As preparation for supporting multiple addresses per interface, we replace the single addr/prefix_len fields with arrays. - We add an ip4_addr_entry and an ip6_addr_entry struct containing address and prefix length. - We set the array sizes to IP4_MAX_ADDRS=8 and IP6_MAX_ADDRS=16, respectively. The only functional change is that the IPv6 prefix length now is properly stored instead of being hardcoded to 64 even when set via the -a option. Signed-off-by: Jon Maloy --- arp.c | 4 +-- conf.c | 97 +++++++++++++++++++++++++++++++++----------------------- dhcp.c | 8 ++--- dhcpv6.c | 6 ++-- fwd.c | 12 +++---- ip.h | 26 +++++++++++++++ ndp.c | 6 ++-- passt.h | 16 ++++++---- pasta.c | 12 ++++--- tap.c | 4 +-- util.h | 1 + 11 files changed, 122 insertions(+), 70 deletions(-) diff --git a/arp.c b/arp.c index bb042e9..7eaf517 100644 --- a/arp.c +++ b/arp.c @@ -54,7 +54,7 @@ static bool ignore_arp(const struct ctx *c, return true; /* Don't resolve the guest's assigned address, either. */ - if (!memcmp(am->tip, &c->ip4.addr, sizeof(am->tip))) + if (!memcmp(am->tip, &c->ip4.addrs[0].addr, sizeof(am->tip))) return true; return false; @@ -145,7 +145,7 @@ void arp_send_init_req(const struct ctx *c) memcpy(req.am.sha, c->our_tap_mac, sizeof(req.am.sha)); memcpy(req.am.sip, &c->ip4.our_tap_addr, sizeof(req.am.sip)); memcpy(req.am.tha, MAC_BROADCAST, sizeof(req.am.tha)); - memcpy(req.am.tip, &c->ip4.addr, sizeof(req.am.tip)); + memcpy(req.am.tip, &c->ip4.addrs[0].addr, sizeof(req.am.tip)); debug("Sending initial ARP request for guest MAC address"); tap_send_single(c, &req, sizeof(req)); diff --git a/conf.c b/conf.c index fdc19e8..0e96f36 100644 --- a/conf.c +++ b/conf.c @@ -694,10 +694,12 @@ static int conf_ip4_prefix(const char *arg) * conf_ip4() - Verify or detect IPv4 support, get relevant addresses * @ifi: Host interface to attempt (0 to determine one) * @ip4: IPv4 context (will be written) + * @permanent: Mark configured addresses as permanent * * Return: interface index for IPv4, or 0 on failure. */ -static unsigned int conf_ip4(unsigned int ifi, struct ip4_ctx *ip4) +static unsigned int conf_ip4(unsigned int ifi, struct ip4_ctx *ip4, + bool permanent) { if (!ifi) ifi = nl_get_ext_if(nl_sock, AF_INET); @@ -717,33 +719,38 @@ static unsigned int conf_ip4(unsigned int ifi, struct ip4_ctx *ip4) } } - if (IN4_IS_ADDR_UNSPECIFIED(&ip4->addr)) { + if (!ip4->addr_count) { int rc = nl_addr_get(nl_sock, ifi, AF_INET, - &ip4->addr, &ip4->prefix_len, NULL); + &ip4->addrs[0].addr, + &ip4->addrs[0].prefix_len, NULL); if (rc < 0) { debug("Couldn't discover IPv4 address: %s", strerror_(-rc)); return 0; } + ip4->addrs[0].permanent = permanent; + ip4->addr_count = 1; } - if (!ip4->prefix_len) { - in_addr_t addr = ntohl(ip4->addr.s_addr); - if (IN_CLASSA(addr)) - ip4->prefix_len = (32 - IN_CLASSA_NSHIFT); - else if (IN_CLASSB(addr)) - ip4->prefix_len = (32 - IN_CLASSB_NSHIFT); - else if (IN_CLASSC(addr)) - ip4->prefix_len = (32 - IN_CLASSC_NSHIFT); + /* Apply default prefix_len to first address if not set */ + if (!ip4->addrs[0].prefix_len) { + in_addr_t a = ntohl(ip4->addrs[0].addr.s_addr); + + if (IN_CLASSA(a)) + ip4->addrs[0].prefix_len = 8; + else if (IN_CLASSB(a)) + ip4->addrs[0].prefix_len = 16; + else if (IN_CLASSC(a)) + ip4->addrs[0].prefix_len = 24; else - ip4->prefix_len = 32; + ip4->addrs[0].prefix_len = 32; } - ip4->addr_seen = ip4->addr; + ip4->addr_seen = ip4->addrs[0].addr; ip4->our_tap_addr = ip4->guest_gw; - if (IN4_IS_ADDR_UNSPECIFIED(&ip4->addr)) + if (IN4_IS_ADDR_UNSPECIFIED(&ip4->addrs[0].addr)) return 0; return ifi; @@ -755,9 +762,9 @@ static unsigned int conf_ip4(unsigned int ifi, struct ip4_ctx *ip4) */ static void conf_ip4_local(struct ip4_ctx *ip4) { - ip4->addr_seen = ip4->addr = IP4_LL_GUEST_ADDR; + ip4->addr_seen = ip4->addrs[0].addr = IP4_LL_GUEST_ADDR; ip4->our_tap_addr = ip4->guest_gw = IP4_LL_GUEST_GW; - ip4->prefix_len = IP4_LL_PREFIX_LEN; + ip4->addrs[0].prefix_len = IP4_LL_PREFIX_LEN; ip4->no_copy_addrs = ip4->no_copy_routes = true; } @@ -766,10 +773,12 @@ static void conf_ip4_local(struct ip4_ctx *ip4) * conf_ip6() - Verify or detect IPv6 support, get relevant addresses * @ifi: Host interface to attempt (0 to determine one) * @ip6: IPv6 context (will be written) + * @permanent: Mark discovered addresses as permanent * * Return: interface index for IPv6, or 0 on failure. */ -static unsigned int conf_ip6(unsigned int ifi, struct ip6_ctx *ip6) +static unsigned int conf_ip6(unsigned int ifi, struct ip6_ctx *ip6, + bool permanent) { int prefix_len = 0; int rc; @@ -792,19 +801,25 @@ static unsigned int conf_ip6(unsigned int ifi, struct ip6_ctx *ip6) } rc = nl_addr_get(nl_sock, ifi, AF_INET6, - IN6_IS_ADDR_UNSPECIFIED(&ip6->addr) ? &ip6->addr : NULL, + ip6->addr_count ? NULL : &ip6->addrs[0].addr, &prefix_len, &ip6->our_tap_ll); if (rc < 0) { debug("Couldn't discover IPv6 address: %s", strerror_(-rc)); return 0; } - ip6->addr_seen = ip6->addr; + if (!ip6->addr_count) { + ip6->addrs[0].prefix_len = prefix_len ? prefix_len : 64; + ip6->addrs[0].permanent = permanent; + ip6->addr_count = 1; + } + + ip6->addr_seen = ip6->addrs[0].addr; if (IN6_IS_ADDR_LINKLOCAL(&ip6->guest_gw)) ip6->our_tap_ll = ip6->guest_gw; - if (IN6_IS_ADDR_UNSPECIFIED(&ip6->addr) || + if (IN6_IS_ADDR_UNSPECIFIED(&ip6->addrs[0].addr) || IN6_IS_ADDR_UNSPECIFIED(&ip6->our_tap_ll)) return 0; @@ -1149,11 +1164,13 @@ static void conf_print(const struct ctx *c) if (!c->no_dhcp) { uint32_t mask; - mask = htonl(0xffffffff << (32 - c->ip4.prefix_len)); + mask = htonl(0xffffffff << + (32 - c->ip4.addrs[0].prefix_len)); info("DHCP:"); info(" assign: %s", - inet_ntop(AF_INET, &c->ip4.addr, buf4, sizeof(buf4))); + inet_ntop(AF_INET, &c->ip4.addrs[0].addr, + buf4, sizeof(buf4))); info(" mask: %s", inet_ntop(AF_INET, &mask, buf4, sizeof(buf4))); info(" router: %s", @@ -1191,7 +1208,8 @@ static void conf_print(const struct ctx *c) goto dns6; info(" assign: %s", - inet_ntop(AF_INET6, &c->ip6.addr, buf6, sizeof(buf6))); + inet_ntop(AF_INET6, &c->ip6.addrs[0].addr, + buf6, sizeof(buf6))); info(" router: %s", inet_ntop(AF_INET6, &c->ip6.guest_gw, buf6, sizeof(buf6))); info(" our link-local: %s", @@ -1812,22 +1830,23 @@ void conf(struct ctx *c, int argc, char **argv) break; } case 'a': - if (inet_pton(AF_INET6, optarg, &c->ip6.addr) && - !IN6_IS_ADDR_UNSPECIFIED(&c->ip6.addr) && - !IN6_IS_ADDR_LOOPBACK(&c->ip6.addr) && - !IN6_IS_ADDR_V4MAPPED(&c->ip6.addr) && - !IN6_IS_ADDR_V4COMPAT(&c->ip6.addr) && - !IN6_IS_ADDR_MULTICAST(&c->ip6.addr)) { + if (inet_pton(AF_INET6, optarg, + &c->ip6.addrs[0].addr) && + !IN6_IS_ADDR_UNSPECIFIED(&c->ip6.addrs[0].addr) && + !IN6_IS_ADDR_LOOPBACK(&c->ip6.addrs[0].addr) && + !IN6_IS_ADDR_V4MAPPED(&c->ip6.addrs[0].addr) && + !IN6_IS_ADDR_V4COMPAT(&c->ip6.addrs[0].addr) && + !IN6_IS_ADDR_MULTICAST(&c->ip6.addrs[0].addr)) { if (c->mode == MODE_PASTA) c->ip6.no_copy_addrs = true; break; } - if (inet_pton(AF_INET, optarg, &c->ip4.addr) && - !IN4_IS_ADDR_UNSPECIFIED(&c->ip4.addr) && - !IN4_IS_ADDR_BROADCAST(&c->ip4.addr) && - !IN4_IS_ADDR_LOOPBACK(&c->ip4.addr) && - !IN4_IS_ADDR_MULTICAST(&c->ip4.addr)) { + if (inet_pton(AF_INET, optarg, &c->ip4.addrs[0].addr) && + !IN4_IS_ADDR_UNSPECIFIED(&c->ip4.addrs[0].addr) && + !IN4_IS_ADDR_BROADCAST(&c->ip4.addrs[0].addr) && + !IN4_IS_ADDR_LOOPBACK(&c->ip4.addrs[0].addr) && + !IN4_IS_ADDR_MULTICAST(&c->ip4.addrs[0].addr)) { if (c->mode == MODE_PASTA) c->ip4.no_copy_addrs = true; break; @@ -1836,8 +1855,8 @@ void conf(struct ctx *c, int argc, char **argv) die("Invalid address: %s", optarg); break; case 'n': - c->ip4.prefix_len = conf_ip4_prefix(optarg); - if (c->ip4.prefix_len < 0) + c->ip4.addrs[0].prefix_len = conf_ip4_prefix(optarg); + if (c->ip4.addrs[0].prefix_len < 0) die("Invalid netmask: %s", optarg); break; @@ -1984,9 +2003,9 @@ void conf(struct ctx *c, int argc, char **argv) nl_sock_init(c, false); if (!v6_only) - c->ifi4 = conf_ip4(ifi4, &c->ip4); + c->ifi4 = conf_ip4(ifi4, &c->ip4, c->pasta_conf_ns); if (!v4_only) - c->ifi6 = conf_ip6(ifi6, &c->ip6); + c->ifi6 = conf_ip6(ifi6, &c->ip6, c->pasta_conf_ns); if (c->ifi4 && c->mtu < IPV4_MIN_MTU) { warn("MTU %"PRIu16" is too small for IPv4 (minimum %u)", @@ -2125,7 +2144,7 @@ void conf(struct ctx *c, int argc, char **argv) if (!c->ifi6) { c->no_ndp = 1; c->no_dhcpv6 = 1; - } else if (IN6_IS_ADDR_UNSPECIFIED(&c->ip6.addr)) { + } else if (IN6_IS_ADDR_UNSPECIFIED(&c->ip6.addrs[0].addr)) { c->no_dhcpv6 = 1; } diff --git a/dhcp.c b/dhcp.c index 6b9c2e3..46ef8e3 100644 --- a/dhcp.c +++ b/dhcp.c @@ -352,7 +352,7 @@ int dhcp(const struct ctx *c, struct iov_tail *data) reply.secs = 0; reply.flags = m->flags; reply.ciaddr = m->ciaddr; - reply.yiaddr = c->ip4.addr; + reply.yiaddr = c->ip4.addrs[0].addr; reply.siaddr = 0; reply.giaddr = m->giaddr; memcpy(&reply.chaddr, m->chaddr, sizeof(reply.chaddr)); @@ -404,7 +404,7 @@ int dhcp(const struct ctx *c, struct iov_tail *data) info(" from %s", eth_ntop(m->chaddr, macstr, sizeof(macstr))); - mask.s_addr = htonl(0xffffffff << (32 - c->ip4.prefix_len)); + mask.s_addr = htonl(0xffffffff << (32 - c->ip4.addrs[0].prefix_len)); memcpy(opts[1].s, &mask, sizeof(mask)); memcpy(opts[3].s, &c->ip4.guest_gw, sizeof(c->ip4.guest_gw)); memcpy(opts[54].s, &c->ip4.our_tap_addr, sizeof(c->ip4.our_tap_addr)); @@ -412,7 +412,7 @@ int dhcp(const struct ctx *c, struct iov_tail *data) /* If the gateway is not on the assigned subnet, send an option 121 * (Classless Static Routing) adding a dummy route to it. */ - if ((c->ip4.addr.s_addr & mask.s_addr) + if ((c->ip4.addrs[0].addr.s_addr & mask.s_addr) != (c->ip4.guest_gw.s_addr & mask.s_addr)) { /* a.b.c.d/32:0.0.0.0, 0:a.b.c.d */ opts[121].slen = 14; @@ -469,7 +469,7 @@ int dhcp(const struct ctx *c, struct iov_tail *data) if (m->flags & FLAG_BROADCAST) dst = in4addr_broadcast; else - dst = c->ip4.addr; + dst = c->ip4.addrs[0].addr; tap_udp4_send(c, c->ip4.our_tap_addr, 67, dst, 68, &reply, dlen); diff --git a/dhcpv6.c b/dhcpv6.c index e4df0db..7eae6a1 100644 --- a/dhcpv6.c +++ b/dhcpv6.c @@ -625,7 +625,7 @@ int dhcpv6(struct ctx *c, struct iov_tail *data, if (mh->type == TYPE_CONFIRM && server_id) return -1; - if (dhcpv6_ia_notonlink(data, &c->ip6.addr)) { + if (dhcpv6_ia_notonlink(data, &c->ip6.addrs[0].addr)) { dhcpv6_send_ia_notonlink(c, data, &client_id_base, ntohs(client_id->l), mh->xid); @@ -679,7 +679,7 @@ int dhcpv6(struct ctx *c, struct iov_tail *data, tap_udp6_send(c, src, 547, tap_ip6_daddr(c, src), 546, mh->xid, &resp, n); - c->ip6.addr_seen = c->ip6.addr; + c->ip6.addr_seen = c->ip6.addrs[0].addr; return 1; } @@ -703,5 +703,5 @@ void dhcpv6_init(const struct ctx *c) memcpy(resp_not_on_link.server_id.duid_lladdr, c->our_tap_mac, sizeof(c->our_tap_mac)); - resp.ia_addr.addr = c->ip6.addr; + resp.ia_addr.addr = c->ip6.addrs[0].addr; } diff --git a/fwd.c b/fwd.c index 44a0e10..408af30 100644 --- a/fwd.c +++ b/fwd.c @@ -516,7 +516,7 @@ static bool fwd_guest_accessible4(const struct ctx *c, /* For IPv4, addr_seen is initialised to addr, so is always a valid * address */ - if (IN4_ARE_ADDR_EQUAL(addr, &c->ip4.addr) || + if (IN4_ARE_ADDR_EQUAL(addr, &c->ip4.addrs[0].addr) || IN4_ARE_ADDR_EQUAL(addr, &c->ip4.addr_seen)) return false; @@ -537,7 +537,7 @@ static bool fwd_guest_accessible6(const struct ctx *c, if (IN6_IS_ADDR_LOOPBACK(addr)) return false; - if (IN6_ARE_ADDR_EQUAL(addr, &c->ip6.addr)) + if (IN6_ARE_ADDR_EQUAL(addr, &c->ip6.addrs[0].addr)) return false; /* For IPv6, addr_seen starts unspecified, because we don't know what LL @@ -587,9 +587,9 @@ static void nat_outbound(const struct ctx *c, const union inany_addr *addr, else if (inany_equals6(addr, &c->ip6.map_host_loopback)) *translated = inany_loopback6; else if (inany_equals4(addr, &c->ip4.map_guest_addr)) - *translated = inany_from_v4(c->ip4.addr); + *translated = inany_from_v4(c->ip4.addrs[0].addr); else if (inany_equals6(addr, &c->ip6.map_guest_addr)) - translated->a6 = c->ip6.addr; + translated->a6 = c->ip6.addrs[0].addr; else *translated = *addr; } @@ -710,10 +710,10 @@ bool nat_inbound(const struct ctx *c, const union inany_addr *addr, inany_equals6(addr, &in6addr_loopback)) { translated->a6 = c->ip6.map_host_loopback; } else if (!IN4_IS_ADDR_UNSPECIFIED(&c->ip4.map_guest_addr) && - inany_equals4(addr, &c->ip4.addr)) { + inany_equals4(addr, &c->ip4.addrs[0].addr)) { *translated = inany_from_v4(c->ip4.map_guest_addr); } else if (!IN6_IS_ADDR_UNSPECIFIED(&c->ip6.map_guest_addr) && - inany_equals6(addr, &c->ip6.addr)) { + inany_equals6(addr, &c->ip6.addrs[0].addr)) { translated->a6 = c->ip6.map_guest_addr; } else if (fwd_guest_accessible(c, addr)) { *translated = *addr; diff --git a/ip.h b/ip.h index 5830b92..748cb1f 100644 --- a/ip.h +++ b/ip.h @@ -135,4 +135,30 @@ static const struct in_addr in4addr_broadcast = { 0xffffffff }; #define IPV6_MIN_MTU 1280 #endif +/* Maximum number of addresses per address family */ +#define IP4_MAX_ADDRS 8 +#define IP6_MAX_ADDRS 16 + +/** + * struct ip4_addr_entry - IPv4 address with prefix length + * @addr: IPv4 address + * @prefix_len: Prefix length (netmask bits) + */ +struct ip4_addr_entry { + struct in_addr addr; + int prefix_len; + int permanent; +}; + +/** + * struct ip6_addr_entry - IPv6 address with prefix length + * @addr: IPv6 address + * @prefix_len: Prefix length + */ +struct ip6_addr_entry { + struct in6_addr addr; + int prefix_len; + int permanent; +}; + #endif /* IP_H */ diff --git a/ndp.c b/ndp.c index eb9e313..868a234 100644 --- a/ndp.c +++ b/ndp.c @@ -257,7 +257,7 @@ static void ndp_ra(const struct ctx *c, const struct in6_addr *dst) .valid_lifetime = ~0U, .pref_lifetime = ~0U, }, - .prefix = c->ip6.addr, + .prefix = c->ip6.addrs[0].addr, .source_ll = { .header = { .type = OPT_SRC_L2_ADDR, @@ -466,8 +466,8 @@ void ndp_send_init_req(const struct ctx *c) .icmp6_solicited = 0, /* Reserved */ .icmp6_override = 0, /* Reserved */ }, - .target_addr = c->ip6.addr + .target_addr = c->ip6.addrs[0].addr }; debug("Sending initial NDP NS request for guest MAC address"); - ndp_send(c, &c->ip6.addr, &ns, sizeof(ns)); + ndp_send(c, &c->ip6.addrs[0].addr, &ns, sizeof(ns)); } diff --git a/passt.h b/passt.h index 79d01dd..533f2cb 100644 --- a/passt.h +++ b/passt.h @@ -66,9 +66,9 @@ enum passt_modes { /** * struct ip4_ctx - IPv4 execution context - * @addr: IPv4 address assigned to guest + * @addrs: IPv4 addresses assigned to guest + * @addr_count: Number of addresses in addrs[] array * @addr_seen: Latest IPv4 address seen as source from tap - * @prefixlen: IPv4 prefix length (netmask) * @guest_gw: IPv4 gateway as seen by the guest * @map_host_loopback: Outbound connections to this address are NATted to the * host's 127.0.0.1 @@ -85,9 +85,10 @@ enum passt_modes { */ struct ip4_ctx { /* PIF_TAP addresses */ - struct in_addr addr; + struct ip4_addr_entry addrs[IP4_MAX_ADDRS]; + int addr_count; + struct in_addr addr_seen; - int prefix_len; struct in_addr guest_gw; struct in_addr map_host_loopback; struct in_addr map_guest_addr; @@ -107,7 +108,8 @@ struct ip4_ctx { /** * struct ip6_ctx - IPv6 execution context - * @addr: IPv6 address assigned to guest + * @addrs: IPv6 addresses assigned to guest + * @addr_count: Number of addresses in addrs[] array * @addr_seen: Latest IPv6 global/site address seen as source from tap * @addr_ll_seen: Latest IPv6 link-local address seen as source from tap * @guest_gw: IPv6 gateway as seen by the guest @@ -126,7 +128,9 @@ struct ip4_ctx { */ struct ip6_ctx { /* PIF_TAP addresses */ - struct in6_addr addr; + struct ip6_addr_entry addrs[IP6_MAX_ADDRS]; + int addr_count; + struct in6_addr addr_seen; struct in6_addr addr_ll_seen; struct in6_addr guest_gw; diff --git a/pasta.c b/pasta.c index 674b554..49b393c 100644 --- a/pasta.c +++ b/pasta.c @@ -331,8 +331,8 @@ void pasta_ns_conf(struct ctx *c) if (c->ip4.no_copy_addrs) { rc = nl_addr_set(nl_sock_ns, c->pasta_ifi, AF_INET, - &c->ip4.addr, - c->ip4.prefix_len); + &c->ip4.addrs[0].addr, + c->ip4.addrs[0].prefix_len); } else { rc = nl_addr_dup(nl_sock, c->ifi4, nl_sock_ns, c->pasta_ifi, @@ -378,10 +378,12 @@ void pasta_ns_conf(struct ctx *c) 0, IFF_NOARP); if (c->ip6.no_copy_addrs) { - if (!IN6_IS_ADDR_UNSPECIFIED(&c->ip6.addr)) { + struct in6_addr *a = &c->ip6.addrs[0].addr; + + if (!IN6_IS_ADDR_UNSPECIFIED(a)) { rc = nl_addr_set(nl_sock_ns, - c->pasta_ifi, AF_INET6, - &c->ip6.addr, 64); + c->pasta_ifi, + AF_INET6, a, 64); } } else { rc = nl_addr_dup(nl_sock, c->ifi6, diff --git a/tap.c b/tap.c index e3ea61c..0b96cc1 100644 --- a/tap.c +++ b/tap.c @@ -951,8 +951,8 @@ resume: c->ip6.addr_seen = *saddr; } - if (IN6_IS_ADDR_UNSPECIFIED(&c->ip6.addr)) - c->ip6.addr = *saddr; + if (IN6_IS_ADDR_UNSPECIFIED(&c->ip6.addrs[0].addr)) + c->ip6.addrs[0].addr = *saddr; } else if (!IN6_IS_ADDR_UNSPECIFIED(saddr)){ c->ip6.addr_seen = *saddr; } diff --git a/util.h b/util.h index f7a941f..4273e0d 100644 --- a/util.h +++ b/util.h @@ -401,4 +401,5 @@ static inline int wrap_getsockname(int sockfd, struct sockaddr *addr, #define PASST_MAXDNAME 254 /* 253 (RFC 1035) + 1 (the terminator) */ void encode_domain_name(char *buf, const char *domain_name); + #endif /* UTIL_H */ -- 2.51.1

