From b9aaf9a4a6cc2fe436976fd68d215619509f9b02 Mon Sep 17 00:00:00 2001 From: Martin KaFai Lau Date: Thu, 20 Aug 2020 12:01:23 -0700 Subject: [PATCH] BACKPORT: tcp: bpf: Optionally store mac header in TCP_SAVE_SYN This patch is adapted from Eric's patch in an earlier discussion [1]. The TCP_SAVE_SYN currently only stores the network header and tcp header. This patch allows it to optionally store the mac header also if the setsockopt's optval is 2. It requires one more bit for the "save_syn" bit field in tcp_sock. This patch achieves this by moving the syn_smc bit next to the is_mptcp. The syn_smc is currently used with the TCP experimental option. Since syn_smc is only used when CONFIG_SMC is enabled, this patch also puts the "IS_ENABLED(CONFIG_SMC)" around it like the is_mptcp did with "IS_ENABLED(CONFIG_MPTCP)". The mac_hdrlen is also stored in the "struct saved_syn" to allow a quick offset from the bpf prog if it chooses to start getting from the network header or the tcp header. [1]: https://lore.kernel.org/netdev/CANn89iLJNWh6bkH7DNhy_kmcAexuUCccqERqe7z2QsvPhGrYPQ@mail.gmail.com/ Suggested-by: Eric Dumazet Change-Id: Ib5dd358e17dbc89275dbbdef4eff1fb9fc2c318c Signed-off-by: Martin KaFai Lau Signed-off-by: Alexei Starovoitov Reviewed-by: Eric Dumazet Link: https://lore.kernel.org/bpf/20200820190123.2886935-1-kafai@fb.com --- include/linux/tcp.h | 13 ++++++++----- include/net/request_sock.h | 1 + include/uapi/linux/bpf.h | 1 + net/core/filter.c | 29 +++++++++++++++++++++++------ net/ipv4/tcp.c | 3 ++- net/ipv4/tcp_input.c | 14 +++++++++++++- tools/include/uapi/linux/bpf.h | 1 + 7 files changed, 49 insertions(+), 13 deletions(-) diff --git a/include/linux/tcp.h b/include/linux/tcp.h index ca7b8461e234..67d2d7cc0946 100644 --- a/include/linux/tcp.h +++ b/include/linux/tcp.h @@ -241,14 +241,13 @@ struct tcp_sock { repair : 1, frto : 1;/* F-RTO (RFC5682) activated in CA_Loss */ u8 repair_queue; - u8 syn_data:1, /* SYN includes data */ + u8 save_syn:2, /* Save headers of SYN packet */ + syn_data:1, /* SYN includes data */ syn_fastopen:1, /* SYN includes Fast Open option */ syn_fastopen_exp:1,/* SYN includes Fast Open exp. option */ syn_fastopen_ch:1, /* Active TFO re-enabling probe */ syn_data_acked:1,/* data in SYN is acked by SYN-ACK */ - save_syn:1, /* Save headers of SYN packet */ - is_cwnd_limited:1,/* forward progress limited by snd_cwnd? */ - syn_smc:1; /* SYN includes SMC */ + is_cwnd_limited:1;/* forward progress limited by snd_cwnd? */ u32 tlp_high_seq; /* snd_nxt at the time of TLP */ u32 tcp_tx_delay; /* delay (in usec) added to TX packets */ @@ -397,6 +396,9 @@ struct tcp_sock { u32 mtu_info; /* We received an ICMP_FRAG_NEEDED / ICMPV6_PKT_TOOBIG * while socket was owned by user. */ +#if IS_ENABLED(CONFIG_SMC) + bool syn_smc; /* SYN includes SMC */ +#endif #ifdef CONFIG_TCP_MD5SIG /* TCP AF-Specific parts; only used by MD5 Signature support so far */ @@ -492,7 +494,8 @@ static inline void tcp_saved_syn_free(struct tcp_sock *tp) static inline u32 tcp_saved_syn_len(const struct saved_syn *saved_syn) { - return saved_syn->network_hdrlen + saved_syn->tcp_hdrlen; + return saved_syn->mac_hdrlen + saved_syn->network_hdrlen + + saved_syn->tcp_hdrlen; } struct sk_buff *tcp_get_timestamping_opt_stats(const struct sock *sk); diff --git a/include/net/request_sock.h b/include/net/request_sock.h index b1b101814ecb..8c99af5ea891 100644 --- a/include/net/request_sock.h +++ b/include/net/request_sock.h @@ -42,6 +42,7 @@ struct request_sock_ops { int inet_rtx_syn_ack(const struct sock *parent, struct request_sock *req); struct saved_syn { + u32 mac_hdrlen; u32 network_hdrlen; u32 tcp_hdrlen; u8 data[]; diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index 7e4e7126dc04..c880ce73fdeb 