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Systemd/src/resolve/resolved-link.c
Lennart Poettering dfc1091b2f resolved: allocate DNS scope for links only if the interface is up 
For mDNS and LLMNR we already created the scopes only if the specific interfaces where actually up and suitable for
Multicasting. Add a similar (but weaker) logic for unicast DNS as well.
2016-01-19 18:37:45 +01:00

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/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
/***
This file is part of systemd.
Copyright 2014 Lennart Poettering
systemd is free software; you can redistribute it and/or modify it
under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or
(at your option) any later version.
systemd is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with systemd; If not, see <http://www.gnu.org/licenses/>.
***/
#include <net/if.h>
#include "sd-network.h"
#include "alloc-util.h"
#include "missing.h"
#include "parse-util.h"
#include "resolved-link.h"
#include "string-util.h"
#include "strv.h"
int link_new(Manager *m, Link **ret, int ifindex) {
_cleanup_(link_freep) Link *l = NULL;
int r;
assert(m);
assert(ifindex > 0);
r = hashmap_ensure_allocated(&m->links, NULL);
if (r < 0)
return r;
l = new0(Link, 1);
if (!l)
return -ENOMEM;
l->ifindex = ifindex;
l->llmnr_support = RESOLVE_SUPPORT_YES;
l->mdns_support = RESOLVE_SUPPORT_NO;
l->dnssec_mode = _DNSSEC_MODE_INVALID;
r = hashmap_put(m->links, INT_TO_PTR(ifindex), l);
if (r < 0)
return r;
l->manager = m;
if (ret)
*ret = l;
l = NULL;
return 0;
}
Link *link_free(Link *l) {
if (!l)
return NULL;
dns_server_unlink_all(l->dns_servers);
dns_search_domain_unlink_all(l->search_domains);
while (l->addresses)
link_address_free(l->addresses);
if (l->manager)
hashmap_remove(l->manager->links, INT_TO_PTR(l->ifindex));
dns_scope_free(l->unicast_scope);
dns_scope_free(l->llmnr_ipv4_scope);
dns_scope_free(l->llmnr_ipv6_scope);
dns_scope_free(l->mdns_ipv4_scope);
dns_scope_free(l->mdns_ipv6_scope);
set_free_free(l->dnssec_negative_trust_anchors);
free(l);
return NULL;
}
static void link_allocate_scopes(Link *l) {
int r;
assert(l);
if (link_relevant(l, AF_UNSPEC, false) &&
l->dns_servers) {
if (!l->unicast_scope) {
r = dns_scope_new(l->manager, &l->unicast_scope, l, DNS_PROTOCOL_DNS, AF_UNSPEC);
if (r < 0)
log_warning_errno(r, "Failed to allocate DNS scope: %m");
}
} else
l->unicast_scope = dns_scope_free(l->unicast_scope);
if (link_relevant(l, AF_INET, true) &&
l->llmnr_support != RESOLVE_SUPPORT_NO &&
l->manager->llmnr_support != RESOLVE_SUPPORT_NO) {
if (!l->llmnr_ipv4_scope) {
r = dns_scope_new(l->manager, &l->llmnr_ipv4_scope, l, DNS_PROTOCOL_LLMNR, AF_INET);
if (r < 0)
log_warning_errno(r, "Failed to allocate LLMNR IPv4 scope: %m");
}
} else
l->llmnr_ipv4_scope = dns_scope_free(l->llmnr_ipv4_scope);
if (link_relevant(l, AF_INET6, true) &&
l->llmnr_support != RESOLVE_SUPPORT_NO &&
l->manager->llmnr_support != RESOLVE_SUPPORT_NO &&
socket_ipv6_is_supported()) {
if (!l->llmnr_ipv6_scope) {
r = dns_scope_new(l->manager, &l->llmnr_ipv6_scope, l, DNS_PROTOCOL_LLMNR, AF_INET6);
if (r < 0)
log_warning_errno(r, "Failed to allocate LLMNR IPv6 scope: %m");
}
} else
l->llmnr_ipv6_scope = dns_scope_free(l->llmnr_ipv6_scope);
if (link_relevant(l, AF_INET, true) &&
