src/network/networkd-sysctl.c

   1 /* SPDX-License-Identifier: LGPL-2.1-or-later */
   2
   3 #include <netinet/in.h>
   4 #include <linux/if.h>
   5 #include <linux/if_arp.h>
   6
   7 #include "missing_network.h"
   8 #include "networkd-link.h"
   9 #include "networkd-manager.h"
  10 #include "networkd-network.h"
  11 #include "networkd-sysctl.h"
  12 #include "socket-util.h"
  13 #include "string-table.h"
  14 #include "sysctl-util.h"
  15
  16 static bool link_is_configured_for_family(Link *link, int family) {
  17         assert(link);
  18
  19         if (!link->network)
  20                 return false;
  21
  22         if (link->flags & IFF_LOOPBACK)
  23                 return false;
  24
  25         /* CAN devices do not support IP layer. Most of the functions below are never called for CAN devices,
  26          * but link_set_ipv6_mtu() may be called after setting interface MTU, and warn about the failure. For
  27          * safety, let's unconditionally check if the interface is not a CAN device. */
  28         if (IN_SET(family, AF_INET, AF_INET6) && link->iftype == ARPHRD_CAN)
  29                 return false;
  30
  31         if (family == AF_INET6 && !socket_ipv6_is_supported())
  32                 return false;
  33
  34         return true;
  35 }
  36
  37 static int link_update_ipv6_sysctl(Link *link) {
  38         assert(link);
  39
  40         if (!link_is_configured_for_family(link, AF_INET6))
  41                 return 0;
  42
  43         if (!link_ipv6_enabled(link))
  44                 return 0;
  45
  46         return sysctl_write_ip_property_boolean(AF_INET6, link->ifname, "disable_ipv6", false);
  47 }
  48
  49 static int link_set_proxy_arp(Link *link) {
  50         assert(link);
  51
  52         if (!link_is_configured_for_family(link, AF_INET))
  53                 return 0;
  54
  55         if (link->network->proxy_arp < 0)
  56                 return 0;
  57
  58         return sysctl_write_ip_property_boolean(AF_INET, link->ifname, "proxy_arp", link->network->proxy_arp > 0);
  59 }
  60
  61 static bool link_ip_forward_enabled(Link *link, int family) {
  62         assert(link);
  63         assert(IN_SET(family, AF_INET, AF_INET6));
  64
  65         if (!link_is_configured_for_family(link, family))
  66                 return false;
  67
  68         return link->network->ip_forward & (family == AF_INET ? ADDRESS_FAMILY_IPV4 : ADDRESS_FAMILY_IPV6);
  69 }
  70
  71 static int link_set_ipv4_forward(Link *link) {
  72         assert(link);
  73
  74         if (!link_ip_forward_enabled(link, AF_INET))
  75                 return 0;
  76
  77         /* We propagate the forwarding flag from one interface to the
  78          * global setting one way. This means: as long as at least one
  79          * interface was configured at any time that had IP forwarding
  80          * enabled the setting will stay on for good. We do this
  81          * primarily to keep IPv4 and IPv6 packet forwarding behaviour
  82          * somewhat in sync (see below). */
  83
  84         return sysctl_write_ip_property(AF_INET, NULL, "ip_forward", "1");
  85 }
  86
  87 static int link_set_ipv6_forward(Link *link) {
  88         assert(link);
  89
  90         if (!link_ip_forward_enabled(link, AF_INET6))
  91                 return 0;
  92
  93         /* On Linux, the IPv6 stack does not know a per-interface
  94          * packet forwarding setting: either packet forwarding is on
  95          * for all, or off for all. We hence don't bother with a
  96          * per-interface setting, but simply propagate the interface
  97          * flag, if it is set, to the global flag, one-way. Note that
  98          * while IPv4 would allow a per-interface flag, we expose the
  99          * same behaviour there and also propagate the setting from
 100          * one to all, to keep things simple (see above). */
 101
 102         return sysctl_write_ip_property(AF_INET6, "all", "forwarding", "1");
 103 }
 104
 105 static int link_set_ipv4_rp_filter(Link *link) {
 106         assert(link);
 107
 108         if (!link_is_configured_for_family(link, AF_INET))
 109                 return 0;
 110
 111         if (link->network->ipv4_rp_filter < 0)
 112                 return 0;
 113
 114         return sysctl_write_ip_property_int(AF_INET, link->ifname, "rp_filter", link->network->ipv4_rp_filter);
 115 }
 116
 117 static int link_set_ipv6_privacy_extensions(Link *link) {
 118         IPv6PrivacyExtensions val;
 119
 120         assert(link);
