Initial rewrite of NDP proxy
[project/odhcpd.git] / src / ndp.c
index 44884be..9840ed4 100644 (file)
--- a/src/ndp.c
+++ b/src/ndp.c
@@ -17,6 +17,7 @@
 #include <signal.h>
 #include <errno.h>
 
+#include <fcntl.h>
 #include <unistd.h>
 #include <arpa/inet.h>
 #include <sys/socket.h>
@@ -36,18 +37,11 @@ static void handle_solicit(void *addr, void *data, size_t len,
                struct interface *iface, void *dest);
 static void handle_rtnetlink(void *addr, void *data, size_t len,
                struct interface *iface, void *dest);
-static struct ndp_neighbor* find_neighbor(struct in6_addr *addr, bool strict);
-static void modify_neighbor(struct in6_addr *addr, struct interface *iface,
-               bool add);
 static ssize_t ping6(struct in6_addr *addr,
                const struct interface *iface);
 
-static struct list_head neighbors = LIST_HEAD_INIT(neighbors);
-static size_t neighbor_count = 0;
 static uint32_t rtnl_seqid = 0;
-
 static int ping_socket = -1;
-static struct odhcpd_event ndp_event = {{.fd = -1}, handle_solicit};
 static struct odhcpd_event rtnl_event = {{.fd = -1}, handle_rtnetlink};
 
 
@@ -116,105 +110,71 @@ int init_ndp(void)
        group = RTNLGRP_NEIGH;
        setsockopt(rtnl_event.uloop.fd, SOL_NETLINK, NETLINK_ADD_MEMBERSHIP, &group, sizeof(group));
 
-       // Synthesize initial neighbor events
-       struct {
-               struct nlmsghdr nh;
-               struct ndmsg ndm;
-       } req = {
-               {sizeof(req), RTM_GETNEIGH, NLM_F_REQUEST | NLM_F_DUMP,
-                               ++rtnl_seqid, 0},
-               {.ndm_family = AF_INET6}
-       };
-       send(rtnl_event.uloop.fd, &req, sizeof(req), MSG_DONTWAIT);
-
        return 0;
 }
 
 
 int setup_ndp_interface(struct interface *iface, bool enable)
 {
-       struct packet_mreq mreq = {iface->ifindex, PACKET_MR_ALLMULTI, ETH_ALEN, {0}};
-       setsockopt(ndp_event.uloop.fd, SOL_PACKET, PACKET_DROP_MEMBERSHIP, &mreq, sizeof(mreq));
-
-       struct ndp_neighbor *c, *n;
-       list_for_each_entry_safe(c, n, &neighbors, head)
-               if (c->iface == iface && (c->timeout == 0 || iface->ndp != RELAYD_RELAY || !enable))
-                       modify_neighbor(&c->addr, c->iface, false);
+       char procbuf[64];
+       snprintf(procbuf, sizeof(procbuf), "/proc/sys/net/ipv6/conf/%s/proxy_ndp", iface->ifname);
+       int procfd = open(procbuf, O_WRONLY);
 
-       if (enable && iface->ndp == RELAYD_RELAY) {
-               setsockopt(ndp_event.uloop.fd, SOL_PACKET, PACKET_ADD_MEMBERSHIP, &mreq, sizeof(mreq));
-
-               if (iface->static_ndp_len) {
-                       char *entry = alloca(iface->static_ndp_len), *saveptr;
-                       if (!entry) {
-                               syslog(LOG_ERR, "Alloca failed for static NDP list");
-                               return -1;
-                       }
-                       memcpy(entry, iface->static_ndp, iface->static_ndp_len);
-
-                       for (entry = strtok_r(entry, " ", &saveptr); entry; entry = strtok_r(NULL, " ", &saveptr)) {
-                               char *sep;
-                               struct ndp_neighbor *n = malloc(sizeof(*n));
-                               if (!n) {
-                                       syslog(LOG_ERR, "Malloc failed for static NDP-prefix %s", entry);
-                                       return -1;
-                               }
-
-                               n->iface = iface;
-                               n->timeout = 0;
-
-                               sep = strchr(entry, '/');
-                               if (!sep) {
-                                       free(n);
-                                       syslog(LOG_ERR, "Invalid static NDP-prefix %s", entry);
-                                       return -1;
-                               }
-                               
-                               *sep = 0;
-                               n->len = atoi(sep + 1);
-                               if (inet_pton(AF_INET6, entry, &n->addr) != 1 || n->len > 128) {
-                                       free(n);
-                                       syslog(LOG_ERR, "Invalid static NDP-prefix %s/%s", entry, sep + 1);
-                                       return -1;
-                               }
+       if (iface->ndp_event.uloop.fd >= 0) {
+               uloop_fd_delete(&iface->ndp_event.uloop);
+               close(iface->ndp_event.uloop.fd);
+               iface->ndp_event.uloop.fd = -1;
 
