On Sun, Feb 22, 2026 at 12:44:40PM -0500, Jon Maloy wrote:
We remove the addr_seen and addr_ll_seen fields in struct ip6_ctx and replace them by setting CONF_ADDR_OBSERVED and CONF_ADDR_LINKLOCAL flags in the corresponding entry in the unified address array.
The observed IPv6 address is always added/moved to position 0 in the array, improving chances for fast lookup.
This completes the unification of address storage for both IPv4 and IPv6, enabling future support for multiple guest addresses per family.
Signed-off-by: Jon Maloy
--- v5: - Made to use same algorithm and function as IPv4 for inserting observed into the array. --- conf.c | 2 -- dhcpv6.c | 6 +----- dhcpv6.h | 2 +- migrate.c | 27 +++++++++++++++++++------- passt.h | 4 ---- pasta.c | 17 +++++++++++++---- tap.c | 57 +++++++++++++++++++++++++++++++++---------------------- 7 files changed, 69 insertions(+), 46 deletions(-)
As noted in the previous patch, there are several hunks from there that ought to be in this patch.
diff --git a/conf.c b/conf.c index faa60ec..f622424 100644 --- a/conf.c +++ b/conf.c @@ -816,8 +816,6 @@ static unsigned int conf_ip6(struct ctx *c, unsigned int ifi) e->flags = CONF_ADDR_HOST; }
- ip6->addr_seen = e->addr.a6; - if (IN6_IS_ADDR_LINKLOCAL(&ip6->guest_gw)) ip6->our_tap_ll = ip6->guest_gw;
diff --git a/dhcpv6.c b/dhcpv6.c index 55c17cf..ba200e5 100644 --- a/dhcpv6.c +++ b/dhcpv6.c @@ -549,7 +549,7 @@ static size_t dhcpv6_client_fqdn_fill(const struct iov_tail *data, * Return: 0 if it's not a DHCPv6 message, 1 if handled, -1 on failure */ int dhcpv6(struct ctx *c, struct iov_tail *data, - const struct in6_addr *saddr, const struct in6_addr *daddr) + const struct in6_addr *daddr) { const struct opt_server_id *server_id = NULL; struct inany_addr_entry *e = first_v6(c); @@ -591,8 +591,6 @@ int dhcpv6(struct ctx *c, struct iov_tail *data, if (mlen + sizeof(*uh) != ntohs(uh->len) || mlen < sizeof(*mh)) return -1;
- c->ip6.addr_ll_seen = *saddr; -
Removing this without a replacement doesn't look correct to me. Possibly it's redundant anyway with code in tap.c, but if that's so removing it in a separate patch with its own rationale would make it clearer.
src = &c->ip6.our_tap_ll;
mh = IOV_REMOVE_HEADER(data, mh_storage); @@ -683,8 +681,6 @@ 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); - if (e) - c->ip6.addr_seen = e->addr.a6;
return 1; } diff --git a/dhcpv6.h b/dhcpv6.h index c706dfd..8cbc769 100644 --- a/dhcpv6.h +++ b/dhcpv6.h @@ -7,7 +7,7 @@ #define DHCPV6_H
int dhcpv6(struct ctx *c, struct iov_tail *data, - struct in6_addr *saddr, struct in6_addr *daddr); + struct in6_addr *daddr); void dhcpv6_init(const struct ctx *c);
#endif /* DHCPV6_H */ diff --git a/migrate.c b/migrate.c index f026e95..1e2830f 100644 --- a/migrate.c +++ b/migrate.c @@ -56,10 +56,7 @@ struct migrate_seen_addrs_v1 { static int seen_addrs_source_v1(struct ctx *c, const struct migrate_stage *stage, int fd) { - struct migrate_seen_addrs_v1 addrs = { - .addr6 = c->ip6.addr_seen, - .addr6_ll = c->ip6.addr_ll_seen, - }; + struct migrate_seen_addrs_v1 addrs = { 0 }; const struct inany_addr_entry *e;
(void)stage; @@ -69,6 +66,15 @@ static int seen_addrs_source_v1(struct ctx *c, if (e) addrs.addr4 = *inany_v4(&e->addr);
+ /* IPv6 observed address */ + e = fwd_get_addr(c, AF_INET6, CONF_ADDR_OBSERVED, 0);
As for v4, you need a fall back if there's no observed address.
+ if (e) { + if (e->flags & CONF_ADDR_LINKLOCAL) + addrs.addr6_ll = e->addr.a6; + else + addrs.addr6 = e->addr.a6; + }
This isn't right. You need to populate *both* addr6 and addr6_ll, not one or the other.
+ memcpy(addrs.mac, c->guest_mac, sizeof(addrs.mac));
if (write_all_buf(fd, &addrs, sizeof(addrs))) @@ -89,6 +95,7 @@ static int seen_addrs_target_v1(struct ctx *c, const struct migrate_stage *stage, int fd) { struct migrate_seen_addrs_v1 addrs; + struct in6_addr addr6, addr6_ll; struct in_addr addr4;
(void)stage; @@ -96,14 +103,20 @@ static int seen_addrs_target_v1(struct ctx *c, if (read_all_buf(fd, &addrs, sizeof(addrs))) return errno;
- c->ip6.addr_seen = addrs.addr6; - c->ip6.addr_ll_seen = addrs.addr6_ll; - /* Copy from packed struct to avoid alignment issues */ addr4 = addrs.addr4; + addr6 = addrs.addr6; + addr6_ll = addrs.addr6_ll; + if (addr4.s_addr) fwd_set_addr(c, &inany_from_v4(addr4), CONF_ADDR_OBSERVED, 0);
+ /* Prefer global over link-local if both present */ + if (!IN6_IS_ADDR_UNSPECIFIED(&addr6)) + fwd_set_addr(c, &inany_from_v6(addr6), CONF_ADDR_OBSERVED, 0); + else if (!IN6_IS_ADDR_UNSPECIFIED(&addr6_ll)) + fwd_set_addr(c, &inany_from_v6(addr6_ll), CONF_ADDR_OBSERVED, 0);
Likewise, you need to put both the LL and non-LL observed addresses back into the table, not just one.
memcpy(c->guest_mac, addrs.mac, sizeof(c->guest_mac));
return 0; diff --git a/passt.h b/passt.h index b808a19..e7489ca 100644 --- a/passt.h +++ b/passt.h @@ -112,8 +112,6 @@ struct ip4_ctx {
/** * struct ip6_ctx - IPv6 execution context - * @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 * @map_host_loopback: Outbound connections to this address are NATted to the * host's [::1] @@ -129,8 +127,6 @@ struct ip4_ctx { * @no_copy_addrs: Don't copy all addresses when configuring namespace */ struct ip6_ctx { - struct in6_addr addr_seen; - struct in6_addr addr_ll_seen; struct in6_addr guest_gw; struct in6_addr map_host_loopback; struct in6_addr map_guest_addr; diff --git a/pasta.c b/pasta.c index 7a081e7..56b2e0a 100644 --- a/pasta.c +++ b/pasta.c @@ -46,6 +46,8 @@
#include "util.h" #include "passt.h" +#include "conf.h" +#include "fwd.h" #include "isolation.h" #include "netlink.h" #include "log.h" @@ -384,12 +386,15 @@ void pasta_ns_conf(struct ctx *c) ipv4_done:
if (c->ifi6) { - rc = nl_addr_get_ll(nl_sock_ns, c->pasta_ifi, - &c->ip6.addr_ll_seen); - if (rc < 0) { + struct in6_addr addr_ll; + + rc = nl_addr_get_ll(nl_sock_ns, c->pasta_ifi, &addr_ll); + if (rc < 0) warn("Can't get LL address from namespace: %s", strerror_(-rc)); - } + else + fwd_set_addr(c, &inany_from_v6(addr_ll), + CONF_ADDR_OBSERVED, 0);
rc = nl_addr_set_ll_nodad(nl_sock_ns, c->pasta_ifi); if (rc < 0) { @@ -403,6 +408,10 @@ ipv4_done:
if (c->ip6.no_copy_addrs) { for_each_addr(e, c, AF_INET6) { + /* Skip, kernel auto-configures */ + if (e->flags & CONF_ADDR_LINKLOCAL) + continue;
This seems like it belongs in an earlier patch - it's not really related to observed addresses specifically.
