[Feature]add MT2731_MP2_MR2_SVN388 baseline version
Change-Id: Ief04314834b31e27effab435d3ca8ba33b499059
diff --git a/src/kernel/linux/v4.14/security/yama/yama_lsm.c b/src/kernel/linux/v4.14/security/yama/yama_lsm.c
new file mode 100644
index 0000000..7d5541c
--- /dev/null
+++ b/src/kernel/linux/v4.14/security/yama/yama_lsm.c
@@ -0,0 +1,492 @@
+/*
+ * Yama Linux Security Module
+ *
+ * Author: Kees Cook <keescook@chromium.org>
+ *
+ * Copyright (C) 2010 Canonical, Ltd.
+ * Copyright (C) 2011 The Chromium OS Authors.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2, as
+ * published by the Free Software Foundation.
+ *
+ */
+
+#include <linux/lsm_hooks.h>
+#include <linux/sysctl.h>
+#include <linux/ptrace.h>
+#include <linux/prctl.h>
+#include <linux/ratelimit.h>
+#include <linux/workqueue.h>
+#include <linux/string_helpers.h>
+#include <linux/task_work.h>
+#include <linux/sched.h>
+#include <linux/spinlock.h>
+
+#define YAMA_SCOPE_DISABLED 0
+#define YAMA_SCOPE_RELATIONAL 1
+#define YAMA_SCOPE_CAPABILITY 2
+#define YAMA_SCOPE_NO_ATTACH 3
+
+static int ptrace_scope = YAMA_SCOPE_RELATIONAL;
+
+/* describe a ptrace relationship for potential exception */
+struct ptrace_relation {
+ struct task_struct *tracer;
+ struct task_struct *tracee;
+ bool invalid;
+ struct list_head node;
+ struct rcu_head rcu;
+};
+
+static LIST_HEAD(ptracer_relations);
+static DEFINE_SPINLOCK(ptracer_relations_lock);
+
+static void yama_relation_cleanup(struct work_struct *work);
+static DECLARE_WORK(yama_relation_work, yama_relation_cleanup);
+
+struct access_report_info {
+ struct callback_head work;
+ const char *access;
+ struct task_struct *target;
+ struct task_struct *agent;
+};
+
+static void __report_access(struct callback_head *work)
+{
+ struct access_report_info *info =
+ container_of(work, struct access_report_info, work);
+ char *target_cmd, *agent_cmd;
+
+ target_cmd = kstrdup_quotable_cmdline(info->target, GFP_KERNEL);
+ agent_cmd = kstrdup_quotable_cmdline(info->agent, GFP_KERNEL);
+
+ pr_notice_ratelimited(
+ "ptrace %s of \"%s\"[%d] was attempted by \"%s\"[%d]\n",
+ info->access, target_cmd, info->target->pid, agent_cmd,
+ info->agent->pid);
+
+ kfree(agent_cmd);
+ kfree(target_cmd);
+
+ put_task_struct(info->agent);
+ put_task_struct(info->target);
+ kfree(info);
+}
+
+/* defers execution because cmdline access can sleep */
+static void report_access(const char *access, struct task_struct *target,
+ struct task_struct *agent)
+{
+ struct access_report_info *info;
+ char agent_comm[sizeof(agent->comm)];
+
+ assert_spin_locked(&target->alloc_lock); /* for target->comm */
+
+ if (current->flags & PF_KTHREAD) {
+ /* I don't think kthreads call task_work_run() before exiting.
+ * Imagine angry ranting about procfs here.
