Commit 333111a6 authored by Hyunchul Lee's avatar Hyunchul Lee Committed by Namjae Jeon
Browse files

ksmbd: factor out a ksmbd_vfs_lock_parent helper 



Factor out a self-contained helper to
get stable parent dentry.

Signed-off-by: default avatarHyunchul Lee <hyc.lee@gmail.com>
Signed-off-by: default avatarNamjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: default avatarSteve French <stfrench@microsoft.com>
parent 49be5aa4

fs/ksmbd/vfs.c

+62 −63
Original line number Diff line number Diff line
@@ -60,6 +60,41 @@ static void ksmbd_vfs_inherit_owner(struct ksmbd_work *work, 
	i_uid_write(inode, i_uid_read(parent_inode));

}



/**

 * ksmbd_vfs_lock_parent() - lock parent dentry if it is stable

 *

 * the parent dentry got by dget_parent or @parent could be

 * unstable, we try to lock a parent inode and lookup the

 * child dentry again.

 *

 * the reference count of @parent isn't incremented.

 */

static int ksmbd_vfs_lock_parent(struct dentry *parent, struct dentry *child)

{

	struct dentry *dentry;

	int ret = 0;



	inode_lock_nested(d_inode(parent), I_MUTEX_PARENT);

	dentry = lookup_one_len(child->d_name.name, parent,

				child->d_name.len);

	if (IS_ERR(dentry)) {

		ret = PTR_ERR(dentry);

		goto out_err;

	}



	if (dentry != child) {

		ret = -ESTALE;

		dput(dentry);

		goto out_err;

	}



	dput(dentry);

	return 0;

out_err:

	inode_unlock(d_inode(parent));

	return ret;

}



int ksmbd_vfs_inode_permission(struct dentry *dentry, int acc_mode, bool delete)

{

	int mask, ret = 0;
@@ -78,29 +113,18 @@ int ksmbd_vfs_inode_permission(struct dentry *dentry, int acc_mode, bool delete) 
		return -EACCES;



	if (delete) {

		struct dentry *child, *parent;

		struct dentry *parent;



		parent = dget_parent(dentry);

		inode_lock_nested(d_inode(parent), I_MUTEX_PARENT);

		child = lookup_one_len(dentry->d_name.name, parent,

				       dentry->d_name.len);

		if (IS_ERR(child)) {

			ret = PTR_ERR(child);

			goto out_lock;

		}



		if (child != dentry) {

			ret = -ESTALE;

			dput(child);

			goto out_lock;

		ret = ksmbd_vfs_lock_parent(parent, dentry);

		if (ret) {

			dput(parent);

			return ret;

		}

		dput(child);



		if (inode_permission(&init_user_ns, d_inode(parent), MAY_EXEC | MAY_WRITE)) {

		if (inode_permission(&init_user_ns, d_inode(parent), MAY_EXEC | MAY_WRITE))

			ret = -EACCES;

			goto out_lock;

		}

out_lock:



		inode_unlock(d_inode(parent));

		dput(parent);

	}
@@ -109,7 +133,7 @@ int ksmbd_vfs_inode_permission(struct dentry *dentry, int acc_mode, bool delete) 


int ksmbd_vfs_query_maximal_access(struct dentry *dentry, __le32 *daccess)

{

	struct dentry *parent, *child;

	struct dentry *parent;

	int ret = 0;



	*daccess = cpu_to_le32(FILE_READ_ATTRIBUTES | READ_CONTROL);
@@ -127,25 +151,15 @@ int ksmbd_vfs_query_maximal_access(struct dentry *dentry, __le32 *daccess) 
		*daccess |= FILE_EXECUTE_LE;



	parent = dget_parent(dentry);

	inode_lock_nested(d_inode(parent), I_MUTEX_PARENT);

	child = lookup_one_len(dentry->d_name.name, parent,

			       dentry->d_name.len);

	if (IS_ERR(child)) {

		ret = PTR_ERR(child);

		goto out_lock;

