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Bug 1436004 - Unexpected, catastrophic behavior from systemd-tmpfiles
Summary: Unexpected, catastrophic behavior from systemd-tmpfiles
Keywords:
Status: CLOSED ERRATA
Alias: None
Product: Red Hat Enterprise Linux 7
Classification: Red Hat
Component: systemd
Version: 7.3
Hardware: x86_64
OS: Linux
unspecified
high
Target Milestone: rc
: ---
Assignee: Jan Synacek
QA Contact: Frantisek Sumsal
URL:
Whiteboard:
Depends On:
Blocks: 1546552 1549617 1551061
TreeView+ depends on / blocked
 
Reported: 2017-03-26 16:00 UTC by Tom Kelliher
Modified: 2022-03-13 14:14 UTC (History)
5 users (show)

Fixed In Version: systemd-219-58.el7
Doc Type: If docs needed, set a value
Doc Text:
Clone Of:
Environment:
Last Closed: 2018-10-30 11:32:10 UTC
Target Upstream Version:
Embargoed:

Attachments (Terms of Use)

Description Tom Kelliher 2017-03-26 16:00:08 UTC 
Description of problem:

A tmpfiles.d entry of the form

R! /foo/.*

appears to be interpreted by systemd-tmpfiles as something similar to

R! /

destroying the filesystem.

Version-Release number of selected component (if applicable):

219-30.el7_3.7

How reproducible:

Consistently reproducible.

Steps to Reproduce:
1. Create the directory /foo.
2. In /etc/tmpfiles.d create the file foo.conf containing the one line
        R! /foo/.*
3. Reboot.
4. Wait several minutes; the system won't come up to the user login stage.
5. Reboot a second time.

Actual results:

Grub reports that it can't find /grub2/i386-pc/normal.mod and drops into rescue mode.  The filesystem appears to be destroyed.

Expected results:

dot files and directories in /foo/ are (recursively) removed.

Additional info:

None.
Comment 2 Jan Synacek 2017-03-27 07:05:12 UTC 
You want to use r! instead of R! if you want to use that glob.
Comment 3 Jan Synacek 2017-03-27 07:50:57 UTC 
https://github.com/systemd/systemd/issues/5644
Comment 4 Lukáš Nykrýn 2017-03-27 10:23:40 UTC 
The problem here is, that tmpfiles did exactly what you asked then to do.
For glob /foo/.* it will also match /foo/.. which is /.

But I agree that this behavior is kinda dangerous and should be changed.
Comment 5 Tom Kelliher 2017-03-27 12:12:49 UTC 
I had forgotten about '..'.  Thanks for enlightening me.  The behavior is kinda dangerous, but entirely consistent.  At the very least, this experience gave me the opportunity to put my dump/restore strategy to the test, during which I came across a bug while restoring a level 1 dump, but that's for another bug report.

Thank you for your responses.
Comment 6 Jan Synacek 2017-03-29 07:05:00 UTC 
Merged upstream.
Comment 7 Jan Synacek 2017-03-29 07:32:42 UTC 
How to test:

1) # mkdir -p /foo/bar/dir{1,2}
2) # touch /foo/bar/file{1,2}
3) # echo "R /foo/bar/.* - - - - -" > /etc/tmpfiles.d/test.conf
4) # systemd-tmpfiles --remove
5) # ls /foo
/foo will be empty if the bug reproduces.
Comment 8 Jan Synacek 2017-03-29 08:28:03 UTC 
A better reproducer...

$ cat rep.sh 
#!/bin/sh

mkdir -p /foo/bar/.dir{1,2}
mkdir -p /foo/bar/dir{3,4}
touch /foo/bar/.file{5,6}
touch /foo/bar/file{7,8}
systemd-tmpfiles --remove
ls -la /foo/bar

The expected input is something like

drwxr-xr-x 4 root root 4096 Mar 29 10:25 .
drwxr-xr-x 3 root root 4096 Mar 29 10:07 ..
drwxr-xr-x 2 root root 4096 Mar 29 10:07 dir3
drwxr-xr-x 2 root root 4096 Mar 29 10:07 dir4
-rw-r--r-- 1 root root    0 Mar 29 10:25 file7
-rw-r--r-- 1 root root    0 Mar 29 10:25 file8

When the bug reproduces, 'ls -la /foo/bar' fails with

ls: cannot access '/foo/bar': No such file or directory
Comment 9 Jan Synacek 2017-04-26 13:22:52 UTC 
(In reply to Jan Synacek from comment #6)
> Merged upstream.

My original patch was merged, but it does solve only a small part of the issue. Much better solution is being implemented in https://github.com/systemd/systemd/pull/5809/.
Comment 10 Jan Synacek 2017-05-03 06:24:56 UTC 
https://github.com/systemd/systemd/commit/84e72b5ef445ffb256bc4add4209c4c9c9855206
Comment 11 Jan Synacek 2017-05-04 13:11:15 UTC 
Backporting the upstream fixes turned out much harder than it looked. Moving to RHEL-7.5.
Comment 15 Jan Synacek 2018-05-28 09:56:21 UTC 
https://github.com/lnykryn/systemd-rhel/pull/208
Comment 16 Lukáš Nykrýn 2018-06-21 10:11:25 UTC 
fix merged to staging branch -> https://github.com/lnykryn/systemd-rhel/pull/208 -> post
Comment 20 errata-xmlrpc 2018-10-30 11:32:10 UTC 
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHBA-2018:3245
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