diff options
Diffstat (limited to 'fs/libfs.c')
-rw-r--r-- | fs/libfs.c | 357 |
1 files changed, 245 insertions, 112 deletions
diff --git a/fs/libfs.c b/fs/libfs.c index 3a6f2cb364f8..9ea0ecc325a8 100644 --- a/fs/libfs.c +++ b/fs/libfs.c @@ -77,6 +77,10 @@ struct dentry *simple_lookup(struct inode *dir, struct dentry *dentry, unsigned return ERR_PTR(-ENAMETOOLONG); if (!dentry->d_sb->s_d_op) d_set_d_op(dentry, &simple_dentry_operations); + + if (IS_ENABLED(CONFIG_UNICODE) && IS_CASEFOLDED(dir)) + return NULL; + d_add(dentry, NULL); return NULL; } @@ -241,9 +245,16 @@ const struct inode_operations simple_dir_inode_operations = { }; EXPORT_SYMBOL(simple_dir_inode_operations); -/* 0 is '.', 1 is '..', so always start with offset 2 or more */ +/* simple_offset_add() never assigns these to a dentry */ enum { - DIR_OFFSET_MIN = 2, + DIR_OFFSET_FIRST = 2, /* Find first real entry */ + DIR_OFFSET_EOD = S32_MAX, +}; + +/* simple_offset_add() allocation range */ +enum { + DIR_OFFSET_MIN = DIR_OFFSET_FIRST + 1, + DIR_OFFSET_MAX = DIR_OFFSET_EOD - 1, }; static void offset_set(struct dentry *dentry, long offset) @@ -287,10 +298,23 @@ int simple_offset_add(struct offset_ctx *octx, struct dentry *dentry) return -EBUSY; ret = mtree_alloc_cyclic(&octx->mt, &offset, dentry, DIR_OFFSET_MIN, - LONG_MAX, &octx->next_offset, GFP_KERNEL); - if (ret < 0) - return ret; + DIR_OFFSET_MAX, &octx->next_offset, + GFP_KERNEL); + if (unlikely(ret < 0)) + return ret == -EBUSY ? -ENOSPC : ret; + + offset_set(dentry, offset); + return 0; +} + +static int simple_offset_replace(struct offset_ctx *octx, struct dentry *dentry, + long offset) +{ + int ret; + ret = mtree_store(&octx->mt, offset, dentry, GFP_KERNEL); + if (ret) + return ret; offset_set(dentry, offset); return 0; } @@ -314,35 +338,33 @@ void simple_offset_remove(struct offset_ctx *octx, struct dentry *dentry) } /** - * simple_offset_empty - Check if a dentry can be unlinked - * @dentry: dentry to be tested + * simple_offset_rename - handle directory offsets for rename + * @old_dir: parent directory of source entry + * @old_dentry: dentry of source entry + * @new_dir: parent_directory of destination entry + * @new_dentry: dentry of destination + * + * Caller provides appropriate serialization. + * + * User space expects the directory offset value of the replaced + * (new) directory entry to be unchanged after a rename. * - * Returns 0 if @dentry is a non-empty directory; otherwise returns 1. + * Returns zero on success, a negative errno value on failure. */ -int simple_offset_empty(struct dentry *dentry) +int simple_offset_rename(struct inode *old_dir, struct dentry *old_dentry, + struct inode *new_dir, struct dentry *new_dentry) { - struct inode *inode = d_inode(dentry); - struct offset_ctx *octx; - struct dentry *child; - unsigned long index; - int ret = 1; + struct offset_ctx *old_ctx = old_dir->i_op->get_offset_ctx(old_dir); + struct offset_ctx *new_ctx = new_dir->i_op->get_offset_ctx(new_dir); + long new_offset = dentry2offset(new_dentry); - if (!inode || !S_ISDIR(inode->i_mode)) - return ret; + simple_offset_remove(old_ctx, old_dentry); - index = DIR_OFFSET_MIN; - octx = inode->i_op->get_offset_ctx(inode); - mt_for_each(&octx->mt, child, index, LONG_MAX) { - spin_lock(&child->d_lock); - if (simple_positive(child)) { - spin_unlock(&child->d_lock); - ret = 0; - break; - } - spin_unlock(&child->d_lock); + if (new_offset) { + offset_set(new_dentry, 0); + return simple_offset_replace(new_ctx, old_dentry, new_offset); } - - return ret; + return simple_offset_add(new_ctx, old_dentry); } /** @@ -352,6 +374,9 @@ int simple_offset_empty(struct dentry *dentry) * @new_dir: destination parent * @new_dentry: destination dentry * + * This API preserves the directory offset values. Caller provides + * appropriate serialization. + * * Returns zero on success. Otherwise a negative errno is returned and the * rename is rolled back. */ @@ -369,11 +394,11 @@ int simple_offset_rename_exchange(struct