We allow for multiple -n/--netmask options, and update the handling so that each given prefix length is applied to the most recently added address instead of always to addrs[0]. This allows per-address prefix configuration, such as: -a 10.0.0.1 -n 24 -a 10.0.0.2 -n 16 If no address has been added yet, -n still applies to addrs[0] for backwards compatibility. Signed-off-by: Jon Maloy --- conf.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/conf.c b/conf.c index e9f217b..0a4a28a 100644 --- a/conf.c +++ b/conf.c @@ -1528,6 +1528,7 @@ void conf(struct ctx *c, int argc, char **argv) size_t logsize = 0; char *runas = NULL; long fd_tap_opt; + int prefix, idx; int name, ret; uid_t uid; gid_t gid; @@ -1872,10 +1873,14 @@ void conf(struct ctx *c, int argc, char **argv) die("Invalid address: %s", optarg); break; case 'n': - c->ip4.addrs[0].prefix_len = conf_ip4_prefix(optarg); - if (c->ip4.addrs[0].prefix_len < 0) + prefix = conf_ip4_prefix(optarg); + + if (prefix < 0) die("Invalid netmask: %s", optarg); + /* Apply to most recent address, or addrs[0] if none yet */ + idx = c->ip4.addr_count ? c->ip4.addr_count - 1 : 0; + c->ip4.addrs[idx].prefix_len = prefix; break; case 'M': parse_mac(c->our_tap_mac, optarg); -- 2.51.1

