diff mbox

[3.16.y-ckt,stable] Patch "security_syslog() should be called once only" has been added to staging queue

Message ID 1436779491-24489-1-git-send-email-luis.henriques@canonical.com
State New
Headers show

Commit Message

Luis Henriques July 13, 2015, 9:24 a.m. UTC 
This is a note to let you know that I have just added a patch titled

    security_syslog() should be called once only

to the linux-3.16.y-queue branch of the 3.16.y-ckt extended stable tree 
which can be found at:

    http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.16.y-queue

This patch is scheduled to be released in version 3.16.7-ckt15.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.16.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

From efe71f71dff3d338b6e823d5c4ca8254b4646528 Mon Sep 17 00:00:00 2001
From: Vasily Averin <vvs@virtuozzo.com>
Date: Thu, 25 Jun 2015 15:01:44 -0700
Subject: security_syslog() should be called once only

commit d194e5d666225b04c7754471df0948f645b6ab3a upstream.

The final version of commit 637241a900cb ("kmsg: honor dmesg_restrict
sysctl on /dev/kmsg") lost few hooks, as result security_syslog() are
processed incorrectly:

- open of /dev/kmsg checks syslog access permissions by using
  check_syslog_permissions() where security_syslog() is not called if
  dmesg_restrict is set.

- syslog syscall and /proc/kmsg calls do_syslog() where security_syslog
  can be executed twice (inside check_syslog_permissions() and then
  directly in do_syslog())

With this patch security_syslog() is called once only in all
syslog-related operations regardless of dmesg_restrict value.

Fixes: 637241a900cb ("kmsg: honor dmesg_restrict sysctl on /dev/kmsg")
Signed-off-by: Vasily Averin <vvs@virtuozzo.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Josh Boyer <jwboyer@redhat.com>
Cc: Eric Paris <eparis@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
---
 kernel/printk/printk.c | 11 ++++-------
 1 file changed, 4 insertions(+), 7 deletions(-)
diff mbox

Patch

diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index cce20d2f38d5..f7f6f7e5ff8a 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -478,11 +478,11 @@  static int check_syslog_permissions(int type, bool from_file)
 	 * already done the capabilities checks at open time.
 	 */
 	if (from_file && type != SYSLOG_ACTION_OPEN)
-		return 0;
+		goto ok;

 	if (syslog_action_restricted(type)) {
 		if (capable(CAP_SYSLOG))
-			return 0;
+			goto ok;
 		/*
 		 * For historical reasons, accept CAP_SYS_ADMIN too, with
 		 * a warning.
@@ -492,10 +492,11 @@  static int check_syslog_permissions(int type, bool from_file)
 				     "CAP_SYS_ADMIN but no CAP_SYSLOG "
 				     "(deprecated).\n",
 				 current->comm, task_pid_nr(current));
-			return 0;
+			goto ok;
 		}
 		return -EPERM;
 	}
+ok:
 	return security_syslog(type);
 }

@@ -1221,10 +1222,6 @@  int do_syslog(int type, char __user *buf, int len, bool from_file)
 	if (error)
 		goto out;

-	error = security_syslog(type);
-	if (error)
-		return error;
-
 	switch (type) {
 	case SYSLOG_ACTION_CLOSE:	/* Close log */
 		break;