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-rw-r--r--epoll_type.h2
-rw-r--r--netlink.c201
-rw-r--r--netlink.h4
-rw-r--r--passt.c7
4 files changed, 211 insertions, 3 deletions
diff --git a/epoll_type.h b/epoll_type.h
index 12ac59b..a90ffb6 100644
--- a/epoll_type.h
+++ b/epoll_type.h
@@ -44,6 +44,8 @@ enum epoll_type {
EPOLL_TYPE_REPAIR_LISTEN,
/* TCP_REPAIR helper socket */
EPOLL_TYPE_REPAIR,
+ /* Netlink neighbour subscription socket */
+ EPOLL_TYPE_NL_NEIGH,
EPOLL_NUM_TYPES,
};
diff --git a/netlink.c b/netlink.c
index 9fe70f2..db4c9f8 100644
--- a/netlink.c
+++ b/netlink.c
@@ -26,6 +26,7 @@
#include <arpa/inet.h>
#include <netinet/in.h>
#include <netinet/if_ether.h>
+#include <net/if_arp.h>
#include <linux/netlink.h>
#include <linux/rtnetlink.h>
@@ -40,6 +41,10 @@
#define RTNH_NEXT_AND_DEC(rtnh, attrlen) \
((attrlen) -= RTNH_ALIGN((rtnh)->rtnh_len), RTNH_NEXT(rtnh))
+/* Convenience macro borrowed from kernel */
+#define NUD_VALID \
+ (NUD_PERMANENT | NUD_NOARP | NUD_REACHABLE | NUD_PROBE | NUD_STALE)
+
/* Netlink expects a buffer of at least 8kiB or the system page size,
* whichever is larger. 32kiB is recommended for more efficient.
* Since the largest page size on any remotely common Linux setup is
@@ -50,9 +55,10 @@
#define NLBUFSIZ 65536
/* Socket in init, in target namespace, sequence (just needs to be monotonic) */
-int nl_sock = -1;
-int nl_sock_ns = -1;
-static int nl_seq = 1;
+int nl_sock = -1;
+int nl_sock_ns = -1;
+static int nl_sock_neigh = -1;
+static int nl_seq = 1;
/**
* nl_sock_init_do() - Set up netlink sockets in init or target namespace
@@ -1103,3 +1109,192 @@ int nl_link_set_flags(int s, unsigned int ifi,
return nl_do(s, &req, RTM_NEWLINK, 0, sizeof(req));
}
+
+/**
+ * nl_neigh_msg_read() - Interpret a neighbour state message from netlink
+ * @c: Execution context
+ * @nh: Message to be read
+ */
+static void nl_neigh_msg_read(const struct ctx *c, struct nlmsghdr *nh)
+{
+ struct ndmsg *ndm = NLMSG_DATA(nh);
+ struct rtattr *rta = (struct rtattr *)(ndm + 1);
+ size_t na = NLMSG_PAYLOAD(nh, sizeof(*ndm));
+ char ip_str[INET6_ADDRSTRLEN];
+ char mac_str[ETH_ADDRSTRLEN];
+ const uint8_t *lladdr = NULL;
+ const void *dst = NULL;
+ size_t lladdr_len = 0;
+ union inany_addr addr;
+ size_t dstlen = 0;
+
+ if (nh->nlmsg_type == NLMSG_DONE)
+ return;
+
+ if (nh->nlmsg_type == NLMSG_ERROR) {
+ const struct nlmsgerr *errmsg = (struct nlmsgerr *)ndm;
+
+ warn("netlink error message on neighbour notifier: %s",
+ strerror_(-errmsg->error));
+ return;
+ }
+
+ if (nh->nlmsg_type != RTM_NEWNEIGH && nh->nlmsg_type != RTM_DELNEIGH)
+ return;
+
+ for (; RTA_OK(rta, na); rta = RTA_NEXT(rta, na)) {
+ if (rta->rta_type == NDA_DST) {
+ dst = RTA_DATA(rta);
+ dstlen = RTA_PAYLOAD(rta);
+ } else if (rta->rta_type == NDA_LLADDR) {
+ lladdr = RTA_DATA(rta);
+ lladdr_len = RTA_PAYLOAD(rta);
