Messages in this thread Patch in this message | | | From | menglong8.dong@gmail ... | Subject | [PATCH net-next v4 6/8] net: tcp: add skb drop reasons to tcp tw code path | Date | Fri, 17 Jun 2022 18:05:12 +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> Reported-by: Eric Dumazet <edumazet@google.com> --- v2: - skb is not freed on TCP_TW_ACK and 'ret' is not initizalized, fix it (Eric Dumazet) --- include/net/dropreason.h | 6 ++++++ include/net/tcp.h | 7 ++++--- net/ipv4/tcp_ipv4.c | 8 ++++++-- net/ipv4/tcp_minisocks.c | 23 +++++++++++++++++++---- net/ipv6/tcp_ipv6.c | 7 +++++-- 5 files changed, 40 insertions(+), 11 deletions(-)
diff --git a/include/net/dropreason.h b/include/net/dropreason.h index 74512e60ab12..90cdb7321926 100644 --- a/include/net/dropreason.h +++ b/include/net/dropreason.h @@ -246,6 +246,12 @@ enum skb_drop_reason { * socket is full, corresponding to LINUX_MIB_TCPREQQFULLDROP */ SKB_DROP_REASON_TCP_REQQFULLDROP, + /** + * @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 + */ + SKB_DROP_REASON_TIMEWAIT, /** * @SKB_DROP_REASON_MAX: the maximum of drop reason, which shouldn't be * used as a real 'reason' diff --git a/include/net/tcp.h b/include/net/tcp.h index 16da150150c3..1a88fabf0cce 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -379,9 +379,10 @@ 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 e1064273062a..f2ed9763d504 100644 --- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -1975,6 +1975,7 @@ int tcp_v4_rcv(struct sk_buff *skb) reqsk_put(req); goto discard_it; } + drop_reason = SKB_DROP_REASON_NOT_SPECIFIED; if (tcp_checksum_complete(skb)) { reqsk_put(req); goto csum_error; @@ -2049,6 +2050,7 @@ int tcp_v4_rcv(struct sk_buff *skb) if (drop_reason) goto discard_and_relse; + drop_reason = SKB_DROP_REASON_NOT_SPECIFIED; nf_reset_ct(skb); if (tcp_filter(sk, skb)) { @@ -2104,7 +2106,6 @@ int tcp_v4_rcv(struct sk_buff *skb) } discard_it: - SKB_DR_OR(drop_reason, NOT_SPECIFIED); /* Discard frame. */ kfree_skb_reason(skb, drop_reason); return 0; @@ -2128,7 +2129,8 @@ 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, @@ -2144,6 +2146,8 @@ 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; diff --git a/net/ipv4/tcp_minisocks.c b/net/ipv4/tcp_minisocks.c index 6854bb1fb32b..dd640574d00f 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; @@ -219,8 +230,10 @@ tcp_timewait_state_process(struct inet_timewait_sock *tw, struct sk_buff *skb, 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 +245,11 @@ 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 dbe356a166c5..9aeb0a7b7c12 100644 --- a/net/ipv6/tcp_ipv6.c +++ b/net/ipv6/tcp_ipv6.c @@ -1644,6 +1644,7 @@ INDIRECT_CALLABLE_SCOPE int tcp_v6_rcv(struct sk_buff *skb) reqsk_put(req); goto discard_it; } + drop_reason = SKB_DROP_REASON_NOT_SPECIFIED; if (tcp_checksum_complete(skb)) { reqsk_put(req); goto csum_error; @@ -1715,6 +1716,7 @@ INDIRECT_CALLABLE_SCOPE int tcp_v6_rcv(struct sk_buff *skb) if (drop_reason) goto discard_and_relse; + drop_reason = SKB_DROP_REASON_NOT_SPECIFIED; if (tcp_filter(sk, skb)) { drop_reason = SKB_DROP_REASON_SOCKET_FILTER; goto discard_and_relse; @@ -1766,7 +1768,6 @@ 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; @@ -1790,7 +1791,8 @@ 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; @@ -1810,6 +1812,7 @@ 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; -- 2.36.1
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