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Diffstat (limited to 'include/net/tcp.h')
| -rw-r--r-- | include/net/tcp.h | 2540 |
1 files changed, 2540 insertions, 0 deletions
diff --git a/include/net/tcp.h b/include/net/tcp.h new file mode 100644 index 000000000..9cbcfb3c9 --- /dev/null +++ b/include/net/tcp.h @@ -0,0 +1,2540 @@ +/* SPDX-License-Identifier: GPL-2.0-or-later */ +/* + * INET An implementation of the TCP/IP protocol suite for the LINUX + * operating system. INET is implemented using the BSD Socket + * interface as the means of communication with the user level. + * + * Definitions for the TCP module. + * + * Version: @(#)tcp.h 1.0.5 05/23/93 + * + * Authors: Ross Biro + * Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG> + */ +#ifndef _TCP_H +#define _TCP_H + +#define FASTRETRANS_DEBUG 1 + +#include <linux/list.h> +#include <linux/tcp.h> +#include <linux/bug.h> +#include <linux/slab.h> +#include <linux/cache.h> +#include <linux/percpu.h> +#include <linux/skbuff.h> +#include <linux/kref.h> +#include <linux/ktime.h> +#include <linux/indirect_call_wrapper.h> + +#include <net/inet_connection_sock.h> +#include <net/inet_timewait_sock.h> +#include <net/inet_hashtables.h> +#include <net/checksum.h> +#include <net/request_sock.h> +#include <net/sock_reuseport.h> +#include <net/sock.h> +#include <net/snmp.h> +#include <net/ip.h> +#include <net/tcp_states.h> +#include <net/inet_ecn.h> +#include <net/dst.h> +#include <net/mptcp.h> + +#include <linux/seq_file.h> +#include <linux/memcontrol.h> +#include <linux/bpf-cgroup.h> +#include <linux/siphash.h> + +extern struct inet_hashinfo tcp_hashinfo; + +DECLARE_PER_CPU(unsigned int, tcp_orphan_count); +int tcp_orphan_count_sum(void); + +void tcp_time_wait(struct sock *sk, int state, int timeo); + +#define MAX_TCP_HEADER L1_CACHE_ALIGN(128 + MAX_HEADER) +#define MAX_TCP_OPTION_SPACE 40 +#define TCP_MIN_SND_MSS 48 +#define TCP_MIN_GSO_SIZE (TCP_MIN_SND_MSS - MAX_TCP_OPTION_SPACE) + +/* + * Never offer a window over 32767 without using window scaling. Some + * poor stacks do signed 16bit maths! + */ +#define MAX_TCP_WINDOW 32767U + +/* Minimal accepted MSS. It is (60+60+8) - (20+20). */ +#define TCP_MIN_MSS 88U + +/* The initial MTU to use for probing */ +#define TCP_BASE_MSS 1024 + +/* probing interval, default to 10 minutes as per RFC4821 */ +#define TCP_PROBE_INTERVAL 600 + +/* Specify interval when tcp mtu probing will stop */ +#define TCP_PROBE_THRESHOLD 8 + +/* After receiving this amount of duplicate ACKs fast retransmit starts. */ +#define TCP_FASTRETRANS_THRESH 3 + +/* Maximal number of ACKs sent quickly to accelerate slow-start. */ +#define TCP_MAX_QUICKACKS 16U + +/* Maximal number of window scale according to RFC1323 */ +#define TCP_MAX_WSCALE 14U + +/* urg_data states */ +#define TCP_URG_VALID 0x0100 +#define TCP_URG_NOTYET 0x0200 +#define TCP_URG_READ 0x0400 + +#define TCP_RETR1 3 /* + * This is how many retries it does before it + * tries to figure out if the gateway is + * down. Minimal RFC value is 3; it corresponds + * to ~3sec-8min depending on RTO. + */ + +#define TCP_RETR2 15 /* + * This should take at least + * 90 minutes to time out. + * RFC1122 says that the limit is 100 sec. + * 15 is ~13-30min depending on RTO. + */ + +#define TCP_SYN_RETRIES 6 /* This is how many retries are done + * when active opening a connection. + * RFC1122 says the minimum retry MUST + * be at least 180secs. Nevertheless + * this value is corresponding to + * 63secs of retransmission with the + * current initial RTO. + */ + +#define TCP_SYNACK_RETRIES 5 /* This is how may retries are done + * when passive opening a connection. + * This is corresponding to 31secs of + * retransmission with the current + * initial RTO. + */ + +#define TCP_TIMEWAIT_LEN (60*HZ) /* how long to wait to destroy TIME-WAIT + * state, about 60 seconds */ +#define TCP_FIN_TIMEOUT TCP_TIMEWAIT_LEN + /* BSD style FIN_WAIT2 deadlock breaker. + * It used to be 3min, new value is 60sec, + * to combine FIN-WAIT-2 timeout with + * TIME-WAIT timer. + */ +#define TCP_FIN_TIMEOUT_MAX (120 * HZ) /* max TCP_LINGER2 value (two minutes) */ + +#define TCP_DELACK_MAX ((unsigned)(HZ/5)) /* maximal time to delay before sending an ACK */ +#if HZ >= 100 +#define TCP_DELACK_MIN ((unsigned)(HZ/25)) /* minimal time to delay before sending an ACK */ +#define TCP_ATO_MIN ((unsigned)(HZ/25)) +#else +#define TCP_DELACK_MIN 4U +#define TCP_ATO_MIN 4U +#endif +#define TCP_RTO_MAX ((unsigned)(120*HZ)) +#define TCP_RTO_MIN ((unsigned)(HZ/5)) +#define TCP_TIMEOUT_MIN (2U) /* Min timeout for TCP timers in jiffies */ + +#define TCP_TIMEOUT_MIN_US (2*USEC_PER_MSEC) /* Min TCP timeout in microsecs */ + +#define TCP_TIMEOUT_INIT ((unsigned)(1*HZ)) /* RFC6298 2.1 initial RTO value */ +#define TCP_TIMEOUT_FALLBACK ((unsigned)(3*HZ)) /* RFC 1122 initial RTO value, now + * used as a fallback RTO for the + * initial data transmission if no + * valid RTT sample has been acquired, + * most likely due to retrans in 3WHS. + */ + +#define TCP_RESOURCE_PROBE_INTERVAL ((unsigned)(HZ/2U)) /* Maximal interval between probes + * for local resources. + */ +#define TCP_KEEPALIVE_TIME (120*60*HZ) /* two hours */ +#define TCP_KEEPALIVE_PROBES 9 /* Max of 9 keepalive probes */ +#define TCP_KEEPALIVE_INTVL (75*HZ) + +#define MAX_TCP_KEEPIDLE 32767 +#define MAX_TCP_KEEPINTVL 32767 +#define MAX_TCP_KEEPCNT 127 +#define MAX_TCP_SYNCNT 127 + +#define TCP_PAWS_24DAYS (60 * 60 * 24 * 24) +#define TCP_PAWS_MSL 60 /* Per-host timestamps are invalidated + * after this time. It should be equal + * (or greater than) TCP_TIMEWAIT_LEN + * to provide reliability equal to one + * provided by timewait state. + */ +#define TCP_PAWS_WINDOW 1 /* Replay window for per-host + * timestamps. It must be less than + * minimal timewait lifetime. + */ +/* + * TCP option + */ + +#define TCPOPT_NOP 1 /* Padding */ +#define TCPOPT_EOL 0 /* End of options */ +#define TCPOPT_MSS 2 /* Segment size negotiating */ +#define TCPOPT_WINDOW 3 /* Window scaling */ +#define TCPOPT_SACK_PERM 4 /* SACK Permitted */ +#define TCPOPT_SACK 5 /* SACK Block */ +#define TCPOPT_TIMESTAMP 8 /* Better RTT estimations/PAWS */ +#define TCPOPT_MD5SIG 19 /* MD5 Signature (RFC2385) */ +#define TCPOPT_MPTCP 30 /* Multipath TCP (RFC6824) */ +#define TCPOPT_FASTOPEN 34 /* Fast open (RFC7413) */ +#define TCPOPT_EXP 254 /* Experimental */ +/* Magic number to be after the option value for sharing TCP + * experimental options. See draft-ietf-tcpm-experimental-options-00.txt + */ +#define TCPOPT_FASTOPEN_MAGIC 0xF989 +#define TCPOPT_SMC_MAGIC 0xE2D4C3D9 + +/* + * TCP option lengths + */ + +#define TCPOLEN_MSS 4 +#define TCPOLEN_WINDOW 3 +#define TCPOLEN_SACK_PERM 2 +#define TCPOLEN_TIMESTAMP 10 +#define TCPOLEN_MD5SIG 18 +#define TCPOLEN_FASTOPEN_BASE 2 +#define TCPOLEN_EXP_FASTOPEN_BASE 4 +#define TCPOLEN_EXP_SMC_BASE 6 + +/* But this is what stacks really send out. */ +#define TCPOLEN_TSTAMP_ALIGNED 12 +#define TCPOLEN_WSCALE_ALIGNED 4 +#define TCPOLEN_SACKPERM_ALIGNED 4 +#define TCPOLEN_SACK_BASE 2 +#define TCPOLEN_SACK_BASE_ALIGNED 4 +#define TCPOLEN_SACK_PERBLOCK 8 +#define TCPOLEN_MD5SIG_ALIGNED 20 +#define TCPOLEN_MSS_ALIGNED 4 +#define TCPOLEN_EXP_SMC_BASE_ALIGNED 8 + +/* Flags in tp->nonagle */ +#define TCP_NAGLE_OFF 1 /* Nagle's algo is disabled */ +#define TCP_NAGLE_CORK 2 /* Socket is corked */ +#define TCP_NAGLE_PUSH 4 /* Cork is overridden for already queued data */ + +/* TCP thin-stream limits */ +#define TCP_THIN_LINEAR_RETRIES 6 /* After 6 linear retries, do exp. backoff */ + +/* TCP initial congestion window as per rfc6928 */ +#define TCP_INIT_CWND 10 + +/* Bit Flags for sysctl_tcp_fastopen */ +#define TFO_CLIENT_ENABLE 1 +#define TFO_SERVER_ENABLE 2 +#define TFO_CLIENT_NO_COOKIE 4 /* Data in SYN w/o cookie option */ + +/* Accept SYN data w/o any cookie option */ +#define TFO_SERVER_COOKIE_NOT_REQD 0x200 + +/* Force enable TFO on all listeners, i.e., not requiring the + * TCP_FASTOPEN socket option. + */ +#define TFO_SERVER_WO_SOCKOPT1 0x400 + + +/* sysctl variables for tcp */ +extern int sysctl_tcp_max_orphans; +extern long sysctl_tcp_mem[3]; + +#define TCP_RACK_LOSS_DETECTION 0x1 /* Use RACK to detect losses */ +#define TCP_RACK_STATIC_REO_WND 0x2 /* Use static RACK reo wnd */ +#define TCP_RACK_NO_DUPTHRESH 0x4 /* Do not use DUPACK threshold in RACK */ + +extern atomic_long_t tcp_memory_allocated; +DECLARE_PER_CPU(int, tcp_memory_per_cpu_fw_alloc); + +extern struct percpu_counter tcp_sockets_allocated; +extern unsigned long tcp_memory_pressure; + +/* optimized version of sk_under_memory_pressure() for TCP sockets */ +static inline bool tcp_under_memory_pressure(const struct sock *sk) +{ + if (mem_cgroup_sockets_enabled && sk->sk_memcg && + mem_cgroup_under_socket_pressure(sk->sk_memcg)) + return true; + + return READ_ONCE(tcp_memory_pressure); +} +/* + * The next routines deal with comparing 32 bit unsigned ints + * and worry about wraparound (automatic with unsigned arithmetic). + */ + +static inline bool before(__u32 seq1, __u32 seq2) +{ + return (__s32)(seq1-seq2) < 0; +} +#define after(seq2, seq1) before(seq1, seq2) + +/* is s2<=s1<=s3 ? */ +static inline bool between(__u32 seq1, __u32 seq2, __u32 seq3) +{ + return seq3 - seq2 >= seq1 - seq2; +} + +static inline bool tcp_out_of_memory(struct sock *sk) +{ + if (sk->sk_wmem_queued > SOCK_MIN_SNDBUF && + sk_memory_allocated(sk) > sk_prot_mem_limits(sk, 2)) + return true; + return false; +} + +static inline void tcp_wmem_free_skb(struct sock *sk, struct sk_buff *skb) +{ + sk_wmem_queued_add(sk, -skb->truesize); + if (!skb_zcopy_pure(skb)) + sk_mem_uncharge(sk, skb->truesize); + else + sk_mem_uncharge(sk, SKB_TRUESIZE(skb_end_offset(skb))); + __kfree_skb(skb); +} + +void sk_forced_mem_schedule(struct sock *sk, int size); + +bool tcp_check_oom(struct sock *sk, int shift); + + +extern struct proto tcp_prot; + +#define