unattended-upgrade(8)

Alexander Schrijver alexander.schrijver at gmail.com
Thu Apr 1 23:34:13 BST 2010


> Read up on help.ubuntu.com about Ubuntu archive we have a few sections
> & a few repositories. I'm talking about distro repository e.g.
> karmic-security. Whatever enters that by default is picked up by
> unattended-upgrades.

I'll try to read a bit more how this stuff works. I find it difficult because
it is all over the place, and not always up to date e.g. manpages.

> It's not all software which has security bugs =) we don't know that.
> It's all packages which have been updated and are deemed important /
> high-risk security vulnerabilities  by Ubuntu security team, e.g. CVE
> fixes.

Yeah, but these would include e.g. Firefox XUL files?

> Yes but -upgrades and -security do not allow API/ABI changes / so-name
> bumps. So we are safe here for majority of programming languages. Read
> up about sonames. Just google.

Okay I will, I thought this was handled different in Ubuntu.

> No. Theoretically someone can get access to your system and whipe your
> whole hardrive or get you into denial of service. It is more important
> to prevent you from becoming a spam sending slave then to prevent
> programs from crashing. Also dpkg writes files atomically so in the
> file system for a given package you either have old files & new files
> or pending / unavailable (e.g. python). And there are no soname
> changes in these upgrades. So there has been a lot of work done to
> make it as harmless as possible.

Except for the program and libraries in memory.

> Crashing programs is not a problem. Loosing user data is, like for
> example the email you have been typing in the browser for an hour is
> important that why programs are not shudown. Just because firefox
> looks weird it doesn't prevent you to save the email into draft before
> restarting firefox.

How can you ever be sure of this? For example in the case of firefox it would
change the XUL/Javascript files. As i said, i noticed the interface would get
messed up, but it could get messed up in a way your data couldn't be send
anymore.

> Potentially anything can happen =) but because of dpkg & sonames &
> ldconfig and massive testing of security fixes & them actually being
> really small crashing is hightly unlickly.
> 
> If firefox did crash on upgrade instead of "firefox needs restarting"
> you will get "firefox has just crashed" and apport will kick in to
> start collecting backtraces to send a bug report to launchpad ;-)

I think this is a really bad policy. Most (All?) programs don't expect their
resources to be changed while they are running. Knowingly bringing programs in
an unknown state seems like a reallly really bad idea to me.




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