Commit d58300c3 authored by Davide Caratti's avatar Davide Caratti Committed by David S. Miller
Browse files

mptcp: validate 'id' when stopping the ADD_ADDR retransmit timer 



when Linux receives an echo-ed ADD_ADDR, it checks the IP address against
the list of "announced" addresses. In case of a positive match, the timer
that handles retransmissions is stopped regardless of the 'Address Id' in
the received packet: this behaviour does not comply with RFC8684 3.4.1.

Fix it by validating the 'Address Id' in received echo-ed ADD_ADDRs.
Tested using packetdrill, with the following captured output:

 unpatched kernel:

 Out <...> Flags [.], ack 1, win 256, options [mptcp add-addr v1 id 1 198.51.100.2 hmac 0xfd2e62517888fe29,mptcp dss ack 3007449509], length 0
 In  <...> Flags [.], ack 1, win 257, options [mptcp add-addr v1-echo id 1 1.2.3.4,mptcp dss ack 3013740213], length 0
 Out <...> Flags [.], ack 1, win 256, options [mptcp add-addr v1 id 1 198.51.100.2 hmac 0xfd2e62517888fe29,mptcp dss ack 3007449509], length 0
 In  <...> Flags [.], ack 1, win 257, options [mptcp add-addr v1-echo id 90 198.51.100.2,mptcp dss ack 3013740213], length 0
        ^^^ retransmission is stopped here, but 'Address Id' is 90

 patched kernel:

 Out <...> Flags [.], ack 1, win 256, options [mptcp add-addr v1 id 1 198.51.100.2 hmac 0x1cf372d59e05f4b8,mptcp dss ack 3007449509], length 0
 In  <...> Flags [.], ack 1, win 257, options [mptcp add-addr v1-echo id 1 1.2.3.4,mptcp dss ack 1672384568], length 0
 Out <...> Flags [.], ack 1, win 256, options [mptcp add-addr v1 id 1 198.51.100.2 hmac 0x1cf372d59e05f4b8,mptcp dss ack 3007449509], length 0
 In  <...> Flags [.], ack 1, win 257, options [mptcp add-addr v1-echo id 90 198.51.100.2,mptcp dss ack 1672384568], length 0
 Out <...> Flags [.], ack 1, win 256, options [mptcp add-addr v1 id 1 198.51.100.2 hmac 0x1cf372d59e05f4b8,mptcp dss ack 3007449509], length 0
 In  <...> Flags [.], ack 1, win 257, options [mptcp add-addr v1-echo id 1 198.51.100.2,mptcp dss ack 1672384568], length 0
        ^^^ retransmission is stopped here, only when both 'Address Id' and 'IP Address' match

Fixes: 00cfd77b ("mptcp: retransmit ADD_ADDR when timeout")
Signed-off-by: default avatarDavide Caratti <dcaratti@redhat.com>
Signed-off-by: default avatarMat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 3ed0a585

net/mptcp/options.c

+1 −1
Original line number Diff line number Diff line
@@ -1023,7 +1023,7 @@ void mptcp_incoming_options(struct sock *sk, struct sk_buff *skb) 
			MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_ADDADDR);

		} else {

			mptcp_pm_add_addr_echoed(msk, &mp_opt.addr);

			mptcp_pm_del_add_timer(msk, &mp_opt.addr);

			mptcp_pm_del_add_timer(msk, &mp_opt.addr, true);

			MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_ECHOADD);

		}

net/mptcp/pm_netlink.c

+4 −4
Original line number Diff line number Diff line
@@ -346,18 +346,18 @@ static void mptcp_pm_add_timer(struct timer_list *timer) 


struct mptcp_pm_add_entry *

mptcp_pm_del_add_timer(struct mptcp_sock *msk,

		       struct mptcp_addr_info *addr)

		       struct mptcp_addr_info *addr, bool check_id)

{

	struct mptcp_pm_add_entry *entry;

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



	spin_lock_bh(&msk->pm.lock);

	entry = mptcp_lookup_anno_list_by_saddr(msk, addr);

	if (entry)

	if (entry && (!check_id || entry->addr.id == addr->id))

		entry->retrans_times = ADD_ADDR_RETRANS_MAX;

	spin_unlock_bh(&msk->pm.lock);



	if (entry)

	if (entry && (!check_id || entry->addr.id == addr->id))

		sk_stop_timer_sync(sk, &entry->add_timer);



	return entry;
@@ -1064,7 +1064,7 @@ static bool remove_anno_list_by_saddr(struct mptcp_sock *msk, 
{

	struct mptcp_pm_add_entry *entry;



	entry = mptcp_pm_del_add_timer(msk, addr);

	entry = mptcp_pm_del_add_timer(msk, addr, false);

	if (entry) {

		list_del(&entry->list);

		kfree(entry);

net/mptcp/protocol.h

+1 −1
Original line number Diff line number Diff line
@@ -672,7 +672,7 @@ void mptcp_pm_free_anno_list(struct mptcp_sock *msk); 
bool mptcp_pm_sport_in_anno_list(struct mptcp_sock *msk, const struct sock *sk);

struct mptcp_pm_add_entry *

mptcp_pm_del_add_timer(struct mptcp_sock *msk,

		       struct mptcp_addr_info *addr);

		       struct mptcp_addr_info *addr, bool check_id);

struct mptcp_pm_add_entry *

mptcp_lookup_anno_list_by_saddr(struct mptcp_sock *msk,

				struct mptcp_addr_info *addr);