+ */
+ pr_notice_ratelimited(
+ "ptrace %s of \"%s\"[%d] was attempted by \"%s\"[%d]\n",
+ access, target->comm, target->pid,
+ get_task_comm(agent_comm, agent), agent->pid);
+ return;
+ }
+
+ info = kmalloc(sizeof(*info), GFP_ATOMIC);
+ if (!info)
+ return;
+ init_task_work(&info->work, __report_access);
+ get_task_struct(target);
+ get_task_struct(agent);
+ info->access = access;
+ info->target = target;
+ info->agent = agent;
+ if (task_work_add(current, &info->work, true) == 0)
+ return; /* success */
+
+ WARN(1, "report_access called from exiting task");
+ put_task_struct(target);
+ put_task_struct(agent);
+ kfree(info);
+}
+
+/**
+ * yama_relation_cleanup - remove invalid entries from the relation list
+ *
+ */
+static void yama_relation_cleanup(struct work_struct *work)
+{
+ struct ptrace_relation *relation;
+
+ spin_lock(&ptracer_relations_lock);
+ rcu_read_lock();
+ list_for_each_entry_rcu(relation, &ptracer_relations, node) {
+ if (relation->invalid) {
+ list_del_rcu(&relation->node);
+ kfree_rcu(relation, rcu);
+ }
+ }
+ rcu_read_unlock();
+ spin_unlock(&ptracer_relations_lock);
+}
+
+/**
+ * yama_ptracer_add - add/replace an exception for this tracer/tracee pair
+ * @tracer: the task_struct of the process doing the ptrace
+ * @tracee: the task_struct of the process to be ptraced
+ *
+ * Each tracee can have, at most, one tracer registered. Each time this
+ * is called, the prior registered tracer will be replaced for the tracee.
+ *
+ * Returns 0 if relationship was added, -ve on error.
+ */
+static int yama_ptracer_add(struct task_struct *tracer,
+ struct task_struct *tracee)
+{
+ struct ptrace_relation *relation, *added;
+
+ added = kmalloc(sizeof(*added), GFP_KERNEL);
+ if (!added)
+ return -ENOMEM;
+
+ added->tracee = tracee;
+ added->tracer = tracer;
+ added->invalid = false;
+
+ spin_lock(&ptracer_relations_lock);
+ rcu_read_lock();
+ list_for_each_entry_rcu(relation, &ptracer_relations, node) {
+ if (relation->invalid)
+ continue;
+ if (relation->tracee == tracee) {
+ list_replace_rcu(&relation->node, &added->node);
+ kfree_rcu(relation, rcu);
+ goto out;
+ }
+ }
+
+ list_add_rcu(&added->node, &ptracer_relations);
+
+out:
+ rcu_read_unlock();
+ spin_unlock(&ptracer_relations_lock);
+ return 0;
+}
+
+/**
+ * yama_ptracer_del - remove exceptions related to the given tasks
+ * @tracer: remove any relation where tracer task matches
+ * @tracee: remove any relation where tracee task matches
+ */
+static void yama_ptracer_del(struct task_struct *tracer,
+ struct task_struct *tracee)
+{
+ struct ptrace_relation *relation;
+ bool marked = false;
+
+ rcu_read_lock();
+ list_for_each_entry_rcu(relation, &ptracer_relations, node) {
+ if (relation->invalid)
+ continue;
+ if (relation->tracee == tracee ||
+ (tracer && relation->tracer == tracer)) {
+ relation->invalid = true;
+ marked = true;
+ }
+ }
+ rcu_read_unlock();
+
+ if (marked)
+ schedule_work(&yama_relation_work);
+}
+
+/**
+ * yama_task_free - check for task_pid to remove from exception list
+ * @task: task being removed
+ */
+void yama_task_free(struct task_struct *task)
+{
+ yama_ptracer_del(task, task);
+}
+
+/**
+ * yama_task_prctl - check for Yama-specific prctl operations
+ * @option: operation
+ * @arg2: argument
+ * @arg3: argument
+ * @arg4: argument
+ * @arg5: argument
+ *
+ * Return 0 on success, -ve on error. -ENOSYS is returned when Yama
+ * does not handle the given option.
+ */
+int yama_task_prctl(int option, unsigned long arg2, unsigned long arg3,
+ unsigned long arg4, unsigned long arg5)
+{
+ int rc = -ENOSYS;
+ struct task_struct *myself = current;
+
+ switch (option) {
+ case PR_SET_PTRACER:
+ /* Since a thread can call prctl(), find the group leader
+ * before calling _add() or _del() on it, since we want
+ * process-level granularity of control. The tracer group
+ * leader checking is handled later when walking the ancestry
+ * at the time of PTRACE_ATTACH check.