TCP_INC_STATS(net, field) SNMP_INC_STATS((net)->mib.tcp_statistics, field) +#define __TCP_INC_STATS(net, field) __SNMP_INC_STATS((net)->mib.tcp_statistics, field) +#define TCP_DEC_STATS(net, field) SNMP_DEC_STATS((net)->mib.tcp_statistics, field) +#define TCP_ADD_STATS(net, field, val) SNMP_ADD_STATS((net)->mib.tcp_statistics, field, val) + +void tcp_tasklet_init(void); + +int tcp_v4_err(struct sk_buff *skb, u32); + +void tcp_shutdown(struct sock *sk, int how); + +int tcp_v4_early_demux(struct sk_buff *skb); +int tcp_v4_rcv(struct sk_buff *skb); + +void tcp_remove_empty_skb(struct sock *sk); +int tcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t size); +int tcp_sendmsg_locked(struct sock *sk, struct msghdr *msg, size_t size); +int tcp_sendmsg_fastopen(struct sock *sk, struct msghdr *msg, int *copied, + size_t size, struct ubuf_info *uarg); +void tcp_splice_eof(struct socket *sock); +int tcp_send_mss(struct sock *sk, int *size_goal, int flags); +int tcp_wmem_schedule(struct sock *sk, int copy); +void tcp_push(struct sock *sk, int flags, int mss_now, int nonagle, + int size_goal); +void tcp_release_cb(struct sock *sk); +void tcp_wfree(struct sk_buff *skb); +void tcp_write_timer_handler(struct sock *sk); +void tcp_delack_timer_handler(struct sock *sk); +int tcp_ioctl(struct sock *sk, int cmd, int *karg); +int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb); +void tcp_rcv_established(struct sock *sk, struct sk_buff *skb); +void tcp_rcv_space_adjust(struct sock *sk); +int tcp_twsk_unique(struct sock *sk, struct sock *sktw, void *twp); +void tcp_twsk_destructor(struct sock *sk); +void tcp_twsk_purge(struct list_head *net_exit_list, int family); +ssize_t tcp_splice_read(struct socket *sk, loff_t *ppos, + struct pipe_inode_info *pipe, size_t len, + unsigned int flags); +struct sk_buff *tcp_stream_alloc_skb(struct sock *sk, gfp_t gfp, + bool force_schedule); + +static inline void tcp_dec_quickack_mode(struct sock *sk) +{ + struct inet_connection_sock *icsk = inet_csk(sk); + + if (icsk->icsk_ack.quick) { + /* How many ACKs S/ACKing new data have we sent? */ + const unsigned int pkts = inet_csk_ack_scheduled(sk) ? 1 : 0; + + if (pkts >= icsk->icsk_ack.quick) { + icsk->icsk_ack.quick = 0; + /* Leaving quickack mode we deflate ATO. */ + icsk->icsk_ack.ato = TCP_ATO_MIN; + } else + icsk->icsk_ack.quick -= pkts; + } +} + +#define TCP_ECN_OK 1 +#define TCP_ECN_QUEUE_CWR 2 +#define TCP_ECN_DEMAND_CWR 4 +#define TCP_ECN_SEEN 8 + +enum tcp_tw_status { + TCP_TW_SUCCESS = 0, + TCP_TW_RST = 1, + TCP_TW_ACK = 2, + TCP_TW_SYN = 3 +}; + + +enum tcp_tw_status tcp_timewait_state_process(struct inet_timewait_sock *tw, + struct sk_buff *skb, + const struct tcphdr *th); +struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb, + struct request_sock *req, bool fastopen, + bool *lost_race); +int tcp_child_process(struct sock *parent, struct sock *child, + struct sk_buff *skb); +void tcp_enter_loss(struct sock *sk); +void tcp_cwnd_reduction(struct sock *sk, int newly_acked_sacked, int newly_lost, int flag); +void tcp_clear_retrans(struct tcp_sock *tp); +void tcp_update_metrics(struct sock *sk); +void tcp_init_metrics(struct sock *sk); +void tcp_metrics_init(void); +bool tcp_peer_is_proven(struct request_sock *req, struct dst_entry *dst); +void __tcp_close(struct sock *sk, long timeout); +void tcp_close(struct sock *sk, long timeout); +void tcp_init_sock(struct sock *sk); +void tcp_init_transfer(struct sock *sk, int bpf_op, struct sk_buff *skb); +__poll_t tcp_poll(struct file *file, struct socket *sock, + struct poll_table_struct *wait); +int do_tcp_getsockopt(struct sock *sk, int level, + int optname, sockptr_t optval, sockptr_t optlen); +int tcp_getsockopt(struct sock *sk, int level, int optname, + char __user *optval, int __user *optlen); +bool tcp_bpf_bypass_getsockopt(int level, int optname); +int do_tcp_setsockopt(struct sock *sk, int level, int optname, + sockptr_t optval, unsigned int optlen); +int tcp_setsockopt(struct sock *sk, int level, int optname, sockptr_t optval, + unsigned int optlen); +void tcp_set_keepalive(struct sock *sk, int val); +void tcp_syn_ack_timeout(const struct request_sock *req); +int tcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, + int flags, int *addr_len); +int tcp_set_rcvlowat(struct sock *sk, int val); +int tcp_set_window_clamp(struct sock *sk, int val); +void tcp_update_recv_tstamps(struct sk_buff *skb, + struct scm_timestamping_internal *tss); +void tcp_recv_timestamp(struct msghdr *msg, const struct sock *sk, + struct scm_timestamping_internal *tss); +void tcp_data_ready(struct sock *sk); +#ifdef CONFIG_MMU +int tcp_mmap(struct file *file, struct socket *sock, + struct vm_area_struct *vma); +#endif +void tcp_parse_options(const struct net *net, const struct sk_buff *skb, + struct tcp_options_received *opt_rx, + int estab, struct tcp_fastopen_cookie *foc); +const u8 *tcp_parse_md5sig_option(const struct tcphdr *th); + +/* + * BPF SKB-less helpers + */ +u16 tcp_v4_get_syncookie(struct sock *sk, struct iphdr *iph, + struct tcphdr *th, u32 *cookie); +u16 tcp_v6_get_syncookie(struct sock *sk, struct ipv6hdr *iph, + struct tcphdr *th, u32 *cookie); +u16 tcp_parse_mss_option(const struct tcphdr *th, u16 user_mss); +u16 tcp_get_syncookie_mss(struct request_sock_ops *rsk_ops, + const struct tcp_request_sock_ops *af_ops, + struct sock *sk, struct tcphdr *th); +/* + * TCP v4 functions exported for the inet6 API + */ + +void tcp_v4_send_check(struct sock *sk, struct sk_buff *skb); +void tcp_v4_mtu_reduced(struct sock *sk); +void tcp_req_err(struct sock *sk, u32 seq, bool abort); +void tcp_ld_RTO_revert(struct sock *sk, u32 seq); +int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb); +struct sock *tcp_create_openreq_child(const struct sock *sk, + struct request_sock *req, + struct sk_buff *skb); +void tcp_ca_openreq_child(struct sock *sk, const struct dst_entry *dst); +struct sock *tcp_v4_syn_recv_sock(const struct sock *sk, struct sk_buff *skb, + struct request_sock *req, + struct dst_entry *dst, + struct request_sock *req_unhash, + bool *own_req); +int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb); +int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len); +int tcp_connect(struct sock *sk); +enum tcp_synack_type { + TCP_SYNACK_NORMAL, + TCP_SYNACK_FASTOPEN, + TCP_SYNACK_COOKIE, +}; +struct sk_buff *tcp_make_synack(const struct sock *sk, struct dst_entry *dst, + struct request_sock *req, + struct tcp_fastopen_cookie *foc, + enum tcp_synack_type synack_type, + struct sk_buff *syn_skb); +int tcp_disconnect(struct sock *sk, int flags); + +void tcp_finish_connect(struct sock *sk, struct sk_buff *skb); +int tcp_send_rcvq(struct sock *sk, struct msghdr *msg, size_t size); +void inet_sk_rx_dst_set(struct sock *sk, const struct sk_buff *skb); + +/* From syncookies.c */ +struct sock *tcp_get_cookie_sock(struct sock *sk, struct sk_buff *skb, + struct request_sock *req, + struct dst_entry *dst, u32 tsoff); +int __cookie_v4_check(const struct iphdr *iph, const struct tcphdr *th, + u32 cookie); +struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb); +struct request_sock *cookie_tcp_reqsk_alloc(const struct request_sock_ops *ops, + const struct tcp_request_sock_ops *af_ops, + struct sock *sk, struct sk_buff *skb); +#ifdef CONFIG_SYN_COOKIES + +/* Syncookies use a monotonic timer which increments every 60 seconds. + * This counter is used both as a hash input and partially encoded into + * the cookie value. A cookie is only validated further if the delta + * between the current counter value and the encoded one is less than this, + * i.e. a sent cookie is valid only at most for 2*60 seconds (or less if + * the counter advances immediately after a cookie is generated). + */ +#define MAX_SYNCOOKIE_AGE 2 +#define TCP_SYNCOOKIE_PERIOD (60 * HZ) +#define TCP_SYNCOOKIE_VALID (MAX_SYNCOOKIE_AGE * TCP_SYNCOOKIE_PERIOD) + +/* syncookies: remember time of last synqueue overflow + * But do not dirty this field too often (once per second is enough) + * It is racy as we do not hold a lock, but race is very minor. + */ +static inline void tcp_synq_overflow(const struct sock *sk) +{ + unsigned int last_overflow; + unsigned int now = jiffies; + + if (sk->sk_reuseport) { + struct sock_reuseport *reuse; + + reuse = rcu_dereference(sk->sk_reuseport_cb); + if (likely(reuse)) { + last_overflow = READ_ONCE(reuse->synq_overflow_ts); + if (!time_between32(now, last_overflow, + last_overflow + HZ)) + WRITE_ONCE(reuse->synq_overflow_ts, now); + return; + } + } + + last_overflow = READ_ONCE(tcp_sk(sk)->rx_opt.ts_recent_stamp); + if (!time_between32(now, last_overflow, last_overflow + HZ)) + WRITE_ONCE(tcp_sk_rw(sk)->rx_opt.ts_recent_stamp, now); +} + +/* syncookies: no recent synqueue overflow on this listening socket? */ +static inline bool tcp_synq_no_recent_overflow(const struct sock *sk) +{ + unsigned int last_overflow; + unsigned int now = jiffies; + + if (sk->sk_reuseport) { + struct sock_reuseport *reuse; + + reuse = rcu_dereference(sk->sk_reuseport_cb); + if (likely(reuse)) { + last_overflow = READ_ONCE(reuse->synq_overflow_ts); + return !time_between32(now, last_overflow - HZ, + last_overflow + + TCP_SYNCOOKIE_VALID); + } + } + + last_overflow = READ_ONCE(tcp_sk(sk)->rx_opt.ts_recent_stamp); + + /* If last_overflow <= jiffies <= last_overflow + TCP_SYNCOOKIE_VALID, + * then we're under synflood. However, we have to use + * 'last_overflow - HZ' as lower bound. That's because a concurrent + * tcp_synq_overflow() could update .ts_recent_stamp after we read + * jiffies but before we store .ts_recent_stamp into last_overflow, + * which could lead to rejecting a valid syncookie. + */ + return !time_between32(now, last_overflow - HZ, + last_overflow + TCP_SYNCOOKIE_VALID); +} + +static inline u32 tcp_cookie_time(void) +{ + u64 val = get_jiffies_64(); + + do_div(val, TCP_SYNCOOKIE_PERIOD); + return val; +} + +u32 __cookie_v4_init_sequence(const struct iphdr *iph, const struct tcphdr *th, + u16 *mssp); +__u32 cookie_v4_init_sequence(const struct sk_buff *skb, __u16 *mss); +u64 cookie_init_timestamp(struct request_sock *req, u64 now); +bool cookie_timestamp_decode(const struct net *net, + struct tcp_options_received *opt); +bool cookie_ecn_ok(const struct tcp_options_received *opt, + const struct net *net, const struct dst_entry *dst); + +/* From net/ipv6/syncookies.c */ +int __cookie_v6_check(const struct ipv6hdr *iph, const struct tcphdr *th, + u32 cookie); +struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb); + +u32 __cookie_v6_init_sequence(const struct ipv6hdr *iph, + const struct tcphdr *th, u16 *mssp); +__u32 cookie_v6_init_sequence(const struct sk_buff *skb, __u16 *mss); +#endif +/* tcp_output.c */ + +void tcp_skb_entail(struct sock *sk, struct sk_buff *skb); +void tcp_mark_push(struct tcp_sock *tp, struct sk_buff *skb); +void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss, + int nonagle); +int __tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs); +int tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs); +void tcp_retransmit_timer(struct sock *sk); +void tcp_xmit_retransmit_queue(struct sock *); +void tcp_simple_retransmit(struct sock *); +void tcp_enter_recovery(struct sock *sk, bool ece_ack); +int tcp_trim_head(struct sock *, struct sk_buff *, u32); +enum tcp_queue { + TCP_FRAG_IN_WRITE_QUEUE, + TCP_FRAG_IN_RTX_QUEUE, +}; +int tcp_fragment(struct sock *sk, enum tcp_queue tcp_queue, + struct sk_buff *skb, u32 len, + unsigned int mss_now, gfp_t gfp); + +void tcp_send_probe0(struct sock *); +int tcp_write_wakeup(struct sock *, int mib); +void tcp_send_fin(struct sock *sk); +void tcp_send_active_reset(struct sock *sk, gfp_t priority); +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); +void tcp_send_delayed_ack(struct sock *sk); +void tcp_send_loss_probe(struct sock *sk); +bool tcp_schedule_loss_probe(struct sock *sk, bool advancing_rto); +void tcp_skb_collapse_tstamp(struct sk_buff *skb, + const struct sk_buff *next_skb); + +/* tcp_input.c */ +void tcp_rearm_rto(struct sock *sk); +void tcp_synack_rtt_meas(struct sock *sk, struct request_sock *req); +void tcp_reset(struct sock *sk, struct sk_buff *skb); +void tcp_fin(struct sock *sk); +void tcp_check_space(struct sock *sk); +void tcp_sack_compress_send_ack(struct sock *sk); + +/* tcp_timer.c */ +void tcp_init_xmit_timers(struct sock *); +static inline void tcp_clear_xmit_timers(struct sock *sk) +{ + if (hrtimer_try_to_cancel(&tcp_sk(sk)->pacing_timer) == 1) + __sock_put(sk); + + if (hrtimer_try_to_cancel(&tcp_sk(sk)->compressed_ack_timer) == 1) + __sock_put(sk); + + inet_csk_clear_xmit_timers(sk); +} + +unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu); +unsigned int tcp_current_mss(struct sock *sk); +u32 tcp_clamp_probe0_to_user_timeout(const struct sock *sk, u32 when); + +/* Bound MSS / TSO packet size with the half of the window */ +static inline int tcp_bound_to_half_wnd(struct tcp_sock *tp, int pktsize) +{ + int cutoff; + + /* When peer uses tiny windows, there is no use in packetizing + * to sub-MSS pieces for the sake of SWS or making sure there + * are enough packets in the pipe for fast recovery. + * + * On the other hand, for extremely large MSS devices, handling + * smaller than MSS windows in this way does make sense. + */ + if (tp->max_window > TCP_MSS_DEFAULT) + cutoff = (tp->max_window >> 1); + else + cutoff = tp->max_window; + + if (cutoff && pktsize > cutoff) + return max_t(int, cutoff, 68U - tp->tcp_header_len); + else + return pktsize; +} + +/* tcp.c */ +void tcp_get_info(struct sock *, struct tcp_info *); + +/* Read 'sendfile()'-style from a TCP socket */ +int tcp_read_sock(struct sock *sk, read_descriptor_t *desc, + sk_read_actor_t recv_actor); +int tcp_read_skb(struct sock *sk, skb_read_actor_t recv_actor); +struct sk_buff *tcp_recv_skb(struct sock *sk, u32 seq, u32 *off); +void tcp_read_done(struct sock *sk, size_t len); + +void tcp_initialize_rcv_mss(struct sock *sk); + +int tcp_mtu_to_mss(struct sock *sk, int pmtu); +int tcp_mss_to_mtu(struct sock *sk, int mss); +void tcp_mtup_init(struct sock *sk); + +static inline void tcp_bound_rto(const struct sock *sk) +{ + if (inet_csk(sk)->icsk_rto > TCP_RTO_MAX) + inet_csk(sk)->icsk_rto = TCP_RTO_MAX; +} + +static inline u32 __tcp_set_rto(const struct tcp_sock *tp) +{ + return usecs_to_jiffies((tp->srtt_us >> 3) + tp->rttvar_us); +} + +static inline void __tcp_fast_path_on(struct tcp_sock *tp, u32 snd_wnd) +{ + /* mptcp hooks are only on the slow path */ + if (sk_is_mptcp((struct sock *)tp)) + return; + + tp->pred_flags = htonl((tp->tcp_header_len << 26) | + ntohl(TCP_FLAG_ACK) | + snd_wnd); +} + +static inline void tcp_fast_path_on(struct tcp_sock *tp) +{ + __tcp_fast_path_on(tp, tp->snd_wnd >> tp->rx_opt.snd_wscale); +} + +static inline void tcp_fast_path_check(struct sock *sk) +{ + struct tcp_sock *tp = tcp_sk(sk); + + if (RB_EMPTY_ROOT(&tp->out_of_order_queue) && + tp->rcv_wnd && + atomic_read(&sk->sk_rmem_alloc) < sk->sk_rcvbuf && + !tp->urg_data) + tcp_fast_path_on(tp); +} + +u32 tcp_delack_max(const struct sock *sk); + +/* Compute the actual rto_min value */ +static inline u32 tcp_rto_min(struct sock *sk) +{ + const struct dst_entry *dst = __sk_dst_get(sk); + u32 rto_min = inet_csk(sk)->icsk_rto_min; + + if (dst && dst_metric_locked(dst, RTAX_RTO_MIN)) + rto_min = dst_metric_rtt(dst, RTAX_RTO_MIN); + return rto_min; +} + +static inline u32 tcp_rto_min_us(struct sock *sk) +{ + return jiffies_to_usecs(tcp_rto_min(sk)); +} + +static inline bool tcp_ca_dst_locked(const struct dst_entry *dst) +{ + return dst_metric_locked(dst, RTAX_CC_ALGO); +} + +/* Minimum RTT in usec. ~0 means not available. */ +static inline u32 tcp_min_rtt(const struct tcp_sock *tp) +{ + return minmax_get(&tp->rtt_min); +} + +/* Compute the actual receive window we are currently advertising. + * Rcv_nxt can be after the window if our peer push more data + * than the offered window. + */ +static inline u32 tcp_receive_window(const struct tcp_sock *tp) +{ + s32 win = tp->rcv_wup + tp->rcv_wnd - tp->rcv_nxt; + + if (win < 0) + win = 0; + return (u32) win; +} + +/* Choose a new window, without checks for shrinking, and without + * scaling applied to the result. The caller does these things + * if necessary. This is a "raw" window selection. + */ +u32 __tcp_select_window(struct sock *sk); + +void tcp_send_window_probe(struct sock *sk); + +/* TCP uses 32bit jiffies to save some space. + * Note that this is different from tcp_time_stamp, which + * historically has been the same until linux-4.13. + */ +#define tcp_jiffies32 ((u32)jiffies) + +/* + * Deliver a 32bit value for TCP timestamp option (RFC 7323) + * It is no longer tied to jiffies, but to 1 ms clock. + * Note: double check if you want to use tcp_jiffies32 instead of this. + */ +#define TCP_TS_HZ 1000 + +static inline u64 tcp_clock_ns(void) +{ + return ktime_get_ns(); +} + +static inline u64 tcp_clock_us(void) +{ + return div_u64(tcp_clock_ns(), NSEC_PER_USEC); +} + +/* This should only be used in contexts where tp->tcp_mstamp is up to date */ +static inline u32 tcp_time_stamp(const struct tcp_sock *tp) +{ + return div_u64(tp->tcp_mstamp, USEC_PER_SEC / TCP_TS_HZ); +} + +/* Convert a nsec timestamp into TCP TSval timestamp (ms based currently) */ +static inline u64 tcp_ns_to_ts(u64 ns) +{ + return div_u64(ns, NSEC_PER_SEC / TCP_TS_HZ); +} + +/* Could use tcp_clock_us() / 1000, but this version uses a single divide */ +static inline u32 tcp_time_stamp_raw(void) +{ + return tcp_ns_to_ts(tcp_clock_ns()); +} + +void tcp_mstamp_refresh(struct tcp_sock *tp); + +static inline u32 tcp_stamp_us_delta(u64 t1, u64 t0) +{ + return max_t(s64, t1 - t0, 0); +} + +static inline u32 tcp_skb_timestamp(const struct sk_buff *skb) +{ + return tcp_ns_to_ts(skb->skb_mstamp_ns); +} + +/* provide the departure time in us unit */ +static inline u64 tcp_skb_timestamp_us(const struct sk_buff *skb) +{ + return div_u64(skb->skb_mstamp_ns, NSEC_PER_USEC); +} + + +#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_SYN_ECN (TCPHDR_SYN | TCPHDR_ECE | TCPHDR_CWR) + +/* This is what the send packet queuing engine uses to pass + * TCP per-packet control information to the transmission code. + * We also store the host-order sequence numbers in here too. + * This is 44 bytes if IPV6 is enabled. + * If this grows please adjust skbuff.h:skbuff->cb[xxx] size appropriately. + */ +struct tcp_skb_cb { + __u32 seq; /* Starting sequence number */ + __u32 end_seq; /* SEQ + FIN + SYN + datalen */ + union { + /* Note : tcp_tw_isn is used in input path only + * (isn chosen by tcp_timewait_state_process()) + * + * tcp_gso_segs/size are used in write queue only, + * cf tcp_skb_pcount()/tcp_skb_mss() + */ + __u32 tcp_tw_isn; + struct { + u16 tcp_gso_segs; + u16 tcp_gso_size; + }; + }; + __u8 tcp_flags; /* TCP header flags. (tcp[13]) */ + + __u8 sacked; /* State flags for SACK. */ +#define TCPCB_SACKED_ACKED 0x01 /* SKB ACK'd by a SACK block */ +#define TCPCB_SACKED_RETRANS 0x02 /* SKB retransmitted */ +#define TCPCB_LOST 0x04 /* SKB is lost */ +#define TCPCB_TAGBITS 0x07 /* All tag bits */ +#define TCPCB_REPAIRED 0x10 /* SKB repaired (no skb_mstamp_ns) */ +#define TCPCB_EVER_RETRANS 0x80 /* Ever retransmitted frame */ +#define TCPCB_RETRANS (TCPCB_SACKED_RETRANS|TCPCB_EVER_RETRANS| \ + TCPCB_REPAIRED) + + __u8 ip_dsfield; /* IPv4 tos or IPv6 dsfield */ + __u8 txstamp_ack:1, /* Record TX timestamp for ack? */ + eor:1, /* Is skb MSG_EOR marked? */ + has_rxtstamp:1, /* SKB has a RX timestamp */ + unused:5; + __u32 ack_seq; /* Sequence number ACK'd */ + union { + struct { +#define TCPCB_DELIVERED_CE_MASK ((1U<<20) - 1) + /* There is space for up to 24 bytes */ + __u32 is_app_limited:1, /* cwnd not fully used? */ + delivered_ce:20, + unused:11; + /* pkts S/ACKed so far upon tx