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:
> > From: Eric Biggers <ebiggers@xxxxxxxxxx>
> >
> > 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 <ebiggers@xxxxxxxxxx>
> > ---
> > 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 <darrick.wong@xxxxxxxxxx>
>
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@xxxxxxxxxx/
- Eric
