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linux-zen-desktop/net/mptcp/subflow.c

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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/algapi.h>
#include <crypto/sha2.h>
#include <net/sock.h>
#include <net/inet_common.h>
#include <net/inet_hashtables.h>
#include <net/protocol.h>
#include <net/tcp.h>
#if IS_ENABLED(CONFIG_MPTCP_IPV6)
#include <net/ip6_route.h>
#include <net/transp_v6.h>
#endif
#include <net/mptcp.h>
#include <uapi/linux/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", 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(msk->local_key, 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;
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", 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))
return -EINVAL;
#endif
mptcp_get_options(skb, &mp_opt);
opt_mp_capable = !!(mp_opt.suboptions & OPTIONS_MPTCP_MPC);
opt_mp_join = !!(mp_opt.suboptions & OPTIONS_MPTCP_MPJ);
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 (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",
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);
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_init_req_cookie_join_save(subflow_req, skb);
else
return -EPERM;
}
pr_debug("token=%u, remote_nonce=%u msk=%p", 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 & OPTIONS_MPTCP_MPC);
opt_mp_join = !!(mp_opt.suboptions & OPTIONS_MPTCP_MPJ);
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 struct dst_entry *subflow_v4_route_req(const struct sock *sk,
struct sk_buff *skb,
struct flowi *fl,
struct request_sock *req)
{
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);
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);
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)
{
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);
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);
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);
tcp_send_active_reset(ssk, GFP_ATOMIC);
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_set_connected(struct sock *sk)
{
if (sk->sk_state == TCP_SYN_SENT) {
inet_sk_state_store(sk, TCP_ESTABLISHED);
sk->sk_state_change(sk);
}
}
static void mptcp_set_connected(struct sock *sk)
{
mptcp_data_lock(sk);
if (!sock_owned_by_user(sk))
__mptcp_set_connected(sk);
else
__set_bit(MPTCP_CONNECTED, &mptcp_sk(sk)->cb_flags);
mptcp_data_unlock(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 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);
mptcp_propagate_sndbuf(parent, sk);
subflow->rel_write_seq = 1;
subflow->conn_finished = 1;
subflow->ssn_offset = TCP_SKB_CB(skb)->seq;
pr_debug("subflow=%p synack seq=%x", subflow, subflow->ssn_offset);
mptcp_get_options(skb, &mp_opt);
if (subflow->request_mptcp) {
if (!(mp_opt.suboptions & OPTIONS_MPTCP_MPC)) {
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;
subflow_set_remote_key(msk, subflow, &mp_opt);
MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPCAPABLEACTIVEACK);
mptcp_finish_connect(sk);
mptcp_set_connected(parent);
} else if (subflow->request_join) {
u8 hmac[SHA256_DIGEST_SIZE];
if (!(mp_opt.suboptions & OPTIONS_MPTCP_MPJ)) {
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;
subflow->remote_id = mp_opt.join_id;
pr_debug("subflow=%p, thmac=%llu, remote_nonce=%u backup=%d",
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_use_different_dport(msk, sk)) {
pr_debug("synack inet_dport=%d %d",
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)) {
fallback:
mptcp_rcv_space_init(msk, sk);
mptcp_set_connected(parent);
}
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)
{
subflow->local_id = local_id;
subflow->local_id_valid = 1;
}
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_valid))
return 0;
err = mptcp_pm_get_local_id(msk, (struct sock_common *)sk);
if (err < 0)
return err;
subflow_set_local_id(subflow, err);
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", 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", 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(msk->remote_key, 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_subflow_context *subflow,
const struct mptcp_options_received *mp_opt)
{
struct mptcp_sock *msk = mptcp_sk(subflow->conn);
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;
struct mptcp_sock *owner;
struct sock *child;
pr_debug("listener=%p, req=%p, conn=%p", 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 & OPTIONS_MPTCP_MPC))
fallback = true;
} else if (subflow_req->mp_join) {
mptcp_get_options(skb, &mp_opt);
if (!(mp_opt.suboptions & OPTIONS_MPTCP_MPJ) ||
!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_subflow_fully_established(ctx, &mp_opt);
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",
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);
goto dispose_child;
}
SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINPORTACKRX);
}
if (!mptcp_finish_join(child))
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 eariler 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);
req->rsk_ops->send_reset(sk, skb);
/* The last child reference will be released by the caller */
return child;
fallback:
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",
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");
MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_INFINITEMAPRX);
subflow->map_data_len = 0;
return MAPPING_INVALID;
}
if (mpext->data_fin == 1) {
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", 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;
} else {
if (updated)