of skb, incl retrans: */ + __u32 delivered; + /* start of send pipeline phase */ + u64 first_tx_mstamp; + /* when we reached the "delivered" count */ + u64 delivered_mstamp; + } tx; /* only used for outgoing skbs */ + union { + struct inet_skb_parm h4; +#if IS_ENABLED(CONFIG_IPV6) + struct inet6_skb_parm h6; +#endif + } header; /* For incoming skbs */ + }; +}; + +#define TCP_SKB_CB(__skb) ((struct tcp_skb_cb *)&((__skb)->cb[0])) + +extern const struct inet_connection_sock_af_ops ipv4_specific; + +#if IS_ENABLED(CONFIG_IPV6) +/* This is the variant of inet6_iif() that must be used by TCP, + * as TCP moves IP6CB into a different location in skb->cb[] + */ +static inline int tcp_v6_iif(const struct sk_buff *skb) +{ + return TCP_SKB_CB(skb)->header.h6.iif; +} + +static inline int tcp_v6_iif_l3_slave(const struct sk_buff *skb) +{ + bool l3_slave = ipv6_l3mdev_skb(TCP_SKB_CB(skb)->header.h6.flags); + + return l3_slave ? skb->skb_iif : TCP_SKB_CB(skb)->header.h6.iif; +} + +/* TCP_SKB_CB reference means this can not be used from early demux */ +static inline int tcp_v6_sdif(const struct sk_buff *skb) +{ +#if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV) + if (skb && ipv6_l3mdev_skb(TCP_SKB_CB(skb)->header.h6.flags)) + return TCP_SKB_CB(skb)->header.h6.iif; +#endif + return 0; +} + +extern const struct inet_connection_sock_af_ops ipv6_specific; + +INDIRECT_CALLABLE_DECLARE(void tcp_v6_send_check(struct sock *sk, struct sk_buff *skb)); +INDIRECT_CALLABLE_DECLARE(int tcp_v6_rcv(struct sk_buff *skb)); +void tcp_v6_early_demux(struct sk_buff *skb); + +#endif + +/* TCP_SKB_CB reference means this can not be used from early demux */ +static inline int tcp_v4_sdif(struct sk_buff *skb) +{ +#if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV) + if (skb && ipv4_l3mdev_skb(TCP_SKB_CB(skb)->header.h4.flags)) + return TCP_SKB_CB(skb)->header.h4.iif; +#endif + return 0; +} + +/* Due to TSO, an SKB can be composed of multiple actual + * packets. To keep these tracked properly, we use this. + */ +static inline int tcp_skb_pcount(const struct sk_buff *skb) +{ + return TCP_SKB_CB(skb)->tcp_gso_segs; +} + +static inline void tcp_skb_pcount_set(struct sk_buff *skb, int segs) +{ + TCP_SKB_CB(skb)->tcp_gso_segs = segs; +} + +static inline void tcp_skb_pcount_add(struct sk_buff *skb, int segs) +{ + TCP_SKB_CB(skb)->tcp_gso_segs += segs; +} + +/* This is valid iff skb is in write queue and tcp_skb_pcount() > 1. */ +static inline int tcp_skb_mss(const struct sk_buff *skb) +{ + return TCP_SKB_CB(skb)->tcp_gso_size; +} + +static inline bool tcp_skb_can_collapse_to(const struct sk_buff *skb) +{ + return likely(!TCP_SKB_CB(skb)->eor); +} + +static inline bool tcp_skb_can_collapse(const struct sk_buff *to, + const struct sk_buff *from) +{ + return likely(tcp_skb_can_collapse_to(to) && + mptcp_skb_can_collapse(to, from) && + skb_pure_zcopy_same(to, from)); +} + +/* Events passed to congestion control interface */ +enum tcp_ca_event { + CA_EVENT_TX_START, /* first transmit when no packets in flight */ + CA_EVENT_CWND_RESTART, /* congestion window restart */ + CA_EVENT_COMPLETE_CWR, /* end of congestion recovery */ + CA_EVENT_LOSS, /* loss timeout */ + CA_EVENT_ECN_NO_CE, /* ECT set, but not CE marked */ + CA_EVENT_ECN_IS_CE, /* received CE marked IP packet */ +}; + +/* Information about inbound ACK, passed to cong_ops->in_ack_event() */ +enum tcp_ca_ack_event_flags { + CA_ACK_SLOWPATH = (1 << 0), /* In slow path processing */ + CA_ACK_WIN_UPDATE = (1 << 1), /* ACK updated window */ + CA_ACK_ECE = (1 << 2), /* ECE bit is set on ack */ +}; + +/* + * Interface for adding new TCP congestion control handlers + */ +#define TCP_CA_NAME_MAX 16 +#define TCP_CA_MAX 128 +#define TCP_CA_BUF_MAX (TCP_CA_NAME_MAX*TCP_CA_MAX) + +#define TCP_CA_UNSPEC 0 + +/* Algorithm can be set on socket without CAP_NET_ADMIN privileges */ +#define TCP_CONG_NON_RESTRICTED 0x1 +/* Requires ECN/ECT set on all packets */ +#define TCP_CONG_NEEDS_ECN 0x2 +#define TCP_CONG_MASK (TCP_CONG_NON_RESTRICTED | TCP_CONG_NEEDS_ECN) + +union tcp_cc_info; + +struct ack_sample { + u32 pkts_acked; + s32 rtt_us; + u32 in_flight; +}; + +/* A rate sample measures the number of (original/retransmitted) data + * packets delivered "delivered" over an interval of time "interval_us". + * The tcp_rate.c code fills in the rate sample, and congestion + * control modules that define a cong_control function to run at the end + * of ACK processing can optionally chose to consult this sample when + * setting cwnd and pacing rate. + * A sample is invalid if "delivered" or "interval_us" is negative. + */ +struct rate_sample { + u64 prior_mstamp; /* starting timestamp for interval */ + u32 prior_delivered; /* tp->delivered at "prior_mstamp" */ + u32 prior_delivered_ce;/* tp->delivered_ce at "prior_mstamp" */ + s32 delivered; /* number of packets delivered over interval */ + s32 delivered_ce; /* number of packets delivered w/ CE marks*/ + long interval_us; /* time for tp->delivered to incr "delivered" */ + u32 snd_interval_us; /* snd interval for delivered packets */ + u32 rcv_interval_us; /* rcv interval for delivered packets */ + long rtt_us; /* RTT of last (S)ACKed packet (or -1) */ + int losses; /* number of packets marked lost upon ACK */ + u32 acked_sacked; /* number of packets newly (S)ACKed upon ACK */ + u32 prior_in_flight; /* in flight before this ACK */ + u32 last_end_seq; /* end_seq of most recently ACKed packet */ + bool is_app_limited; /* is sample from packet with bubble in pipe? */ + bool is_retrans; /* is sample from retransmission? */ + bool is_ack_delayed; /* is this (likely) a delayed ACK? */ +}; + +struct tcp_congestion_ops { +/* fast path fields are put first to fill one cache line */ + + /* return slow start threshold (required) */ + u32 (*ssthresh)(struct sock *sk); + + /* do new cwnd calculation (required) */ + void (*cong_avoid)(struct sock *sk, u32 ack, u32 acked); + + /* call before changing ca_state (optional) */ + void (*set_state)(struct sock *sk, u8 new_state); + + /* call when cwnd event occurs (optional) */ + void (*cwnd_event)(struct sock *sk, enum tcp_ca_event ev); + + /* call when ack arrives (optional) */ + void (*in_ack_event)(struct sock *sk, u32 flags); + + /* hook for packet ack accounting (optional) */ + void (*pkts_acked)(struct sock *sk, const struct ack_sample *sample); + + /* override sysctl_tcp_min_tso_segs */ + u32 (*min_tso_segs)(struct sock *sk); + + /* call when packets are delivered to update cwnd and pacing rate, + * after all the ca_state processing. (optional) + */ + void (*cong_control)(struct sock *sk, const struct rate_sample *rs); + + + /* new value of cwnd after loss (required) */ + u32 (*undo_cwnd)(struct sock *sk); + /* returns the multiplier used in tcp_sndbuf_expand (optional) */ + u32 (*sndbuf_expand)(struct sock *sk); + +/* control/slow paths put last */ + /* get info for inet_diag (optional) */ + size_t (*get_info)(struct sock *sk, u32 ext, int *attr, + union tcp_cc_info *info); + + char name[TCP_CA_NAME_MAX]; + struct module *owner; + struct list_head list; + u32 key; + u32 flags; + + /* initialize private data (optional) */ + void (*init)(struct sock *sk); + /* cleanup private data (optional) */ + void (*release)(struct sock *sk); +} ____cacheline_aligned_in_smp; + +int tcp_register_congestion_control(struct tcp_congestion_ops *type); +void tcp_unregister_congestion_control(struct tcp_congestion_ops *type); +int tcp_update_congestion_control(struct tcp_congestion_ops *type, + struct tcp_congestion_ops *old_type); +int tcp_validate_congestion_control(struct tcp_congestion_ops *ca); + +void tcp_assign_congestion_control(struct sock *sk); +void tcp_init_congestion_control(struct sock *sk); +void tcp_cleanup_congestion_control(struct sock *sk); +int tcp_set_default_congestion_control(struct net *net, const char *name); +void tcp_get_default_congestion_control(struct net *net, char *name); +void tcp_get_available_congestion_control(char *buf, size_t len); +void tcp_get_allowed_congestion_control(char *buf, size_t len); +int tcp_set_allowed_congestion_control(char *allowed); +int tcp_set_congestion_control(struct sock *sk, const char *name, bool load, + bool cap_net_admin); +u32 tcp_slow_start(struct tcp_sock *tp, u32 acked); +void tcp_cong_avoid_ai(struct tcp_sock *tp, u32 w, u32 acked); + +u32 tcp_reno_ssthresh(struct sock *sk); +u32 tcp_reno_undo_cwnd(struct sock *sk); +void tcp_reno_cong_avoid(struct sock *sk, u32 ack, u32 acked); +extern struct tcp_congestion_ops tcp_reno; + +struct tcp_congestion_ops *tcp_ca_find(const char *name); +struct tcp_congestion_ops *tcp_ca_find_key(u32 key); +u32 tcp_ca_get_key_by_name(struct net *net, const char *name, bool *ecn_ca); +#ifdef CONFIG_INET +char *tcp_ca_get_name_by_key(u32 key, char *buffer); +#else +static inline char *tcp_ca_get_name_by_key(u32 key, char *buffer) +{ + return NULL; +} +#endif + +static inline bool tcp_ca_needs_ecn(const struct sock *sk) +{ + const struct inet_connection_sock *icsk = inet_csk(sk); + + return icsk->icsk_ca_ops->flags & TCP_CONG_NEEDS_ECN; +} + +static inline void tcp_ca_event(struct sock *sk, const enum tcp_ca_event event) +{ + const struct inet_connection_sock *icsk = inet_csk(sk); + + if (icsk->icsk_ca_ops->cwnd_event) + icsk->icsk_ca_ops->cwnd_event(sk, event); +} + +/* From tcp_cong.c */ +void tcp_set_ca_state(struct sock *sk, const u8 ca_state); + +/* From tcp_rate.c */ +void tcp_rate_skb_sent(struct sock *sk, struct sk_buff *skb); +void tcp_rate_skb_delivered(struct sock *sk, struct sk_buff *skb, + struct rate_sample *rs); +void tcp_rate_gen(struct sock *sk, u32 delivered, u32 lost, + bool is_sack_reneg, struct rate_sample *rs); +void tcp_rate_check_app_limited(struct sock *sk); + +static inline bool tcp_skb_sent_after(u64 t1, u64 t2, u32 seq1, u32 seq2) +{ + return t1 > t2 || (t1 == t2 && after(seq1, seq2)); +} + +/* These functions determine how