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27069e7cb3
linux/net/mptcp/subflow.c
Matthieu Baerts (NGI0) 27069e7cb3 mptcp: disable active MPTCP in case of blackhole 
An MPTCP firewall blackhole can be detected if the following SYN
retransmission after a fallback to "plain" TCP is accepted.

In case of blackhole, a similar technique to the one in place with TFO
is now used: MPTCP can be disabled for a certain period of time, 1h by
default. This time period will grow exponentially when more blackhole
issues get detected right after MPTCP is re-enabled and will reset to
the initial value when the blackhole issue goes away.

The blackhole period can be modified thanks to a new sysctl knob:
blackhole_timeout. Two new MIB counters help understanding what's
happening:

- 'Blackhole', incremented when a blackhole is detected.
- 'MPCapableSYNTXDisabled', incremented when an MPTCP connection
  directly falls back to TCP during the blackhole period.

Because the technique is inspired by the one used by TFO, an important
part of the new code is similar to what can find in tcp_fastopen.c, with
some adaptations to the MPTCP case.

Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/57
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20240909-net-next-mptcp-fallback-x-mpc-v1-3-da7ebb4cd2a3@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2024-09-11 15:57:50 -07:00

2182 lines
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// SPDX-License-Identifier: GPL-2.0
/* Multipath TCP
*
* Copyright (c) 2017 - 2019, Intel Corporation.
*/
#define pr_fmt(fmt) "MPTCP: " fmt
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/netdevice.h>
#include <crypto/sha2.h>
#include <crypto/utils.h>
#include <net/sock.h>
#include <net/inet_common.h>
#include <net/inet_hashtables.h>
#include <net/protocol.h>
#if IS_ENABLED(CONFIG_MPTCP_IPV6)
#include <net/ip6_route.h>
#include <net/transp_v6.h>
#endif
#include <net/mptcp.h>
#include "protocol.h"
#include "mib.h"
#include <trace/events/mptcp.h>
#include <trace/events/sock.h>
static void mptcp_subflow_ops_undo_override(struct sock *ssk);
static void SUBFLOW_REQ_INC_STATS(struct request_sock *req,
enum linux_mptcp_mib_field field)
{
MPTCP_INC_STATS(sock_net(req_to_sk(req)), field);
}
static void subflow_req_destructor(struct request_sock *req)
{
struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
pr_debug("subflow_req=%p\n", subflow_req);
if (subflow_req->msk)
sock_put((struct sock *)subflow_req->msk);
mptcp_token_destroy_request(req);
}
static void subflow_generate_hmac(u64 key1, u64 key2, u32 nonce1, u32 nonce2,
void *hmac)
{
u8 msg[8];
put_unaligned_be32(nonce1, &msg[0]);
put_unaligned_be32(nonce2, &msg[4]);
mptcp_crypto_hmac_sha(key1, key2, msg, 8, hmac);
}
static bool mptcp_can_accept_new_subflow(const struct mptcp_sock *msk)
{
return mptcp_is_fully_established((void *)msk) &&
((mptcp_pm_is_userspace(msk) &&
mptcp_userspace_pm_active(msk)) ||
READ_ONCE(msk->pm.accept_subflow));
}
/* validate received token and create truncated hmac and nonce for SYN-ACK */
static void subflow_req_create_thmac(struct mptcp_subflow_request_sock *subflow_req)
{
struct mptcp_sock *msk = subflow_req->msk;
u8 hmac[SHA256_DIGEST_SIZE];
get_random_bytes(&subflow_req->local_nonce, sizeof(u32));
subflow_generate_hmac(READ_ONCE(msk->local_key),
READ_ONCE(msk->remote_key),
subflow_req->local_nonce,
subflow_req->remote_nonce, hmac);
subflow_req->thmac = get_unaligned_be64(hmac);
}
static struct mptcp_sock *subflow_token_join_request(struct request_sock *req)
{
struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
struct mptcp_sock *msk;
int local_id;
msk = mptcp_token_get_sock(sock_net(req_to_sk(req)), subflow_req->token);
if (!msk) {
SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINNOTOKEN);
return NULL;
}
local_id = mptcp_pm_get_local_id(msk, (struct sock_common *)req);
if (local_id < 0) {
sock_put((struct sock *)msk);
return NULL;
}
subflow_req->local_id = local_id;
subflow_req->request_bkup = mptcp_pm_is_backup(msk, (struct sock_common *)req);
return msk;
}
static void subflow_init_req(struct request_sock *req, const struct sock *sk_listener)
{
struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
subflow_req->mp_capable = 0;
subflow_req->mp_join = 0;
subflow_req->csum_reqd = mptcp_is_checksum_enabled(sock_net(sk_listener));
subflow_req->allow_join_id0 = mptcp_allow_join_id0(sock_net(sk_listener));
subflow_req->msk = NULL;
mptcp_token_init_request(req);
}
static bool subflow_use_different_sport(struct mptcp_sock *msk, const struct sock *sk)
{
return inet_sk(sk)->inet_sport != inet_sk((struct sock *)msk)->inet_sport;
}
static void subflow_add_reset_reason(struct sk_buff *skb, u8 reason)
{
struct mptcp_ext *mpext = skb_ext_add(skb, SKB_EXT_MPTCP);
if (mpext) {
memset(mpext, 0, sizeof(*mpext));
mpext->reset_reason = reason;
}
}
/* Init mptcp request socket.
*
* Returns an error code if a JOIN has failed and a TCP reset
* should be sent.
*/
static int subflow_check_req(struct request_sock *req,
const struct sock *sk_listener,
struct sk_buff *skb)
{
struct mptcp_subflow_context *listener = mptcp_subflow_ctx(sk_listener);
struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
struct mptcp_options_received mp_opt;
bool opt_mp_capable, opt_mp_join;
pr_debug("subflow_req=%p, listener=%p\n", subflow_req, listener);
#ifdef CONFIG_TCP_MD5SIG
/* no MPTCP if MD5SIG is enabled on this socket or we may run out of
* TCP option space.
*/
if (rcu_access_pointer(tcp_sk(sk_listener)->md5sig_info)) {
subflow_add_reset_reason(skb, MPTCP_RST_EMPTCP);
return -EINVAL;
}
#endif
mptcp_get_options(skb, &mp_opt);
opt_mp_capable = !!(mp_opt.suboptions & OPTION_MPTCP_MPC_SYN);
opt_mp_join = !!(mp_opt.suboptions & OPTION_MPTCP_MPJ_SYN);
if (opt_mp_capable) {
SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_MPCAPABLEPASSIVE);
if (opt_mp_join)
return 0;
} else if (opt_mp_join) {
SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINSYNRX);
if (mp_opt.backup)
SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINSYNBACKUPRX);
}
if (opt_mp_capable && listener->request_mptcp) {
int err, retries = MPTCP_TOKEN_MAX_RETRIES;
subflow_req->ssn_offset = TCP_SKB_CB(skb)->seq;
again:
do {
get_random_bytes(&subflow_req->local_key, sizeof(subflow_req->local_key));
} while (subflow_req->local_key == 0);
if (unlikely(req->syncookie)) {
mptcp_crypto_key_sha(subflow_req->local_key,
&subflow_req->token,
&subflow_req->idsn);
if (mptcp_token_exists(subflow_req->token)) {
if (retries-- > 0)
goto again;
SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_TOKENFALLBACKINIT);
} else {
subflow_req->mp_capable = 1;
}
return 0;
}
err = mptcp_token_new_request(req);
if (err == 0)
subflow_req->mp_capable = 1;
else if (retries-- > 0)
goto again;
else
SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_TOKENFALLBACKINIT);
} else if (opt_mp_join && listener->request_mptcp) {
subflow_req->ssn_offset = TCP_SKB_CB(skb)->seq;
subflow_req->mp_join = 1;
subflow_req->backup = mp_opt.backup;
subflow_req->remote_id = mp_opt.join_id;
subflow_req->token = mp_opt.token;
subflow_req->remote_nonce = mp_opt.nonce;
subflow_req->msk = subflow_token_join_request(req);
/* Can't fall back to TCP in this case. */
if (!subflow_req->msk) {
subflow_add_reset_reason(skb, MPTCP_RST_EMPTCP);
return -EPERM;
}
if (subflow_use_different_sport(subflow_req->msk, sk_listener)) {
pr_debug("syn inet_sport=%d %d\n",
ntohs(inet_sk(sk_listener)->inet_sport),
ntohs(inet_sk((struct sock *)subflow_req->msk)->inet_sport));
if (!mptcp_pm_sport_in_anno_list(subflow_req->msk, sk_listener)) {
SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_MISMATCHPORTSYNRX);
subflow_add_reset_reason(skb, MPTCP_RST_EPROHIBIT);
return -EPERM;
}
SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINPORTSYNRX);
}
subflow_req_create_thmac(subflow_req);
