From 149dfb31615e22271d2525f078c95ea49bc4db24 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Ilpo=20J=C3=A4rvinen?= Date: Wed, 5 Mar 2025 23:38:41 +0100 Subject: [PATCH 01/11] tcp: reorganize tcp_in_ack_event() and tcp_count_delivered() MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit - Move tcp_count_delivered() earlier and split tcp_count_delivered_ce() out of it - Move tcp_in_ack_event() later - While at it, remove the inline from tcp_in_ack_event() and let the compiler to decide Accurate ECN's heuristics does not know if there is going to be ACE field based CE counter increase or not until after rtx queue has been processed. Only then the number of ACKed bytes/pkts is available. As CE or not affects presence of FLAG_ECE, that information for tcp_in_ack_event is not yet available in the old location of the call to tcp_in_ack_event(). Signed-off-by: Ilpo Järvinen Signed-off-by: Chia-Yu Chang Signed-off-by: David S. Miller --- net/ipv4/tcp_input.c | 56 +++++++++++++++++++++++++------------------- 1 file changed, 32 insertions(+), 24 deletions(-) diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index 4e2212348088..6a8eca916580 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -421,6 +421,20 @@ static bool tcp_ecn_rcv_ecn_echo(const struct tcp_sock *tp, const struct tcphdr return false; } +static void tcp_count_delivered_ce(struct tcp_sock *tp, u32 ecn_count) +{ + tp->delivered_ce += ecn_count; +} + +/* Updates the delivered and delivered_ce counts */ +static void tcp_count_delivered(struct tcp_sock *tp, u32 delivered, + bool ece_ack) +{ + tp->delivered += delivered; + if (ece_ack) + tcp_count_delivered_ce(tp, delivered); +} + /* Buffer size and advertised window tuning. * * 1. Tuning sk->sk_sndbuf, when connection enters established state. @@ -1156,15 +1170,6 @@ void tcp_mark_skb_lost(struct sock *sk, struct sk_buff *skb) } } -/* Updates the delivered and delivered_ce counts */ -static void tcp_count_delivered(struct tcp_sock *tp, u32 delivered, - bool ece_ack) -{ - tp->delivered += delivered; - if (ece_ack) - tp->delivered_ce += delivered; -} - /* This procedure tags the retransmission queue when SACKs arrive. * * We have three tag bits: SACKED(S), RETRANS(R) and LOST(L). @@ -3864,12 +3869,23 @@ static void tcp_process_tlp_ack(struct sock *sk, u32 ack, int flag) } } -static inline void tcp_in_ack_event(struct sock *sk, u32 flags) +static void tcp_in_ack_event(struct sock *sk, int flag) { const struct inet_connection_sock *icsk = inet_csk(sk); - if (icsk->icsk_ca_ops->in_ack_event) - icsk->icsk_ca_ops->in_ack_event(sk, flags); + if (icsk->icsk_ca_ops->in_ack_event) { + u32 ack_ev_flags = 0; + + if (flag & FLAG_WIN_UPDATE) + ack_ev_flags |= CA_ACK_WIN_UPDATE; + if (flag & FLAG_SLOWPATH) { + ack_ev_flags |= CA_ACK_SLOWPATH; + if (flag & FLAG_ECE) + ack_ev_flags |= CA_ACK_ECE; + } + + icsk->icsk_ca_ops->in_ack_event(sk, ack_ev_flags); + } } /* Congestion control has updated the cwnd already. So if we're in @@ -3986,12 +4002,8 @@ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag) tcp_snd_una_update(tp, ack); flag |= FLAG_WIN_UPDATE; - tcp_in_ack_event(sk, CA_ACK_WIN_UPDATE); - NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPHPACKS); } else { - u32 ack_ev_flags = CA_ACK_SLOWPATH; - if (ack_seq != TCP_SKB_CB(skb)->end_seq) flag |= FLAG_DATA; else @@ -4003,19 +4015,12 @@ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag) flag |= tcp_sacktag_write_queue(sk, skb, prior_snd_una, &sack_state); - if (tcp_ecn_rcv_ecn_echo(tp, tcp_hdr(skb))) { + if (tcp_ecn_rcv_ecn_echo(tp, tcp_hdr(skb))) flag |= FLAG_ECE; - ack_ev_flags |= CA_ACK_ECE; - } if (sack_state.sack_delivered) tcp_count_delivered(tp, sack_state.sack_delivered, flag & FLAG_ECE); - - if (flag & FLAG_WIN_UPDATE) - ack_ev_flags |= CA_ACK_WIN_UPDATE; - - tcp_in_ack_event(sk, ack_ev_flags); } /* This is a deviation from RFC3168 since it states that: @@ -4042,6 +4047,8 @@ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag) tcp_rack_update_reo_wnd(sk, &rs); + tcp_in_ack_event(sk, flag); + if (tp->tlp_high_seq) tcp_process_tlp_ack(sk, ack, flag); @@ -4073,6 +4080,7 @@ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag) return 1; no_queue: + tcp_in_ack_event(sk, flag); /* If data was DSACKed, see if we can undo a cwnd reduction. */ if (flag & FLAG_DSACKING_ACK) { tcp_fastretrans_alert(sk, prior_snd_una, num_dupack, &flag, From da610e18313be854977347450c86997548406813 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Ilpo=20J=C3=A4rvinen?= Date: Wed, 5 Mar 2025 23:38:42 +0100 Subject: [PATCH 02/11] tcp: create FLAG_TS_PROGRESS MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Whenever timestamp advances, it declares progress which can be used by the other parts of the stack to decide that the ACK is the most recent one seen so far. AccECN will use this flag when deciding whether to use the ACK to update AccECN state or not. Signed-off-by: Ilpo Järvinen Signed-off-by: Chia-Yu Chang Reviewed-by: Eric Dumazet Signed-off-by: David S. Miller --- net/ipv4/tcp_input.c | 37 ++++++++++++++++++++++++++++--------- 1 file changed, 28 insertions(+), 9 deletions(-) diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index 6a8eca916580..771e075d457d 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -102,6 +102,7 @@ int sysctl_tcp_max_orphans __read_mostly = NR_FILE; #define FLAG_NO_CHALLENGE_ACK 0x8000 /* do not call tcp_send_challenge_ack() */ #define FLAG_ACK_MAYBE_DELAYED 0x10000 /* Likely a delayed ACK */ #define FLAG_DSACK_TLP 0x20000 /* DSACK for tail loss probe */ +#define FLAG_TS_PROGRESS 0x40000 /* Positive timestamp delta */ #define FLAG_ACKED (FLAG_DATA_ACKED|FLAG_SYN_ACKED) #define FLAG_NOT_DUP (FLAG_DATA|FLAG_WIN_UPDATE|FLAG_ACKED) @@ -3821,8 +3822,16 @@ static void tcp_store_ts_recent(struct tcp_sock *tp) tp->rx_opt.ts_recent_stamp = ktime_get_seconds(); } -static