Commit c11c5906 authored by Florian Westphal's avatar Florian Westphal Committed by David S. Miller
Browse files

mptcp: add MPTCP_SUBFLOW_ADDRS getsockopt support 



This retrieves the address pairs of all subflows currently
active for a given mptcp connection.

It re-uses the same meta-header as for MPTCP_TCPINFO.

A new structure is provided to hold the subflow
address data:

struct mptcp_subflow_addrs {
	union {
		__kernel_sa_family_t sa_family;
		struct sockaddr sa_local;
		struct sockaddr_in sin_local;
		struct sockaddr_in6 sin6_local;
		struct sockaddr_storage ss_local;
	};
	union {
		struct sockaddr sa_remote;
		struct sockaddr_in sin_remote;
		struct sockaddr_in6 sin6_remote;
		struct sockaddr_storage ss_remote;
	};
};

Usage of the new getsockopt is very similar to
MPTCP_TCPINFO one.

Userspace allocates a
'struct mptcp_subflow_data', followed by one or
more 'struct mptcp_subflow_addrs', then inits the
mptcp_subflow_data structure as follows:

struct mptcp_subflow_addrs *sf_addr;
struct mptcp_subflow_data *addr;
socklen_t olen = sizeof(*addr) + (8 * sizeof(*sf_addr));

addr = malloc(olen);
addr->size_subflow_data = sizeof(*addr);
addr->num_subflows = 0;
addr->size_kernel = 0;
addr->size_user = sizeof(struct mptcp_subflow_addrs);

sf_addr = (struct mptcp_subflow_addrs *)(addr + 1);

and then retrieves the endpoint addresses via:
ret = getsockopt(fd, SOL_MPTCP, MPTCP_SUBFLOW_ADDRS,
		 addr, &olen);

If the call succeeds, kernel will have added up to 8
endpoint addresses after the 'mptcp_subflow_data' header.

Userspace needs to re-check 'olen' value to detect how
many bytes have been filled in by the kernel.

Userspace can check addr->num_subflows to discover when
there were more subflows that available data space.

Co-developed-by: default avatarMatthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: default avatarMatthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: default avatarFlorian Westphal <fw@strlen.de>
Signed-off-by: default avatarMat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 06f15cee

include/uapi/linux/mptcp.h

+24 −0
Original line number Diff line number Diff line
@@ -4,6 +4,13 @@ 


#include <linux/const.h>

#include <linux/types.h>

#include <linux/in.h>		/* for sockaddr_in			*/

#include <linux/in6.h>		/* for sockaddr_in6			*/

#include <linux/socket.h>	/* for sockaddr_storage and sa_family	*/



#ifndef __KERNEL__

#include <sys/socket.h>		/* for struct sockaddr			*/

#endif



#define MPTCP_SUBFLOW_FLAG_MCAP_REM		_BITUL(0)

#define MPTCP_SUBFLOW_FLAG_MCAP_LOC		_BITUL(1)
@@ -200,8 +207,25 @@ struct mptcp_subflow_data { 
	__u32		size_user;			/* size of one element in data[] */

} __attribute__((aligned(8)));



struct mptcp_subflow_addrs {

	union {

		__kernel_sa_family_t sa_family;

		struct sockaddr sa_local;

		struct sockaddr_in sin_local;

		struct sockaddr_in6 sin6_local;

		struct __kernel_sockaddr_storage ss_local;

	};

	union {

		struct sockaddr sa_remote;

		struct sockaddr_in sin_remote;

		struct sockaddr_in6 sin6_remote;

		struct __kernel_sockaddr_storage ss_remote;

	};

};



/* MPTCP socket options */

#define MPTCP_INFO		1

#define MPTCP_TCPINFO		2

#define MPTCP_SUBFLOW_ADDRS	3



#endif /* _UAPI_MPTCP_H */

net/mptcp/sockopt.c

+91 −0
Original line number Diff line number Diff line
@@ -840,6 +840,95 @@ static int mptcp_getsockopt_tcpinfo(struct mptcp_sock *msk, char __user *optval, 
	return 0;