if (unlikely(req->syncookie)) {
if (!mptcp_can_accept_new_subflow(subflow_req->msk)) {
subflow_add_reset_reason(skb, MPTCP_RST_EPROHIBIT);
return -EPERM;
}
subflow_init_req_cookie_join_save(subflow_req, skb);
}
pr_debug("token=%u, remote_nonce=%u msk=%p\n", subflow_req->token,
subflow_req->remote_nonce, subflow_req->msk);
}
return 0;
}
int mptcp_subflow_init_cookie_req(struct request_sock *req,
const struct sock *sk_listener,
struct sk_buff *skb)
{
struct mptcp_subflow_context *listener = mptcp_subflow_ctx(sk_listener);
struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
struct mptcp_options_received mp_opt;
bool opt_mp_capable, opt_mp_join;
int err;
subflow_init_req(req, sk_listener);
mptcp_get_options(skb, &mp_opt);
opt_mp_capable = !!(mp_opt.suboptions & OPTION_MPTCP_MPC_ACK);
opt_mp_join = !!(mp_opt.suboptions & OPTION_MPTCP_MPJ_ACK);
if (opt_mp_capable && opt_mp_join)
return -EINVAL;
if (opt_mp_capable && listener->request_mptcp) {
if (mp_opt.sndr_key == 0)
return -EINVAL;
subflow_req->local_key = mp_opt.rcvr_key;
err = mptcp_token_new_request(req);
if (err)
return err;
subflow_req->mp_capable = 1;
subflow_req->ssn_offset = TCP_SKB_CB(skb)->seq - 1;
} else if (opt_mp_join && listener->request_mptcp) {
if (!mptcp_token_join_cookie_init_state(subflow_req, skb))
return -EINVAL;
subflow_req->mp_join = 1;
subflow_req->ssn_offset = TCP_SKB_CB(skb)->seq - 1;
}
return 0;
}
EXPORT_SYMBOL_GPL(mptcp_subflow_init_cookie_req);
static enum sk_rst_reason mptcp_get_rst_reason(const struct sk_buff *skb)
{
const struct mptcp_ext *mpext = mptcp_get_ext(skb);
if (!mpext)
return SK_RST_REASON_NOT_SPECIFIED;
return sk_rst_convert_mptcp_reason(mpext->reset_reason);
}
static struct dst_entry *subflow_v4_route_req(const struct sock *sk,
struct sk_buff *skb,
struct flowi *fl,
struct request_sock *req,
u32 tw_isn)
{
struct dst_entry *dst;
int err;
tcp_rsk(req)->is_mptcp = 1;
subflow_init_req(req, sk);
dst = tcp_request_sock_ipv4_ops.route_req(sk, skb, fl, req, tw_isn);
if (!dst)
return NULL;
err = subflow_check_req(req, sk, skb);
if (err == 0)
return dst;
dst_release(dst);
if (!req->syncookie)
tcp_request_sock_ops.send_reset(sk, skb,
mptcp_get_rst_reason(skb));
return NULL;
}
static void subflow_prep_synack(const struct sock *sk, struct request_sock *req,
struct tcp_fastopen_cookie *foc,
enum tcp_synack_type synack_type)
{
struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
struct inet_request_sock *ireq = inet_rsk(req);
/* clear tstamp_ok, as needed depending on cookie */
if (foc && foc->len > -1)
ireq->tstamp_ok = 0;
if (synack_type == TCP_SYNACK_FASTOPEN)
mptcp_fastopen_subflow_synack_set_params(subflow, req);
}
static int subflow_v4_send_synack(const struct sock *sk, struct dst_entry *dst,
struct flowi *fl,
struct request_sock *req,
struct tcp_fastopen_cookie *foc,
enum tcp_synack_type synack_type,
struct sk_buff *syn_skb)
{
subflow_prep_synack(sk, req, foc, synack_type);
return tcp_request_sock_ipv4_ops.send_synack(sk, dst, fl, req, foc,
synack_type, syn_skb);
}
#if IS_ENABLED(CONFIG_MPTCP_IPV6)
static int subflow_v6_send_synack(const struct sock *sk, struct dst_entry *dst,
struct flowi *fl,
struct request_sock *req,
struct tcp_fastopen_cookie *foc,
enum tcp_synack_type synack_type,
struct sk_buff *syn_skb)
{
subflow_prep_synack(sk, req, foc, synack_type);
return tcp_request_sock_ipv6_ops.send_synack(sk, dst, fl, req, foc,
synack_type, syn_skb);
}
static struct dst_entry *subflow_v6_route_req(const struct sock *sk,
struct sk_buff *skb,
struct flowi *fl,
struct request_sock *req,
u32 tw_isn)
{
struct dst_entry *dst;
int err;
tcp_rsk(req)->is_mptcp = 1;
subflow_init_req(req, sk);
dst = tcp_request_sock_ipv6_ops.route_req(sk, skb, fl, req, tw_isn);
if (!dst)
return NULL;
err = subflow_check_req(req, sk, skb);
if (err == 0)
return dst;
dst_release(dst);
if (!req->syncookie)
tcp6_request_sock_ops.send_reset(sk, skb,
mptcp_get_rst_reason(skb));
return NULL;
}
#endif
/* validate received truncated hmac and create hmac for third ACK */
static bool subflow_thmac_valid(struct mptcp_subflow_context *subflow)
{
u8 hmac[SHA256_DIGEST_SIZE];
u64 thmac;
subflow_generate_hmac(subflow->remote_key, subflow->local_key,
subflow->remote_nonce, subflow->local_nonce,
hmac);
thmac = get_unaligned_be64(hmac);
pr_debug("subflow=%p, token=%u, thmac=%llu, subflow->thmac=%llu\n",
subflow, subflow->token, thmac, subflow->thmac);
return thmac == subflow->thmac;
}
void mptcp_subflow_reset(struct sock *ssk)
{
struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
struct sock *sk = subflow->conn;
/* mptcp_mp_fail_no_response() can reach here on an already closed
* socket
*/
if (ssk->sk_state == TCP_CLOSE)
return;
/* must hold: tcp_done() could drop last reference on parent */
sock_hold(sk);
mptcp_send_active_reset_reason(ssk);
tcp_done(ssk);
if (!test_and_set_bit(MPTCP_WORK_CLOSE_SUBFLOW, &mptcp_sk(sk)->flags))
mptcp_schedule_work(sk);
sock_put(sk);
}
static bool subflow_use_different_dport(struct mptcp_sock *msk, const struct sock *sk)
{
return inet_sk(sk)->inet_dport != inet_sk((struct sock *)msk)->inet_dport;
}
void __mptcp_sync_state(struct sock *sk, int state)
{
struct mptcp_subflow_context *subflow;
struct mptcp_sock *msk = mptcp_sk(sk);
struct sock *ssk = msk->first;
subflow = mptcp_subflow_ctx(ssk);
__mptcp_propagate_sndbuf(sk, ssk);
if (!msk->rcvspace_init)
mptcp_rcv_space_init(msk, ssk);
if (sk->sk_state == TCP_SYN_SENT) {
/* subflow->idsn is always available is TCP_SYN_SENT state,
* even for the FASTOPEN scenarios
*/
WRITE_ONCE(msk->write_seq, subflow->idsn + 1);
WRITE_ONCE(msk->snd_nxt, msk->write_seq);
mptcp_set_state(sk, state);
sk->sk_state_change(sk);
}
}
static void subflow_set_remote_key(struct mptcp_sock *msk,
struct mptcp_subflow_context *subflow,
const struct mptcp_options_received *mp_opt)
{
/* active MPC subflow will reach here multiple times:
* at subflow_finish_connect() time and at 4th ack time
*/
if (subflow->remote_key_valid)
return;
subflow->remote_key_valid = 1;
subflow->remote_key = mp_opt->sndr_key;
mptcp_crypto_key_sha(subflow->remote_key, NULL, &subflow->iasn);
subflow->iasn++;
WRITE_ONCE(msk->remote_key, subflow->remote_key);
WRITE_ONCE(msk->ack_seq, subflow->iasn);
WRITE_ONCE(msk->can_ack, true);
atomic64_set(&msk->rcv_wnd_sent, subflow->iasn);
}
static void mptcp_propagate_state(struct sock *sk, struct sock *ssk,
struct mptcp_subflow_context *subflow,
const struct mptcp_options_received *mp_opt)
{
struct mptcp_sock *msk = mptcp_sk(sk);
mptcp_data_lock(sk);
if (mp_opt) {
/* Options are available only in the non fallback cases
* avoid updating rx path fields otherwise
*/
WRITE_ONCE(msk->snd_una, subflow->idsn + 1);
WRITE_ONCE(msk->wnd_end, subflow->idsn + 1 + tcp_sk(ssk)->snd_wnd);
subflow_set_remote_key(msk, subflow, mp_opt);
}
if (!sock_owned_by_user(sk)) {
__mptcp_sync_state(sk, ssk->sk_state);
} else {
msk->pending_state = ssk->sk_state;
__set_bit(MPTCP_SYNC_STATE, &msk->cb_flags);
}
mptcp_data_unlock(sk);
}
static void subflow_finish_connect(struct sock *sk, const struct sk_buff *skb)
{
struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
struct mptcp_options_received mp_opt;
struct sock *parent = subflow->conn;
struct mptcp_sock *msk;
subflow->icsk_af_ops->sk_rx_dst_set(sk, skb);
/* be sure no special action on any packet other than syn-ack */
if (subflow->conn_finished)
return;
msk = mptcp_sk(parent);
subflow->rel_write_seq = 1;
subflow->conn_finished = 1;
subflow->ssn_offset = TCP_SKB_CB(skb)->seq;
pr_debug("subflow=%p synack seq=%x\n", subflow, subflow->ssn_offset);
mptcp_get_options(skb, &mp_opt);
if (subflow->request_mptcp) {
if (!(mp_opt.suboptions & OPTION_MPTCP_MPC_SYNACK)) {
MPTCP_INC_STATS(sock_net(sk),
MPTCP_MIB_MPCAPABLEACTIVEFALLBACK);
mptcp_do_fallback(sk);
pr_fallback(msk);
goto fallback;
}
if (mp_opt.suboptions & OPTION_MPTCP_CSUMREQD)
