// SPDX-License-Identifier: GPL-2.0-or-later
/* SCTP kernel implementation
* Copyright (c) 1999-2000 Cisco, Inc.
* Copyright (c) 1999-2001 Motorola, Inc.
* Copyright (c) 2001-2003 International Business Machines, Corp.
* Copyright (c) 2001 Intel Corp.
* Copyright (c) 2001 Nokia, Inc.
* Copyright (c) 2001 La Monte H.P. Yarroll
*
* This file is part of the SCTP kernel implementation
*
* These functions handle all input from the IP layer into SCTP.
*
* Please send any bug reports or fixes you make to the
* email address(es):
* lksctp developers <[email protected]>
*
* Written or modified by:
* La Monte H.P. Yarroll <[email protected]>
* Karl Knutson <[email protected]>
* Xingang Guo <[email protected]>
* Jon Grimm <[email protected]>
* Hui Huang <[email protected]>
* Daisy Chang <[email protected]>
* Sridhar Samudrala <[email protected]>
* Ardelle Fan <[email protected]>
*/
#include <linux/types.h>
#include <linux/list.h> /* For struct list_head */
#include <linux/socket.h>
#include <linux/ip.h>
#include <linux/time.h> /* For struct timeval */
#include <linux/slab.h>
#include <net/ip.h>
#include <net/icmp.h>
#include <net/snmp.h>
#include <net/sock.h>
#include <net/xfrm.h>
#include <net/sctp/sctp.h>
#include <net/sctp/sm.h>
#include <net/sctp/checksum.h>
#include <net/net_namespace.h>
#include <linux/rhashtable.h>
#include <net/sock_reuseport.h>
/* Forward declarations for internal helpers. */
static int sctp_rcv_ootb(struct sk_buff *);
static struct sctp_association *__sctp_rcv_lookup(struct net *net,
struct sk_buff *skb,
const union sctp_addr *paddr,
const union sctp_addr *laddr,
struct sctp_transport **transportp,
int dif, int sdif);
static struct sctp_endpoint *__sctp_rcv_lookup_endpoint(
struct net *net, struct sk_buff *skb,
const union sctp_addr *laddr,
const union sctp_addr *daddr,
int dif, int sdif);
static struct sctp_association *__sctp_lookup_association(
struct net *net,
const union sctp_addr *local,
const union sctp_addr *peer,
struct sctp_transport **pt,
int dif, int sdif);
static int sctp_add_backlog(struct sock *sk, struct sk_buff *skb);
/* Calculate the SCTP checksum of an SCTP packet. */
static inline int sctp_rcv_checksum(struct net *net, struct sk_buff *skb)
{
struct sctphdr *sh = sctp_hdr(skb);
__le32 cmp = sh->checksum;
__le32 val = sctp_compute_cksum(skb, 0);
if (val != cmp) {
/* CRC failure, dump it. */
__SCTP_INC_STATS(net, SCTP_MIB_CHECKSUMERRORS);
return -1;
}
return 0;
}
/*
* This is the routine which IP calls when receiving an SCTP packet.
*/
int sctp_rcv(struct sk_buff *skb)
{
struct sock *sk;
struct sctp_association *asoc;
struct sctp_endpoint *ep = NULL;
struct sctp_ep_common *rcvr;
struct sctp_transport *transport = NULL;
struct sctp_chunk *chunk;
union sctp_addr src;
union sctp_addr dest;
int family;
struct sctp_af *af;
struct net *net = dev_net(skb->dev);
bool is_gso = skb_is_gso(skb) && skb_is_gso_sctp(skb);
int dif, sdif;
if (skb->pkt_type != PACKET_HOST)
goto discard_it;
__SCTP_INC_STATS(net, SCTP_MIB_INSCTPPACKS);
/* If packet is too small to contain a single chunk, let's not
* waste time on it anymore.
*/
if (skb->len < sizeof(struct sctphdr) + sizeof(struct sctp_chunkhdr) +
skb_transport_offset(skb))
goto discard_it;
/* If the packet is fragmented and we need to do crc checking,
* it's better to just linearize it otherwise crc computing
* takes longer.
*/
if ((!is_gso && skb_linearize(skb)) ||
!pskb_may_pull(skb, sizeof(struct sctphdr)))
goto discard_it;
/* Pull up the IP header. */
__skb_pull(skb, skb_transport_offset(skb));
skb->csum_valid = 0; /* Previous value not applicable */
if (skb_csum_unnecessary(skb))
__skb_decr_checksum_unnecessary(skb);
else if (!sctp_checksum_disable &&
!is_gso &&
sctp_rcv_checksum(net, skb) < 0)
goto discard_it;
skb->csum_valid = 1;
__skb_pull(skb, sizeof(struct sctphdr));
family = ipver2af(ip_hdr(skb)->version);
af = sctp_get_af_specific(family);
if (unlikely(!af))
goto discard_it;
SCTP_INPUT_CB(skb)->af = af;
/* Initialize local addresses for lookups. */
af->from_skb(&src, skb, 1);
af->from_skb(&dest, skb, 0);
dif = af->skb_iif(skb);
sdif = af->skb_sdif(skb);
/* If the packet is to or from a non-unicast address,
* silently discard the packet.
*
* This is not clearly defined in the RFC except in section
* 8.4 - OOTB handling. However, based on the book "Stream Control
* Transmission Protocol" 2.1, "It is important to note that the
* IP address of an SCTP transport address must be a routable
* unicast address. In other words, IP multicast addresses and
* IP broadcast addresses cannot be used in an SCTP transport
* address."
