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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/sha.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>
#endif
#include <net/mptcp.h>
#include "protocol.h"
#include "mib.h"
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 int subflow_rebuild_header(struct sock *sk)
{
struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
int local_id, err = 0;
if (subflow->request_mptcp && !subflow->token) {
pr_debug("subflow=%p", sk);
err = mptcp_token_new_connect(sk);
} else if (subflow->request_join && !subflow->local_nonce) {
struct mptcp_sock *msk = (struct mptcp_sock *)subflow->conn;
pr_debug("subflow=%p", sk);
do {
get_random_bytes(&subflow->local_nonce, sizeof(u32));
} while (!subflow->local_nonce);
if (subflow->local_id)
goto out;
local_id = mptcp_pm_get_local_id(msk, (struct sock_common *)sk);
if (local_id < 0)
return -EINVAL;
subflow->local_id = local_id;
}
out:
if (err)
return err;
return subflow->icsk_af_ops->rebuild_header(sk);
}
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);
if (subflow_req->mp_capable)
mptcp_token_destroy_request(subflow_req->token);
tcp_request_sock_ops.destructor(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);
}
/* validate received token and create truncated hmac and nonce for SYN-ACK */
static struct mptcp_sock *subflow_token_join_request(struct request_sock *req,
const struct sk_buff *skb)
{
struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
u8 hmac[SHA256_DIGEST_SIZE];
struct mptcp_sock *msk;
int local_id;
msk = mptcp_token_get_sock(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;
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);
return msk;
}
static void subflow_init_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;
pr_debug("subflow_req=%p, listener=%p", subflow_req, listener);
mptcp_get_options(skb, &mp_opt);
subflow_req->mp_capable = 0;
subflow_req->mp_join = 0;
subflow_req->msk = NULL;
#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;
#endif
if (mp_opt.mp_capable) {
SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_MPCAPABLEPASSIVE);
if (mp_opt.mp_join)
return;
} else if (mp_opt.mp_join) {
SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINSYNRX);
}
if (mp_opt.mp_capable && listener->request_mptcp) {
int err;
err = mptcp_token_new_request(req);
if (err == 0)
subflow_req->mp_capable = 1;
subflow_req->ssn_offset = TCP_SKB_CB(skb)->seq;
} else if (mp_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, skb);
pr_debug("token=%u, remote_nonce=%u msk=%p", subflow_req->token,
subflow_req->remote_nonce, subflow_req->msk);
}
}
static void subflow_v4_init_req(struct request_sock *req,
const struct sock *sk_listener,
struct sk_buff *skb)
{
tcp_rsk(req)->is_mptcp = 1;
tcp_request_sock_ipv4_ops.init_req(req, sk_listener, skb);
subflow_init_req(req, sk_listener, skb);
}
#if IS_ENABLED(CONFIG_MPTCP_IPV6)
static void subflow_v6_init_req(struct request_sock *req,
const struct sock *sk_listener,
struct sk_buff *skb)
{
tcp_rsk(req)->is_mptcp = 1;
tcp_request_sock_ipv6_ops.init_req(req, sk_listener, skb);
subflow_init_req(req, sk_listener, skb);
}
#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,
(unsigned long long)thmac,
(unsigned long long)subflow->thmac);
return thmac == subflow->thmac;
}
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 tcp_sock *tp = tcp_sk(sk);
subflow->icsk_af_ops->sk_rx_dst_set(sk, skb);
if (inet_sk_state_load(parent) == TCP_SYN_SENT) {
inet_sk_state_store(parent, TCP_ESTABLISHED);
parent->sk_state_change(parent);
}
/* be sure no special action on any packet other than syn-ack */
if (subflow->conn_finished)
return;
subflow->conn_finished = 1;
mptcp_get_options(skb, &mp_opt);
if (subflow->request_mptcp && mp_opt.mp_capable) {
subflow->mp_capable = 1;
subflow->can_ack = 1;
subflow->remote_key = mp_opt.sndr_key;
pr_debug("subflow=%p, remote_key=%llu", subflow,
subflow->remote_key);
} else if (subflow->request_join && mp_opt.mp_join) {
subflow->mp_join = 1;