+ */
+ rcu_read_lock();
+ if (!thread_group_leader(myself))
+ myself = rcu_dereference(myself->group_leader);
+ get_task_struct(myself);
+ rcu_read_unlock();
+
+ if (arg2 == 0) {
+ yama_ptracer_del(NULL, myself);
+ rc = 0;
+ } else if (arg2 == PR_SET_PTRACER_ANY || (int)arg2 == -1) {
+ rc = yama_ptracer_add(NULL, myself);
+ } else {
+ struct task_struct *tracer;
+
+ rcu_read_lock();
+ tracer = find_task_by_vpid(arg2);
+ if (tracer)
+ get_task_struct(tracer);
+ else
+ rc = -EINVAL;
+ rcu_read_unlock();
+
+ if (tracer) {
+ rc = yama_ptracer_add(tracer, myself);
+ put_task_struct(tracer);
+ }
+ }
+
+ put_task_struct(myself);
+ break;
+ }
+
+ return rc;
+}
+
+/**
+ * task_is_descendant - walk up a process family tree looking for a match
+ * @parent: the process to compare against while walking up from child
+ * @child: the process to start from while looking upwards for parent
+ *
+ * Returns 1 if child is a descendant of parent, 0 if not.
+ */
+static int task_is_descendant(struct task_struct *parent,
+ struct task_struct *child)
+{
+ int rc = 0;
+ struct task_struct *walker = child;
+
+ if (!parent || !child)
+ return 0;
+
+ rcu_read_lock();
+ if (!thread_group_leader(parent))
+ parent = rcu_dereference(parent->group_leader);
+ while (walker->pid > 0) {
+ if (!thread_group_leader(walker))
+ walker = rcu_dereference(walker->group_leader);
+ if (walker == parent) {
+ rc = 1;
+ break;
+ }
+ walker = rcu_dereference(walker->real_parent);
+ }
+ rcu_read_unlock();
+
+ return rc;
+}
+
+/**
+ * ptracer_exception_found - tracer registered as exception for this tracee
+ * @tracer: the task_struct of the process attempting ptrace
+ * @tracee: the task_struct of the process to be ptraced
+ *
+ * Returns 1 if tracer has a ptracer exception ancestor for tracee.
+ */
+static int ptracer_exception_found(struct task_struct *tracer,
+ struct task_struct *tracee)
+{
+ int rc = 0;
+ struct ptrace_relation *relation;
+ struct task_struct *parent = NULL;
+ bool found = false;
+
+ rcu_read_lock();
+
+ /*
+ * If there's already an active tracing relationship, then make an
+ * exception for the sake of other accesses, like process_vm_rw().
+ */
+ parent = ptrace_parent(tracee);
+ if (parent != NULL && same_thread_group(parent, tracer)) {
+ rc = 1;
+ goto unlock;
+ }
+
+ /* Look for a PR_SET_PTRACER relationship. */
+ if (!thread_group_leader(tracee))
+ tracee = rcu_dereference(tracee->group_leader);
+ list_for_each_entry_rcu(relation, &ptracer_relations, node) {
+ if (relation->invalid)
+ continue;
+ if (relation->tracee == tracee) {
+ parent = relation->tracer;
+ found = true;
+ break;
+ }
+ }
+
+ if (found && (parent == NULL || task_is_descendant(parent, tracer)))
+ rc = 1;
+
+unlock:
+ rcu_read_unlock();
+
+ return rc;
+}
+
+/**
+ * yama_ptrace_access_check - validate PTRACE_ATTACH calls
+ * @child: task that current task is attempting to ptrace
+ * @mode: ptrace attach mode
+ *
+ * Returns 0 if following the ptrace is allowed, -ve on error.
