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Message-Id: <20241015102940.26157-25-chia-yu.chang@nokia-bell-labs.com>
Date: Tue, 15 Oct 2024 12:29:20 +0200
From: chia-yu.chang@...ia-bell-labs.com
To: netdev@...r.kernel.org, ij@...nel.org, ncardwell@...gle.com,
koen.de_schepper@...ia-bell-labs.com, g.white@...leLabs.com,
ingemar.s.johansson@...csson.com, mirja.kuehlewind@...csson.com,
cheshire@...le.com, rs.ietf@....at, Jason_Livingood@...cast.com,
vidhi_goel@...le.com
Cc: Chia-Yu Chang <chia-yu.chang@...ia-bell-labs.com>
Subject: [PATCH net-next 24/44] tcp: accecn: AccECN option failure handling
From: Chia-Yu Chang <chia-yu.chang@...ia-bell-labs.com>
AccECN option may fail in various way, handle these:
- Remove option from SYN/ACK rexmits to handle blackholes
- If no option arrives in SYN/ACK, assume Option is not usable
- If an option arrives later, re-enabled
- If option is zeroed, disable AccECN option processing
Signed-off-by: Ilpo Järvinen <ij@...nel.org>
Signed-off-by: Chia-Yu Chang <chia-yu.chang@...ia-bell-labs.com>
---
include/linux/tcp.h | 6 +++--
include/net/tcp.h | 7 ++++++
net/ipv4/tcp.c | 1 +
net/ipv4/tcp_input.c | 47 +++++++++++++++++++++++++++++++++++-----
net/ipv4/tcp_minisocks.c | 33 ++++++++++++++++++++++++++++
net/ipv4/tcp_output.c | 7 ++++--
6 files changed, 92 insertions(+), 9 deletions(-)
diff --git a/include/linux/tcp.h b/include/linux/tcp.h
index e4aa10fdc032..d817a4d1e17c 100644
--- a/include/linux/tcp.h
+++ b/include/linux/tcp.h
@@ -160,7 +160,8 @@ struct tcp_request_sock {
u8 accecn_ok : 1,
syn_ect_snt: 2,
syn_ect_rcv: 2;
- u8 accecn_fail_mode:4;
+ u8 accecn_fail_mode:4,
+ saw_accecn_opt :2;
u32 txhash;
u32 rcv_isn;
u32 snt_isn;
@@ -387,7 +388,8 @@ struct tcp_sock {
syn_ect_snt:2, /* AccECN ECT memory, only */
syn_ect_rcv:2, /* ... needed durign 3WHS + first seqno */
wait_third_ack:1; /* Need 3rd ACK in simultaneous open for AccECN */
- u8 accecn_fail_mode:4; /* AccECN failure handling */
+ u8 accecn_fail_mode:4, /* AccECN failure handling */
+ saw_accecn_opt:2; /* An AccECN option was seen */
u8 thin_lto : 1,/* Use linear timeouts for thin streams */
fastopen_connect:1, /* FASTOPEN_CONNECT sockopt */
fastopen_no_cookie:1, /* Allow send/recv SYN+data without a cookie */
diff --git a/include/net/tcp.h b/include/net/tcp.h
index b3cbf9a11dbc..18c6f0ada141 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -274,6 +274,12 @@ static inline void tcp_accecn_fail_mode_set(struct tcp_sock *tp, u8 mode)
tp->accecn_fail_mode |= mode;
}
+/* tp->saw_accecn_opt states */
+#define TCP_ACCECN_OPT_NOT_SEEN 0x0
+#define TCP_ACCECN_OPT_EMPTY_SEEN 0x1
+#define TCP_ACCECN_OPT_COUNTER_SEEN 0x2
+#define TCP_ACCECN_OPT_FAIL_SEEN 0x3
+
/* Flags in tp->nonagle */
#define TCP_NAGLE_OFF 1 /* Nagle's algo is disabled */
