From e7ed11ee945438b737e2ae2370e35591e16ec371 Mon Sep 17 00:00:00 2001 From: Yousuk Seung Date: Wed, 20 Jan 2021 12:41:55 -0800 Subject: [PATCH] tcp: add TTL to SCM_TIMESTAMPING_OPT_STATS This patch adds TCP_NLA_TTL to SCM_TIMESTAMPING_OPT_STATS that exports the time-to-live or hop limit of the latest incoming packet with SCM_TSTAMP_ACK. The value exported may not be from the packet that acks the sequence when incoming packets are aggregated. Exporting the time-to-live or hop limit value of incoming packets helps to estimate the hop count of the path of the flow that may change over time. Signed-off-by: Yousuk Seung Signed-off-by: Eric Dumazet Signed-off-by: Neal Cardwell Link: https://lore.kernel.org/r/20210120204155.552275-1-ysseung@google.com Signed-off-by: Jakub Kicinski --- include/linux/skbuff.h | 2 +- include/linux/tcp.h | 3 ++- include/uapi/linux/tcp.h | 1 + net/core/dev.c | 2 +- net/core/skbuff.c | 6 ++++-- net/ipv4/tcp.c | 18 +++++++++++++++++- net/ipv4/tcp_input.c | 16 ++++++++-------- 7 files changed, 34 insertions(+), 14 deletions(-) diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index 186dad2..9313b5a 100644 --- a/include/linux/skbuff.h +++ b/include/linux/skbuff.h @@ -3859,7 +3859,7 @@ static inline bool skb_defer_rx_timestamp(struct sk_buff *skb) void skb_complete_tx_timestamp(struct sk_buff *skb, struct skb_shared_hwtstamps *hwtstamps); -void __skb_tstamp_tx(struct sk_buff *orig_skb, +void __skb_tstamp_tx(struct sk_buff *orig_skb, const struct sk_buff *ack_skb, struct skb_shared_hwtstamps *hwtstamps, struct sock *sk, int tstype); diff --git a/include/linux/tcp.h b/include/linux/tcp.h index 2f87377..48d8a36 100644 --- a/include/linux/tcp.h +++ b/include/linux/tcp.h @@ -496,7 +496,8 @@ static inline u32 tcp_saved_syn_len(const struct saved_syn *saved_syn) } struct sk_buff *tcp_get_timestamping_opt_stats(const struct sock *sk, - const struct sk_buff *orig_skb); + const struct sk_buff *orig_skb, + const struct sk_buff *ack_skb); static inline u16 tcp_mss_clamp(const struct tcp_sock *tp, u16 mss) { diff --git a/include/uapi/linux/tcp.h b/include/uapi/linux/tcp.h index 768e93b..16dfa40 100644 --- a/include/uapi/linux/tcp.h +++ b/include/uapi/linux/tcp.h @@ -314,6 +314,7 @@ enum { TCP_NLA_TIMEOUT_REHASH, /* Timeout-triggered rehash attempts */ TCP_NLA_BYTES_NOTSENT, /* Bytes in write queue not yet sent */ TCP_NLA_EDT, /* Earliest departure time (CLOCK_MONOTONIC) */ + TCP_NLA_TTL, /* TTL or hop limit of a packet received */ }; /* for TCP_MD5SIG socket option */ diff --git a/net/core/dev.c b/net/core/dev.c index d9ce02e..6df3f1b 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -4084,7 +4084,7 @@ static int __dev_queue_xmit(struct sk_buff *skb, struct net_device *sb_dev) skb_reset_mac_header(skb); if (unlikely(skb_shinfo(skb)->tx_flags & SKBTX_SCHED_TSTAMP)) - __skb_tstamp_tx(skb, NULL, skb->sk, SCM_TSTAMP_SCHED); + __skb_tstamp_tx(skb, NULL, NULL, skb->sk, SCM_TSTAMP_SCHED); /* Disable soft irqs for various locks below. Also * stops preemption for RCU. diff --git a/net/core/skbuff.c b/net/core/skbuff.c index 145503d..2af12f7 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -4721,6 +4721,7 @@ err: EXPORT_SYMBOL_GPL(skb_complete_tx_timestamp); void __skb_tstamp_tx(struct sk_buff *orig_skb, + const struct sk_buff *ack_skb, struct skb_shared_hwtstamps *hwtstamps, struct sock *sk, int tstype) { @@ -4743,7 +4744,8 @@ void __skb_tstamp_tx(struct sk_buff *orig_skb, if ((sk->sk_tsflags & SOF_TIMESTAMPING_OPT_STATS) && sk->sk_protocol == IPPROTO_TCP && sk->sk_type == SOCK_STREAM) { - skb = tcp_get_timestamping_opt_stats(sk, orig_skb); + skb = tcp_get_timestamping_opt_stats(sk, orig_skb, + ack_skb); opt_stats = true; } else #endif @@ -4772,7 +4774,7 @@ EXPORT_SYMBOL_GPL(__skb_tstamp_tx); void