unix: properly account for FDs passed over unix sockets
It is possible for a process to allocate and accumulate far more FDs than
the process' limit by sending them over a unix socket then closing them
to keep the process' fd count low.
This change addresses this problem by keeping track of the number of FDs
in flight per user and preventing non-privileged processes from having
more FDs in flight than their configured FD limit.
Reported-by: socketpair@gmail.com
Reported-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Mitigates: CVE-2013-4312 (Linux 2.0+)
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/sched.h b/include/linux/sched.h
index edad7a4..fbf25f1 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -830,6 +830,7 @@
unsigned long mq_bytes; /* How many bytes can be allocated to mqueue? */
#endif
unsigned long locked_shm; /* How many pages of mlocked shm ? */
+ unsigned long unix_inflight; /* How many files in flight in unix sockets */
#ifdef CONFIG_KEYS
struct key *uid_keyring; /* UID specific keyring */