subflow->thmac = mp_opt.thmac;
subflow->remote_nonce = mp_opt.nonce;
pr_debug("subflow=%p, thmac=%llu, remote_nonce=%u", subflow,
subflow->thmac, subflow->remote_nonce);
} else if (subflow->request_mptcp) {
tp->is_mptcp = 0;
}
if (!tp->is_mptcp)
return;
if (subflow->mp_capable) {
pr_debug("subflow=%p, remote_key=%llu", mptcp_subflow_ctx(sk),
subflow->remote_key);
mptcp_finish_connect(sk);
if (skb) {
pr_debug("synack seq=%u", TCP_SKB_CB(skb)->seq);
subflow->ssn_offset = TCP_SKB_CB(skb)->seq;
}
} else if (subflow->mp_join) {
u8 hmac[SHA256_DIGEST_SIZE];
pr_debug("subflow=%p, thmac=%llu, remote_nonce=%u",
subflow, subflow->thmac,
subflow->remote_nonce);
if (!subflow_thmac_valid(subflow)) {
MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_JOINACKMAC);
subflow->mp_join = 0;
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);
if (skb)
subflow->ssn_offset = TCP_SKB_CB(skb)->seq;
if (!mptcp_finish_join(sk))
goto do_reset;
MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_JOINSYNACKRX);
} else {
do_reset:
tcp_send_active_reset(sk, GFP_ATOMIC);
tcp_done(sk);
}
}
static struct request_sock_ops subflow_request_sock_ops;
static struct tcp_request_sock_ops subflow_request_sock_ipv4_ops;
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(&subflow_request_sock_ops,
&subflow_request_sock_ipv4_ops,
sk, skb);
drop:
tcp_listendrop(sk);
return 0;
}
#if IS_ENABLED(CONFIG_MPTCP_IPV6)
static struct tcp_request_sock_ops subflow_request_sock_ipv6_ops;
static struct inet_connection_sock_af_ops subflow_v6_specific;
static struct inet_connection_sock_af_ops subflow_v6m_specific;
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;
return tcp_conn_request(&subflow_request_sock_ops,
&subflow_request_sock_ipv6_ops, sk, skb);
drop:
tcp_listendrop(sk);
return 0; /* don't send reset */
}
#endif
/* 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 mptcp_sock_destruct(struct sock *sk)
{
/* if new mptcp socket isn't accepted, it is free'd
* from the tcp listener sockets request queue, linked
* from req->sk. The tcp socket is released.
* This calls the ULP release function which will
* also remove the mptcp socket, via
* sock_put(ctx->conn).
*
* Problem is that the mptcp socket will not be in
* SYN_RECV state and doesn't have SOCK_DEAD flag.
* Both result in warnings from inet_sock_destruct.
*/
if (sk->sk_state == TCP_SYN_RECV) {
sk->sk_state = TCP_CLOSE;
WARN_ON_ONCE(sk->sk_socket);
sock_orphan(sk);
}
mptcp_token_destroy(mptcp_sk(sk)->token);
inet_sock_destruct(sk);
}
static void mptcp_force_close(struct sock *sk)
{
inet_sk_state_store(sk, TCP_CLOSE);
sk_common_release(sk);
}
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;
}
static void subflow_drop_ctx(struct sock *ssk)
{
struct mptcp_subflow_context *ctx = mptcp_subflow_ctx(ssk);
if (!ctx)
return;
subflow_ulp_fallback(ssk, ctx);
if (ctx->conn)
sock_put(ctx->conn);
kfree_rcu(ctx, rcu);
}
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 sock *new_msk = NULL;
struct sock *child;
pr_debug("listener=%p, req=%p, conn=%p", listener, req, listener->conn);
/* After child creation we must look for 'mp_capable' even when options
* are not parsed
*/
mp_opt.mp_capable = 0;
/* hopefully temporary handling for MP_JOIN+syncookie */
subflow_req = mptcp_subflow_rsk(req);
fallback_is_fatal = 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) {
if (TCP_SKB_CB(skb)->seq != subflow_req->ssn_offset + 1) {
/* here we can receive and accept an in-window,
* out-of-order pkt, which will not carry the MP_CAPABLE
* opt even on mptcp enabled paths
*/
goto create_msk;
}
mptcp_get_options(skb, &mp_opt);
if (!mp_opt.mp_capable) {
fallback = true;
goto create_child;
}
create_msk:
new_msk = mptcp_sk_clone(listener->conn, &mp_opt, req);
if (!new_msk)
fallback = true;
} else if (subflow_req->mp_join) {
mptcp_get_options(skb, &mp_opt);
if (!mp_opt.mp_join ||
!subflow_hmac_valid(req, &mp_opt)) {
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)
goto dispose_child;
subflow_drop_ctx(child);