WRITE_ONCE(msk->csum_enabled, true);
if (mp_opt.deny_join_id0)
WRITE_ONCE(msk->pm.remote_deny_join_id0, true);
subflow->mp_capable = 1;
MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPCAPABLEACTIVEACK);
mptcp_finish_connect(sk);
mptcp_active_enable(parent);
mptcp_propagate_state(parent, sk, subflow, &mp_opt);
} else if (subflow->request_join) {
u8 hmac[SHA256_DIGEST_SIZE];
if (!(mp_opt.suboptions & OPTION_MPTCP_MPJ_SYNACK)) {
subflow->reset_reason = MPTCP_RST_EMPTCP;
goto do_reset;
}
subflow->backup = mp_opt.backup;
subflow->thmac = mp_opt.thmac;
subflow->remote_nonce = mp_opt.nonce;
WRITE_ONCE(subflow->remote_id, mp_opt.join_id);
pr_debug("subflow=%p, thmac=%llu, remote_nonce=%u backup=%d\n",
subflow, subflow->thmac, subflow->remote_nonce,
subflow->backup);
if (!subflow_thmac_valid(subflow)) {
MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_JOINACKMAC);
subflow->reset_reason = MPTCP_RST_EMPTCP;
goto do_reset;
}
if (!mptcp_finish_join(sk))
goto do_reset;
subflow_generate_hmac(subflow->local_key, subflow->remote_key,
subflow->local_nonce,
subflow->remote_nonce,
hmac);
memcpy(subflow->hmac, hmac, MPTCPOPT_HMAC_LEN);
subflow->mp_join = 1;
MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_JOINSYNACKRX);
if (subflow->backup)
MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_JOINSYNACKBACKUPRX);
if (subflow_use_different_dport(msk, sk)) {
pr_debug("synack inet_dport=%d %d\n",
ntohs(inet_sk(sk)->inet_dport),
ntohs(inet_sk(parent)->inet_dport));
MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_JOINPORTSYNACKRX);
}
} else if (mptcp_check_fallback(sk)) {
/* It looks like MPTCP is blocked, while TCP is not */
if (subflow->mpc_drop)
mptcp_active_disable(parent);
fallback:
mptcp_propagate_state(parent, sk, subflow, NULL);
}
return;
do_reset:
subflow->reset_transient = 0;
mptcp_subflow_reset(sk);
}
static void subflow_set_local_id(struct mptcp_subflow_context *subflow, int local_id)
{
WARN_ON_ONCE(local_id < 0 || local_id > 255);
WRITE_ONCE(subflow->local_id, local_id);
}
static int subflow_chk_local_id(struct sock *sk)
{
struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
struct mptcp_sock *msk = mptcp_sk(subflow->conn);
int err;
if (likely(subflow->local_id >= 0))
return 0;
err = mptcp_pm_get_local_id(msk, (struct sock_common *)sk);
if (err < 0)
return err;
subflow_set_local_id(subflow, err);
subflow->request_bkup = mptcp_pm_is_backup(msk, (struct sock_common *)sk);
return 0;
}
static int subflow_rebuild_header(struct sock *sk)
{
int err = subflow_chk_local_id(sk);
if (unlikely(err < 0))
return err;
return inet_sk_rebuild_header(sk);
}
#if IS_ENABLED(CONFIG_MPTCP_IPV6)
static int subflow_v6_rebuild_header(struct sock *sk)
{
int err = subflow_chk_local_id(sk);
if (unlikely(err < 0))
return err;
return inet6_sk_rebuild_header(sk);
}
#endif
static struct request_sock_ops mptcp_subflow_v4_request_sock_ops __ro_after_init;
static struct tcp_request_sock_ops subflow_request_sock_ipv4_ops __ro_after_init;
static int subflow_v4_conn_request(struct sock *sk, struct sk_buff *skb)
{
struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
pr_debug("subflow=%p\n", subflow);
/* Never answer to SYNs sent to broadcast or multicast */
if (skb_rtable(skb)->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
goto drop;
return tcp_conn_request(&mptcp_subflow_v4_request_sock_ops,
&subflow_request_sock_ipv4_ops,
sk, skb);
drop:
tcp_listendrop(sk);
return 0;
}
static void subflow_v4_req_destructor(struct request_sock *req)
{
subflow_req_destructor(req);
tcp_request_sock_ops.destructor(req);
}
#if IS_ENABLED(CONFIG_MPTCP_IPV6)
static struct request_sock_ops mptcp_subflow_v6_request_sock_ops __ro_after_init;
static struct tcp_request_sock_ops subflow_request_sock_ipv6_ops __ro_after_init;
static struct inet_connection_sock_af_ops subflow_v6_specific __ro_after_init;
static struct inet_connection_sock_af_ops subflow_v6m_specific __ro_after_init;
static struct proto tcpv6_prot_override __ro_after_init;
static int subflow_v6_conn_request(struct sock *sk, struct sk_buff *skb)
{
struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
pr_debug("subflow=%p\n", subflow);
if (skb->protocol == htons(ETH_P_IP))
return subflow_v4_conn_request(sk, skb);
if (!ipv6_unicast_destination(skb))
goto drop;
if (ipv6_addr_v4mapped(&ipv6_hdr(skb)->saddr)) {
__IP6_INC_STATS(sock_net(sk), NULL, IPSTATS_MIB_INHDRERRORS);
return 0;
}
return tcp_conn_request(&mptcp_subflow_v6_request_sock_ops,
&subflow_request_sock_ipv6_ops, sk, skb);
drop:
tcp_listendrop(sk);
return 0; /* don't send reset */
}
static void subflow_v6_req_destructor(struct request_sock *req)
{
subflow_req_destructor(req);
tcp6_request_sock_ops.destructor(req);
}
#endif
struct request_sock *mptcp_subflow_reqsk_alloc(const struct request_sock_ops *ops,
struct sock *sk_listener,
bool attach_listener)
{
if (ops->family == AF_INET)
ops = &mptcp_subflow_v4_request_sock_ops;
#if IS_ENABLED(CONFIG_MPTCP_IPV6)
else if (ops->family == AF_INET6)
ops = &mptcp_subflow_v6_request_sock_ops;
#endif
return inet_reqsk_alloc(ops, sk_listener, attach_listener);
}
EXPORT_SYMBOL(mptcp_subflow_reqsk_alloc);
/* validate hmac received in third ACK */
static bool subflow_hmac_valid(const struct request_sock *req,
const struct mptcp_options_received *mp_opt)
{
const struct mptcp_subflow_request_sock *subflow_req;
u8 hmac[SHA256_DIGEST_SIZE];
struct mptcp_sock *msk;
subflow_req = mptcp_subflow_rsk(req);
msk = subflow_req->msk;
if (!msk)
return false;
subflow_generate_hmac(READ_ONCE(msk->remote_key),
READ_ONCE(msk->local_key),
subflow_req->remote_nonce,
subflow_req->local_nonce, hmac);
return !crypto_memneq(hmac, mp_opt->hmac, MPTCPOPT_HMAC_LEN);
}
static void subflow_ulp_fallback(struct sock *sk,
struct mptcp_subflow_context *old_ctx)
{
struct inet_connection_sock *icsk = inet_csk(sk);
mptcp_subflow_tcp_fallback(sk, old_ctx);
icsk->icsk_ulp_ops = NULL;
rcu_assign_pointer(icsk->icsk_ulp_data, NULL);
tcp_sk(sk)->is_mptcp = 0;
mptcp_subflow_ops_undo_override(sk);
}
void mptcp_subflow_drop_ctx(struct sock *ssk)
{
struct mptcp_subflow_context *ctx = mptcp_subflow_ctx(ssk);
if (!ctx)
return;
list_del(&mptcp_subflow_ctx(ssk)->node);
if (inet_csk(ssk)->icsk_ulp_ops) {
subflow_ulp_fallback(ssk, ctx);
if (ctx->conn)
sock_put(ctx->conn);
}
kfree_rcu(ctx, rcu);
}
void __mptcp_subflow_fully_established(struct mptcp_sock *msk,
struct mptcp_subflow_context *subflow,
const struct mptcp_options_received *mp_opt)
{
subflow_set_remote_key(msk, subflow, mp_opt);
subflow->fully_established = 1;
WRITE_ONCE(msk->fully_established, true);
if (subflow->is_mptfo)
__mptcp_fastopen_gen_msk_ackseq(msk, subflow, mp_opt);
}
static struct sock *subflow_syn_recv_sock(const struct sock *sk,
struct sk_buff *skb,
struct request_sock *req,
struct dst_entry *dst,
struct request_sock *req_unhash,
bool *own_req)
{
struct mptcp_subflow_context *listener = mptcp_subflow_ctx(sk);
struct mptcp_subflow_request_sock *subflow_req;
struct mptcp_options_received mp_opt;
bool fallback, fallback_is_fatal;
enum sk_rst_reason reason;
struct mptcp_sock *owner;
struct sock *child;
pr_debug("listener=%p, req=%p, conn=%p\n", listener, req, listener->conn);
/* After child creation we must look for MPC even when options
* are not parsed
*/
mp_opt.suboptions = 0;
/* hopefully temporary handling for MP_JOIN+syncookie */
subflow_req = mptcp_subflow_rsk(req);
fallback_is_fatal = tcp_rsk(req)->is_mptcp && subflow_req->mp_join;
fallback = !tcp_rsk(req)->is_mptcp;
if (fallback)
goto create_child;
/* if the sk is MP_CAPABLE, we try to fetch the client key */
if (subflow_req->mp_capable) {
/* we can receive and accept an in-window, out-of-order pkt,
* which may not carry the MP_CAPABLE opt even on mptcp enabled
* paths: always try to extract the peer key, and fallback
* for packets missing it.
