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-rw-r--r--include/linux/tcp.h3
-rw-r--r--include/net/mptcp.h17
-rw-r--r--net/ipv4/tcp_input.c2
-rw-r--r--net/ipv4/tcp_output.c2
-rw-r--r--net/mptcp/options.c162
-rw-r--r--net/mptcp/protocol.h6
-rw-r--r--net/mptcp/subflow.c14
7 files changed, 160 insertions, 46 deletions
diff --git a/include/linux/tcp.h b/include/linux/tcp.h
index 0d00dad4b85d..4e2124607d32 100644
--- a/include/linux/tcp.h
+++ b/include/linux/tcp.h
@@ -94,7 +94,8 @@ struct mptcp_options_received {
data_fin:1,
use_ack:1,
ack64:1,
- __unused:3;
+ mpc_map:1,
+ __unused:2;
};
#endif
diff --git a/include/net/mptcp.h b/include/net/mptcp.h
index 8619c1fca741..27627e2d1bc2 100644
--- a/include/net/mptcp.h
+++ b/include/net/mptcp.h
@@ -23,7 +23,8 @@ struct mptcp_ext {
data_fin:1,
use_ack:1,
ack64:1,
- __unused:3;
+ mpc_map:1,
+ __unused:2;
/* one byte hole */
};
@@ -50,10 +51,10 @@ static inline bool rsk_is_mptcp(const struct request_sock *req)
return tcp_rsk(req)->is_mptcp;
}
-void mptcp_parse_option(const unsigned char *ptr, int opsize,
- struct tcp_options_received *opt_rx);
-bool mptcp_syn_options(struct sock *sk, unsigned int *size,
- struct mptcp_out_options *opts);
+void mptcp_parse_option(const struct sk_buff *skb, const unsigned char *ptr,
+ int opsize, struct tcp_options_received *opt_rx);
+bool mptcp_syn_options(struct sock *sk, const struct sk_buff *skb,
+ unsigned int *size, struct mptcp_out_options *opts);
void mptcp_rcv_synsent(struct sock *sk);
bool mptcp_synack_options(const struct request_sock *req, unsigned int *size,
struct mptcp_out_options *opts);
@@ -121,12 +122,14 @@ static inline bool rsk_is_mptcp(const struct request_sock *req)
return false;
}
-static inline void mptcp_parse_option(const unsigned char *ptr, int opsize,
+static inline void mptcp_parse_option(const struct sk_buff *skb,
+ const unsigned char *ptr, int opsize,
struct tcp_options_received *opt_rx)
{
}
-static inline bool mptcp_syn_options(struct sock *sk, unsigned int *size,
+static inline bool mptcp_syn_options(struct sock *sk, const struct sk_buff *skb,
+ unsigned int *size,
struct mptcp_out_options *opts)
{
return false;
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 28d31f2c1422..2f475b897c11 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -3926,7 +3926,7 @@ void tcp_parse_options(const struct net *net,
break;
#endif
case TCPOPT_MPTCP:
- mptcp_parse_option(ptr, opsize, opt_rx);
+ mptcp_parse_option(skb, ptr, opsize, opt_rx);
break;
case TCPOPT_FASTOPEN:
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 5456076166da..fec4b3a4b22d 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -685,7 +685,7 @@ static unsigned int tcp_syn_options(struct sock *sk, struct sk_buff *skb,
if (sk_is_mptcp(sk)) {
unsigned int size;
- if (mptcp_syn_options(sk, &size, &opts->mptcp)) {
+ if (mptcp_syn_options(sk, skb, &size, &opts->mptcp)) {
opts->options |= OPTION_MPTCP;
remaining -= size;
}
diff --git a/net/mptcp/options.c b/net/mptcp/options.c
index 1aec742ca8e1..8f82ff9a5a8e 100644
--- a/net/mptcp/options.c
+++ b/net/mptcp/options.c
@@ -14,8 +14,8 @@ static bool mptcp_cap_flag_sha256(u8 flags)
return (flags & MPTCP_CAP_FLAG_MASK) == MPTCP_CAP_HMAC_SHA256;
}
-void mptcp_parse_option(const unsigned char *ptr, int opsize,
- struct tcp_options_received *opt_rx)
+void mptcp_parse_option(const struct sk_buff *skb, const unsigned char *ptr,
+ int opsize, struct tcp_options_received *opt_rx)
{
struct mptcp_options_received *mp_opt = &opt_rx->mptcp;
u8 subtype = *ptr >> 4;
@@ -25,13 +25,29 @@ void mptcp_parse_option(const unsigned char *ptr, int opsize,
switch (subtype) {
case MPTCPOPT_MP_CAPABLE:
- if (opsize != TCPOLEN_MPTCP_MPC_SYN &&
- opsize != TCPOLEN_MPTCP_MPC_ACK)
+ /* 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;
+ } else {
