diff options
Diffstat (limited to 'fs/overlayfs/readdir.c')
| -rw-r--r-- | fs/overlayfs/readdir.c | 1232 |
1 files changed, 1232 insertions, 0 deletions
diff --git a/fs/overlayfs/readdir.c b/fs/overlayfs/readdir.c new file mode 100644 index 000000000..cc1e80257 --- /dev/null +++ b/fs/overlayfs/readdir.c @@ -0,0 +1,1232 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * + * Copyright (C) 2011 Novell Inc. + */ + +#include <linux/fs.h> +#include <linux/slab.h> +#include <linux/namei.h> +#include <linux/file.h> +#include <linux/xattr.h> +#include <linux/rbtree.h> +#include <linux/security.h> +#include <linux/cred.h> +#include <linux/ratelimit.h> +#include "overlayfs.h" + +struct ovl_cache_entry { + unsigned int len; + unsigned int type; + u64 real_ino; + u64 ino; + struct list_head l_node; + struct rb_node node; + struct ovl_cache_entry *next_maybe_whiteout; + bool is_upper; + bool is_whiteout; + char name[]; +}; + +struct ovl_dir_cache { + long refcount; + u64 version; + struct list_head entries; + struct rb_root root; +}; + +struct ovl_readdir_data { + struct dir_context ctx; + struct dentry *dentry; + bool is_lowest; + struct rb_root *root; + struct list_head *list; + struct list_head middle; + struct ovl_cache_entry *first_maybe_whiteout; + int count; + int err; + bool is_upper; + bool d_type_supported; +}; + +struct ovl_dir_file { + bool is_real; + bool is_upper; + struct ovl_dir_cache *cache; + struct list_head *cursor; + struct file *realfile; + struct file *upperfile; +}; + +static struct ovl_cache_entry *ovl_cache_entry_from_node(struct rb_node *n) +{ + return rb_entry(n, struct ovl_cache_entry, node); +} + +static bool ovl_cache_entry_find_link(const char *name, int len, + struct rb_node ***link, + struct rb_node **parent) +{ + bool found = false; + struct rb_node **newp = *link; + + while (!found && *newp) { + int cmp; + struct ovl_cache_entry *tmp; + + *parent = *newp; + tmp = ovl_cache_entry_from_node(*newp); + cmp = strncmp(name, tmp->name, len); + if (cmp > 0) + newp = &tmp->node.rb_right; + else if (cmp < 0 || len < tmp->len) + newp = &tmp->node.rb_left; + else + found = true; + } + *link = newp; + + return found; +} + +static struct ovl_cache_entry *ovl_cache_entry_find(struct rb_root *root, + const char *name, int len) +{ + struct rb_node *node = root->rb_node; + int cmp; + + while (node) { + struct ovl_cache_entry *p = ovl_cache_entry_from_node(node); + + cmp = strncmp(name, p->name, len); + if (cmp > 0) + node = p->node.rb_right; + else if (cmp < 0 || len < p->len) + node = p->node.rb_left; + else + return p; + } + + return NULL; +} + +static bool ovl_calc_d_ino(struct ovl_readdir_data *rdd, + struct ovl_cache_entry *p) +{ + /* Don't care if not doing ovl_iter() */ + if (!rdd->dentry) + return false; + + /* Always recalc d_ino when remapping lower inode numbers */ + if (ovl_xino_bits(rdd->dentry->d_sb)) + return true; + + /* Always recalc d_ino for parent */ + if (strcmp(p->name, "..") == 0) + return true; + + /* If this is lower, then native d_ino will do */ + if (!rdd->is_upper) + return false; + + /* + * Recalc d_ino for '.' and for all entries if dir is impure (contains + * copied up entries) + */ + if ((p->name[0] == '.' && p->len == 1) || + ovl_test_flag(OVL_IMPURE, d_inode(rdd->dentry))) + return true; + + return false; +} + +static struct ovl_cache_entry *ovl_cache_entry_new(struct ovl_readdir_data *rdd, + const char *name, int len, + u64 ino, unsigned int d_type) +{ + struct ovl_cache_entry *p; + size_t size = offsetof(struct ovl_cache_entry, name[len + 1]); + + p = kmalloc(size, GFP_KERNEL); + if (!p) + return