diff options
Diffstat (limited to 'include/net/tcp.h')
| -rw-r--r-- | include/net/tcp.h | 1721 |
1 files changed, 1721 insertions, 0 deletions
diff --git a/include/net/tcp.h b/include/net/tcp.h new file mode 100644 index 000000000..69096c703 --- /dev/null +++ b/include/net/tcp.h @@ -0,0 +1,1721 @@ +/* + * 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> + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation; either version + * 2 of the License, or (at your option) any later version. + */ +#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/crypto.h> +#include <linux/cryptohash.h> +#include <linux/kref.h> +#include <linux/ktime.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.h> +#include <net/snmp.h> +#include <net/ip.h> +#include <net/tcp_states.h> +#include <net/inet_ecn.h> +#include <net/dst.h> + +#include <linux/seq_file.h> +#include <linux/memcontrol.h> + +extern struct inet_hashinfo tcp_hashinfo; + +extern struct percpu_counter tcp_orphan_count; +void tcp_time_wait(struct sock *sk, int state, int timeo); + +#define MAX_TCP_HEADER (128 + MAX_HEADER) +#define MAX_TCP_OPTION_SPACE 40 + +/* + * 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 least 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 + +/* 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_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_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_SYNQ_INTERVAL (HZ/5) /* Period of SYNACK timer */ + +#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_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 + +/* + * 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 + +/* 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 + +/* 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 draft-hkchu-tcpm-initcwnd-01 */ +#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. SOCKOPT1/2 determine how to set max_qlen. + */ +#define TFO_SERVER_WO_SOCKOPT1 0x400 +#define TFO_SERVER_WO_SOCKOPT2 0x800 + +extern struct inet_timewait_death_row tcp_death_row; + +/* sysctl variables for tcp */ +extern int sysctl_tcp_timestamps; +extern int sysctl_tcp_window_scaling; +extern int sysctl_tcp_sack; +extern int sysctl_tcp_fin_timeout; +extern int sysctl_tcp_keepalive_time; +extern int sysctl_tcp_keepalive_probes; +extern int sysctl_tcp_keepalive_intvl; +extern int sysctl_tcp_syn_retries; +extern int sysctl_tcp_synack_retries; +extern int sysctl_tcp_retries1; +extern int sysctl_tcp_retries2; +extern int sysctl_tcp_orphan_retries; +extern int sysctl_tcp_syncookies; +extern int sysctl_tcp_fastopen; +extern int sysctl_tcp_retrans_collapse; +extern int sysctl_tcp_stdurg; +extern int sysctl_tcp_rfc1337; +extern int sysctl_tcp_abort_on_overflow; +extern int sysctl_tcp_max_orphans; +extern int sysctl_tcp_fack; +extern int sysctl_tcp_reordering; +extern int sysctl_tcp_max_reordering; +extern int sysctl_tcp_dsack; +extern long sysctl_tcp_mem[3]; +extern int sysctl_tcp_wmem[3]; +extern int sysctl_tcp_rmem[3]; +extern int sysctl_tcp_app_win; +extern int sysctl_tcp_adv_win_scale; +extern int sysctl_tcp_tw_reuse; +extern int sysctl_tcp_frto; +extern int sysctl_tcp_low_latency; +extern int sysctl_tcp_nometrics_save; +extern int sysctl_tcp_moderate_rcvbuf; +extern int sysctl_tcp_tso_win_divisor; +extern int sysctl_tcp_workaround_signed_windows; +extern int sysctl_tcp_slow_start_after_idle; +extern int sysctl_tcp_thin_linear_timeouts; +extern int sysctl_tcp_thin_dupack; +extern int sysctl_tcp_early_retrans; +extern int sysctl_tcp_limit_output_bytes; +extern int sysctl_tcp_challenge_ack_limit; +extern unsigned int sysctl_tcp_notsent_lowat; +extern int sysctl_tcp_min_tso_segs; +extern int sysctl_tcp_autocorking; +extern int sysctl_tcp_invalid_ratelimit; + +extern atomic_long_t tcp_memory_allocated; +extern struct percpu_counter