void tcp_replace_ts_recent(struct tcp_sock *tp, u32 seq) +static int __tcp_replace_ts_recent(struct tcp_sock *tp, s32 tstamp_delta) { + tcp_store_ts_recent(tp); + return tstamp_delta > 0 ? FLAG_TS_PROGRESS : 0; +} + +static int tcp_replace_ts_recent(struct tcp_sock *tp, u32 seq) +{ + s32 delta; + if (tp->rx_opt.saw_tstamp && !after(seq, tp->rcv_wup)) { /* PAWS bug workaround wrt. ACK frames, the PAWS discard * extra check below makes sure this can only happen @@ -3831,9 +3840,13 @@ static void tcp_replace_ts_recent(struct tcp_sock *tp, u32 seq) * Not only, also it occurs for expired timestamps. */ - if (tcp_paws_check(&tp->rx_opt, 0)) - tcp_store_ts_recent(tp); + if (tcp_paws_check(&tp->rx_opt, 0)) { + delta = tp->rx_opt.rcv_tsval - tp->rx_opt.ts_recent; + return __tcp_replace_ts_recent(tp, delta); + } } + + return 0; } /* This routine deals with acks during a TLP episode and ends an episode by @@ -3990,7 +4003,7 @@ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag) * is in window. */ if (flag & FLAG_UPDATE_TS_RECENT) - tcp_replace_ts_recent(tp, TCP_SKB_CB(skb)->seq); + flag |= tcp_replace_ts_recent(tp, TCP_SKB_CB(skb)->seq); if ((flag & (FLAG_SLOWPATH | FLAG_SND_UNA_ADVANCED)) == FLAG_SND_UNA_ADVANCED) { @@ -6165,6 +6178,8 @@ void tcp_rcv_established(struct sock *sk, struct sk_buff *skb) TCP_SKB_CB(skb)->seq == tp->rcv_nxt && !after(TCP_SKB_CB(skb)->ack_seq, tp->snd_nxt)) { int tcp_header_len = tp->tcp_header_len; + s32 delta = 0; + int flag = 0; /* Timestamp header prediction: tcp_header_len * is automatically equal to th->doff*4 due to pred_flags @@ -6177,8 +6192,10 @@ void tcp_rcv_established(struct sock *sk, struct sk_buff *skb) if (!tcp_parse_aligned_timestamp(tp, th)) goto slow_path; + delta = tp->rx_opt.rcv_tsval - + tp->rx_opt.ts_recent; /* If PAWS failed, check it more carefully in slow path */ - if ((s32)(tp->rx_opt.rcv_tsval - tp->rx_opt.ts_recent) < 0) + if (delta < 0) goto slow_path; /* DO NOT update ts_recent here, if checksum fails @@ -6198,12 +6215,13 @@ void tcp_rcv_established(struct sock *sk, struct sk_buff *skb) if (tcp_header_len == (sizeof(struct tcphdr) + TCPOLEN_TSTAMP_ALIGNED) && tp->rcv_nxt == tp->rcv_wup) - tcp_store_ts_recent(tp); + flag |= __tcp_replace_ts_recent(tp, + delta); /* We know that such packets are checksummed * on entry. */ - tcp_ack(sk, skb, 0); + tcp_ack(sk, skb, flag); __kfree_skb(skb); tcp_data_snd_check(sk); /* When receiving pure ack in fast path, update @@ -6234,7 +6252,8 @@ void tcp_rcv_established(struct sock *sk, struct sk_buff *skb) if (tcp_header_len == (sizeof(struct tcphdr) + TCPOLEN_TSTAMP_ALIGNED) && tp->rcv_nxt == tp->rcv_wup) - tcp_store_ts_recent(tp); + flag |= __tcp_replace_ts_recent(tp, + delta); tcp_rcv_rtt_measure_ts(sk, skb); @@ -6249,7 +6268,7 @@ void tcp_rcv_established(struct sock *sk, struct sk_buff *skb) if (TCP_SKB_CB(skb)->ack_seq != tp->snd_una) { /* Well, only one small jumplet in fast path... */ - tcp_ack(sk, skb, FLAG_DATA); + tcp_ack(sk, skb, flag | FLAG_DATA); tcp_data_snd_check(sk); if (!inet_csk_ack_scheduled(sk)) goto no_ack; From 0114a91da67263c56612ff19a6aa0992466e7756 Mon Sep 17 00:00:00 2001 From: Chia-Yu Chang Date: Wed, 5 Mar 2025 23:38:43 +0100 Subject: [PATCH 03/11] tcp: use BIT() macro in include/net/tcp.h MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Use BIT() macro for TCP flags field and TCP congestion control flags that will be used by the congestion control algorithm. No functional changes. Signed-off-by: Chia-Yu Chang Reviewed-by: Ilpo Järvinen Reviewed-by: Eric Dumazet Signed-off-by: David S. Miller --- include/net/tcp.h | 21 +++++++++++---------- 1 file changed, 11 insertions(+), 10 deletions(-) diff --git a/include/net/tcp.h b/include/net/tcp.h index 7207c52b1fc9..d2315d69e019 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -26,6 +26,7 @@ #include #include #include +#include #include #include @@ -934,14 +935,14 @@ static inline u32 tcp_rsk_tsval(const struct tcp_request_sock *treq) #define tcp_flag_byte(th) (((u_int8_t *)th)[13]) -#define TCPHDR_FIN 0x01 -#define TCPHDR_SYN 0x02 -#define TCPHDR_RST 0x04 -#define TCPHDR_PSH 0x08 -#define TCPHDR_ACK 0x10 -#define TCPHDR_URG 0x20 -#define TCPHDR_ECE 0x40 -#define TCPHDR_CWR 0x80 +#define TCPHDR_FIN BIT(0) +#define TCPHDR_SYN BIT(1) +#define TCPHDR_RST BIT(2) +#define TCPHDR_PSH BIT(3) +#define TCPHDR_ACK BIT(4) +#define TCPHDR_URG BIT(5) +#define TCPHDR_ECE BIT(6) +#define TCPHDR_CWR BIT(7) #define TCPHDR_SYN_ECN (TCPHDR_SYN | TCPHDR_ECE | TCPHDR_CWR) @@ -1132,9 +1133,9 @@ enum tcp_ca_ack_event_flags { #define TCP_CA_UNSPEC 0 /* Algorithm can be set on socket without CAP_NET_ADMIN privileges */ -#define TCP_CONG_NON_RESTRICTED 0x1 +#define TCP_CONG_NON_RESTRICTED BIT(0) /* Requires ECN/ECT set on all packets */ -#define TCP_CONG_NEEDS_ECN 0x2 +#define TCP_CONG_NEEDS_ECN BIT(1) #define TCP_CONG_MASK (TCP_CONG_NON_RESTRICTED | TCP_CONG_NEEDS_ECN) union tcp_cc_info; From 2c2f08d31d2f6cd5621b121d596986bd54da679a Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Ilpo=20J=C3=A4rvinen?