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linux/net/mptcp/options.c
Paolo Abeni 38967f424b mptcp: track some aggregate data counters 
Currently there are no data transfer counters accounting for all
the subflows used by a given MPTCP socket. The user-space can compute
such figures aggregating the subflow info, but that is inaccurate
if any subflow is closed before the MPTCP socket itself.

Add the new counters in the MPTCP socket itself and expose them
via the existing diag and sockopt. While touching mptcp_diag_fill_info(),
acquire the relevant locks before fetching the msk data, to ensure
better data consistency

Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/385
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2023-06-21 22:45:57 -07:00

1652 lines
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// SPDX-License-Identifier: GPL-2.0
/* Multipath TCP
*
* Copyright (c) 2017 - 2019, Intel Corporation.
*/
#define pr_fmt(fmt) "MPTCP: " fmt
#include <linux/kernel.h>
#include <crypto/sha2.h>
#include <net/tcp.h>
#include <net/mptcp.h>
#include "protocol.h"
#include "mib.h"
#include <trace/events/mptcp.h>
static bool mptcp_cap_flag_sha256(u8 flags)
{
return (flags & MPTCP_CAP_FLAG_MASK) == MPTCP_CAP_HMAC_SHA256;
}
static void mptcp_parse_option(const struct sk_buff *skb,
const unsigned char *ptr, int opsize,
struct mptcp_options_received *mp_opt)
{
u8 subtype = *ptr >> 4;
int expected_opsize;
u16 subopt;
u8 version;
u8 flags;
u8 i;
switch (subtype) {
case MPTCPOPT_MP_CAPABLE:
/* strict size checking */
if (!(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN)) {
if (skb->len > tcp_hdr(skb)->doff << 2)
expected_opsize = TCPOLEN_MPTCP_MPC_ACK_DATA;
else
expected_opsize = TCPOLEN_MPTCP_MPC_ACK;
subopt = OPTION_MPTCP_MPC_ACK;
} else {
if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_ACK) {
expected_opsize = TCPOLEN_MPTCP_MPC_SYNACK;
subopt = OPTION_MPTCP_MPC_SYNACK;
} else {
expected_opsize = TCPOLEN_MPTCP_MPC_SYN;
subopt = OPTION_MPTCP_MPC_SYN;
}
}
/* Cfr RFC 8684 Section 3.3.0:
* If a checksum is present but its use had
* not been negotiated in the MP_CAPABLE handshake, the receiver MUST
* close the subflow with a RST, as it is not behaving as negotiated.
* If a checksum is not present when its use has been negotiated, the
* receiver MUST close the subflow with a RST, as it is considered
* broken
* We parse even option with mismatching csum presence, so that
* later in subflow_data_ready we can trigger the reset.
*/
if (opsize != expected_opsize &&
(expected_opsize != TCPOLEN_MPTCP_MPC_ACK_DATA ||
opsize != TCPOLEN_MPTCP_MPC_ACK_DATA_CSUM))
break;
/* try to be gentle vs future versions on the initial syn */
version = *ptr++ & MPTCP_VERSION_MASK;
if (opsize != TCPOLEN_MPTCP_MPC_SYN) {
if (version != MPTCP_SUPPORTED_VERSION)
break;
} else if (version < MPTCP_SUPPORTED_VERSION) {
break;
}
flags = *ptr++;
if (!mptcp_cap_flag_sha256(flags) ||
(flags & MPTCP_CAP_EXTENSIBILITY))
break;
/* RFC 6824, Section 3.1:
* "For the Checksum Required bit (labeled "A"), if either
* host requires the use of checksums, checksums MUST be used.
* In other words, the only way for checksums not to be used
* is if both hosts in their SYNs set A=0."
*/
if (flags & MPTCP_CAP_CHECKSUM_REQD)
mp_opt->suboptions |= OPTION_MPTCP_CSUMREQD;
mp_opt->deny_join_id0 = !!(flags & MPTCP_CAP_DENY_JOIN_ID0);
mp_opt->suboptions |= subopt;
if (opsize >= TCPOLEN_MPTCP_MPC_SYNACK) {
mp_opt->sndr_key = get_unaligned_be64(ptr);
ptr += 8;
}
if (opsize >= TCPOLEN_MPTCP_MPC_ACK) {
mp_opt->rcvr_key = get_unaligned_be64(ptr);
ptr += 8;
}
if (opsize >= TCPOLEN_MPTCP_MPC_ACK_DATA) {
/* Section 3.1.:
* "the data parameters in a MP_CAPABLE are semantically
* equivalent to those in a DSS option and can be used
* interchangeably."
*/
mp_opt->suboptions |= OPTION_MPTCP_DSS;
mp_opt->use_map = 1;
mp_opt->mpc_map = 1;
mp_opt->data_len = get_unaligned_be16(ptr);
ptr += 2;
}
if (opsize == TCPOLEN_MPTCP_MPC_ACK_DATA_CSUM) {
mp_opt->csum = get_unaligned((__force __sum16 *)ptr);
mp_opt->suboptions |= OPTION_MPTCP_CSUMREQD;
ptr += 2;
}
pr_debug("MP_CAPABLE version=%x, flags=%x, optlen=%d sndr=%llu, rcvr=%llu len=%d csum=%u",
version, flags, opsize, mp_opt->sndr_key,
mp_opt->rcvr_key, mp_opt->data_len, mp_opt->csum);
break;
case MPTCPOPT_MP_JOIN:
mp_opt->suboptions |= OPTIONS_MPTCP_MPJ;
if (opsize == TCPOLEN_MPTCP_MPJ_SYN) {
mp_opt->backup = *ptr++ & MPTCPOPT_BACKUP;
mp_opt->join_id = *ptr++;
mp_opt->token = get_unaligned_be32(ptr);
ptr += 4;
mp_opt->nonce = get_unaligned_be32(ptr);
ptr += 4;
pr_debug("MP_JOIN bkup=%u, id=%u, token=%u, nonce=%u",
mp_opt->backup, mp_opt->join_id,
mp_opt->token, mp_opt->nonce);
} else if (opsize == TCPOLEN_MPTCP_MPJ_SYNACK) {
mp_opt->backup = *ptr++ & MPTCPOPT_BACKUP;
mp_opt->join_id = *ptr++;
mp_opt->thmac = get_unaligned_be64(ptr);
ptr += 8;
mp_opt->nonce = get_unaligned_be32(ptr);
ptr += 4;
pr_debug("MP_JOIN bkup=%u, id=%u, thmac=%llu, nonce=%u",
mp_opt->backup, mp_opt->join_id,
mp_opt->thmac, mp_opt->nonce);
} else if (opsize == TCPOLEN_MPTCP_MPJ_ACK) {
ptr += 2;
memcpy(mp_opt->hmac, ptr, MPTCPOPT_HMAC_LEN);
pr_debug("MP_JOIN hmac");
} else {
mp_opt->suboptions &= ~OPTIONS_MPTCP_MPJ;
}
break;
case MPTCPOPT_DSS:
