Package: lxc
Version: 1:4.0.6-1
563ec46266b8967f0ee60e0032bbe66b3b37207c introduced a bug into
lxc 4.0.6: /proc/sys/net is mounted read-only, even though the
container is privileged and did not drop CAP_NET_ADMIN. Result:
# echo 0 >/proc/sys/net/ipv4/ip_forward
bash: /proc/sys/net/ipv4/ip_forward: Read-only file system
See
https://github.com/lxc/lxc/issues/3627
https://github.com/brauner/lxc/commit/3cf860f7ed3eb989fd0a3f31c761966e0fb07937
for further details and a fix (attached).
Regards
Harri
commit 563ec46266b8967f0ee60e0032bbe66b3b37207c
Author: Christian Brauner <christian.brau...@ubuntu.com>
Date: Fri Jan 22 11:41:11 2021 +0100
conf: fix containers retaining CAP_NET_ADMIN
Fixes: #3627
Cc: stable-4.0
Signed-off-by: Christian Brauner <christian.brau...@ubuntu.com>
diff --git a/src/lxc/cgroups/cgfsng.c b/src/lxc/cgroups/cgfsng.c
index 303c2f6ab..acc64a778 100644
--- a/src/lxc/cgroups/cgfsng.c
+++ b/src/lxc/cgroups/cgfsng.c
@@ -1831,7 +1831,7 @@ __cgfsng_ops static bool cgfsng_mount(struct cgroup_ops *ops,
}
if (!wants_force_mount) {
- wants_force_mount = lxc_wants_cap(CAP_SYS_ADMIN, handler->conf);
+ wants_force_mount = !lxc_wants_cap(CAP_SYS_ADMIN, handler->conf);
/*
* Most recent distro versions currently have init system that
diff --git a/src/lxc/conf.c b/src/lxc/conf.c
index ae4972551..d9217a6e1 100644
--- a/src/lxc/conf.c
+++ b/src/lxc/conf.c
@@ -620,24 +620,24 @@ static int lxc_mount_auto_mounts(struct lxc_conf *conf, int flags, struct lxc_ha
* it's busy... MS_REMOUNT|MS_BIND|MS_RDONLY seems to work for
* kernels as low as 2.6.32...
*/
- { LXC_AUTO_PROC_MASK, LXC_AUTO_PROC_MIXED, "proc", "%r/proc", "proc", MS_NODEV|MS_NOEXEC|MS_NOSUID, NULL, 0 },
+ { LXC_AUTO_PROC_MASK, LXC_AUTO_PROC_MIXED, "proc", "%r/proc", "proc", MS_NODEV|MS_NOEXEC|MS_NOSUID, NULL, false },
/* proc/tty is used as a temporary placeholder for proc/sys/net which we'll move back in a few steps */
- { LXC_AUTO_PROC_MASK, LXC_AUTO_PROC_MIXED, "%r/proc/sys/net", "%r/proc/tty", NULL, MS_BIND, NULL, 1 },
- { LXC_AUTO_PROC_MASK, LXC_AUTO_PROC_MIXED, "%r/proc/sys", "%r/proc/sys", NULL, MS_BIND, NULL, 0 },
- { LXC_AUTO_PROC_MASK, LXC_AUTO_PROC_MIXED, NULL, "%r/proc/sys", NULL, MS_REMOUNT|MS_BIND|MS_RDONLY, NULL, 0 },
- { LXC_AUTO_PROC_MASK, LXC_AUTO_PROC_MIXED, "%r/proc/tty", "%r/proc/sys/net", NULL, MS_MOVE, NULL, 1 },
- { LXC_AUTO_PROC_MASK, LXC_AUTO_PROC_MIXED, "%r/proc/sysrq-trigger", "%r/proc/sysrq-trigger", NULL, MS_BIND, NULL, 0 },
- { LXC_AUTO_PROC_MASK, LXC_AUTO_PROC_MIXED, NULL, "%r/proc/sysrq-trigger", NULL, MS_REMOUNT|MS_BIND|MS_RDONLY, NULL, 0 },
- { LXC_AUTO_PROC_MASK, LXC_AUTO_PROC_RW, "proc", "%r/proc", "proc", MS_NODEV|MS_NOEXEC|MS_NOSUID, NULL, 0 },
- { LXC_AUTO_SYS_MASK, LXC_AUTO_SYS_RW, "sysfs", "%r/sys", "sysfs", 0, NULL, 0 },
- { LXC_AUTO_SYS_MASK, LXC_AUTO_SYS_RO, "sysfs", "%r/sys", "sysfs", MS_RDONLY, NULL, 0 },
- { LXC_AUTO_SYS_MASK, LXC_AUTO_SYS_MIXED, "sysfs", "%r/sys", "sysfs", MS_NODEV|MS_NOEXEC|MS_NOSUID, NULL, 0 },