tcp_sockets_allocated; +extern int 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 bool tcp_too_many_orphans(struct sock *sk, int shift) +{ + struct percpu_counter *ocp = sk->sk_prot->orphan_count; + int orphans = percpu_counter_read_positive(ocp); + + if (orphans << shift > sysctl_tcp_max_orphans) { + orphans = percpu_counter_sum_positive(ocp); + if (orphans << shift > sysctl_tcp_max_orphans) + return true; + } + return false; +} + +bool tcp_check_oom(struct sock *sk, int shift); + +/* syncookies: remember time of last synqueue overflow */ +static inline void tcp_synq_overflow(struct sock *sk) +{ + tcp_sk(sk)->rx_opt.ts_recent_stamp = jiffies; +} + +/* syncookies: no recent synqueue overflow on this listening socket? */ +static inline bool tcp_synq_no_recent_overflow(const struct sock *sk) +{ + unsigned long last_overflow = tcp_sk(sk)->rx_opt.ts_recent_stamp; + return time_after(jiffies, last_overflow + TCP_TIMEOUT_FALLBACK); +} + +extern struct proto tcp_prot; + +#define TCP_INC_STATS(net, field) SNMP_INC_STATS((net)->mib.tcp_statistics, field) +#define TCP_INC_STATS_BH(net, field) SNMP_INC_STATS_BH((net)->mib.tcp_statistics, field) +#define TCP_DEC_STATS(net, field) SNMP_DEC_STATS((net)->mib.tcp_statistics, field) +#define TCP_ADD_STATS_USER(net, field, val) SNMP_ADD_STATS_USER((net)->mib.tcp_statistics, field, val) +#define TCP_ADD_STATS(net, field, val) SNMP_ADD_STATS((net)->mib.tcp_statistics, field, val) + +void tcp_tasklet_init(void); + +void tcp_v4_err(struct sk_buff *skb, u32); + +void tcp_shutdown(struct sock *sk, int how); + +void tcp_v4_early_demux(struct sk_buff *skb); +int tcp_v4_rcv(struct sk_buff *skb); + +int tcp_v4_tw_remember_stamp(struct inet_timewait_sock *tw); +int tcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t size); +int tcp_sendpage(struct sock *sk, struct page *page, int offset, size_t size, + int flags); +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, unsigned long arg); +int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb, + const struct tcphdr *th, unsigned int len); +void tcp_rcv_established(struct sock *sk, struct sk_buff *skb, + const struct tcphdr *th, unsigned int len); +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); +ssize_t tcp_splice_read(struct socket *sk, loff_t *ppos, + struct pipe_inode_info *pipe, size_t len, + unsigned int flags); + +static inline void tcp_dec_quickack_mode(struct sock *sk, + const unsigned int pkts) +{ + struct inet_connection_sock *icsk = inet_csk(sk); + + if (icsk->icsk_ack.quick) { + 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); +int tcp_child_process(struct sock *parent, struct sock *child, + struct sk_buff *skb); +void tcp_enter_loss(struct sock *sk); +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, + bool paws_check, bool timestamps); +bool tcp_remember_stamp(struct sock *sk); +bool tcp_tw_remember_stamp(struct inet_timewait_sock *tw); +void tcp_fetch_timewait_stamp(struct sock *sk, struct dst_entry *dst); +void tcp_disable_fack(struct tcp_sock *tp); +void tcp_close(struct sock *sk, long timeout); +void tcp_init_sock(struct sock *sk); +unsigned int tcp_poll(struct file *file, struct socket *sock, + struct poll_table_struct *wait); +int tcp_getsockopt(struct sock *sk, int level, int optname, + char __user *optval, int __user *optlen); +int tcp_setsockopt(struct sock *sk, int level, int optname, + char __user *optval, unsigned int optlen); +int compat_tcp_getsockopt(struct sock *sk, int level, int optname, + char __user *optval, int __user *optlen); +int compat_tcp_setsockopt(struct sock *sk, int level, int optname, + char __user *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 nonblock, + int flags, int *addr_len); +void tcp_parse_options(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); +#ifdef CONFIG_TCP_STEALTH +const bool tcp_parse_tsval_option(u32 *tsval, const struct tcphdr *th); +int tcp_stealth_integrity(u16 *hash, u8 *secret, u8 *payload, int len); +#define be32_isn_to_be16_av(x) (((__be16 *)&x)[0]) +#define be32_isn_to_be16_ih(x) (((__be16 *)&x)[1]) +#endif + +/* + * 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); +int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb); +struct sock *tcp_create_openreq_child(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(struct sock *sk, struct sk_buff *skb, + struct request_sock *req, + struct dst_entry *dst); +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); +struct sk_buff *tcp_make_synack(struct sock *sk, struct dst_entry *dst, + struct request_sock *req, + struct tcp_fastopen_cookie *foc); +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 */ +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); +#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 + +static inline u32 tcp_cookie_time(void) +{ + u64 val = get_jiffies_64(); + + do_div(val, 60 * HZ); + return val; +} + +u32 __cookie_v4_init_sequence(const struct iphdr *iph, const struct tcphdr *th, + u16 *mssp); +__u32 cookie_v4_init_sequence(struct sock *sk, const struct sk_buff *skb, + __u16 *mss); +__u32 cookie_init_timestamp(struct request_sock *req); +bool cookie_timestamp_decode(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(struct sock *sk, const struct sk_buff *skb, + __u16 *mss); +#endif +/* tcp_output.c */ + +void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss, + int nonagle); +bool tcp_may_send_now(struct sock *sk); +int __tcp_retransmit_skb(struct sock *, struct sk_buff *); +int tcp_retransmit_skb(struct sock *, struct sk_buff *); +void tcp_retransmit_timer(struct sock *sk); +void tcp_xmit_retransmit_queue(struct sock *); +void tcp_simple_retransmit(struct sock *); +int tcp_trim_head(struct sock *, struct sk_buff *, u32); +int tcp_fragment(struct sock *, struct sk_buff *, u32, unsigned int, gfp_t); + +void tcp_send_probe0(struct sock *); +void tcp_send_partial(struct sock *); +int tcp_write_wakeup(struct sock *); +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); +void tcp_send_delayed_ack(struct sock *sk); +void tcp_send_loss_probe(struct sock *sk); +bool tcp_schedule_loss_probe(struct sock *sk); + +/* tcp_input.c */ +void tcp_resume_early_retransmit(struct sock *sk); +void tcp_rearm_rto(struct sock *sk); +void tcp_reset(struct sock *sk); + +/* tcp_timer.c */ +void tcp_init_xmit_timers(struct sock *); +static inline void tcp_clear_xmit_timers(struct sock *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); + +/* 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 >= 512) + 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 */ +typedef int (*sk_read_actor_t)(read_descriptor_t *, struct sk_buff *, + unsigned int, size_t); +int tcp_read_sock(struct sock *sk, read_descriptor_t *desc, + sk_read_actor_t recv_actor); + +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); +void tcp_init_buffer_space(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) +{ + 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 (skb_queue_empty(&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); +} + +/* 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 = TCP_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); +} + +/* 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 timestamps are only 32-bits, this causes a slight + * complication on 64-bit systems since we store a snapshot + * of jiffies in the buffer control blocks below. We decided + * to use only the low 32-bits of jiffies and hide the ugly + * casts with the following macro. + */ +#define tcp_time_stamp ((__u32)(jiffies)) + +static inline u32 tcp_skb_timestamp(const struct sk_buff *skb) +{ + return