Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755467AbaFXRax (ORCPT ); Tue, 24 Jun 2014 13:30:53 -0400 Received: from mx1.redhat.com ([209.132.183.28]:62239 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751862AbaFXRav (ORCPT ); Tue, 24 Jun 2014 13:30:51 -0400 Date: Tue, 24 Jun 2014 19:27:53 +0200 From: Oleg Nesterov To: Kees Cook Cc: linux-kernel@vger.kernel.org, Andy Lutomirski , Alexei Starovoitov , "Michael Kerrisk (man-pages)" , Andrew Morton , Daniel Borkmann , Will Drewry , Julien Tinnes , David Drysdale , linux-api@vger.kernel.org, x86@kernel.org, linux-arm-kernel@lists.infradead.org, linux-mips@linux-mips.org, linux-arch@vger.kernel.org, linux-security-module@vger.kernel.org Subject: Re: [PATCH v7 7/9] seccomp: implement SECCOMP_FILTER_FLAG_TSYNC Message-ID: <20140624172753.GA31435@redhat.com> References: <1403560693-21809-1-git-send-email-keescook@chromium.org> <1403560693-21809-8-git-send-email-keescook@chromium.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1403560693-21809-8-git-send-email-keescook@chromium.org> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 06/23, Kees Cook wrote: > > +static pid_t seccomp_can_sync_threads(void) > +{ > + struct task_struct *thread, *caller; > + > + BUG_ON(write_can_lock(&tasklist_lock)); > + BUG_ON(!spin_is_locked(¤t->sighand->siglock)); > + > + if (current->seccomp.mode != SECCOMP_MODE_FILTER) > + return -EACCES; > + > + /* Validate all threads being eligible for synchronization. */ > + thread = caller = current; > + for_each_thread(caller, thread) { > + pid_t failed; > + > + if (thread->seccomp.mode == SECCOMP_MODE_DISABLED || > + (thread->seccomp.mode == SECCOMP_MODE_FILTER && > + is_ancestor(thread->seccomp.filter, > + caller->seccomp.filter))) > + continue; > + > + /* Return the first thread that cannot be synchronized. */ > + failed = task_pid_vnr(thread); > + /* If the pid cannot be resolved, then return -ESRCH */ > + if (failed == 0) > + failed = -ESRCH; forgot to mention, task_pid_vnr() can't fail. sighand->siglock is held, for_each_thread() can't see a thread which has passed unhash_process(). Oleg. -- 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/