audit: allow interfield comparison between gid and ogid

Allow audit rules to compare the gid of the running task to the gid of the
inode in question.

Signed-off-by: Eric Paris <eparis@redhat.com>

2 files changed, 8 insertions, 1 deletions

diff --git a/include/linux/audit.h b/include/linux/audit.h
index 838e05fc0582..fffbc2176ee1 100644
--- a/include/linux/audit.h
+++ b/include/linux/audit.h
@@ -184,8 +184,9 @@
 
 /* AUDIT_FIELD_COMPARE rule list */
 #define AUDIT_COMPARE_UID_TO_OBJ_UID    1
+#define AUDIT_COMPARE_GID_TO_OBJ_GID    2
 
-#define AUDIT_MAX_FIELD_COMPARE AUDIT_COMPARE_UID_TO_OBJ_UID
+#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
diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index b12cc32fe377..861c7b9c565a 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -474,6 +474,8 @@ static int audit_compare_id(uid_t uid1,
         uid_t uid2;
         int rc;
 
+        BUILD_BUG_ON(sizeof(uid_t) != sizeof(gid_t));
+
         if (name) {
                 addr = (unsigned long)name;
                 addr += name_offset;
@@ -510,6 +512,10 @@ static int audit_field_compare(struct task_struct *tsk,
                 return audit_compare_id(cred->uid,
                                         name, offsetof(struct audit_names, uid),
                                         f, ctx);
+        case AUDIT_COMPARE_GID_TO_OBJ_GID:
+                return audit_compare_id(cred->gid,
+                                        name, offsetof(struct audit_names, gid),
+                                        f, ctx);
         default:
                 WARN(1, "Missing AUDIT_COMPARE define.  Report as a bug\n");
                 return 0;