skb->skb_mstamp.stamp_jiffies; +} + + +#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 + +/* 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 is used in write queue only, + * cf tcp_skb_pcount() + */ + __u32 tcp_tw_isn; + __u32 tcp_gso_segs; + }; + __u8 tcp_flags; /* TCP header flags. (tcp[13]) */ + + __u8 sacked; /* State flags for SACK/FACK. */ +#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) */ +#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 */ + /* 1 byte hole */ + __u32 ack_seq; /* Sequence number ACK'd */ + union { + struct inet_skb_parm h4; +#if IS_ENABLED(CONFIG_IPV6) + struct inet6_skb_parm h6; +#endif + } header; /* For incoming frames */ +}; + +#define TCP_SKB_CB(__skb) ((struct tcp_skb_cb *)&((__skb)->cb[0])) + + +#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; +} +#endif + +/* 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 tcp_skb_pcount() > 1. */ +static inline int tcp_skb_mss(const struct sk_buff *skb) +{ + return skb_shinfo(skb)->gso_size; +} + +/* 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 */ + CA_EVENT_DELAYED_ACK, /* Delayed ack is sent */ + CA_EVENT_NON_DELAYED_ACK, +}; + +/* 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 + +union tcp_cc_info; + +struct tcp_congestion_ops { + 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); + + /* 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); + /* new value of cwnd after loss (optional) */ + u32 (*undo_cwnd)(struct sock *sk); + /* hook for packet ack accounting (optional) */ + void (*pkts_acked)(struct sock *sk, u32 num_acked, s32 rtt_us); + /* 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; +}; + +int tcp_register_congestion_control(struct tcp_congestion_ops *type); +void tcp_unregister_congestion_control(struct tcp_congestion_ops *type); + +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(const char *name); +void tcp_get_default_congestion_control(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); +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); +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_key(u32 key); +u32 tcp_ca_get_key_by_name(const char *name); +#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_set_ca_state(struct sock *sk, const u8 ca_state) +{ + struct inet_connection_sock *icsk = inet_csk(sk); + + if (icsk->icsk_ca_ops->set_state) + icsk->icsk_ca_ops->set_state(sk, ca_state); + icsk->icsk_ca_state = ca_state; +} + +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); +} + +/* 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 + * tcp_is_fack - FACK enabled, implies SACK enabled + */ +static inline int tcp_is_sack(const struct tcp_sock *tp) +{ + return tp->rx_opt.sack_ok; +} + +static inline bool tcp_is_reno(const struct tcp_sock *tp) +{ + return !tcp_is_sack(tp); +} + +static inline bool tcp_is_fack(const struct tcp_sock *tp) +{ + return tp->rx_opt.sack_ok & TCP_FACK_ENABLED; +} + +static inline void tcp_enable_fack(struct tcp_sock *tp) +{ + tp->rx_opt.sack_ok |= TCP_FACK_ENABLED; +} + +/* TCP early-retransmit (ER) is similar to but more conservative than + * the thin-dupack feature. Enable ER only if thin-dupack is disabled. + */ +static inline void tcp_enable_early_retrans(struct tcp_sock *tp) +{ + tp->do_early_retrans = sysctl_tcp_early_retrans && + sysctl_tcp_early_retrans < 4 && !sysctl_tcp_thin_dupack && + sysctl_tcp_reordering == 3; +} + +static inline void tcp_disable_early_retrans(struct tcp_sock *tp) +{ + tp->do_early_retrans = 0; +} + +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 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, + ((tp->snd_cwnd >> 1) + + (tp->snd_cwnd >> 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; +} + +/* Slow start with delack produces 3 packets of burst, so that + * it is safe "de facto". This will be the default - same as + * the