Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753762Ab0FWVwy (ORCPT ); Wed, 23 Jun 2010 17:52:54 -0400 Received: from mail.pripojeni.net ([217.66.174.14]:37301 "EHLO mail.pripojeni.net" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1752188Ab0FWVwt (ORCPT ); Wed, 23 Jun 2010 17:52:49 -0400 From: Jiri Slaby To: jirislaby@gmail.com Cc: Oleg Nesterov , akpm@linux-foundation.org, adobriyan@gmail.com, nhorman@tuxdriver.com, Stephen Smalley , James Morris , Eric Paris , linux-kernel@vger.kernel.org Subject: [PATCH v4 06/12] rlimits: allow setrlimit to non-current tasks Date: Wed, 23 Jun 2010 23:52:07 +0200 Message-Id: <1277329933-8139-6-git-send-email-jslaby@suse.cz> X-Mailer: git-send-email 1.7.1 In-Reply-To: <1277329933-8139-1-git-send-email-jslaby@suse.cz> References: <1277329933-8139-1-git-send-email-jslaby@suse.cz> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2240 Lines: 72 From: Jiri Slaby Add locking to allow setrlimit accept task parameter other than current. Namely, lock tasklist_lock for read and check whether the task structure has sighand non-null. Do all the signal processing under that lock still held. There are some points: 1) security_task_setrlimit is now called with that lock held. This is not new, many security_* functions are called with this lock held already so it doesn't harm (all this security_* stuff does almost the same). 2) task->sighand->siglock (in update_rlimit_cpu) is nested in tasklist_lock. This dependence is already existing. 3) tsk->alloc_lock is nested in tasklist_lock. This is OK too, already existing dependence. Signed-off-by: Jiri Slaby Cc: Oleg Nesterov --- kernel/sys.c | 11 ++++++++++- 1 files changed, 10 insertions(+), 1 deletions(-) diff --git a/kernel/sys.c b/kernel/sys.c index b5b96e3..9dbcbbc 100644 --- a/kernel/sys.c +++ b/kernel/sys.c @@ -1272,6 +1272,7 @@ SYSCALL_DEFINE2(old_getrlimit, unsigned int, resource, #endif +/* make sure you are allowed to change @tsk limits before calling this */ int do_setrlimit(struct task_struct *tsk, unsigned int resource, struct rlimit *new_rlim) { @@ -1285,9 +1286,16 @@ int do_setrlimit(struct task_struct *tsk, unsigned int resource, if (resource == RLIMIT_NOFILE && new_rlim->rlim_max > sysctl_nr_open) return -EPERM; + /* protect tsk->signal and tsk->sighand from disappearing */ + read_lock(&tasklist_lock); + if (!tsk->sighand) { + retval = -ESRCH; + goto out; + } + retval = security_task_setrlimit(tsk->group_leader, resource, new_rlim); if (retval) - return retval; + goto out; if (resource == RLIMIT_CPU && new_rlim->rlim_cur == 0) { /* @@ -1322,6 +1330,7 @@ int do_setrlimit(struct task_struct *tsk, unsigned int resource, update_rlimit_cpu(tsk, new_rlim->rlim_cur); out: + read_unlock(&tasklist_lock); return retval; } -- 1.7.1 -- 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/