* Even OoO DSS packets coming legitly after dropped or
* reordered MPC will cause fallback, but we don't have other
* options.
*/
mptcp_get_options(skb, &mp_opt);
if (!(mp_opt.suboptions &
(OPTION_MPTCP_MPC_SYN | OPTION_MPTCP_MPC_ACK)))
fallback = true;
} else if (subflow_req->mp_join) {
mptcp_get_options(skb, &mp_opt);
if (!(mp_opt.suboptions & OPTION_MPTCP_MPJ_ACK) ||
!subflow_hmac_valid(req, &mp_opt) ||
!mptcp_can_accept_new_subflow(subflow_req->msk)) {
SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINACKMAC);
fallback = true;
}
}
create_child:
child = listener->icsk_af_ops->syn_recv_sock(sk, skb, req, dst,
req_unhash, own_req);
if (child && *own_req) {
struct mptcp_subflow_context *ctx = mptcp_subflow_ctx(child);
tcp_rsk(req)->drop_req = false;
/* we need to fallback on ctx allocation failure and on pre-reqs
* checking above. In the latter scenario we additionally need
* to reset the context to non MPTCP status.
*/
if (!ctx || fallback) {
if (fallback_is_fatal) {
subflow_add_reset_reason(skb, MPTCP_RST_EMPTCP);
goto dispose_child;
}
goto fallback;
}
/* ssk inherits options of listener sk */
ctx->setsockopt_seq = listener->setsockopt_seq;
if (ctx->mp_capable) {
ctx->conn = mptcp_sk_clone_init(listener->conn, &mp_opt, child, req);
if (!ctx->conn)
goto fallback;
ctx->subflow_id = 1;
owner = mptcp_sk(ctx->conn);
mptcp_pm_new_connection(owner, child, 1);
/* with OoO packets we can reach here without ingress
* mpc option
*/
if (mp_opt.suboptions & OPTION_MPTCP_MPC_ACK) {
mptcp_pm_fully_established(owner, child);
ctx->pm_notified = 1;
}
} else if (ctx->mp_join) {
owner = subflow_req->msk;
if (!owner) {
subflow_add_reset_reason(skb, MPTCP_RST_EPROHIBIT);
goto dispose_child;
}
/* move the msk reference ownership to the subflow */
subflow_req->msk = NULL;
ctx->conn = (struct sock *)owner;
if (subflow_use_different_sport(owner, sk)) {
pr_debug("ack inet_sport=%d %d\n",
ntohs(inet_sk(sk)->inet_sport),
ntohs(inet_sk((struct sock *)owner)->inet_sport));
if (!mptcp_pm_sport_in_anno_list(owner, sk)) {
SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_MISMATCHPORTACKRX);
subflow_add_reset_reason(skb, MPTCP_RST_EPROHIBIT);
goto dispose_child;
}
SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINPORTACKRX);
}
if (!mptcp_finish_join(child)) {
struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(child);
subflow_add_reset_reason(skb, subflow->reset_reason);
goto dispose_child;
}
SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINACKRX);
tcp_rsk(req)->drop_req = true;
}
}
/* check for expected invariant - should never trigger, just help
* catching earlier subtle bugs
*/
WARN_ON_ONCE(child && *own_req && tcp_sk(child)->is_mptcp &&
(!mptcp_subflow_ctx(child) ||
!mptcp_subflow_ctx(child)->conn));
return child;
dispose_child:
mptcp_subflow_drop_ctx(child);
tcp_rsk(req)->drop_req = true;
inet_csk_prepare_for_destroy_sock(child);
tcp_done(child);
reason = mptcp_get_rst_reason(skb);
req->rsk_ops->send_reset(sk, skb, reason);
/* The last child reference will be released by the caller */
return child;
fallback:
if (fallback)
SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_MPCAPABLEPASSIVEFALLBACK);
mptcp_subflow_drop_ctx(child);
return child;
}
static struct inet_connection_sock_af_ops subflow_specific __ro_after_init;
static struct proto tcp_prot_override __ro_after_init;
enum mapping_status {
MAPPING_OK,
MAPPING_INVALID,
MAPPING_EMPTY,
MAPPING_DATA_FIN,
MAPPING_DUMMY,
MAPPING_BAD_CSUM
};
static void dbg_bad_map(struct mptcp_subflow_context *subflow, u32 ssn)
{
pr_debug("Bad mapping: ssn=%d map_seq=%d map_data_len=%d\n",
ssn, subflow->map_subflow_seq, subflow->map_data_len);
}
static bool skb_is_fully_mapped(struct sock *ssk, struct sk_buff *skb)
{
struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
unsigned int skb_consumed;
skb_consumed = tcp_sk(ssk)->copied_seq - TCP_SKB_CB(skb)->seq;
if (WARN_ON_ONCE(skb_consumed >= skb->len))
return true;
return skb->len - skb_consumed <= subflow->map_data_len -
mptcp_subflow_get_map_offset(subflow);
}
static bool validate_mapping(struct sock *ssk, struct sk_buff *skb)
{
struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
u32 ssn = tcp_sk(ssk)->copied_seq - subflow->ssn_offset;
if (unlikely(before(ssn, subflow->map_subflow_seq))) {
/* Mapping covers data later in the subflow stream,
* currently unsupported.
*/
dbg_bad_map(subflow, ssn);
return false;
}
if (unlikely(!before(ssn, subflow->map_subflow_seq +
subflow->map_data_len))) {
/* Mapping does covers past subflow data, invalid */
dbg_bad_map(subflow, ssn);
return false;
}
return true;
}
static enum mapping_status validate_data_csum(struct sock *ssk, struct sk_buff *skb,
bool csum_reqd)
{
struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
u32 offset, seq, delta;
__sum16 csum;
int len;
if (!csum_reqd)
return MAPPING_OK;
/* mapping already validated on previous traversal */
if (subflow->map_csum_len == subflow->map_data_len)
return MAPPING_OK;
/* traverse the receive queue, ensuring it contains a full
* DSS mapping and accumulating the related csum.
* Preserve the accoumlate csum across multiple calls, to compute
* the csum only once
*/
delta = subflow->map_data_len - subflow->map_csum_len;
for (;;) {
seq = tcp_sk(ssk)->copied_seq + subflow->map_csum_len;
offset = seq - TCP_SKB_CB(skb)->seq;
/* if the current skb has not been accounted yet, csum its contents
* up to the amount covered by the current DSS
*/
if (offset < skb->len) {
__wsum csum;
len = min(skb->len - offset, delta);
csum = skb_checksum(skb, offset, len, 0);
subflow->map_data_csum = csum_block_add(subflow->map_data_csum, csum,
subflow->map_csum_len);
delta -= len;
subflow->map_csum_len += len;
}
if (delta == 0)
break;
if (skb_queue_is_last(&ssk->sk_receive_queue, skb)) {
/* if this subflow is closed, the partial mapping
* will be never completed; flush the pending skbs, so
* that subflow_sched_work_if_closed() can kick in
*/
if (unlikely(ssk->sk_state == TCP_CLOSE))
while ((skb = skb_peek(&ssk->sk_receive_queue)))
sk_eat_skb(ssk, skb);
/* not enough data to validate the csum */
return MAPPING_EMPTY;
}
/* the DSS mapping for next skbs will be validated later,
* when a get_mapping_status call will process such skb
*/
skb = skb->next;
}
/* note that 'map_data_len' accounts only for the carried data, does
* not include the eventual seq increment due to the data fin,
* while the pseudo header requires the original DSS data len,
* including that
*/
csum = __mptcp_make_csum(subflow->map_seq,
subflow->map_subflow_seq,
subflow->map_data_len + subflow->map_data_fin,
subflow->map_data_csum);
if (unlikely(csum)) {
MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_DATACSUMERR);
return MAPPING_BAD_CSUM;
}
subflow->valid_csum_seen = 1;
return MAPPING_OK;
}
static enum mapping_status get_mapping_status(struct sock *ssk,
struct mptcp_sock *msk)
{
struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
bool csum_reqd = READ_ONCE(msk->csum_enabled);
struct mptcp_ext *mpext;
struct sk_buff *skb;
u16 data_len;
u64 map_seq;
skb = skb_peek(&ssk->sk_receive_queue);
if (!skb)
return MAPPING_EMPTY;
if (mptcp_check_fallback(ssk))
return MAPPING_DUMMY;
mpext = mptcp_get_ext(skb);
if (!mpext || !mpext->use_map) {
if (!subflow->map_valid && !skb->len) {
/* the TCP stack deliver 0 len FIN pkt to the receive
* queue, that is the only 0len pkts ever expected here,
* and we can admit no mapping only for 0 len pkts
*/
if (!(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN))
WARN_ONCE(1, "0len seq %d:%d flags %x",
TCP_SKB_CB(skb)->seq,
TCP_SKB_CB(skb)->end_seq,
TCP_SKB_CB(skb)->tcp_flags);
sk_eat_skb(ssk, skb);
return MAPPING_EMPTY;
}
if (!subflow->map_valid)
return MAPPING_INVALID;
goto validate_seq;
}
trace_get_mapping_status(mpext);
data_len = mpext->data_len;
if (data_len == 0) {
pr_debug("infinite mapping received\n");
MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_INFINITEMAPRX);
subflow->map_data_len = 0;
return MAPPING_INVALID;
}
if (mpext->data_fin == 1) {
u64 data_fin_seq;
if (data_len == 1) {
bool updated = mptcp_update_rcv_data_fin(msk, mpext->data_seq,
mpext->dsn64);
pr_debug("DATA_FIN with no payload seq=%llu\n", mpext->data_seq);
if (subflow->map_valid) {
/* A DATA_FIN might arrive in a DSS
* option before the previous mapping
* has been fully consumed. Continue
* handling the existing mapping.