l->mdns_support != RESOLVE_SUPPORT_NO &&
l->manager->mdns_support != RESOLVE_SUPPORT_NO) {
if (!l->mdns_ipv4_scope) {
r = dns_scope_new(l->manager, &l->mdns_ipv4_scope, l, DNS_PROTOCOL_MDNS, AF_INET);
if (r < 0)
log_warning_errno(r, "Failed to allocate mDNS IPv4 scope: %m");
}
} else
l->mdns_ipv4_scope = dns_scope_free(l->mdns_ipv4_scope);
if (link_relevant(l, AF_INET6, true) &&
l->mdns_support != RESOLVE_SUPPORT_NO &&
l->manager->mdns_support != RESOLVE_SUPPORT_NO) {
if (!l->mdns_ipv6_scope) {
r = dns_scope_new(l->manager, &l->mdns_ipv6_scope, l, DNS_PROTOCOL_MDNS, AF_INET6);
if (r < 0)
log_warning_errno(r, "Failed to allocate mDNS IPv6 scope: %m");
}
} else
l->mdns_ipv6_scope = dns_scope_free(l->mdns_ipv6_scope);
}
void link_add_rrs(Link *l, bool force_remove) {
LinkAddress *a;
LIST_FOREACH(addresses, a, l->addresses)
link_address_add_rrs(a, force_remove);
}
int link_update_rtnl(Link *l, sd_netlink_message *m) {
const char *n = NULL;
int r;
assert(l);
assert(m);
r = sd_rtnl_message_link_get_flags(m, &l->flags);
if (r < 0)
return r;
sd_netlink_message_read_u32(m, IFLA_MTU, &l->mtu);
if (sd_netlink_message_read_string(m, IFLA_IFNAME, &n) >= 0) {
strncpy(l->name, n, sizeof(l->name)-1);
char_array_0(l->name);
}
link_allocate_scopes(l);
link_add_rrs(l, false);
return 0;
}
static int link_update_dns_servers(Link *l) {
_cleanup_strv_free_ char **nameservers = NULL;
char **nameserver;
int r;
assert(l);
r = sd_network_link_get_dns(l->ifindex, &nameservers);
if (r == -ENODATA) {
r = 0;
goto clear;
}
if (r < 0)
goto clear;
dns_server_mark_all(l->dns_servers);
STRV_FOREACH(nameserver, nameservers) {
union in_addr_union a;
DnsServer *s;
int family;
r = in_addr_from_string_auto(*nameserver, &family, &a);
if (r < 0)
goto clear;
s = dns_server_find(l->dns_servers, family, &a);
if (s)
dns_server_move_back_and_unmark(s);
else {
r = dns_server_new(l->manager, NULL, DNS_SERVER_LINK, l, family, &a);
if (r < 0)
goto clear;
}
}
dns_server_unlink_marked(l->dns_servers);
return 0;
clear:
dns_server_unlink_all(l->dns_servers);
return r;
}
static int link_update_llmnr_support(Link *l) {
_cleanup_free_ char *b = NULL;
int r;
assert(l);
r = sd_network_link_get_llmnr(l->ifindex, &b);
if (r == -ENODATA) {
r = 0;
goto clear;
}
if (r < 0)
goto clear;
l->llmnr_support = resolve_support_from_string(b);
if (l->llmnr_support < 0) {
r = -EINVAL;
goto clear;
}
return 0;
clear:
l->llmnr_support = RESOLVE_SUPPORT_YES;
return r;
}
static int link_update_mdns_support(Link *l) {
_cleanup_free_ char *b = NULL;
int r;
assert(l);
r = sd_network_link_get_mdns(l->ifindex, &b);
if (r == -ENODATA) {
r = 0;
goto clear;
}
if (r < 0)
goto clear;
l->mdns_support = resolve_support_from_string(b);
if (l->mdns_support < 0) {
r = -EINVAL;
goto clear;
}
return 0;
clear:
l->mdns_support = RESOLVE_SUPPORT_NO;
return r;
}
static int link_update_dnssec_mode(Link *l) {
_cleanup_free_ char *m = NULL;
DnssecMode mode;
int r;
assert(l);
r = sd_network_link_get_dnssec(l->ifindex, &m);
if (r == -ENODATA) {
r = 0;
goto clear;
}
if (r < 0)
goto clear;
mode = dnssec_mode_from_string(m);
if (mode < 0) {
r = -EINVAL;
goto clear;
}
if ((l->dnssec_mode == DNSSEC_NO && mode != DNSSEC_NO) ||
(l->dnssec_mode == DNSSEC_ALLOW_DOWNGRADE && mode == DNSSEC_YES)) {
/* When switching from non-DNSSEC mode to DNSSEC mode, flush the cache. Also when switching from the
