[T106][ZXW-22]7520V3SCV2.01.01.02P42U09_VEC_V0.8_AP_VEC origin source commit
Change-Id: Ic6e05d89ecd62fc34f82b23dcf306c93764aec4b
diff --git a/ap/os/linux/linux-3.4.x/fs/namei.c b/ap/os/linux/linux-3.4.x/fs/namei.c
new file mode 100644
index 0000000..4fc034f
--- /dev/null
+++ b/ap/os/linux/linux-3.4.x/fs/namei.c
@@ -0,0 +1,3528 @@
+/*
+ * 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/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 <asm/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.
+ */
+static int do_getname(const char __user *filename, char *page)
+{
+ int retval;
+ unsigned long len = PATH_MAX;
+
+ if (!segment_eq(get_fs(), KERNEL_DS)) {
+ if ((unsigned long) filename >= TASK_SIZE)
+ return -EFAULT;
+ if (TASK_SIZE - (unsigned long) filename < PATH_MAX)
+ len = TASK_SIZE - (unsigned long) filename;
+ }
+
+ retval = strncpy_from_user(page, filename, len);
+ if (retval > 0) {
+ if (retval < len)
+ return 0;
+ return -ENAMETOOLONG;
+ } else if (!retval)
+ retval = -ENOENT;
+ return retval;
+}
+
+static char *getname_flags(const char __user *filename, int flags, int *empty)
+{
+ char *result = __getname();
+ int retval;
+
+ if (!result)
+ return ERR_PTR(-ENOMEM);
+
+ retval = do_getname(filename, result);
+ if (retval < 0) {
+ if (retval == -ENOENT && empty)
+ *empty = 1;
+ if (retval != -ENOENT || !(flags & LOOKUP_EMPTY)) {
+ __putname(result);
+ return ERR_PTR(retval);
+ }
+ }
+ audit_getname(result);
+ return result;
+}
+
+char *getname(const char __user * filename)
+{
+ return getname_flags(filename, 0, NULL);
+}
+
+#ifdef CONFIG_AUDITSYSCALL
+void putname(const char *name)
+{
+ if (unlikely(!audit_dummy_context()))
+ audit_putname(name);
+ else
+ __putname(name);
+}
+EXPORT_SYMBOL(putname);
+#endif
+
+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 (acl == ACL_NOT_CACHED)
+ return -ECHILD;
+ return posix_acl_permission(inode, acl, mask & ~MAY_NOT_BLOCK);
+ }
+
+ acl = get_cached_acl(inode, ACL_TYPE_ACCESS);
+
+ /*
+ * A filesystem can force a ACL callback by just never filling the
+ * ACL cache. But normally you'd fill the cache either at inode
+ * instantiation time, or on the first ->get_acl call.
+ *
+ * If the filesystem doesn't have a get_acl() function at all, we'll
+ * just create the negative cache entry.
+ */
+ if (acl == ACL_NOT_CACHED) {
+ if (inode->i_op->get_acl) {
+ acl = inode->i_op->get_acl(inode, ACL_TYPE_ACCESS);
+ if (IS_ERR(acl))
+ return PTR_ERR(acl);
+ } else {
+ set_cached_acl(inode, ACL_TYPE_ACCESS, NULL);
+ return -EAGAIN;
+ }
+ }
+
+ 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 (current_user_ns() != inode_userns(inode))
+ goto other_perms;
+
+ if (likely(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;
+ }
+
+other_perms:
+ /*
+ * 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 (ns_capable(inode_userns(inode), CAP_DAC_OVERRIDE))
+ return 0;
+ if (!(mask & MAY_WRITE))
+ if (ns_capable(inode_userns(inode), CAP_DAC_READ_SEARCH))
+ return 0;
+ return -EACCES;
+ }
+ /*
+ * 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 (ns_capable(inode_userns(inode), CAP_DAC_OVERRIDE))
+ return 0;
+
+ /*
+ * Searching includes executable on directories, else just read.
+ */
+ mask &= MAY_READ | MAY_WRITE | MAY_EXEC;
+ if (mask == MAY_READ)
+ if (ns_capable(inode_userns(inode), CAP_DAC_READ_SEARCH))
+ return 0;
+
+ return -EACCES;
+}
+
+/*
+ * 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 inode *inode, int mask)
+{
+ if (unlikely(!(inode->i_opflags & IOP_FASTPERM))) {
+ 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, ...)
+ *
+ * Used to check for read/write/execute permissions on an inode.
+ * We use "fsuid" 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_permission(struct inode *inode, int mask)
+{
+ int retval;
+
+ if (unlikely(mask & MAY_WRITE)) {
+ umode_t mode = inode->i_mode;
+
+ /*
+ * Nobody gets write access to a read-only fs.
+ */
+ if (IS_RDONLY(inode) &&
+ (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode)))
+ return -EROFS;
+
+ /*
+ * Nobody gets write access to an immutable file.
+ */
+ if (IS_IMMUTABLE(inode))
+ return -EACCES;
+ }
+
+ retval = do_inode_permission(inode, mask);
+ if (retval)
+ return retval;
+
+ retval = devcgroup_inode_permission(inode, mask);
+ if (retval)
+ return retval;
+
+ return security_inode_permission(inode, mask);
+}
+
+/**
+ * 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(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(struct path *path)
+{
+ dput(path->dentry);
+ mntput(path->mnt);
+}
+EXPORT_SYMBOL(path_put);
+
+/**
+ * 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;
+
+ /* Only bind mounts can have disconnected paths */
+ if (mnt->mnt_root == mnt->mnt_sb->s_root)
+ return true;
+
+ return is_subdir(path->dentry, mnt->mnt_root);
+}
+
+/*
+ * 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 rcu-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
+ * @dentry: child of nd->path.dentry or NULL
+ * Returns: 0 on success, -ECHILD on failure
+ *
+ * unlazy_walk 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 or NULL. Must be called from rcu-walk context.
+ */
+static int unlazy_walk(struct nameidata *nd, struct dentry *dentry)
+{
+ struct fs_struct *fs = current->fs;
+ struct dentry *parent = nd->path.dentry;
+ int want_root = 0;
+
+ BUG_ON(!(nd->flags & LOOKUP_RCU));
+ if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) {
+ want_root = 1;
+ spin_lock(&fs->lock);
+ if (nd->root.mnt != fs->root.mnt ||
+ nd->root.dentry != fs->root.dentry)
+ goto err_root;
+ }
+ spin_lock(&parent->d_lock);
+ if (!dentry) {
+ if (!__d_rcu_to_refcount(parent, nd->seq))
+ goto err_parent;
+ BUG_ON(nd->inode != parent->d_inode);
+ } else {
+ if (dentry->d_parent != parent)
+ goto err_parent;
+ spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
+ if (!__d_rcu_to_refcount(dentry, nd->seq))
+ goto err_child;
+ /*
+ * If the sequence check on the child dentry passed, then
+ * the child has not been removed from its parent. This
+ * means the parent dentry must be valid and able to take
+ * a reference at this point.