*/
skb_ext_del(skb, SKB_EXT_MPTCP);
return MAPPING_OK;
}
if (updated)
mptcp_schedule_work((struct sock *)msk);
return MAPPING_DATA_FIN;
}
data_fin_seq = mpext->data_seq + data_len - 1;
/* If mpext->data_seq is a 32-bit value, data_fin_seq must also
* be limited to 32 bits.
*/
if (!mpext->dsn64)
data_fin_seq &= GENMASK_ULL(31, 0);
mptcp_update_rcv_data_fin(msk, data_fin_seq, mpext->dsn64);
pr_debug("DATA_FIN with mapping seq=%llu dsn64=%d\n",
data_fin_seq, mpext->dsn64);
/* Adjust for DATA_FIN using 1 byte of sequence space */
data_len--;
}
map_seq = mptcp_expand_seq(READ_ONCE(msk->ack_seq), mpext->data_seq, mpext->dsn64);
WRITE_ONCE(mptcp_sk(subflow->conn)->use_64bit_ack, !!mpext->dsn64);
if (subflow->map_valid) {
/* Allow replacing only with an identical map */
if (subflow->map_seq == map_seq &&
subflow->map_subflow_seq == mpext->subflow_seq &&
subflow->map_data_len == data_len &&
subflow->map_csum_reqd == mpext->csum_reqd) {
skb_ext_del(skb, SKB_EXT_MPTCP);
goto validate_csum;
}
/* If this skb data are fully covered by the current mapping,
* the new map would need caching, which is not supported
*/
if (skb_is_fully_mapped(ssk, skb)) {
MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_DSSNOMATCH);
return MAPPING_INVALID;
}
/* will validate the next map after consuming the current one */
goto validate_csum;
}
subflow->map_seq = map_seq;
subflow->map_subflow_seq = mpext->subflow_seq;
subflow->map_data_len = data_len;
subflow->map_valid = 1;
subflow->map_data_fin = mpext->data_fin;
subflow->mpc_map = mpext->mpc_map;
subflow->map_csum_reqd = mpext->csum_reqd;
subflow->map_csum_len = 0;
subflow->map_data_csum = csum_unfold(mpext->csum);
/* Cfr RFC 8684 Section 3.3.0 */
if (unlikely(subflow->map_csum_reqd != csum_reqd))
return MAPPING_INVALID;
pr_debug("new map seq=%llu subflow_seq=%u data_len=%u csum=%d:%u\n",
subflow->map_seq, subflow->map_subflow_seq,
subflow->map_data_len, subflow->map_csum_reqd,
subflow->map_data_csum);
validate_seq:
/* we revalidate valid mapping on new skb, because we must ensure
* the current skb is completely covered by the available mapping
*/
if (!validate_mapping(ssk, skb)) {
MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_DSSTCPMISMATCH);
return MAPPING_INVALID;
}
skb_ext_del(skb, SKB_EXT_MPTCP);
validate_csum:
return validate_data_csum(ssk, skb, csum_reqd);
}
static void mptcp_subflow_discard_data(struct sock *ssk, struct sk_buff *skb,
u64 limit)
{
struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
bool fin = TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN;
struct tcp_sock *tp = tcp_sk(ssk);
u32 offset, incr, avail_len;
offset = tp->copied_seq - TCP_SKB_CB(skb)->seq;
if (WARN_ON_ONCE(offset > skb->len))
goto out;
avail_len = skb->len - offset;
incr = limit >= avail_len ? avail_len + fin : limit;
pr_debug("discarding=%d len=%d offset=%d seq=%d\n", incr, skb->len,
offset, subflow->map_subflow_seq);
MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_DUPDATA);
tcp_sk(ssk)->copied_seq += incr;
out:
if (!before(tcp_sk(ssk)->copied_seq, TCP_SKB_CB(skb)->end_seq))
sk_eat_skb(ssk, skb);
if (mptcp_subflow_get_map_offset(subflow) >= subflow->map_data_len)
subflow->map_valid = 0;
}
/* sched mptcp worker to remove the subflow if no more data is pending */
static void subflow_sched_work_if_closed(struct mptcp_sock *msk, struct sock *ssk)
{
struct sock *sk = (struct sock *)msk;
if (likely(ssk->sk_state != TCP_CLOSE &&
(ssk->sk_state != TCP_CLOSE_WAIT ||
inet_sk_state_load(sk) != TCP_ESTABLISHED)))
return;
if (skb_queue_empty(&ssk->sk_receive_queue) &&
!test_and_set_bit(MPTCP_WORK_CLOSE_SUBFLOW, &msk->flags))
mptcp_schedule_work(sk);
}
static bool subflow_can_fallback(struct mptcp_subflow_context *subflow)
{
struct mptcp_sock *msk = mptcp_sk(subflow->conn);
if (subflow->mp_join)
return false;
else if (READ_ONCE(msk->csum_enabled))
return !subflow->valid_csum_seen;
else
return !subflow->fully_established;
}
static void mptcp_subflow_fail(struct mptcp_sock *msk, struct sock *ssk)
{
struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
unsigned long fail_tout;
/* graceful failure can happen only on the MPC subflow */
if (WARN_ON_ONCE(ssk != READ_ONCE(msk->first)))
return;
/* since the close timeout take precedence on the fail one,
* no need to start the latter when the first is already set
*/
if (sock_flag((struct sock *)msk, SOCK_DEAD))
return;
/* we don't need extreme accuracy here, use a zero fail_tout as special
* value meaning no fail timeout at all;
*/
fail_tout = jiffies + TCP_RTO_MAX;
if (!fail_tout)
fail_tout = 1;
WRITE_ONCE(subflow->fail_tout, fail_tout);
tcp_send_ack(ssk);
mptcp_reset_tout_timer(msk, subflow->fail_tout);
}
static bool subflow_check_data_avail(struct sock *ssk)
{
struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
enum mapping_status status;
struct mptcp_sock *msk;
struct sk_buff *skb;
if (!skb_peek(&ssk->sk_receive_queue))
WRITE_ONCE(subflow->data_avail, false);
if (subflow->data_avail)
return true;
msk = mptcp_sk(subflow->conn);
for (;;) {
u64 ack_seq;
u64 old_ack;
status = get_mapping_status(ssk, msk);
trace_subflow_check_data_avail(status, skb_peek(&ssk->sk_receive_queue));
if (unlikely(status == MAPPING_INVALID || status == MAPPING_DUMMY ||
status == MAPPING_BAD_CSUM))
goto fallback;
if (status != MAPPING_OK)
goto no_data;
skb = skb_peek(&ssk->sk_receive_queue);
if (WARN_ON_ONCE(!skb))
goto no_data;
if (unlikely(!READ_ONCE(msk->can_ack)))
goto fallback;
old_ack = READ_ONCE(msk->ack_seq);
ack_seq = mptcp_subflow_get_mapped_dsn(subflow);
pr_debug("msk ack_seq=%llx subflow ack_seq=%llx\n", old_ack,
ack_seq);
if (unlikely(before64(ack_seq, old_ack))) {
mptcp_subflow_discard_data(ssk, skb, old_ack - ack_seq);
continue;
}
WRITE_ONCE(subflow->data_avail, true);
break;
}
return true;
no_data:
subflow_sched_work_if_closed(msk, ssk);
return false;
fallback:
if (!__mptcp_check_fallback(msk)) {
/* RFC 8684 section 3.7. */
if (status == MAPPING_BAD_CSUM &&
(subflow->mp_join || subflow->valid_csum_seen)) {
subflow->send_mp_fail = 1;
if (!READ_ONCE(msk->allow_infinite_fallback)) {
subflow->reset_transient = 0;
subflow->reset_reason = MPTCP_RST_EMIDDLEBOX;
goto reset;
}
mptcp_subflow_fail(msk, ssk);
WRITE_ONCE(subflow->data_avail, true);
return true;
}
if (!subflow_can_fallback(subflow) && subflow->map_data_len) {
/* fatal protocol error, close the socket.