NULL; + + memcpy(p->name, name, len); + p->name[len] = '\0'; + p->len = len; + p->type = d_type; + p->real_ino = ino; + p->ino = ino; + /* Defer setting d_ino for upper entry to ovl_iterate() */ + if (ovl_calc_d_ino(rdd, p)) + p->ino = 0; + p->is_upper = rdd->is_upper; + p->is_whiteout = false; + + if (d_type == DT_CHR) { + p->next_maybe_whiteout = rdd->first_maybe_whiteout; + rdd->first_maybe_whiteout = p; + } + return p; +} + +static int ovl_cache_entry_add_rb(struct ovl_readdir_data *rdd, + const char *name, int len, u64 ino, + unsigned int d_type) +{ + struct rb_node **newp = &rdd->root->rb_node; + struct rb_node *parent = NULL; + struct ovl_cache_entry *p; + + if (ovl_cache_entry_find_link(name, len, &newp, &parent)) + return 0; + + p = ovl_cache_entry_new(rdd, name, len, ino, d_type); + if (p == NULL) { + rdd->err = -ENOMEM; + return -ENOMEM; + } + + list_add_tail(&p->l_node, rdd->list); + rb_link_node(&p->node, parent, newp); + rb_insert_color(&p->node, rdd->root); + + return 0; +} + +static int ovl_fill_lowest(struct ovl_readdir_data *rdd, + const char *name, int namelen, + loff_t offset, u64 ino, unsigned int d_type) +{ + struct ovl_cache_entry *p; + + p = ovl_cache_entry_find(rdd->root, name, namelen); + if (p) { + list_move_tail(&p->l_node, &rdd->middle); + } else { + p = ovl_cache_entry_new(rdd, name, namelen, ino, d_type); + if (p == NULL) + rdd->err = -ENOMEM; + else + list_add_tail(&p->l_node, &rdd->middle); + } + + return rdd->err; +} + +void ovl_cache_free(struct list_head *list) +{ + struct ovl_cache_entry *p; + struct ovl_cache_entry *n; + + list_for_each_entry_safe(p, n, list, l_node) + kfree(p); + + INIT_LIST_HEAD(list); +} + +void ovl_dir_cache_free(struct inode *inode) +{ + struct ovl_dir_cache *cache = ovl_dir_cache(inode); + + if (cache) { + ovl_cache_free(&cache->entries); + kfree(cache); + } +} + +static void ovl_cache_put(struct ovl_dir_file *od, struct dentry *dentry) +{ + struct ovl_dir_cache *cache = od->cache; + + WARN_ON(cache->refcount <= 0); + cache->refcount--; + if (!cache->refcount) { + if (ovl_dir_cache(d_inode(dentry)) == cache) + ovl_set_dir_cache(d_inode(dentry), NULL); + + ovl_cache_free(&cache->entries); + kfree(cache); + } +} + +static int ovl_fill_merge(struct dir_context *ctx, const char *name, + int namelen, loff_t offset, u64 ino, + unsigned int d_type) +{ + struct ovl_readdir_data *rdd = + container_of(ctx, struct ovl_readdir_data, ctx); + + rdd->count++; + if (!rdd->is_lowest) + return ovl_cache_entry_add_rb(rdd, name, namelen, ino, d_type); + else + return ovl_fill_lowest(rdd, name, namelen, offset, ino, d_type); +} + +static int ovl_check_whiteouts(struct dentry *dir, struct ovl_readdir_data *rdd) +{ + int err; + struct ovl_cache_entry *p; + struct dentry *dentry; + const struct cred *old_cred; + + old_cred = ovl_override_creds(rdd->dentry->d_sb); + + err = down_write_killable(&dir->d_inode->i_rwsem); + if (!err) { + while (rdd->first_maybe_whiteout) { + p = rdd->first_maybe_whiteout; + rdd->first_maybe_whiteout = p->next_maybe_whiteout; + dentry = lookup_one_len(p->name, dir, p->len); + if (!IS_ERR(dentry)) { + p->is_whiteout = ovl_is_whiteout(dentry); + dput(dentry); + } + } + inode_unlock(dir->d_inode); + } + revert_creds(old_cred); + + return err; +} + +static inline int ovl_dir_read(struct path *realpath, + struct ovl_readdir_data *rdd) +{ + struct file *realfile; + int err; + + realfile = ovl_path_open(realpath, O_RDONLY | O_LARGEFILE); + if (IS_ERR(realfile)) + return PTR_ERR(realfile); + + rdd->first_maybe_whiteout = NULL; + rdd->ctx.pos = 0; + do { + rdd->count = 