* allow-downgrade mode to full DNSSEC mode, flush it too. */
if (l->unicast_scope)
dns_cache_flush(&l->unicast_scope->cache);
}
l->dnssec_mode = mode;
return 0;
clear:
l->dnssec_mode = _DNSSEC_MODE_INVALID;
return r;
}
static int link_update_dnssec_negative_trust_anchors(Link *l) {
_cleanup_strv_free_ char **ntas = NULL;
_cleanup_set_free_free_ Set *ns = NULL;
char **i;
int r;
assert(l);
r = sd_network_link_get_dnssec_negative_trust_anchors(l->ifindex, &ntas);
if (r == -ENODATA) {
r = 0;
goto clear;
}
if (r < 0)
goto clear;
ns = set_new(&dns_name_hash_ops);
if (!ns)
return -ENOMEM;
STRV_FOREACH(i, ntas) {
r = set_put_strdup(ns, *i);
if (r < 0)
return r;
}
set_free_free(l->dnssec_negative_trust_anchors);
l->dnssec_negative_trust_anchors = ns;
ns = NULL;
return 0;
clear:
l->dnssec_negative_trust_anchors = set_free_free(l->dnssec_negative_trust_anchors);
return r;
}
static int link_update_search_domains(Link *l) {
_cleanup_strv_free_ char **domains = NULL;
char **i;
int r;
assert(l);
r = sd_network_link_get_domains(l->ifindex, &domains);
if (r == -ENODATA) {
/* networkd knows nothing about this interface, and that's fine. */
r = 0;
goto clear;
}
if (r < 0)
goto clear;
dns_search_domain_mark_all(l->search_domains);
STRV_FOREACH(i, domains) {
DnsSearchDomain *d;
r = dns_search_domain_find(l->search_domains, *i, &d);
if (r < 0)
goto clear;
if (r > 0)
dns_search_domain_move_back_and_unmark(d);
else {
r = dns_search_domain_new(l->manager, NULL, DNS_SEARCH_DOMAIN_LINK, l, *i);
if (r < 0)
goto clear;
}
}
dns_search_domain_unlink_marked(l->search_domains);
return 0;
clear:
dns_search_domain_unlink_all(l->search_domains);
return r;
}
int link_update_monitor(Link *l) {
int r;
assert(l);
r = link_update_dns_servers(l);
if (r < 0)
log_warning_errno(r, "Failed to read DNS servers for interface %s, ignoring: %m", l->name);
r = link_update_llmnr_support(l);
if (r < 0)
log_warning_errno(r, "Failed to read LLMNR support for interface %s, ignoring: %m", l->name);
r = link_update_mdns_support(l);
if (r < 0)
log_warning_errno(r, "Failed to read mDNS support for interface %s, ignoring: %m", l->name);
r = link_update_dnssec_mode(l);
if (r < 0)
log_warning_errno(r, "Failed to read DNSSEC mode for interface %s, ignoring: %m", l->name);
r = link_update_dnssec_negative_trust_anchors(l);
if (r < 0)
log_warning_errno(r, "Failed to read DNSSEC negative trust anchors for interface %s, ignoring: %m", l->name);
r = link_update_search_domains(l);
if (r < 0)
log_warning_errno(r, "Failed to read search domains for interface %s, ignoring: %m", l->name);
link_allocate_scopes(l);
link_add_rrs(l, false);
return 0;
}
bool link_relevant(Link *l, int family, bool multicast) {
_cleanup_free_ char *state = NULL;
LinkAddress *a;
assert(l);
/* A link is relevant for multicast traffic if it isn't a loopback or pointopoint device, has a link beat, can
* do multicast and has at least one relevant IP address */
if (l->flags & (IFF_LOOPBACK|IFF_DORMANT))
return false;
if ((l->flags & (IFF_UP|IFF_LOWER_UP)) != (IFF_UP|IFF_LOWER_UP))
return false;
if (multicast) {
if (l->flags & IFF_POINTOPOINT)
return false;
if ((l->flags & IFF_MULTICAST) != IFF_MULTICAST)
return false;
}
sd_network_link_get_operational_state(l->ifindex, &state);
if (state && !STR_IN_SET(state, "unknown", "degraded", "routable"))