+ }
+ }
+
+ if (!dst)
+ return;
+
+ if (ndm->ndm_family == AF_INET && ndm->ndm_ifindex != c->ifi4)
+ return;
+
+ if (ndm->ndm_family == AF_INET6 && ndm->ndm_ifindex != c->ifi6)
+ return;
+
+ if (ndm->ndm_family != AF_INET && ndm->ndm_family != AF_INET6)
+ return;
+
+ if (ndm->ndm_family == AF_INET && dstlen != sizeof(struct in_addr)) {
+ warn("netlink: wrong address length in AF_INET notification");
+ return;
+ }
+ if (ndm->ndm_family == AF_INET6 && dstlen != sizeof(struct in6_addr)) {
+ warn("netlink: wrong address length in AF_INET6 notification");
+ return;
+ }
+ inany_from_af(&addr, ndm->ndm_family, dst);
+ inany_ntop(&addr, ip_str, sizeof(ip_str));
+
+ if (nh->nlmsg_type == RTM_DELNEIGH) {
+ trace("neighbour notifier delete: %s", ip_str);
+ return;
+ }
+ if (!(ndm->ndm_state & NUD_VALID)) {
+ trace("neighbour notifier: %s unreachable, state: 0x%04x",
+ ip_str, ndm->ndm_state);
+ return;
+ }
+ if (!lladdr) {
+ warn("RTM_NEWNEIGH %s: missing link layer address", ip_str);
+ return;
+ }
+ if (lladdr_len != ETH_ALEN || ndm->ndm_type != ARPHRD_ETHER)
+ return;
+
+ eth_ntop(lladdr, mac_str, sizeof(mac_str));
+ trace("neighbour notifier update: %s / %s", ip_str, mac_str);
+}
+
+/**
+ * nl_neigh_sync() - Read current contents of ARP/NDP tables
+ * @c: Execution context
+ * @proto: Protocol, AF_INET or AF_INET6
+ * @ifi: Interface index
+ */
+static void nl_neigh_sync(const struct ctx *c, int proto, int ifi)
+{
+ struct {
+ struct nlmsghdr nlh;
+ struct ndmsg ndm;
+ } req = {
+ .ndm.ndm_family = proto,
+ .ndm.ndm_ifindex = ifi,
+ };
+ struct nlmsghdr *nh;
+ char buf[NLBUFSIZ];
+ ssize_t status;
+ uint32_t seq;
+
+ seq = nl_send(nl_sock_neigh, &req, RTM_GETNEIGH,
+ NLM_F_DUMP, sizeof(req));
+ nl_foreach_oftype(nh, status, nl_sock_neigh, buf, seq, RTM_NEWNEIGH)
+ nl_neigh_msg_read(c, nh);
+ if (status < 0)
+ warn("netlink: RTM_GETNEIGH failed: %s", strerror_(-status));
+}
+
+/**
+ * nl_neigh_notify_handler() - Non-blocking drain of pending neighbour updates
+ * @c: Execution context
+ */
+void nl_neigh_notify_handler(const struct ctx *c)
+{
+ char buf[NLBUFSIZ];
+
+ for (;;) {
+ ssize_t n = recv(nl_sock_neigh, buf, sizeof(buf), MSG_DONTWAIT);
+ struct nlmsghdr *nh = (struct nlmsghdr *)buf;
+
+ if (n < 0) {
+ if (errno == EINTR)
+ continue;
+ if (errno != EAGAIN)
+ warn_perror("netlink notifier read error");
+ return;
+ }
+ for (; NLMSG_OK(nh, n); nh = NLMSG_NEXT(nh, n))
+ nl_neigh_msg_read(c, nh);
+ }
+}
+
+/**
+ * nl_neigh_notify_init() - Subscribe to neighbour events
+ * @c: Execution context
+ *
+ * Return: 0 on success, -1 on failure
+ */
+int nl_neigh_notify_init(const struct ctx *c)
+{
+ union epoll_ref ref = {
+ .type = EPOLL_TYPE_NL_NEIGH
+ };
+ struct epoll_event ev = {
+ .events = EPOLLIN
+ };
+ struct sockaddr_nl addr = {
+ .nl_family = AF_NETLINK,
+ .nl_groups = RTMGRP_NEIGH,