skb_tstamp_tx(struct sk_buff *orig_skb, struct skb_shared_hwtstamps *hwtstamps) { - return __skb_tstamp_tx(orig_skb, hwtstamps, orig_skb->sk, + return __skb_tstamp_tx(orig_skb, NULL, hwtstamps, orig_skb->sk, SCM_TSTAMP_SND); } EXPORT_SYMBOL_GPL(skb_tstamp_tx); diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index 856ae51..a1a17b6 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -3767,11 +3767,24 @@ static size_t tcp_opt_stats_get_size(void) nla_total_size(sizeof(u16)) + /* TCP_NLA_TIMEOUT_REHASH */ nla_total_size(sizeof(u32)) + /* TCP_NLA_BYTES_NOTSENT */ nla_total_size_64bit(sizeof(u64)) + /* TCP_NLA_EDT */ + nla_total_size(sizeof(u8)) + /* TCP_NLA_TTL */ 0; } +/* Returns TTL or hop limit of an incoming packet from skb. */ +static u8 tcp_skb_ttl_or_hop_limit(const struct sk_buff *skb) +{ + if (skb->protocol == htons(ETH_P_IP)) + return ip_hdr(skb)->ttl; + else if (skb->protocol == htons(ETH_P_IPV6)) + return ipv6_hdr(skb)->hop_limit; + else + return 0; +} + struct sk_buff *tcp_get_timestamping_opt_stats(const struct sock *sk, - const struct sk_buff *orig_skb) + const struct sk_buff *orig_skb, + const struct sk_buff *ack_skb) { const struct tcp_sock *tp = tcp_sk(sk); struct sk_buff *stats; @@ -3827,6 +3840,9 @@ struct sk_buff *tcp_get_timestamping_opt_stats(const struct sock *sk, max_t(int, 0, tp->write_seq - tp->snd_nxt)); nla_put_u64_64bit(stats, TCP_NLA_EDT, orig_skb->skb_mstamp_ns, TCP_NLA_PAD); + if (ack_skb) + nla_put_u8(stats, TCP_NLA_TTL, + tcp_skb_ttl_or_hop_limit(ack_skb)); return stats; } diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index a7dfca0..d4f66ab 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -3145,7 +3145,7 @@ static u32 tcp_tso_acked(struct sock *sk, struct sk_buff *skb) } static void tcp_ack_tstamp(struct sock *sk, struct sk_buff *skb, - u32 prior_snd_una) + const struct sk_buff *ack_skb, u32 prior_snd_una) { const struct skb_shared_info *shinfo; @@ -3157,7 +3157,7 @@ static void tcp_ack_tstamp(struct sock *sk, struct sk_buff *skb, if (!before(shinfo->tskey, prior_snd_una) && before(shinfo->tskey, tcp_sk(sk)->snd_una)) { tcp_skb_tsorted_save(skb) { - __skb_tstamp_tx(skb, NULL, sk, SCM_TSTAMP_ACK); + __skb_tstamp_tx(skb, ack_skb, NULL, sk, SCM_TSTAMP_ACK); } tcp_skb_tsorted_restore(skb); } } @@ -3166,8 +3166,8 @@ static void tcp_ack_tstamp(struct sock *sk, struct sk_buff *skb, * is before the ack sequence we can discard it as it's confirmed to have * arrived at the other end. */ -static int tcp_clean_rtx_queue(struct sock *sk, u32 prior_fack, - u32 prior_snd_una, +static int tcp_clean_rtx_queue(struct sock *sk, const struct sk_buff *ack_skb, + u32 prior_fack, u32 prior_snd_una, struct tcp_sacktag_state *sack, bool ece_ack) { const struct inet_connection_sock *icsk = inet_csk(sk); @@ -3256,7 +3256,7 @@ static int tcp_clean_rtx_queue(struct sock *sk, u32 prior_fack, if (!fully_acked) break; - tcp_ack_tstamp(sk, skb, prior_snd_una); + tcp_ack_tstamp(sk, skb, ack_skb, prior_snd_una); next = skb_rb_next(skb); if (unlikely(skb == tp->retransmit_skb_hint)) @@ -3274,7 +3274,7 @@ static int tcp_clean_rtx_queue(struct sock *sk, u32 prior_fack, tp->snd_up = tp->snd_una; if (skb) { - tcp_ack_tstamp(sk, skb, prior_snd_una); + tcp_ack_tstamp(sk, skb, ack_skb, prior_snd_una); if (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED) flag |= FLAG_SACK_RENEGING; } @@ -3809,8 +3809,8 @@ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag) goto no_queue; /* See if we can take anything off of the retransmit queue. */ - flag |= tcp_clean_rtx_queue(sk, prior_fack, prior_snd_una, &sack_state, - flag & FLAG_ECE); + flag |= tcp_clean_rtx_queue(sk, skb, prior_fack, prior_snd_una, + &sack_state, flag & FLAG_ECE); tcp_rack_update_reo_wnd(sk, &rs); -- 2.7.4