netlink: policy: refactor per-attr policy writing

Refactor the per-attribute policy writing into a new
helper function, to be used later for dumping out the
policy of a rejected attribute.

v2:
 - fix some indentation
v3:
 - change variable order in netlink_policy_dump_write()

Reviewed-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/net/netlink/policy.c b/net/netlink/policy.c
index ee26d01..4383436 100644 (file)
--- a/net/netlink/policy.c
+++ b/net/netlink/policy.c
@@ -196,49 +196,33 @@ bool netlink_policy_dump_loop(struct netlink_policy_dump_state *state)
        return !netlink_policy_dump_finished(state);
 }
 
-/**
- * netlink_policy_dump_write - write current policy dump attributes
- * @skb: the message skb to write to
- * @state: the policy dump state
- *
- * Returns: 0 on success, an error code otherwise
- */
-int netlink_policy_dump_write(struct sk_buff *skb,
-                             struct netlink_policy_dump_state *state)
+static int
+__netlink_policy_dump_write_attr(struct netlink_policy_dump_state *state,
+                                struct sk_buff *skb,
+                                const struct nla_policy *pt,
+                                int nestattr)
 {
-       const struct nla_policy *pt;
-       struct nlattr *policy, *attr;
        enum netlink_attribute_type type;
-       bool again;
-
-send_attribute:
-       again = false;
-
-       pt = &state->policies[state->policy_idx].policy[state->attr_idx];
+       struct nlattr *attr;
 
-       policy = nla_nest_start(skb, state->policy_idx);
-       if (!policy)
-               return -ENOBUFS;
-
-       attr = nla_nest_start(skb, state->attr_idx);
+       attr = nla_nest_start(skb, nestattr);
        if (!attr)
-               goto nla_put_failure;
+               return -ENOBUFS;
 
        switch (pt->type) {
        default:
        case NLA_UNSPEC:
        case NLA_REJECT:
                /* skip - use NLA_MIN_LEN to advertise such */
-               nla_nest_cancel(skb, policy);
-               again = true;
-               goto next;
+               nla_nest_cancel(skb, attr);
+               return -ENODATA;
        case NLA_NESTED:
                type = NL_ATTR_TYPE_NESTED;
                fallthrough;
        case NLA_NESTED_ARRAY:
                if (pt->type == NLA_NESTED_ARRAY)
                        type = NL_ATTR_TYPE_NESTED_ARRAY;
-               if (pt->nested_policy && pt->len &&
+               if (state && pt->nested_policy && pt->len &&
                    (nla_put_u32(skb, NL_POLICY_TYPE_ATTR_POLICY_IDX,
                                 netlink_policy_dump_get_policy_idx(state,
                                                                    pt->nested_policy,
@@ -349,8 +333,47 @@ send_attribute:
        if (nla_put_u32(skb, NL_POLICY_TYPE_ATTR_TYPE, type))
                goto nla_put_failure;
 
-       /* finish and move state to next attribute */
        nla_nest_end(skb, attr);
+       return 0;
+nla_put_failure:
+       nla_nest_cancel(skb, attr);
+       return -ENOBUFS;
+}
+
+/**
+ * netlink_policy_dump_write - write current policy dump attributes
+ * @skb: the message skb to write to
+ * @state: the policy dump state
+ *
+ * Returns: 0 on success, an error code otherwise
+ */
+int netlink_policy_dump_write(struct sk_buff *skb,
+                             struct netlink_policy_dump_state *state)
+{
+       const struct nla_policy *pt;
+       struct nlattr *policy;
+       bool again;
+       int err;
+
+send_attribute:
+       again = false;
+
+       pt = &state->policies[state->policy_idx].policy[state->attr_idx];
+
+       policy = nla_nest_start(skb, state->policy_idx);
+       if (!policy)
+               return -ENOBUFS;
+
+       err = __netlink_policy_dump_write_attr(state, skb, pt, state->attr_idx);
+       if (err == -ENODATA) {
+               nla_nest_cancel(skb, policy);
+               again = true;
+               goto next;
+       } else if (err) {
+               goto nla_put_failure;
+       }
+
+       /* finish and move state to next attribute */
        nla_nest_end(skb, policy);
 
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