From b70a80e7a133a0c86f2fa078e7c144597c516415 Mon Sep 17 00:00:00 2001 From: Miklos Szeredi Date: Tue, 1 Oct 2013 16:44:54 +0200 Subject: vfs: introduce d_instantiate_no_diralias() ...which just returns -EBUSY if a directory alias would be created. This is to be used by fuse mkdir to make sure that a buggy or malicious userspace filesystem doesn't do anything nasty. Previously fuse used a private mutex for this purpose, which can now go away. Signed-off-by: Miklos Szeredi --- fs/fuse/dir.c | 40 +++++----------------------------------- 1 file changed, 5 insertions(+), 35 deletions(-) (limited to 'fs/fuse/dir.c') diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c index b7989f2ab4c4..c3eb2c46c8f1 100644 --- a/fs/fuse/dir.c +++ b/fs/fuse/dir.c @@ -342,24 +342,6 @@ int fuse_lookup_name(struct super_block *sb, u64 nodeid, struct qstr *name, return err; } -static struct dentry *fuse_materialise_dentry(struct dentry *dentry, - struct inode *inode) -{ - struct dentry *newent; - - if (inode && S_ISDIR(inode->i_mode)) { - struct fuse_conn *fc = get_fuse_conn(inode); - - mutex_lock(&fc->inst_mutex); - newent = d_materialise_unique(dentry, inode); - mutex_unlock(&fc->inst_mutex); - } else { - newent = d_materialise_unique(dentry, inode); - } - - return newent; -} - static struct dentry *fuse_lookup(struct inode *dir, struct dentry *entry, unsigned int flags) { @@ -382,7 +364,7 @@ static struct dentry *fuse_lookup(struct inode *dir, struct dentry *entry, if (inode && get_node_id(inode) == FUSE_ROOT_ID) goto out_iput; - newent = fuse_materialise_dentry(entry, inode); + newent = d_materialise_unique(entry, inode); err = PTR_ERR(newent); if (IS_ERR(newent)) goto out_err; @@ -601,21 +583,9 @@ static int create_new_entry(struct fuse_conn *fc, struct fuse_req *req, } kfree(forget); - if (S_ISDIR(inode->i_mode)) { - struct dentry *alias; - mutex_lock(&fc->inst_mutex); - alias = d_find_alias(inode); - if (alias) { - /* New directory must have moved since mkdir */ - mutex_unlock(&fc->inst_mutex); - dput(alias); - iput(inode); - return -EBUSY; - } - d_instantiate(entry, inode); - mutex_unlock(&fc->inst_mutex); - } else - d_instantiate(entry, inode); + err = d_instantiate_no_diralias(entry, inode); + if (err) + return err; fuse_change_entry_timeout(entry, &outarg); fuse_invalidate_attr(dir); @@ -1284,7 +1254,7 @@ static int fuse_direntplus_link(struct file *file, if (!inode) goto out; - alias = fuse_materialise_dentry(dentry, inode); + alias = d_materialise_unique(dentry, inode); err = PTR_ERR(alias); if (IS_ERR(alias)) goto out; -- cgit v1.2.1