Commit 49243207 authored by Paolo Abeni's avatar Paolo Abeni Committed by Jakub Kicinski
Browse files

mptcp: introduce MPTCP_FULL_INFO getsockopt 

Some user-space applications want to monitor the subflows utilization.

Dumping the per subflow tcp_info is not enough, as the PM could close
and re-create the subflows under-the-hood, fooling the accounting.
Even checking the src/dst addresses used by each subflow could not
be enough, because new subflows could re-use the same address/port of
the just closed one.

This patch introduces a new socket option, allow dumping all the relevant
information all-at-once (everything, everywhere...), in a consistent
manner.

Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/388


Signed-off-by: default avatarPaolo Abeni <pabeni@redhat.com>
Reviewed-by: default avatarMatthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: default avatarMatthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent 6f06b4d4

include/uapi/linux/mptcp.h

+24 −0
Original line number Diff line number Diff line
@@ -249,9 +249,33 @@ struct mptcp_subflow_addrs { 
	};

};



struct mptcp_subflow_info {

	__u32				id;

	struct mptcp_subflow_addrs	addrs;

};



struct mptcp_full_info {

	__u32		size_tcpinfo_kernel;	/* must be 0, set by kernel */

	__u32		size_tcpinfo_user;

	__u32		size_sfinfo_kernel;	/* must be 0, set by kernel */

	__u32		size_sfinfo_user;

	__u32		num_subflows;		/* must be 0, set by kernel (real subflow count) */

	__u32		size_arrays_user;	/* max subflows that userspace is interested in;

						 * the buffers at subflow_info/tcp_info

						 * are respectively at least:

						 *  size_arrays * size_sfinfo_user

						 *  size_arrays * size_tcpinfo_user

						 * bytes wide

						 */

	__aligned_u64		subflow_info;

	__aligned_u64		tcp_info;

	struct mptcp_info	mptcp_info;

};



/* MPTCP socket options */

#define MPTCP_INFO		1

#define MPTCP_TCPINFO		2

#define MPTCP_SUBFLOW_ADDRS	3

#define MPTCP_FULL_INFO		4



#endif /* _UAPI_MPTCP_H */

net/mptcp/sockopt.c

+125 −2
Original line number Diff line number Diff line
@@ -15,6 +15,7 @@ 
#include "protocol.h"



#define MIN_INFO_OPTLEN_SIZE		16

#define MIN_FULL_INFO_OPTLEN_SIZE	40



static struct sock *__mptcp_tcp_fallback(struct mptcp_sock *msk)

{
@@ -981,7 +982,8 @@ static int mptcp_put_subflow_data(struct mptcp_subflow_data *sfd, 
}



static int mptcp_get_subflow_data(struct mptcp_subflow_data *sfd,

				  char __user *optval, int __user *optlen)

				  char __user *optval,

				  int __user *optlen)

{

	int len, copylen;
@@ -1162,6 +1164,125 @@ static int mptcp_getsockopt_subflow_addrs(struct mptcp_sock *msk, char __user *o 
	return 0;

}



static int mptcp_get_full_info(struct mptcp_full_info *mfi,

			       char __user *optval,

			       int __user *optlen)

{

	int len;



	BUILD_BUG_ON(offsetof(struct mptcp_full_info, mptcp_info) !=

		     MIN_FULL_INFO_OPTLEN_SIZE);



	if (get_user(len, optlen))

		return -EFAULT;



	if (len < MIN_FULL_INFO_OPTLEN_SIZE)

		return -EINVAL;



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

	if (copy_from_user(mfi, optval, MIN_FULL_INFO_OPTLEN_SIZE))

		return -EFAULT;



	if (mfi->size_tcpinfo_kernel ||

	    mfi->size_sfinfo_kernel ||

	    mfi->num_subflows)

		return -EINVAL;



	if (mfi->size_sfinfo_user > INT_MAX ||

	    mfi->size_tcpinfo_user > INT_MAX)

		return -EINVAL;



	return len - MIN_FULL_INFO_OPTLEN_SIZE;