inode *old_dir, simple_offset_remove(old_ctx, old_dentry); simple_offset_remove(new_ctx, new_dentry); - ret = simple_offset_add(new_ctx, old_dentry); + ret = simple_offset_replace(new_ctx, old_dentry, new_index); if (ret) goto out_restore; - ret = simple_offset_add(old_ctx, new_dentry); + ret = simple_offset_replace(old_ctx, new_dentry, old_index); if (ret) { simple_offset_remove(new_ctx, old_dentry); goto out_restore; @@ -388,10 +413,8 @@ int simple_offset_rename_exchange(struct inode *old_dir, return 0; out_restore: - offset_set(old_dentry, old_index); - mtree_store(&old_ctx->mt, old_index, old_dentry, GFP_KERNEL); - offset_set(new_dentry, new_index); - mtree_store(&new_ctx->mt, new_index, new_dentry, GFP_KERNEL); + (void)simple_offset_replace(old_ctx, old_dentry, old_index); + (void)simple_offset_replace(new_ctx, new_dentry, new_index); return ret; } @@ -432,57 +455,89 @@ static loff_t offset_dir_llseek(struct file *file, loff_t offset, int whence) return -EINVAL; } - /* In this case, ->private_data is protected by f_pos_lock */ - file->private_data = NULL; return vfs_setpos(file, offset, LONG_MAX); } -static struct dentry *offset_find_next(struct offset_ctx *octx, loff_t offset) +static struct dentry *find_positive_dentry(struct dentry *parent, + struct dentry *dentry, + bool next) { - MA_STATE(mas, &octx->mt, offset, offset); + struct dentry *found = NULL; + + spin_lock(&parent->d_lock); + if (next) + dentry = d_next_sibling(dentry); + else if (!dentry) + dentry = d_first_child(parent); + hlist_for_each_entry_from(dentry, d_sib) { + if (!simple_positive(dentry)) + continue; + spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); + if (simple_positive(dentry)) + found = dget_dlock(dentry); + spin_unlock(&dentry->d_lock); + if (likely(found)) + break; + } + spin_unlock(&parent->d_lock); + return found; +} + +static noinline_for_stack struct dentry * +offset_dir_lookup(struct dentry *parent, loff_t offset) +{ + struct inode *inode = d_inode(parent); + struct offset_ctx *octx = inode->i_op->get_offset_ctx(inode); struct dentry *child, *found = NULL; - rcu_read_lock(); - child = mas_find(&mas, LONG_MAX); - if (!child) - goto out; - spin_lock(&child->d_lock); - if (simple_positive(child)) - found = dget_dlock(child); - spin_unlock(&child->d_lock); -out: - rcu_read_unlock(); + MA_STATE(mas, &octx->mt, offset, offset); + + if (offset == DIR_OFFSET_FIRST) + found = find_positive_dentry(parent, NULL, false); + else { + rcu_read_lock(); + child = mas_find_rev(&mas, DIR_OFFSET_MIN); + found = find_positive_dentry(parent, child, false); + rcu_read_unlock(); + } return found; } static bool offset_dir_emit(struct dir_context *ctx, struct dentry *dentry) { struct inode *inode = d_inode(dentry); - long offset = dentry2offset(dentry); - return ctx->actor(ctx, dentry->d_name.name, dentry->d_name.len, offset, - inode->i_ino, fs_umode_to_dtype(inode->i_mode)); + return dir_emit(ctx, dentry->d_name.name, dentry->d_name.len, + inode->i_ino, fs_umode_to_dtype(inode->i_mode)); } -static void *offset_iterate_dir(struct inode *inode, struct dir_context *ctx) +static void offset_iterate_dir(struct file *file, struct dir_context *ctx) { - struct offset_ctx *octx = inode->i_op->get_offset_ctx(inode); + struct dentry *dir = file->f_path.dentry; struct dentry *dentry; + dentry = offset_dir_lookup(dir, ctx->pos); + if (!dentry) + goto out_eod; while (true) { - dentry = offset_find_next(octx, ctx->pos); - if (!dentry) - return ERR_PTR(-ENOENT); + struct dentry *next; - if (!offset_dir_emit(ctx, dentry)) { - dput(dentry); + ctx->pos = dentry2offset(dentry); + if (!offset_dir_emit(ctx, dentry)) break; - } - ctx->pos = dentry2offset(dentry) + 1; + next = find_positive_dentry(dir, dentry, true); dput(dentry); + + if (!next) + goto out_eod; + dentry = next; } - return NULL; + dput(dentry); + return; + +out_eod: + ctx->pos = DIR_OFFSET_EOD; } /** @@ -502,6 +557,8 @@ static void *offset_iterate_dir(struct inode *inode, struct dir_context *ctx) * * On return, @ctx->pos contains an offset that will read the next entry * in this directory when offset_readdir() is called again with @ctx. + * Caller places this value in the d_off field of the last entry in the + * user's buffer. * * Return values: * %0 - Complete @@ -514,13 +571,8 @@ static int offset_readdir(struct file *file, struct dir_context *ctx) if (!dir_emit_dots(file, ctx)) return 0; - - /* In this case, ->private_data is protected by f_pos_lock */ - if (ctx->pos == DIR_OFFSET_MIN) - file->private_data = NULL; - else if (file->private_data == ERR_PTR(-ENOENT)) - return 0; - file->private_data = offset_iterate_dir(d_inode(dir), ctx); + if (ctx->pos != DIR_OFFSET_EOD) + offset_iterate_dir(file, ctx); return 0; } @@ -531,7 +583,7 @@ const struct file_operations simple_offset_dir_operations = { .fsync = noop_fsync, }; -static struct dentry *find_next_child(struct dentry *parent, struct dentry *prev) +struct dentry *find_next_child(struct dentry *parent, struct dentry *prev) { struct dentry *child = NULL, *d; @@ -551,6 +603,7 @@ static struct dentry *find_next_child(struct dentry *parent, struct dentry *prev dput(prev); return child; } +EXPORT_SYMBOL(find_next_child); void simple_recursive_removal(struct dentry *dentry, void (*callback)(struct dentry *)) @@ -613,6 +666,7 @@ static int pseudo_fs_fill_super(struct super_block *s, struct fs_context *fc) s->s_blocksize_bits = PAGE_SHIFT; s->s_magic = ctx->magic; s->s_op = ctx->ops ?: &simple_super_operations; + s->s_export_op = ctx->eops; s->s_xattr = ctx->xattr; s->s_time_gran = 1; root = new_inode(s); @@ -858,7 +912,7 @@ static int simple_read_folio(struct file *file, struct folio *folio) int simple_write_begin(struct file *file, struct address_space *mapping, loff_t pos, unsigned len, - struct page **pagep, void **fsdata) + struct folio **foliop, void **fsdata) { struct folio *folio; @@ -867,7 +921,7 @@ int simple_write_begin(struct file *file, struct address_space *mapping, if (IS_ERR(folio)) return PTR_ERR(folio); - *pagep = &folio->page; + *foliop = folio; if (!folio_test_uptodate(folio) && (len != folio_size(folio))) { size_t from = offset_in_folio(folio, pos); @@ -886,11 +940,11 @@ EXPORT_SYMBOL(simple_write_begin); * @pos: " * @len: " * @copied: " - * @page: " + * @folio: " * @fsdata: " * - * simple_write_end does the minimum needed for updating a page after writing is - * done. It has the same API signature as the .write_end of + * simple_write_end does the minimum needed for updating a folio after + * writing is done. It has the same API signature as the .write_end of * address_space_operations vector. So it can just be set onto .write_end for * FSes that don't need any other processing. i_mutex is assumed to be held. * Block based filesystems should use generic_write_end(). @@ -903,9 +957,8 @@ EXPORT_SYMBOL(simple_write_begin); */ static int simple_write_end(struct file *file, struct address_space *mapping, loff_t pos, unsigned len, unsigned copied, - struct page *page, void *fsdata) + struct folio *folio, void *fsdata) { - struct folio *folio = page_folio(page); struct inode *inode = folio->mapping->host; loff_t last_pos = pos + copied; @@ -1595,10 +1648,16 @@ struct inode *alloc_anon_inode(struct super_block *s) * that it already _is_ on the dirty list. */ inode->i_state = I_DIRTY; - inode->i_mode = S_IRUSR | S_IWUSR; + /* + * Historically anonymous inodes didn't have a type at all and + * userspace has come to rely on this. Internally they're just + * regular files but S_IFREG is masked off when reporting + * information to userspace. + */ + inode->i_mode = S_IFREG | S_IRUSR | S_IWUSR; inode->i_uid = current_fsuid(); inode->i_gid = current_fsgid(); - inode->i_flags |= S_PRIVATE; + inode->i_flags |= S_PRIVATE | S_ANON_INODE; simple_inode_init_ts(inode); return inode; } @@ -1656,15 +1715,6 @@ static struct dentry *empty_dir_lookup(struct inode *dir, struct dentry *dentry, return ERR_PTR(-ENOENT); } -static int empty_dir_getattr(struct