Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 107db7c7 authored by David Howells's avatar David Howells Committed by James Morris
Browse files

CRED: Guard the setprocattr security hook against ptrace 



Guard the setprocattr security hook against ptrace by taking the target task's
cred_guard_mutex around it.  The problem is that setprocattr() may otherwise
note the lack of a debugger, and then perform an action on that basis whilst
letting a debugger attach between the two points.  Holding cred_guard_mutex
across the test and the action prevents ptrace_attach() from doing that.

Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
Signed-off-by: default avatarJames Morris <jmorris@namei.org>
parent 5e751e99

fs/proc/base.c

+6 −0
Original line number Diff line number Diff line
@@ -2128,9 +2128,15 @@ static ssize_t proc_pid_attr_write(struct file * file, const char __user * buf, 
	if (copy_from_user(page, buf, count))

		goto out_free;



	/* Guard against adverse ptrace interaction */

	length = mutex_lock_interruptible(&task->cred_guard_mutex);

	if (length < 0)

		goto out_free;



	length = security_setprocattr(task,

				      (char*)file->f_path.dentry->d_name.name,

				      (void*)page, count);

	mutex_unlock(&task->cred_guard_mutex);

out_free:

	free_page((unsigned long) page);

out: