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nspawn: don't try mknod() of /dev/console with the correct major/minor

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We overmount /dev/console with an external pty anyway, hence there's no
point in using the real major/minor when we create the node to
overmount. Instead, use the one of /dev/null now.

This fixes a race against the cgroup device controller setup we are
using. In case /dev/console was create before the cgroup policy was
applied all was good, but if created in the opposite order the mknod()
would fail, since creating /dev/console is not allowed by it. Creating
/dev/null instances is however permitted, and hence use it.
This commit is contained in:
Lennart Poettering
2014-03-10 21:36:01 +01:00
parent 1b9e5b1263
commit eb0f0863f5
1 changed files with 11 additions and 16 deletions
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27
src/nspawn/nspawn.c
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@@ -879,23 +879,19 @@ static int setup_ptmx(const char *dest) {
}
static int setup_dev_console(const char *dest, const char *console) {
struct stat st;
_cleanup_free_ char *to = NULL;
int r;
_cleanup_umask_ mode_t u;
const char *to;
struct stat st;
int r;
assert(dest);
assert(console);
u = umask(0000);
if (stat(console, &st) < 0) {
log_error("Failed to stat %s: %m", console);
if (stat("/dev/null", &st) < 0) {
log_error("Failed to stat /dev/null: %m");
return -errno;
} else if (!S_ISCHR(st.st_mode)) {
log_error("/dev/console is not a char device");
return -EIO;
}
r = chmod_and_chown(console, 0600, 0, 0);
@@ -904,16 +900,15 @@ static int setup_dev_console(const char *dest, const char *console) {
return r;
}
if (asprintf(&to, "%s/dev/console", dest) < 0)
return log_oom();
/* We need to bind mount the right tty to /dev/console since
* ptys can only exist on pts file systems. To have something
* to bind mount things on we create a device node first, that
* has the right major/minor (note that the major minor
* doesn't actually matter here, since we mount it over
* anyway). */
* to bind mount things on we create a device node first, and
* use /dev/null for that since we the cgroups device policy
* allows us to create that freely, while we cannot create
* /dev/console. (Note that the major minor doesn't actually
* matter here, since we mount it over anyway). */
to = strappenda(dest, "/dev/console");
if (mknod(to, (st.st_mode & ~07777) | 0600, st.st_rdev) < 0) {
log_error("mknod() for /dev/console failed: %m");
return -errno;