Re: [PATCH v6 07/13] ip: refactor function pasta_ns_conf()

Nit: starting the subject with "ip:" when the patch doesn't touch ip.c doesn't make a lot of sense. I think "netlink, pasta:" would make more sense. On Sat, Mar 21, 2026 at 08:43:27PM -0400, Jon Maloy wrote:

After the previous changes in this series it becomes possible to simplify the pasta_ns_conf() function.

We extract address and route configuration into helper functions pasta_conf_addrs() and pasta_conf_routes(), reducing nesting and improving readability.

To allow pasta_conf_addrs() to handle both address families uniformly, we change nl_addr_set() to take a union inany_addr pointer instead of void pointer, moving the address family handling into the function itself.

We also fix a bug where the IPv6 code path incorrectly wrote to req.set.a4.rta_l.rta_type instead of req.set.a6.rta_l.rta_type.

Signed-off-by: Jon Maloy --- netlink.c | 13 +-- netlink.h | 2 +- pasta.c | 232 +++++++++++++++++++++++++++--------------------------- 3 files changed, 124 insertions(+), 123 deletions(-)

diff --git a/netlink.c b/netlink.c index 2727eec..fcdc983 100644 --- a/netlink.c +++ b/netlink.c @@ -870,7 +870,7 @@ int nl_addr_get_ll(int s, unsigned int ifi, struct in6_addr *addr) * Return: 0 on success, negative error code on failure */ int nl_addr_set(int s, unsigned int ifi, sa_family_t af,

You should be able to extract the family from the inany and remove this parameter, no? (Pre-existing: arguably we should set ifa_scope based on the address, rather than assuming RT_SCOPE_UNIVERSE, too)

- const void *addr, int prefix_len) + const union inany_addr *addr, int prefix_len) { struct req_t { struct nlmsghdr nlh; @@ -905,21 +905,22 @@ int nl_addr_set(int s, unsigned int ifi, sa_family_t af,

len = offsetof(struct req_t, set.a6) + sizeof(req.set.a6);

- memcpy(&req.set.a6.l, addr, sizeof(req.set.a6.l)); + memcpy(&req.set.a6.l, &addr->a6, sizeof(req.set.a6.l)); req.set.a6.rta_l.rta_len = rta_len; - req.set.a4.rta_l.rta_type = IFA_LOCAL; - memcpy(&req.set.a6.a, addr, sizeof(req.set.a6.a)); + req.set.a6.rta_l.rta_type = IFA_LOCAL; + memcpy(&req.set.a6.a, &addr->a6, sizeof(req.set.a6.a)); req.set.a6.rta_a.rta_len = rta_len; req.set.a6.rta_a.rta_type = IFA_ADDRESS; } else { + const struct in_addr *v4 = inany_v4(addr); size_t rta_len = RTA_LENGTH(sizeof(req.set.a4.l));

len = offsetof(struct req_t, set.a4) + sizeof(req.set.a4);

- memcpy(&req.set.a4.l, addr, sizeof(req.set.a4.l)); + memcpy(&req.set.a4.l, v4, sizeof(req.set.a4.l)); req.set.a4.rta_l.rta_len = rta_len; req.set.a4.rta_l.rta_type = IFA_LOCAL; - memcpy(&req.set.a4.a, addr, sizeof(req.set.a4.a)); + memcpy(&req.set.a4.a, v4, sizeof(req.set.a4.a)); req.set.a4.rta_a.rta_len = rta_len; req.set.a4.rta_a.rta_type = IFA_ADDRESS; } diff --git a/netlink.h b/netlink.h index 3af6d58..26f5ef7 100644 --- a/netlink.h +++ b/netlink.h @@ -23,7 +23,7 @@ int nl_addr_get_all(struct ctx *c, int s, unsigned int ifi, sa_family_t af); bool nl_neigh_mac_get(int s, const union inany_addr *addr, int ifi, unsigned char *mac); int nl_addr_set(int s, unsigned int ifi, sa_family_t af, - const void *addr, int prefix_len); + const union inany_addr *addr, int prefix_len); int nl_addr_get_ll(int s, unsigned int ifi, struct in6_addr *addr); int nl_addr_set_ll_nodad(int s, unsigned int ifi); int nl_addr_dup(int s_src, unsigned int ifi_src, diff --git a/pasta.c b/pasta.c index 6307c65..b8d7cf4 100644 --- a/pasta.c +++ b/pasta.c @@ -46,6 +46,7 @@

#include "util.h" #include "passt.h" +#include "conf.h" #include "isolation.h" #include "netlink.h" #include "log.h" @@ -303,13 +304,73 @@ void pasta_start_ns(struct ctx *c, uid_t uid, gid_t gid, die_perror("Failed to join network namespace"); }

+/** + * pasta_conf_addrs() - Configure addresses for one address family in namespace + * @c: Execution context + * @af: Address family (AF_INET or AF_INET6)

Eventually, I think it would be nicer to set all the addresses (v4 and v6) from a single loop. However, I can see that this is a useful interim step, because doing that straight away would make things a bit awkward in the caller.