+ */
+ BUG_ON(!IS_ROOT(dentry) && dentry->d_parent != parent);
+ BUG_ON(!parent->d_count);
+ parent->d_count++;
+ spin_unlock(&dentry->d_lock);
+ }
+ spin_unlock(&parent->d_lock);
+ if (want_root) {
+ path_get(&nd->root);
+ spin_unlock(&fs->lock);
+ }
+ mntget(nd->path.mnt);
+
+ rcu_read_unlock();
+ br_read_unlock(vfsmount_lock);
+ nd->flags &= ~LOOKUP_RCU;
+ return 0;
+
+err_child:
+ spin_unlock(&dentry->d_lock);
+err_parent:
+ spin_unlock(&parent->d_lock);
+err_root:
+ if (want_root)
+ spin_unlock(&fs->lock);
+ return -ECHILD;
+}
+
+/**
+ * release_open_intent - free up open intent resources
+ * @nd: pointer to nameidata
+ */
+void release_open_intent(struct nameidata *nd)
+{
+ struct file *file = nd->intent.open.file;
+
+ if (file && !IS_ERR(file)) {
+ if (file->f_path.dentry == NULL)
+ put_filp(file);
+ else
+ fput(file);
+ }
+}
+
+static inline int d_revalidate(struct dentry *dentry, struct nameidata *nd)
+{
+ return dentry->d_op->d_revalidate(dentry, nd);
+}
+
+/**
+ * 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) {
+ nd->flags &= ~LOOKUP_RCU;
+ if (!(nd->flags & LOOKUP_ROOT))
+ nd->root.mnt = NULL;
+ spin_lock(&dentry->d_lock);
+ if (unlikely(!__d_rcu_to_refcount(dentry, nd->seq))) {
+ spin_unlock(&dentry->d_lock);
+ rcu_read_unlock();
+ br_read_unlock(vfsmount_lock);
+ return -ECHILD;
+ }
+ BUG_ON(nd->inode != dentry->d_inode);
+ spin_unlock(&dentry->d_lock);
+ mntget(nd->path.mnt);
+ rcu_read_unlock();
+ br_read_unlock(vfsmount_lock);
+ }
+
+ if (likely(!(nd->flags & LOOKUP_JUMPED)))
+ return 0;
+
+ if (likely(!(dentry->d_flags & DCACHE_OP_REVALIDATE)))
+ return 0;
+
+ if (likely(!(dentry->d_sb->s_type->fs_flags & FS_REVAL_DOT)))
+ return 0;
+
+ /* Note: we do not d_invalidate() */
+ status = d_revalidate(dentry, nd);
+ if (status > 0)
+ return 0;
+
+ if (!status)
+ status = -ESTALE;
+
+ path_put(&nd->path);
+ return status;
+}
+
+static __always_inline void set_root(struct nameidata *nd)
+{
+ get_fs_root(current->fs, &nd->root);
+}
+
+static int link_path_walk(const char *, struct nameidata *);
+
+static __always_inline unsigned set_root_rcu(struct nameidata *nd)
+{
+ struct fs_struct *fs = current->fs;
+ unsigned seq, res;
+
+ do {
+ seq = read_seqcount_begin(&fs->seq);
+ nd->root = fs->root;
+ res = __read_seqcount_begin(&nd->root.dentry->d_seq);
+ } while (read_seqcount_retry(&fs->seq, seq));
+ return res;
+}
+
+static __always_inline int __vfs_follow_link(struct nameidata *nd, const char *link)
+{
+ int ret;
+
+ if (IS_ERR(link))
+ goto fail;
+
+ if (*link == '/') {
+ if (!nd->root.mnt)
+ set_root(nd);
+ path_put(&nd->path);
+ nd->path = nd->root;
+ path_get(&nd->root);
+ nd->flags |= LOOKUP_JUMPED;
+ }
+ nd->inode = nd->path.dentry->d_inode;
+
+ ret = link_path_walk(link, nd);
+ return ret;
+fail:
+ path_put(&nd->path);
+ return PTR_ERR(link);
+}
+
+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 inline void put_link(struct nameidata *nd, struct path *link, void *cookie)
+{
+ struct inode *inode = link->dentry->d_inode;
+ if (!IS_ERR(cookie) && inode->i_op->put_link)
+ inode->i_op->put_link(link->dentry, nd, cookie);
+ path_put(link);
+}
+
+static __always_inline int
+follow_link(struct path *link, struct nameidata *nd, void **p)
+{
+ int error;
+ struct dentry *dentry = link->dentry;
+
+ BUG_ON(nd->flags & LOOKUP_RCU);
+
+ if (link->mnt == nd->path.mnt)
+ mntget(link->mnt);
+
+ if (unlikely(current->total_link_count >= 40)) {
+ *p = ERR_PTR(-ELOOP); /* no ->put_link(), please */
+ path_put(&nd->path);
+ return -ELOOP;
+ }
+ cond_resched();
+ current->total_link_count++;
+
+ touch_atime(link);
+ nd_set_link(nd, NULL);
+
+ error = security_inode_follow_link(link->dentry, nd);
+ if (error) {
+ *p = ERR_PTR(error); /* no ->put_link(), please */
+ path_put(&nd->path);
+ return error;
+ }
+
+ nd->last_type = LAST_BIND;
+ *p = dentry->d_inode->i_op->follow_link(dentry, nd);
+ error = PTR_ERR(*p);
+ if (!IS_ERR(*p)) {
+ char *s = nd_get_link(nd);
+ error = 0;
+ if (s)
+ error = __vfs_follow_link(nd, s);
+ else if (nd->last_type == LAST_BIND) {
+ nd->flags |= LOOKUP_JUMPED;
+ nd->inode = nd->path.dentry->d_inode;
+ if (nd->inode->i_op->follow_link) {
+ /* stepped on a _really_ weird one */
+ path_put(&nd->path);
+ error = -ELOOP;
+ }
+ }
+ }
+ return error;
+}
+
+static int follow_up_rcu(struct path *path)
+{
+ struct mount *mnt = real_mount(path->mnt);
+ struct mount *parent;
+ struct dentry *mountpoint;
+
+ parent = mnt->mnt_parent;
+ if (&parent->mnt == path->mnt)
+ return 0;
+ mountpoint = mnt->mnt_mountpoint;
+ path->dentry = mountpoint;
+ path->mnt = &parent->mnt;
+ return 1;
+}
+
+int follow_up(struct path *path)
+{
+ struct mount *mnt = real_mount(path->mnt);
+ struct mount *parent;
+ struct dentry *mountpoint;
+
+ br_read_lock(vfsmount_lock);
+ parent = mnt->mnt_parent;
+ if (&parent->mnt == path->mnt) {
+ br_read_unlock(vfsmount_lock);
+ return 0;
+ }
+ mntget(&parent->mnt);
+ mountpoint = dget(mnt->mnt_mountpoint);
+ br_read_unlock(vfsmount_lock);
+ dput(path->dentry);
+ path->dentry = mountpoint;
+ mntput(path->mnt);
+ path->mnt = &parent->mnt;
+ return 1;
+}
+
+/*
+ * 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, unsigned flags,
+ 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 (!(flags & (LOOKUP_PARENT | LOOKUP_DIRECTORY |
+ LOOKUP_OPEN | LOOKUP_CREATE | LOOKUP_AUTOMOUNT)) &&
+ path->dentry->d_inode)
+ return -EISDIR;
+
+ current->total_link_count++;
+ if (current->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 && (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, unsigned flags)
+{
+ 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->dentry, 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 we managed to get the
+ * vfsmount_lock */
+ }
+
+ /* Handle an automount point */
+ if (managed & DCACHE_NEED_AUTOMOUNT) {
+ ret = follow_automount(path, flags, &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 = 0;
+ return ret < 0 ? ret : need_mntput;
+}
+
+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;
+}
+
+static inline bool managed_dentry_might_block(struct dentry *dentry)
+{
+ return (dentry->d_flags & DCACHE_MANAGE_TRANSIT &&
+ dentry->d_op->d_manage(dentry, 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)
+{
+ for (;;) {
+ struct mount *mounted;
+ /*
+ * Don't forget we might have a non-mountpoint managed dentry
+ * that wants to block transit.
+ */
+ if (unlikely(managed_dentry_might_block(path->dentry)))
+ return false;
+
+ if (!d_mountpoint(path->dentry))
+ break;
+
+ mounted = __lookup_mnt(path->mnt, path->dentry, 1);
+ if (!mounted)
+ break;
+ path->mnt = &mounted->mnt;
+ path->dentry = mounted->mnt.mnt_root;
+ nd->flags |= LOOKUP_JUMPED;
+ nd->seq = 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 true;
+}
+
+static void follow_mount_rcu(struct nameidata *nd)
+{
+ while (d_mountpoint(nd->path.dentry)) {
+ struct mount *mounted;
+ mounted = __lookup_mnt(nd->path.mnt, nd->path.dentry, 1);
+ if (!mounted)
+ break;
+ nd->path.mnt = &mounted->mnt;
+ nd->path.dentry = mounted->mnt.mnt_root;
+ nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq);
+ }
+}
+
+static int follow_dotdot_rcu(struct nameidata *nd)
+{
+ if (!nd->root.mnt)
+ set_root_rcu(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) {
+ struct dentry *old = nd->path.dentry;
+ struct dentry *parent = old->d_parent;
+ unsigned seq;
+
+ seq = read_seqcount_begin(&parent->d_seq);
+ if (read_seqcount_retry(&old->d_seq, nd->seq))
+ goto failed;
+ nd->path.dentry = parent;
+ nd->seq = seq;
+ if (unlikely(!path_connected(&nd->path)))
+ goto failed;
+ break;
+ }
+ if (!follow_up_rcu(&nd->path))
+ break;
+ nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq);
+ }
+ follow_mount_rcu(nd);
+ nd->inode = nd->path.dentry->d_inode;
+ return 0;
+
+failed:
+ nd->flags &= ~LOOKUP_RCU;
+ if (!(nd->flags & LOOKUP_ROOT))
+ nd->root.mnt = NULL;
+ rcu_read_unlock();
+ br_read_unlock(vfsmount_lock);
+ return -ECHILD;
+}
+
+/*
+ * 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->dentry, 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;
+}
+
+/*
+ * 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 follow_dotdot(struct nameidata *nd)
+{
+ if (!nd->root.mnt)
+ set_root(nd);
+
+ while(1) {
+ struct dentry *old = nd->path.dentry;
+
+ if (nd->path.dentry == nd->root.dentry &&
+ nd->path.mnt == nd->root.mnt) {
+ break;
+ }
+ if (nd->path.dentry != nd->path.mnt->mnt_root) {
+ /* rare case of legitimate dget_parent()... */
+ nd->path.dentry = dget_parent(nd->path.dentry);
+ dput(old);
+ if (unlikely(!path_connected(&nd->path))) {
+ path_put(&nd->path);
+ return -ENOENT;
+ }
+ 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, possibly revalidates the old dentry and
+ * allocates a new one if not found or not valid. In the need_lookup argument
+ * returns whether i_op->lookup is necessary.
+ *
+ * dir->d_inode->i_mutex must be held
+ */
+static struct dentry *lookup_dcache(struct qstr *name, struct dentry *dir,
+ struct nameidata *nd, bool *need_lookup)
+{
+ struct dentry *dentry;
+ int error;
+
+ *need_lookup = false;
+ dentry = d_lookup(dir, name);
+ if (dentry) {
+ if (d_need_lookup(dentry)) {
+ *need_lookup = true;
+ } else if (dentry->d_flags & DCACHE_OP_REVALIDATE) {
+ error = d_revalidate(dentry, nd);
+ if (unlikely(error <= 0)) {
+ if (error < 0) {
+ dput(dentry);
+ return ERR_PTR(error);
+ } else if (!d_invalidate(dentry)) {
+ dput(dentry);
+ dentry = NULL;
+ }
+ }
+ }
+ }
+
+ if (!dentry) {
+ dentry = d_alloc(dir, name);
+ if (unlikely(!dentry))
+ return ERR_PTR(-ENOMEM);
+
+ *need_lookup = true;
+ }
+ return dentry;
+}
+
+/*
+ * Call i_op->lookup on the dentry. The dentry must be negative but may be
+ * hashed if it was pouplated with DCACHE_NEED_LOOKUP.
