cregit-Linux how code gets into the kernel

Release 4.11 net/rxrpc/input.c

Directory: net/rxrpc
/* RxRPC packet reception
 *
 * Copyright (C) 2007, 2016 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 *
 * 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.
 */


#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/module.h>
#include <linux/net.h>
#include <linux/skbuff.h>
#include <linux/errqueue.h>
#include <linux/udp.h>
#include <linux/in.h>
#include <linux/in6.h>
#include <linux/icmp.h>
#include <linux/gfp.h>
#include <net/sock.h>
#include <net/af_rxrpc.h>
#include <net/ip.h>
#include <net/udp.h>
#include <net/net_namespace.h>
#include "ar-internal.h"


static void rxrpc_proto_abort(const char *why, struct rxrpc_call *call, rxrpc_seq_t seq) { if (rxrpc_abort_call(why, call, seq, RX_PROTOCOL_ERROR, EBADMSG)) { set_bit(RXRPC_CALL_EV_ABORT, &call->events); rxrpc_queue_call(call); } }

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/* * Do TCP-style congestion management [RFC 5681]. */
static void rxrpc_congestion_management(struct rxrpc_call *call, struct sk_buff *skb, struct rxrpc_ack_summary *summary, rxrpc_serial_t acked_serial) { enum rxrpc_congest_change change = rxrpc_cong_no_change; unsigned int cumulative_acks = call->cong_cumul_acks; unsigned int cwnd = call->cong_cwnd; bool resend = false; summary->flight_size = (call->tx_top - call->tx_hard_ack) - summary->nr_acks; if (test_and_clear_bit(RXRPC_CALL_RETRANS_TIMEOUT, &call->flags)) { summary->retrans_timeo = true; call->cong_ssthresh = max_t(unsigned int, summary->flight_size / 2, 2); cwnd = 1; if (cwnd >= call->cong_ssthresh && call->cong_mode == RXRPC_CALL_SLOW_START) { call->cong_mode = RXRPC_CALL_CONGEST_AVOIDANCE; call->cong_tstamp = skb->tstamp; cumulative_acks = 0; } } cumulative_acks += summary->nr_new_acks; cumulative_acks += summary->nr_rot_new_acks; if (cumulative_acks > 255) cumulative_acks = 255; summary->mode = call->cong_mode; summary->cwnd = call->cong_cwnd; summary->ssthresh = call->cong_ssthresh; summary->cumulative_acks = cumulative_acks; summary->dup_acks = call->cong_dup_acks; switch (call->cong_mode) { case RXRPC_CALL_SLOW_START: if (summary->nr_nacks > 0) goto packet_loss_detected; if (summary->cumulative_acks > 0) cwnd += 1; if (cwnd >= call->cong_ssthresh) { call->cong_mode = RXRPC_CALL_CONGEST_AVOIDANCE; call->cong_tstamp = skb->tstamp; } goto out; case RXRPC_CALL_CONGEST_AVOIDANCE: if (summary->nr_nacks > 0) goto packet_loss_detected; /* We analyse the number of packets that get ACK'd per RTT * period and increase the window if we managed to fill it. */ if (call->peer->rtt_usage == 0) goto out; if (ktime_before(skb->tstamp, ktime_add_ns(call->cong_tstamp, call->peer->rtt))) goto out_no_clear_ca; change = rxrpc_cong_rtt_window_end; call->cong_tstamp = skb->tstamp; if (cumulative_acks >= cwnd) cwnd++; goto out; case RXRPC_CALL_PACKET_LOSS: if (summary->nr_nacks == 0) goto resume_normality; if (summary->new_low_nack) { change = rxrpc_cong_new_low_nack; call->cong_dup_acks = 1; if (call->cong_extra > 1) call->cong_extra = 1; goto send_extra_data; } call->cong_dup_acks++; if (call->cong_dup_acks < 3) goto send_extra_data; change = rxrpc_cong_begin_retransmission; call->cong_mode = RXRPC_CALL_FAST_RETRANSMIT; call->cong_ssthresh = max_t(unsigned int, summary->flight_size / 2, 2); cwnd = call->cong_ssthresh + 3; call->cong_extra = 0; call->cong_dup_acks = 0; resend = true; goto out; case RXRPC_CALL_FAST_RETRANSMIT: if (!summary->new_low_nack) { if (summary->nr_new_acks == 0) cwnd += 1; call->cong_dup_acks++; if (call->cong_dup_acks == 2) { change = rxrpc_cong_retransmit_again; call->cong_dup_acks = 0; resend = true; } } else { change = rxrpc_cong_progress; cwnd = call->cong_ssthresh; if (summary->nr_nacks == 0) goto resume_normality; } goto out; default: BUG(); goto out; } resume_normality: change = rxrpc_cong_cleared_nacks; call->cong_dup_acks = 0; call->cong_extra = 0; call->cong_tstamp = skb->tstamp; if (cwnd < call->cong_ssthresh) call->cong_mode = RXRPC_CALL_SLOW_START; else call->cong_mode = RXRPC_CALL_CONGEST_AVOIDANCE; out: cumulative_acks = 0; out_no_clear_ca: if (cwnd >= RXRPC_RXTX_BUFF_SIZE - 1) cwnd = RXRPC_RXTX_BUFF_SIZE - 1; call->cong_cwnd = cwnd; call->cong_cumul_acks = cumulative_acks; trace_rxrpc_congest(call, summary, acked_serial, change); if (resend && !test_and_set_bit(RXRPC_CALL_EV_RESEND, &call->events)) rxrpc_queue_call(call); return; packet_loss_detected: change = rxrpc_cong_saw_nack; call->cong_mode = RXRPC_CALL_PACKET_LOSS; call->cong_dup_acks = 0; goto send_extra_data; send_extra_data: /* Send some previously unsent DATA if we have some to advance the ACK * state. */ if (call->rxtx_annotations[call->tx_top & RXRPC_RXTX_BUFF_MASK] & RXRPC_TX_ANNO_LAST || summary->nr_acks != call->tx_top - call->tx_hard_ack) { call->cong_extra++; wake_up(&call->waitq); } goto out_no_clear_ca; }