mnt_idmap *idmap, - const struct path *path, struct kstat *stat, - u32 request_mask, unsigned int query_flags) -{ - struct inode *inode = d_inode(path->dentry); - generic_fillattr(&nop_mnt_idmap, request_mask, inode, stat); - return 0; -} - static int empty_dir_setattr(struct mnt_idmap *idmap, struct dentry *dentry, struct iattr *attr) { @@ -1678,9 +1728,7 @@ static ssize_t empty_dir_listxattr(struct dentry *dentry, char *list, size_t siz static const struct inode_operations empty_dir_inode_operations = { .lookup = empty_dir_lookup, - .permission = generic_permission, .setattr = empty_dir_setattr, - .getattr = empty_dir_getattr, .listxattr = empty_dir_listxattr, }; @@ -1736,12 +1784,12 @@ bool is_empty_dir_inode(struct inode *inode) * * Return: 0 if names match, 1 if mismatch, or -ERRNO */ -static int generic_ci_d_compare(const struct dentry *dentry, unsigned int len, - const char *str, const struct qstr *name) +int generic_ci_d_compare(const struct dentry *dentry, unsigned int len, + const char *str, const struct qstr *name) { const struct dentry *parent; const struct inode *dir; - char strbuf[DNAME_INLINE_LEN]; + union shortname_store strbuf; struct qstr qstr; /* @@ -1761,25 +1809,27 @@ static int generic_ci_d_compare(const struct dentry *dentry, unsigned int len, if (!dir || !IS_CASEFOLDED(dir)) return 1; + qstr.len = len; + qstr.name = str; /* * If the dentry name is stored in-line, then it may be concurrently * modified by a rename. If this happens, the VFS will eventually retry * the lookup, so it doesn't matter what ->d_compare() returns. * However, it's unsafe to call utf8_strncasecmp() with an unstable * string. Therefore, we have to copy the name into a temporary buffer. + * As above, len is guaranteed to match str, so the shortname case + * is exactly when str points to ->d_shortname. */ - if (len <= DNAME_INLINE_LEN - 1) { - memcpy(strbuf, str, len); - strbuf[len] = 0; - str = strbuf; + if (qstr.name == dentry->d_shortname.string) { + strbuf = dentry->d_shortname; // NUL is guaranteed to be in there + qstr.name = strbuf.string; /* prevent compiler from optimizing out the temporary buffer */ barrier(); } - qstr.len = len; - qstr.name = str; return utf8_strncasecmp(dentry->d_sb->s_encoding, name, &qstr); } +EXPORT_SYMBOL(generic_ci_d_compare); /** * generic_ci_d_hash - generic d_hash implementation for casefolding filesystems @@ -1788,7 +1838,7 @@ static int generic_ci_d_compare(const struct dentry *dentry, unsigned int len, * * Return: 0 if hash was successful or unchanged, and -EINVAL on error */ -static int generic_ci_d_hash(const struct dentry *dentry, struct qstr *str) +int generic_ci_d_hash(const struct dentry *dentry, struct qstr *str) { const struct inode *dir = READ_ONCE(dentry->d_inode); struct super_block *sb = dentry->d_sb; @@ -1803,6 +1853,7 @@ static int generic_ci_d_hash(const struct dentry *dentry, struct qstr *str) return -EINVAL; return 0; } +EXPORT_SYMBOL(generic_ci_d_hash); static const struct dentry_operations generic_ci_dentry_ops = { .d_hash = generic_ci_d_hash, @@ -1811,6 +1862,80 @@ static const struct dentry_operations generic_ci_dentry_ops = { .d_revalidate = fscrypt_d_revalidate, #endif }; + +/** + * generic_ci_match() - Match a name (case-insensitively) with a dirent. + * This is a filesystem helper for comparison with directory entries. + * generic_ci_d_compare should be used in VFS' ->d_compare instead. + * + * @parent: Inode of the parent of the dirent under comparison + * @name: name under lookup. + * @folded_name: Optional pre-folded name under lookup + * @de_name: Dirent name. + * @de_name_len: dirent name length. + * + * Test whether a case-insensitive directory entry matches the filename + * being searched. If @folded_name is provided, it is used instead of + * recalculating the casefold of @name. + * + * Return: > 0 if the directory entry matches, 0 if it doesn't match, or + * < 0 on error. + */ +int generic_ci_match(const struct inode *parent, + const struct