src/virt.c

   1 /*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
   2
   3 /***
   4   This file is part of systemd.
   5
   6   Copyright 2011 Lennart Poettering
   7
   8   systemd is free software; you can redistribute it and/or modify it
   9   under the terms of the GNU General Public License as published by
  10   the Free Software Foundation; either version 2 of the License, or
  11   (at your option) any later version.
  12
  13   systemd is distributed in the hope that it will be useful, but
  14   WITHOUT ANY WARRANTY; without even the implied warranty of
  15   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  16   General Public License for more details.
  17
  18   You should have received a copy of the GNU General Public License
  19   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  20 ***/
  21
  22 #include <string.h>
  23 #include <errno.h>
  24 #include <unistd.h>
  25
  26 #include "util.h"
  27 #include "virt.h"
  28
  29 /* Returns a short identifier for the various VM implementations */
  30 int detect_vm(const char **id) {
  31
  32 #if defined(__i386__) || defined(__x86_64__)
  33
  34         /* Both CPUID and DMI are x86 specific interfaces... */
  35
  36         static const char *const dmi_vendors[] = {
  37                 "/sys/class/dmi/id/sys_vendor",
  38                 "/sys/class/dmi/id/board_vendor",
  39                 "/sys/class/dmi/id/bios_vendor"
  40         };
  41
  42         static const char dmi_vendor_table[] =
  43                 "QEMU\0"                  "qemu\0"
  44                 /* http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1009458 */
  45                 "VMware\0"                "vmware\0"
  46                 "VMW\0"                   "vmware\0"
  47                 "Microsoft Corporation\0" "microsoft\0"
  48                 "innotek GmbH\0"          "oracle\0"
  49                 "Xen\0"                   "xen\0"
  50                 "Bochs\0"                 "bochs\0";
  51
  52         static const char cpuid_vendor_table[] =
  53                 "XenVMMXenVMM\0"          "xen\0"
  54                 "KVMKVMKVM\0"             "kvm\0"
  55                 /* http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1009458 */
  56                 "VMwareVMware\0"          "vmware\0"
  57                 /* http://msdn.microsoft.com/en-us/library/ff542428.aspx */
  58                 "Microsoft Hv\0"          "microsoft\0";
  59
  60         uint32_t eax, ecx;
  61         union {
  62                 uint32_t sig32[3];
  63                 char text[13];
  64         } sig;
  65         unsigned i;
  66         const char *j, *k;
  67         bool hypervisor;
  68
  69         /* http://lwn.net/Articles/301888/ */
  70         zero(sig);
  71
  72 #if defined (__i386__)
  73 #define REG_a "eax"
  74 #define REG_b "ebx"
  75 #elif defined (__amd64__)
  76 #define REG_a "rax"
  77 #define REG_b "rbx"
  78 #endif
  79
  80         /* First detect whether there is a hypervisor */
  81         eax = 1;
  82         __asm__ __volatile__ (
  83                 /* ebx/rbx is being used for PIC! */
  84                 "  push %%"REG_b"         \n\t"
  85                 "  cpuid                  \n\t"
  86                 "  pop %%"REG_b"          \n\t"
  87
  88                 : "=a" (eax), "=c" (ecx)
  89                 : "0" (eax)
  90         );
  91
  92         hypervisor = !!(ecx & 0x80000000U);
  93
  94         if (hypervisor) {
  95
  96                 /* There is a hypervisor, see what it is */
  97                 eax = 0x40000000U;
  98                 __asm__ __volatile__ (
  99                         /* ebx/rbx is being used for PIC! */
 100                         "  push %%"REG_b"         \n\t"
 101                         "  cpuid                  \n\t"
 102                         "  mov %%ebx, %1          \n\t"
 103                         "  pop %%"REG_b"          \n\t"
 104
 105                         : "=a" (eax), "=r" (sig.sig32[0]), "=c" (sig.sig32[1]), "=d" (sig.sig32[2])
 106                         : "0" (eax)
 107                 );
 108
 109                 NULSTR_FOREACH_PAIR(j, k, cpuid_vendor_table)
 110                         if (streq(sig.text, j)) {
 111
 112                                 if (id)
 113                                         *id = k;
 114
 115                                 return 1;
 116                         }
 117         }
 118
 119         for (i = 0; i < ELEMENTSOF(dmi_vendors); i++) {
 120                 char *s;
 121                 int r;
 122                 const char *found = NULL;
 123
 124                 if ((r = read_one_line_file(dmi_vendors[i], &s)) < 0) {
 125                         if (r != -ENOENT)
 126                                 return r;
 127
 128                         continue;
 129                 }
 130
 131                 NULSTR_FOREACH_PAIR(j, k, dmi_vendor_table)
