On Tue, Jun 08, 2021 at 04:38:15PM -0700, Andi Kleen wrote:
On 6/8/2021 4:19 PM, Kees Cook wrote:
On Sat, Jun 05, 2021 at 05:03:57PM +0200, John Wood wrote:
[...] the kselftest to avoid the detection ;) ). So, in this version, to track all the statistical data (info related with application crashes), the extended attributes feature for the executable files are used. The xattr is also used to mark the executables as "not allowed" when an attack is detected. Then, the execve system call rely on this flag to avoid following executions of this file.
I have some concerns about this being actually usable and not creating DoS situations. For example, let's say an attacker had found a hard-to-hit bug in "sudo", and starts brute forcing it. When the brute LSM notices, it'll make "sudo" unusable for the entire system, yes?
And a reboot won't fix it, either, IIUC.
The whole point of the mitigation is to trade potential attacks against DOS.
If you're worried about DOS the whole thing is not for you.
Right, but there's no need to make a system unusable for everyone else. There's nothing here that relaxes the defense (i.e. stop spawning apache for 10 minutes). Writing it to disk with nothing that undoes it seems a bit too much. :)