goto out;
}
if (ctx->mp_capable) {
/* new mpc subflow takes ownership of the newly
* created mptcp socket
*/
new_msk->sk_destruct = mptcp_sock_destruct;
mptcp_pm_new_connection(mptcp_sk(new_msk), 1);
ctx->conn = new_msk;
new_msk = NULL;
/* with OoO packets we can reach here without ingress
* mpc option
*/
ctx->remote_key = mp_opt.sndr_key;
ctx->fully_established = mp_opt.mp_capable;
ctx->can_ack = mp_opt.mp_capable;
} else if (ctx->mp_join) {
struct mptcp_sock *owner;
owner = subflow_req->msk;
if (!owner)
goto dispose_child;
/* move the msk reference ownership to the subflow */
subflow_req->msk = NULL;
ctx->conn = (struct sock *)owner;
if (!mptcp_finish_join(child))
goto dispose_child;
SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINACKRX);
tcp_rsk(req)->drop_req = true;
}
}
out:
/* dispose of the left over mptcp master, if any */
if (unlikely(new_msk))
mptcp_force_close(new_msk);
/* 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:
subflow_drop_ctx(child);
tcp_rsk(req)->drop_req = true;
tcp_send_active_reset(child, GFP_ATOMIC);
inet_csk_prepare_for_destroy_sock(child);
tcp_done(child);
/* The last child reference will be released by the caller */
return child;
}
static struct inet_connection_sock_af_ops subflow_specific;
enum mapping_status {
MAPPING_OK,
MAPPING_INVALID,
MAPPING_EMPTY,
MAPPING_DATA_FIN
};
static u64 expand_seq(u64 old_seq, u16 old_data_len, u64 seq)
{
if ((u32)seq == (u32)old_seq)
return old_seq;
/* Assume map covers data not mapped yet. */
return seq | ((old_seq + old_data_len + 1) & GENMASK_ULL(63, 32));
}
static void warn_bad_map(struct mptcp_subflow_context *subflow, u32 ssn)
{
WARN_ONCE(1, "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.
*/
warn_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 */
warn_bad_map(subflow, ssn + skb->len);
return false;
}
return true;
}
static enum mapping_status get_mapping_status(struct sock *ssk)
{
struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk);
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;
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;
}
pr_debug("seq=%llu is64=%d ssn=%u data_len=%u data_fin=%d",
mpext->data_seq, mpext->dsn64, mpext->subflow_seq,
mpext->data_len, mpext->data_fin);
data_len = mpext->data_len;
if (data_len == 0) {
pr_err("Infinite mapping not handled");
MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_INFINITEMAPRX);
return MAPPING_INVALID;
}
if (mpext->data_fin == 1) {
if (data_len == 1) {
pr_debug("DATA_FIN with no payload");
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 {
return MAPPING_DATA_FIN;
}
}
/* Adjust for DATA_FIN using 1 byte of sequence space */
data_len--;
}
if (!mpext->dsn64) {
map_seq = expand_seq(subflow->map_seq, subflow->map_data_len,
mpext->data_seq);
subflow->use_64bit_ack = 0;
pr_debug("expanded seq=%llu", subflow->map_seq);
} else {
map_seq = mpext->data_seq;
subflow->use_64bit_ack = 1;
}
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) {
skb_ext_del(skb, SKB_EXT_MPTCP);
return MAPPING_OK;
}
/* 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 */
return MAPPING_OK;
}
subflow->map_seq = map_seq;
subflow->map_subflow_seq = mpext->subflow_seq;
subflow->map_data_len = data_len;
subflow->map_valid = 1;
subflow->mpc_map = mpext->mpc_map;
pr_debug("new map seq=%llu subflow_seq=%u data_len=%u",
subflow->map_seq, subflow->map_subflow_seq,
subflow->map_data_len);
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))
return MAPPING_INVALID;
skb_ext_del(skb, SKB_EXT_MPTCP);
return MAPPING_OK;
}
static int subflow_read_actor(read_descriptor_t *desc,
struct sk_buff *skb,
unsigned int offset, size_t len)
{
size_t copy_len = min(desc->count, len);
desc->count -= copy_len;
pr_debug("flushed %zu bytes, %zu left", copy_len, desc->count);
return copy_len;
}
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;
pr_debug("msk=%p ssk=%p data_avail=%d skb=%p", subflow->conn, ssk,
subflow->data_avail, skb_peek(&ssk->sk_receive_queue));
if (subflow->data_avail)