 121         assert(link->manager);
 122
 123         if (!link_is_configured_for_family(link, AF_INET6))
 124                 return 0;
 125
 126         val = link->network->ipv6_privacy_extensions;
 127         if (val < 0) /* If not specified, then use the global setting. */
 128                 val = link->manager->ipv6_privacy_extensions;
 129
 130         /* When "kernel", do not update the setting. */
 131         if (val == IPV6_PRIVACY_EXTENSIONS_KERNEL)
 132                 return 0;
 133
 134         return sysctl_write_ip_property_int(AF_INET6, link->ifname, "use_tempaddr", (int) val);
 135 }
 136
 137 static int link_set_ipv6_accept_ra(Link *link) {
 138         assert(link);
 139
 140         if (!link_is_configured_for_family(link, AF_INET6))
 141                 return 0;
 142
 143         return sysctl_write_ip_property(AF_INET6, link->ifname, "accept_ra", "0");
 144 }
 145
 146 static int link_set_ipv6_dad_transmits(Link *link) {
 147         assert(link);
 148
 149         if (!link_is_configured_for_family(link, AF_INET6))
 150                 return 0;
 151
 152         if (link->network->ipv6_dad_transmits < 0)
 153                 return 0;
 154
 155         return sysctl_write_ip_property_int(AF_INET6, link->ifname, "dad_transmits", link->network->ipv6_dad_transmits);
 156 }
 157
 158 static int link_set_ipv6_hop_limit(Link *link) {
 159         assert(link);
 160
 161         if (!link_is_configured_for_family(link, AF_INET6))
 162                 return 0;
 163
 164         if (link->network->ipv6_hop_limit <= 0)
 165                 return 0;
 166
 167         return sysctl_write_ip_property_int(AF_INET6, link->ifname, "hop_limit", link->network->ipv6_hop_limit);
 168 }
 169
 170 static int link_set_ipv6_proxy_ndp(Link *link) {
 171         bool v;
 172
 173         assert(link);
 174
 175         if (!link_is_configured_for_family(link, AF_INET6))
 176                 return 0;
 177
 178         if (link->network->ipv6_proxy_ndp >= 0)
 179                 v = link->network->ipv6_proxy_ndp;
 180         else
 181                 v = !set_isempty(link->network->ipv6_proxy_ndp_addresses);
 182
 183         return sysctl_write_ip_property_boolean(AF_INET6, link->ifname, "proxy_ndp", v);
 184 }
 185
 186 int link_set_ipv6_mtu(Link *link) {
 187         uint32_t mtu;
 188
 189         assert(link);
 190
 191         if (!link_is_configured_for_family(link, AF_INET6))
 192                 return 0;
 193
 194         if (link->network->ipv6_mtu == 0)
 195                 return 0;
 196
 197         mtu = link->network->ipv6_mtu;
 198         if (mtu > link->max_mtu) {
 199                 log_link_warning(link, "Reducing requested IPv6 MTU %"PRIu32" to the interface's maximum MTU %"PRIu32".",
 200                                  mtu, link->max_mtu);
 201                 mtu = link->max_mtu;
 202         }
 203
 204         return sysctl_write_ip_property_uint32(AF_INET6, link->ifname, "mtu", mtu);
 205 }
 206
 207 static int link_set_ipv4_accept_local(Link *link) {
 208         assert(link);
 209
 210         if (!link_is_configured_for_family(link, AF_INET))
 211                 return 0;
 212
 213         if (link->network->ipv4_accept_local < 0)
 214                 return 0;
 215
 216         return sysctl_write_ip_property_boolean(AF_INET, link->ifname, "accept_local", link->network->ipv4_accept_local > 0);
 217 }
 218
 219 static int link_set_ipv4_route_localnet(Link *link) {
 220         assert(link);
 221
 222         if (!link_is_configured_for_family(link, AF_INET))
 223                 return 0;
 224
 225         if (link->network->ipv4_route_localnet < 0)
 226                 return 0;
 227
 228         return sysctl_write_ip_property_boolean(AF_INET, link->ifname, "route_localnet", link->network->ipv4_route_localnet > 0);
 229 }
 230
 231 static int link_set_ipv4_promote_secondaries(Link *link) {
 232         assert(link);
 233
 234         if (!link_is_configured_for_family(link, AF_INET))
 235                 return 0;
 236
 237         /* If promote_secondaries is not set, DHCP will work only as long as the IP address does not
 238          * changes between leases. The kernel will remove all secondary IP addresses of an interface
 239          * otherwise. The way systemd-networkd works is that the new IP of a lease is added as a
 240          * secondary IP and when the primary one expires it relies on the kernel to promote the
 241          * secondary IP. See also https://github.com/systemd/systemd/issues/7163 */