= Date: Wed, 5 Mar 2025 23:38:44 +0100 Subject: [PATCH 04/11] tcp: extend TCP flags to allow AE bit/ACE field MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit With AccECN, there's one additional TCP flag to be used (AE) and ACE field that overloads the definition of AE, CWR, and ECE flags. As tcp_flags was previously only 1 byte, the byte-order stuff needs to be added to it's handling. Signed-off-by: Ilpo Järvinen Signed-off-by: Chia-Yu Chang Reviewed-by: Eric Dumazet Signed-off-by: David S. Miller --- include/net/tcp.h | 11 +++++++++-- include/uapi/linux/tcp.h | 9 ++++++--- net/ipv4/tcp_ipv4.c | 2 +- net/ipv4/tcp_output.c | 8 ++++---- net/ipv6/tcp_ipv6.c | 2 +- net/netfilter/nf_log_syslog.c | 8 +++++--- 6 files changed, 26 insertions(+), 14 deletions(-) diff --git a/include/net/tcp.h b/include/net/tcp.h index d2315d69e019..4e11bdc86470 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -943,7 +943,14 @@ static inline u32 tcp_rsk_tsval(const struct tcp_request_sock *treq) #define TCPHDR_URG BIT(5) #define TCPHDR_ECE BIT(6) #define TCPHDR_CWR BIT(7) - +#define TCPHDR_AE BIT(8) +#define TCPHDR_FLAGS_MASK (TCPHDR_FIN | TCPHDR_SYN | TCPHDR_RST | \ + TCPHDR_PSH | TCPHDR_ACK | TCPHDR_URG | \ + TCPHDR_ECE | TCPHDR_CWR | TCPHDR_AE) +#define tcp_flags_ntohs(th) (ntohs(*(__be16 *)&tcp_flag_word(th)) & \ + TCPHDR_FLAGS_MASK) + +#define TCPHDR_ACE (TCPHDR_ECE | TCPHDR_CWR | TCPHDR_AE) #define TCPHDR_SYN_ECN (TCPHDR_SYN | TCPHDR_ECE | TCPHDR_CWR) /* State flags for sacked in struct tcp_skb_cb */ @@ -978,7 +985,7 @@ struct tcp_skb_cb { u16 tcp_gso_size; }; }; - __u8 tcp_flags; /* TCP header flags. (tcp[13]) */ + __u16 tcp_flags; /* TCP header flags (tcp[12-13])*/ __u8 sacked; /* State flags for SACK. */ __u8 ip_dsfield; /* IPv4 tos or IPv6 dsfield */ diff --git a/include/uapi/linux/tcp.h b/include/uapi/linux/tcp.h index 32a27b4a5020..92a2e79222ea 100644 --- a/include/uapi/linux/tcp.h +++ b/include/uapi/linux/tcp.h @@ -28,7 +28,8 @@ struct tcphdr { __be32 seq; __be32 ack_seq; #if defined(__LITTLE_ENDIAN_BITFIELD) - __u16 res1:4, + __u16 ae:1, + res1:3, doff:4, fin:1, syn:1, @@ -40,7 +41,8 @@ struct tcphdr { cwr:1; #elif defined(__BIG_ENDIAN_BITFIELD) __u16 doff:4, - res1:4, + res1:3, + ae:1, cwr:1, ece:1, urg:1, @@ -70,6 +72,7 @@ union tcp_word_hdr { #define tcp_flag_word(tp) (((union tcp_word_hdr *)(tp))->words[3]) enum { + TCP_FLAG_AE = __constant_cpu_to_be32(0x01000000), TCP_FLAG_CWR = __constant_cpu_to_be32(0x00800000), TCP_FLAG_ECE = __constant_cpu_to_be32(0x00400000), TCP_FLAG_URG = __constant_cpu_to_be32(0x00200000), @@ -78,7 +81,7 @@ enum { TCP_FLAG_RST = __constant_cpu_to_be32(0x00040000), TCP_FLAG_SYN = __constant_cpu_to_be32(0x00020000), TCP_FLAG_FIN = __constant_cpu_to_be32(0x00010000), - TCP_RESERVED_BITS = __constant_cpu_to_be32(0x0F000000), + TCP_RESERVED_BITS = __constant_cpu_to_be32(0x0E000000), TCP_DATA_OFFSET = __constant_cpu_to_be32(0xF0000000) }; diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c index d9405b012dff..fab684221bf7 100644 --- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -2159,7 +2159,7 @@ static void tcp_v4_fill_cb(struct sk_buff *skb, const struct iphdr *iph, TCP_SKB_CB(skb)->end_seq = (TCP_SKB_CB(skb)->seq + th->syn + th->fin + skb->len - th->doff * 4); TCP_SKB_CB(skb)->ack_seq = ntohl(th->ack_seq); - TCP_SKB_CB(skb)->tcp_flags = tcp_flag_byte(th); + TCP_SKB_CB(skb)->tcp_flags = tcp_flags_ntohs(th); TCP_SKB_CB(skb)->ip_dsfield = ipv4_get_dsfield(iph); TCP_SKB_CB(skb)->sacked = 0; TCP_SKB_CB(skb)->has_rxtstamp = diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index 24e56bf96747..efd3cb5e1ded 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -403,7 +403,7 @@ static void tcp_ecn_send(struct sock *sk, struct sk_buff *skb, /* Constructs common control bits of non-data skb. If SYN/FIN is present, * auto increment end seqno. */ -static void tcp_init_nondata_skb(struct sk_buff *skb, u32 seq, u8 flags) +static void tcp_init_nondata_skb(struct sk_buff *skb, u32 seq, u16 flags) { skb->ip_summed = CHECKSUM_PARTIAL; @@ -1395,7 +1395,7 @@ static int __tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, th->seq = htonl(tcb->seq); th->ack_seq = htonl(rcv_nxt); *(((__be16 *)th) + 6) = htons(((tcp_header_size >> 2) << 12) | - tcb->tcp_flags); + (tcb->tcp_flags & TCPHDR_FLAGS_MASK)); th->check = 0; th->urg_ptr = 0; @@ -1616,8 +1616,8 @@ int tcp_fragment(struct sock *sk, enum tcp_queue tcp_queue, struct sk_buff *buff; int old_factor; long limit; + u16 flags; int nlen; - u8 flags; if (WARN_ON(len > skb->len)) return -EINVAL; @@ -2171,7 +2171,7 @@ static int tso_fragment(struct sock *sk, struct sk_buff *skb, unsigned int len, { int nlen = skb->len - len; struct sk_buff *buff; - u8 flags; + u16 flags; /* All of a TSO frame must be composed of paged data. */ DEBUG_NET_WARN_ON_ONCE(skb->len != skb->data_len); diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c index 85c4820bfe15..a2fcc317a88e 100644 --- a/net/ipv6/tcp_ipv6.c +++ b/net/ipv6/tcp_ipv6.c @@ -1731,7 +1731,7 @@ static void tcp_v6_fill_cb(struct sk_buff *skb, const struct ipv6hdr *hdr, TCP_SKB_CB(skb)->end_seq = (TCP_SKB_CB(skb)->seq + th->syn + th->fin + skb->len - th->doff*4); TCP_SKB_CB(skb)->ack_seq = ntohl(th->ack_seq); - TCP_SKB_CB(skb)->tcp_flags = tcp_flag_byte(th); + TCP_SKB_CB(skb)->tcp_flags = tcp_flags_ntohs(th); TCP_SKB_CB(skb)->ip_dsfield = ipv6_get_dsfield(hdr); TCP_SKB_CB(skb)->sacked = 0; TCP_SKB_CB(skb)->has_rxtstamp = diff --git a/net/netfilter/nf_log_syslog.c b/net/netfilter/nf_log_syslog.c index 58402226045e..86d5fc5d28e3 100644 --- a/net/netfilter/nf_log_syslog.c +++ b/net/netfilter/nf_log_syslog.c @@ -216,7 +216,9 @@ nf_log_dump_tcp_header(struct nf_log_buf *m, /* Max length: 9 "RES=0x3C " */ nf_log_buf_add(m, "RES=0x%02x ", (u_int8_t)(ntohl(tcp_flag_word(th) & TCP_RESERVED_BITS) >> 22)); - /* Max length: 32 "CWR ECE URG ACK PSH RST SYN FIN " */ + /* Max length: 35 "AE CWR ECE URG ACK PSH RST SYN FIN " */ + if (th->ae) + nf_log_buf_add(m, "AE "); if (th->cwr) nf_log_buf_add(m, "CWR "); if (th->ece) @@ -516,7 +518,7 @@ dump_ipv4_packet(struct net *net, struct nf_log_buf *m, /* Proto Max log string length */ /* IP: 40+46+6+11+127 = 230 */ - /* TCP: 10+max(25,20+30+13+9+32+11+127) = 252 */ + /* TCP: 10+max(25,20+30+13+9+35+11+127) = 255 */ /* UDP: 10+max(25,20) = 35 */ /* UDPLITE: 14+max(25,20) = 39 */ /* ICMP: 11+max(25, 18+25+max(19,14,24+3+n+10,3+n+10)) = 91+n */ @@ -526,7 +528,7 @@ dump_ipv4_packet(struct net *net, struct nf_log_buf *m, /* (ICMP allows recursion one level deep) */ /* maxlen = IP + ICMP + IP + max(TCP,UDP,ICMP,unknown) */ - /* maxlen = 230+ 91 + 230 + 252 = 803 */ + /* maxlen = 230+ 91 + 230 + 255 = 806 */ } static noinline_for_stack void From f0db2bca0cf9d35a348f8fa726c1f61879a5cd02 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Ilpo=20J=C3=A4rvinen?