leandrof/linux
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

unix: properly account for FDs passed over unix sockets

Browse Source 
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>
This commit is contained in:
willy tarreau
2016-01-10 07:54:56 +01:00
committed by David S. Miller
parent 3e4006f0b8
commit 712f4aad40
3 changed files with 29 additions and 9 deletions
Download Patch File Download Diff File Expand all files Collapse all files

13
net/unix/garbage.c
View File

@@ -120,11 +120,11 @@ void unix_inflight(struct file *fp)
{
struct sock *s = unix_get_socket(fp);
spin_lock(&unix_gc_lock);
if (s) {
struct unix_sock *u = unix_sk(s);
spin_lock(&unix_gc_lock);
if (atomic_long_inc_return(&u->inflight) == 1) {
BUG_ON(!list_empty(&u->link));
list_add_tail(&u->link, &gc_inflight_list);
@@ -132,25 +132,28 @@ void unix_inflight(struct file *fp)
BUG_ON(list_empty(&u->link));
}
unix_tot_inflight++;
spin_unlock(&unix_gc_lock);
}
fp->f_cred->user->unix_inflight++;
spin_unlock(&unix_gc_lock);
}
void unix_notinflight(struct file *fp)
{
struct sock *s = unix_get_socket(fp);
spin_lock(&unix_gc_lock);
if (s) {
struct unix_sock *u = unix_sk(s);
spin_lock(&unix_gc_lock);
BUG_ON(list_empty(&u->link));
if (atomic_long_dec_and_test(&u->inflight))
list_del_init(&u->link);
unix_tot_inflight--;
spin_unlock(&unix_gc_lock);
}
fp->f_cred->user->unix_inflight--;
spin_unlock(&unix_gc_lock);
}
static void scan_inflight(struct sock *x, void (*func)(struct unix_sock *),