audit: implement all object interfield comparisons

This completes the matrix of interfield comparisons between uid/gid
information for the current task and the uid/gid information for inodes.
aka I can audit based on differences between the euid of the process and
the uid of fs objects.

Signed-off-by: Peter Moody <pmoody@google.com>
Signed-off-by: Eric Paris <eparis@redhat.com>

include/linux/audit.h

@@ -185,8 +185,16 @@
 /* AUDIT_FIELD_COMPARE rule list */
 #define AUDIT_COMPARE_UID_TO_OBJ_UID	1
 #define AUDIT_COMPARE_GID_TO_OBJ_GID	2
+#define AUDIT_COMPARE_EUID_TO_OBJ_UID	3
+#define AUDIT_COMPARE_EGID_TO_OBJ_GID	4
+#define AUDIT_COMPARE_AUID_TO_OBJ_UID	5
+#define AUDIT_COMPARE_SUID_TO_OBJ_UID	6
+#define AUDIT_COMPARE_SGID_TO_OBJ_GID	7
+#define AUDIT_COMPARE_FSUID_TO_OBJ_UID	8
+#define AUDIT_COMPARE_FSGID_TO_OBJ_GID	9
+
+#define AUDIT_MAX_FIELD_COMPARE		AUDIT_COMPARE_FSGID_TO_OBJ_GID
 
-#define AUDIT_MAX_FIELD_COMPARE	AUDIT_COMPARE_GID_TO_OBJ_GID
 /* Rule fields */
 				/* These are useful when checking the
 				 * task structure at task creation time

kernel/auditsc.c

@@ -508,6 +508,7 @@ static int audit_field_compare(struct task_struct *tsk,
 			       struct audit_names *name)
 {
 	switch (f->val) {
+	/* process to file object comparisons */
 	case AUDIT_COMPARE_UID_TO_OBJ_UID:
 		return audit_compare_id(cred->uid,
 					name, offsetof(struct audit_names, uid),
@@ -516,6 +517,34 @@ static int audit_field_compare(struct task_struct *tsk,
 		return audit_compare_id(cred->gid,
 					name, offsetof(struct audit_names, gid),
 					f, ctx);
+	case AUDIT_COMPARE_EUID_TO_OBJ_UID:
+		return audit_compare_id(cred->euid,
+					name, offsetof(struct audit_names, uid),
+					f, ctx);
+	case AUDIT_COMPARE_EGID_TO_OBJ_GID:
+		return audit_compare_id(cred->egid,
+					name, offsetof(struct audit_names, gid),
+					f, ctx);
+	case AUDIT_COMPARE_AUID_TO_OBJ_UID:
+		return audit_compare_id(tsk->loginuid,
+					name, offsetof(struct audit_names, uid),
+					f, ctx);
+	case AUDIT_COMPARE_SUID_TO_OBJ_UID:
+		return audit_compare_id(cred->suid,
+					name, offsetof(struct audit_names, uid),
+					f, ctx);
+	case AUDIT_COMPARE_SGID_TO_OBJ_GID:
+		return audit_compare_id(cred->sgid,
+					name, offsetof(struct audit_names, gid),
+					f, ctx);
+	case AUDIT_COMPARE_FSUID_TO_OBJ_UID:
+		return audit_compare_id(cred->fsuid,
+					name, offsetof(struct audit_names, uid),
+					f, ctx);
+	case AUDIT_COMPARE_FSGID_TO_OBJ_GID:
+		return audit_compare_id(cred->fsgid,
+					name, offsetof(struct audit_names, gid),
+					f, ctx);
 	default:
 		WARN(1, "Missing AUDIT_COMPARE define.  Report as a bug\n");
 		return 0;