[apparmor] Apparmor: Queries

[Seth Arnold]

On Tue, Apr 13, 2021 at 11:18:12PM +0530, Murali Selvaraj wrote:
> We have observed few configuration files are present in /tmp which are
> needed for certain processes.
> For example, few of the files are hidden files located in /tmp/.
> 
> In that case, shall we add below entry
> 
> /tmp/** rw,
> 
> or Do we need to add entries for file specific as below
> 
> /tmp/file.txt r,
> /tmp/.init_complete rw,
> 
> Which would be the best way for security concern as well as embedded devices ?
> Please advise.

I'm worried that applications that are writing to /tmp/ using fixed
filenames like this are likely to be susceptible to file /tmp/ races. You
can enable the kernel's mitigations (see sysctl -a | grep fs.protected)
for this but that's only a partial mitigation for the problem.

Better is for the applications to write their temporary files into
per-application directories as appropriate.

Certainly I'd want to give tighter rules than /tmp/** rw, wherever
possible.

Thanks
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