Implement RFC4941, Privacy Extensions for Stateless Address Autoconfiguration

in IPv6 when dhcpcd is overriding the in-kernel RA support.

For Linux kernels (3.18+) which support IFA_F_MANAGETEMPADDR the bulk of
this changeset is compiled out and the kernel will manage the temporary
addresses entirely.

For BSD, this is a fully compliant implementation with the caveat
that when dhcpcd is restarted the last non deprecated temp address on the
interface will be treated as being created when it was last updated
rather when it was actually added. Thus this may voilate section 3.3.
As dhcpcd won't restart in normal operation, this isn't an issue.

For Linux (3.18+) which supports IFA_F_MANAGETEMPADDR, the bulk of this
changeset is compiled out as the kernel will manage the temporary addresses.
For older Linux this is a fully compliant implementation with the caveat that
when restarted new temporary addresses will be generated.

Fixes [2ddfcb190f]

1 files changed, 37 insertions, 3 deletions

diff --git a/ipv6nd.c b/ipv6nd.c
index 51952f3d..ed9bb2cc 100644
--- a/ipv6nd.c
+++ b/ipv6nd.c
@@ -691,7 +691,7 @@ ipv6nd_handlera(struct ipv6_ctx *ctx, struct interface *ifp,
 	struct ipv6_addr *ap;
 	char *opt, *opt2, *tmp;
 	struct timeval expire;
-	uint8_t new_rap, new_data;
+	uint8_t new_rap, new_data, new_ap;
 
 	if (len < sizeof(struct nd_router_advert)) {
 		syslog(LOG_ERR, "IPv6 RA packet too short from %s", ctx->sfrom);
@@ -793,6 +793,7 @@ ipv6nd_handlera(struct ipv6_ctx *ctx, struct interface *ifp,
 	if (rap->lifetime)
 		rap->expired = 0;
 
+	ipv6_settempstale(ifp);
 	TAILQ_FOREACH(ap, &rap->addrs, next) {
 		ap->flags |= IPV6_AF_STALE;
 	}
@@ -894,13 +895,27 @@ ipv6nd_handlera(struct ipv6_ctx *ctx, struct interface *ifp,
 					ap->saddr[0] = '\0';
 				}
 				ap->dadcallback = ipv6nd_dadcallback;
+				ap->created = ap->acquired = rap->received;
 				TAILQ_INSERT_TAIL(&rap->addrs, ap, next);
-			} else
+
+				/* New address to dhcpcd RA handling.
+				 * If the address already exists and a valid
+				 * temporary address also exists then
+				 * extend the existing one rather than
+				 * create a new one */
+				if (ipv6_iffindaddr(ifp, &ap->addr) &&
+				    ipv6_settemptime(ap, 0))
+					new_ap = 0;
+				else
+					new_ap = 1;
+			} else {
+				new_ap = 0;
 				ap->flags &= ~IPV6_AF_STALE;
+				ap->acquired = rap->received;
+			}
 			if (pi->nd_opt_pi_flags_reserved &
 			    ND_OPT_PI_FLAG_ONLINK)
 				ap->flags |= IPV6_AF_ONLINK;
-			ap->acquired = rap->received;
 			ap->prefix_vltime =
 			    ntohl(pi->nd_opt_pi_valid_time);
 			ap->prefix_pltime =
@@ -916,6 +931,24 @@ ipv6nd_handlera(struct ipv6_ctx *ctx, struct interface *ifp,
 					opt2 = strdup(ap->saddr);
 				}
 			}
+
+			/* RFC4941 Section 3.3.3 */
+			if (ap->flags & IPV6_AF_AUTOCONF &&
+			    ap->iface->options->options & DHCPCD_IPV6RA_OWN &&
+			    ip6_use_tempaddr(ap->iface->name))
+			{
+				if (!new_ap) {
+					if (ipv6_settemptime(ap, 1) == NULL)
+						new_ap = 1;
+				}
+				if (new_ap && ap->prefix_pltime) {
+					if (ipv6_createtempaddr(ap,
+					    &ap->acquired) == NULL)
+						syslog(LOG_ERR,
+						    "ipv6_createtempaddr: %m");
+				}
+			}
+
 			lifetime = ap->prefix_vltime;
 			break;
 
@@ -1067,6 +1100,7 @@ extra_opt:
 		goto handle_flag;
 	}
 	ipv6_addaddrs(&rap->addrs);
+	ipv6_addtempaddrs(ifp, &rap->received);
 	ipv6_buildroutes(ifp->ctx);
 	if (ipv6nd_scriptrun(rap))
 		return;