* subflow_error_report() will introduce the appropriate barriers
*/
subflow->reset_transient = 0;
subflow->reset_reason = MPTCP_RST_EMPTCP;
reset:
WRITE_ONCE(ssk->sk_err, EBADMSG);
tcp_set_state(ssk, TCP_CLOSE);
while ((skb = skb_peek(&ssk->sk_receive_queue)))
sk_eat_skb(ssk, skb);
mptcp_send_active_reset_reason(ssk);
WRITE_ONCE(subflow->data_avail, false);
return false;
}
mptcp_do_fallback(ssk);
}
skb = skb_peek(&ssk->sk_receive_queue);
subflow->map_valid = 1;
subflow->map_seq = READ_ONCE(msk->ack_seq);
subflow->map_data_len = skb->len;
subflow->map_subflow_seq = tcp_sk(ssk)->copied_seq - subflow->ssn_offset;
WRITE_ONCE(subflow->data_avail, true);
return true;
}
bool mptcp_subflow_data_available(struct sock *sk)
{
struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
/* check if current mapping is still valid */
if (subflow->map_valid &&
mptcp_subflow_get_map_offset(subflow) >= subflow->map_data_len) {
subflow->map_valid = 0;
WRITE_ONCE(subflow->data_avail, false);
pr_debug("Done with mapping: seq=%u data_len=%u\n",
subflow->map_subflow_seq,
subflow->map_data_len);
}
return subflow_check_data_avail(sk);
}
/* If ssk has an mptcp parent socket, use the mptcp rcvbuf occupancy,
* not the ssk one.
*
* In mptcp, rwin is about the mptcp-level connection data.
*
* Data that is still on the ssk rx queue can thus be ignored,
* as far as mptcp peer is concerned that data is still inflight.
* DSS ACK is updated when skb is moved to the mptcp rx queue.
*/
void mptcp_space(const struct sock *ssk, int *space, int *full_space)
{
const struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
const struct sock *sk = subflow->conn;
*space = __mptcp_space(sk);
*full_space = mptcp_win_from_space(sk, READ_ONCE(sk->sk_rcvbuf));
}
static void subflow_error_report(struct sock *ssk)
{
struct sock *sk = mptcp_subflow_ctx(ssk)->conn;
/* bail early if this is a no-op, so that we avoid introducing a
* problematic lockdep dependency between TCP accept queue lock
* and msk socket spinlock
*/
if (!sk->sk_socket)
return;
mptcp_data_lock(sk);
if (!sock_owned_by_user(sk))
__mptcp_error_report(sk);
else
__set_bit(MPTCP_ERROR_REPORT, &mptcp_sk(sk)->cb_flags);
mptcp_data_unlock(sk);
}
static void subflow_data_ready(struct sock *sk)
{
struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
u16 state = 1 << inet_sk_state_load(sk);
struct sock *parent = subflow->conn;
struct mptcp_sock *msk;
trace_sk_data_ready(sk);
msk = mptcp_sk(parent);
if (state & TCPF_LISTEN) {
/* MPJ subflow are removed from accept queue before reaching here,
* avoid stray wakeups
*/
if (reqsk_queue_empty(&inet_csk(sk)->icsk_accept_queue))
return;
parent->sk_data_ready(parent);
return;
}
WARN_ON_ONCE(!__mptcp_check_fallback(msk) && !subflow->mp_capable &&
!subflow->mp_join && !(state & TCPF_CLOSE));
if (mptcp_subflow_data_available(sk)) {
mptcp_data_ready(parent, sk);
/* subflow-level lowat test are not relevant.
* respect the msk-level threshold eventually mandating an immediate ack
*/
if (mptcp_data_avail(msk) < parent->sk_rcvlowat &&
(tcp_sk(sk)->rcv_nxt - tcp_sk(sk)->rcv_wup) > inet_csk(sk)->icsk_ack.rcv_mss)
inet_csk(sk)->icsk_ack.pending |= ICSK_ACK_NOW;
} else if (unlikely(sk->sk_err)) {
subflow_error_report(sk);
}
}
static void subflow_write_space(struct sock *ssk)
{
struct sock *sk = mptcp_subflow_ctx(ssk)->conn;
mptcp_propagate_sndbuf(sk, ssk);
mptcp_write_space(sk);
}
static const struct inet_connection_sock_af_ops *
subflow_default_af_ops(struct sock *sk)
{
#if IS_ENABLED(CONFIG_MPTCP_IPV6)
if (sk->sk_family == AF_INET6)
return &subflow_v6_specific;
#endif
return &subflow_specific;
}
#if IS_ENABLED(CONFIG_MPTCP_IPV6)
void mptcpv6_handle_mapped(struct sock *sk, bool mapped)
{
struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
struct inet_connection_sock *icsk = inet_csk(sk);
const struct inet_connection_sock_af_ops *target;
target = mapped ? &subflow_v6m_specific : subflow_default_af_ops(sk);
pr_debug("subflow=%p family=%d ops=%p target=%p mapped=%d\n",
subflow, sk->sk_family, icsk->icsk_af_ops, target, mapped);
if (likely(icsk->icsk_af_ops == target))
return;
subflow->icsk_af_ops = icsk->icsk_af_ops;
icsk->icsk_af_ops = target;
}
#endif
void mptcp_info2sockaddr(const struct mptcp_addr_info *info,
struct sockaddr_storage *addr,
unsigned short family)
{
memset(addr, 0, sizeof(*addr));
addr->ss_family = family;
if (addr->ss_family == AF_INET) {
struct sockaddr_in *in_addr = (struct sockaddr_in *)addr;
if (info->family == AF_INET)
in_addr->sin_addr = info->addr;
#if IS_ENABLED(CONFIG_MPTCP_IPV6)
else if (ipv6_addr_v4mapped(&info->addr6))
in_addr->sin_addr.s_addr = info->addr6.s6_addr32[3];
#endif
in_addr->sin_port = info->port;
}
#if IS_ENABLED(CONFIG_MPTCP_IPV6)
else if (addr->ss_family == AF_INET6) {
struct sockaddr_in6 *in6_addr = (struct sockaddr_in6 *)addr;
if (info->family == AF_INET)
ipv6_addr_set_v4mapped(info->addr.s_addr,
&in6_addr->sin6_addr);
else
in6_addr->sin6_addr = info->addr6;
in6_addr->sin6_port = info->port;
}
#endif
}
int __mptcp_subflow_connect(struct sock *sk, const struct mptcp_pm_local *local,
const struct mptcp_addr_info *remote)
{
struct mptcp_sock *msk = mptcp_sk(sk);
struct mptcp_subflow_context *subflow;
int local_id = local->addr.id;
struct sockaddr_storage addr;
int remote_id = remote->id;
int err = -ENOTCONN;
struct socket *sf;
struct sock *ssk;
u32 remote_token;
int addrlen;
/* The userspace PM sent the request too early? */
if (!mptcp_is_fully_established(sk))
goto err_out;
err = mptcp_subflow_create_socket(sk, local->addr.family, &sf);
if (err) {
MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_JOINSYNTXCREATSKERR);
pr_debug("msk=%p local=%d remote=%d create sock error: %d\n",
msk, local_id, remote_id, err);
goto err_out;
}
ssk = sf->sk;
subflow = mptcp_subflow_ctx(ssk);
do {
get_random_bytes(&subflow->local_nonce, sizeof(u32));
} while (!subflow->local_nonce);
/* if 'IPADDRANY', the ID will be set later, after the routing */
if (local->addr.family == AF_INET) {
if (!local->addr.addr.s_addr)
local_id = -1;
#if IS_ENABLED(CONFIG_MPTCP_IPV6)
} else if (sk->sk_family == AF_INET6) {
if (ipv6_addr_any(&local->addr.addr6))
local_id = -1;
#endif
}
if (local_id >= 0)
subflow_set_local_id(subflow, local_id);
subflow->remote_key_valid = 1;
subflow->remote_key = READ_ONCE(msk->remote_key);
subflow->local_key = READ_ONCE(msk->local_key);
subflow->token = msk->token;
mptcp_info2sockaddr(&local->addr, &addr, ssk->sk_family);
addrlen = sizeof(struct sockaddr_in);
#if IS_ENABLED(CONFIG_MPTCP_IPV6)
if (addr.ss_family == AF_INET6)
addrlen = sizeof(struct sockaddr_in6);
#endif
ssk->sk_bound_dev_if = local->ifindex;
err = kernel_bind(sf, (struct sockaddr *)&addr, addrlen);
if (err) {
MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_JOINSYNTXBINDERR);
pr_debug("msk=%p local=%d remote=%d bind error: %d\n",
msk, local_id, remote_id, err);
goto failed;
}
mptcp_crypto_key_sha(subflow->remote_key, &remote_token, NULL);
pr_debug("msk=%p remote_token=%u local_id=%d remote_id=%d\n", msk,
remote_token, local_id, remote_id);
subflow->remote_token = remote_token;
WRITE_ONCE(subflow->remote_id, remote_id);
subflow->request_join = 1;
subflow->request_bkup = !!(local->flags & MPTCP_PM_ADDR_FLAG_BACKUP);