+ if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_ACK)
+ expected_opsize = TCPOLEN_MPTCP_MPC_SYNACK;
+ else
+ expected_opsize = TCPOLEN_MPTCP_MPC_SYN;
+ }
+ if (opsize != expected_opsize)
break;
+ /* try to be gentle vs future versions on the initial syn */
version = *ptr++ & MPTCP_VERSION_MASK;
- if (version != MPTCP_SUPPORTED_VERSION)
+ 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) ||
@@ -55,23 +71,40 @@ void mptcp_parse_option(const unsigned char *ptr, int opsize,
break;
mp_opt->mp_capable = 1;
- mp_opt->sndr_key = get_unaligned_be64(ptr);
- ptr += 8;
-
- if (opsize == TCPOLEN_MPTCP_MPC_ACK) {
+ 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;
- pr_debug("MP_CAPABLE sndr=%llu, rcvr=%llu",
- mp_opt->sndr_key, mp_opt->rcvr_key);
- } else {
- pr_debug("MP_CAPABLE sndr=%llu", mp_opt->sndr_key);
}
+ 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->dss = 1;
+ mp_opt->use_map = 1;
+ mp_opt->mpc_map = 1;
+ mp_opt->data_len = get_unaligned_be16(ptr);
+ ptr += 2;
+ }
+ pr_debug("MP_CAPABLE version=%x, flags=%x, optlen=%d sndr=%llu, rcvr=%llu len=%d",
+ version, flags, opsize, mp_opt->sndr_key,
+ mp_opt->rcvr_key, mp_opt->data_len);
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;
@@ -176,18 +209,22 @@ void mptcp_get_options(const struct sk_buff *skb,
if (opsize > length)
return; /* don't parse partial options */
if (opcode == TCPOPT_MPTCP)
- mptcp_parse_option(ptr, opsize, opt_rx);
+ mptcp_parse_option(skb, ptr, opsize, opt_rx);
ptr += opsize - 2;
length -= opsize;
}
}
}
-bool mptcp_syn_options(struct sock *sk, unsigned int *size,
- struct mptcp_out_options *opts)
+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) {
pr_debug("local_key=%llu", subflow->local_key);
opts->suboptions = OPTION_MPTCP_MPC_SYN;
@@ -212,20 +249,52 @@ void mptcp_rcv_synsent(struct sock *sk)
}
}
-static bool mptcp_established_options_mp(struct sock *sk, unsigned int *size,
+static bool mptcp_established_options_mp(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_ext *mpext;
+ unsigned int data_len;
+
+ pr_debug("subflow=%p fourth_ack=%d seq=%x:%x remaining=%d", subflow,
+ subflow->fourth_ack, subflow->snd_isn,
+ skb ? TCP_SKB_CB(skb)->seq : 0, remaining);
+
+ if (subflow->mp_capable && !subflow->fourth_ack && skb &&
+ subflow->snd_isn == TCP_SKB_CB(skb)->seq) {
+ /* When skb is not available, we better over-estimate the
+ * emitted options len. A full DSS option is longer than
+ * TCPOLEN_MPTCP_MPC_ACK_DATA, so let's the caller try to fit
+ * that.
+ */
+ mpext = mptcp_get_ext(skb);
+ data_len = mpext ? mpext->data_len : 0;
- if (!subflow->fourth_ack) {
+ /* we will check ext_copy.data_len in mptcp_write_options() to
+ * discriminate between TCPOLEN_MPTCP_MPC_ACK_DATA and
+ * TCPOLEN_MPTCP_MPC_ACK
+ */
+ opts->ext_copy.data_len = data_len;
opts->suboptions = OPTION_MPTCP_MPC_ACK;
opts->sndr_key = subflow->local_key;
opts->rcvr_key = subflow->remote_key;
- *size = TCPOLEN_MPTCP_MPC_ACK;
- subflow->fourth_ack = 1;
- pr_debug("subflow=%p, local_key=%llu, remote_key=%llu",
- subflow, subflow->local_key, subflow->remote_key);
+
+ /* 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)
+ *size = ALIGN(TCPOLEN_MPTCP_MPC_ACK_DATA, 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;
}
return false;
@@ -319,7 +388,7 @@ bool mptcp_established_options(struct sock *sk, struct sk_buff *skb,
unsigned int opt_size = 0;
bool ret = false;
- if (mptcp_established_options_mp(sk, &opt_size, remaining, opts))
+ if (mptcp_established_options_mp(sk, skb, &opt_size, remaining, opts))
ret = true;
else if (mptcp_established_options_dss(sk, skb, &opt_size, remaining,
opts))
@@ -371,11 +440,26 @@ void mptcp_incoming_options(struct sock *sk, struct sk_buff *skb,
memset(mpext, 0, sizeof(*mpext));
if (mp_opt->use_map) {
- mpext->data_seq = mp_opt->data_seq;
- mpext->subflow_seq = mp_opt->subflow_seq;