#define TCP_NAGLE_CORK 2 /* Socket is corked */
@@ -475,6 +481,7 @@ static inline int tcp_accecn_extract_syn_ect(u8 ace)
bool tcp_accecn_validate_syn_feedback(struct sock *sk, u8 ace, u8 sent_ect);
void tcp_accecn_third_ack(struct sock *sk, const struct sk_buff *skb,
u8 syn_ect_snt);
+u8 tcp_accecn_option_init(const struct sk_buff *skb, u8 opt_offset);
void tcp_ecn_received_counters(struct sock *sk, const struct sk_buff *skb,
u32 payload_len);
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index e59fd2cabe03..7ef69b7265eb 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -3339,6 +3339,7 @@ int tcp_disconnect(struct sock *sk, int flags)
tp->delivered_ce = 0;
tp->wait_third_ack = 0;
tp->accecn_fail_mode = 0;
+ tp->saw_accecn_opt = TCP_ACCECN_OPT_NOT_SEEN;
tcp_accecn_init_counters(tp);
tp->prev_ecnfield = 0;
tp->accecn_opt_tstamp = 0;
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 14b9a5e63687..a8669c407978 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -439,8 +439,8 @@ bool tcp_accecn_validate_syn_feedback(struct sock *sk, u8 ace, u8 sent_ect)
}
/* See Table 2 of the AccECN draft */
-static void tcp_ecn_rcv_synack(struct sock *sk, const struct tcphdr *th,
- u8 ip_dsfield)
+static void tcp_ecn_rcv_synack(struct sock *sk, const struct sk_buff *skb,
+ const struct tcphdr *th, u8 ip_dsfield)
{
struct tcp_sock *tp = tcp_sk(sk);
u8 ace = tcp_accecn_ace(th);
@@ -459,7 +459,14 @@ static void tcp_ecn_rcv_synack(struct sock *sk, const struct tcphdr *th,
default:
tcp_ecn_mode_set(tp, TCP_ECN_MODE_ACCECN);
tp->syn_ect_rcv = ip_dsfield & INET_ECN_MASK;
- tp->accecn_opt_demand = 2;
+ if (tp->rx_opt.accecn &&
+ tp->saw_accecn_opt < TCP_ACCECN_OPT_COUNTER_SEEN) {
+ tp->saw_accecn_opt = tcp_accecn_option_init(skb,
+ tp->rx_opt.accecn);
+ if (tp->saw_accecn_opt == TCP_ACCECN_OPT_FAIL_SEEN)
+ tcp_accecn_fail_mode_set(tp, TCP_ACCECN_OPT_FAIL_RECV);
+ tp->accecn_opt_demand = 2;
+ }
if (tcp_accecn_validate_syn_feedback(sk, ace, tp->syn_ect_snt) &&
INET_ECN_is_ce(ip_dsfield)) {
tp->received_ce++;
@@ -574,7 +581,21 @@ static bool tcp_accecn_process_option(struct tcp_sock *tp,
bool order1, res;
unsigned int i;
+ if (tcp_accecn_opt_fail_recv(tp))
+ return false;
+
if (!(flag & FLAG_SLOWPATH) || !tp->rx_opt.accecn) {
+ if (!tp->saw_accecn_opt) {
+ /* Too late to enable after this point due to
+ * potential counter wraps
+ */
+ if (tp->bytes_sent >= (1 << 23) - 1) {
+ tp->saw_accecn_opt = TCP_ACCECN_OPT_FAIL_SEEN;
+ tcp_accecn_fail_mode_set(tp, TCP_ACCECN_OPT_FAIL_RECV);
+ }
+ return false;
+ }
+
if (estimate_ecnfield) {
tp->delivered_ecn_bytes[estimate_ecnfield - 1] += delivered_bytes;
return true;
@@ -588,6 +609,13 @@ static bool tcp_accecn_process_option(struct tcp_sock *tp,
order1 = (ptr[0] == TCPOPT_ACCECN1);
