}
EXPORT_SYMBOL(path_put);
+/**
+ * path_connected - Verify that a path->dentry is below path->mnt.mnt_root
+ * @path: nameidate to verify
+ *
+ * Rename can sometimes move a file or directory outside of a bind
+ * mount, path_connected allows those cases to be detected.
+ */
+static bool path_connected(const struct path *path)
+{
+ struct vfsmount *mnt = path->mnt;
+
+ /* Only bind mounts can have disconnected paths */
+ if (mnt->mnt_root == mnt->mnt_sb->s_root)
+ return true;
+
+ return is_subdir(path->dentry, mnt->mnt_root);
+}
+
/*
* Path walking has 2 modes, rcu-walk and ref-walk (see
* Documentation/filesystems/path-lookup.txt). In situations when we can't
static __always_inline void set_root(struct nameidata *nd)
{
- if (!nd->root.mnt)
- get_fs_root(current->fs, &nd->root);
+ get_fs_root(current->fs, &nd->root);
}
static int link_path_walk(const char *, struct nameidata *);
-static __always_inline void set_root_rcu(struct nameidata *nd)
+static __always_inline unsigned set_root_rcu(struct nameidata *nd)
{
- if (!nd->root.mnt) {
- struct fs_struct *fs = current->fs;
- unsigned seq;
+ struct fs_struct *fs = current->fs;
+ unsigned seq, res;
- do {
- seq = read_seqcount_begin(&fs->seq);
- nd->root = fs->root;
- nd->seq = __read_seqcount_begin(&nd->root.dentry->d_seq);
- } while (read_seqcount_retry(&fs->seq, seq));
- }
+ do {
+ seq = read_seqcount_begin(&fs->seq);
+ nd->root = fs->root;
+ res = __read_seqcount_begin(&nd->root.dentry->d_seq);
+ } while (read_seqcount_retry(&fs->seq, seq));
+ return res;
}
static __always_inline int __vfs_follow_link(struct nameidata *nd, const char *link)
goto fail;
if (*link == '/') {
- set_root(nd);
+ if (!nd->root.mnt)
+ set_root(nd);
path_put(&nd->path);
nd->path = nd->root;
path_get(&nd->root);
mntput(path->mnt);
if (ret == -EISDIR)
ret = 0;
- return ret;
+ return ret < 0 ? ret : need_mntput;
}
int follow_down_one(struct path *path)
break;
path->mnt = mounted;
path->dentry = mounted->mnt_root;
+ nd->flags |= LOOKUP_JUMPED;
nd->seq = read_seqcount_begin(&path->dentry->d_seq);
/*
* Update the inode too. We don't need to re-check the
return true;
}
-static void follow_mount_rcu(struct nameidata *nd)
-{
- while (d_mountpoint(nd->path.dentry)) {
- struct vfsmount *mounted;
- mounted = __lookup_mnt(nd->path.mnt, nd->path.dentry, 1);
- if (!mounted)
- break;
- nd->path.mnt = mounted;
- nd->path.dentry = mounted->mnt_root;
- nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq);
- }
-}
-
static int follow_dotdot_rcu(struct nameidata *nd)
{
- set_root_rcu(nd);
+ struct inode *inode = nd->inode;
+ if (!nd->root.mnt)
+ set_root_rcu(nd);
while (1) {
if (nd->path.dentry == nd->root.dentry &&
struct dentry *parent = old->d_parent;
unsigned seq;
+ inode = parent->d_inode;
seq = read_seqcount_begin(&parent->d_seq);
if (read_seqcount_retry(&old->d_seq, nd->seq))
goto failed;
nd->path.dentry = parent;
nd->seq = seq;
+ if (unlikely(!path_connected(&nd->path)))
