On Wed, May 31, 2023 at 09:07:34AM -0500, Serge E. Hallyn wrote:
> 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>
Sorry, obviously I should have removed this, until the comment below was
answered :)
> > ---
> > 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
