On Wed, Nov 06, 2019 at 05:44:20PM -0800, Darrick J. Wong wrote:

On Tue, Oct 29, 2019 at 01:41:38PM -0700, Eric Biggers wrote:

quoted

From: Eric Biggers <redacted>

Add a statx attribute bit STATX_ATTR_VERITY which will be set if the
file has fs-verity enabled.  This is the statx() equivalent of
FS_VERITY_FL which is returned by FS_IOC_GETFLAGS.

This is useful because it allows applications to check whether a file is
a verity file without opening it.  Opening a verity file can be
expensive because the fsverity_info is set up on open, which involves
parsing metadata and optionally verifying a cryptographic signature.

This is analogous to how various other bits are exposed through both
FS_IOC_GETFLAGS and statx(), e.g. the encrypt bit.

Signed-off-by: Eric Biggers <redacted>
---
 include/linux/stat.h      | 3 ++-
 include/uapi/linux/stat.h | 2 +-
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/include/linux/stat.h b/include/linux/stat.h
index 765573dc17d659..528c4baad09146 100644
--- a/include/linux/stat.h
+++ b/include/linux/stat.h

@@ -33,7 +33,8 @@ struct kstat {
 	 STATX_ATTR_IMMUTABLE |				\
 	 STATX_ATTR_APPEND |				\
 	 STATX_ATTR_NODUMP |				\
-	 STATX_ATTR_ENCRYPTED				\
+	 STATX_ATTR_ENCRYPTED |				\
+	 STATX_ATTR_VERITY				\
 	 )/* Attrs corresponding to FS_*_FL flags */
 	u64		ino;
 	dev_t		dev;

diff --git a/include/uapi/linux/stat.h b/include/uapi/linux/stat.h
index 7b35e98d3c58b1..ad80a5c885d598 100644
--- a/include/uapi/linux/stat.h
+++ b/include/uapi/linux/stat.h

@@ -167,8 +167,8 @@ struct statx {
 #define STATX_ATTR_APPEND		0x00000020 /* [I] File is append-only */
 #define STATX_ATTR_NODUMP		0x00000040 /* [I] File is not to be dumped */
 #define STATX_ATTR_ENCRYPTED		0x00000800 /* [I] File requires key to decrypt in fs */
-
 #define STATX_ATTR_AUTOMOUNT		0x00001000 /* Dir: Automount trigger */
+#define STATX_ATTR_VERITY		0x00100000 /* [I] Verity protected file */

Any reason why this wasn't 0x2000?

Yes, as Andreas pointed out, the value is chosen to match the corresponding
FS_IOC_GETFLAGS bit, like the other bits above marked [I].

If there's a manpage update that goes with this, then...
Acked-by: Darrick J. Wong <redacted>

It's pretty trivial to add it to the statx(2) man page.
I've sent out a patch for comment:
https://lkml.kernel.org/linux-fscrypt/20191107220248.32025-1-ebiggers@kernel.org/

- Eric