This is a note to let you know that I've just added the patch titled
__ptrace_may_access() should not deny sub-threads
to the 3.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
__ptrace_may_access-should-not-deny-sub-threads.patch
and it can be found in the queue-3.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 73af963f9f3036dffed55c3a2898598186db1045 Mon Sep 17 00:00:00 2001
From: Mark Grondona <mgrondona@xxxxxxxx>
Date: Wed, 11 Sep 2013 14:24:31 -0700
Subject: __ptrace_may_access() should not deny sub-threads
From: Mark Grondona <mgrondona@xxxxxxxx>
commit 73af963f9f3036dffed55c3a2898598186db1045 upstream.
__ptrace_may_access() checks get_dumpable/ptrace_has_cap/etc if task !=
current, this can can lead to surprising results.
For example, a sub-thread can't readlink("/proc/self/exe") if the
executable is not readable. setup_new_exec()->would_dump() notices that
inode_permission(MAY_READ) fails and then it does
set_dumpable(suid_dumpable). After that get_dumpable() fails.
(It is not clear why proc_pid_readlink() checks get_dumpable(), perhaps we
could add PTRACE_MODE_NODUMPABLE)
Change __ptrace_may_access() to use same_thread_group() instead of "task
== current". Any security check is pointless when the tasks share the
same ->mm.
Signed-off-by: Mark Grondona <mgrondona@xxxxxxxx>
Signed-off-by: Ben Woodard <woodard@xxxxxxxxxx>
Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
kernel/ptrace.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -236,7 +236,7 @@ static int __ptrace_may_access(struct ta
*/
int dumpable = 0;
/* Don't let security modules deny introspection */
- if (task == current)
+ if (same_thread_group(task, current))
return 0;
rcu_read_lock();
tcred = __task_cred(task);
Patches currently in stable-queue which might be from mgrondona@xxxxxxxx are
queue-3.10/__ptrace_may_access-should-not-deny-sub-threads.patch
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