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sctp: clean up sctp_packet_transmit 

After adding sctp gso, sctp_packet_transmit is a quite big function now.

This patch is to extract the codes for packing packet to sctp_packet_pack
from sctp_packet_transmit, and add some comments, simplify the err path by
freeing auth chunk when freeing packet chunk_list in out path and freeing
head skb early if it fails to pack packet.

Signed-off-by: Xin Long <lucien.xin@gmail.com>
Acked-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Xin Long 2016-11-01 00:49:41 +08:00 committed by David S. Miller
parent 9290182753
commit e4ff952a7e
1 changed files with 165 additions and 284 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

449
net/sctp/output.c
View File

@ -399,187 +399,72 @@ static void sctp_packet_set_owner_w(struct sk_buff *skb, struct sock *sk)
atomic_inc(&sk->sk_wmem_alloc);
}
/* All packets are sent to the network through this function from
* sctp_outq_tail().
*
* The return value is a normal kernel error return value.
*/
int sctp_packet_transmit(struct sctp_packet *packet, gfp_t gfp)
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_association *asoc = tp->asoc;
struct sctphdr *sh;
struct sk_buff *nskb = NULL, *head = NULL;
struct sctp_auth_chunk *auth = NULL;
struct sctp_chunk *chunk, *tmp;
struct sock *sk;
int err = 0;
int padding; /* How much padding do we need? */
int pkt_size;
__u8 has_data = 0;
int gso = 0;
int pktcount = 0;
int pkt_count = 0, pkt_size;
struct sock *sk = head->sk;
struct sk_buff *nskb;
int auth_len = 0;
struct dst_entry *dst;
unsigned char *auth = NULL; /* pointer to auth in skb data */
pr_debug("%s: packet:%p\n", __func__, packet);
/* Do NOT generate a chunkless packet. */
if (list_empty(&packet->chunk_list))
return err;
/* Set up convenience variables... */
chunk = list_entry(packet->chunk_list.next, struct sctp_chunk, list);
sk = chunk->skb->sk;
/* Allocate the head skb, or main one if not in GSO */
if (packet->size > tp->pathmtu && !packet->ipfragok) {
if (sk_can_gso(sk)) {
gso = 1;
pkt_size = packet->overhead;
} else {
/* If this happens, we trash this packet and try
* to build a new one, hopefully correct this
* time. Application may notice this error.
*/
pr_err_once("Trying to GSO but underlying device doesn't support it.");
goto err;
}
} else {
pkt_size = packet->size;
}
head = alloc_skb(pkt_size + MAX_HEADER, gfp);
if (!head)
goto err;
if (gso) {
NAPI_GRO_CB(head)->last = head;
skb_shinfo(head)->gso_type = sk->sk_gso_type;
NAPI_GRO_CB(head)->last = head;
} else {
nskb = head;
pkt_size = packet->size;
goto merge;
}
/* Make sure the outbound skb has enough header room reserved. */
skb_reserve(head, packet->overhead + MAX_HEADER);
/* Set the owning socket so that we know where to get the
* destination IP address.
*/
sctp_packet_set_owner_w(head, sk);
if (!sctp_transport_dst_check(tp)) {
sctp_transport_route(tp, NULL, sctp_sk(sk));
if (asoc && (asoc->param_flags & SPP_PMTUD_ENABLE)) {
sctp_assoc_sync_pmtu(sk, asoc);
}
}
dst = dst_clone(tp->dst);
if (!dst) {
if (asoc)
IP_INC_STATS(sock_net(asoc->base.sk),
IPSTATS_MIB_OUTNOROUTES);
goto nodst;
}
skb_dst_set(head, dst);
/* Build the SCTP header. */
sh = (struct sctphdr *)skb_push(head, sizeof(struct sctphdr));
skb_reset_transport_header(head);
sh->source = htons(packet->source_port);
sh->dest = htons(packet->destination_port);
/* From 6.8 Adler-32 Checksum Calculation:
* After the packet is constructed (containing the SCTP common
* header and one or more control or DATA chunks), the
* transmitter shall:
*
* 1) Fill in the proper Verification Tag in the SCTP common
* header and initialize the checksum field to 0's.
*/
sh->vtag = htonl(packet->vtag);
sh->checksum = 0;
pr_debug("***sctp_transmit_packet***\n");
do {
/* Set up convenience variables... */
chunk = list_entry(packet->chunk_list.next, struct sctp_chunk, list);
pktcount++;
/* 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);
/* Calculate packet size, so it fits in PMTU. Leave
* other chunks for the next packets.
*/
if (gso) {
pkt_size = packet->overhead;
list_for_each_entry(chunk, &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)
goto nomem;
else if (pkt_size + padded > tp->pathmtu)
break;
pkt_size += padded;
}
/* Allocate a new skb. */
nskb = alloc_skb(pkt_size + MAX_HEADER, gfp);
if (!nskb)
goto nomem;
/* Make sure the outbound skb has enough header
* room reserved.
*/
skb_reserve(nskb, packet->overhead + MAX_HEADER);
} else {
nskb = head;
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);
/**
* 3.2 Chunk Field Descriptions
*
* The total length of a chunk (including Type, Length and
* Value fields) MUST be a multiple of 4 bytes. If the length
* of the chunk is not a multiple of 4 bytes, the sender MUST
* pad the chunk with all zero bytes and this padding is not
* included in the chunk length field. The sender should
* never pad with more than 3 bytes.
*
* [This whole comment explains SCTP_PAD4() below.]
*/
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)) {
/* 6.3.1 C4) When data is in flight and when allowed
* by rule C5, a new RTT measurement MUST be made each
* round trip. Furthermore, new RTT measurements
* SHOULD be made no more than once per round-trip
* for a given destination transport address.
*/
if (!sctp_chunk_retransmitted(chunk) &&
!tp->rto_pending) {
chunk->rtt_in_progress = 1;
tp->rto_pending = 1;
}
has_data = 1;
}
padding = SCTP_PAD4(chunk->skb->len) - chunk->skb->len;
if (padding)
memset(skb_put(chunk->skb, padding), 0, padding);
/* if this is the auth chunk that we are adding,
* store pointer where it will be added and put
* the auth into the packet.
*/
if (chunk == packet->auth)
auth = skb_tail_pointer(nskb);
auth = (struct sctp_auth_chunk *)
skb_tail_pointer(nskb);
memcpy(skb_put(nskb, chunk->skb->len),
chunk->skb->data, chunk->skb->len);
memcpy(skb_put(nskb, chunk->skb->len), 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,
@ -589,11 +474,6 @@ int sctp_packet_transmit(struct sctp_packet *packet, gfp_t gfp)
ntohs(chunk->chunk_hdr->length), chunk->skb->len,
chunk->rtt_in_progress);
/* If this is a control chunk, this is our last
* reference. Free data chunks after they've been
* acknowledged or have failed.
* Re-queue auth chunks if needed.
*/
pkt_size -= SCTP_PAD4(chunk->skb->len);
if (!sctp_chunk_is_data(chunk) && chunk != packet->auth)
@ -603,160 +483,161 @@ int sctp_packet_transmit(struct sctp_packet *packet, gfp_t gfp)
break;
}
/* SCTP-AUTH, Section 6.2
* The sender MUST calculate the MAC as described in RFC2104 [2]
* using the hash function H as described by the MAC Identifier and
* the shared association key K based on the endpoint pair shared key
* described by the shared key identifier. The 'data' used for the
* computation of the AUTH-chunk is given by the AUTH chunk with its
* HMAC field set to zero (as shown in Figure 6) followed by all
* chunks that are placed after the AUTH chunk in the SCTP packet.
*/
if (auth)
sctp_auth_calculate_hmac(asoc, nskb,
(struct sctp_auth_chunk *)auth,
gfp);
if (packet->auth) {
if (!list_empty(&packet->chunk_list)) {
/* We will generate more packets, so re-queue
* auth chunk.
*/
if (auth) {
sctp_auth_calculate_hmac(tp->asoc, nskb, auth, 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);
} else {
sctp_chunk_free(packet->auth);
packet->auth = NULL;
}
if (gso) {
if (skb_gro_receive(&head, nskb)) {
kfree_skb(nskb);
return 0;
}
if (WARN_ON_ONCE(skb_shinfo(head)->gso_segs >=
sk->sk_gso_max_segs))
return 0;
}
if (!gso)
break;
if (skb_gro_receive(&head, nskb)) {
kfree_skb(nskb);
goto nomem;
}
nskb = NULL;
if (WARN_ON_ONCE(skb_shinfo(head)->gso_segs >=
sk->sk_gso_max_segs))
goto nomem;
pkt_count++;
} while (!list_empty(&packet->chunk_list));
/* 2) Calculate the Adler-32 checksum of the whole packet,
* including the SCTP common header and all the