0; + rdd->err = 0; + err = iterate_dir(realfile, &rdd->ctx); + if (err >= 0) + err = rdd->err; + } while (!err && rdd->count); + + if (!err && rdd->first_maybe_whiteout && rdd->dentry) + err = ovl_check_whiteouts(realpath->dentry, rdd); + + fput(realfile); + + return err; +} + +static void ovl_dir_reset(struct file *file) +{ + struct ovl_dir_file *od = file->private_data; + struct ovl_dir_cache *cache = od->cache; + struct dentry *dentry = file->f_path.dentry; + bool is_real; + + if (cache && ovl_dentry_version_get(dentry) != cache->version) { + ovl_cache_put(od, dentry); + od->cache = NULL; + od->cursor = NULL; + } + is_real = ovl_dir_is_real(dentry); + if (od->is_real != is_real) { + /* is_real can only become false when dir is copied up */ + if (WARN_ON(is_real)) + return; + od->is_real = false; + } +} + +static int ovl_dir_read_merged(struct dentry *dentry, struct list_head *list, + struct rb_root *root) +{ + int err; + struct path realpath; + struct ovl_readdir_data rdd = { + .ctx.actor = ovl_fill_merge, + .dentry = dentry, + .list = list, + .root = root, + .is_lowest = false, + }; + int idx, next; + + for (idx = 0; idx != -1; idx = next) { + next = ovl_path_next(idx, dentry, &realpath); + rdd.is_upper = ovl_dentry_upper(dentry) == realpath.dentry; + + if (next != -1) { + err = ovl_dir_read(&realpath, &rdd); + if (err) + break; + } else { + /* + * Insert lowest layer entries before upper ones, this + * allows offsets to be reasonably constant + */ + list_add(&rdd.middle, rdd.list); + rdd.is_lowest = true; + err = ovl_dir_read(&realpath, &rdd); + list_del(&rdd.middle); + } + } + return err; +} + +static void ovl_seek_cursor(struct ovl_dir_file *od, loff_t pos) +{ + struct list_head *p; + loff_t off = 0; + + list_for_each(p, &od->cache->entries) { + if (off >= pos) + break; + off++; + } + /* Cursor is safe since the cache is stable */ + od->cursor = p; +} + +static struct ovl_dir_cache *ovl_cache_get(struct dentry *dentry) +{ + int res; + struct ovl_dir_cache *cache; + + cache = ovl_dir_cache(d_inode(dentry)); + if (cache && ovl_dentry_version_get(dentry) == cache->version) { + WARN_ON(!cache->refcount); + cache->refcount++; + return cache; + } + ovl_set_dir_cache(d_inode(dentry), NULL); + + cache = kzalloc(sizeof(struct ovl_dir_cache), GFP_KERNEL); + if (!cache) + return ERR_PTR(-ENOMEM); + + cache->refcount = 1; + INIT_LIST_HEAD(&cache->entries); + cache->root = RB_ROOT; + + res = ovl_dir_read_merged(dentry, &cache->entries, &cache->root); + if (res) { + ovl_cache_free(&cache->entries); + kfree(cache); + return ERR_PTR(res); + } + + cache->version = ovl_dentry_version_get(dentry); + ovl_set_dir_cache(d_inode(dentry), cache); + + return cache; +} + +/* Map inode number to lower fs unique range */ +static u64 ovl_remap_lower_ino(u64 ino, int xinobits, int fsid, + const char *name, int namelen, bool warn) +{ + unsigned int xinoshift = 64 - xinobits; + + if (unlikely(ino >> xinoshift)) { + if (warn) { + pr_warn_ratelimited("d_ino too big (%.*s, ino=%llu, xinobits=%d)\n", + namelen, name, ino, xinobits); + } + return ino; + } + + /* + * The lowest xinobit is reserved for mapping the non-peresistent inode + * numbers range, but this range is only exposed via st_ino, not here. + */ + return ino | ((u64)fsid) << (xinoshift + 1); +} + +/* + * Set d_ino for upper entries. Non-upper entries should always report + * the uppermost real inode ino and should not call this function. + * + * When not all layer are on same fs, report real ino also for upper. + * + * When all layers are on the same fs, and upper has a reference to + * copy up origin, call