linux/net/sctp/output.c
Alexander Duyck 7c4e983c4f net: allow gso_max_size to exceed 65536
The code for gso_max_size was added originally to allow for debugging and
workaround of buggy devices that couldn't support TSO with blocks 64K in
size. The original reason for limiting it to 64K was because that was the
existing limits of IPv4 and non-jumbogram IPv6 length fields.

With the addition of Big TCP we can remove this limit and allow the value
to potentially go up to UINT_MAX and instead be limited by the tso_max_size
value.

So in order to support this we need to go through and clean up the
remaining users of the gso_max_size value so that the values will cap at
64K for non-TCPv6 flows. In addition we can clean up the GSO_MAX_SIZE value
so that 64K becomes GSO_LEGACY_MAX_SIZE and UINT_MAX will now be the upper
limit for GSO_MAX_SIZE.

v6: (edumazet) fixed a compile error if CONFIG_IPV6=n,
               in a new sk_trim_gso_size() helper.
               netif_set_tso_max_size() caps the requested TSO size
               with GSO_MAX_SIZE.

Signed-off-by: Alexander Duyck <alexanderduyck@fb.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2022-05-16 10:18:55 +01:00

866 lines
24 KiB
C

// SPDX-License-Identifier: GPL-2.0-or-later
/* SCTP kernel implementation
* (C) Copyright IBM Corp. 2001, 2004
* Copyright (c) 1999-2000 Cisco, Inc.
* Copyright (c) 1999-2001 Motorola, Inc.
*
* This file is part of the SCTP kernel implementation
*
* These functions handle output processing.
*
* Please send any bug reports or fixes you make to the
* email address(es):
* lksctp developers <linux-sctp@vger.kernel.org>
*
* Written or modified by:
* La Monte H.P. Yarroll <piggy@acm.org>
* Karl Knutson <karl@athena.chicago.il.us>
* Jon Grimm <jgrimm@austin.ibm.com>
* Sridhar Samudrala <sri@us.ibm.com>
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/wait.h>
#include <linux/time.h>
#include <linux/ip.h>
#include <linux/ipv6.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <net/inet_ecn.h>
#include <net/ip.h>
#include <net/icmp.h>
#include <net/net_namespace.h>
#include <linux/socket.h> /* for sa_family_t */
#include <net/sock.h>
#include <net/sctp/sctp.h>
#include <net/sctp/sm.h>
#include <net/sctp/checksum.h>
/* Forward declarations for private helpers. */
static enum sctp_xmit __sctp_packet_append_chunk(struct sctp_packet *packet,
struct sctp_chunk *chunk);
static enum sctp_xmit sctp_packet_can_append_data(struct sctp_packet *packet,
struct sctp_chunk *chunk);
static void sctp_packet_append_data(struct sctp_packet *packet,
struct sctp_chunk *chunk);
static enum sctp_xmit sctp_packet_will_fit(struct sctp_packet *packet,
struct sctp_chunk *chunk,
u16 chunk_len);
static void sctp_packet_reset(struct sctp_packet *packet)
{
/* sctp_packet_transmit() relies on this to reset size to the
* current overhead after sending packets.
*/
packet->size = packet->overhead;
packet->has_cookie_echo = 0;
packet->has_sack = 0;
packet->has_data = 0;
packet->has_auth = 0;
packet->ipfragok = 0;
packet->auth = NULL;
}
/* Config a packet.
* This appears to be a followup set of initializations.
*/
void sctp_packet_config(struct sctp_packet *packet, __u32 vtag,
int ecn_capable)
{
struct sctp_transport *tp = packet->transport;
struct sctp_association *asoc = tp->asoc;
struct sctp_sock *sp = NULL;
struct sock *sk;
pr_debug("%s: packet:%p vtag:0x%x\n", __func__, packet, vtag);
packet->vtag = vtag;
/* do the following jobs only once for a flush schedule */
if (!sctp_packet_empty(packet))
return;
/* set packet max_size with pathmtu, then calculate overhead */
packet->max_size = tp->pathmtu;
if (asoc) {
sk = asoc->base.sk;
sp = sctp_sk(sk);
}
packet->overhead = sctp_mtu_payload(sp, 0, 0);
packet->size = packet->overhead;
if (!asoc)
return;
/* update dst or transport pathmtu if in need */
if (!sctp_transport_dst_check(tp)) {
sctp_transport_route(tp, NULL, sp);
if (asoc->param_flags & SPP_PMTUD_ENABLE)
sctp_assoc_sync_pmtu(asoc);
} else if (!sctp_transport_pl_enabled(tp) &&
asoc->param_flags & SPP_PMTUD_ENABLE) {
if (!sctp_transport_pmtu_check(tp))
sctp_assoc_sync_pmtu(asoc);
}
if (asoc->pmtu_pending) {
if (asoc->param_flags & SPP_PMTUD_ENABLE)
sctp_assoc_sync_pmtu(asoc);
asoc->pmtu_pending = 0;
}
/* If there a is a prepend chunk stick it on the list before
* any other chunks get appended.