*/
if (!af->addr_valid(&src, NULL, skb) ||
!af->addr_valid(&dest, NULL, skb))
goto discard_it;
asoc = __sctp_rcv_lookup(net, skb, &src, &dest, &transport, dif, sdif);
if (!asoc)
ep = __sctp_rcv_lookup_endpoint(net, skb, &dest, &src, dif, sdif);
/* Retrieve the common input handling substructure. */
rcvr = asoc ? &asoc->base : &ep->base;
sk = rcvr->sk;
/*
* RFC 2960, 8.4 - Handle "Out of the blue" Packets.
* An SCTP packet is called an "out of the blue" (OOTB)
* packet if it is correctly formed, i.e., passed the
* receiver's checksum check, but the receiver is not
* able to identify the association to which this
* packet belongs.
*/
if (!asoc) {
if (sctp_rcv_ootb(skb)) {
__SCTP_INC_STATS(net, SCTP_MIB_OUTOFBLUES);
goto discard_release;
}
}
if (!xfrm_policy_check(sk, XFRM_POLICY_IN, skb, family))
goto discard_release;
nf_reset_ct(skb);
if (sk_filter(sk, skb))
goto discard_release;
/* Create an SCTP packet structure. */
chunk = sctp_chunkify(skb, asoc, sk, GFP_ATOMIC);
if (!chunk)
goto discard_release;
SCTP_INPUT_CB(skb)->chunk = chunk;
/* Remember what endpoint is to handle this packet. */
chunk->rcvr = rcvr;
/* Remember the SCTP header. */
chunk->sctp_hdr = sctp_hdr(skb);
/* Set the source and destination addresses of the incoming chunk. */
sctp_init_addrs(chunk, &src, &dest);
/* Remember where we came from. */
chunk->transport = transport;
/* Acquire access to the sock lock. Note: We are safe from other
* bottom halves on this lock, but a user may be in the lock too,
* so check if it is busy.
*/
bh_lock_sock(sk);
if (sk != rcvr->sk) {
/* Our cached sk is different from the rcvr->sk. This is
* because migrate()/accept() may have moved the association
* to a new socket and released all the sockets. So now we
* are holding a lock on the old socket while the user may
* be doing something with the new socket. Switch our veiw
* of the current sk.
*/
bh_unlock_sock(sk);
sk = rcvr->sk;
bh_lock_sock(sk);
}
if (sock_owned_by_user(sk) || !sctp_newsk_ready(sk)) {
if (sctp_add_backlog(sk, skb)) {
bh_unlock_sock(sk);
sctp_chunk_free(chunk);
skb = NULL; /* sctp_chunk_free already freed the skb */
goto discard_release;
}
__SCTP_INC_STATS(net, SCTP_MIB_IN_PKT_BACKLOG);
} else {
__SCTP_INC_STATS(net, SCTP_MIB_IN_PKT_SOFTIRQ);
sctp_inq_push(&chunk->rcvr->inqueue, chunk);
}
bh_unlock_sock(sk);
/* Release the asoc/ep ref we took in the lookup calls. */
if (transport)
sctp_transport_put(transport);
else
sctp_endpoint_put(ep);
return 0;
discard_it:
__SCTP_INC_STATS(net, SCTP_MIB_IN_PKT_DISCARDS);
kfree_skb(skb);
return 0;
discard_release:
/* Release the asoc/ep ref we took in the lookup calls. */
if (transport)
sctp_transport_put(transport);
else
sctp_endpoint_put(ep);
goto discard_it;
}
/* Process the backlog queue of the socket. Every skb on
* the backlog holds a ref on an association or endpoint.
* We hold this ref throughout the state machine to make
* sure that the structure we need is still around.
*/
int sctp_backlog_rcv(struct sock *sk, struct sk_buff *skb)
{
struct sctp_chunk *chunk = SCTP_INPUT_CB(skb)->chunk;
struct sctp_inq *inqueue = &chunk->rcvr->inqueue;
struct sctp_transport *t = chunk->transport;
struct sctp_ep_common *rcvr = NULL;
int backloged = 0;
rcvr = chunk->rcvr;
/* If the rcvr is dead then the association or endpoint
* has been deleted and we can safely drop the chunk
* and refs that we are holding.
*/
if (rcvr->dead) {
sctp_chunk_free(chunk);
goto done;
}
if (unlikely(rcvr->sk != sk)) {
/* In this case, the association moved from one socket to
* another. We are currently sitting on the backlog of the
* old socket, so we need to move.
* However, since we are here in the process context we
* need to take make sure that the user doesn't own
* the new socket when we process the packet.
* If the new socket is user-owned, queue the chunk to the
* backlog of the new socket without dropping any refs.
* Otherwise, we can safely push the chunk on the inqueue.