We add subscriptions to RTMGRP_LINK, RTMGRP_IPV4_IFADDR, and RTMGRP_IPV6_IFADDR, so that we can receive notifications when link state or addresses change on the namespace interface. When addresses are discovered via netlink: - We mark them as non-permanent, which means they can be modified or deleted by subsequent events. - We apply the prefix indicated in the notification. - Update addr_seen to track the new address as the active one. This provides the foundation for dynamic address monitoring, and supports runtime network changes. Signed-off-by: Jon Maloy --- epoll_type.h | 2 + netlink.c | 370 +++++++++++++++++++++++++++++++++++++++++++++++++++ netlink.h | 3 + passt.c | 5 + passt.h | 1 + tap.c | 6 +- 6 files changed, 384 insertions(+), 3 deletions(-) diff --git a/epoll_type.h b/epoll_type.h index a90ffb6..0a16d94 100644 --- a/epoll_type.h +++ b/epoll_type.h @@ -46,6 +46,8 @@ enum epoll_type { EPOLL_TYPE_REPAIR, /* Netlink neighbour subscription socket */ EPOLL_TYPE_NL_NEIGH, + /* Netlink link/address subscription socket */ + EPOLL_TYPE_NL_LINKADDR, EPOLL_NUM_TYPES, }; diff --git a/netlink.c b/netlink.c index 82a2f0c..7492f17 100644 --- a/netlink.c +++ b/netlink.c @@ -35,6 +35,9 @@ #include "passt.h" #include "log.h" #include "ip.h" +#include "tap.h" +#include "arp.h" +#include "ndp.h" #include "netlink.h" #include "epoll_ctl.h" @@ -59,6 +62,7 @@ int nl_sock = -1; int nl_sock_ns = -1; static int nl_sock_neigh = -1; +static int nl_sock_linkaddr = -1; static int nl_seq = 1; /** @@ -91,6 +95,372 @@ static int nl_sock_init_do(void *arg) return 0; } +/** + * nl_addr4_find() - Find an IPv4 address in the address array + * @c: Execution context + * @addr: Address to find + * + * Return: index if found, -1 otherwise + */ +static int nl_addr4_find(const struct ctx *c, const struct in_addr *addr) +{ + int i; + + for (i = 0; i < c->ip4.addr_count; i++) + if (IN4_ARE_ADDR_EQUAL(&c->ip4.addrs[i].addr, addr)) + return (int)i; + + return -1; +} + +/** + * nl_addr6_find() - Find an IPv6 address in the address array + * @c: Execution context + * @addr: Address to find + * + * Return: index if found, -1 otherwise + */ +static int nl_addr6_find(const struct ctx *c, const struct in6_addr *addr) +{ + int i; + + for (i = 0; i < c->ip6.addr_count; i++) + if (IN6_ARE_ADDR_EQUAL(&c->ip6.addrs[i].addr, addr)) + return (int)i; + + return -1; +} + +/** + * nl_addr4_add() - Add a discovered IPv4 address to the address array + * @c: Execution context + * @addr: Address to add + * @prefix_len: Prefix length + * + * Return: true if added or updated, false if array full or already permanent + */ +static bool nl_addr4_add(struct ctx *c, const struct in_addr *addr, + int prefix_len) +{ + int idx = nl_addr4_find(c, addr); + + if (idx >= 0) { + /* Address exists - if permanent, don't touch; else update */ + if (c->ip4.addrs[idx].permanent) + return false; + c->ip4.addrs[idx].prefix_len = prefix_len; + return true; + } + + /* New address - add if room */ + if (c->ip4.addr_count >= IP4_MAX_ADDRS) { + debug("IPv4 address array full, ignoring discovered address"); + return false; + } + + idx = c->ip4.addr_count++; + c->ip4.addrs[idx].addr = *addr; + c->ip4.addrs[idx].prefix_len = prefix_len; + c->ip4.addrs[idx].permanent = 0; + return true; +} + +/** + * nl_addr6_add() - Add a discovered IPv6 address to the address array + * @c: Execution context + * @addr: Address to add + * @prefix_len: Prefix length + * + * Return: true if added or updated, false if array full or already permanent + */ +static bool nl_addr6_add(struct ctx *c, const struct in6_addr *addr, + int prefix_len) +{ + int idx = nl_addr6_find(c, addr); + + if (idx >= 0) { + /* Address exists - if permanent, don't touch; else update */ + if (c->ip6.addrs[idx].permanent) + return false; + c->ip6.addrs[idx].prefix_len = prefix_len; + return true; + } + + /* New address - add if room */ + if (c->ip6.addr_count >= IP6_MAX_ADDRS) { + debug("IPv6 address array full, ignoring discovered address"); + return false; + } + + idx = c->ip6.addr_count++; + c->ip6.addrs[idx].addr = *addr; + c->ip6.addrs[idx].prefix_len = prefix_len; + c->ip6.addrs[idx].permanent = 0; + return true; +} + +/** + * nl_addr4_del() - Remove an IPv4 address from the array if not permanent + * @c: Execution context + * @addr: Address to remove + * + * Return: true if removed, false if not found or permanent + */ +static bool nl_addr4_del(struct ctx *c, const struct in_addr *addr) +{ + int i, idx = nl_addr4_find(c, addr); + + if (idx < 0) + return false; + + if (c->ip4.addrs[idx].permanent) + return false; + + /* Shift remaining entries down */ + c->ip4.addr_count--; + for (i = idx; i < c->ip4.addr_count; i++) + c->ip4.addrs[i] = c->ip4.addrs[i + 1]; + + return true; +} + +/** + * nl_addr6_del() - Remove an IPv6 address from the array if not permanent + * @c: Execution context + * @addr: Address to remove + * + * Return: true if removed, false if not found or permanent + */ +static bool nl_addr6_del(struct ctx *c, const struct in6_addr *addr) +{ + int i, idx = nl_addr6_find(c, addr); + + if (idx < 0) + return false; + + if (c->ip6.addrs[idx].permanent) + return false; + + /* Shift remaining entries down */ + c->ip6.addr_count--; + for (i = idx; i < c->ip6.addr_count; i++) + c->ip6.addrs[i] = c->ip6.addrs[i + 1]; + + return true; +} + +/** + * nl_linkaddr_msg_read() - Parse and log a netlink link/addr message + * @c: Execution context + * @nh: Netlink message header + */ +static void nl_linkaddr_msg_read(struct ctx *c, const struct nlmsghdr *nh) +{ + if (nh->nlmsg_type == NLMSG_DONE || nh->nlmsg_type == NLMSG_ERROR) + return; + + if (nh->nlmsg_type == RTM_NEWLINK || nh->nlmsg_type == RTM_DELLINK) { + const struct ifinfomsg *ifm = NLMSG_DATA(nh); + struct rtattr *rta = IFLA_RTA(ifm); + size_t na = IFLA_PAYLOAD(nh); + const char *name = "?"; + bool up = !!(ifm->ifi_flags & IFF_UP); + bool running = !!(ifm->ifi_flags & IFF_RUNNING); + + for (; RTA_OK(rta, na); rta = RTA_NEXT(rta, na)) { + if (rta->rta_type == IFLA_IFNAME) { + name = (const char *)RTA_DATA(rta); + break; + } + } + + /* Update pasta interface UP state if this is our interface */ + if (c->mode == MODE_PASTA && + (unsigned int)ifm->ifi_index == c->pasta_ifi) { + c->pasta_ifi_up = up; + debug("Interface %s", up ? "UP" : "DOWN"); + } + + if (nh->nlmsg_type == RTM_NEWLINK) + debug("Link %s (idx=%d): %s %s", name, ifm->ifi_index, + up ? "UP" : "DOWN", running ? "RUNNING" : ""); + else + debug("Link %s (idx=%d): DELETED", name, ifm->ifi_index); + + return; + } + + if (nh->nlmsg_type == RTM_NEWADDR || nh->nlmsg_type == RTM_DELADDR) { + bool is_new = (nh->nlmsg_type == RTM_NEWADDR); + const struct ifaddrmsg *ifa = NLMSG_DATA(nh); + char addr_str[INET6_ADDRSTRLEN]; + struct rtattr *rta = IFA_RTA(ifa); + char ifname[IFNAMSIZ] = { 0 }; + size_t na = IFA_PAYLOAD(nh); + void *addr = NULL; + + for (; RTA_OK(rta, na); rta = RTA_NEXT(rta, na)) { + if (ifa->ifa_family == AF_INET && + rta->rta_type == IFA_LOCAL) { + addr = RTA_DATA(rta); + break; + } else if (ifa->ifa_family == AF_INET6 && + rta->rta_type == IFA_ADDRESS) { + addr = RTA_DATA(rta); + break; + } + } + + if (!addr) + return; + + if_indextoname(ifa->ifa_index, ifname); + inet_ntop(ifa->ifa_family, addr, addr_str, sizeof(addr_str)); + + debug("%s addr on %s (index=%d): %s/%i%s", + is_new ? "NEW" : "DEL", ifname, ifa->ifa_index, addr_str, + ifa->ifa_prefixlen, + tap_is_ready(c) ? " (tap UP)" : " (tap DOWN)"); + + /* Only handle our pasta interface */ + if (c->mode != MODE_PASTA || ifa->ifa_index != c->pasta_ifi) + return; + + if (ifa->ifa_family == AF_INET) { + struct in_addr *a = (struct in_addr *)addr; + + if (!is_new) { + nl_addr4_del(c, a); + return; + } + + if (nl_addr4_add(c, a, ifa->ifa_prefixlen)) { + c->ip4.addr_seen = *a; + if (c->pasta_ifi_up && c->ifi4) { + debug("Sending ARP"); + arp_send_init_req(c); + } + } + } else if (ifa->ifa_family == AF_INET6) { + struct in6_addr *a = (struct in6_addr *)addr; + + if (!is_new) { + nl_addr6_del(c, a); + return; + } + + if (nl_addr6_add(c, a, + ifa->ifa_prefixlen)) { + c->ip6.addr_seen = *a; + if (c->pasta_ifi_up && + c->ifi6 && !c->no_ndp) { + debug("Sending NDP"); + ndp_send_init_req(c); + } + } + } + } +} + +/** + * nl_linkaddr_notify_handler() - Handle events from link/addr notifier socket + * @c: Execution context + */ +void nl_linkaddr_notify_handler(struct ctx *c) +{ + char buf[NLBUFSIZ]; + + for (;;) { + ssize_t n = recv(nl_sock_linkaddr, buf, sizeof(buf), MSG_DONTWAIT); + struct nlmsghdr *nh = (struct nlmsghdr *)buf; + + if (n < 0) { + if (errno == EINTR) + continue; + if (errno != EAGAIN) + debug("recv() error: %s", strerror_(errno)); + break; + } + + debug("Received %zd bytes", n); + + for (; NLMSG_OK(nh, n); nh = NLMSG_NEXT(nh, n)) + nl_linkaddr_msg_read(c, nh); + } +} + +/** + * nl_linkaddr_init_do() - Actually create and bind the netlink socket + * @arg: Execution context (for namespace entry) or NULL + * + * Return: 0 on success, -1 on failure + */ +static int nl_linkaddr_init_do(void *arg) +{ + struct sockaddr_nl addr = { .nl_family = AF_NETLINK, + .nl_groups = RTMGRP_LINK | RTMGRP_IPV4_IFADDR | + RTMGRP_IPV6_IFADDR }; + + if (arg) + ns_enter((struct ctx *)arg); + + nl_sock_linkaddr = socket(AF_NETLINK, SOCK_RAW | SOCK_CLOEXEC, NETLINK_ROUTE); + if (nl_sock_linkaddr < 0) { + debug("socket() failed: %s", strerror_(errno)); + return -1; + } + + if (bind(nl_sock_linkaddr, (struct sockaddr *)&addr, sizeof(addr)) < 0) { + debug("bind() failed: %s", strerror_(errno)); + close(nl_sock_linkaddr); + nl_sock_linkaddr = -1; + return -1; + } + + debug("socket fd=%d", nl_sock_linkaddr); + return 0; +} + +/** + * nl_linkaddr_notify_init() - Initialize link/address change notifier + * @c: Execution context + * + * Return: 0 on success, -1 on failure + */ +int nl_linkaddr_notify_init(const struct ctx *c) +{ + union epoll_ref ref = { .type = EPOLL_TYPE_NL_LINKADDR }; + struct epoll_event ev = { .events = EPOLLIN }; + + if (nl_sock_linkaddr >= 0) { + debug("notifier already initialized (fd=%d)", nl_sock_linkaddr); + return 0; + } + + /* Open the notifier socket in the namespace for pasta mode, + * or in the init namespace otherwise. + */ + if (c->mode == MODE_PASTA) + NS_CALL(nl_linkaddr_init_do, (void *)c); + else + nl_linkaddr_init_do(NULL); + + if (nl_sock_linkaddr < 0) { + warn("Failed to create/bind link/addr notifier socket"); + return -1; + } + + ev.data.u64 = ref.u64; + if (epoll_ctl(c->epollfd, EPOLL_CTL_ADD, nl_sock_linkaddr, &ev) == -1) { + warn("epoll_ctl() failed on link/addr notifier socket: %s", + strerror_(errno)); + close(nl_sock_linkaddr); + nl_sock_linkaddr = -1; + return -1; + } + + return 0; +} /** * nl_sock_init() - Call nl_sock_init_do(), won't return on failure * @c: Execution context diff --git a/netlink.h b/netlink.h index 8f1e9b9..1796a72 100644 --- a/netlink.h +++ b/netlink.h @@ -33,4 +33,7 @@ int nl_link_set_flags(int s, unsigned int ifi, int nl_neigh_notify_init(const struct ctx *c); void nl_neigh_notify_handler(const struct ctx *c); +int nl_linkaddr_notify_init(const struct ctx *c); +void nl_linkaddr_notify_handler(struct ctx *c); + #endif /* NETLINK_H */ diff --git a/passt.c b/passt.c index 5ed88d0..f274858 100644 --- a/passt.c +++ b/passt.c @@ -80,6 +80,7 @@ char *epoll_type_str[] = { [EPOLL_TYPE_REPAIR_LISTEN] = "TCP_REPAIR helper listening socket", [EPOLL_TYPE_REPAIR] = "TCP_REPAIR helper socket", [EPOLL_TYPE_NL_NEIGH] = "netlink neighbour notifier socket", + [EPOLL_TYPE_NL_LINKADDR] = "netlink link/address notifier socket", }; static_assert(ARRAY_SIZE(epoll_type_str) == EPOLL_NUM_TYPES, "epoll_type_str[] doesn't match enum epoll_type"); @@ -304,6 +305,9 @@ static void passt_worker(void *opaque, int nfds, struct epoll_event *events) case EPOLL_TYPE_NL_NEIGH: nl_neigh_notify_handler(c); break; + case EPOLL_TYPE_NL_LINKADDR: + nl_linkaddr_notify_handler(c); + break; default: /* Can't happen */ ASSERT(0); @@ -413,6 +417,7 @@ int main(int argc, char **argv) fwd_neigh_table_init(&c); nl_neigh_notify_init(&c); + nl_linkaddr_notify_init(&c); if (!c.foreground) { if ((devnull_fd = open("/dev/null", O_RDWR | O_CLOEXEC)) < 0) diff --git a/passt.h b/passt.h index 533f2cb..70ccaf1 100644 --- a/passt.h +++ b/passt.h @@ -264,6 +264,7 @@ struct ctx { char pasta_ifn[IF_NAMESIZE]; unsigned int pasta_ifi; int pasta_conf_ns; + int pasta_ifi_up; /* Namespace interface is UP */ int no_tcp; struct tcp_ctx tcp; diff --git a/tap.c b/tap.c index 0b96cc1..a2a4459 100644 --- a/tap.c +++ b/tap.c @@ -1363,10 +1363,10 @@ bool tap_is_ready(const struct ctx *c) return false; if (c->mode == MODE_PASTA) { - /* If pasta_conf_ns is set, the interface was configured and - * brought up during initialization. If not, it's still down. + /* Check if the namespace interface is actually UP. + * This is tracked by netlink link notifications. */ - return c->pasta_conf_ns; + return c->pasta_ifi_up; } return true; -- 2.51.1

