MySQL Bugs: #36462: mysql_install_db fails when run as user root and root-directory not writable

Bug #36462	mysql_install_db fails when run as user root and root-directory not writable
Submitted:	2 May 2008 5:52	Modified:	7 Mar 2010 18:46
Reporter:	Johannes Martin	Email Updates:
Status:	Closed	Impact on me:	None
Category:	MySQL Server: Installing	Severity:	S3 (Non-critical)
Version:	5.0.45, 5.0, 5.1, 6.0 bzr	OS:	Linux
Assigned to:	Jonathan Perkin	CPU Architecture:	Any

Description:
After creating the /var/lib/mysql, /var/lib/mysql/mysql and /var/lib/mysql/test directories, mysql should change ownership of the directories to the mysql user. However, it only does this if the root directory is writable:
if test -w / -a ! -z "$user"; then
  chown $user $ldata $ldata/mysql $ldata/test;
fi

"test -w /" does not seem to be a suitable check for determining whether the current user is root.

How to repeat:
Start mysql_install_db --user=mysql ... as user root on a system that has a non-writable root-directory

Result:
---
Creating MySQL privilege database...
Installing MySQL system tables...
ERROR: 1005  Can't create table 'db' (errno: 13)
080502  9:26:34 [ERROR] Aborting
---

Suggested fix:
Change the statement to read:

if test ! -z "$user"; then
  chown $user $ldata $ldata/mysql $ldata/test;
fi

Thank you for the report.

Please provide output of `ls -laR /var/lib/mysql`

Sorry, the original directory contents are no longer available.

Also, I do not quite understand why you would need this. You can verify that "test -w /" does not work as intended quite easily.

Thank you for the feedback.

But root user is allowed to write even to directory with 000 rights:

apple:/test root# ls -ld bug36462/
d---------   2 apple  apple  68 22 май 00:34 bug36462/
apple:/test root# id
uid=0(root) gid=0(wheel) groups=0(wheel) ...
apple:/test root#  if test -w bug36462; then echo 1; fi
1
apple:/test root# rmdir bug36462/
apple:/test root# 

I ask for output of ls command to be sure directories have correct rights.

You wrote:
> But root user is allowed to write even to directory with 000 rights:
Yes, that's true.

But the root user cannot write to a filesystem that is mounted read-only.

If you boot from the network or a CD, you may have a root filesystem that is not-writable at all.

Thank you for the feedback.

Verified as described reading source code.

A patch for this bug has been committed. After review, it may
be pushed to the relevant source trees for release in the next
version. You can access the patch from:

  http://lists.mysql.com/commits/62625

2667 Jonathan Perkin	2009-01-07
      bug#36462: mysql_install_db fails when run as user root and root-directory not writable
      
      Rather than use the -w test, attempt the chown and bail out if it fails.

Simple comment: "Check you have" should be "Check that you have", shouldn't it?

Also, aren't you also changing the behavior? Before, if you ran this as an ordinary user, it would not try to chown. But now if you do the same, it fails because it can't. Maybe that's the correct behavior but it's changed as far as I can tell.

'Check that' is probably better grammar, though given the quality of English throughout the rest of the script I'm not sure it matters much :-)

The change in behaviour is deliberate.  I know of no reasonable way of portably checking that the chown will succeed other than actually running it and checking exit status.  Note that this whole test is still wrapped inside the test for --user being passed on the command line, which an 'ordinary user' would be unlikely to use (the --help still suggests that you need to be root to use --user, although that is not necessarily the case).

A patch for this bug has been committed. After review, it may
be pushed to the relevant source trees for release in the next
version. You can access the patch from:

  http://lists.mysql.com/commits/62690

2667 Jonathan Perkin	2009-01-08
      bug#36462: mysql_install_db fails when run as user root and root-directory not writable
            
      Rather than use the -w test, attempt the chown and bail out if it fails.

OK to push.

A patch for this bug has been committed. After review, it may
be pushed to the relevant source trees for release in the next
version. You can access the patch from:

  http://lists.mysql.com/commits/70593

2750 Jonathan Perkin	2009-03-26 [merge]
      bug#36462: mysql_install_db fails when run as user root and root-directory
                 not writable
                  
      Rather than use the -w test, attempt the chown and bail out if it fails.

Pushed into mysql-6.0-build.

Pushed into 6.0.12-alpha (revid:svoj@sun.com-20090506125450-yokcmvqf2g7jhujq) (version source revid:timothy.smith@sun.com-20090402052930-78npdzhwd7hg7dav) (merge vers: 6.0.11-alpha) (pib:6)

Noted in 6.0.12 changelog.

mysql_install_db failed if run as root and the root directory (/) was
not writable.

A patch for this bug has been committed. After review, it may
be pushed to the relevant source trees for release in the next
version. You can access the patch from:

  http://lists.mysql.com/commits/91112

2948 Jonathan Perkin	2009-11-20
      bug#36462: mysql_install_db fails when run as user root and
                 root-directory not writable
                        
      Rather than use the -w test, attempt the chown and bail out if
      it fails.

A patch for this bug has been committed. After review, it may
be pushed to the relevant source trees for release in the next
version. You can access the patch from:

  http://lists.mysql.com/commits/91310

2899 Jonathan Perkin	2009-11-23
      bug#36462: mysql_install_db fails when run as user root and
                 root-directory not writable
      
      Rather than use the -w test, attempt the chown and bail out if
      it fails.

Pushed into 6.0.14-alpha (revid:alik@sun.com-20091211055901-yp18b3c7xuhl87rf) (version source revid:alik@sun.com-20091211055401-43rjwq7gjed6ds83) (merge vers: 6.0.14-alpha) (pib:13)

Pushed into 5.6.0-beta (revid:alik@sun.com-20091211055628-ltr7fero363uev7r) (version source revid:alik@sun.com-20091211055453-717czhtezc74u8db) (merge vers: 5.6.0-beta) (pib:13)

Entries added to the 5.60 and 6.0.14 changelogs.

Pushed into 5.5.3-m3 (revid:alik@sun.com-20100306103849-hha31z2enhh7jwt3) (version source revid:vvaintroub@mysql.com-20091211201717-03qf8ckwiw0np80p) (merge vers: 5.6.0-beta) (pib:16)

Moved 5.6.0 changelog entry to 5.5.3.