* chunks.
*
* Note: Adler-32 is no longer applicable, as has been replaced
* by CRC32-C as described in <draft-ietf-tsvwg-sctpcsum-02.txt>.
*
* If it's a GSO packet, it's postponed to sctp_skb_segment.
*/
if (!sctp_checksum_disable || gso) {
if (!gso && (!(dst->dev->features & NETIF_F_SCTP_CRC) ||
dst_xfrm(dst) || packet->ipfragok)) {
sh->checksum = sctp_compute_cksum(head, 0);
} else {
/* no need to seed pseudo checksum for SCTP */
head->ip_summed = CHECKSUM_PARTIAL;
head->csum_start = skb_transport_header(head) - head->head;
head->csum_offset = offsetof(struct sctphdr, checksum);
}
}
/* IP layer ECN support
* From RFC 2481
* "The ECN-Capable Transport (ECT) bit would be set by the
* data sender to indicate that the end-points of the
* transport protocol are ECN-capable."
*
* Now setting the ECT bit all the time, as it should not cause
* any problems protocol-wise even if our peer ignores it.
*
* Note: The works for IPv6 layer checks this bit too later
* in transmission. See IP6_ECN_flow_xmit().
*/
tp->af_specific->ecn_capable(sk);
/* Set up the IP options. */
/* BUG: not implemented
* For v4 this all lives somewhere in sk->sk_opt...
*/
/* Dump that on IP! */
if (asoc) {
asoc->stats.opackets += pktcount;
if (asoc->peer.last_sent_to != tp)
/* Considering the multiple CPU scenario, this is a
* "correcter" place for last_sent_to. --xguo
*/
asoc->peer.last_sent_to = tp;
}
if (has_data) {
struct timer_list *timer;
unsigned long timeout;
/* Restart the AUTOCLOSE timer when sending data. */
if (sctp_state(asoc, ESTABLISHED) &&
asoc->timeouts[SCTP_EVENT_TIMEOUT_AUTOCLOSE]) {
timer = &asoc->timers[SCTP_EVENT_TIMEOUT_AUTOCLOSE];
timeout = asoc->timeouts[SCTP_EVENT_TIMEOUT_AUTOCLOSE];
if (!mod_timer(timer, jiffies + timeout))
sctp_association_hold(asoc);
}
}
pr_debug("***sctp_transmit_packet*** skb->len:%d\n", head->len);
if (gso) {
/* Cleanup our debris for IP stacks */
memset(head->cb, 0, max(sizeof(struct inet_skb_parm),
sizeof(struct inet6_skb_parm)));
skb_shinfo(head)->gso_segs = pktcount;
skb_shinfo(head)->gso_segs = pkt_count;
skb_shinfo(head)->gso_size = GSO_BY_FRAGS;
/* We have to refresh this in case we are xmiting to
* more than one transport at a time
*/
rcu_read_lock();
if (__sk_dst_get(sk) != tp->dst) {
if (skb_dst(head) != tp->dst) {
dst_hold(tp->dst);
sk_setup_caps(sk, tp->dst);
}
rcu_read_unlock();
goto chksum;
}
if (sctp_checksum_disable)
return 1;
if (!(skb_dst(head)->dev->features & NETIF_F_SCTP_CRC) ||
dst_xfrm(skb_dst(head)) || packet->ipfragok) {
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_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 dst_entry *dst;
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);
sctp_packet_set_owner_w(head, sk);
/* set sctp header */
sh = (struct sctphdr *)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;
/* update dst if in need */
if (!sctp_transport_dst_check(tp)) {
sctp_transport_route(tp, NULL, sctp_sk(sk));
if (asoc && asoc->param_flags & SPP_PMTUD_ENABLE)
sctp_assoc_sync_pmtu(sk, asoc);
}
dst = dst_clone(tp->dst);
if (!dst) {
IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTNOROUTES);
kfree_skb(head);
goto out;
}
skb_dst_set(head, dst);
/* 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;
tp->af_specific->sctp_xmit(head, tp);
goto out;
nomem:
if (packet->auth && list_empty(&packet->auth->list))
sctp_chunk_free(packet->auth);
nodst:
/* FIXME: Returning the 'err' will effect all the associations
* associated with a socket, although only one of the paths of the
* association is unreachable.
* The real failure of a transport or association can be passed on
* to the user via notifications. So setting this error may not be
* required.
*/
/* err = -EHOSTUNREACH; */
kfree_skb(head);
err:
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);
}
out:
sctp_packet_reset(packet);
return err;
return 0;
}
/********************************************************************