src/libsystemd-network/dhcp-identifier.c

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2 /***
   3   Copyright (C) 2015 Tom Gundersen <teg@jklmen>
   4 ***/
   5
   6 #include "libudev.h"
   7 #include "sd-id128.h"
   8
   9 #include "dhcp-identifier.h"
  10 #include "dhcp6-protocol.h"
  11 #include "network-internal.h"
  12 #include "siphash24.h"
  13 #include "sparse-endian.h"
  14 #include "udev-util.h"
  15 #include "virt.h"
  16
  17 #define SYSTEMD_PEN 43793
  18 #define HASH_KEY SD_ID128_MAKE(80,11,8c,c2,fe,4a,03,ee,3e,d6,0c,6f,36,39,14,09)
  19
  20 int dhcp_validate_duid_len(uint16_t duid_type, size_t duid_len) {
  21         struct duid d;
  22
  23         assert_cc(sizeof(d.raw) >= MAX_DUID_LEN);
  24         if (duid_len > MAX_DUID_LEN)
  25                 return -EINVAL;
  26
  27         switch (duid_type) {
  28         case DUID_TYPE_LLT:
  29                 if (duid_len <= sizeof(d.llt))
  30                         return -EINVAL;
  31                 break;
  32         case DUID_TYPE_EN:
  33                 if (duid_len != sizeof(d.en))
  34                         return -EINVAL;
  35                 break;
  36         case DUID_TYPE_LL:
  37                 if (duid_len <= sizeof(d.ll))
  38                         return -EINVAL;
  39                 break;
  40         case DUID_TYPE_UUID:
  41                 if (duid_len != sizeof(d.uuid))
  42                         return -EINVAL;
  43                 break;
  44         default:
  45                 /* accept unknown type in order to be forward compatible */
  46                 break;
  47         }
  48         return 0;
  49 }
  50
  51 int dhcp_identifier_set_duid_en(struct duid *duid, size_t *len) {
  52         sd_id128_t machine_id;
  53         uint64_t hash;
  54         int r;
  55
  56         assert(duid);
  57         assert(len);
  58
  59         r = sd_id128_get_machine(&machine_id);
  60         if (r < 0)
  61                 return r;
  62
  63         unaligned_write_be16(&duid->type, DUID_TYPE_EN);
  64         unaligned_write_be32(&duid->en.pen, SYSTEMD_PEN);
  65
  66         *len = sizeof(duid->type) + sizeof(duid->en);
  67
  68         /* a bit of snake-oil perhaps, but no need to expose the machine-id
  69            directly; duid->en.id might not be aligned, so we need to copy */
  70         hash = htole64(siphash24(&machine_id, sizeof(machine_id), HASH_KEY.bytes));
  71         memcpy(duid->en.id, &hash, sizeof(duid->en.id));
  72
  73         return 0;
  74 }
  75
  76 int dhcp_identifier_set_iaid(int ifindex, uint8_t *mac, size_t mac_len, void *_id) {
  77         /* name is a pointer to memory in the udev_device struct, so must
  78            have the same scope */
  79         _cleanup_(udev_device_unrefp) struct udev_device *device = NULL;
  80         const char *name = NULL;
  81         uint64_t id;
  82
  83         if (detect_container() <= 0) {
  84                 /* not in a container, udev will be around */
  85                 _cleanup_(udev_unrefp) struct udev *udev;
  86                 char ifindex_str[2 + DECIMAL_STR_MAX(int)];
  87
  88                 udev = udev_new();
  89                 if (!udev)
  90                         return -ENOMEM;
  91
  92                 sprintf(ifindex_str, "n%d", ifindex);
  93                 device = udev_device_new_from_device_id(udev, ifindex_str);
  94                 if (device) {
  95                         if (udev_device_get_is_initialized(device) <= 0)
  96                                 /* not yet ready */
  97                                 return -EBUSY;
  98
  99                         name = net_get_name(device);
 100                 }
 101         }
 102
 103         if (name)
 104                 id = siphash24(name, strlen(name), HASH_KEY.bytes);
 105         else
 106                 /* fall back to MAC address if no predictable name available */
 107                 id = siphash24(mac, mac_len, HASH_KEY.bytes);
 108
 109         id = htole64(id);
 110
 111         /* fold into 32 bits */
 112         unaligned_write_be32(_id, (id & 0xffffffff) ^ (id >> 32));
 113
 114         return 0;
 115 }