+ *
+ * dir->d_inode->i_mutex must be held
+ */
+static struct dentry *lookup_real(struct inode *dir, struct dentry *dentry,
+ struct nameidata *nd)
+{
+ 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, nd);
+ if (unlikely(old)) {
+ dput(dentry);
+ dentry = old;
+ }
+ return dentry;
+}
+
+static struct dentry *__lookup_hash(struct qstr *name,
+ struct dentry *base, struct nameidata *nd)
+{
+ bool need_lookup;
+ struct dentry *dentry;
+
+ dentry = lookup_dcache(name, base, nd, &need_lookup);
+ if (!need_lookup)
+ return dentry;
+
+ return lookup_real(base->d_inode, dentry, nd);
+}
+
+/*
+ * It's more convoluted than I'd like it to be, but... it's still fairly
+ * small and for now I'd prefer to have fast path as straight as possible.
+ * It _is_ time-critical.
+ */
+static int do_lookup(struct nameidata *nd, struct qstr *name,
+ struct path *path, struct inode **inode)
+{
+ struct vfsmount *mnt = nd->path.mnt;
+ struct dentry *dentry, *parent = nd->path.dentry;
+ int need_reval = 1;
+ 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, we're going to
+ * do the non-racy lookup, below.
+ */
+ if (nd->flags & LOOKUP_RCU) {
+ unsigned seq;
+ *inode = nd->inode;
+ dentry = __d_lookup_rcu(parent, name, &seq, inode);
+ if (!dentry)
+ goto unlazy;
+
+ /* Memory barrier in read_seqcount_begin of child is enough */
+ if (__read_seqcount_retry(&parent->d_seq, nd->seq))
+ return -ECHILD;
+ nd->seq = seq;
+
+ if (unlikely(d_need_lookup(dentry)))
+ goto unlazy;
+ if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) {
+ status = d_revalidate(dentry, nd);
+ if (unlikely(status <= 0)) {
+ if (status != -ECHILD)
+ need_reval = 0;
+ goto unlazy;
+ }
+ }
+ path->mnt = mnt;
+ path->dentry = dentry;
+ if (unlikely(!__follow_mount_rcu(nd, path, inode)))
+ goto unlazy;
+ if (unlikely(path->dentry->d_flags & DCACHE_NEED_AUTOMOUNT))
+ goto unlazy;
+ return 0;
+unlazy:
+ if (unlazy_walk(nd, dentry))
+ return -ECHILD;
+ } else {
+ dentry = __d_lookup(parent, name);
+ }
+
+ if (unlikely(!dentry))
+ goto need_lookup;
+
+ if (unlikely(d_need_lookup(dentry))) {
+ dput(dentry);
+ goto need_lookup;
+ }
+
+ if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE) && need_reval)
+ status = d_revalidate(dentry, nd);
+ if (unlikely(status <= 0)) {
+ if (status < 0) {
+ dput(dentry);
+ return status;
+ }
+ if (!d_invalidate(dentry)) {
+ dput(dentry);
+ goto need_lookup;
+ }
+ }
+done:
+ path->mnt = mnt;
+ path->dentry = dentry;
+ err = follow_managed(path, nd->flags);
+ if (unlikely(err < 0)) {
+ path_put_conditional(path, nd);
+ return err;
+ }
+ if (err)
+ nd->flags |= LOOKUP_JUMPED;
+ *inode = path->dentry->d_inode;
+ return 0;
+
+need_lookup:
+ BUG_ON(nd->inode != parent->d_inode);
+
+ mutex_lock(&parent->d_inode->i_mutex);
+ dentry = __lookup_hash(name, parent, nd);
+ mutex_unlock(&parent->d_inode->i_mutex);
+ if (IS_ERR(dentry))
+ return PTR_ERR(dentry);
+ goto done;
+}
+
+static inline int may_lookup(struct nameidata *nd)
+{
+ if (nd->flags & LOOKUP_RCU) {
+ int err = inode_permission(nd->inode, MAY_EXEC|MAY_NOT_BLOCK);
+ if (err != -ECHILD)
+ return err;
+ if (unlazy_walk(nd, NULL))
+ return -ECHILD;
+ }
+ return inode_permission(nd->inode, MAY_EXEC);
+}
+
+static inline int handle_dots(struct nameidata *nd, int type)
+{
+ if (type == LAST_DOTDOT) {
+ if (nd->flags & LOOKUP_RCU) {
+ if (follow_dotdot_rcu(nd))
+ return -ECHILD;
+ } else
+ return follow_dotdot(nd);
+ }
+ return 0;
+}
+
+static void terminate_walk(struct nameidata *nd)
+{
+ if (!(nd->flags & LOOKUP_RCU)) {
+ path_put(&nd->path);
+ } else {
+ nd->flags &= ~LOOKUP_RCU;
+ if (!(nd->flags & LOOKUP_ROOT))
+ nd->root.mnt = NULL;
+ rcu_read_unlock();
+ br_read_unlock(vfsmount_lock);
+ }
+}
+
+/*
+ * 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 should_follow_link(struct inode *inode, int follow)
+{
+ if (unlikely(!(inode->i_opflags & IOP_NOFOLLOW))) {
+ if (likely(inode->i_op->follow_link))
+ return follow;
+
+ /* This gets set once for the inode lifetime */
+ spin_lock(&inode->i_lock);
+ inode->i_opflags |= IOP_NOFOLLOW;
+ spin_unlock(&inode->i_lock);
+ }
+ return 0;
+}
+
+static inline int walk_component(struct nameidata *nd, struct path *path,
+ struct qstr *name, int type, int follow)
+{
+ struct inode *inode;
+ 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(type != LAST_NORM))
+ return handle_dots(nd, type);
+ err = do_lookup(nd, name, path, &inode);
+ if (unlikely(err)) {
+ terminate_walk(nd);
+ return err;
+ }
+ if (!inode) {
+ path_to_nameidata(path, nd);
+ terminate_walk(nd);
+ return -ENOENT;
+ }
+ if (should_follow_link(inode, follow)) {
+ if (nd->flags & LOOKUP_RCU) {
+ if (unlikely(nd->path.mnt != path->mnt ||
+ unlazy_walk(nd, path->dentry))) {
+ terminate_walk(nd);
+ return -ECHILD;
+ }
+ }
+ BUG_ON(inode != path->dentry->d_inode);
+ return 1;
+ }
+ path_to_nameidata(path, nd);
+ nd->inode = inode;
+ return 0;
+}
+
+/*
+ * This limits recursive symlink follows to 8, while
+ * limiting consecutive symlinks to 40.
+ *
+ * Without that kind of total limit, nasty chains of consecutive
+ * symlinks can cause almost arbitrarily long lookups.
+ */
+static inline int nested_symlink(struct path *path, struct nameidata *nd)
+{
+ int res;
+
+ if (unlikely(current->link_count >= MAX_NESTED_LINKS)) {
+ path_put_conditional(path, nd);
+ path_put(&nd->path);
+ return -ELOOP;
+ }
+ BUG_ON(nd->depth >= MAX_NESTED_LINKS);
+
+ nd->depth++;
+ current->link_count++;
+
+ do {
+ struct path link = *path;
+ void *cookie;
+
+ res = follow_link(&link, nd, &cookie);
+ if (!res)
+ res = walk_component(nd, path, &nd->last,
+ nd->last_type, LOOKUP_FOLLOW);
+ put_link(nd, &link, cookie);
+ } while (res > 0);
+
+ current->link_count--;
+ nd->depth--;
+ return res;
+}
+
+/*
+ * We really don't want to look at inode->i_op->lookup
+ * when we don't have to. So we keep a cache bit in
+ * the inode ->i_opflags field that says "yes, we can
+ * do lookup on this inode".
+ */
+static inline int can_lookup(struct inode *inode)
+{
+ if (likely(inode->i_opflags & IOP_LOOKUP))
+ return 1;
+ if (likely(!inode->i_op->lookup))
+ return 0;
+
+ /* We do this once for the lifetime of the inode */
+ spin_lock(&inode->i_lock);
+ inode->i_opflags |= IOP_LOOKUP;
+ spin_unlock(&inode->i_lock);
+ return 1;
+}
+
+/*
+ * 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.
+ *
+ * - Little-endian machines (so that we can generate the mask
+ * of low bytes efficiently). Again, we *could* do a byte
+ * swapping load on big-endian architectures if that is not
+ * expensive enough to make the optimization worthless.
+ *
+ * - 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 CONFIG_64BIT
+
+static inline unsigned int fold_hash(unsigned long hash)
+{
+ hash += hash >> (8*sizeof(int));
+ return hash;
+}
+
+#else /* 32-bit case */
+
+#define fold_hash(x) (x)
+
+#endif
+
+unsigned int full_name_hash(const unsigned char *name, unsigned int len)
+{
+ unsigned long a, mask;
+ unsigned long hash = 0;
+
+ for (;;) {
+ a = load_unaligned_zeropad(name);
+ if (len < sizeof(unsigned long))
+ break;
+ hash += a;
+ hash *= 9;
+ name += sizeof(unsigned long);
+ len -= sizeof(unsigned long);
+ if (!len)
+ goto done;
+ }
+ mask = ~(~0ul << len*8);
+ hash += mask & a;
+done:
+ return fold_hash(hash);
+}
+EXPORT_SYMBOL(full_name_hash);
+
+/*
+ * Calculate the length and hash of the path component, and
+ * return the length of the component;
+ */
+static inline unsigned long hash_name(const char *name, unsigned int *hashp)
+{
+ unsigned long a, mask, hash, len;
+
+ hash = a = 0;
+ len = -sizeof(unsigned long);
+ do {
+ hash = (hash + a) * 9;
+ len += sizeof(unsigned long);
+ a = load_unaligned_zeropad(name+len);
+ /* Do we have any NUL or '/' bytes in this word? */
+ mask = has_zero(a) | has_zero(a ^ REPEAT_BYTE('/'));
+ } while (!mask);
+
+ /* The mask *below* the first high bit set */
+ mask = (mask - 1) & ~mask;
+ mask >>= 7;
+ hash += a & mask;
+ *hashp = fold_hash(hash);
+
+ return len + count_masked_bytes(mask);
+}
+
+#else
+
+unsigned int full_name_hash(const unsigned char *name, unsigned int len)
+{
+ unsigned long hash = init_name_hash();
+ while (len--)
+ hash = partial_name_hash(*name++, hash);
+ return end_name_hash(hash);
+}
+EXPORT_SYMBOL(full_name_hash);
+
+/*
+ * We know there's a real path component here of at least
+ * one character.
