fill_autodev: bind-mount if mknod fails (v3)

First, rename setup_autodev to fill_autodev, since all it
does is populate it, not fully set it up.

Secondly, if mknod of a device fails, then try bind-mounting
it from the host rather than failing immediately.

Note that this isn't an urgent patch because the common.userns
configuration hook already specifies bind,create=file mount
entries for all the devices we would want.

Changelog (v3): ignore if /dev doesn't exist

Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
Acked-by: Stéphane Graber <stgraber@ubuntu.com>
This commit is contained in:
Serge Hallyn 2015-01-12 23:56:28 +00:00 committed by Stéphane Graber
parent 87da4ec337
commit 9cb4d18355

View File

@ -1155,7 +1155,7 @@ static const struct lxc_devs lxc_devs[] = {
{ "console", S_IFCHR | S_IRUSR | S_IWUSR, 5, 1 },
};
static int setup_autodev(const char *root)
static int fill_autodev(const char *root)
{
int ret;
char path[MAXPATHLEN];
@ -1170,6 +1170,9 @@ static int setup_autodev(const char *root)
return -1;
}
if (!dir_exists(path)) // ignore, just don't try to fill in
return 0;
INFO("Populating /dev under %s", root);
cmask = umask(S_IXUSR | S_IXGRP | S_IXOTH);
for (i = 0; i < sizeof(lxc_devs) / sizeof(lxc_devs[0]); i++) {
@ -1179,8 +1182,25 @@ static int setup_autodev(const char *root)
return -1;
ret = mknod(path, d->mode, makedev(d->maj, d->min));
if (ret && errno != EEXIST) {
SYSERROR("Error creating %s", d->name);
return -1;
char hostpath[MAXPATHLEN];
FILE *pathfile;
// Unprivileged containers cannot create devices, so
// bind mount the device from the host
ret = snprintf(hostpath, MAXPATHLEN, "/dev/%s", d->name);
if (ret < 0 || ret >= MAXPATHLEN)
return -1;
pathfile = fopen(path, "wb");
if (!pathfile) {
SYSERROR("Failed to create device mount target '%s'", path);
return -1;
}
fclose(pathfile);
if (mount(hostpath, path, 0, MS_BIND, NULL) != 0) {
SYSERROR("Failed bind mounting device %s from host into container",
d->name);
return -1;
}
}
}
umask(cmask);
@ -3847,7 +3867,7 @@ int lxc_setup(struct lxc_handler *handler)
ERROR("failed to run autodev hooks for container '%s'.", name);
return -1;
}
if (setup_autodev(lxc_conf->rootfs.mount)) {
if (fill_autodev(lxc_conf->rootfs.mount)) {
ERROR("failed to populate /dev in the container");
return -1;
}