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authorStefan Roesch <shr@fb.com>2022-02-25 19:53:26 +0100
committerJens Axboe <axboe@kernel.dk>2022-03-10 17:33:55 +0100
commit1b6fe6e0dfecf8c82a64fb87148ad9333fa2f62e (patch)
treef5c41470131e67327323a593e14622429d36b76c /fs/stat.c
parentio_uring: Add support for napi_busy_poll (diff)
downloadlinux-1b6fe6e0dfecf8c82a64fb87148ad9333fa2f62e.tar.xz
linux-1b6fe6e0dfecf8c82a64fb87148ad9333fa2f62e.zip
io-uring: Make statx API stable
One of the key architectual tenets is to keep the parameters for io-uring stable. After the call has been submitted, its value can be changed. Unfortunaltely this is not the case for the current statx implementation. IO-Uring change: This changes replaces the const char * filename pointer in the io_statx structure with a struct filename *. In addition it also creates the filename object during the prepare phase. With this change, the opcode also needs to invoke cleanup, so the filename object gets freed after processing the request. fs change: 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> Link: https://lore.kernel.org/r/20220225185326.1373304-2-shr@fb.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'fs/stat.c')
-rw-r--r--fs/stat.c49
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