pr_debug("DSS");
ptr++;
/* we must clear 'mpc_map' be able to detect MP_CAPABLE
* map vs DSS map in mptcp_incoming_options(), and reconstruct
* map info accordingly
*/
mp_opt->mpc_map = 0;
flags = (*ptr++) & MPTCP_DSS_FLAG_MASK;
mp_opt->data_fin = (flags & MPTCP_DSS_DATA_FIN) != 0;
mp_opt->dsn64 = (flags & MPTCP_DSS_DSN64) != 0;
mp_opt->use_map = (flags & MPTCP_DSS_HAS_MAP) != 0;
mp_opt->ack64 = (flags & MPTCP_DSS_ACK64) != 0;
mp_opt->use_ack = (flags & MPTCP_DSS_HAS_ACK);
pr_debug("data_fin=%d dsn64=%d use_map=%d ack64=%d use_ack=%d",
mp_opt->data_fin, mp_opt->dsn64,
mp_opt->use_map, mp_opt->ack64,
mp_opt->use_ack);
expected_opsize = TCPOLEN_MPTCP_DSS_BASE;
if (mp_opt->use_ack) {
if (mp_opt->ack64)
expected_opsize += TCPOLEN_MPTCP_DSS_ACK64;
else
expected_opsize += TCPOLEN_MPTCP_DSS_ACK32;
}
if (mp_opt->use_map) {
if (mp_opt->dsn64)
expected_opsize += TCPOLEN_MPTCP_DSS_MAP64;
else
expected_opsize += TCPOLEN_MPTCP_DSS_MAP32;
}
/* Always parse any csum presence combination, we will enforce
* RFC 8684 Section 3.3.0 checks later in subflow_data_ready
*/
if (opsize != expected_opsize &&
opsize != expected_opsize + TCPOLEN_MPTCP_DSS_CHECKSUM)
break;
mp_opt->suboptions |= OPTION_MPTCP_DSS;
if (mp_opt->use_ack) {
if (mp_opt->ack64) {
mp_opt->data_ack = get_unaligned_be64(ptr);
ptr += 8;
} else {
mp_opt->data_ack = get_unaligned_be32(ptr);
ptr += 4;
}
pr_debug("data_ack=%llu", mp_opt->data_ack);
}
if (mp_opt->use_map) {
if (mp_opt->dsn64) {
mp_opt->data_seq = get_unaligned_be64(ptr);
ptr += 8;
} else {
mp_opt->data_seq = get_unaligned_be32(ptr);
ptr += 4;
}
mp_opt->subflow_seq = get_unaligned_be32(ptr);
ptr += 4;
mp_opt->data_len = get_unaligned_be16(ptr);
ptr += 2;
if (opsize == expected_opsize + TCPOLEN_MPTCP_DSS_CHECKSUM) {
mp_opt->suboptions |= OPTION_MPTCP_CSUMREQD;
mp_opt->csum = get_unaligned((__force __sum16 *)ptr);
ptr += 2;
}
pr_debug("data_seq=%llu subflow_seq=%u data_len=%u csum=%d:%u",
mp_opt->data_seq, mp_opt->subflow_seq,
mp_opt->data_len, !!(mp_opt->suboptions & OPTION_MPTCP_CSUMREQD),
mp_opt->csum);
}
break;
case MPTCPOPT_ADD_ADDR:
mp_opt->echo = (*ptr++) & MPTCP_ADDR_ECHO;
if (!mp_opt->echo) {
if (opsize == TCPOLEN_MPTCP_ADD_ADDR ||
opsize == TCPOLEN_MPTCP_ADD_ADDR_PORT)
mp_opt->addr.family = AF_INET;
#if IS_ENABLED(CONFIG_MPTCP_IPV6)
else if (opsize == TCPOLEN_MPTCP_ADD_ADDR6 ||
opsize == TCPOLEN_MPTCP_ADD_ADDR6_PORT)
mp_opt->addr.family = AF_INET6;
#endif
else
break;
} else {
if (opsize == TCPOLEN_MPTCP_ADD_ADDR_BASE ||
opsize == TCPOLEN_MPTCP_ADD_ADDR_BASE_PORT)
mp_opt->addr.family = AF_INET;
#if IS_ENABLED(CONFIG_MPTCP_IPV6)
else if (opsize == TCPOLEN_MPTCP_ADD_ADDR6_BASE ||
opsize == TCPOLEN_MPTCP_ADD_ADDR6_BASE_PORT)
mp_opt->addr.family = AF_INET6;
#endif
else
break;
}
mp_opt->suboptions |= OPTION_MPTCP_ADD_ADDR;
mp_opt->addr.id = *ptr++;
mp_opt->addr.port = 0;
mp_opt->ahmac = 0;
if (mp_opt->addr.family == AF_INET) {
memcpy((u8 *)&mp_opt->addr.addr.s_addr, (u8 *)ptr, 4);
ptr += 4;
if (opsize == TCPOLEN_MPTCP_ADD_ADDR_PORT ||
opsize == TCPOLEN_MPTCP_ADD_ADDR_BASE_PORT) {
mp_opt->addr.port = htons(get_unaligned_be16(ptr));
ptr += 2;
}
}
#if IS_ENABLED(CONFIG_MPTCP_IPV6)
else {
memcpy(mp_opt->addr.addr6.s6_addr, (u8 *)ptr, 16);
ptr += 16;
if (opsize == TCPOLEN_MPTCP_ADD_ADDR6_PORT ||
opsize == TCPOLEN_MPTCP_ADD_ADDR6_BASE_PORT) {
mp_opt->addr.port = htons(get_unaligned_be16(ptr));
ptr += 2;
}
}
#endif
if (!mp_opt->echo) {
mp_opt->ahmac = get_unaligned_be64(ptr);
ptr += 8;
}
pr_debug("ADD_ADDR%s: id=%d, ahmac=%llu, echo=%d, port=%d",
(mp_opt->addr.family == AF_INET6) ? "6" : "",
mp_opt->addr.id, mp_opt->ahmac, mp_opt->echo, ntohs(mp_opt->addr.port));
break;
case MPTCPOPT_RM_ADDR:
if (opsize < TCPOLEN_MPTCP_RM_ADDR_BASE + 1 ||
opsize > TCPOLEN_MPTCP_RM_ADDR_BASE + MPTCP_RM_IDS_MAX)
break;
ptr++;
mp_opt->suboptions |= OPTION_MPTCP_RM_ADDR;
mp_opt->rm_list.nr = opsize - TCPOLEN_MPTCP_RM_ADDR_BASE;
for (i = 0; i < mp_opt->rm_list.nr; i++)
mp_opt->rm_list.ids[i] = *ptr++;
pr_debug("RM_ADDR: rm_list_nr=%d", mp_opt->rm_list.nr);
break;
case MPTCPOPT_MP_PRIO:
if (opsize != TCPOLEN_MPTCP_PRIO)
break;
mp_opt->suboptions |= OPTION_MPTCP_PRIO;
mp_opt->backup = *ptr++ & MPTCP_PRIO_BKUP;
pr_debug("MP_PRIO: prio=%d", mp_opt->backup);
break;
case MPTCPOPT_MP_FASTCLOSE:
if (opsize != TCPOLEN_MPTCP_FASTCLOSE)
break;
ptr += 2;
mp_opt->rcvr_key = get_unaligned_be64(ptr);
ptr += 8;
mp_opt->suboptions |= OPTION_MPTCP_FASTCLOSE;
pr_debug("MP_FASTCLOSE: recv_key=%llu", mp_opt->rcvr_key);
break;
case MPTCPOPT_RST:
if (opsize != TCPOLEN_MPTCP_RST)
break;
if (!(TCP_SKB_CB(skb)->tcp_flags & TCPHDR_RST))
break;
mp_opt->suboptions |= OPTION_MPTCP_RST;
flags = *ptr++;
mp_opt->reset_transient = flags & MPTCP_RST_TRANSIENT;
mp_opt->reset_reason = *ptr;
pr_debug("MP_RST: transient=%u reason=%u",
mp_opt->reset_transient, mp_opt->reset_reason);
break;
case MPTCPOPT_MP_FAIL:
if (opsize != TCPOLEN_MPTCP_FAIL)
break;
ptr += 2;
mp_opt->suboptions |= OPTION_MPTCP_FAIL;
mp_opt->fail_seq = get_unaligned_be64(ptr);
pr_debug("MP_FAIL: data_seq=%llu", mp_opt->fail_seq);
break;
default:
break;
}
}
void mptcp_get_options(const struct sk_buff *skb,
struct mptcp_options_received *mp_opt)
{
const struct tcphdr *th = tcp_hdr(skb);
const unsigned char *ptr;
