Skip to content

Commit

Permalink
mptcp: validate 'id' when stopping the ADD_ADDR retransmit timer
Browse files Browse the repository at this point in the history
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: 00cfd77 ("mptcp: retransmit ADD_ADDR when timeout")
Signed-off-by: Davide Caratti <dcaratti@redhat.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
  • Loading branch information
Davide Caratti authored and David S. Miller committed May 25, 2021
1 parent 3ed0a58 commit d58300c
Show file tree
Hide file tree
Showing 3 changed files with 6 additions and 6 deletions.
2 changes: 1 addition & 1 deletion net/mptcp/options.c
Original file line number Diff line number Diff line change
Expand Up @@ -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);
}

Expand Down
8 changes: 4 additions & 4 deletions net/mptcp/pm_netlink.c
Original file line number Diff line number Diff line change
Expand Up @@ -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;
Expand Down Expand Up @@ -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);
Expand Down
2 changes: 1 addition & 1 deletion net/mptcp/protocol.h
Original file line number Diff line number Diff line change
Expand Up @@ -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);
Expand Down

0 comments on commit d58300c

Please sign in to comment.