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David Howells724100.00%3100.00%
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/* * Ping the other end to fill our RTT cache and to retrieve the rwind * and MTU parameters. */
static void rxrpc_send_ping(struct rxrpc_call *call, struct sk_buff *skb, int skew) { struct rxrpc_skb_priv *sp = rxrpc_skb(skb); ktime_t now = skb->tstamp; if (call->peer->rtt_usage < 3 || ktime_before(ktime_add_ms(call->peer->rtt_last_req, 1000), now)) rxrpc_propose_ACK(call, RXRPC_ACK_PING, skew, sp->hdr.serial, true, true, rxrpc_propose_ack_ping_for_params); }

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David Howells83100.00%3100.00%
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/* * Apply a hard ACK by advancing the Tx window. */
static void rxrpc_rotate_tx_window(struct rxrpc_call *call, rxrpc_seq_t to, struct rxrpc_ack_summary *summary) { struct sk_buff *skb, *list = NULL; int ix; u8 annotation; if (call->acks_lowest_nak == call->tx_hard_ack) { call->acks_lowest_nak = to; } else if (before_eq(call->acks_lowest_nak, to)) { summary->new_low_nack = true; call->acks_lowest_nak = to; } spin_lock(&call->lock); while (before(call->tx_hard_ack, to)) { call->tx_hard_ack++; ix = call->tx_hard_ack & RXRPC_RXTX_BUFF_MASK; skb = call->rxtx_buffer[ix]; annotation = call->rxtx_annotations[ix]; rxrpc_see_skb(skb, rxrpc_skb_tx_rotated); call->rxtx_buffer[ix] = NULL; call->rxtx_annotations[ix] = 0; skb->next = list; list = skb; if (annotation & RXRPC_TX_ANNO_LAST) set_bit(RXRPC_CALL_TX_LAST, &call->flags); if ((annotation & RXRPC_TX_ANNO_MASK) != RXRPC_TX_ANNO_ACK) summary->nr_rot_new_acks++; } spin_unlock(&call->lock); trace_rxrpc_transmit(call, (test_bit(RXRPC_CALL_TX_LAST, &call->flags) ? rxrpc_transmit_rotate_last : rxrpc_transmit_rotate)); wake_up(&call->waitq); while (list) { skb = list; list = skb->next; skb->next = NULL; rxrpc_free_skb(skb, rxrpc_skb_tx_freed); } }

