in current Linux, MPTCP peers advertising endpoints with port numbers use
a sub-option length that wrongly accounts for the trailing TCP NOP. Also,
receivers will only process incoming ADD_ADDR with port having such wrong
sub-option length. Fix this, making ADD_ADDR compliant to RFC8684 §3.4.1.
this can be verified running tcpdump on the kselftests artifacts:
unpatched kernel:
[root@bottarga mptcp]# tcpdump -tnnr unpatched.pcap | grep add-addr
reading from file unpatched.pcap, link-type LINUX_SLL (Linux cooked v1), snapshot length 65535
IP 10.0.1.1.10000 > 10.0.1.2.53078: Flags [.], ack 101, win 509, options [nop,nop,TS val 214459678 ecr 521312851,mptcp add-addr v1 id 1 a00:201:2774:2d88:7436:85c3:17fd:101], length 0
IP 10.0.1.2.53078 > 10.0.1.1.10000: Flags [.], ack 101, win 502, options [nop,nop,TS val 521312852 ecr 214459678,mptcp add-addr[bad opt]]
patched kernel:
[root@bottarga mptcp]# tcpdump -tnnr patched.pcap | grep add-addr
reading from file patched.pcap, link-type LINUX_SLL (Linux cooked v1), snapshot length 65535
IP 10.0.1.1.10000 > 10.0.1.2.38178: Flags [.], ack 101, win 509, options [nop,nop,TS val 3728873902 ecr 2732713192,mptcp add-addr v1 id 1 10.0.2.1:10100 hmac 0xbccdfcbe59292a1f,nop,nop], length 0
IP 10.0.1.2.38178 > 10.0.1.1.10000: Flags [.], ack 101, win 502, options [nop,nop,TS val 2732713195 ecr 3728873902,mptcp add-addr v1-echo id 1 10.0.2.1:10100,nop,nop], length 0
Fixes: 22fb85ffaefb ("mptcp: add port support for ADD_ADDR suboption writing")
CC: stable@xxxxxxxxxxxxxxx # 5.11+
Reviewed-by: Mat Martineau <mathew.j.martineau@xxxxxxxxxxxxxxx>
Acked-and-tested-by: Geliang Tang <geliangtang@xxxxxxxxx>
Signed-off-by: Davide Caratti <dcaratti@xxxxxxxxxx>
---
net/mptcp/protocol.h | 14 ++++++++------
1 file changed, 8 insertions(+), 6 deletions(-)
diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
index 91827d949766..e21a5bc36cf0 100644
--- a/net/mptcp/protocol.h
+++ b/net/mptcp/protocol.h
@@ -52,14 +52,15 @@
#define TCPOLEN_MPTCP_DSS_MAP64 14
#define TCPOLEN_MPTCP_DSS_CHECKSUM 2
#define TCPOLEN_MPTCP_ADD_ADDR 16
-#define TCPOLEN_MPTCP_ADD_ADDR_PORT 20
+#define TCPOLEN_MPTCP_ADD_ADDR_PORT 18
#define TCPOLEN_MPTCP_ADD_ADDR_BASE 8
-#define TCPOLEN_MPTCP_ADD_ADDR_BASE_PORT 12
+#define TCPOLEN_MPTCP_ADD_ADDR_BASE_PORT 10
#define TCPOLEN_MPTCP_ADD_ADDR6 28
-#define TCPOLEN_MPTCP_ADD_ADDR6_PORT 32
+#define TCPOLEN_MPTCP_ADD_ADDR6_PORT 30
#define TCPOLEN_MPTCP_ADD_ADDR6_BASE 20
-#define TCPOLEN_MPTCP_ADD_ADDR6_BASE_PORT 24
-#define TCPOLEN_MPTCP_PORT_LEN 4
+#define TCPOLEN_MPTCP_ADD_ADDR6_BASE_PORT 22
+#define TCPOLEN_MPTCP_PORT_LEN 2
+#define TCPOLEN_MPTCP_PORT_ALIGN 2
#define TCPOLEN_MPTCP_RM_ADDR_BASE 4
#define TCPOLEN_MPTCP_PRIO 3
#define TCPOLEN_MPTCP_PRIO_ALIGN 4
@@ -701,8 +702,9 @@ static inline unsigned int mptcp_add_addr_len(int family, bool echo, bool port)
len = TCPOLEN_MPTCP_ADD_ADDR6_BASE;
if (!echo)
len += MPTCPOPT_THMAC_LEN;
+ /* account for 2 trailing 'nop' options */
if (port)
- len += TCPOLEN_MPTCP_PORT_LEN;
+ len += TCPOLEN_MPTCP_PORT_LEN + TCPOLEN_MPTCP_PORT_ALIGN;
return len;
}
--
2.29.2
