diff options
Diffstat (limited to 'libbtrfsutil/subvolume.c')
| -rw-r--r-- | libbtrfsutil/subvolume.c | 446 |
1 files changed, 379 insertions, 67 deletions
diff --git a/libbtrfsutil/subvolume.c b/libbtrfsutil/subvolume.c index 867b3e10..60ab9f9d 100644 --- a/libbtrfsutil/subvolume.c +++ b/libbtrfsutil/subvolume.c @@ -31,6 +31,11 @@ #include "btrfsutil_internal.h" +static bool is_root(void) +{ + return geteuid() == 0; +} + /* * This intentionally duplicates btrfs_util_is_subvolume_fd() instead of opening * a file descriptor and calling it, because fstat() and fstatfs() don't accept @@ -295,8 +300,8 @@ PUBLIC enum btrfs_util_error btrfs_util_subvolume_info(const char *path, return err; } -PUBLIC enum btrfs_util_error btrfs_util_subvolume_info_fd(int fd, uint64_t id, - struct btrfs_util_subvolume_info *subvol) +static enum btrfs_util_error get_subvolume_info_privileged(int fd, uint64_t id, + struct btrfs_util_subvolume_info *subvol) { struct btrfs_ioctl_search_args search = { .key = { @@ -310,27 +315,10 @@ PUBLIC enum btrfs_util_error btrfs_util_subvolume_info_fd(int fd, uint64_t id, .nr_items = 0, }, }; - enum btrfs_util_error err; size_t items_pos = 0, buf_off = 0; bool need_root_item = true, need_root_backref = true; int ret; - if (id == 0) { - err = btrfs_util_is_subvolume_fd(fd); - if (err) - return err; - - err = btrfs_util_subvolume_id_fd(fd, &id); - if (err) - return err; - } - - if ((id < BTRFS_FIRST_FREE_OBJECTID && id != BTRFS_FS_TREE_OBJECTID) || - id > BTRFS_LAST_FREE_OBJECTID) { - errno = ENOENT; - return BTRFS_UTIL_ERROR_SUBVOLUME_NOT_FOUND; - } - search.key.min_objectid = search.key.max_objectid = id; if (subvol) { @@ -400,6 +388,72 @@ PUBLIC enum btrfs_util_error btrfs_util_subvolume_info_fd(int fd, uint64_t id, return BTRFS_UTIL_OK; } +static enum btrfs_util_error get_subvolume_info_unprivileged(int fd, + struct btrfs_util_subvolume_info *subvol) +{ + struct btrfs_ioctl_get_subvol_info_args info; + int ret; + + ret = ioctl(fd, BTRFS_IOC_GET_SUBVOL_INFO, &info); + if (ret == -1) + return BTRFS_UTIL_ERROR_GET_SUBVOL_INFO_FAILED; + + subvol->id = info.treeid; + subvol->parent_id = info.parent_id; + subvol->dir_id = info.dirid; + subvol->flags = info.flags; + subvol->generation = info.generation; + + memcpy(subvol->uuid, info.uuid, sizeof(subvol->uuid)); + memcpy(subvol->parent_uuid, info.parent_uuid, + sizeof(subvol->parent_uuid)); + memcpy(subvol->received_uuid, info.received_uuid, + sizeof(subvol->received_uuid)); + + subvol->ctransid = info.ctransid; + subvol->otransid = info.otransid; + subvol->stransid = info.stransid; + subvol->rtransid = info.rtransid; + + subvol->ctime.tv_sec = info.ctime.sec; + subvol->ctime.tv_nsec = info.ctime.nsec; + subvol->otime.tv_sec = info.otime.sec; + subvol->otime.tv_nsec = info.otime.nsec; + subvol->stime.tv_sec = info.stime.sec; + subvol->stime.tv_nsec = info.stime.nsec; + subvol->rtime.tv_sec = info.rtime.sec; + subvol->rtime.tv_nsec = info.rtime.nsec; + + return BTRFS_UTIL_OK; +} + +PUBLIC enum btrfs_util_error btrfs_util_subvolume_info_fd(int fd, uint64_t id, + struct btrfs_util_subvolume_info *subvol) +{ + enum btrfs_util_error err; + + if (id == 0) { + err = btrfs_util_is_subvolume_fd(fd); + if (err) + return err; + + if (!is_root()) + return get_subvolume_info_unprivileged(fd, subvol); + + err = btrfs_util_subvolume_id_fd(fd, &id); + if (err) + return err; + } + + if ((id < BTRFS_FIRST_FREE_OBJECTID && id != BTRFS_FS_TREE_OBJECTID) || + id > BTRFS_LAST_FREE_OBJECTID) { + errno = ENOENT; + return BTRFS_UTIL_ERROR_SUBVOLUME_NOT_FOUND; + } + + return get_subvolume_info_privileged(fd, id, subvol); +} + PUBLIC enum btrfs_util_error btrfs_util_get_subvolume_read_only_fd(int fd, bool *read_only_ret) { @@ -695,13 +749,28 @@ 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 { - struct btrfs_ioctl_search_args