Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753282Ab1BDROX (ORCPT ); Fri, 4 Feb 2011 12:14:23 -0500 Received: from 184-106-158-135.static.cloud-ips.com ([184.106.158.135]:38560 "EHLO mail" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752511Ab1BDROW (ORCPT ); Fri, 4 Feb 2011 12:14:22 -0500 Date: Fri, 4 Feb 2011 17:15:02 +0000 From: "Serge E. Hallyn" To: Gergely Nagy Cc: "Serge E. Hallyn" , James Morris , Linux Kernel Mailing List Subject: Re: CAP_SYSLOG, 2.6.38 and user space Message-ID: <20110204171502.GA24226@mail.hallyn.com> References: <1296733177.14846.26.camel@moria> <20110203153252.GA24153@mail.hallyn.com> <20110204160513.GB17396@mail.hallyn.com> <1296837186.24742.15.camel@moria> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1296837186.24742.15.camel@moria> 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: 3294 Lines: 94 Quoting Gergely Nagy (algernon@balabit.hu): > On Fri, 2011-02-04 at 16:05 +0000, Serge E. Hallyn wrote: > > Quoting Serge E. Hallyn (serge@hallyn.com): > > > >From 2d7408541dd3a6e19a4265b028233789be6a40f4 Mon Sep 17 00:00:00 2001 > > > From: Serge Hallyn > > > Date: Thu, 3 Feb 2011 09:26:15 -0600 > > > Subject: [PATCH 1/1] cap_syslog: don't refuse cap_sys_admin for now > > > > > > At 2.6.39 or 2.6.40, let's add a sysctl which defaults to 0. When > > > 0, refuse if cap_sys_admin, if 1, then allow. This will allow > > > users to acknowledge (permanently, if they must, using /etc/sysctl.conf) > > > that they've seen the syslog message about cap_sys_admin being > > > deprecated for syslog. > > > > > > Signed-off-by: Serge Hallyn > > [...snip...] > > > James, do you mind taking this patch? > > Would it be possible to change the commit message to say that 1 would be > the default? Just to avoid future confusion... (having it at 0 default > later would just postpone the userspace breakage) > Good point, attached. >From ead9a1649880806c333b7f2378509d7d93725480 Mon Sep 17 00:00:00 2001 From: Serge Hallyn Date: Thu, 3 Feb 2011 09:26:15 -0600 Subject: [PATCH 1/1] cap_syslog: don't refuse cap_sys_admin for now At 2.6.39 or 2.6.40, let's add a sysctl which defaults to 1. When 0, refuse if cap_sys_admin, if 1, then allow. Signed-off-by: Serge Hallyn --- kernel/printk.c | 26 ++++++++++++++++---------- 1 files changed, 16 insertions(+), 10 deletions(-) diff --git a/kernel/printk.c b/kernel/printk.c index 2ddbdc7..bc56386 100644 --- a/kernel/printk.c +++ b/kernel/printk.c @@ -274,12 +274,24 @@ 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_SYSLOG)) - goto warn; /* switch to return -EPERM after 2.6.39 */ + if (dmesg_restrict && !capable(CAP_SYSLOG)) { + /* 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).\n"); + else + return -EPERM; + } if ((type != SYSLOG_ACTION_READ_ALL && type != SYSLOG_ACTION_SIZE_BUFFER) && - !capable(CAP_SYSLOG)) - goto warn; /* switch to return -EPERM after 2.6.39 */ + !capable(CAP_SYSLOG)) { + /* 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).\n"); + else + return -EPERM; + } } error = security_syslog(type); @@ -423,12 +435,6 @@ 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) -- 1.7.2.3 -- 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/