From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id EB832C17449 for ; Wed, 13 Nov 2019 02:03:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C603522467 for ; Wed, 13 Nov 2019 02:03:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729865AbfKMCDm (ORCPT ); Tue, 12 Nov 2019 21:03:42 -0500 Received: from zeniv.linux.org.uk ([195.92.253.2]:39298 "EHLO ZenIV.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728300AbfKMCDm (ORCPT ); Tue, 12 Nov 2019 21:03:42 -0500 Received: from viro by ZenIV.linux.org.uk with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1iUhzv-0008C3-Ic; Wed, 13 Nov 2019 02:03:07 +0000 Date: Wed, 13 Nov 2019 02:03:07 +0000 From: Al Viro To: Aleksa Sarai Cc: Jeff Layton , "J. Bruce Fields" , Arnd Bergmann , David Howells , Shuah Khan , Shuah Khan , Ingo Molnar , Peter Zijlstra , Christian Brauner , Eric Biederman , Andy Lutomirski , Andrew Morton , Alexei Starovoitov , Kees Cook , Jann Horn , Tycho Andersen , David Drysdale , Chanho Min , Oleg Nesterov , Rasmus Villemoes , Alexander Shishkin , Jiri Olsa , Namhyung Kim , Christian Brauner , Aleksa Sarai , Linus Torvalds , containers@lists.linux-foundation.org, linux-alpha@vger.kernel.org, linux-api@vger.kernel.org, libc-alpha@sourceware.org, linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-ia64@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-m68k@lists.linux-m68k.org, linux-mips@vger.kernel.org, linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, linux-xtensa@linux-xtensa.org, sparclinux@vger.kernel.org Subject: Re: [PATCH v15 5/9] namei: LOOKUP_IN_ROOT: chroot-like scoped resolution Message-ID: <20191113020307.GB26530@ZenIV.linux.org.uk> References: <20191105090553.6350-1-cyphar@cyphar.com> <20191105090553.6350-6-cyphar@cyphar.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191105090553.6350-6-cyphar@cyphar.com> User-Agent: Mutt/1.12.1 (2019-06-15) Sender: linux-kselftest-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org On Tue, Nov 05, 2019 at 08:05:49PM +1100, Aleksa Sarai wrote: > @@ -2277,12 +2277,20 @@ static const char *path_init(struct nameidata *nd, unsigned flags) > > nd->m_seq = read_seqbegin(&mount_lock); > > - /* Figure out the starting path and root (if needed). */ > - if (*s == '/') { > + /* Absolute pathname -- fetch the root. */ > + if (flags & LOOKUP_IN_ROOT) { > + /* With LOOKUP_IN_ROOT, act as a relative path. */ > + while (*s == '/') > + s++; Er... Why bother skipping slashes? I mean, not only link_path_walk() will skip them just fine, you are actually risking breakage in this: if (*s && unlikely(!d_can_lookup(dentry))) { fdput(f); return ERR_PTR(-ENOTDIR); } which is downstream from there with you patch, AFAICS. From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9ECD5C17441 for ; Wed, 13 Nov 2019 02:03:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 77974222CA for ; Wed, 13 Nov 2019 02:03:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729875AbfKMCDn (ORCPT ); Tue, 12 Nov 2019 21:03:43 -0500 Received: from zeniv.linux.org.uk ([195.92.253.2]:39298 "EHLO ZenIV.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728300AbfKMCDm (ORCPT ); Tue, 12 Nov 2019 21:03:42 -0500 Received: from viro by ZenIV.linux.org.uk with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1iUhzv-0008C3-Ic; Wed, 13 Nov 2019 02:03:07 +0000 Date: Wed, 13 Nov 2019 02:03:07 +0000 From: Al Viro To: Aleksa Sarai Cc: Jeff Layton , "J. Bruce Fields" , Arnd Bergmann , David Howells , Shuah Khan , Shuah Khan , Ingo Molnar , Peter Zijlstra , Christian Brauner , Eric Biederman , Andy Lutomirski , Andrew Morton , Alexei Starovoitov , Kees Cook , Jann Horn , Tycho Andersen , David Drysdale , Chanho Min , Oleg Nesterov , Rasmus Villemoes , Alexander Shishkin , Jiri Olsa , Namhyung Kim , Christian Brauner , Aleksa Sarai , Linus Torvalds , containers@lists.linux-foundation.org, linux-alpha@vger.kernel.org, linux-api@vger.kernel.org, libc-alpha@sourceware.org, linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-ia64@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-m68k@lists.linux-m68k.org, linux-mips@vger.kernel.org, linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, linux-xtensa@linux-xtensa.org, sparclinux@vger.kernel.org Subject: Re: [PATCH v15 5/9] namei: LOOKUP_IN_ROOT: chroot-like scoped resolution Message-ID: <20191113020307.GB26530@ZenIV.linux.org.uk> References: <20191105090553.6350-1-cyphar@cyphar.com> <20191105090553.6350-6-cyphar@cyphar.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191105090553.6350-6-cyphar@cyphar.com> User-Agent: Mutt/1.12.1 (2019-06-15) Sender: linux-m68k-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-m68k@vger.kernel.org Message-ID: <20191113020307.xBNdv4bzO9Ow4TwM84TaKcr-t0f9_WDZIn-lwmzrCGk@z> On Tue, Nov 05, 2019 at 08:05:49PM +1100, Aleksa Sarai wrote: > @@ -2277,12 +2277,20 @@ static const char *path_init(struct nameidata *nd, unsigned flags) > > nd->m_seq = read_seqbegin(&mount_lock); > > - /* Figure out the starting path and root (if needed). */ > - if (*s == '/') { > + /* Absolute pathname -- fetch the root. */ > + if (flags & LOOKUP_IN_ROOT) { > + /* With LOOKUP_IN_ROOT, act as a relative path. */ > + while (*s == '/') > + s++; Er... Why bother skipping slashes? I mean, not only link_path_walk() will skip them just fine, you are actually risking breakage in this: if (*s && unlikely(!d_can_lookup(dentry))) { fdput(f); return ERR_PTR(-ENOTDIR); } which is downstream from there with you patch, AFAICS.