- { LXC_AUTO_SYS_MASK, LXC_AUTO_SYS_MIXED, "%r/sys", "%r/sys", NULL, MS_BIND, NULL, 0 },
- { LXC_AUTO_SYS_MASK, LXC_AUTO_SYS_MIXED, NULL, "%r/sys", NULL, MS_REMOUNT|MS_BIND|MS_RDONLY, NULL, 0 },
- { LXC_AUTO_SYS_MASK, LXC_AUTO_SYS_MIXED, "sysfs", "%r/sys/devices/virtual/net", "sysfs", 0, NULL, 0 },
- { LXC_AUTO_SYS_MASK, LXC_AUTO_SYS_MIXED, "%r/sys/devices/virtual/net/devices/virtual/net", "%r/sys/devices/virtual/net", NULL, MS_BIND, NULL, 0 },
- { LXC_AUTO_SYS_MASK, LXC_AUTO_SYS_MIXED, NULL, "%r/sys/devices/virtual/net", NULL, MS_REMOUNT|MS_BIND|MS_NOSUID|MS_NODEV|MS_NOEXEC, NULL, 0 },
- { 0, 0, NULL, NULL, NULL, 0, NULL, 0 }
+ { LXC_AUTO_PROC_MASK, LXC_AUTO_PROC_MIXED, "%r/proc/sys/net", "%r/proc/tty", NULL, MS_BIND, NULL, true },
+ { LXC_AUTO_PROC_MASK, LXC_AUTO_PROC_MIXED, "%r/proc/sys", "%r/proc/sys", NULL, MS_BIND, NULL, false },
+ { LXC_AUTO_PROC_MASK, LXC_AUTO_PROC_MIXED, NULL, "%r/proc/sys", NULL, MS_REMOUNT|MS_BIND|MS_RDONLY, NULL, false },
+ { LXC_AUTO_PROC_MASK, LXC_AUTO_PROC_MIXED, "%r/proc/tty", "%r/proc/sys/net", NULL, MS_MOVE, NULL, true },
+ { LXC_AUTO_PROC_MASK, LXC_AUTO_PROC_MIXED, "%r/proc/sysrq-trigger", "%r/proc/sysrq-trigger", NULL, MS_BIND, NULL, false },
+ { LXC_AUTO_PROC_MASK, LXC_AUTO_PROC_MIXED, NULL, "%r/proc/sysrq-trigger", NULL, MS_REMOUNT|MS_BIND|MS_RDONLY, NULL, false },
+ { LXC_AUTO_PROC_MASK, LXC_AUTO_PROC_RW, "proc", "%r/proc", "proc", MS_NODEV|MS_NOEXEC|MS_NOSUID, NULL, false },
+ { LXC_AUTO_SYS_MASK, LXC_AUTO_SYS_RW, "sysfs", "%r/sys", "sysfs", 0, NULL, false },
+ { LXC_AUTO_SYS_MASK, LXC_AUTO_SYS_RO, "sysfs", "%r/sys", "sysfs", MS_RDONLY, NULL, false },
+ { LXC_AUTO_SYS_MASK, LXC_AUTO_SYS_MIXED, "sysfs", "%r/sys", "sysfs", MS_NODEV|MS_NOEXEC|MS_NOSUID, NULL, false },
+ { LXC_AUTO_SYS_MASK, LXC_AUTO_SYS_MIXED, "%r/sys", "%r/sys", NULL, MS_BIND, NULL, false },
+ { LXC_AUTO_SYS_MASK, LXC_AUTO_SYS_MIXED, NULL, "%r/sys", NULL, MS_REMOUNT|MS_BIND|MS_RDONLY, NULL, false },
+ { LXC_AUTO_SYS_MASK, LXC_AUTO_SYS_MIXED, "sysfs", "%r/sys/devices/virtual/net", "sysfs", 0, NULL, false },
+ { LXC_AUTO_SYS_MASK, LXC_AUTO_SYS_MIXED, "%r/sys/devices/virtual/net/devices/virtual/net", "%r/sys/devices/virtual/net", NULL, MS_BIND, NULL, false },
+ { LXC_AUTO_SYS_MASK, LXC_AUTO_SYS_MIXED, NULL, "%r/sys/devices/virtual/net", NULL, MS_REMOUNT|MS_BIND|MS_NOSUID|MS_NODEV|MS_NOEXEC, NULL, false },
+ { 0, 0, NULL, NULL, NULL, 0, NULL, false }
};
bool has_cap_net_admin = lxc_wants_cap(CAP_NET_ADMIN, conf);
diff --git a/src/lxc/conf.h b/src/lxc/conf.h
index 664533b8e..28b679fff 100644
--- a/src/lxc/conf.h
+++ b/src/lxc/conf.h
@@ -509,9 +509,9 @@ static inline bool lxc_wants_cap(int cap, struct lxc_conf *conf)
return false;
if (!lxc_list_empty(&conf->keepcaps))
- return !in_caplist(cap, &conf->keepcaps);
+ return in_caplist(cap, &conf->keepcaps);
- return in_caplist(cap, &conf->caps);
+ return !in_caplist(cap, &conf->caps);
}
__hidden extern int setup_sysctl_parameters(struct lxc_list *sysctls);
