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-rw-r--r--src/machine-id-setup.c38
1 files changed, 30 insertions, 8 deletions
diff --git a/src/machine-id-setup.c b/src/machine-id-setup.c
index 98e288e1b5..be51d0dec7 100644
--- a/src/machine-id-setup.c
+++ b/src/machine-id-setup.c
@@ -32,16 +32,28 @@
#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;
+}
+
static int generate(char id[34]) {
int fd;
- char buf[16];
- char *p, *q;
+ unsigned char buf[16], *p;
+ char *q;
ssize_t k;
assert(id);
/* First, try reading the D-Bus machine id, unless it is a symlink */
- if ((fd = open("/var/lib/dbus/machine-id", O_RDONLY|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW)) >= 0) {
+ 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);
close_nointr_nofail(fd);
@@ -56,7 +68,8 @@ static int generate(char id[34]) {
}
/* If that didn't work, generate a random machine id */
- if ((fd = open("/dev/urandom", O_RDONLY|O_CLOEXEC|O_NOCTTY)) < 0) {
+ fd = open("/dev/urandom", O_RDONLY|O_CLOEXEC|O_NOCTTY);
+ if (fd < 0) {
log_error("Failed to open /dev/urandom: %m");
return -errno;
}
@@ -69,6 +82,11 @@ static int generate(char id[34]) {
return k < 0 ? (int) k : -EIO;
}
+ /* 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);
+
for (p = buf, q = id; p < buf + sizeof(buf); p++, q += 2) {
q[0] = hexchar(*p >> 4);
q[1] = hexchar(*p & 15);
@@ -96,10 +114,12 @@ int machine_id_setup(void) {
* will be owned by root it doesn't matter much, but maybe
* people look. */
- if ((fd = open("/etc/machine-id", O_RDWR|O_CREAT|O_CLOEXEC|O_NOCTTY, 0444)) >= 0)
+ fd = open("/etc/machine-id", O_RDWR|O_CREAT|O_CLOEXEC|O_NOCTTY, 0444);
+ if (fd >= 0)
writable = true;
else {
- if ((fd = open("/etc/machine-id", O_RDONLY|O_CLOEXEC|O_NOCTTY)) < 0) {
+ fd = open("/etc/machine-id", O_RDONLY|O_CLOEXEC|O_NOCTTY);
+ if (fd < 0) {
umask(m);
log_error("Cannot open /etc/machine-id: %m");
return -errno;
@@ -126,7 +146,8 @@ int machine_id_setup(void) {
/* Hmm, so, the id currently stored is not useful, then let's
* generate one */
- if ((r = generate(id)) < 0)
+ r = generate(id);
+ if (r < 0)
goto finish;
if (S_ISREG(st.st_mode) && writable) {
@@ -146,7 +167,8 @@ int machine_id_setup(void) {
mkdir_p("/run/systemd", 0755);
- if ((r = write_one_line_file("/run/systemd/machine-id", id)) < 0) {
+ r = write_one_line_file("/run/systemd/machine-id", id);
+ if (r < 0) {
log_error("Cannot write /run/systemd/machine-id: %s", strerror(-r));
unlink("/run/systemd/machine-id");