return false;
LIST_FOREACH(addresses, a, l->addresses)
if ((family == AF_UNSPEC || a->family == family) && link_address_relevant(a))
return true;
return false;
}
LinkAddress *link_find_address(Link *l, int family, const union in_addr_union *in_addr) {
LinkAddress *a;
assert(l);
LIST_FOREACH(addresses, a, l->addresses)
if (a->family == family && in_addr_equal(family, &a->in_addr, in_addr))
return a;
return NULL;
}
DnsServer* link_set_dns_server(Link *l, DnsServer *s) {
assert(l);
if (l->current_dns_server == s)
return s;
if (s)
log_info("Switching to DNS server %s for interface %s.", dns_server_string(s), l->name);
dns_server_unref(l->current_dns_server);
l->current_dns_server = dns_server_ref(s);
if (l->unicast_scope)
dns_cache_flush(&l->unicast_scope->cache);
return s;
}
DnsServer *link_get_dns_server(Link *l) {
assert(l);
if (!l->current_dns_server)
link_set_dns_server(l, l->dns_servers);
return l->current_dns_server;
}
void link_next_dns_server(Link *l) {
assert(l);
if (!l->current_dns_server)
return;
/* Change to the next one, but make sure to follow the linked
* list only if this server is actually still linked. */
if (l->current_dns_server->linked && l->current_dns_server->servers_next) {
link_set_dns_server(l, l->current_dns_server->servers_next);
return;
}
link_set_dns_server(l, l->dns_servers);
}
int link_address_new(Link *l, LinkAddress **ret, int family, const union in_addr_union *in_addr) {
LinkAddress *a;
assert(l);
assert(in_addr);
a = new0(LinkAddress, 1);
if (!a)
return -ENOMEM;
a->family = family;
a->in_addr = *in_addr;
a->link = l;
LIST_PREPEND(addresses, l->addresses, a);
if (ret)
*ret = a;
return 0;
}
LinkAddress *link_address_free(LinkAddress *a) {
if (!a)
return NULL;
if (a->link) {
LIST_REMOVE(addresses, a->link->addresses, a);
if (a->llmnr_address_rr) {
if (a->family == AF_INET && a->link->llmnr_ipv4_scope)
dns_zone_remove_rr(&a->link->llmnr_ipv4_scope->zone, a->llmnr_address_rr);
else if (a->family == AF_INET6 && a->link->llmnr_ipv6_scope)
dns_zone_remove_rr(&a->link->llmnr_ipv6_scope->zone, a->llmnr_address_rr);
}
if (a->llmnr_ptr_rr) {
if (a->family == AF_INET && a->link->llmnr_ipv4_scope)
dns_zone_remove_rr(&a->link->llmnr_ipv4_scope->zone, a->llmnr_ptr_rr);
else if (a->family == AF_INET6 && a->link->llmnr_ipv6_scope)
dns_zone_remove_rr(&a->link->llmnr_ipv6_scope->zone, a->llmnr_ptr_rr);
}
}
dns_resource_record_unref(a->llmnr_address_rr);
dns_resource_record_unref(a->llmnr_ptr_rr);
free(a);
return NULL;
}
void link_address_add_rrs(LinkAddress *a, bool force_remove) {
int r;
assert(a);
if (a->family == AF_INET) {
if (!force_remove &&
link_address_relevant(a) &&
a->link->llmnr_ipv4_scope &&
a->link->llmnr_support == RESOLVE_SUPPORT_YES &&
a->link->manager->llmnr_support == RESOLVE_SUPPORT_YES) {
if (!a->link->manager->llmnr_host_ipv4_key) {
a->link->manager->llmnr_host_ipv4_key = dns_resource_key_new(DNS_CLASS_IN, DNS_TYPE_A, a->link->manager->llmnr_hostname);
if (!a->link->manager->llmnr_host_ipv4_key) {
r = -ENOMEM;
goto fail;
}
}
if (!a->llmnr_address_rr) {
a->llmnr_address_rr = dns_resource_record_new(a->link->manager->llmnr_host_ipv4_key);
if (!a->llmnr_address_rr) {
r = -ENOMEM;
goto fail;
}
a->llmnr_address_rr->a.in_addr = a->in_addr.in;
a->llmnr_address_rr->ttl = LLMNR_DEFAULT_TTL;
}