int length;
/* initialize option status */
mp_opt->suboptions = 0;
length = (th->doff * 4) - sizeof(struct tcphdr);
ptr = (const unsigned char *)(th + 1);
while (length > 0) {
int opcode = *ptr++;
int opsize;
switch (opcode) {
case TCPOPT_EOL:
return;
case TCPOPT_NOP: /* Ref: RFC 793 section 3.1 */
length--;
continue;
default:
if (length < 2)
return;
opsize = *ptr++;
if (opsize < 2) /* "silly options" */
return;
if (opsize > length)
return; /* don't parse partial options */
if (opcode == TCPOPT_MPTCP)
mptcp_parse_option(skb, ptr, opsize, mp_opt);
ptr += opsize - 2;
length -= opsize;
}
}
}
bool mptcp_syn_options(struct sock *sk, const struct sk_buff *skb,
unsigned int *size, struct mptcp_out_options *opts)
{
struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
/* we will use snd_isn to detect first pkt [re]transmission
* in mptcp_established_options_mp()
*/
subflow->snd_isn = TCP_SKB_CB(skb)->end_seq;
if (subflow->request_mptcp) {
opts->suboptions = OPTION_MPTCP_MPC_SYN;
opts->csum_reqd = mptcp_is_checksum_enabled(sock_net(sk));
opts->allow_join_id0 = mptcp_allow_join_id0(sock_net(sk));
*size = TCPOLEN_MPTCP_MPC_SYN;
return true;
} else if (subflow->request_join) {
pr_debug("remote_token=%u, nonce=%u", subflow->remote_token,
subflow->local_nonce);
opts->suboptions = OPTION_MPTCP_MPJ_SYN;
opts->join_id = subflow->local_id;
opts->token = subflow->remote_token;
opts->nonce = subflow->local_nonce;
opts->backup = subflow->request_bkup;
*size = TCPOLEN_MPTCP_MPJ_SYN;
return true;
}
return false;
}
static void clear_3rdack_retransmission(struct sock *sk)
{
struct inet_connection_sock *icsk = inet_csk(sk);
sk_stop_timer(sk, &icsk->icsk_delack_timer);
icsk->icsk_ack.timeout = 0;
icsk->icsk_ack.ato = 0;
icsk->icsk_ack.pending &= ~(ICSK_ACK_SCHED | ICSK_ACK_TIMER);
}
static bool mptcp_established_options_mp(struct sock *sk, struct sk_buff *skb,
bool snd_data_fin_enable,
unsigned int *size,
struct mptcp_out_options *opts)
{
struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
struct mptcp_sock *msk = mptcp_sk(subflow->conn);
struct mptcp_ext *mpext;
unsigned int data_len;
u8 len;
/* When skb is not available, we better over-estimate the emitted
* options len. A full DSS option (28 bytes) is longer than
* TCPOLEN_MPTCP_MPC_ACK_DATA(22) or TCPOLEN_MPTCP_MPJ_ACK(24), so
* tell the caller to defer the estimate to
* mptcp_established_options_dss(), which will reserve enough space.
*/
if (!skb)
return false;
/* MPC/MPJ needed only on 3rd ack packet, DATA_FIN and TCP shutdown take precedence */
if (subflow->fully_established || snd_data_fin_enable ||
subflow->snd_isn != TCP_SKB_CB(skb)->seq ||
sk->sk_state != TCP_ESTABLISHED)
return false;
if (subflow->mp_capable) {
mpext = mptcp_get_ext(skb);
data_len = mpext ? mpext->data_len : 0;
/* we will check ops->data_len in mptcp_write_options() to
* discriminate between TCPOLEN_MPTCP_MPC_ACK_DATA and
* TCPOLEN_MPTCP_MPC_ACK
*/
opts->data_len = data_len;
opts->suboptions = OPTION_MPTCP_MPC_ACK;
opts->sndr_key = subflow->local_key;
opts->rcvr_key = subflow->remote_key;
opts->csum_reqd = READ_ONCE(msk->csum_enabled);
opts->allow_join_id0 = mptcp_allow_join_id0(sock_net(sk));
/* Section 3.1.
* The MP_CAPABLE option is carried on the SYN, SYN/ACK, and ACK
* packets that start the first subflow of an MPTCP connection,
* as well as the first packet that carries data
*/
if (data_len > 0) {
len = TCPOLEN_MPTCP_MPC_ACK_DATA;
if (opts->csum_reqd) {
/* we need to propagate more info to csum the pseudo hdr */
opts->data_seq = mpext->data_seq;
opts->subflow_seq = mpext->subflow_seq;
opts->csum = mpext->csum;
len += TCPOLEN_MPTCP_DSS_CHECKSUM;
}
*size = ALIGN(len, 4);
} else {
*size = TCPOLEN_MPTCP_MPC_ACK;
}
pr_debug("subflow=%p, local_key=%llu, remote_key=%llu map_len=%d",
subflow, subflow->local_key, subflow->remote_key,
data_len);
return true;
} else if (subflow->mp_join) {
opts->suboptions = OPTION_MPTCP_MPJ_ACK;
memcpy(opts->hmac, subflow->hmac, MPTCPOPT_HMAC_LEN);
*size = TCPOLEN_MPTCP_MPJ_ACK;
pr_debug("subflow=%p", subflow);
/* we can use the full delegate action helper only from BH context
* If we are in process context - sk is flushing the backlog at
* socket lock release time - just set the appropriate flag, will
* be handled by the release callback
*/
if (sock_owned_by_user(sk))
set_bit(MPTCP_DELEGATE_ACK, &subflow->delegated_status);
else
mptcp_subflow_delegate(subflow, MPTCP_DELEGATE_ACK);
return true;
}
return false;
}
static void mptcp_write_data_fin(struct mptcp_subflow_context *subflow,
struct sk_buff *skb, struct mptcp_ext *ext)
{
/* The write_seq value has already been incremented, so the actual
* sequence number for the DATA_FIN is one less.
*/
u64 data_fin_tx_seq = READ_ONCE(mptcp_sk(subflow->conn)->write_seq) - 1;
if (!ext->use_map || !skb->len) {
/* RFC6824 requires a DSS mapping with specific values
* if DATA_FIN is set but no data payload is mapped
*/
ext->data_fin = 1;
ext->use_map = 1;
ext->dsn64 = 1;
ext->data_seq = data_fin_tx_seq;
ext->subflow_seq = 0;
ext->data_len = 1;
} else if (ext->data_seq + ext->data_len == data_fin_tx_seq) {
/* If there's an existing DSS mapping and it is the
* final mapping, DATA_FIN consumes 1 additional byte of
* mapping space.