}



static int mptcp_put_full_info(struct mptcp_full_info *mfi,

			       char __user *optval,

			       u32 copylen,

			       int __user *optlen)

{

	copylen += MIN_FULL_INFO_OPTLEN_SIZE;

	if (put_user(copylen, optlen))

		return -EFAULT;



	if (copy_to_user(optval, mfi, copylen))

		return -EFAULT;

	return 0;

}



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

				      int __user *optlen)

{

	unsigned int sfcount = 0, copylen = 0;

	struct mptcp_subflow_context *subflow;

	struct sock *sk = (struct sock *)msk;

	void __user *tcpinfoptr, *sfinfoptr;

	struct mptcp_full_info mfi;

	int len;



	len = mptcp_get_full_info(&mfi, optval, optlen);

	if (len < 0)

		return len;



	/* don't bother filling the mptcp info if there is not enough

	 * user-space-provided storage

	 */

	if (len > 0) {

		mptcp_diag_fill_info(msk, &mfi.mptcp_info);

		copylen += min_t(unsigned int, len, sizeof(struct mptcp_info));

	}



	mfi.size_tcpinfo_kernel = sizeof(struct tcp_info);

	mfi.size_tcpinfo_user = min_t(unsigned int, mfi.size_tcpinfo_user,

				      sizeof(struct tcp_info));

	sfinfoptr = u64_to_user_ptr(mfi.subflow_info);

	mfi.size_sfinfo_kernel = sizeof(struct mptcp_subflow_info);

	mfi.size_sfinfo_user = min_t(unsigned int, mfi.size_sfinfo_user,

				     sizeof(struct mptcp_subflow_info));

	tcpinfoptr = u64_to_user_ptr(mfi.tcp_info);



	lock_sock(sk);

	mptcp_for_each_subflow(msk, subflow) {

		struct sock *ssk = mptcp_subflow_tcp_sock(subflow);

		struct mptcp_subflow_info sfinfo;

		struct tcp_info tcp_info;



		if (sfcount++ >= mfi.size_arrays_user)

			continue;



		/* fetch addr/tcp_info only if the user space buffers

		 * are wide enough

		 */

		memset(&sfinfo, 0, sizeof(sfinfo));

		sfinfo.id = subflow->subflow_id;

		if (mfi.size_sfinfo_user >

		    offsetof(struct mptcp_subflow_info, addrs))

			mptcp_get_sub_addrs(ssk, &sfinfo.addrs);

		if (copy_to_user(sfinfoptr, &sfinfo, mfi.size_sfinfo_user))

			goto fail_release;



		if (mfi.size_tcpinfo_user) {

			tcp_get_info(ssk, &tcp_info);

			if (copy_to_user(tcpinfoptr, &tcp_info,

					 mfi.size_tcpinfo_user))

				goto fail_release;

		}



		tcpinfoptr += mfi.size_tcpinfo_user;

		sfinfoptr += mfi.size_sfinfo_user;

	}

	release_sock(sk);



	mfi.num_subflows = sfcount;

	if (mptcp_put_full_info(&mfi, optval, copylen, optlen))

		return -EFAULT;



	return 0;



fail_release:

	release_sock(sk);

	return -EFAULT;

}



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

				int __user *optlen, int val)

{
@@ -1235,6 +1356,8 @@ static int mptcp_getsockopt_sol_mptcp(struct mptcp_sock *msk, int optname, 
	switch (optname) {

	case MPTCP_INFO:

		return mptcp_getsockopt_info(msk, optval, optlen);

	case MPTCP_FULL_INFO:

		return mptcp_getsockopt_full_info(msk, optval, optlen);

	case MPTCP_TCPINFO:

		return mptcp_getsockopt_tcpinfo(msk, optval, optlen);

	case MPTCP_SUBFLOW_ADDRS: