Unverified Commit 1ead2213 authored by NeilBrown's avatar NeilBrown Committed by Christian Brauner
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smb/server: use end_removing_noperm for for target of smb2_create_link() 



Sometimes smb2_create_link() needs to remove the target before creating
the link.
It uses ksmbd_vfs_kern_locked(), and is the only user of that interface.

To match the new naming, that function is changed to
ksmbd_vfs_kern_start_removing(), and related functions or flags are also
renamed.

The lock actually happens in ksmbd_vfs_path_lookup() and that is changed
to use start_removing_noperm() - permission to perform lookup in the
parent was already checked in vfs_path_parent_lookup().

Signed-off-by: default avatarNeilBrown <neil@brown.name>
Link: https://patch.msgid.link/20251113002050.676694-8-neilb@ownmail.net


Signed-off-by: default avatarChristian Brauner <brauner@kernel.org>
parent c9ba789d

fs/smb/server/smb2pdu.c

+3 −3
Original line number Diff line number Diff line
@@ -6084,7 +6084,7 @@ static int smb2_create_link(struct ksmbd_work *work, 
	}



	ksmbd_debug(SMB, "target name is %s\n", target_name);

	rc = ksmbd_vfs_kern_path_locked(work, link_name, LOOKUP_NO_SYMLINKS,

	rc = ksmbd_vfs_kern_path_start_removing(work, link_name, LOOKUP_NO_SYMLINKS,

						&path, 0);

	if (rc) {

		if (rc != -ENOENT)
@@ -6103,7 +6103,7 @@ static int smb2_create_link(struct ksmbd_work *work, 
			ksmbd_debug(SMB, "link already exists\n");

			goto out;

		}

		ksmbd_vfs_kern_path_unlock(&path);

		ksmbd_vfs_kern_path_end_removing(&path);

	}

	rc = ksmbd_vfs_link(work, target_name, link_name);

	if (rc)

fs/smb/server/vfs.c

+12 −15
Original line number Diff line number Diff line
@@ -69,7 +69,7 @@ int ksmbd_vfs_lock_parent(struct dentry *parent, struct dentry *child) 


static int ksmbd_vfs_path_lookup(struct ksmbd_share_config *share_conf,

				 char *pathname, unsigned int flags,

				 struct path *path, bool do_lock)

				 struct path *path, bool for_remove)

{

	struct qstr last;

	struct filename *filename __free(putname) = NULL;
@@ -99,22 +99,20 @@ static int ksmbd_vfs_path_lookup(struct ksmbd_share_config *share_conf, 
		return -ENOENT;

	}



	if (do_lock) {

	if (for_remove) {

		err = mnt_want_write(path->mnt);

		if (err) {

			path_put(path);

			return -ENOENT;

		}



		inode_lock_nested(path->dentry->d_inode, I_MUTEX_PARENT);

		d = lookup_one_qstr_excl(&last, path->dentry, 0);

		d = start_removing_noperm(path->dentry, &last);



		if (!IS_ERR(d)) {

			dput(path->dentry);

			path->dentry = d;

			return 0;

		}

		inode_unlock(path->dentry->d_inode);

		mnt_drop_write(path->mnt);

		path_put(path);

		return -ENOENT;
@@ -1207,7 +1205,7 @@ static int ksmbd_vfs_lookup_in_dir(const struct path *dir, char *name, 
static

int __ksmbd_vfs_kern_path(struct ksmbd_work *work, char *filepath,

			  unsigned int flags,

			  struct path *path, bool caseless, bool do_lock)

			  struct path *path, bool caseless, bool for_remove)

{

	struct ksmbd_share_config *share_conf = work->tcon->share_conf;

	struct path parent_path;
@@ -1215,7 +1213,7 @@ int __ksmbd_vfs_kern_path(struct ksmbd_work *work, char *filepath, 
	int err;



retry:

	err = ksmbd_vfs_path_lookup(share_conf, filepath, flags, path, do_lock);

	err = ksmbd_vfs_path_lookup(share_conf, filepath, flags, path, for_remove);

	if (!err || !caseless)

		return err;
@@ -1286,7 +1284,7 @@ int ksmbd_vfs_kern_path(struct ksmbd_work *work, char *filepath, 
}



/**

 * ksmbd_vfs_kern_path_locked() - lookup a file and get path info

 * ksmbd_vfs_kern_path_start_remove() - lookup a file and get path info prior to removal

 * @work:		work

 * @filepath:		file path that is relative to share

 * @flags:		lookup flags
@@ -1298,7 +1296,7 @@ int ksmbd_vfs_kern_path(struct ksmbd_work *work, char *filepath, 
 * filesystem will have been gained.

 * Return:	0 on if file was found, otherwise error

 */

int ksmbd_vfs_kern_path_locked(struct ksmbd_work *work, char *filepath,

int ksmbd_vfs_kern_path_start_removing(struct ksmbd_work *work, char *filepath,

				       unsigned int flags,

				       struct path *path, bool caseless)

{
@@ -1306,12 +1304,11 @@ int ksmbd_vfs_kern_path_locked(struct ksmbd_work *work, char *filepath, 
				     caseless, true);

}



void ksmbd_vfs_kern_path_unlock(const struct path *path)

void ksmbd_vfs_kern_path_end_removing(const struct path *path)

{

	/* While lock is still held, ->d_parent is safe */

	inode_unlock(d_inode(path->dentry->d_parent));

	end_removing(path->dentry);

	mnt_drop_write(path->mnt);

	path_put(path);

	mntput(path->mnt);

}



struct dentry *ksmbd_vfs_kern_path_create(struct ksmbd_work *work,

fs/smb/server/vfs.h

+4 −4
Original line number Diff line number Diff line
@@ -120,10 +120,10 @@ int ksmbd_vfs_remove_xattr(struct mnt_idmap *idmap, 
int ksmbd_vfs_kern_path(struct ksmbd_work *work, char *name,

			unsigned int flags,

			struct path *path, bool caseless);

int ksmbd_vfs_kern_path_locked(struct ksmbd_work *work, char *name,

int ksmbd_vfs_kern_path_start_removing(struct ksmbd_work *work, char *name,

				       unsigned int flags,

				       struct path *path, bool caseless);

void ksmbd_vfs_kern_path_unlock(const struct path *path);

void ksmbd_vfs_kern_path_end_removing(const struct path *path);

struct dentry *ksmbd_vfs_kern_path_create(struct ksmbd_work *work,

					  const char *name,

					  unsigned int flags,