	}



	if (child != dentry) {

		ret = -ESTALE;

		dput(child);

		goto out_lock;

	ret = ksmbd_vfs_lock_parent(parent, dentry);

	if (ret) {

		dput(parent);

		return ret;

	}

	dput(child);



	if (!inode_permission(&init_user_ns, d_inode(parent), MAY_EXEC | MAY_WRITE))

		*daccess |= FILE_DELETE_LE;



out_lock:

	inode_unlock(d_inode(parent));

	dput(parent);

	return ret;
@@ -573,7 +587,7 @@ int ksmbd_vfs_fsync(struct ksmbd_work *work, u64 fid, u64 p_id) 
int ksmbd_vfs_remove_file(struct ksmbd_work *work, char *name)

{

	struct path path;

	struct dentry *dentry, *parent;

	struct dentry *parent;

	int err;

	int flags = 0;
@@ -592,35 +606,32 @@ int ksmbd_vfs_remove_file(struct ksmbd_work *work, char *name) 
	}



	parent = dget_parent(path.dentry);

	inode_lock_nested(d_inode(parent), I_MUTEX_PARENT);

	dentry = lookup_one_len(path.dentry->d_name.name, parent,

				strlen(path.dentry->d_name.name));

	if (IS_ERR(dentry)) {

		err = PTR_ERR(dentry);

		ksmbd_debug(VFS, "%s: lookup failed, err %d\n",

			    path.dentry->d_name.name, err);

		goto out_err;

	err = ksmbd_vfs_lock_parent(parent, path.dentry);

	if (err) {

		dput(parent);

		path_put(&path);

		ksmbd_revert_fsids(work);

		return err;

	}



	if (!d_inode(dentry) || !d_inode(dentry)->i_nlink) {

		dput(dentry);

	if (!d_inode(path.dentry)->i_nlink) {

		err = -ENOENT;

		goto out_err;

	}



	if (S_ISDIR(d_inode(dentry)->i_mode)) {

		err = vfs_rmdir(&init_user_ns, d_inode(parent), dentry);

	if (S_ISDIR(d_inode(path.dentry)->i_mode)) {

		err = vfs_rmdir(&init_user_ns, d_inode(parent), path.dentry);

		if (err && err != -ENOTEMPTY)

			ksmbd_debug(VFS, "%s: rmdir failed, err %d\n", name,

				    err);

	} else {

		err = vfs_unlink(&init_user_ns, d_inode(parent), dentry, NULL);

		err = vfs_unlink(&init_user_ns, d_inode(parent), path.dentry,

				 NULL);

		if (err)

			ksmbd_debug(VFS, "%s: unlink failed, err %d\n", name,

				    err);

	}



	dput(dentry);

out_err:

	inode_unlock(d_inode(parent));

	dput(parent);
@@ -1086,30 +1097,18 @@ int ksmbd_vfs_remove_xattr(struct dentry *dentry, char *attr_name) 


int ksmbd_vfs_unlink(struct dentry *dir, struct dentry *dentry)

{

	struct dentry *child;

	int err = 0;



	inode_lock_nested(d_inode(dir), I_MUTEX_PARENT);

	err = ksmbd_vfs_lock_parent(dir, dentry);

	if (err)

		return err;

	dget(dentry);

	child = lookup_one_len(dentry->d_name.name, dir, dentry->d_name.len);

	if (IS_ERR(child)) {

		err = PTR_ERR(child);

		goto out;

	}



	if (child != dentry) {

		err = -ESTALE;

		dput(child);

		goto out;

	}

	dput(child);



	if (S_ISDIR(d_inode(dentry)->i_mode))

		err = vfs_rmdir(&init_user_ns, d_inode(dir), dentry);

	else

		err = vfs_unlink(&init_user_ns, d_inode(dir), dentry, NULL);



out:

	dput(dentry);

	inode_unlock(d_inode(dir));

	if (err)