+ */
+static inline unsigned long hash_name(const char *name, unsigned int *hashp)
+{
+ unsigned long hash = init_name_hash();
+ 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 != '/');
+ *hashp = end_name_hash(hash);
+ return 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)
+{
+ struct path next;
+ int err;
+
+ while (*name=='/')
+ name++;
+ if (!*name)
+ return 0;
+
+ /* At this point we know we have a real path component. */
+ for(;;) {
+ struct qstr this;
+ long len;
+ int type;
+
+ err = may_lookup(nd);
+ if (err)
+ break;
+
+ len = hash_name(name, &this.hash);
+ this.name = name;
+ this.len = len;
+
+ type = LAST_NORM;
+ if (name[0] == '.') switch (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)) {
+ err = parent->d_op->d_hash(parent, nd->inode,
+ &this);
+ if (err < 0)
+ break;
+ }
+ }
+
+ if (!name[len])
+ goto last_component;
+ /*
+ * If it wasn't NUL, we know it was '/'. Skip that
+ * slash, and continue until no more slashes.
+ */
+ do {
+ len++;
+ } while (unlikely(name[len] == '/'));
+ if (!name[len])
+ goto last_component;
+ name += len;
+
+ err = walk_component(nd, &next, &this, type, LOOKUP_FOLLOW);
+ if (err < 0)
+ return err;
+
+ if (err) {
+ err = nested_symlink(&next, nd);
+ if (err)
+ return err;
+ }
+ if (can_lookup(nd->inode))
+ continue;
+ err = -ENOTDIR;
+ break;
+ /* here ends the main loop */
+
+last_component:
+ nd->last = this;
+ nd->last_type = type;
+ return 0;
+ }
+ terminate_walk(nd);
+ return err;
+}
+
+static int path_init(int dfd, const char *name, unsigned int flags,
+ struct nameidata *nd, struct file **fp)
+{
+ int retval = 0;
+ int fput_needed;
+ struct file *file;
+
+ nd->last_type = LAST_ROOT; /* if there are only slashes... */
+ nd->flags = flags | LOOKUP_JUMPED;
+ nd->depth = 0;
+ if (flags & LOOKUP_ROOT) {
+ struct inode *inode = nd->root.dentry->d_inode;
+ if (*name) {
+ if (!inode->i_op->lookup)
+ return -ENOTDIR;
+ retval = inode_permission(inode, MAY_EXEC);
+ if (retval)
+ return retval;
+ }
+ nd->path = nd->root;
+ nd->inode = inode;
+ if (flags & LOOKUP_RCU) {
+ br_read_lock(vfsmount_lock);
+ rcu_read_lock();
+ nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq);
+ } else {
+ path_get(&nd->path);
+ }
+ return 0;
+ }
+
+ nd->root.mnt = NULL;
+
+ if (*name=='/') {
+ if (flags & LOOKUP_RCU) {
+ br_read_lock(vfsmount_lock);
+ rcu_read_lock();
+ nd->seq = set_root_rcu(nd);
+ } else {
+ set_root(nd);
+ path_get(&nd->root);
+ }
+ nd->path = nd->root;
+ } else if (dfd == AT_FDCWD) {
+ if (flags & LOOKUP_RCU) {
+ struct fs_struct *fs = current->fs;
+ unsigned seq;
+
+ br_read_lock(vfsmount_lock);
+ rcu_read_lock();
+
+ do {
+ seq = read_seqcount_begin(&fs->seq);
+ nd->path = fs->pwd;
+ 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);
+ }
+ } else {
+ struct dentry *dentry;
+
+ file = fget_raw_light(dfd, &fput_needed);
+ retval = -EBADF;
+ if (!file)
+ goto out_fail;
+
+ dentry = file->f_path.dentry;
+
+ if (*name) {
+ retval = -ENOTDIR;
+ if (!S_ISDIR(dentry->d_inode->i_mode))
+ goto fput_fail;
+
+ retval = inode_permission(dentry->d_inode, MAY_EXEC);
+ if (retval)
+ goto fput_fail;
+ }
+
+ nd->path = file->f_path;
+ if (flags & LOOKUP_RCU) {
+ if (fput_needed)
+ *fp = file;
+ nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq);
+ br_read_lock(vfsmount_lock);
+ rcu_read_lock();
+ } else {
+ path_get(&file->f_path);
+ fput_light(file, fput_needed);
+ }
+ }
+
+ nd->inode = nd->path.dentry->d_inode;
+ return 0;
+
+fput_fail:
+ fput_light(file, fput_needed);
+out_fail:
+ return retval;
+}
+
+static inline int lookup_last(struct nameidata *nd, struct path *path)
+{
+ 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, path, &nd->last, nd->last_type,
+ nd->flags & LOOKUP_FOLLOW);
+}
+
+/* Returns 0 and nd will be valid on success; Retuns error, otherwise. */
+static int path_lookupat(int dfd, const char *name,
+ unsigned int flags, struct nameidata *nd)
+{
+ struct file *base = NULL;
+ struct path path;
+ int err;
+
+ /*
+ * Path walking is largely split up into 2 different synchronisation
+ * schemes, rcu-walk and ref-walk (explained in
+ * Documentation/filesystems/path-lookup.txt). These share much of the
+ * path walk code, but some things particularly setup, cleanup, and
+ * following mounts are sufficiently divergent that functions are
+ * duplicated. Typically there is a function foo(), and its RCU
+ * analogue, foo_rcu().
+ *
+ * -ECHILD is the error number of choice (just to avoid clashes) that
+ * is returned if some aspect of an rcu-walk fails. Such an error must
+ * be handled by restarting a traditional ref-walk (which will always
+ * be able to complete).
+ */
+ err = path_init(dfd, name, flags | LOOKUP_PARENT, nd, &base);
+
+ if (unlikely(err))
+ return err;
+
+ current->total_link_count = 0;
+ err = link_path_walk(name, nd);
+
+ if (!err && !(flags & LOOKUP_PARENT)) {
+ err = lookup_last(nd, &path);
+ while (err > 0) {
+ void *cookie;
+ struct path link = path;
+ nd->flags |= LOOKUP_PARENT;
+ err = follow_link(&link, nd, &cookie);
+ if (!err)
+ err = lookup_last(nd, &path);
+ put_link(nd, &link, cookie);
+ }
+ }
+
+ if (!err)
+ err = complete_walk(nd);
+
+ if (!err && nd->flags & LOOKUP_DIRECTORY) {
+ if (!nd->inode->i_op->lookup) {
+ path_put(&nd->path);
+ err = -ENOTDIR;
+ }
+ }
+
+ if (base)
+ fput(base);
+
+ if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT)) {
+ path_put(&nd->root);
+ nd->root.mnt = NULL;
+ }
+ return err;
+}
+
+static int do_path_lookup(int dfd, const char *name,
+ unsigned int flags, struct nameidata *nd)
+{
+ int retval = path_lookupat(dfd, name, flags | LOOKUP_RCU, nd);
+ if (unlikely(retval == -ECHILD))
+ retval = path_lookupat(dfd, name, flags, nd);
+ if (unlikely(retval == -ESTALE))
+ retval = path_lookupat(dfd, name, flags | LOOKUP_REVAL, nd);
+
+ if (likely(!retval)) {
+ if (unlikely(!audit_dummy_context())) {
+ if (nd->path.dentry && nd->inode)
+ audit_inode(name, nd->path.dentry);
+ }
+ }
+ return retval;
+}
+
+int kern_path_parent(const char *name, struct nameidata *nd)
+{
+ return do_path_lookup(AT_FDCWD, name, LOOKUP_PARENT, nd);
+}
+
+int kern_path(const char *name, unsigned int flags, struct path *path)
+{
+ struct nameidata nd;
+ int res = do_path_lookup(AT_FDCWD, name, flags, &nd);
+ if (!res)
+ *path = nd.path;
+ return res;
+}
+
+/**
+ * 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 nameidata nd;
+ int err;
+ nd.root.dentry = dentry;
+ nd.root.mnt = mnt;
+ BUG_ON(flags & LOOKUP_PARENT);
+ /* the first argument of do_path_lookup() is ignored with LOOKUP_ROOT */
+ err = do_path_lookup(AT_FDCWD, name, flags | LOOKUP_ROOT, &nd);
+ if (!err)
+ *path = nd.path;
+ return err;
+}
+
+/*
+ * Restricted form of lookup. Doesn't follow links, single-component only,
+ * needs parent already locked. Doesn't follow mounts.
+ * SMP-safe.
+ */
+static struct dentry *lookup_hash(struct nameidata *nd)
+{
+ return __lookup_hash(&nd->last, nd->path.dentry, nd);
+}
+
+/**
+ * lookup_one_len - 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. Also note that by using this function the
+ * nameidata argument is passed to the filesystem methods and a filesystem
+ * using this helper needs to be prepared for that.
