src/libsystemd/sd-id128/sd-id128.c

   1 /***
   2   This file is part of systemd.
   3
   4   Copyright 2011 Lennart Poettering
   5
   6   systemd is free software; you can redistribute it and/or modify it
   7   under the terms of the GNU Lesser General Public License as published by
   8   the Free Software Foundation; either version 2.1 of the License, or
   9   (at your option) any later version.
  10
  11   systemd is distributed in the hope that it will be useful, but
  12   WITHOUT ANY WARRANTY; without even the implied warranty of
  13   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  14   Lesser General Public License for more details.
  15
  16   You should have received a copy of the GNU Lesser General Public License
  17   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  18 ***/
  19
  20 #include <errno.h>
  21 #include <fcntl.h>
  22 #include <unistd.h>
  23
  24 #include "sd-id128.h"
  25
  26 #include "fd-util.h"
  27 #include "hexdecoct.h"
  28 #include "id128-util.h"
  29 #include "io-util.h"
  30 #include "khash.h"
  31 #include "macro.h"
  32 #include "random-util.h"
  33 #include "util.h"
  34
  35 _public_ char *sd_id128_to_string(sd_id128_t id, char s[SD_ID128_STRING_MAX]) {
  36         unsigned n;
  37
  38         assert_return(s, NULL);
  39
  40         for (n = 0; n < 16; n++) {
  41                 s[n*2] = hexchar(id.bytes[n] >> 4);
  42                 s[n*2+1] = hexchar(id.bytes[n] & 0xF);
  43         }
  44
  45         s[32] = 0;
  46
  47         return s;
  48 }
  49
  50 _public_ int sd_id128_from_string(const char s[], sd_id128_t *ret) {
  51         unsigned n, i;
  52         sd_id128_t t;
  53         bool is_guid = false;
  54
  55         assert_return(s, -EINVAL);
  56
  57         for (n = 0, i = 0; n < 16;) {
  58                 int a, b;
  59
  60                 if (s[i] == '-') {
  61                         /* Is this a GUID? Then be nice, and skip over
  62                          * the dashes */
  63
  64                         if (i == 8)
  65                                 is_guid = true;
  66                         else if (i == 13 || i == 18 || i == 23) {
  67                                 if (!is_guid)
  68                                         return -EINVAL;
  69                         } else
  70                                 return -EINVAL;
  71
  72                         i++;
  73                         continue;
  74                 }
  75
  76                 a = unhexchar(s[i++]);
  77                 if (a < 0)
  78                         return -EINVAL;
  79
  80                 b = unhexchar(s[i++]);
  81                 if (b < 0)
  82                         return -EINVAL;
  83
  84                 t.bytes[n++] = (a << 4) | b;
  85         }
  86
  87         if (i != (is_guid ? 36 : 32))
  88                 return -EINVAL;
  89
  90         if (s[i] != 0)
  91                 return -EINVAL;
  92
  93         if (ret)
  94                 *ret = t;
  95         return 0;
  96 }
  97
  98 _public_ int sd_id128_get_machine(sd_id128_t *ret) {
  99         static thread_local sd_id128_t saved_machine_id = {};
 100         int r;
 101
 102         assert_return(ret, -EINVAL);
 103
 104         if (sd_id128_is_null(saved_machine_id)) {
 105                 r = id128_read("/etc/machine-id", ID128_PLAIN, &saved_machine_id);
 106                 if (r < 0)
 107                         return r;
 108
 109                 if (sd_id128_is_null(saved_machine_id))
 110                         return -EINVAL;
 111         }
 112
 113         *ret = saved_machine_id;
 114         return 0;
 115 }
 116
 117 _public_ int sd_id128_get_boot(sd_id128_t *ret) {
 118         static thread_local sd_id128_t saved_boot_id = {};
 119         int r;
 120
 121         assert_return(ret, -EINVAL);
 122
 123         if (sd_id128_is_null(saved_boot_id)) {
 124                 r = id128_read("/proc/sys/kernel/random/boot_id", ID128_UUID, &saved_boot_id);
 125                 if (r < 0)
 126                         return r;
 127         }
 128
 129         *ret = saved_boot_id;
 130         return 0;
 131 }
 132
 133 _public_ int sd_id128_get_invocation(sd_id128_t *ret) {
 134         static thread_local sd_id128_t saved_invocation_id = {};
 135         int r;
 136
 137         assert_return(ret, -EINVAL);
 138
 139         if (sd_id128_is_null(saved_invocation_id)) {
 140                 const char *e;
 141
 142                 e = secure_getenv("INVOCATION_ID");
 143                 if (!e)
 144                         return -ENXIO;
 145
 146                 r = sd_id128_from_string(e, &saved_invocation_id);
 147                 if (r < 0)
 148                         return r;
 149         }
 150
 151         *ret = saved_invocation_id;
 152         return 0;
 153 }
 154
 155 static sd_id128_t make_v4_uuid(sd_id128_t id) {
 156         /* Stolen from generate_random_uuid() of drivers/char/random.c
 157          * in the kernel sources */
 158
 159         /* Set UUID version to 4 --- truly random generation */
 160         id.bytes[6] = (id.bytes[6] & 0x0F) | 0x40;
 161
 162         /* Set the UUID variant to DCE */
 163         id.bytes[8] = (id.bytes[8] & 0x3F) | 0x80;
 164
 165         return id;
 166 }
 167
 168 _public_ int sd_id128_randomize(sd_id128_t *ret) {
 169         sd_id128_t t;
 170         int r;
 171
 172         assert_return(ret, -EINVAL);
 173
 174         r = dev_urandom(&t, sizeof(t));
 175         if (r < 0)
 176                 return r;
 177
 178         /* Turn this into a valid v4 UUID, to be nice. Note that we
 179          * only guarantee this for newly generated UUIDs, not for
 180          * pre-existing ones. */
 181
 182         *ret = make_v4_uuid(t);
 183         return 0;
 184 }
 185
 186 _public_ int sd_id128_get_machine_app_specific(sd_id128_t app_id, sd_id128_t *ret) {
 187         _cleanup_(khash_unrefp) khash *h = NULL;
 188         sd_id128_t m, result;
 189         const void *p;
 190         int r;
 191
 192         assert_return(ret, -EINVAL);
 193
 194         r = sd_id128_get_machine(&m);
 195         if (r < 0)
 196                 return r;
 197
 198         r = khash_new_with_key(&h, "hmac(sha256)", &m, sizeof(m));
 199         if (r < 0)
 200                 return r;
 201
 202         r = khash_put(h, &app_id, sizeof(app_id));
 203         if (r < 0)
 204                 return r;
 205
 206         r = khash_digest_data(h, &p);
 207         if (r < 0)
 208                 return r;
 209
 210         /* We chop off the trailing 16 bytes */
 211         memcpy(&result, p, MIN(khash_get_size(h), sizeof(result)));
 212
 213         *ret = make_v4_uuid(result);
 214         return 0;
 215 }