From patchwork Mon Nov 23 03:50:25 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Marcos Paulo de Souza X-Patchwork-Id: 11924365 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=-16.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham 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 2E6E4C63777 for ; Mon, 23 Nov 2020 04:38:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BFF09206C0 for ; Mon, 23 Nov 2020 04:38:00 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=mpdesouza.com header.i=@mpdesouza.com header.b="YxW+pLJD" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727255AbgKWEiA (ORCPT ); Sun, 22 Nov 2020 23:38:00 -0500 Received: from gateway21.websitewelcome.com ([192.185.45.175]:23888 "EHLO gateway21.websitewelcome.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726993AbgKWEh7 (ORCPT ); Sun, 22 Nov 2020 23:37:59 -0500 Received: from cm17.websitewelcome.com (cm17.websitewelcome.com [100.42.49.20]) by gateway21.websitewelcome.com (Postfix) with ESMTP id 5081F400C6A6F for ; Sun, 22 Nov 2020 21:50:58 -0600 (CST) Received: from br540.hostgator.com.br ([108.179.252.180]) by cmsmtp with SMTP id h2sUk3eRQAAk4h2sUkXDTx; Sun, 22 Nov 2020 21:50:58 -0600 X-Authority-Reason: nr=8 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=mpdesouza.com; s=default; h=Content-Transfer-Encoding:MIME-Version: References:In-Reply-To:Message-Id:Date:Subject:Cc:To:From:Sender:Reply-To: Content-Type:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id:List-Help: List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=yZ6FDyvy5b99xpX89Y2nOal23ajdV4FPVU0JpFwdWZ4=; b=YxW+pLJDRLO4vDTFfNDZLXjNw1 YIPlXP55lGZAWuqDseFRAPSPK/eeUH3c5G/b9KtcVWLpBH9dJBxFkUxoFOq78A0ZcaLYskFNlVvGA Mwdv7igyYM9p6Gv2cRT11MDoeu1etmWCKaPkrF04sg96w01acsDNARV9KMTEpq4GVd8zytUt0HOXE VM404ZZUK34nwaMX4SH0L8aidu7/YsBZuFJOVVeld3u1dj5aDnCfDiMJrMyFNUtR3FnPToWo3aScC VvBQtFLbHG5gZVLTLc1DUhLsQjf7y9XlnKtpTluZ1M1JnVM8bdy67w52wIk2EHf93nSNmRbg/sdJx nTW97/KQ==; Received: from [191.249.68.105] (port=43094 helo=localhost.suse.de) by br540.hostgator.com.br with esmtpsa (TLS1.2) tls TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 (Exim 4.93) (envelope-from ) id 1kh2sT-0007ir-OA; Mon, 23 Nov 2020 00:50:58 -0300 From: Marcos Paulo de Souza To: linux-btrfs@vger.kernel.org Cc: Marcos Paulo de Souza , wqu@suse.com, dsterba@suse.com Subject: [PATCH v3 2/3] btrfs-progs: inspect: Fix logical-resolve file path lookup Date: Mon, 23 Nov 2020 00:50:25 -0300 Message-Id: <20201123035026.7282-3-marcos@mpdesouza.com> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20201123035026.7282-1-marcos@mpdesouza.com> References: <20201123035026.7282-1-marcos@mpdesouza.com> MIME-Version: 1.0 X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - br540.hostgator.com.br X-AntiAbuse: Original Domain - vger.kernel.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - mpdesouza.com X-BWhitelist: no X-Source-IP: 191.249.68.105 X-Source-L: No X-Exim-ID: 1kh2sT-0007ir-OA X-Source: X-Source-Args: X-Source-Dir: X-Source-Sender: (localhost.suse.de) [191.249.68.105]:43094 X-Source-Auth: marcos@mpdesouza.com X-Email-Count: 12 X-Source-Cap: bXBkZXNvNTM7bXBkZXNvNTM7YnI1NDAuaG9zdGdhdG9yLmNvbS5icg== X-Local-Domain: yes Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org From: Marcos Paulo de Souza [BUG] logical-resolve is currently broken on systems that have a child subvolume being mounted without access to the parent subvolume. This is the default for SLE/openSUSE installations. openSUSE has the subvolume '@' as the parent of all other subvolumes like /boot, /home. The subvolume '@' is never mounted and accessed, but only it's childs: mount | grep btrfs /dev/sda2 on / type btrfs (rw,relatime,ssd,space_cache,subvolid=267,subvol=/@/.snapshots/1/snapshot) /dev/sda2 on /opt type btrfs (rw,relatime,ssd,space_cache,subvolid=262,subvol=/@/opt) /dev/sda2 on /boot/grub2/i386-pc type btrfs (rw,relatime,ssd,space_cache,subvolid=265,subvol=/@/boot/grub2/i386-pc) logical-resolve command calls btrfs_list_path_for_root, that returns the subvolume full-path that corresponds to the tree id of the logical address. As the name implies, the 'full-path' returns the subvolume full path, starting from '@'. Later on, btrfs_open_dir is called using the path