if (!a->llmnr_ptr_rr) {
r = dns_resource_record_new_reverse(&a->llmnr_ptr_rr, a->family, &a->in_addr, a->link->manager->llmnr_hostname);
if (r < 0)
goto fail;
a->llmnr_ptr_rr->ttl = LLMNR_DEFAULT_TTL;
}
r = dns_zone_put(&a->link->llmnr_ipv4_scope->zone, a->link->llmnr_ipv4_scope, a->llmnr_address_rr, true);
if (r < 0)
log_warning_errno(r, "Failed to add A record to LLMNR zone: %m");
r = dns_zone_put(&a->link->llmnr_ipv4_scope->zone, a->link->llmnr_ipv4_scope, a->llmnr_ptr_rr, false);
if (r < 0)
log_warning_errno(r, "Failed to add IPv6 PTR record to LLMNR zone: %m");
} else {
if (a->llmnr_address_rr) {
if (a->link->llmnr_ipv4_scope)
dns_zone_remove_rr(&a->link->llmnr_ipv4_scope->zone, a->llmnr_address_rr);
a->llmnr_address_rr = dns_resource_record_unref(a->llmnr_address_rr);
}
if (a->llmnr_ptr_rr) {
if (a->link->llmnr_ipv4_scope)
dns_zone_remove_rr(&a->link->llmnr_ipv4_scope->zone, a->llmnr_ptr_rr);
a->llmnr_ptr_rr = dns_resource_record_unref(a->llmnr_ptr_rr);
}
}
}
if (a->family == AF_INET6) {
if (!force_remove &&
link_address_relevant(a) &&
a->link->llmnr_ipv6_scope &&
a->link->llmnr_support == RESOLVE_SUPPORT_YES &&
a->link->manager->llmnr_support == RESOLVE_SUPPORT_YES) {
if (!a->link->manager->llmnr_host_ipv6_key) {
a->link->manager->llmnr_host_ipv6_key = dns_resource_key_new(DNS_CLASS_IN, DNS_TYPE_AAAA, a->link->manager->llmnr_hostname);
if (!a->link->manager->llmnr_host_ipv6_key) {
r = -ENOMEM;
goto fail;
}
}
if (!a->llmnr_address_rr) {
a->llmnr_address_rr = dns_resource_record_new(a->link->manager->llmnr_host_ipv6_key);
if (!a->llmnr_address_rr) {
r = -ENOMEM;
goto fail;
}
a->llmnr_address_rr->aaaa.in6_addr = a->in_addr.in6;
a->llmnr_address_rr->ttl = LLMNR_DEFAULT_TTL;
}
if (!a->llmnr_ptr_rr) {
r = dns_resource_record_new_reverse(&a->llmnr_ptr_rr, a->family, &a->in_addr, a->link->manager->llmnr_hostname);
if (r < 0)
goto fail;
a->llmnr_ptr_rr->ttl = LLMNR_DEFAULT_TTL;
}
r = dns_zone_put(&a->link->llmnr_ipv6_scope->zone, a->link->llmnr_ipv6_scope, a->llmnr_address_rr, true);
if (r < 0)
log_warning_errno(r, "Failed to add AAAA record to LLMNR zone: %m");
r = dns_zone_put(&a->link->llmnr_ipv6_scope->zone, a->link->llmnr_ipv6_scope, a->llmnr_ptr_rr, false);
if (r < 0)
log_warning_errno(r, "Failed to add IPv6 PTR record to LLMNR zone: %m");
} else {
if (a->llmnr_address_rr) {
if (a->link->llmnr_ipv6_scope)
dns_zone_remove_rr(&a->link->llmnr_ipv6_scope->zone, a->llmnr_address_rr);
a->llmnr_address_rr = dns_resource_record_unref(a->llmnr_address_rr);
}
if (a->llmnr_ptr_rr) {
if (a->link->llmnr_ipv6_scope)
dns_zone_remove_rr(&a->link->llmnr_ipv6_scope->zone, a->llmnr_ptr_rr);
a->llmnr_ptr_rr = dns_resource_record_unref(a->llmnr_ptr_rr);
}
}
}
return;
fail:
log_debug_errno(r, "Failed to update address RRs: %m");
}
int link_address_update_rtnl(LinkAddress *a, sd_netlink_message *m) {
int r;
assert(a);
assert(m);
r = sd_rtnl_message_addr_get_flags(m, &a->flags);
if (r < 0)
return r;
sd_rtnl_message_addr_get_scope(m, &a->scope);
link_allocate_scopes(a->link);
link_add_rrs(a->link, false);
return 0;
}
bool link_address_relevant(LinkAddress *a) {
assert(a);
if (a->flags & (IFA_F_DEPRECATED|IFA_F_TENTATIVE))
return false;
if (IN_SET(a->scope, RT_SCOPE_HOST, RT_SCOPE_NOWHERE))
return false;
return true;
}
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