We update ignore_arp() to check against all addresses in the addrs[] array, not just addrs[0]. This ensures ARP requests for any of the guest's configured addresses are properly ignored. Signed-off-by: Jon Maloy --- arp.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/arp.c b/arp.c index 7eaf517..61c309e 100644 --- a/arp.c +++ b/arp.c @@ -41,6 +41,8 @@ static bool ignore_arp(const struct ctx *c, const struct arphdr *ah, const struct arpmsg *am) { + int i; + if (ah->ar_hrd != htons(ARPHRD_ETHER) || ah->ar_pro != htons(ETH_P_IP) || ah->ar_hln != ETH_ALEN || @@ -53,9 +55,10 @@ static bool ignore_arp(const struct ctx *c, !memcmp(am->sip, am->tip, sizeof(am->sip))) return true; - /* Don't resolve the guest's assigned address, either. */ - if (!memcmp(am->tip, &c->ip4.addrs[0].addr, sizeof(am->tip))) - return true; + /* Don't resolve any of the guest's assigned addresses, either */ + for (i = 0; i < c->ip4.addr_count; i++) + if (!memcmp(am->tip, &c->ip4.addrs[i].addr, sizeof(am->tip))) + return true; return false; } -- 2.51.1

We extend host-side netlink monitoring to also track default route changes on the template interface and propagate them to the namespace. - Subscribe to RTMGRP_IPV4_ROUTE and RTMGRP_IPV6_ROUTE groups on the host-side netlink socket - Handle RTM_NEWROUTE/RTM_DELROUTE events for default routes. - Support late binding via routes: if no template interface is bound yet, adopt the interface in question when a default route appears on it. - When a default route is added, set guest_gw/our_tap_addr and propagate the route to the namespace via nl_route_set_def() - When a default route is removed, clear guest_gw/our_tap_addr Signed-off-by: Jon Maloy --- netlink.c | 100 ++++++++++++++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 97 insertions(+), 3 deletions(-) diff --git a/netlink.c b/netlink.c index 583ada8..d049239 100644 --- a/netlink.c +++ b/netlink.c @@ -199,7 +199,7 @@ static bool nl_addr6_add(struct ctx *c, const struct in6_addr *addr, idx = c->ip6.addr_count++; c->ip6.addrs[idx].addr = *addr; c->ip6.addrs[idx].prefix_len = prefix_len; - c->ip6.addrs[idxyes].permanent = 0; + c->ip6.addrs[idx].permanent = 0; return true; } @@ -254,7 +254,7 @@ static bool nl_addr6_del(struct ctx *c, const struct in6_addr *addr) } /** - * nl_linkaddr_host_msg_read() - Handle host-side link/addr changes + * nl_linkaddr_host_msg_read() - Handle host-side link/addr/route changes * @c: Execution context * @nh: Netlink message header * @@ -420,6 +420,99 @@ static void nl_linkaddr_host_msg_read(struct ctx *c, const struct nlmsghdr *nh) } return; } + + if (nh->nlmsg_type == RTM_NEWROUTE || nh->nlmsg_type == RTM_DELROUTE) { + bool is_new = (nh->nlmsg_type == RTM_NEWROUTE); + const struct rtmsg *rtm = NLMSG_DATA(nh); + struct rtattr *rta = RTM_RTA(rtm); + size_t na = RTM_PAYLOAD(nh); + unsigned int template_ifi; + char ifname[IFNAMSIZ]; + unsigned int oif = 0; + void *gw = NULL; + bool is_default; + bool is_match; + bool unbound; + + /* Only interested in default routes */ + if (rtm->rtm_dst_len != 0) + return; + + for (; RTA_OK(rta, na); rta = RTA_NEXT(rta, na)) { + if (rta->rta_type == RTA_GATEWAY) + gw = RTA_DATA(rta); + else if (rta->rta_type == RTA_OIF) + oif = *(unsigned int *)RTA_DATA(rta); + } + + if (!gw || !oif) + return; + + /* Get interface name for late binding check */ + if (!if_indextoname(oif, ifname)) + return; + + /* Check for late binding conditions */ + is_default = !strcmp(c->pasta_ifn, pasta_default_ifn); + is_match = !strcmp(ifname, c->pasta_ifn); + + if (rtm->rtm_family == AF_INET) + template_ifi = c->ifi4; + else if (rtm->rtm_family == AF_INET6) + template_ifi = c->ifi6; + else + return; + + unbound = (rtm->rtm_family == AF_INET) ? + (int)c->ifi4 <= 0 : (int)c->ifi6 <= 0; + + if (unbound && (is_default || is_match)) { + debug("Late binding (route): using %s as %s template", + ifname, + rtm->rtm_family == AF_INET ? "IPv4" : "IPv6"); + + if (rtm->rtm_family == AF_INET) { + c->ifi4 = oif; + template_ifi = c->ifi4; + } else { + c->ifi6 = oif; + template_ifi = c->ifi6; + } + + if (is_default) + snprintf(c->pasta_ifn, sizeof(c->pasta_ifn), + "%s", ifname); + } + + if (oif != template_ifi) + return; + + if (rtm->rtm_family == AF_INET) { + char buf[INET_ADDRSTRLEN]; + + if (!is_new) { + c->ip4.guest_gw = (struct in_addr){ 0 }; + c->ip4.our_tap_addr = (struct in_addr){ 0 }; + return; + } + c->ip4.guest_gw = *(struct in_addr *)gw; + c->ip4.our_tap_addr = c->ip4.guest_gw; + nl_route_set_def(nl_sock_ns, c->pasta_ifi, AF_INET, gw); + inet_ntop(AF_INET, &c->ip4.guest_gw, buf, sizeof(buf)); + debug("Set IPv4 default route via %s", buf); + } else if (rtm->rtm_family == AF_INET6) { + char buf[INET6_ADDRSTRLEN]; + + if (!is_new) { + c->ip6.guest_gw = (struct in6_addr){ 0 }; + return; + } + c->ip6.guest_gw = *(struct in6_addr *)gw; + nl_route_set_def(nl_sock_ns, c->pasta_ifi, AF_INET6, gw); + inet_ntop(AF_INET6, &c->ip6.guest_gw, buf, sizeof(buf)); + debug("Set IPv6 default route via %s", buf); + } + } } /** @@ -676,7 +769,8 @@ static int nl_linkaddr_init_do(void *arg) static int nl_linkaddr_host_init_do(void *arg) { struct sockaddr_nl addr = { .nl_family = AF_NETLINK, - .nl_groups = RTMGRP_LINK | RTMGRP_IPV4_IFADDR | RTMGRP_IPV6_IFADDR }; + .nl_groups = RTMGRP_LINK | RTMGRP_IPV4_IFADDR | RTMGRP_IPV6_IFADDR | + RTMGRP_IPV4_ROUTE | RTMGRP_IPV6_ROUTE }; (void)arg; -- 2.51.1

When pasta starts without a template interface (-I), it creates the tap device with the default name (tap0). Later, when late binding discovers the actual template interface, we now rename the device to match it. This ensures the namespace interface has the expected name, matching the discovered host interface. Key changes: - Add nl_link_rename() function to rename network interfaces - When late binding triggers with the default TAP name, bring it down, rename it to match the discovered interface, then bring it up Signed-off-by: Jon Maloy --- netlink.c | 37 +++++++++++++++++++++++++++++++++++++ tap.c | 27 +++++++++++++++++++++++++++ tap.h | 1 + 3 files changed, 65 insertions(+) diff --git a/netlink.c b/netlink.c index de04fb7..71089ab 100644 --- a/netlink.c +++ b/netlink.c @@ -44,6 +44,8 @@ /* Default namespace interface name from conf.c */ extern const char *pasta_default_ifn; +static int nl_link_rename(int s, unsigned int ifi, const char *name); + /* Same as RTA_NEXT() but for nexthops: RTNH_NEXT() doesn't take 'attrlen' */ #define RTNH_NEXT_AND_DEC(rtnh, attrlen) \ ((attrlen) -= RTNH_ALIGN((rtnh)->rtnh_len), RTNH_NEXT(rtnh)) @@ -315,6 +317,14 @@ static void nl_linkaddr_host_msg_read(struct ctx *c, const struct nlmsghdr *nh) } late_binding = true; + /* Rename interface if it is still using default name */ + if (is_default && strcmp(ifname, pasta_default_ifn)) { + nl_link_set_flags(nl_sock_ns, c->pasta_ifi, + 0, IFF_UP); + nl_link_rename(nl_sock_ns, c->pasta_ifi, ifname); + debug("Renamed tap: %s -> %s", + pasta_default_ifn, ifname); + } if (is_default) snprintf(c->pasta_ifn, sizeof(c->pasta_ifn), "%s", ifname); @@ -1943,6 +1953,33 @@ int nl_link_set_flags(int s, unsigned int ifi, return nl_do(s, &req, RTM_NEWLINK, 0, sizeof(req)); } +/** + * nl_link_rename() - Rename a network interface + * @s: Netlink socket + * @ifi: Interface index + * @name: New interface name + * + * Return: 0 on success, negative error code on failure + */ +static int nl_link_rename(int s, unsigned int ifi, const char *name) +{ + struct req_t { + struct nlmsghdr nlh; + struct ifinfomsg ifm; + struct rtattr rta; + char name[IFNAMSIZ]; + } req = { + .ifm.ifi_family = AF_UNSPEC, + .ifm.ifi_index = ifi, + .rta.rta_type = IFLA_IFNAME, + .rta.rta_len = RTA_LENGTH(IFNAMSIZ), + }; + + snprintf(req.name, IFNAMSIZ, "%s", name); + + return nl_do(s, &req, RTM_NEWLINK, 0, sizeof(req)); +} + /** * nl_neigh_msg_read() - Interpret a neighbour state message from netlink * @c: Execution context diff --git a/tap.c b/tap.c index a2a4459..cd59160 100644 --- a/tap.c +++ b/tap.c @@ -1502,6 +1502,33 @@ static void tap_sock_tun_init(struct ctx *c) tap_start_connection(c); } +/** + * tap_backend_init_late() - Create tap device for late binding + * @c: Execution context + * + * Called when late binding discovers the template interface name. + * Creates the TAP device with the discovered name. + */ +void tap_backend_init_late(struct ctx *c) +{ + if (c->mode != MODE_PASTA || c->fd_tap != -1) + return; + + if (!*c->pasta_ifn) { + warn("%s called with empty pasta_ifn", __func__); + return; + } + + NS_CALL(tap_ns_tun, c); + if (c->fd_tap == -1) { + err("Failed to set up tap device in namespace"); + return; + } + + tap_start_connection(c); + info("Created tap device %s for late binding", c->pasta_ifn); +} + /** * tap_sock_update_pool() - Set the buffer base and size for the pool of packets * @base: Buffer base diff --git a/tap.h b/tap.h index ee22a9d..b41eae9 100644 --- a/tap.h +++ b/tap.h @@ -118,6 +118,7 @@ void tap_handler_passt(struct ctx *c, uint32_t events, int tap_sock_unix_open(char *sock_path); void tap_sock_reset(struct ctx *c); void tap_backend_init(struct ctx *c); +void tap_backend_init_late(struct ctx *c); void tap_flush_pools(void); void tap_handler(struct ctx *c, const struct timespec *now); void tap_add_packet(struct ctx *c, struct iov_tail *data, -- 2.51.1

On Sun, Dec 14, 2025 at 08:54:30PM -0500, Jon Maloy wrote:

As preparation for supporting multiple addresses per interface, we replace the single addr/prefix_len fields with arrays.

- We add an ip4_addr_entry and an ip6_addr_entry struct containing address and prefix length.

- We set the array sizes to IP4_MAX_ADDRS=8 and IP6_MAX_ADDRS=16, respectively.

The only functional change is that the IPv6 prefix length now is properly stored instead of being hardcoded to 64 even when set via the -a option.

Signed-off-by: Jon Maloy --- arp.c | 4 +-- conf.c | 97 +++++++++++++++++++++++++++++++++----------------------- dhcp.c | 8 ++--- dhcpv6.c | 6 ++-- fwd.c | 12 +++---- ip.h | 26 +++++++++++++++ ndp.c | 6 ++-- passt.h | 16 ++++++---- pasta.c | 12 ++++--- tap.c | 4 +-- util.h | 1 + 11 files changed, 122 insertions(+), 70 deletions(-)

diff --git a/arp.c b/arp.c index bb042e9..7eaf517 100644 --- a/arp.c +++ b/arp.c @@ -54,7 +54,7 @@ static bool ignore_arp(const struct ctx *c, return true;

/* Don't resolve the guest's assigned address, either. */ - if (!memcmp(am->tip, &c->ip4.addr, sizeof(am->tip))) + if (!memcmp(am->tip, &c->ip4.addrs[0].addr, sizeof(am->tip))) return true;

Sorry, missed this on my first pass. This needs to skip *all* of the guest addresses, not just the first one. Otherwise passt will respond to arps for the guest's other addresses with its own MAC which will break everything. -- David Gibson (he or they) | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you, not the other way | around. http://www.ozlabs.org/~dgibson

On Sun, Dec 14, 2025 at 08:54:33PM -0500, Jon Maloy wrote:

We allow for multiple -n/--netmask options, and update the handling so that each given prefix length is applied to the most recently added address instead of always to addrs[0].