+ * @ifi: Host interface index for this address family + * @no_copy: If true, set addresses from c->addrs; if false, copy from host + * + * Return: 0 on success, negative error code on failure + */ +static int pasta_conf_addrs(struct ctx *c, sa_family_t af, + int ifi, bool no_copy) +{ + const struct guest_addr *a; + + if (!ifi) + return 0; + + if (!no_copy) + return nl_addr_dup(nl_sock, ifi, nl_sock_ns, c->pasta_ifi, af); + + for_each_addr(a, c, af) { + int rc; + + /* Skip link-local, kernel auto-configures */

Hrm... conceptually it's an array of *guest* addresses, even if take from the host. So link-local addresses should probably be excluded from the list before they're inserted, rather than when we're reading it.

+ if (a->flags & CONF_ADDR_LINKLOCAL) + continue; + + rc = nl_addr_set(nl_sock_ns, c->pasta_ifi, af, &a->addr, + inany_prefix_len(a)); + if (rc < 0) + return rc; + } + return 0; +} + +/** + * pasta_conf_routes() - Configure routes for one address family in namespace + * @c: Execution context + * @af: Address family (AF_INET or AF_INET6) + * @ifi: Host interface index for this address family + * @no_copy: If true, set default route; if false, copy routes from host + * + * Return: 0 on success, negative error code on failure + */ +static int pasta_conf_routes(struct ctx *c, sa_family_t af, int ifi, + bool no_copy) +{ + const void *gw = (af == AF_INET) ? + (const void *)&c->ip4.guest_gw : (const void *)&c->ip6.guest_gw; + + if (!ifi) + return 0; + + if (no_copy) + return nl_route_set_def(nl_sock_ns, c->pasta_ifi, af, gw); + + return nl_route_dup(nl_sock, ifi, nl_sock_ns, c->pasta_ifi, af); +} + /** * pasta_ns_conf() - Set up loopback and tap interfaces in namespace as needed * @c: Execution context */ void pasta_ns_conf(struct ctx *c) { - int rc = 0; + unsigned int flags = IFF_UP; + int rc;

rc = nl_link_set_flags(nl_sock_ns, 1 /* lo */, IFF_UP, IFF_UP); if (rc < 0) @@ -328,123 +389,62 @@ void pasta_ns_conf(struct ctx *c) die("Couldn't set MAC address in namespace: %s", strerror_(-rc));

