Subject: + __ptrace_may_access-should-not-deny-sub-threads.patch added to -mm tree
To: mgrondona@xxxxxxxx,oleg@xxxxxxxxxx,woodard@xxxxxxxxxx
From: akpm@xxxxxxxxxxxxxxxxxxxx
Date: Wed, 14 Aug 2013 15:29:19 -0700
The patch titled
Subject: __ptrace_may_access() should not deny sub-threads
has been added to the -mm tree. Its filename is
__ptrace_may_access-should-not-deny-sub-threads.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/__ptrace_may_access-should-not-deny-sub-threads.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/__ptrace_may_access-should-not-deny-sub-threads.patch
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------------------------------------------------------
From: Mark Grondona <mgrondona@xxxxxxxx>
Subject: __ptrace_may_access() should not deny sub-threads
__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>
---
kernel/ptrace.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff -puN kernel/ptrace.c~__ptrace_may_access-should-not-deny-sub-threads kernel/ptrace.c
--- a/kernel/ptrace.c~__ptrace_may_access-should-not-deny-sub-threads
+++ a/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 -mm which might be from mgrondona@xxxxxxxx are
__ptrace_may_access-should-not-deny-sub-threads.patch
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