[PATCH net-next 4/5] net: sched: em_ipt: keep the user-specified nfproto and use it

[Nikolay Aleksandrov]

For NFPROTO_UNSPEC xt_matches there's no way to restrict the matching to a
specific family, in order to do so we record the user-specified family
and later enforce it while doing the match.

Signed-off-by: Nikolay Aleksandrov <niko...@cumulusnetworks.com>
---
 net/sched/em_ipt.c | 23 ++++++++++++++++++-----
 1 file changed, 18 insertions(+), 5 deletions(-)

diff --git a/net/sched/em_ipt.c b/net/sched/em_ipt.c
index d4257f5f1d94..cfb93ce340da 100644
--- 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 +127,16 @@ 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:
+       case NFPROTO_UNSPEC:
+               break;
+       default:
+               return -EINVAL;
+       }
+
        match = get_xt_match(tb);
        if (IS_ERR(match)) {
                pr_err("unable to load match\n");
@@ -140,6 +152,7 @@ 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);
@@ -187,16 +200,16 @@ static int em_ipt_match(struct sk_buff *skb, struct 
tcf_ematch *em,
 
        switch (tc_skb_protocol(skb)) {
        case htons(ETH_P_IP):
-               if (im->match->family != NFPROTO_UNSPEC &&
-                   im->match->family != NFPROTO_IPV4)
+               if (im->nfproto != NFPROTO_UNSPEC &&
+                   im->nfproto != NFPROTO_IPV4)
                        return 0;
                if (!pskb_network_may_pull(skb, sizeof(struct iphdr)))
                        return 0;
                state.pf = NFPROTO_IPV4;
                break;
        case htons(ETH_P_IPV6):
-               if (im->match->family != NFPROTO_UNSPEC &&
-                   im->match->family != NFPROTO_IPV6)
+               if (im->nfproto != NFPROTO_UNSPEC &&
+                   im->nfproto != NFPROTO_IPV6)
                        return 0;
                if (!pskb_network_may_pull(skb, sizeof(struct ipv6hdr)))
                        return 0;
@@ -234,7 +247,7 @@ 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,
-- 
2.20.1