
+ }
+ path_to_nameidata(&path, nd);
+ nd->inode = inode;
+ nd->seq = seq;
+ return 0;
+}
+
+/* Returns 0 and nd will be valid on success; Retuns error, otherwise. */
+static int path_lookupat(struct nameidata *nd, unsigned flags, struct path *path)
+{
+ const char *s = path_init(nd, flags);
+ int err;
+
+ if (IS_ERR(s))
+ return PTR_ERR(s);
+
+ if (unlikely(flags & LOOKUP_DOWN)) {
+ err = handle_lookup_down(nd);
+ if (unlikely(err < 0)) {
+ terminate_walk(nd);
+ return err;
+ }
+ }
+
+ while (!(err = link_path_walk(s, nd))
+ && ((err = lookup_last(nd)) > 0)) {
+ s = trailing_symlink(nd);
+ if (IS_ERR(s)) {
+ err = PTR_ERR(s);
+ break;
+ }
+ }
+ if (!err)
+ err = complete_walk(nd);
+
+ if (!err && nd->flags & LOOKUP_DIRECTORY)
+ if (!d_can_lookup(nd->path.dentry))
+ err = -ENOTDIR;
+ if (!err) {
+ *path = nd->path;
+ nd->path.mnt = NULL;
+ nd->path.dentry = NULL;
+ }
+ terminate_walk(nd);
+ return err;
+}
+
+static int filename_lookup(int dfd, struct filename *name, unsigned flags,
+ struct path *path, struct path *root)
+{
+ int retval;
+ struct nameidata nd;
+ if (IS_ERR(name))
+ return PTR_ERR(name);
+ if (unlikely(root)) {
+ nd.root = *root;
+ flags |= LOOKUP_ROOT;
+ }
+ set_nameidata(&nd, dfd, name);
+ retval = path_lookupat(&nd, flags | LOOKUP_RCU, path);
+ if (unlikely(retval == -ECHILD))
+ retval = path_lookupat(&nd, flags, path);
+ if (unlikely(retval == -ESTALE))
+ retval = path_lookupat(&nd, flags | LOOKUP_REVAL, path);
+
+ if (likely(!retval))
+ audit_inode(name, path->dentry, flags & LOOKUP_PARENT);
+ restore_nameidata();
+ putname(name);
+ return retval;
+}
+
+/* Returns 0 and nd will be valid on success; Retuns error, otherwise. */
+static int path_parentat(struct nameidata *nd, unsigned flags,
+ struct path *parent)
+{
+ const char *s = path_init(nd, flags);
+ int err;
+ if (IS_ERR(s))
+ return PTR_ERR(s);
+ err = link_path_walk(s, nd);
+ if (!err)
+ err = complete_walk(nd);
+ if (!err) {
+ *parent = nd->path;
+ nd->path.mnt = NULL;
+ nd->path.dentry = NULL;
+ }
+ terminate_walk(nd);
+ return err;
+}
+
+static struct filename *filename_parentat(int dfd, struct filename *name,
+ unsigned int flags, struct path *parent,
+ struct qstr *last, int *type)
+{
+ int retval;
+ struct nameidata nd;
+
+ if (IS_ERR(name))
+ return name;
+ set_nameidata(&nd, dfd, name);
+ retval = path_parentat(&nd, flags | LOOKUP_RCU, parent);
+ if (unlikely(retval == -ECHILD))
+ retval = path_parentat(&nd, flags, parent);
+ if (unlikely(retval == -ESTALE))
+ retval = path_parentat(&nd, flags | LOOKUP_REVAL, parent);
+ if (likely(!retval)) {
+ *last = nd.last;
+ *type = nd.last_type;
+ audit_inode(name, parent->dentry, LOOKUP_PARENT);
+ } else {
+ putname(name);
+ name = ERR_PTR(retval);
+ }
+ restore_nameidata();
+ return name;
+}
+
+/* does lookup, returns the object with parent locked */
+struct dentry *kern_path_locked(const char *name, struct path *path)
+{
+ struct filename *filename;
+ struct dentry *d;
+ struct qstr last;
+ int type;
+
+ filename = filename_parentat(AT_FDCWD, getname_kernel(name), 0, path,
+ &last, &type);
+ if (IS_ERR(filename))
+ return ERR_CAST(filename);
+ if (unlikely(type != LAST_NORM)) {
+ path_put(path);
+ putname(filename);
+ return ERR_PTR(-EINVAL);
+ }
+ inode_lock_nested(path->dentry->d_inode, I_MUTEX_PARENT);
+ d = __lookup_hash(&last, path->dentry, 0);
+ if (IS_ERR(d)) {
+ inode_unlock(path->dentry->d_inode);
+ path_put(path);
+ }
+ putname(filename);
+ return d;
+}
+
+int kern_path(const char *name, unsigned int flags, struct path *path)
+{
+ return filename_lookup(AT_FDCWD, getname_kernel(name),
+ flags, path, NULL);
+}
+EXPORT_SYMBOL(kern_path);
+
+/**
+ * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair
+ * @dentry: pointer to dentry of the base directory
+ * @mnt: pointer to vfs mount of the base directory
+ * @name: pointer to file name
+ * @flags: lookup flags
+ * @path: pointer to struct path to fill
+ */
+int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt,
+ const char *name, unsigned int flags,
+ struct path *path)
+{
+ struct path root = {.mnt = mnt, .dentry = dentry};
+ /* the first argument of filename_lookup() is ignored with root */
+ return filename_lookup(AT_FDCWD, getname_kernel(name),
+ flags , path, &root);
+}
+EXPORT_SYMBOL(vfs_path_lookup);
+
+/**
+ * lookup_one_len - filesystem helper to lookup single pathname component
+ * @name: pathname component to lookup
+ * @mnt: mount we are looking up on
+ * @base: base directory to lookup from
+ * @len: maximum length @len should be interpreted to
+ *
+ * Note that this routine is purely a helper for filesystem usage and should
+ * not be called by generic code.
+ *
+ * The caller must hold base->i_mutex.
+ */
+struct dentry *lookup_one_len2(const char *name, struct vfsmount *mnt, struct dentry *base, int len)
+{
+ struct qstr this;
+ unsigned int c;
+ int err;
+
+ WARN_ON_ONCE(!inode_is_locked(base->d_inode));
+
+ this.name = name;
+ this.len = len;
+ this.hash = full_name_hash(base, name, len);
+ if (!len)
+ return ERR_PTR(-EACCES);
+
+ if (unlikely(name[0] == '.')) {
+ if (len < 2 || (len == 2 && name[1] == '.'))
+ return ERR_PTR(-EACCES);
+ }
+
+ while (len--) {
+ c = *(const unsigned char *)name++;
+ if (c == '/' || c == '\0')
+ return ERR_PTR(-EACCES);
+ }
+ /*
+ * See if the low-level filesystem might want
+ * to use its own hash..
+ */
+ if (base->d_flags & DCACHE_OP_HASH) {
+ int err = base->d_op->d_hash(base, &this);
+ if (err < 0)
+ return ERR_PTR(err);
+ }
+
+ err = inode_permission2(mnt, base->d_inode, MAY_EXEC);
+ if (err)
+ return ERR_PTR(err);
+
+ return __lookup_hash(&this, base, 0);
+}
+EXPORT_SYMBOL(lookup_one_len2);
+
+struct dentry *lookup_one_len(const char *name, struct dentry *base, int len)
+{
+ return lookup_one_len2(name, NULL, base, len);
+}
+EXPORT_SYMBOL(lookup_one_len);
+
+/**
+ * lookup_one_len_unlocked - filesystem helper to lookup single pathname component
+ * @name: pathname component to lookup
+ * @base: base directory to lookup from
+ * @len: maximum length @len should be interpreted to
+ *
+ * Note that this routine is purely a helper for filesystem usage and should
+ * not be called by generic code.
+ *
+ * Unlike lookup_one_len, it should be called without the parent
+ * i_mutex held, and will take the i_mutex itself if necessary.
+ */
+struct dentry *lookup_one_len_unlocked(const char *name,
+ struct dentry *base, int len)
+{
+ struct qstr this;
+ unsigned int c;
+ int err;
+ struct dentry *ret;
+
+ this.name = name;
+ this.len = len;
+ this.hash = full_name_hash(base, name, len);
+ if (!len)
+ return ERR_PTR(-EACCES);
+
+ if (unlikely(name[0] == '.')) {
+ if (len < 2 || (len == 2 && name[1] == '.'))
+ return ERR_PTR(-EACCES);
+ }
+
+ while (len--) {
+ c = *(const unsigned char *)name++;
+ if (c == '/' || c == '\0')
+ return ERR_PTR(-EACCES);
+ }
+ /*
+ * See if the low-level filesystem might want
+ * to use its own hash..
+ */
+ if (base->d_flags & DCACHE_OP_HASH) {
+ int err = base->d_op->d_hash(base, &this);
+ if (err < 0)
+ return ERR_PTR(err);
+ }
+
+ err = inode_permission(base->d_inode, MAY_EXEC);
+ if (err)
+ return ERR_PTR(err);
+
+ ret = lookup_dcache(&this, base, 0);
+ if (!ret)
+ ret = lookup_slow(&this, base, 0);
+ return ret;
+}
+EXPORT_SYMBOL(lookup_one_len_unlocked);
+
+#ifdef CONFIG_UNIX98_PTYS
+int path_pts(struct path *path)
+{
+ /* Find something mounted on "pts" in the same directory as
+ * the input path.
+ */
+ struct dentry *child, *parent;
+ struct qstr this;
+ int ret;
+
+ ret = path_parent_directory(path);
+ if (ret)
+ return ret;
+
+ parent = path->dentry;
+ this.name = "pts";
+ this.len = 3;
+ child = d_hash_and_lookup(parent, &this);
+ if (!child)
+ return -ENOENT;
+
+ path->dentry = child;
+ dput(parent);
+ follow_mount(path);
+ return 0;
+}
+#endif
+
+int user_path_at_empty(int dfd, const char __user *name, unsigned flags,
+ struct path *path, int *empty)
+{
+ return filename_lookup(dfd, getname_flags(name, flags, empty),
+ flags, path, NULL);
+}
+EXPORT_SYMBOL(user_path_at_empty);
+
+/**
+ * mountpoint_last - look up last component for umount
+ * @nd: pathwalk nameidata - currently pointing at parent directory of "last"
+ *
+ * This is a special lookup_last function just for umount. In this case, we
+ * need to resolve the path without doing any revalidation.
+ *
+ * The nameidata should be the result of doing a LOOKUP_PARENT pathwalk. Since
+ * mountpoints are always pinned in the dcache, their ancestors are too. Thus,
+ * in almost all cases, this lookup will be served out of the dcache. The only
+ * cases where it won't are if nd->last refers to a symlink or the path is
+ * bogus and it doesn't exist.