 242         return sysctl_write_ip_property_boolean(AF_INET, link->ifname, "promote_secondaries", true);
 243 }
 244
 245 int link_set_sysctl(Link *link) {
 246         int r;
 247
 248         assert(link);
 249
 250         /* If IPv6 configured that is static IPv6 address and IPv6LL autoconfiguration is enabled
 251          * for this interface, then enable IPv6 */
 252         r = link_update_ipv6_sysctl(link);
 253         if (r < 0)
 254                 log_link_warning_errno(link, r, "Cannot enable IPv6, ignoring: %m");
 255
 256         r = link_set_proxy_arp(link);
 257         if (r < 0)
 258                log_link_warning_errno(link, r, "Cannot configure proxy ARP for interface, ignoring: %m");
 259
 260         r = link_set_ipv4_forward(link);
 261         if (r < 0)
 262                 log_link_warning_errno(link, r, "Cannot turn on IPv4 packet forwarding, ignoring: %m");
 263
 264         r = link_set_ipv6_forward(link);
 265         if (r < 0)
 266                 log_link_warning_errno(link, r, "Cannot configure IPv6 packet forwarding, ignoring: %m");
 267
 268         r = link_set_ipv6_privacy_extensions(link);
 269         if (r < 0)
 270                 log_link_warning_errno(link, r, "Cannot configure IPv6 privacy extensions for interface, ignoring: %m");
 271
 272         r = link_set_ipv6_accept_ra(link);
 273         if (r < 0)
 274                 log_link_warning_errno(link, r, "Cannot disable kernel IPv6 accept_ra for interface, ignoring: %m");
 275
 276         r = link_set_ipv6_dad_transmits(link);
 277         if (r < 0)
 278                 log_link_warning_errno(link, r, "Cannot set IPv6 dad transmits for interface, ignoring: %m");
 279
 280         r = link_set_ipv6_hop_limit(link);
 281         if (r < 0)
 282                 log_link_warning_errno(link, r, "Cannot set IPv6 hop limit for interface, ignoring: %m");
 283
 284         r = link_set_ipv6_proxy_ndp(link);
 285         if (r < 0)
 286                 log_link_warning_errno(link, r, "Cannot set IPv6 proxy NDP, ignoring: %m");
 287
 288         r = link_set_ipv6_mtu(link);
 289         if (r < 0)
 290                 log_link_warning_errno(link, r, "Cannot set IPv6 MTU, ignoring: %m");
 291
 292         r = link_set_ipv6ll_stable_secret(link);
 293         if (r < 0)
 294                 log_link_warning_errno(link, r, "Cannot set stable secret address for IPv6 link-local address: %m");
 295
 296         r = link_set_ipv4_accept_local(link);
 297         if (r < 0)
 298                 log_link_warning_errno(link, r, "Cannot set IPv4 accept_local flag for interface, ignoring: %m");
 299
 300         r = link_set_ipv4_route_localnet(link);
 301         if (r < 0)
 302                 log_link_warning_errno(link, r, "Cannot set IPv4 route_localnet flag for interface, ignoring: %m");
 303
 304         r = link_set_ipv4_rp_filter(link);
 305         if (r < 0)
 306                 log_link_warning_errno(link, r, "Cannot set IPv4 reverse path filtering for interface, ignoring: %m");
 307
 308         r = link_set_ipv4_promote_secondaries(link);
 309         if (r < 0)
 310                 log_link_warning_errno(link, r, "Cannot enable promote_secondaries for interface, ignoring: %m");
 311
 312         return 0;
 313 }
 314
 315 static const char* const ipv6_privacy_extensions_table[_IPV6_PRIVACY_EXTENSIONS_MAX] = {
 316         [IPV6_PRIVACY_EXTENSIONS_NO]            = "no",
 317         [IPV6_PRIVACY_EXTENSIONS_PREFER_PUBLIC] = "prefer-public",
 318         [IPV6_PRIVACY_EXTENSIONS_YES]           = "yes",
 319         [IPV6_PRIVACY_EXTENSIONS_KERNEL]        = "kernel",
 320 };
 321
 322 DEFINE_STRING_TABLE_LOOKUP_WITH_BOOLEAN(ipv6_privacy_extensions, IPv6PrivacyExtensions,
 323                                         IPV6_PRIVACY_EXTENSIONS_YES);
 324 DEFINE_CONFIG_PARSE_ENUM(config_parse_ipv6_privacy_extensions, ipv6_privacy_extensions, IPv6PrivacyExtensions,
 325                          "Failed to parse IPv6 privacy extensions option");
 326
 327 static const char* const ip_reverse_path_filter_table[_IP_REVERSE_PATH_FILTER_MAX] = {
 328         [IP_REVERSE_PATH_FILTER_NO]     = "no",
 329         [IP_REVERSE_PATH_FILTER_STRICT] = "strict",
 330         [IP_REVERSE_PATH_FILTER_LOOSE]  = "loose",
 331 };
 332
 333 DEFINE_STRING_TABLE_LOOKUP(ip_reverse_path_filter, IPReversePathFilter);
 334 DEFINE_CONFIG_PARSE_ENUM(config_parse_ip_reverse_path_filter, ip_reverse_path_filter, IPReversePathFilter,
 335                          "Failed to parse IP reverse path filter option");