From patchwork Fri May 11 07:29:43 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Misono Tomohiro X-Patchwork-Id: 10393377 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id BEAF6602B1 for ; Fri, 11 May 2018 07:27:44 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 7834D28D97 for ; Fri, 11 May 2018 07:27:44 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 6D24D28E00; Fri, 11 May 2018 07:27:44 +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=ham 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 6FCB728D97 for ; Fri, 11 May 2018 07:27:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752614AbeEKH1m (ORCPT ); Fri, 11 May 2018 03:27:42 -0400 Received: from mgwym04.jp.fujitsu.com ([211.128.242.43]:29755 "EHLO mgwym04.jp.fujitsu.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751433AbeEKH1j (ORCPT ); Fri, 11 May 2018 03:27:39 -0400 Received: from yt-mxauth.gw.nic.fujitsu.com (unknown [192.168.229.68]) by mgwym04.jp.fujitsu.com with smtp id 4718_53ed_347db39b_2aed_4155_9926_f8b0372ca0a3; Fri, 11 May 2018 16:27:33 +0900 Received: from g01jpfmpwkw03.exch.g01.fujitsu.local (g01jpfmpwkw03.exch.g01.fujitsu.local [10.0.193.57]) by yt-mxauth.gw.nic.fujitsu.com (Postfix) with ESMTP id A6A77AC051A for ; Fri, 11 May 2018 16:27:32 +0900 (JST) Received: from g01jpexchkw35.g01.fujitsu.local (unknown [10.0.193.4]) by g01jpfmpwkw03.exch.g01.fujitsu.local (Postfix) with ESMTP id D94E0BD67EB for ; Fri, 11 May 2018 16:27:31 +0900 (JST) Received: from luna3.soft.fujitsu.com (10.124.196.199) by g01jpexchkw35.g01.fujitsu.local (10.0.193.50) with Microsoft SMTP Server id 14.3.352.0; Fri, 11 May 2018 16:27:31 +0900 From: Tomohiro Misono To: Subject: [PATCH 05/11] btrfs-progs: libbtrfsutil: Update the behavior of subvolume iterator and relax the privileges Date: Fri, 11 May 2018 16:29:43 +0900 Message-ID: <20180511072949.15269-6-misono.tomohiro@jp.fujitsu.com> X-Mailer: git-send-email 2.14.3 In-Reply-To: <20180511072949.15269-1-misono.tomohiro@jp.fujitsu.com> References: <20180511072949.15269-1-misono.tomohiro@jp.fujitsu.com> MIME-Version: 1.0 X-SecurityPolicyCheck-GC: OK by FENCE-Mail X-TM-AS-MML: disable Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP By using new ioctls (BTRFS_IOC_GET_ROOTREF_INFO/BTRFS_IOC_INO_LOOKUP_USER), this commit update the subvolume iterator when it is created by btrfs_util_create_subvolume_iterator() with @top zero (i.e. if the iterator is created from givin path/fd). In that case, - an iterator can be created from non-subvolume directory and will skip a subvolume if - it does not exist nor has different id from the found subvolume by INO_LOOKUP_USER (may happen if a dir in the path is being mounted) - it cannot be opened due to permission error Since above ioctls do not require root privileges, non-privileged user can also use the iterator. If @top is specified, the behavior is the same as before (and thus non-privileged user cannot use). Signed-off-by: Tomohiro Misono --- libbtrfsutil/btrfsutil.h | 19 ++- libbtrfsutil/errors.c | 4 + libbtrfsutil/subvolume.c | 319 +++++++++++++++++++++++++++++++++++++++++++---- 3 files changed, 315 insertions(+), 27 deletions(-) diff --git a/libbtrfsutil/btrfsutil.h b/libbtrfsutil/btrfsutil.h index 5fe798c5..b90dc93e 100644 --- a/libbtrfsutil/btrfsutil.h +++ b/libbtrfsutil/btrfsutil.h @@ -65,6 +65,8 @@ enum btrfs_util_error { BTRFS_UTIL_ERROR_WAIT_SYNC_FAILED, BTRFS_UTIL_ERROR_INVALID_ARGUMENT_FOR_USER, BTRFS_UTIL_ERROR_GET_SUBVOL_INFO_FAILED, + BTRFS_UTIL_ERROR_GET_SUBVOL_ROOTREF_FAILED, + BTRFS_UTIL_ERROR_INO_LOOKUP_USER_FAILED, }; /** @@ -510,6 +512,11 @@ struct btrfs_util_subvolume_iterator; * @flags: Bitmask of BTRFS_UTIL_SUBVOLUME_ITERATOR_* flags. * @ret: Returned iterator. * + * For newer kenrels which supports BTRFS_IOC_GET_SUBVOL_ROOTREF and + * BTRFS_IOC_INO_LOOKUP_USER, @path does not have to refer to a subvolume when + * @top is zero. In that case, subvolumes only below the specified path will + * be returned. + * * The returned iterator must be freed with * btrfs_util_destroy_subvolume_iterator(). * @@ -558,7 +565,11 @@ int btrfs_util_subvolume_iterator_fd(const struct btrfs_util_subvolume_iterator * Must be freed with free(). * @id_ret: Returned subvolume ID. May be %NULL. * - * This requires appropriate privilege (CAP_SYS_ADMIN). + * This requires appropriate privilege (CAP_SYS_ADMIN) for older kernel. + * For newer kenrels which supports BTRFS_IOC_GET_SUBVOL_ROOTREF and + * BTRFS_IOC_INO_LOOKUP_USER, non-privileged user also can use this. + * In that case, subvolumes which cannot be accessed by the user will be + * skipped. * * Return: %BTRFS_UTIL_OK on success, %BTRFS_UTIL_ERROR_STOP_ITERATION if there * are no more subvolumes, non-zero error code on failure. @@ -577,7 +588,11 @@ enum btrfs_util_error btrfs_util_subvolume_iterator_next(struct btrfs_util_subvo * This convenience function basically combines * btrfs_util_subvolume_iterator_next() and btrfs_util_subvolume_info(). * - * This requires appropriate privilege (CAP_SYS_ADMIN). + * This requires appropriate privilege (CAP_SYS_ADMIN) for older kernel. + * For newer kenrels which supports BTRFS_IOC_GET_SUGBVOL_INFO, + * BTRFS_IOC_GET_SUBVOL_ROOTREF and BTRFS_IOC_INO_LOOKUP_USER, + * non-privileged user also can use this. In that case, subvolumes which + * cannot be accessed by the user will be skipped. * * Return: See btrfs_util_subvolume_iterator_next(). */ diff --git a/libbtrfsutil/errors.c b/libbtrfsutil/errors.c index f196fa71..21bbc7b2 100644 --- a/libbtrfsutil/errors.c +++ b/libbtrfsutil/errors.c @@ -49,6 +49,10 @@ static const char * const error_messages[] = { "Non-root user cannot specify subvolume id", [BTRFS_UTIL_ERROR_GET_SUBVOL_INFO_FAILED] = "Could not get subvolume information by BTRFS_IOC_GET_SUBVOL_INFO", + [BTRFS_UTIL_ERROR_GET_SUBVOL_ROOTREF_FAILED] = + "Could not get rootref information by BTRRFS_IOC_GET_ROOTREF_INFO", + [BTRFS_UTIL_ERROR_INO_LOOKUP_USER_FAILED] = + "Could not resolve subvolume path by BTRFS_IOC_INO_LOOKUP_USER", }; PUBLIC const char *btrfs_util_strerror(enum btrfs_util_error err) diff --git a/libbtrfsutil/subvolume.c b/libbtrfsutil/subvolume.c index 08bbeca2..036af546 100644 --- a/libbtrfsutil/subvolume.c +++ b/libbtrfsutil/subvolume.c @@ -39,6 +39,24 @@ static bool is_root(void) return (uid == 0); } +/* + * We need both BTRFS_IOC_GET_SUBVOL_ROOTREF and BTRFS_IOC_INO_LOOKUP_USER + * but only checks BTRFS_IOC_GET_SUBVOL_ROOTREF for brevity. + */ +static bool check_support_rootref_ioctl(int fd) +{ + struct btrfs_ioctl_get_subvol_rootref_args args; + int ret; + + memset(&args, 