-                               list_add(&n->head, &neighbors);
-                       }
-               }
+               write(procfd, "0\n", 2);
        }
 
-       bool enable_packet = false;
-       struct interface *i;
-       list_for_each_entry(i, &interfaces, head) {
-               if (i == iface && !enable)
-                       continue;
-
-               if (i->ndp == RELAYD_RELAY)
-                       enable_packet = true;
-       }
+       if (enable && iface->ndp == RELAYD_RELAY) {
+               write(procfd, "1\n", 2);
 
-       if (enable_packet && ndp_event.uloop.fd < 0) {
-               // Create socket for intercepting NDP
-               int sock = socket(AF_PACKET, SOCK_DGRAM | SOCK_CLOEXEC | SOCK_NONBLOCK,
-                               htons(ETH_P_ALL)); // ETH_P_ALL for ingress + egress
+               int sock = socket(AF_PACKET, SOCK_DGRAM | SOCK_CLOEXEC, htons(ETH_P_IPV6));
                if (sock < 0) {
                        syslog(LOG_ERR, "Unable to open packet socket: %s",
                                        strerror(errno));
                        return -1;
                }
 
+#ifdef PACKET_RECV_TYPE
+               int pktt = 1 << PACKET_MULTICAST;
+               setsockopt(sock, SOL_PACKET, PACKET_RECV_TYPE, &pktt, sizeof(pktt));
+#endif
+
                if (setsockopt(sock, SOL_SOCKET, SO_ATTACH_FILTER,
                                &bpf_prog, sizeof(bpf_prog))) {
                        syslog(LOG_ERR, "Failed to set BPF: %s", strerror(errno));
                        return -1;
                }
 
-               ndp_event.uloop.fd = sock;
-               odhcpd_register(&ndp_event);
-       } else if (!enable_packet && ndp_event.uloop.fd >= 0) {
-               close(ndp_event.uloop.fd);
-               ndp_event.uloop.fd = -1;
+               struct sockaddr_ll ll = {
+                       .sll_family = AF_PACKET,
+                       .sll_ifindex = iface->ifindex,
+                       .sll_protocol = htons(ETH_P_IPV6),
+               };
+               bind(sock, (struct sockaddr*)&ll, sizeof(ll));
+
+               struct packet_mreq mreq = {iface->ifindex, PACKET_MR_ALLMULTI, ETH_ALEN, {0}};
+               setsockopt(sock, SOL_PACKET, PACKET_ADD_MEMBERSHIP, &mreq, sizeof(mreq));
+
+               iface->ndp_event.uloop.fd = sock;
+               iface->ndp_event.handle_dgram = handle_solicit;
+               odhcpd_register(&iface->ndp_event);
+
+               // Dump neighbor events
+               struct {
+                       struct nlmsghdr nh;
+                       struct ndmsg ndm;
+               } req = {
+                       {sizeof(req), RTM_GETNEIGH, NLM_F_REQUEST | NLM_F_DUMP,
+                                       ++rtnl_seqid, 0},
+                       {.ndm_family = AF_INET6}
+               };
+               send(rtnl_event.uloop.fd, &req, sizeof(req), MSG_DONTWAIT);
        }
+       close(procfd);
 
        return 0;
 }
@@ -266,61 +226,14 @@ static void handle_solicit(void *addr, void *data, size_t len,
 
        uint8_t mac[6];
        odhcpd_get_mac(iface, mac);
-       if (!memcmp(ll->sll_addr, mac, sizeof(mac)) &&
-                       ll->sll_pkttype != PACKET_OUTGOING)
+       if (!memcmp(ll->sll_addr, mac, sizeof(mac)))
                return; // Looped back
 
