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tcp.c
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tcp.c
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// 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.
*
* Implementation of the Transmission Control Protocol(TCP).
*
* Authors: Ross Biro
* Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
* Mark Evans, <evansmp@uhura.aston.ac.uk>
* Corey Minyard <wf-rch!minyard@relay.EU.net>
* Florian La Roche, <flla@stud.uni-sb.de>
* Charles Hedrick, <hedrick@klinzhai.rutgers.edu>
* Linus Torvalds, <torvalds@cs.helsinki.fi>
* Alan Cox, <gw4pts@gw4pts.ampr.org>
* Matthew Dillon, <dillon@apollo.west.oic.com>
* Arnt Gulbrandsen, <agulbra@nvg.unit.no>
* Jorge Cwik, <jorge@laser.satlink.net>
*
* Fixes:
* Alan Cox : Numerous verify_area() calls
* Alan Cox : Set the ACK bit on a reset
* Alan Cox : Stopped it crashing if it closed while
* sk->inuse=1 and was trying to connect
* (tcp_err()).
* Alan Cox : All icmp error handling was broken
* pointers passed where wrong and the
* socket was looked up backwards. Nobody
* tested any icmp error code obviously.
* Alan Cox : tcp_err() now handled properly. It
* wakes people on errors. poll
* behaves and the icmp error race
* has gone by moving it into sock.c
* Alan Cox : tcp_send_reset() fixed to work for
* everything not just packets for
* unknown sockets.
* Alan Cox : tcp option processing.
* Alan Cox : Reset tweaked (still not 100%) [Had
* syn rule wrong]
* Herp Rosmanith : More reset fixes
* Alan Cox : No longer acks invalid rst frames.
* Acking any kind of RST is right out.
* Alan Cox : Sets an ignore me flag on an rst
* receive otherwise odd bits of prattle
* escape still
* Alan Cox : Fixed another acking RST frame bug.
* Should stop LAN workplace lockups.
* Alan Cox : Some tidyups using the new skb list
* facilities
* Alan Cox : sk->keepopen now seems to work
* Alan Cox : Pulls options out correctly on accepts
* Alan Cox : Fixed assorted sk->rqueue->next errors
* Alan Cox : PSH doesn't end a TCP read. Switched a
* bit to skb ops.
* Alan Cox : Tidied tcp_data to avoid a potential
* nasty.
* Alan Cox : Added some better commenting, as the
* tcp is hard to follow
* Alan Cox : Removed incorrect check for 20 * psh
* Michael O'Reilly : ack < copied bug fix.
* Johannes Stille : Misc tcp fixes (not all in yet).
* Alan Cox : FIN with no memory -> CRASH
* Alan Cox : Added socket option proto entries.
* Also added awareness of them to accept.
* Alan Cox : Added TCP options (SOL_TCP)
* Alan Cox : Switched wakeup calls to callbacks,
* so the kernel can layer network
* sockets.
* Alan Cox : Use ip_tos/ip_ttl settings.
* Alan Cox : Handle FIN (more) properly (we hope).
* Alan Cox : RST frames sent on unsynchronised
* state ack error.
* Alan Cox : Put in missing check for SYN bit.
* Alan Cox : Added tcp_select_window() aka NET2E
* window non shrink trick.
* Alan Cox : Added a couple of small NET2E timer
* fixes
* Charles Hedrick : TCP fixes
* Toomas Tamm : TCP window fixes
* Alan Cox : Small URG fix to rlogin ^C ack fight
* Charles Hedrick : Rewrote most of it to actually work
* Linus : Rewrote tcp_read() and URG handling
* completely
* Gerhard Koerting: Fixed some missing timer handling
* Matthew Dillon : Reworked TCP machine states as per RFC
* Gerhard Koerting: PC/TCP workarounds
* Adam Caldwell : Assorted timer/timing errors
* Matthew Dillon : Fixed another RST bug
* Alan Cox : Move to kernel side addressing changes.
* Alan Cox : Beginning work on TCP fastpathing
* (not yet usable)
* Arnt Gulbrandsen: Turbocharged tcp_check() routine.
* Alan Cox : TCP fast path debugging
* Alan Cox : Window clamping
* Michael Riepe : Bug in tcp_check()
* Matt Dillon : More TCP improvements and RST bug fixes
* Matt Dillon : Yet more small nasties remove from the
* TCP code (Be very nice to this man if
* tcp finally works 100%) 8)
* Alan Cox : BSD accept semantics.