*/
ext->data_fin = 1;
ext->data_len++;
}
}
static bool mptcp_established_options_dss(struct sock *sk, struct sk_buff *skb,
bool snd_data_fin_enable,
unsigned int *size,
struct mptcp_out_options *opts)
{
struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
struct mptcp_sock *msk = mptcp_sk(subflow->conn);
unsigned int dss_size = 0;
struct mptcp_ext *mpext;
unsigned int ack_size;
bool ret = false;
u64 ack_seq;
opts->csum_reqd = READ_ONCE(msk->csum_enabled);
mpext = skb ? mptcp_get_ext(skb) : NULL;
if (!skb || (mpext && mpext->use_map) || snd_data_fin_enable) {
unsigned int map_size = TCPOLEN_MPTCP_DSS_BASE + TCPOLEN_MPTCP_DSS_MAP64;
if (mpext) {
if (opts->csum_reqd)
map_size += TCPOLEN_MPTCP_DSS_CHECKSUM;
opts->ext_copy = *mpext;
}
dss_size = map_size;
if (skb && snd_data_fin_enable)
mptcp_write_data_fin(subflow, skb, &opts->ext_copy);
opts->suboptions = OPTION_MPTCP_DSS;
ret = true;
}
/* passive sockets msk will set the 'can_ack' after accept(), even
* if the first subflow may have the already the remote key handy
*/
opts->ext_copy.use_ack = 0;
if (!READ_ONCE(msk->can_ack)) {
*size = ALIGN(dss_size, 4);
return ret;
}
ack_seq = READ_ONCE(msk->ack_seq);
if (READ_ONCE(msk->use_64bit_ack)) {
ack_size = TCPOLEN_MPTCP_DSS_ACK64;
opts->ext_copy.data_ack = ack_seq;
opts->ext_copy.ack64 = 1;
} else {
ack_size = TCPOLEN_MPTCP_DSS_ACK32;
opts->ext_copy.data_ack32 = (uint32_t)ack_seq;
opts->ext_copy.ack64 = 0;
}
opts->ext_copy.use_ack = 1;
opts->suboptions = OPTION_MPTCP_DSS;
WRITE_ONCE(msk->old_wspace, __mptcp_space((struct sock *)msk));
/* Add kind/length/subtype/flag overhead if mapping is not populated */
if (dss_size == 0)
ack_size += TCPOLEN_MPTCP_DSS_BASE;
dss_size += ack_size;
*size = ALIGN(dss_size, 4);
return true;
}
static u64 add_addr_generate_hmac(u64 key1, u64 key2,
struct mptcp_addr_info *addr)
{
u16 port = ntohs(addr->port);
u8 hmac[SHA256_DIGEST_SIZE];
u8 msg[19];
int i = 0;
msg[i++] = addr->id;
if (addr->family == AF_INET) {
memcpy(&msg[i], &addr->addr.s_addr, 4);
i += 4;
}
#if IS_ENABLED(CONFIG_MPTCP_IPV6)
else if (addr->family == AF_INET6) {
memcpy(&msg[i], &addr->addr6.s6_addr, 16);
i += 16;
}
#endif
msg[i++] = port >> 8;
msg[i++] = port & 0xFF;
mptcp_crypto_hmac_sha(key1, key2, msg, i, hmac);
return get_unaligned_be64(&hmac[SHA256_DIGEST_SIZE - sizeof(u64)]);
}
static bool mptcp_established_options_add_addr(struct sock *sk, struct sk_buff *skb,
unsigned int *size,
unsigned int remaining,
struct mptcp_out_options *opts)
{
struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
struct mptcp_sock *msk = mptcp_sk(subflow->conn);
bool drop_other_suboptions = false;
unsigned int opt_size = *size;
bool echo;
int len;
/* add addr will strip the existing options, be sure to avoid breaking
* MPC/MPJ handshakes
*/
if (!mptcp_pm_should_add_signal(msk) ||
(opts->suboptions & (OPTION_MPTCP_MPJ_ACK | OPTION_MPTCP_MPC_ACK)) ||
!mptcp_pm_add_addr_signal(msk, skb, opt_size, remaining, &opts->addr,
&echo, &drop_other_suboptions))
return false;
if (drop_other_suboptions)
remaining += opt_size;
len = mptcp_add_addr_len(opts->addr.family, echo, !!opts->addr.port);
if (remaining < len)
return false;
*size = len;
if (drop_other_suboptions) {
pr_debug("drop other suboptions");
opts->suboptions = 0;
/* note that e.g. DSS could have written into the memory
* aliased by ahmac, we must reset the field here
* to avoid appending the hmac even for ADD_ADDR echo
* options
*/
opts->ahmac = 0;
*size -= opt_size;
}
opts->suboptions |= OPTION_MPTCP_ADD_ADDR;
if (!echo) {
MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_ADDADDRTX);
opts->ahmac = add_addr_generate_hmac(msk->local_key,
msk->remote_key,
&opts->addr);
} else {
MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_ECHOADDTX);
}
pr_debug("addr_id=%d, ahmac=%llu, echo=%d, port=%d",
opts->addr.id, opts->ahmac, echo, ntohs(opts->addr.port));
return true;
}
static bool mptcp_established_options_rm_addr(struct sock *sk,
unsigned int *size,
unsigned int remaining,
struct mptcp_out_options *opts)
{
struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
struct mptcp_sock *msk = mptcp_sk(subflow->conn);
struct mptcp_rm_list rm_list;
int i, len;
if (!mptcp_pm_should_rm_signal(msk) ||
!(mptcp_pm_rm_addr_signal(msk, remaining, &rm_list)))
return false;
len = mptcp_rm_addr_len(&rm_list);
if (len < 0)
return false;
if (remaining < len)
return false;
*size = len;
opts->suboptions |= OPTION_MPTCP_RM_ADDR;
opts->rm_list = rm_list;
for (i = 0; i < opts->rm_list.nr; i++)
pr_debug("rm_list_ids[%d]=%d", i, opts->rm_list.ids[i]);
MPTCP_ADD_STATS(sock_net(sk), MPTCP_MIB_RMADDRTX, opts->rm_list.nr);
return true;
}
static bool mptcp_established_options_mp_prio(struct sock *sk,
unsigned int *size,
unsigned int remaining,
struct mptcp_out_options *opts)
{
struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
/* can't send MP_PRIO with MPC, as they share the same option space:
* 'backup'. Also it makes no sense at all
*/
if (!subflow->send_mp_prio || (opts->suboptions & OPTIONS_MPTCP_MPC))
return false;
/* account for the trailing 'nop' option */
if (remaining < TCPOLEN_MPTCP_PRIO_ALIGN)
return false;
*size = TCPOLEN_MPTCP_PRIO_ALIGN;
opts->suboptions |= OPTION_MPTCP_PRIO;
opts->backup = subflow->request_bkup;
pr_debug("prio=%d", opts->backup);
return true;
}
static noinline bool mptcp_established_options_rst(struct sock *sk, struct sk_buff *skb,
unsigned int *size,
unsigned int remaining,
struct mptcp_out_options *opts)
{
const struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
if (remaining < TCPOLEN_MPTCP_RST)
return false;
*size = TCPOLEN_MPTCP_RST;
opts->suboptions |= OPTION_MPTCP_RST;
opts->reset_transient = subflow->reset_transient;
opts->reset_reason = subflow->reset_reason;
MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPRSTTX);
return true;
}
static bool mptcp_established_options_fastclose(struct sock *sk,
unsigned int *size,
unsigned int remaining,
struct mptcp_out_options *opts)
{
struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
struct mptcp_sock *msk = mptcp_sk(subflow->conn);
if (likely(!subflow->send_fastclose))
return false;
if (remaining < TCPOLEN_MPTCP_FASTCLOSE)
return false;
*size = TCPOLEN_MPTCP_FASTCLOSE;
opts->suboptions |= OPTION_MPTCP_FASTCLOSE;
opts->rcvr_key = msk->remote_key;
pr_debug("FASTCLOSE key=%llu", opts->rcvr_key);
MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPFASTCLOSETX);
return true;
}
static bool mptcp_established_options_mp_fail(struct sock *sk,
unsigned int *size,
unsigned int remaining,
struct mptcp_out_options *opts)
{
struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
if (likely(!subflow->send_mp_fail))
return false;
if (remaining < TCPOLEN_MPTCP_FAIL)
return false;
*size = TCPOLEN_MPTCP_FAIL;
opts->suboptions |= OPTION_MPTCP_FAIL;
opts->fail_seq = subflow->map_seq;
pr_debug("MP_FAIL fail_seq=%llu", opts->fail_seq);
MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPFAILTX);
return true;
}
bool mptcp_established_options(struct sock *sk, struct sk_buff *skb,
unsigned int *size, unsigned int remaining,
struct mptcp_out_options *opts)
{
struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
struct mptcp_sock *msk = mptcp_sk(subflow->conn);
unsigned int opt_size = 0;
bool snd_data_fin;
bool ret = false;
opts->suboptions = 0;
if (unlikely(__mptcp_check_fallback(msk) && !mptcp_check_infinite_map(skb)))
return false;
if (unlikely(skb && TCP_SKB_CB(skb)->tcp_flags & TCPHDR_RST)) {
if (mptcp_established_options_fastclose(sk, &opt_size, remaining, opts) ||
mptcp_established_options_mp_fail(sk, &opt_size, remaining, opts)) {
*size += opt_size;
remaining -= opt_size;
}
/* MP_RST can be used with MP_FASTCLOSE and MP_FAIL if there is room */
if (mptcp_established_options_rst(sk, skb, &opt_size, remaining, opts)) {
*size += opt_size;
remaining -= opt_size;
}
return true;
}
snd_data_fin = mptcp_data_fin_enabled(msk);
if (mptcp_established_options_mp(sk, skb, snd_data_fin, &opt_size, opts))
ret = true;
else if (mptcp_established_options_dss(sk, skb, snd_data_fin, &opt_size, opts)) {
unsigned int mp_fail_size;
ret = true;
if (mptcp_established_options_mp_fail(sk, &mp_fail_size,
remaining - opt_size, opts)) {
*size += opt_size + mp_fail_size;
remaining -= opt_size - mp_fail_size;
return true;
}
}
/* we reserved enough space for the above options, and exceeding the
* TCP option space would be fatal
*/
if (WARN_ON_ONCE(opt_size > remaining))
return false;
*size += opt_size;
remaining -= opt_size;
if (mptcp_established_options_add_addr(sk, skb, &opt_size, remaining, opts)) {
*size += opt_size;
remaining -= opt_size;
ret = true;
} else if (mptcp_established_options_rm_addr(sk, &opt_size, remaining, opts)) {
*size += opt_size;
remaining -= opt_size;
ret = true;
}
if (mptcp_established_options_mp_prio(sk, &opt_size, remaining, opts)) {
*size += opt_size;
remaining -= opt_size;
ret = true;
}
return ret;
}
bool mptcp_synack_options(const struct request_sock *req, unsigned int *size,
struct mptcp_out_options *opts)
{
struct mptcp_subflow_request_sock *subflow_req = mptcp_subflow_rsk(req);
if (subflow_req->mp_capable) {
opts->suboptions = OPTION_MPTCP_MPC_SYNACK;
opts->sndr_key = subflow_req->local_key;
opts->csum_reqd = subflow_req->csum_reqd;
opts->allow_join_id0 = subflow_req->allow_join_id0;
*size = TCPOLEN_MPTCP_MPC_SYNACK;
pr_debug("subflow_req=%p, local_key=%llu",
subflow_req, subflow_req->local_key);
return true;
} else if (subflow_req->mp_join) {
opts->suboptions = OPTION_MPTCP_MPJ_SYNACK;
opts->backup = subflow_req->backup;
opts->join_id = subflow_req->local_id;
opts->thmac = subflow_req->thmac;
opts->nonce = subflow_req->local_nonce;
pr_debug("req=%p, bkup=%u, id=%u, thmac=%llu, nonce=%u",
subflow_req, opts->backup, opts->join_id,
opts->thmac, opts->nonce);
*size = TCPOLEN_MPTCP_MPJ_SYNACK;
return true;
}
return false;
}
static bool check_fully_established(struct mptcp_sock *msk, struct sock *ssk,
struct mptcp_subflow_context *subflow,
struct sk_buff *skb,
struct mptcp_options_received *mp_opt)
{
/* here we can process OoO, in-window pkts, only in-sequence 4th ack
* will make the subflow fully established
*/
if (likely(subflow->fully_established)) {
/* on passive sockets, check for 3rd ack retransmission
* note that msk is always set by subflow_syn_recv_sock()
* for mp_join subflows
*/
if (TCP_SKB_CB(skb)->seq == subflow->ssn_offset + 1 &&
TCP_SKB_CB(skb)->end_seq == TCP_SKB_CB(skb)->seq &&
subflow->mp_join && (mp_opt->suboptions & OPTIONS_MPTCP_MPJ) &&
!subflow->request_join)
tcp_send_ack(ssk);
goto check_notify;
}
/* we must process OoO packets before the first subflow is fully
* established. OoO packets are instead a protocol violation
* for MP_JOIN subflows as the peer must not send any data
* before receiving the forth ack - cfr. RFC 8684 section 3.2.
*/
if (TCP_SKB_CB(skb)->seq != subflow->ssn_offset + 1) {
if (subflow->mp_join)
goto reset;
if (subflow->is_mptfo && mp_opt->suboptions & OPTION_MPTCP_MPC_ACK)
goto set_fully_established;
return subflow->mp_capable;
}
if (subflow->remote_key_valid &&
(((mp_opt->suboptions & OPTION_MPTCP_DSS) && mp_opt->use_ack) ||
((mp_opt->suboptions & OPTION_MPTCP_ADD_ADDR) && !mp_opt->echo))) {
/* subflows are fully established as soon as we get any
* additional ack, including ADD_ADDR.
*/
subflow->fully_established = 1;
WRITE_ONCE(msk->fully_established, true);
goto check_notify;
}
/* If the first established packet does not contain MP_CAPABLE + data
* then fallback to TCP. Fallback scenarios requires a reset for
* MP_JOIN subflows.