This allows per-address prefix configuration, such as:

-a 10.0.0.1 -n 24 -a 10.0.0.2 -n 16

If no address has been added yet, -n still applies to addrs[0] for backwards compatibility.

Huh. I'd forgotten until looking at this series that we had the -n option. We probably do need this change, but in general I think we'd be better off deprecating -n, in favour of allowing a prefix len as part of the -a option, e.g. -a 10.0.0.1/24 -a 10.0.0.2/16 That could be a smaller change preliminary to this series.

Signed-off-by: Jon Maloy --- conf.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/conf.c b/conf.c index e9f217b..0a4a28a 100644 --- a/conf.c +++ b/conf.c @@ -1528,6 +1528,7 @@ void conf(struct ctx *c, int argc, char **argv) size_t logsize = 0; char *runas = NULL; long fd_tap_opt; + int prefix, idx; int name, ret; uid_t uid; gid_t gid; @@ -1872,10 +1873,14 @@ void conf(struct ctx *c, int argc, char **argv) die("Invalid address: %s", optarg); break; case 'n': - c->ip4.addrs[0].prefix_len = conf_ip4_prefix(optarg); - if (c->ip4.addrs[0].prefix_len < 0) + prefix = conf_ip4_prefix(optarg); + + if (prefix < 0) die("Invalid netmask: %s", optarg);

+ /* Apply to most recent address, or addrs[0] if none yet */ + idx = c->ip4.addr_count ? c->ip4.addr_count - 1 : 0; + c->ip4.addrs[idx].prefix_len = prefix; break; case 'M': parse_mac(c->our_tap_mac, optarg); -- 2.51.1

-- David Gibson (he or they) | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you, not the other way | around. http://www.ozlabs.org/~dgibson

On Sun, Dec 14, 2025 at 08:54:35PM -0500, Jon Maloy wrote:

We update ignore_arp() to check against all addresses in the addrs[] array, not just addrs[0]. This ensures ARP requests for any of the guest's configured addresses are properly ignored.

Signed-off-by: Jon Maloy --- arp.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/arp.c b/arp.c index 7eaf517..61c309e 100644 --- a/arp.c +++ b/arp.c @@ -41,6 +41,8 @@ static bool ignore_arp(const struct ctx *c, const struct arphdr *ah, const struct arpmsg *am) { + int i; + if (ah->ar_hrd != htons(ARPHRD_ETHER) || ah->ar_pro != htons(ETH_P_IP) || ah->ar_hln != ETH_ALEN || @@ -53,9 +55,10 @@ static bool ignore_arp(const struct ctx *c, !memcmp(am->sip, am->tip, sizeof(am->sip))) return true;

- /* Don't resolve the guest's assigned address, either. */ - if (!memcmp(am->tip, &c->ip4.addrs[0].addr, sizeof(am->tip))) - return true; + /* Don't resolve any of the guest's assigned addresses, either */ + for (i = 0; i < c->ip4.addr_count; i++) + if (!memcmp(am->tip, &c->ip4.addrs[i].addr, sizeof(am->tip))) + return true;

Ah, right. I think this needs to move earlier in the series, otherwise things are broken in between allowing multiple addresses and this change.

return false; } -- 2.51.1

-- David Gibson (he or they) | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you, not the other way | around. http://www.ozlabs.org/~dgibson

On Sun, Dec 14, 2025 at 08:54:36PM -0500, Jon Maloy wrote:

We add subscriptions to RTMGRP_LINK, RTMGRP_IPV4_IFADDR, and RTMGRP_IPV6_IFADDR, so that we can receive notifications when link state or addresses change on the namespace interface.

When addresses are discovered via netlink:

- We mark them as non-permanent, which means they can be modified or deleted by subsequent events. - We apply the prefix indicated in the notification. - Update addr_seen to track the new address as the active one.

addr_seen isn't really about an "active" address. The expectation was that the guest would only use a single address, it just might not be the one we told it to. Now that we're aiming to allow multiple concurrent addresses, we can expect the guest to use all of them actively.

This provides the foundation for dynamic address monitoring, and supports runtime network changes.

Signed-off-by: Jon Maloy --- epoll_type.h | 2 + netlink.c | 370 +++++++++++++++++++++++++++++++++++++++++++++++++++ netlink.h | 3 + passt.c | 5 + passt.h | 1 + tap.c | 6 +- 6 files changed, 384 insertions(+), 3 deletions(-)

diff --git a/epoll_type.h b/epoll_type.h index a90ffb6..0a16d94 100644 --- a/epoll_type.h +++ b/epoll_type.h @@ -46,6 +46,8 @@ enum epoll_type { EPOLL_TYPE_REPAIR, /* Netlink neighbour subscription socket */ EPOLL_TYPE_NL_NEIGH, + /* Netlink link/address subscription socket */ + EPOLL_TYPE_NL_LINKADDR,

EPOLL_NUM_TYPES, }; diff --git a/netlink.c b/netlink.c index 82a2f0c..7492f17 100644 --- a/netlink.c +++ b/netlink.c @@ -35,6 +35,9 @@ #include "passt.h" #include "log.h" #include "ip.h" +#include "tap.h" +#include "arp.h" +#include "ndp.h" #include "netlink.h" #include "epoll_ctl.h"

@@ -59,6 +62,7 @@ int nl_sock = -1; int nl_sock_ns = -1; static int nl_sock_neigh = -1; +static int nl_sock_linkaddr = -1; static int nl_seq = 1;

/** @@ -91,6 +95,372 @@ static int nl_sock_init_do(void *arg) return 0; }

+/** + * nl_addr4_find() - Find an IPv4 address in the address array + * @c: Execution context + * @addr: Address to find + * + * Return: index if found, -1 otherwise + */ +static int nl_addr4_find(const struct ctx *c, const struct in_addr *addr) +{ + int i; + + for (i = 0; i < c->ip4.addr_count; i++) + if (IN4_ARE_ADDR_EQUAL(&c->ip4.addrs[i].addr, addr)) + return (int)i; + + return -1; +} + +/** + * nl_addr6_find() - Find an IPv6 address in the address array + * @c: Execution context + * @addr: Address to find + * + * Return: index if found, -1 otherwise + */ +static int nl_addr6_find(const struct ctx *c, const struct in6_addr *addr) +{ + int i; + + for (i = 0; i < c->ip6.addr_count; i++) + if (IN6_ARE_ADDR_EQUAL(&c->ip6.addrs[i].addr, addr)) + return (int)i; + + return -1; +} + +/** + * nl_addr4_add() - Add a discovered IPv4 address to the address array + * @c: Execution context + * @addr: Address to add + * @prefix_len: Prefix length + * + * Return: true if added or updated, false if array full or already permanent + */ +static bool nl_addr4_add(struct ctx *c, const struct in_addr *addr, + int prefix_len) +{ + int idx = nl_addr4_find(c, addr); + + if (idx >= 0) { + /* Address exists - if permanent, don't touch; else update */ + if (c->ip4.addrs[idx].permanent) + return false; + c->ip4.addrs[idx].prefix_len = prefix_len; + return true; + } + + /* New address - add if room */ + if (c->ip4.addr_count >= IP4_MAX_ADDRS) { + debug("IPv4 address array full, ignoring discovered address"); + return false; + } + + idx = c->ip4.addr_count++; + c->ip4.addrs[idx].addr = *addr; + c->ip4.addrs[idx].prefix_len = prefix_len; + c->ip4.addrs[idx].permanent = 0; + return true; +} + +/** + * nl_addr6_add() - Add a discovered IPv6 address to the address array + * @c: Execution context + * @addr: Address to add + * @prefix_len: Prefix length + * + * Return: true if added or updated, false if array full or already permanent + */ +static bool nl_addr6_add(struct ctx *c, const struct in6_addr *addr, + int prefix_len) +{ + int idx = nl_addr6_find(c, addr); + + if (idx >= 0) { + /* Address exists - if permanent, don't touch; else update */ + if (c->ip6.addrs[idx].permanent) + return false; + c->ip6.addrs[idx].prefix_len = prefix_len; + return true; + } + + /* New address - add if room */ + if (c->ip6.addr_count >= IP6_MAX_ADDRS) { + debug("IPv6 address array full, ignoring discovered address"); + return false; + } + + idx = c->ip6.addr_count++; + c->ip6.addrs[idx].addr = *addr; + c->ip6.addrs[idx].prefix_len = prefix_len; + c->ip6.addrs[idx].permanent = 0; + return true; +} + +/** + * nl_addr4_del() - Remove an IPv4 address from the array if not permanent + * @c: Execution context + * @addr: Address to remove + * + * Return: true if removed, false if not found or permanent + */ +static bool nl_addr4_del(struct ctx *c, const struct in_addr *addr) +{ + int i, idx = nl_addr4_find(c, addr); + + if (idx < 0) + return false; + + if (c->ip4.addrs[idx].permanent) + return false; + + /* Shift remaining entries down */ + c->ip4.addr_count--; + for (i = idx; i < c->ip4.addr_count; i++) + c->ip4.addrs[i] = c->ip4.addrs[i + 1]; + + return true; +} + +/** + * nl_addr6_del() - Remove an IPv6 address from the array if not permanent + * @c: Execution context + * @addr: Address to remove + * + * Return: true if removed, false if not found or permanent + */ +static bool nl_addr6_del(struct ctx *c, const struct in6_addr *addr) +{ + int i, idx = nl_addr6_find(c, addr); + + if (idx < 0) + return false; + + if (c->ip6.addrs[idx].permanent) + return false; + + /* Shift remaining entries down */ + c->ip6.addr_count--; + for (i = idx; i < c->ip6.addr_count; i++) + c->ip6.addrs[i] = c->ip6.addrs[i + 1]; + + return true; +}

All the functions above are more to do with the data structure storing the addresses than they are to do with netlink. Better to move them into... maybe ip.c? And use them from conf.c as well. Given the amount of near-duplication here, maybe it would be better to have a single table for v4 and v6 using inany_addr?

+/** + * nl_linkaddr_msg_read() - Parse and log a netlink link/addr message + * @c: Execution context + * @nh: Netlink message header + */ +static void nl_linkaddr_msg_read(struct ctx *c, const struct nlmsghdr *nh) +{ + if (nh->nlmsg_type == NLMSG_DONE || nh->nlmsg_type == NLMSG_ERROR) + return; + + if (nh->nlmsg_type == RTM_NEWLINK || nh->nlmsg_type == RTM_DELLINK) { + const struct ifinfomsg *ifm = NLMSG_DATA(nh); + struct rtattr *rta = IFLA_RTA(ifm); + size_t na = IFLA_PAYLOAD(nh); + const char *name = "?"; + bool up = !!(ifm->ifi_flags & IFF_UP); + bool running = !!(ifm->ifi_flags & IFF_RUNNING); + + for (; RTA_OK(rta, na); rta = RTA_NEXT(rta, na)) { + if (rta->rta_type == IFLA_IFNAME) { + name = (const char *)RTA_DATA(rta); + break; + } + } + + /* Update pasta interface UP state if this is our interface */ + if (c->mode == MODE_PASTA && + (unsigned int)ifm->ifi_index == c->pasta_ifi) { + c->pasta_ifi_up = up; + debug("Interface %s", up ? "UP" : "DOWN");

This only makes sense if we're listening to netlink messages in the guest netns, but the address stuff only makes sense listening to messages in the host netns.

+ } + + if (nh->nlmsg_type == RTM_NEWLINK) + debug("Link %s (idx=%d): %s %s", name, ifm->ifi_index, + up ? "UP" : "DOWN", running ? "RUNNING" : ""); + else + debug("Link %s (idx=%d): DELETED", name, ifm->ifi_index); + + return; + } + + if (nh->nlmsg_type == RTM_NEWADDR || nh->nlmsg_type == RTM_DELADDR) { + bool is_new = (nh->nlmsg_type == RTM_NEWADDR); + const struct ifaddrmsg *ifa = NLMSG_DATA(nh); + char addr_str[INET6_ADDRSTRLEN]; + struct rtattr *rta = IFA_RTA(ifa); + char ifname[IFNAMSIZ] = { 0 }; + size_t na = IFA_PAYLOAD(nh); + void *addr = NULL; + for (; RTA_OK(rta, na); rta = RTA_NEXT(rta, na)) { + if (ifa->ifa_family == AF_INET && + rta->rta_type == IFA_LOCAL) { + addr = RTA_DATA(rta); + break; + } else if (ifa->ifa_family == AF_INET6 && + rta->rta_type == IFA_ADDRESS) { + addr = RTA_DATA(rta); + break; + } + } + + if (!addr) + return; + + if_indextoname(ifa->ifa_index, ifname); + inet_ntop(ifa->ifa_family, addr, addr_str, sizeof(addr_str)); + + debug("%s addr on %s (index=%d): %s/%i%s", + is_new ? "NEW" : "DEL", ifname, ifa->ifa_index, addr_str, + ifa->ifa_prefixlen, + tap_is_ready(c) ? " (tap UP)" : " (tap DOWN)"); + + /* Only handle our pasta interface */ + if (c->mode != MODE_PASTA || ifa->ifa_index != c->pasta_ifi) + return;

Nope. This is a host netns event, so comparing to pasta_ifi makes no sense. We _should_ be comparing to ifi4 or ifi6 (depending on address family), and we should probably do that before we go parsing the details above. We should also probably check for --no-copy-addrs here, too. In the other direction, even for PASST mode we can store this address in our table, it just won't do anything until DHCP or whatever consults it.