+ */
+struct dentry *lookup_one_len(const char *name, struct dentry *base, int len)
+{
+ struct qstr this;
+ unsigned int c;
+ int err;
+
+ WARN_ON_ONCE(!mutex_is_locked(&base->d_inode->i_mutex));
+
+ this.name = name;
+ this.len = len;
+ this.hash = full_name_hash(name, len);
+ if (!len)
+ 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, base->d_inode, &this);
+ if (err < 0)
+ return ERR_PTR(err);
+ }
+
+ err = inode_permission(base->d_inode, MAY_EXEC);
+ if (err)
+ return ERR_PTR(err);
+
+ return __lookup_hash(&this, base, NULL);
+}
+
+int user_path_at_empty(int dfd, const char __user *name, unsigned flags,
+ struct path *path, int *empty)
+{
+ struct nameidata nd;
+ char *tmp = getname_flags(name, flags, empty);
+ int err = PTR_ERR(tmp);
+ if (!IS_ERR(tmp)) {
+
+ BUG_ON(flags & LOOKUP_PARENT);
+
+ err = do_path_lookup(dfd, tmp, flags, &nd);
+ putname(tmp);
+ if (!err)
+ *path = nd.path;
+ }
+ return err;
+}
+
+int user_path_at(int dfd, const char __user *name, unsigned flags,
+ struct path *path)
+{
+ return user_path_at_empty(dfd, name, flags, path, NULL);
+}
+
+static int user_path_parent(int dfd, const char __user *path,
+ struct nameidata *nd, char **name)
+{
+ char *s = getname(path);
+ int error;
+
+ if (IS_ERR(s))
+ return PTR_ERR(s);
+
+ error = do_path_lookup(dfd, s, LOOKUP_PARENT, nd);
+ if (error)
+ putname(s);
+ else
+ *name = s;
+
+ return error;
+}
+
+/*
+ * It's inline, so penalty for filesystems that don't use sticky bit is
+ * minimal.
+ */
+static inline int check_sticky(struct inode *dir, struct inode *inode)
+{
+ uid_t fsuid = current_fsuid();
+
+ if (!(dir->i_mode & S_ISVTX))
+ return 0;
+ if (current_user_ns() != inode_userns(inode))
+ goto other_userns;
+ if (inode->i_uid == fsuid)
+ return 0;
+ if (dir->i_uid == fsuid)
+ return 0;
+
+other_userns:
+ return !ns_capable(inode_userns(inode), CAP_FOWNER);
+}
+
+/*
+ * 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 we were asked to remove a directory and victim isn't one - ENOTDIR.
+ * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR.
+ * 9. We can't remove a root or mountpoint.
+ * 10. We don't allow removal of NFS sillyrenamed files; it's handled by
+ * nfs_async_unlink().
+ */
+static int may_delete(struct inode *dir,struct dentry *victim,int isdir)
+{
+ int error;
+
+ if (!victim->d_inode)
+ return -ENOENT;
+
+ BUG_ON(victim->d_parent->d_inode != dir);
+ audit_inode_child(victim, dir);
+
+ error = inode_permission(dir, MAY_WRITE | MAY_EXEC);
+ if (error)
+ return error;
+ if (IS_APPEND(dir))
+ return -EPERM;
+ if (check_sticky(dir, victim->d_inode)||IS_APPEND(victim->d_inode)||
+ IS_IMMUTABLE(victim->d_inode) || IS_SWAPFILE(victim->d_inode))
+ return -EPERM;
+ if (isdir) {
+ if (!S_ISDIR(victim->d_inode->i_mode))
+ return -ENOTDIR;
+ if (IS_ROOT(victim))
+ return -EBUSY;
+ } else if (S_ISDIR(victim->d_inode->i_mode))
+ 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 should have write and exec permissions on dir
+ * 4. We can't do it if dir is immutable (done in permission())
+ */
+static inline int may_create(struct inode *dir, struct dentry *child)
+{
+ if (child->d_inode)
+ return -EEXIST;
+ if (IS_DEADDIR(dir))
+ return -ENOENT;
+ return inode_permission(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) {
+ mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT);
+ return NULL;
+ }
+
+ mutex_lock(&p1->d_inode->i_sb->s_vfs_rename_mutex);
+
+ p = d_ancestor(p2, p1);
+ if (p) {
+ mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_PARENT);
+ mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_CHILD);
+ return p;
+ }
+
+ p = d_ancestor(p1, p2);
+ if (p) {
+ mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT);
+ mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD);
+ return p;
+ }
+
+ mutex_lock_nested(&p1->d_inode->i_mutex, I_MUTEX_PARENT);
+ mutex_lock_nested(&p2->d_inode->i_mutex, I_MUTEX_CHILD);
+ return NULL;
+}
+
+void unlock_rename(struct dentry *p1, struct dentry *p2)
+{
+ mutex_unlock(&p1->d_inode->i_mutex);
+ if (p1 != p2) {
+ mutex_unlock(&p2->d_inode->i_mutex);
+ mutex_unlock(&p1->d_inode->i_sb->s_vfs_rename_mutex);
+ }
+}
+
+int vfs_create(struct inode *dir, struct dentry *dentry, umode_t mode,
+ struct nameidata *nd)
+{
+ int error = may_create(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, nd);
+ if (!error)
+ fsnotify_create(dir, dentry);
+ return error;
+}
+
+static int may_open(struct path *path, int acc_mode, int flag)
+{
+ struct dentry *dentry = path->dentry;
+ struct inode *inode = dentry->d_inode;
+ int error;
+
+ /* O_PATH? */
+ if (!acc_mode)
+ return 0;
+
+ 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 (path->mnt->mnt_flags & MNT_NODEV)
+ return -EACCES;
+ /*FALLTHRU*/
+ case S_IFIFO:
+ case S_IFSOCK:
+ flag &= ~O_TRUNC;
+ break;
+ }
+
+ error = inode_permission(inode, 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)
+{
+ 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(inode);
+ if (!error)
+ error = security_path_truncate(path);
+ if (!error) {
+ error = do_truncate(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;
+}
+
+/*
+ * Handle the last step of open()
+ */
+static struct file *do_last(struct nameidata *nd, struct path *path,
+ const struct open_flags *op, const char *pathname)
+{
+ struct dentry *dir = nd->path.dentry;
+ struct dentry *dentry;
+ int open_flag = op->open_flag;
+ int will_truncate = open_flag & O_TRUNC;
+ int want_write = 0;
+ int acc_mode = op->acc_mode;
+ struct file *filp;
+ int error;
+
+ nd->flags &= ~LOOKUP_PARENT;
+ nd->flags |= op->intent;
+
+ switch (nd->last_type) {
+ case LAST_DOTDOT:
+ case LAST_DOT:
+ error = handle_dots(nd, nd->last_type);
+ if (error)
+ return ERR_PTR(error);
+ /* fallthrough */
+ case LAST_ROOT:
+ error = complete_walk(nd);
+ if (error)
+ return ERR_PTR(error);
+ audit_inode(pathname, nd->path.dentry);
+ if (open_flag & O_CREAT) {
+ error = -EISDIR;
+ goto exit;
+ }
+ goto ok;
+ case LAST_BIND:
+ error = complete_walk(nd);
+ if (error)
+ return ERR_PTR(error);
+ audit_inode(pathname, dir);
+ goto ok;
+ }
+
+ if (!(open_flag & O_CREAT)) {
+ int symlink_ok = 0;
+ if (nd->last.name[nd->last.len])
+ nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
+ if (open_flag & O_PATH && !(nd->flags & LOOKUP_FOLLOW))
+ symlink_ok = 1;
+ /* we _can_ be in RCU mode here */
+ error = walk_component(nd, path, &nd->last, LAST_NORM,
+ !symlink_ok);
+ if (error < 0)
+ return ERR_PTR(error);
+ if (error) /* symlink */
+ return NULL;
+ /* sayonara */
+ error = complete_walk(nd);
+ if (error)
+ return ERR_PTR(error);
+
+ error = -ENOTDIR;
+ if (nd->flags & LOOKUP_DIRECTORY) {
+ if (!nd->inode->i_op->lookup)
+ goto exit;
+ }
+ audit_inode(pathname, nd->path.dentry);
+ goto ok;
+ }
+
+ /* 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 ERR_PTR(error);
+
+ audit_inode(pathname, dir);
+ error = -EISDIR;
+ /* trailing slashes? */
+ if (nd->last.name[nd->last.len])
+ goto exit;
+
+ mutex_lock(&dir->d_inode->i_mutex);
+
+ dentry = lookup_hash(nd);
+ error = PTR_ERR(dentry);
+ if (IS_ERR(dentry)) {
+ mutex_unlock(&dir->d_inode->i_mutex);
+ goto exit;
+ }
+
+ path->dentry = dentry;
+ path->mnt = nd->path.mnt;
+
+ /* Negative dentry, just create the file */
+ if (!dentry->d_inode) {
+ umode_t mode = op->mode;
+ if (!IS_POSIXACL(dir->d_inode))
+ mode &= ~current_umask();
+ /*
+ * This write is needed to ensure that a
+ * rw->ro transition does not occur between
+ * the time when the file is created and when
+ * a permanent write count is taken through
+ * the 'struct file' in nameidata_to_filp().
+ */
+ error = mnt_want_write(nd->path.mnt);
+ if (error)
+ goto exit_mutex_unlock;
+ want_write = 1;
+ /* Don't check for write permission, don't truncate */
+ open_flag &= ~O_TRUNC;
+ will_truncate = 0;
+ acc_mode = MAY_OPEN;
+ error = security_path_mknod(&nd->path, dentry, mode, 0);
+ if (error)
+ goto exit_mutex_unlock;
+ error = vfs_create(dir->d_inode, dentry, mode, nd);
+ if (error)
+ goto exit_mutex_unlock;
+ mutex_unlock(&dir->d_inode->i_mutex);
+ dput(nd->path.dentry);
+ nd->path.dentry = dentry;
+ goto common;
+ }
+
+ /*
+ * It already exists.
