Messages in this thread Patch in this message | | | From | menglong8.dong@gmail ... | Subject | [PATCH net-next v2 8/9] net: tcp: add skb drop reasons to tcp tw code path | Date | Tue, 17 May 2022 16:10:07 +0800 |
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From: Menglong Dong <imagedong@tencent.com>
In order to get the reasons of skb drops, add a function argument of type 'enum skb_drop_reason *reason' to tcp_timewait_state_process().
In the origin code, all packets to time-wait socket are treated as dropping with kfree_skb(), which can make users confused. Therefore, we use consume_skb() for the skbs that are 'good'. We can check the value of 'reason' to decide use kfree_skb() or consume_skb().
The new reason 'TIMEWAIT' is added for the case that the skb is dropped as the socket in time-wait state.
Reviewed-by: Jiang Biao <benbjiang@tencent.com> Reviewed-by: Hao Peng <flyingpeng@tencent.com> Signed-off-by: Menglong Dong <imagedong@tencent.com> --- v2: - skb is not freed on TCP_TW_ACK and 'ret' is not initizalized, fix it (Eric Dumazet) --- include/linux/skbuff.h | 5 +++++ include/net/tcp.h | 7 ++++--- net/ipv4/tcp_ipv4.c | 9 ++++++++- net/ipv4/tcp_minisocks.c | 24 ++++++++++++++++++++---- net/ipv6/tcp_ipv6.c | 9 ++++++++- 5 files changed, 45 insertions(+), 9 deletions(-)
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index 4578bbab5a3e..8d18fc5a5af6 100644 --- a/include/linux/skbuff.h +++ b/include/linux/skbuff.h @@ -560,6 +560,10 @@ struct sk_buff; * SKB_DROP_REASON_TCP_REQQFULLDROP * request queue of the listen socket is full, corresponding to * LINUX_MIB_TCPREQQFULLDROP + * + * SKB_DROP_REASON_TIMEWAIT + * socket is in time-wait state and all packet that received will + * be treated as 'drop', except a good 'SYN' packet */ #define __DEFINE_SKB_DROP_REASON(FN) \ FN(NOT_SPECIFIED) \ @@ -631,6 +635,7 @@ struct sk_buff; FN(TCP_ABORTONDATA) \ FN(LISTENOVERFLOWS) \ FN(TCP_REQQFULLDROP) \ + FN(TIMEWAIT) \ FN(MAX) /* The reason of skb drop, which is used in kfree_skb_reason(). diff --git a/include/net/tcp.h b/include/net/tcp.h index 082dd0627e2e..88217b8d95ac 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -380,9 +380,10 @@ enum tcp_tw_status { }; -enum tcp_tw_status tcp_timewait_state_process(struct inet_timewait_sock *tw, - struct sk_buff *skb, - const struct tcphdr *th); +enum tcp_tw_status +tcp_timewait_state_process(struct inet_timewait_sock *tw, struct sk_buff *skb, + const struct tcphdr *th, + enum skb_drop_reason *reason); struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb, struct request_sock *req, bool fastopen, bool *lost_race); diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c index 708f92b03f42..3c163b54b0f8 100644 --- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -2134,7 +2134,8 @@ int tcp_v4_rcv(struct sk_buff *skb) inet_twsk_put(inet_twsk(sk)); goto csum_error; } - switch (tcp_timewait_state_process(inet_twsk(sk), skb, th)) { + switch (tcp_timewait_state_process(inet_twsk(sk), skb, th, + &drop_reason)) { case TCP_TW_SYN: { struct sock *sk2 = inet_lookup_listener(dev_net(skb->dev), &tcp_hashinfo, skb, @@ -2150,11 +2151,17 @@ int tcp_v4_rcv(struct sk_buff *skb) refcounted = false; goto process; } + /* TCP_FLAGS or NO_SOCKET? */ + SKB_DR_SET(drop_reason, TCP_FLAGS); } /* to ACK */ fallthrough; case TCP_TW_ACK: tcp_v4_timewait_ack(sk, skb); + if (!drop_reason) { + consume_skb(skb); + return 0; + } break; case TCP_TW_RST: tcp_v4_send_reset(sk, skb); diff --git a/net/ipv4/tcp_minisocks.c b/net/ipv4/tcp_minisocks.c