+ + if (ifa->ifa_family == AF_INET) { + struct in_addr *a = (struct in_addr *)addr; + + if (!is_new) { + nl_addr4_del(c, a); + return; + } + + if (nl_addr4_add(c, a, ifa->ifa_prefixlen)) { + c->ip4.addr_seen = *a; + if (c->pasta_ifi_up && c->ifi4) { + debug("Sending ARP"); + arp_send_init_req(c);

What does this ARP request do? AFAICT we haven't actually added the address in the guest netns yet, so the guest won't respond to the ARP.

+ } + } + } else if (ifa->ifa_family == AF_INET6) { + struct in6_addr *a = (struct in6_addr *)addr; + + if (!is_new) { + nl_addr6_del(c, a); + return; + } + + if (nl_addr6_add(c, a, + ifa->ifa_prefixlen)) { + c->ip6.addr_seen = *a; + if (c->pasta_ifi_up && + c->ifi6 && !c->no_ndp) { + debug("Sending NDP"); + ndp_send_init_req(c);

Some question with this NDP.

+ } + } + } + } +} + +/** + * nl_linkaddr_notify_handler() - Handle events from link/addr notifier socket + * @c: Execution context + */ +void nl_linkaddr_notify_handler(struct ctx *c) +{ + char buf[NLBUFSIZ]; + + for (;;) { + ssize_t n = recv(nl_sock_linkaddr, buf, sizeof(buf), MSG_DONTWAIT); + struct nlmsghdr *nh = (struct nlmsghdr *)buf; + + if (n < 0) { + if (errno == EINTR) + continue; + if (errno != EAGAIN) + debug("recv() error: %s", strerror_(errno)); + break; + } + + debug("Received %zd bytes", n); + + for (; NLMSG_OK(nh, n); nh = NLMSG_NEXT(nh, n)) + nl_linkaddr_msg_read(c, nh); + } +} + +/** + * nl_linkaddr_init_do() - Actually create and bind the netlink socket + * @arg: Execution context (for namespace entry) or NULL + * + * Return: 0 on success, -1 on failure + */ +static int nl_linkaddr_init_do(void *arg) +{ + struct sockaddr_nl addr = { .nl_family = AF_NETLINK, + .nl_groups = RTMGRP_LINK | RTMGRP_IPV4_IFADDR | + RTMGRP_IPV6_IFADDR }; + + if (arg) + ns_enter((struct ctx *)arg); + + nl_sock_linkaddr = socket(AF_NETLINK, SOCK_RAW | SOCK_CLOEXEC, NETLINK_ROUTE);

Is there a reason to use an additional socket, rather than adding more events to the neighbour listening socket?

+ if (nl_sock_linkaddr < 0) { + debug("socket() failed: %s", strerror_(errno)); + return -1; + } + + if (bind(nl_sock_linkaddr, (struct sockaddr *)&addr, sizeof(addr)) < 0) { + debug("bind() failed: %s", strerror_(errno)); + close(nl_sock_linkaddr); + nl_sock_linkaddr = -1; + return -1; + } + + debug("socket fd=%d", nl_sock_linkaddr); + return 0; +} + +/** + * nl_linkaddr_notify_init() - Initialize link/address change notifier + * @c: Execution context + * + * Return: 0 on success, -1 on failure + */ +int nl_linkaddr_notify_init(const struct ctx *c) +{ + union epoll_ref ref = { .type = EPOLL_TYPE_NL_LINKADDR }; + struct epoll_event ev = { .events = EPOLLIN }; + + if (nl_sock_linkaddr >= 0) { + debug("notifier already initialized (fd=%d)", nl_sock_linkaddr); + return 0; + } + + /* Open the notifier socket in the namespace for pasta mode, + * or in the init namespace otherwise.

Definitely wrong. We're trying to watch host addresses so that we can copy them to the guest - therefore we always need to watch in the host netns. On pasta there might be reasons to *also* listen in the guest netns, but that would want a different handler to do different things.

+ */ + if (c->mode == MODE_PASTA) + NS_CALL(nl_linkaddr_init_do, (void *)c); + else + nl_linkaddr_init_do(NULL); + + if (nl_sock_linkaddr < 0) { + warn("Failed to create/bind link/addr notifier socket"); + return -1; + } + + ev.data.u64 = ref.u64; + if (epoll_ctl(c->epollfd, EPOLL_CTL_ADD, nl_sock_linkaddr, &ev) == -1) { + warn("epoll_ctl() failed on link/addr notifier socket: %s", + strerror_(errno)); + close(nl_sock_linkaddr); + nl_sock_linkaddr = -1; + return -1; + } + + return 0; +} /** * nl_sock_init() - Call nl_sock_init_do(), won't return on failure * @c: Execution context diff --git a/netlink.h b/netlink.h index 8f1e9b9..1796a72 100644 --- a/netlink.h +++ b/netlink.h @@ -33,4 +33,7 @@ int nl_link_set_flags(int s, unsigned int ifi, int nl_neigh_notify_init(const struct ctx *c); void nl_neigh_notify_handler(const struct ctx *c);

+int nl_linkaddr_notify_init(const struct ctx *c); +void nl_linkaddr_notify_handler(struct ctx *c); + #endif /* NETLINK_H */ diff --git a/passt.c b/passt.c index 5ed88d0..f274858 100644 --- a/passt.c +++ b/passt.c @@ -80,6 +80,7 @@ char *epoll_type_str[] = { [EPOLL_TYPE_REPAIR_LISTEN] = "TCP_REPAIR helper listening socket", [EPOLL_TYPE_REPAIR] = "TCP_REPAIR helper socket", [EPOLL_TYPE_NL_NEIGH] = "netlink neighbour notifier socket", + [EPOLL_TYPE_NL_LINKADDR] = "netlink link/address notifier socket", }; static_assert(ARRAY_SIZE(epoll_type_str) == EPOLL_NUM_TYPES, "epoll_type_str[] doesn't match enum epoll_type"); @@ -304,6 +305,9 @@ static void passt_worker(void *opaque, int nfds, struct epoll_event *events) case EPOLL_TYPE_NL_NEIGH: nl_neigh_notify_handler(c); break; + case EPOLL_TYPE_NL_LINKADDR: + nl_linkaddr_notify_handler(c); + break; default: /* Can't happen */ ASSERT(0); @@ -413,6 +417,7 @@ int main(int argc, char **argv)

fwd_neigh_table_init(&c); nl_neigh_notify_init(&c); + nl_linkaddr_notify_init(&c);

if (!c.foreground) { if ((devnull_fd = open("/dev/null", O_RDWR | O_CLOEXEC)) < 0) diff --git a/passt.h b/passt.h index 533f2cb..70ccaf1 100644 --- a/passt.h +++ b/passt.h @@ -264,6 +264,7 @@ struct ctx { char pasta_ifn[IF_NAMESIZE]; unsigned int pasta_ifi; int pasta_conf_ns; + int pasta_ifi_up; /* Namespace interface is UP */

int no_tcp; struct tcp_ctx tcp; diff --git a/tap.c b/tap.c index 0b96cc1..a2a4459 100644 --- a/tap.c +++ b/tap.c @@ -1363,10 +1363,10 @@ bool tap_is_ready(const struct ctx *c) return false;

if (c->mode == MODE_PASTA) { - /* If pasta_conf_ns is set, the interface was configured and - * brought up during initialization. If not, it's still down. + /* Check if the namespace interface is actually UP. + * This is tracked by netlink link notifications. */ - return c->pasta_conf_ns; + return c->pasta_ifi_up; }

return true; -- 2.51.1

-- David Gibson (he or they) | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you, not the other way | around. http://www.ozlabs.org/~dgibson

On 2025-12-15 04:40, David Gibson wrote:

On Sun, Dec 14, 2025 at 08:54:30PM -0500, Jon Maloy wrote:

...

As preparation for supporting multiple addresses per interface, we replace the single addr/prefix_len fields with arrays.

- We add an ip4_addr_entry and an ip6_addr_entry struct containing address and prefix length.

- We set the array sizes to IP4_MAX_ADDRS=8 and IP6_MAX_ADDRS=16, respectively.

The only functional change is that the IPv6 prefix length now is properly stored instead of being hardcoded to 64 even when set via the -a option.

Signed-off-by: Jon Maloy --- arp.c | 4 +-- conf.c | 97 +++++++++++++++++++++++++++++++++----------------------- dhcp.c | 8 ++--- dhcpv6.c | 6 ++-- fwd.c | 12 +++---- ip.h | 26 +++++++++++++++ ndp.c | 6 ++-- passt.h | 16 ++++++---- pasta.c | 12 ++++--- tap.c | 4 +-- util.h | 1 + 11 files changed, 122 insertions(+), 70 deletions(-)

diff --git a/arp.c b/arp.c index bb042e9..7eaf517 100644 --- a/arp.c +++ b/arp.c @@ -54,7 +54,7 @@ static bool ignore_arp(const struct ctx *c, return true;

/* Don't resolve the guest's assigned address, either. */ - if (!memcmp(am->tip, &c->ip4.addr, sizeof(am->tip))) + if (!memcmp(am->tip, &c->ip4.addrs[0].addr, sizeof(am->tip))) return true;

return false; @@ -145,7 +145,7 @@ void arp_send_init_req(const struct ctx *c) memcpy(req.am.sha, c->our_tap_mac, sizeof(req.am.sha)); memcpy(req.am.sip, &c->ip4.our_tap_addr, sizeof(req.am.sip)); memcpy(req.am.tha, MAC_BROADCAST, sizeof(req.am.tha)); - memcpy(req.am.tip, &c->ip4.addr, sizeof(req.am.tip)); + memcpy(req.am.tip, &c->ip4.addrs[0].addr, sizeof(req.am.tip));

debug("Sending initial ARP request for guest MAC address"); tap_send_single(c, &req, sizeof(req)); diff --git a/conf.c b/conf.c index fdc19e8..0e96f36 100644 --- a/conf.c +++ b/conf.c @@ -694,10 +694,12 @@ static int conf_ip4_prefix(const char *arg) * conf_ip4() - Verify or detect IPv4 support, get relevant addresses * @ifi: Host interface to attempt (0 to determine one) * @ip4: IPv4 context (will be written) + * @permanent: Mark configured addresses as permanent * * Return: interface index for IPv4, or 0 on failure. */ -static unsigned int conf_ip4(unsigned int ifi, struct ip4_ctx *ip4) +static unsigned int conf_ip4(unsigned int ifi, struct ip4_ctx *ip4, + bool permanent) { if (!ifi) ifi = nl_get_ext_if(nl_sock, AF_INET); @@ -717,33 +719,38 @@ static unsigned int conf_ip4(unsigned int ifi, struct ip4_ctx *ip4) } }

- if (IN4_IS_ADDR_UNSPECIFIED(&ip4->addr)) { + if (!ip4->addr_count) { int rc = nl_addr_get(nl_sock, ifi, AF_INET, - &ip4->addr, &ip4->prefix_len, NULL); + &ip4->addrs[0].addr, + &ip4->addrs[0].prefix_len, NULL); if (rc < 0) { debug("Couldn't discover IPv4 address: %s", strerror_(-rc)); return 0; } + ip4->addrs[0].permanent = permanent; + ip4->addr_count = 1; }

- if (!ip4->prefix_len) { - in_addr_t addr = ntohl(ip4->addr.s_addr); - if (IN_CLASSA(addr)) - ip4->prefix_len = (32 - IN_CLASSA_NSHIFT); - else if (IN_CLASSB(addr)) - ip4->prefix_len = (32 - IN_CLASSB_NSHIFT); - else if (IN_CLASSC(addr)) - ip4->prefix_len = (32 - IN_CLASSC_NSHIFT); + /* Apply default prefix_len to first address if not set */ + if (!ip4->addrs[0].prefix_len) { + in_addr_t a = ntohl(ip4->addrs[0].addr.s_addr); + + if (IN_CLASSA(a)) + ip4->addrs[0].prefix_len = 8; + else if (IN_CLASSB(a)) + ip4->addrs[0].prefix_len = 16; + else if (IN_CLASSC(a)) + ip4->addrs[0].prefix_len = 24; else - ip4->prefix_len = 32; + ip4->addrs[0].prefix_len = 32; }

- ip4->addr_seen = ip4->addr; + ip4->addr_seen = ip4->addrs[0].addr;

ip4->our_tap_addr = ip4->guest_gw;

- if (IN4_IS_ADDR_UNSPECIFIED(&ip4->addr)) + if (IN4_IS_ADDR_UNSPECIFIED(&ip4->addrs[0].addr)) return 0;

return ifi; @@ -755,9 +762,9 @@ static unsigned int conf_ip4(unsigned int ifi, struct ip4_ctx *ip4) */ static void conf_ip4_local(struct ip4_ctx *ip4) { - ip4->addr_seen = ip4->addr = IP4_LL_GUEST_ADDR; + ip4->addr_seen = ip4->addrs[0].addr = IP4_LL_GUEST_ADDR; ip4->our_tap_addr = ip4->guest_gw = IP4_LL_GUEST_GW; - ip4->prefix_len = IP4_LL_PREFIX_LEN; + ip4->addrs[0].prefix_len = IP4_LL_PREFIX_LEN;

ip4->no_copy_addrs = ip4->no_copy_routes = true; } @@ -766,10 +773,12 @@ static void conf_ip4_local(struct ip4_ctx *ip4) * conf_ip6() - Verify or detect IPv6 support, get relevant addresses * @ifi: Host interface to attempt (0 to determine one) * @ip6: IPv6 context (will be written) + * @permanent: Mark discovered addresses as permanent * * Return: interface index for IPv6, or 0 on failure. */ -static unsigned int conf_ip6(unsigned int ifi, struct ip6_ctx *ip6) +static unsigned int conf_ip6(unsigned int ifi, struct ip6_ctx *ip6, + bool permanent) { int prefix_len = 0; int rc; @@ -792,19 +801,25 @@ static unsigned int conf_ip6(unsigned int ifi, struct ip6_ctx *ip6) }

rc = nl_addr_get(nl_sock, ifi, AF_INET6, - IN6_IS_ADDR_UNSPECIFIED(&ip6->addr) ? &ip6->addr : NULL, + ip6->addr_count ? NULL : &ip6->addrs[0].addr, &prefix_len, &ip6->our_tap_ll); if (rc < 0) { debug("Couldn't discover IPv6 address: %s", strerror_(-rc)); return 0; }