subflow->subflow_id = msk->subflow_id++;
mptcp_info2sockaddr(remote, &addr, ssk->sk_family);
sock_hold(ssk);
list_add_tail(&subflow->node, &msk->conn_list);
err = kernel_connect(sf, (struct sockaddr *)&addr, addrlen, O_NONBLOCK);
if (err && err != -EINPROGRESS) {
MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_JOINSYNTXCONNECTERR);
pr_debug("msk=%p local=%d remote=%d connect error: %d\n",
msk, local_id, remote_id, err);
goto failed_unlink;
}
MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_JOINSYNTX);
/* discard the subflow socket */
mptcp_sock_graft(ssk, sk->sk_socket);
iput(SOCK_INODE(sf));
WRITE_ONCE(msk->allow_infinite_fallback, false);
mptcp_stop_tout_timer(sk);
return 0;
failed_unlink:
list_del(&subflow->node);
sock_put(mptcp_subflow_tcp_sock(subflow));
failed:
subflow->disposable = 1;
sock_release(sf);
err_out:
/* we account subflows before the creation, and this failures will not
* be caught by sk_state_change()
*/
mptcp_pm_close_subflow(msk);
return err;
}
static void mptcp_attach_cgroup(struct sock *parent, struct sock *child)
{
#ifdef CONFIG_SOCK_CGROUP_DATA
struct sock_cgroup_data *parent_skcd = &parent->sk_cgrp_data,
*child_skcd = &child->sk_cgrp_data;
/* only the additional subflows created by kworkers have to be modified */
if (cgroup_id(sock_cgroup_ptr(parent_skcd)) !=
cgroup_id(sock_cgroup_ptr(child_skcd))) {
#ifdef CONFIG_MEMCG
struct mem_cgroup *memcg = parent->sk_memcg;
mem_cgroup_sk_free(child);
if (memcg && css_tryget(&memcg->css))
child->sk_memcg = memcg;
#endif /* CONFIG_MEMCG */
cgroup_sk_free(child_skcd);
*child_skcd = *parent_skcd;
cgroup_sk_clone(child_skcd);
}
#endif /* CONFIG_SOCK_CGROUP_DATA */
}
static void mptcp_subflow_ops_override(struct sock *ssk)
{
#if IS_ENABLED(CONFIG_MPTCP_IPV6)
if (ssk->sk_prot == &tcpv6_prot)
ssk->sk_prot = &tcpv6_prot_override;
else
#endif
ssk->sk_prot = &tcp_prot_override;
}
static void mptcp_subflow_ops_undo_override(struct sock *ssk)
{
#if IS_ENABLED(CONFIG_MPTCP_IPV6)
if (ssk->sk_prot == &tcpv6_prot_override)
ssk->sk_prot = &tcpv6_prot;
else
#endif
ssk->sk_prot = &tcp_prot;
}
int mptcp_subflow_create_socket(struct sock *sk, unsigned short family,
struct socket **new_sock)
{
struct mptcp_subflow_context *subflow;
struct net *net = sock_net(sk);
struct socket *sf;
int err;
/* un-accepted server sockets can reach here - on bad configuration
* bail early to avoid greater trouble later
*/
if (unlikely(!sk->sk_socket))
return -EINVAL;
err = sock_create_kern(net, family, SOCK_STREAM, IPPROTO_TCP, &sf);
if (err)
return err;
lock_sock_nested(sf->sk, SINGLE_DEPTH_NESTING);
err = security_mptcp_add_subflow(sk, sf->sk);
if (err)
goto err_free;
/* the newly created socket has to be in the same cgroup as its parent */
mptcp_attach_cgroup(sk, sf->sk);
/* kernel sockets do not by default acquire net ref, but TCP timer
* needs it.
* Update ns_tracker to current stack trace and refcounted tracker.
*/
__netns_tracker_free(net, &sf->sk->ns_tracker, false);
sf->sk->sk_net_refcnt = 1;
get_net_track(net, &sf->sk->ns_tracker, GFP_KERNEL);
sock_inuse_add(net, 1);
err = tcp_set_ulp(sf->sk, "mptcp");
if (err)
goto err_free;
mptcp_sockopt_sync_locked(mptcp_sk(sk), sf->sk);
release_sock(sf->sk);
/* the newly created socket really belongs to the owning MPTCP
* socket, even if for additional subflows the allocation is performed
* by a kernel workqueue. Adjust inode references, so that the
* procfs/diag interfaces really show this one belonging to the correct
* user.
*/
SOCK_INODE(sf)->i_ino = SOCK_INODE(sk->sk_socket)->i_ino;
SOCK_INODE(sf)->i_uid = SOCK_INODE(sk->sk_socket)->i_uid;
SOCK_INODE(sf)->i_gid = SOCK_INODE(sk->sk_socket)->i_gid;
subflow = mptcp_subflow_ctx(sf->sk);
pr_debug("subflow=%p\n", subflow);
*new_sock = sf;
sock_hold(sk);
subflow->conn = sk;
mptcp_subflow_ops_override(sf->sk);
return 0;
err_free:
release_sock(sf->sk);
sock_release(sf);
return err;
}
static struct mptcp_subflow_context *subflow_create_ctx(struct sock *sk,
gfp_t priority)
{
struct inet_connection_sock *icsk = inet_csk(sk);
struct mptcp_subflow_context *ctx;
ctx = kzalloc(sizeof(*ctx), priority);
if (!ctx)
return NULL;
rcu_assign_pointer(icsk->icsk_ulp_data, ctx);
INIT_LIST_HEAD(&ctx->node);
INIT_LIST_HEAD(&ctx->delegated_node);
pr_debug("subflow=%p\n", ctx);
ctx->tcp_sock = sk;
WRITE_ONCE(ctx->local_id, -1);
return ctx;
}
static void __subflow_state_change(struct sock *sk)
{
struct socket_wq *wq;
rcu_read_lock();
wq = rcu_dereference(sk->sk_wq);
if (skwq_has_sleeper(wq))
wake_up_interruptible_all(&wq->wait);
rcu_read_unlock();
}
static bool subflow_is_done(const struct sock *sk)
{
return sk->sk_shutdown & RCV_SHUTDOWN || sk->sk_state == TCP_CLOSE;
}
static void subflow_state_change(struct sock *sk)
{
struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
struct sock *parent = subflow->conn;
struct mptcp_sock *msk;
__subflow_state_change(sk);
msk = mptcp_sk(parent);
if (subflow_simultaneous_connect(sk)) {
mptcp_do_fallback(sk);
pr_fallback(msk);
subflow->conn_finished = 1;
mptcp_propagate_state(parent, sk, subflow, NULL);
}
/* as recvmsg() does not acquire the subflow socket for ssk selection
* a fin packet carrying a DSS can be unnoticed if we don't trigger
* the data available machinery here.
*/
if (mptcp_subflow_data_available(sk))
mptcp_data_ready(parent, sk);
else if (unlikely(sk->sk_err))
subflow_error_report(sk);
subflow_sched_work_if_closed(mptcp_sk(parent), sk);
/* when the fallback subflow closes the rx side, trigger a 'dummy'
* ingress data fin, so that the msk state will follow along
*/
if (__mptcp_check_fallback(msk) && subflow_is_done(sk) && msk->first == sk &&
mptcp_update_rcv_data_fin(msk, READ_ONCE(msk->ack_seq), true))
mptcp_schedule_work(parent);
}
void mptcp_subflow_queue_clean(struct sock *listener_sk, struct sock *listener_ssk)
{
struct request_sock_queue *queue = &inet_csk(listener_ssk)->icsk_accept_queue;
struct request_sock *req, *head, *tail;
struct mptcp_subflow_context *subflow;
struct sock *sk, *ssk;
/* Due to lock dependencies no relevant lock can be acquired under rskq_lock.
* Splice the req list, so that accept() can not reach the pending ssk after
* the listener socket is released below.
*/
spin_lock_bh(&queue->rskq_lock);
head = queue->rskq_accept_head;
tail = queue->rskq_accept_tail;
queue->rskq_accept_head = NULL;
queue->rskq_accept_tail = NULL;
spin_unlock_bh(&queue->rskq_lock);
if (!head)
return;
/* can't acquire the msk socket lock under the subflow one,
* or will cause ABBA deadlock
*/
release_sock(listener_ssk);
for (req = head; req; req = req->dl_next) {
ssk = req->sk;
if (!sk_is_mptcp(ssk))
continue;
subflow = mptcp_subflow_ctx(ssk);
if (!subflow || !subflow->conn)
continue;
sk = subflow->conn;
sock_hold(sk);
lock_sock_nested(sk, SINGLE_DEPTH_NESTING);
__mptcp_unaccepted_force_close(sk);
release_sock(sk);
/* lockdep will report a false positive ABBA deadlock
* between cancel_work_sync and the listener socket.
* The involved locks belong to different sockets WRT
* the existing AB chain.
* Using a per socket key is problematic as key
* deregistration requires process context and must be
* performed at socket disposal time, in atomic
* context.
* Just tell lockdep to consider the listener socket
* released here.
