neighbour: Move two validations from neigh_get() to neigh_valid_get_req().

We will remove RTNL for neigh_get() and run it under RCU instead.

neigh_get() returns -EINVAL in the following cases:

  * NDA_DST is not specified
  * Both ndm->ndm_ifindex and NTF_PROXY are not specified

These validations do not require RCU.

Let's move them to neigh_valid_get_req().

While at it, the extack string for the first case is replaced with
NL_SET_ERR_ATTR_MISS().

Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
Link: https://patch.msgid.link/20250716221221.442239-3-kuniyu@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/net/core/neighbour.c b/net/core/neighbour.c
index e888827c4b7d4240890384ce81bbb00e93c525f0..7b63f47cd61a3d847567c615f1a272d3758f03ef 100644 (file)
--- a/net/core/neighbour.c
+++ b/net/core/neighbour.c
@@ -2935,6 +2935,11 @@ static struct ndmsg *neigh_valid_get_req(const struct nlmsghdr *nlh,
                return ERR_PTR(-EINVAL);
        }
 
+       if (!(ndm->ndm_flags & NTF_PROXY) && !ndm->ndm_ifindex) {
+               NL_SET_ERR_MSG(extack, "No device specified");
+               return ERR_PTR(-EINVAL);
+       }
+
        err = nlmsg_parse_deprecated_strict(nlh, sizeof(struct ndmsg), tb,
                                            NDA_MAX, nda_policy, extack);
        if (err < 0)
@@ -2947,11 +2952,13 @@ static struct ndmsg *neigh_valid_get_req(const struct nlmsghdr *nlh,
        }
 
        for (i = 0; i <= NDA_MAX; ++i) {
-               if (!tb[i])
-                       continue;
-
                switch (i) {
                case NDA_DST:
+                       if (!tb[i]) {
+                               NL_SET_ERR_ATTR_MISS(extack, NULL, NDA_DST);
+                               return ERR_PTR(-EINVAL);
+                       }
+
                        if (nla_len(tb[i]) != (int)(*tbl)->key_len) {
                                NL_SET_ERR_MSG(extack, "Invalid network address in neighbor get request");
                                return ERR_PTR(-EINVAL);
@@ -2959,6 +2966,9 @@ static struct ndmsg *neigh_valid_get_req(const struct nlmsghdr *nlh,
                        *dst = nla_data(tb[i]);
                        break;
                default:
+                       if (!tb[i])
+                               continue;
+
                        NL_SET_ERR_MSG(extack, "Unsupported attribute in neighbor get request");
                        return ERR_PTR(-EINVAL);
                }
@@ -3051,11 +3061,6 @@ static int neigh_get(struct sk_buff *in_skb, struct nlmsghdr *nlh,
                }
        }
 
-       if (!dst) {
-               NL_SET_ERR_MSG(extack, "Network address not specified");
-               return -EINVAL;
-       }
-
        if (ndm->ndm_flags & NTF_PROXY) {
                struct pneigh_entry *pn;
 
@@ -3068,11 +3073,6 @@ static int neigh_get(struct sk_buff *in_skb, struct nlmsghdr *nlh,
                                        nlh->nlmsg_seq, tbl);
        }
 
-       if (!dev) {
-               NL_SET_ERR_MSG(extack, "No device specified");
-               return -EINVAL;
-       }
-
        neigh = neigh_lookup(tbl, dst, dev);
        if (!neigh) {
                NL_SET_ERR_MSG(extack, "Neighbour entry not found");