From eb0f0863f5af48865fb4569e2076d5f9e2313995 Mon Sep 17 00:00:00 2001 From: Lennart Poettering Date: Mon, 10 Mar 2014 21:36:01 +0100 Subject: [PATCH] nspawn: don't try mknod() of /dev/console with the correct major/minor 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. --- src/nspawn/nspawn.c | 25 ++++++++++--------------- 1 file changed, 10 insertions(+), 15 deletions(-) diff --git a/src/nspawn/nspawn.c b/src/nspawn/nspawn.c index d8d0dae16..bef866a96 100644 --- a/src/nspawn/nspawn.c +++ b/src/nspawn/nspawn.c @@ -879,23 +879,19 @@ static int setup_ptmx(const char *dest) { } static int setup_dev_console(const char *dest, const char *console) { + _cleanup_umask_ mode_t u; + const char *to; struct stat st; - _cleanup_free_ char *to = NULL; int r; - _cleanup_umask_ mode_t u; 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; -- 2.30.2