- ip6->addr_seen = ip6->addr; + if (!ip6->addr_count) { + ip6->addrs[0].prefix_len = prefix_len ? prefix_len : 64; + ip6->addrs[0].permanent = permanent; + ip6->addr_count = 1; + } + + ip6->addr_seen = ip6->addrs[0].addr;

if (IN6_IS_ADDR_LINKLOCAL(&ip6->guest_gw)) ip6->our_tap_ll = ip6->guest_gw;

- if (IN6_IS_ADDR_UNSPECIFIED(&ip6->addr) || + if (IN6_IS_ADDR_UNSPECIFIED(&ip6->addrs[0].addr) || IN6_IS_ADDR_UNSPECIFIED(&ip6->our_tap_ll)) return 0;

@@ -1149,11 +1164,13 @@ static void conf_print(const struct ctx *c) if (!c->no_dhcp) { uint32_t mask;

- mask = htonl(0xffffffff << (32 - c->ip4.prefix_len)); + mask = htonl(0xffffffff << + (32 - c->ip4.addrs[0].prefix_len));

info("DHCP:"); info(" assign: %s", - inet_ntop(AF_INET, &c->ip4.addr, buf4, sizeof(buf4))); + inet_ntop(AF_INET, &c->ip4.addrs[0].addr, + buf4, sizeof(buf4))); info(" mask: %s", inet_ntop(AF_INET, &mask, buf4, sizeof(buf4))); info(" router: %s", @@ -1191,7 +1208,8 @@ static void conf_print(const struct ctx *c) goto dns6;

info(" assign: %s", - inet_ntop(AF_INET6, &c->ip6.addr, buf6, sizeof(buf6))); + inet_ntop(AF_INET6, &c->ip6.addrs[0].addr, + buf6, sizeof(buf6))); info(" router: %s", inet_ntop(AF_INET6, &c->ip6.guest_gw, buf6, sizeof(buf6))); info(" our link-local: %s", @@ -1812,22 +1830,23 @@ void conf(struct ctx *c, int argc, char **argv) break; } case 'a': - if (inet_pton(AF_INET6, optarg, &c->ip6.addr) && - !IN6_IS_ADDR_UNSPECIFIED(&c->ip6.addr) && - !IN6_IS_ADDR_LOOPBACK(&c->ip6.addr) && - !IN6_IS_ADDR_V4MAPPED(&c->ip6.addr) && - !IN6_IS_ADDR_V4COMPAT(&c->ip6.addr) && - !IN6_IS_ADDR_MULTICAST(&c->ip6.addr)) { + if (inet_pton(AF_INET6, optarg, + &c->ip6.addrs[0].addr) && + !IN6_IS_ADDR_UNSPECIFIED(&c->ip6.addrs[0].addr) && + !IN6_IS_ADDR_LOOPBACK(&c->ip6.addrs[0].addr) && + !IN6_IS_ADDR_V4MAPPED(&c->ip6.addrs[0].addr) && + !IN6_IS_ADDR_V4COMPAT(&c->ip6.addrs[0].addr) && + !IN6_IS_ADDR_MULTICAST(&c->ip6.addrs[0].addr)) { if (c->mode == MODE_PASTA) c->ip6.no_copy_addrs = true; break; }

- if (inet_pton(AF_INET, optarg, &c->ip4.addr) && - !IN4_IS_ADDR_UNSPECIFIED(&c->ip4.addr) && - !IN4_IS_ADDR_BROADCAST(&c->ip4.addr) && - !IN4_IS_ADDR_LOOPBACK(&c->ip4.addr) && - !IN4_IS_ADDR_MULTICAST(&c->ip4.addr)) { + if (inet_pton(AF_INET, optarg, &c->ip4.addrs[0].addr) && + !IN4_IS_ADDR_UNSPECIFIED(&c->ip4.addrs[0].addr) && + !IN4_IS_ADDR_BROADCAST(&c->ip4.addrs[0].addr) && + !IN4_IS_ADDR_LOOPBACK(&c->ip4.addrs[0].addr) && + !IN4_IS_ADDR_MULTICAST(&c->ip4.addrs[0].addr)) { if (c->mode == MODE_PASTA) c->ip4.no_copy_addrs = true; break; @@ -1836,8 +1855,8 @@ void conf(struct ctx *c, int argc, char **argv) die("Invalid address: %s", optarg); break; case 'n': - c->ip4.prefix_len = conf_ip4_prefix(optarg); - if (c->ip4.prefix_len < 0) + c->ip4.addrs[0].prefix_len = conf_ip4_prefix(optarg); + if (c->ip4.addrs[0].prefix_len < 0) die("Invalid netmask: %s", optarg);

break; @@ -1984,9 +2003,9 @@ void conf(struct ctx *c, int argc, char **argv)

nl_sock_init(c, false); if (!v6_only) - c->ifi4 = conf_ip4(ifi4, &c->ip4); + c->ifi4 = conf_ip4(ifi4, &c->ip4, c->pasta_conf_ns); if (!v4_only) - c->ifi6 = conf_ip6(ifi6, &c->ip6); + c->ifi6 = conf_ip6(ifi6, &c->ip6, c->pasta_conf_ns);

if (c->ifi4 && c->mtu < IPV4_MIN_MTU) { warn("MTU %"PRIu16" is too small for IPv4 (minimum %u)", @@ -2125,7 +2144,7 @@ void conf(struct ctx *c, int argc, char **argv) if (!c->ifi6) { c->no_ndp = 1; c->no_dhcpv6 = 1; - } else if (IN6_IS_ADDR_UNSPECIFIED(&c->ip6.addr)) { + } else if (IN6_IS_ADDR_UNSPECIFIED(&c->ip6.addrs[0].addr)) { c->no_dhcpv6 = 1; }

diff --git a/dhcp.c b/dhcp.c index 6b9c2e3..46ef8e3 100644 --- a/dhcp.c +++ b/dhcp.c @@ -352,7 +352,7 @@ int dhcp(const struct ctx *c, struct iov_tail *data) reply.secs = 0; reply.flags = m->flags; reply.ciaddr = m->ciaddr; - reply.yiaddr = c->ip4.addr; + reply.yiaddr = c->ip4.addrs[0].addr; reply.siaddr = 0; reply.giaddr = m->giaddr; memcpy(&reply.chaddr, m->chaddr, sizeof(reply.chaddr)); @@ -404,7 +404,7 @@ int dhcp(const struct ctx *c, struct iov_tail *data)

info(" from %s", eth_ntop(m->chaddr, macstr, sizeof(macstr)));

- mask.s_addr = htonl(0xffffffff << (32 - c->ip4.prefix_len)); + mask.s_addr = htonl(0xffffffff << (32 - c->ip4.addrs[0].prefix_len)); memcpy(opts[1].s, &mask, sizeof(mask)); memcpy(opts[3].s, &c->ip4.guest_gw, sizeof(c->ip4.guest_gw)); memcpy(opts[54].s, &c->ip4.our_tap_addr, sizeof(c->ip4.our_tap_addr)); @@ -412,7 +412,7 @@ int dhcp(const struct ctx *c, struct iov_tail *data) /* If the gateway is not on the assigned subnet, send an option 121 * (Classless Static Routing) adding a dummy route to it. */ - if ((c->ip4.addr.s_addr & mask.s_addr) + if ((c->ip4.addrs[0].addr.s_addr & mask.s_addr) != (c->ip4.guest_gw.s_addr & mask.s_addr)) { /* a.b.c.d/32:0.0.0.0, 0:a.b.c.d */ opts[121].slen = 14; @@ -469,7 +469,7 @@ int dhcp(const struct ctx *c, struct iov_tail *data) if (m->flags & FLAG_BROADCAST) dst = in4addr_broadcast; else - dst = c->ip4.addr; + dst = c->ip4.addrs[0].addr;

tap_udp4_send(c, c->ip4.our_tap_addr, 67, dst, 68, &reply, dlen);

diff --git a/dhcpv6.c b/dhcpv6.c index e4df0db..7eae6a1 100644 --- a/dhcpv6.c +++ b/dhcpv6.c @@ -625,7 +625,7 @@ int dhcpv6(struct ctx *c, struct iov_tail *data, if (mh->type == TYPE_CONFIRM && server_id) return -1;

- if (dhcpv6_ia_notonlink(data, &c->ip6.addr)) { + if (dhcpv6_ia_notonlink(data, &c->ip6.addrs[0].addr)) {

dhcpv6_send_ia_notonlink(c, data, &client_id_base, ntohs(client_id->l), mh->xid); @@ -679,7 +679,7 @@ int dhcpv6(struct ctx *c, struct iov_tail *data,

tap_udp6_send(c, src, 547, tap_ip6_daddr(c, src), 546, mh->xid, &resp, n); - c->ip6.addr_seen = c->ip6.addr; + c->ip6.addr_seen = c->ip6.addrs[0].addr;

return 1; } @@ -703,5 +703,5 @@ void dhcpv6_init(const struct ctx *c) memcpy(resp_not_on_link.server_id.duid_lladdr, c->our_tap_mac, sizeof(c->our_tap_mac));

- resp.ia_addr.addr = c->ip6.addr; + resp.ia_addr.addr = c->ip6.addrs[0].addr; } diff --git a/fwd.c b/fwd.c index 44a0e10..408af30 100644 --- a/fwd.c +++ b/fwd.c @@ -516,7 +516,7 @@ static bool fwd_guest_accessible4(const struct ctx *c, /* For IPv4, addr_seen is initialised to addr, so is always a valid * address */ - if (IN4_ARE_ADDR_EQUAL(addr, &c->ip4.addr) || + if (IN4_ARE_ADDR_EQUAL(addr, &c->ip4.addrs[0].addr) || IN4_ARE_ADDR_EQUAL(addr, &c->ip4.addr_seen)) return false;

@@ -537,7 +537,7 @@ static bool fwd_guest_accessible6(const struct ctx *c, if (IN6_IS_ADDR_LOOPBACK(addr)) return false;

- if (IN6_ARE_ADDR_EQUAL(addr, &c->ip6.addr)) + if (IN6_ARE_ADDR_EQUAL(addr, &c->ip6.addrs[0].addr)) return false;

/* For IPv6, addr_seen starts unspecified, because we don't know what LL @@ -587,9 +587,9 @@ static void nat_outbound(const struct ctx *c, const union inany_addr *addr, else if (inany_equals6(addr, &c->ip6.map_host_loopback)) *translated = inany_loopback6; else if (inany_equals4(addr, &c->ip4.map_guest_addr)) - *translated = inany_from_v4(c->ip4.addr); + *translated = inany_from_v4(c->ip4.addrs[0].addr); else if (inany_equals6(addr, &c->ip6.map_guest_addr)) - translated->a6 = c->ip6.addr; + translated->a6 = c->ip6.addrs[0].addr; else *translated = *addr; } @@ -710,10 +710,10 @@ bool nat_inbound(const struct ctx *c, const union inany_addr *addr, inany_equals6(addr, &in6addr_loopback)) { translated->a6 = c->ip6.map_host_loopback; } else if (!IN4_IS_ADDR_UNSPECIFIED(&c->ip4.map_guest_addr) && - inany_equals4(addr, &c->ip4.addr)) { + inany_equals4(addr, &c->ip4.addrs[0].addr)) { *translated = inany_from_v4(c->ip4.map_guest_addr); } else if (!IN6_IS_ADDR_UNSPECIFIED(&c->ip6.map_guest_addr) && - inany_equals6(addr, &c->ip6.addr)) { + inany_equals6(addr, &c->ip6.addrs[0].addr)) { translated->a6 = c->ip6.map_guest_addr; } else if (fwd_guest_accessible(c, addr)) { *translated = *addr; diff --git a/ip.h b/ip.h index 5830b92..748cb1f 100644 --- a/ip.h +++ b/ip.h @@ -135,4 +135,30 @@ static const struct in_addr in4addr_broadcast = { 0xffffffff }; #define IPV6_MIN_MTU 1280 #endif

+/* Maximum number of addresses per address family */ +#define IP4_MAX_ADDRS 8 +#define IP6_MAX_ADDRS 16 + +/** + * struct ip4_addr_entry - IPv4 address with prefix length + * @addr: IPv4 address + * @prefix_len: Prefix length (netmask bits) + */ +struct ip4_addr_entry { + struct in_addr addr; + int prefix_len; + int permanent;

Might as well make these uint8_t and bool, respectively. There will be some padding, but the overall structure will still be smaller.

Or, it might be worth considering replacing 'permanent' with a flags mask, in case we have future uses for it.

Agree with that. I'll make that change, and if we ver need more we can replace the boolean with a bitmask. /jon

On 2025-12-15 05:32, David Gibson wrote:

On Sun, Dec 14, 2025 at 08:54:36PM -0500, Jon Maloy wrote:

...

We add subscriptions to RTMGRP_LINK, RTMGRP_IPV4_IFADDR, and RTMGRP_IPV6_IFADDR, so that we can receive notifications when link state or addresses change on the namespace interface.

When addresses are discovered via netlink:

- We mark them as non-permanent, which means they can be modified or deleted by subsequent events. - We apply the prefix indicated in the notification. - Update addr_seen to track the new address as the active one.

addr_seen isn't really about an "active" address. The expectation was that the guest would only use a single address, it just might not be the one we told it to.

Now that we're aiming to allow multiple concurrent addresses, we can expect the guest to use all of them actively.