*/
sk = rcvr->sk;
local_bh_disable();
bh_lock_sock(sk);
if (sock_owned_by_user(sk) || !sctp_newsk_ready(sk)) {
if (sk_add_backlog(sk, skb, READ_ONCE(sk->sk_rcvbuf)))
sctp_chunk_free(chunk);
else
backloged = 1;
} else
sctp_inq_push(inqueue, chunk);
bh_unlock_sock(sk);
local_bh_enable();
/* If the chunk was backloged again, don't drop refs */
if (backloged)
return 0;
} else {
if (!sctp_newsk_ready(sk)) {
if (!sk_add_backlog(sk, skb, READ_ONCE(sk->sk_rcvbuf)))
return 0;
sctp_chunk_free(chunk);
} else {
sctp_inq_push(inqueue, chunk);
}
}
done:
/* Release the refs we took in sctp_add_backlog */
if (SCTP_EP_TYPE_ASSOCIATION == rcvr->type)
sctp_transport_put(t);
else if (SCTP_EP_TYPE_SOCKET == rcvr->type)
sctp_endpoint_put(sctp_ep(rcvr));
else
BUG();
return 0;
}
static int sctp_add_backlog(struct sock *sk, struct sk_buff *skb)
{
struct sctp_chunk *chunk = SCTP_INPUT_CB(skb)->chunk;
struct sctp_transport *t = chunk->transport;
struct sctp_ep_common *rcvr = chunk->rcvr;
int ret;
ret = sk_add_backlog(sk, skb, READ_ONCE(sk->sk_rcvbuf));
if (!ret) {
/* Hold the assoc/ep while hanging on the backlog queue.
* This way, we know structures we need will not disappear
* from us
*/
if (SCTP_EP_TYPE_ASSOCIATION == rcvr->type)
sctp_transport_hold(t);
else if (SCTP_EP_TYPE_SOCKET == rcvr->type)
sctp_endpoint_hold(sctp_ep(rcvr));
else
BUG();
}
return ret;
}
/* Handle icmp frag needed error. */
void sctp_icmp_frag_needed(struct sock *sk, struct sctp_association *asoc,
struct sctp_transport *t, __u32 pmtu)
{
if (!t ||
(t->pathmtu <= pmtu &&
t->pl.probe_size + sctp_transport_pl_hlen(t) <= pmtu))
return;
if (sock_owned_by_user(sk)) {
atomic_set(&t->mtu_info, pmtu);
asoc->pmtu_pending = 1;
t->pmtu_pending = 1;
return;
}
if (!(t->param_flags & SPP_PMTUD_ENABLE))
/* We can't allow retransmitting in such case, as the
* retransmission would be sized just as before, and thus we
* would get another icmp, and retransmit again.
*/
return;
/* Update transports view of the MTU. Return if no update was needed.
* If an update wasn't needed/possible, it also doesn't make sense to
* try to retransmit now.
*/
if (!sctp_transport_update_pmtu(t, pmtu))
return;
/* Update association pmtu. */
sctp_assoc_sync_pmtu(asoc);
/* Retransmit with the new pmtu setting. */
sctp_retransmit(&asoc->outqueue, t, SCTP_RTXR_PMTUD);
}
void sctp_icmp_redirect(struct sock *sk, struct sctp_transport *t,
struct sk_buff *skb)
{
struct dst_entry *dst;
if (sock_owned_by_user(sk) || !t)
return;
dst = sctp_transport_dst_check(t);
if (dst)
dst->ops->redirect(dst, sk, skb);
}
/*
* SCTP Implementer's Guide, 2.37 ICMP handling procedures
*
* ICMP8) If the ICMP code is a "Unrecognized next header type encountered"
* or a "Protocol Unreachable" treat this message as an abort
* with the T bit set.
*
* This function sends an event to the state machine, which will abort the
* association.
*
*/
void sctp_icmp_proto_unreachable(struct sock *sk,
struct sctp_association *asoc,
struct sctp_transport *t)
{
if (sock_owned_by_user(sk)) {
if (timer_pending(&t->proto_unreach_timer))
return;
else {
if (!mod_timer(&t->proto_unreach_timer,
jiffies + (HZ/20)))
sctp_transport_hold(t);
}
} else {
struct net *net = sock_net(sk);
pr_debug("%s: unrecognized next header type "
"encountered!\n", __func__);
if (del_timer(&t->proto_unreach_timer))
sctp_transport_put(t);
sctp_do_sm(net, SCTP_EVENT_T_OTHER,
SCTP_ST_OTHER(SCTP_EVENT_ICMP_PROTO_UNREACH),
asoc->state, asoc->ep, asoc, t,
GFP_ATOMIC);
}
}
/* Common lookup code for icmp/icmpv6 error handler. */
struct sock *sctp_err_lookup(struct net *net, int family, struct sk_buff *skb,
struct sctphdr *sctphdr,
struct sctp_association **app,
struct sctp_transport **tpp)
{
struct sctp_init_chunk *chunkhdr, _chunkhdr;
union sctp_addr saddr;
union sctp_addr daddr;
struct sctp_af *af;
struct sock *sk = NULL;
struct sctp_association *asoc;
struct sctp_transport *transport = NULL;
__u32 vtag = ntohl(sctphdr->vtag);
int sdif = inet_sdif(skb);
int dif = inet_iif(skb);
*app = NULL; *tpp = NULL;
af = sctp_get_af_specific(family);
if (unlikely(!af)) {
return NULL;
}
/* Initialize local addresses for lookups. */
af->from_skb(&saddr, skb, 1);
af->from_skb(&daddr, skb, 0);
/* Look for an association that matches the incoming ICMP error
* packet.