*/
if (ecn_capable) {
struct sctp_chunk *chunk = sctp_get_ecne_prepend(asoc);
if (chunk)
sctp_packet_append_chunk(packet, chunk);
}
if (!tp->dst)
return;
/* set packet max_size with gso_max_size if gso is enabled*/
rcu_read_lock();
if (__sk_dst_get(sk) != tp->dst) {
dst_hold(tp->dst);
sk_setup_caps(sk, tp->dst);
}
packet->max_size = sk_can_gso(sk) ? min(READ_ONCE(tp->dst->dev->gso_max_size),
GSO_LEGACY_MAX_SIZE)
: asoc->pathmtu;
rcu_read_unlock();
}
/* Initialize the packet structure. */
void sctp_packet_init(struct sctp_packet *packet,
struct sctp_transport *transport,
__u16 sport, __u16 dport)
{
pr_debug("%s: packet:%p transport:%p\n", __func__, packet, transport);
packet->transport = transport;
packet->source_port = sport;
packet->destination_port = dport;
INIT_LIST_HEAD(&packet->chunk_list);
/* The overhead will be calculated by sctp_packet_config() */
packet->overhead = 0;
sctp_packet_reset(packet);
packet->vtag = 0;
}
/* Free a packet. */
void sctp_packet_free(struct sctp_packet *packet)
{
struct sctp_chunk *chunk, *tmp;
pr_debug("%s: packet:%p\n", __func__, packet);
list_for_each_entry_safe(chunk, tmp, &packet->chunk_list, list) {
list_del_init(&chunk->list);
sctp_chunk_free(chunk);
}
}
/* This routine tries to append the chunk to the offered packet. If adding
* the chunk causes the packet to exceed the path MTU and COOKIE_ECHO chunk
* is not present in the packet, it transmits the input packet.
* Data can be bundled with a packet containing a COOKIE_ECHO chunk as long
* as it can fit in the packet, but any more data that does not fit in this
* packet can be sent only after receiving the COOKIE_ACK.
*/
enum sctp_xmit sctp_packet_transmit_chunk(struct sctp_packet *packet,
struct sctp_chunk *chunk,
int one_packet, gfp_t gfp)
{
enum sctp_xmit retval;
pr_debug("%s: packet:%p size:%zu chunk:%p size:%d\n", __func__,
packet, packet->size, chunk, chunk->skb ? chunk->skb->len : -1);
switch ((retval = (sctp_packet_append_chunk(packet, chunk)))) {
case SCTP_XMIT_PMTU_FULL:
if (!packet->has_cookie_echo) {
int error = 0;
error = sctp_packet_transmit(packet, gfp);
if (error < 0)
chunk->skb->sk->sk_err = -error;
/* If we have an empty packet, then we can NOT ever
* return PMTU_FULL.