+ *
+ * Returns:
+ * -error: if there was an error during lookup. This includes -ENOENT if the
+ * lookup found a negative dentry.
+ *
+ * 0: if we successfully resolved nd->last and found it to not to be a
+ * symlink that needs to be followed.
+ *
+ * 1: if we successfully resolved nd->last and found it to be a symlink
+ * that needs to be followed.
+ */
+static int
+mountpoint_last(struct nameidata *nd)
+{
+ int error = 0;
+ struct dentry *dir = nd->path.dentry;
+ struct path path;
+
+ /* If we're in rcuwalk, drop out of it to handle last component */
+ if (nd->flags & LOOKUP_RCU) {
+ if (unlazy_walk(nd))
+ return -ECHILD;
+ }
+
+ nd->flags &= ~LOOKUP_PARENT;
+
+ if (unlikely(nd->last_type != LAST_NORM)) {
+ error = handle_dots(nd, nd->last_type);
+ if (error)
+ return error;
+ path.dentry = dget(nd->path.dentry);
+ } else {
+ path.dentry = d_lookup(dir, &nd->last);
+ if (!path.dentry) {
+ /*
+ * No cached dentry. Mounted dentries are pinned in the
+ * cache, so that means that this dentry is probably
+ * a symlink or the path doesn't actually point
+ * to a mounted dentry.
+ */
+ path.dentry = lookup_slow(&nd->last, dir,
+ nd->flags | LOOKUP_NO_REVAL);
+ if (IS_ERR(path.dentry))
+ return PTR_ERR(path.dentry);
+ }
+ }
+ if (d_is_negative(path.dentry)) {
+ dput(path.dentry);
+ return -ENOENT;
+ }
+ path.mnt = nd->path.mnt;
+ return step_into(nd, &path, 0, d_backing_inode(path.dentry), 0);
+}
+
+/**
+ * path_mountpoint - look up a path to be umounted
+ * @nd: lookup context
+ * @flags: lookup flags
+ * @path: pointer to container for result
+ *
+ * Look up the given name, but don't attempt to revalidate the last component.
+ * Returns 0 and "path" will be valid on success; Returns error otherwise.
+ */
+static int
+path_mountpoint(struct nameidata *nd, unsigned flags, struct path *path)
+{
+ const char *s = path_init(nd, flags);
+ int err;
+ if (IS_ERR(s))
+ return PTR_ERR(s);
+ while (!(err = link_path_walk(s, nd)) &&
+ (err = mountpoint_last(nd)) > 0) {
+ s = trailing_symlink(nd);
+ if (IS_ERR(s)) {
+ err = PTR_ERR(s);
+ break;
+ }
+ }
+ if (!err) {
+ *path = nd->path;
+ nd->path.mnt = NULL;
+ nd->path.dentry = NULL;
+ follow_mount(path);
+ }
+ terminate_walk(nd);
+ return err;
+}
+
+static int
+filename_mountpoint(int dfd, struct filename *name, struct path *path,
+ unsigned int flags)
+{
+ struct nameidata nd;
+ int error;
+ if (IS_ERR(name))
+ return PTR_ERR(name);
+ set_nameidata(&nd, dfd, name);
+ error = path_mountpoint(&nd, flags | LOOKUP_RCU, path);
+ if (unlikely(error == -ECHILD))
+ error = path_mountpoint(&nd, flags, path);
+ if (unlikely(error == -ESTALE))
+ error = path_mountpoint(&nd, flags | LOOKUP_REVAL, path);
+ if (likely(!error))
+ audit_inode(name, path->dentry, 0);
+ restore_nameidata();
+ putname(name);
+ return error;
+}
+
+/**
+ * user_path_mountpoint_at - lookup a path from userland in order to umount it
+ * @dfd: directory file descriptor
+ * @name: pathname from userland
+ * @flags: lookup flags
+ * @path: pointer to container to hold result
+ *
+ * A umount is a special case for path walking. We're not actually interested
+ * in the inode in this situation, and ESTALE errors can be a problem. We
+ * simply want track down the dentry and vfsmount attached at the mountpoint
+ * and avoid revalidating the last component.
+ *
+ * Returns 0 and populates "path" on success.
+ */
+int
+user_path_mountpoint_at(int dfd, const char __user *name, unsigned int flags,
+ struct path *path)
+{
+ return filename_mountpoint(dfd, getname(name), path, flags);
+}
+
+int
+kern_path_mountpoint(int dfd, const char *name, struct path *path,
+ unsigned int flags)
+{
+ return filename_mountpoint(dfd, getname_kernel(name), path, flags);
+}
+EXPORT_SYMBOL(kern_path_mountpoint);
+
+int __check_sticky(struct inode *dir, struct inode *inode)
+{
+ kuid_t fsuid = current_fsuid();
+
+ if (uid_eq(inode->i_uid, fsuid))
+ return 0;
+ if (uid_eq(dir->i_uid, fsuid))
+ return 0;
+ return !capable_wrt_inode_uidgid(inode, CAP_FOWNER);
+}
+EXPORT_SYMBOL(__check_sticky);
+
+/*
+ * Check whether we can remove a link victim from directory dir, check
+ * whether the type of victim is right.
+ * 1. We can't do it if dir is read-only (done in permission())
+ * 2. We should have write and exec permissions on dir
+ * 3. We can't remove anything from append-only dir
+ * 4. We can't do anything with immutable dir (done in permission())
+ * 5. If the sticky bit on dir is set we should either
+ * a. be owner of dir, or
+ * b. be owner of victim, or
+ * c. have CAP_FOWNER capability
+ * 6. If the victim is append-only or immutable we can't do antyhing with
+ * links pointing to it.
+ * 7. If the victim has an unknown uid or gid we can't change the inode.
+ * 8. If we were asked to remove a directory and victim isn't one - ENOTDIR.
+ * 9. If we were asked to remove a non-directory and victim isn't one - EISDIR.
+ * 10. We can't remove a root or mountpoint.
+ * 11. We don't allow removal of NFS sillyrenamed files; it's handled by
+ * nfs_async_unlink().
+ */
+static int may_delete(struct vfsmount *mnt, struct inode *dir, struct dentry *victim, bool isdir)
+{
+ struct inode *inode = d_backing_inode(victim);
+ int error;
+
+ if (d_is_negative(victim))
+ return -ENOENT;
+ BUG_ON(!inode);
+
+ BUG_ON(victim->d_parent->d_inode != dir);
+ audit_inode_child(dir, victim, AUDIT_TYPE_CHILD_DELETE);
+
+ error = inode_permission2(mnt, dir, MAY_WRITE | MAY_EXEC);
+ if (error)
+ return error;
+ if (IS_APPEND(dir))
+ return -EPERM;
+
+ if (check_sticky(dir, inode) || IS_APPEND(inode) ||
+ IS_IMMUTABLE(inode) || IS_SWAPFILE(inode) || HAS_UNMAPPED_ID(inode))
+ return -EPERM;
+ if (isdir) {
+ if (!d_is_dir(victim))
+ return -ENOTDIR;
+ if (IS_ROOT(victim))
+ return -EBUSY;
+ } else if (d_is_dir(victim))
+ return -EISDIR;
+ if (IS_DEADDIR(dir))
+ return -ENOENT;
+ if (victim->d_flags & DCACHE_NFSFS_RENAMED)
+ return -EBUSY;
+ return 0;
+}
+
+/* Check whether we can create an object with dentry child in directory
+ * dir.
+ * 1. We can't do it if child already exists (open has special treatment for
+ * this case, but since we are inlined it's OK)
+ * 2. We can't do it if dir is read-only (done in permission())
+ * 3. We can't do it if the fs can't represent the fsuid or fsgid.
+ * 4. We should have write and exec permissions on dir
+ * 5. We can't do it if dir is immutable (done in permission())
+ */
+static inline int may_create(struct vfsmount *mnt, struct inode *dir, struct dentry *child)
+{
+ struct user_namespace *s_user_ns;
+ audit_inode_child(dir, child, AUDIT_TYPE_CHILD_CREATE);
+ if (child->d_inode)
+ return -EEXIST;
+ if (IS_DEADDIR(dir))
+ return -ENOENT;
+ s_user_ns = dir->i_sb->s_user_ns;
+ if (!kuid_has_mapping(s_user_ns, current_fsuid()) ||
+ !kgid_has_mapping(s_user_ns, current_fsgid()))
+ return -EOVERFLOW;
+ return inode_permission2(mnt, dir, MAY_WRITE | MAY_EXEC);
+}
+
+/*
+ * p1 and p2 should be directories on the same fs.
+ */
+struct dentry *lock_rename(struct dentry *p1, struct dentry *p2)
+{
+ struct dentry *p;
+
+ if (p1 == p2) {
+ inode_lock_nested(p1->d_inode, I_MUTEX_PARENT);
+ return NULL;
+ }
+
+ mutex_lock(&p1->d_sb->s_vfs_rename_mutex);
+
+ p = d_ancestor(p2, p1);
+ if (p) {
+ inode_lock_nested(p2->d_inode, I_MUTEX_PARENT);
+ inode_lock_nested(p1->d_inode, I_MUTEX_CHILD);
+ return p;
+ }
+
+ p = d_ancestor(p1, p2);
+ if (p) {
+ inode_lock_nested(p1->d_inode, I_MUTEX_PARENT);
+ inode_lock_nested(p2->d_inode, I_MUTEX_CHILD);
+ return p;
+ }
+
+ inode_lock_nested(p1->d_inode, I_MUTEX_PARENT);
+ inode_lock_nested(p2->d_inode, I_MUTEX_PARENT2);
+ return NULL;
+}
+EXPORT_SYMBOL(lock_rename);
+
+void unlock_rename(struct dentry *p1, struct dentry *p2)
+{
+ inode_unlock(p1->d_inode);
+ if (p1 != p2) {
+ inode_unlock(p2->d_inode);
+ mutex_unlock(&p1->d_sb->s_vfs_rename_mutex);
+ }
+}
+EXPORT_SYMBOL(unlock_rename);
+
+int vfs_create2(struct vfsmount *mnt, struct inode *dir, struct dentry *dentry,
+ umode_t mode, bool want_excl)
+{
+ int error = may_create(mnt, dir, dentry);
+ if (error)
+ return error;
+
+ if (!dir->i_op->create)
+ return -EACCES; /* shouldn't it be ENOSYS? */
+ mode &= S_IALLUGO;
+ mode |= S_IFREG;
+ error = security_inode_create(dir, dentry, mode);
+ if (error)
+ return error;
+ error = dir->i_op->create(dir, dentry, mode, want_excl);
+ if (!error)
+ fsnotify_create(dir, dentry);
+ return error;
+}
+EXPORT_SYMBOL(vfs_create2);
+
+int vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode,
+ bool want_excl)
+{
+ return vfs_create2(NULL, dir, dentry, mode, want_excl);
+}
+EXPORT_SYMBOL(vfs_create);
+
+bool may_open_dev(const struct path *path)
+{
+ return !(path->mnt->mnt_flags & MNT_NODEV) &&
+ !(path->mnt->mnt_sb->s_iflags & SB_I_NODEV);
+}
+
+static int may_open(const struct path *path, int acc_mode, int flag)
+{
+ struct dentry *dentry = path->dentry;
+ struct vfsmount *mnt = path->mnt;
+ struct inode *inode = dentry->d_inode;
+ int error;
+
+ if (!inode)
+ return -ENOENT;
+
+ switch (inode->i_mode & S_IFMT) {
+ case S_IFLNK:
+ return -ELOOP;
+ case S_IFDIR:
+ if (acc_mode & MAY_WRITE)
+ return -EISDIR;
+ break;
+ case S_IFBLK:
+ case S_IFCHR:
+ if (!may_open_dev(path))
+ return -EACCES;
+ /*FALLTHRU*/
+ case S_IFIFO:
+ case S_IFSOCK:
+ flag &= ~O_TRUNC;
+ break;
+ }
+
+ error = inode_permission2(mnt, inode, MAY_OPEN | acc_mode);
+ if (error)
+ return error;
+
+ /*
+ * An append-only file must be opened in append mode for writing.