* Alan Cox : Reset on closedown bug.
* Peter De Schrijver : ENOTCONN check missing in tcp_sendto().
* Michael Pall : Handle poll() after URG properly in
* all cases.
* Michael Pall : Undo the last fix in tcp_read_urg()
* (multi URG PUSH broke rlogin).
* Michael Pall : Fix the multi URG PUSH problem in
* tcp_readable(), poll() after URG
* works now.
* Michael Pall : recv(...,MSG_OOB) never blocks in the
* BSD api.
* Alan Cox : Changed the semantics of sk->socket to
* fix a race and a signal problem with
* accept() and async I/O.
* Alan Cox : Relaxed the rules on tcp_sendto().
* Yury Shevchuk : Really fixed accept() blocking problem.
* Craig I. Hagan : Allow for BSD compatible TIME_WAIT for
* clients/servers which listen in on
* fixed ports.
* Alan Cox : Cleaned the above up and shrank it to
* a sensible code size.
* Alan Cox : Self connect lockup fix.
* Alan Cox : No connect to multicast.
* Ross Biro : Close unaccepted children on master
* socket close.
* Alan Cox : Reset tracing code.
* Alan Cox : Spurious resets on shutdown.
* Alan Cox : Giant 15 minute/60 second timer error
* Alan Cox : Small whoops in polling before an
* accept.
* Alan Cox : Kept the state trace facility since
* it's handy for debugging.
* Alan Cox : More reset handler fixes.
* Alan Cox : Started rewriting the code based on
* the RFC's for other useful protocol
* references see: Comer, KA9Q NOS, and
* for a reference on the difference
* between specifications and how BSD
* works see the 4.4lite source.
* A.N.Kuznetsov : Don't time wait on completion of tidy
* close.
* Linus Torvalds : Fin/Shutdown & copied_seq changes.
* Linus Torvalds : Fixed BSD port reuse to work first syn
* Alan Cox : Reimplemented timers as per the RFC
* and using multiple timers for sanity.
* Alan Cox : Small bug fixes, and a lot of new
* comments.
* Alan Cox : Fixed dual reader crash by locking
* the buffers (much like datagram.c)
* Alan Cox : Fixed stuck sockets in probe. A probe
* now gets fed up of retrying without
* (even a no space) answer.
* Alan Cox : Extracted closing code better
* Alan Cox : Fixed the closing state machine to
* resemble the RFC.
* Alan Cox : More 'per spec' fixes.
* Jorge Cwik : Even faster checksumming.
* Alan Cox : tcp_data() doesn't ack illegal PSH
* only frames. At least one pc tcp stack
* generates them.
* Alan Cox : Cache last socket.
* Alan Cox : Per route irtt.
* Matt Day : poll()->select() match BSD precisely on error
* Alan Cox : New buffers
* Marc Tamsky : Various sk->prot->retransmits and
* sk->retransmits misupdating fixed.
* Fixed tcp_write_timeout: stuck close,
* and TCP syn retries gets used now.
* Mark Yarvis : In tcp_read_wakeup(), don't send an
* ack if state is TCP_CLOSED.
* Alan Cox : Look up device on a retransmit - routes may
* change. Doesn't yet cope with MSS shrink right
* but it's a start!
* Marc Tamsky : Closing in closing fixes.
* Mike Shaver : RFC1122 verifications.
* Alan Cox : rcv_saddr errors.
* Alan Cox : Block double connect().
* Alan Cox : Small hooks for enSKIP.
* Alexey Kuznetsov: Path MTU discovery.
* Alan Cox : Support soft errors.
* Alan Cox : Fix MTU discovery pathological case
* when the remote claims no mtu!
* Marc Tamsky : TCP_CLOSE fix.
* Colin (G3TNE) : Send a reset on syn ack replies in
* window but wrong (fixes NT lpd problems)
* Pedro Roque : Better TCP window handling, delayed ack.
* Joerg Reuter : No modification of locked buffers in
* tcp_do_retransmit()
* Eric Schenk : Changed receiver side silly window
* avoidance algorithm to BSD style
* algorithm. This doubles throughput
* against machines running Solaris,
* and seems to result in general
* improvement.
* Stefan Magdalinski : adjusted tcp_readable() to fix FIONREAD
* Willy Konynenberg : Transparent proxying support.
