From b21507e272627c434e8dd74e8d51fd8245281b59 Mon Sep 17 00:00:00 2001 From: Stephen Smalley Date: Mon, 9 Jan 2017 10:07:31 -0500 Subject: proc,security: move restriction on writing /proc/pid/attr nodes to proc Processes can only alter their own security attributes via /proc/pid/attr nodes. This is presently enforced by each individual security module and is also imposed by the Linux credentials implementation, which only allows a task to alter its own credentials. Move the check enforcing this restriction from the individual security modules to proc_pid_attr_write() before calling the security hook, and drop the unnecessary task argument to the security hook since it can only ever be the current task. Signed-off-by: Stephen Smalley Acked-by: Casey Schaufler Acked-by: John Johansen Signed-off-by: Paul Moore --- fs/proc/base.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) (limited to 'fs/proc') diff --git a/fs/proc/base.c b/fs/proc/base.c index 8e7e61b28f31..988c5a77e888 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -2488,6 +2488,12 @@ static ssize_t proc_pid_attr_write(struct file * file, const char __user * buf, length = -ESRCH; if (!task) goto out_no_task; + + /* A task may only write its own attributes. */ + length = -EACCES; + if (current != task) + goto out; + if (count > PAGE_SIZE) count = PAGE_SIZE; @@ -2503,14 +2509,13 @@ static ssize_t proc_pid_attr_write(struct file * file, const char __user * buf, } /* Guard against adverse ptrace interaction */ - length = mutex_lock_interruptible(&task->signal->cred_guard_mutex); + length = mutex_lock_interruptible(¤t->signal->cred_guard_mutex); if (length < 0) goto out_free; - length = security_setprocattr(task, - (char*)file->f_path.dentry->d_name.name, + length = security_setprocattr(file->f_path.dentry->d_name.name, page, count); - mutex_unlock(&task->signal->cred_guard_mutex); + mutex_unlock(¤t->signal->cred_guard_mutex); out_free: kfree(page); out: -- cgit v1.2.3