src/libsystemd-network/sd-ipv4ll.c

   1 /* SPDX-License-Identifier: LGPL-2.1-or-later */
   2 /***
   3   Copyright © 2014 Axis Communications AB. All rights reserved.
   4 ***/
   5
   6 #include <arpa/inet.h>
   7 #include <errno.h>
   8 #include <stdio.h>
   9 #include <stdlib.h>
  10
  11 #include "sd-id128.h"
  12 #include "sd-ipv4acd.h"
  13 #include "sd-ipv4ll.h"
  14
  15 #include "alloc-util.h"
  16 #include "ether-addr-util.h"
  17 #include "in-addr-util.h"
  18 #include "network-common.h"
  19 #include "random-util.h"
  20 #include "siphash24.h"
  21 #include "sparse-endian.h"
  22 #include "string-util.h"
  23
  24 #define IPV4LL_NETWORK UINT32_C(0xA9FE0000)
  25 #define IPV4LL_NETMASK UINT32_C(0xFFFF0000)
  26
  27 #define IPV4LL_DONT_DESTROY(ll) \
  28         _cleanup_(sd_ipv4ll_unrefp) _unused_ sd_ipv4ll *_dont_destroy_##ll = sd_ipv4ll_ref(ll)
  29
  30 struct sd_ipv4ll {
  31         unsigned n_ref;
  32
  33         sd_ipv4acd *acd;
  34
  35         be32_t address; /* the address pushed to ACD */
  36         struct ether_addr mac;
  37
  38         struct {
  39                 le64_t value;
  40                 le64_t generation;
  41         } seed;
  42         bool seed_set;
  43
  44         /* External */
  45         be32_t claimed_address;
  46
  47         sd_ipv4ll_callback_t callback;
  48         void *userdata;
  49
  50         sd_ipv4ll_check_mac_callback_t check_mac_callback;
  51         void *check_mac_userdata;
  52 };
  53
  54 #define log_ipv4ll_errno(ll, error, fmt, ...)           \
  55         log_interface_prefix_full_errno(                \
  56                 "IPv4LL: ",                             \
  57                 sd_ipv4ll, ll,                          \
  58                 error, fmt, ##__VA_ARGS__)
  59 #define log_ipv4ll(ll, fmt, ...)                        \
  60         log_interface_prefix_full_errno_zerook(         \
  61                 "IPv4LL: ",                             \
  62                 sd_ipv4ll, ll,                          \
  63                 0, fmt, ##__VA_ARGS__)
  64
  65 static void ipv4ll_on_acd(sd_ipv4acd *acd, int event, void *userdata);
  66 static int ipv4ll_check_mac(sd_ipv4acd *acd, const struct ether_addr *mac, void *userdata);
  67
  68 static sd_ipv4ll *ipv4ll_free(sd_ipv4ll *ll) {
  69         assert(ll);
  70
  71         sd_ipv4acd_unref(ll->acd);
  72         return mfree(ll);
  73 }
  74
  75 DEFINE_TRIVIAL_REF_UNREF_FUNC(sd_ipv4ll, sd_ipv4ll, ipv4ll_free);
  76
  77 int sd_ipv4ll_new(sd_ipv4ll **ret) {
  78         _cleanup_(sd_ipv4ll_unrefp) sd_ipv4ll *ll = NULL;
  79         int r;
  80
  81         assert_return(ret, -EINVAL);
  82
  83         ll = new0(sd_ipv4ll, 1);
  84         if (!ll)
  85                 return -ENOMEM;
  86
  87         ll->n_ref = 1;
  88
  89         r = sd_ipv4acd_new(&ll->acd);
  90         if (r < 0)
  91                 return r;
  92
  93         r = sd_ipv4acd_set_callback(ll->acd, ipv4ll_on_acd, ll);
  94         if (r < 0)
  95                 return r;
  96
  97         r = sd_ipv4acd_set_check_mac_callback(ll->acd, ipv4ll_check_mac, ll);
  98         if (r < 0)
  99                 return r;
 100
 101         *ret = TAKE_PTR(ll);
 102
 103         return 0;
 104 }
 105
 106 int sd_ipv4ll_stop(sd_ipv4ll *ll) {
 107         if (!ll)
 108                 return 0;
 109
 110         return sd_ipv4acd_stop(ll->acd);
 111 }
 112
 113 int sd_ipv4ll_set_ifindex(sd_ipv4ll *ll, int ifindex) {
 114         assert_return(ll, -EINVAL);
 115         assert_return(ifindex > 0, -EINVAL);
 116         assert_return(sd_ipv4ll_is_running(ll) == 0, -EBUSY);
 117
 118         return sd_ipv4acd_set_ifindex(ll->acd, ifindex);
 119 }
 120
 121 int sd_ipv4ll_get_ifindex(sd_ipv4ll *ll) {
 122         if (!ll)
 123                 return -EINVAL;
 124
