Don't attempt to create devices in LXC containers
Affects | Status | Importance | Assigned to | Milestone | |
---|---|---|---|---|---|
makedev (Ubuntu) |
Fix Released
|
High
|
Unassigned | ||
Precise |
Fix Released
|
High
|
Unassigned | ||
Trusty |
Fix Released
|
High
|
Unassigned | ||
Xenial |
Fix Released
|
High
|
Unassigned | ||
Yakkety |
Fix Released
|
High
|
Unassigned | ||
Zesty |
Fix Released
|
High
|
Unassigned |
Bug Description
Right now the "makedev" postinst script will attempt to create a number of devices in /dev, failing the package upgrade should any of those mknod calls fail.
LXC containers, especially unprivileged ones do not allow the use of mknod, making it impossible to upgrade makedev in those containers and preventing Ubuntu release upgrades.
The fix is quite simple, detect that we are running in an LXC container and skip the rest of the postinst script as is done in a number of other cases.
= SRU
== Rationale
This issue prevents release to release upgrades in unprivileged LXC containers when makedev is part of the upgraded set. This is currently visible when upgrading from Ubuntu 12.04 to Ubuntu 14.04.
== Testcase
Install the new package in an unprivileged container. With LXD, simply use "lxc launch ubuntu:<series> test" to create the container.
Prior to this fix, the upgrade will fail on some mknod errors, after it, it'll go on after printing a message indicating that LXC was detected.
== Regression potential
The detection logic is based on PID 1's environment containing a container=lxc entry. If a non-LXC system somehow had that set, it'd lead to the makedev upgrade no longer creating extra devices. This is unlikely to really matter though since the system is clearly already functioning properly at that point.
Similarly, some privileged LXC containers can be configured in a way where mknod is possible, this update will still disable the postinst for those cases as short of attempting every mknod ahead of time, there is no reliable way to detect any seccomp or apparmor policy in play.
no longer affects: | makedev (Ubuntu Vivid) |
Changed in makedev (Ubuntu Precise): | |
assignee: | nobody → rahmadani (rahmadani) |
Changed in makedev (Ubuntu Trusty): | |
assignee: | nobody → rahmadani (rahmadani) |
Changed in makedev (Ubuntu Xenial): | |
assignee: | nobody → rahmadani (rahmadani) |
Changed in makedev (Ubuntu Yakkety): | |
assignee: | nobody → rahmadani (rahmadani) |
Changed in makedev (Ubuntu Zesty): | |
assignee: | nobody → rahmadani (rahmadani) |
Changed in makedev (Ubuntu Precise): | |
assignee: | rahmadani (rahmadani) → nobody |
Changed in makedev (Ubuntu Trusty): | |
assignee: | rahmadani (rahmadani) → nobody |
Changed in makedev (Ubuntu Xenial): | |
assignee: | rahmadani (rahmadani) → nobody |
Changed in makedev (Ubuntu Yakkety): | |
assignee: | rahmadani (rahmadani) → nobody |
Changed in makedev (Ubuntu Zesty): | |
assignee: | rahmadani (rahmadani) → nobody |
This needs to be urgently fixed for 12.04, as this bug is blocking upgrades of 12.04 to 14.04 succeeding.