Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751491AbbEXQUK (ORCPT ); Sun, 24 May 2015 12:20:10 -0400 Received: from mailhub.sw.ru ([195.214.232.25]:22714 "EHLO relay.sw.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751072AbbEXQUF (ORCPT ); Sun, 24 May 2015 12:20:05 -0400 Message-ID: <5561F9E0.6050504@virtuozzo.com> Date: Sun, 24 May 2015 19:18:40 +0300 From: Vasily Averin Organization: Odin User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.6.0 MIME-Version: 1.0 To: linux-kernel@vger.kernel.org, Andrew Morton CC: Kees Cook , Josh Boyer , Eric Paris Subject: [PATCH v2] security_syslog() should be called once only References: <20150514150154.dbfb8ab275aa30d0fe93172b@linux-foundation.org> In-Reply-To: <20150514150154.dbfb8ab275aa30d0fe93172b@linux-foundation.org> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2203 Lines: 72 v2: subject changed, patch comment modified Fixes: 637241a900cb ("kmsg: honor dmesg_restrict sysctl on /dev/kmsg") Final version of patch 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. Signed-off-by: Vasily Averin --- 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 c099b08..bff0169 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/