net: sched: em_ipt: keep the user-specified nfproto and dump it

If we dump NFPROTO_UNSPEC as nfproto user-space libxtables can't handle
it and would exit with an error like:
"libxtables: unhandled NFPROTO in xtables_set_nfproto"
In order to avoid the error return the user-specified nfproto. If we
don't record it then the match family is used which can be
NFPROTO_UNSPEC. Even if we add support to mask NFPROTO_UNSPEC in
iproute2 we have to be compatible with older versions which would be
also be allowed to add NFPROTO_UNSPEC matches (e.g. addrtype after the
last patch).

v3: don't use the user nfproto for matching, only for dumping the rule,
    also don't allow the nfproto to be unspecified (explained above)
v2: adjust changes to missing patch, was patch 04 in v1

Signed-off-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/sched/em_ipt.c b/net/sched/em_ipt.c
index fd7f5b288c311e6e8a8343b9e63c050887884330..3c356d6f719aab9effe168d49dbfc2a0172731a6 100644 (file)
--- a/net/sched/em_ipt.c
+++ b/net/sched/em_ipt.c
@@ -21,6 +21,7 @@
 struct em_ipt_match {
        const struct xt_match *match;
        u32 hook;
+       u8 nfproto;
        u8 match_data[0] __aligned(8);
 };
 
@@ -115,6 +116,7 @@ static int em_ipt_change(struct net *net, void *data, int data_len,
        struct em_ipt_match *im = NULL;
        struct xt_match *match;
        int mdata_len, ret;
+       u8 nfproto;
 
        ret = nla_parse_deprecated(tb, TCA_EM_IPT_MAX, data, data_len,
                                   em_ipt_policy, NULL);
@@ -125,6 +127,15 @@ static int em_ipt_change(struct net *net, void *data, int data_len,
            !tb[TCA_EM_IPT_MATCH_DATA] || !tb[TCA_EM_IPT_NFPROTO])
                return -EINVAL;
 
+       nfproto = nla_get_u8(tb[TCA_EM_IPT_NFPROTO]);
+       switch (nfproto) {
+       case NFPROTO_IPV4:
+       case NFPROTO_IPV6:
+               break;
+       default:
+               return -EINVAL;
+       }
+
        match = get_xt_match(tb);
        if (IS_ERR(match)) {
                pr_err("unable to load match\n");
@@ -140,6 +151,7 @@ static int em_ipt_change(struct net *net, void *data, int data_len,
 
        im->match = match;
        im->hook = nla_get_u32(tb[TCA_EM_IPT_HOOK]);
+       im->nfproto = nfproto;
        nla_memcpy(im->match_data, tb[TCA_EM_IPT_MATCH_DATA], mdata_len);
 
        ret = check_match(net, im, mdata_len);
@@ -231,7 +243,7 @@ static int em_ipt_dump(struct sk_buff *skb, struct tcf_ematch *em)
                return -EMSGSIZE;
        if (nla_put_u8(skb, TCA_EM_IPT_MATCH_REVISION, im->match->revision) < 0)
                return -EMSGSIZE;
-       if (nla_put_u8(skb, TCA_EM_IPT_NFPROTO, im->match->family) < 0)
+       if (nla_put_u8(skb, TCA_EM_IPT_NFPROTO, im->nfproto) < 0)
                return -EMSGSIZE;
        if (nla_put(skb, TCA_EM_IPT_MATCH_DATA,
                    im->match->usersize ?: im->match->matchsize,