* Mike McLagan : Routing by source
* Keith Owens : Do proper merging with partial SKB's in
* tcp_do_sendmsg to avoid burstiness.
* Eric Schenk : Fix fast close down bug with
* shutdown() followed by close().
* Andi Kleen : Make poll agree with SIGIO
* Salvatore Sanfilippo : Support SO_LINGER with linger == 1 and
* lingertime == 0 (RFC 793 ABORT Call)
* Hirokazu Takahashi : Use copy_from_user() instead of
* csum_and_copy_from_user() if possible.
*
* Description of States:
*
* TCP_SYN_SENT sent a connection request, waiting for ack
*
* TCP_SYN_RECV received a connection request, sent ack,
* waiting for final ack in three-way handshake.
*
* TCP_ESTABLISHED connection established
*
* TCP_FIN_WAIT1 our side has shutdown, waiting to complete
* transmission of remaining buffered data
*
* TCP_FIN_WAIT2 all buffered data sent, waiting for remote
* to shutdown
*
* TCP_CLOSING both sides have shutdown but we still have
* data we have to finish sending
*
* TCP_TIME_WAIT timeout to catch resent junk before entering
* closed, can only be entered from FIN_WAIT2
* or CLOSING. Required because the other end
* may not have gotten our last ACK causing it
* to retransmit the data packet (which we ignore)
*
* TCP_CLOSE_WAIT remote side has shutdown and is waiting for
* us to finish writing our data and to shutdown
* (we have to close() to move on to LAST_ACK)
*
* TCP_LAST_ACK out side has shutdown after remote has
* shutdown. There may still be data in our
* buffer that we have to finish sending
*
* TCP_CLOSE socket is finished
*/
#define pr_fmt(fmt) "TCP: " fmt
#include <crypto/hash.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/types.h>
#include <linux/fcntl.h>
#include <linux/poll.h>
#include <linux/inet_diag.h>
#include <linux/init.h>
#include <linux/fs.h>
#include <linux/skbuff.h>
#include <linux/scatterlist.h>
#include <linux/splice.h>
#include <linux/net.h>
#include <linux/socket.h>
#include <linux/random.h>
#include <linux/memblock.h>
#include <linux/highmem.h>
#include <linux/cache.h>
#include <linux/err.h>
#include <linux/time.h>
#include <linux/slab.h>
#include <linux/errqueue.h>
#include <linux/static_key.h>
#include <linux/btf.h>
#include <net/icmp.h>
#include <net/inet_common.h>
#include <net/tcp.h>
#include <net/mptcp.h>
#include <net/xfrm.h>
#include <net/ip.h>
#include <net/sock.h>
#include <linux/uaccess.h>
#include <asm/ioctls.h>
#include <net/busy_poll.h>
/* Track pending CMSGs. */
enum {
TCP_CMSG_INQ = 1,
TCP_CMSG_TS = 2
};
DEFINE_PER_CPU(unsigned int, tcp_orphan_count);
EXPORT_PER_CPU_SYMBOL_GPL(tcp_orphan_count);
long sysctl_tcp_mem[3] __read_mostly;
EXPORT_SYMBOL(sysctl_tcp_mem);
atomic_long_t tcp_memory_allocated ____cacheline_aligned_in_smp; /* Current allocated memory. */
EXPORT_SYMBOL(tcp_memory_allocated);
DEFINE_PER_CPU(int, tcp_memory_per_cpu_fw_alloc);
EXPORT_PER_CPU_SYMBOL_GPL(tcp_memory_per_cpu_fw_alloc);
#if IS_ENABLED(CONFIG_SMC)
DEFINE_STATIC_KEY_FALSE(tcp_have_smc);
EXPORT_SYMBOL(tcp_have_smc);
#endif
/*
* Current number of TCP sockets.
*/
struct percpu_counter tcp_sockets_allocated ____cacheline_aligned_in_smp;
EXPORT_SYMBOL(tcp_sockets_allocated);
/*
* TCP splice context
*/
struct tcp_splice_state {
struct pipe_inode_info *pipe;
size_t len;
unsigned int flags;
};
/*
* Pressure flag: try to collapse.
* Technical note: it is used by multiple contexts non atomically.
* All the __sk_mem_schedule() is of this nature: accounting
* is strict, actions are advisory and have some latency.