+ */
+ if (IS_APPEND(inode)) {
+ if ((flag & O_ACCMODE) != O_RDONLY && !(flag & O_APPEND))
+ return -EPERM;
+ if (flag & O_TRUNC)
+ return -EPERM;
+ }
+
+ /* O_NOATIME can only be set by the owner or superuser */
+ if (flag & O_NOATIME && !inode_owner_or_capable(inode))
+ return -EPERM;
+
+ return 0;
+}
+
+static int handle_truncate(struct file *filp)
+{
+ const struct path *path = &filp->f_path;
+ struct inode *inode = path->dentry->d_inode;
+ int error = get_write_access(inode);
+ if (error)
+ return error;
+ /*
+ * Refuse to truncate files with mandatory locks held on them.
+ */
+ error = locks_verify_locked(filp);
+ if (!error)
+ error = security_path_truncate(path);
+ if (!error) {
+ error = do_truncate2(path->mnt, path->dentry, 0,
+ ATTR_MTIME|ATTR_CTIME|ATTR_OPEN,
+ filp);
+ }
+ put_write_access(inode);
+ return error;
+}
+
+static inline int open_to_namei_flags(int flag)
+{
+ if ((flag & O_ACCMODE) == 3)
+ flag--;
+ return flag;
+}
+
+static int may_o_create(const struct path *dir, struct dentry *dentry, umode_t mode)
+{
+ struct user_namespace *s_user_ns;
+ int error = security_path_mknod(dir, dentry, mode, 0);
+ if (error)
+ return error;
+
+ s_user_ns = dir->dentry->d_sb->s_user_ns;
+ if (!kuid_has_mapping(s_user_ns, current_fsuid()) ||
+ !kgid_has_mapping(s_user_ns, current_fsgid()))
+ return -EOVERFLOW;
+
+ error = inode_permission2(dir->mnt, dir->dentry->d_inode, MAY_WRITE | MAY_EXEC);
+ if (error)
+ return error;
+
+ return security_inode_create(dir->dentry->d_inode, dentry, mode);
+}
+
+/*
+ * Attempt to atomically look up, create and open a file from a negative
+ * dentry.
+ *
+ * Returns 0 if successful. The file will have been created and attached to
+ * @file by the filesystem calling finish_open().
+ *
+ * Returns 1 if the file was looked up only or didn't need creating. The
+ * caller will need to perform the open themselves. @path will have been
+ * updated to point to the new dentry. This may be negative.
+ *
+ * Returns an error code otherwise.
+ */
+static int atomic_open(struct nameidata *nd, struct dentry *dentry,
+ struct path *path, struct file *file,
+ const struct open_flags *op,
+ int open_flag, umode_t mode,
+ int *opened)
+{
+ struct dentry *const DENTRY_NOT_SET = (void *) -1UL;
+ struct inode *dir = nd->path.dentry->d_inode;
+ int error;
+
+ if (!(~open_flag & (O_EXCL | O_CREAT))) /* both O_EXCL and O_CREAT */
+ open_flag &= ~O_TRUNC;
+
+ if (nd->flags & LOOKUP_DIRECTORY)
+ open_flag |= O_DIRECTORY;
+
+ file->f_path.dentry = DENTRY_NOT_SET;
+ file->f_path.mnt = nd->path.mnt;
+ error = dir->i_op->atomic_open(dir, dentry, file,
+ open_to_namei_flags(open_flag),
+ mode, opened);
+ d_lookup_done(dentry);
+ if (!error) {
+ /*
+ * We didn't have the inode before the open, so check open
+ * permission here.
+ */
+ int acc_mode = op->acc_mode;
+ if (*opened & FILE_CREATED) {
+ WARN_ON(!(open_flag & O_CREAT));
+ fsnotify_create(dir, dentry);
+ acc_mode = 0;
+ }
+ error = may_open(&file->f_path, acc_mode, open_flag);
+ if (WARN_ON(error > 0))
+ error = -EINVAL;
+ } else if (error > 0) {
+ if (WARN_ON(file->f_path.dentry == DENTRY_NOT_SET)) {
+ error = -EIO;
+ } else {
+ if (file->f_path.dentry) {
+ dput(dentry);
+ dentry = file->f_path.dentry;
+ }
+ if (*opened & FILE_CREATED)
+ fsnotify_create(dir, dentry);
+ if (unlikely(d_is_negative(dentry))) {
+ error = -ENOENT;
+ } else {
+ path->dentry = dentry;
+ path->mnt = nd->path.mnt;
+ return 1;
+ }
+ }
+ }
+ dput(dentry);
+ return error;
+}
+
+/*
+ * Look up and maybe create and open the last component.
+ *
+ * Must be called with i_mutex held on parent.
+ *
+ * Returns 0 if the file was successfully atomically created (if necessary) and
+ * opened. In this case the file will be returned attached to @file.
+ *
+ * Returns 1 if the file was not completely opened at this time, though lookups
+ * and creations will have been performed and the dentry returned in @path will
+ * be positive upon return if O_CREAT was specified. If O_CREAT wasn't
+ * specified then a negative dentry may be returned.
+ *
+ * An error code is returned otherwise.
+ *
+ * FILE_CREATE will be set in @*opened if the dentry was created and will be
+ * cleared otherwise prior to returning.
+ */
+static int lookup_open(struct nameidata *nd, struct path *path,
+ struct file *file,
+ const struct open_flags *op,
+ bool got_write, int *opened)
+{
+ struct dentry *dir = nd->path.dentry;
+ struct inode *dir_inode = dir->d_inode;
+ int open_flag = op->open_flag;
+ struct dentry *dentry;
+ int error, create_error = 0;
+ umode_t mode = op->mode;
+ DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq);
+
+ if (unlikely(IS_DEADDIR(dir_inode)))
+ return -ENOENT;
+
+ *opened &= ~FILE_CREATED;
+ dentry = d_lookup(dir, &nd->last);
+ for (;;) {
+ if (!dentry) {
+ dentry = d_alloc_parallel(dir, &nd->last, &wq);
+ if (IS_ERR(dentry))
+ return PTR_ERR(dentry);
+ }
+ if (d_in_lookup(dentry))
+ break;
+
+ error = d_revalidate(dentry, nd->flags);
+ if (likely(error > 0))
+ break;
+ if (error)
+ goto out_dput;
+ d_invalidate(dentry);
+ dput(dentry);
+ dentry = NULL;
+ }
+ if (dentry->d_inode) {
+ /* Cached positive dentry: will open in f_op->open */
+ goto out_no_open;
+ }
+
+ /*
+ * Checking write permission is tricky, bacuse we don't know if we are
+ * going to actually need it: O_CREAT opens should work as long as the
+ * file exists. But checking existence breaks atomicity. The trick is
+ * to check access and if not granted clear O_CREAT from the flags.
+ *
+ * Another problem is returing the "right" error value (e.g. for an
+ * O_EXCL open we want to return EEXIST not EROFS).
+ */
+ if (open_flag & O_CREAT) {
+ if (!IS_POSIXACL(dir->d_inode))
+ mode &= ~current_umask();
+ if (unlikely(!got_write)) {
+ create_error = -EROFS;
+ open_flag &= ~O_CREAT;
+ if (open_flag & (O_EXCL | O_TRUNC))
+ goto no_open;
+ /* No side effects, safe to clear O_CREAT */
+ } else {
+ create_error = may_o_create(&nd->path, dentry, mode);
+ if (create_error) {
+ open_flag &= ~O_CREAT;
+ if (open_flag & O_EXCL)
+ goto no_open;
+ }
+ }
+ } else if ((open_flag & (O_TRUNC|O_WRONLY|O_RDWR)) &&
+ unlikely(!got_write)) {
+ /*
+ * No O_CREATE -> atomicity not a requirement -> fall
+ * back to lookup + open
+ */
+ goto no_open;
+ }
+
+ if (dir_inode->i_op->atomic_open) {
+ error = atomic_open(nd, dentry, path, file, op, open_flag,
+ mode, opened);
+ if (unlikely(error == -ENOENT) && create_error)
+ error = create_error;
+ return error;
+ }
+
+no_open:
+ if (d_in_lookup(dentry)) {
+ struct dentry *res = dir_inode->i_op->lookup(dir_inode, dentry,
+ nd->flags);
+ d_lookup_done(dentry);
+ if (unlikely(res)) {
+ if (IS_ERR(res)) {
+ error = PTR_ERR(res);
+ goto out_dput;
+ }
+ dput(dentry);
+ dentry = res;
+ }
+ }
+
+ /* Negative dentry, just create the file */
+ if (!dentry->d_inode && (open_flag & O_CREAT)) {
+ *opened |= FILE_CREATED;
+ audit_inode_child(dir_inode, dentry, AUDIT_TYPE_CHILD_CREATE);
+ if (!dir_inode->i_op->create) {
+ error = -EACCES;
+ goto out_dput;
+ }
+ error = dir_inode->i_op->create(dir_inode, dentry, mode,
+ open_flag & O_EXCL);
+ if (error)
+ goto out_dput;
+ fsnotify_create(dir_inode, dentry);
+ }
+ if (unlikely(create_error) && !dentry->d_inode) {
+ error = create_error;
+ goto out_dput;
+ }
+out_no_open:
+ path->dentry = dentry;
+ path->mnt = nd->path.mnt;
+ return 1;
+
+out_dput:
+ dput(dentry);
+ return error;
+}
+
+/*
+ * Handle the last step of open()
+ */
+static int do_last(struct nameidata *nd,
+ struct file *file, const struct open_flags *op,
+ int *opened)
+{
+ struct dentry *dir = nd->path.dentry;
+ kuid_t dir_uid = nd->inode->i_uid;
+ umode_t dir_mode = nd->inode->i_mode;
+ int open_flag = op->open_flag;
+ bool will_truncate = (open_flag & O_TRUNC) != 0;
+ bool got_write = false;
+ int acc_mode = op->acc_mode;
+ unsigned seq;
+ struct inode *inode;
+ struct path path;
+ int error;
+
+ nd->flags &= ~LOOKUP_PARENT;
+ nd->flags |= op->intent;
+
+ if (nd->last_type != LAST_NORM) {
+ error = handle_dots(nd, nd->last_type);
+ if (unlikely(error))
+ return error;
+ goto finish_open;
+ }
+
+ if (!(open_flag & O_CREAT)) {
+ if (nd->last.name[nd->last.len])
+ nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
+ /* we _can_ be in RCU mode here */
+ error = lookup_fast(nd, &path, &inode, &seq);
+ if (likely(error > 0))
+ goto finish_lookup;
+
+ if (error < 0)
+ return error;
+
+ BUG_ON(nd->inode != dir->d_inode);
+ BUG_ON(nd->flags & LOOKUP_RCU);
+ } else {
+ /* create side of things */
+ /*
+ * This will *only* deal with leaving RCU mode - LOOKUP_JUMPED
+ * has been cleared when we got to the last component we are
+ * about to look up
+ */
+ error = complete_walk(nd);
+ if (error)
+ return error;
+
+ audit_inode(nd->name, dir, LOOKUP_PARENT);
+ /* trailing slashes? */
+ if (unlikely(nd->last.name[nd->last.len]))
+ return -EISDIR;
+ }
+
+ if (open_flag & (O_CREAT | O_TRUNC | O_WRONLY | O_RDWR)) {
+ error = mnt_want_write(nd->path.mnt);
+ if (!error)
+ got_write = true;
+ /*
+ * do _not_ fail yet - we might not need that or fail with
+ * a different error; let lookup_open() decide; we'll be
+ * dropping this one anyway.