*/
mutex_release(&listener_sk->sk_lock.dep_map, _RET_IP_);
mptcp_cancel_work(sk);
mutex_acquire(&listener_sk->sk_lock.dep_map, 0, 0, _RET_IP_);
sock_put(sk);
}
/* we are still under the listener msk socket lock */
lock_sock_nested(listener_ssk, SINGLE_DEPTH_NESTING);
/* restore the listener queue, to let the TCP code clean it up */
spin_lock_bh(&queue->rskq_lock);
WARN_ON_ONCE(queue->rskq_accept_head);
queue->rskq_accept_head = head;
queue->rskq_accept_tail = tail;
spin_unlock_bh(&queue->rskq_lock);
}
static int subflow_ulp_init(struct sock *sk)
{
struct inet_connection_sock *icsk = inet_csk(sk);
struct mptcp_subflow_context *ctx;
struct tcp_sock *tp = tcp_sk(sk);
int err = 0;
/* disallow attaching ULP to a socket unless it has been
* created with sock_create_kern()
*/
if (!sk->sk_kern_sock) {
err = -EOPNOTSUPP;
goto out;
}
ctx = subflow_create_ctx(sk, GFP_KERNEL);
if (!ctx) {
err = -ENOMEM;
goto out;
}
pr_debug("subflow=%p, family=%d\n", ctx, sk->sk_family);
tp->is_mptcp = 1;
ctx->icsk_af_ops = icsk->icsk_af_ops;
icsk->icsk_af_ops = subflow_default_af_ops(sk);
ctx->tcp_state_change = sk->sk_state_change;
ctx->tcp_error_report = sk->sk_error_report;
WARN_ON_ONCE(sk->sk_data_ready != sock_def_readable);
WARN_ON_ONCE(sk->sk_write_space != sk_stream_write_space);
sk->sk_data_ready = subflow_data_ready;
sk->sk_write_space = subflow_write_space;
sk->sk_state_change = subflow_state_change;
sk->sk_error_report = subflow_error_report;
out:
return err;
}
static void subflow_ulp_release(struct sock *ssk)
{
struct mptcp_subflow_context *ctx = mptcp_subflow_ctx(ssk);
bool release = true;
struct sock *sk;
if (!ctx)
return;
sk = ctx->conn;
if (sk) {
/* if the msk has been orphaned, keep the ctx
* alive, will be freed by __mptcp_close_ssk(),
* when the subflow is still unaccepted
*/
release = ctx->disposable || list_empty(&ctx->node);
/* inet_child_forget() does not call sk_state_change(),
* explicitly trigger the socket close machinery
*/
if (!release && !test_and_set_bit(MPTCP_WORK_CLOSE_SUBFLOW,
&mptcp_sk(sk)->flags))
mptcp_schedule_work(sk);
sock_put(sk);
}
mptcp_subflow_ops_undo_override(ssk);
if (release)
kfree_rcu(ctx, rcu);
}
static void subflow_ulp_clone(const struct request_sock *req,
struct sock *newsk,
const gfp_t priority)
{
struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
struct mptcp_subflow_context *old_ctx = mptcp_subflow_ctx(newsk);
struct mptcp_subflow_context *new_ctx;
if (!tcp_rsk(req)->is_mptcp ||
(!subflow_req->mp_capable && !subflow_req->mp_join)) {
subflow_ulp_fallback(newsk, old_ctx);
return;
}
new_ctx = subflow_create_ctx(newsk, priority);
if (!new_ctx) {
subflow_ulp_fallback(newsk, old_ctx);
return;
}
new_ctx->conn_finished = 1;
new_ctx->icsk_af_ops = old_ctx->icsk_af_ops;
new_ctx->tcp_state_change = old_ctx->tcp_state_change;
new_ctx->tcp_error_report = old_ctx->tcp_error_report;
new_ctx->rel_write_seq = 1;
new_ctx->tcp_sock = newsk;
if (subflow_req->mp_capable) {
/* see comments in subflow_syn_recv_sock(), MPTCP connection
* is fully established only after we receive the remote key
*/
new_ctx->mp_capable = 1;
new_ctx->local_key = subflow_req->local_key;
new_ctx->token = subflow_req->token;
new_ctx->ssn_offset = subflow_req->ssn_offset;
new_ctx->idsn = subflow_req->idsn;
/* this is the first subflow, id is always 0 */
subflow_set_local_id(new_ctx, 0);
} else if (subflow_req->mp_join) {
new_ctx->ssn_offset = subflow_req->ssn_offset;
new_ctx->mp_join = 1;
new_ctx->fully_established = 1;
new_ctx->remote_key_valid = 1;
new_ctx->backup = subflow_req->backup;
new_ctx->request_bkup = subflow_req->request_bkup;
WRITE_ONCE(new_ctx->remote_id, subflow_req->remote_id);
new_ctx->token = subflow_req->token;
new_ctx->thmac = subflow_req->thmac;
/* the subflow req id is valid, fetched via subflow_check_req()
* and subflow_token_join_request()
*/
subflow_set_local_id(new_ctx, subflow_req->local_id);
}
}
static void tcp_release_cb_override(struct sock *ssk)
{
struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
long status;
/* process and clear all the pending actions, but leave the subflow into
* the napi queue. To respect locking, only the same CPU that originated
* the action can touch the list. mptcp_napi_poll will take care of it.
*/
status = set_mask_bits(&subflow->delegated_status, MPTCP_DELEGATE_ACTIONS_MASK, 0);
if (status)
mptcp_subflow_process_delegated(ssk, status);
tcp_release_cb(ssk);
}
static int tcp_abort_override(struct sock *ssk, int err)
{
/* closing a listener subflow requires a great deal of care.
* keep it simple and just prevent such operation
*/
if (inet_sk_state_load(ssk) == TCP_LISTEN)
return -EINVAL;
return tcp_abort(ssk, err);
}
static struct tcp_ulp_ops subflow_ulp_ops __read_mostly = {
.name = "mptcp",
.owner = THIS_MODULE,
.init = subflow_ulp_init,
.release = subflow_ulp_release,
.clone = subflow_ulp_clone,
};
static int subflow_ops_init(struct request_sock_ops *subflow_ops)
{
subflow_ops->obj_size = sizeof(struct mptcp_subflow_request_sock);
subflow_ops->slab = kmem_cache_create(subflow_ops->slab_name,
subflow_ops->obj_size, 0,
SLAB_ACCOUNT |
SLAB_TYPESAFE_BY_RCU,
NULL);
if (!subflow_ops->slab)
return -ENOMEM;
return 0;
}
void __init mptcp_subflow_init(void)
{
mptcp_subflow_v4_request_sock_ops = tcp_request_sock_ops;
mptcp_subflow_v4_request_sock_ops.slab_name = "request_sock_subflow_v4";
mptcp_subflow_v4_request_sock_ops.destructor = subflow_v4_req_destructor;
if (subflow_ops_init(&mptcp_subflow_v4_request_sock_ops) != 0)
panic("MPTCP: failed to init subflow v4 request sock ops\n");
subflow_request_sock_ipv4_ops = tcp_request_sock_ipv4_ops;
subflow_request_sock_ipv4_ops.route_req = subflow_v4_route_req;
subflow_request_sock_ipv4_ops.send_synack = subflow_v4_send_synack;
subflow_specific = ipv4_specific;
subflow_specific.conn_request = subflow_v4_conn_request;
subflow_specific.syn_recv_sock = subflow_syn_recv_sock;
subflow_specific.sk_rx_dst_set = subflow_finish_connect;
subflow_specific.rebuild_header = subflow_rebuild_header;
tcp_prot_override = tcp_prot;
tcp_prot_override.release_cb = tcp_release_cb_override;
tcp_prot_override.diag_destroy = tcp_abort_override;
#if IS_ENABLED(CONFIG_MPTCP_IPV6)
/* In struct mptcp_subflow_request_sock, we assume the TCP request sock
* structures for v4 and v6 have the same size. It should not changed in
* the future but better to make sure to be warned if it is no longer
* the case.
*/
BUILD_BUG_ON(sizeof(struct tcp_request_sock) != sizeof(struct tcp6_request_sock));
mptcp_subflow_v6_request_sock_ops = tcp6_request_sock_ops;
mptcp_subflow_v6_request_sock_ops.slab_name = "request_sock_subflow_v6";
mptcp_subflow_v6_request_sock_ops.destructor = subflow_v6_req_destructor;
if (subflow_ops_init(&mptcp_subflow_v6_request_sock_ops) != 0)
panic("MPTCP: failed to init subflow v6 request sock ops\n");
subflow_request_sock_ipv6_ops = tcp_request_sock_ipv6_ops;
subflow_request_sock_ipv6_ops.route_req = subflow_v6_route_req;
subflow_request_sock_ipv6_ops.send_synack = subflow_v6_send_synack;
subflow_v6_specific = ipv6_specific;
subflow_v6_specific.conn_request = subflow_v6_conn_request;
subflow_v6_specific.syn_recv_sock = subflow_syn_recv_sock;
subflow_v6_specific.sk_rx_dst_set = subflow_finish_connect;
subflow_v6_specific.rebuild_header = subflow_v6_rebuild_header;
subflow_v6m_specific = subflow_v6_specific;
subflow_v6m_specific.queue_xmit = ipv4_specific.queue_xmit;
subflow_v6m_specific.send_check = ipv4_specific.send_check;
subflow_v6m_specific.net_header_len = ipv4_specific.net_header_len;
subflow_v6m_specific.mtu_reduced = ipv4_specific.mtu_reduced;
subflow_v6m_specific.rebuild_header = subflow_rebuild_header;
tcpv6_prot_override = tcpv6_prot;
tcpv6_prot_override.release_cb = tcp_release_cb_override;
tcpv6_prot_override.diag_destroy = tcp_abort_override;
#endif
mptcp_diag_subflow_init(&subflow_ulp_ops);
if (tcp_register_ulp(&subflow_ulp_ops) != 0)
panic("MPTCP: failed to register subflows to ULP\n");
}
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