vfs_getattr() on the overlay entry to make + * sure that d_ino will be consistent with st_ino from stat(2). + */ +static int ovl_cache_update_ino(struct path *path, struct ovl_cache_entry *p) + +{ + struct dentry *dir = path->dentry; + struct dentry *this = NULL; + enum ovl_path_type type; + u64 ino = p->real_ino; + int xinobits = ovl_xino_bits(dir->d_sb); + int err = 0; + + if (!ovl_same_dev(dir->d_sb)) + goto out; + + if (p->name[0] == '.') { + if (p->len == 1) { + this = dget(dir); + goto get; + } + if (p->len == 2 && p->name[1] == '.') { + /* we shall not be moved */ + this = dget(dir->d_parent); + goto get; + } + } + this = lookup_one_len(p->name, dir, p->len); + if (IS_ERR_OR_NULL(this) || !this->d_inode) { + if (IS_ERR(this)) { + err = PTR_ERR(this); + this = NULL; + goto fail; + } + goto out; + } + +get: + type = ovl_path_type(this); + if (OVL_TYPE_ORIGIN(type)) { + struct kstat stat; + struct path statpath = *path; + + statpath.dentry = this; + err = vfs_getattr(&statpath, &stat, STATX_INO, 0); + if (err) + goto fail; + + /* + * Directory inode is always on overlay st_dev. + * Non-dir with ovl_same_dev() could be on pseudo st_dev in case + * of xino bits overflow. + */ + WARN_ON_ONCE(S_ISDIR(stat.mode) && + dir->d_sb->s_dev != stat.dev); + ino = stat.ino; + } else if (xinobits && !OVL_TYPE_UPPER(type)) { + ino = ovl_remap_lower_ino(ino, xinobits, + ovl_layer_lower(this)->fsid, + p->name, p->len, + ovl_xino_warn(dir->d_sb)); + } + +out: + p->ino = ino; + dput(this); + return err; + +fail: + pr_warn_ratelimited("failed to look up (%s) for ino (%i)\n", + p->name, err); + goto out; +} + +static int ovl_fill_plain(struct dir_context *ctx, const char *name, + int namelen, loff_t offset, u64 ino, + unsigned int d_type) +{ + struct ovl_cache_entry *p; + struct ovl_readdir_data *rdd = + container_of(ctx, struct ovl_readdir_data, ctx); + + rdd->count++; + p = ovl_cache_entry_new(rdd, name, namelen, ino, d_type); + if (p == NULL) { + rdd->err = -ENOMEM; + return -ENOMEM; + } + list_add_tail(&p->l_node, rdd->list); + + return 0; +} + +static int ovl_dir_read_impure(struct path *path, struct list_head *list, + struct rb_root *root) +{ + int err; + struct path realpath; + struct ovl_cache_entry *p, *n; + struct ovl_readdir_data rdd = { + .ctx.actor = ovl_fill_plain, + .list = list, + .root = root, + }; + + INIT_LIST_HEAD(list); + *root = RB_ROOT; + ovl_path_upper(path->dentry, &realpath); + + err = ovl_dir_read(&realpath, &rdd); + if (err) + return err; + + list_for_each_entry_safe(p, n, list, l_node) { + if (strcmp(p->name, ".") != 0 && + strcmp(p->name, "..") != 0) { + err = ovl_cache_update_ino(path, p); + if (err) + return err; + } + if (p->ino == p->real_ino) { + list_del(&p->l_node); + kfree(p); + } else { + struct rb_node **newp = &root->rb_node; + struct rb_node *parent = NULL; + + if (WARN_ON(ovl_cache_entry_find_link(p->name, p->len, + &newp, &parent))) + return -EIO; + + rb_link_node(&p->node, parent, newp); + rb_insert_color(&p->node, root); + } + } + return 0; +} + +static struct ovl_dir_cache *ovl_cache_get_impure(struct path *path) +{ + int res; + struct dentry *dentry = path->dentry; + struct ovl_fs *ofs = OVL_FS(dentry->d_sb); + struct ovl_dir_cache *cache; + + cache = ovl_dir_cache(d_inode(dentry)); + if (cache && ovl_dentry_version_get(dentry) == cache->version) + return cache; + + /* Impure cache is not refcounted, free it here */ + ovl_dir_cache_free(d_inode(dentry)); + ovl_set_dir_cache(d_inode(dentry), NULL); + + cache = kzalloc(sizeof(struct ovl_dir_cache), GFP_KERNEL); + if (!cache) + return ERR_PTR(-ENOMEM); + + res = ovl_dir_read_impure(path, &cache->entries, &cache->root); + if (res) { + ovl_cache_free(&cache->entries); + kfree(cache); + return ERR_PTR(res); + } + if (list_empty(&cache->entries)) { + /* + * A good opportunity to get rid of an unneeded "impure" flag. + * Removing the "impure" xattr is best effort. + */ + if (!ovl_want_write(dentry)) { + ovl_do_removexattr(ofs, ovl_dentry_upper(dentry), + OVL_XATTR_IMPURE); + ovl_drop_write(dentry); + } + ovl_clear_flag(OVL_IMPURE, d_inode(dentry)); + kfree(cache); + return NULL; + } + + cache->version = ovl_dentry_version_get(dentry); + ovl_set_dir_cache(d_inode(dentry), cache); + + return cache; +} + +struct ovl_readdir_translate { + struct dir_context *orig_ctx; + struct ovl_dir_cache *cache; + struct dir_context ctx; + u64 parent_ino; + int fsid; + int xinobits; + bool xinowarn; +}; + +static int ovl_fill_real(struct dir_context *ctx, const char *name, + int namelen, loff_t offset, u64 ino, + unsigned int d_type) +{ + struct ovl_readdir_translate *rdt = + container_of(ctx, struct ovl_readdir_translate, ctx); + struct dir_context *orig_ctx = rdt->orig_ctx; + + if (rdt->parent_ino && strcmp(name, "..") == 0) { + ino = rdt->parent_ino; + } else if (rdt->cache) { + struct ovl_cache_entry *p; + + p = ovl_cache_entry_find(&rdt->cache->root, name, namelen); + if (p) + ino = p->ino; + } else if (rdt->xinobits) { + ino = ovl_remap_lower_ino(ino, rdt->xinobits, rdt->fsid, + name, namelen, rdt->xinowarn); + } + + return orig_ctx->actor(orig_ctx, name, namelen, offset, ino, d_type); +} + +static bool ovl_is_impure_dir(struct file *file) +{ + struct ovl_dir_file *od = file->private_data; + struct inode *dir = d_inode(file->f_path.dentry); + + /* + * Only upper dir can be impure, but if we are in the middle of + * iterating a lower real dir, dir could be copied up and marked + * impure. We only want the impure cache if we started iterating + * a real upper dir to begin with. + */ + return od->is_upper && ovl_test_flag(OVL_IMPURE, dir); + +} + +static int ovl_iterate_real(struct file *file, struct dir_context *ctx) +{ + int err; + struct ovl_dir_file *od = file->private_data; + struct dentry *dir = file->f_path.dentry; + const struct ovl_layer *lower_layer = ovl_layer_lower(dir); + struct ovl_readdir_translate rdt = { + .ctx.actor = ovl_fill_real, + .orig_ctx = ctx, + .xinobits = ovl_xino_bits(dir->d_sb), + .xinowarn = ovl_xino_warn(dir->d_sb), + }; + + if (rdt.xinobits && lower_layer) + rdt.fsid = lower_layer->fsid; + + if (OVL_TYPE_MERGE(ovl_path_type(dir->d_parent))) { + struct kstat stat; + struct path statpath = file->f_path; + + statpath.dentry = dir->d_parent; + err = vfs_getattr(&statpath, &stat, STATX_INO, 0); + if (err) + return err; + + WARN_ON_ONCE(dir->d_sb->s_dev != stat.dev); + rdt.parent_ino = stat.ino; + } + + if (ovl_is_impure_dir(file)) { + rdt.cache = ovl_cache_get_impure(&file->f_path); + if (IS_ERR(rdt.cache)) + return PTR_ERR(rdt.cache); + } + + err = iterate_dir(od->realfile, &rdt.ctx); + ctx->pos = rdt.ctx.pos; + + return err; +} + + +static int ovl_iterate(struct file *file, struct dir_context *ctx) +{ + struct ovl_dir_file *od = file->private_data; + struct dentry *dentry = file->f_path.dentry; + struct ovl_cache_entry *p; + const struct cred *old_cred; + int err; + + old_cred = ovl_override_creds(dentry->d_sb); + if (!ctx->pos) + ovl_dir_reset(file); + + if (od->is_real) { + /* + * If parent is merge, then need to adjust d_ino for '..', if + * dir is impure then need to adjust d_ino for copied up + * entries. + */ + if (ovl_xino_bits(dentry->d_sb) || + (ovl_same_fs(dentry->d_sb) && + (ovl_is_impure_dir(file) || + OVL_TYPE_MERGE(ovl_path_type(dentry->d_parent))))) { + err = ovl_iterate_real(file, ctx); + } else { + err = iterate_dir(od->realfile, ctx); + } + goto out; + } + + if (!od->cache) { + struct ovl_dir_cache *cache; + + cache = ovl_cache_get(dentry); + err = PTR_ERR(cache); + if (IS_ERR(cache)) + goto out; + + od->cache = cache; + ovl_seek_cursor(od, ctx->pos); + } + + while (od->cursor != &od->cache->entries) { + p = list_entry(od->cursor, struct ovl_cache_entry, l_node); + if (!p->is_whiteout) { + if (!p->ino) { + err = ovl_cache_update_ino(&file->f_path, p); + if (err) + goto out; + } + if (!dir_emit(ctx, p->name, p->len, p->ino, p->type)) + break; + } + od->cursor = p->l_node.next; + ctx->pos++; + } + err = 0; +out: + revert_creds(old_cred); + return err; +} + +static loff_t ovl_dir_llseek(struct file *file, loff_t offset, int origin) +{ + loff_t res; + struct ovl_dir_file *od = file->private_data; + + inode_lock(file_inode(file)); + if (!file->f_pos) + ovl_dir_reset(file); + + if (od->is_real) { + res = vfs_llseek(od->realfile, offset, origin); + file->f_pos = od->realfile->f_pos; + } else { + res = -EINVAL; + + switch (origin) { + case SEEK_CUR: + offset += file->f_pos; + break; + case SEEK_SET: + break; + default: + goto out_unlock; + } + if (offset < 0) + goto out_unlock; + + if (offset != file->f_pos) { + file->f_pos = offset; + if (od->cache) + ovl_seek_cursor(od, offset); + } + res = offset; + } +out_unlock: + inode_unlock(file_inode(file)); + + return res; +} + +static struct file *ovl_dir_open_realfile(const struct file *file, + struct path *realpath) +{ + struct file *res; + const struct cred *old_cred; + + old_cred = ovl_override_creds(file_inode(file)->i_sb); + res = ovl_path_open(realpath, O_RDONLY | (file->f_flags & O_LARGEFILE)); + revert_creds(old_cred); + + return res; +} + +/* + * Like ovl_real_fdget(), returns upperfile if dir was copied up since open. + * Unlike ovl_real_fdget(), this caches upperfile in file->private_data. + * + * TODO: use same abstract type for file->private_data of dir and file so + * upperfile could also be cached for files as well. + */ +struct file *ovl_dir_real_file(const struct file *file, bool want_upper) +{ + + struct ovl_dir_file *od = file->private_data; + struct dentry *dentry = file->f_path.dentry; + struct file *old, *realfile = od->realfile; + + if (!OVL_TYPE_UPPER(ovl_path_type(dentry))) + return want_upper ? NULL : realfile; + + /* + * Need to check if we started out being a lower dir, but got copied up + */ + if (!od->is_upper) { + realfile = READ_ONCE(od->upperfile); + if (!realfile) { + struct path upperpath; + + ovl_path_upper(dentry, &upperpath); + realfile = ovl_dir_open_realfile(file, &upperpath); + if (IS_ERR(realfile)) + return realfile; + + old = cmpxchg_release(&od->upperfile, NULL, realfile); + if (old) { + fput(realfile); + realfile = old; + } + } + } + + return realfile; +} + +static int ovl_dir_fsync(struct file *file, loff_t start, loff_t end, + int datasync) +{ + struct file *realfile; + int err; + + err = ovl_sync_status(OVL_FS(file->f_path.dentry->d_sb)); + if (err <= 0) + return err; + + realfile = ovl_dir_real_file(file, true); + err = PTR_ERR_OR_ZERO(realfile); + + /* Nothing to sync for lower */ + if (!realfile || err) + return err; + + return vfs_fsync_range(realfile, start, end, datasync); +} + +static int ovl_dir_release(struct inode *inode, struct file *file) +{ + struct ovl_dir_file *od = file->private_data; + + if (od->cache) { + inode_lock(inode); + ovl_cache_put(od, file->f_path.dentry); + inode_unlock(inode); + } + fput(od->realfile); + if (od->upperfile) + fput(od->upperfile); + kfree(od); + + return 0; +} + +static int ovl_dir_open(struct inode *inode, struct file *file) +{ + struct path realpath; + struct file *realfile; + struct ovl_dir_file *od; + enum ovl_path_type type; + + od = kzalloc(sizeof(struct ovl_dir_file), GFP_KERNEL); + if (!od) + return -ENOMEM; + + type = ovl_path_real(file->f_path.dentry, &realpath); + realfile = ovl_dir_open_realfile(file, &realpath); + if (IS_ERR(realfile)) { + kfree(od); + return PTR_ERR(realfile); + } + od->realfile = realfile; + od->is_real = ovl_dir_is_real(file->f_path.dentry); + od->is_upper = OVL_TYPE_UPPER(type); + file->private_data = od; + + return 0; +} + +const struct file_operations ovl_dir_operations = { + .read = generic_read_dir, + .open = ovl_dir_open, + .iterate = ovl_iterate, + .llseek = ovl_dir_llseek, + .fsync = ovl_dir_fsync, + .release = ovl_dir_release, + .unlocked_ioctl = ovl_ioctl, +#ifdef CONFIG_COMPAT + .compat_ioctl = ovl_compat_ioctl, +#endif +}; + +int ovl_check_empty_dir(struct dentry *dentry, struct list_head *list) +{ + int err; + struct ovl_cache_entry *p, *n; + struct rb_root root = RB_ROOT; + const struct cred *old_cred; + + old_cred = ovl_override_creds(dentry->d_sb); + err = ovl_dir_read_merged(dentry, list, &root); + revert_creds(old_cred); + if (err) + return err; + + err = 0; + + list_for_each_entry_safe(p, n, list, l_node) { + /* + * Select whiteouts in upperdir, they should + * be cleared when deleting this directory. + */ + if (p->is_whiteout) { + if (p->is_upper) + continue; + goto del_entry; + } + + if (p->name[0] == '.') { + if (p->len == 1) + goto del_entry; + if (p->len == 2 && p->name[1] == '.') + goto del_entry; + } + err = -ENOTEMPTY; + break; + +del_entry: + list_del(&p->l_node); + kfree(p); + } + + return err; +} + +void ovl_cleanup_whiteouts(struct dentry *upper, struct list_head *list) +{ + struct ovl_cache_entry *p; + + inode_lock_nested(upper->d_inode, I_MUTEX_CHILD); + list_for_each_entry(p, list, l_node) { + struct dentry *dentry; + + if (WARN_ON(!p->is_whiteout || !p->is_upper)) + continue; + + dentry = lookup_one_len(p->name, upper, p->len); + if (IS_ERR(dentry)) { + pr_err("lookup '%s/%.*s' failed (%i)\n", + upper->d_name.name, p->len, p->name, + (int) PTR_ERR(dentry)); + continue; + } + if (dentry->d_inode) + ovl_cleanup(upper->d_inode, dentry); + dput(dentry); + } + inode_unlock(upper->d_inode); +} + +static int ovl_check_d_type(struct dir_context *ctx, const char *name, + int namelen, loff_t offset, u64 ino, + unsigned int d_type) +{ + struct ovl_readdir_data *rdd = + container_of(ctx, struct ovl_readdir_data, ctx); + + /* Even if d_type is not supported, DT_DIR is returned for . and .. */ + if (!strncmp(name, ".", namelen) || !strncmp(name, "..", namelen)) + return 0; + + if (d_type != DT_UNKNOWN) + rdd->d_type_supported = true; + + return 0; +} + +/* + * Returns 1 if d_type is supported, 0 not supported/unknown. Negative values + * if error is encountered. + */ +int ovl_check_d_type_supported(struct path *realpath) +{ + int err; + struct ovl_readdir_data rdd = { + .ctx.actor = ovl_check_d_type, + .d_type_supported = false, + }; + + err = ovl_dir_read(realpath, &rdd); + if (err) + return err; + + return rdd.d_type_supported; +} + +#define OVL_INCOMPATDIR_NAME "incompat" + +static int ovl_workdir_cleanup_recurse(struct path *path, int level) +{ + int err; + struct inode *dir = path->dentry->d_inode; + LIST_HEAD(list); + struct rb_root root = RB_ROOT; + struct ovl_cache_entry *p; + struct ovl_readdir_data rdd = { + .ctx.actor = ovl_fill_merge, + .dentry = NULL, + .list = &list, + .root = &root, + .is_lowest = false, + }; + bool incompat = false; + + /* + * The "work/incompat" directory is treated specially - if it is not + * empty, instead of printing a generic error and mounting read-only, + * we will error about incompat features and fail the mount. + * + * When called from ovl_indexdir_cleanup(), path->dentry->d_name.name + * starts with '#'. + */ + if (level == 2 && + !strcmp(path->dentry->d_name.name, OVL_INCOMPATDIR_NAME)) + incompat = true; + + err = ovl_dir_read(path, &rdd); + if (err) + goto out; + + inode_lock_nested(dir, I_MUTEX_PARENT); + list_for_each_entry(p, &list, l_node) { + struct dentry *dentry; + + if (p->name[0] == '.') { + if (p->len == 1) + continue; + if (p->len == 2 && p->name[1] == '.') + continue; + } else if (incompat) { + pr_err("overlay with incompat feature '%s' cannot be mounted\n", + p->name); + err = -EINVAL; + break; + } + dentry = lookup_one_len(p->name, path->dentry, p->len); + if (IS_ERR(dentry)) + continue; + if (dentry->d_inode) + err = ovl_workdir_cleanup(dir, path->mnt, dentry, level); + dput(dentry); + if (err) + break; + } + inode_unlock(dir); +out: + ovl_cache_free(&list); + return err; +} + +int ovl_workdir_cleanup(struct inode *dir, struct vfsmount *mnt, + struct dentry *dentry, int level) +{ + int err; + + if (!d_is_dir(dentry) || level > 1) { + return ovl_cleanup(dir, dentry); + } + + err = ovl_do_rmdir(dir, dentry); + if (err) { + struct path path = { .mnt = mnt, .dentry = dentry }; + + inode_unlock(dir); + err = ovl_workdir_cleanup_recurse(&path, level + 1); + inode_lock_nested(dir, I_MUTEX_PARENT); + if (!err) + err = ovl_cleanup(dir, dentry); + } + + return err; +} + +int ovl_indexdir_cleanup(struct ovl_fs *ofs) +{ + int err; + struct dentry *indexdir = ofs->indexdir; + struct dentry *index = NULL; + struct inode *dir = indexdir->d_inode; + struct path path = { .mnt = ovl_upper_mnt(ofs), .dentry = indexdir }; + LIST_HEAD(list); + struct rb_root root = RB_ROOT; + struct ovl_cache_entry *p; + struct ovl_readdir_data rdd = { + .ctx.actor = ovl_fill_merge, + .dentry = NULL, + .list = &list, + .root = &root, + .is_lowest = false, + }; + + err = ovl_dir_read(&path, &rdd); + if (err) + goto out; + + inode_lock_nested(dir, I_MUTEX_PARENT); + list_for_each_entry(p, &list, l_node) { + if (p->name[0] == '.') { + if (p->len == 1) + continue; + if (p->len == 2 && p->name[1] == '.') + continue; + } + index = lookup_one_len(p->name, indexdir, p->len); + if (IS_ERR(index)) { + err = PTR_ERR(index); + index = NULL; + break; + } + /* Cleanup leftover from index create/cleanup attempt */ + if (index->d_name.name[0] == '#') { + err = ovl_workdir_cleanup(dir, path.mnt, index, 1); + if (err) + break; + goto next; + } + err = ovl_verify_index(ofs, index); + if (!err) { + goto next; + } else if (err == -ESTALE) { + /* Cleanup stale index entries */ + err = ovl_cleanup(dir, index); + } else if (err != -ENOENT) { + /* + * Abort mount to avoid corrupting the index if + * an incompatible index entry was found or on out + * of memory. + */ + break; + } else if (ofs->config.nfs_export) { + /* + * Whiteout orphan index to block future open by + * handle after overlay nlink dropped to zero. + */ + err = ovl_cleanup_and_whiteout(ofs, dir, index); + } else { + /* Cleanup orphan index entries */ + err = ovl_cleanup(dir, index); + } + + if (err) + break; + +next: + dput(index); + index = NULL; + } + dput(index); + inode_unlock(dir); +out: + ovl_cache_free(&list); + if (err) + pr_err("failed index dir cleanup (%i)\n", err); + return err; +} |