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David Howells263100.00%8100.00%
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/* * End the transmission phase of a call. * * This occurs when we get an ACKALL packet, the first DATA packet of a reply, * or a final ACK packet. */
static bool rxrpc_end_tx_phase(struct rxrpc_call *call, bool reply_begun, const char *abort_why) { ASSERT(test_bit(RXRPC_CALL_TX_LAST, &call->flags)); write_lock(&call->state_lock); switch (call->state) { case RXRPC_CALL_CLIENT_SEND_REQUEST: case RXRPC_CALL_CLIENT_AWAIT_REPLY: if (reply_begun) call->state = RXRPC_CALL_CLIENT_RECV_REPLY; else call->state = RXRPC_CALL_CLIENT_AWAIT_REPLY; break; case RXRPC_CALL_SERVER_AWAIT_ACK: __rxrpc_call_completed(call); rxrpc_notify_socket(call); break; default: goto bad_state; } write_unlock(&call->state_lock); if (call->state == RXRPC_CALL_CLIENT_AWAIT_REPLY) { rxrpc_propose_ACK(call, RXRPC_ACK_IDLE, 0, 0, false, true, rxrpc_propose_ack_client_tx_end); trace_rxrpc_transmit(call, rxrpc_transmit_await_reply); } else { trace_rxrpc_transmit(call, rxrpc_transmit_end); } _leave(" = ok"); return true; bad_state: write_unlock(&call->state_lock); kdebug("end_tx %s", rxrpc_call_states[call->state]); rxrpc_proto_abort(abort_why, call, call->tx_top); return false; }

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David Howells186100.00%8100.00%
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/* * Begin the reply reception phase of a call. */
static bool rxrpc_receiving_reply(struct rxrpc_call *call) { struct rxrpc_ack_summary summary = { 0 }; rxrpc_seq_t top = READ_ONCE(call->tx_top); if (call->ackr_reason) { spin_lock_bh(&call->lock); call->ackr_reason = 0; call->resend_at = call->expire_at; call->ack_at = call->expire_at; spin_unlock_bh(&call->lock); rxrpc_set_timer(call, rxrpc_timer_init_for_reply, ktime_get_real()); } if (!test_bit(RXRPC_CALL_TX_LAST, &call->flags)) rxrpc_rotate_tx_window(call, top, &summary); if (!test_bit(RXRPC_CALL_TX_LAST, &call->flags)) { rxrpc_proto_abort("TXL", call, top); return false; } if (!rxrpc_end_tx_phase(call, true, "ETD")) return false; call->tx_phase = false; return true; }

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David Howells159100.00%5100.00%
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/* * Scan a jumbo packet to validate its structure and to work out how many * subpackets it contains. * * A jumbo packet is a collection of consecutive packets glued together with * little headers between that indicate how to change the initial header for * each subpacket. * * RXRPC_JUMBO_PACKET must be set on all but the last subpacket - and all but * the last are RXRPC_JUMBO_DATALEN in size. The last subpacket may be of any * size. */
static bool rxrpc_validate_jumbo(struct sk_buff *skb) { struct rxrpc_skb_priv *sp = rxrpc_skb(skb); unsigned int offset = sizeof(struct rxrpc_wire_header); unsigned int len = skb->len; int nr_jumbo = 1; u8 flags = sp->hdr.flags; do { nr_jumbo++; if (len - offset < RXRPC_JUMBO_SUBPKTLEN) goto protocol_error; if (flags & RXRPC_LAST_PACKET) goto protocol_error; offset += RXRPC_JUMBO_DATALEN; if (skb_copy_bits(skb, offset, &flags, 1) < 0) goto protocol_error; offset += sizeof(struct rxrpc_jumbo_header); } while (flags & RXRPC_JUMBO_PACKET); sp->nr_jumbo = nr_jumbo; return true; protocol_error: return false; }

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David Howells131100.00%6100.00%
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/* * Handle reception of a duplicate packet. * * We have to take care to avoid an attack here whereby we're given a series of * jumbograms, each with a sequence number one before the preceding one and * filled up to maximum UDP size. If they never send us the first packet in * the sequence, they can cause us to have to hold on to around 2MiB of kernel * space until the call times out. * * We limit the space usage by only accepting three duplicate jumbo packets per * call. After that, we tell the other side we're no longer accepting jumbos * (that information is encoded in the ACK packet). */
static void rxrpc_input_dup_data(struct rxrpc_call *call, rxrpc_seq_t seq, u8 annotation, bool *_jumbo_bad) { /* Discard normal packets that are duplicates. */ if (annotation == 0) return; /* Skip jumbo subpackets that are duplicates. When we've had three or * more partially duplicate jumbo packets, we refuse to take any more * jumbos for this call. */ if (!*_jumbo_bad) { call->nr_jumbo_bad++; *_jumbo_bad = true; } }

