procd: detect lxc container and behave accordingly

meaning to not mount some specific parts witch cause trouble.

The patch is based on previous work of @mikma to combine OpenWrt with
lxd[0]. This patch however adds a detection copied from *virt-what* to
check /proc/1/environment for the string "container".

Thanks to @dangowrt for the cleanup.

[0]: https://github.com/containercraft/openwrt-lxd/blob/master/patches/procd-openwrt-18.06/001_lxd_no_mounts.patch

Signed-off-by: Paul Spooren <mail@aparcar.org>

diff --git a/container.h b/container.h
new file mode 100644 (file)
index 0000000..7fb0768
--- /dev/null
+++ b/container.h
@@ -0,0 +1,22 @@
+/*
+ * Copyright (C) 2019 Paul Spooren <mail@aparcar.de>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License version 2.1
+ * as published by the Free Software Foundation
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#ifndef __CONTAINER_H
+#define __CONTAINER_H
+#include <stdlib.h>
+
+static inline bool is_container() {
+       return !!getenv("container");
+}
+
+#endif

diff --git a/initd/early.c b/initd/early.c
index 2e151125d2c08830e435841be3ddb1e8a76d2a63..7b281b20b8233785de957d6b0dba23338e916e45 100644 (file)
--- a/initd/early.c
+++ b/initd/early.c
@@ -25,6 +25,7 @@
 #include "../utils/utils.h"
 #include "init.h"
 #include "../libc-compat.h"
+#include "../container.h"
 
 static void
 early_dev(void)
@@ -56,14 +57,17 @@ early_mounts(void)
 {
        unsigned int oldumask = umask(0);
 
-       mount("proc", "/proc", "proc", MS_NOATIME | MS_NODEV | MS_NOEXEC | MS_NOSUID, 0);
-       mount("sysfs", "/sys", "sysfs", MS_NOATIME | MS_NODEV | MS_NOEXEC | MS_NOSUID, 0);
-       mount("cgroup", "/sys/fs/cgroup", "cgroup",  MS_NODEV | MS_NOEXEC | MS_NOSUID, 0);
-       mount("tmpfs", "/dev", "tmpfs", MS_NOATIME | MS_NOSUID, "mode=0755,size=512K");
-       ignore(symlink("/tmp/shm", "/dev/shm"));
-       mkdir("/dev/pts", 0755);
-       mount("devpts", "/dev/pts", "devpts", MS_NOATIME | MS_NOEXEC | MS_NOSUID, "mode=600");
-       early_dev();
+       if (!is_container()) {
+               mount("proc", "/proc", "proc", MS_NOATIME | MS_NODEV | MS_NOEXEC | MS_NOSUID, 0);
+               mount("sysfs", "/sys", "sysfs", MS_NOATIME | MS_NODEV | MS_NOEXEC | MS_NOSUID, 0);
+               mount("cgroup", "/sys/fs/cgroup", "cgroup",  MS_NODEV | MS_NOEXEC | MS_NOSUID, 0);
+               mount("tmpfs", "/dev", "tmpfs", MS_NOATIME | MS_NOSUID, "mode=0755,size=512K");
+               ignore(symlink("/tmp/shm", "/dev/shm"));
+               mkdir("/dev/pts", 0755);
+               mount("devpts", "/dev/pts", "devpts", MS_NOATIME | MS_NOEXEC | MS_NOSUID, "mode=600");
+
+               early_dev();
+       }
 
        early_console("/dev/console");
        if (mount_zram_on_tmp()) {

diff --git a/initd/zram.c b/initd/zram.c
index b41bfd999ba2630f086cba140e5fdcd7aabfac6b..487d3d615f1d0b0eb9a28697383c2c89806868c0 100644 (file)
--- a/initd/zram.c
+++ b/initd/zram.c
@@ -12,6 +12,7 @@
 #include <sys/stat.h>
 
 #include "../log.h"
+#include "../container.h"
 
 #include "init.h"
 
@@ -116,10 +117,12 @@ mount_zram_on_tmp(void)
                waitpid(pid, NULL, 0);
        }
 
-       ret = mount("/dev/zram0", "/tmp", "ext4", MS_NOSUID | MS_NODEV | MS_NOATIME, "errors=continue,noquota");
-       if (ret < 0) {
-               ERROR("Can't mount /dev/zram0 on /tmp: %m\n");
-               return errno;
+       if (!is_container()) {
+               ret = mount("/dev/zram0", "/tmp", "ext4", MS_NOSUID | MS_NODEV | MS_NOATIME, "errors=continue,noquota");
+               if (ret < 0) {
+                       ERROR("Can't mount /dev/zram0 on /tmp: %m\n");
+                       return errno;
+               }
        }
 
        LOG("Using up to %ld kB of RAM as ZRAM storage on /mnt\n", zramsize);

diff --git a/plug/coldplug.c b/plug/coldplug.c
index c6a89c30a6fc2e11539f7643d4fde41c12bbbf62..12df421bb205c4074a4f08af4493bec3d9d37891 100644 (file)
--- a/plug/coldplug.c
+++ b/plug/coldplug.c
@@ -22,6 +22,7 @@
 #include "../libc-compat.h"
 
 #include "hotplug.h"
+#include "../container.h"
 
 static struct uloop_process udevtrigger;
 
@@ -43,13 +44,16 @@ void procd_coldplug(void)
        char *argv[] = { "udevtrigger", NULL };
        unsigned int oldumask = umask(0);
 
-       umount2("/dev/pts", MNT_DETACH);
-       umount2("/dev/", MNT_DETACH);
-       mount("tmpfs", "/dev", "tmpfs", MS_NOSUID, "mode=0755,size=512K");
+       if (!is_container()) {
+               umount2("/dev/pts", MNT_DETACH);
+               umount2("/dev/", MNT_DETACH);
+               mount("tmpfs", "/dev", "tmpfs", MS_NOSUID, "mode=0755,size=512K");
+               mkdir("/dev/pts", 0755);
+               mount("devpts", "/dev/pts", "devpts", MS_NOEXEC | MS_NOSUID, 0);
+       }
+
        ignore(symlink("/tmp/shm", "/dev/shm"));
-       mkdir("/dev/pts", 0755);
        umask(oldumask);
-       mount("devpts", "/dev/pts", "devpts", MS_NOEXEC | MS_NOSUID, 0);
        udevtrigger.cb = udevtrigger_complete;
        udevtrigger.pid = fork();
        if (!udevtrigger.pid) {