+ };
+
+ if (nl_sock_neigh >= 0) {
+ warn("netlink: neighbour notifier socket already exists");
+ return 0;
+ }
+
+ nl_sock_neigh = socket(AF_NETLINK, SOCK_RAW | SOCK_CLOEXEC,
+ NETLINK_ROUTE);
+ if (nl_sock_neigh < 0) {
+ warn_perror("Failed to create neighbour notifier socket");
+ return -1;
+ }
+
+ if (bind(nl_sock_neigh, (struct sockaddr *)&addr, sizeof(addr)) < 0) {
+ warn_perror("Failed to bind neighbour notifier socket");
+ close(nl_sock_neigh);
+ nl_sock_neigh = -1;
+ return -1;
+ }
+
+ ev.data.u64 = ref.u64;
+ if (epoll_ctl(c->epollfd, EPOLL_CTL_ADD, nl_sock_neigh, &ev) == -1) {
+ warn_perror("epoll_ctl() on neighbour notifier socket failed");
+ close(nl_sock_neigh);
+ nl_sock_neigh = -1;
+ return -1;
+ }
+
+ nl_neigh_sync(c, AF_INET, c->ifi4);
+ nl_neigh_sync(c, AF_INET6, c->ifi6);
+
+ return 0;
+}
diff --git a/netlink.h b/netlink.h
index b51e99c..8f1e9b9 100644
--- a/netlink.h
+++ b/netlink.h
@@ -17,6 +17,8 @@ int nl_route_dup(int s_src, unsigned int ifi_src,
int s_dst, unsigned int ifi_dst, sa_family_t af);
int nl_addr_get(int s, unsigned int ifi, sa_family_t af,
void *addr, int *prefix_len, void *addr_l);
+bool nl_neigh_mac_get(int s, const union inany_addr *addr, int ifi,
+ unsigned char *mac);
int nl_addr_set(int s, unsigned int ifi, sa_family_t af,
const void *addr, int prefix_len);
int nl_addr_get_ll(int s, unsigned int ifi, struct in6_addr *addr);
@@ -28,5 +30,7 @@ int nl_link_set_mac(int s, unsigned int ifi, const void *mac);
int nl_link_set_mtu(int s, unsigned int ifi, int mtu);
int nl_link_set_flags(int s, unsigned int ifi,
unsigned int set, unsigned int change);
+int nl_neigh_notify_init(const struct ctx *c);
+void nl_neigh_notify_handler(const struct ctx *c);
#endif /* NETLINK_H */
diff --git a/passt.c b/passt.c
index bdb7b69..a10e469 100644
--- a/passt.c
+++ b/passt.c
@@ -53,6 +53,7 @@
#include "vu_common.h"
#include "migrate.h"
#include "repair.h"
+#include "netlink.h"
#define NUM_EPOLL_EVENTS 8
@@ -79,6 +80,7 @@ char *epoll_type_str[] = {
[EPOLL_TYPE_VHOST_KICK] = "vhost-user kick socket",
[EPOLL_TYPE_REPAIR_LISTEN] = "TCP_REPAIR helper listening socket",
[EPOLL_TYPE_REPAIR] = "TCP_REPAIR helper socket",
+ [EPOLL_TYPE_NL_NEIGH] = "netlink neighbour notifier socket",
};
static_assert(ARRAY_SIZE(epoll_type_str) == EPOLL_NUM_TYPES,
"epoll_type_str[] doesn't match enum epoll_type");
@@ -322,6 +324,8 @@ int main(int argc, char **argv)
pcap_init(&c);
+ nl_neigh_notify_init(&c);
+
if (!c.foreground) {
if ((devnull_fd = open("/dev/null", O_RDWR | O_CLOEXEC)) < 0)
die_perror("Failed to open /dev/null");
@@ -414,6 +418,9 @@ loop:
case EPOLL_TYPE_REPAIR:
repair_handler(&c, eventmask);
break;
+ case EPOLL_TYPE_NL_NEIGH:
+ nl_neigh_notify_handler(&c);
+ break;
default:
/* Can't happen */
ASSERT(0);
generated by cgit v1.2.3 (git 2.25.1) at 2025-12-15 18:16:59 +0000