Merge pull request #31314 from yuwata/network-ndisc-check-conflicting-address

network/ndisc: check conflicting address

src/network/networkd-address.c

@@ -516,11 +516,9 @@ static int address_compare_func(const Address *a1, const Address *a2) {
         }
 }
 
-static bool address_can_update(const Address *la, const Address *na) {
-        assert(la);
-        assert(la->link);
-        assert(na);
-        assert(na->network);
+bool address_can_update(const Address *existing, const Address *requesting) {
+        assert(existing);
+        assert(requesting);
 
         /*
          * property     |    IPv4     |  IPv6
@@ -545,32 +543,32 @@ static bool address_can_update(const Address *la, const Address *na) {
          * IPv6 : See inet6_addr_modify() in net/ipv6/addrconf.c.
          */
 
-        if (la->family != na->family)
+        if (existing->family != requesting->family)
                 return false;
 
-        if (la->prefixlen != na->prefixlen)
+        if (existing->prefixlen != requesting->prefixlen)
                 return false;
 
         /* When a null address is requested, the address to be assigned/updated will be determined later. */
-        if (!address_is_static_null(na) &&
-            in_addr_equal(la->family, &la->in_addr, &na->in_addr) <= 0)
+        if (!address_is_static_null(requesting) &&
+            in_addr_equal(existing->family, &existing->in_addr, &requesting->in_addr) <= 0)
                 return false;
 
-        switch (la->family) {
+        switch (existing->family) {
         case AF_INET: {
                 struct in_addr bcast;
 
-                if (la->scope != na->scope)
+                if (existing->scope != requesting->scope)
                         return false;
-                if (((la->flags ^ na->flags) & KNOWN_FLAGS & ~IPV6ONLY_FLAGS & ~UNMANAGED_FLAGS) != 0)
+                if (((existing->flags ^ requesting->flags) & KNOWN_FLAGS & ~IPV6ONLY_FLAGS & ~UNMANAGED_FLAGS) != 0)
                         return false;
-                if (!streq_ptr(la->label, na->label))
+                if (!streq_ptr(existing->label, requesting->label))
                         return false;
-                if (!in4_addr_equal(&la->in_addr_peer.in, &na->in_addr_peer.in))
+                if (!in4_addr_equal(&existing->in_addr_peer.in, &requesting->in_addr_peer.in))
                         return false;
-                if (address_get_broadcast(na, la->link, &bcast) >= 0) {
+                if (existing->link && address_get_broadcast(requesting, existing->link, &bcast) >= 0) {
                         /* If the broadcast address can be determined now, check if they match. */
-                        if (!in4_addr_equal(&la->broadcast, &bcast))
+                        if (!in4_addr_equal(&existing->broadcast, &bcast))
                                 return false;
                 } else {
                         /* When a null address is requested, then the broadcast address will be
@@ -578,7 +576,7 @@ static bool address_can_update(const Address *la, const Address *na) {
                          *     192.168.0.10/24 -> 192.168.0.255
                          * So, here let's only check if the broadcast is the last address in the range, e.g.
                          *     0.0.0.0/24 -> 0.0.0.255 */
-                        if (!FLAGS_SET(la->broadcast.s_addr, htobe32(UINT32_C(0xffffffff) >> la->prefixlen)))
+                        if (!FLAGS_SET(existing->broadcast.s_addr, htobe32(UINT32_C(0xffffffff) >> existing->prefixlen)))
                                 return false;
                 }
                 break;

src/network/networkd-address.h

@@ -85,6 +85,8 @@ void link_get_address_states(
 
 extern const struct hash_ops address_hash_ops;
 
+bool address_can_update(const Address *existing, const Address *requesting);
+
 Address* address_ref(Address *address);
 Address* address_unref(Address *address);
 

src/network/networkd-dhcp6.c

@@ -158,8 +158,7 @@ static int verify_dhcp6_address(Link *link, const Address *address) {
         } else
                 log_level = LOG_DEBUG;
 
-        if (address->prefixlen == existing->prefixlen)
-                /* Currently, only conflict in prefix length is reported. */
+        if (address_can_update(existing, address))
                 goto simple_log;
 
         if (existing->source == NETWORK_CONFIG_SOURCE_NDISC)

src/network/networkd-ndisc.c

@@ -249,8 +249,7 @@ static int ndisc_address_handler(sd_netlink *rtnl, sd_netlink_message *m, Reques
         return 1;
 }
 
-static int ndisc_request_address(Address *in, Link *link, sd_ndisc_router *rt) {
-        _cleanup_(address_unrefp) Address *address = in;
+static int ndisc_request_address(Address *address, Link *link, sd_ndisc_router *rt) {
         struct in6_addr router;
         bool is_new;
         int r;
@@ -270,7 +269,26 @@ static int ndisc_request_address(Address *in, Link *link, sd_ndisc_router *rt) {
         if (r < 0)
                 return r;
 
-        is_new = address_get(link, address, NULL) < 0;
+        Address *existing;
+        if (address_get_harder(link, address, &existing) < 0)
+                is_new = true;
+        else if (address_can_update(existing, address))
+                is_new = false;
+        else if (existing->source == NETWORK_CONFIG_SOURCE_DHCP6) {
+                /* SLAAC address is preferred over DHCPv6 address. */
+                log_link_debug(link, "Conflicting DHCPv6 address %s exists, removing.",
+                               IN_ADDR_PREFIX_TO_STRING(existing->family, &existing->in_addr, existing->prefixlen));
+                r = address_remove(existing, link);
+                if (r < 0)
+                        return r;
+
+                is_new = true;
+        } else {
+                /* Conflicting static address is configured?? */
+                log_link_debug(link, "Conflicting address %s exists, ignoring request.",
+                               IN_ADDR_PREFIX_TO_STRING(existing->family, &existing->in_addr, existing->prefixlen));
+                return 0;
+        }
 
         r = link_request_address(link, address, &link->ndisc_messages,
                                  ndisc_address_handler, NULL);
@@ -485,7 +503,7 @@ static int ndisc_router_process_autonomous_prefix(Link *link, sd_ndisc_router *r
                 address->lifetime_valid_usec = lifetime_valid_usec;
                 address->lifetime_preferred_usec = lifetime_preferred_usec;
 
-                r = ndisc_request_address(TAKE_PTR(address), link, rt);
+                r = ndisc_request_address(address, link, rt);
                 if (r < 0)
                         return log_link_warning_errno(link, r, "Could not request SLAAC address: %m");
         }