X-Git-Url: http://plrg.eecs.uci.edu/git/?a=blobdiff_plain;f=kernel%2Ffork.c;h=b0663950634b332526d3bd28074953e1369361c9;hb=73cc56277c42fd13bed3921b07c84ac4b030321a;hp=2c76e11ba9390a6351906406699a07f8af53a2fa;hpb=0ee8bb9c4864ee826e6c669f230562cd0fed8722;p=firefly-linux-kernel-4.4.55.git

diff --git a/kernel/fork.c b/kernel/fork.c
index 2c76e11ba939..b0663950634b 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -198,6 +198,9 @@ struct kmem_cache *vm_area_cachep;
 /* SLAB cache for mm_struct structures (tsk->mm) */
 static struct kmem_cache *mm_cachep;
 
+/* Notifier list called when a task struct is freed */
+static ATOMIC_NOTIFIER_HEAD(task_free_notifier);
+
 static void account_kernel_stack(struct thread_info *ti, int account)
 {
 	struct zone *zone = page_zone(virt_to_page(ti));
@@ -231,6 +234,18 @@ static inline void put_signal_struct(struct signal_struct *sig)
 		free_signal_struct(sig);
 }
 
+int task_free_register(struct notifier_block *n)
+{
+	return atomic_notifier_chain_register(&task_free_notifier, n);
+}
+EXPORT_SYMBOL(task_free_register);
+
+int task_free_unregister(struct notifier_block *n)
+{
+	return atomic_notifier_chain_unregister(&task_free_notifier, n);
+}
+EXPORT_SYMBOL(task_free_unregister);
+
 void __put_task_struct(struct task_struct *tsk)
 {
 	WARN_ON(!tsk->exit_state);
@@ -242,6 +257,7 @@ void __put_task_struct(struct task_struct *tsk)
 	delayacct_tsk_free(tsk);
 	put_signal_struct(tsk->signal);
 
+	atomic_notifier_call_chain(&task_free_notifier, 0, tsk);
 	if (!profile_handoff_task(tsk))
 		free_task(tsk);
 }
@@ -311,6 +327,15 @@ static struct task_struct *dup_task_struct(struct task_struct *orig)
 		goto free_ti;
 
 	tsk->stack = ti;
+#ifdef CONFIG_SECCOMP
+	/*
+	 * We must handle setting up seccomp filters once we're under
+	 * the sighand lock in case orig has changed between now and
+	 * then. Until then, filter must be NULL to avoid messing up
+	 * the usage counts on the error path calling free_task.
+	 */
+	tsk->seccomp.filter = NULL;
+#endif
 
 	setup_thread_stack(tsk, orig);
 	clear_user_return_notifier(tsk);
@@ -697,7 +722,8 @@ struct mm_struct *mm_access(struct task_struct *task, unsigned int mode)
 
 	mm = get_task_mm(task);
 	if (mm && mm != current->mm &&
-			!ptrace_may_access(task, mode)) {
+			!ptrace_may_access(task, mode) &&
+			!capable(CAP_SYS_RESOURCE)) {
 		mmput(mm);
 		mm = ERR_PTR(-EACCES);
 	}
@@ -1091,6 +1117,39 @@ static void copy_flags(unsigned long clone_flags, struct task_struct *p)
 	p->flags = new_flags;
 }
 
+static void copy_seccomp(struct task_struct *p)
+{
+#ifdef CONFIG_SECCOMP
+	/*
+	 * Must be called with sighand->lock held, which is common to
+	 * all threads in the group. Holding cred_guard_mutex is not
+	 * needed because this new task is not yet running and cannot
+	 * be racing exec.
+	 */
+	assert_spin_locked(&current->sighand->siglock);
+
+	/* Ref-count the new filter user, and assign it. */
+	get_seccomp_filter(current);
+	p->seccomp = current->seccomp;
+
+	/*
+	 * Explicitly enable no_new_privs here in case it got set
+	 * between the task_struct being duplicated and holding the
+	 * sighand lock. The seccomp state and nnp must be in sync.
+	 */
+	if (task_no_new_privs(current))
+		task_set_no_new_privs(p);
+
+	/*
+	 * If the parent gained a seccomp mode after copying thread
+	 * flags and between before we held the sighand lock, we have
+	 * to manually enable the seccomp thread flag here.
+	 */
+	if (p->seccomp.mode != SECCOMP_MODE_DISABLED)
+		set_tsk_thread_flag(p, TIF_SECCOMP);
+#endif
+}
+
 SYSCALL_DEFINE1(set_tid_address, int __user *, tidptr)
 {
 	current->clear_child_tid = tidptr;
@@ -1195,7 +1254,6 @@ static struct task_struct *copy_process(unsigned long clone_flags,
 		goto fork_out;
 
 	ftrace_graph_init_task(p);
-	get_seccomp_filter(p);
 
 	rt_mutex_init_task(p);
 
@@ -1324,7 +1382,7 @@ static struct task_struct *copy_process(unsigned long clone_flags,
 		goto bad_fork_cleanup_policy;
 	retval = audit_alloc(p);
 	if (retval)
-		goto bad_fork_cleanup_policy;
+		goto bad_fork_cleanup_perf;
 	/* copy all the process information */
 	retval = copy_semundo(clone_flags, p);
 	if (retval)
@@ -1437,6 +1495,12 @@ static struct task_struct *copy_process(unsigned long clone_flags,
 
 	spin_lock(&current->sighand->siglock);
 
+	/*
+	 * Copy seccomp details explicitly here, in case they were changed
+	 * before holding sighand lock.
+	 */
+	copy_seccomp(p);
+
 	/*
 	 * Process group and session signals need to be delivered to just the
 	 * parent before the fork or both the parent and the child after the
@@ -1522,8 +1586,9 @@ bad_fork_cleanup_semundo:
 	exit_sem(p);
 bad_fork_cleanup_audit:
 	audit_free(p);
-bad_fork_cleanup_policy:
+bad_fork_cleanup_perf:
 	perf_event_free_task(p);
+bad_fork_cleanup_policy:
 #ifdef CONFIG_NUMA
 	mpol_put(p->mempolicy);
 bad_fork_cleanup_cgroup: