On Wed, Nov 07, 2018 at 01:36:07PM -0800, Andrey Ignatov wrote:
> 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 <r...@fb.com>
Good catch.
Acked-by: Martin KaFai Lau <ka...@fb.com>
> ---
> net/core/filter.c | 5 ++---
> 1 file changed, 2 insertions(+), 3 deletions(-)
>
> diff --git a/net/core/filter.c b/net/core/filter.c
> index e521c5ebc7d1..9a1327eb25fa 100644
> --- 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
> --
> 2.17.1
>