rc = nl_addr_set(nl_sock_ns, c->pasta_ifi, AF_INET6, &e->addr.a6, diff --git a/tap.c b/tap.c index 30e52f7..875c2bf 100644 --- a/tap.c +++ b/tap.c @@ -174,6 +174,17 @@ static void tap_check_src_addr4(struct ctx *c, const struct in_addr *addr) fwd_set_addr(c, &inany_from_v4(*addr), CONF_ADDR_OBSERVED, 0); }
+/** + * tap_check_src_addr6() - Note an IPv6 address seen in guest traffic + * @c: Execution context + * @addr: IPv6 address seen as source from guest + */ +static void tap_check_src_addr6(struct ctx *c, const struct in6_addr *addr) +{ + if (!IN6_IS_ADDR_UNSPECIFIED(addr)) + fwd_set_addr(c, &inany_from_v6(*addr), CONF_ADDR_OBSERVED, 0); +} + /** * tap_ip6_daddr() - Normal IPv6 destination address for inbound packets * @c: Execution context @@ -184,9 +195,25 @@ static void tap_check_src_addr4(struct ctx *c, const struct in_addr *addr) const struct in6_addr *tap_ip6_daddr(const struct ctx *c, const struct in6_addr *src) { - if (IN6_IS_ADDR_LINKLOCAL(src)) - return &c->ip6.addr_ll_seen; - return &c->ip6.addr_seen; + const struct inany_addr_entry *e; + + if (IN6_IS_ADDR_LINKLOCAL(src)) { + /* Link-local: first LL address (observed is at front) */ + e = fwd_get_addr(c, AF_INET6, CONF_ADDR_LINKLOCAL, 0); + } else { + /* Global: observed non-LL first, then any non-LL */
Do you need this in addition to your logic to put observed addresses at the beginning of the array?
+ e = fwd_get_addr(c, AF_INET6, CONF_ADDR_OBSERVED, + CONF_ADDR_LINKLOCAL); + if (!e) + e = fwd_get_addr(c, AF_INET6, 0, CONF_ADDR_LINKLOCAL); + } + + if (e) + return &e->addr.a6; + + /* Last resort: first IPv6 address */ + e = first_v6(c);
I think we should fail rather than falling back further. We really mustn't mix linklocal and non-linklocal addresses in a packet.
+ return e ? &e->addr.a6 : &in6addr_any; }
/** @@ -786,7 +813,7 @@ resume:
if (iph->saddr) tap_check_src_addr4(c, - (const struct in_addr *)&iph->saddr); + (const struct in_addr *)&iph->saddr);
Unrelated whitespace change
if (!iov_drop_header(&data, hlen)) continue; @@ -958,24 +985,8 @@ resume: continue; }
- if (IN6_IS_ADDR_LINKLOCAL(saddr)) { - c->ip6.addr_ll_seen = *saddr; - - if (IN6_IS_ADDR_UNSPECIFIED(&c->ip6.addr_seen)) { - c->ip6.addr_seen = *saddr; - } - - if (!first_v6(c) && c->addr_count < INANY_MAX_ADDRS) { - struct inany_addr_entry *e; - - e = &c->addrs[c->addr_count++]; - e->addr.a6 = *saddr; - e->prefix_len = 64; - e->flags = CONF_ADDR_LINKLOCAL; - } - } else if (!IN6_IS_ADDR_UNSPECIFIED(saddr)){ - c->ip6.addr_seen = *saddr; - } + if (!IN6_IS_ADDR_UNSPECIFIED(saddr))
Redundant with the check inside tap_check_src_addr6().
+ tap_check_src_addr6(c, saddr);
if (proto == IPPROTO_ICMPV6) { struct iov_tail ndp_data; @@ -1006,7 +1017,7 @@ resume: if (proto == IPPROTO_UDP) { struct iov_tail uh_data = data;
- if (dhcpv6(c, &uh_data, saddr, daddr)) + if (dhcpv6(c, &uh_data, daddr)) continue; }
-- 2.52.0
-- 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