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David Howells48100.00%3100.00%
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/* * Process a DATA packet, adding the packet to the Rx ring. */
static void rxrpc_input_data(struct rxrpc_call *call, struct sk_buff *skb, u16 skew) { struct rxrpc_skb_priv *sp = rxrpc_skb(skb); enum rxrpc_call_state state; unsigned int offset = sizeof(struct rxrpc_wire_header); unsigned int ix; rxrpc_serial_t serial = sp->hdr.serial, ack_serial = 0; rxrpc_seq_t seq = sp->hdr.seq, hard_ack; bool immediate_ack = false, jumbo_bad = false, queued; u16 len; u8 ack = 0, flags, annotation = 0; _enter("{%u,%u},{%u,%u}", call->rx_hard_ack, call->rx_top, skb->len, seq); _proto("Rx DATA %%%u { #%u f=%02x }", sp->hdr.serial, seq, sp->hdr.flags); state = READ_ONCE(call->state); if (state >= RXRPC_CALL_COMPLETE) return; /* Received data implicitly ACKs all of the request packets we sent * when we're acting as a client. */ if ((state == RXRPC_CALL_CLIENT_SEND_REQUEST || state == RXRPC_CALL_CLIENT_AWAIT_REPLY) && !rxrpc_receiving_reply(call)) return; call->ackr_prev_seq = seq; hard_ack = READ_ONCE(call->rx_hard_ack); if (after(seq, hard_ack + call->rx_winsize)) { ack = RXRPC_ACK_EXCEEDS_WINDOW; ack_serial = serial; goto ack; } flags = sp->hdr.flags; if (flags & RXRPC_JUMBO_PACKET) { if (call->nr_jumbo_bad > 3) { ack = RXRPC_ACK_NOSPACE; ack_serial = serial; goto ack; } annotation = 1; } next_subpacket: queued = false; ix = seq & RXRPC_RXTX_BUFF_MASK; len = skb->len; if (flags & RXRPC_JUMBO_PACKET) len = RXRPC_JUMBO_DATALEN; if (flags & RXRPC_LAST_PACKET) { if (test_bit(RXRPC_CALL_RX_LAST, &call->flags) && seq != call->rx_top) return rxrpc_proto_abort("LSN", call, seq); } else { if (test_bit(RXRPC_CALL_RX_LAST, &call->flags) && after_eq(seq, call->rx_top)) return rxrpc_proto_abort("LSA", call, seq); } trace_rxrpc_rx_data(call, seq, serial, flags, annotation); if (before_eq(seq, hard_ack)) { ack = RXRPC_ACK_DUPLICATE; ack_serial = serial; goto skip; } if (flags & RXRPC_REQUEST_ACK && !ack) { ack = RXRPC_ACK_REQUESTED; ack_serial = serial; } if (call->rxtx_buffer[ix]) { rxrpc_input_dup_data(call, seq, annotation, &jumbo_bad); if (ack != RXRPC_ACK_DUPLICATE) { ack = RXRPC_ACK_DUPLICATE; ack_serial = serial; } immediate_ack = true; goto skip; } /* Queue the packet. We use a couple of memory barriers here as need * to make sure that rx_top is perceived to be set after the buffer * pointer and that the buffer pointer is set after the annotation and * the skb data. * * Barriers against rxrpc_recvmsg_data() and rxrpc_rotate_rx_window() * and also rxrpc_fill_out_ack(). */ rxrpc_get_skb(skb, rxrpc_skb_rx_got); call->rxtx_annotations[ix] = annotation; smp_wmb(); call->rxtx_buffer[ix] = skb; if (after(seq, call->rx_top)) { smp_store_release(&call->rx_top, seq); } else if (before(seq, call->rx_top)) { /* Send an immediate ACK if we fill in a hole */ if (!ack) { ack = RXRPC_ACK_DELAY; ack_serial = serial; } immediate_ack = true; } if (flags & RXRPC_LAST_PACKET) { set_bit(RXRPC_CALL_RX_LAST, &call->flags); trace_rxrpc_receive(call, rxrpc_receive_queue_last, serial, seq); } else { trace_rxrpc_receive(call, rxrpc_receive_queue, serial, seq); } queued = true; if (after_eq(seq, call->rx_expect_next)) { if (after(seq, call->rx_expect_next)) { _net("OOS %u > %u", seq, call->rx_expect_next); ack = RXRPC_ACK_OUT_OF_SEQUENCE; ack_serial = serial; } call->rx_expect_next = seq + 1; } skip: offset += len; if (flags & RXRPC_JUMBO_PACKET) { if (skb_copy_bits(skb, offset, &flags, 1) < 0) return rxrpc_proto_abort("XJF", call, seq); offset += sizeof(struct rxrpc_jumbo_header); seq++; serial++; annotation++; if (flags & RXRPC_JUMBO_PACKET) annotation |= RXRPC_RX_ANNO_JLAST; if (after(seq, hard_ack + call->rx_winsize)) { ack = RXRPC_ACK_EXCEEDS_WINDOW; ack_serial = serial; if (!jumbo_bad) { call->nr_jumbo_bad++; jumbo_bad = true; } goto ack; } _proto("Rx DATA Jumbo %%%u", serial); goto next_subpacket; } if (queued && flags & RXRPC_LAST_PACKET && !ack) { ack = RXRPC_ACK_DELAY; ack_serial = serial; } ack: if (ack) rxrpc_propose_ACK(call, ack, skew, ack_serial, immediate_ack, true, rxrpc_propose_ack_input_data); if (sp->hdr.seq == READ_ONCE(call->rx_hard_ack) + 1) rxrpc_notify_socket(call); _leave(" [queued]"); }