ptr += 2;
+ if (tp->saw_accecn_opt < TCP_ACCECN_OPT_COUNTER_SEEN) {
+ tp->saw_accecn_opt = tcp_accecn_option_init(skb,
+ tp->rx_opt.accecn);
+ if (tp->saw_accecn_opt == TCP_ACCECN_OPT_FAIL_SEEN)
+ tcp_accecn_fail_mode_set(tp, TCP_ACCECN_OPT_FAIL_RECV);
+ }
+
res = !!estimate_ecnfield;
for (i = 0; i < 3; i++) {
if (optlen >= TCPOLEN_ACCECN_PERFIELD) {
@@ -6410,7 +6438,14 @@ static bool tcp_validate_incoming(struct sock *sk, struct sk_buff *skb,
if (th->syn) {
if (tcp_ecn_mode_accecn(tp)) {
send_accecn_reflector = true;
- tp->accecn_opt_demand = max_t(u8, 1, tp->accecn_opt_demand);
+ if (tp->rx_opt.accecn &&
+ tp->saw_accecn_opt < TCP_ACCECN_OPT_COUNTER_SEEN) {
+ tp->saw_accecn_opt = tcp_accecn_option_init(skb,
+ tp->rx_opt.accecn);
+ if (tp->saw_accecn_opt == TCP_ACCECN_OPT_FAIL_SEEN)
+ tcp_accecn_fail_mode_set(tp, TCP_ACCECN_OPT_FAIL_RECV);
+ tp->accecn_opt_demand = max_t(u8, 1, tp->accecn_opt_demand);
+ }
}
if (sk->sk_state == TCP_SYN_RECV && sk->sk_socket && th->ack &&
TCP_SKB_CB(skb)->seq + 1 == TCP_SKB_CB(skb)->end_seq &&
@@ -6900,7 +6935,7 @@ static int tcp_rcv_synsent_state_process(struct sock *sk, struct sk_buff *skb,
*/
if (tcp_ecn_mode_any(tp))
- tcp_ecn_rcv_synack(sk, th, TCP_SKB_CB(skb)->ip_dsfield);
+ tcp_ecn_rcv_synack(sk, skb, th, TCP_SKB_CB(skb)->ip_dsfield);
tcp_init_wl(tp, TCP_SKB_CB(skb)->seq);
tcp_try_undo_spurious_syn(sk);
@@ -7476,6 +7511,8 @@ static void tcp_openreq_init(struct request_sock *req,
tcp_rsk(req)->snt_synack = 0;
tcp_rsk(req)->last_oow_ack_time = 0;
tcp_rsk(req)->accecn_ok = 0;
+ tcp_rsk(req)->saw_accecn_opt = TCP_ACCECN_OPT_NOT_SEEN;
+ tcp_rsk(req)->accecn_fail_mode = 0;
tcp_rsk(req)->syn_ect_rcv = 0;
tcp_rsk(req)->syn_ect_snt = 0;
req->mss = rx_opt->mss_clamp;
diff --git a/net/ipv4/tcp_minisocks.c b/net/ipv4/tcp_minisocks.c
index 75baa72849fe..cce1816e4244 100644
--- a/net/ipv4/tcp_minisocks.c
+++ b/net/ipv4/tcp_minisocks.c
@@ -490,6 +490,7 @@ static void tcp_ecn_openreq_child(struct sock *sk,
tcp_ecn_mode_set(tp, TCP_ECN_MODE_ACCECN);
tp->syn_ect_snt = treq->syn_ect_snt;
tcp_accecn_third_ack(sk, skb, treq->syn_ect_snt);
+ tp->saw_accecn_opt = treq->saw_accecn_opt;
tp->prev_ecnfield = treq->syn_ect_rcv;
tp->accecn_opt_demand = 1;
tcp_ecn_received_counters(sk, skb, skb->len - th->doff * 4);
@@ -544,6 +545,30 @@ static void smc_check_reset_syn_req(const struct tcp_sock *oldtp,
#endif
}
+u8 tcp_accecn_option_init(const struct sk_buff *skb, u8 opt_offset)
+{
+ unsigned char *ptr = skb_transport_header(skb) + opt_offset;
+ unsigned int optlen = ptr[1] - 2;
+
+ WARN_ON_ONCE(ptr[0] != TCPOPT_ACCECN0 && ptr[0] != TCPOPT_ACCECN1);
+ ptr += 2;
+
+ /* Detect option zeroing: an AccECN connection "MAY check that the
+ * initial value of the EE0B field or the EE1B field is non-zero"