*/
asoc = __sctp_lookup_association(net, &saddr, &daddr, &transport, dif, sdif);
if (!asoc)
return NULL;
sk = asoc->base.sk;
/* RFC 4960, Appendix C. ICMP Handling
*
* ICMP6) An implementation MUST validate that the Verification Tag
* contained in the ICMP message matches the Verification Tag of
* the peer. If the Verification Tag is not 0 and does NOT
* match, discard the ICMP message. If it is 0 and the ICMP
* message contains enough bytes to verify that the chunk type is
* an INIT chunk and that the Initiate Tag matches the tag of the
* peer, continue with ICMP7. If the ICMP message is too short
* or the chunk type or the Initiate Tag does not match, silently
* discard the packet.
*/
if (vtag == 0) {
/* chunk header + first 4 octects of init header */
chunkhdr = skb_header_pointer(skb, skb_transport_offset(skb) +
sizeof(struct sctphdr),
sizeof(struct sctp_chunkhdr) +
sizeof(__be32), &_chunkhdr);
if (!chunkhdr ||
chunkhdr->chunk_hdr.type != SCTP_CID_INIT ||
ntohl(chunkhdr->init_hdr.init_tag) != asoc->c.my_vtag)
goto out;
} else if (vtag != asoc->c.peer_vtag) {
goto out;
}
bh_lock_sock(sk);
/* If too many ICMPs get dropped on busy
* servers this needs to be solved differently.
*/
if (sock_owned_by_user(sk))
__NET_INC_STATS(net, LINUX_MIB_LOCKDROPPEDICMPS);
*app = asoc;
*tpp = transport;
return sk;
out:
sctp_transport_put(transport);
return NULL;
}
/* Common cleanup code for icmp/icmpv6 error handler. */
void sctp_err_finish(struct sock *sk, struct sctp_transport *t)
__releases(&((__sk)->sk_lock.slock))
{
bh_unlock_sock(sk);
sctp_transport_put(t);
}
static void sctp_v4_err_handle(struct sctp_transport *t, struct sk_buff *skb,
__u8 type, __u8 code, __u32 info)
{
struct sctp_association *asoc = t->asoc;
struct sock *sk = asoc->base.sk;
int err = 0;
switch (type) {
case ICMP_PARAMETERPROB:
err = EPROTO;
break;
case ICMP_DEST_UNREACH:
if (code > NR_ICMP_UNREACH)
return;
if (code == ICMP_FRAG_NEEDED) {
sctp_icmp_frag_needed(sk, asoc, t, SCTP_TRUNC4(info));
return;
}
if (code == ICMP_PROT_UNREACH) {
sctp_icmp_proto_unreachable(sk, asoc, t);
return;
}
err = icmp_err_convert[code].errno;
break;
case ICMP_TIME_EXCEEDED:
if (code == ICMP_EXC_FRAGTIME)
return;
err = EHOSTUNREACH;
break;
case ICMP_REDIRECT:
sctp_icmp_redirect(sk, t, skb);
return;
default:
return;
}
if (!sock_owned_by_user(sk) && inet_test_bit(RECVERR, sk)) {
sk->sk_err = err;
sk_error_report(sk);
} else { /* Only an error on timeout */
WRITE_ONCE(sk->sk_err_soft, err);
}
}
/*
* This routine is called by the ICMP module when it gets some
* sort of error condition. If err < 0 then the socket should
* be closed and the error returned to the user. If err > 0
* it's just the icmp type << 8 | icmp code. After adjustment
* header points to the first 8 bytes of the sctp header. We need
* to find the appropriate port.
*
* The locking strategy used here is very "optimistic". When
* someone else accesses the socket the ICMP is just dropped
* and for some paths there is no check at all.
* A more general error queue to queue errors for later handling
* is probably better.
*
*/
int sctp_v4_err(struct sk_buff *skb, __u32 info)
{
const struct iphdr *iph = (const struct iphdr *)skb->data;
const int type = icmp_hdr(skb)->type;
const int code = icmp_hdr(skb)->code;
struct net *net = dev_net(skb->dev);
struct sctp_transport *transport;
struct sctp_association *asoc;
__u16 saveip, savesctp;
struct sock *sk;
/* Fix up skb to look at the embedded net header. */
saveip = skb->network_header;
savesctp = skb->transport_header;
skb_reset_network_header(skb);
skb_set_transport_header(skb, iph->ihl * 4);
sk = sctp_err_lookup(net, AF_INET, skb, sctp_hdr(skb), &asoc, &transport);
/* Put back, the original values. */
skb->network_header = saveip;
skb->transport_header = savesctp;
if (!sk) {
__ICMP_INC_STATS(net, ICMP_MIB_INERRORS);
return -ENOENT;
}
sctp_v4_err_handle(transport, skb, type, code, info);
sctp_err_finish(sk, transport);
return 0;
}
int sctp_udp_v4_err(struct sock *sk, struct sk_buff *skb)
{
struct net *net = dev_net(skb->dev);
struct sctp_association *asoc;
struct sctp_transport *t;
struct icmphdr *hdr;
__u32 info = 0;
skb->transport_header += sizeof(struct udphdr);
sk = sctp_err_lookup(net, AF_INET, skb, sctp_hdr(skb), &asoc, &t);
if (!sk) {
__ICMP_INC_STATS(net, ICMP_MIB_INERRORS);
return -ENOENT;
}
skb->transport_header -= sizeof(struct udphdr);
hdr = (struct icmphdr *)(skb_network_header(skb) - sizeof(struct icmphdr));
if (hdr->type == ICMP_REDIRECT) {
/* can't be handled without outer iphdr known, leave it to udp_err */
sctp_err_finish(sk, t);
return 0;
}
if (hdr->type == ICMP_DEST_UNREACH && hdr->code == ICMP_FRAG_NEEDED)
info = ntohs(hdr->un.frag.mtu);
sctp_v4_err_handle(t, skb, hdr->type, hdr->code, info);
sctp_err_finish(sk, t);
return 1;
}
/*
* RFC 2960, 8.4 - Handle "Out of the blue" Packets.
*
* This function scans all the chunks in the OOTB packet to determine if
* the packet should be discarded right away. If a response might be needed
* for this packet, or, if further processing is possible, the packet will
* be queued to a proper inqueue for the next phase of handling.
*
* Output:
* Return 0 - If further processing is needed.
* Return 1 - If the packet can be discarded right away.
*/
static int sctp_rcv_ootb(struct sk_buff *skb)
{
struct sctp_chunkhdr *ch, _ch;
int ch_end, offset = 0;
/* Scan through all the chunks in the packet. */
do {
/* Make sure we have at least the header there */
if (offset + sizeof(_ch) > skb->len)
break;
ch = skb_header_pointer(skb, offset, sizeof(*ch), &_ch);
/* Break out if chunk length is less then minimal. */
if (!ch || ntohs(ch->length) < sizeof(_ch))
break;
ch_end = offset + SCTP_PAD4(ntohs(ch->length));
if (ch_end > skb->len)
break;
/* RFC 8.4, 2) If the OOTB packet contains an ABORT chunk, the
* receiver MUST silently discard the OOTB packet and take no
* further action.
*/
if (SCTP_CID_ABORT == ch->type)
goto discard;
/* RFC 8.4, 6) If the packet contains a SHUTDOWN COMPLETE
* chunk, the receiver should silently discard the packet
* and take no further action.
*/
if (SCTP_CID_SHUTDOWN_COMPLETE == ch->type)
goto discard;
/* RFC 4460, 2.11.2
* This will discard packets with INIT chunk bundled as
* subsequent chunks in the packet. When INIT is first,
* the normal INIT processing will discard the chunk.
*/
if (SCTP_CID_INIT == ch->type && (void *)ch != skb->data)
goto discard;
offset = ch_end;
} while (ch_end < skb->len);
return 0;
discard:
return 1;
}
/* Insert endpoint into the hash table. */
static int __sctp_hash_endpoint(struct sctp_endpoint *ep)
{
struct sock *sk = ep->base.sk;
struct net *net = sock_net(sk);
struct sctp_hashbucket *head;
int err = 0;
ep->hashent = sctp_ep_hashfn(net, ep->base.bind_addr.port);
head = &sctp_ep_hashtable[ep->hashent];
write_lock(&head->lock);
if (sk->sk_reuseport) {
bool any = sctp_is_ep_boundall(sk);
struct sctp_endpoint *ep2;
struct list_head *list;
int cnt = 0;
err = 1;
list_for_each(list, &ep->base.bind_addr.address_list)
cnt++;
sctp_for_each_hentry(ep2, &head->chain) {
struct sock *sk2 = ep2->base.sk;
if (!net_eq(sock_net(sk2), net) || sk2 == sk ||
!uid_eq(sock_i_uid(sk2), sock_i_uid(sk)) ||
!sk2->sk_reuseport)
continue;
err = sctp_bind_addrs_check(sctp_sk(sk2),
sctp_sk(sk), cnt);
if (!err) {
err = reuseport_add_sock(sk, sk2, any);
if (err)
goto out;
break;
} else if (err < 0) {
goto out;
}
}
if (err) {
err = reuseport_alloc(sk, any);
if (err)
goto out;
}
}
hlist_add_head(&ep->node, &head->chain);
out:
write_unlock(&head->lock);
return err;
}
/* Add an endpoint to the hash. Local BH-safe. */
int sctp_hash_endpoint(struct sctp_endpoint *ep)
{
int err;
local_bh_disable();
err = __sctp_hash_endpoint(ep);
local_bh_enable();
return err;
}
/* Remove endpoint from the hash table. */
static void __sctp_unhash_endpoint(struct sctp_endpoint *ep)
{
struct sock *sk = ep->base.sk;
struct sctp_hashbucket *head;
ep->hashent = sctp_ep_hashfn(sock_net(sk), ep->base.bind_addr.port);
head = &sctp_ep_hashtable[ep->hashent];
write_lock(&head->lock);
if (rcu_access_pointer(sk->sk_reuseport_cb))
reuseport_detach_sock(sk);
hlist_del_init(&ep->node);
write_unlock(&head->lock);
}
/* Remove endpoint from the hash. Local BH-safe. */
void sctp_unhash_endpoint(struct sctp_endpoint *ep)
{
local_bh_disable();
__sctp_unhash_endpoint(ep);
local_bh_enable();
}
static inline __u32 sctp_hashfn(const struct net *net, __be16 lport,
const union sctp_addr *paddr, __u32 seed)
{
__u32 addr;
if (paddr->sa.sa_family == AF_INET6)
addr = jhash(&paddr->v6.sin6_addr, 16, seed);
else
addr = (__force __u32)paddr->v4.sin_addr.s_addr;
return jhash_3words(addr, ((__force __u32)paddr->v4.sin_port) << 16 |
(__force __u32)lport, net_hash_mix(net), seed);
}
/* Look up an endpoint. */
static struct sctp_endpoint *__sctp_rcv_lookup_endpoint(
struct net *net, struct sk_buff *skb,
const union sctp_addr *laddr,
const union sctp_addr *paddr,
int dif, int sdif)
{
struct sctp_hashbucket *head;
struct sctp_endpoint *ep;
