Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755156AbbGPBMF (ORCPT ); Wed, 15 Jul 2015 21:12:05 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:56381 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755109AbbGPBMA (ORCPT ); Wed, 15 Jul 2015 21:12:00 -0400 From: Kamal Mostafa To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Vasily Averin , Kees Cook , Josh Boyer , Eric Paris , Andrew Morton , Linus Torvalds , Kamal Mostafa Subject: [PATCH 3.19.y-ckt 236/251] security_syslog() should be called once only Date: Wed, 15 Jul 2015 18:09:17 -0700 Message-Id: <1437008972-9140-237-git-send-email-kamal@canonical.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1437008972-9140-1-git-send-email-kamal@canonical.com> References: <1437008972-9140-1-git-send-email-kamal@canonical.com> X-Extended-Stable: 3.19 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2657 Lines: 85 3.19.8-ckt4 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Vasily Averin 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 Cc: Kees Cook Cc: Josh Boyer Cc: Eric Paris Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Kamal Mostafa --- 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 2cdd353..4b52ee5 100644 --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -484,11 +484,11 @@ 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. @@ -498,10 +498,11 @@ 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); } @@ -1263,10 +1264,6 @@ 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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/