+ goto failed;
break;
}
if (!follow_up_rcu(&nd->path))
break;
+ inode = nd->path.dentry->d_inode;
nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq);
}
- follow_mount_rcu(nd);
- nd->inode = nd->path.dentry->d_inode;
+ while (d_mountpoint(nd->path.dentry)) {
+ struct vfsmount *mounted;
+ mounted = __lookup_mnt(nd->path.mnt, nd->path.dentry, 1);
+ if (!mounted)
+ break;
+ nd->path.mnt = mounted;
+ nd->path.dentry = mounted->mnt_root;
+ inode = nd->path.dentry->d_inode;
+ nd->seq = read_seqcount_begin(&nd->path.dentry->d_seq);
+ }
+ nd->inode = inode;
return 0;
failed:
}
}
-static void follow_dotdot(struct nameidata *nd)
+static int follow_dotdot(struct nameidata *nd)
{
- set_root(nd);
+ if (!nd->root.mnt)
+ set_root(nd);
while(1) {
struct dentry *old = nd->path.dentry;
/* rare case of legitimate dget_parent()... */
nd->path.dentry = dget_parent(nd->path.dentry);
dput(old);
+ if (unlikely(!path_connected(&nd->path))) {
+ path_put(&nd->path);
+ return -ENOENT;
+ }
break;
}
if (!follow_up(&nd->path))
}
follow_mount(&nd->path);
nd->inode = nd->path.dentry->d_inode;
+ return 0;
}
/*
struct dentry *old;
/* Don't create child dentry for a dead directory. */
- if (unlikely(IS_DEADDIR(inode)))
+ if (unlikely(IS_DEADDIR(inode))) {
+ dput(dentry);
return ERR_PTR(-ENOENT);
+ }
old = inode->i_op->lookup(inode, dentry, nd);
if (unlikely(old)) {
path_put_conditional(path, nd);
return err;
}
+ if (err)
+ nd->flags |= LOOKUP_JUMPED;
*inode = path->dentry->d_inode;
return 0;
}
if (follow_dotdot_rcu(nd))
return -ECHILD;
} else
- follow_dotdot(nd);
+ return follow_dotdot(nd);
}
return 0;
}
if (flags & LOOKUP_RCU) {
br_read_lock(vfsmount_lock);
rcu_read_lock();
- set_root_rcu(nd);
+ nd->seq = set_root_rcu(nd);
} else {
set_root(nd);
path_get(&nd->root);
}
nd->inode = nd->path.dentry->d_inode;
- return 0;
+ if (!(flags & LOOKUP_RCU))
+ return 0;
+ if (likely(!read_seqcount_retry(&nd->path.dentry->d_seq, nd->seq)))
+ return 0;
+ if (!(nd->flags & LOOKUP_ROOT))
+ nd->root.mnt = NULL;
+ rcu_read_unlock();
+ br_read_unlock(vfsmount_lock);
+ return -ECHILD;
fput_fail:
fput_light(file, fput_needed);
/* sayonara */
error = complete_walk(nd);
if (error)
- return ERR_PTR(-ECHILD);
+ return ERR_PTR(error);
error = -ENOTDIR;
if (nd->flags & LOOKUP_DIRECTORY) {
}
/* create side of things */
+ /*
+ * This will *only* deal with leaving RCU mode - LOOKUP_JUMPED has been
+ * cleared when we got to the last component we are about to look up
+ */
error = complete_walk(nd);
if (error)
return ERR_PTR(error);
if (error < 0)
goto exit_dput;
+ if (error)
+ nd->flags |= LOOKUP_JUMPED;
+
error = -ENOENT;
if (!path->dentry->d_inode)
goto exit_dput;
path_to_nameidata(path, nd);
nd->inode = path->dentry->d_inode;
+ /* Why this, you ask? _Now_ we might have grown LOOKUP_JUMPED... */
+ error = complete_walk(nd);
+ if (error)
+ return ERR_PTR(error);
error = -EISDIR;
if (S_ISDIR(nd->inode->i_mode))
goto exit;