struct sock *sk;
__be16 lport;
int hash;
lport = laddr->v4.sin_port;
hash = sctp_ep_hashfn(net, ntohs(lport));
head = &sctp_ep_hashtable[hash];
read_lock(&head->lock);
sctp_for_each_hentry(ep, &head->chain) {
if (sctp_endpoint_is_match(ep, net, laddr, dif, sdif))
goto hit;
}
ep = sctp_sk(net->sctp.ctl_sock)->ep;
hit:
sk = ep->base.sk;
if (sk->sk_reuseport) {
__u32 phash = sctp_hashfn(net, lport, paddr, 0);
sk = reuseport_select_sock(sk, phash, skb,
sizeof(struct sctphdr));
if (sk)
ep = sctp_sk(sk)->ep;
}
sctp_endpoint_hold(ep);
read_unlock(&head->lock);
return ep;
}
/* rhashtable for transport */
struct sctp_hash_cmp_arg {
const union sctp_addr *paddr;
const struct net *net;
__be16 lport;
};
static inline int sctp_hash_cmp(struct rhashtable_compare_arg *arg,
const void *ptr)
{
struct sctp_transport *t = (struct sctp_transport *)ptr;
const struct sctp_hash_cmp_arg *x = arg->key;
int err = 1;
if (!sctp_cmp_addr_exact(&t->ipaddr, x->paddr))
return err;
if (!sctp_transport_hold(t))
return err;
if (!net_eq(t->asoc->base.net, x->net))
goto out;
if (x->lport != htons(t->asoc->base.bind_addr.port))
goto out;
err = 0;
out:
sctp_transport_put(t);
return err;
}
static inline __u32 sctp_hash_obj(const void *data, u32 len, u32 seed)
{
const struct sctp_transport *t = data;
return sctp_hashfn(t->asoc->base.net,
htons(t->asoc->base.bind_addr.port),
&t->ipaddr, seed);
}
static inline __u32 sctp_hash_key(const void *data, u32 len, u32 seed)
{
const struct sctp_hash_cmp_arg *x = data;
return sctp_hashfn(x->net, x->lport, x->paddr, seed);
}
static const struct rhashtable_params sctp_hash_params = {
.head_offset = offsetof(struct sctp_transport, node),
.hashfn = sctp_hash_key,
.obj_hashfn = sctp_hash_obj,
.obj_cmpfn = sctp_hash_cmp,
.automatic_shrinking = true,
};
int sctp_transport_hashtable_init(void)
{
return rhltable_init(&sctp_transport_hashtable, &sctp_hash_params);
}
void sctp_transport_hashtable_destroy(void)
{
rhltable_destroy(&sctp_transport_hashtable);
}
int sctp_hash_transport(struct sctp_transport *t)
{
struct sctp_transport *transport;
struct rhlist_head *tmp, *list;
struct sctp_hash_cmp_arg arg;
int err;
if (t->asoc->temp)
return 0;
arg.net = t->asoc->base.net;
arg.paddr = &t->ipaddr;
arg.lport = htons(t->asoc->base.bind_addr.port);
rcu_read_lock();
list = rhltable_lookup(&sctp_transport_hashtable, &arg,
sctp_hash_params);
rhl_for_each_entry_rcu(transport, tmp, list, node)
if (transport->asoc->ep == t->asoc->ep) {
rcu_read_unlock();
return -EEXIST;
}
rcu_read_unlock();
err = rhltable_insert_key(&sctp_transport_hashtable, &arg,
&t->node, sctp_hash_params);
if (err)
pr_err_once("insert transport fail, errno %d\n", err);
return err;
}
void sctp_unhash_transport(struct sctp_transport *t)
{
if (t->asoc->temp)
return;
rhltable_remove(&sctp_transport_hashtable, &t->node,
sctp_hash_params);
}
bool sctp_sk_bound_dev_eq(struct net *net, int bound_dev_if, int dif, int sdif)
{
bool l3mdev_accept = true;
#if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV)
l3mdev_accept = !!READ_ONCE(net->sctp.l3mdev_accept);
#endif
return inet_bound_dev_eq(l3mdev_accept, bound_dev_if, dif, sdif);
}
/* return a transport with holding it */
struct sctp_transport *sctp_addrs_lookup_transport(
struct net *net,
const union sctp_addr *laddr,
const union sctp_addr *paddr,
int dif, int sdif)
{
struct rhlist_head *tmp, *list;
struct sctp_transport *t;
int bound_dev_if;
struct sctp_hash_cmp_arg arg = {
.paddr = paddr,
.net = net,
.lport = laddr->v4.sin_port,
};
list = rhltable_lookup(&sctp_transport_hashtable, &arg,
sctp_hash_params);
rhl_for_each_entry_rcu(t, tmp, list, node) {
if (!sctp_transport_hold(t))
continue;
bound_dev_if = READ_ONCE(t->asoc->base.sk->sk_bound_dev_if);
if (sctp_sk_bound_dev_eq(net, bound_dev_if, dif, sdif) &&
sctp_bind_addr_match(&t->asoc->base.bind_addr,
laddr, sctp_sk(t->asoc->base.sk)))
return t;
sctp_transport_put(t);
}
return NULL;
}
/* return a transport without holding it, as it's only used under sock lock */
struct sctp_transport *sctp_epaddr_lookup_transport(
const struct sctp_endpoint *ep,
const union sctp_addr *paddr)
{