return true;
msk = mptcp_sk(subflow->conn);
for (;;) {
u32 map_remaining;
size_t delta;
u64 ack_seq;
u64 old_ack;
status = get_mapping_status(ssk);
pr_debug("msk=%p ssk=%p status=%d", msk, ssk, status);
if (status == MAPPING_INVALID) {
ssk->sk_err = EBADMSG;
goto fatal;
}
if (status != MAPPING_OK)
return false;
skb = skb_peek(&ssk->sk_receive_queue);
if (WARN_ON_ONCE(!skb))
return false;
/* if msk lacks the remote key, this subflow must provide an
* MP_CAPABLE-based mapping
*/
if (unlikely(!READ_ONCE(msk->can_ack))) {
if (!subflow->mpc_map) {
ssk->sk_err = EBADMSG;
goto fatal;
}
WRITE_ONCE(msk->remote_key, subflow->remote_key);
WRITE_ONCE(msk->ack_seq, subflow->map_seq);
WRITE_ONCE(msk->can_ack, true);
}
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 (ack_seq == old_ack)
break;
/* only accept in-sequence mapping. Old values are spurious
* retransmission; we can hit "future" values on active backup
* subflow switch, we relay on retransmissions to get
* in-sequence data.
* Cuncurrent subflows support will require subflow data
* reordering
*/
map_remaining = subflow->map_data_len -
mptcp_subflow_get_map_offset(subflow);
if (before64(ack_seq, old_ack))
delta = min_t(size_t, old_ack - ack_seq, map_remaining);
else
delta = min_t(size_t, ack_seq - old_ack, map_remaining);
/* discard mapped data */
pr_debug("discarding %zu bytes, current map len=%d", delta,
map_remaining);
if (delta) {
read_descriptor_t desc = {
.count = delta,
};
int ret;
ret = tcp_read_sock(ssk, &desc, subflow_read_actor);
if (ret < 0) {
ssk->sk_err = -ret;
goto fatal;
}
if (ret < delta)
return false;
if (delta == map_remaining)
subflow->map_valid = 0;
}
}
return true;
fatal:
/* fatal protocol error, close the socket */
/* This barrier is coupled with smp_rmb() in tcp_poll() */
smp_wmb();
ssk->sk_error_report(ssk);
tcp_set_state(ssk, TCP_CLOSE);
tcp_send_active_reset(ssk, GFP_ATOMIC);
return false;
}
bool mptcp_subflow_data_available(struct sock *sk)
{
struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
struct sk_buff *skb;
/* 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;
subflow->data_avail = 0;
pr_debug("Done with mapping: seq=%u data_len=%u",
subflow->map_subflow_seq,
subflow->map_data_len);
}
if (!subflow_check_data_avail(sk)) {
subflow->data_avail = 0;
return false;
}
skb = skb_peek(&sk->sk_receive_queue);
subflow->data_avail = skb &&
before(tcp_sk(sk)->copied_seq, TCP_SKB_CB(skb)->end_seq);
return subflow->data_avail;
}
/* 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 concerened 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 = tcp_space(sk);
*full_space = tcp_full_space(sk);
}
static void subflow_data_ready(struct sock *sk)
{
struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
struct sock *parent = subflow->conn;
if (!subflow->mp_capable && !subflow->mp_join) {
subflow->tcp_data_ready(sk);
parent->sk_data_ready(parent);
return;
}
if (mptcp_subflow_data_available(sk))
mptcp_data_ready(parent, sk);
}
static void subflow_write_space(struct sock *sk)
{
struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
struct sock *parent = subflow->conn;
sk_stream_write_space(sk);
if (sk_stream_is_writeable(sk)) {
set_bit(MPTCP_SEND_SPACE, &mptcp_sk(parent)->flags);
smp_mb__after_atomic();
/* set SEND_SPACE before sk_stream_write_space clears NOSPACE */
sk_stream_write_space(parent);
}
}
static 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);
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
static void mptcp_info2sockaddr(const struct mptcp_addr_info *info,
struct sockaddr_storage *addr)
{
memset(addr, 0, sizeof(*addr));
addr->ss_family = info->family;
if (addr->ss_family == AF_INET) {
struct sockaddr_in *in_addr = (struct sockaddr_in *)addr;
in_addr->sin_addr = info->addr;
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;
in6_addr->sin6_addr = info->addr6;
in6_addr->sin6_port = info->port;
}
#endif
}
int __mptcp_subflow_connect(struct sock *sk, int ifindex,
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;
struct socket *sf;
u32 remote_token;
int addrlen;
int err;
if (sk->sk_state != TCP_ESTABLISHED)
return -ENOTCONN;
err = mptcp_subflow_create_socket(sk, &sf);
if (err)
return err;
subflow = mptcp_subflow_ctx(sf->sk);
subflow->remote_key = msk->remote_key;
subflow->local_key = msk->local_key;
subflow->token = msk->token;
mptcp_info2sockaddr(loc, &addr);
addrlen = sizeof(struct sockaddr_in);
#if IS_ENABLED(CONFIG_MPTCP_IPV6)
if (loc->family == AF_INET6)
addrlen = sizeof(struct sockaddr_in6);
#endif
sf->sk->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", msk, remote_token);
subflow->remote_token = remote_token;
subflow->local_id = loc->id;
subflow->request_join = 1;
subflow->request_bkup = 1;
mptcp_info2sockaddr(remote, &addr);
err = kernel_connect(sf, (struct sockaddr *)&addr, addrlen, O_NONBLOCK);
if (err && err != -EINPROGRESS)
goto failed;
spin_lock_bh(&msk->join_list_lock);
list_add_tail(&subflow->node, &msk->join_list);
spin_unlock_bh(&msk->join_list_lock);
return err;
failed:
sock_release(sf);
return err;
}
int mptcp_subflow_create_socket(struct sock *sk, struct socket **new_sock)
{
struct mptcp_subflow_context *subflow;
struct net *net = sock_net(sk);
struct socket *sf;
int err;
err = sock_create_kern(net, sk->sk_family, SOCK_STREAM, IPPROTO_TCP,
&sf);
if (err)
return err;
lock_sock(sf->sk);
/* kernel sockets do not by default acquire net ref, but TCP timer
* needs it.
*/
sf->sk->sk_net_refcnt = 1;
get_net(net);
#ifdef CONFIG_PROC_FS
this_cpu_add(*net->core.sock_inuse, 1);
#endif
err = tcp_set_ulp(sf->sk, "mptcp");
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 interaces 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;
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);
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;
__subflow_state_change(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 (subflow->mp_capable && mptcp_subflow_data_available(sk))
mptcp_data_ready(parent, sk);
if (!(parent->sk_shutdown & RCV_SHUTDOWN) &&
!subflow->rx_eof && subflow_is_done(sk)) {
subflow->rx_eof = 1;
mptcp_subflow_eof(parent);
}
}
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_data_ready = sk->sk_data_ready;
ctx->tcp_state_change = sk->sk_state_change;
ctx->tcp_write_space = sk->sk_write_space;
sk->sk_data_ready = subflow_data_ready;
sk->sk_write_space = subflow_write_space;
sk->sk_state_change = subflow_state_change;
out:
return err;
}
static void subflow_ulp_release(struct sock *sk)
{
struct mptcp_subflow_context *ctx = mptcp_subflow_ctx(sk);
if (!ctx)
return;
if (ctx->conn)
sock_put(ctx->conn);
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_data_ready = old_ctx->tcp_data_ready;
new_ctx->tcp_state_change = old_ctx->tcp_state_change;
new_ctx->tcp_write_space = old_ctx->tcp_write_space;
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;
} 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->backup = subflow_req->backup;
new_ctx->local_id = subflow_req->local_id;
new_ctx->token = subflow_req->token;
new_ctx->thmac = subflow_req->thmac;
}
}
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_name = "request_sock_subflow";
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;
subflow_ops->destructor = subflow_req_destructor;
return 0;
}
void __init mptcp_subflow_init(void)
{
subflow_request_sock_ops = tcp_request_sock_ops;
if (subflow_ops_init(&subflow_request_sock_ops) != 0)
panic("MPTCP: failed to init subflow request sock ops\n");
subflow_request_sock_ipv4_ops = tcp_request_sock_ipv4_ops;
subflow_request_sock_ipv4_ops.init_req = subflow_v4_init_req;
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;
#if IS_ENABLED(CONFIG_MPTCP_IPV6)
subflow_request_sock_ipv6_ops = tcp_request_sock_ipv6_ops;
subflow_request_sock_ipv6_ops.init_req = subflow_v6_init_req;
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_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;
#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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