From f7c917ba11a67632a8452ea99fe132f626a7a2cc Mon Sep 17 00:00:00 2001 From: brakmo Date: Fri, 1 Mar 2019 12:38:46 -0800 Subject: bpf: add bpf helper bpf_skb_ecn_set_ce This patch adds a new bpf helper BPF_FUNC_skb_ecn_set_ce "int bpf_skb_ecn_set_ce(struct sk_buff *skb)". It is added to BPF_PROG_TYPE_CGROUP_SKB typed bpf_prog which currently can be attached to the ingress and egress path. The helper is needed because his type of bpf_prog cannot modify the skb directly. This helper is used to set the ECN field of ECN capable IP packets to ce (congestion encountered) in the IPv6 or IPv4 header of the skb. It can be used by a bpf_prog to manage egress or ingress network bandwdith limit per cgroupv2 by inducing an ECN response in the TCP sender. This works best when using DCTCP. Signed-off-by: Lawrence Brakmo Signed-off-by: Martin KaFai Lau Acked-by: Song Liu Signed-off-by: Alexei Starovoitov --- net/core/filter.c | 28 ++++++++++++++++++++++++++++ 1 file changed, 28 insertions(+) (limited to 'net') diff --git a/net/core/filter.c b/net/core/filter.c index 85749f6ec789..558ca72f2254 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -5426,6 +5426,32 @@ static const struct bpf_func_proto bpf_tcp_sock_proto = { .arg1_type = ARG_PTR_TO_SOCK_COMMON, }; +BPF_CALL_1(bpf_skb_ecn_set_ce, struct sk_buff *, skb) +{ + unsigned int iphdr_len; + + if (skb->protocol == cpu_to_be16(ETH_P_IP)) + iphdr_len = sizeof(struct iphdr); + else if (skb->protocol == cpu_to_be16(ETH_P_IPV6)) + iphdr_len = sizeof(struct ipv6hdr); + else + return 0; + + if (skb_headlen(skb) < iphdr_len) + return 0; + + if (skb_cloned(skb) && !skb_clone_writable(skb, iphdr_len)) + return 0; + + return INET_ECN_set_ce(skb); +} + +static const struct bpf_func_proto bpf_skb_ecn_set_ce_proto = { + .func = bpf_skb_ecn_set_ce, + .gpl_only = false, + .ret_type = RET_INTEGER, + .arg1_type = ARG_PTR_TO_CTX, +}; #endif /* CONFIG_INET */ bool bpf_helper_changes_pkt_data(void *func) @@ -5585,6 +5611,8 @@ cg_skb_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) #ifdef CONFIG_INET case BPF_FUNC_tcp_sock: return &bpf_tcp_sock_proto; + case BPF_FUNC_skb_ecn_set_ce: + return &bpf_skb_ecn_set_ce_proto; #endif default: return sk_filter_func_proto(func_id, prog); -- cgit v1.2.3-59-g8ed1b