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

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commit d58300c3185b78ab910092488126b97f0abe3ae2 upstream.

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: 00cfd77b9063 ("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>
Stable-dep-of: b4cd80b03389 ("mptcp: pm: Fix uaf in __timer_delete_sync")
[ Conflicts in options.c, because some features are missing in this
  version, e.g. commit 557963c383e8 ("mptcp: move to next addr when
  subflow creation fail") and commit f7dafee18538 ("mptcp: use
  mptcp_addr_info in mptcp_options_received"). ]
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Davide Caratti 2024-09-17 09:26:10 +02:00 • committed by Ksawlii
parent 60be0592ec
commit f9df528cbf
3 changed files with 6 additions and 6 deletions
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2
net/mptcp/options.c
View file

@ -915,7 +915,7 @@ void mptcp_incoming_options(struct sock *sk, struct sk_buff *skb)
mptcp_pm_add_addr_received(msk, &addr);
MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_ADDADDR);
} else {
mptcp_pm_del_add_timer(msk, &addr);
mptcp_pm_del_add_timer(msk, &addr, true);
MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_ECHOADD);
}
mp_opt.add_addr = 0;

8
net/mptcp/pm_netlink.c
View file

@ -249,18 +249,18 @@ out:
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;
@ -764,7 +764,7 @@ 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);

2
net/mptcp/protocol.h
View file

@ -450,7 +450,7 @@ void mptcp_pm_rm_addr_received(struct mptcp_sock *msk, u8 rm_id);
void mptcp_pm_free_anno_list(struct mptcp_sock *msk);
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);