+ if (mp_opt->mpc_map) {
+ struct mptcp_subflow_context *subflow =
+ mptcp_subflow_ctx(sk);
+
+ /* 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;
+ } else {
+ mpext->data_seq = mp_opt->data_seq;
+ mpext->subflow_seq = mp_opt->subflow_seq;
+ mpext->dsn64 = mp_opt->dsn64;
+ }
mpext->data_len = mp_opt->data_len;
mpext->use_map = 1;
- mpext->dsn64 = mp_opt->dsn64;
}
if (mp_opt->use_ack) {
@@ -389,8 +473,7 @@ void mptcp_incoming_options(struct sock *sk, struct sk_buff *skb,
void mptcp_write_options(__be32 *ptr, struct mptcp_out_options *opts)
{
- if ((OPTION_MPTCP_MPC_SYN |
- OPTION_MPTCP_MPC_SYNACK |
+ if ((OPTION_MPTCP_MPC_SYN | OPTION_MPTCP_MPC_SYNACK |
OPTION_MPTCP_MPC_ACK) & opts->suboptions) {
u8 len;
@@ -398,6 +481,8 @@ void mptcp_write_options(__be32 *ptr, struct mptcp_out_options *opts)
len = TCPOLEN_MPTCP_MPC_SYN;
else if (OPTION_MPTCP_MPC_SYNACK & opts->suboptions)
len = TCPOLEN_MPTCP_MPC_SYNACK;
+ else if (opts->ext_copy.data_len)
+ len = TCPOLEN_MPTCP_MPC_ACK_DATA;
else
len = TCPOLEN_MPTCP_MPC_ACK;
@@ -405,14 +490,27 @@ void mptcp_write_options(__be32 *ptr, struct mptcp_out_options *opts)
(MPTCPOPT_MP_CAPABLE << 12) |
(MPTCP_SUPPORTED_VERSION << 8) |
MPTCP_CAP_HMAC_SHA256);
+
+ 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) {
- put_unaligned_be64(opts->rcvr_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->ext_copy.data_len)
+ goto mp_capable_done;
+
+ put_unaligned_be32(opts->ext_copy.data_len << 16 |
+ TCPOPT_NOP << 8 | TCPOPT_NOP, ptr);
+ ptr += 1;
}
+mp_capable_done:
if (opts->ext_copy.use_ack || opts->ext_copy.use_map) {
struct mptcp_ext *mpext = &opts->ext_copy;
u8 len = TCPOLEN_MPTCP_DSS_BASE;
diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
index a355bb1cf31b..36b90024d34d 100644
--- a/net/mptcp/protocol.h
+++ b/net/mptcp/protocol.h
@@ -11,7 +11,7 @@
#include <net/tcp.h>
#include <net/inet_connection_sock.h>
-#define MPTCP_SUPPORTED_VERSION 0
+#define MPTCP_SUPPORTED_VERSION 1
/* MPTCP option bits */
#define OPTION_MPTCP_MPC_SYN BIT(0)
@@ -29,9 +29,10 @@
#define MPTCPOPT_MP_FASTCLOSE 7
/* MPTCP suboption lengths */
-#define TCPOLEN_MPTCP_MPC_SYN 12
+#define TCPOLEN_MPTCP_MPC_SYN 4
#define TCPOLEN_MPTCP_MPC_SYNACK 12
#define TCPOLEN_MPTCP_MPC_ACK 20
+#define TCPOLEN_MPTCP_MPC_ACK_DATA 22
#define TCPOLEN_MPTCP_DSS_BASE 4
#define TCPOLEN_MPTCP_DSS_ACK32 4
#define TCPOLEN_MPTCP_DSS_ACK64 8
@@ -106,6 +107,7 @@ struct mptcp_subflow_context {
u64 remote_key;
u64 idsn;
u64 map_seq;
+ u32 snd_isn;
u32 token;
u32 rel_write_seq;
u32 map_subflow_seq;
diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c
index 9fb3eb87a20f..8892855f4f52 100644
--- a/net/mptcp/subflow.c
+++ b/net/mptcp/subflow.c
@@ -77,7 +77,6 @@ static void subflow_init_req(struct request_sock *req,
if (err == 0)
subflow_req->mp_capable = 1;
- subflow_req->remote_key = rx_opt.mptcp.sndr_key;
subflow_req->ssn_offset = TCP_SKB_CB(skb)->seq;
}
}
@@ -180,11 +179,22 @@ static struct sock *subflow_syn_recv_sock(const struct sock *sk,
bool *own_req)
{
struct mptcp_subflow_context *listener = mptcp_subflow_ctx(sk);
+ struct mptcp_subflow_request_sock *subflow_req;
+ struct tcp_options_received opt_rx;
struct sock *child;
pr_debug("listener=%p, req=%p, conn=%p", listener, req, listener->conn);
- /* if the sk is MP_CAPABLE, we already received the client key */
+ /* if the sk is MP_CAPABLE, we need to fetch the client key */
+ subflow_req = mptcp_subflow_rsk(req);
+ if (subflow_req->mp_capable) {
+ opt_rx.mptcp.mp_capable = 0;
+ mptcp_get_options(skb, &opt_rx);
+ if (!opt_rx.mptcp.mp_capable)
+ subflow_req->mp_capable = 0;
+ else
+ subflow_req->remote_key = opt_rx.mptcp.sndr_key;
+ }
child = listener->icsk_af_ops->syn_recv_sock(sk, skb, req, dst,
req_unhash, own_req);
Copyright © 1996 – 2023 Jason A. Donenfeld. All Rights Reverse Engineered.