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David Howells826100.00%17100.00%
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/* * Process a requested ACK. */
static void rxrpc_input_requested_ack(struct rxrpc_call *call, ktime_t resp_time, rxrpc_serial_t orig_serial, rxrpc_serial_t ack_serial) { struct rxrpc_skb_priv *sp; struct sk_buff *skb; ktime_t sent_at; int ix; for (ix = 0; ix < RXRPC_RXTX_BUFF_SIZE; ix++) { skb = call->rxtx_buffer[ix]; if (!skb) continue; sp = rxrpc_skb(skb); if (sp->hdr.serial != orig_serial) continue; smp_rmb(); sent_at = skb->tstamp; goto found; } return; found: rxrpc_peer_add_rtt(call, rxrpc_rtt_rx_requested_ack, orig_serial, ack_serial, sent_at, resp_time); }

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David Howells114100.00%1100.00%
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/* * Process a ping response. */
static void rxrpc_input_ping_response(struct rxrpc_call *call, ktime_t resp_time, rxrpc_serial_t orig_serial, rxrpc_serial_t ack_serial) { rxrpc_serial_t ping_serial; ktime_t ping_time; ping_time = call->ping_time; smp_rmb(); ping_serial = call->ping_serial; if (!test_bit(RXRPC_CALL_PINGING, &call->flags) || before(orig_serial, ping_serial)) return; clear_bit(RXRPC_CALL_PINGING, &call->flags); if (after(orig_serial, ping_serial)) return; rxrpc_peer_add_rtt(call, rxrpc_rtt_rx_ping_response, orig_serial, ack_serial, ping_time, resp_time); }

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David Howells97100.00%2100.00%
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/* * Process the extra information that may be appended to an ACK packet */
static void rxrpc_input_ackinfo(struct rxrpc_call *call, struct sk_buff *skb, struct rxrpc_ackinfo *ackinfo) { struct rxrpc_skb_priv *sp = rxrpc_skb(skb); struct rxrpc_peer *peer; unsigned int mtu; bool wake = false; u32 rwind = ntohl(ackinfo->rwind); _proto("Rx ACK %%%u Info { rx=%u max=%u rwin=%u jm=%u }", sp->hdr.serial, ntohl(ackinfo->rxMTU), ntohl(ackinfo->maxMTU), rwind, ntohl(ackinfo->jumbo_max)); if (call->tx_winsize != rwind) { if (rwind > RXRPC_RXTX_BUFF_SIZE - 1) rwind = RXRPC_RXTX_BUFF_SIZE - 1; if (rwind > call->tx_winsize) wake = true; call->tx_winsize = rwind; } if (call->cong_ssthresh > rwind) call->cong_ssthresh = rwind; mtu = min(ntohl(ackinfo->rxMTU), ntohl(ackinfo->maxMTU)); peer = call->peer; if (mtu < peer->maxdata) { spin_lock_bh(&peer->lock); peer->maxdata = mtu; peer->mtu = mtu + peer->hdrsize; spin_unlock_bh(&peer->lock); _net("Net MTU %u (maxdata %u)", peer->mtu, peer->maxdata); } if (wake) wake_up(&call->waitq); }

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David Howells237100.00%6100.00%
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/* * Process individual soft ACKs. * * Each ACK in the array corresponds to one packet and can be either an ACK or * a NAK. If we get find an explicitly NAK'd packet we resend immediately; * packets that lie beyond the end of the ACK list are scheduled for resend by * the timer on the basis that the peer might just not have processed them at * the time the ACK was sent. */
static void rxrpc_input_soft_acks(struct rxrpc_call *call, u8 *acks, rxrpc_seq_t seq, int nr_acks, struct rxrpc_ack_summary *summary) { int ix; u8 annotation, anno_type; for (; nr_acks > 0; nr_acks--, seq++) { ix = seq & RXRPC_RXTX_BUFF_MASK; annotation