From: Roy Marples <roy@marples.name>
Date: Fri, 19 Feb 2016 22:20:51 +0000 (+0000)
Subject: Enforce correctness of vltime, pltime, T1 and T2.
X-Git-Tag: v6.10.2~43
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=303c8d7c97b02353e99dc22effe410b08dd1a123;p=thirdparty%2Fdhcpcd.git

Enforce correctness of vltime, pltime, T1 and T2.
Warn about addresses expiring before T1.
If all addresses expire before T1, violate RFC 3315 22.4 and
present T1 and T2 are zero so dhcpcd will use sane defaults
based on the lowest vltime and pltime.

Fixes [004f2b78ed]
---

diff --git a/dhcp6.c b/dhcp6.c
index 67590e09..6e040818 100644
--- a/dhcp6.c
+++ b/dhcp6.c
@@ -1728,7 +1728,7 @@ dhcp6_findna(struct interface *ifp, uint16_t ot, const uint8_t *iaid,
 	char iabuf[INET6_ADDRSTRLEN];
 	const char *ia;
 	int i;
-	uint32_t u32;
+	uint32_t u32, pltime, vltime;
 	size_t off;
 	const struct dhcp6_ia_addr *iap;
 
@@ -1748,6 +1748,16 @@ dhcp6_findna(struct interface *ifp, uint16_t ot, const uint8_t *iaid,
 			continue;
 		}
 		iap = (const struct dhcp6_ia_addr *)D6_COPTION_DATA(o);
+		pltime = ntohl(iap->pltime);
+		vltime = ntohl(iap->vltime);
+		/* RFC 3315 22.6 */
+		if (pltime > vltime) {
+			errno = EINVAL;
+			logger(ifp->ctx, LOG_ERR,
+			    "%s: IA Address pltime %"PRIu32" > vltime %"PRIu32,
+			    ifp->name, pltime, vltime);
+			continue;
+		}
 		TAILQ_FOREACH(a, &state->addrs, next) {
 			if (ipv6_findaddrmatch(a, &iap->addr, 0))
 				break;
@@ -1787,11 +1797,10 @@ dhcp6_findna(struct interface *ifp, uint16_t ot, const uint8_t *iaid,
 			a->flags &= ~IPV6_AF_STALE;
 		}
 		a->acquired = *acquired;
-		a->prefix_pltime = ntohl(iap->pltime);
-		u32 = ntohl(iap->vltime);
-		if (a->prefix_vltime != u32) {
+		a->prefix_pltime = pltime;
+		if (a->prefix_vltime != vltime) {
 			a->flags |= IPV6_AF_NEW;
-			a->prefix_vltime = u32;
+			a->prefix_vltime = vltime;
 		}
 		if (a->prefix_pltime && a->prefix_pltime < state->lowpl)
 		    state->lowpl = a->prefix_pltime;
@@ -2022,6 +2031,16 @@ dhcp6_findia(struct interface *ifp, const struct dhcp6_message *m, size_t l,
 			rebind = ntohl(u32);
 			p += sizeof(u32);
 			ol = (uint16_t)(ol - sizeof(u32));
+
+			/* RFC 3315 22.4 */
+			if (rebind > 0 && renew > rebind) {
+				logger(ifp->ctx, LOG_WARNING,
+				    "%s: IAID %s T1 (%d) > T2 (%d) from %s",
+				    ifp->name,
+				    hwaddr_ntoa(iaid, sizeof(iaid), buf, sizeof(buf)),
+				    renew, rebind, sfrom);
+				continue;
+			}
 		} else
 			renew = rebind = 0; /* appease gcc */
 		if (dhcp6_checkstatusok(ifp, NULL, p, ol) == -1) {
@@ -2045,14 +2064,6 @@ dhcp6_findia(struct interface *ifp, const struct dhcp6_message *m, size_t l,
 			}
 		}
 		if (code != D6_OPTION_IA_TA) {
-			if (renew > rebind && rebind > 0) {
-				if (sfrom)
-				    logger(ifp->ctx, LOG_WARNING,
-					"%s: T1 (%d) > T2 (%d) from %s",
-					ifp->name, renew, rebind, sfrom);
-				renew = 0;
-				rebind = 0;
-			}
 			if (renew != 0 &&
 			    (renew < state->renew || state->renew == 0))
 				state->renew = renew;
@@ -2984,6 +2995,37 @@ recv:
 	case DH6S_CONFIRM:
 		if (state->reason == NULL)
 			state->reason = "REBOOT6";
+		if (state->renew != 0) {
+			int all_expired = 1;
+
+			TAILQ_FOREACH(ap, &state->addrs, next) { 
+				if (ap->prefix_vltime <= state->renew)
+					logger(ifp->ctx, LOG_WARNING,
+					    "%s: %s will expire before renewal",
+					    ifp->name, ap->saddr);
+				else
+					all_expired = 0;
+			}
+			if (all_expired) {
+				/* All address's vltime happens at or before
+				 * the configured T1 in the IA.
+				 * This is a badly configured server and we
+				 * have to use our own notion of what
+				 * T1 and T2 should be as a result.
+				 *
+				 * Doing this violates RFC 3315 22.4:
+				 * In a message sent by a server to a client,
+				 * the client MUST use the values in the T1
+				 * and T2 fields for the T1 and T2 parameters,
+				 * unless those values in those fields are 0.
+				 */
+				logger(ifp->ctx, LOG_WARNING,
+				    "%s: ignoring T1 %"PRIu32
+				    " to due address expiry",
+				    ifp->name, state->renew);
+				state->renew = state->rebind = 0;
+			}
+		}
 		if (state->renew == 0) {
 			if (state->expire == ND6_INFINITE_LIFETIME)
 				state->renew = ND6_INFINITE_LIFETIME;