Right. This makes the case for having guest/tap side subscriptions, since we now will now know all addresses he is using, so addr_seen should become obsolete.

...

This provides the foundation for dynamic address monitoring, and supports runtime network changes.

Signed-off-by: Jon Maloy --- epoll_type.h | 2 + netlink.c | 370 +++++++++++++++++++++++++++++++++++++++++++++++++++ netlink.h | 3 + passt.c | 5 + passt.h | 1 + tap.c | 6 +- 6 files changed, 384 insertions(+), 3 deletions(-)

diff --git a/epoll_type.h b/epoll_type.h index a90ffb6..0a16d94 100644 --- a/epoll_type.h +++ b/epoll_type.h @@ -46,6 +46,8 @@ enum epoll_type { EPOLL_TYPE_REPAIR, /* Netlink neighbour subscription socket */ EPOLL_TYPE_NL_NEIGH, + /* Netlink link/address subscription socket */ + EPOLL_TYPE_NL_LINKADDR,

EPOLL_NUM_TYPES, }; diff --git a/netlink.c b/netlink.c index 82a2f0c..7492f17 100644 --- a/netlink.c +++ b/netlink.c @@ -35,6 +35,9 @@ #include "passt.h" #include "log.h" #include "ip.h" +#include "tap.h" +#include "arp.h" +#include "ndp.h" #include "netlink.h" #include "epoll_ctl.h"

@@ -59,6 +62,7 @@ int nl_sock = -1; int nl_sock_ns = -1; static int nl_sock_neigh = -1; +static int nl_sock_linkaddr = -1; static int nl_seq = 1;

/** @@ -91,6 +95,372 @@ static int nl_sock_init_do(void *arg) return 0; }

+/** + * nl_addr4_find() - Find an IPv4 address in the address array + * @c: Execution context + * @addr: Address to find + * + * Return: index if found, -1 otherwise + */ +static int nl_addr4_find(const struct ctx *c, const struct in_addr *addr) +{ + int i; + + for (i = 0; i < c->ip4.addr_count; i++) + if (IN4_ARE_ADDR_EQUAL(&c->ip4.addrs[i].addr, addr)) + return (int)i; + + return -1; +} + +/** + * nl_addr6_find() - Find an IPv6 address in the address array + * @c: Execution context + * @addr: Address to find + * + * Return: index if found, -1 otherwise + */ +static int nl_addr6_find(const struct ctx *c, const struct in6_addr *addr) +{ + int i; + + for (i = 0; i < c->ip6.addr_count; i++) + if (IN6_ARE_ADDR_EQUAL(&c->ip6.addrs[i].addr, addr)) + return (int)i; + + return -1; +} + +/** + * nl_addr4_add() - Add a discovered IPv4 address to the address array + * @c: Execution context + * @addr: Address to add + * @prefix_len: Prefix length + * + * Return: true if added or updated, false if array full or already permanent + */ +static bool nl_addr4_add(struct ctx *c, const struct in_addr *addr, + int prefix_len) +{ + int idx = nl_addr4_find(c, addr); + + if (idx >= 0) { + /* Address exists - if permanent, don't touch; else update */ + if (c->ip4.addrs[idx].permanent) + return false; + c->ip4.addrs[idx].prefix_len = prefix_len; + return true; + } + + /* New address - add if room */ + if (c->ip4.addr_count >= IP4_MAX_ADDRS) { + debug("IPv4 address array full, ignoring discovered address"); + return false; + } + + idx = c->ip4.addr_count++; + c->ip4.addrs[idx].addr = *addr; + c->ip4.addrs[idx].prefix_len = prefix_len; + c->ip4.addrs[idx].permanent = 0; + return true; +} + +/** + * nl_addr6_add() - Add a discovered IPv6 address to the address array + * @c: Execution context + * @addr: Address to add + * @prefix_len: Prefix length + * + * Return: true if added or updated, false if array full or already permanent + */ +static bool nl_addr6_add(struct ctx *c, const struct in6_addr *addr, + int prefix_len) +{ + int idx = nl_addr6_find(c, addr); + + if (idx >= 0) { + /* Address exists - if permanent, don't touch; else update */ + if (c->ip6.addrs[idx].permanent) + return false; + c->ip6.addrs[idx].prefix_len = prefix_len; + return true; + } + + /* New address - add if room */ + if (c->ip6.addr_count >= IP6_MAX_ADDRS) { + debug("IPv6 address array full, ignoring discovered address"); + return false; + } + + idx = c->ip6.addr_count++; + c->ip6.addrs[idx].addr = *addr; + c->ip6.addrs[idx].prefix_len = prefix_len; + c->ip6.addrs[idx].permanent = 0; + return true; +} + +/** + * nl_addr4_del() - Remove an IPv4 address from the array if not permanent + * @c: Execution context + * @addr: Address to remove + * + * Return: true if removed, false if not found or permanent + */ +static bool nl_addr4_del(struct ctx *c, const struct in_addr *addr) +{ + int i, idx = nl_addr4_find(c, addr); + + if (idx < 0) + return false; + + if (c->ip4.addrs[idx].permanent) + return false; + + /* Shift remaining entries down */ + c->ip4.addr_count--; + for (i = idx; i < c->ip4.addr_count; i++) + c->ip4.addrs[i] = c->ip4.addrs[i + 1]; + + return true; +} + +/** + * nl_addr6_del() - Remove an IPv6 address from the array if not permanent + * @c: Execution context + * @addr: Address to remove + * + * Return: true if removed, false if not found or permanent + */ +static bool nl_addr6_del(struct ctx *c, const struct in6_addr *addr) +{ + int i, idx = nl_addr6_find(c, addr); + + if (idx < 0) + return false; + + if (c->ip6.addrs[idx].permanent) + return false; + + /* Shift remaining entries down */ + c->ip6.addr_count--; + for (i = idx; i < c->ip6.addr_count; i++) + c->ip6.addrs[i] = c->ip6.addrs[i + 1]; + + return true; +}

All the functions above are more to do with the data structure storing the addresses than they are to do with netlink. Better to move them into... maybe ip.c? And use them from conf.c as well.

Agreed. I'll fix that.

Given the amount of near-duplication here, maybe it would be better to have a single table for v4 and v6 using inany_addr?

Yes.

...

+/** + * nl_linkaddr_msg_read() - Parse and log a netlink link/addr message + * @c: Execution context + * @nh: Netlink message header + */ +static void nl_linkaddr_msg_read(struct ctx *c, const struct nlmsghdr *nh) +{ + if (nh->nlmsg_type == NLMSG_DONE || nh->nlmsg_type == NLMSG_ERROR) + return; + + if (nh->nlmsg_type == RTM_NEWLINK || nh->nlmsg_type == RTM_DELLINK) { + const struct ifinfomsg *ifm = NLMSG_DATA(nh); + struct rtattr *rta = IFLA_RTA(ifm); + size_t na = IFLA_PAYLOAD(nh); + const char *name = "?"; + bool up = !!(ifm->ifi_flags & IFF_UP); + bool running = !!(ifm->ifi_flags & IFF_RUNNING); + + for (; RTA_OK(rta, na); rta = RTA_NEXT(rta, na)) { + if (rta->rta_type == IFLA_IFNAME) { + name = (const char *)RTA_DATA(rta); + break; + } + } + + /* Update pasta interface UP state if this is our interface */ + if (c->mode == MODE_PASTA && + (unsigned int)ifm->ifi_index == c->pasta_ifi) { + c->pasta_ifi_up = up; + debug("Interface %s", up ? "UP" : "DOWN");

This only makes sense if we're listening to netlink messages in the guest netns, but the address stuff only makes sense listening to messages in the host netns.

See previous response.>

...

+ } + + if (nh->nlmsg_type == RTM_NEWLINK) + debug("Link %s (idx=%d): %s %s", name, ifm->ifi_index, + up ? "UP" : "DOWN", running ? "RUNNING" : ""); + else + debug("Link %s (idx=%d): DELETED", name, ifm->ifi_index); + + return; + } + + if (nh->nlmsg_type == RTM_NEWADDR || nh->nlmsg_type == RTM_DELADDR) { + bool is_new = (nh->nlmsg_type == RTM_NEWADDR); + const struct ifaddrmsg *ifa = NLMSG_DATA(nh); + char addr_str[INET6_ADDRSTRLEN]; + struct rtattr *rta = IFA_RTA(ifa); + char ifname[IFNAMSIZ] = { 0 }; + size_t na = IFA_PAYLOAD(nh); + void *addr = NULL; + for (; RTA_OK(rta, na); rta = RTA_NEXT(rta, na)) { + if (ifa->ifa_family == AF_INET && + rta->rta_type == IFA_LOCAL) { + addr = RTA_DATA(rta); + break; + } else if (ifa->ifa_family == AF_INET6 && + rta->rta_type == IFA_ADDRESS) { + addr = RTA_DATA(rta); + break; + } + } + + if (!addr) + return; + + if_indextoname(ifa->ifa_index, ifname); + inet_ntop(ifa->ifa_family, addr, addr_str, sizeof(addr_str)); + + debug("%s addr on %s (index=%d): %s/%i%s", + is_new ? "NEW" : "DEL", ifname, ifa->ifa_index, addr_str, + ifa->ifa_prefixlen, + tap_is_ready(c) ? " (tap UP)" : " (tap DOWN)"); + + /* Only handle our pasta interface */ + if (c->mode != MODE_PASTA || ifa->ifa_index != c->pasta_ifi) + return;

Nope. This is a host netns event, so comparing to pasta_ifi makes no sense. We _should_ be comparing to ifi4 or ifi6 (depending on address family), and we should probably do that before we go parsing the details above.

We should also probably check for --no-copy-addrs here, too.

In the other direction, even for PASST mode we can store this address in our table, it just won't do anything until DHCP or whatever consults it.

ok

...

+ + if (ifa->ifa_family == AF_INET) { + struct in_addr *a = (struct in_addr *)addr; + + if (!is_new) { + nl_addr4_del(c, a); + return; + } + + if (nl_addr4_add(c, a, ifa->ifa_prefixlen)) { + c->ip4.addr_seen = *a; + if (c->pasta_ifi_up && c->ifi4) { + debug("Sending ARP"); + arp_send_init_req(c);

What does this ARP request do? AFAICT we haven't actually added the address in the guest netns yet, so the guest won't respond to the ARP.

The address was set by the guest, so why wouldn't he respond?

...

+ } + } + } else if (ifa->ifa_family == AF_INET6) { + struct in6_addr *a = (struct in6_addr *)addr; + + if (!is_new) { + nl_addr6_del(c, a); + return; + } + + if (nl_addr6_add(c, a, + ifa->ifa_prefixlen)) { + c->ip6.addr_seen = *a; + if (c->pasta_ifi_up && + c->ifi6 && !c->no_ndp) { + debug("Sending NDP"); + ndp_send_init_req(c);

Some question with this NDP.

...

+ } + } + } + } +} + +/** + * nl_linkaddr_notify_handler() - Handle events from link/addr notifier socket + * @c: Execution context + */ +void nl_linkaddr_notify_handler(struct ctx *c) +{ + char buf[NLBUFSIZ]; + + for (;;) { + ssize_t n = recv(nl_sock_linkaddr, buf, sizeof(buf), MSG_DONTWAIT); + struct nlmsghdr *nh = (struct nlmsghdr *)buf; + + if (n < 0) { + if (errno == EINTR) + continue; + if (errno != EAGAIN) + debug("recv() error: %s", strerror_(errno)); + break; + } + + debug("Received %zd bytes", n); + + for (; NLMSG_OK(nh, n); nh = NLMSG_NEXT(nh, n)) + nl_linkaddr_msg_read(c, nh); + } +} + +/** + * nl_linkaddr_init_do() - Actually create and bind the netlink socket + * @arg: Execution context (for namespace entry) or NULL + * + * Return: 0 on success, -1 on failure + */ +static int nl_linkaddr_init_do(void *arg) +{ + struct sockaddr_nl addr = { .nl_family = AF_NETLINK, + .nl_groups = RTMGRP_LINK | RTMGRP_IPV4_IFADDR | + RTMGRP_IPV6_IFADDR }; + + if (arg) + ns_enter((struct ctx *)arg); + + nl_sock_linkaddr = socket(AF_NETLINK, SOCK_RAW | SOCK_CLOEXEC, NETLINK_ROUTE);

Is there a reason to use an additional socket, rather than adding more events to the neighbour listening socket?

None in particular. I'll look into it.

...

+ if (nl_sock_linkaddr < 0) { + debug("socket() failed: %s", strerror_(errno)); + return -1; + } + + if (bind(nl_sock_linkaddr, (struct sockaddr *)&addr, sizeof(addr)) < 0) { + debug("bind() failed: %s", strerror_(errno)); + close(nl_sock_linkaddr); + nl_sock_linkaddr = -1; + return -1; + } + + debug("socket fd=%d", nl_sock_linkaddr); + return 0; +} + +/** + * nl_linkaddr_notify_init() - Initialize link/address change notifier + * @c: Execution context + * + * Return: 0 on success, -1 on failure + */ +int nl_linkaddr_notify_init(const struct ctx *c) +{ + union epoll_ref ref = { .type = EPOLL_TYPE_NL_LINKADDR }; + struct epoll_event ev = { .events = EPOLLIN }; + + if (nl_sock_linkaddr >= 0) { + debug("notifier already initialized (fd=%d)", nl_sock_linkaddr); + return 0; + } + + /* Open the notifier socket in the namespace for pasta mode, + * or in the init namespace otherwise.

Definitely wrong. We're trying to watch host addresses so that we can copy them to the guest - therefore we always need to watch in the host netns. On pasta there might be reasons to *also* listen in the guest netns, but that would want a different handler to do different things.

Hmm. I think I'll wait for your feedback on the remaining patches before I comment on this. /jon