namei: make do_mkdirat() take struct filename

Pass in the struct filename pointers instead of the user string, and
update the three callers to do the same. This is heavily based on
commit dbea8d345177 ("fs: make do_renameat2() take struct filename").

This behaves like do_unlinkat() and do_renameat2().

Cc: Al Viro <viro@zeniv.linux.org.uk>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Dmitry Kadashev <dkadashev@gmail.com>
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
Link: https://lore.kernel.org/r/20210708063447.3556403-4-dkadashev@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

1 files changed, 19 insertions, 7 deletions

diff --git a/fs/namei.c b/fs/namei.c
index aaba6b42b222..e9358e61fce2 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -3573,7 +3573,7 @@ struct file *do_file_open_root(const struct path *root,
 	return file;
 }
 
-static struct dentry *filename_create(int dfd, struct filename *name,
+static struct dentry *__filename_create(int dfd, struct filename *name,
 				struct path *path, unsigned int lookup_flags)
 {
 	struct dentry *dentry = ERR_PTR(-EEXIST);
@@ -3589,7 +3589,7 @@ static struct dentry *filename_create(int dfd, struct filename *name,
 	 */
 	lookup_flags &= LOOKUP_REVAL;
 
-	error = filename_parentat(dfd, name, lookup_flags, path, &last, &type);
+	error = __filename_parentat(dfd, name, lookup_flags, path, &last, &type);
 	if (error)
 		return ERR_PTR(error);
 
@@ -3642,6 +3642,15 @@ out:
 	return dentry;
 }
 
+static inline struct dentry *filename_create(int dfd, struct filename *name,
+				struct path *path, unsigned int lookup_flags)
+{
+	struct dentry *res = __filename_create(dfd, name, path, lookup_flags);
+
+	putname(name);
+	return res;
+}
+
 struct dentry *kern_path_create(int dfd, const char *pathname,
 				struct path *path, unsigned int lookup_flags)
 {
@@ -3832,7 +3841,7 @@ int vfs_mkdir(struct user_namespace *mnt_userns, struct inode *dir,
 }
 EXPORT_SYMBOL(vfs_mkdir);
 
-static long do_mkdirat(int dfd, const char __user *pathname, umode_t mode)
+long do_mkdirat(int dfd, struct filename *name, umode_t mode)
 {
 	struct dentry *dentry;
 	struct path path;
@@ -3840,9 +3849,10 @@ static long do_mkdirat(int dfd, const char __user *pathname, umode_t mode)
 	unsigned int lookup_flags = LOOKUP_DIRECTORY;
 
 retry:
-	dentry = user_path_create(dfd, pathname, &path, lookup_flags);
+	dentry = __filename_create(dfd, name, &path, lookup_flags);
+	error = PTR_ERR(dentry);
 	if (IS_ERR(dentry))
-		return PTR_ERR(dentry);
+		goto out_putname;
 
 	if (!IS_POSIXACL(path.dentry->d_inode))
 		mode &= ~current_umask();
@@ -3858,17 +3868,19 @@ retry:
 		lookup_flags |= LOOKUP_REVAL;
 		goto retry;
 	}
+out_putname:
+	putname(name);
 	return error;
 }
 
 SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, umode_t, mode)
 {
-	return do_mkdirat(dfd, pathname, mode);
+	return do_mkdirat(dfd, getname(pathname), mode);
 }
 
 SYSCALL_DEFINE2(mkdir, const char __user *, pathname, umode_t, mode)
 {
-	return do_mkdirat(AT_FDCWD, pathname, mode);
+	return do_mkdirat(AT_FDCWD, getname(pathname), mode);
 }
 
 /**