+ */
+ if (optlen < TCPOLEN_ACCECN_PERFIELD)
+ return TCP_ACCECN_OPT_EMPTY_SEEN;
+ if (get_unaligned_be24(ptr) == 0)
+ return TCP_ACCECN_OPT_FAIL_SEEN;
+ if (optlen < TCPOLEN_ACCECN_PERFIELD * 3)
+ return TCP_ACCECN_OPT_COUNTER_SEEN;
+ ptr += TCPOLEN_ACCECN_PERFIELD * 2;
+ if (get_unaligned_be24(ptr) == 0)
+ return TCP_ACCECN_OPT_FAIL_SEEN;
+
+ return TCP_ACCECN_OPT_COUNTER_SEEN;
+}
+
/* This is not only more efficient than what we used to do, it eliminates
* a lot of code duplication between IPv4/IPv6 SYN recv processing. -DaveM
*
@@ -704,6 +729,7 @@ struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb,
bool own_req;
tmp_opt.saw_tstamp = 0;
+ tmp_opt.accecn = 0;
if (th->doff > (sizeof(struct tcphdr)>>2)) {
tcp_parse_options(sock_net(sk), skb, &tmp_opt, 0, NULL);
@@ -879,6 +905,13 @@ struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb,
if (!(flg & TCP_FLAG_ACK))
return NULL;
+ if (tcp_rsk(req)->accecn_ok && tmp_opt.accecn &&
+ tcp_rsk(req)->saw_accecn_opt < TCP_ACCECN_OPT_COUNTER_SEEN) {
+ tcp_rsk(req)->saw_accecn_opt = tcp_accecn_option_init(skb, tmp_opt.accecn);
+ if (tcp_rsk(req)->saw_accecn_opt == TCP_ACCECN_OPT_FAIL_SEEN)
+ tcp_rsk(req)->accecn_fail_mode |= TCP_ACCECN_OPT_FAIL_RECV;
+ }
+
/* For Fast Open no more processing is needed (sk is the
* child socket).
*/
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 22f6cfba5b27..ee23b08bd750 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -1069,6 +1069,7 @@ static unsigned int tcp_syn_options(struct sock *sk, struct sk_buff *skb,
/* Simultaneous open SYN/ACK needs AccECN option but not SYN */
if (unlikely((TCP_SKB_CB(skb)->tcp_flags & TCPHDR_ACK) &&
tcp_ecn_mode_accecn(tp) &&
+ inet_csk(sk)->icsk_retransmits < 2 &&
sock_net(sk)->ipv4.sysctl_tcp_ecn_option &&
remaining >= TCPOLEN_ACCECN_BASE)) {
opts->ecn_bytes = synack_ecn_bytes;
@@ -1151,7 +1152,7 @@ static unsigned int tcp_synack_options(const struct sock *sk,
smc_set_option_cond(tcp_sk(sk), ireq, opts, &remaining);
if (treq->accecn_ok && sock_net(sk)->ipv4.sysctl_tcp_ecn_option &&
- remaining >= TCPOLEN_ACCECN_BASE) {
+ req->num_timeout < 1 && remaining >= TCPOLEN_ACCECN_BASE) {
opts->ecn_bytes = synack_ecn_bytes;
remaining -= tcp_options_fit_accecn(opts, 0, remaining,
tcp_synack_options_combine_saving(opts));
@@ -1228,7 +1229,9 @@ static unsigned int tcp_established_options(struct sock *sk, struct sk_buff *skb
}
if (tcp_ecn_mode_accecn(tp) &&
- sock_net(sk)->ipv4.sysctl_tcp_ecn_option) {
+ sock_net(sk)->ipv4.sysctl_tcp_ecn_option &&
+ tp->saw_accecn_opt &&
+ !tcp_accecn_opt_fail_send(tp)) {
if (sock_net(sk)->ipv4.sysctl_tcp_ecn_option >= 2 ||
tp->accecn_opt_demand ||
tcp_accecn_option_beacon_check(sk)) {
--
2.34.1
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