-       time_t now = time(NULL);
-
-       struct ndp_neighbor *n = find_neighbor(&req->nd_ns_target, false);
-       if (n && (n->iface || abs(n->timeout - now) < 5)) {
-               syslog(LOG_DEBUG, "%s is on %s", ipbuf,
-                               (n->iface) ? n->iface->ifname : "<pending>");
-               if (!n->iface || n->iface == iface)
-                       return;
-
-               // Found on other interface, answer with advertisement
-               struct {
-                       struct nd_neighbor_advert body;
-                       struct nd_opt_hdr opt_ll_hdr;
-                       uint8_t mac[6];
-               } advert = {
-                       .body = {
-                               .nd_na_hdr = {ND_NEIGHBOR_ADVERT,
-                                       0, 0, {{0}}},
-                               .nd_na_target = req->nd_ns_target,
-                       },
-                       .opt_ll_hdr = {ND_OPT_TARGET_LINKADDR, 1},
-               };
-
-               memcpy(advert.mac, mac, sizeof(advert.mac));
-               advert.body.nd_na_flags_reserved = ND_NA_FLAG_ROUTER |
-                               ND_NA_FLAG_SOLICITED;
-
-               struct sockaddr_in6 dest = {AF_INET6, 0, 0, ALL_IPV6_NODES, 0};
-               if (!ns_is_dad) // If not DAD, then unicast to source
-                       dest.sin6_addr = ip6->ip6_src;
-
-               // Linux seems to not honor IPV6_PKTINFO on raw-sockets, so work around
-               setsockopt(ping_socket, SOL_SOCKET, SO_BINDTODEVICE,
-                                       iface->ifname, sizeof(iface->ifname));
-               struct iovec iov = {&advert, sizeof(advert)};
-               odhcpd_send(ping_socket, &dest, &iov, 1, iface);
-       } else {
-               // Send echo to all other interfaces to see where target is on
-               // This will trigger neighbor discovery which is what we want.
-               // We will observe the neighbor cache to see results.
-
-               ssize_t sent = 0;
-               struct interface *c;
-               list_for_each_entry(c, &interfaces, head)
-                       if (iface->ndp == RELAYD_RELAY && iface != c &&
-                                       (!ns_is_dad || !c->external == false))
-                               sent += ping6(&req->nd_ns_target, c);
-
-               if (sent > 0) // Sent a ping, add pending neighbor entry
-                       modify_neighbor(&req->nd_ns_target, NULL, true);
-       }
+       struct interface *c;
+       list_for_each_entry(c, &interfaces, head)
+               if (iface->ndp == RELAYD_RELAY && iface != c &&
+                               (!ns_is_dad || !c->external == false))
+                       ping6(&req->nd_ns_target, c);
 }
 
 
@@ -384,74 +297,15 @@ static void setup_route(struct in6_addr *addr, struct interface *iface,
        odhcpd_setup_route(addr, 128, iface, NULL, add);
 }
 
-static void free_neighbor(struct ndp_neighbor *n)
-{
-       setup_route(&n->addr, n->iface, false);
-       list_del(&n->head);
-       free(n);
-       --neighbor_count;
-}
-
-static struct ndp_neighbor* find_neighbor(struct in6_addr *addr, bool strict)
-{
-       time_t now = time(NULL);
-       struct ndp_neighbor *n, *e;
-       list_for_each_entry_safe(n, e, &neighbors, head) {
-               if ((!strict && !odhcpd_bmemcmp(&n->addr, addr, n->len)) ||
-                               (n->len == 128 && IN6_ARE_ADDR_EQUAL(&n->addr, addr)))
-                       return n;
-
-               if (!n->iface && abs(n->timeout - now) >= 5)
-                       free_neighbor(n);
-       }
-       return NULL;
-}
-
-
-// Modified our own neighbor-entries
-static void modify_neighbor(struct in6_addr *addr,
-               struct interface *iface, bool add)
-{
-       if (!addr || (void*)addr == (void*)iface)
-               return;
-
-       struct ndp_neighbor *n = find_neighbor(addr, true);
-       if (!add) { // Delete action
-               if (n && (!n->iface || n->iface == iface))
-                       free_neighbor(n);
-       } else if (!n) { // No entry yet, add one if possible
-               if (neighbor_count >= NDP_MAX_NEIGHBORS ||
-                               !(n = malloc(sizeof(*n))))
-                       return;
-
-               n->len = 128;
-               n->addr = *addr;
-               n->iface = iface;
-               if (!n->iface)
-                       time(&n->timeout);
-               list_add(&n->head, &neighbors);
-               ++neighbor_count;
-               setup_route(addr, n->iface, add);
-       } else if (n->iface == iface) {
-               if (!n->iface)
-                       time(&n->timeout);
-       } else if (iface && (!n->iface ||
-                       (!iface->external && n->iface->external))) {
-               setup_route(addr, n->iface, false);
-               n->iface = iface;
-               setup_route(addr, n->iface, add);
-       }
-       // TODO: In case a host switches interfaces we might want
-       // to set its old neighbor entry to NUD_STALE and ping it
-       // on the old interface to confirm if the MACs match.
-}
-
 