+ */
+ }
+ if (open_flag & O_CREAT)
+ inode_lock(dir->d_inode);
+ else
+ inode_lock_shared(dir->d_inode);
+ error = lookup_open(nd, &path, file, op, got_write, opened);
+ if (open_flag & O_CREAT)
+ inode_unlock(dir->d_inode);
+ else
+ inode_unlock_shared(dir->d_inode);
+
+ if (error <= 0) {
+ if (error)
+ goto out;
+
+ if ((*opened & FILE_CREATED) ||
+ !S_ISREG(file_inode(file)->i_mode))
+ will_truncate = false;
+
+ audit_inode(nd->name, file->f_path.dentry, 0);
+ goto opened;
+ }
+
+ if (*opened & FILE_CREATED) {
+ /* Don't check for write permission, don't truncate */
+ open_flag &= ~O_TRUNC;
+ will_truncate = false;
+ acc_mode = 0;
+ path_to_nameidata(&path, nd);
+ goto finish_open_created;
+ }
+
+ /*
+ * If atomic_open() acquired write access it is dropped now due to
+ * possible mount and symlink following (this might be optimized away if
+ * necessary...)
+ */
+ if (got_write) {
+ mnt_drop_write(nd->path.mnt);
+ got_write = false;
+ }
+
+ error = follow_managed(&path, nd);
+ if (unlikely(error < 0))
+ return error;
+
+ if (unlikely(d_is_negative(path.dentry))) {
+ path_to_nameidata(&path, nd);
+ return -ENOENT;
+ }
+
+ /*
+ * create/update audit record if it already exists.
+ */
+ audit_inode(nd->name, path.dentry, 0);
+
+ if (unlikely((open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT))) {
+ path_to_nameidata(&path, nd);
+ return -EEXIST;
+ }
+
+ seq = 0; /* out of RCU mode, so the value doesn't matter */
+ inode = d_backing_inode(path.dentry);
+finish_lookup:
+ error = step_into(nd, &path, 0, inode, seq);
+ if (unlikely(error))
+ return error;
+finish_open:
+ /* Why this, you ask? _Now_ we might have grown LOOKUP_JUMPED... */
+ error = complete_walk(nd);
+ if (error)
+ return error;
+ audit_inode(nd->name, nd->path.dentry, 0);
+ if (open_flag & O_CREAT) {
+ error = -EISDIR;
+ if (d_is_dir(nd->path.dentry))
+ goto out;
+ error = may_create_in_sticky(dir_mode, dir_uid,
+ d_backing_inode(nd->path.dentry));
+ if (unlikely(error))
+ goto out;
+ }
+ error = -ENOTDIR;
+ if ((nd->flags & LOOKUP_DIRECTORY) && !d_can_lookup(nd->path.dentry))
+ goto out;
+ if (!d_is_reg(nd->path.dentry))
+ will_truncate = false;
+
+ if (will_truncate) {
+ error = mnt_want_write(nd->path.mnt);
+ if (error)
+ goto out;
+ got_write = true;
+ }
+finish_open_created:
+ error = may_open(&nd->path, acc_mode, open_flag);
+ if (error)
+ goto out;
+ BUG_ON(*opened & FILE_OPENED); /* once it's opened, it's opened */
+ error = vfs_open(&nd->path, file, current_cred());
+ if (error)
+ goto out;
+ *opened |= FILE_OPENED;
+opened:
+ error = open_check_o_direct(file);
+ if (!error)
+ error = ima_file_check(file, op->acc_mode, *opened);
+ if (!error && will_truncate)
+ error = handle_truncate(file);
+out:
+ if (unlikely(error) && (*opened & FILE_OPENED))
+ fput(file);
+ if (unlikely(error > 0)) {
+ WARN_ON(1);
+ error = -EINVAL;
+ }
+ if (got_write)
+ mnt_drop_write(nd->path.mnt);
+ return error;
+}
+
+struct dentry *vfs_tmpfile(struct dentry *dentry, umode_t mode, int open_flag)
+{
+ struct dentry *child = NULL;
+ struct inode *dir = dentry->d_inode;
+ struct inode *inode;
+ int error;
+
+ /* we want directory to be writable */
+ error = inode_permission2(ERR_PTR(-EOPNOTSUPP), dir,
+ MAY_WRITE | MAY_EXEC);
+ if (error)
+ goto out_err;
+ error = -EOPNOTSUPP;
+ if (!dir->i_op->tmpfile)
+ goto out_err;
+ error = -ENOMEM;
+ child = d_alloc(dentry, &slash_name);
+ if (unlikely(!child))
+ goto out_err;
+ error = dir->i_op->tmpfile(dir, child, mode);
+ if (error)
+ goto out_err;
+ error = -ENOENT;
+ inode = child->d_inode;
+ if (unlikely(!inode))
+ goto out_err;
+ if (!(open_flag & O_EXCL)) {
+ spin_lock(&inode->i_lock);
+ inode->i_state |= I_LINKABLE;
+ spin_unlock(&inode->i_lock);
+ }
+ return child;
+
+out_err:
+ dput(child);
+ return ERR_PTR(error);
+}
+EXPORT_SYMBOL(vfs_tmpfile);
+
+static int do_tmpfile(struct nameidata *nd, unsigned flags,
+ const struct open_flags *op,
+ struct file *file, int *opened)
+{
+ struct dentry *child;
+ struct path path;
+ int error = path_lookupat(nd, flags | LOOKUP_DIRECTORY, &path);
+ if (unlikely(error))
+ return error;
+ error = mnt_want_write(path.mnt);
+ if (unlikely(error))
+ goto out;
+ child = vfs_tmpfile(path.dentry, op->mode, op->open_flag);
+ error = PTR_ERR(child);
+ if (unlikely(IS_ERR(child)))
+ goto out2;
+ dput(path.dentry);
+ path.dentry = child;
+ audit_inode(nd->name, child, 0);
+ /* Don't check for other permissions, the inode was just created */
+ error = may_open(&path, 0, op->open_flag);
+ if (error)
+ goto out2;
+ file->f_path.mnt = path.mnt;
+ error = finish_open(file, child, NULL, opened);
+ if (error)
+ goto out2;
+ error = open_check_o_direct(file);
+ if (error)
+ fput(file);
+out2:
+ mnt_drop_write(path.mnt);
+out:
+ path_put(&path);
+ return error;
+}
+
+static int do_o_path(struct nameidata *nd, unsigned flags, struct file *file)
+{
+ struct path path;
+ int error = path_lookupat(nd, flags, &path);
+ if (!error) {
+ audit_inode(nd->name, path.dentry, 0);
+ error = vfs_open(&path, file, current_cred());
+ path_put(&path);
+ }
+ return error;
+}
+
+static struct file *path_openat(struct nameidata *nd,
+ const struct open_flags *op, unsigned flags)
+{
+ const char *s;
+ struct file *file;
+ int opened = 0;
+ int error;
+
+ file = get_empty_filp();
+ if (IS_ERR(file))
+ return file;
+
+ file->f_flags = op->open_flag;
+
+ if (unlikely(file->f_flags & __O_TMPFILE)) {
+ error = do_tmpfile(nd, flags, op, file, &opened);
+ goto out2;
+ }
+
+ if (unlikely(file->f_flags & O_PATH)) {
+ error = do_o_path(nd, flags, file);
+ if (!error)
+ opened |= FILE_OPENED;
+ goto out2;
+ }
+
+ s = path_init(nd, flags);
+ if (IS_ERR(s)) {
+ put_filp(file);
+ return ERR_CAST(s);
+ }
+ while (!(error = link_path_walk(s, nd)) &&
+ (error = do_last(nd, file, op, &opened)) > 0) {
+ nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL);
+ s = trailing_symlink(nd);
+ if (IS_ERR(s)) {
+ error = PTR_ERR(s);
+ break;
+ }
+ }
+ terminate_walk(nd);
+out2:
+ if (!(opened & FILE_OPENED)) {
+ BUG_ON(!error);
+ put_filp(file);
+ }
+ if (unlikely(error)) {
+ if (error == -EOPENSTALE) {
+ if (flags & LOOKUP_RCU)
+ error = -ECHILD;
+ else
+ error = -ESTALE;
+ }
+ file = ERR_PTR(error);
+ }
+ return file;
+}
+
+struct file *do_filp_open(int dfd, struct filename *pathname,
+ const struct open_flags *op)
+{
+ struct nameidata nd;
+ int flags = op->lookup_flags;
+ struct file *filp;
+
+ set_nameidata(&nd, dfd, pathname);
+ filp = path_openat(&nd, op, flags | LOOKUP_RCU);
+ if (unlikely(filp == ERR_PTR(-ECHILD)))
+ filp = path_openat(&nd, op, flags);
+ if (unlikely(filp == ERR_PTR(-ESTALE)))
+ filp = path_openat(&nd, op, flags | LOOKUP_REVAL);
+ restore_nameidata();
+ return filp;
+}
+
+struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt,
+ const char *name, const struct open_flags *op)
+{
+ struct nameidata nd;
+ struct file *file;
+ struct filename *filename;
+ int flags = op->lookup_flags | LOOKUP_ROOT;
+
+ nd.root.mnt = mnt;
+ nd.root.dentry = dentry;
+
+ if (d_is_symlink(dentry) && op->intent & LOOKUP_OPEN)
+ return ERR_PTR(-ELOOP);
+
+ filename = getname_kernel(name);
+ if (IS_ERR(filename))
+ return ERR_CAST(filename);
+
+ set_nameidata(&nd, -1, filename);
+ file = path_openat(&nd, op, flags | LOOKUP_RCU);
+ if (unlikely(file == ERR_PTR(-ECHILD)))
+ file = path_openat(&nd, op, flags);
+ if (unlikely(file == ERR_PTR(-ESTALE)))
+ file = path_openat(&nd, op, flags | LOOKUP_REVAL);
+ restore_nameidata();
+ putname(filename);
+ return file;
+}
+
+static struct dentry *filename_create(int dfd, struct filename *name,
+ struct path *path, unsigned int lookup_flags)
+{
+ struct dentry *dentry = ERR_PTR(-EEXIST);
+ struct qstr last;
+ int type;
+ int err2;
+ int error;
+ bool is_dir = (lookup_flags & LOOKUP_DIRECTORY);
+
+ /*
+ * Note that only LOOKUP_REVAL and LOOKUP_DIRECTORY matter here. Any
+ * other flags passed in are ignored!