qstr *name, + const struct qstr *folded_name, + const u8 *de_name, u32 de_name_len) +{ + const struct super_block *sb = parent->i_sb; + const struct unicode_map *um = sb->s_encoding; + struct fscrypt_str decrypted_name = FSTR_INIT(NULL, de_name_len); + struct qstr dirent = QSTR_INIT(de_name, de_name_len); + int res = 0; + + if (IS_ENCRYPTED(parent)) { + const struct fscrypt_str encrypted_name = + FSTR_INIT((u8 *) de_name, de_name_len); + + if (WARN_ON_ONCE(!fscrypt_has_encryption_key(parent))) + return -EINVAL; + + decrypted_name.name = kmalloc(de_name_len, GFP_KERNEL); + if (!decrypted_name.name) + return -ENOMEM; + res = fscrypt_fname_disk_to_usr(parent, 0, 0, &encrypted_name, + &decrypted_name); + if (res < 0) { + kfree(decrypted_name.name); + return res; + } + dirent.name = decrypted_name.name; + dirent.len = decrypted_name.len; + } + + /* + * Attempt a case-sensitive match first. It is cheaper and + * should cover most lookups, including all the sane + * applications that expect a case-sensitive filesystem. + */ + + if (dirent.len == name->len && + !memcmp(name->name, dirent.name, dirent.len)) + goto out; + + if (folded_name->name) + res = utf8_strncasecmp_folded(um, folded_name, &dirent); + else + res = utf8_strncasecmp(um, name, &dirent); + +out: + kfree(decrypted_name.name); + if (res < 0 && sb_has_strict_encoding(sb)) { + pr_err_ratelimited("Directory contains filename that is invalid UTF-8"); + return 0; + } + return !res; +} +EXPORT_SYMBOL(generic_ci_match); #endif #ifdef CONFIG_FS_ENCRYPTION @@ -1873,13 +1998,19 @@ bool inode_maybe_inc_iversion(struct inode *inode, bool force) * information, but the legacy inode_inc_iversion code used a spinlock * to serialize increments. * - * Here, we add full memory barriers to ensure that any de-facto - * ordering with other info is preserved. + * We add a full memory barrier to ensure that any de facto ordering + * with other state is preserved (either implicitly coming from cmpxchg + * or explicitly from smp_mb if we don't know upfront if we will execute + * the former). * - * This barrier pairs with the barrier in inode_query_iversion() + * These barriers pair with inode_query_iversion(). */ - smp_mb(); cur = inode_peek_iversion_raw(inode); + if (!force && !(cur & I_VERSION_QUERIED)) { + smp_mb(); + cur = inode_peek_iversion_raw(inode); + } + do { /* If flag is clear then we needn't do anything */ if (!force && !(cur & I_VERSION_QUERIED)) @@ -1908,20 +2039,22 @@ EXPORT_SYMBOL(inode_maybe_inc_iversion); u64 inode_query_iversion(struct inode *inode) { u64 cur, new; + bool fenced = false; + /* + * Memory barriers (implicit in cmpxchg, explicit in smp_mb) pair with + * inode_maybe_inc_iversion(), see that routine for more details. + */ cur = inode_peek_iversion_raw(inode); do { /* If flag is already set, then no need to swap */ if (cur & I_VERSION_QUERIED) { - /* - * This barrier (and the implicit barrier in the - * cmpxchg below) pairs with the barrier in - * inode_maybe_inc_iversion(). - */ - smp_mb(); + if (!fenced) + smp_mb(); break; } + fenced = true; new = cur | I_VERSION_QUERIED; } while (!atomic64_try_cmpxchg(&inode->i_version, &cur, new)); return cur >> I_VERSION_QUERIED_SHIFT; @@ -1987,12 +2120,12 @@ struct timespec64 simple_inode_init_ts(struct inode *inode) } EXPORT_SYMBOL(simple_inode_init_ts); -static inline struct dentry *get_stashed_dentry(struct dentry *stashed) +struct dentry *stashed_dentry_get(struct dentry **stashed) { struct dentry *dentry; guard(rcu)(); - dentry = READ_ONCE(stashed); + dentry = rcu_dereference(*stashed); if (!dentry) return NULL; if (!lockref_get_not_dead(&dentry->d_lockref)) @@ -2089,7 +2222,7 @@ int path_from_stashed(struct dentry **stashed, struct vfsmount *mnt, void *data, const struct stashed_operations *sops = mnt->mnt_sb->s_fs_info; /* See if dentry can be reused. */ - path->dentry = get_stashed_dentry(*stashed); + path->dentry = stashed_dentry_get(stashed); if (path->dentry) { sops->put_data(data); goto out_path; |