 // Handler for neighbor cache entries from the kernel. This is our source
 // to learn and unlearn hosts on interfaces.
 static void handle_rtnetlink(_unused void *addr, void *data, size_t len,
                _unused struct interface *iface, _unused void *dest)
 {
+       bool dump_neigh = false;
+       struct in6_addr last_solicited = IN6ADDR_ANY_INIT;
+
        for (struct nlmsghdr *nh = data; NLMSG_OK(nh, len);
                        nh = NLMSG_NEXT(nh, len)) {
                struct rtmsg *rtm = NLMSG_DATA(nh);
@@ -506,8 +360,61 @@ static void handle_rtnetlink(_unused void *addr, void *data, size_t len,
                                (NUD_REACHABLE | NUD_STALE | NUD_DELAY | NUD_PROBE
                                                | NUD_PERMANENT | NUD_NOARP)));
 
-               if (iface->ndp == RELAYD_RELAY)
-                       modify_neighbor(addr, iface, add);
+               if (iface->ndp == RELAYD_RELAY) {
+                       // Replay change to all neighbor cache
+                       struct {
+                               struct nlmsghdr nh;
+                               struct ndmsg ndm;
+                               struct nlattr nla_dst;
+                               struct in6_addr dst;
+                       } req = {
+                               {sizeof(req), RTM_DELNEIGH, NLM_F_REQUEST,
+                                               ++rtnl_seqid, 0},
+                               {.ndm_family = AF_INET6, .ndm_flags = NTF_PROXY},
+                               {sizeof(struct nlattr) + sizeof(struct in6_addr), NDA_DST},
+                               *addr
+                       };
+
+                       if (add) {
+                               req.nh.nlmsg_type = RTM_NEWNEIGH;
+                               req.nh.nlmsg_flags |= NLM_F_CREATE;
+
+                               struct interface *c;
+                               list_for_each_entry(c, &interfaces, head) {
+                                       if (c->ndp == RELAYD_RELAY && iface != c) {
+                                               req.ndm.ndm_ifindex = c->ifindex;
+                                               send(rtnl_event.uloop.fd, &req, sizeof(req), MSG_DONTWAIT);
+                                       }
+                               }
+
+                               setup_route(addr, iface, true);
+                       } else {
+                               if (nh->nlmsg_type == RTM_NEWNEIGH) {
+                                       // might be locally originating
+                                       if (!IN6_ARE_ADDR_EQUAL(&last_solicited, addr)) {
+                                               last_solicited = *addr;
+
+                                               struct interface *c;
+                                               list_for_each_entry(c, &interfaces, head)
+                                                       if (iface->ndp == RELAYD_RELAY && iface != c &&
+                                                                       !c->external == false)
+                                                               ping6(addr, c);
+                                       }
+                               } else {
+                                       struct interface *c;
+                                       list_for_each_entry(c, &interfaces, head) {
+                                               if (c->ndp == RELAYD_RELAY && iface != c) {
+                                                       req.ndm.ndm_ifindex = c->ifindex;
+                                                       send(rtnl_event.uloop.fd, &req, sizeof(req), MSG_DONTWAIT);
+                                               }
+                                       }
+                                       setup_route(addr, iface, false);
+
+                                       // also: dump to add proxies back in case it moved elsewhere
+                                       dump_neigh = true;
+                               }
+                       }
+               }
 
                if (is_addr && iface->ra == RELAYD_SERVER)
                        raise(SIGUSR1); // Inform about a change in addresses
@@ -530,11 +437,17 @@ static void handle_rtnetlink(_unused void *addr, void *data, size_t len,
                                }
                        }
                }
+       }
 
-               /* TODO: See if this is required for optimal operation
-               // Keep neighbor entries alive so we don't loose routes
-                */
-               if (add && (ndm->ndm_state & NUD_STALE))
-                       ping6(addr, iface);
+       if (dump_neigh) {
+               struct {
+                       struct nlmsghdr nh;
+                       struct ndmsg ndm;
+               } req = {
+                       {sizeof(req), RTM_GETNEIGH, NLM_F_REQUEST | NLM_F_DUMP,
+                                       ++rtnl_seqid, 0},
+                       {.ndm_family = AF_INET6}
+               };
+               send(rtnl_event.uloop.fd, &req, sizeof(req), MSG_DONTWAIT);
        }
 }