Subject: Re: [RFC net-next 07/13] selftests: ovpn: check asymmetric peer-id

From: Sabrina Dubroca <[email-masked]>
Date: Thu, 27 Nov 2025 01:13:37 +0100

2025-11-21, 01:20:38 +0100, Antonio Quartulli wrote:
> diff --git a/tools/testing/selftests/net/ovpn/common.sh b/tools/testing/selftests/net/ovpn/common.sh
> index b91cf17ab01f..d926413c9f16 100644
> --- a/tools/testing/selftests/net/ovpn/common.sh
> +++ b/tools/testing/selftests/net/ovpn/common.sh
> @@ -75,13 +75,14 @@ add_peer() {
>  					data64.key
>  			done
>  		else
> -			RADDR=$(awk "NR == ${1} {print \$2}" ${UDP_PEERS_FILE})
> -			RPORT=$(awk "NR == ${1} {print \$3}" ${UDP_PEERS_FILE})
> -			LPORT=$(awk "NR == ${1} {print \$5}" ${UDP_PEERS_FILE})
> -			ip netns exec peer${1} ${OVPN_CLI} new_peer tun${1} ${1} ${LPORT} \
> -				${RADDR} ${RPORT}
> -			ip netns exec peer${1} ${OVPN_CLI} new_key tun${1} ${1} 1 0 ${ALG} 1 \
> -				data64.key
> +			TX_ID=$(awk "NR == ${1} {print \$2}" ${UDP_PEERS_FILE})
> +			RADDR=$(awk "NR == ${1} {print \$3}" ${UDP_PEERS_FILE})
> +			RPORT=$(awk "NR == ${1} {print \$4}" ${UDP_PEERS_FILE})
> +			LPORT=$(awk "NR == ${1} {print \$6}" ${UDP_PEERS_FILE})
> +			ip netns exec peer${1} ${OVPN_CLI} new_peer tun${1} ${TX_ID} ${1} \
> +				${LPORT} ${RADDR} ${RPORT}
> +			ip netns exec peer${1} ${OVPN_CLI} new_key tun${1} ${TX_ID} 1 0 \
> +				${ALG} 1 data64.key

IIUC, we're creating a "client" with peer_id=$TX_ID and tx_id=$ID so
that they're flipped from what we installed on the multi-peer side?

> diff --git a/tools/testing/selftests/net/ovpn/ovpn-cli.c b/tools/testing/selftests/net/ovpn/ovpn-cli.c
> index 064453d16fdd..baabb4c9120e 100644
> --- a/tools/testing/selftests/net/ovpn/ovpn-cli.c
> +++ b/tools/testing/selftests/net/ovpn/ovpn-cli.c
> @@ -103,7 +103,7 @@ struct ovpn_ctx {
>  
>  	sa_family_t sa_family;
>  
> -	unsigned long peer_id;
> +	unsigned long peer_id, tx_id;
>  	unsigned long lport;
>  
>  	union {
> @@ -649,6 +649,7 @@ static int ovpn_new_peer(struct ovpn_ctx *ovpn, bool is_tcp)
>  
>  	attr = nla_nest_start(ctx->nl_msg, OVPN_A_PEER);
>  	NLA_PUT_U32(ctx->nl_msg, OVPN_A_PEER_ID, ovpn->peer_id);
> +	NLA_PUT_U32(ctx->nl_msg, OVPN_A_PEER_TX_ID, ovpn->tx_id);

So, with these changes, it's no longer possible to test a userspace
not passing the new OVPN_A_PEER_TX_ID attribute? But I guess we could
simulate that behavior by passing TX_ID==ID (is there still a test
doing that?).

Do we need to preserve some testing of the case where userspace is not
passing the new attribute?

>  	NLA_PUT_U32(ctx->nl_msg, OVPN_A_PEER_SOCKET, ovpn->socket);
>  
>  	if (!is_tcp) {
> @@ -767,6 +768,10 @@ static int ovpn_handle_peer(struct nl_msg *msg, void (*arg)__always_unused)
>  		fprintf(stderr, "* Peer %u\n",
>  			nla_get_u32(pattrs[OVPN_A_PEER_ID]));
>  
> +	if (pattrs[OVPN_A_PEER_TX_ID])
> +		fprintf(stderr, "\tTX peer ID %u\n",
> +			nla_get_u32(pattrs[OVPN_A_PEER_TX_ID]));
> +
>  	if (pattrs[OVPN_A_PEER_SOCKET_NETNSID])
>  		fprintf(stderr, "\tsocket NetNS ID: %d\n",
>  			nla_get_s32(pattrs[OVPN_A_PEER_SOCKET_NETNSID]));
> @@ -1676,11 +1681,13 @@ static void usage(const char *cmd)
>  		"\tkey_file: file containing the symmetric key for encryption\n");
>  
>  	fprintf(stderr,
> -		"* new_peer <iface> <peer_id> <lport> <raddr> <rport> [vpnaddr]: add new peer\n");
> +		"* new_peer <iface> <peer_id> <tx_id> <lport> <raddr> <rport> [vpnaddr]: add new peer\n");
>  	fprintf(stderr, "\tiface: ovpn interface name\n");
>  	fprintf(stderr, "\tlport: local UDP port to bind to\n");
>  	fprintf(stderr,
> -		"\tpeer_id: peer ID to be used in data packets to/from this peer\n");
> +		"\tpeer_id: peer ID found in data packets received from this peer\n");
> +	fprintf(stderr,
> +		"\ttx_id: peer ID to be used when sending to this peer\n");
>  	fprintf(stderr, "\traddr: peer IP address\n");
>  	fprintf(stderr, "\trport: peer UDP port\n");
>  	fprintf(stderr, "\tvpnaddr: peer VPN IP\n");
> @@ -1691,7 +1698,7 @@ static void usage(const char *cmd)
>  	fprintf(stderr, "\tlport: local UDP port to bind to\n");
>  	fprintf(stderr,
>  		"\tpeers_file: text file containing one peer per line. Line format:\n");
> -	fprintf(stderr, "\t\t<peer_id> <raddr> <rport> <vpnaddr>\n");
> +	fprintf(stderr, "\t\t<peer_id> <tx_id> <raddr> <rport> <laddr> <lport> <vpnaddr>\n");

Looks like this is missing similar updates for connect and listen,
based on changes to ovpn_run_cmd and ovpn_parse_cmd_args?

-- 
Sabrina