*/
if (!one_packet)
retval = sctp_packet_append_chunk(packet,
chunk);
}
break;
case SCTP_XMIT_RWND_FULL:
case SCTP_XMIT_OK:
case SCTP_XMIT_DELAY:
break;
}
return retval;
}
/* Try to bundle a pad chunk into a packet with a heartbeat chunk for PLPMTUTD probe */
static enum sctp_xmit sctp_packet_bundle_pad(struct sctp_packet *pkt, struct sctp_chunk *chunk)
{
struct sctp_transport *t = pkt->transport;
struct sctp_chunk *pad;
int overhead = 0;
if (!chunk->pmtu_probe)
return SCTP_XMIT_OK;
/* calculate the Padding Data size for the pad chunk */
overhead += sizeof(struct sctphdr) + sizeof(struct sctp_chunkhdr);
overhead += sizeof(struct sctp_sender_hb_info) + sizeof(struct sctp_pad_chunk);
pad = sctp_make_pad(t->asoc, t->pl.probe_size - overhead);
if (!pad)
return SCTP_XMIT_DELAY;
list_add_tail(&pad->list, &pkt->chunk_list);
pkt->size += SCTP_PAD4(ntohs(pad->chunk_hdr->length));
chunk->transport = t;
return SCTP_XMIT_OK;
}
/* Try to bundle an auth chunk into the packet. */
static enum sctp_xmit sctp_packet_bundle_auth(struct sctp_packet *pkt,
struct sctp_chunk *chunk)
{
struct sctp_association *asoc = pkt->transport->asoc;
enum sctp_xmit retval = SCTP_XMIT_OK;
struct sctp_chunk *auth;
/* if we don't have an association, we can't do authentication */
if (!asoc)
return retval;
/* See if this is an auth chunk we are bundling or if
* auth is already bundled.
*/
if (chunk->chunk_hdr->type == SCTP_CID_AUTH || pkt->has_auth)
return retval;
/* if the peer did not request this chunk to be authenticated,
* don't do it
*/
if (!chunk->auth)
return retval;
auth = sctp_make_auth(asoc, chunk->shkey->key_id);
if (!auth)
return retval;
auth->shkey = chunk->shkey;
sctp_auth_shkey_hold(auth->shkey);
retval = __sctp_packet_append_chunk(pkt, auth);
if (retval != SCTP_XMIT_OK)
sctp_chunk_free(auth);
return retval;
}
/* Try to bundle a SACK with the packet. */
static enum sctp_xmit sctp_packet_bundle_sack(struct sctp_packet *pkt,
struct sctp_chunk *chunk)
{
enum sctp_xmit retval = SCTP_XMIT_OK;
/* If sending DATA and haven't aleady bundled a SACK, try to
* bundle one in to the packet.
*/
if (sctp_chunk_is_data(chunk) && !pkt->has_sack &&
!pkt->has_cookie_echo) {
struct sctp_association *asoc;
struct timer_list *timer;
asoc = pkt->transport->asoc;
timer = &asoc->timers[SCTP_EVENT_TIMEOUT_SACK];
/* If the SACK timer is running, we have a pending SACK */
if (timer_pending(timer)) {
struct sctp_chunk *sack;
if (pkt->transport->sack_generation !=
pkt->transport->asoc->peer.sack_generation)
return retval;
asoc->a_rwnd = asoc->rwnd;
sack = sctp_make_sack(asoc);
if (sack) {
retval = __sctp_packet_append_chunk(pkt, sack);
if (retval != SCTP_XMIT_OK) {
sctp_chunk_free(sack);
goto out;
}
SCTP_INC_STATS(asoc->base.net,
SCTP_MIB_OUTCTRLCHUNKS);
asoc->stats.octrlchunks++;
asoc->peer.sack_needed = 0;
if (del_timer(timer))
sctp_association_put(asoc);
}
}
}
out:
return retval;
}
/* Append a chunk to the offered packet reporting back any inability to do
* so.
*/
static enum sctp_xmit __sctp_packet_append_chunk(struct sctp_packet *packet,
struct sctp_chunk *chunk)
{
__u16 chunk_len = SCTP_PAD4(ntohs(chunk->chunk_hdr->length));
enum sctp_xmit retval = SCTP_XMIT_OK;
/* Check to see if this chunk will fit into the packet */
retval = sctp_packet_will_fit(packet, chunk, chunk_len);
if (retval != SCTP_XMIT_OK)
goto finish;
/* We believe that this chunk is OK to add to the packet */
switch (chunk->chunk_hdr->type) {
case SCTP_CID_DATA:
case SCTP_CID_I_DATA:
/* Account for the data being in the packet */
sctp_packet_append_data(packet, chunk);
/* Disallow SACK bundling after DATA. */
packet->has_sack = 1;
/* Disallow AUTH bundling after DATA */
packet->has_auth = 1;
/* Let it be knows that packet has DATA in it */
packet->has_data = 1;
/* timestamp the chunk for rtx purposes */
chunk->sent_at = jiffies;
/* Mainly used for prsctp RTX policy */
chunk->sent_count++;
break;
case SCTP_CID_COOKIE_ECHO:
packet->has_cookie_echo = 1;
break;
case SCTP_CID_SACK:
packet->has_sack = 1;
if (chunk->asoc)
chunk->asoc->stats.osacks++;
break;
case SCTP_CID_AUTH:
packet->has_auth = 1;
packet->auth = chunk;
break;
}
/* It is OK to send this chunk. */
list_add_tail(&chunk->list, &packet->chunk_list);
packet->size += chunk_len;
chunk->transport = packet->transport;
finish:
return retval;
}
/* Append a chunk to the offered packet reporting back any inability to do
* so.