search; - size_t items_pos, buf_off; + union { + /* Used for subvolume_iterator_next_tree_search(). */ + struct { + struct btrfs_ioctl_search_args search; + size_t buf_off; + }; + /* Used for subvolume_iterator_next_unprivileged(). */ + struct { + uint64_t id; + struct btrfs_ioctl_get_subvol_rootref_args rootref_args; + }; + }; + /* Used for both. */ + size_t items_pos; size_t path_len; }; struct btrfs_util_subvolume_iterator { + bool use_tree_search; int fd; + /* cur_fd is only used for subvolume_iterator_next_unprivileged(). */ + int cur_fd; int flags; struct search_stack_entry *search_stack; @@ -712,6 +781,58 @@ struct btrfs_util_subvolume_iterator { size_t cur_path_capacity; }; +static struct search_stack_entry *top_search_stack_entry(struct btrfs_util_subvolume_iterator *iter) +{ + return &iter->search_stack[iter->search_stack_len - 1]; +} + +/* + * Check that a path that we opened is the subvolume which we expect. It may not + * be if there is another filesystem mounted over a parent directory or the + * subvolume itself. + */ +static enum btrfs_util_error check_expected_subvolume(int fd, int parent_fd, + uint64_t tree_id) +{ + struct btrfs_ioctl_fs_info_args parent_fs_info, fs_info; + enum btrfs_util_error err; + uint64_t id; + int ret; + + /* Make sure it's a subvolume. */ + err = btrfs_util_is_subvolume_fd(fd); + if (err == BTRFS_UTIL_ERROR_NOT_BTRFS || + err == BTRFS_UTIL_ERROR_NOT_SUBVOLUME) { + errno = ENOENT; + return BTRFS_UTIL_ERROR_SUBVOLUME_NOT_FOUND; + } else if (err) { + return err; + } + + /* Make sure it's on the same filesystem. */ + ret = ioctl(parent_fd, BTRFS_IOC_FS_INFO, &parent_fs_info); + if (ret == -1) + return BTRFS_UTIL_ERROR_FS_INFO_FAILED; + ret = ioctl(fd, BTRFS_IOC_FS_INFO, &fs_info); + if (ret == -1) + return BTRFS_UTIL_ERROR_FS_INFO_FAILED; + if (memcmp(parent_fs_info.fsid, fs_info.fsid, sizeof(fs_info.fsid)) != 0) { + errno = ENOENT; + return BTRFS_UTIL_ERROR_SUBVOLUME_NOT_FOUND; + } + + /* Make sure it's the subvolume that we expected. */ + err = btrfs_util_subvolume_id_fd(fd, &id); + if (err) + return err; + if (id != tree_id) { + errno = ENOENT; + return BTRFS_UTIL_ERROR_SUBVOLUME_NOT_FOUND; + } + + return BTRFS_UTIL_OK; +} + static enum btrfs_util_error append_to_search_stack(struct btrfs_util_subvolume_iterator *iter, uint64_t tree_id, size_t path_len) @@ -732,24 +853,84 @@ static enum btrfs_util_error append_to_search_stack(struct btrfs_util_subvolume_ iter->search_stack = new_search_stack; } - entry = &iter->search_stack[iter->search_stack_len++]; + 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; + memset(entry, 0, sizeof(*entry)); + entry->path_len = path_len; + if (iter->use_tree_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; + } else { + entry->id = tree_id; - entry->items_pos = 0; - entry->buf_off = 0; + if (iter->search_stack_len) { + struct search_stack_entry *top; + enum btrfs_util_error err; + char *path; + int fd; - entry->path_len = path_len; + top = top_search_stack_entry(iter); + path = &iter->cur_path[top->path_len]; + if (*path == '/') + path++; + fd = openat(iter->cur_fd, path, O_RDONLY); + if (fd == -1) + return BTRFS_UTIL_ERROR_OPEN_FAILED; + + err = check_expected_subvolume(fd, iter->cur_fd, + tree_id); + if (err) { + close(fd); + return err; + } + + close(iter->cur_fd); + iter->cur_fd = fd; + } + } + + iter->search_stack_len++; + + return BTRFS_UTIL_OK; +} + +static enum btrfs_util_error pop_search_stack(struct btrfs_util_subvolume_iterator *iter) +{ + struct search_stack_entry *top, *parent; + int fd, parent_fd; + size_t i; + + if (iter->use_tree_search || iter->search_stack_len == 1) { + iter->search_stack_len--; + return BTRFS_UTIL_OK; + } + + top = top_search_stack_entry(iter); + iter->search_stack_len--; + parent = top_search_stack_entry(iter); + + fd = iter->cur_fd; + for (i = parent->path_len; i < top->path_len; i++) { + if (i == 0 || iter->cur_path[i] == '/') { + parent_fd = openat(fd, "..", O_RDONLY); + if (fd != iter->cur_fd) + SAVE_ERRNO_AND_CLOSE(fd); + if (parent_fd == -1) + return BTRFS_UTIL_ERROR_OPEN_FAILED; + fd = parent_fd; + } + } + if (iter->cur_fd != iter->fd) + close(iter->cur_fd); + iter->cur_fd = fd; return BTRFS_UTIL_OK; } @@ -782,12 +963,14 @@ 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; if (flags & ~BTRFS_UTIL_SUBVOLUME_ITERATOR_MASK) { errno = EINVAL; return BTRFS_UTIL_ERROR_INVALID_ARGUMENT; } + use_tree_search = top != 0 || is_root(); if (top == 0) { err = btrfs_util_is_subvolume_fd(fd); if (err) @@ -803,7 +986,9 @@ PUBLIC enum btrfs_util_error btrfs_util_create_subvolume_iterator_fd(int fd, return BTRFS_UTIL_ERROR_NO_MEMORY; iter->fd = fd; + iter->cur_fd = fd; iter->flags = flags; + iter->use_tree_search = use_tree_search; iter->search_stack_len = 0; iter->search_stack_capacity = 4; @@ -1112,6 +1297,8 @@ PUBLIC void btrfs_util_destroy_subvolume_iterator(struct btrfs_util_subvolume_it if (iter) { free(iter->cur_path); free(iter->search_stack); + if (iter->cur_fd != iter->fd) + SAVE_ERRNO_AND_CLOSE(iter->cur_fd); if (iter->flags & BTRFS_UTIL_SUBVOLUME_ITERATOR_CLOSE_FD) SAVE_ERRNO_AND_CLOSE(iter->fd); free(iter); @@ -1123,32 +1310,14 @@ PUBLIC int btrfs_util_subvolume_iterator_fd(const struct btrfs_util_subvolume_it return iter->fd; } -static struct search_stack_entry *top_search_stack_entry(struct btrfs_util_subvolume_iterator *iter) -{ - return &iter->search_stack[iter->search_stack_len - 1]; -} - static enum btrfs_util_error build_subvol_path(struct btrfs_util_subvolume_iterator *iter, - const struct btrfs_ioctl_search_header *header, - const struct btrfs_root_ref *ref, - const char *name, + const char *name, size_t name_len, + const char *dir, size_t dir_len, size_t *path_len_ret) { - struct btrfs_ioctl_ino_lookup_args lookup = { - .treeid = header->objectid, - .objectid = le64_to_cpu(ref->dirid), - }; struct search_stack_entry *top = top_search_stack_entry(iter); - size_t dir_len, name_len, path_len; + size_t path_len; char *p; - int ret; - - ret = ioctl(iter->fd, BTRFS_IOC_INO_LOOKUP, &lookup); - if (ret == -1) - return BTRFS_UTIL_ERROR_INO_LOOKUP_FAILED; - - dir_len = strlen(lookup.name); - name_len = le16_to_cpu(ref->name_len); path_len = top->path_len; /* @@ -1166,33 +1335,75 @@ static enum btrfs_util_error build_subvol_path(struct btrfs_util_subvolume_itera path_len++; path_len += name_len; - if (path_len > iter->cur_path_capacity) { - char *tmp = realloc(iter->cur_path, path_len); + /* We need one extra character for the NUL terminator. */ + if (path_len + 1 > iter->cur_path_capacity) { + char *tmp = realloc(iter->cur_path, path_len + 1); if (!tmp) return BTRFS_UTIL_ERROR_NO_MEMORY; iter->cur_path = tmp; - iter->cur_path_capacity = path_len; + iter->cur_path_capacity = path_len + 1; } p = iter->cur_path + top->path_len; if (top->path_len && dir_len) *p++ = '/'; - memcpy(p, lookup.name, dir_len); + memcpy(p, dir, dir_len); p += dir_len; if (top->path_len && !dir_len && name_len) *p++ = '/'; memcpy(p, name, name_len); p += name_len; + *p = '\0'; *path_len_ret = path_len; 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) +static enum btrfs_util_error build_subvol_path_privileged(struct btrfs_util_subvolume_iterator *iter, + const struct btrfs_ioctl_search_header *header, + const struct btrfs_root_ref *ref, + const char *name, + size_t *path_len_ret) +{ + struct btrfs_ioctl_ino_lookup_args lookup = { + .treeid = header->objectid, + .objectid = le64_to_cpu(ref->dirid), + }; + int ret; + + ret = ioctl(iter->fd, BTRFS_IOC_INO_LOOKUP, &lookup); + if (ret == -1) + return BTRFS_UTIL_ERROR_INO_LOOKUP_FAILED; + + return build_subvol_path(iter, name, le16_to_cpu(ref->name_len), + lookup.name, strlen(lookup.name), + path_len_ret); +} + +static