diff mbox series

[v2,1/2] fs: replace const char* parameter in vfs_statx and do_statx with struct filename

Message ID 20220215002121.2049686-2-shr@fb.com (mailing list archive)
State New, archived
Headers show
Series io-uring: Make statx api stable | expand

Commit Message

Stefan Roesch Feb. 15, 2022, 12:21 a.m. UTC 
This replaces the const char* __user filename parameter in the two
functions do_statx and vfs_statx with a struct filename *. In addition
to be able to correctly construct a filename object a new helper
function getname_statx_lookup_flags is introduced. The function makes
sure that do_statx and vfs_statx is invoked with the correct lookup flags.

Signed-off-by: Stefan Roesch <shr@fb.com>
---
 fs/internal.h |  4 +++-
 fs/stat.c     | 48 +++++++++++++++++++++++++++++++++++-------------
 2 files changed, 38 insertions(+), 14 deletions(-)

Comments

Al Viro Feb. 15, 2022, 1:15 a.m. UTC | #1 
On Mon, Feb 14, 2022 at 04:21:20PM -0800, Stefan Roesch wrote:
>  {
> -	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);
> +	if (name)
> +		putname(name);

... and the same comment goes for this one - getname... does *not*
report a failure as NULL; it's ERR_PTR(), and putname(ERR_PTR(...))
is an explicit no-op.
Stefan Roesch Feb. 15, 2022, 6:19 p.m. UTC | #2 
On 2/14/22 5:15 PM, Al Viro wrote:
> On Mon, Feb 14, 2022 at 04:21:20PM -0800, Stefan Roesch wrote:
>>  {
>> -	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);
>> +	if (name)
>> +		putname(name);
> 
> ... and the same comment goes for this one - getname... does *not*
> report a failure as NULL; it's ERR_PTR(), and putname(ERR_PTR(...))
> is an explicit no-op.

I addressed this with v3 of the patch.
diff mbox series

Patch

diff --git a/fs/internal.h b/fs/internal.h
index 8590c973c2f4..56c0477f4215 100644
--- a/fs/internal.h
+++ b/fs/internal.h
@@ -184,7 +184,9 @@  int sb_init_dio_done_wq(struct super_block *sb);
 /*
  * fs/stat.c:
  */
-int do_statx(int dfd, const char __user *filename, unsigned flags,
+
+int getname_statx_lookup_flags(int flags);
+int do_statx(int dfd, struct filename *filename, unsigned int flags,
 	     unsigned int mask, struct statx __user *buffer);
 
 /*
diff --git a/fs/stat.c b/fs/stat.c
index 28d2020ba1f4..ea1ab31a7a0c 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
@@ -199,7 +213,7 @@  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;
@@ -210,15 +224,8 @@  static int vfs_statx(int dfd, const char __user *filename, int flags,
 		      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, flags, &path, NULL);
 	if (error)
 		goto out;
 
@@ -240,8 +247,15 @@  static int vfs_statx(int dfd, const char __user *filename, int flags,
 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 +650,15 @@  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);
+	if (name)
+		putname(name);
+
+	return ret;
 }
 
 #ifdef CONFIG_COMPAT