 132                         if (startswith(s, j))
 133                                 found = k;
 134                 free(s);
 135
 136                 if (found) {
 137                         if (id)
 138                                 *id = found;
 139
 140                         return 1;
 141                 }
 142         }
 143
 144         if (hypervisor) {
 145                 if (id)
 146                         *id = "other";
 147
 148                 return 1;
 149         }
 150
 151 #endif
 152         return 0;
 153 }
 154
 155 int detect_container(const char **id) {
 156         FILE *f;
 157
 158         /* Unfortunately many of these operations require root access
 159          * in one way or another */
 160
 161         if (geteuid() != 0)
 162                 return -EPERM;
 163
 164         if (running_in_chroot() > 0) {
 165
 166                 if (id)
 167                         *id = "chroot";
 168
 169                 return 1;
 170         }
 171
 172         /* /proc/vz exists in container and outside of the container,
 173          * /proc/bc only outside of the container. */
 174         if (access("/proc/vz", F_OK) >= 0 &&
 175             access("/proc/bc", F_OK) < 0) {
 176
 177                 if (id)
 178                         *id = "openvz";
 179
 180                 return 1;
 181         }
 182
 183         f = fopen("/proc/1/environ", "re");
 184         if (f) {
 185                 bool done = false;
 186
 187                 do {
 188                         char line[LINE_MAX];
 189                         unsigned i;
 190
 191                         for (i = 0; i < sizeof(line)-1; i++) {
 192                                 int c;
 193
 194                                 c = getc(f);
 195                                 if (_unlikely_(c == EOF)) {
 196                                         done = true;
 197                                         break;
 198                                 } else if (c == 0)
 199                                         break;
 200
 201                                 line[i] = c;
 202                         }
 203                         line[i] = 0;
 204
 205                         if (streq(line, "container=lxc")) {
 206                                 fclose(f);
 207
 208                                 if (id)
 209                                         *id = "lxc";
 210                                 return 1;
 211
 212                         } else if (streq(line, "container=lxc-libvirt")) {
 213                                 fclose(f);
 214
 215                                 if (id)
 216                                         *id = "lxc-libvirt";
 217                                 return 1;
 218
 219                         } else if (streq(line, "container=systemd-nspawn")) {
 220                                 fclose(f);
 221
 222                                 if (id)
 223                                         *id = "systemd-nspawn";
 224                                 return 1;
 225
 226                         } else if (startswith(line, "container=")) {
 227                                 fclose(f);
 228
 229                                 if (id)
 230                                         *id = "other";
 231                                 return 1;
 232                         }
 233
 234                 } while (!done);
 235
 236                 fclose(f);
 237         }
 238
 239         return 0;
 240 }
 241
 242 /* Returns a short identifier for the various VM/container implementations */
 243 Virtualization detect_virtualization(const char **id) {
 244
 245         static __thread Virtualization cached_virt = _VIRTUALIZATION_INVALID;
 246         static __thread const char *cached_id = NULL;
 247
 248         const char *_id;
 249         int r;
 250         Virtualization v;
 251
 252         if (_likely_(cached_virt >= 0)) {
 253
 254                 if (id && cached_virt > 0)
 255                         *id = cached_id;
 256
 257                 return cached_virt;
 258         }
 259
 260         r = detect_container(&_id);
 261         if (r < 0) {
 262                 v = r;
 263                 goto finish;
 264         } else if (r > 0) {
 265                 v = VIRTUALIZATION_CONTAINER;
 266                 goto finish;
 267         }
 268
 269         r = detect_vm(&_id);
 270         if (r < 0) {
 271                 v = r;
 272                 goto finish;
 273         } else if (r > 0) {
 274                 v = VIRTUALIZATION_VM;
 275                 goto finish;
 276         }
 277
 278         v = VIRTUALIZATION_NONE;
 279
 280 finish:
 281         if (v > 0) {
 282                 cached_id = _id;
 283
 284                 if (id)
 285                         *id = _id;
 286         }
 287
 288         if (v >= 0)
 289                 cached_virt = v;
 290
 291         return v;
 292 }