struct rhlist_head *tmp, *list;
struct sctp_transport *t;
struct sctp_hash_cmp_arg arg = {
.paddr = paddr,
.net = ep->base.net,
.lport = htons(ep->base.bind_addr.port),
};
list = rhltable_lookup(&sctp_transport_hashtable, &arg,
sctp_hash_params);
rhl_for_each_entry_rcu(t, tmp, list, node)
if (ep == t->asoc->ep)
return t;
return NULL;
}
/* Look up an association. */
static struct sctp_association *__sctp_lookup_association(
struct net *net,
const union sctp_addr *local,
const union sctp_addr *peer,
struct sctp_transport **pt,
int dif, int sdif)
{
struct sctp_transport *t;
struct sctp_association *asoc = NULL;
t = sctp_addrs_lookup_transport(net, local, peer, dif, sdif);
if (!t)
goto out;
asoc = t->asoc;
*pt = t;
out:
return asoc;
}
/* Look up an association. protected by RCU read lock */
static
struct sctp_association *sctp_lookup_association(struct net *net,
const union sctp_addr *laddr,
const union sctp_addr *paddr,
struct sctp_transport **transportp,
int dif, int sdif)
{
struct sctp_association *asoc;
rcu_read_lock();
asoc = __sctp_lookup_association(net, laddr, paddr, transportp, dif, sdif);
rcu_read_unlock();
return asoc;
}
/* Is there an association matching the given local and peer addresses? */
bool sctp_has_association(struct net *net,
const union sctp_addr *laddr,
const union sctp_addr *paddr,
int dif, int sdif)
{
struct sctp_transport *transport;
if (sctp_lookup_association(net, laddr, paddr, &transport, dif, sdif)) {
sctp_transport_put(transport);
return true;
}
return false;
}
/*
* SCTP Implementors Guide, 2.18 Handling of address
* parameters within the INIT or INIT-ACK.
*
* D) When searching for a matching TCB upon reception of an INIT
* or INIT-ACK chunk the receiver SHOULD use not only the
* source address of the packet (containing the INIT or
* INIT-ACK) but the receiver SHOULD also use all valid
* address parameters contained within the chunk.
*
* 2.18.3 Solution description
*
* This new text clearly specifies to an implementor the need
* to look within the INIT or INIT-ACK. Any implementation that
* does not do this, may not be able to establish associations
* in certain circumstances.
*
*/
static struct sctp_association *__sctp_rcv_init_lookup(struct net *net,
struct sk_buff *skb,
const union sctp_addr *laddr, struct sctp_transport **transportp,
int dif, int sdif)
{
struct sctp_association *asoc;
union sctp_addr addr;
union sctp_addr *paddr = &addr;
struct sctphdr *sh = sctp_hdr(skb);
union sctp_params params;
struct sctp_init_chunk *init;
struct sctp_af *af;
/*
* This code will NOT touch anything inside the chunk--it is
* strictly READ-ONLY.
*
* RFC 2960 3 SCTP packet Format
*
* Multiple chunks can be bundled into one SCTP packet up to
* the MTU size, except for the INIT, INIT ACK, and SHUTDOWN
* COMPLETE chunks. These chunks MUST NOT be bundled with any
* other chunk in a packet. See Section 6.10 for more details
* on chunk bundling.
*/
/* Find the start of the TLVs and the end of the chunk. This is
* the region we search for address parameters.
*/
init = (struct sctp_init_chunk *)skb->data;
/* Walk the parameters looking for embedded addresses. */
sctp_walk_params(params, init) {
/* Note: Ignoring hostname addresses. */
af = sctp_get_af_specific(param_type2af(params.p->type));
if (!af)
continue;
if (!af->from_addr_param(paddr, params.addr, sh->source, 0))
continue;
asoc = __sctp_lookup_association(net, laddr, paddr, transportp, dif, sdif);
if (asoc)
return asoc;
}
return NULL;
}
/* ADD-IP, Section 5.2
* When an endpoint receives an ASCONF Chunk from the remote peer
* special procedures may be needed to identify the association the
* ASCONF Chunk is associated with. To properly find the association
* the following procedures SHOULD be followed:
*
* D2) If the association is not found, use the address found in the
* Address Parameter TLV combined with the port number found in the
* SCTP common header. If found proceed to rule D4.
*
* D2-ext) If more than one ASCONF Chunks are packed together, use the
* address found in the ASCONF Address Parameter TLV of each of the
* subsequent ASCONF Chunks. If found, proceed to rule D4.