*/
if (!(mp_opt->suboptions & OPTIONS_MPTCP_MPC)) {
if (subflow->mp_join)
goto reset;
subflow->mp_capable = 0;
pr_fallback(msk);
mptcp_do_fallback(ssk);
return false;
}
if (mp_opt->deny_join_id0)
WRITE_ONCE(msk->pm.remote_deny_join_id0, true);
set_fully_established:
if (unlikely(!READ_ONCE(msk->pm.server_side)))
pr_warn_once("bogus mpc option on established client sk");
mptcp_subflow_fully_established(subflow, mp_opt);
check_notify:
/* if the subflow is not already linked into the conn_list, we can't
* notify the PM: this subflow is still on the listener queue
* and the PM possibly acquiring the subflow lock could race with
* the listener close
*/
if (likely(subflow->pm_notified) || list_empty(&subflow->node))
return true;
subflow->pm_notified = 1;
if (subflow->mp_join) {
clear_3rdack_retransmission(ssk);
mptcp_pm_subflow_established(msk);
} else {
mptcp_pm_fully_established(msk, ssk);
}
return true;
reset:
mptcp_subflow_reset(ssk);
return false;
}
u64 __mptcp_expand_seq(u64 old_seq, u64 cur_seq)
{
u32 old_seq32, cur_seq32;
old_seq32 = (u32)old_seq;
cur_seq32 = (u32)cur_seq;
cur_seq = (old_seq & GENMASK_ULL(63, 32)) + cur_seq32;
if (unlikely(cur_seq32 < old_seq32 && before(old_seq32, cur_seq32)))
return cur_seq + (1LL << 32);
/* reverse wrap could happen, too */
if (unlikely(cur_seq32 > old_seq32 && after(old_seq32, cur_seq32)))
return cur_seq - (1LL << 32);
return cur_seq;
}
static void __mptcp_snd_una_update(struct mptcp_sock *msk, u64 new_snd_una)
{
msk->bytes_acked += new_snd_una - msk->snd_una;
msk->snd_una = new_snd_una;
}
static void ack_update_msk(struct mptcp_sock *msk,
struct sock *ssk,
struct mptcp_options_received *mp_opt)
{
u64 new_wnd_end, new_snd_una, snd_nxt = READ_ONCE(msk->snd_nxt);
struct sock *sk = (struct sock *)msk;
u64 old_snd_una;
mptcp_data_lock(sk);
/* avoid ack expansion on update conflict, to reduce the risk of
* wrongly expanding to a future ack sequence number, which is way
* more dangerous than missing an ack
*/
old_snd_una = msk->snd_una;
new_snd_una = mptcp_expand_seq(old_snd_una, mp_opt->data_ack, mp_opt->ack64);
/* ACK for data not even sent yet? Ignore.*/
if (unlikely(after64(new_snd_una, snd_nxt)))
new_snd_una = old_snd_una;
new_wnd_end = new_snd_una + tcp_sk(ssk)->snd_wnd;
if (after64(new_wnd_end, msk->wnd_end))
msk->wnd_end = new_wnd_end;
/* this assumes mptcp_incoming_options() is invoked after tcp_ack() */
if (after64(msk->wnd_end, READ_ONCE(msk->snd_nxt)))
__mptcp_check_push(sk, ssk);
if (after64(new_snd_una, old_snd_una)) {
__mptcp_snd_una_update(msk, new_snd_una);
__mptcp_data_acked(sk);
}
mptcp_data_unlock(sk);
trace_ack_update_msk(mp_opt->data_ack,
old_snd_una, new_snd_una,
new_wnd_end, msk->wnd_end);
}
bool mptcp_update_rcv_data_fin(struct mptcp_sock *msk, u64 data_fin_seq, bool use_64bit)
{
/* Skip if DATA_FIN was already received.
* If updating simultaneously with the recvmsg loop, values
* should match. If they mismatch, the peer is misbehaving and
* we will prefer the most recent information.
*/
if (READ_ONCE(msk->rcv_data_fin))
return false;
WRITE_ONCE(msk->rcv_data_fin_seq,
mptcp_expand_seq(READ_ONCE(msk->ack_seq), data_fin_seq, use_64bit));
WRITE_ONCE(msk->rcv_data_fin, 1);
return true;
}
static bool add_addr_hmac_valid(struct mptcp_sock *msk,
struct mptcp_options_received *mp_opt)
{
u64 hmac = 0;
if (mp_opt->echo)
return true;
hmac = add_addr_generate_hmac(msk->remote_key,
msk->local_key,
&mp_opt->addr);
pr_debug("msk=%p, ahmac=%llu, mp_opt->ahmac=%llu\n",
msk, hmac, mp_opt->ahmac);
return hmac == mp_opt->ahmac;
}
/* Return false if a subflow has been reset, else return true */
bool mptcp_incoming_options(struct sock *sk, struct sk_buff *skb)
{
struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
struct mptcp_sock *msk = mptcp_sk(subflow->conn);
struct mptcp_options_received mp_opt;
struct mptcp_ext *mpext;
if (__mptcp_check_fallback(msk)) {
/* Keep it simple and unconditionally trigger send data cleanup and
* pending queue spooling. We will need to acquire the data lock
* for more accurate checks, and once the lock is acquired, such
* helpers are cheap.
*/
mptcp_data_lock(subflow->conn);
if (sk_stream_memory_free(sk))
__mptcp_check_push(subflow->conn, sk);
/* on fallback we just need to ignore the msk-level snd_una, as
* this is really plain TCP
*/
__mptcp_snd_una_update(msk, READ_ONCE(msk->snd_nxt));
__mptcp_data_acked(subflow->conn);
mptcp_data_unlock(subflow->conn);
return true;
}
mptcp_get_options(skb, &mp_opt);
/* The subflow can be in close state only if check_fully_established()
* just sent a reset. If so, tell the caller to ignore the current packet.
*/
if (!check_fully_established(msk, sk, subflow, skb, &mp_opt))
return sk->sk_state != TCP_CLOSE;
if (unlikely(mp_opt.suboptions != OPTION_MPTCP_DSS)) {
if ((mp_opt.suboptions & OPTION_MPTCP_FASTCLOSE) &&
msk->local_key == mp_opt.rcvr_key) {
WRITE_ONCE(msk->rcv_fastclose, true);
mptcp_schedule_work((struct sock *)msk);
MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPFASTCLOSERX);
}
if ((mp_opt.suboptions & OPTION_MPTCP_ADD_ADDR) &&
add_addr_hmac_valid(msk, &mp_opt)) {
if (!mp_opt.echo) {
mptcp_pm_add_addr_received(sk, &mp_opt.addr);
MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_ADDADDR);
} else {
mptcp_pm_add_addr_echoed(msk, &mp_opt.addr);
mptcp_pm_del_add_timer(msk, &mp_opt.addr, true);
MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_ECHOADD);
}
if (mp_opt.addr.port)
MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_PORTADD);
}
if (mp_opt.suboptions & OPTION_MPTCP_RM_ADDR)
mptcp_pm_rm_addr_received(msk, &mp_opt.rm_list);
if (mp_opt.suboptions & OPTION_MPTCP_PRIO) {
mptcp_pm_mp_prio_received(sk, mp_opt.backup);
MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPPRIORX);
}
if (mp_opt.suboptions & OPTION_MPTCP_FAIL) {
mptcp_pm_mp_fail_received(sk, mp_opt.fail_seq);
MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPFAILRX);
}
if (mp_opt.suboptions & OPTION_MPTCP_RST) {
subflow->reset_seen = 1;
subflow->reset_reason = mp_opt.reset_reason;
subflow->reset_transient = mp_opt.reset_transient;
MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPRSTRX);
}
if (!(mp_opt.suboptions & OPTION_MPTCP_DSS))
return true;
}
/* we can't wait for recvmsg() to update the ack_seq, otherwise
* monodirectional flows will stuck
*/
if (mp_opt.use_ack)
ack_update_msk(msk, sk, &mp_opt);
/* Zero-data-length packets are dropped by the caller and not
* propagated to the MPTCP layer, so the skb extension does not
* need to be allocated or populated. DATA_FIN information, if
* present, needs to be updated here before the skb is freed.
*/
if (TCP_SKB_CB(skb)->seq == TCP_SKB_CB(skb)->end_seq) {
if (mp_opt.data_fin && mp_opt.data_len == 1 &&
mptcp_update_rcv_data_fin(msk, mp_opt.data_seq, mp_opt.dsn64))
mptcp_schedule_work((struct sock *)msk);
return true;
}
mpext = skb_ext_add(skb, SKB_EXT_MPTCP);
if (!mpext)
return true;
memset(mpext, 0, sizeof(*mpext));
if (likely(mp_opt.use_map)) {
if (mp_opt.mpc_map) {
/* this is an MP_CAPABLE carrying MPTCP data
* we know this map the first chunk of data
*/
mptcp_crypto_key_sha(subflow->remote_key, NULL,
&mpext->data_seq);
mpext->data_seq++;
mpext->subflow_seq = 1;
mpext->dsn64 = 1;
mpext->mpc_map = 1;
mpext->data_fin = 0;
} else {
mpext->data_seq = mp_opt.data_seq;
mpext->subflow_seq = mp_opt.subflow_seq;
mpext->dsn64 = mp_opt.dsn64;
mpext->data_fin = mp_opt.data_fin;
}
mpext->data_len = mp_opt.data_len;
mpext->use_map = 1;
mpext->csum_reqd = !!(mp_opt.suboptions & OPTION_MPTCP_CSUMREQD);
if (mpext->csum_reqd)
mpext->csum = mp_opt.csum;
}
return true;
}
static void mptcp_set_rwin(struct tcp_sock *tp, struct tcphdr *th)
{
const struct sock *ssk = (const struct sock *)tp;
struct mptcp_subflow_context *subflow;
u64 ack_seq, rcv_wnd_old, rcv_wnd_new;
struct mptcp_sock *msk;
u32 new_win;
u64 win;
subflow = mptcp_subflow_ctx(ssk);
msk = mptcp_sk(subflow->conn);
ack_seq = READ_ONCE(msk->ack_seq);
rcv_wnd_new = ack_seq + tp->rcv_wnd;
rcv_wnd_old = atomic64_read(&msk->rcv_wnd_sent);
if (after64(rcv_wnd_new, rcv_wnd_old)) {
u64 rcv_wnd;
for (;;) {
rcv_wnd = atomic64_cmpxchg(&msk->rcv_wnd_sent, rcv_wnd_old, rcv_wnd_new);
if (rcv_wnd == rcv_wnd_old)
break;
if (before64(rcv_wnd_new, rcv_wnd)) {
MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_RCVWNDCONFLICTUPDATE);
goto raise_win;
}
MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_RCVWNDCONFLICT);
rcv_wnd_old = rcv_wnd;
}
return;
}
if (rcv_wnd_new != rcv_wnd_old) {
raise_win:
win = rcv_wnd_old - ack_seq;
tp->rcv_wnd = min_t(u64, win, U32_MAX);
new_win = tp->rcv_wnd;
/* Make sure we do not exceed the maximum possible
* scaled window.
*/
if (unlikely(th->syn))
new_win = min(new_win, 65535U) << tp->rx_opt.rcv_wscale;
if (!tp->rx_opt.rcv_wscale &&
READ_ONCE(sock_net(ssk)->ipv4.sysctl_tcp_workaround_signed_windows))
new_win = min(new_win, MAX_TCP_WINDOW);
else
new_win = min(new_win, (65535U << tp->rx_opt.rcv_wscale));
/* RFC1323 scaling applied */
new_win >>= tp->rx_opt.rcv_wscale;
th->window = htons(new_win);
MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_RCVWNDSHARED);
}
}
__sum16 __mptcp_make_csum(u64 data_seq, u32 subflow_seq, u16 data_len, __wsum sum)
{
struct csum_pseudo_header header;
__wsum csum;
/* cfr RFC 8684 3.3.1.:
* the data sequence number used in the pseudo-header is
* always the 64-bit value, irrespective of what length is used in the
* DSS option itself.
*/
header.data_seq = cpu_to_be64(data_seq);
header.subflow_seq = htonl(subflow_seq);
header.data_len = htons(data_len);
header.csum = 0;
csum = csum_partial(&header, sizeof(header), sum);
return csum_fold(csum);
}
static __sum16 mptcp_make_csum(const struct mptcp_ext *mpext)
{
return __mptcp_make_csum(mpext->data_seq, mpext->subflow_seq, mpext->data_len,
~csum_unfold(mpext->csum));
}
static void put_len_csum(u16 len, __sum16 csum, void *data)
{
__sum16 *sumptr = data + 2;
__be16 *ptr = data;
put_unaligned_be16(len, ptr);
put_unaligned(csum, sumptr);
}
void mptcp_write_options(struct tcphdr *th, __be32 *ptr, struct tcp_sock *tp,
struct mptcp_out_options *opts)
{
const struct sock *ssk = (const struct sock *)tp;
struct mptcp_subflow_context *subflow;
/* Which options can be used together?
*
* X: mutually exclusive
* O: often used together
* C: can be used together in some cases
* P: could be used together but we prefer not to (optimisations)
*
* Opt: | MPC | MPJ | DSS | ADD | RM | PRIO | FAIL | FC |
* ------|------|------|------|------|------|------|------|------|
* MPC |------|------|------|------|------|------|------|------|
* MPJ | X |------|------|------|------|------|------|------|
* DSS | X | X |------|------|------|------|------|------|
* ADD | X | X | P |------|------|------|------|------|
* RM | C | C | C | P |------|------|------|------|
* PRIO | X | C | C | C | C |------|------|------|
* FAIL | X | X | C | X | X | X |------|------|
* FC | X | X | X | X | X | X | X |------|
* RST | X | X | X | X | X | X | O | O |
* ------|------|------|------|------|------|------|------|------|
*
* The same applies in mptcp_established_options() function.
*/
if (likely(OPTION_MPTCP_DSS & opts->suboptions)) {
struct mptcp_ext *mpext = &opts->ext_copy;
u8 len = TCPOLEN_MPTCP_DSS_BASE;
u8 flags = 0;
if (mpext->use_ack) {
flags = MPTCP_DSS_HAS_ACK;
if (mpext->ack64) {
len += TCPOLEN_MPTCP_DSS_ACK64;
flags |= MPTCP_DSS_ACK64;
} else {
len += TCPOLEN_MPTCP_DSS_ACK32;
}
}
if (mpext->use_map) {
len += TCPOLEN_MPTCP_DSS_MAP64;
/* Use only 64-bit mapping flags for now, add
* support for optional 32-bit mappings later.
*/
flags |= MPTCP_DSS_HAS_MAP | MPTCP_DSS_DSN64;
if (mpext->data_fin)
flags |= MPTCP_DSS_DATA_FIN;
if (opts->csum_reqd)
len += TCPOLEN_MPTCP_DSS_CHECKSUM;
}
*ptr++ = mptcp_option(MPTCPOPT_DSS, len, 0, flags);
if (mpext->use_ack) {
if (mpext->ack64) {
put_unaligned_be64(mpext->data_ack, ptr);
ptr += 2;
} else {
put_unaligned_be32(mpext->data_ack32, ptr);
ptr += 1;
}
}
if (mpext->use_map) {
put_unaligned_be64(mpext->data_seq, ptr);
ptr += 2;
put_unaligned_be32(mpext->subflow_seq, ptr);
ptr += 1;
if (opts->csum_reqd) {
/* data_len == 0 is reserved for the infinite mapping,
* the checksum will also be set to 0.