*/
enum sctp_xmit sctp_packet_append_chunk(struct sctp_packet *packet,
struct sctp_chunk *chunk)
{
enum sctp_xmit retval = SCTP_XMIT_OK;
pr_debug("%s: packet:%p chunk:%p\n", __func__, packet, chunk);
/* Data chunks are special. Before seeing what else we can
* bundle into this packet, check to see if we are allowed to
* send this DATA.
*/
if (sctp_chunk_is_data(chunk)) {
retval = sctp_packet_can_append_data(packet, chunk);
if (retval != SCTP_XMIT_OK)
goto finish;
}
/* Try to bundle AUTH chunk */
retval = sctp_packet_bundle_auth(packet, chunk);
if (retval != SCTP_XMIT_OK)
goto finish;
/* Try to bundle SACK chunk */
retval = sctp_packet_bundle_sack(packet, chunk);
if (retval != SCTP_XMIT_OK)
goto finish;
retval = __sctp_packet_append_chunk(packet, chunk);
if (retval != SCTP_XMIT_OK)
goto finish;
retval = sctp_packet_bundle_pad(packet, chunk);
finish:
return retval;
}
static void sctp_packet_gso_append(struct sk_buff *head, struct sk_buff *skb)
{
if (SCTP_OUTPUT_CB(head)->last == head)
skb_shinfo(head)->frag_list = skb;
else
SCTP_OUTPUT_CB(head)->last->next = skb;
SCTP_OUTPUT_CB(head)->last = skb;
head->truesize += skb->truesize;
head->data_len += skb->len;
head->len += skb->len;
refcount_add(skb->truesize, &head->sk->sk_wmem_alloc);
__skb_header_release(skb);
}
static int sctp_packet_pack(struct sctp_packet *packet,
struct sk_buff *head, int gso, gfp_t gfp)
{
struct sctp_transport *tp = packet->transport;
struct sctp_auth_chunk *auth = NULL;
struct sctp_chunk *chunk, *tmp;
int pkt_count = 0, pkt_size;
struct sock *sk = head->sk;
struct sk_buff *nskb;
int auth_len = 0;
if (gso) {
skb_shinfo(head)->gso_type = sk->sk_gso_type;
SCTP_OUTPUT_CB(head)->last = head;
} else {
nskb = head;
pkt_size = packet->size;
goto merge;
}
do {
/* calculate the pkt_size and alloc nskb */
pkt_size = packet->overhead;
list_for_each_entry_safe(chunk, tmp, &packet->chunk_list,
list) {
int padded = SCTP_PAD4(chunk->skb->len);
if (chunk == packet->auth)
auth_len = padded;
else if (auth_len + padded + packet->overhead >
tp->pathmtu)
return 0;
else if (pkt_size + padded > tp->pathmtu)
break;
pkt_size += padded;
}
nskb = alloc_skb(pkt_size + MAX_HEADER, gfp);
if (!nskb)
return 0;
skb_reserve(nskb, packet->overhead + MAX_HEADER);
merge:
/* merge chunks into nskb and append nskb into head list */
pkt_size -= packet->overhead;
list_for_each_entry_safe(chunk, tmp, &packet->chunk_list, list) {
int padding;
list_del_init(&chunk->list);
if (sctp_chunk_is_data(chunk)) {
if (!sctp_chunk_retransmitted(chunk) &&
!tp->rto_pending) {
chunk->rtt_in_progress = 1;
tp->rto_pending = 1;
}
}
padding = SCTP_PAD4(chunk->skb->len) - chunk->skb->len;
if (padding)
skb_put_zero(chunk->skb, padding);
if (chunk == packet->auth)
auth = (struct sctp_auth_chunk *)
skb_tail_pointer(nskb);
skb_put_data(nskb, chunk->skb->data, chunk->skb->len);
pr_debug("*** Chunk:%p[%s] %s 0x%x, length:%d, chunk->skb->len:%d, rtt_in_progress:%d\n",
chunk,
sctp_cname(SCTP_ST_CHUNK(chunk->chunk_hdr->type)),
chunk->has_tsn ? "TSN" : "No TSN",
chunk->has_tsn ? ntohl(chunk->subh.data_hdr->tsn) : 0,
ntohs(chunk->chunk_hdr->length), chunk->skb->len,
chunk->rtt_in_progress);
pkt_size -= SCTP_PAD4(chunk->skb->len);
if (!sctp_chunk_is_data(chunk) && chunk != packet->auth)
sctp_chunk_free(chunk);
if (!pkt_size)
break;
}
if (auth) {
sctp_auth_calculate_hmac(tp->asoc, nskb, auth,
packet->auth->shkey, gfp);
/* free auth if no more chunks, or add it back */
if (list_empty(&packet->chunk_list))
sctp_chunk_free(packet->auth);
else
list_add(&packet->auth->list,
&packet->chunk_list);
}
if (gso)
sctp_packet_gso_append(head, nskb);
pkt_count++;
} while (!list_empty(&packet->chunk_list));
if (gso) {
memset(head->cb, 0, max(sizeof(struct inet_skb_parm),
sizeof(struct inet6_skb_parm)));
skb_shinfo(head)->gso_segs = pkt_count;
skb_shinfo(head)->gso_size = GSO_BY_FRAGS;
goto chksum;
}
if (sctp_checksum_disable)
return 1;
if (!(tp->dst->dev->features & NETIF_F_SCTP_CRC) ||
dst_xfrm(tp->dst) || packet->ipfragok || tp->encap_port) {
struct sctphdr *sh =
(struct sctphdr *)skb_transport_header(head);
sh->checksum = sctp_compute_cksum(head, 0);
} else {
chksum:
head->ip_summed = CHECKSUM_PARTIAL;
head->csum_not_inet = 1;
head->csum_start = skb_transport_header(head) - head->head;
head->csum_offset = offsetof(struct sctphdr, checksum);
}
return pkt_count;
}
/* All packets are sent to the network through this function from
* sctp_outq_tail().
*
* The return value is always 0 for now.
*/
int sctp_packet_transmit(struct sctp_packet *packet, gfp_t gfp)
{
struct sctp_transport *tp = packet->transport;
struct sctp_association *asoc = tp->asoc;
struct sctp_chunk *chunk, *tmp;
int pkt_count, gso = 0;
struct sk_buff *head;
struct sctphdr *sh;
struct sock *sk;
pr_debug("%s: packet:%p\n", __func__, packet);
if (list_empty(&packet->chunk_list))
return 0;
chunk = list_entry(packet->chunk_list.next, struct sctp_chunk, list);
sk = chunk->skb->sk;
if (packet->size > tp->pathmtu && !packet->ipfragok && !chunk->pmtu_probe) {
if (tp->pl.state == SCTP_PL_ERROR) { /* do IP fragmentation if in Error state */
packet->ipfragok = 1;
} else {
if (!sk_can_gso(sk)) { /* check gso */
pr_err_once("Trying to GSO but underlying device doesn't support it.");
goto out;
}
gso = 1;
}
}
/* alloc head skb */
head = alloc_skb((gso ? packet->overhead : packet->size) +
MAX_HEADER, gfp);
if (!head)
goto out;
skb_reserve(head, packet->overhead + MAX_HEADER);
skb_set_owner_w(head, sk);
/* set sctp header */
sh = skb_push(head, sizeof(struct sctphdr));
skb_reset_transport_header(head);
sh->source = htons(packet->source_port);
sh->dest = htons(packet->destination_port);
sh->vtag = htonl(packet->vtag);
sh->checksum = 0;
/* drop packet if no dst */
if (!tp->dst) {
IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTNOROUTES);
kfree_skb(head);
goto out;
}
/* pack up chunks */
pkt_count = sctp_packet_pack(packet, head, gso, gfp);
if (!pkt_count) {
kfree_skb(head);
goto out;
}
pr_debug("***sctp_transmit_packet*** skb->len:%d\n", head->len);
/* start autoclose timer */
if (packet->has_data && sctp_state(asoc, ESTABLISHED) &&
asoc->timeouts[SCTP_EVENT_TIMEOUT_AUTOCLOSE]) {
struct timer_list *timer =
&asoc->timers[SCTP_EVENT_TIMEOUT_AUTOCLOSE];
unsigned long timeout =
asoc->timeouts[SCTP_EVENT_TIMEOUT_AUTOCLOSE];
if (!mod_timer(timer, jiffies + timeout))
sctp_association_hold(asoc);
}
/* sctp xmit */
tp->af_specific->ecn_capable(sk);
if (asoc) {
asoc->stats.opackets += pkt_count;
if (asoc->peer.last_sent_to != tp)
asoc->peer.last_sent_to = tp;
}
head->ignore_df = packet->ipfragok;
if (tp->dst_pending_confirm)
skb_set_dst_pending_confirm(head, 1);
/* neighbour should be confirmed on successful transmission or
* positive error
*/
if (tp->af_specific->sctp_xmit(head, tp) >= 0 &&
tp->dst_pending_confirm)
tp->dst_pending_confirm = 0;
out:
list_for_each_entry_safe(chunk, tmp, &packet->chunk_list, list) {
list_del_init(&chunk->list);
if (!sctp_chunk_is_data(chunk))
sctp_chunk_free(chunk);
}
sctp_packet_reset(packet);
return 0;
}
/********************************************************************
* 2nd Level Abstractions
********************************************************************/
/* This private function check to see if a chunk can be added */
static enum sctp_xmit sctp_packet_can_append_data(struct sctp_packet *packet,
struct sctp_chunk *chunk)
{
size_t datasize, rwnd, inflight, flight_size;
struct sctp_transport *transport = packet->transport;
struct sctp_association *asoc = transport->asoc;
struct sctp_outq *q = &asoc->outqueue;
/* RFC 2960 6.1 Transmission of DATA Chunks
*
* A) At any given time, the data sender MUST NOT transmit new data to
* any destination transport address if its peer's rwnd indicates
* that the peer has no buffer space (i.e. rwnd is 0, see Section
* 6.2.1). However, regardless of the value of rwnd (including if it
* is 0), the data sender can always have one DATA chunk in flight to
* the receiver if allowed by cwnd (see rule B below). This rule
* allows the sender to probe for a change in rwnd that the sender
* missed due to the SACK having been lost in transit from the data
* receiver to the data sender.
*/
rwnd = asoc->peer.rwnd;
inflight = q->outstanding_bytes;
flight_size = transport->flight_size;
datasize = sctp_data_size(chunk);
if (datasize > rwnd && inflight > 0)
/* We have (at least) one data chunk in flight,
* so we can't fall back to rule 6.1 B).
*/
return SCTP_XMIT_RWND_FULL;
/* RFC 2960 6.1 Transmission of DATA Chunks
*
* B) At any given time, the sender MUST NOT transmit new data
* to a given transport address if it has cwnd or more bytes
* of data outstanding to that transport address.
*/
/* RFC 7.2.4 & the Implementers Guide 2.8.
*
* 3) ...
* When a Fast Retransmit is being performed the sender SHOULD
* ignore the value of cwnd and SHOULD NOT delay retransmission.
*/
if (chunk->fast_retransmit != SCTP_NEED_FRTX &&
flight_size >= transport->cwnd)
return SCTP_XMIT_RWND_FULL;
/* Nagle's algorithm to solve small-packet problem:
* Inhibit the sending of new chunks when new outgoing data arrives
* if any previously transmitted data on the connection remains
* unacknowledged.
*/
if ((sctp_sk(asoc->base.sk)->nodelay || inflight == 0) &&
!asoc->force_delay)
/* Nothing unacked */
return SCTP_XMIT_OK;
if (!sctp_packet_empty(packet))
/* Append to packet */
return SCTP_XMIT_OK;
if (!sctp_state(asoc, ESTABLISHED))
return SCTP_XMIT_OK;
/* Check whether this chunk and all the rest of pending data will fit
* or delay in hopes of bundling a full sized packet.