index 1a21018f6f64..329724118b7f 100644 --- a/net/ipv4/tcp_minisocks.c +++ b/net/ipv4/tcp_minisocks.c @@ -83,13 +83,15 @@ tcp_timewait_check_oow_rate_limit(struct inet_timewait_sock *tw, */ enum tcp_tw_status tcp_timewait_state_process(struct inet_timewait_sock *tw, struct sk_buff *skb, - const struct tcphdr *th) + const struct tcphdr *th, + enum skb_drop_reason *reason) { struct tcp_options_received tmp_opt; struct tcp_timewait_sock *tcptw = tcp_twsk((struct sock *)tw); bool paws_reject = false; tmp_opt.saw_tstamp = 0; + *reason = SKB_DROP_REASON_NOT_SPECIFIED; if (th->doff > (sizeof(*th) >> 2) && tcptw->tw_ts_recent_stamp) { tcp_parse_options(twsk_net(tw), skb, &tmp_opt, 0, NULL); @@ -113,11 +115,16 @@ tcp_timewait_state_process(struct inet_timewait_sock *tw, struct sk_buff *skb, return tcp_timewait_check_oow_rate_limit( tw, skb, LINUX_MIB_TCPACKSKIPPEDFINWAIT2); - if (th->rst) + if (th->rst) { + SKB_DR_SET(*reason, TCP_RESET); goto kill; + } - if (th->syn && !before(TCP_SKB_CB(skb)->seq, tcptw->tw_rcv_nxt)) + if (th->syn && !before(TCP_SKB_CB(skb)->seq, + tcptw->tw_rcv_nxt)) { + SKB_DR_SET(*reason, TCP_FLAGS); return TCP_TW_RST; + } /* Dup ACK? */ if (!th->ack || @@ -143,6 +150,9 @@ tcp_timewait_state_process(struct inet_timewait_sock *tw, struct sk_buff *skb, } inet_twsk_reschedule(tw, TCP_TIMEWAIT_LEN); + + /* skb should be free normally on this case. */ + *reason = SKB_NOT_DROPPED_YET; return TCP_TW_ACK; } @@ -174,6 +184,7 @@ tcp_timewait_state_process(struct inet_timewait_sock *tw, struct sk_buff *skb, * protocol bug yet. */ if (twsk_net(tw)->ipv4.sysctl_tcp_rfc1337 == 0) { + SKB_DR_SET(*reason, TCP_RESET); kill: inet_twsk_deschedule_put(tw); return TCP_TW_SUCCESS; @@ -216,11 +227,14 @@ tcp_timewait_state_process(struct inet_timewait_sock *tw, struct sk_buff *skb, if (isn == 0) isn++; TCP_SKB_CB(skb)->tcp_tw_isn = isn; + *reason = SKB_NOT_DROPPED_YET; return TCP_TW_SYN; } - if (paws_reject) + if (paws_reject) { + SKB_DR_SET(*reason, TCP_RFC7323_PAWS); __NET_INC_STATS(twsk_net(tw), LINUX_MIB_PAWSESTABREJECTED); + } if (!th->rst) { /* In this case we must reset the TIMEWAIT timer. @@ -232,9 +246,11 @@ tcp_timewait_state_process(struct inet_timewait_sock *tw, struct sk_buff *skb, if (paws_reject || th->ack) inet_twsk_reschedule(tw, TCP_TIMEWAIT_LEN); + SKB_DR_OR(*reason, TIMEWAIT); return tcp_timewait_check_oow_rate_limit( tw, skb, LINUX_MIB_TCPACKSKIPPEDTIMEWAIT); } + SKB_DR_SET(*reason, TCP_RESET); inet_twsk_put(tw); return TCP_TW_SUCCESS; } diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c index 27c51991bd54..132b27763229 100644 --- a/net/ipv6/tcp_ipv6.c +++ b/net/ipv6/tcp_ipv6.c @@ -1772,6 +1772,7 @@ INDIRECT_CALLABLE_SCOPE int tcp_v6_rcv(struct sk_buff *skb) } discard_it: + SKB_DR_OR(drop_reason, NOT_SPECIFIED); kfree_skb_reason(skb, drop_reason); return 0; @@ -1795,7 +1796,8 @@ INDIRECT_CALLABLE_SCOPE int tcp_v6_rcv(struct sk_buff *skb) goto csum_error; } - switch (tcp_timewait_state_process(inet_twsk(sk), skb, th)) { + switch (tcp_timewait_state_process(inet_twsk(sk), skb, th, + &drop_reason)) { case TCP_TW_SYN: { struct sock *sk2; @@ -1815,11 +1817,16 @@ INDIRECT_CALLABLE_SCOPE int tcp_v6_rcv(struct sk_buff *skb) refcounted = false; goto process; } + SKB_DR_SET(drop_reason, TCP_FLAGS); } /* to ACK */ fallthrough; case TCP_TW_ACK: tcp_v6_timewait_ack(sk, skb); + if (!drop_reason) { + consume_skb(skb); + return 0; + } break; case TCP_TW_RST: tcp_v6_send_reset(sk, skb); -- 2.36.1
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