From f6ad6accaa99dfa7462d18687961b8421d707c1e Mon Sep 17 00:00:00 2001 From: Willem de Bruijn Date: Tue, 23 Apr 2019 14:43:49 -0400 Subject: selftests/bpf: expand test_tc_tunnel with SIT encap So far, all BPF tc tunnel testcases encapsulate in the same network protocol. Add an encap testcase that requires updating skb->protocol. The 6in4 tunnel encapsulates an IPv6 packet inside an IPv4 tunnel. Verify that bpf_skb_net_grow correctly updates skb->protocol to select the right protocol handler in __netif_receive_skb_core. The BPF program should also manually update the link layer header to encode the right network protocol. Changes v1->v2 - improve documentation of non-obvious logic Signed-off-by: Willem de Bruijn Tested-by: Alan Maguire Acked-by: Yonghong Song Signed-off-by: Daniel Borkmann --- tools/testing/selftests/bpf/progs/test_tc_tunnel.c | 64 ++++++++++++++++++++-- 1 file changed, 60 insertions(+), 4 deletions(-) (limited to 'tools/testing/selftests/bpf/progs') diff --git a/tools/testing/selftests/bpf/progs/test_tc_tunnel.c b/tools/testing/selftests/bpf/progs/test_tc_tunnel.c index ab56a6a72b7a..74370e7e286d 100644 --- a/tools/testing/selftests/bpf/progs/test_tc_tunnel.c +++ b/tools/testing/selftests/bpf/progs/test_tc_tunnel.c @@ -77,17 +77,52 @@ static __always_inline int encap_ipv4(struct __sk_buff *skb, __u8 encap_proto, struct v4hdr h_outer; struct tcphdr tcph; int olen, l2_len; + int tcp_off; __u64 flags; - if (bpf_skb_load_bytes(skb, ETH_HLEN, &iph_inner, - sizeof(iph_inner)) < 0) - return TC_ACT_OK; + /* Most tests encapsulate a packet into a tunnel with the same + * network protocol, and derive the outer header fields from + * the inner header. + * + * The 6in4 case tests different inner and outer protocols. As + * the inner is ipv6, but the outer expects an ipv4 header as + * input, manually build a struct iphdr based on the ipv6hdr. + */ + if (encap_proto == IPPROTO_IPV6) { + const __u32 saddr = (192 << 24) | (168 << 16) | (1 << 8) | 1; + const __u32 daddr = (192 << 24) | (168 << 16) | (1 << 8) | 2; + struct ipv6hdr iph6_inner; + + /* Read the IPv6 header */ + if (bpf_skb_load_bytes(skb, ETH_HLEN, &iph6_inner, + sizeof(iph6_inner)) < 0) + return TC_ACT_OK; + + /* Derive the IPv4 header fields from the IPv6 header */ + memset(&iph_inner, 0, sizeof(iph_inner)); + iph_inner.version = 4; + iph_inner.ihl = 5; + iph_inner.tot_len = bpf_htons(sizeof(iph6_inner) + + bpf_ntohs(iph6_inner.payload_len)); + iph_inner.ttl = iph6_inner.hop_limit - 1; + iph_inner.protocol = iph6_inner.nexthdr; + iph_inner.saddr = __bpf_constant_htonl(saddr); + iph_inner.daddr = __bpf_constant_htonl(daddr); + + tcp_off = sizeof(iph6_inner); + } else { + if (bpf_skb_load_bytes(skb, ETH_HLEN, &iph_inner, + sizeof(iph_inner)) < 0) + return TC_ACT_OK; + + tcp_off = sizeof(iph_inner); + } /* filter only packets we want */ if (iph_inner.ihl != 5 || iph_inner.protocol != IPPROTO_TCP) return TC_ACT_OK; - if (bpf_skb_load_bytes(skb, ETH_HLEN + sizeof(iph_inner), + if (bpf_skb_load_bytes(skb, ETH_HLEN + tcp_off, &tcph, sizeof(tcph)) < 0) return TC_ACT_OK; @@ -129,6 +164,7 @@ static __always_inline int encap_ipv4(struct __sk_buff *skb, __u8 encap_proto, l2_len); break; case IPPROTO_IPIP: + case IPPROTO_IPV6: break; default: return TC_ACT_OK; @@ -164,6 +200,17 @@ static __always_inline int encap_ipv4(struct __sk_buff *skb, __u8 encap_proto, BPF_F_INVALIDATE_HASH) < 0) return TC_ACT_SHOT; + /* if changing outer proto type, update eth->h_proto */ + if (encap_proto == IPPROTO_IPV6) { + struct ethhdr eth; + + if (bpf_skb_load_bytes(skb, 0, ð, sizeof(eth)) < 0) + return TC_ACT_SHOT; + eth.h_proto = bpf_htons(ETH_P_IP); + if (bpf_skb_store_bytes(skb, 0, ð, sizeof(eth), 0) < 0) + return TC_ACT_SHOT; + } + return TC_ACT_OK; } @@ -325,6 +372,15 @@ int __encap_udp_eth(struct __sk_buff *skb) return TC_ACT_OK; } +SEC("encap_sit_none") +int __encap_sit_none(struct __sk_buff *skb) +{ + if (skb->protocol == __bpf_constant_htons(ETH_P_IPV6)) + return encap_ipv4(skb, IPPROTO_IPV6, ETH_P_IP); + else + return TC_ACT_OK; +} + SEC("encap_ip6tnl_none") int __encap_ip6tnl_none(struct __sk_buff *skb) { -- cgit v1.2.3-59-g8ed1b