+ */
+ mutex_unlock(&dir->d_inode->i_mutex);
+ audit_inode(pathname, path->dentry);
+
+ error = -EEXIST;
+ if (open_flag & O_EXCL)
+ goto exit_dput;
+
+ error = follow_managed(path, nd->flags);
+ if (error < 0)
+ goto exit_dput;
+
+ if (error)
+ nd->flags |= LOOKUP_JUMPED;
+
+ error = -ENOENT;
+ if (!path->dentry->d_inode)
+ goto exit_dput;
+
+ if (path->dentry->d_inode->i_op->follow_link)
+ return NULL;
+
+ path_to_nameidata(path, nd);
+ nd->inode = path->dentry->d_inode;
+ /* Why this, you ask? _Now_ we might have grown LOOKUP_JUMPED... */
+ error = complete_walk(nd);
+ if (error)
+ return ERR_PTR(error);
+ error = -EISDIR;
+ if (S_ISDIR(nd->inode->i_mode))
+ goto exit;
+ok:
+ if (!S_ISREG(nd->inode->i_mode))
+ will_truncate = 0;
+
+ if (will_truncate) {
+ error = mnt_want_write(nd->path.mnt);
+ if (error)
+ goto exit;
+ want_write = 1;
+ }
+common:
+ error = may_open(&nd->path, acc_mode, open_flag);
+ if (error)
+ goto exit;
+ filp = nameidata_to_filp(nd);
+ if (!IS_ERR(filp)) {
+ error = ima_file_check(filp, op->acc_mode);
+ if (error) {
+ fput(filp);
+ filp = ERR_PTR(error);
+ }
+ }
+ if (!IS_ERR(filp)) {
+ if (will_truncate) {
+ error = handle_truncate(filp);
+ if (error) {
+ fput(filp);
+ filp = ERR_PTR(error);
+ }
+ }
+ }
+out:
+ if (want_write)
+ mnt_drop_write(nd->path.mnt);
+ path_put(&nd->path);
+ return filp;
+
+exit_mutex_unlock:
+ mutex_unlock(&dir->d_inode->i_mutex);
+exit_dput:
+ path_put_conditional(path, nd);
+exit:
+ filp = ERR_PTR(error);
+ goto out;
+}
+
+static struct file *path_openat(int dfd, const char *pathname,
+ struct nameidata *nd, const struct open_flags *op, int flags)
+{
+ struct file *base = NULL;
+ struct file *filp;
+ struct path path;
+ int error;
+
+ filp = get_empty_filp();
+ if (!filp)
+ return ERR_PTR(-ENFILE);
+
+ filp->f_flags = op->open_flag;
+ nd->intent.open.file = filp;
+ nd->intent.open.flags = open_to_namei_flags(op->open_flag);
+ nd->intent.open.create_mode = op->mode;
+
+ error = path_init(dfd, pathname, flags | LOOKUP_PARENT, nd, &base);
+ if (unlikely(error))
+ goto out_filp;
+
+ current->total_link_count = 0;
+ error = link_path_walk(pathname, nd);
+ if (unlikely(error))
+ goto out_filp;
+
+ filp = do_last(nd, &path, op, pathname);
+ while (unlikely(!filp)) { /* trailing symlink */
+ struct path link = path;
+ void *cookie;
+ if (!(nd->flags & LOOKUP_FOLLOW)) {
+ path_put_conditional(&path, nd);
+ path_put(&nd->path);
+ filp = ERR_PTR(-ELOOP);
+ break;
+ }
+ nd->flags |= LOOKUP_PARENT;
+ nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL);
+ error = follow_link(&link, nd, &cookie);
+ if (unlikely(error))
+ filp = ERR_PTR(error);
+ else
+ filp = do_last(nd, &path, op, pathname);
+ put_link(nd, &link, cookie);
+ }
+out:
+ if (nd->root.mnt && !(nd->flags & LOOKUP_ROOT))
+ path_put(&nd->root);
+ if (base)
+ fput(base);
+ release_open_intent(nd);
+ return filp;
+
+out_filp:
+ filp = ERR_PTR(error);
+ goto out;
+}
+
+struct file *do_filp_open(int dfd, const char *pathname,
+ const struct open_flags *op, int flags)
+{
+ struct nameidata nd;
+ struct file *filp;
+
+ filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_RCU);
+ if (unlikely(filp == ERR_PTR(-ECHILD)))
+ filp = path_openat(dfd, pathname, &nd, op, flags);
+ if (unlikely(filp == ERR_PTR(-ESTALE)))
+ filp = path_openat(dfd, pathname, &nd, op, flags | LOOKUP_REVAL);
+ return filp;
+}
+
+struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt,
+ const char *name, const struct open_flags *op, int flags)
+{
+ struct nameidata nd;
+ struct file *file;
+
+ nd.root.mnt = mnt;
+ nd.root.dentry = dentry;
+
+ flags |= LOOKUP_ROOT;
+
+ if (dentry->d_inode->i_op->follow_link && op->intent & LOOKUP_OPEN)
+ return ERR_PTR(-ELOOP);
+
+ file = path_openat(-1, name, &nd, op, flags | LOOKUP_RCU);
+ if (unlikely(file == ERR_PTR(-ECHILD)))
+ file = path_openat(-1, name, &nd, op, flags);
+ if (unlikely(file == ERR_PTR(-ESTALE)))
+ file = path_openat(-1, name, &nd, op, flags | LOOKUP_REVAL);
+ return file;
+}
+
+struct dentry *kern_path_create(int dfd, const char *pathname, struct path *path, int is_dir)
+{
+ struct dentry *dentry = ERR_PTR(-EEXIST);
+ struct nameidata nd;
+ int error = do_path_lookup(dfd, pathname, LOOKUP_PARENT, &nd);
+ if (error)
+ return ERR_PTR(error);
+
+ /*
+ * Yucky last component or no last component at all?
+ * (foo/., foo/.., /////)
+ */
+ if (nd.last_type != LAST_NORM)
+ goto out;
+ nd.flags &= ~LOOKUP_PARENT;
+ nd.flags |= LOOKUP_CREATE | LOOKUP_EXCL;
+ nd.intent.open.flags = O_EXCL;
+
+ /*
+ * Do the final lookup.
+ */
+ mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT);
+ dentry = lookup_hash(&nd);
+ if (IS_ERR(dentry))
+ goto fail;
+
+ if (dentry->d_inode)
+ goto eexist;
+ /*
+ * 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 && nd.last.name[nd.last.len])) {
+ dput(dentry);
+ dentry = ERR_PTR(-ENOENT);
+ goto fail;
+ }
+ *path = nd.path;
+ return dentry;
+eexist:
+ dput(dentry);
+ dentry = ERR_PTR(-EEXIST);
+fail:
+ mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
+out:
+ path_put(&nd.path);
+ return dentry;
+}
+EXPORT_SYMBOL(kern_path_create);
+
+struct dentry *user_path_create(int dfd, const char __user *pathname, struct path *path, int is_dir)
+{
+ char *tmp = getname(pathname);
+ struct dentry *res;
+ if (IS_ERR(tmp))
+ return ERR_CAST(tmp);
+ res = kern_path_create(dfd, tmp, path, is_dir);
+ putname(tmp);
+ return res;
+}
+EXPORT_SYMBOL(user_path_create);
+
+int vfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev)
+{
+ int error = may_create(dir, dentry);
+
+ if (error)
+ return error;
+
+ if ((S_ISCHR(mode) || S_ISBLK(mode)) &&
+ !ns_capable(inode_userns(dir), 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;
+}
+
+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;
+
+ if (S_ISDIR(mode))
+ return -EPERM;
+
+ dentry = user_path_create(dfd, filename, &path, 0);
+ if (IS_ERR(dentry))
+ return PTR_ERR(dentry);
+
+ if (!IS_POSIXACL(path.dentry->d_inode))
+ mode &= ~current_umask();
+ error = may_mknod(mode);
+ if (error)
+ goto out_dput;
+ error = mnt_want_write(path.mnt);
+ if (error)
+ goto out_dput;
+ error = security_path_mknod(&path, dentry, mode, dev);
+ if (error)
+ goto out_drop_write;
+ switch (mode & S_IFMT) {
+ case 0: case S_IFREG:
+ error = vfs_create(path.dentry->d_inode,dentry,mode,NULL);
+ break;
+ case S_IFCHR: case S_IFBLK:
+ error = vfs_mknod(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_drop_write:
+ mnt_drop_write(path.mnt);
+out_dput:
+ dput(dentry);
+ mutex_unlock(&path.dentry->d_inode->i_mutex);
+ path_put(&path);
+
+ return error;
+}
+
+SYSCALL_DEFINE3(mknod, const char __user *, filename, umode_t, mode, unsigned, dev)
+{
+ return sys_mknodat(AT_FDCWD, filename, mode, dev);
+}
+
+int vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
+{
+ int error = may_create(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;
+}
+
+SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, umode_t, mode)
+{
+ struct dentry *dentry;
+ struct path path;
+ int error;
+
+ dentry = user_path_create(dfd, pathname, &path, 1);
+ if (IS_ERR(dentry))
+ return PTR_ERR(dentry);
+
+ if (!IS_POSIXACL(path.dentry->d_inode))
+ mode &= ~current_umask();
+ error = mnt_want_write(path.mnt);
+ if (error)
+ goto out_dput;
+ error = security_path_mkdir(&path, dentry, mode);
+ if (error)
+ goto out_drop_write;
+ error = vfs_mkdir(path.dentry->d_inode, dentry, mode);
+out_drop_write:
+ mnt_drop_write(path.mnt);
+out_dput:
+ dput(dentry);
+ mutex_unlock(&path.dentry->d_inode->i_mutex);
+ path_put(&path);
+ return error;
+}
+
+SYSCALL_DEFINE2(mkdir, const char __user *, pathname, umode_t, mode)
+{
+ return sys_mkdirat(AT_FDCWD, pathname, mode);
+}
+
+/*
+ * The dentry_unhash() helper will try to drop the dentry early: we
+ * should have a usage count of 1 if we're the only user of this
+ * dentry, and if that is true (possibly after pruning the dcache),
+ * then we drop the dentry now.
+ *
+ * A low-level filesystem can, if it choses, legally
+ * do a
+ *
+ * if (!d_unhashed(dentry))
+ * return -EBUSY;
+ *
+ * if it cannot handle the case of removing a directory
+ * that is still in use by something else..