+ */
+ lookup_flags &= LOOKUP_REVAL;
+
+ name = filename_parentat(dfd, name, lookup_flags, path, &last, &type);
+ if (IS_ERR(name))
+ return ERR_CAST(name);
+
+ /*
+ * Yucky last component or no last component at all?
+ * (foo/., foo/.., /////)
+ */
+ if (unlikely(type != LAST_NORM))
+ goto out;
+
+ /* don't fail immediately if it's r/o, at least try to report other errors */
+ err2 = mnt_want_write(path->mnt);
+ /*
+ * Do the final lookup.
+ */
+ lookup_flags |= LOOKUP_CREATE | LOOKUP_EXCL;
+ inode_lock_nested(path->dentry->d_inode, I_MUTEX_PARENT);
+ dentry = __lookup_hash(&last, path->dentry, lookup_flags);
+ if (IS_ERR(dentry))
+ goto unlock;
+
+ error = -EEXIST;
+ if (d_is_positive(dentry))
+ goto fail;
+
+ /*
+ * Special case - lookup gave negative, but... we had foo/bar/
+ * From the vfs_mknod() POV we just have a negative dentry -
+ * all is fine. Let's be bastards - you had / on the end, you've
+ * been asking for (non-existent) directory. -ENOENT for you.
+ */
+ if (unlikely(!is_dir && last.name[last.len])) {
+ error = -ENOENT;
+ goto fail;
+ }
+ if (unlikely(err2)) {
+ error = err2;
+ goto fail;
+ }
+ putname(name);
+ return dentry;
+fail:
+ dput(dentry);
+ dentry = ERR_PTR(error);
+unlock:
+ inode_unlock(path->dentry->d_inode);
+ if (!err2)
+ mnt_drop_write(path->mnt);
+out:
+ path_put(path);
+ putname(name);
+ return dentry;
+}
+
+struct dentry *kern_path_create(int dfd, const char *pathname,
+ struct path *path, unsigned int lookup_flags)
+{
+ return filename_create(dfd, getname_kernel(pathname),
+ path, lookup_flags);
+}
+EXPORT_SYMBOL(kern_path_create);
+
+void done_path_create(struct path *path, struct dentry *dentry)
+{
+ dput(dentry);
+ inode_unlock(path->dentry->d_inode);
+ mnt_drop_write(path->mnt);
+ path_put(path);
+}
+EXPORT_SYMBOL(done_path_create);
+
+inline struct dentry *user_path_create(int dfd, const char __user *pathname,
+ struct path *path, unsigned int lookup_flags)
+{
+ return filename_create(dfd, getname(pathname), path, lookup_flags);
+}
+EXPORT_SYMBOL(user_path_create);
+
+int vfs_mknod2(struct vfsmount *mnt, struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev)
+{
+ int error = may_create(mnt, dir, dentry);
+
+ if (error)
+ return error;
+
+ if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD))
+ return -EPERM;
+
+ if (!dir->i_op->mknod)
+ return -EPERM;
+
+ error = devcgroup_inode_mknod(mode, dev);
+ if (error)
+ return error;
+
+ error = security_inode_mknod(dir, dentry, mode, dev);
+ if (error)
+ return error;
+
+ error = dir->i_op->mknod(dir, dentry, mode, dev);
+ if (!error)
+ fsnotify_create(dir, dentry);
+ return error;
+}
+EXPORT_SYMBOL(vfs_mknod2);
+
+int vfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev)
+{
+ return vfs_mknod2(NULL, dir, dentry, mode, dev);
+}
+EXPORT_SYMBOL(vfs_mknod);
+
+static int may_mknod(umode_t mode)
+{
+ switch (mode & S_IFMT) {
+ case S_IFREG:
+ case S_IFCHR:
+ case S_IFBLK:
+ case S_IFIFO:
+ case S_IFSOCK:
+ case 0: /* zero mode translates to S_IFREG */
+ return 0;
+ case S_IFDIR:
+ return -EPERM;
+ default:
+ return -EINVAL;
+ }
+}
+
+SYSCALL_DEFINE4(mknodat, int, dfd, const char __user *, filename, umode_t, mode,
+ unsigned, dev)
+{
+ struct dentry *dentry;
+ struct path path;
+ int error;
+ unsigned int lookup_flags = 0;
+
+ error = may_mknod(mode);
+ if (error)
+ return error;
+retry:
+ dentry = user_path_create(dfd, filename, &path, lookup_flags);
+ if (IS_ERR(dentry))
+ return PTR_ERR(dentry);
+
+ if (!IS_POSIXACL(path.dentry->d_inode))
+ mode &= ~current_umask();
+ error = security_path_mknod(&path, dentry, mode, dev);
+ if (error)
+ goto out;
+ switch (mode & S_IFMT) {
+ case 0: case S_IFREG:
+ error = vfs_create2(path.mnt, path.dentry->d_inode,dentry,mode,true);
+ if (!error)
+ ima_post_path_mknod(dentry);
+ break;
+ case S_IFCHR: case S_IFBLK:
+ error = vfs_mknod2(path.mnt, path.dentry->d_inode,dentry,mode,
+ new_decode_dev(dev));
+ break;
+ case S_IFIFO: case S_IFSOCK:
+ error = vfs_mknod(path.dentry->d_inode,dentry,mode,0);
+ break;
+ }
+out:
+ done_path_create(&path, dentry);
+ if (retry_estale(error, lookup_flags)) {
+ lookup_flags |= LOOKUP_REVAL;
+ goto retry;
+ }
+ return error;
+}
+
+SYSCALL_DEFINE3(mknod, const char __user *, filename, umode_t, mode, unsigned, dev)
+{
+ return sys_mknodat(AT_FDCWD, filename, mode, dev);
+}
+
+int vfs_mkdir2(struct vfsmount *mnt, struct inode *dir, struct dentry *dentry, umode_t mode)
+{
+ int error = may_create(mnt, dir, dentry);
+ unsigned max_links = dir->i_sb->s_max_links;
+
+ if (error)
+ return error;
+
+ if (!dir->i_op->mkdir)
+ return -EPERM;
+
+ mode &= (S_IRWXUGO|S_ISVTX);
+ error = security_inode_mkdir(dir, dentry, mode);
+ if (error)
+ return error;
+
+ if (max_links && dir->i_nlink >= max_links)
+ return -EMLINK;
+
+ error = dir->i_op->mkdir(dir, dentry, mode);
+ if (!error)
+ fsnotify_mkdir(dir, dentry);
+ return error;
+}
+EXPORT_SYMBOL(vfs_mkdir2);
+
+int vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
+{
+ return vfs_mkdir2(NULL, dir, dentry, mode);
+}
+EXPORT_SYMBOL(vfs_mkdir);
+
+SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, umode_t, mode)
+{
+ struct dentry *dentry;
+ struct path path;
+ int error;
+ unsigned int lookup_flags = LOOKUP_DIRECTORY;
+
+retry:
+ dentry = user_path_create(dfd, pathname, &path, lookup_flags);
+ if (IS_ERR(dentry))
+ return PTR_ERR(dentry);
+
+ if (!IS_POSIXACL(path.dentry->d_inode))
+ mode &= ~current_umask();
+ error = security_path_mkdir(&path, dentry, mode);
+ if (!error)
+ error = vfs_mkdir2(path.mnt, path.dentry->d_inode, dentry, mode);
+ done_path_create(&path, dentry);
+ if (retry_estale(error, lookup_flags)) {
+ lookup_flags |= LOOKUP_REVAL;
+ goto retry;
+ }
+ return error;
+}
+
+SYSCALL_DEFINE2(mkdir, const char __user *, pathname, umode_t, mode)
+{
+ return sys_mkdirat(AT_FDCWD, pathname, mode);
+}
+
+int vfs_rmdir2(struct vfsmount *mnt, struct inode *dir, struct dentry *dentry)
+{
+ int error = may_delete(mnt, dir, dentry, 1);
+
+ if (error)
+ return error;
+
+ if (!dir->i_op->rmdir)
+ return -EPERM;
+
+ dget(dentry);
+ inode_lock(dentry->d_inode);
+
+ error = -EBUSY;
+ if (is_local_mountpoint(dentry))
+ goto out;
+
+ error = security_inode_rmdir(dir, dentry);
+ if (error)
+ goto out;
+
+ shrink_dcache_parent(dentry);
+ error = dir->i_op->rmdir(dir, dentry);
+ if (error)
+ goto out;
+
+ dentry->d_inode->i_flags |= S_DEAD;
+ dont_mount(dentry);
+ detach_mounts(dentry);
+
+out:
+ inode_unlock(dentry->d_inode);
+ dput(dentry);
+ if (!error)
+ d_delete(dentry);
+ return error;
+}
+EXPORT_SYMBOL(vfs_rmdir2);
+
+int vfs_rmdir(struct inode *dir, struct dentry *dentry)
+{
+ return vfs_rmdir2(NULL, dir, dentry);
+}
+EXPORT_SYMBOL(vfs_rmdir);
+
+static long do_rmdir(int dfd, const char __user *pathname)
+{
+ int error = 0;
+ struct filename *name;
+ struct dentry *dentry;
+ struct path path;
+ struct qstr last;
+ int type;
+ unsigned int lookup_flags = 0;
+retry:
+ name = filename_parentat(dfd, getname(pathname), lookup_flags,
+ &path, &last, &type);
+ if (IS_ERR(name))
+ return PTR_ERR(name);
+
+ switch (type) {
+ case LAST_DOTDOT:
+ error = -ENOTEMPTY;
+ goto exit1;
+ case LAST_DOT:
+ error = -EINVAL;
+ goto exit1;
+ case LAST_ROOT:
+ error = -EBUSY;
+ goto exit1;
+ }
+
+ error = mnt_want_write(path.mnt);
+ if (error)
+ goto exit1;
+
+ inode_lock_nested(path.dentry->d_inode, I_MUTEX_PARENT);
+ dentry = __lookup_hash(&last, path.dentry, lookup_flags);
+ error = PTR_ERR(dentry);
+ if (IS_ERR(dentry))
+ goto exit2;
+ if (!dentry->d_inode) {
+ error = -ENOENT;
+ goto exit3;
+ }
+ error = security_path_rmdir(&path, dentry);
+ if (error)
+ goto exit3;
+ error = vfs_rmdir2(path.mnt, path.dentry->d_inode, dentry);
+exit3:
+ dput(dentry);
+exit2:
+ inode_unlock(path.dentry->d_inode);
+ mnt_drop_write(path.mnt);
+exit1:
+ path_put(&path);
+ putname(name);
+ if (retry_estale(error, lookup_flags)) {
+ lookup_flags |= LOOKUP_REVAL;
+ goto retry;
+ }
+ return error;
+}
+
+SYSCALL_DEFINE1(rmdir, const char __user *, pathname)
+{
+ return do_rmdir(AT_FDCWD, pathname);
+}
+
+/**
+ * vfs_unlink - unlink a filesystem object
+ * @dir: parent directory
+ * @dentry: victim
+ * @delegated_inode: returns victim inode, if the inode is delegated.