= Date: Wed, 5 Mar 2025 23:38:46 +0100 Subject: [PATCH 05/11] tcp: rework {__,}tcp_ecn_check_ce() -> tcp_data_ecn_check() MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Rename tcp_ecn_check_ce to tcp_data_ecn_check as it is called only for data segments, not for ACKs (with AccECN, also ACKs may get ECN bits). The extra "layer" in tcp_ecn_check_ce() function just checks for ECN being enabled, that can be moved into tcp_ecn_field_check rather than having the __ variant. No functional changes. Signed-off-by: Ilpo Järvinen Signed-off-by: Chia-Yu Chang Reviewed-by: Eric Dumazet Signed-off-by: David S. Miller --- net/ipv4/tcp_input.c | 15 ++++++--------- 1 file changed, 6 insertions(+), 9 deletions(-) diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index 771e075d457d..769048b559e5 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -365,10 +365,13 @@ static void tcp_ecn_withdraw_cwr(struct tcp_sock *tp) tp->ecn_flags &= ~TCP_ECN_QUEUE_CWR; } -static void __tcp_ecn_check_ce(struct sock *sk, const struct sk_buff *skb) +static void tcp_data_ecn_check(struct sock *sk, const struct sk_buff *skb) { struct tcp_sock *tp = tcp_sk(sk); + if (!(tcp_sk(sk)->ecn_flags & TCP_ECN_OK)) + return; + switch (TCP_SKB_CB(skb)->ip_dsfield & INET_ECN_MASK) { case INET_ECN_NOT_ECT: /* Funny extension: if ECT is not set on a segment, @@ -397,12 +400,6 @@ static void __tcp_ecn_check_ce(struct sock *sk, const struct sk_buff *skb) } } -static void tcp_ecn_check_ce(struct sock *sk, const struct sk_buff *skb) -{ - if (tcp_sk(sk)->ecn_flags & TCP_ECN_OK) - __tcp_ecn_check_ce(sk, skb); -} - static void tcp_ecn_rcv_synack(struct tcp_sock *tp, const struct tcphdr *th) { if ((tp->ecn_flags & TCP_ECN_OK) && (!th->ece || th->cwr)) @@ -874,7 +871,7 @@ static void tcp_event_data_recv(struct sock *sk, struct sk_buff *skb) icsk->icsk_ack.lrcvtime = now; tcp_save_lrcv_flowlabel(sk, skb); - tcp_ecn_check_ce(sk, skb); + tcp_data_ecn_check(sk, skb); if (skb->len >= 128) tcp_grow_window(sk, skb, true); @@ -5041,7 +5038,7 @@ static void tcp_data_queue_ofo(struct sock *sk, struct sk_buff *skb) bool fragstolen; tcp_save_lrcv_flowlabel(sk, skb); - tcp_ecn_check_ce(sk, skb); + tcp_data_ecn_check(sk, skb); if (unlikely(tcp_try_rmem_schedule(sk, skb, skb->truesize))) { NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPOFODROP); From 041fb11d518f5d25d323766bc0f59b09bba314bc Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Ilpo=20J=C3=A4rvinen?= Date: Wed, 5 Mar 2025 23:38:47 +0100 Subject: [PATCH 06/11] tcp: helpers for ECN mode handling MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Create helpers for TCP ECN modes. No functional changes. Signed-off-by: Ilpo Järvinen Signed-off-by: Chia-Yu Chang Reviewed-by: Eric Dumazet Signed-off-by: David S. Miller --- include/net/tcp.h | 44 ++++++++++++++++++++++++++++++++++++---- net/ipv4/tcp.c | 2 +- net/ipv4/tcp_dctcp.c | 2 +- net/ipv4/tcp_input.c | 14 ++++++------- net/ipv4/tcp_minisocks.c | 4 +++- net/ipv4/tcp_output.c | 6 +++--- 6 files changed, 55 insertions(+), 17 deletions(-) diff --git a/include/net/tcp.h b/include/net/tcp.h index 4e11bdc86470..5520f2d62dc0 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -374,10 +374,46 @@ static inline void tcp_dec_quickack_mode(struct sock *sk) } } -#define TCP_ECN_OK 1 -#define TCP_ECN_QUEUE_CWR 2 -#define TCP_ECN_DEMAND_CWR 4 -#define TCP_ECN_SEEN 8 +#define TCP_ECN_MODE_RFC3168 BIT(0) +#define TCP_ECN_QUEUE_CWR BIT(1) +#define TCP_ECN_DEMAND_CWR BIT(2) +#define TCP_ECN_SEEN BIT(3) +#define TCP_ECN_MODE_ACCECN BIT(4) + +#define TCP_ECN_DISABLED 0 +#define TCP_ECN_MODE_PENDING (TCP_ECN_MODE_RFC3168 | TCP_ECN_MODE_ACCECN) +#define TCP_ECN_MODE_ANY (TCP_ECN_MODE_RFC3168 | TCP_ECN_MODE_ACCECN) + +static inline bool tcp_ecn_mode_any(const struct tcp_sock *tp) +{ + return tp->ecn_flags & TCP_ECN_MODE_ANY; +} + +static inline bool tcp_ecn_mode_rfc3168(const struct tcp_sock *tp) +{ + return (tp->ecn_flags & TCP_ECN_MODE_ANY) == TCP_ECN_MODE_RFC3168; +} + +static inline bool tcp_ecn_mode_accecn(const struct tcp_sock *tp) +{ + return (tp->ecn_flags & TCP_ECN_MODE_ANY) == TCP_ECN_MODE_ACCECN; +} + +static inline bool tcp_ecn_disabled(const struct tcp_sock *tp) +{ + return !tcp_ecn_mode_any(tp); +} + +static inline bool tcp_ecn_mode_pending(const struct tcp_sock *tp) +{ + return (tp->ecn_flags & TCP_ECN_MODE_PENDING) == TCP_ECN_MODE_PENDING; +} + +static inline void tcp_ecn_mode_set(struct tcp_sock *tp, u8 mode) +{ + tp->ecn_flags &= ~TCP_ECN_MODE_ANY; + tp->ecn_flags |= mode; +} enum tcp_tw_status { TCP_TW_SUCCESS = 0, diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index 46951e749308..989c3c3d8e75 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -4138,7 +4138,7 @@ void tcp_get_info(struct sock *sk, struct tcp_info *info) info->tcpi_rcv_wscale = tp->rx_opt.rcv_wscale; } - if (tp->ecn_flags & TCP_ECN_OK) + if (tcp_ecn_mode_any(tp)) info->tcpi_options |= TCPI_OPT_ECN; if (tp->ecn_flags & TCP_ECN_SEEN) info->tcpi_options |= TCPI_OPT_ECN_SEEN; diff --git a/net/ipv4/tcp_dctcp.c b/net/ipv4/tcp_dctcp.c index 8a45a4aea933..03abe0848420 100644 --- a/net/ipv4/tcp_dctcp.c +++ b/net/ipv4/tcp_dctcp.c @@ -90,7 +90,7 @@ __bpf_kfunc static void dctcp_init(struct sock *sk) { const struct tcp_sock *tp = tcp_sk(sk); - if ((tp->ecn_flags & TCP_ECN_OK) || + if (tcp_ecn_mode_any(tp) || (sk->sk_state == TCP_LISTEN || sk->sk_state == TCP_CLOSE)) { struct dctcp *ca = inet_csk_ca(sk); diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index 769048b559e5..5c270cf96678 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -342,7 +342,7 @@ static bool tcp_in_quickack_mode(struct sock *sk) static void tcp_ecn_queue_cwr(struct tcp_sock *tp) { - if (tp->ecn_flags & TCP_ECN_OK) + if (tcp_ecn_mode_rfc3168(tp)) tp->ecn_flags |= TCP_ECN_QUEUE_CWR; } @@ -369,7 +369,7 @@ static void tcp_data_ecn_check(struct sock *sk, const struct sk_buff *skb) { struct tcp_sock *tp = tcp_sk(sk); - if (!