+ */
+void dentry_unhash(struct dentry *dentry)
+{
+ shrink_dcache_parent(dentry);
+ spin_lock(&dentry->d_lock);
+ if (dentry->d_count == 1)
+ __d_drop(dentry);
+ spin_unlock(&dentry->d_lock);
+}
+
+int vfs_rmdir(struct inode *dir, struct dentry *dentry)
+{
+ int error = may_delete(dir, dentry, 1);
+
+ if (error)
+ return error;
+
+ if (!dir->i_op->rmdir)
+ return -EPERM;
+
+ dget(dentry);
+ mutex_lock(&dentry->d_inode->i_mutex);
+
+ error = -EBUSY;
+ if (d_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);
+
+out:
+ mutex_unlock(&dentry->d_inode->i_mutex);
+ dput(dentry);
+ if (!error)
+ d_delete(dentry);
+ return error;
+}
+
+static long do_rmdir(int dfd, const char __user *pathname)
+{
+ int error = 0;
+ char * name;
+ struct dentry *dentry;
+ struct nameidata nd;
+
+ error = user_path_parent(dfd, pathname, &nd, &name);
+ if (error)
+ return error;
+
+ switch(nd.last_type) {
+ case LAST_DOTDOT:
+ error = -ENOTEMPTY;
+ goto exit1;
+ case LAST_DOT:
+ error = -EINVAL;
+ goto exit1;
+ case LAST_ROOT:
+ error = -EBUSY;
+ goto exit1;
+ }
+
+ nd.flags &= ~LOOKUP_PARENT;
+
+ mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT);
+ dentry = lookup_hash(&nd);
+ error = PTR_ERR(dentry);
+ if (IS_ERR(dentry))
+ goto exit2;
+ if (!dentry->d_inode) {
+ error = -ENOENT;
+ goto exit3;
+ }
+ error = mnt_want_write(nd.path.mnt);
+ if (error)
+ goto exit3;
+ error = security_path_rmdir(&nd.path, dentry);
+ if (error)
+ goto exit4;
+ error = vfs_rmdir(nd.path.dentry->d_inode, dentry);
+exit4:
+ mnt_drop_write(nd.path.mnt);
+exit3:
+ dput(dentry);
+exit2:
+ mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
+exit1:
+ path_put(&nd.path);
+ putname(name);
+ return error;
+}
+
+SYSCALL_DEFINE1(rmdir, const char __user *, pathname)
+{
+ return do_rmdir(AT_FDCWD, pathname);
+}
+
+int vfs_unlink(struct inode *dir, struct dentry *dentry)
+{
+ int error = may_delete(dir, dentry, 0);
+
+ if (error)
+ return error;
+
+ if (!dir->i_op->unlink)
+ return -EPERM;
+
+ mutex_lock(&dentry->d_inode->i_mutex);
+ if (d_mountpoint(dentry))
+ error = -EBUSY;
+ else {
+ error = security_inode_unlink(dir, dentry);
+ if (!error) {
+ error = dir->i_op->unlink(dir, dentry);
+ if (!error)
+ dont_mount(dentry);
+ }
+ }
+ mutex_unlock(&dentry->d_inode->i_mutex);
+
+ /* We don't d_delete() NFS sillyrenamed files--they still exist. */
+ if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) {
+ fsnotify_link_count(dentry->d_inode);
+ d_delete(dentry);
+ }
+
+ return error;
+}
+
+/*
+ * 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;
+ char *name;
+ struct dentry *dentry;
+ struct nameidata nd;
+ struct inode *inode = NULL;
+
+ error = user_path_parent(dfd, pathname, &nd, &name);
+ if (error)
+ return error;
+
+ error = -EISDIR;
+ if (nd.last_type != LAST_NORM)
+ goto exit1;
+
+ nd.flags &= ~LOOKUP_PARENT;
+
+ mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT);
+ dentry = lookup_hash(&nd);
+ error = PTR_ERR(dentry);
+ if (!IS_ERR(dentry)) {
+ /* Why not before? Because we want correct error value */
+ if (nd.last.name[nd.last.len])
+ goto slashes;
+ inode = dentry->d_inode;
+ if (!inode)
+ goto slashes;
+ ihold(inode);
+ error = mnt_want_write(nd.path.mnt);
+ if (error)
+ goto exit2;
+ error = security_path_unlink(&nd.path, dentry);
+ if (error)
+ goto exit3;
+ error = vfs_unlink(nd.path.dentry->d_inode, dentry);
+exit3:
+ mnt_drop_write(nd.path.mnt);
+ exit2:
+ dput(dentry);
+ }
+ mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
+ if (inode)
+ iput(inode); /* truncate the inode here */
+exit1:
+ path_put(&nd.path);
+ putname(name);
+ return error;
+
+slashes:
+ error = !dentry->d_inode ? -ENOENT :
+ S_ISDIR(dentry->d_inode->i_mode) ? -EISDIR : -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_symlink(struct inode *dir, struct dentry *dentry, const char *oldname)
+{
+ int error = may_create(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;
+}
+
+SYSCALL_DEFINE3(symlinkat, const char __user *, oldname,
+ int, newdfd, const char __user *, newname)
+{
+ int error;
+ char *from;
+ struct dentry *dentry;
+ struct path path;
+
+ from = getname(oldname);
+ if (IS_ERR(from))
+ return PTR_ERR(from);
+
+ dentry = user_path_create(newdfd, newname, &path, 0);
+ error = PTR_ERR(dentry);
+ if (IS_ERR(dentry))
+ goto out_putname;
+
+ error = mnt_want_write(path.mnt);
+ if (error)
+ goto out_dput;
+ error = security_path_symlink(&path, dentry, from);
+ if (error)
+ goto out_drop_write;
+ error = vfs_symlink(path.dentry->d_inode, dentry, from);
+out_drop_write:
+ mnt_drop_write(path.mnt);
+out_dput:
+ dput(dentry);
+ mutex_unlock(&path.dentry->d_inode->i_mutex);
+ path_put(&path);
+out_putname:
+ putname(from);
+ return error;
+}
+
+SYSCALL_DEFINE2(symlink, const char __user *, oldname, const char __user *, newname)
+{
+ return sys_symlinkat(oldname, AT_FDCWD, newname);
+}
+
+int vfs_link(struct dentry *old_dentry, struct inode *dir, struct dentry *new_dentry)
+{
+ 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(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;
+ 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;
+
+ mutex_lock(&inode->i_mutex);
+ /* Make sure we don't allow creating hardlink to an unlinked file */
+ if (inode->i_nlink == 0)
+ error = -ENOENT;
+ else if (max_links && inode->i_nlink >= max_links)
+ error = -EMLINK;
+ else
+ error = dir->i_op->link(old_dentry, dir, new_dentry);
+ mutex_unlock(&inode->i_mutex);
+ if (!error)
+ fsnotify_link(dir, inode, new_dentry);
+ return error;
+}
+
+/*
+ * 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;
+ 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;
+
+ error = user_path_at(olddfd, oldname, how, &old_path);
+ if (error)
+ return error;
+
+ new_dentry = user_path_create(newdfd, newname, &new_path, 0);
+ 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 = mnt_want_write(new_path.mnt);
+ if (error)
+ goto out_dput;
+ error = security_path_link(old_path.dentry, &new_path, new_dentry);
+ if (error)
+ goto out_drop_write;
+ error = vfs_link(old_path.dentry, new_path.dentry->d_inode, new_dentry);
+out_drop_write:
+ mnt_drop_write(new_path.mnt);
+out_dput:
+ dput(new_dentry);
+ mutex_unlock(&new_path.dentry->d_inode->i_mutex);
+ path_put(&new_path);
+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);
+}
+
+/*
+ * 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. Check is done in is_subdir().
+ * 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 _three_ objects - parents and victim (if it exists).
+ * 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].
+ */
+static int vfs_rename_dir(struct inode *old_dir, struct dentry *old_dentry,
+ struct inode *new_dir, struct dentry *new_dentry)
+{
+ int error = 0;
+ struct inode *target = new_dentry->d_inode;
+ unsigned max_links = new_dir->i_sb->s_max_links;
+
+ /*
+ * If we are going to change the parent - check write permissions,
+ * we'll need to flip '..'.