default reordering threshold - but if reordering increases, + * we must be able to allow cwnd to burst at least this much in order + * to not pull it back when holes are filled. + */ +static __inline__ __u32 tcp_max_burst(const struct tcp_sock *tp) +{ + return tp->reordering; +} + +/* 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 in slow start, ensure cwnd grows to twice what was ACKed. */ + if (tp->snd_cwnd <= tp->snd_ssthresh) + return tp->snd_cwnd < 2 * tp->max_packets_out; + + return tp->is_cwnd_limited; +} + +static inline void tcp_check_probe_timer(struct sock *sk) +{ + const struct tcp_sock *tp = tcp_sk(sk); + const struct inet_connection_sock *icsk = inet_csk(sk); + + if (!tp->packets_out && !icsk->icsk_pending) + inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0, + icsk->icsk_rto, 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 __sum16 __tcp_checksum_complete(struct sk_buff *skb) +{ + return __skb_checksum_complete(skb); +} + +static inline bool tcp_checksum_complete(struct sk_buff *skb) +{ + return !skb_csum_unnecessary(skb) && + __tcp_checksum_complete(skb); +} + +/* Prequeue for VJ style copy to user, combined with checksumming. */ + +static inline void tcp_prequeue_init(struct tcp_sock *tp) +{ + tp->ucopy.task = NULL; + tp->ucopy.len = 0; + tp->ucopy.memory = 0; + skb_queue_head_init(&tp->ucopy.prequeue); +} + +bool tcp_prequeue(struct sock *sk, struct sk_buff *skb); + +#undef STATE_TRACE + +#ifdef STATE_TRACE +static const char *statename[]={ + "Unused","Established","Syn Sent","Syn Recv", + "Fin Wait 1","Fin Wait 2","Time Wait", "Close", + "Close Wait","Last ACK","Listen","Closing" +}; +#endif +void tcp_set_state(struct sock *sk, int state); + +void tcp_done(struct sock *sk); + +static inline void tcp_sack_reset(struct tcp_options_received *rx_opt) +{ + rx_opt->dsack = 0; + rx_opt->num_sacks = 0; +} + +u32 tcp_default_init_rwnd(u32 mss); + +/* Determine a window scaling and initial window to offer. */ +void tcp_select_initial_window(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(int space) +{ + return sysctl_tcp_adv_win_scale<=0 ? + (space>>(-sysctl_tcp_adv_win_scale)) : + space - (space>>sysctl_tcp_adv_win_scale); +} + +/* 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->sk_rcvbuf - + atomic_read(&sk->sk_rmem_alloc)); +} + +static inline int tcp_full_space(const struct sock *sk) +{ + return tcp_win_from_space(sk->sk_rcvbuf); +} + +extern void tcp_openreq_init_rwin(struct request_sock *req, + struct sock *sk, struct dst_entry *dst); + +void tcp_enter_memory_pressure(struct sock *sk); + +static inline int keepalive_intvl_when(const struct tcp_sock *tp) +{ + return tp->keepalive_intvl ? : sysctl_tcp_keepalive_intvl; +} + +static inline int keepalive_time_when(const struct tcp_sock *tp) +{ + return tp->keepalive_time ? : sysctl_tcp_keepalive_time; +} + +static inline int keepalive_probes(const struct tcp_sock *tp) +{ + return tp->keepalive_probes ? : 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_time_stamp - icsk->icsk_ack.lrcvtime, + tcp_time_stamp - tp->rcv_tstamp); +} + +static inline int tcp_fin_time(const struct sock *sk) +{ + int fin_timeout = tcp_sk(sk)->linger2 ? : 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(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 && 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_USER(net, TCP_MIB_RTOALGORITHM, 1); + TCP_ADD_STATS_USER(net, TCP_MIB_RTOMIN, TCP_RTO_MIN*1000/HZ); + TCP_ADD_STATS_USER(net, TCP_MIB_RTOMAX, TCP_RTO_MAX*1000/HZ); + TCP_ADD_STATS_USER(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; +} + +/* MD5 Signature */ +struct crypto_hash; + +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 */ + union tcp_md5_addr addr; + 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 hash_desc md5_desc; + union