returned, but it fails to resolve it since it contains the '@' and this subvolume cannot be accessed. The same problem can be triggered to any user that calls for logical-resolve on a child subvolume that has the parent subvolume not accessible. Another problem in the current approach is that it believes that a subvolume will be mounted in a directory with the same name e.g /@/boot being mounted in /boot. When this is not true, the code also fails, since it uses the subvolume name as the path. [FIX] Extent the find_mount_root function by allowing it to check for mnt_opts member of mntent struct. Using this new approach we can change logical-resolve command to search for subvolid=XXX,subvol=YYY returning the correct path accessible to the user. Using this approach we can solve the problems stated above by not trusting the subvolume name being the mountpoint, and not executing the lookup based only in the subvolume tree. Signed-off-by: Marcos Paulo de Souza --- cmds/inspect.c | 37 +++++++++++++++++++++++++++++-------- common/utils.c | 29 +++++++++++++++++++++++------ common/utils.h | 5 ++++- 3 files changed, 56 insertions(+), 15 deletions(-) diff --git a/cmds/inspect.c b/cmds/inspect.c index 2530b904..81185537 100644 --- a/cmds/inspect.c +++ b/cmds/inspect.c @@ -245,15 +245,36 @@ static int cmd_inspect_logical_resolve(const struct cmd_struct *cmd, path_ptr[-1] = '\0'; path_fd = fd; } else { - path_ptr[-1] = '/'; - ret = snprintf(path_ptr, bytes_left, "%s", - name); - free(name); - if (ret >= bytes_left) { - error("path buffer too small: %d bytes", - bytes_left - ret); - goto out; + char *mounted = NULL; + char volid_str[PATH_MAX]; + + /* + * btrfs_list_path_for_root returns the full + * path to the subvolume pointed by root, but the + * subvolume can be mounted in a directory name + * different from the subvolume name. In this + * case we need to find the correct mountpoint + * using same subvol path and subvol id found + * before. + */ + snprintf(volid_str, PATH_MAX, "subvolid=%llu,subvol=/%s", + root, name); + + ret = find_mount_root(full_path, volid_str, + BTRFS_FIND_ROOT_OPTS, &mounted); + + if (ret == -ENOENT) { + printf("inode %llu subvol %s could not be accessed: not mounted\n", + inum, name); + continue; } + + if (ret < 0) + goto out; + + strncpy(full_path, mounted, PATH_MAX); + free(mounted); + path_fd = btrfs_open_dir(full_path, &dirs, 1); if (path_fd < 0) { ret = -ENOENT; diff --git a/common/utils.c b/common/utils.c index 1c264455..1562ac52 100644 --- a/common/utils.c +++ b/common/utils.c @@ -1259,9 +1259,6 @@ int find_mount_root(const char *path, const char *data, u8 flag, char **mount_ro int longest_matchlen = 0; char *longest_match = NULL; char *cmp_field = NULL; - bool found; - - BUG_ON(flag != BTRFS_FIND_ROOT_PATH); fd = open(path, O_RDONLY | O_NOATIME); if (fd < 0) @@ -1273,12 +1270,32 @@ int find_mount_root(const char *path, const char *data, u8 flag, char **mount_ro return -errno; while ((ent = getmntent(mnttab))) { - cmp_field = ent->mnt_dir; + bool found = false; - len = strlen(cmp_field); + /* BTRFS_FIND_ROOT_PATH is the default behavior */ + if (flag == BTRFS_FIND_ROOT_OPTS) + cmp_field = ent->mnt_opts; + else + cmp_field = ent->mnt_dir; - found = strncmp(cmp_field, data, len) == 0; + len = strlen(cmp_field); + if (flag == BTRFS_FIND_ROOT_OPTS) { + size_t dlen = strlen(data); + char *tmp_str = strstr(cmp_field, data); + /* + * Make sure that we are dealing with the wanted string, + * since strstr returns the start of the string found. + * Compare the end string position from data with the + * mount point found, and make sure that we have an + * option separator or string end. + */ + if (tmp_str) + found = tmp_str[dlen] == ',' || + tmp_str[dlen] == 0; + } else { + found = strncmp(cmp_field, data, len) == 0; + } if (found) { /* match found and use the latest match */ if (longest_matchlen <= len) { diff --git a/common/utils.h b/common/utils.h index 449e1d3e..b5d256c6 100644 --- a/common/utils.h +++ b/common/utils.h @@ -54,7 +54,10 @@ enum btrfs_find_root_flags { /* check mnt_dir of mntent */ - BTRFS_FIND_ROOT_PATH = 0 + BTRFS_FIND_ROOT_PATH = 0, + + /* check mnt_opts of mntent */ + BTRFS_FIND_ROOT_OPTS }; void units_set_mode(unsigned *units, unsigned mode);