bpf: Fix IPv6 dport byte order in bpf_sk_lookup_udp

Lookup functions in sk_lookup have different expectations about byte
order of provided arguments.

Specifically __inet_lookup, __udp4_lib_lookup and __udp6_lib_lookup
expect dport to be in network byte order and do ntohs(dport) internally.

At the same time __inet6_lookup expects dport to be in host byte order
and correspondingly name the argument hnum.

sk_lookup works correctly with __inet_lookup, __udp4_lib_lookup and
__inet6_lookup with regard to dport. But in __udp6_lib_lookup case it
uses host instead of expected network byte order. It makes result
returned by bpf_sk_lookup_udp for IPv6 incorrect.

The patch fixes byte order of dport passed to __udp6_lib_lookup.

Originally sk_lookup properly handled UDPv6, but not TCPv6. 5ef0ae84f02a
fixes TCPv6 but breaks UDPv6.

Fixes: 5ef0ae84f02a ("bpf: Fix IPv6 dport byte-order in bpf_sk_lookup")
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Acked-by: Joe Stringer <joe@wand.net.nz>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

diff --git a/net/core/filter.c b/net/core/filter.c
index e521c5ebc7d11cdfdcc10307ad973bcac2d1602a..9a1327eb25faf2c73a37d253f88b19c6b92414d6 100644 (file)
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -4852,18 +4852,17 @@ static struct sock *sk_lookup(struct net *net, struct bpf_sock_tuple *tuple,
        } else {
                struct in6_addr *src6 = (struct in6_addr *)&tuple->ipv6.saddr;
                struct in6_addr *dst6 = (struct in6_addr *)&tuple->ipv6.daddr;
-               u16 hnum = ntohs(tuple->ipv6.dport);
                int sdif = inet6_sdif(skb);
 
                if (proto == IPPROTO_TCP)
                        sk = __inet6_lookup(net, &tcp_hashinfo, skb, 0,
                                            src6, tuple->ipv6.sport,
-                                           dst6, hnum,
+                                           dst6, ntohs(tuple->ipv6.dport),
                                            dif, sdif, &refcounted);
                else if (likely(ipv6_bpf_stub))
                        sk = ipv6_bpf_stub->udp6_lib_lookup(net,
                                                            src6, tuple->ipv6.sport,
-                                                           dst6, hnum,
+                                                           dst6, tuple->ipv6.dport,
                                                            dif, sdif,
                                                            &udp_table, skb);
 #endif