*/
unsigned long tcp_memory_pressure __read_mostly;
EXPORT_SYMBOL_GPL(tcp_memory_pressure);
void tcp_enter_memory_pressure(struct sock *sk)
{
unsigned long val;
if (READ_ONCE(tcp_memory_pressure))
return;
val = jiffies;
if (!val)
val--;
if (!cmpxchg(&tcp_memory_pressure, 0, val))
NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPMEMORYPRESSURES);
}
EXPORT_SYMBOL_GPL(tcp_enter_memory_pressure);
void tcp_leave_memory_pressure(struct sock *sk)
{
unsigned long val;
if (!READ_ONCE(tcp_memory_pressure))
return;
val = xchg(&tcp_memory_pressure, 0);
if (val)
NET_ADD_STATS(sock_net(sk), LINUX_MIB_TCPMEMORYPRESSURESCHRONO,
jiffies_to_msecs(jiffies - val));
}
EXPORT_SYMBOL_GPL(tcp_leave_memory_pressure);
/* Convert seconds to retransmits based on initial and max timeout */
static u8 secs_to_retrans(int seconds, int timeout, int rto_max)
{
u8 res = 0;
if (seconds > 0) {
int period = timeout;
res = 1;
while (seconds > period && res < 255) {
res++;
timeout <<= 1;
if (timeout > rto_max)
timeout = rto_max;
period += timeout;
}
}
return res;
}
/* Convert retransmits to seconds based on initial and max timeout */
static int retrans_to_secs(u8 retrans, int timeout, int rto_max)
{
int period = 0;
if (retrans > 0) {
period = timeout;
while (--retrans) {
timeout <<= 1;
if (timeout > rto_max)
timeout = rto_max;
period += timeout;
}
}
return period;
}
static u64 tcp_compute_delivery_rate(const struct tcp_sock *tp)
{
u32 rate = READ_ONCE(tp->rate_delivered);
u32 intv = READ_ONCE(tp->rate_interval_us);
u64 rate64 = 0;
if (rate && intv) {
rate64 = (u64)rate * tp->mss_cache * USEC_PER_SEC;
do_div(rate64, intv);
}
return rate64;
}
/* Address-family independent initialization for a tcp_sock.
*
* NOTE: A lot of things set to zero explicitly by call to
* sk_alloc() so need not be done here.
*/
void tcp_init_sock(struct sock *sk)
{
struct inet_connection_sock *icsk = inet_csk(sk);
struct tcp_sock *tp = tcp_sk(sk);
tp->out_of_order_queue = RB_ROOT;
sk->tcp_rtx_queue = RB_ROOT;
tcp_init_xmit_timers(sk);
INIT_LIST_HEAD(&tp->tsq_node);
INIT_LIST_HEAD(&tp->tsorted_sent_queue);
icsk->icsk_rto = TCP_TIMEOUT_INIT;
icsk->icsk_rto_min = TCP_RTO_MIN;
icsk->icsk_delack_max = TCP_DELACK_MAX;
tp->mdev_us = jiffies_to_usecs(TCP_TIMEOUT_INIT);
minmax_reset(&tp->rtt_min, tcp_jiffies32, ~0U);
/* So many TCP implementations out there (incorrectly) count the
* initial SYN frame in their delayed-ACK and congestion control
* algorithms that we must have the following bandaid to talk
* efficiently to them. -DaveM
*/
tcp_snd_cwnd_set(tp, TCP_INIT_CWND);
/* There's a bubble in the pipe until at least the first ACK. */
tp->app_limited = ~0U;
/* See draft-stevens-tcpca-spec-01 for discussion of the
* initialization of these values.
*/
tp->snd_ssthresh = TCP_INFINITE_SSTHRESH;
tp->snd_cwnd_clamp = ~0;
tp->mss_cache = TCP_MSS_DEFAULT;
tp->reordering = READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_reordering);
tcp_assign_congestion_control(sk);
tp->tsoffset = 0;
tp->rack.reo_wnd_steps = 1;
sk->sk_write_space = sk_stream_write_space;
sock_set_flag(sk, SOCK_USE_WRITE_QUEUE);
icsk->icsk_sync_mss = tcp_sync_mss;
WRITE_ONCE(sk->sk_sndbuf, READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_wmem[1]));
WRITE_ONCE(sk->sk_rcvbuf, READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_rmem[1]));
sk_sockets_allocated_inc(sk);
}
EXPORT_SYMBOL(tcp_init_sock);
static void tcp_tx_timestamp(struct sock *sk, u16 tsflags)
{
struct sk_buff *skb = tcp_write_queue_tail(sk);
if (tsflags && skb) {
struct skb_shared_info *shinfo = skb_shinfo(skb);
struct tcp_skb_cb *tcb = TCP_SKB_CB(skb);
sock_tx_timestamp(sk, tsflags, &shinfo->tx_flags);
if (tsflags & SOF_TIMESTAMPING_TX_ACK)
tcb->txstamp_ack = 1;
if (tsflags & SOF_TIMESTAMPING_TX_RECORD_MASK)
shinfo->tskey = TCP_SKB_CB(skb)->seq + skb->len - 1;
}
}
static bool tcp_stream_is_readable(struct sock *sk, int target)
{
if (tcp_epollin_ready(sk, target))
return true;
return sk_is_readable(sk);
}
/*
* Wait for a TCP event.
*
* Note that we don't need to lock the socket, as the upper poll layers
* take care of normal races (between the test and the event) and we don't
* go look at any of the socket buffers directly.
*/
__poll_t tcp_poll(struct file *file, struct socket *sock, poll_table *wait)
{
__poll_t mask;
struct sock *sk = sock->sk;
const struct tcp_sock *tp = tcp_sk(sk);
int state;
sock_poll_wait(file, sock, wait);
state = inet_sk_state_load(sk);
if (state == TCP_LISTEN)
return inet_csk_listen_poll(sk);
/* Socket is not locked. We are protected from async events
* by poll logic and correct handling of state changes
* made by other threads is impossible in any case.
*/
mask = 0;
/*
* EPOLLHUP is certainly not done right. But poll() doesn't
* have a notion of HUP in just one direction, and for a
* socket the read side is more interesting.
*
* Some poll() documentation says that EPOLLHUP is incompatible
* with the EPOLLOUT/POLLWR flags, so somebody should check this
* all. But careful, it tends to be safer to return too many
* bits than too few, and you can easily break real applications
* if you don't tell them that something has hung up!
*
* Check-me.
*
* Check number 1. EPOLLHUP is _UNMASKABLE_ event (see UNIX98 and
* our fs/select.c). It means that after we received EOF,
* poll always returns immediately, making impossible poll() on write()
* in state CLOSE_WAIT. One solution is evident --- to set EPOLLHUP
* if and only if shutdown has been made in both directions.
* Actually, it is interesting to look how Solaris and DUX
* solve this dilemma. I would prefer, if EPOLLHUP were maskable,
* then we could set it on SND_SHUTDOWN. BTW examples given
* in Stevens' books assume exactly this behaviour, it explains
* why EPOLLHUP is incompatible with EPOLLOUT. --ANK
*
* NOTE. Check for TCP_CLOSE is added. The goal is to prevent
* blocking on fresh not-connected or disconnected socket. --ANK
*/
if (sk->sk_shutdown == SHUTDOWN_MASK || state == TCP_CLOSE)
mask |= EPOLLHUP;
if (sk->sk_shutdown & RCV_SHUTDOWN)
mask |= EPOLLIN | EPOLLRDNORM | EPOLLRDHUP;
/* Connected or passive Fast Open socket? */
if (state != TCP_SYN_SENT &&
(state != TCP_SYN_RECV || rcu_access_pointer(tp->fastopen_rsk))) {
int target = sock_rcvlowat(sk, 0, INT_MAX);
u16 urg_data = READ_ONCE(tp->urg_data);
if (unlikely(urg_data) &&
READ_ONCE(tp->urg_seq) == READ_ONCE(tp->copied_seq) &&
!sock_flag(sk, SOCK_URGINLINE))
target++;
if (tcp_stream_is_readable(sk, target))
mask |= EPOLLIN | EPOLLRDNORM;
if (!(sk->sk_shutdown & SEND_SHUTDOWN)) {
if (__sk_stream_is_writeable(sk, 1)) {
mask |= EPOLLOUT | EPOLLWRNORM;
} else { /* send SIGIO later */
sk_set_bit(SOCKWQ_ASYNC_NOSPACE, sk);
set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
/* Race breaker. If space is freed after
* wspace test but before the flags are set,
* IO signal will be lost. Memory barrier
* pairs with the input side.
