audit: audit feature to only allow unsetting the loginuid

This is a new audit feature which only grants processes with
CAP_AUDIT_CONTROL the ability to unset their loginuid.  They cannot
directly set it from a valid uid to another valid uid.  The ability to
unset the loginuid is nice because a priviledged task, like that of
container creation, can unset the loginuid and then priv is not needed
inside the container when a login daemon needs to set the loginuid.

Signed-off-by: Eric Paris <eparis@redhat.com>
Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
Signed-off-by: Eric Paris <eparis@redhat.com>
This commit is contained in:
Eric Paris 2013-05-24 09:18:04 -04:00
parent 81407c84ac
commit d040e5af38
3 changed files with 7 additions and 2 deletions

View File

@ -386,7 +386,8 @@ struct audit_features {
__u32 lock; /* which features to lock */
};
#define AUDIT_LAST_FEATURE -1
#define AUDIT_FEATURE_ONLY_UNSET_LOGINUID 0
#define AUDIT_LAST_FEATURE AUDIT_FEATURE_ONLY_UNSET_LOGINUID
#define audit_feature_valid(x) ((x) >= 0 && (x) <= AUDIT_LAST_FEATURE)
#define AUDIT_FEATURE_TO_MASK(x) (1 << ((x) & 31)) /* mask for __u32 */

View File

@ -144,7 +144,8 @@ static struct audit_features af = {.vers = AUDIT_FEATURE_VERSION,
.features = 0,
.lock = 0,};
static char *audit_feature_names[0] = {
static char *audit_feature_names[1] = {
"only_unset_loginuid",
};

View File

@ -1974,6 +1974,9 @@ static int audit_set_loginuid_perm(kuid_t loginuid)
/* it is set, you need permission */
if (!capable(CAP_AUDIT_CONTROL))
return -EPERM;
/* reject if this is not an unset and we don't allow that */
if (is_audit_feature_set(AUDIT_FEATURE_ONLY_UNSET_LOGINUID) && uid_valid(loginuid))
return -EPERM;
return 0;
}