- if (c->pasta_conf_ns) { - unsigned int flags = IFF_UP; - const struct guest_addr *a; - - if (c->mtu) - nl_link_set_mtu(nl_sock_ns, c->pasta_ifi, c->mtu); - - if (c->ifi6) /* Avoid duplicate address detection on link up */ - flags |= IFF_NOARP; - - nl_link_set_flags(nl_sock_ns, c->pasta_ifi, flags, flags); - - if (c->ifi4) { - if (c->ip4.no_copy_addrs) { - for_each_addr(a, c, AF_INET) { - rc = nl_addr_set(nl_sock_ns, - c->pasta_ifi, AF_INET, - inany_v4(&a->addr), - inany_prefix_len(a)); - if (rc < 0) - break; - } - } else { - rc = nl_addr_dup(nl_sock, c->ifi4, - nl_sock_ns, c->pasta_ifi, - AF_INET); - } - - if (c->ifi4 == -1 && rc == -ENOTSUP) { - warn("IPv4 not supported, disabling"); - c->ifi4 = 0; - goto ipv4_done; - } - - if (rc < 0) { - die("Couldn't set IPv4 address(es) in namespace: %s", - strerror_(-rc)); - } - - if (c->ip4.no_copy_routes) { - rc = nl_route_set_def(nl_sock_ns, c->pasta_ifi, - AF_INET, - &c->ip4.guest_gw); - } else { - rc = nl_route_dup(nl_sock, c->ifi4, nl_sock_ns, - c->pasta_ifi, AF_INET); - } - - if (rc < 0) { - die("Couldn't set IPv4 route(s) in guest: %s", - strerror_(-rc)); - } - } -ipv4_done: - - if (c->ifi6) { - rc = nl_addr_get_ll(nl_sock_ns, c->pasta_ifi, - &c->ip6.addr_ll_seen); - if (rc < 0) { - warn("Can't get LL address from namespace: %s", - strerror_(-rc)); - } - - rc = nl_addr_set_ll_nodad(nl_sock_ns, c->pasta_ifi); - if (rc < 0) { - warn("Can't set nodad for LL in namespace: %s", - strerror_(-rc)); - } - - /* We dodged DAD: re-enable neighbour solicitations */ - nl_link_set_flags(nl_sock_ns, c->pasta_ifi, - 0, IFF_NOARP); - - if (c->ip6.no_copy_addrs) { - for_each_addr(a, c, AF_INET6) { - rc = nl_addr_set(nl_sock_ns, - c->pasta_ifi, - AF_INET6, &a->addr.a6, - a->prefix_len); - if (rc < 0) - break; - } - } else { - rc = nl_addr_dup(nl_sock, c->ifi6, - nl_sock_ns, c->pasta_ifi, - AF_INET6); - } - - if (rc < 0) { - die("Couldn't set IPv6 address(es) in namespace: %s", - strerror_(-rc)); - } - - if (c->ip6.no_copy_routes) { - rc = nl_route_set_def(nl_sock_ns, c->pasta_ifi, - AF_INET6, - &c->ip6.guest_gw); - } else { - rc = nl_route_dup(nl_sock, c->ifi6, - nl_sock_ns, c->pasta_ifi, - AF_INET6); - } - - if (c->ifi6 == -1 && rc == -ENOTSUP) { - warn("IPv6 not supported, disabling"); - c->ifi6 = 0; - goto ipv6_done; - } - - if (rc < 0) { - die("Couldn't set IPv6 route(s) in guest: %s", - strerror_(-rc)); - } - } + if (!c->pasta_conf_ns) + goto done; + + if (c->mtu) + nl_link_set_mtu(nl_sock_ns, c->pasta_ifi, c->mtu); + + if (c->ifi6) /* Avoid duplicate address detection on link up */ + flags |= IFF_NOARP; + + nl_link_set_flags(nl_sock_ns, c->pasta_ifi, flags, flags); + + /* IPv4 configuration */ + rc = pasta_conf_addrs(c, AF_INET, c->ifi4, c->ip4.no_copy_addrs); + if (c->ifi4 == -1 && rc == -ENOTSUP) { + warn("IPv4 not supported, disabling"); + c->ifi4 = 0; + } else if (rc < 0) { + die("Couldn't set IPv4 address(es): %s", strerror_(-rc)); + } else if (c->ifi4) { + rc = pasta_conf_routes(c, AF_INET, c->ifi4, + c->ip4.no_copy_routes); + if (rc < 0) + die("Couldn't set IPv4 route(s): %s", strerror_(-rc)); + } + + if (!c->ifi6) + goto done; + + rc = nl_addr_get_ll(nl_sock_ns, c->pasta_ifi, + &c->ip6.addr_ll_seen); + if (rc < 0) + warn("Can't get LL address from namespace: %s", + strerror_(-rc)); + + rc = nl_addr_set_ll_nodad(nl_sock_ns, c->pasta_ifi); + if (rc < 0) + warn("Can't set nodad for LL in namespace: %s", + strerror_(-rc)); + + /* We dodged DAD: re-enable neighbour solicitations */ + nl_link_set_flags(nl_sock_ns, c->pasta_ifi, 0, IFF_NOARP); + + rc = pasta_conf_addrs(c, AF_INET6, c->ifi6, c->ip6.no_copy_addrs); + if (c->ifi6 == -1 && rc == -ENOTSUP) { + warn("IPv6 not supported, disabling"); + c->ifi6 = 0; + } else if (rc < 0) { + die("Couldn't set IPv6 address(es): %s", strerror_(-rc)); + } else { + rc = pasta_conf_routes(c, AF_INET6, c->ifi6, + c->ip6.no_copy_routes); + if (rc < 0) + die("Couldn't set IPv6 route(s): %s", strerror_(-rc)); } -ipv6_done:

+done: proto_update_l2_buf(c->guest_mac);

Could we move this up before the if (c->pasta_conf_ns), rather than having an awkward goto?

}

-- 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