*/
smp_mb__after_atomic();
if (__sk_stream_is_writeable(sk, 1))
mask |= EPOLLOUT | EPOLLWRNORM;
}
} else
mask |= EPOLLOUT | EPOLLWRNORM;
if (urg_data & TCP_URG_VALID)
mask |= EPOLLPRI;
} else if (state == TCP_SYN_SENT && inet_sk(sk)->defer_connect) {
/* Active TCP fastopen socket with defer_connect
* Return EPOLLOUT so application can call write()
* in order for kernel to generate SYN+data
*/
mask |= EPOLLOUT | EPOLLWRNORM;
}
/* This barrier is coupled with smp_wmb() in tcp_reset() */
smp_rmb();
if (sk->sk_err || !skb_queue_empty_lockless(&sk->sk_error_queue))
mask |= EPOLLERR;
return mask;
}
EXPORT_SYMBOL(tcp_poll);
int tcp_ioctl(struct sock *sk, int cmd, unsigned long arg)
{
struct tcp_sock *tp = tcp_sk(sk);
int answ;
bool slow;
switch (cmd) {
case SIOCINQ:
if (sk->sk_state == TCP_LISTEN)
return -EINVAL;
slow = lock_sock_fast(sk);
answ = tcp_inq(sk);
unlock_sock_fast(sk, slow);
break;
case SIOCATMARK:
answ = READ_ONCE(tp->urg_data) &&
READ_ONCE(tp->urg_seq) == READ_ONCE(tp->copied_seq);
break;
case SIOCOUTQ:
if (sk->sk_state == TCP_LISTEN)
return -EINVAL;
if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV))
answ = 0;
else
answ = READ_ONCE(tp->write_seq) - tp->snd_una;
break;
case SIOCOUTQNSD:
if (sk->sk_state == TCP_LISTEN)
return -EINVAL;
if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV))
answ = 0;
else
answ = READ_ONCE(tp->write_seq) -
READ_ONCE(tp->snd_nxt);
break;
default:
return -ENOIOCTLCMD;
}
return put_user(answ, (int __user *)arg);
}
EXPORT_SYMBOL(tcp_ioctl);
void tcp_mark_push(struct tcp_sock *tp, struct sk_buff *skb)
{
TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_PSH;
tp->pushed_seq = tp->write_seq;
}
static inline bool forced_push(const struct tcp_sock *tp)
{
return after(tp->write_seq, tp->pushed_seq + (tp->max_window >> 1));
}
void tcp_skb_entail(struct sock *sk, struct sk_buff *skb)
{
struct tcp_sock *tp = tcp_sk(sk);
struct tcp_skb_cb *tcb = TCP_SKB_CB(skb);
tcb->seq = tcb->end_seq = tp->write_seq;
tcb->tcp_flags = TCPHDR_ACK;
__skb_header_release(skb);
tcp_add_write_queue_tail(sk, skb);
sk_wmem_queued_add(sk, skb->truesize);
sk_mem_charge(sk, skb->truesize);
if (tp->nonagle & TCP_NAGLE_PUSH)
tp->nonagle &= ~TCP_NAGLE_PUSH;
tcp_slow_start_after_idle_check(sk);
}
static inline void tcp_mark_urg(struct tcp_sock *tp, int flags)
{
if (flags & MSG_OOB)
tp->snd_up = tp->write_seq;
}
/* If a not yet filled skb is pushed, do not send it if
* we have data packets in Qdisc or NIC queues :
* Because TX completion will happen shortly, it gives a chance
* to coalesce future sendmsg() payload into this skb, without
* need for a timer, and with no latency trade off.
* As packets containing data payload have a bigger truesize
* than pure acks (dataless) packets, the last checks prevent
* autocorking if we only have an ACK in Qdisc/NIC queues,
* or if TX completion was delayed after we processed ACK packet.
*/
static bool tcp_should_autocork(struct sock *sk, struct sk_buff *skb,
int size_goal)
{
return skb->len < size_goal &&
READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_autocorking) &&
!tcp_rtx_queue_empty(sk) &&
refcount_read(&sk->sk_wmem_alloc) > skb->truesize &&
tcp_skb_can_collapse_to(skb);
}
void tcp_push(struct sock *sk, int flags, int mss_now,
int nonagle, int size_goal)
{
struct tcp_sock *tp = tcp_sk(sk);
struct sk_buff *skb;
skb = tcp_write_queue_tail(sk);
if (!skb)
return;
if (!(flags & MSG_MORE) || forced_push(tp))
tcp_mark_push(tp, skb);
tcp_mark_urg(tp, flags);
if (tcp_should_autocork(sk, skb, size_goal)) {
/* avoid atomic op if TSQ_THROTTLED bit is already set */
if (!test_bit(TSQ_THROTTLED, &sk->sk_tsq_flags)) {
NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPAUTOCORKING);
set_bit(TSQ_THROTTLED, &sk->sk_tsq_flags);
}
/* It is possible TX completion already happened
* before we set TSQ_THROTTLED.