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -4551,6 +4551,7 @@ enum { */ TCP_BPF_SYN = 1005, /* Copy the TCP header */ TCP_BPF_SYN_IP = 1006, /* Copy the IP[46] and TCP header */ + TCP_BPF_SYN_MAC = 1007, /* Copy the MAC, IP[46], and TCP header */ }; enum { diff --git a/net/core/filter.c b/net/core/filter.c index bc1c5d7a14af..6f41310109a7 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -4724,11 +4724,16 @@ static int bpf_sock_ops_get_syn(struct bpf_sock_ops_kern *bpf_sock, if (optname == TCP_BPF_SYN) { hdr_start = syn_skb->data; ret = tcp_hdrlen(syn_skb); - } else { - /* optname == TCP_BPF_SYN_IP */ + } else if (optname == TCP_BPF_SYN_IP) { hdr_start = skb_network_header(syn_skb); ret = skb_network_header_len(syn_skb) + tcp_hdrlen(syn_skb); + } else { + /* optname == TCP_BPF_SYN_MAC */ + hdr_start = skb_mac_header(syn_skb); + ret = skb_mac_header_len(syn_skb) + + skb_network_header_len(syn_skb) + + tcp_hdrlen(syn_skb); } } else { struct sock *sk = bpf_sock->sk; @@ -4748,13 +4753,25 @@ static int bpf_sock_ops_get_syn(struct bpf_sock_ops_kern *bpf_sock, if (optname == TCP_BPF_SYN) { hdr_start = saved_syn->data + + saved_syn->mac_hdrlen + saved_syn->network_hdrlen; ret = saved_syn->tcp_hdrlen; - } else { - /* optname == TCP_BPF_SYN_IP */ - hdr_start = saved_syn->data; + } else if (optname == TCP_BPF_SYN_IP) { + hdr_start = saved_syn->data + + saved_syn->mac_hdrlen; ret = saved_syn->network_hdrlen + saved_syn->tcp_hdrlen; + } else { + /* optname == TCP_BPF_SYN_MAC */ + + /* TCP_SAVE_SYN may not have saved the mac hdr */ + if (!saved_syn->mac_hdrlen) + return -ENOENT; + + hdr_start = saved_syn->data; + ret = saved_syn->mac_hdrlen + + saved_syn->network_hdrlen + + saved_syn->tcp_hdrlen; } } @@ -4766,7 +4783,7 @@ BPF_CALL_5(bpf_sock_ops_getsockopt, struct bpf_sock_ops_kern *, bpf_sock, int, level, int, optname, char *, optval, int, optlen) { if (IS_ENABLED(CONFIG_INET) && level == SOL_TCP && - optname >= TCP_BPF_SYN && optname <= TCP_BPF_SYN_IP) { + optname >= TCP_BPF_SYN && optname <= TCP_BPF_SYN_MAC) { int ret, copy_len = 0; const u8 *start; diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index 591b5ba9b49c..955a080b6c19 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -3103,7 +3103,8 @@ static int do_tcp_setsockopt(struct sock *sk, int level, break; case TCP_SAVE_SYN: - if (val < 0 || val > 1) + /* 0: disable, 1: enable, 2: start from ether_header */ + if (val < 0 || val > 2) err = -EINVAL; else tp->save_syn = val; diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index 2dd2852108d6..c3041cdf6d7b 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -6723,13 +6723,25 @@ static void tcp_reqsk_record_syn(const struct sock *sk, if (tcp_sk(sk)->save_syn) { u32 len = skb_network_header_len(skb) + tcp_hdrlen(skb); struct saved_syn *saved_syn; + u32 mac_hdrlen; + void *base; + + if (tcp_sk(sk)->save_syn == 2) { /* Save full header. */ + base = skb_mac_header(skb); + mac_hdrlen = skb_mac_header_len(skb); + len += mac_hdrlen; + } else { + base = skb_network_header(skb); + mac_hdrlen = 0; + } saved_syn = kmalloc(struct_size(saved_syn, data, len), GFP_ATOMIC); if (saved_syn) { + saved_syn->mac_hdrlen = mac_hdrlen; saved_syn->network_hdrlen = skb_network_header_len(skb); saved_syn->tcp_hdrlen = tcp_hdrlen(skb); - memcpy(saved_syn->data, skb_network_header(skb), len); + memcpy(saved_syn->data, base, len); req->saved_syn = saved_syn; } } diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h index 8724e726ff13..383eae8067ac 100644 --- a/tools/include/uapi/linux/bpf.h +++ b/tools/include/uapi/linux/bpf.h @@ -4444,6 +4444,7 @@ enum { */ TCP_BPF_SYN = 1005, /* Copy the TCP header */ TCP_BPF_SYN_IP = 1006, /* Copy the IP[46] and TCP header */ + TCP_BPF_SYN_MAC = 1007, /* Copy the MAC, IP[46], and TCP header */ }; enum {