+ *
+ * The caller must hold dir->i_mutex.
+ *
+ * If vfs_unlink discovers a delegation, it will return -EWOULDBLOCK and
+ * return a reference to the inode in delegated_inode. The caller
+ * should then break the delegation on that inode and retry. Because
+ * breaking a delegation may take a long time, the caller should drop
+ * dir->i_mutex before doing so.
+ *
+ * Alternatively, a caller may pass NULL for delegated_inode. This may
+ * be appropriate for callers that expect the underlying filesystem not
+ * to be NFS exported.
+ */
+int vfs_unlink2(struct vfsmount *mnt, struct inode *dir, struct dentry *dentry, struct inode **delegated_inode)
+{
+ struct inode *target = dentry->d_inode;
+ int error = may_delete(mnt, dir, dentry, 0);
+
+ if (error)
+ return error;
+
+ if (!dir->i_op->unlink)
+ return -EPERM;
+
+ inode_lock(target);
+ if (is_local_mountpoint(dentry))
+ error = -EBUSY;
+ else {
+ error = security_inode_unlink(dir, dentry);
+ if (!error) {
+ error = try_break_deleg(target, delegated_inode);
+ if (error)
+ goto out;
+ error = dir->i_op->unlink(dir, dentry);
+ if (!error) {
+ dont_mount(dentry);
+ detach_mounts(dentry);
+ }
+ }
+ }
+out:
+ inode_unlock(target);
+
+ /* We don't d_delete() NFS sillyrenamed files--they still exist. */
+ if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) {
+ fsnotify_link_count(target);
+ d_delete(dentry);
+ }
+
+ return error;
+}
+EXPORT_SYMBOL(vfs_unlink2);
+
+int vfs_unlink(struct inode *dir, struct dentry *dentry, struct inode **delegated_inode)
+{
+ return vfs_unlink2(NULL, dir, dentry, delegated_inode);
+}
+EXPORT_SYMBOL(vfs_unlink);
+
+/*
+ * Make sure that the actual truncation of the file will occur outside its
+ * directory's i_mutex. Truncate can take a long time if there is a lot of
+ * writeout happening, and we don't want to prevent access to the directory
+ * while waiting on the I/O.
+ */
+static long do_unlinkat(int dfd, const char __user *pathname)
+{
+ int error;
+ struct filename *name;
+ struct dentry *dentry;
+ struct path path;
+ struct qstr last;
+ int type;
+ struct inode *inode = NULL;
+ struct inode *delegated_inode = NULL;
+ unsigned int lookup_flags = 0;
+retry:
+ name = filename_parentat(dfd, getname(pathname), lookup_flags,
+ &path, &last, &type);
+ if (IS_ERR(name))
+ return PTR_ERR(name);
+
+ error = -EISDIR;
+ if (type != LAST_NORM)
+ goto exit1;
+
+ error = mnt_want_write(path.mnt);
+ if (error)
+ goto exit1;
+retry_deleg:
+ inode_lock_nested(path.dentry->d_inode, I_MUTEX_PARENT);
+ dentry = __lookup_hash(&last, path.dentry, lookup_flags);
+ error = PTR_ERR(dentry);
+ if (!IS_ERR(dentry)) {
+ /* Why not before? Because we want correct error value */
+ if (last.name[last.len])
+ goto slashes;
+ inode = dentry->d_inode;
+ if (d_is_negative(dentry))
+ goto slashes;
+ ihold(inode);
+ error = security_path_unlink(&path, dentry);
+ if (error)
+ goto exit2;
+ error = vfs_unlink2(path.mnt, path.dentry->d_inode, dentry, &delegated_inode);
+exit2:
+ dput(dentry);
+ }
+ inode_unlock(path.dentry->d_inode);
+ if (inode)
+ iput(inode); /* truncate the inode here */
+ inode = NULL;
+ if (delegated_inode) {
+ error = break_deleg_wait(&delegated_inode);
+ if (!error)
+ goto retry_deleg;
+ }
+ mnt_drop_write(path.mnt);
+exit1:
+ path_put(&path);
+ putname(name);
+ if (retry_estale(error, lookup_flags)) {
+ lookup_flags |= LOOKUP_REVAL;
+ inode = NULL;
+ goto retry;
+ }
+ return error;
+
+slashes:
+ if (d_is_negative(dentry))
+ error = -ENOENT;
+ else if (d_is_dir(dentry))
+ error = -EISDIR;
+ else
+ error = -ENOTDIR;
+ goto exit2;
+}
+
+SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag)
+{
+ if ((flag & ~AT_REMOVEDIR) != 0)
+ return -EINVAL;
+
+ if (flag & AT_REMOVEDIR)
+ return do_rmdir(dfd, pathname);
+
+ return do_unlinkat(dfd, pathname);
+}
+
+SYSCALL_DEFINE1(unlink, const char __user *, pathname)
+{
+ return do_unlinkat(AT_FDCWD, pathname);
+}
+
+int vfs_symlink2(struct vfsmount *mnt, struct inode *dir, struct dentry *dentry, const char *oldname)
+{
+ int error = may_create(mnt, dir, dentry);
+
+ if (error)
+ return error;
+
+ if (!dir->i_op->symlink)
+ return -EPERM;
+
+ error = security_inode_symlink(dir, dentry, oldname);
+ if (error)
+ return error;
+
+ error = dir->i_op->symlink(dir, dentry, oldname);
+ if (!error)
+ fsnotify_create(dir, dentry);
+ return error;
+}
+EXPORT_SYMBOL(vfs_symlink2);
+
+int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname)
+{
+ return vfs_symlink2(NULL, dir, dentry, oldname);
+}
+EXPORT_SYMBOL(vfs_symlink);
+
+SYSCALL_DEFINE3(symlinkat, const char __user *, oldname,
+ int, newdfd, const char __user *, newname)
+{
+ int error;
+ struct filename *from;
+ struct dentry *dentry;
+ struct path path;
+ unsigned int lookup_flags = 0;
+
+ from = getname(oldname);
+ if (IS_ERR(from))
+ return PTR_ERR(from);
+retry:
+ dentry = user_path_create(newdfd, newname, &path, lookup_flags);
+ error = PTR_ERR(dentry);
+ if (IS_ERR(dentry))
+ goto out_putname;
+
+ error = security_path_symlink(&path, dentry, from->name);
+ if (!error)
+ error = vfs_symlink2(path.mnt, path.dentry->d_inode, dentry, from->name);
+ done_path_create(&path, dentry);
+ if (retry_estale(error, lookup_flags)) {
+ lookup_flags |= LOOKUP_REVAL;
+ goto retry;
+ }
+out_putname:
+ putname(from);
+ return error;
+}
+
+SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname)
+{
+ return sys_symlinkat(oldname, AT_FDCWD, newname);
+}
+
+/**
+ * vfs_link - create a new link
+ * @old_dentry: object to be linked
+ * @dir: new parent
+ * @new_dentry: where to create the new link
+ * @delegated_inode: returns inode needing a delegation break
+ *
+ * The caller must hold dir->i_mutex
+ *
+ * If vfs_link discovers a delegation on the to-be-linked file in need
+ * of breaking, it will return -EWOULDBLOCK and return a reference to the
+ * inode in delegated_inode. The caller should then break the delegation
+ * and retry. Because breaking a delegation may take a long time, the
+ * caller should drop the i_mutex before doing so.
+ *
+ * Alternatively, a caller may pass NULL for delegated_inode. This may
+ * be appropriate for callers that expect the underlying filesystem not
+ * to be NFS exported.
+ */
+int vfs_link2(struct vfsmount *mnt, struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry, struct inode **delegated_inode)
+{
+ struct inode *inode = old_dentry->d_inode;
+ unsigned max_links = dir->i_sb->s_max_links;
+ int error;
+
+ if (!inode)
+ return -ENOENT;
+
+ error = may_create(mnt, dir, new_dentry);
+ if (error)
+ return error;
+
+ if (dir->i_sb != inode->i_sb)
+ return -EXDEV;
+
+ /*
+ * A link to an append-only or immutable file cannot be created.
+ */
+ if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
+ return -EPERM;
+ /*
+ * Updating the link count will likely cause i_uid and i_gid to
+ * be writen back improperly if their true value is unknown to
+ * the vfs.