the current flow behaves in respect of SACK + * handling. SACK is negotiated with the peer, and therefore it can vary + * between different flows. + * + * tcp_is_sack - SACK enabled + * tcp_is_reno - No SACK + */ +static inline int tcp_is_sack(const struct tcp_sock *tp) +{ + return likely(tp->rx_opt.sack_ok); +} + +static inline bool tcp_is_reno(const struct tcp_sock *tp) +{ + return !tcp_is_sack(tp); +} + +static inline unsigned int tcp_left_out(const struct tcp_sock *tp) +{ + return tp->sacked_out + tp->lost_out; +} + +/* This determines how many packets are "in the network" to the best + * of our knowledge. In many cases it is conservative, but where + * detailed information is available from the receiver (via SACK + * blocks etc.) we can make more aggressive calculations. + * + * Use this for decisions involving congestion control, use just + * tp->packets_out to determine if the send queue is empty or not. + * + * Read this equation as: + * + * "Packets sent once on transmission queue" MINUS + * "Packets left network, but not honestly ACKed yet" PLUS + * "Packets fast retransmitted" + */ +static inline unsigned int tcp_packets_in_flight(const struct tcp_sock *tp) +{ + return tp->packets_out - tcp_left_out(tp) + tp->retrans_out; +} + +#define TCP_INFINITE_SSTHRESH 0x7fffffff + +static inline u32 tcp_snd_cwnd(const struct tcp_sock *tp) +{ + return tp->snd_cwnd; +} + +static inline void tcp_snd_cwnd_set(struct tcp_sock *tp, u32 val) +{ + WARN_ON_ONCE((int)val <= 0); + tp->snd_cwnd = val; +} + +static inline bool tcp_in_slow_start(const struct tcp_sock *tp) +{ + return tcp_snd_cwnd(tp) < tp->snd_ssthresh; +} + +static inline bool tcp_in_initial_slowstart(const struct tcp_sock *tp) +{ + return tp->snd_ssthresh >= TCP_INFINITE_SSTHRESH; +} + +static inline bool tcp_in_cwnd_reduction(const struct sock *sk) +{ + return (TCPF_CA_CWR | TCPF_CA_Recovery) & + (1 << inet_csk(sk)->icsk_ca_state); +} + +/* If cwnd > ssthresh, we may raise ssthresh to be half-way to cwnd. + * The exception is cwnd reduction phase, when cwnd is decreasing towards + * ssthresh. + */ +static inline __u32 tcp_current_ssthresh(const struct sock *sk) +{ + const struct tcp_sock *tp = tcp_sk(sk); + + if (tcp_in_cwnd_reduction(sk)) + return tp->snd_ssthresh; + else + return max(tp->snd_ssthresh, + ((tcp_snd_cwnd(tp) >> 1) + + (tcp_snd_cwnd(tp) >> 2))); +} + +/* Use define here intentionally to get WARN_ON location shown at the caller */ +#define tcp_verify_left_out(tp) WARN_ON(tcp_left_out(tp) > tp->packets_out) + +void tcp_enter_cwr(struct sock *sk); +__u32 tcp_init_cwnd(const struct tcp_sock *tp, const struct dst_entry *dst); + +/* The maximum number of MSS of available cwnd for which TSO defers + * sending if not using sysctl_tcp_tso_win_divisor. + */ +static inline __u32 tcp_max_tso_deferred_mss(const struct tcp_sock *tp) +{ + return 3; +} + +/* Returns end sequence number of the receiver's advertised window */ +static inline u32 tcp_wnd_end(const struct tcp_sock *tp) +{ + return tp->snd_una + tp->snd_wnd; +} + +/* We follow the spirit of RFC2861 to validate cwnd but implement a more + * flexible approach. The RFC suggests cwnd should not be raised unless + * it was fully used previously. And that's exactly what we do in + * congestion avoidance mode. But in slow start we allow cwnd to grow + * as long as the application has used half the cwnd. + * Example : + * cwnd is 10 (IW10), but application sends 9 frames. + * We allow cwnd to reach 18 when all frames are ACKed. + * This check is safe because it's as aggressive as slow start which already + * risks 100% overshoot. The advantage is that we discourage application to + * either send more filler packets or data to artificially blow up the cwnd + * usage, and allow application-limited process to probe bw more aggressively. + */ +static inline bool tcp_is_cwnd_limited(const struct sock *sk) +{ + const struct tcp_sock *tp = tcp_sk(sk); + + if (tp->is_cwnd_limited) + return true; + + /* If in slow start, ensure cwnd grows to twice what was ACKed. */ + if (tcp_in_slow_start(tp)) + return tcp_snd_cwnd(tp) < 2 * tp->max_packets_out; + + return false; +} + +/* BBR congestion control needs pacing. + * Same remark for SO_MAX_PACING_RATE. + * sch_fq packet scheduler is efficiently handling pacing, + * but is not always installed/used. + * Return true if TCP stack should pace packets itself. + */ +static inline bool tcp_needs_internal_pacing(const struct sock *sk) +{ + return smp_load_acquire(&sk->sk_pacing_status) == SK_PACING_NEEDED; +} + +/* Estimates in how many jiffies next packet for this flow can be sent. + * Scheduling a retransmit timer too early would be silly. + */ +static inline unsigned long tcp_pacing_delay(const struct sock *sk) +{ + s64 delay = tcp_sk(sk)->tcp_wstamp_ns - tcp_sk(sk)->tcp_clock_cache; + + return delay > 0 ? nsecs_to_jiffies(delay) : 0; +} + +static inline void tcp_reset_xmit_timer(struct sock *sk, + const int what, + unsigned long when, + const unsigned long max_when) +{ + inet_csk_reset_xmit_timer(sk, what, when + tcp_pacing_delay(sk), + max_when); +} + +/* Something is really bad, we could not queue an additional packet, + * because qdisc is full or receiver sent a 0 window, or we are paced. + * We do not want to add fuel to the fire, or abort too early, + * so make sure the timer we arm now is at least 200ms in the future, + * regardless of current icsk_rto value (as it could be ~2ms) + */ +static inline unsigned long tcp_probe0_base(const struct sock *sk) +{ + return max_t(unsigned long, inet_csk(sk)->icsk_rto, TCP_RTO_MIN); +} + +/* Variant of inet_csk_rto_backoff() used for zero window probes */ +static inline unsigned long tcp_probe0_when(const struct sock *sk, + unsigned long max_when) +{ + u8 backoff = min_t(u8, ilog2(TCP_RTO_MAX / TCP_RTO_MIN) + 1, + inet_csk(sk)->icsk_backoff); + u64 when = (u64)tcp_probe0_base(sk) << backoff; + + return (unsigned long)min_t(u64, when, max_when); +} + +static inline void tcp_check_probe_timer(struct sock *sk) +{ + if (!tcp_sk(sk)->packets_out && !inet_csk(sk)->icsk_pending) + tcp_reset_xmit_timer(sk, ICSK_TIME_PROBE0, + tcp_probe0_base(sk), TCP_RTO_MAX); +} + +static inline void tcp_init_wl(struct tcp_sock *tp, u32 seq) +{ + tp->snd_wl1 = seq; +} + +static inline void tcp_update_wl(struct tcp_sock *tp, u32 seq) +{ + tp->snd_wl1 = seq; +} + +/* + * Calculate(/check) TCP checksum + */ +static inline __sum16 tcp_v4_check(int len, __be32 saddr, + __be32 daddr, __wsum base) +{ + return csum_tcpudp_magic(saddr, daddr, len, IPPROTO_TCP, base); +} + +static inline bool tcp_checksum_complete(struct sk_buff *skb) +{ + return !skb_csum_unnecessary(skb) && + __skb_checksum_complete(skb); +} + +bool tcp_add_backlog(struct sock *sk, struct sk_buff *skb, + enum skb_drop_reason *reason); + + +int tcp_filter(struct sock *sk, struct sk_buff *skb); +void tcp_set_state(struct sock *sk, int state); +void tcp_done(struct sock *sk); +int tcp_abort(struct sock *sk, int err); + +static inline void tcp_sack_reset(struct tcp_options_received *rx_opt) +{ + rx_opt->dsack = 0; + rx_opt->num_sacks = 0; +} + +void tcp_cwnd_restart(struct sock *sk, s32 delta); + +static inline void tcp_slow_start_after_idle_check(struct sock *sk) +{ + const struct tcp_congestion_ops *ca_ops = inet_csk(sk)->icsk_ca_ops; + struct tcp_sock *tp = tcp_sk(sk); + s32 delta; + + if (!READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_slow_start_after_idle) || + tp->packets_out || ca_ops->cong_control) + return; + delta = tcp_jiffies32 - tp->lsndtime; + if (delta > inet_csk(sk)->icsk_rto) + tcp_cwnd_restart(sk, delta); +} + +/* Determine a window scaling and initial window to offer. */ +void tcp_select_initial_window(const struct sock *sk, int __space, + __u32 mss, __u32 *rcv_wnd, + __u32 *window_clamp, int wscale_ok, + __u8 *rcv_wscale, __u32 init_rcv_wnd); + +static inline int __tcp_win_from_space(u8 scaling_ratio, int space) +{ + s64 scaled_space = (s64)space * scaling_ratio; + + return scaled_space >> TCP_RMEM_TO_WIN_SCALE; +} + +static inline int tcp_win_from_space(const struct sock *sk, int space) +{ + return __tcp_win_from_space(tcp_sk(sk)->scaling_ratio, space); +} + +/* inverse of __tcp_win_from_space() */ +static inline int __tcp_space_from_win(u8 scaling_ratio, int win) +{ + u64 val = (u64)win << TCP_RMEM_TO_WIN_SCALE; + + do_div(val, scaling_ratio); + return val; +} + +static inline int tcp_space_from_win(const struct sock *sk, int win) +{ + return __tcp_space_from_win(tcp_sk(sk)->scaling_ratio, win); +} + +static inline void tcp_scaling_ratio_init(struct sock *sk) +{ + /* Assume a conservative default of 1200 bytes of payload per 4K page. + * This may be adjusted later in tcp_measure_rcv_mss(). + */ + tcp_sk(sk)->scaling_ratio = (1200 << TCP_RMEM_TO_WIN_SCALE) / + SKB_TRUESIZE(4096); +} + +/* Note: caller must be prepared to deal with negative returns */ +static inline int tcp_space(const struct sock *sk) +{ + return tcp_win_from_space(sk, READ_ONCE(sk->sk_rcvbuf) - + READ_ONCE(sk->sk_backlog.len) - + atomic_read(&sk->sk_rmem_alloc)); +} + +static inline int tcp_full_space(const struct sock *sk) +{ + return tcp_win_from_space(sk, READ_ONCE(sk->sk_rcvbuf)); +} + +static inline void __tcp_adjust_rcv_ssthresh(struct sock *sk, u32 new_ssthresh) +{ + int unused_mem = sk_unused_reserved_mem(sk); + struct tcp_sock *tp = tcp_sk(sk); + + tp->rcv_ssthresh = min(tp->rcv_ssthresh, new_ssthresh); + if (unused_mem) + tp->rcv_ssthresh = max_t(u32, tp->rcv_ssthresh, + tcp_win_from_space(sk, unused_mem)); +} + +static inline void tcp_adjust_rcv_ssthresh(struct sock *sk) +{ + __tcp_adjust_rcv_ssthresh(sk, 4U * tcp_sk(sk)->advmss); +} + +void tcp_cleanup_rbuf(struct sock *sk, int copied); +void __tcp_cleanup_rbuf(struct sock *sk, int copied); + + +/* We provision sk_rcvbuf around 200% of sk_rcvlowat. + * If 87.5 % (7/8) of the space has been consumed, we want to override + * SO_RCVLOWAT constraint, since we are receiving skbs with too small + * len/truesize ratio. + */ +static inline bool tcp_rmem_pressure(const struct sock *sk) +{ + int rcvbuf, threshold; + + if (tcp_under_memory_pressure(sk)) + return true; + + rcvbuf = READ_ONCE(sk->sk_rcvbuf); + threshold = rcvbuf - (rcvbuf >> 3); + + return atomic_read(&sk->sk_rmem_alloc) > threshold; +} + +static inline bool tcp_epollin_ready(const struct sock *sk, int target) +{ + const struct tcp_sock *tp = tcp_sk(sk); + int avail = READ_ONCE(tp->rcv_nxt) - READ_ONCE(tp->copied_seq); + + if (avail <= 0) + return false; + + return (avail >= target) || tcp_rmem_pressure(sk) || + (tcp_receive_window(tp) <= inet_csk(sk)->icsk_ack.rcv_mss); +} + +extern void tcp_openreq_init_rwin(struct request_sock *req, + const struct sock *sk_listener, + const struct dst_entry *dst); + +void tcp_enter_memory_pressure(struct sock *sk); +void tcp_leave_memory_pressure(struct sock *sk); + +static inline int keepalive_intvl_when(const struct tcp_sock *tp) +{ + struct net *net = sock_net((struct sock *)tp); + int val; + + /* Paired with WRITE_ONCE() in tcp_sock_set_keepintvl() + * and do_tcp_setsockopt(). + */ + val = READ_ONCE(tp->keepalive_intvl); + + return val ? : READ_ONCE(net->ipv4.sysctl_tcp_keepalive_intvl); +} + +static inline int keepalive_time_when(const struct tcp_sock *tp) +{ + struct net *net = sock_net((struct sock *)tp); + int val; + + /* Paired with WRITE_ONCE() in tcp_sock_set_keepidle_locked() */ + val = READ_ONCE(tp->keepalive_time); + + return val ? : READ_ONCE(net->ipv4.sysctl_tcp_keepalive_time); +} + +static inline int keepalive_probes(const struct tcp_sock *tp) +{ + struct net *net = sock_net((struct sock *)tp); + int val; + + /* Paired with WRITE_ONCE() in tcp_sock_set_keepcnt() + * and do_tcp_setsockopt(). + */ + val = READ_ONCE(tp->keepalive_probes); + + return val ? : READ_ONCE(net->ipv4.sysctl_tcp_keepalive_probes); +} + +static inline u32 keepalive_time_elapsed(const struct tcp_sock *tp) +{ + const struct inet_connection_sock *icsk = &tp->inet_conn; + + return min_t(u32, tcp_jiffies32 - icsk->icsk_ack.lrcvtime, + tcp_jiffies32 - tp->rcv_tstamp); +} + +static inline int tcp_fin_time(const struct sock *sk) +{ + int fin_timeout = tcp_sk(sk)->linger2 ? : + READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_fin_timeout); + const int rto = inet_csk(sk)->icsk_rto; + + if (fin_timeout < (rto << 2) - (rto >> 1)) + fin_timeout = (rto << 2) - (rto >> 1); + + return fin_timeout; +} + +static inline bool tcp_paws_check(const struct tcp_options_received *rx_opt, + int paws_win) +{ + if ((s32)(rx_opt->ts_recent - rx_opt->rcv_tsval) <= paws_win) + return true; + if (unlikely(!time_before32(ktime_get_seconds(), + rx_opt->ts_recent_stamp + TCP_PAWS_24DAYS))) + return true; + /* + * Some OSes send SYN and SYNACK messages with tsval=0 tsecr=0, + * then following tcp messages have valid values. Ignore 0 value, + * or else 'negative' tsval might forbid us to accept their packets. + */ + if (!rx_opt->ts_recent) + return true; + return false; +} + +static inline bool tcp_paws_reject(const struct tcp_options_received *rx_opt, + int rst) +{ + if (tcp_paws_check(rx_opt, 0)) + return false; + + /* RST segments are not recommended to carry timestamp, + and, if they do, it is recommended to ignore PAWS because + "their cleanup function should take precedence over timestamps." + Certainly, it is mistake. It is necessary to understand the reasons + of this constraint to relax it: if peer reboots, clock may go + out-of-sync and half-open connections will not be reset. + Actually, the problem would be not existing if all + the implementations followed draft about maintaining clock + via reboots. Linux-2.2 DOES NOT! + + However, we can relax time bounds for RST segments to MSL. + */ + if (rst && !time_before32(ktime_get_seconds(), + rx_opt->ts_recent_stamp + TCP_PAWS_MSL)) + return false; + return true; +} + +bool tcp_oow_rate_limited(struct net *net, const struct sk_buff *skb, + int mib_idx, u32 *last_oow_ack_time); + +static inline void tcp_mib_init(struct net *net) +{ + /* See RFC 2012 */ + TCP_ADD_STATS(net, TCP_MIB_RTOALGORITHM, 1); + TCP_ADD_STATS(net, TCP_MIB_RTOMIN, TCP_RTO_MIN*1000/HZ); + TCP_ADD_STATS(net, TCP_MIB_RTOMAX, TCP_RTO_MAX*1000/HZ); + TCP_ADD_STATS(net, TCP_MIB_MAXCONN, -1); +} + +/* from STCP */ +static inline void tcp_clear_retrans_hints_partial(struct tcp_sock *tp) +{ + tp->lost_skb_hint = NULL; +} + +static inline void tcp_clear_all_retrans_hints(struct tcp_sock *tp) +{ + tcp_clear_retrans_hints_partial(tp); + tp->retransmit_skb_hint = NULL; +} + +union tcp_md5_addr { + struct in_addr a4; +#if IS_ENABLED(CONFIG_IPV6) + struct in6_addr a6; +#endif +}; + +/* - key database */ +struct tcp_md5sig_key { + struct hlist_node node; + u8 keylen; + u8 family; /* AF_INET or AF_INET6 */ + u8 prefixlen; + u8 flags; + union tcp_md5_addr addr; + int l3index; /* set if key added with L3 scope */ + u8 key[TCP_MD5SIG_MAXKEYLEN]; + struct rcu_head rcu; +}; + +/* - sock block */ +struct tcp_md5sig_info { + struct hlist_head head; + struct rcu_head rcu; +}; + +/* - pseudo header */ +struct tcp4_pseudohdr { + __be32 saddr; + __be32 daddr; + __u8 pad; + __u8 protocol; + __be16 len; +}; + +struct tcp6_pseudohdr { + struct in6_addr saddr; + struct in6_addr daddr; + __be32 len; + __be32 protocol; /* including padding */ +}; + +union tcp_md5sum_block { + struct tcp4_pseudohdr ip4; +#if IS_ENABLED(CONFIG_IPV6) + struct tcp6_pseudohdr ip6; +#endif +}; + +/* - pool: digest algorithm, hash description and scratch buffer */ +struct tcp_md5sig_pool { + struct ahash_request *md5_req; + void *scratch; +}; + +/* - functions */ +int tcp_v4_md5_hash_skb(char *md5_hash, const struct tcp_md5sig_key *key, + const struct sock *sk, const struct sk_buff *skb); +int tcp_md5_do_add(struct sock *sk, const union tcp_md5_addr *addr, + int family, u8 prefixlen, int l3index, u8 flags, + const u8 *newkey, u8 newkeylen); +int tcp_md5_key_copy(struct sock *sk, const union tcp_md5_addr *addr, + int family, u8 prefixlen, int l3index, + struct tcp_md5sig_key *key); + +int tcp_md5_do_del(struct sock *sk, const union tcp_md5_addr *addr, + int family, u8 prefixlen, int l3index, u8 flags); +struct tcp_md5sig_key *tcp_v4_md5_lookup(const struct sock *sk, + const struct sock *addr_sk); + +#ifdef CONFIG_TCP_MD5SIG +#include <linux/jump_label.h> +extern struct static_key_false_deferred tcp_md5_needed; +struct tcp_md5sig_key *__tcp_md5_do_lookup(const struct sock *sk, int l3index, + const union tcp_md5_addr *addr, + int family); +static inline struct tcp_md5sig_key * +tcp_md5_do_lookup(const struct sock *sk, int l3index, + const union tcp_md5_addr *addr, int family) +{ + if (!static_branch_unlikely(&tcp_md5_needed.key)) + return NULL; + return __tcp_md5_do_lookup(sk, l3index, addr, family); +} + +enum skb_drop_reason +tcp_inbound_md5_hash(const struct sock *sk, const struct sk_buff *skb, + const void *saddr, const void *daddr, + int family, int dif, int sdif); + + +#define tcp_twsk_md5_key(twsk) ((twsk)->tw_md5_key) +#else +static inline struct tcp_md5sig_key * +tcp_md5_do_lookup(const struct sock *sk, int l3index, + const union tcp_md5_addr *addr, int family) +{ + return NULL; +} + +static inline enum skb_drop_reason +tcp_inbound_md5_hash(const struct sock *sk, const struct sk_buff *skb, + const void *saddr, const void *daddr, + int family, int dif, int sdif) +{ + return SKB_NOT_DROPPED_YET; +} +#define tcp_twsk_md5_key(twsk) NULL +#endif + +bool tcp_alloc_md5sig_pool(void); + +struct tcp_md5sig_pool *tcp_get_md5sig_pool(void); +static inline void tcp_put_md5sig_pool(void) +{ + local_bh_enable(); +} + +int tcp_md5_hash_skb_data(struct tcp_md5sig_pool *, const struct sk_buff *, + unsigned int header_len); +int tcp_md5_hash_key(struct tcp_md5sig_pool *hp, + const struct tcp_md5sig_key *key); + +/* From tcp_fastopen.c */ +void tcp_fastopen_cache_get(struct sock *sk, u16 *mss, + struct tcp_fastopen_cookie *cookie); +void tcp_fastopen_cache_set(struct sock *sk, u16 mss, + struct tcp_fastopen_cookie *cookie, bool syn_lost, + u16 try_exp); +struct tcp_fastopen_request { + /* Fast Open cookie. Size 0 means a cookie request */ + struct tcp_fastopen_cookie cookie; + struct msghdr *data; /* data in MSG_FASTOPEN */ + size_t size; + int copied; /* queued in tcp_connect() */ + struct ubuf_info *uarg; +}; +void tcp_free_fastopen_req(struct tcp_sock *tp); +void tcp_fastopen_destroy_cipher(struct sock *sk); +void tcp_fastopen_ctx_destroy(struct net *net); +int tcp_fastopen_reset_cipher(struct net *net, struct sock *sk, + void *primary_key, void *backup_key); +int tcp_fastopen_get_cipher(struct net *net, struct inet_connection_sock *icsk, + u64 *key); +void tcp_fastopen_add_skb(struct sock *sk, struct sk_buff *skb); +struct sock *tcp_try_fastopen(struct sock *sk, struct sk_buff *skb, + struct request_sock *req, + struct tcp_fastopen_cookie *foc, + const struct dst_entry *dst); +void tcp_fastopen_init_key_once(struct net *net); +bool tcp_fastopen_cookie_check(struct sock *sk, u16 *mss, + struct tcp_fastopen_cookie *cookie); +bool tcp_fastopen_defer_connect(struct sock *sk, int *err); +#define TCP_FASTOPEN_KEY_LENGTH sizeof(siphash_key_t) +#define TCP_FASTOPEN_KEY_MAX 2 +#define TCP_FASTOPEN_KEY_BUF_LENGTH \ + (TCP_FASTOPEN_KEY_LENGTH * TCP_FASTOPEN_KEY_MAX) + +/* Fastopen key context */ +struct tcp_fastopen_context { + siphash_key_t key[TCP_FASTOPEN_KEY_MAX]; + int num; + struct rcu_head rcu; +}; + +void tcp_fastopen_active_disable(struct sock *sk); +bool tcp_fastopen_active_should_disable(struct sock *sk); +void tcp_fastopen_active_disable_ofo_check(struct sock *sk); +void tcp_fastopen_active_detect_blackhole(struct sock *sk, bool expired); + +/* Caller needs to wrap with rcu_read_(un)lock() */ +static inline +struct tcp_fastopen_context *tcp_fastopen_get_ctx(const struct sock *sk) +{ + struct tcp_fastopen_context *ctx; + + ctx = rcu_dereference(inet_csk(sk)->icsk_accept_queue.fastopenq.ctx); + if (!ctx) + ctx = rcu_dereference(sock_net(sk)->ipv4.tcp_fastopen_ctx); + return ctx; +} + +static inline +bool tcp_fastopen_cookie_match(const struct tcp_fastopen_cookie *foc, + const struct tcp_fastopen_cookie *orig) +{ + if (orig->len == TCP_FASTOPEN_COOKIE_SIZE && + orig->len == foc->len && + !memcmp(orig->val, foc->val, foc->len)) + return true; + return false; +} + +static inline +int tcp_fastopen_context_len(const struct tcp_fastopen_context *ctx) +{ + return ctx->num; +} + +/* Latencies incurred by various limits for a sender. They are + * chronograph-like stats that are mutually exclusive. + */ +enum tcp_chrono { + TCP_CHRONO_UNSPEC, + TCP_CHRONO_BUSY, /* Actively sending data (non-empty write queue) */ + TCP_CHRONO_RWND_LIMITED, /* Stalled by insufficient receive window */ + TCP_CHRONO_SNDBUF_LIMITED, /* Stalled by insufficient send buffer */ + __TCP_CHRONO_MAX, +}; + +void tcp_chrono_start(struct sock *sk, const enum tcp_chrono type); +void tcp_chrono_stop(struct sock *sk, const enum tcp_chrono type); + +/* This helper is needed, because skb->tcp_tsorted_anchor uses + * the same memory storage than skb->destructor/_skb_refdst + */ +static inline void tcp_skb_tsorted_anchor_cleanup(struct sk_buff *skb) +{ + skb->destructor = NULL; + skb->_skb_refdst = 0UL; +} + +#define tcp_skb_tsorted_save(skb) { \ + unsigned long _save = skb->_skb_refdst; \ + skb->_skb_refdst = 0UL; + +#define tcp_skb_tsorted_restore(skb) \ + skb->_skb_refdst = _save; \ +} + +void tcp_write_queue_purge(struct sock *sk); + +static inline struct sk_buff *tcp_rtx_queue_head(const struct sock *sk) +{ + return skb_rb_first(&sk->tcp_rtx_queue); +} + +static inline struct sk_buff *tcp_rtx_queue_tail(const struct sock *sk) +{ + return skb_rb_last(&sk->tcp_rtx_queue); +} + +static inline struct sk_buff *tcp_write_queue_tail(const struct sock *sk) +{ + return skb_peek_tail(&sk->sk_write_queue); +} + +#define tcp_for_write_queue_from_safe(skb, tmp, sk) \ + skb_queue_walk_from_safe(&(sk)->sk_write_queue, skb, tmp) + +static inline struct sk_buff *tcp_send_head(const struct sock *sk) +{ + return skb_peek(&sk->sk_write_queue); +} + +static inline bool tcp_skb_is_last(const struct sock *sk, + const struct sk_buff *skb) +{ + return skb_queue_is_last(&sk->sk_write_queue, skb); +} + +/** + * tcp_write_queue_empty - test if any payload (or FIN) is available in write queue + * @sk: socket + * + * Since the write queue can have a temporary empty skb in it, + * we must not use "return skb_queue_empty(&sk->sk_write_queue)" + */ +static inline bool tcp_write_queue_empty(const struct sock *sk) +{ + const struct tcp_sock *tp = tcp_sk(sk); + + return tp->write_seq == tp->snd_nxt; +} + +static inline bool tcp_rtx_queue_empty(const struct sock *sk) +{ + return RB_EMPTY_ROOT(&sk->tcp_rtx_queue); +} + +static inline bool tcp_rtx_and_write_queues_empty(const struct sock *sk) +{ + return tcp_rtx_queue_empty(sk) && tcp_write_queue_empty(sk); +} + +static inline void tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb) +{ + __skb_queue_tail(&sk->sk_write_queue, skb); + + /* Queue it, remembering where we must start sending. */ + if (sk->sk_write_queue.next == skb) + tcp_chrono_start(sk, TCP_CHRONO_BUSY); +} + +/* Insert new before skb on the write queue of sk. */ +static inline void tcp_insert_write_queue_before(struct sk_buff *new, + struct sk_buff *skb, + struct sock *sk) +{ + __skb_queue_before(&sk->sk_write_queue, skb, new); +} + +static inline void tcp_unlink_write_queue(struct sk_buff *skb, struct sock *sk) +{ + tcp_skb_tsorted_anchor_cleanup(skb); + __skb_unlink(skb, &sk->sk_write_queue); +} + +void tcp_rbtree_insert(struct rb_root *root, struct sk_buff *skb); + +static inline void tcp_rtx_queue_unlink(struct sk_buff *skb, struct sock *sk) +{ + tcp_skb_tsorted_anchor_cleanup(skb); + rb_erase(&skb->rbnode, &sk->tcp_rtx_queue); +} + +static inline void tcp_rtx_queue_unlink_and_free(struct sk_buff *skb, struct sock *sk) +{ + list_del(&skb->tcp_tsorted_anchor); + tcp_rtx_queue_unlink(skb, sk); + tcp_wmem_free_skb(sk, skb); +} + +static inline void tcp_push_pending_frames(struct sock *sk) +{ + if (tcp_send_head(sk)) { + struct tcp_sock *tp = tcp_sk(sk); + + __tcp_push_pending_frames(sk, tcp_current_mss(sk), tp->nonagle); + } +} + +/* Start sequence of the skb just after the highest skb with SACKed + * bit, valid only if sacked_out > 0 or when the caller has ensured + * validity by itself. + */ +static inline u32 tcp_highest_sack_seq(struct tcp_sock *tp) +{ + if (!tp->sacked_out) + return tp->snd_una; + + if (tp->highest_sack == NULL) + return tp->snd_nxt; + + return TCP_SKB_CB(tp->highest_sack)->seq; +} + +static inline void tcp_advance_highest_sack(struct sock *sk, struct sk_buff *skb) +{ + tcp_sk(sk)->highest_sack = skb_rb_next(skb); +} + +static inline struct sk_buff *tcp_highest_sack(struct sock *sk) +{ + return tcp_sk(sk)->highest_sack; +} + +static inline void tcp_highest_sack_reset(struct sock *sk) +{ + tcp_sk(sk)->highest_sack = tcp_rtx_queue_head(sk); +} + +/* Called when old skb is about to be deleted and replaced by new skb */ +static inline void tcp_highest_sack_replace(struct sock *sk, + struct sk_buff *old, + struct sk_buff *new) +{ + if (old == tcp_highest_sack(sk)) + tcp_sk(sk)->highest_sack = new; +} + +/* This helper checks if socket has IP_TRANSPARENT set */ +static inline bool inet_sk_transparent(const struct sock *sk) +{ + switch (sk->sk_state) { + case TCP_TIME_WAIT: + return inet_twsk(sk)->tw_transparent; + case TCP_NEW_SYN_RECV: + return inet_rsk(inet_reqsk(sk))->no_srccheck; + } + return inet_test_bit(TRANSPARENT, sk); +} + +/* Determines whether this is a thin stream (which may suffer from + * increased latency). Used to trigger latency-reducing mechanisms. + */ +static inline bool tcp_stream_is_thin(struct tcp_sock *tp) +{ + return tp->packets_out < 4 && !tcp_in_initial_slowstart(tp); +} + +/* /proc */ +enum tcp_seq_states { + TCP_SEQ_STATE_LISTENING, + TCP_SEQ_STATE_ESTABLISHED, +}; + +void *tcp_seq_start(struct seq_file *seq, loff_t *pos); +void *tcp_seq_next(struct seq_file *seq, void *v, loff_t *pos); +void tcp_seq_stop(struct seq_file *seq, void *v); + +struct tcp_seq_afinfo { + sa_family_t family; +}; + +struct tcp_iter_state { + struct seq_net_private p; + enum tcp_seq_states state; + struct sock *syn_wait_sk; + int bucket, offset, sbucket, num; + loff_t last_pos; +}; + +extern struct request_sock_ops tcp_request_sock_ops; +extern struct request_sock_ops tcp6_request_sock_ops; + +void tcp_v4_destroy_sock(struct sock *sk); + +struct sk_buff *tcp_gso_segment(struct sk_buff *skb, + netdev_features_t features); +struct sk_buff *tcp_gro_receive(struct list_head *head, struct sk_buff *skb); +INDIRECT_CALLABLE_DECLARE(int tcp4_gro_complete(struct sk_buff *skb, int thoff)); +INDIRECT_CALLABLE_DECLARE(struct sk_buff *tcp4_gro_receive(struct list_head *head, struct sk_buff *skb)); +INDIRECT_CALLABLE_DECLARE(int tcp6_gro_complete(struct sk_buff *skb, int thoff)); +INDIRECT_CALLABLE_DECLARE(struct sk_buff *tcp6_gro_receive(struct list_head *head, struct sk_buff *skb)); +void tcp_gro_complete(struct sk_buff *skb); + +void __tcp_v4_send_check(struct sk_buff *skb, __be32 saddr, __be32 daddr); + +static inline u32 tcp_notsent_lowat(const struct tcp_sock *tp) +{ + struct net *net = sock_net((struct sock *)tp); + u32 val; + + val = READ_ONCE(tp->notsent_lowat); + + return val ?: READ_ONCE(net->ipv4.sysctl_tcp_notsent_lowat); +} + +bool tcp_stream_memory_free(const struct sock *sk, int wake); + +#ifdef CONFIG_PROC_FS +int tcp4_proc_init(void); +void tcp4_proc_exit(void); +#endif + +int tcp_rtx_synack(const struct sock *sk, struct request_sock *req); +int tcp_conn_request(struct request_sock_ops *rsk_ops, + const struct tcp_request_sock_ops *af_ops, + struct sock *sk, struct sk_buff *skb); + +/* TCP af-specific functions */ +struct tcp_sock_af_ops { +#ifdef CONFIG_TCP_MD5SIG + struct tcp_md5sig_key *(*md5_lookup) (const struct sock *sk, + const struct sock *addr_sk); + int (*calc_md5_hash)(char *location, + const struct tcp_md5sig_key *md5, + const struct sock *sk, + const struct sk_buff *skb); + int (*md5_parse)(struct sock *sk, + int optname, + sockptr_t optval, + int optlen); +#endif +}; + +struct tcp_request_sock_ops { + u16 mss_clamp; +#ifdef CONFIG_TCP_MD5SIG + struct tcp_md5sig_key *(*req_md5_lookup)(const struct sock *sk, + const struct sock *addr_sk); + int (*calc_md5_hash) (char *location, + const struct tcp_md5sig_key *md5, + const struct sock *sk, + const struct sk_buff *skb); +#endif +#ifdef CONFIG_SYN_COOKIES + __u32 (*cookie_init_seq)(const struct sk_buff *skb, + __u16 *mss); +#endif + struct dst_entry *(*route_req)(const struct sock *sk, + struct sk_buff *skb, + struct flowi *fl, + struct request_sock *req); + u32 (*init_seq)(const struct sk_buff *skb); + u32 (*init_ts_off)(const struct net *net, const struct sk_buff *skb); + int (*send_synack)(const struct sock *sk, struct dst_entry *dst, + struct flowi *fl, struct request_sock *req, + struct tcp_fastopen_cookie *foc, + enum tcp_synack_type synack_type, + struct sk_buff *syn_skb); +}; + +extern const struct tcp_request_sock_ops tcp_request_sock_ipv4_ops; +#if IS_ENABLED(CONFIG_IPV6) +extern const struct tcp_request_sock_ops tcp_request_sock_ipv6_ops; +#endif + +#ifdef CONFIG_SYN_COOKIES +static inline __u32 cookie_init_sequence(const struct tcp_request_sock_ops *ops, + const struct sock *sk, struct sk_buff *skb, + __u16 *mss) +{ + tcp_synq_overflow(sk); + __NET_INC_STATS(sock_net(sk), LINUX_MIB_SYNCOOKIESSENT); + return ops->cookie_init_seq(skb, mss); +} +#else +static inline __u32 cookie_init_sequence(const struct tcp_request_sock_ops *ops, + const struct sock *sk, struct sk_buff *skb, + __u16 *mss) +{ + return 0; +} +#endif + +int tcpv4_offload_init(void); + +void tcp_v4_init(void); +void