[PATCH v15 20/23] Audit: Add subj_LSM fields when necessary

[Paul Moore]

On Fri, Feb 21, 2020 at 7:06 PM Casey Schaufler <casey at schaufler-ca.com> wrote:
>
> Add record entries to identify subject data for all of the
> security modules when there is more than one.
>
> Acked-by: Stephen Smalley <sds at tycho.nsa.gov>
> Signed-off-by: Casey Schaufler <casey at schaufler-ca.com>
> Cc: netdev at vger.kernel.org
> Cc: linux-audit at redhat.com
> ---
>  drivers/android/binder.c                |  2 +-
>  include/linux/audit.h                   |  1 +
>  include/linux/security.h                |  9 ++++-
>  include/net/scm.h                       |  3 +-
>  kernel/audit.c                          | 40 ++++++++++++++++++-
>  kernel/audit_fsnotify.c                 |  1 +
>  kernel/auditfilter.c                    |  1 +
>  kernel/auditsc.c                        | 10 +++--
>  net/ipv4/ip_sockglue.c                  |  2 +-
>  net/netfilter/nf_conntrack_netlink.c    |  4 +-
>  net/netfilter/nf_conntrack_standalone.c |  2 +-
>  net/netfilter/nfnetlink_queue.c         |  2 +-
>  net/netlabel/netlabel_unlabeled.c       | 11 ++++--
>  net/netlabel/netlabel_user.c            |  2 +-
>  net/xfrm/xfrm_policy.c                  |  2 +
>  net/xfrm/xfrm_state.c                   |  2 +
>  security/integrity/ima/ima_api.c        |  1 +
>  security/integrity/integrity_audit.c    |  1 +
>  security/security.c                     | 51 +++++++++++++++++++++++--
>  19 files changed, 124 insertions(+), 23 deletions(-)

...

> diff --git a/kernel/audit.c b/kernel/audit.c
> index a25097cfe623..c3a1d8d2d33c 100644
> --- a/kernel/audit.c
> +++ b/kernel/audit.c
> @@ -2054,6 +2061,33 @@ void audit_log_key(struct audit_buffer *ab, char *key)
>                 audit_log_format(ab, "(null)");
>  }
>
> +void audit_log_task_lsms(struct audit_buffer *ab)
> +{
> +       int i;
> +       const char *lsm;
> +       struct lsmblob blob;
> +       struct lsmcontext context;
> +
> +       /*
> +        * Don't do anything unless there is more than one LSM
> +        * with a security context to report.
> +        */
> +       if (security_lsm_slot_name(1) == NULL)
> +               return;
> +
> +       security_task_getsecid(current, &blob);
> +
> +       for (i = 0; i < LSMBLOB_ENTRIES; i++) {
> +               lsm = security_lsm_slot_name(i);
> +               if (lsm == NULL)
> +                       break;
> +               if (security_secid_to_secctx(&blob, &context, i))
> +                       continue;
> +               audit_log_format(ab, " subj_%s=%s", lsm, context.context);
> +               security_release_secctx(&context);
> +       }
> +}
> +
>  int audit_log_task_context(struct audit_buffer *ab)
>  {
>         int error;
> @@ -2064,7 +2098,7 @@ int audit_log_task_context(struct audit_buffer *ab)
>         if (!lsmblob_is_set(&blob))
>                 return 0;
>
> -       error = security_secid_to_secctx(&blob, &context);
> +       error = security_secid_to_secctx(&blob, &context, LSMBLOB_FIRST);
>         if (error) {
>                 if (error != -EINVAL)
>                         goto error_path;

Sorry, please disregard my previous ACK.

We should treat "subj=" similar to how we treat "obj="; if there is
more than one LSM loaded the "subj=" should be set to "?" with the
"subj_XXX=" set to the appropriate label for the named LSM.  This
patch looks like it is always using LSMBLOB_FIRST and not "?" when
multiple LSMs are present.

-- 
paul moore
www.paul-moore.com