+ */
+ if (HAS_UNMAPPED_ID(inode))
+ return -EPERM;
+ if (!dir->i_op->link)
+ return -EPERM;
+ if (S_ISDIR(inode->i_mode))
+ return -EPERM;
+
+ error = security_inode_link(old_dentry, dir, new_dentry);
+ if (error)
+ return error;
+
+ inode_lock(inode);
+ /* Make sure we don't allow creating hardlink to an unlinked file */
+ if (inode->i_nlink == 0 && !(inode->i_state & I_LINKABLE))
+ error = -ENOENT;
+ else if (max_links && inode->i_nlink >= max_links)
+ error = -EMLINK;
+ else {
+ error = try_break_deleg(inode, delegated_inode);
+ if (!error)
+ error = dir->i_op->link(old_dentry, dir, new_dentry);
+ }
+
+ if (!error && (inode->i_state & I_LINKABLE)) {
+ spin_lock(&inode->i_lock);
+ inode->i_state &= ~I_LINKABLE;
+ spin_unlock(&inode->i_lock);
+ }
+ inode_unlock(inode);
+ if (!error)
+ fsnotify_link(dir, inode, new_dentry);
+ return error;
+}
+EXPORT_SYMBOL(vfs_link2);
+
+int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry, struct inode **delegated_inode)
+{
+ return vfs_link2(NULL, old_dentry, dir, new_dentry, delegated_inode);
+}
+EXPORT_SYMBOL(vfs_link);
+
+/*
+ * Hardlinks are often used in delicate situations. We avoid
+ * security-related surprises by not following symlinks on the
+ * newname. --KAB
+ *
+ * We don't follow them on the oldname either to be compatible
+ * with linux 2.0, and to avoid hard-linking to directories
+ * and other special files. --ADM
+ */
+SYSCALL_DEFINE5(linkat, int, olddfd, const char __user *, oldname,
+ int, newdfd, const char __user *, newname, int, flags)
+{
+ struct dentry *new_dentry;
+ struct path old_path, new_path;
+ struct inode *delegated_inode = NULL;
+ int how = 0;
+ int error;
+
+ if ((flags & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0)
+ return -EINVAL;
+ /*
+ * To use null names we require CAP_DAC_READ_SEARCH
+ * This ensures that not everyone will be able to create
+ * handlink using the passed filedescriptor.
+ */
+ if (flags & AT_EMPTY_PATH) {
+ if (!capable(CAP_DAC_READ_SEARCH))
+ return -ENOENT;
+ how = LOOKUP_EMPTY;
+ }
+
+ if (flags & AT_SYMLINK_FOLLOW)
+ how |= LOOKUP_FOLLOW;
+retry:
+ error = user_path_at(olddfd, oldname, how, &old_path);
+ if (error)
+ return error;
+
+ new_dentry = user_path_create(newdfd, newname, &new_path,
+ (how & LOOKUP_REVAL));
+ error = PTR_ERR(new_dentry);
+ if (IS_ERR(new_dentry))
+ goto out;
+
+ error = -EXDEV;
+ if (old_path.mnt != new_path.mnt)
+ goto out_dput;
+ error = may_linkat(&old_path);
+ if (unlikely(error))
+ goto out_dput;
+ error = security_path_link(old_path.dentry, &new_path, new_dentry);
+ if (error)
+ goto out_dput;
+ error = vfs_link2(old_path.mnt, old_path.dentry, new_path.dentry->d_inode, new_dentry, &delegated_inode);
+out_dput:
+ done_path_create(&new_path, new_dentry);
+ if (delegated_inode) {
+ error = break_deleg_wait(&delegated_inode);
+ if (!error) {
+ path_put(&old_path);
+ goto retry;
+ }
+ }
+ if (retry_estale(error, how)) {
+ path_put(&old_path);
+ how |= LOOKUP_REVAL;
+ goto retry;
+ }
+out:
+ path_put(&old_path);
+
+ return error;
+}
+
+SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname)
+{
+ return sys_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0);
+}
+
+/**
+ * vfs_rename - rename a filesystem object
+ * @old_dir: parent of source
+ * @old_dentry: source
+ * @new_dir: parent of destination
+ * @new_dentry: destination
+ * @delegated_inode: returns an inode needing a delegation break
+ * @flags: rename flags
+ *
+ * The caller must hold multiple mutexes--see lock_rename()).
+ *
+ * If vfs_rename discovers a delegation in need of breaking at either
+ * the source or destination, it will return -EWOULDBLOCK and return a
+ * reference to the inode in delegated_inode. The caller should then
+ * break the delegation and retry. Because breaking a delegation may
+ * take a long time, the caller should drop all locks before doing
+ * so.
+ *
+ * Alternatively, a caller may pass NULL for delegated_inode. This may
+ * be appropriate for callers that expect the underlying filesystem not
+ * to be NFS exported.
+ *
+ * The worst of all namespace operations - renaming directory. "Perverted"
+ * doesn't even start to describe it. Somebody in UCB had a heck of a trip...
+ * Problems:
+ *
+ * a) we can get into loop creation.
+ * b) race potential - two innocent renames can create a loop together.
+ * That's where 4.4 screws up. Current fix: serialization on
+ * sb->s_vfs_rename_mutex. We might be more accurate, but that's another
+ * story.
+ * c) we have to lock _four_ objects - parents and victim (if it exists),
+ * and source (if it is not a directory).
+ * And that - after we got ->i_mutex on parents (until then we don't know
+ * whether the target exists). Solution: try to be smart with locking
+ * order for inodes. We rely on the fact that tree topology may change
+ * only under ->s_vfs_rename_mutex _and_ that parent of the object we
+ * move will be locked. Thus we can rank directories by the tree
+ * (ancestors first) and rank all non-directories after them.
+ * That works since everybody except rename does "lock parent, lookup,
+ * lock child" and rename is under ->s_vfs_rename_mutex.
+ * HOWEVER, it relies on the assumption that any object with ->lookup()
+ * has no more than 1 dentry. If "hybrid" objects will ever appear,
+ * we'd better make sure that there's no link(2) for them.
+ * d) conversion from fhandle to dentry may come in the wrong moment - when
+ * we are removing the target. Solution: we will have to grab ->i_mutex
+ * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on
+ * ->i_mutex on parents, which works but leads to some truly excessive
+ * locking].
+ */
+int vfs_rename2(struct vfsmount *mnt,
+ struct inode *old_dir, struct dentry *old_dentry,
+ struct inode *new_dir, struct dentry *new_dentry,
+ struct inode **delegated_inode, unsigned int flags)
+{
+ int error;
+ bool is_dir = d_is_dir(old_dentry);
+ struct inode *source = old_dentry->d_inode;
+ struct inode *target = new_dentry->d_inode;
+ bool new_is_dir = false;
+ unsigned max_links = new_dir->i_sb->s_max_links;
+ struct name_snapshot old_name;
+
+ if (source == target)
+ return 0;
+
+ error = may_delete(mnt, old_dir, old_dentry, is_dir);
+ if (error)
+ return error;
+
+ if (!target) {
+ error = may_create(mnt, new_dir, new_dentry);
+ } else {
+ new_is_dir = d_is_dir(new_dentry);
+
+ if (!(flags & RENAME_EXCHANGE))
+ error = may_delete(mnt, new_dir, new_dentry, is_dir);
+ else
+ error = may_delete(mnt, new_dir, new_dentry, new_is_dir);
+ }
+ if (error)
+ return error;
+
+ if (!old_dir->i_op->rename)
+ return -EPERM;
+
+ /*
+ * If we are going to change the parent - check write permissions,
+ * we'll need to flip '..'.
+ */
+ if (new_dir != old_dir) {
+ if (is_dir) {
+ error = inode_permission2(mnt, source, MAY_WRITE);
+ if (error)
+ return error;
+ }
+ if ((flags & RENAME_EXCHANGE) && new_is_dir) {
+ error = inode_permission2(mnt, target, MAY_WRITE);
+ if (error)
+ return error;
+ }
+ }
+
+ error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry,
+ flags);
+ if (error)
+ return error;
+
+ take_dentry_name_snapshot(&old_name, old_dentry);
+ dget(new_dentry);
+ if (!is_dir || (flags & RENAME_EXCHANGE))
+ lock_two_nondirectories(source, target);
+ else if (target)
+ inode_lock(target);
+
+ error = -EBUSY;
+ if (is_local_mountpoint(old_dentry) || is_local_mountpoint(new_dentry))
+ goto out;
+
+ if (max_links && new_dir != old_dir) {
+ error = -EMLINK;
+ if (is_dir && !new_is_dir && new_dir->i_nlink >= max_links)
+ goto out;
+ if ((flags & RENAME_EXCHANGE) && !is_dir && new_is_dir &&
+ old_dir->i_nlink >= max_links)
+ goto out;
+ }
+ if (is_dir && !(flags & RENAME_EXCHANGE) && target)
+ shrink_dcache_parent(new_dentry);
+ if (!is_dir) {
+ error = try_break_deleg(source, delegated_inode);
+ if (error)
+ goto out;
+ }
+ if (target && !new_is_dir) {
+ error = try_break_deleg(target, delegated_inode);
+ if (error)
+ goto out;
+ }
+ error = old_dir->i_op->rename(old_dir, old_dentry,
+ new_dir, new_dentry, flags);
+ if (error)
+ goto out;
+
+ if (!(flags & RENAME_EXCHANGE) && target) {
+ if (is_dir)
+ target->i_flags |= S_DEAD;
+ dont_mount(new_dentry);
+ detach_mounts(new_dentry);
+ }
+ if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE)) {
+ if (!(flags & RENAME_EXCHANGE))
+ d_move(old_dentry, new_dentry);
+ else
+ d_exchange(old_dentry, new_dentry);
+ }
+out:
+ if (!is_dir || (flags & RENAME_EXCHANGE))
+ unlock_two_nondirectories(source, target);
+ else if (target)
+ inode_unlock(target);
+ dput(new_dentry);
+ if (!error) {
+ fsnotify_move(old_dir, new_dir, old_name.name, is_dir,
+ !(flags & RENAME_EXCHANGE) ? target : NULL, old_dentry);
+ if (flags & RENAME_EXCHANGE) {
+ fsnotify_move(new_dir, old_dir, old_dentry->d_name.name,
+ new_is_dir, NULL, new_dentry);
+ }
+ }
+ release_dentry_name_snapshot(&old_name);
+
+ return error;
+}
+EXPORT_SYMBOL(vfs_rename2);
+
+int vfs_rename(struct inode *old_dir, struct dentry *old_dentry,
+ struct inode *new_dir, struct dentry *new_dentry,
