[MPTCP] Re: [MPTCP][PATCH v3 mptcp-next 1/2] mptcp: convert IPv4 address with IPv4-mapped address

[MPTCP] Re: [MPTCP][PATCH v3 mptcp-next 1/2] mptcp: convert IPv4 address with IPv4-mapped address

[Mat Martineau]

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On Fri, 18 Dec 2020, Geliang Tang wrote:

> Currently, PM doesn't create subflow with IPv4-mapped IPv6 socket. This
> patch added IPv4-mapped Ipv6 address support, by converting the IPv4
> address with IPv4-mapped IPv6 address.
>
> Co-developed-by: Matthieu Baerts <matthieu.baerts(a)tessares.net>
> Signed-off-by: Matthieu Baerts <matthieu.baerts(a)tessares.net>
> Signed-off-by: Geliang Tang <geliangtang(a)gmail.com>
> ---
> net/mptcp/pm_netlink.c | 21 ++++++++++++---------
> net/mptcp/subflow.c    | 22 +++++++++++++++-------
> 2 files changed, 27 insertions(+), 16 deletions(-)
>
> diff --git a/net/mptcp/pm_netlink.c b/net/mptcp/pm_netlink.c
> index 9b1f6298bbdb..9c688023f494 100644
> --- a/net/mptcp/pm_netlink.c
> +++ b/net/mptcp/pm_netlink.c
> @@ -60,15 +60,19 @@ static bool addresses_equal(const struct mptcp_addr_info *a,
> {
> 	bool addr_equals = false;
>
> -	if (a->family != b->family)
> -		return false;
> -
> -	if (a->family == AF_INET)
> -		addr_equals = a->addr.s_addr == b->addr.s_addr;
> +	if (a->family == b->family) {
> +		if (a->family == AF_INET)
> +			addr_equals = a->addr.s_addr == b->addr.s_addr;
> #if IS_ENABLED(CONFIG_MPTCP_IPV6)
> -	else
> -		addr_equals = !ipv6_addr_cmp(&a->addr6, &b->addr6);
> +		else
> +			addr_equals = !ipv6_addr_cmp(&a->addr6, &b->addr6);
> +	} else {
> +		if (a->family == AF_INET && ipv6_addr_v4mapped(&b->addr6))
> +			addr_equals = a->addr.s_addr == b->addr6.s6_addr32[3];
> +		if (b->family == AF_INET && ipv6_addr_v4mapped(&a->addr6))
> +			addr_equals = a->addr6.s6_addr32[3] == b->addr.s_addr;
> #endif
> +	}
>
> 	if (!addr_equals)
> 		return false;
> @@ -147,8 +151,7 @@ select_local_address(const struct pm_nl_pernet *pernet,
> 		/* avoid any address already in use by subflows and
> 		 * pending join
> 		 */
> -		if (entry->addr.family == ((struct sock *)msk)->sk_family &&
> -		    !lookup_subflow_by_saddr(&msk->conn_list, &entry->addr)) {
> +		if (!lookup_subflow_by_saddr(&msk->conn_list, &entry->addr)) {
> 			ret = entry;
> 			break;
> 		}
> diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c
> index 278cbe3e539e..8586d95310e2 100644
> --- a/net/mptcp/subflow.c
> +++ b/net/mptcp/subflow.c
> @@ -1074,21 +1074,29 @@ void mptcpv6_handle_mapped(struct sock *sk, bool mapped)
> #endif
>
> static void mptcp_info2sockaddr(const struct mptcp_addr_info *info,
> -				struct sockaddr_storage *addr)
> +				struct sockaddr_storage *addr,
> +				unsigned short family)
> {
> 	memset(addr, 0, sizeof(*addr));
> -	addr->ss_family = info->family;
> +	addr->ss_family = family;
> 	if (addr->ss_family == AF_INET) {
> 		struct sockaddr_in *in_addr = (struct sockaddr_in *)addr;
>
> -		in_addr->sin_addr = info->addr;
> +		if (info->family == AF_INET)
> +			in_addr->sin_addr = info->addr;

> +		else
> +			in_addr->sin_addr.s_addr = info->addr6.s6_addr32[3];

One small fix - addr6 needs CONFIG_MPTCP_IPV6, this breaks non-IPv6 
builds.

The rest looks good to me! Tests pass on my system.

Mat


> 		in_addr->sin_port = info->port;
> 	}
> #if IS_ENABLED(CONFIG_MPTCP_IPV6)
> 	else if (addr->ss_family == AF_INET6) {
> 		struct sockaddr_in6 *in6_addr = (struct sockaddr_in6 *)addr;
>
> -		in6_addr->sin6_addr = info->addr6;
> +		if (info->family == AF_INET)
> +			ipv6_addr_set_v4mapped(info->addr.s_addr,
> +					       &in6_addr->sin6_addr);
> +		else
> +			in6_addr->sin6_addr = info->addr6;
> 		in6_addr->sin6_port = info->port;
> 	}
> #endif
> @@ -1132,11 +1140,11 @@ int __mptcp_subflow_connect(struct sock *sk, const struct mptcp_addr_info *loc,
> 	subflow->remote_key = msk->remote_key;
> 	subflow->local_key = msk->local_key;
> 	subflow->token = msk->token;
> -	mptcp_info2sockaddr(loc, &addr);
> +	mptcp_info2sockaddr(loc, &addr, ssk->sk_family);
>
> 	addrlen = sizeof(struct sockaddr_in);
> #if IS_ENABLED(CONFIG_MPTCP_IPV6)
> -	if (loc->family == AF_INET6)
> +	if (addr.ss_family == AF_INET6)
> 		addrlen = sizeof(struct sockaddr_in6);
> #endif
> 	ssk->sk_bound_dev_if = loc->ifindex;
> @@ -1152,7 +1160,7 @@ int __mptcp_subflow_connect(struct sock *sk, const struct mptcp_addr_info *loc,
> 	subflow->remote_id = remote_id;
> 	subflow->request_join = 1;
> 	subflow->request_bkup = !!(loc->flags & MPTCP_PM_ADDR_FLAG_BACKUP);
> -	mptcp_info2sockaddr(remote, &addr);
> +	mptcp_info2sockaddr(remote, &addr, ssk->sk_family);
>
> 	mptcp_add_pending_subflow(msk, subflow);
> 	err = kernel_connect(sf, (struct sockaddr *)&addr, addrlen, O_NONBLOCK);
> -- 
> 2.29.2
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>

--
Mat Martineau
Intel