*/
put_len_csum(mpext->data_len,
(mpext->data_len ? mptcp_make_csum(mpext) : 0),
ptr);
} else {
put_unaligned_be32(mpext->data_len << 16 |
TCPOPT_NOP << 8 | TCPOPT_NOP, ptr);
}
ptr += 1;
}
/* We might need to add MP_FAIL options in rare cases */
if (unlikely(OPTION_MPTCP_FAIL & opts->suboptions))
goto mp_fail;
} else if (OPTIONS_MPTCP_MPC & opts->suboptions) {
u8 len, flag = MPTCP_CAP_HMAC_SHA256;
if (OPTION_MPTCP_MPC_SYN & opts->suboptions) {
len = TCPOLEN_MPTCP_MPC_SYN;
} else if (OPTION_MPTCP_MPC_SYNACK & opts->suboptions) {
len = TCPOLEN_MPTCP_MPC_SYNACK;
} else if (opts->data_len) {
len = TCPOLEN_MPTCP_MPC_ACK_DATA;
if (opts->csum_reqd)
len += TCPOLEN_MPTCP_DSS_CHECKSUM;
} else {
len = TCPOLEN_MPTCP_MPC_ACK;
}
if (opts->csum_reqd)
flag |= MPTCP_CAP_CHECKSUM_REQD;
if (!opts->allow_join_id0)
flag |= MPTCP_CAP_DENY_JOIN_ID0;
*ptr++ = mptcp_option(MPTCPOPT_MP_CAPABLE, len,
MPTCP_SUPPORTED_VERSION,
flag);
if (!((OPTION_MPTCP_MPC_SYNACK | OPTION_MPTCP_MPC_ACK) &
opts->suboptions))
goto mp_capable_done;
put_unaligned_be64(opts->sndr_key, ptr);
ptr += 2;
if (!((OPTION_MPTCP_MPC_ACK) & opts->suboptions))
goto mp_capable_done;
put_unaligned_be64(opts->rcvr_key, ptr);
ptr += 2;
if (!opts->data_len)
goto mp_capable_done;
if (opts->csum_reqd) {
put_len_csum(opts->data_len,
__mptcp_make_csum(opts->data_seq,
opts->subflow_seq,
opts->data_len,
~csum_unfold(opts->csum)),
ptr);
} else {
put_unaligned_be32(opts->data_len << 16 |
TCPOPT_NOP << 8 | TCPOPT_NOP, ptr);
}
ptr += 1;
/* MPC is additionally mutually exclusive with MP_PRIO */
goto mp_capable_done;
} else if (OPTIONS_MPTCP_MPJ & opts->suboptions) {
if (OPTION_MPTCP_MPJ_SYN & opts->suboptions) {
*ptr++ = mptcp_option(MPTCPOPT_MP_JOIN,
TCPOLEN_MPTCP_MPJ_SYN,
opts->backup, opts->join_id);
put_unaligned_be32(opts->token, ptr);
ptr += 1;
put_unaligned_be32(opts->nonce, ptr);
ptr += 1;
} else if (OPTION_MPTCP_MPJ_SYNACK & opts->suboptions) {
*ptr++ = mptcp_option(MPTCPOPT_MP_JOIN,
TCPOLEN_MPTCP_MPJ_SYNACK,
opts->backup, opts->join_id);
put_unaligned_be64(opts->thmac, ptr);
ptr += 2;
put_unaligned_be32(opts->nonce, ptr);
ptr += 1;
} else {
*ptr++ = mptcp_option(MPTCPOPT_MP_JOIN,
TCPOLEN_MPTCP_MPJ_ACK, 0, 0);
memcpy(ptr, opts->hmac, MPTCPOPT_HMAC_LEN);
ptr += 5;
}
} else if (OPTION_MPTCP_ADD_ADDR & opts->suboptions) {
u8 len = TCPOLEN_MPTCP_ADD_ADDR_BASE;
u8 echo = MPTCP_ADDR_ECHO;
#if IS_ENABLED(CONFIG_MPTCP_IPV6)
if (opts->addr.family == AF_INET6)
len = TCPOLEN_MPTCP_ADD_ADDR6_BASE;
#endif
if (opts->addr.port)
len += TCPOLEN_MPTCP_PORT_LEN;
if (opts->ahmac) {
len += sizeof(opts->ahmac);
echo = 0;
}
*ptr++ = mptcp_option(MPTCPOPT_ADD_ADDR,
len, echo, opts->addr.id);
if (opts->addr.family == AF_INET) {
memcpy((u8 *)ptr, (u8 *)&opts->addr.addr.s_addr, 4);
ptr += 1;
}
#if IS_ENABLED(CONFIG_MPTCP_IPV6)
else if (opts->addr.family == AF_INET6) {
memcpy((u8 *)ptr, opts->addr.addr6.s6_addr, 16);
ptr += 4;
}
#endif
if (!opts->addr.port) {
if (opts->ahmac) {
put_unaligned_be64(opts->ahmac, ptr);
ptr += 2;
}
} else {
u16 port = ntohs(opts->addr.port);
if (opts->ahmac) {
u8 *bptr = (u8 *)ptr;
put_unaligned_be16(port, bptr);
bptr += 2;
put_unaligned_be64(opts->ahmac, bptr);
bptr += 8;
put_unaligned_be16(TCPOPT_NOP << 8 |
TCPOPT_NOP, bptr);
ptr += 3;
} else {
put_unaligned_be32(port << 16 |
TCPOPT_NOP << 8 |
TCPOPT_NOP, ptr);
ptr += 1;
}
}
} else if (unlikely(OPTION_MPTCP_FASTCLOSE & opts->suboptions)) {
/* FASTCLOSE is mutually exclusive with others except RST */
*ptr++ = mptcp_option(MPTCPOPT_MP_FASTCLOSE,
TCPOLEN_MPTCP_FASTCLOSE,
0, 0);
put_unaligned_be64(opts->rcvr_key, ptr);
ptr += 2;
if (OPTION_MPTCP_RST & opts->suboptions)
goto mp_rst;
return;
} else if (unlikely(OPTION_MPTCP_FAIL & opts->suboptions)) {
mp_fail:
/* MP_FAIL is mutually exclusive with others except RST */
subflow = mptcp_subflow_ctx(ssk);
subflow->send_mp_fail = 0;
*ptr++ = mptcp_option(MPTCPOPT_MP_FAIL,
TCPOLEN_MPTCP_FAIL,
0, 0);
put_unaligned_be64(opts->fail_seq, ptr);
ptr += 2;
if (OPTION_MPTCP_RST & opts->suboptions)
goto mp_rst;
return;
} else if (unlikely(OPTION_MPTCP_RST & opts->suboptions)) {
mp_rst:
*ptr++ = mptcp_option(MPTCPOPT_RST,
TCPOLEN_MPTCP_RST,
opts->reset_transient,
opts->reset_reason);
return;
}
if (OPTION_MPTCP_PRIO & opts->suboptions) {
subflow = mptcp_subflow_ctx(ssk);
subflow->send_mp_prio = 0;
*ptr++ = mptcp_option(MPTCPOPT_MP_PRIO,
TCPOLEN_MPTCP_PRIO,
opts->backup, TCPOPT_NOP);
MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_MPPRIOTX);
}
mp_capable_done:
if (OPTION_MPTCP_RM_ADDR & opts->suboptions) {
u8 i = 1;
*ptr++ = mptcp_option(MPTCPOPT_RM_ADDR,
TCPOLEN_MPTCP_RM_ADDR_BASE + opts->rm_list.nr,
0, opts->rm_list.ids[0]);
while (i < opts->rm_list.nr) {
u8 id1, id2, id3, id4;
id1 = opts->rm_list.ids[i];
id2 = i + 1 < opts->rm_list.nr ? opts->rm_list.ids[i + 1] : TCPOPT_NOP;
id3 = i + 2 < opts->rm_list.nr ? opts->rm_list.ids[i + 2] : TCPOPT_NOP;
id4 = i + 3 < opts->rm_list.nr ? opts->rm_list.ids[i + 3] : TCPOPT_NOP;
put_unaligned_be32(id1 << 24 | id2 << 16 | id3 << 8 | id4, ptr);
ptr += 1;
i += 4;
}
}
if (tp)
mptcp_set_rwin(tp, th);
}
__be32 mptcp_get_reset_option(const struct sk_buff *skb)
{
const struct mptcp_ext *ext = mptcp_get_ext(skb);
u8 flags, reason;
if (ext) {
flags = ext->reset_transient;
reason = ext->reset_reason;
return mptcp_option(MPTCPOPT_RST, TCPOLEN_MPTCP_RST,
flags, reason);
}
return htonl(0u);
}
EXPORT_SYMBOL_GPL(mptcp_get_reset_option);
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