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authorDavidlohr Bueso <dave@stgolabs.net>2018-04-10 16:35:30 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2018-04-11 10:28:37 -0700
commit23c8cec8cf679b10997a512abb1e86f0cedc42ba (patch)
tree6c4e7044aef117bf202b06210fbae71fa0229889 /security/smack/smack_lsm.c
parenta280d6dc77eb6002f269d58cd47c7c7e69b617b6 (diff)
downloadlinux-23c8cec8cf679b10997a512abb1e86f0cedc42ba.tar.gz
ipc/msg: introduce msgctl(MSG_STAT_ANY)
There is a permission discrepancy when consulting msq ipc object metadata between /proc/sysvipc/msg (0444) and the MSG_STAT shmctl command. The later does permission checks for the object vs S_IRUGO. As such there can be cases where EACCESS is returned via syscall but the info is displayed anyways in the procfs files. While this might have security implications via info leaking (albeit no writing to the msq metadata), this behavior goes way back and showing all the objects regardless of the permissions was most likely an overlook - so we are stuck with it. Furthermore, modifying either the syscall or the procfs file can cause userspace programs to break (ie ipcs). Some applications require getting the procfs info (without root privileges) and can be rather slow in comparison with a syscall -- up to 500x in some reported cases for shm. This patch introduces a new MSG_STAT_ANY command such that the msq ipc object permissions are ignored, and only audited instead. In addition, I've left the lsm security hook checks in place, as if some policy can block the call, then the user has no other choice than just parsing the procfs file. Link: http://lkml.kernel.org/r/20180215162458.10059-4-dave@stgolabs.net Signed-off-by: Davidlohr Bueso <dbueso@suse.de> Reported-by: Robert Kettler <robert.kettler@outlook.com> Cc: Eric W. Biederman <ebiederm@xmission.com> Cc: Kees Cook <keescook@chromium.org> Cc: Manfred Spraul <manfred@colorfullife.com> Cc: Michael Kerrisk <mtk.manpages@gmail.com> Cc: Michal Hocko <mhocko@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'security/smack/smack_lsm.c')
-rw-r--r--security/smack/smack_lsm.c1
1 files changed, 1 insertions, 0 deletions
diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index cb36498a5076..0b414836bebd 100644
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -3230,6 +3230,7 @@ static int smack_msg_queue_msgctl(struct kern_ipc_perm *isp, int cmd)
switch (cmd) {
case IPC_STAT:
case MSG_STAT:
+ case MSG_STAT_ANY:
may = MAY_READ;
break;
case IPC_SET: