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![Xin Long](/assets/img/avatar_default.png)
This patch does what the rfc6951#section-5.3 says for ipv4: "Within the UDP header, the source port MUST be the local UDP encapsulation port number of the SCTP stack, and the destination port MUST be the remote UDP encapsulation port number maintained for the association and the destination address to which the packet is sent (see Section 5.1). Because the SCTP packet is the UDP payload, the length of the UDP packet MUST be the length of the SCTP packet plus the size of the UDP header. The SCTP checksum MUST be computed for IPv4 and IPv6, and the UDP checksum SHOULD be computed for IPv4 and IPv6." Some places need to be adjusted in sctp_packet_transmit(): 1. For non-gso packets, when transport's encap_port is set, sctp checksum has to be done in sctp_packet_pack(), as the outer udp will use ip_summed = CHECKSUM_PARTIAL to do the offload setting for checksum. 2. Delay calling dst_clone() and skb_dst_set() for non-udp packets until sctp_v4_xmit(), as for udp packets, skb_dst_set() is not needed before calling udp_tunnel_xmit_skb(). then in sctp_v4_xmit(): 1. Go to udp_tunnel_xmit_skb() only when transport->encap_port and net->sctp.udp_port both are set, as these are one for dst port and another for src port. 2. For gso packet, SKB_GSO_UDP_TUNNEL_CSUM is set for gso_type, and with this udp checksum can be done in __skb_udp_tunnel_segment() for each segments after the sctp gso. 3. inner_mac_header and inner_transport_header are set, as these will be needed in __skb_udp_tunnel_segment() to find the right headers. 4. df and ttl are calculated, as these are the required params by udp_tunnel_xmit_skb(). 5. nocheck param has to be false, as "the UDP checksum SHOULD be computed for IPv4 and IPv6", says in rfc6951#section-5.3. v1->v2: - Use sp->udp_port instead in sctp_v4_xmit(), which is more safe. Signed-off-by: Xin Long <lucien.xin@gmail.com> Acked-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
839 lines
23 KiB
C
839 lines
23 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/* SCTP kernel implementation
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* (C) Copyright IBM Corp. 2001, 2004
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* Copyright (c) 1999-2000 Cisco, Inc.
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* Copyright (c) 1999-2001 Motorola, Inc.
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*
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* This file is part of the SCTP kernel implementation
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*
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* These functions handle output processing.
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*
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* Please send any bug reports or fixes you make to the
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* email address(es):
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* lksctp developers <linux-sctp@vger.kernel.org>
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*
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* Written or modified by:
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* La Monte H.P. Yarroll <piggy@acm.org>
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* Karl Knutson <karl@athena.chicago.il.us>
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* Jon Grimm <jgrimm@austin.ibm.com>
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* Sridhar Samudrala <sri@us.ibm.com>
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/types.h>
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#include <linux/kernel.h>
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#include <linux/wait.h>
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#include <linux/time.h>
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#include <linux/ip.h>
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#include <linux/ipv6.h>
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#include <linux/init.h>
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#include <linux/slab.h>
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#include <net/inet_ecn.h>
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#include <net/ip.h>
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#include <net/icmp.h>
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#include <net/net_namespace.h>
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#include <linux/socket.h> /* for sa_family_t */
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#include <net/sock.h>
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#include <net/sctp/sctp.h>
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#include <net/sctp/sm.h>
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#include <net/sctp/checksum.h>
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/* Forward declarations for private helpers. */
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static enum sctp_xmit __sctp_packet_append_chunk(struct sctp_packet *packet,
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struct sctp_chunk *chunk);
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static enum sctp_xmit sctp_packet_can_append_data(struct sctp_packet *packet,
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struct sctp_chunk *chunk);
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static void sctp_packet_append_data(struct sctp_packet *packet,
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struct sctp_chunk *chunk);
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static enum sctp_xmit sctp_packet_will_fit(struct sctp_packet *packet,
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struct sctp_chunk *chunk,
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u16 chunk_len);
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static void sctp_packet_reset(struct sctp_packet *packet)
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{
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/* sctp_packet_transmit() relies on this to reset size to the
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* current overhead after sending packets.
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*/
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packet->size = packet->overhead;
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packet->has_cookie_echo = 0;
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packet->has_sack = 0;
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packet->has_data = 0;
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packet->has_auth = 0;
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packet->ipfragok = 0;
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packet->auth = NULL;
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}
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/* Config a packet.
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* This appears to be a followup set of initializations.
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*/
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void sctp_packet_config(struct sctp_packet *packet, __u32 vtag,
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int ecn_capable)
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{
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struct sctp_transport *tp = packet->transport;
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struct sctp_association *asoc = tp->asoc;
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struct sctp_sock *sp = NULL;
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struct sock *sk;
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pr_debug("%s: packet:%p vtag:0x%x\n", __func__, packet, vtag);
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packet->vtag = vtag;
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/* do the following jobs only once for a flush schedule */
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if (!sctp_packet_empty(packet))
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return;
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/* set packet max_size with pathmtu, then calculate overhead */
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packet->max_size = tp->pathmtu;
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if (asoc) {
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sk = asoc->base.sk;
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sp = sctp_sk(sk);
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}
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packet->overhead = sctp_mtu_payload(sp, 0, 0);
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packet->size = packet->overhead;
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if (!asoc)
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return;
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/* update dst or transport pathmtu if in need */
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if (!sctp_transport_dst_check(tp)) {
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sctp_transport_route(tp, NULL, sp);
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if (asoc->param_flags & SPP_PMTUD_ENABLE)
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sctp_assoc_sync_pmtu(asoc);
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} else if (!sctp_transport_pmtu_check(tp)) {
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if (asoc->param_flags & SPP_PMTUD_ENABLE)
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sctp_assoc_sync_pmtu(asoc);
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}
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if (asoc->pmtu_pending) {
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if (asoc->param_flags & SPP_PMTUD_ENABLE)
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sctp_assoc_sync_pmtu(asoc);
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asoc->pmtu_pending = 0;
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}
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/* If there a is a prepend chunk stick it on the list before
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* any other chunks get appended.
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*/
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if (ecn_capable) {
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struct sctp_chunk *chunk = sctp_get_ecne_prepend(asoc);
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if (chunk)
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sctp_packet_append_chunk(packet, chunk);
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}
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if (!tp->dst)
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return;
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/* set packet max_size with gso_max_size if gso is enabled*/
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rcu_read_lock();
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if (__sk_dst_get(sk) != tp->dst) {
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dst_hold(tp->dst);
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sk_setup_caps(sk, tp->dst);
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}
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packet->max_size = sk_can_gso(sk) ? tp->dst->dev->gso_max_size
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: asoc->pathmtu;
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rcu_read_unlock();
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}
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/* Initialize the packet structure. */
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void sctp_packet_init(struct sctp_packet *packet,
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struct sctp_transport *transport,
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__u16 sport, __u16 dport)
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{
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pr_debug("%s: packet:%p transport:%p\n", __func__, packet, transport);
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packet->transport = transport;
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packet->source_port = sport;
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packet->destination_port = dport;
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INIT_LIST_HEAD(&packet->chunk_list);
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/* The overhead will be calculated by sctp_packet_config() */
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packet->overhead = 0;
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sctp_packet_reset(packet);
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packet->vtag = 0;
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}
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/* Free a packet. */
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void sctp_packet_free(struct sctp_packet *packet)
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{
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struct sctp_chunk *chunk, *tmp;
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pr_debug("%s: packet:%p\n", __func__, packet);
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list_for_each_entry_safe(chunk, tmp, &packet->chunk_list, list) {
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list_del_init(&chunk->list);
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sctp_chunk_free(chunk);
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}
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}
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/* This routine tries to append the chunk to the offered packet. If adding
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* the chunk causes the packet to exceed the path MTU and COOKIE_ECHO chunk
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* is not present in the packet, it transmits the input packet.
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* Data can be bundled with a packet containing a COOKIE_ECHO chunk as long
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* as it can fit in the packet, but any more data that does not fit in this
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* packet can be sent only after receiving the COOKIE_ACK.
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*/
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enum sctp_xmit sctp_packet_transmit_chunk(struct sctp_packet *packet,
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struct sctp_chunk *chunk,
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int one_packet, gfp_t gfp)
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{
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enum sctp_xmit retval;
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pr_debug("%s: packet:%p size:%zu chunk:%p size:%d\n", __func__,
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packet, packet->size, chunk, chunk->skb ? chunk->skb->len : -1);
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switch ((retval = (sctp_packet_append_chunk(packet, chunk)))) {
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case SCTP_XMIT_PMTU_FULL:
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if (!packet->has_cookie_echo) {
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int error = 0;
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error = sctp_packet_transmit(packet, gfp);
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if (error < 0)
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chunk->skb->sk->sk_err = -error;
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/* If we have an empty packet, then we can NOT ever
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* return PMTU_FULL.
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*/
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if (!one_packet)
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retval = sctp_packet_append_chunk(packet,
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chunk);
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}
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break;
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case SCTP_XMIT_RWND_FULL:
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case SCTP_XMIT_OK:
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case SCTP_XMIT_DELAY:
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break;
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}
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return retval;
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}
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/* Try to bundle an auth chunk into the packet. */
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static enum sctp_xmit sctp_packet_bundle_auth(struct sctp_packet *pkt,
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struct sctp_chunk *chunk)
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{
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struct sctp_association *asoc = pkt->transport->asoc;
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enum sctp_xmit retval = SCTP_XMIT_OK;
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struct sctp_chunk *auth;
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/* if we don't have an association, we can't do authentication */
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if (!asoc)
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return retval;
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/* See if this is an auth chunk we are bundling or if
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* auth is already bundled.
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*/
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if (chunk->chunk_hdr->type == SCTP_CID_AUTH || pkt->has_auth)
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return retval;
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/* if the peer did not request this chunk to be authenticated,
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* don't do it
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*/
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if (!chunk->auth)
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return retval;
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auth = sctp_make_auth(asoc, chunk->shkey->key_id);
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if (!auth)
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return retval;
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auth->shkey = chunk->shkey;
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sctp_auth_shkey_hold(auth->shkey);
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retval = __sctp_packet_append_chunk(pkt, auth);
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if (retval != SCTP_XMIT_OK)
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sctp_chunk_free(auth);
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return retval;
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}
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/* Try to bundle a SACK with the packet. */
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static enum sctp_xmit sctp_packet_bundle_sack(struct sctp_packet *pkt,
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struct sctp_chunk *chunk)
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{
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enum sctp_xmit retval = SCTP_XMIT_OK;
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/* If sending DATA and haven't aleady bundled a SACK, try to
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* bundle one in to the packet.
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*/
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if (sctp_chunk_is_data(chunk) && !pkt->has_sack &&
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!pkt->has_cookie_echo) {
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struct sctp_association *asoc;
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struct timer_list *timer;
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asoc = pkt->transport->asoc;
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timer = &asoc->timers[SCTP_EVENT_TIMEOUT_SACK];
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/* If the SACK timer is running, we have a pending SACK */
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if (timer_pending(timer)) {
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struct sctp_chunk *sack;
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if (pkt->transport->sack_generation !=
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pkt->transport->asoc->peer.sack_generation)
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return retval;
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asoc->a_rwnd = asoc->rwnd;
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sack = sctp_make_sack(asoc);
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if (sack) {
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retval = __sctp_packet_append_chunk(pkt, sack);
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if (retval != SCTP_XMIT_OK) {
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sctp_chunk_free(sack);
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goto out;
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}
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SCTP_INC_STATS(asoc->base.net,
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SCTP_MIB_OUTCTRLCHUNKS);
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asoc->stats.octrlchunks++;
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asoc->peer.sack_needed = 0;
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if (del_timer(timer))
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sctp_association_put(asoc);
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}
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}
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}
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out:
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return retval;
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}
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/* Append a chunk to the offered packet reporting back any inability to do
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* so.
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*/
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static enum sctp_xmit __sctp_packet_append_chunk(struct sctp_packet *packet,
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struct sctp_chunk *chunk)
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{
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__u16 chunk_len = SCTP_PAD4(ntohs(chunk->chunk_hdr->length));
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enum sctp_xmit retval = SCTP_XMIT_OK;
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/* Check to see if this chunk will fit into the packet */
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retval = sctp_packet_will_fit(packet, chunk, chunk_len);
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if (retval != SCTP_XMIT_OK)
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goto finish;
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/* We believe that this chunk is OK to add to the packet */
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switch (chunk->chunk_hdr->type) {
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case SCTP_CID_DATA:
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case SCTP_CID_I_DATA:
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/* Account for the data being in the packet */
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sctp_packet_append_data(packet, chunk);
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/* Disallow SACK bundling after DATA. */
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packet->has_sack = 1;
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/* Disallow AUTH bundling after DATA */
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packet->has_auth = 1;
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/* Let it be knows that packet has DATA in it */
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packet->has_data = 1;
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/* timestamp the chunk for rtx purposes */
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chunk->sent_at = jiffies;
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/* Mainly used for prsctp RTX policy */
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chunk->sent_count++;
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break;
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case SCTP_CID_COOKIE_ECHO:
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packet->has_cookie_echo = 1;
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break;
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case SCTP_CID_SACK:
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packet->has_sack = 1;
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if (chunk->asoc)
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chunk->asoc->stats.osacks++;
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break;
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case SCTP_CID_AUTH:
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packet->has_auth = 1;
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packet->auth = chunk;
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break;
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}
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/* It is OK to send this chunk. */
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list_add_tail(&chunk->list, &packet->chunk_list);
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packet->size += chunk_len;
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chunk->transport = packet->transport;
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finish:
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return retval;
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}
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/* Append a chunk to the offered packet reporting back any inability to do
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* so.
