audit: Make testing for a valid loginuid explicit.
audit rule additions containing "-F auid!=4294967295" were failing
with EINVAL because of a regression caused by e1760bd.
Apparently some userland audit rule sets want to know if loginuid uid
has been set and are using a test for auid != 4294967295 to determine
that.
In practice that is a horrible way to ask if a value has been set,
because it relies on subtle implementation details and will break
every time the uid implementation in the kernel changes.
So add a clean way to test if the audit loginuid has been set, and
silently convert the old idiom to the cleaner and more comprehensible
new idiom.
Cc: <stable@vger.kernel.org> # 3.7
Reported-By: Richard Guy Briggs <rgb@redhat.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Tested-by: Richard Guy Briggs <rgb@redhat.com>
Signed-off-by: Eric Paris <eparis@redhat.com>
diff --git a/include/linux/audit.h b/include/linux/audit.h
index 469d117..b20b038 100644
--- a/include/linux/audit.h
+++ b/include/linux/audit.h
@@ -391,6 +391,11 @@
#define audit_signals 0
#endif /* CONFIG_AUDITSYSCALL */
+static inline bool audit_loginuid_set(struct task_struct *tsk)
+{
+ return uid_valid(audit_get_loginuid(tsk));
+}
+
#ifdef CONFIG_AUDIT
/* These are defined in audit.c */
/* Public API */
diff --git a/include/uapi/linux/audit.h b/include/uapi/linux/audit.h
index c058c24..75cef3f 100644
--- a/include/uapi/linux/audit.h
+++ b/include/uapi/linux/audit.h
@@ -246,6 +246,7 @@
#define AUDIT_OBJ_TYPE 21
#define AUDIT_OBJ_LEV_LOW 22
#define AUDIT_OBJ_LEV_HIGH 23
+#define AUDIT_LOGINUID_SET 24
/* These are ONLY useful when checking
* at syscall exit time (AUDIT_AT_EXIT). */
diff --git a/kernel/auditfilter.c b/kernel/auditfilter.c
index 478f460..bc6595f 100644
--- a/kernel/auditfilter.c
+++ b/kernel/auditfilter.c
@@ -365,7 +365,10 @@
case AUDIT_DIR:
case AUDIT_FILTERKEY:
break;
- /* arch is only allowed to be = or != */
+ case AUDIT_LOGINUID_SET:
+ if ((f->val != 0) && (f->val != 1))
+ return -EINVAL;
+ /* FALL THROUGH */
case AUDIT_ARCH:
if (f->op != Audit_not_equal && f->op != Audit_equal)
return -EINVAL;
@@ -419,17 +422,23 @@
f->lsm_str = NULL;
f->lsm_rule = NULL;
+ /* Support legacy tests for a valid loginuid */
+ if ((f->type == AUDIT_LOGINUID) && (f->val == 4294967295)) {
+ f->type = AUDIT_LOGINUID_SET;
+ f->val = 0;
+ }
+
err = audit_field_valid(entry, f);
if (err)
goto exit_free;
err = -EINVAL;
switch (f->type) {
+ case AUDIT_LOGINUID:
case AUDIT_UID:
case AUDIT_EUID:
case AUDIT_SUID:
case AUDIT_FSUID:
- case AUDIT_LOGINUID:
case AUDIT_OBJ_UID:
f->uid = make_kuid(current_user_ns(), f->val);
if (!uid_valid(f->uid))
@@ -1222,6 +1231,10 @@
result = audit_uid_comparator(audit_get_loginuid(current),
f->op, f->uid);
break;
+ case AUDIT_LOGINUID_SET:
+ result = audit_comparator(audit_loginuid_set(current),
+ f->op, f->val);
+ break;
case AUDIT_MSGTYPE:
result = audit_comparator(type, f->op, f->val);
break;
diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index add3086..3c8a601 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -613,6 +613,9 @@
if (ctx)
result = audit_uid_comparator(tsk->loginuid, f->op, f->uid);
break;
+ case AUDIT_LOGINUID_SET:
+ result = audit_comparator(audit_loginuid_set(tsk), f->op, f->val);
+ break;
case AUDIT_SUBJ_USER:
case AUDIT_SUBJ_ROLE:
case AUDIT_SUBJ_TYPE:
@@ -1970,7 +1973,7 @@
unsigned int sessionid;
#ifdef CONFIG_AUDIT_LOGINUID_IMMUTABLE
- if (uid_valid(task->loginuid))
+ if (audit_loginuid_set(task))
return -EPERM;
#else /* CONFIG_AUDIT_LOGINUID_IMMUTABLE */
if (!capable(CAP_AUDIT_CONTROL))