mptcp_schedule_work((struct sock *)msk);
return MAPPING_DATA_FIN;
}
} else {
u64 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",
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",
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;
u32 incr;
incr = limit >= skb->len ? skb->len + fin : limit;
pr_debug("discarding=%d len=%d seq=%d", incr, skb->len,
subflow->map_subflow_seq);
MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_DUPDATA);
tcp_sk(ssk)->copied_seq += incr;
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)
{
if (likely(ssk->sk_state != TCP_CLOSE))
return;
if (skb_queue_empty(&ssk->sk_receive_queue) &&
!test_and_set_bit(MPTCP_WORK_CLOSE_SUBFLOW, &msk->flags))
mptcp_schedule_work((struct sock *)msk);
}
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;
/* greceful 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_timeout(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, MPTCP_SUBFLOW_NODATA);
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", 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, MPTCP_SUBFLOW_DATA_AVAIL);
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, MPTCP_SUBFLOW_DATA_AVAIL);
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);
tcp_send_active_reset(ssk, GFP_ATOMIC);
WRITE_ONCE(subflow->data_avail, MPTCP_SUBFLOW_NODATA);
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, MPTCP_SUBFLOW_DATA_AVAIL);
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, MPTCP_SUBFLOW_NODATA);
pr_debug("Done with mapping: seq=%u data_len=%u",
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 = tcp_full_space(sk);
}
void __mptcp_error_report(struct sock *sk)
{
struct mptcp_subflow_context *subflow;
struct mptcp_sock *msk = mptcp_sk(sk);
mptcp_for_each_subflow(msk, subflow) {
struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
int err = sock_error(ssk);
int ssk_state;
if (!err)
continue;
/* only propagate errors on fallen-back sockets or
* on MPC connect
*/
if (sk->sk_state != TCP_SYN_SENT && !__mptcp_check_fallback(msk))
continue;
/* We need to propagate only transition to CLOSE state.
* Orphaned socket will see such state change via
* subflow_sched_work_if_closed() and that path will properly
* destroy the msk as needed.
*/
ssk_state = inet_sk_state_load(ssk);
if (ssk_state == TCP_CLOSE && !sock_flag(sk, SOCK_DEAD))
inet_sk_state_store(sk, ssk_state);
WRITE_ONCE(sk->sk_err, -err);
/* This barrier is coupled with smp_rmb() in mptcp_poll() */
smp_wmb();
sk_error_report(sk);
break;
}
}
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);
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",
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_addr_info *loc,
const struct mptcp_addr_info *remote)
{
struct mptcp_sock *msk = mptcp_sk(sk);
struct mptcp_subflow_context *subflow;
struct sockaddr_storage addr;
int remote_id = remote->id;
int local_id = loc->id;
int err = -ENOTCONN;
struct socket *sf;
struct sock *ssk;
u32 remote_token;
int addrlen;
int ifindex;
u8 flags;
if (!mptcp_is_fully_established(sk))
goto err_out;
err = mptcp_subflow_create_socket(sk, loc->family, &sf);
if (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 (local_id)
subflow_set_local_id(subflow, local_id);
mptcp_pm_get_flags_and_ifindex_by_id(msk, local_id,
&flags, &ifindex);
subflow->remote_key_valid = 1;
subflow->remote_key = msk->remote_key;
subflow->local_key = msk->local_key;
subflow->token = msk->token;
mptcp_info2sockaddr(loc, &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
mptcp_sockopt_sync(msk, ssk);
ssk->sk_bound_dev_if = ifindex;
err = kernel_bind(sf, (struct sockaddr *)&addr, addrlen);
if (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", msk,
remote_token, local_id, remote_id);
subflow->remote_token = remote_token;
subflow->remote_id = remote_id;
subflow->request_join = 1;
subflow->request_bkup = !!(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)
goto failed_unlink;
/* discard the subflow socket */
mptcp_sock_graft(ssk, sk->sk_socket);
iput(SOCK_INODE(sf));
WRITE_ONCE(msk->allow_infinite_fallback, false);
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 release_ssk;
/* 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");
release_ssk:
release_sock(sf->sk);
if (err) {
sock_release(sf);
return err;
}
/* the newly created socket really belongs to the owning MPTCP master
* 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", subflow);
*new_sock = sf;
sock_hold(sk);
subflow->conn = sk;
mptcp_subflow_ops_override(sf->sk);
return 0;
}
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", ctx);
ctx->tcp_sock = sk;
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_propagate_sndbuf(parent, sk);
mptcp_do_fallback(sk);
mptcp_rcv_space_init(msk, sk);
pr_fallback(msk);
subflow->conn_finished = 1;
mptcp_set_connected(parent);
}
/* 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", 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 */
new_ctx->local_id_valid = 1;
} 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->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);
if (mptcp_subflow_has_delegated_action(subflow))
mptcp_subflow_process_delegated(ssk);
tcp_release_cb(ssk);
}
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;
#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.net_frag_header_len = 0;
subflow_v6m_specific.rebuild_header = subflow_rebuild_header;
tcpv6_prot_override = tcpv6_prot;
tcpv6_prot_override.release_cb = tcp_release_cb_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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