 125         return sd_ipv4acd_get_ifindex(ll->acd);
 126 }
 127
 128 int sd_ipv4ll_set_ifname(sd_ipv4ll *ll, const char *ifname) {
 129         assert_return(ll, -EINVAL);
 130         assert_return(ifname, -EINVAL);
 131
 132         return sd_ipv4acd_set_ifname(ll->acd, ifname);
 133 }
 134
 135 int sd_ipv4ll_get_ifname(sd_ipv4ll *ll, const char **ret) {
 136         assert_return(ll, -EINVAL);
 137
 138         return sd_ipv4acd_get_ifname(ll->acd, ret);
 139 }
 140
 141 int sd_ipv4ll_set_mac(sd_ipv4ll *ll, const struct ether_addr *addr) {
 142         int r;
 143
 144         assert_return(ll, -EINVAL);
 145         assert_return(addr, -EINVAL);
 146         assert_return(!ether_addr_is_null(addr), -EINVAL);
 147
 148         r = sd_ipv4acd_set_mac(ll->acd, addr);
 149         if (r < 0)
 150                 return r;
 151
 152         ll->mac = *addr;
 153         return 0;
 154 }
 155
 156 int sd_ipv4ll_detach_event(sd_ipv4ll *ll) {
 157         assert_return(ll, -EINVAL);
 158
 159         return sd_ipv4acd_detach_event(ll->acd);
 160 }
 161
 162 int sd_ipv4ll_attach_event(sd_ipv4ll *ll, sd_event *event, int64_t priority) {
 163         assert_return(ll, -EINVAL);
 164
 165         return sd_ipv4acd_attach_event(ll->acd, event, priority);
 166 }
 167
 168 int sd_ipv4ll_set_callback(sd_ipv4ll *ll, sd_ipv4ll_callback_t cb, void *userdata) {
 169         assert_return(ll, -EINVAL);
 170
 171         ll->callback = cb;
 172         ll->userdata = userdata;
 173
 174         return 0;
 175 }
 176
 177 int sd_ipv4ll_set_check_mac_callback(sd_ipv4ll *ll, sd_ipv4ll_check_mac_callback_t cb, void *userdata) {
 178         assert_return(ll, -EINVAL);
 179
 180         ll->check_mac_callback = cb;
 181         ll->check_mac_userdata = userdata;
 182
 183         return 0;
 184 }
 185
 186 int sd_ipv4ll_get_address(sd_ipv4ll *ll, struct in_addr *address) {
 187         assert_return(ll, -EINVAL);
 188         assert_return(address, -EINVAL);
 189
 190         if (ll->claimed_address == 0)
 191                 return -ENOENT;
 192
 193         address->s_addr = ll->claimed_address;
 194
 195         return 0;
 196 }
 197
 198 int sd_ipv4ll_set_address_seed(sd_ipv4ll *ll, uint64_t seed) {
 199         assert_return(ll, -EINVAL);
 200         assert_return(sd_ipv4ll_is_running(ll) == 0, -EBUSY);
 201
 202         ll->seed.value = htole64(seed);
 203         ll->seed_set = true;
 204
 205         return 0;
 206 }
 207
 208 int sd_ipv4ll_is_running(sd_ipv4ll *ll) {
 209         assert_return(ll, false);
 210
 211         return sd_ipv4acd_is_running(ll->acd);
 212 }
 213
 214 int sd_ipv4ll_set_address(sd_ipv4ll *ll, const struct in_addr *address) {
 215         int r;
 216
 217         assert_return(ll, -EINVAL);
 218         assert_return(address, -EINVAL);
 219         assert_return(in4_addr_is_link_local_dynamic(address), -EINVAL);
 220
 221         r = sd_ipv4acd_set_address(ll->acd, address);
 222         if (r < 0)
 223                 return r;
 224
 225         ll->address = address->s_addr;
 226
 227         return 0;
 228 }
 229
 230 #define PICK_HASH_KEY SD_ID128_MAKE(15,ac,82,a6,d6,3f,49,78,98,77,5d,0c,69,02,94,0b)
 231
 232 static int ipv4ll_pick_address(sd_ipv4ll *ll) {
 233         be32_t addr;
 234
 235         assert(ll);
 236
 237         do {
 238                 uint64_t h;
 239
 240                 h = siphash24(&ll->seed, sizeof(ll->seed), PICK_HASH_KEY.bytes);
 241
 242                 /* Increase the generation counter by one */
 243                 ll->seed.generation = htole64(le64toh(ll->seed.generation) + 1);
 244
 245                 addr = htobe32((h & UINT32_C(0x0000FFFF)) | IPV4LL_NETWORK);
 246         } while (addr == ll->address ||
 247                  IN_SET(be32toh(addr) & 0x0000FF00U, 0x0000U, 0xFF00U));
 248
 249         log_ipv4ll(ll, "Picked new IP address %s.", IN4_ADDR_TO_STRING((const struct in_addr*) &addr));
