From patchwork Mon May 20 13:32:59 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Aleksa Sarai X-Patchwork-Id: 10951135 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 581381390 for ; Mon, 20 May 2019 13:34:45 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 49BEA2873A for ; Mon, 20 May 2019 13:34:45 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 3DD3B28895; Mon, 20 May 2019 13:34:45 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id CC8742888C for ; Mon, 20 May 2019 13:34:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732090AbfETNel (ORCPT ); Mon, 20 May 2019 09:34:41 -0400 Received: from mx1.mailbox.org ([80.241.60.212]:59666 "EHLO mx1.mailbox.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728634AbfETNek (ORCPT ); Mon, 20 May 2019 09:34:40 -0400 Received: from smtp2.mailbox.org (smtp2.mailbox.org [80.241.60.241]) (using TLSv1.2 with cipher ECDHE-RSA-CHACHA20-POLY1305 (256/256 bits)) (No client certificate requested) by mx1.mailbox.org (Postfix) with ESMTPS id 7072950251; Mon, 20 May 2019 15:34:37 +0200 (CEST) X-Virus-Scanned: amavisd-new at heinlein-support.de Received: from smtp2.mailbox.org ([80.241.60.241]) by spamfilter06.heinlein-hosting.de (spamfilter06.heinlein-hosting.de [80.241.56.125]) (amavisd-new, port 10030) with ESMTP id u25V7i0GyP7E; Mon, 20 May 2019 15:34:32 +0200 (CEST) From: Aleksa Sarai To: Al Viro , Jeff Layton , "J. Bruce Fields" , Arnd Bergmann , David Howells , Shuah Khan , Shuah Khan Cc: Aleksa Sarai , Eric Biederman , Andy Lutomirski , Andrew Morton , Alexei Starovoitov , Kees Cook , Jann Horn , Christian Brauner , Tycho Andersen , David Drysdale , Chanho Min , Oleg Nesterov , Aleksa Sarai , Linus Torvalds , containers@lists.linux-foundation.org, linux-kselftest@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-api@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org Subject: [PATCH RFC v8 04/10] namei: split out nd->dfd handling to dirfd_path_init Date: Mon, 20 May 2019 23:32:59 +1000 Message-Id: <20190520133305.11925-5-cyphar@cyphar.com> In-Reply-To: <20190520133305.11925-1-cyphar@cyphar.com> References: <20190520133305.11925-1-cyphar@cyphar.com> MIME-Version: 1.0 Sender: linux-kselftest-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Previously, path_init's handling of *at(dfd, ...) was only done once, but with LOOKUP_BENEATH (and LOOKUP_IN_ROOT) we have to parse the initial nd->path at different times (before or after absolute path handling) depending on whether we have been asked to scope resolution within a root. Signed-off-by: Aleksa Sarai --- fs/namei.c | 103 ++++++++++++++++++++++++++++++----------------------- 1 file changed, 59 insertions(+), 44 deletions(-) diff --git a/fs/namei.c b/fs/namei.c index 46c5302eea4a..dc323e25d4d2 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -2251,9 +2251,59 @@ static int link_path_walk(const char *name, struct nameidata *nd) } } +/* + * Configure nd->path based on the nd->dfd. This is only used as part of + * path_init(). + */ +static inline int dirfd_path_init(struct nameidata *nd) +{ + if (nd->dfd == AT_FDCWD) { + if (nd->flags & LOOKUP_RCU) { + struct fs_struct *fs = current->fs; + unsigned seq; + + do { + seq = read_seqcount_begin(&fs->seq); + nd->path = fs->pwd; + nd->inode = nd->path.dentry->d_inode; + nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); + } while (read_seqcount_retry(&fs->seq, seq)); + } else { + get_fs_pwd(current->fs, &nd->path); + nd->inode = nd->path.dentry->d_inode; + } + } else { + /* Caller must check execute permissions on the starting path component */ + struct fd f = fdget_raw(nd->dfd); + struct dentry *dentry; + + if (!f.file) + return -EBADF; + + dentry = f.file->f_path.dentry; + + if (*nd->name->name && unlikely(!d_can_lookup(dentry))) { + fdput(f); + return -ENOTDIR; + } + + nd->path = f.file->f_path; + if (nd->flags & LOOKUP_RCU) { + nd->inode = nd->path.dentry->d_inode; + nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); + } else { + path_get(&nd->path); + nd->inode = nd->path.dentry->d_inode; + } + fdput(f); + } + return 0; +} + /* must be paired with terminate_walk() */ static const char *path_init(struct nameidata *nd, unsigned flags) { + int error; const char *s = nd->name->name; if (!*s) @@ -2287,52 +2337,17 @@ static const char *path_init(struct nameidata *nd, unsigned flags) nd->m_seq = read_seqbegin(&mount_lock); if (*s == '/') { - set_root(nd); - if (likely(!nd_jump_root(nd))) - return s; - return ERR_PTR(-ECHILD); - } else if (nd->dfd == AT_FDCWD) { - if (flags & LOOKUP_RCU) { - struct fs_struct *fs = current->fs; - unsigned seq; - - do { - seq = read_seqcount_begin(&fs->seq); - nd->path = fs->pwd; - nd->inode = nd->path.dentry->d_inode; - nd->seq = __read_seqcount_begin(&nd->path.dentry->d_seq); - } while (read_seqcount_retry(&fs->seq, seq)); - } else { - get_fs_pwd(current->fs, &nd->path); - nd->inode = nd->path.dentry->d_inode; - } - return s; - } else { - /* Caller must check execute permissions on the starting path component */ - struct fd f = fdget_raw(nd->dfd); - struct dentry *dentry; - - if (!f.file) - return ERR_PTR(-EBADF); - - dentry = f.file->f_path.dentry; - - if (*s && unlikely(!d_can_lookup(dentry))) { - fdput(f); - return ERR_PTR(-ENOTDIR); - } - - nd->path = f.file->f_path; - if (flags & LOOKUP_RCU) { - nd->inode = nd->path.dentry->d_inode; - nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq); - } else { - path_get(&nd->path); - nd->inode = nd->path.dentry->d_inode; - } - fdput(f); + if (likely(!nd->root.mnt)) + set_root(nd); + error = nd_jump_root(nd); + if (unlikely(error)) + s = ERR_PTR(error); return s; } + error = dirfd_path_init(nd); + if (unlikely(error)) + return ERR_PTR(error); + return s; } static const char *trailing_symlink(struct nameidata *nd)