conf, pasta: With --config-net, copy all addresses by default

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.

This option is introduced as deprecated right away: it's not expected
to be of any use, but it's helpful to keep it around for a while to
debug any suspected issue with this change.

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

conf.c

@@ -902,6 +902,8 @@ pasta_opts:
 	info(   "  --config-net		Configure tap interface in namespace");
 	info(   "  --no-copy-routes	DEPRECATED:");
 	info(   "			Don't copy all routes to namespace");
+	info(   "  --no-copy-addrs	DEPRECATED:");
+	info(   "			Don't copy all addresses to namespace");
 	info(   "  --ns-mac-addr ADDR	Set MAC address on tap interface");
 
 	exit(EXIT_FAILURE);
@@ -1178,6 +1180,7 @@ 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 };
@@ -1349,6 +1352,13 @@ void conf(struct ctx *c, int argc, char **argv)
 			warn("--no-copy-routes will be dropped soon");
 			c->no_copy_routes = 1;
 			break;
+		case 19:
+			if (c->mode != MODE_PASTA)
+				die("--no-copy-addrs is for pasta mode only");
+
+			warn("--no-copy-addrs will be dropped soon");
+			c->no_copy_addrs = 1;
+			break;
 		case 'd':
 			if (c->debug)
 				die("Multiple --debug options given");
@@ -1634,8 +1644,12 @@ 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)
+	if (c->mode == MODE_PASTA && !c->pasta_conf_ns) {
-		die("Option --no-copy-routes needs --config-net");
+		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);

passt.1

@@ -563,6 +563,20 @@ future version. It is not expected to be of any use, and it simply reflects a
 legacy behaviour. If you have any use for this, refer to \fBREPORTING BUGS\fR
 below.
 
+.TP
+.BR \-\-no-copy-addrs " " (DEPRECATED)
+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.
+
+Note that this configuration option is \fBdeprecated\fR and will be removed in a
+future version. It is not expected to be of any use, and it simply reflects a
+legacy behaviour. If you have any use for this, refer to \fBREPORTING BUGS\fR
+below.
+
 .TP
 .BR \-\-ns-mac-addr " " \fIaddr
 Configure MAC address \fIaddr\fR on the tap interface in the namespace.

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;

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);