Re: [PATCH] audit: convert status version to a feature bitmap

On Thursday, November 13, 2014 03:29:10 PM Richard Guy Briggs wrote: > The version field defined in the audit status structure was found to have > limitations in terms of its expressibility of features supported. This is > distict from the get/set features call to be able to command those features > that are present. > > Converting this field from a version number to a feature bitmap will allow > distributions to selectively backport and support certain features and will > allow upstream to be able to deprecate features in the future. It will > allow userspace clients to first query the kernel for which features are > actually present and supported. Currently, EINVAL is returned rather than > EOPNOTSUP, which isn't helpful in determining if there was an error in the > command, or if it simply isn't supported yet. Past features are not > represented by this bitmap, but their use may be converted to EOPNOTSUP if > needed in the future. > > Since "version" is too generic to convert with a #define, use a union in the > struct status, introducing the member "feature_bitmap" unionized with > "version". > > Convert existing AUDIT_VERSION_* macros over to AUDIT_FEATURE_BITMAP* > counterparts, leaving the former for backwards compatibility. > > Signed-off-by: Richard Guy Briggs <rgb(a)redhat.com&gt; > --- > include/uapi/linux/audit.h | 17 +++++++++++++---- > kernel/audit.c | 2 +- > 2 files changed, 14 insertions(+), 5 deletions(-) Looks good for the most part, just a naming nit pick and a question about the deprecated AUDIT_VERSION_* defines; see below ... > diff --git a/include/uapi/linux/audit.h b/include/uapi/linux/audit.h > index 4d100c8..74aa584 100644 > --- a/include/uapi/linux/audit.h > +++ b/include/uapi/linux/audit.h > @@ -322,9 +322,15 @@ enum { > #define AUDIT_STATUS_BACKLOG_LIMIT 0x0010 > #define AUDIT_STATUS_BACKLOG_WAIT_TIME 0x0020 > > -#define AUDIT_VERSION_BACKLOG_LIMIT 1 > -#define AUDIT_VERSION_BACKLOG_WAIT_TIME 2 > -#define AUDIT_VERSION_LATEST AUDIT_VERSION_BACKLOG_WAIT_TIME > +#define AUDIT_FEATURE_BITMAP_BACKLOG_LIMIT 0x00000001 > +#define AUDIT_FEATURE_BITMAP_BACKLOG_WAIT_TIME 0x00000002 > +#define AUDIT_FEATURE_BITMAP ( AUDIT_FEATURE_BITMAP_BACKLOG_LIMIT | \ > + AUDIT_FEATURE_BITMAP_BACKLOG_WAIT_TIME ) How about AUDIT_FEATURE_BIMAP_ALL instead of just AUDIT_FEATURE_BITMAP?

> +/* deprecated: AUDIT_VERSION_* */ > +#define AUDIT_VERSION_LATEST AUDIT_FEATURE_BITMAP > +#define AUDIT_VERSION_BACKLOG_LIMIT AUDIT_FEATURE_BITMAP_BACKLOG_LIMIT > +#define AUDIT_VERSION_BACKLOG_WAIT_TIME > ... AUDIT_FEATURE_BITMAP_BACKLOG_WAIT_TIME So what terrible things happen to userspace if AUDIT_VERSION_BACKLOG_WAIT_TIME becomes 0x03 instead of 0x02?

paul moore