audit: complex interfield comparison helper

Rather than code the same loop over and over implement a helper function which
uses some pointer magic to make it generic enough to be used numerous places
as we implement more audit interfield comparisons

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

1 files changed, 39 insertions, 11 deletions

diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index 8fb2c8e6d624..b12cc32fe377 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -463,25 +463,53 @@ static int match_tree_refs(struct audit_context *ctx, struct audit_tree *tree)
         return 0;
 }
 
+static int audit_compare_id(uid_t uid1,
+                            struct audit_names *name,
+                            unsigned long name_offset,
+                            struct audit_field *f,
+                            struct audit_context *ctx)
+{
+        struct audit_names *n;
+        unsigned long addr;
+        uid_t uid2;
+        int rc;
+
+        if (name) {
+                addr = (unsigned long)name;
+                addr += name_offset;
+
+                uid2 = *(uid_t *)addr;
+                rc = audit_comparator(uid1, f->op, uid2);
+                if (rc)
+                        return rc;
+        }
+
+        if (ctx) {
+                list_for_each_entry(n, &ctx->names_list, list) {
+                        addr = (unsigned long)n;
+                        addr += name_offset;
+
+                        uid2 = *(uid_t *)addr;
+
+                        rc = audit_comparator(uid1, f->op, uid2);
+                        if (rc)
+                                return rc;
+                }
+        }
+        return 0;
+}
+
 static int audit_field_compare(struct task_struct *tsk,
                                const struct cred *cred,
                                struct audit_field *f,
                                struct audit_context *ctx,
                                struct audit_names *name)
 {
-        struct audit_names *n;
-
         switch (f->val) {
         case AUDIT_COMPARE_UID_TO_OBJ_UID:
-                if (name) {
-                        return audit_comparator(cred->uid, f->op, name->uid);
-                } else if (ctx) {
-                        list_for_each_entry(n, &ctx->names_list, list) {
-                                if (audit_comparator(cred->uid, f->op, n->uid))
-                                        return 1;
-                        }
-                }
-                break;
+                return audit_compare_id(cred->uid,
+                                        name, offsetof(struct audit_names, uid),
+                                        f, ctx);
         default:
                 WARN(1, "Missing AUDIT_COMPARE define.  Report as a bug\n");
                 return 0;