*/
if (refcount_read(&sk->sk_wmem_alloc) > skb->truesize)
return;
}
if (flags & MSG_MORE)
nonagle = TCP_NAGLE_CORK;
__tcp_push_pending_frames(sk, mss_now, nonagle);
}
static int tcp_splice_data_recv(read_descriptor_t *rd_desc, struct sk_buff *skb,
unsigned int offset, size_t len)
{
struct tcp_splice_state *tss = rd_desc->arg.data;
int ret;
ret = skb_splice_bits(skb, skb->sk, offset, tss->pipe,
min(rd_desc->count, len), tss->flags);
if (ret > 0)
rd_desc->count -= ret;
return ret;
}
static int __tcp_splice_read(struct sock *sk, struct tcp_splice_state *tss)
{
/* Store TCP splice context information in read_descriptor_t. */
read_descriptor_t rd_desc = {
.arg.data = tss,
.count = tss->len,
};
return tcp_read_sock(sk, &rd_desc, tcp_splice_data_recv);
}
/**
* tcp_splice_read - splice data from TCP socket to a pipe
* @sock: socket to splice from
* @ppos: position (not valid)
* @pipe: pipe to splice to
* @len: number of bytes to splice
* @flags: splice modifier flags
*
* Description:
* Will read pages from given socket and fill them into a pipe.
*
**/
ssize_t tcp_splice_read(struct socket *sock, loff_t *ppos,
struct pipe_inode_info *pipe, size_t len,
unsigned int flags)
{
struct sock *sk = sock->sk;
struct tcp_splice_state tss = {
.pipe = pipe,
.len = len,
.flags = flags,
};
long timeo;
ssize_t spliced;
int ret;
sock_rps_record_flow(sk);
/*
* We can't seek on a socket input
*/
if (unlikely(*ppos))
return -ESPIPE;
ret = spliced = 0;
lock_sock(sk);
timeo = sock_rcvtimeo(sk, sock->file->f_flags & O_NONBLOCK);
while (tss.len) {
ret = __tcp_splice_read(sk, &tss);
if (ret < 0)
break;
else if (!ret) {
if (spliced)
break;
if (sock_flag(sk, SOCK_DONE))
break;
if (sk->sk_err) {
ret = sock_error(sk);
break;
}
if (sk->sk_shutdown & RCV_SHUTDOWN)
break;
if (sk->sk_state == TCP_CLOSE) {
/*
* This occurs when user tries to read
* from never connected socket.
*/
ret = -ENOTCONN;
break;
}
if (!timeo) {
ret = -EAGAIN;
break;
}
/* if __tcp_splice_read() got nothing while we have
* an skb in receive queue, we do not want to loop.
* This might happen with URG data.