+ struct inode **delegated_inode, unsigned int flags)
+{
+ return vfs_rename2(NULL, old_dir, old_dentry, new_dir, new_dentry, delegated_inode, flags);
+}
+EXPORT_SYMBOL(vfs_rename);
+
+SYSCALL_DEFINE5(renameat2, int, olddfd, const char __user *, oldname,
+ int, newdfd, const char __user *, newname, unsigned int, flags)
+{
+ struct dentry *old_dentry, *new_dentry;
+ struct dentry *trap;
+ struct path old_path, new_path;
+ struct qstr old_last, new_last;
+ int old_type, new_type;
+ struct inode *delegated_inode = NULL;
+ struct filename *from;
+ struct filename *to;
+ unsigned int lookup_flags = 0, target_flags = LOOKUP_RENAME_TARGET;
+ bool should_retry = false;
+ int error;
+
+ if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT))
+ return -EINVAL;
+
+ if ((flags & (RENAME_NOREPLACE | RENAME_WHITEOUT)) &&
+ (flags & RENAME_EXCHANGE))
+ return -EINVAL;
+
+ if ((flags & RENAME_WHITEOUT) && !capable(CAP_MKNOD))
+ return -EPERM;
+
+ if (flags & RENAME_EXCHANGE)
+ target_flags = 0;
+
+retry:
+ from = filename_parentat(olddfd, getname(oldname), lookup_flags,
+ &old_path, &old_last, &old_type);
+ if (IS_ERR(from)) {
+ error = PTR_ERR(from);
+ goto exit;
+ }
+
+ to = filename_parentat(newdfd, getname(newname), lookup_flags,
+ &new_path, &new_last, &new_type);
+ if (IS_ERR(to)) {
+ error = PTR_ERR(to);
+ goto exit1;
+ }
+
+ error = -EXDEV;
+ if (old_path.mnt != new_path.mnt)
+ goto exit2;
+
+ error = -EBUSY;
+ if (old_type != LAST_NORM)
+ goto exit2;
+
+ if (flags & RENAME_NOREPLACE)
+ error = -EEXIST;
+ if (new_type != LAST_NORM)
+ goto exit2;
+
+ error = mnt_want_write(old_path.mnt);
+ if (error)
+ goto exit2;
+
+retry_deleg:
+ trap = lock_rename(new_path.dentry, old_path.dentry);
+
+ old_dentry = __lookup_hash(&old_last, old_path.dentry, lookup_flags);
+ error = PTR_ERR(old_dentry);
+ if (IS_ERR(old_dentry))
+ goto exit3;
+ /* source must exist */
+ error = -ENOENT;
+ if (d_is_negative(old_dentry))
+ goto exit4;
+ new_dentry = __lookup_hash(&new_last, new_path.dentry, lookup_flags | target_flags);
+ error = PTR_ERR(new_dentry);
+ if (IS_ERR(new_dentry))
+ goto exit4;
+ error = -EEXIST;
+ if ((flags & RENAME_NOREPLACE) && d_is_positive(new_dentry))
+ goto exit5;
+ if (flags & RENAME_EXCHANGE) {
+ error = -ENOENT;
+ if (d_is_negative(new_dentry))
+ goto exit5;
+
+ if (!d_is_dir(new_dentry)) {
+ error = -ENOTDIR;
+ if (new_last.name[new_last.len])
+ goto exit5;
+ }
+ }
+ /* unless the source is a directory trailing slashes give -ENOTDIR */
+ if (!d_is_dir(old_dentry)) {
+ error = -ENOTDIR;
+ if (old_last.name[old_last.len])
+ goto exit5;
+ if (!(flags & RENAME_EXCHANGE) && new_last.name[new_last.len])
+ goto exit5;
+ }
+ /* source should not be ancestor of target */
+ error = -EINVAL;
+ if (old_dentry == trap)
+ goto exit5;
+ /* target should not be an ancestor of source */
+ if (!(flags & RENAME_EXCHANGE))
+ error = -ENOTEMPTY;
+ if (new_dentry == trap)
+ goto exit5;
+
+ error = security_path_rename(&old_path, old_dentry,
+ &new_path, new_dentry, flags);
+ if (error)
+ goto exit5;
+ error = vfs_rename2(old_path.mnt, old_path.dentry->d_inode, old_dentry,
+ new_path.dentry->d_inode, new_dentry,
+ &delegated_inode, flags);
+exit5:
+ dput(new_dentry);
+exit4:
+ dput(old_dentry);
+exit3:
+ unlock_rename(new_path.dentry, old_path.dentry);
+ if (delegated_inode) {
+ error = break_deleg_wait(&delegated_inode);
+ if (!error)
+ goto retry_deleg;
+ }
+ mnt_drop_write(old_path.mnt);
+exit2:
+ if (retry_estale(error, lookup_flags))
+ should_retry = true;
+ path_put(&new_path);
+ putname(to);
+exit1:
+ path_put(&old_path);
+ putname(from);
+ if (should_retry) {
+ should_retry = false;
+ lookup_flags |= LOOKUP_REVAL;
+ goto retry;
+ }
+exit:
+ return error;
+}
+
+SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname,
+ int, newdfd, const char __user *, newname)
+{
+ return sys_renameat2(olddfd, oldname, newdfd, newname, 0);
+}
+
+SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname)
+{
+ return sys_renameat2(AT_FDCWD, oldname, AT_FDCWD, newname, 0);
+}
+
+int vfs_whiteout(struct inode *dir, struct dentry *dentry)
+{
+ int error = may_create(NULL, dir, dentry);
+ if (error)
+ return error;
+
+ if (!dir->i_op->mknod)
+ return -EPERM;
+
+ return dir->i_op->mknod(dir, dentry,
+ S_IFCHR | WHITEOUT_MODE, WHITEOUT_DEV);
+}
+EXPORT_SYMBOL(vfs_whiteout);
+
+int readlink_copy(char __user *buffer, int buflen, const char *link)
+{
+ int len = PTR_ERR(link);
+ if (IS_ERR(link))
+ goto out;
+
+ len = strlen(link);
+ if (len > (unsigned) buflen)
+ len = buflen;
+ if (copy_to_user(buffer, link, len))
+ len = -EFAULT;
+out:
+ return len;
+}
+
+/*
+ * A helper for ->readlink(). This should be used *ONLY* for symlinks that
+ * have ->get_link() not calling nd_jump_link(). Using (or not using) it
+ * for any given inode is up to filesystem.
+ */
+static int generic_readlink(struct dentry *dentry, char __user *buffer,
+ int buflen)
+{
+ DEFINE_DELAYED_CALL(done);
+ struct inode *inode = d_inode(dentry);
+ const char *link = inode->i_link;
+ int res;
+
+ if (!link) {
+ link = inode->i_op->get_link(dentry, inode, &done);
+ if (IS_ERR(link))
+ return PTR_ERR(link);
+ }
+ res = readlink_copy(buffer, buflen, link);
+ do_delayed_call(&done);
+ return res;
+}
+
+/**
+ * vfs_readlink - copy symlink body into userspace buffer
+ * @dentry: dentry on which to get symbolic link
+ * @buffer: user memory pointer
+ * @buflen: size of buffer
+ *
+ * Does not touch atime. That's up to the caller if necessary
+ *
+ * Does not call security hook.
+ */
+int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen)
+{
+ struct inode *inode = d_inode(dentry);
+
+ if (unlikely(!(inode->i_opflags & IOP_DEFAULT_READLINK))) {
+ if (unlikely(inode->i_op->readlink))
+ return inode->i_op->readlink(dentry, buffer, buflen);
+
+ if (!d_is_symlink(dentry))
+ return -EINVAL;
+
+ spin_lock(&inode->i_lock);
+ inode->i_opflags |= IOP_DEFAULT_READLINK;
+ spin_unlock(&inode->i_lock);
+ }
+
+ return generic_readlink(dentry, buffer, buflen);
+}
+EXPORT_SYMBOL(vfs_readlink);
+
+/**
+ * vfs_get_link - get symlink body
+ * @dentry: dentry on which to get symbolic link
+ * @done: caller needs to free returned data with this
+ *
+ * Calls security hook and i_op->get_link() on the supplied inode.
+ *
+ * It does not touch atime. That's up to the caller if necessary.
+ *
+ * Does not work on "special" symlinks like /proc/$$/fd/N
+ */
+const char *vfs_get_link(struct dentry *dentry, struct delayed_call *done)
+{
+ const char *res = ERR_PTR(-EINVAL);
+ struct inode *inode = d_inode(dentry);
+
+ if (d_is_symlink(dentry)) {
+ res = ERR_PTR(security_inode_readlink(dentry));
+ if (!res)
+ res = inode->i_op->get_link(dentry, inode, done);
+ }
+ return res;
+}
+EXPORT_SYMBOL(vfs_get_link);
+
+/* get the link contents into pagecache */
+const char *page_get_link(struct dentry *dentry, struct inode *inode,
+ struct delayed_call *callback)
+{
+ char *kaddr;
+ struct page *page;
+ struct address_space *mapping = inode->i_mapping;
+
+ if (!dentry) {
+ page = find_get_page(mapping, 0);
+ if (!page)
+ return ERR_PTR(-ECHILD);
+ if (!PageUptodate(page)) {
+ put_page(page);
+ return ERR_PTR(-ECHILD);
+ }
+ } else {
+ page = read_mapping_page(mapping, 0, NULL);
+ if (IS_ERR(page))
+ return (char*)page;
+ }
+ set_delayed_call(callback, page_put_link, page);
+ BUG_ON(mapping_gfp_mask(mapping) & __GFP_HIGHMEM);
+ kaddr = page_address(page);
+ nd_terminate_link(kaddr, inode->i_size, PAGE_SIZE - 1);
+ return kaddr;
+}
+
+EXPORT_SYMBOL(page_get_link);
+
+void page_put_link(void *arg)
+{
+ put_page(arg);
+}
+EXPORT_SYMBOL(page_put_link);
+
+int page_readlink(struct dentry *dentry, char __user *buffer, int buflen)
+{
+ DEFINE_DELAYED_CALL(done);
+ int res = readlink_copy(buffer, buflen,
+ page_get_link(dentry, d_inode(dentry),
+ &done));
+ do_delayed_call(&done);
+ return res;
+}
+EXPORT_SYMBOL(page_readlink);
+
+/*
+ * The nofs argument instructs pagecache_write_begin to pass AOP_FLAG_NOFS
+ */
+int __page_symlink(struct inode *inode, const char *symname, int len, int nofs)
+{
+ struct address_space *mapping = inode->i_mapping;
+ struct page *page;
+ void *fsdata;
+ int err;
+ unsigned int flags = 0;
+ if (nofs)
+ flags |= AOP_FLAG_NOFS;
+
+retry:
+ err = pagecache_write_begin(NULL, mapping, 0, len-1,
+ flags, &page, &fsdata);
+ if (err)
+ goto fail;
+
+ memcpy(page_address(page), symname, len-1);
+
+ err = pagecache_write_end(NULL, mapping, 0, len-1, len-1,
+ page, fsdata);
+ if (err < 0)
+ goto fail;
+ if (err < len-1)
+ goto retry;
+
+ mark_inode_dirty(inode);
+ return 0;
+fail:
+ return err;
+}
+EXPORT_SYMBOL(__page_symlink);
+
+int page_symlink(struct inode *inode, const char *symname, int len)
+{
+ return __page_symlink(inode, symname, len,
+ !mapping_gfp_constraint(inode->i_mapping, __GFP_FS));
+}
+EXPORT_SYMBOL(page_symlink);
+
+const struct inode_operations page_symlink_inode_operations = {
+ .get_link = page_get_link,
+};
+EXPORT_SYMBOL(page_symlink_inode_operations);