enum btrfs_util_error build_subvol_path_unprivileged(struct btrfs_util_subvolume_iterator *iter, + uint64_t treeid, + uint64_t dirid, + size_t *path_len_ret) +{ + struct btrfs_ioctl_ino_lookup_user_args args = { + .treeid = treeid, + .dirid = dirid, + }; + int ret; + + ret = ioctl(iter->cur_fd, BTRFS_IOC_INO_LOOKUP_USER, &args); + if (ret == -1) + return BTRFS_UTIL_ERROR_INO_LOOKUP_USER_FAILED; + + return build_subvol_path(iter, args.name, strlen(args.name), + args.path, strlen(args.path), path_len_ret); +} + +static enum btrfs_util_error subvolume_iterator_next_tree_search(struct btrfs_util_subvolume_iterator *iter, + char **path_ret, + uint64_t *id_ret) { struct search_stack_entry *top; const struct btrfs_ioctl_search_header *header; @@ -1219,7 +1430,10 @@ PUBLIC enum btrfs_util_error btrfs_util_subvolume_iterator_next(struct btrfs_uti top->buf_off = 0; if (top->search.key.nr_items == 0) { - iter->search_stack_len--; + /* + * This never fails for use_tree_search. + */ + pop_search_stack(iter); if ((iter->flags & BTRFS_UTIL_SUBVOLUME_ITERATOR_POST_ORDER) && iter->search_stack_len) goto out; @@ -1239,7 +1453,8 @@ PUBLIC enum btrfs_util_error btrfs_util_subvolume_iterator_next(struct btrfs_uti ref = (struct btrfs_root_ref *)(header + 1); name = (const char *)(ref + 1); - err = build_subvol_path(iter, header, ref, name, &path_len); + err = build_subvol_path_privileged(iter, header, ref, name, + &path_len); if (err) return err; @@ -1266,6 +1481,100 @@ out: return BTRFS_UTIL_OK; } +static enum btrfs_util_error subvolume_iterator_next_unprivileged(struct btrfs_util_subvolume_iterator *iter, + char **path_ret, + uint64_t *id_ret) +{ + struct search_stack_entry *top; + uint64_t treeid, dirid; + enum btrfs_util_error err; + size_t path_len; + int ret; + + for (;;) { + for (;;) { + if (iter->search_stack_len == 0) + return BTRFS_UTIL_ERROR_STOP_ITERATION; + + top = top_search_stack_entry(iter); + if (top->items_pos < top->rootref_args.num_items) { + break; + } else { + ret = ioctl(iter->cur_fd, + BTRFS_IOC_GET_SUBVOL_ROOTREF, + &top->rootref_args); + if (ret == -1 && errno != EOVERFLOW) + return BTRFS_UTIL_ERROR_GET_SUBVOL_ROOTREF_FAILED; + top->items_pos = 0; + + if (top->rootref_args.num_items == 0) { + err = pop_search_stack(iter); + if (err) + return err; + if ((iter->flags & BTRFS_UTIL_SUBVOLUME_ITERATOR_POST_ORDER) && + iter->search_stack_len) + goto out; + } + } + } + + treeid = top->rootref_args.rootref[top->items_pos].treeid; + dirid = top->rootref_args.rootref[top->items_pos].dirid; + top->items_pos++; + err = build_subvol_path_unprivileged(iter, treeid, dirid, + &path_len); + if (err) { + /* Skip the subvolume if we can't access it. */ + if (errno == EACCES) + continue; + return err; + } + + err = append_to_search_stack(iter, treeid, path_len); + if (err) { + /* + * Skip the subvolume if it does not exist (which can + * happen if there is another filesystem mounted over a + * parent directory) or we don't have permission to + * access it. + */ + if (errno == ENOENT || errno == EACCES) + continue; + 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) +{ + if (iter->use_tree_search) { + return subvolume_iterator_next_tree_search(iter, path_ret, + id_ret); + } else { + return subvolume_iterator_next_unprivileged(iter, path_ret, + id_ret); + } +} + PUBLIC enum btrfs_util_error btrfs_util_subvolume_iterator_next_info(struct btrfs_util_subvolume_iterator *iter, char **path_ret, struct btrfs_util_subvolume_info *subvol) @@ -1277,7 +1586,10 @@ PUBLIC enum btrfs_util_error btrfs_util_subvolume_iterator_next_info(struct btrf 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 + return btrfs_util_subvolume_info_fd(iter->cur_fd, 0, subvol); } PUBLIC enum btrfs_util_error btrfs_util_deleted_subvolumes(const char *path, |