*/
if (chunk->skb->len + q->out_qlen > transport->pathmtu -
packet->overhead - sctp_datachk_len(&chunk->asoc->stream) - 4)
/* Enough data queued to fill a packet */
return SCTP_XMIT_OK;
/* Don't delay large message writes that may have been fragmented */
if (!chunk->msg->can_delay)
return SCTP_XMIT_OK;
/* Defer until all data acked or packet full */
return SCTP_XMIT_DELAY;
}
/* This private function does management things when adding DATA chunk */
static void sctp_packet_append_data(struct sctp_packet *packet,
struct sctp_chunk *chunk)
{
struct sctp_transport *transport = packet->transport;
size_t datasize = sctp_data_size(chunk);
struct sctp_association *asoc = transport->asoc;
u32 rwnd = asoc->peer.rwnd;
/* Keep track of how many bytes are in flight over this transport. */
transport->flight_size += datasize;
/* Keep track of how many bytes are in flight to the receiver. */
asoc->outqueue.outstanding_bytes += datasize;
/* Update our view of the receiver's rwnd. */
if (datasize < rwnd)
rwnd -= datasize;
else
rwnd = 0;
asoc->peer.rwnd = rwnd;
sctp_chunk_assign_tsn(chunk);
asoc->stream.si->assign_number(chunk);
}
static enum sctp_xmit sctp_packet_will_fit(struct sctp_packet *packet,
struct sctp_chunk *chunk,
u16 chunk_len)
{
enum sctp_xmit retval = SCTP_XMIT_OK;
size_t psize, pmtu, maxsize;
/* Don't bundle in this packet if this chunk's auth key doesn't
* match other chunks already enqueued on this packet. Also,
* don't bundle the chunk with auth key if other chunks in this
* packet don't have auth key.
*/
if ((packet->auth && chunk->shkey != packet->auth->shkey) ||
(!packet->auth && chunk->shkey &&
chunk->chunk_hdr->type != SCTP_CID_AUTH))
return SCTP_XMIT_PMTU_FULL;
psize = packet->size;
if (packet->transport->asoc)
pmtu = packet->transport->asoc->pathmtu;
else
pmtu = packet->transport->pathmtu;
/* Decide if we need to fragment or resubmit later. */
if (psize + chunk_len > pmtu) {
/* It's OK to fragment at IP level if any one of the following
* is true:
* 1. The packet is empty (meaning this chunk is greater
* the MTU)
* 2. The packet doesn't have any data in it yet and data
* requires authentication.
*/
if (sctp_packet_empty(packet) ||
(!packet->has_data && chunk->auth)) {
/* We no longer do re-fragmentation.
* Just fragment at the IP layer, if we
* actually hit this condition
*/
packet->ipfragok = 1;
goto out;
}
/* Similarly, if this chunk was built before a PMTU
* reduction, we have to fragment it at IP level now. So
* if the packet already contains something, we need to
* flush.
*/
maxsize = pmtu - packet->overhead;
if (packet->auth)
maxsize -= SCTP_PAD4(packet->auth->skb->len);
if (chunk_len > maxsize)
retval = SCTP_XMIT_PMTU_FULL;
/* It is also okay to fragment if the chunk we are
* adding is a control chunk, but only if current packet
* is not a GSO one otherwise it causes fragmentation of
* a large frame. So in this case we allow the
* fragmentation by forcing it to be in a new packet.
*/
if (!sctp_chunk_is_data(chunk) && packet->has_data)
retval = SCTP_XMIT_PMTU_FULL;
if (psize + chunk_len > packet->max_size)
/* Hit GSO/PMTU limit, gotta flush */
retval = SCTP_XMIT_PMTU_FULL;
if (!packet->transport->burst_limited &&
psize + chunk_len > (packet->transport->cwnd >> 1))
/* Do not allow a single GSO packet to use more
* than half of cwnd.
*/
retval = SCTP_XMIT_PMTU_FULL;
if (packet->transport->burst_limited &&
psize + chunk_len > (packet->transport->burst_limited >> 1))
/* Do not allow a single GSO packet to use more
* than half of original cwnd.
*/
retval = SCTP_XMIT_PMTU_FULL;
/* Otherwise it will fit in the GSO packet */
}
out:
return retval;
}