0, sizeof(args)); + ret = ioctl(fd, BTRFS_IOC_GET_SUBVOL_ROOTREF, &args); + + if (ret < 0 && errno == ENOTTY) + return false; + + return true; +} + /* * This intentionally duplicates btrfs_util_is_subvolume_fd() instead of opening * a file descriptor and calling it, because fstat() and fstatfs() don't accept @@ -760,12 +778,18 @@ PUBLIC enum btrfs_util_error btrfs_util_create_subvolume_fd(int parent_fd, #define BTRFS_UTIL_SUBVOLUME_ITERATOR_CLOSE_FD (1 << 30) struct search_stack_entry { + /* used for subvolume_iterator_next_user */ + uint64_t id; + struct btrfs_ioctl_get_subvol_rootref_args rootref_args; + /* used for subvolume_iterator_next_root */ struct btrfs_ioctl_search_args search; + /* used for both */ size_t items_pos, buf_off; size_t path_len; }; struct btrfs_util_subvolume_iterator { + bool use_tree_search; int fd; int flags; @@ -799,22 +823,28 @@ static enum btrfs_util_error append_to_search_stack(struct btrfs_util_subvolume_ entry = &iter->search_stack[iter->search_stack_len++]; - memset(&entry->search, 0, sizeof(entry->search)); - entry->search.key.tree_id = BTRFS_ROOT_TREE_OBJECTID; - entry->search.key.min_objectid = tree_id; - entry->search.key.max_objectid = tree_id; - entry->search.key.min_type = BTRFS_ROOT_REF_KEY; - entry->search.key.max_type = BTRFS_ROOT_REF_KEY; - entry->search.key.min_offset = 0; - entry->search.key.max_offset = UINT64_MAX; - entry->search.key.min_transid = 0; - entry->search.key.max_transid = UINT64_MAX; - entry->search.key.nr_items = 0; - - entry->items_pos = 0; - entry->buf_off = 0; - - entry->path_len = path_len; + if (iter->use_tree_search) { + memset(&entry->search, 0, sizeof(entry->search)); + entry->search.key.tree_id = BTRFS_ROOT_TREE_OBJECTID; + entry->search.key.min_objectid = tree_id; + entry->search.key.max_objectid = tree_id; + entry->search.key.min_type = BTRFS_ROOT_REF_KEY; + entry->search.key.max_type = BTRFS_ROOT_REF_KEY; + entry->search.key.min_offset = 0; + entry->search.key.max_offset = UINT64_MAX; + entry->search.key.min_transid = 0; + entry->search.key.max_transid = UINT64_MAX; + entry->search.key.nr_items = 0; + + entry->items_pos = 0; + entry->buf_off = 0; + + entry->path_len = path_len; + } else { + memset(entry, 0, sizeof(*entry)); + entry->path_len = path_len; + entry->id = tree_id; + } return BTRFS_UTIL_OK; } @@ -847,6 +877,7 @@ PUBLIC enum btrfs_util_error btrfs_util_create_subvolume_iterator_fd(int fd, { struct btrfs_util_subvolume_iterator *iter; enum btrfs_util_error err; + bool use_tree_search = true; if (flags & ~BTRFS_UTIL_SUBVOLUME_ITERATOR_MASK) { errno = EINVAL; @@ -854,13 +885,25 @@ PUBLIC enum btrfs_util_error btrfs_util_create_subvolume_iterator_fd(int fd, } if (top == 0) { - err = btrfs_util_is_subvolume_fd(fd); - if (err) - return err; - - err = btrfs_util_subvolume_id_fd(fd, &top); - if (err) - return err; + if (check_support_rootref_ioctl(fd)) { + /* + * if new ioctls (GET_SUBVOL_ROOTREF etc) is available, + * always use these as this allows to create subvolume + * iterator which starts from non-subvolume directory. + */ + use_tree_search = false; + } else { + if (!is_root()) + return BTRFS_UTIL_ERROR_INVALID_ARGUMENT_FOR_USER; + + err = btrfs_util_is_subvolume_fd(fd); + if (err) + return err; + + err = btrfs_util_subvolume_id_fd(fd, &top); + if (err) + return