linux/include/net/mptcp.h
Florian Westphal c83a47e50d mptcp: subflow: add mptcp_subflow_init_cookie_req helper
Will be used to initialize the mptcp request socket when a MP_CAPABLE
request was handled in syncookie mode, i.e. when a TCP ACK containing a
MP_CAPABLE option is a valid syncookie value.

Normally (non-cookie case), MPTCP will generate a unique 32 bit connection
ID and stores it in the MPTCP token storage to be able to retrieve the
mptcp socket for subflow joining.

In syncookie case, we do not want to store any state, so just generate the
unique ID and use it in the reply.

This means there is a small window where another connection could generate
the same token.

When Cookie ACK comes back, we check that the token has not been registered
in the mean time.  If it was, the connection needs to fall back to TCP.

Changes in v2:
 - use req->syncookie instead of passing 'want_cookie' arg to ->init_req()
   (Eric Dumazet)

Signed-off-by: Florian Westphal <fw@strlen.de>
Reviewed-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2020-07-31 16:55:32 -07:00

224 lines
5.2 KiB
C

/* SPDX-License-Identifier: GPL-2.0 */
/*
* Multipath TCP
*
* Copyright (c) 2017 - 2019, Intel Corporation.
*/
#ifndef __NET_MPTCP_H
#define __NET_MPTCP_H
#include <linux/skbuff.h>
#include <linux/tcp.h>
#include <linux/types.h>
struct seq_file;
/* MPTCP sk_buff extension data */
struct mptcp_ext {
union {
u64 data_ack;
u32 data_ack32;
};
u64 data_seq;
u32 subflow_seq;
u16 data_len;
u8 use_map:1,
dsn64:1,
data_fin:1,
use_ack:1,
ack64:1,
mpc_map:1,
__unused:2;
/* one byte hole */
};
struct mptcp_out_options {
#if IS_ENABLED(CONFIG_MPTCP)
u16 suboptions;
u64 sndr_key;
u64 rcvr_key;
union {
struct in_addr addr;
#if IS_ENABLED(CONFIG_MPTCP_IPV6)
struct in6_addr addr6;
#endif
};
u8 addr_id;
u64 ahmac;
u8 rm_id;
u8 join_id;
u8 backup;
u32 nonce;
u64 thmac;
u32 token;
u8 hmac[20];
struct mptcp_ext ext_copy;
#endif
};
#ifdef CONFIG_MPTCP
extern struct request_sock_ops mptcp_subflow_request_sock_ops;
void mptcp_init(void);
static inline bool sk_is_mptcp(const struct sock *sk)
{
return tcp_sk(sk)->is_mptcp;
}
static inline bool rsk_is_mptcp(const struct request_sock *req)
{
return tcp_rsk(req)->is_mptcp;
}
static inline bool rsk_drop_req(const struct request_sock *req)
{
return tcp_rsk(req)->is_mptcp && tcp_rsk(req)->drop_req;
}
void mptcp_space(const struct sock *ssk, int *space, int *full_space);
bool mptcp_syn_options(struct sock *sk, const struct sk_buff *skb,
unsigned int *size, struct mptcp_out_options *opts);
bool mptcp_synack_options(const struct request_sock *req, unsigned int *size,
struct mptcp_out_options *opts);
bool mptcp_established_options(struct sock *sk, struct sk_buff *skb,
unsigned int *size, unsigned int remaining,
struct mptcp_out_options *opts);
void mptcp_incoming_options(struct sock *sk, struct sk_buff *skb,
struct tcp_options_received *opt_rx);
void mptcp_write_options(__be32 *ptr, struct mptcp_out_options *opts);
/* move the skb extension owership, with the assumption that 'to' is
* newly allocated
*/
static inline void mptcp_skb_ext_move(struct sk_buff *to,
struct sk_buff *from)
{
if (!skb_ext_exist(from, SKB_EXT_MPTCP))
return;
if (WARN_ON_ONCE(to->active_extensions))
skb_ext_put(to);
to->active_extensions = from->active_extensions;
to->extensions = from->extensions;
from->active_extensions = 0;
}
static inline bool mptcp_ext_matches(const struct mptcp_ext *to_ext,
const struct mptcp_ext *from_ext)
{
/* MPTCP always clears the ext when adding it to the skb, so
* holes do not bother us here
*/
return !from_ext ||
(to_ext && from_ext &&
!memcmp(from_ext, to_ext, sizeof(struct mptcp_ext)));
}
/* check if skbs can be collapsed.
* MPTCP collapse is allowed if neither @to or @from carry an mptcp data
* mapping, or if the extension of @to is the same as @from.
* Collapsing is not possible if @to lacks an extension, but @from carries one.
*/
static inline bool mptcp_skb_can_collapse(const struct sk_buff *to,
const struct sk_buff *from)
{
return mptcp_ext_matches(skb_ext_find(to, SKB_EXT_MPTCP),
skb_ext_find(from, SKB_EXT_MPTCP));
}
void mptcp_seq_show(struct seq_file *seq);
int mptcp_subflow_init_cookie_req(struct request_sock *req,
const struct sock *sk_listener,
struct sk_buff *skb);
#else
static inline void mptcp_init(void)
{
}
static inline bool sk_is_mptcp(const struct sock *sk)
{
return false;
}
static inline bool rsk_is_mptcp(const struct request_sock *req)
{
return false;
}
static inline bool rsk_drop_req(const struct request_sock *req)
{
return false;
}
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, const struct sk_buff *skb,
unsigned int *size,
struct mptcp_out_options *opts)
{
return false;
}
static inline bool mptcp_synack_options(const struct request_sock *req,
unsigned int *size,
struct mptcp_out_options *opts)
{
return false;
}
static inline bool mptcp_established_options(struct sock *sk,
struct sk_buff *skb,
unsigned int *size,
unsigned int remaining,
struct mptcp_out_options *opts)
{
return false;
}
static inline void mptcp_incoming_options(struct sock *sk,
struct sk_buff *skb,
struct tcp_options_received *opt_rx)
{
}
static inline void mptcp_skb_ext_move(struct sk_buff *to,
const struct sk_buff *from)
{
}
static inline bool mptcp_skb_can_collapse(const struct sk_buff *to,
const struct sk_buff *from)
{
return true;
}
static inline void mptcp_space(const struct sock *ssk, int *s, int *fs) { }
static inline void mptcp_seq_show(struct seq_file *seq) { }
static inline int mptcp_subflow_init_cookie_req(struct request_sock *req,
const struct sock *sk_listener,
struct sk_buff *skb)
{
return 0; /* TCP fallback */
}
#endif /* CONFIG_MPTCP */
#if IS_ENABLED(CONFIG_MPTCP_IPV6)
int mptcpv6_init(void);
void mptcpv6_handle_mapped(struct sock *sk, bool mapped);
#elif IS_ENABLED(CONFIG_IPV6)
static inline int mptcpv6_init(void) { return 0; }
static inline void mptcpv6_handle_mapped(struct sock *sk, bool mapped) { }
#endif
#endif /* __NET_MPTCP_H */