tcp_init(void); + +/* tcp_recovery.c */ +void tcp_mark_skb_lost(struct sock *sk, struct sk_buff *skb); +void tcp_newreno_mark_lost(struct sock *sk, bool snd_una_advanced); +extern s32 tcp_rack_skb_timeout(struct tcp_sock *tp, struct sk_buff *skb, + u32 reo_wnd); +extern bool tcp_rack_mark_lost(struct sock *sk); +extern void tcp_rack_advance(struct tcp_sock *tp, u8 sacked, u32 end_seq, + u64 xmit_time); +extern void tcp_rack_reo_timeout(struct sock *sk); +extern void tcp_rack_update_reo_wnd(struct sock *sk, struct rate_sample *rs); + +/* tcp_plb.c */ + +/* + * Scaling factor for fractions in PLB. For example, tcp_plb_update_state + * expects cong_ratio which represents fraction of traffic that experienced + * congestion over a single RTT. In order to avoid floating point operations, + * this fraction should be mapped to (1 << TCP_PLB_SCALE) and passed in. + */ +#define TCP_PLB_SCALE 8 + +/* State for PLB (Protective Load Balancing) for a single TCP connection. */ +struct tcp_plb_state { + u8 consec_cong_rounds:5, /* consecutive congested rounds */ + unused:3; + u32 pause_until; /* jiffies32 when PLB can resume rerouting */ +}; + +static inline void tcp_plb_init(const struct sock *sk, + struct tcp_plb_state *plb) +{ + plb->consec_cong_rounds = 0; + plb->pause_until = 0; +} +void tcp_plb_update_state(const struct sock *sk, struct tcp_plb_state *plb, + const int cong_ratio); +void tcp_plb_check_rehash(struct sock *sk, struct tcp_plb_state *plb); +void tcp_plb_update_state_upon_rto(struct sock *sk, struct tcp_plb_state *plb); + +/* At how many usecs into the future should the RTO fire? */ +static inline s64 tcp_rto_delta_us(const struct sock *sk) +{ + const struct sk_buff *skb = tcp_rtx_queue_head(sk); + u32 rto = inet_csk(sk)->icsk_rto; + u64 rto_time_stamp_us = tcp_skb_timestamp_us(skb) + jiffies_to_usecs(rto); + + return rto_time_stamp_us - tcp_sk(sk)->tcp_mstamp; +} + +/* + * Save and compile IPv4 options, return a pointer to it + */ +static inline struct ip_options_rcu *tcp_v4_save_options(struct net *net, + struct sk_buff *skb) +{ + const struct ip_options *opt = &TCP_SKB_CB(skb)->header.h4.opt; + struct ip_options_rcu *dopt = NULL; + + if (opt->optlen) { + int opt_size = sizeof(*dopt) + opt->optlen; + + dopt = kmalloc(opt_size, GFP_ATOMIC); + if (dopt && __ip_options_echo(net, &dopt->opt, skb, opt)) { + kfree(dopt); + dopt = NULL; + } + } + return dopt; +} + +/* locally generated TCP pure ACKs have skb->truesize == 2 + * (check tcp_send_ack() in net/ipv4/tcp_output.c ) + * This is much faster than dissecting the packet to find out. + * (Think of GRE encapsulations, IPv4, IPv6, ...) + */ +static inline bool skb_is_tcp_pure_ack(const struct sk_buff *skb) +{ + return skb->truesize == 2; +} + +static inline void skb_set_tcp_pure_ack(struct sk_buff *skb) +{ + skb->truesize = 2; +} + +static inline int tcp_inq(struct sock *sk) +{ + struct tcp_sock *tp = tcp_sk(sk); + int answ; + + if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV)) { + answ = 0; + } else if (sock_flag(sk, SOCK_URGINLINE) || + !tp->urg_data || + before(tp->urg_seq, tp->copied_seq) || + !before(tp->urg_seq, tp->rcv_nxt)) { + + answ = tp->rcv_nxt - tp->copied_seq; + + /* Subtract 1, if FIN was received */ + if (answ && sock_flag(sk, SOCK_DONE)) + answ--; + } else { + answ = tp->urg_seq - tp->copied_seq; + } + + return answ; +} + +int tcp_peek_len(struct socket *sock); + +static inline void tcp_segs_in(struct tcp_sock *tp, const struct sk_buff *skb) +{ + u16 segs_in; + + segs_in = max_t(u16, 1, skb_shinfo(skb)->gso_segs); + + /* We update these fields while other threads might + * read them from tcp_get_info() + */ + WRITE_ONCE(tp->segs_in, tp->segs_in + segs_in); + if (skb->len > tcp_hdrlen(skb)) + WRITE_ONCE(tp->data_segs_in, tp->data_segs_in + segs_in); +} + +/* + * TCP listen path runs lockless. + * We forced "struct sock" to be const qualified to make sure + * we don't modify one of its field by mistake. + * Here, we increment sk_drops which is an atomic_t, so we can safely + * make sock writable again. + */ +static inline void tcp_listendrop(const struct sock *sk) +{ + atomic_inc(&((struct sock *)sk)->sk_drops); + __NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENDROPS); +} + +enum hrtimer_restart tcp_pace_kick(struct hrtimer *timer); + +/* + * Interface for adding Upper Level Protocols over TCP + */ + +#define TCP_ULP_NAME_MAX 16 +#define TCP_ULP_MAX 128 +#define TCP_ULP_BUF_MAX (TCP_ULP_NAME_MAX*TCP_ULP_MAX) + +struct tcp_ulp_ops { + struct list_head list; + + /* initialize ulp */ + int (*init)(struct sock *sk); + /* update ulp */ + void (*update)(struct sock *sk, struct proto *p, + void (*write_space)(struct sock *sk)); + /* cleanup ulp */ + void (*release)(struct sock *sk); + /* diagnostic */ + int (*get_info)(const struct sock *sk, struct sk_buff *skb); + size_t (*get_info_size)(const struct sock *sk); + /* clone ulp */ + void (*clone)(const struct request_sock *req, struct sock *newsk, + const gfp_t priority); + + char name[TCP_ULP_NAME_MAX]; + struct module *owner; +}; +int tcp_register_ulp(struct tcp_ulp_ops *type); +void tcp_unregister_ulp(struct tcp_ulp_ops *type); +int tcp_set_ulp(struct sock *sk, const char *name); +void tcp_get_available_ulp(char *buf, size_t len); +void tcp_cleanup_ulp(struct sock *sk); +void tcp_update_ulp(struct sock *sk, struct proto *p, + void (*write_space)(struct sock *sk)); + +#define MODULE_ALIAS_TCP_ULP(name) \ + __MODULE_INFO(alias, alias_userspace, name); \ + __MODULE_INFO(alias, alias_tcp_ulp, "tcp-ulp-" name) + +#ifdef CONFIG_NET_SOCK_MSG +struct sk_msg; +struct sk_psock; + +#ifdef CONFIG_BPF_SYSCALL +int tcp_bpf_update_proto(struct sock *sk, struct sk_psock *psock, bool restore); +void tcp_bpf_clone(const struct sock *sk, struct sock *newsk); +#endif /* CONFIG_BPF_SYSCALL */ + +#ifdef CONFIG_INET +void tcp_eat_skb(struct sock *sk, struct sk_buff *skb); +#else +static inline void tcp_eat_skb(struct sock *sk, struct sk_buff *skb) +{ +} +#endif + +int tcp_bpf_sendmsg_redir(struct sock *sk, bool ingress, + struct sk_msg *msg, u32 bytes, int flags); +#endif /* CONFIG_NET_SOCK_MSG */ + +#if !defined(CONFIG_BPF_SYSCALL) || !defined(CONFIG_NET_SOCK_MSG) +static inline void tcp_bpf_clone(const struct sock *sk, struct sock *newsk) +{ +} +#endif + +#ifdef CONFIG_CGROUP_BPF +static inline void bpf_skops_init_skb(struct bpf_sock_ops_kern *skops, + struct sk_buff *skb, + unsigned int end_offset) +{ + skops->skb = skb; + skops->skb_data_end = skb->data + end_offset; +} +#else +static inline void bpf_skops_init_skb(struct bpf_sock_ops_kern *skops, + struct sk_buff *skb, + unsigned int end_offset) +{ +} +#endif + +/* Call BPF_SOCK_OPS program that returns an int. If the return value + * is < 0, then the BPF op failed (for example if the loaded BPF + * program does not support the chosen operation or there is no BPF + * program loaded). + */ +#ifdef CONFIG_BPF +static inline int tcp_call_bpf(struct sock *sk, int op, u32 nargs, u32 *args) +{ + struct bpf_sock_ops_kern sock_ops; + int ret; + + memset(&sock_ops, 0, offsetof(struct bpf_sock_ops_kern, temp)); + if (sk_fullsock(sk)) { + sock_ops.is_fullsock = 1; + sock_owned_by_me(sk); + } + + sock_ops.sk = sk; + sock_ops.op = op; + if (nargs > 0) + memcpy(sock_ops.args, args, nargs * sizeof(*args)); + + ret = BPF_CGROUP_RUN_PROG_SOCK_OPS(&sock_ops); + if (ret == 0) + ret = sock_ops.reply; + else + ret = -1; + return ret; +} + +static inline int tcp_call_bpf_2arg(struct sock *sk, int op, u32 arg1, u32 arg2) +{ + u32 args[2] = {arg1, arg2}; + + return tcp_call_bpf(sk, op, 2, args); +} + +static inline int tcp_call_bpf_3arg(struct sock *sk, int op, u32 arg1, u32 arg2, + u32 arg3) +{ + u32 args[3] = {arg1, arg2, arg3}; + + return tcp_call_bpf(sk, op, 3, args); +} + +#else +static inline int tcp_call_bpf(struct sock *sk, int op, u32 nargs, u32 *args) +{ + return -EPERM; +} + +static inline int tcp_call_bpf_2arg(struct sock *sk, int op, u32 arg1, u32 arg2) +{ + return -EPERM; +} + +static inline int tcp_call_bpf_3arg(struct sock *sk, int op, u32 arg1, u32 arg2, + u32 arg3) +{ + return -EPERM; +} + +#endif + +static inline u32 tcp_timeout_init(struct sock *sk) +{ + int timeout; + + timeout = tcp_call_bpf(sk, BPF_SOCK_OPS_TIMEOUT_INIT, 0, NULL); + + if (timeout <= 0) + timeout = TCP_TIMEOUT_INIT; + return min_t(int, timeout, TCP_RTO_MAX); +} + +static inline u32 tcp_rwnd_init_bpf(struct sock *sk) +{ + int rwnd; + + rwnd = tcp_call_bpf(sk, BPF_SOCK_OPS_RWND_INIT, 0, NULL); + + if (rwnd < 0) + rwnd = 0; + return rwnd; +} + +static inline bool tcp_bpf_ca_needs_ecn(struct sock *sk) +{ + return (tcp_call_bpf(sk, BPF_SOCK_OPS_NEEDS_ECN, 0, NULL) == 1); +} + +static inline void tcp_bpf_rtt(struct sock *sk) +{ + if (BPF_SOCK_OPS_TEST_FLAG(tcp_sk(sk), BPF_SOCK_OPS_RTT_CB_FLAG)) + tcp_call_bpf(sk, BPF_SOCK_OPS_RTT_CB, 0, NULL); +} + +#if IS_ENABLED(CONFIG_SMC) +extern struct static_key_false tcp_have_smc; +#endif + +#if IS_ENABLED(CONFIG_TLS_DEVICE) +void clean_acked_data_enable(struct inet_connection_sock *icsk, + void (*cad)(struct sock *sk, u32 ack_seq)); +void clean_acked_data_disable(struct inet_connection_sock *icsk); +void clean_acked_data_flush(void); +#endif + +DECLARE_STATIC_KEY_FALSE(tcp_tx_delay_enabled); +static inline void tcp_add_tx_delay(struct sk_buff *skb, + const struct tcp_sock *tp) +{ + if (static_branch_unlikely(&tcp_tx_delay_enabled)) + skb->skb_mstamp_ns += (u64)tp->tcp_tx_delay * NSEC_PER_USEC; +} + +/* Compute Earliest Departure Time for some control packets + * like ACK or RST for TIME_WAIT or non ESTABLISHED sockets. + */ +static inline u64 tcp_transmit_time(const struct sock *sk) +{ + if (static_branch_unlikely(&tcp_tx_delay_enabled)) { + u32 delay = (sk->sk_state == TCP_TIME_WAIT) ? + tcp_twsk(sk)->tw_tx_delay : tcp_sk(sk)->tcp_tx_delay; + + return tcp_clock_ns() + (u64)delay * NSEC_PER_USEC; + } + return 0; +} + +#endif /* _TCP_H */ |