tcp_md5sum_block md5_blk; +}; + +/* - 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, const u8 *newkey, u8 newkeylen, gfp_t gfp); +int tcp_md5_do_del(struct sock *sk, const union tcp_md5_addr *addr, + int family); +struct tcp_md5sig_key *tcp_v4_md5_lookup(struct sock *sk, + const struct sock *addr_sk); + +#ifdef CONFIG_TCP_MD5SIG +struct tcp_md5sig_key *tcp_md5_do_lookup(struct sock *sk, + const union tcp_md5_addr *addr, + int family); +#define tcp_twsk_md5_key(twsk) ((twsk)->tw_md5_key) +#else +static inline struct tcp_md5sig_key *tcp_md5_do_lookup(struct sock *sk, + const union tcp_md5_addr *addr, + int family) +{ + return NULL; +} +#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_header(struct tcp_md5sig_pool *, const struct tcphdr *); +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, int *syn_loss, + unsigned long *last_syn_loss); +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() */ +}; +void tcp_free_fastopen_req(struct tcp_sock *tp); + +extern struct tcp_fastopen_context __rcu *tcp_fastopen_ctx; +int tcp_fastopen_reset_cipher(void *key, unsigned int len); +bool tcp_try_fastopen(struct sock *sk, struct sk_buff *skb, + struct request_sock *req, + struct tcp_fastopen_cookie *foc, + struct dst_entry *dst); +void tcp_fastopen_init_key_once(bool publish); +#define TCP_FASTOPEN_KEY_LENGTH 16 + +/* Fastopen key context */ +struct tcp_fastopen_context { + struct crypto_cipher *tfm; + __u8 key[TCP_FASTOPEN_KEY_LENGTH]; + struct rcu_head rcu; +}; + +/* write queue abstraction */ +static inline void tcp_write_queue_purge(struct sock *sk) +{ + struct sk_buff *skb; + + while ((skb = __skb_dequeue(&sk->sk_write_queue)) != NULL) + sk_wmem_free_skb(sk, skb); + sk_mem_reclaim(sk); + tcp_clear_all_retrans_hints(tcp_sk(sk)); +} + +static inline struct sk_buff *tcp_write_queue_head(const struct sock *sk) +{ + return skb_peek(&sk->sk_write_queue); +} + +static inline struct sk_buff *tcp_write_queue_tail(const struct sock *sk) +{ + return skb_peek_tail(&sk->sk_write_queue); +} + +static inline struct sk_buff *tcp_write_queue_next(const struct sock *sk, + const struct sk_buff *skb) +{ + return skb_queue_next(&sk->sk_write_queue, skb); +} + +static inline struct sk_buff *tcp_write_queue_prev(const struct sock *sk, + const struct sk_buff *skb) +{ + return skb_queue_prev(&sk->sk_write_queue, skb); +} + +#define tcp_for_write_queue(skb, sk) \ + skb_queue_walk(&(sk)->sk_write_queue, skb) + +#define tcp_for_write_queue_from(skb, sk) \ + skb_queue_walk_from(&(sk)->sk_write_queue, skb) + +#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 sk->sk_send_head; +} + +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); +} + +static inline void tcp_advance_send_head(struct sock *sk, const struct sk_buff *skb) +{ + if (tcp_skb_is_last(sk, skb)) + sk->sk_send_head = NULL; + else + sk->sk_send_head = tcp_write_queue_next(sk, skb); +} + +static inline void tcp_check_send_head(struct sock *sk, struct sk_buff *skb_unlinked) +{ + if (sk->sk_send_head == skb_unlinked) + sk->sk_send_head = NULL; +} + +static inline void tcp_init_send_head(struct sock *sk) +{ + sk->sk_send_head = NULL; +} + +static inline void __tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb) +{ + __skb_queue_tail(&sk->sk_write_queue, skb); +} + +static inline void tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb) +{ + __tcp_add_write_queue_tail(sk, skb); + + /* Queue it, remembering where we must start sending. */ + if (sk->sk_send_head == NULL) { + sk->sk_send_head = skb; + + if (tcp_sk(sk)->highest_sack == NULL) + tcp_sk(sk)->highest_sack = skb; + } +} + +static inline void __tcp_add_write_queue_head(struct sock *sk, struct sk_buff *skb) +{ + __skb_queue_head(&sk->sk_write_queue, skb); +} + +/* Insert buff after skb on the write queue of sk. */ +static inline void