+ */
+static int yama_ptrace_access_check(struct task_struct *child,
+ unsigned int mode)
+{
+ int rc = 0;
+
+ /* require ptrace target be a child of ptracer on attach */
+ if (mode & PTRACE_MODE_ATTACH) {
+ switch (ptrace_scope) {
+ case YAMA_SCOPE_DISABLED:
+ /* No additional restrictions. */
+ break;
+ case YAMA_SCOPE_RELATIONAL:
+ rcu_read_lock();
+ if (!pid_alive(child))
+ rc = -EPERM;
+ if (!rc && !task_is_descendant(current, child) &&
+ !ptracer_exception_found(current, child) &&
+ !ns_capable(__task_cred(child)->user_ns, CAP_SYS_PTRACE))
+ rc = -EPERM;
+ rcu_read_unlock();
+ break;
+ case YAMA_SCOPE_CAPABILITY:
+ rcu_read_lock();
+ if (!ns_capable(__task_cred(child)->user_ns, CAP_SYS_PTRACE))
+ rc = -EPERM;
+ rcu_read_unlock();
+ break;
+ case YAMA_SCOPE_NO_ATTACH:
+ default:
+ rc = -EPERM;
+ break;
+ }
+ }
+
+ if (rc && (mode & PTRACE_MODE_NOAUDIT) == 0)
+ report_access("attach", child, current);
+
+ return rc;
+}
+
+/**
+ * yama_ptrace_traceme - validate PTRACE_TRACEME calls
+ * @parent: task that will become the ptracer of the current task
+ *
+ * Returns 0 if following the ptrace is allowed, -ve on error.
+ */
+int yama_ptrace_traceme(struct task_struct *parent)
+{
+ int rc = 0;
+
+ /* Only disallow PTRACE_TRACEME on more aggressive settings. */
+ switch (ptrace_scope) {
+ case YAMA_SCOPE_CAPABILITY:
+ if (!has_ns_capability(parent, current_user_ns(), CAP_SYS_PTRACE))
+ rc = -EPERM;
+ break;
+ case YAMA_SCOPE_NO_ATTACH:
+ rc = -EPERM;
+ break;
+ }
+
+ if (rc) {
+ task_lock(current);
+ report_access("traceme", current, parent);
+ task_unlock(current);
+ }
+
+ return rc;
+}
+
+static struct security_hook_list yama_hooks[] __lsm_ro_after_init = {
+ LSM_HOOK_INIT(ptrace_access_check, yama_ptrace_access_check),
+ LSM_HOOK_INIT(ptrace_traceme, yama_ptrace_traceme),
+ LSM_HOOK_INIT(task_prctl, yama_task_prctl),
+ LSM_HOOK_INIT(task_free, yama_task_free),
+};
+
+#ifdef CONFIG_SYSCTL
+static int yama_dointvec_minmax(struct ctl_table *table, int write,
+ void __user *buffer, size_t *lenp, loff_t *ppos)
+{
+ struct ctl_table table_copy;
+
+ if (write && !capable(CAP_SYS_PTRACE))
+ return -EPERM;
+
+ /* Lock the max value if it ever gets set. */
+ table_copy = *table;
+ if (*(int *)table_copy.data == *(int *)table_copy.extra2)
+ table_copy.extra1 = table_copy.extra2;
+
+ return proc_dointvec_minmax(&table_copy, write, buffer, lenp, ppos);
+}
+
+static int zero;
+static int max_scope = YAMA_SCOPE_NO_ATTACH;
+
+struct ctl_path yama_sysctl_path[] = {
+ { .procname = "kernel", },
+ { .procname = "yama", },
+ { }
+};
+
+static struct ctl_table yama_sysctl_table[] = {
+ {
+ .procname = "ptrace_scope",
+ .data = &ptrace_scope,
+ .maxlen = sizeof(int),
+ .mode = 0644,
+ .proc_handler = yama_dointvec_minmax,
+ .extra1 = &zero,
+ .extra2 = &max_scope,
+ },
+ { }
+};
+static void __init yama_init_sysctl(void)
+{
+ if (!register_sysctl_paths(yama_sysctl_path, yama_sysctl_table))
+ panic("Yama: sysctl registration failed.\n");
+}
+#else
+static inline void yama_init_sysctl(void) { }
+#endif /* CONFIG_SYSCTL */
+
+void __init yama_add_hooks(void)
+{
+ pr_info("Yama: becoming mindful.\n");
+ security_add_hooks(yama_hooks, ARRAY_SIZE(yama_hooks), "yama");
+ yama_init_sysctl();
+}