*/
static struct sctp_association *__sctp_rcv_asconf_lookup(
struct net *net,
struct sctp_chunkhdr *ch,
const union sctp_addr *laddr,
__be16 peer_port,
struct sctp_transport **transportp,
int dif, int sdif)
{
struct sctp_addip_chunk *asconf = (struct sctp_addip_chunk *)ch;
struct sctp_af *af;
union sctp_addr_param *param;
union sctp_addr paddr;
if (ntohs(ch->length) < sizeof(*asconf) + sizeof(struct sctp_paramhdr))
return NULL;
/* Skip over the ADDIP header and find the Address parameter */
param = (union sctp_addr_param *)(asconf + 1);
af = sctp_get_af_specific(param_type2af(param->p.type));
if (unlikely(!af))
return NULL;
if (!af->from_addr_param(&paddr, param, peer_port, 0))
return NULL;
return __sctp_lookup_association(net, laddr, &paddr, transportp, dif, sdif);
}
/* SCTP-AUTH, Section 6.3:
* If the receiver does not find a STCB for a packet containing an AUTH
* chunk as the first chunk and not a COOKIE-ECHO chunk as the second
* chunk, it MUST use the chunks after the AUTH chunk to look up an existing
* association.
*
* This means that any chunks that can help us identify the association need
* to be looked at to find this association.
*/
static struct sctp_association *__sctp_rcv_walk_lookup(struct net *net,
struct sk_buff *skb,
const union sctp_addr *laddr,
struct sctp_transport **transportp,
int dif, int sdif)
{
struct sctp_association *asoc = NULL;
struct sctp_chunkhdr *ch;
int have_auth = 0;
unsigned int chunk_num = 1;
__u8 *ch_end;
/* Walk through the chunks looking for AUTH or ASCONF chunks
* to help us find the association.
*/
ch = (struct sctp_chunkhdr *)skb->data;
do {
/* Break out if chunk length is less then minimal. */
if (ntohs(ch->length) < sizeof(*ch))
break;
ch_end = ((__u8 *)ch) + SCTP_PAD4(ntohs(ch->length));
if (ch_end > skb_tail_pointer(skb))
break;
switch (ch->type) {
case SCTP_CID_AUTH:
have_auth = chunk_num;
break;
case SCTP_CID_COOKIE_ECHO:
/* If a packet arrives containing an AUTH chunk as
* a first chunk, a COOKIE-ECHO chunk as the second
* chunk, and possibly more chunks after them, and
* the receiver does not have an STCB for that
* packet, then authentication is based on
* the contents of the COOKIE- ECHO chunk.
*/
if (have_auth == 1 && chunk_num == 2)
return NULL;
break;
case SCTP_CID_ASCONF:
if (have_auth || net->sctp.addip_noauth)
asoc = __sctp_rcv_asconf_lookup(
net, ch, laddr,
sctp_hdr(skb)->source,
transportp, dif, sdif);
break;
default:
break;
}
if (asoc)
break;
ch = (struct sctp_chunkhdr *)ch_end;
chunk_num++;
} while (ch_end + sizeof(*ch) < skb_tail_pointer(skb));
return asoc;
}
/*
* There are circumstances when we need to look inside the SCTP packet
* for information to help us find the association. Examples
* include looking inside of INIT/INIT-ACK chunks or after the AUTH
* chunks.
*/
static struct sctp_association *__sctp_rcv_lookup_harder(struct net *net,
struct sk_buff *skb,
const union sctp_addr *laddr,
struct sctp_transport **transportp,
int dif, int sdif)
{
struct sctp_chunkhdr *ch;
/* We do not allow GSO frames here as we need to linearize and
* then cannot guarantee frame boundaries. This shouldn't be an
* issue as packets hitting this are mostly INIT or INIT-ACK and
* those cannot be on GSO-style anyway.
*/
if (skb_is_gso(skb) && skb_is_gso_sctp(skb))
return NULL;
ch = (struct sctp_chunkhdr *)skb->data;
/* The code below will attempt to walk the chunk and extract
* parameter information. Before we do that, we need to verify
* that the chunk length doesn't cause overflow. Otherwise, we'll
* walk off the end.
*/
if (SCTP_PAD4(ntohs(ch->length)) > skb->len)
return NULL;
/* If this is INIT/INIT-ACK look inside the chunk too. */
if (ch->type == SCTP_CID_INIT || ch->type == SCTP_CID_INIT_ACK)
return __sctp_rcv_init_lookup(net, skb, laddr, transportp, dif, sdif);
return __sctp_rcv_walk_lookup(net, skb, laddr, transportp, dif, sdif);
}
/* Lookup an association for an inbound skb. */
static struct sctp_association *__sctp_rcv_lookup(struct net *net,
struct sk_buff *skb,
const union sctp_addr *paddr,
const union sctp_addr *laddr,
struct sctp_transport **transportp,
int dif, int sdif)
{
struct sctp_association *asoc;
asoc = __sctp_lookup_association(net, laddr, paddr, transportp, dif, sdif);
if (asoc)
goto out;
/* Further lookup for INIT/INIT-ACK packets.
* SCTP Implementors Guide, 2.18 Handling of address
* parameters within the INIT or INIT-ACK.
*/
asoc = __sctp_rcv_lookup_harder(net, skb, laddr, transportp, dif, sdif);
if (asoc)
goto out;
if (paddr->sa.sa_family == AF_INET)
pr_debug("sctp: asoc not found for src:%pI4:%d dst:%pI4:%d\n",
&laddr->v4.sin_addr, ntohs(laddr->v4.sin_port),
&paddr->v4.sin_addr, ntohs(paddr->v4.sin_port));
else
pr_debug("sctp: asoc not found for src:%pI6:%d dst:%pI6:%d\n",
&laddr->v6.sin6_addr, ntohs(laddr->v6.sin6_port),
&paddr->v6.sin6_addr, ntohs(paddr->v6.sin6_port));
out:
return asoc;
}
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