diff options
Diffstat (limited to 'net/mptcp/subflow.c')
| -rw-r--r-- | net/mptcp/subflow.c | 2077 |
1 files changed, 2077 insertions, 0 deletions
diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c new file mode 100644 index 000000000..d3c5ecf8d --- /dev/null +++ b/net/mptcp/subflow.c @@ -0,0 +1,2077 @@ +// 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 & 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 (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 & 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 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_sync_state(struct sock *sk, int state) +{ + struct mptcp_sock *msk = mptcp_sk(sk); + + __mptcp_propagate_sndbuf(sk, msk->first); + if (sk->sk_state == TCP_SYN_SENT) { + inet_sk_state_store(sk, state); + sk->sk_state_change(sk); + } +} + +static void mptcp_propagate_state(struct sock *sk, struct sock *ssk) +{ + struct mptcp_sock *msk = mptcp_sk(sk); + + mptcp_data_lock(sk); + 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_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); + 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 & 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; + subflow_set_remote_key(msk, subflow, &mp_opt); + MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPCAPABLEACTIVEACK); + mptcp_finish_connect(sk); + mptcp_propagate_state(parent, sk); + } 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; + 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_propagate_state(parent, sk); + } + 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 & + (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_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_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, 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 = 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); + 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); + 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 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_do_fallback(sk); + mptcp_rcv_space_init(msk, sk); + pr_fallback(msk); + subflow->conn_finished = 1; + mptcp_propagate_state(parent, sk); + } + + /* 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); + 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.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; + 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"); +} |