diff options
-rw-r--r-- | fs/overlayfs/readdir.c | 77 | ||||
-rw-r--r-- | fs/overlayfs/super.c | 113 |
2 files changed, 139 insertions, 51 deletions
diff --git a/fs/overlayfs/readdir.c b/fs/overlayfs/readdir.c index 907870e81a72..70e9af551600 100644 --- a/fs/overlayfs/readdir.c +++ b/fs/overlayfs/readdir.c @@ -23,6 +23,7 @@ struct ovl_cache_entry { u64 ino; struct list_head l_node; struct rb_node node; + struct ovl_cache_entry *next_maybe_whiteout; bool is_whiteout; char name[]; }; @@ -39,7 +40,7 @@ struct ovl_readdir_data { struct rb_root root; struct list_head *list; struct list_head middle; - struct dentry *dir; + struct ovl_cache_entry *first_maybe_whiteout; int count; int err; }; @@ -79,7 +80,7 @@ static struct ovl_cache_entry *ovl_cache_entry_find(struct rb_root *root, return NULL; } -static struct ovl_cache_entry *ovl_cache_entry_new(struct dentry *dir, +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) { @@ -98,29 +99,8 @@ static struct ovl_cache_entry *ovl_cache_entry_new(struct dentry *dir, p->is_whiteout = false; if (d_type == DT_CHR) { - struct dentry *dentry; - const struct cred *old_cred; - struct cred *override_cred; - - override_cred = prepare_creds(); - if (!override_cred) { - kfree(p); - return NULL; - } - - /* - * CAP_DAC_OVERRIDE for lookup - */ - cap_raise(override_cred->cap_effective, CAP_DAC_OVERRIDE); - old_cred = override_creds(override_cred); - - dentry = lookup_one_len(name, dir, len); - if (!IS_ERR(dentry)) { - p->is_whiteout = ovl_is_whiteout(dentry); - dput(dentry); - } - revert_creds(old_cred); - put_cred(override_cred); + p->next_maybe_whiteout = rdd->first_maybe_whiteout; + rdd->first_maybe_whiteout = p; } return p; } @@ -148,7 +128,7 @@ static int ovl_cache_entry_add_rb(struct ovl_readdir_data *rdd, return 0; } - p = ovl_cache_entry_new(rdd->dir, name, len, ino, d_type); + p = ovl_cache_entry_new(rdd, name, len, ino, d_type); if (p == NULL) return -ENOMEM; @@ -169,7 +149,7 @@ static int ovl_fill_lower(struct ovl_readdir_data *rdd, if (p) { list_move_tail(&p->l_node, &rdd->middle); } else { - p = ovl_cache_entry_new(rdd->dir, name, namelen, ino, d_type); + p = ovl_cache_entry_new(rdd, name, namelen, ino, d_type); if (p == NULL) rdd->err = -ENOMEM; else @@ -219,6 +199,43 @@ static int ovl_fill_merge(struct dir_context *ctx, const char *name, return ovl_fill_lower(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; + struct cred *override_cred; + + override_cred = prepare_creds(); + if (!override_cred) + return -ENOMEM; + + /* + * CAP_DAC_OVERRIDE for lookup + */ + cap_raise(override_cred->cap_effective, CAP_DAC_OVERRIDE); + old_cred = override_creds(override_cred); + + err = mutex_lock_killable(&dir->d_inode->i_mutex); + 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); + } + } + mutex_unlock(&dir->d_inode->i_mutex); + } + revert_creds(old_cred); + put_cred(override_cred); + + return err; +} + static inline int ovl_dir_read(struct path *realpath, struct ovl_readdir_data *rdd) { @@ -229,7 +246,7 @@ static inline int ovl_dir_read(struct path *realpath, if (IS_ERR(realfile)) return PTR_ERR(realfile); - rdd->dir = realpath->dentry; + rdd->first_maybe_whiteout = NULL; rdd->ctx.pos = 0; do { rdd->count = 0; @@ -238,6 +255,10 @@ static inline int ovl_dir_read(struct path *realpath, if (err >= 0) err = rdd->err; } while (!err && rdd->count); + + if (!err && rdd->first_maybe_whiteout) + err = ovl_check_whiteouts(realpath->dentry, rdd); + fput(realfile); return err; diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c index bf8537c7f455..8a08c582bc22 100644 --- a/fs/overlayfs/super.c +++ b/fs/overlayfs/super.c @@ -273,10 +273,57 @@ static void ovl_dentry_release(struct dentry *dentry) } } +static int ovl_dentry_revalidate(struct dentry *dentry, unsigned int flags) +{ + struct ovl_entry *oe = dentry->d_fsdata; + unsigned int i; + int ret = 1; + + for (i = 0; i < oe->numlower; i++) { + struct dentry *d = oe->lowerstack[i].dentry; + + if (d->d_flags & DCACHE_OP_REVALIDATE) { + ret = d->d_op->d_revalidate(d, flags); + if (ret < 0) + return ret; + if (!ret) { + if (!