*/
if (!skb_queue_empty(&sk->sk_receive_queue))
break;
sk_wait_data(sk, &timeo, NULL);
if (signal_pending(current)) {
ret = sock_intr_errno(timeo);
break;
}
continue;
}
tss.len -= ret;
spliced += ret;
if (!timeo)
break;
release_sock(sk);
lock_sock(sk);
if (sk->sk_err || sk->sk_state == TCP_CLOSE ||
(sk->sk_shutdown & RCV_SHUTDOWN) ||
signal_pending(current))
break;
}
release_sock(sk);
if (spliced)
return spliced;
return ret;
}
EXPORT_SYMBOL(tcp_splice_read);
struct sk_buff *tcp_stream_alloc_skb(struct sock *sk, int size, gfp_t gfp,
bool force_schedule)
{
struct sk_buff *skb;
skb = alloc_skb_fclone(size + MAX_TCP_HEADER, gfp);
if (likely(skb)) {
bool mem_scheduled;
skb->truesize = SKB_TRUESIZE(skb_end_offset(skb));
if (force_schedule) {
mem_scheduled = true;
sk_forced_mem_schedule(sk, skb->truesize);
} else {
mem_scheduled = sk_wmem_schedule(sk, skb->truesize);
}
if (likely(mem_scheduled)) {
skb_reserve(skb, MAX_TCP_HEADER);
skb->ip_summed = CHECKSUM_PARTIAL;
INIT_LIST_HEAD(&skb->tcp_tsorted_anchor);
return skb;
}
__kfree_skb(skb);
} else {
sk->sk_prot->enter_memory_pressure(sk);
sk_stream_moderate_sndbuf(sk);
}
return NULL;
}
static unsigned int tcp_xmit_size_goal(struct sock *sk, u32 mss_now,
int large_allowed)
{
struct tcp_sock *tp = tcp_sk(sk);
u32 new_size_goal, size_goal;
if (!large_allowed)
return mss_now;
/* Note : tcp_tso_autosize() will eventually split this later */
new_size_goal = tcp_bound_to_half_wnd(tp, sk->sk_gso_max_size);
/* We try hard to avoid divides here */
size_goal = tp->gso_segs * mss_now;
if (unlikely(new_size_goal < size_goal ||
new_size_goal >= size_goal + mss_now)) {
tp->gso_segs = min_t(u16, new_size_goal / mss_now,
sk->sk_gso_max_segs);
size_goal = tp->gso_segs * mss_now;
}
return max(size_goal, mss_now);
}
int tcp_send_mss(struct sock *sk, int *size_goal, int flags)
{
int mss_now;
mss_now = tcp_current_mss(sk);
*size_goal = tcp_xmit_size_goal(sk, mss_now, !(flags & MSG_OOB));
return mss_now;
}
/* In some cases, both sendpage() and sendmsg() could have added
* an skb to the write queue, but failed adding payload on it.
* We need to remove it to consume less memory, but more
* importantly be able to generate EPOLLOUT for Edge Trigger epoll()
* users.
*/
void tcp_remove_empty_skb(struct sock *sk)
{
struct sk_buff *skb = tcp_write_queue_tail(sk);
if (skb && TCP_SKB_CB(skb)->seq == TCP_SKB_CB(skb)->end_seq) {
tcp_unlink_write_queue(skb, sk);
if (tcp_write_queue_empty(sk))
tcp_chrono_stop(sk, TCP_CHRONO_BUSY);
tcp_wmem_free_skb(sk, skb);
}
}
/* skb changing from pure zc to mixed, must charge zc */
static int tcp_downgrade_zcopy_pure(struct sock *sk, struct sk_buff *skb)
{
if (unlikely(skb_zcopy_pure(skb))) {
u32 extra = skb->truesize -
SKB_TRUESIZE(skb_end_offset(skb));
if (!sk_wmem_schedule(sk, extra))
return -ENOMEM;
sk_mem_charge(sk, extra);
skb_shinfo(skb)->flags &= ~SKBFL_PURE_ZEROCOPY;
}
return 0;
}
static int tcp_wmem_schedule(struct sock *sk, int copy)
{
int left;
if (likely(sk_wmem_schedule(sk, copy)))
return copy;
/* We could be in trouble if we have nothing queued.
* Use whatever is left in sk->sk_forward_alloc and tcp_wmem[0]
* to guarantee some progress.
*/
left = sock_net(sk)->ipv4.sysctl_tcp_wmem[0] - sk->sk_wmem_queued;
if (left > 0)
sk_forced_mem_schedule(sk, min(left, copy));
return min(copy, sk->sk_forward_alloc);
}
static struct sk_buff *tcp_build_frag(struct sock *sk, int size_goal, int flags,
struct page *page, int offset, size_t *size)
{
struct sk_buff *skb = tcp_write_queue_tail(sk);
struct tcp_sock *tp = tcp_sk(sk);
bool can_coalesce;
int copy, i;
if (!skb || (copy = size_goal - skb->len) <= 0 ||
!tcp_skb_can_collapse_to(skb)) {
new_segment:
if (!sk_stream_memory_free(sk))
return NULL;
skb = tcp_stream_alloc_skb(sk, 0, sk->sk_allocation,
tcp_rtx_and_write_queues_empty(sk));
if (!skb)
return NULL;
#ifdef CONFIG_TLS_DEVICE
skb->decrypted = !!(flags & MSG_SENDPAGE_DECRYPTED);
#endif
tcp_skb_entail(sk, skb);
copy = size_goal;
}
if (copy > *size)
copy = *size;