On Thu, May 11, 2023 at 04:25:24PM +0200, Christian Göttsche wrote:
> Introduce a new capable flag, CAP_OPT_NODENYAUDIT, to not generate
> an audit event if the requested capability is not granted. This will be
> used in a new capable_any() functionality to reduce the number of
> necessary capable calls.
>
> Handle the flag accordingly in AppArmor and SELinux.
>
> Suggested-by: Paul Moore <paul@xxxxxxxxxxxxxx>
> Signed-off-by: Christian Göttsche <cgzones@xxxxxxxxxxxxxx>
Reviewed-by: Serge Hallyn <serge@xxxxxxxxxx>
> ---
> include/linux/security.h | 2 ++
> security/apparmor/capability.c | 8 +++++---
> security/selinux/hooks.c | 14 ++++++++------
> 3 files changed, 15 insertions(+), 9 deletions(-)
>
> diff --git a/include/linux/security.h b/include/linux/security.h
> index e2734e9e44d5..629c775ec297 100644
> --- a/include/linux/security.h
> +++ b/include/linux/security.h
> @@ -67,6 +67,8 @@ struct watch_notification;
> #define CAP_OPT_NOAUDIT BIT(1)
> /* If capable is being called by a setid function */
> #define CAP_OPT_INSETID BIT(2)
> +/* If capable should audit the security request for authorized requests only */
> +#define CAP_OPT_NODENYAUDIT BIT(3)
>
> /* LSM Agnostic defines for security_sb_set_mnt_opts() flags */
> #define SECURITY_LSM_NATIVE_LABELS 1
> diff --git a/security/apparmor/capability.c b/security/apparmor/capability.c
> index 326a51838ef2..98120dd62ca7 100644
> --- a/security/apparmor/capability.c
> +++ b/security/apparmor/capability.c
> @@ -108,7 +108,8 @@ static int audit_caps(struct common_audit_data *sa, struct aa_profile *profile,
> * profile_capable - test if profile allows use of capability @cap
> * @profile: profile being enforced (NOT NULL, NOT unconfined)
> * @cap: capability to test if allowed
> - * @opts: CAP_OPT_NOAUDIT bit determines whether audit record is generated
> + * @opts: CAP_OPT_NOAUDIT/CAP_OPT_NODENYAUDIT bit determines whether audit
> + * record is generated
> * @sa: audit data (MAY BE NULL indicating no auditing)
> *
> * Returns: 0 if allowed else -EPERM
> @@ -126,7 +127,7 @@ static int profile_capable(struct aa_profile *profile, int cap,
> else
> error = -EPERM;
>
> - if (opts & CAP_OPT_NOAUDIT) {
> + if ((opts & CAP_OPT_NOAUDIT) || ((opts & CAP_OPT_NODENYAUDIT) && error)) {
> if (!COMPLAIN_MODE(profile))
> return error;
> /* audit the cap request in complain mode but note that it
> @@ -142,7 +143,8 @@ static int profile_capable(struct aa_profile *profile, int cap,
> * aa_capable - test permission to use capability
> * @label: label being tested for capability (NOT NULL)
> * @cap: capability to be tested
> - * @opts: CAP_OPT_NOAUDIT bit determines whether audit record is generated
> + * @opts: CAP_OPT_NOAUDIT/CAP_OPT_NODENYAUDIT bit determines whether audit
> + * record is generated
> *
> * Look up capability in profile capability set.
> *
> diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
> index 79b4890e9936..0730edf2f5f1 100644
> --- a/security/selinux/hooks.c
> +++ b/security/selinux/hooks.c
> @@ -1571,7 +1571,7 @@ static int cred_has_capability(const struct cred *cred,
> u16 sclass;
> u32 sid = cred_sid(cred);
> u32 av = CAP_TO_MASK(cap);
> - int rc;
> + int rc, rc2;
>
> ad.type = LSM_AUDIT_DATA_CAP;
> ad.u.cap = cap;
> @@ -1590,11 +1590,13 @@ static int cred_has_capability(const struct cred *cred,
> }
>
> rc = avc_has_perm_noaudit(sid, sid, sclass, av, 0, &avd);
> - if (!(opts & CAP_OPT_NOAUDIT)) {
> - int rc2 = avc_audit(sid, sid, sclass, av, &avd, rc, &ad);
> - if (rc2)
> - return rc2;
> - }
> + if ((opts & CAP_OPT_NOAUDIT) || ((opts & CAP_OPT_NODENYAUDIT) && rc))
> + return rc;
Hm, if the caller passes only CAP_OPT_NODENYAUDIT, and rc == 0, then
you will audit the allow. Is that what you want, or did you want, or
did you want CAP_OPT_NODENYAUDIT to imply CAP_OPT_NOAUDIT?
> +
> + rc2 = avc_audit(sid, sid, sclass, av, &avd, rc, &ad);
> + if (rc2)
> + return rc2;
> +
> return rc;
> }
>
> --
> 2.40.1
