[3.13.y-ckt stable] Patch "security_syslog() should be called once only" has been added to staging queue
Kamal Mostafa
kamal at canonical.com
Thu Jul 23 01:59:24 UTC 2015
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-3.13.y-queue branch of the 3.13.y-ckt extended stable tree
which can be found at:
http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.13.y-queue
This patch is scheduled to be released in version 3.13.11-ckt24.
If you, or anyone else, feels it should not be added to this tree, please
reply to this email.
For more information about the 3.13.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable
Thanks.
-Kamal
------
>From ce458596648d7b79abff18cf278bd76435ad80ec Mon Sep 17 00:00:00 2001
From: Vasily Averin <vvs at 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 at virtuozzo.com>
Cc: Kees Cook <keescook at chromium.org>
Cc: Josh Boyer <jwboyer at redhat.com>
Cc: Eric Paris <eparis at redhat.com>
Signed-off-by: Andrew Morton <akpm at linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds at linux-foundation.org>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
kernel/printk/printk.c | 11 ++++-------
1 file changed, 4 insertions(+), 7 deletions(-)
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 886555f..9b6f5d2 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -383,11 +383,11 @@ 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.
@@ -397,10 +397,11 @@ 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);
}
@@ -1130,10 +1131,6 @@ 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;
--
1.9.1
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