 250
 251         return sd_ipv4ll_set_address(ll, &(struct in_addr) { addr });
 252 }
 253
 254 #define MAC_HASH_KEY SD_ID128_MAKE(df,04,22,98,3f,ad,14,52,f9,87,2e,d1,9c,70,e2,f2)
 255
 256 static int ipv4ll_start_internal(sd_ipv4ll *ll, bool reset_generation) {
 257         int r;
 258         bool picked_address = false;
 259
 260         assert_return(ll, -EINVAL);
 261         assert_return(!ether_addr_is_null(&ll->mac), -EINVAL);
 262
 263         /* If no random seed is set, generate some from the MAC address */
 264         if (!ll->seed_set)
 265                 ll->seed.value = htole64(siphash24(ll->mac.ether_addr_octet, ETH_ALEN, MAC_HASH_KEY.bytes));
 266
 267         if (reset_generation)
 268                 ll->seed.generation = 0;
 269
 270         if (ll->address == 0) {
 271                 r = ipv4ll_pick_address(ll);
 272                 if (r < 0)
 273                         return r;
 274
 275                 picked_address = true;
 276         }
 277
 278         r = sd_ipv4acd_start(ll->acd, reset_generation);
 279         if (r < 0) {
 280
 281                 /* We couldn't start? If so, let's forget the picked address again, the user might make a change and
 282                  * retry, and we want the new data to take effect when picking an address. */
 283                 if (picked_address)
 284                         ll->address = 0;
 285
 286                 return r;
 287         }
 288
 289         return 1;
 290 }
 291
 292 int sd_ipv4ll_start(sd_ipv4ll *ll) {
 293         assert_return(ll, -EINVAL);
 294
 295         if (sd_ipv4ll_is_running(ll))
 296                 return 0;
 297
 298         return ipv4ll_start_internal(ll, true);
 299 }
 300
 301 int sd_ipv4ll_restart(sd_ipv4ll *ll) {
 302         ll->address = 0;
 303
 304         return ipv4ll_start_internal(ll, false);
 305 }
 306
 307 static void ipv4ll_client_notify(sd_ipv4ll *ll, int event) {
 308         assert(ll);
 309
 310         if (ll->callback)
 311                 ll->callback(ll, event, ll->userdata);
 312 }
 313
 314 void ipv4ll_on_acd(sd_ipv4acd *acd, int event, void *userdata) {
 315         sd_ipv4ll *ll = ASSERT_PTR(userdata);
 316         IPV4LL_DONT_DESTROY(ll);
 317         int r;
 318
 319         assert(acd);
 320
 321         switch (event) {
 322
 323         case SD_IPV4ACD_EVENT_STOP:
 324                 ipv4ll_client_notify(ll, SD_IPV4LL_EVENT_STOP);
 325                 ll->claimed_address = 0;
 326                 break;
 327
 328         case SD_IPV4ACD_EVENT_BIND:
 329                 ll->claimed_address = ll->address;
 330                 ipv4ll_client_notify(ll, SD_IPV4LL_EVENT_BIND);
 331                 break;
 332
 333         case SD_IPV4ACD_EVENT_CONFLICT:
 334                 /* if an address was already bound we must call up to the
 335                    user to handle this, otherwise we just try again */
 336                 if (ll->claimed_address != 0) {
 337                         ipv4ll_client_notify(ll, SD_IPV4LL_EVENT_CONFLICT);
 338
 339                         ll->claimed_address = 0;
 340                 } else {
 341                         r = sd_ipv4ll_restart(ll);
 342                         if (r < 0)
 343                                 goto error;
 344                 }
 345
 346                 break;
 347
 348         default:
 349                 assert_not_reached();
 350         }
 351
 352         return;
 353
 354 error:
 355         ipv4ll_client_notify(ll, SD_IPV4LL_EVENT_STOP);
 356 }
 357
 358 static int ipv4ll_check_mac(sd_ipv4acd *acd, const struct ether_addr *mac, void *userdata) {
 359         sd_ipv4ll *ll = ASSERT_PTR(userdata);
 360
 361         if (ll->check_mac_callback)
 362                 return ll->check_mac_callback(ll, mac, ll->check_mac_userdata);
 363
 364         return 0;
 365 }