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network/ndisc: drop onlink prefix route when on-link flag is zero

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Fixes #28435.
This commit is contained in:
Yu Watanabe 2024-02-02 16:08:23 +09:00
parent a8b0b84822
commit 155d7a2c04
1 changed files with 68 additions and 4 deletions
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72
src/network/networkd-ndisc.c
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@ -545,6 +545,69 @@ static int ndisc_router_process_onlink_prefix(Link *link, sd_ndisc_router *rt) {
return 0;
}
static int ndisc_router_drop_onlink_prefix(Link *link, sd_ndisc_router *rt) {
_cleanup_(route_unrefp) Route *route = NULL;
unsigned prefixlen, preference;
struct in6_addr prefix;
usec_t lifetime_usec;
int r;
assert(link);
assert(link->network);
assert(rt);
/* RFC 4861 section 6.3.4.
* Note, however, that a Prefix Information option with the on-link flag set to zero conveys no
* information concerning on-link determination and MUST NOT be interpreted to mean that addresses
* covered by the prefix are off-link. The only way to cancel a previous on-link indication is to
* advertise that prefix with the L-bit set and the Lifetime set to zero. */
if (!link->network->ipv6_accept_ra_use_onlink_prefix)
return 0;
r = sd_ndisc_router_prefix_get_valid_lifetime(rt, &lifetime_usec);
if (r < 0)
return log_link_warning_errno(link, r, "Failed to get prefix lifetime: %m");
if (lifetime_usec != 0)
return 0;
r = sd_ndisc_router_prefix_get_address(rt, &prefix);
if (r < 0)
return log_link_warning_errno(link, r, "Failed to get prefix address: %m");
r = sd_ndisc_router_prefix_get_prefixlen(rt, &prefixlen);
if (r < 0)
return log_link_warning_errno(link, r, "Failed to get prefix length: %m");
/* Prefix Information option does not have preference, hence we use the 'main' preference here */
r = sd_ndisc_router_get_preference(rt, &preference);
if (r < 0)
return log_link_warning_errno(link, r, "Failed to get router preference from RA: %m");
r = route_new(&route);
if (r < 0)
return log_oom();
route->family = AF_INET6;
route->dst.in6 = prefix;
route->dst_prefixlen = prefixlen;
route->table = link_get_ipv6_accept_ra_route_table(link);
route->pref = preference;
ndisc_set_route_priority(link, route);
route->protocol = RTPROT_RA;
r = route_adjust_nexthops(route, link);
if (r < 0)
return r;
r = route_remove_and_cancel(route, link->manager);
if (r < 0)
return log_link_warning_errno(link, r, "Could not remove prefix route: %m");
return 0;
}
static int ndisc_router_process_prefix(Link *link, sd_ndisc_router *rt) {
unsigned prefixlen;
struct in6_addr a;
@ -584,11 +647,12 @@ static int ndisc_router_process_prefix(Link *link, sd_ndisc_router *rt) {
if (r < 0)
return log_link_warning_errno(link, r, "Failed to get RA prefix flags: %m");
if (FLAGS_SET(flags, ND_OPT_PI_FLAG_ONLINK)) {
if (FLAGS_SET(flags, ND_OPT_PI_FLAG_ONLINK))
r = ndisc_router_process_onlink_prefix(link, rt);
if (r < 0)
return r;
}
else
r = ndisc_router_drop_onlink_prefix(link, rt);
if (r < 0)
return r;
if (FLAGS_SET(flags, ND_OPT_PI_FLAG_AUTO)) {
r = ndisc_router_process_autonomous_prefix(link, rt);