Commit 27ab92d9 authored by Davide Caratti's avatar Davide Caratti Committed by David S. Miller
Browse files

mptcp: fix length of ADD_ADDR with port sub-option 



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: 22fb85ff ("mptcp: add port support for ADD_ADDR suboption writing")
CC: stable@vger.kernel.org # 5.11+
Reviewed-by: default avatarMat Martineau <mathew.j.martineau@linux.intel.com>
Acked-and-tested-by: default avatarGeliang Tang <geliangtang@gmail.com>
Signed-off-by: default avatarDavide Caratti <dcaratti@redhat.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 2055a99d

net/mptcp/protocol.h

+8 −6
Original line number Diff line number Diff line
@@ -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;

}