[PATCH 3.10 14/16] security: let security modules use PTRACE_MODE_* with bitmasks

[Willy Tarreau <w@1wt.eu>]

From: Jann Horn <jann@thejh.net>

commit 3dfb7d8cdbc7ea0c2970450e60818bb3eefbad69 upstream.

It looks like smack and yama weren't aware that the ptrace mode
can have flags ORed into it - PTRACE_MODE_NOAUDIT until now, but
only for /proc/$pid/stat, and with the PTRACE_MODE_*CREDS patch,
all modes have flags ORed into them.

Signed-off-by: Jann Horn <jann@thejh.net>
Acked-by: Kees Cook <keescook@chromium.org>
Acked-by: Casey Schaufler <casey@schaufler-ca.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Morris <james.l.morris@oracle.com>
Cc: "Serge E. Hallyn" <serge.hallyn@ubuntu.com>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Willy Tarreau <w@1wt.eu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
[wt: no smk_ptrace_mode() in 3.10]
Signed-off-by: Willy Tarreau <w@1wt.eu>
---
 security/yama/yama_lsm.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/security/yama/yama_lsm.c b/security/yama/yama_lsm.c
index 13c88fbc..0038834 100644
--- a/security/yama/yama_lsm.c
+++ b/security/yama/yama_lsm.c
@@ -292,7 +292,7 @@ int yama_ptrace_access_check(struct task_struct *child,
 		return rc;
 
 	/* require ptrace target be a child of ptracer on attach */
-	if (mode == PTRACE_MODE_ATTACH) {
+	if (mode & PTRACE_MODE_ATTACH) {
 		switch (ptrace_scope) {
 		case YAMA_SCOPE_DISABLED:
 			/* No additional restrictions. */
@@ -318,7 +318,7 @@ int yama_ptrace_access_check(struct task_struct *child,
 		}
 	}
 
-	if (rc) {
+	if (rc && (mode & PTRACE_MODE_NOAUDIT) == 0) {
 		printk_ratelimited(KERN_NOTICE
 			"ptrace of pid %d was attempted by: %s (pid %d)\n",
 			child->pid, current->comm, current->pid);
-- 
2.8.0.rc2.1.gbe9624a