X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?a=blobdiff_plain;f=src%2Fmachine-id-setup.c;h=d584181bede517e0f0155d459255decd5a587d39;hb=fa734f4da837abe6c893e75c95be78527db72c0f;hp=519521fe6768f9de96fffb8bc44fc314a54991f7;hpb=4c12626c8e3491570b395d68380543e10c98ad33;p=elogind.git

diff --git a/src/machine-id-setup.c b/src/machine-id-setup.c
index 519521fe6..d584181be 100644
--- a/src/machine-id-setup.c
+++ b/src/machine-id-setup.c
@@ -27,27 +27,21 @@
 #include <fcntl.h>
 #include <sys/mount.h>
 
+#include <systemd/sd-id128.h>
+
 #include "machine-id-setup.h"
 #include "macro.h"
 #include "util.h"
 #include "log.h"
-
-static void make_v4_uuid(unsigned char *id) {
-        /* Stolen from generate_random_uuid() of drivers/char/random.c
-         * in the kernel sources */
-
-        /* Set UUID version to 4 --- truly random generation */
-        id[6] = (id[6] & 0x0F) | 0x40;
-
-        /* Set the UUID variant to DCE */
-        id[8] = (id[8] & 0x3F) | 0x80;
-}
+#include "virt.h"
 
 static int generate(char id[34]) {
-        int fd;
-        unsigned char buf[16], *p;
+        int fd, r;
+        unsigned char *p;
+        sd_id128_t buf;
         char *q;
         ssize_t k;
+        const char *vm_id;
 
         assert(id);
 
@@ -55,7 +49,7 @@ static int generate(char id[34]) {
         fd = open("/var/lib/dbus/machine-id", O_RDONLY|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW);
         if (fd >= 0) {
 
-                k = loop_read(fd, id, 33, false);
+                k = loop_read(fd, id, 32, false);
                 close_nointr_nofail(fd);
 
                 if (k >= 32) {
@@ -67,27 +61,51 @@ static int generate(char id[34]) {
                 }
         }
 
-        /* If that didn't work, generate a random machine id */
-        fd = open("/dev/urandom", O_RDONLY|O_CLOEXEC|O_NOCTTY);
-        if (fd < 0) {
-                log_error("Failed to open /dev/urandom: %m");
-                return -errno;
-        }
+        /* If that didn't work, see if we are running in qemu/kvm and a
+         * machine ID was passed in via -uuid on the qemu/kvm command
+         * line */
 
-        k = loop_read(fd, buf, sizeof(buf), false);
-        close_nointr_nofail(fd);
+        r = detect_vm(&vm_id);
+        if (r > 0 && streq(vm_id, "kvm")) {
+                char uuid[37];
+
+                fd = open("/sys/class/dmi/id/product_uuid", O_RDONLY|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW);
+                if (fd >= 0) {
+                        k = loop_read(fd, uuid, 36, false);
+                        close_nointr_nofail(fd);
 
-        if (k != sizeof(buf)) {
-                log_error("Failed to read /dev/urandom: %s", strerror(k < 0 ? -k : EIO));
-                return k < 0 ? (int) k : -EIO;
+                        if (k >= 36) {
+                                unsigned i, j;
+
+                                for (i = 0, j = 0; i < 36 && j < 32; i++) {
+                                        int t;
+
+                                        t = unhexchar(uuid[i]);
+                                        if (t < 0)
+                                                continue;
+
+                                        id[j++] = hexchar(t);
+                                }
+
+                                if (i == 36 && j == 32) {
+                                        id[32] = '\n';
+                                        id[33] = 0;
+
+                                        log_info("Initializing machine ID from KVM UUID");
+                                        return 0;
+                                }
+                        }
+                }
         }
 
-        /* Turn this into a valid v4 UUID, to be nice. Note that we
-         * only guarantee this for newly generated UUIDs, not for
-         * pre-existing ones.*/
-        make_v4_uuid(buf);
+        /* If that didn't work, generate a random machine id */
+        r = sd_id128_randomize(&buf);
+        if (r < 0) {
+                log_error("Failed to open /dev/urandom: %s", strerror(-r));
+                return r;
+        }
 
-        for (p = buf, q = id; p < buf + sizeof(buf); p++, q += 2) {
+        for (p = buf.bytes, q = id; p < buf.bytes + sizeof(buf); p++, q += 2) {
                 q[0] = hexchar(*p >> 4);
                 q[1] = hexchar(*p & 15);
         }