Re: [PATCH v2 09/10] conf, pasta: With --config-net, copy all addresses by default

[David Gibson <david@gibson.dropbear.id.au>]

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On Mon, May 22, 2023 at 01:42:23AM +0200, Stefano Brivio wrote:
> Use the newly-introduced NL_DUP mode for nl_addr() to copy all the
> addresses associated to the template interface in the outer
> namespace, unless --no-copy-addrs (also implied by -a) is given.

Again, I'm always concerned by the addition of new command line
options.  Particularly in this case, where it looks like you can get
the same behaviour by using the right -a option.

> This is done mostly for consistency with routes. It might partially
> cover the issue at:
>   https://bugs.passt.top/show_bug.cgi?id=47
>   Support multiple addresses per address family
> 
> for some use cases, but not the originally intended one: we'll still
> use a single outbound address (unless the routing table specifies
> different preferred source addresses depending on the destination),
> regardless of the address used in the target namespace.
> 
> Link: https://bugs.passt.top/show_bug.cgi?id=47
> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

Logic looks sound though, so

Reviewed-by: David Gibson <david@gibson.dropbear.id.au>

> ---
>  conf.c  | 16 ++++++++++++++--
>  passt.1 |  9 +++++++++
>  passt.h |  2 ++
>  pasta.c |  5 +++--
>  4 files changed, 28 insertions(+), 4 deletions(-)
> 
> diff --git a/conf.c b/conf.c
> index 1ffd05c..e6c68e2 100644
> --- a/conf.c
> +++ b/conf.c
> @@ -901,6 +901,7 @@ pasta_opts:
>  	info(   "  			network namespace is deleted");
>  	info(   "  --config-net		Configure tap interface in namespace");
>  	info(   "  --no-copy-routes	Don't copy all routes to namespace");
> +	info(   "  --no-copy-addrs	Don't copy all addresses to namespace");
>  	info(   "  --ns-mac-addr ADDR	Set MAC address on tap interface");
>  
>  	exit(EXIT_FAILURE);
> @@ -1177,6 +1178,7 @@ void conf(struct ctx *c, int argc, char **argv)
>  		{"outbound-if6", required_argument,	NULL,		16 },
>  		{"config-net",	no_argument,		NULL,		17 },
>  		{"no-copy-routes", no_argument,		NULL,		18 },
> +		{"no-copy-addrs", no_argument,		NULL,		19 },
>  		{ 0 },
>  	};
>  	struct get_bound_ports_ns_arg ns_ports_arg = { .c = c };
> @@ -1347,6 +1349,12 @@ void conf(struct ctx *c, int argc, char **argv)
>  
>  			c->no_copy_routes = 1;
>  			break;
> +		case 19:
> +			if (c->mode != MODE_PASTA)
> +				die("--no-copy-addrs is for pasta mode only");
> +
> +			c->no_copy_addrs = 1;
> +			break;
>  		case 'd':
>  			if (c->debug)
>  				die("Multiple --debug options given");
> @@ -1632,8 +1640,12 @@ void conf(struct ctx *c, int argc, char **argv)
>  	if (*c->sock_path && c->fd_tap >= 0)
>  		die("Options --socket and --fd are mutually exclusive");
>  
> -	if (c->mode == MODE_PASTA && c->no_copy_routes && !c->pasta_conf_ns)
> -		die("Option --no-copy-routes needs --config-net");
> +	if (c->mode == MODE_PASTA && !c->pasta_conf_ns) {
> +		if (c->no_copy_routes)
> +			die("Option --no-copy-routes needs --config-net");
> +		if (c->no_copy_addrs)
> +			die("Option --no-copy-addrs needs --config-net");
> +	}
>  
>  	if (!ifi4 && *c->ip4.ifname_out)
>  		ifi4 = if_nametoindex(c->ip4.ifname_out);
> diff --git a/passt.1 b/passt.1
> index f965c34..87b076d 100644
> --- a/passt.1
> +++ b/passt.1
> @@ -558,6 +558,15 @@ Default is to copy all the routing entries from the interface in the outer
>  namespace to the target namespace, translating the output interface attribute to
>  the outbound interface in the namespace.
>  
> +.TP
> +.BR \-\-no-copy-addrs
> +With \-\-config-net, do not copy all the addresses associated to the interface
> +we derive addresses and routes from: set up a single one. Implied by \-a,
> +\-\-address.
> +
> +Default is to copy all the addresses, except for link-local ones, from the
> +interface from the outer namespace to the target namespace.
> +
>  .TP
>  .BR \-\-ns-mac-addr " " \fIaddr
>  Configure MAC address \fIaddr\fR on the tap interface in the namespace.
> diff --git a/passt.h b/passt.h
> index d314596..b51a1e5 100644
> --- a/passt.h
> +++ b/passt.h
> @@ -183,6 +183,7 @@ struct ip6_ctx {
>   * @pasta_ifn:		Index of namespace interface for pasta
>   * @pasta_conf_ns:	Configure namespace after creating it
>   * @no_copy_routes:	Don't copy all routes when configuring target namespace
> + * @no_copy_addrs:	Don't copy all addresses when configuring namespace
>   * @no_tcp:		Disable TCP operation
>   * @tcp:		Context for TCP protocol handler
>   * @no_tcp:		Disable UDP operation
> @@ -242,6 +243,7 @@ struct ctx {
>  	unsigned int pasta_ifi;
>  	int pasta_conf_ns;
>  	int no_copy_routes;
> +	int no_copy_addrs;
>  
>  	int no_tcp;
>  	struct tcp_ctx tcp;
> diff --git a/pasta.c b/pasta.c
> index 99ef3fc..4054e9a 100644
> --- a/pasta.c
> +++ b/pasta.c
> @@ -274,11 +274,12 @@ void pasta_ns_conf(struct ctx *c)
>  
>  	if (c->pasta_conf_ns) {
>  		enum nl_op op_routes = c->no_copy_routes ? NL_SET : NL_DUP;
> +		enum nl_op op_addrs =  c->no_copy_addrs  ? NL_SET : NL_DUP;
>  
>  		nl_link(1, c->pasta_ifi, c->mac_guest, 1, c->mtu);
>  
>  		if (c->ifi4) {
> -			nl_addr(NL_SET, c->ifi4, c->pasta_ifi, AF_INET,
> +			nl_addr(op_addrs, c->ifi4, c->pasta_ifi, AF_INET,
>  				&c->ip4.addr, &c->ip4.prefix_len, NULL);
>  			nl_route(op_routes, c->ifi4, c->pasta_ifi, AF_INET,
>  				 &c->ip4.gw);
> @@ -286,7 +287,7 @@ void pasta_ns_conf(struct ctx *c)
>  
>  		if (c->ifi6) {
>  			int prefix_len = 64;
> -			nl_addr(NL_SET, c->ifi6, c->pasta_ifi, AF_INET6,
> +			nl_addr(op_addrs, c->ifi6, c->pasta_ifi, AF_INET6,
>  				&c->ip6.addr, &prefix_len, NULL);
>  			nl_route(op_routes, c->ifi6, c->pasta_ifi, AF_INET6,
>  				 &c->ip6.gw);

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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