(tcp_sk(sk)->ecn_flags & TCP_ECN_OK)) + if (tcp_ecn_disabled(tp)) return; switch (TCP_SKB_CB(skb)->ip_dsfield & INET_ECN_MASK) { @@ -402,19 +402,19 @@ static void tcp_data_ecn_check(struct sock *sk, const struct sk_buff *skb) static void tcp_ecn_rcv_synack(struct tcp_sock *tp, const struct tcphdr *th) { - if ((tp->ecn_flags & TCP_ECN_OK) && (!th->ece || th->cwr)) - tp->ecn_flags &= ~TCP_ECN_OK; + if (tcp_ecn_mode_rfc3168(tp) && (!th->ece || th->cwr)) + tcp_ecn_mode_set(tp, TCP_ECN_DISABLED); } static void tcp_ecn_rcv_syn(struct tcp_sock *tp, const struct tcphdr *th) { - if ((tp->ecn_flags & TCP_ECN_OK) && (!th->ece || !th->cwr)) - tp->ecn_flags &= ~TCP_ECN_OK; + if (tcp_ecn_mode_rfc3168(tp) && (!th->ece || !th->cwr)) + tcp_ecn_mode_set(tp, TCP_ECN_DISABLED); } static bool tcp_ecn_rcv_ecn_echo(const struct tcp_sock *tp, const struct tcphdr *th) { - if (th->ece && !th->syn && (tp->ecn_flags & TCP_ECN_OK)) + if (th->ece && !th->syn && tcp_ecn_mode_rfc3168(tp)) return true; return false; } diff --git a/net/ipv4/tcp_minisocks.c b/net/ipv4/tcp_minisocks.c index 3cb8f281186b..0ae24add155b 100644 --- a/net/ipv4/tcp_minisocks.c +++ b/net/ipv4/tcp_minisocks.c @@ -461,7 +461,9 @@ void tcp_openreq_init_rwin(struct request_sock *req, static void tcp_ecn_openreq_child(struct tcp_sock *tp, const struct request_sock *req) { - tp->ecn_flags = inet_rsk(req)->ecn_ok ? TCP_ECN_OK : 0; + tcp_ecn_mode_set(tp, inet_rsk(req)->ecn_ok ? + TCP_ECN_MODE_RFC3168 : + TCP_ECN_DISABLED); } void tcp_ca_openreq_child(struct sock *sk, const struct dst_entry *dst) diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index efd3cb5e1ded..fffbd3ee44ed 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -325,7 +325,7 @@ static void tcp_ecn_send_synack(struct sock *sk, struct sk_buff *skb) const struct tcp_sock *tp = tcp_sk(sk); TCP_SKB_CB(skb)->tcp_flags &= ~TCPHDR_CWR; - if (!(tp->ecn_flags & TCP_ECN_OK)) + if (tcp_ecn_disabled(tp)) TCP_SKB_CB(skb)->tcp_flags &= ~TCPHDR_ECE; else if (tcp_ca_needs_ecn(sk) || tcp_bpf_ca_needs_ecn(sk)) @@ -351,7 +351,7 @@ static void tcp_ecn_send_syn(struct sock *sk, struct sk_buff *skb) if (use_ecn) { TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_ECE | TCPHDR_CWR; - tp->ecn_flags = TCP_ECN_OK; + tcp_ecn_mode_set(tp, TCP_ECN_MODE_RFC3168); if (tcp_ca_needs_ecn(sk) || bpf_needs_ecn) INET_ECN_xmit(sk); } @@ -381,7 +381,7 @@ static void tcp_ecn_send(struct sock *sk, struct sk_buff *skb, { struct tcp_sock *tp = tcp_sk(sk); - if (tp->ecn_flags & TCP_ECN_OK) { + if (tcp_ecn_mode_rfc3168(tp)) { /* Not-retransmitted data segment: set ECT and inject CWR. */ if (skb->len != tcp_header_len && !before(TCP_SKB_CB(skb)->seq, tp->snd_nxt)) { From 023af5a72ab161f2e661afb53e3b6a6901f6ba00 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Ilpo=20J=C3=A4rvinen?= Date: Wed, 5 Mar 2025 23:38:48 +0100 Subject: [PATCH 07/11] gso: AccECN support MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Handling the CWR flag differs between RFC 3168 ECN and AccECN. With RFC 3168 ECN aware TSO (NETIF_F_TSO_ECN) CWR flag is cleared starting from 2nd segment which is incompatible how AccECN handles the CWR flag. Such super-segments are indicated by SKB_GSO_TCP_ECN. With AccECN, CWR flag (or more accurately, the ACE field that also includes ECE & AE flags) changes only when new packet(s) with CE mark arrives so the flag should not be changed within a super-skb. The new skb/feature flags are necessary to prevent such TSO engines corrupting AccECN ACE counters by clearing the CWR flag (if the CWR handling feature cannot be turned off). If NIC is completely unaware of RFC3168 ECN (doesn't support NETIF_F_TSO_ECN) or its TSO engine can be set to not touch CWR flag despite supporting also NETIF_F_TSO_ECN, TSO could be safely used with AccECN on such NIC. This should be evaluated per NIC basis (not done in this patch series for any NICs). For the cases, where TSO cannot keep its hands off the CWR flag, a GSO fallback is provided by this patch. Signed-off-by: Ilpo Järvinen Signed-off-by: Chia-Yu Chang Reviewed-by: Eric Dumazet Signed-off-by: David S. Miller --- include/linux/netdev_features.h | 8 +++++--- include/linux/netdevice.h | 2 ++ include/linux/skbuff.h | 2 ++ net/ethtool/common.c | 1 + net/ipv4/tcp_offload.c | 6 +++++- 5 files changed, 15 insertions(+), 4 deletions(-) diff --git a/include/linux/netdev_features.h b/include/linux/netdev_features.h index 11be70a7929f..7a01c518e573 100644 --- a/include/linux/netdev_features.h +++ b/include/linux/netdev_features.h @@ -53,12 +53,12 @@ enum { NETIF_F_GSO_UDP_BIT, /* ... UFO, deprecated except tuntap */ NETIF_F_GSO_UDP_L4_BIT, /* ... UDP payload GSO (not UFO) */ NETIF_F_GSO_FRAGLIST_BIT, /* ... Fraglist GSO */ + NETIF_F_GSO_ACCECN_BIT, /* TCP AccECN w/ TSO (no clear CWR) */ /**/NETIF_F_GSO_LAST = /* last bit, see GSO_MASK */ - NETIF_F_GSO_FRAGLIST_BIT, + NETIF_F_GSO_ACCECN_BIT, NETIF_F_FCOE_CRC_BIT, /* FCoE CRC32 */ NETIF_F_SCTP_CRC_BIT, /* SCTP checksum offload */ - __UNUSED_NETIF_F_37, NETIF_F_NTUPLE_BIT, /* N-tuple filters supported */ NETIF_F_RXHASH_BIT, /* Receive hashing offload */ NETIF_F_RXCSUM_BIT, /* Receive checksumming offload */ @@ -128,6 +128,7 @@ enum { #define NETIF_F_SG __NETIF_F(SG) #define NETIF_F_TSO6 __NETIF_F(TSO6) #define NETIF_F_TSO_ECN __NETIF_F(TSO_ECN) +#define NETIF_F_GSO_ACCECN __NETIF_F(GSO_ACCECN) #define NETIF_F_TSO __NETIF_F(TSO) #define NETIF_F_VLAN_CHALLENGED __NETIF_F(VLAN_CHALLENGED) #define NETIF_F_RXFCS __NETIF_F(RXFCS) @@ -210,7 +211,8 @@ static inline int find_next_netdev_feature(u64 feature, unsigned long start) NETIF_F_TSO_ECN | NETIF_F_TSO_MANGLEID) /* List of features with software fallbacks. */ -#define NETIF_F_GSO_SOFTWARE (NETIF_F_ALL_TSO | NETIF_F_GSO_SCTP | \ +#define NETIF_F_GSO_SOFTWARE (NETIF_F_ALL_TSO | \ + NETIF_F_GSO_ACCECN | NETIF_F_GSO_SCTP | \ NETIF_F_GSO_UDP_L4 | NETIF_F_GSO_FRAGLIST) /* diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h index 0dbfe069a6e3..67527243459b 100644 --- a/include/linux/netdevice.h +++ b/include/linux/netdevice.h @@ -5269,6 +5269,8 @@ static inline bool net_gso_ok(netdev_features_t features, int gso_type) BUILD_BUG_ON(SKB_GSO_UDP != (NETIF_F_GSO_UDP >> NETIF_F_GSO_SHIFT)); BUILD_BUG_ON(SKB_GSO_UDP_L4 != (NETIF_F_GSO_UDP_L4 >> NETIF_F_GSO_SHIFT)); BUILD_BUG_ON(SKB_GSO_FRAGLIST != (NETIF_F_GSO_FRAGLIST >> NETIF_F_GSO_SHIFT)); + BUILD_BUG_ON(SKB_GSO_TCP_ACCECN != + (NETIF_F_GSO_ACCECN >> NETIF_F_GSO_SHIFT)); return (features & feature) == feature; } diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index 14517e95a46c..b8a1343d6785 100644 --- a/include/linux/skbuff.h +++ b/include/linux/skbuff.h @@ -708,6 +708,8 @@ enum { SKB_GSO_UDP_L4 = 1 << 17, SKB_GSO_FRAGLIST = 1 << 18, + + SKB_GSO_TCP_ACCECN = 1 << 19, }; #if BITS_PER_LONG > 32 diff --git a/net/ethtool/common.c b/net/ethtool/common.c index ac8b6107863e..1c6f2a2f1871 100644 --- a/net/ethtool/common.c +++ b/net/ethtool/common.c @@ -36,6 +36,7 @@ const char netdev_features_strings[NETDEV_FEATURE_COUNT][ETH_GSTRING_LEN] = { [NETIF_F_TSO_BIT] = "tx-tcp-segmentation", [NETIF_F_GSO_ROBUST_BIT] = "tx-gso-robust", [NETIF_F_TSO_ECN_BIT] = "tx-tcp-ecn-segmentation", + [NETIF_F_GSO_ACCECN_BIT] = "tx-tcp-accecn-segmentation", [NETIF_F_TSO_MANGLEID_BIT] = "tx-tcp-mangleid-segmentation", [NETIF_F_TSO6_BIT] = "tx-tcp6-segmentation", [NETIF_F_FSO_BIT] = "tx-fcoe-segmentation", diff --git a/net/ipv4/tcp_offload.c b/net/ipv4/tcp_offload.c index e27f4ee2a0de..8c74fd69db2a 100644 --- a/net/ipv4/tcp_offload.c +++ b/net/ipv4/tcp_offload.c @@ -142,6 +142,7 @@ struct sk_buff *tcp_gso_segment(struct sk_buff *skb, struct sk_buff *gso_skb = skb; __sum16 newcheck; bool ooo_okay, copy_destructor; + bool ecn_cwr_mask; __wsum delta; th = tcp_hdr(skb); @@ -201,6 +202,8 @@ struct sk_buff *tcp_gso_segment(struct sk_buff *skb, newcheck = ~csum_fold(csum_add(csum_unfold(th->check), delta)); + ecn_cwr_mask = !!(skb_shinfo(gso_skb)->gso_type & SKB_GSO_TCP_ACCECN); + while (skb->next) { th->fin = th->psh = 0; th->check = newcheck; @@ -220,7 +223,8 @@ struct sk_buff *tcp_gso_segment(struct sk_buff *skb, th = tcp_hdr(skb); th->seq = htonl(seq); - th->cwr = 0; + + th->cwr &= ecn_cwr_mask; } /* Following permits TCP Small Queues to work well with GSO : From 4e4f7cefb130af6aba6a393b2d13930b49390df9 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Ilpo=20J=C3=A4rvinen?= Date: Wed, 5 Mar 2025 23:38:49 +0100 Subject: [PATCH 08/11] gro: prevent ACE field corruption & better AccECN handling MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit There are important differences in how the CWR field behaves in RFC3168 and AccECN. With AccECN, CWR flag is part of the ACE counter and its changes are important so adjust the flags changed mask accordingly. Also, if CWR is there, set the Accurate ECN GSO flag to avoid corrupting CWR flag somewhere. Signed-off-by: Ilpo Järvinen Signed-off-by: Chia-Yu Chang Signed-off-by: David S. Miller --- net/ipv4/tcp_offload.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/net/ipv4/tcp_offload.c b/net/ipv4/tcp_offload.c index 8c74fd69db2a..934f777f29d3 100644 --- a/net/ipv4/tcp_offload.c +++ b/net/ipv4/tcp_offload.c @@ -332,7 +332,7 @@ struct sk_buff *tcp_gro_receive(struct list_head *head, struct sk_buff *skb, th2 = tcp_hdr(p); flush = (__force int)(flags & TCP_FLAG_CWR); flush |= (__force int)((flags ^ tcp_flag_word(th2)) & - ~(TCP_FLAG_CWR | TCP_FLAG_FIN | TCP_FLAG_PSH)); + ~(TCP_FLAG_FIN | TCP_FLAG_PSH)); flush |= (__force int)(th->ack_seq ^ th2->ack_seq); for (i = sizeof(*th); i < thlen; i += 4) flush |= *(u32 *)((u8 *)th + i) ^ @@ -408,7 +408,7 @@ void tcp_gro_complete(struct sk_buff *skb) shinfo->gso_segs = NAPI_GRO_CB(skb)->count; if (th->cwr) - shinfo->gso_type |= SKB_GSO_TCP_ECN; + shinfo->gso_type |= SKB_GSO_TCP_ACCECN; } EXPORT_SYMBOL(tcp_gro_complete); From d722762c4eaa918d3d2f78b41cca3f480a616d65 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Ilpo=20J=C3=A4rvinen?= Date: Wed, 5 Mar 2025 23:38:50 +0100 Subject: [PATCH 09/11] tcp: AccECN support to tcp_add_backlog MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit AE flag needs to be preserved for AccECN. Signed-off-by: Ilpo Järvinen Signed-off-by: Chia-Yu Chang Reviewed-by: Eric Dumazet Signed-off-by: David S. Miller --- net/ipv4/tcp_ipv4.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c index fab684221bf7..87f270ebc635 100644 --- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -2051,7 +2051,8 @@ bool tcp_add_backlog(struct sock *sk, struct sk_buff *skb, !((TCP_SKB_CB(tail)->tcp_flags & TCP_SKB_CB(skb)->tcp_flags) & TCPHDR_ACK) || ((TCP_SKB_CB(tail)->tcp_flags ^ - TCP_SKB_CB(skb)->tcp_flags) & (TCPHDR_ECE | TCPHDR_CWR)) || + TCP_SKB_CB(skb)->tcp_flags) & + (TCPHDR_ECE | TCPHDR_CWR | TCPHDR_AE)) || !tcp_skb_can_collapse_rx(tail, skb) || thtail->doff != th->doff || memcmp(thtail + 1, th + 1, hdrlen - sizeof(*th))) From 4618e195f9251947a5f15f7e5533bcc3a19b93ef Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Ilpo=20J=C3=A4rvinen?