AppArmor, Ubuntu and MySQL
The other night I was investigating a rather heinous utf8 issue. I was working on a local copy of Ubuntu 12.04 that contained the entire dev environment, except for data. So I exported a copy of the relevant data as a CSV, pulled it down, and attempted to run a
LOAD DATA INFILE. Sane enough right? This is something I’ve done a million times in a bunch of different environments. However, in the vast, vast majority of cases, the error is typically pretty clear. In this case, not so much.
The error here was;
ERROR 29 (HY000): File ‘/home/technician/data.csv’ not found (Errcode: 13)
I’ve been known to have short term memory glitches, so I exited mysql and double checked my path. Three times. After jumping in and out of the mysql shell, I figured there must have been some sort of issue with the placement or permissions of file. Perhaps mysql simply isn’t allowed to read the file from there. So I moved it over to the /tmp folder. Ubuntu allows everyone to read from there. No dice. So I moved it back to someplace that made sense and chown'ed it to mysql:mysql still no dice. It was simply as if mysql couldn’t see the file.
After quite a bit of googling, it turns out a program called AppArmor was blocking mysql’s access to the filesystem. From the AppArmor Wiki;
AppArmor is a Linux Security Module implementation of name-based mandatory access controls. AppArmor confines individual programs to a set of listed files and posix 1003.1e draft capabilities.
As it turns out, I’m not the only one who had issues with this piece of software. Like any good piece of software fighting the good security fight, it gives no quarter, intentionally obfuscating the exact error. For Ubuntu, this is pretty strange behavior. Typically, things in Ubuntu just work, and there aren’t too many gotchas.
After a bit more Googling, the solution was relatively simple. AppArmor operates by reading in profiles for each piece of software that it monitors. Those profiles have two modes of execution, per the docs.
- Complaining/Learning: profile violations are permitted and logged. Useful for testing and developing new profiles.
- Enforced/Confined: enforces profile policy as well as logging the violation.
So the only thing we actually have to do to get mysql back in a place where it’s working as expected is to run the following.
$ sudo aa-complain /usr/bin/mysql
It’s great that Ubuntu has enabled this by default, and taken a great step in being secure. However, it feels too heavy handed.
Hope this helps someone!