err; + } } iter = malloc(sizeof(*iter)); @@ -869,6 +912,7 @@ PUBLIC enum btrfs_util_error btrfs_util_create_subvolume_iterator_fd(int fd, iter->fd = fd; iter->flags = flags; + iter->use_tree_search = use_tree_search; iter->search_stack_len = 0; iter->search_stack_capacity = 4; @@ -1255,6 +1299,70 @@ static enum btrfs_util_error build_subvol_path(struct btrfs_util_subvolume_itera return BTRFS_UTIL_OK; } +static enum btrfs_util_error build_subvol_path_user(struct btrfs_util_subvolume_iterator *iter, + int fd, + size_t *path_len_ret) +{ + struct search_stack_entry *top = top_search_stack_entry(iter); + struct btrfs_ioctl_ino_lookup_user_args args; + uint64_t dirid, subvolid; + size_t dir_len, name_len, path_len; + char *p; + int ret; + + dirid = top->rootref_args.rootref[top->items_pos].dirid; + subvolid = top->rootref_args.rootref[top->items_pos].subvolid; + + memset(&args, 0, sizeof(args)); + args.dirid = dirid; + args.subvolid = subvolid; + + ret = ioctl(fd, BTRFS_IOC_INO_LOOKUP_USER, &args); + if (ret < 0) + return BTRFS_UTIL_ERROR_INO_LOOKUP_USER_FAILED; + + dir_len = strlen(args.path); + name_len = strlen(args.name); + path_len = top->path_len; + /* + * We need a joining slash if we have a current path and a subdirectory. + */ + if (top->path_len && dir_len) + path_len++; + path_len += dir_len; + /* + * We need another joining slash if we have a current path and a name, + * but not if we have a subdirectory, because the lookup ioctl includes + * a trailing slash. + */ + if (top->path_len && !dir_len && name_len) + path_len++; + path_len += name_len; + + if (path_len > iter->cur_path_capacity) { + char *tmp = realloc(iter->cur_path, path_len); + + if (!tmp) + return BTRFS_UTIL_ERROR_NO_MEMORY; + iter->cur_path = tmp; + iter->cur_path_capacity = path_len; + } + + p = iter->cur_path + top->path_len; + if (top->path_len && dir_len) + *p++ = '/'; + memcpy(p, args.path, dir_len); + p += dir_len; + if (top->path_len && !dir_len && name_len) + *p++ = '/'; + memcpy(p, args.name, name_len); + p += name_len; + + *path_len_ret = path_len; + + return BTRFS_UTIL_OK; +} + static enum btrfs_util_error subvolume_iterator_next_root(struct btrfs_util_subvolume_iterator *iter, char **path_ret, uint64_t *id_ret) @@ -1331,11 +1439,161 @@ out: return BTRFS_UTIL_OK; } +static enum btrfs_util_error subvolume_iterator_next_user(struct btrfs_util_subvolume_iterator *iter, + char **path_ret, + uint64_t *id_ret) +{ + int ret, fd, fd2; + size_t path_len; + struct search_stack_entry *top; + enum btrfs_util_error err; + char *path; + + for (;;) { + fd = -1; + + for (;;) { + if (iter->search_stack_len == 0) + return BTRFS_UTIL_ERROR_STOP_ITERATION; + + top = top_search_stack_entry(iter); + + if (fd == -1) { + if (!top->path_len) { + fd = dup(iter->fd); + } else { + path = iter->cur_path; + path[top->path_len] = '\0'; + fd = openat(iter->fd, path, O_RDONLY); + } + + if (fd < 0) { + /* skip permission error */ + if (errno == EACCES) { + iter->search_stack_len--; + if ((iter->flags & BTRFS_UTIL_SUBVOLUME_ITERATOR_POST_ORDER) && + iter->search_stack_len) + goto out; + continue; + } else { + return BTRFS_UTIL_ERROR_OPEN_FAILED; + } + } + } + + if (top->items_pos < top->rootref_args.num_items) { + break; + } else { + top->items_pos = 0; + ret = ioctl(fd, BTRFS_IOC_GET_SUBVOL_ROOTREF, + &top->rootref_args); + if (ret < 0) { + if (errno != EOVERFLOW) { + SAVE_ERRNO_AND_CLOSE(fd); + return BTRFS_UTIL_ERROR_GET_SUBVOL_ROOTREF_FAILED; + } + } else { + if (top->rootref_args.num_items == 0) { + iter->search_stack_len--; + SAVE_ERRNO_AND_CLOSE(fd); + fd = -1; + + if ((iter->flags & BTRFS_UTIL_SUBVOLUME_ITERATOR_POST_ORDER) && + iter->search_stack_len) + goto out; + } + } + } + } + + err = build_subvol_path_user(iter, fd, + &path_len); + top->id = top->rootref_args.rootref[top->items_pos].subvolid; + top->items_pos++; + SAVE_ERRNO_AND_CLOSE(fd); + + /* Skip if permission error happens during path construction */ + if (err) { + if (errno == EACCES) { + fd = -1; + continue; + } + return err; + } + + /* Extra check to the constructed path */ + iter->cur_path[path_len] = '\0'; + fd2 = openat(iter->fd, iter->cur_path, O_RDONLY); + if (fd2 < 0) { + /* + * Skip if + * 1. the path does not exist + * (may happen if a dir in the path is mounted) + * 2. cannot open the path due to permission error + */ + if (errno == ENOENT || errno == EACCES) { + fd = -1; + continue; + } + return BTRFS_UTIL_ERROR_OPEN_FAILED; + } else { + uint64_t temp_id; + + /* + * Check the subvolume status and skip if other volume + * is mounted + */ + err = btrfs_util_is_subvolume_fd(fd2); + if (err) { + SAVE_ERRNO_AND_CLOSE(fd2); + if (err == BTRFS_UTIL_ERROR_NOT_BTRFS || + err == BTRFS_UTIL_ERROR_NOT_SUBVOLUME) { + fd = -1; + continue; + } + return err; + } + err = btrfs_util_subvolume_id_fd(fd2, &temp_id); + SAVE_ERRNO_AND_CLOSE(fd2); + if (err) + return err; + if (top->id != temp_id) { + fd = -1; + continue; + } + } + + err = append_to_search_stack(iter, top->id, path_len); + if (err) + return err; + + if (!(iter->flags & BTRFS_UTIL_SUBVOLUME_ITERATOR_POST_ORDER)) { + top = top_search_stack_entry(iter); + goto out; + } + } + +out: + if (path_ret) { + *path_ret = malloc(top->path_len + 1); + if (!*path_ret) + return BTRFS_UTIL_ERROR_NO_MEMORY; + memcpy(*path_ret, iter->cur_path, top->path_len); + (*path_ret)[top->path_len] = '\0'; + } + if (id_ret) + *id_ret = top->id; + return BTRFS_UTIL_OK; +} + PUBLIC enum btrfs_util_error btrfs_util_subvolume_iterator_next(struct btrfs_util_subvolume_iterator *iter, char **path_ret, uint64_t *id_ret) { - return subvolume_iterator_next_root(iter, path_ret, id_ret); + if (iter->use_tree_search) + return subvolume_iterator_next_root(iter, path_ret, id_ret); + else + return subvolume_iterator_next_user(iter, path_ret, id_ret); } PUBLIC enum btrfs_util_error btrfs_util_subvolume_iterator_next_info(struct btrfs_util_subvolume_iterator *iter, @@ -1344,12 +1602,23 @@ PUBLIC enum btrfs_util_error btrfs_util_subvolume_iterator_next_info(struct btrf { enum btrfs_util_error err; uint64_t id; + int fd; err = btrfs_util_subvolume_iterator_next(iter, path_ret, &id); if (err) return err; - return btrfs_util_subvolume_info_fd(iter->fd, id, subvol); + if (iter->use_tree_search) { + return btrfs_util_subvolume_info_fd(iter->fd, id, subvol); + } else { + fd = openat(iter->fd, *path_ret, O_RDONLY); + if (fd < 0) + return BTRFS_UTIL_ERROR_OPEN_FAILED; + + err = btrfs_util_subvolume_info_fd(fd, 0, subvol); + SAVE_ERRNO_AND_CLOSE(fd); + return err; + } } PUBLIC enum btrfs_util_error btrfs_util_deleted_subvolumes(const char *path,