= Date: Wed, 5 Mar 2025 23:38:51 +0100 Subject: [PATCH 10/11] tcp: add new TCP_TW_ACK_OOW state and allow ECN bits in TOS MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit ECN bits in TOS are always cleared when sending in ACKs in TW. Clearing them is problematic for TCP flows that used Accurate ECN because ECN bits decide which service queue the packet is placed into (L4S vs Classic). Effectively, TW ACKs are always downgraded from L4S to Classic queue which might impact, e.g., delay the ACK will experience on the path compared with the other packets of the flow. Change the TW ACK sending code to differentiate: - In tcp_v4_send_reset(), commit ba9e04a7ddf4f ("ip: fix tos reflection in ack and reset packets") cleans ECN bits for TW reset and this is not affected. - In tcp_v4_timewait_ack(), ECN bits for all TW ACKs are cleaned. But now only ECN bits of ACKs for oow data or paws_reject are cleaned, and ECN bits of other ACKs will not be cleaned. - In tcp_v4_reqsk_send_ack(), commit 66b13d99d96a1 ("ipv4: tcp: fix TOS value in ACK messages sent from TIME_WAIT") did not clean ECN bits of ACKs for oow data or paws_reject. But now the ECN bits rae cleaned for these ACKs. Signed-off-by: Ilpo Järvinen Signed-off-by: Chia-Yu Chang Signed-off-by: David S. Miller --- include/net/tcp.h | 3 ++- net/ipv4/ip_output.c | 3 +-- net/ipv4/tcp_ipv4.c | 29 +++++++++++++++++++++++------ net/ipv4/tcp_minisocks.c | 2 +- net/ipv6/tcp_ipv6.c | 24 +++++++++++++++++------- 5 files changed, 44 insertions(+), 17 deletions(-) diff --git a/include/net/tcp.h b/include/net/tcp.h index 5520f2d62dc0..c6bdd3d63159 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -419,7 +419,8 @@ enum tcp_tw_status { TCP_TW_SUCCESS = 0, TCP_TW_RST = 1, TCP_TW_ACK = 2, - TCP_TW_SYN = 3 + TCP_TW_SYN = 3, + TCP_TW_ACK_OOW = 4 }; diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c index ea7a260bec8a..6e18d7ec5062 100644 --- a/net/ipv4/ip_output.c +++ b/net/ipv4/ip_output.c @@ -75,7 +75,6 @@ #include #include #include -#include #include #include #include @@ -1640,7 +1639,7 @@ void ip_send_unicast_reply(struct sock *sk, const struct sock *orig_sk, if (IS_ERR(rt)) return; - inet_sk(sk)->tos = arg->tos & ~INET_ECN_MASK; + inet_sk(sk)->tos = arg->tos; sk->sk_protocol = ip_hdr(skb)->protocol; sk->sk_bound_dev_if = arg->bound_dev_if; diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c index 87f270ebc635..4fa4fbb0ad12 100644 --- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -66,6 +66,7 @@ #include #include #include +#include #include #include #include @@ -887,7 +888,8 @@ static void tcp_v4_send_reset(const struct sock *sk, struct sk_buff *skb, BUILD_BUG_ON(offsetof(struct sock, sk_bound_dev_if) != offsetof(struct inet_timewait_sock, tw_bound_dev_if)); - arg.tos = ip_hdr(skb)->tos; + /* ECN bits of TW reset are cleared */ + arg.tos = ip_hdr(skb)->tos & ~INET_ECN_MASK; arg.uid = sock_net_uid(net, sk && sk_fullsock(sk) ? sk : NULL); local_bh_disable(); local_lock_nested_bh(&ipv4_tcp_sk.bh_lock); @@ -1033,11 +1035,21 @@ static void tcp_v4_send_ack(const struct sock *sk, local_bh_enable(); } -static void tcp_v4_timewait_ack(struct sock *sk, struct sk_buff *skb) +static void tcp_v4_timewait_ack(struct sock *sk, struct sk_buff *skb, + enum tcp_tw_status tw_status) { struct inet_timewait_sock *tw = inet_twsk(sk); struct tcp_timewait_sock *tcptw = tcp_twsk(sk); struct tcp_key key = {}; + u8 tos = tw->tw_tos; + + /* Cleaning only ECN bits of TW ACKs of oow data or is paws_reject, + * while not cleaning ECN bits of other TW ACKs to avoid these ACKs + * being placed in a different service queues (Classic rather than L4S) + */ + if (tw_status == TCP_TW_ACK_OOW) + tos &= ~INET_ECN_MASK; + #ifdef CONFIG_TCP_AO struct tcp_ao_info *ao_info; @@ -1081,7 +1093,7 @@ static void tcp_v4_timewait_ack(struct sock *sk, struct sk_buff *skb) READ_ONCE(tcptw->tw_ts_recent), tw->tw_bound_dev_if, &key, tw->tw_transparent ? IP_REPLY_ARG_NOSRCCHECK : 0, - tw->tw_tos, + tos, tw->tw_txhash); inet_twsk_put(tw); @@ -1151,6 +1163,7 @@ static void tcp_v4_reqsk_send_ack(const struct sock *sk, struct sk_buff *skb, key.type = TCP_KEY_MD5; } + /* Cleaning ECN bits of TW ACKs of oow data or is paws_reject */ tcp_v4_send_ack(sk, skb, seq, tcp_rsk(req)->rcv_nxt, tcp_synack_window(req) >> inet_rsk(req)->rcv_wscale, @@ -1158,7 +1171,7 @@ static void tcp_v4_reqsk_send_ack(const struct sock *sk, struct sk_buff *skb, req->ts_recent, 0, &key, inet_rsk(req)->no_srccheck ? IP_REPLY_ARG_NOSRCCHECK : 0, - ip_hdr(skb)->tos, + ip_hdr(skb)->tos & ~INET_ECN_MASK, READ_ONCE(tcp_rsk(req)->txhash)); if (tcp_key_is_ao(&key)) kfree(key.traffic_key); @@ -2175,6 +2188,7 @@ int tcp_v4_rcv(struct sk_buff *skb) { struct net *net = dev_net_rcu(skb->dev); enum skb_drop_reason drop_reason; + enum tcp_tw_status tw_status; int sdif = inet_sdif(skb); int dif = inet_iif(skb); const struct iphdr *iph; @@ -2402,7 +2416,9 @@ 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, &isn)) { + + tw_status = tcp_timewait_state_process(inet_twsk(sk), skb, th, &isn); + switch (tw_status) { case TCP_TW_SYN: { struct sock *sk2 = inet_lookup_listener(net, net->ipv4.tcp_death_row.hashinfo, @@ -2423,7 +2439,8 @@ int tcp_v4_rcv(struct sk_buff *skb) /* to ACK */ fallthrough; case TCP_TW_ACK: - tcp_v4_timewait_ack(sk, skb); + case TCP_TW_ACK_OOW: + tcp_v4_timewait_ack(sk, skb, tw_status); break; case TCP_TW_RST: tcp_v4_send_reset(sk, skb, SK_RST_REASON_TCP_TIMEWAIT_SOCKET); diff --git a/net/ipv4/tcp_minisocks.c b/net/ipv4/tcp_minisocks.c index 0ae24add155b..fb9349be36b8 100644 --- a/net/ipv4/tcp_minisocks.c +++ b/net/ipv4/tcp_minisocks.c @@ -44,7 +44,7 @@ tcp_timewait_check_oow_rate_limit(struct inet_timewait_sock *tw, /* Send ACK. Note, we do not put the bucket, * it will be released by caller. */ - return TCP_TW_ACK; + return TCP_TW_ACK_OOW; } /* We are rate-limiting, so just release the tw sock and drop skb. */ diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c index a2fcc317a88e..e182ee0a2330 100644 --- a/net/ipv6/tcp_ipv6.c +++ b/net/ipv6/tcp_ipv6.c @@ -999,7 +999,7 @@ static void tcp_v6_send_response(const struct sock *sk, struct sk_buff *skb, u32 if (!IS_ERR(dst)) { skb_dst_set(buff, dst); ip6_xmit(ctl_sk, buff, &fl6, fl6.flowi6_mark, NULL, - tclass & ~INET_ECN_MASK, priority); + tclass, priority); TCP_INC_STATS(net, TCP_MIB_OUTSEGS); if (rst) TCP_INC_STATS(net, TCP_MIB_OUTRSTS); @@ -1135,7 +1135,8 @@ static void tcp_v6_send_reset(const struct sock *sk, struct sk_buff *skb, trace_tcp_send_reset(sk, skb, reason); tcp_v6_send_response(sk, skb, seq, ack_seq, 0, 0, 0, oif, 1, - ipv6_get_dsfield(ipv6h), label, priority, txhash, + ipv6_get_dsfield(ipv6h) & ~INET_ECN_MASK, + label, priority, txhash, &key); #if defined(CONFIG_TCP_MD5SIG) || defined(CONFIG_TCP_AO) @@ -1155,11 +1156,16 @@ static void tcp_v6_send_ack(const struct sock *sk, struct sk_buff *skb, u32 seq, tclass, label, priority, txhash, key); } -static void tcp_v6_timewait_ack(struct sock *sk, struct sk_buff *skb) +static void tcp_v6_timewait_ack(struct sock *sk, struct sk_buff *skb, + enum tcp_tw_status tw_status) { struct inet_timewait_sock *tw = inet_twsk(sk); struct tcp_timewait_sock *tcptw = tcp_twsk(sk); + u8 tclass = tw->tw_tclass; struct tcp_key key = {}; + + if (tw_status == TCP_TW_ACK_OOW) + tclass &= ~INET_ECN_MASK; #ifdef CONFIG_TCP_AO struct tcp_ao_info *ao_info; @@ -1203,7 +1209,7 @@ static void tcp_v6_timewait_ack(struct sock *sk, struct sk_buff *skb) tcptw->tw_rcv_wnd >> tw->tw_rcv_wscale, tcp_tw_tsval(tcptw), READ_ONCE(tcptw->tw_ts_recent), tw->tw_bound_dev_if, - &key, tw->tw_tclass, cpu_to_be32(tw->tw_flowlabel), + &key, tclass, cpu_to_be32(tw->tw_flowlabel), tw->tw_priority, tw->tw_txhash); #ifdef CONFIG_TCP_AO @@ -1280,7 +1286,8 @@ static void tcp_v6_reqsk_send_ack(const struct sock *sk, struct sk_buff *skb, tcp_synack_window(req) >> inet_rsk(req)->rcv_wscale, tcp_rsk_tsval(tcp_rsk(req)), req->ts_recent, sk->sk_bound_dev_if, - &key, ipv6_get_dsfield(ipv6_hdr(skb)), 0, + &key, ipv6_get_dsfield(ipv6_hdr(skb)) & ~INET_ECN_MASK, + 0, READ_ONCE(sk->sk_priority), READ_ONCE(tcp_rsk(req)->txhash)); if (tcp_key_is_ao(&key)) @@ -1742,6 +1749,7 @@ INDIRECT_CALLABLE_SCOPE int tcp_v6_rcv(struct sk_buff *skb) { struct net *net = dev_net_rcu(skb->dev); enum skb_drop_reason drop_reason; + enum tcp_tw_status tw_status; int sdif = inet6_sdif(skb); int dif = inet6_iif(skb); const struct tcphdr *th; @@ -1962,7 +1970,8 @@ INDIRECT_CALLABLE_SCOPE int tcp_v6_rcv(struct sk_buff *skb) goto csum_error; } - switch (tcp_timewait_state_process(inet_twsk(sk), skb, th, &isn)) { + tw_status = tcp_timewait_state_process(inet_twsk(sk), skb, th, &isn); + switch (tw_status) { case TCP_TW_SYN: { struct sock *sk2; @@ -1987,7 +1996,8 @@ INDIRECT_CALLABLE_SCOPE int tcp_v6_rcv(struct sk_buff *skb) /* to ACK */ fallthrough; case TCP_TW_ACK: - tcp_v6_timewait_ack(sk, skb); + case TCP_TW_ACK_OOW: + tcp_v6_timewait_ack(sk, skb, tw_status); break; case TCP_TW_RST: tcp_v6_send_reset(sk, skb, SK_RST_REASON_TCP_TIMEWAIT_SOCKET); From 9866884ce8ef25338c5b33cbb97c2b5d92088528 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Ilpo=20J=C3=A4rvinen?= Date: Wed, 5 Mar 2025 23:38:52 +0100 Subject: [PATCH 11/11] tcp: Pass flags to __tcp_send_ack MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Accurate ECN needs to send custom flags to handle IP-ECN field reflection during handshake. Signed-off-by: Ilpo Järvinen Signed-off-by: Chia-Yu Chang Reviewed-by: Eric Dumazet Signed-off-by: David S. Miller --- include/net/tcp.h | 2 +- net/ipv4/bpf_tcp_ca.c | 2 +- net/ipv4/tcp_dctcp.h | 2 +- net/ipv4/tcp_output.c | 6 +++--- 4 files changed, 6 insertions(+), 6 deletions(-) diff --git a/include/net/tcp.h b/include/net/tcp.h index c6bdd3d63159..d08fbf90495d 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -707,7 +707,7 @@ void tcp_send_active_reset(struct sock *sk, gfp_t priority, enum sk_rst_reason reason); int tcp_send_synack(struct sock *); void tcp_push_one(struct sock *, unsigned int mss_now); -void __tcp_send_ack(struct sock *sk, u32 rcv_nxt); +void __tcp_send_ack(struct sock *sk, u32 rcv_nxt, u16 flags); void tcp_send_ack(struct sock *sk); void tcp_send_delayed_ack(struct sock *sk); void tcp_send_loss_probe(struct sock *sk); diff --git a/net/ipv4/bpf_tcp_ca.c b/net/ipv4/bpf_tcp_ca.c index 554804774628..e01492234b0b 100644 --- a/net/ipv4/bpf_tcp_ca.c +++ b/net/ipv4/bpf_tcp_ca.c @@ -121,7 +121,7 @@ static int bpf_tcp_ca_btf_struct_access(struct bpf_verifier_log *log, BPF_CALL_2(bpf_tcp_send_ack, struct tcp_sock *, tp, u32, rcv_nxt) { /* bpf_tcp_ca prog cannot have NULL tp */ - __tcp_send_ack((struct sock *)tp, rcv_nxt); + __tcp_send_ack((struct sock *)tp, rcv_nxt, 0); return 0; } diff --git a/net/ipv4/tcp_dctcp.h b/net/ipv4/tcp_dctcp.h index d69a77cbd0c7..4b0259111d81 100644 --- a/net/ipv4/tcp_dctcp.h +++ b/net/ipv4/tcp_dctcp.h @@ -28,7 +28,7 @@ static inline void dctcp_ece_ack_update(struct sock *sk, enum tcp_ca_event evt, */ if (inet_csk(sk)->icsk_ack.pending & ICSK_ACK_TIMER) { dctcp_ece_ack_cwr(sk, *ce_state); - __tcp_send_ack(sk, *prior_rcv_nxt); + __tcp_send_ack(sk, *prior_rcv_nxt, 0); } inet_csk(sk)->icsk_ack.pending |= ICSK_ACK_NOW; } diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index fffbd3ee44ed..e0a4e5432399 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -4240,7 +4240,7 @@ void tcp_send_delayed_ack(struct sock *sk) } /* This routine sends an ack and also updates the window. */ -void __tcp_send_ack(struct sock *sk, u32 rcv_nxt) +void __tcp_send_ack(struct sock *sk, u32 rcv_nxt, u16 flags) { struct sk_buff *buff; @@ -4269,7 +4269,7 @@ void __tcp_send_ack(struct sock *sk, u32 rcv_nxt) /* Reserve space for headers and prepare control bits. */ skb_reserve(buff, MAX_TCP_HEADER); - tcp_init_nondata_skb(buff, tcp_acceptable_seq(sk), TCPHDR_ACK); + tcp_init_nondata_skb(buff, tcp_acceptable_seq(sk), TCPHDR_ACK | flags); /* We do not want pure acks influencing TCP Small Queues or fq/pacing * too much. @@ -4284,7 +4284,7 @@ EXPORT_SYMBOL_GPL(__tcp_send_ack); void tcp_send_ack(struct sock *sk) { - __tcp_send_ack(sk, tcp_sk(sk)->rcv_nxt); + __tcp_send_ack(sk, tcp_sk(sk)->rcv_nxt, 0); } /* This routine sends a packet with an out of date sequence