tcp_insert_write_queue_after(struct sk_buff *skb, + struct sk_buff *buff, + struct sock *sk) +{ + __skb_queue_after(&sk->sk_write_queue, skb, buff); +} + +/* 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); + + if (sk->sk_send_head == skb) + sk->sk_send_head = new; +} + +static inline void tcp_unlink_write_queue(struct sk_buff *skb, struct sock *sk) +{ + __skb_unlink(skb, &sk->sk_write_queue); +} + +static inline bool tcp_write_queue_empty(struct sock *sk) +{ + return skb_queue_empty(&sk->sk_write_queue); +} + +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 = tcp_skb_is_last(sk, skb) ? NULL : + tcp_write_queue_next(sk, 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_write_queue_head(sk); +} + +/* Called when old skb is about to be deleted (to be combined with new skb) */ +static inline void tcp_highest_sack_combine(struct sock *sk, + struct sk_buff *old, + struct sk_buff *new) +{ + if (tcp_sk(sk)->sacked_out && (old == tcp_sk(sk)->highest_sack)) + tcp_sk(sk)->highest_sack = new; +} + +/* 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_OPENREQ, + TCP_SEQ_STATE_ESTABLISHED, +}; + +int tcp_seq_open(struct inode *inode, struct file *file); + +struct tcp_seq_afinfo { + char *name; + sa_family_t family; + const struct file_operations *seq_fops; + struct seq_operations seq_ops; +}; + +struct tcp_iter_state { + struct seq_net_private p; + sa_family_t family; + enum tcp_seq_states state; + struct sock *syn_wait_sk; + int bucket, offset, sbucket, num; + kuid_t uid; + loff_t last_pos; +}; + +int tcp_proc_register(struct net *net, struct tcp_seq_afinfo *afinfo); +void tcp_proc_unregister(struct net *net, struct tcp_seq_afinfo *afinfo); + +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 sk_buff **head, struct sk_buff *skb); +int 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) +{ + return tp->notsent_lowat ?: sysctl_tcp_notsent_lowat; +} + +static inline bool tcp_stream_memory_free(const struct sock *sk) +{ + const struct tcp_sock *tp = tcp_sk(sk); + u32 notsent_bytes = tp->write_seq - tp->snd_nxt; + + return notsent_bytes < tcp_notsent_lowat(tp); +} + +#ifdef CONFIG_PROC_FS +int tcp4_proc_init(void); +void tcp4_proc_exit(void); +#endif + +int tcp_rtx_synack(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) (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, + char __user *optval, + int optlen); +#endif +}; + +struct tcp_request_sock_ops { + u16 mss_clamp; +#ifdef CONFIG_TCP_MD5SIG + struct tcp_md5sig_key *(*req_md5_lookup)(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 + void (*init_req)(struct request_sock *req, struct sock *sk, + struct sk_buff *skb); +#ifdef CONFIG_SYN_COOKIES + __u32 (*cookie_init_seq)(struct sock *sk, const struct sk_buff *skb, + __u16 *mss); +#endif + struct dst_entry *(*route_req)(struct sock *sk, struct flowi *fl, + const struct request_sock *req, + bool *strict); + __u32 (*init_seq)(const struct sk_buff *skb); + int (*send_synack)(struct sock *sk, struct dst_entry *dst, + struct flowi *fl, struct request_sock *req, + u16 queue_mapping, struct tcp_fastopen_cookie *foc); + void (*queue_hash_add)(struct sock *sk, struct request_sock *req, + const unsigned long timeout); +}; + +#ifdef CONFIG_SYN_COOKIES +static inline __u32 cookie_init_sequence(const struct tcp_request_sock_ops *ops, + struct sock *sk, struct sk_buff *skb, + __u16 *mss) +{ + return ops->cookie_init_seq(sk, skb, mss); +} +#else +static inline __u32 cookie_init_sequence(const struct tcp_request_sock_ops *ops, + 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); + +/* + * Save and compile IPv4 options, return a pointer to it + */ +static inline struct ip_options_rcu *tcp_v4_save_options(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(&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; +} + +#endif /* _TCP_H */ |