Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755711Ab0LHPSR (ORCPT ); Wed, 8 Dec 2010 10:18:17 -0500 Received: from 184-106-158-135.static.cloud-ips.com ([184.106.158.135]:39902 "EHLO mail" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1755597Ab0LHPSP (ORCPT ); Wed, 8 Dec 2010 10:18:15 -0500 Date: Wed, 8 Dec 2010 15:19:01 +0000 From: "Serge E. Hallyn" To: James Morris , Eric Paris , Stephen Smalley , dwalsh@redhat.com, Kees Cook , linux-kernel@vger.kernel.org Subject: [PATCH] syslog: check cap_syslog when dmesg_restrict Message-ID: <20101208151901.GA20557@mail.hallyn.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2680 Lines: 74 Eric Paris pointed out that it doesn't make sense to require both CAP_SYS_ADMIN and CAP_SYSLOG for certain syslog actions. So require CAP_SYSLOG, not CAP_SYS_ADMIN, when dmesg_restrict is set. (I'm also consolidating the now common error path) Signed-off-by: Serge E. Hallyn --- Documentation/sysctl/kernel.txt | 2 +- kernel/printk.c | 20 ++++++++++---------- 2 files changed, 11 insertions(+), 11 deletions(-) diff --git a/Documentation/sysctl/kernel.txt b/Documentation/sysctl/kernel.txt index 209e158..5740671 100644 --- a/Documentation/sysctl/kernel.txt +++ b/Documentation/sysctl/kernel.txt @@ -219,7 +219,7 @@ dmesg_restrict: This toggle indicates whether unprivileged users are prevented from using dmesg(8) to view messages from the kernel's log buffer. When dmesg_restrict is set to (0) there are no restrictions. When -dmesg_restrict is set set to (1), users must have CAP_SYS_ADMIN to use +dmesg_restrict is set set to (1), users must have CAP_SYSLOG to use dmesg(8). The kernel config option CONFIG_SECURITY_DMESG_RESTRICT sets the default diff --git a/kernel/printk.c b/kernel/printk.c index 0712380..0cecba0 100644 --- a/kernel/printk.c +++ b/kernel/printk.c @@ -279,18 +279,12 @@ int do_syslog(int type, char __user *buf, int len, bool from_file) * at open time. */ if (type == SYSLOG_ACTION_OPEN || !from_file) { - if (dmesg_restrict && !capable(CAP_SYS_ADMIN)) - return -EPERM; + if (dmesg_restrict && !capable(CAP_SYSLOG)) + goto warn; /* switch to return -EPERM after 2.6.39 */ if ((type != SYSLOG_ACTION_READ_ALL && type != SYSLOG_ACTION_SIZE_BUFFER) && - !capable(CAP_SYSLOG)) { - /* remove after 2.6.38 */ - if (capable(CAP_SYS_ADMIN)) - WARN_ONCE(1, "Attempt to access syslog with " - "CAP_SYS_ADMIN but no CAP_SYSLOG " - "(deprecated and denied).\n"); - return -EPERM; - } + !capable(CAP_SYSLOG)) + goto warn; /* switch to return -EPERM after 2.6.39 */ } error = security_syslog(type); @@ -434,6 +428,12 @@ int do_syslog(int type, char __user *buf, int len, bool from_file) } out: return error; +warn: + /* remove after 2.6.39 */ + if (capable(CAP_SYS_ADMIN)) + WARN_ONCE(1, "Attempt to access syslog with CAP_SYS_ADMIN " + "but no CAP_SYSLOG (deprecated and denied).\n"); + return -EPERM; } SYSCALL_DEFINE3(syslog, int, type, char __user *, buf, int, len) -- 1.7.0.4 -- 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/