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*/
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enum sctp_xmit sctp_packet_append_chunk(struct sctp_packet *packet,
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struct sctp_chunk *chunk)
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{
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enum sctp_xmit retval = SCTP_XMIT_OK;
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pr_debug("%s: packet:%p chunk:%p\n", __func__, packet, chunk);
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/* Data chunks are special. Before seeing what else we can
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* bundle into this packet, check to see if we are allowed to
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* send this DATA.
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*/
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if (sctp_chunk_is_data(chunk)) {
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retval = sctp_packet_can_append_data(packet, chunk);
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if (retval != SCTP_XMIT_OK)
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goto finish;
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}
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/* Try to bundle AUTH chunk */
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retval = sctp_packet_bundle_auth(packet, chunk);
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if (retval != SCTP_XMIT_OK)
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goto finish;
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/* Try to bundle SACK chunk */
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retval = sctp_packet_bundle_sack(packet, chunk);
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if (retval != SCTP_XMIT_OK)
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goto finish;
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retval = __sctp_packet_append_chunk(packet, chunk);
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finish:
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return retval;
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}
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static void sctp_packet_gso_append(struct sk_buff *head, struct sk_buff *skb)
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{
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if (SCTP_OUTPUT_CB(head)->last == head)
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skb_shinfo(head)->frag_list = skb;
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else
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SCTP_OUTPUT_CB(head)->last->next = skb;
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SCTP_OUTPUT_CB(head)->last = skb;
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head->truesize += skb->truesize;
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head->data_len += skb->len;
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head->len += skb->len;
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refcount_add(skb->truesize, &head->sk->sk_wmem_alloc);
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__skb_header_release(skb);
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}
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static int sctp_packet_pack(struct sctp_packet *packet,
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struct sk_buff *head, int gso, gfp_t gfp)
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{
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struct sctp_transport *tp = packet->transport;
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struct sctp_auth_chunk *auth = NULL;
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struct sctp_chunk *chunk, *tmp;
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int pkt_count = 0, pkt_size;
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struct sock *sk = head->sk;
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struct sk_buff *nskb;
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int auth_len = 0;
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if (gso) {
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skb_shinfo(head)->gso_type = sk->sk_gso_type;
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SCTP_OUTPUT_CB(head)->last = head;
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} else {
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nskb = head;
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pkt_size = packet->size;
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goto merge;
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}
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do {
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/* calculate the pkt_size and alloc nskb */
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pkt_size = packet->overhead;
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list_for_each_entry_safe(chunk, tmp, &packet->chunk_list,
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list) {
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int padded = SCTP_PAD4(chunk->skb->len);
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|
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if (chunk == packet->auth)
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auth_len = padded;
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else if (auth_len + padded + packet->overhead >
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tp->pathmtu)
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return 0;
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else if (pkt_size + padded > tp->pathmtu)
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break;
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pkt_size += padded;
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}
|
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nskb = alloc_skb(pkt_size + MAX_HEADER, gfp);
|
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if (!nskb)
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return 0;
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skb_reserve(nskb, packet->overhead + MAX_HEADER);
|
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|
|
merge:
|
|
/* merge chunks into nskb and append nskb into head list */
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pkt_size -= packet->overhead;
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list_for_each_entry_safe(chunk, tmp, &packet->chunk_list, list) {
|
|
int padding;
|
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|
|
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;
|
|
|
|
/* check gso */
|
|
if (packet->size > tp->pathmtu && !packet->ipfragok) {
|
|
if (!sk_can_gso(sk)) {
|
|
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;
|
|
}
|
|
|
|
rcu_read_lock();
|
|
if (__sk_dst_get(sk) != tp->dst) {
|
|
dst_hold(tp->dst);
|
|
sk_setup_caps(sk, tp->dst);
|
|
}
|
|
rcu_read_unlock();
|
|
|
|
/* 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;
|
|
}
|