+ */
+ if (new_dir != old_dir) {
+ error = inode_permission(old_dentry->d_inode, MAY_WRITE);
+ if (error)
+ return error;
+ }
+
+ error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry);
+ if (error)
+ return error;
+
+ dget(new_dentry);
+ if (target)
+ mutex_lock(&target->i_mutex);
+
+ error = -EBUSY;
+ if (d_mountpoint(old_dentry) || d_mountpoint(new_dentry))
+ goto out;
+
+ error = -EMLINK;
+ if (max_links && !target && new_dir != old_dir &&
+ new_dir->i_nlink >= max_links)
+ goto out;
+
+ if (target)
+ shrink_dcache_parent(new_dentry);
+ error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry);
+ if (error)
+ goto out;
+
+ if (target) {
+ target->i_flags |= S_DEAD;
+ dont_mount(new_dentry);
+ }
+out:
+ if (target)
+ mutex_unlock(&target->i_mutex);
+ dput(new_dentry);
+ if (!error)
+ if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE))
+ d_move(old_dentry,new_dentry);
+ return error;
+}
+
+static int vfs_rename_other(struct inode *old_dir, struct dentry *old_dentry,
+ struct inode *new_dir, struct dentry *new_dentry)
+{
+ struct inode *target = new_dentry->d_inode;
+ int error;
+
+ error = security_inode_rename(old_dir, old_dentry, new_dir, new_dentry);
+ if (error)
+ return error;
+
+ dget(new_dentry);
+ if (target)
+ mutex_lock(&target->i_mutex);
+
+ error = -EBUSY;
+ if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry))
+ goto out;
+
+ error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry);
+ if (error)
+ goto out;
+
+ if (target)
+ dont_mount(new_dentry);
+ if (!(old_dir->i_sb->s_type->fs_flags & FS_RENAME_DOES_D_MOVE))
+ d_move(old_dentry, new_dentry);
+out:
+ if (target)
+ mutex_unlock(&target->i_mutex);
+ dput(new_dentry);
+ return error;
+}
+
+int vfs_rename(struct inode *old_dir, struct dentry *old_dentry,
+ struct inode *new_dir, struct dentry *new_dentry)
+{
+ int error;
+ int is_dir = S_ISDIR(old_dentry->d_inode->i_mode);
+ const unsigned char *old_name;
+
+ if (old_dentry->d_inode == new_dentry->d_inode)
+ return 0;
+
+ error = may_delete(old_dir, old_dentry, is_dir);
+ if (error)
+ return error;
+
+ if (!new_dentry->d_inode)
+ error = may_create(new_dir, new_dentry);
+ else
+ error = may_delete(new_dir, new_dentry, is_dir);
+ if (error)
+ return error;
+
+ if (!old_dir->i_op->rename)
+ return -EPERM;
+
+ old_name = fsnotify_oldname_init(old_dentry->d_name.name);
+
+ if (is_dir)
+ error = vfs_rename_dir(old_dir,old_dentry,new_dir,new_dentry);
+ else
+ error = vfs_rename_other(old_dir,old_dentry,new_dir,new_dentry);
+ if (!error)
+ fsnotify_move(old_dir, new_dir, old_name, is_dir,
+ new_dentry->d_inode, old_dentry);
+ fsnotify_oldname_free(old_name);
+
+ return error;
+}
+
+SYSCALL_DEFINE4(renameat, int, olddfd, const char __user *, oldname,
+ int, newdfd, const char __user *, newname)
+{
+ struct dentry *old_dir, *new_dir;
+ struct dentry *old_dentry, *new_dentry;
+ struct dentry *trap;
+ struct nameidata oldnd, newnd;
+ char *from;
+ char *to;
+ int error;
+
+ error = user_path_parent(olddfd, oldname, &oldnd, &from);
+ if (error)
+ goto exit;
+
+ error = user_path_parent(newdfd, newname, &newnd, &to);
+ if (error)
+ goto exit1;
+
+ error = -EXDEV;
+ if (oldnd.path.mnt != newnd.path.mnt)
+ goto exit2;
+
+ old_dir = oldnd.path.dentry;
+ error = -EBUSY;
+ if (oldnd.last_type != LAST_NORM)
+ goto exit2;
+
+ new_dir = newnd.path.dentry;
+ if (newnd.last_type != LAST_NORM)
+ goto exit2;
+
+ oldnd.flags &= ~LOOKUP_PARENT;
+ newnd.flags &= ~LOOKUP_PARENT;
+ newnd.flags |= LOOKUP_RENAME_TARGET;
+
+ trap = lock_rename(new_dir, old_dir);
+
+ old_dentry = lookup_hash(&oldnd);
+ error = PTR_ERR(old_dentry);
+ if (IS_ERR(old_dentry))
+ goto exit3;
+ /* source must exist */
+ error = -ENOENT;
+ if (!old_dentry->d_inode)
+ goto exit4;
+ /* unless the source is a directory trailing slashes give -ENOTDIR */
+ if (!S_ISDIR(old_dentry->d_inode->i_mode)) {
+ error = -ENOTDIR;
+ if (oldnd.last.name[oldnd.last.len])
+ goto exit4;
+ if (newnd.last.name[newnd.last.len])
+ goto exit4;
+ }
+ /* source should not be ancestor of target */
+ error = -EINVAL;
+ if (old_dentry == trap)
+ goto exit4;
+ new_dentry = lookup_hash(&newnd);
+ error = PTR_ERR(new_dentry);
+ if (IS_ERR(new_dentry))
+ goto exit4;
+ /* target should not be an ancestor of source */
+ error = -ENOTEMPTY;
+ if (new_dentry == trap)
+ goto exit5;
+
+ error = mnt_want_write(oldnd.path.mnt);
+ if (error)
+ goto exit5;
+ error = security_path_rename(&oldnd.path, old_dentry,
+ &newnd.path, new_dentry);
+ if (error)
+ goto exit6;
+ error = vfs_rename(old_dir->d_inode, old_dentry,
+ new_dir->d_inode, new_dentry);
+exit6:
+ mnt_drop_write(oldnd.path.mnt);
+exit5:
+ dput(new_dentry);
+exit4:
+ dput(old_dentry);
+exit3:
+ unlock_rename(new_dir, old_dir);
+exit2:
+ path_put(&newnd.path);
+ putname(to);
+exit1:
+ path_put(&oldnd.path);
+ putname(from);
+exit:
+ return error;
+}
+
+SYSCALL_DEFINE2(rename, const char __user *, oldname, const char __user *, newname)
+{
+ return sys_renameat(AT_FDCWD, oldname, AT_FDCWD, newname);
+}
+
+int vfs_readlink(struct dentry *dentry, char __user *buffer, int buflen, const char *link)
+{
+ int len;
+
+ 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 ->follow_link() touching nd only in nd_set_link(). Using (or not
+ * using) it for any given inode is up to filesystem.
+ */
+int generic_readlink(struct dentry *dentry, char __user *buffer, int buflen)
+{
+ struct nameidata nd;
+ void *cookie;
+ int res;
+
+ nd.depth = 0;
+ cookie = dentry->d_inode->i_op->follow_link(dentry, &nd);
+ if (IS_ERR(cookie))
+ return PTR_ERR(cookie);
+
+ res = vfs_readlink(dentry, buffer, buflen, nd_get_link(&nd));
+ if (dentry->d_inode->i_op->put_link)
+ dentry->d_inode->i_op->put_link(dentry, &nd, cookie);
+ return res;
+}
+
+int vfs_follow_link(struct nameidata *nd, const char *link)
+{
+ return __vfs_follow_link(nd, link);
+}
+
+/* get the link contents into pagecache */
+static char *page_getlink(struct dentry * dentry, struct page **ppage)
+{
+ char *kaddr;
+ struct page *page;
+ struct address_space *mapping = dentry->d_inode->i_mapping;
+ page = read_mapping_page(mapping, 0, NULL);
+ if (IS_ERR(page))
+ return (char*)page;
+ *ppage = page;
+ kaddr = kmap(page);
+ nd_terminate_link(kaddr, dentry->d_inode->i_size, PAGE_SIZE - 1);
+ return kaddr;
+}
+
+int page_readlink(struct dentry *dentry, char __user *buffer, int buflen)
+{
+ struct page *page = NULL;
+ char *s = page_getlink(dentry, &page);
+ int res = vfs_readlink(dentry,buffer,buflen,s);
+ if (page) {
+ kunmap(page);
+ page_cache_release(page);
+ }
+ return res;
+}
+
+void *page_follow_link_light(struct dentry *dentry, struct nameidata *nd)
+{
+ struct page *page = NULL;
+ nd_set_link(nd, page_getlink(dentry, &page));
+ return page;
+}
+
+void page_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie)
+{
+ struct page *page = cookie;
+
+ if (page) {
+ kunmap(page);
+ page_cache_release(page);
+ }
+}
+
+/*
+ * 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;
+ char *kaddr;
+ unsigned int flags = AOP_FLAG_UNINTERRUPTIBLE;
+ if (nofs)
+ flags |= AOP_FLAG_NOFS;
+
+retry:
+ err = pagecache_write_begin(NULL, mapping, 0, len-1,
+ flags, &page, &fsdata);
+ if (err)
+ goto fail;
+
+ kaddr = kmap_atomic(page);
+ memcpy(kaddr, symname, len-1);
+ kunmap_atomic(kaddr);
+
+ 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;
+}
+
+int page_symlink(struct inode *inode, const char *symname, int len)
+{
+ return __page_symlink(inode, symname, len,
+ !(mapping_gfp_mask(inode->i_mapping) & __GFP_FS));
+}
+
+const struct inode_operations page_symlink_inode_operations = {
+ .readlink = generic_readlink,
+ .follow_link = page_follow_link_light,
+ .put_link = page_put_link,
+};
+
+EXPORT_SYMBOL(user_path_at);
+EXPORT_SYMBOL(follow_down_one);
+EXPORT_SYMBOL(follow_down);
+EXPORT_SYMBOL(follow_up);
+EXPORT_SYMBOL(get_write_access); /* binfmt_aout */
+EXPORT_SYMBOL(getname);
+EXPORT_SYMBOL(lock_rename);
+EXPORT_SYMBOL(lookup_one_len);
+EXPORT_SYMBOL(page_follow_link_light);
+EXPORT_SYMBOL(page_put_link);
+EXPORT_SYMBOL(page_readlink);
+EXPORT_SYMBOL(__page_symlink);
+EXPORT_SYMBOL(page_symlink);
+EXPORT_SYMBOL(page_symlink_inode_operations);
+EXPORT_SYMBOL(kern_path);
+EXPORT_SYMBOL(vfs_path_lookup);
+EXPORT_SYMBOL(inode_permission);
+EXPORT_SYMBOL(unlock_rename);
+EXPORT_SYMBOL(vfs_create);
+EXPORT_SYMBOL(vfs_follow_link);
+EXPORT_SYMBOL(vfs_link);
+EXPORT_SYMBOL(vfs_mkdir);
+EXPORT_SYMBOL(vfs_mknod);
+EXPORT_SYMBOL(generic_permission);
+EXPORT_SYMBOL(vfs_readlink);
+EXPORT_SYMBOL(vfs_rename);
+EXPORT_SYMBOL(vfs_rmdir);
+EXPORT_SYMBOL(vfs_symlink);
+EXPORT_SYMBOL(vfs_unlink);
+EXPORT_SYMBOL(dentry_unhash);
+EXPORT_SYMBOL(generic_readlink);