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authorMiklos Szeredi <mszeredi@suse.cz>2013-10-01 18:44:54 +0400
committerAl Viro <viro@zeniv.linux.org.uk>2013-10-25 07:41:37 +0400
commitb70a80e7a133a0c86f2fa078e7c144597c516415 (patch)
tree378dbeeafc1510fb326eda10e1f48085be098f6c /fs/fuse/dir.c
parent94e92a6e772e009e27083a7f42d49a179e5f668c (diff)
downloadlinux-b70a80e7a133a0c86f2fa078e7c144597c516415.tar.xz
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 <mszeredi@suse.cz>
Diffstat (limited to 'fs/fuse/dir.c')
-rw-r--r--fs/fuse/dir.c40
1 files changed, 5 insertions, 35 deletions
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;