(flags & LOOKUP_RCU)) + d_invalidate(d); + return -ESTALE; + } + } + } + return 1; +} + +static int ovl_dentry_weak_revalidate(struct dentry *dentry, unsigned int flags) +{ + struct ovl_entry *oe = dentry->d_fsdata; + unsigned int i; + int ret = 1; + + for (i = 0; i < oe->numlower; i++) { + struct dentry *d = oe->lowerstack[i].dentry; + + if (d->d_flags & DCACHE_OP_WEAK_REVALIDATE) { + ret = d->d_op->d_weak_revalidate(d, flags); + if (ret <= 0) + break; + } + } + return ret; +} + static const struct dentry_operations ovl_dentry_operations = { .d_release = ovl_dentry_release, }; +static const struct dentry_operations ovl_reval_dentry_operations = { + .d_release = ovl_dentry_release, + .d_revalidate = ovl_dentry_revalidate, + .d_weak_revalidate = ovl_dentry_weak_revalidate, +}; + static struct ovl_entry *ovl_alloc_entry(unsigned int numlower) { size_t size = offsetof(struct ovl_entry, lowerstack[numlower]); @@ -288,6 +335,20 @@ static struct ovl_entry *ovl_alloc_entry(unsigned int numlower) return oe; } +static bool ovl_dentry_remote(struct dentry *dentry) +{ + return dentry->d_flags & + (DCACHE_OP_REVALIDATE | DCACHE_OP_WEAK_REVALIDATE); +} + +static bool ovl_dentry_weird(struct dentry *dentry) +{ + return dentry->d_flags & (DCACHE_NEED_AUTOMOUNT | + DCACHE_MANAGE_TRANSIT | + DCACHE_OP_HASH | + DCACHE_OP_COMPARE); +} + static inline struct dentry *ovl_lookup_real(struct dentry *dir, struct qstr *name) { @@ -303,6 +364,10 @@ static inline struct dentry *ovl_lookup_real(struct dentry *dir, } else if (!dentry->d_inode) { dput(dentry); dentry = NULL; + } else if (ovl_dentry_weird(dentry)) { + dput(dentry); + /* Don't support traversing automounts and other weirdness */ + dentry = ERR_PTR(-EREMOTE); } return dentry; } @@ -350,6 +415,11 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry, goto out; if (this) { + if (unlikely(ovl_dentry_remote(this))) { + dput(this); + err = -EREMOTE; + goto out; + } if (ovl_is_whiteout(this)) { dput(this); this = NULL; @@ -694,25 +764,6 @@ static void ovl_unescape(char *s) } } -static bool ovl_is_allowed_fs_type(struct dentry *root) -{ - const struct dentry_operations *dop = root->d_op; - - /* - * We don't support: - * - automount filesystems - * - filesystems with revalidate (FIXME for lower layer) - * - filesystems with case insensitive names - */ - if (dop && - (dop->d_manage || dop->d_automount || - dop->d_revalidate || dop->d_weak_revalidate || - dop->d_compare || dop->d_hash)) { - return false; - } - return true; -} - static int ovl_mount_dir_noesc(const char *name, struct path *path) { int err = -EINVAL; @@ -727,7 +778,7 @@ static int ovl_mount_dir_noesc(const char *name, struct path *path) goto out; } err = -EINVAL; - if (!ovl_is_allowed_fs_type(path->dentry)) { + if (ovl_dentry_weird(path->dentry)) { pr_err("overlayfs: filesystem on '%s' not supported\n", name); goto out_put; } @@ -751,13 +802,21 @@ static int ovl_mount_dir(const char *name, struct path *path) if (tmp) { ovl_unescape(tmp); err = ovl_mount_dir_noesc(tmp, path); + + if (!err) + if (ovl_dentry_remote(path->dentry)) { + pr_err("overlayfs: filesystem on '%s' not supported as upperdir\n", + tmp); + path_put(path); + err = -EINVAL; + } kfree(tmp); } return err; } static int ovl_lower_dir(const char *name, struct path *path, long *namelen, - int *stack_depth) + int *stack_depth, bool *remote) { int err; struct kstatfs statfs; @@ -774,6 +833,9 @@ static int ovl_lower_dir(const char *name, struct path *path, long *namelen, *namelen = max(*namelen, statfs.f_namelen); *stack_depth = max(*stack_depth, path->mnt->mnt_sb->s_stack_depth); + if (ovl_dentry_remote(path->dentry)) + *remote = true; + return 0; out_put: @@ -827,6 +889,7 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent) unsigned int numlower; unsigned int stacklen = 0; unsigned int i; + bool remote = false; int err; err = -ENOMEM; @@ -900,7 +963,8 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent) lower = lowertmp; for (numlower = 0; numlower < stacklen; numlower++) { err = ovl_lower_dir(lower, &stack[numlower], - &ufs->lower_namelen, &sb->s_stack_depth); + &ufs->lower_namelen, &sb->s_stack_depth, + &remote); if (err) goto out_put_lowerpath; @@ -958,7 +1022,10 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent) if (!ufs->upper_mnt) sb->s_flags |= MS_RDONLY; - sb->s_d_op = &ovl_dentry_operations; + if (remote) + sb->s_d_op = &ovl_reval_dentry_operations; + else + sb->s_d_op = &ovl_dentry_operations; err = -ENOMEM; oe = ovl_alloc_entry(numlower); |