Merge tag 'for-5.18/io_uring-statx-2022-03-18' of git://git.kernel.dk/linux-block

Pull io_uring statx fixes from Jens Axboe:
 "On top of the main io_uring branch, this is to ensure that the
  filename component of statx is stable after submit.

  That requires a few VFS related changes"

* tag 'for-5.18/io_uring-statx-2022-03-18' of git://git.kernel.dk/linux-block:
  io-uring: Make statx API stable

1 files changed, 35 insertions, 14 deletions

diff --git a/fs/stat.c b/fs/stat.c
index 28d2020ba1f4..7f734be0e57e 100644
--- a/fs/stat.c
+++ b/fs/stat.c
@@ -184,6 +184,20 @@ int vfs_fstat(int fd, struct kstat *stat)
 	return error;
 }
 
+int getname_statx_lookup_flags(int flags)
+{
+	int lookup_flags = 0;
+
+	if (!(flags & AT_SYMLINK_NOFOLLOW))
+		lookup_flags |= LOOKUP_FOLLOW;
+	if (!(flags & AT_NO_AUTOMOUNT))
+		lookup_flags |= LOOKUP_AUTOMOUNT;
+	if (flags & AT_EMPTY_PATH)
+		lookup_flags |= LOOKUP_EMPTY;
+
+	return lookup_flags;
+}
+
 /**
  * vfs_statx - Get basic and extra attributes by filename
  * @dfd: A file descriptor representing the base dir for a relative filename
@@ -199,26 +213,19 @@ int vfs_fstat(int fd, struct kstat *stat)
  *
  * 0 will be returned on success, and a -ve error code if unsuccessful.
  */
-static int vfs_statx(int dfd, const char __user *filename, int flags,
+static int vfs_statx(int dfd, struct filename *filename, int flags,
 	      struct kstat *stat, u32 request_mask)
 {
 	struct path path;
-	unsigned lookup_flags = 0;
+	unsigned int lookup_flags = getname_statx_lookup_flags(flags);
 	int error;
 
 	if (flags & ~(AT_SYMLINK_NOFOLLOW | AT_NO_AUTOMOUNT | AT_EMPTY_PATH |
 		      AT_STATX_SYNC_TYPE))
 		return -EINVAL;
 
-	if (!(flags & AT_SYMLINK_NOFOLLOW))
-		lookup_flags |= LOOKUP_FOLLOW;
-	if (!(flags & AT_NO_AUTOMOUNT))
-		lookup_flags |= LOOKUP_AUTOMOUNT;
-	if (flags & AT_EMPTY_PATH)
-		lookup_flags |= LOOKUP_EMPTY;
-
 retry:
-	error = user_path_at(dfd, filename, lookup_flags, &path);
+	error = filename_lookup(dfd, filename, lookup_flags, &path, NULL);
 	if (error)
 		goto out;
 
@@ -240,8 +247,15 @@ out:
 int vfs_fstatat(int dfd, const char __user *filename,
 			      struct kstat *stat, int flags)
 {
-	return vfs_statx(dfd, filename, flags | AT_NO_AUTOMOUNT,
-			 stat, STATX_BASIC_STATS);
+	int ret;
+	int statx_flags = flags | AT_NO_AUTOMOUNT;
+	struct filename *name;
+
+	name = getname_flags(filename, getname_statx_lookup_flags(statx_flags), NULL);
+	ret = vfs_statx(dfd, name, statx_flags, stat, STATX_BASIC_STATS);
+	putname(name);
+
+	return ret;
 }
 
 #ifdef __ARCH_WANT_OLD_STAT
@@ -602,7 +616,7 @@ cp_statx(const struct kstat *stat, struct statx __user *buffer)
 	return copy_to_user(buffer, &tmp, sizeof(tmp)) ? -EFAULT : 0;
 }
 
-int do_statx(int dfd, const char __user *filename, unsigned flags,
+int do_statx(int dfd, struct filename *filename, unsigned int flags,
 	     unsigned int mask, struct statx __user *buffer)
 {
 	struct kstat stat;
@@ -636,7 +650,14 @@ SYSCALL_DEFINE5(statx,
 		unsigned int, mask,
 		struct statx __user *, buffer)
 {
-	return do_statx(dfd, filename, flags, mask, buffer);
+	int ret;
+	struct filename *name;
+
+	name = getname_flags(filename, getname_statx_lookup_flags(flags), NULL);
+	ret = do_statx(dfd, name, flags, mask, buffer);
+	putname(name);
+
+	return ret;
 }
 
 #ifdef CONFIG_COMPAT