statx: Reserve the top bit of the mask for future struct expansion

Reserve the top bit of the mask for future expansion of the statx struct
and give an error if statx() sees it set.  All the other bits are ignored
if we see them set but don't support the bit; we just clear the bit in the
returned mask.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
David Howells 2017-03-31 18:32:10 +01:00 committed by Al Viro
parent 5f955f26f3
commit 47071aee6a
2 changed files with 3 additions and 0 deletions

View File

@ -562,6 +562,8 @@ SYSCALL_DEFINE5(statx,
struct kstat stat;
int error;
if (mask & STATX__RESERVED)
return -EINVAL;
if ((flags & AT_STATX_SYNC_TYPE) == AT_STATX_SYNC_TYPE)
return -EINVAL;

View File

@ -152,6 +152,7 @@ struct statx {
#define STATX_BASIC_STATS 0x000007ffU /* The stuff in the normal stat struct */
#define STATX_BTIME 0x00000800U /* Want/got stx_btime */
#define STATX_ALL 0x00000fffU /* All currently supported flags */
#define STATX__RESERVED 0x80000000U /* Reserved for future struct statx expansion */
/*
* Attributes to be found in stx_attributes