}



static void mptcp_get_sub_addrs(const struct sock *sk, struct mptcp_subflow_addrs *a)

{

	struct inet_sock *inet = inet_sk(sk);



	memset(a, 0, sizeof(*a));



	if (sk->sk_family == AF_INET) {

		a->sin_local.sin_family = AF_INET;

		a->sin_local.sin_port = inet->inet_sport;

		a->sin_local.sin_addr.s_addr = inet->inet_rcv_saddr;



		if (!a->sin_local.sin_addr.s_addr)

			a->sin_local.sin_addr.s_addr = inet->inet_saddr;



		a->sin_remote.sin_family = AF_INET;

		a->sin_remote.sin_port = inet->inet_dport;

		a->sin_remote.sin_addr.s_addr = inet->inet_daddr;

#if IS_ENABLED(CONFIG_IPV6)

	} else if (sk->sk_family == AF_INET6) {

		const struct ipv6_pinfo *np = inet6_sk(sk);



		a->sin6_local.sin6_family = AF_INET6;

		a->sin6_local.sin6_port = inet->inet_sport;



		if (ipv6_addr_any(&sk->sk_v6_rcv_saddr))

			a->sin6_local.sin6_addr = np->saddr;

		else

			a->sin6_local.sin6_addr = sk->sk_v6_rcv_saddr;



		a->sin6_remote.sin6_family = AF_INET6;

		a->sin6_remote.sin6_port = inet->inet_dport;

		a->sin6_remote.sin6_addr = sk->sk_v6_daddr;

#endif

	}

}



static int mptcp_getsockopt_subflow_addrs(struct mptcp_sock *msk, char __user *optval,

					  int __user *optlen)

{

	struct sock *sk = &msk->sk.icsk_inet.sk;

	struct mptcp_subflow_context *subflow;

	unsigned int sfcount = 0, copied = 0;

	struct mptcp_subflow_data sfd;

	char __user *addrptr;

	int len;



	len = mptcp_get_subflow_data(&sfd, optval, optlen);

	if (len < 0)

		return len;



	sfd.size_kernel = sizeof(struct mptcp_subflow_addrs);

	sfd.size_user = min_t(unsigned int, sfd.size_user,

			      sizeof(struct mptcp_subflow_addrs));



	addrptr = optval + sfd.size_subflow_data;



	lock_sock(sk);



	mptcp_for_each_subflow(msk, subflow) {

		struct sock *ssk = mptcp_subflow_tcp_sock(subflow);



		++sfcount;



		if (len && len >= sfd.size_user) {

			struct mptcp_subflow_addrs a;



			mptcp_get_sub_addrs(ssk, &a);



			if (copy_to_user(addrptr, &a, sfd.size_user)) {

				release_sock(sk);

				return -EFAULT;

			}



			addrptr += sfd.size_user;

			copied += sfd.size_user;

			len -= sfd.size_user;

		}

	}



	release_sock(sk);



	sfd.num_subflows = sfcount;



	if (mptcp_put_subflow_data(&sfd, optval, copied, optlen))

		return -EFAULT;



	return 0;

}



static int mptcp_getsockopt_sol_tcp(struct mptcp_sock *msk, int optname,

				    char __user *optval, int __user *optlen)

{
@@ -862,6 +951,8 @@ static int mptcp_getsockopt_sol_mptcp(struct mptcp_sock *msk, int optname, 
		return mptcp_getsockopt_info(msk, optval, optlen);

	case MPTCP_TCPINFO:

		return mptcp_getsockopt_tcpinfo(msk, optval, optlen);

	case MPTCP_SUBFLOW_ADDRS:

		return mptcp_getsockopt_subflow_addrs(msk, optval, optlen);

	}



	return -EOPNOTSUPP;