Re: [PATCH, local root on 2.4, 2.6?] compute_creds race

[Olaf Dietsche <olaf+list.linux-kernel@olafdietsche.de>]

Andy Lutomirski <luto@myrealbox.com> writes:

> The setuid program is now running with uid=euid=500 but full permitted
> capabilities.  There are two (or three) ways to effectively get local
> root now:
>
> 1. IIRC, linux 2.4 doesn't check capabilities in ptrace, so A could
> just ptrace B again.

In linux 2.4.25 there is no LSM and thus no vulnerability.

linux-2.4.25/fs/exec.c:
		lock_kernel();
		if (must_not_trace_exec(current)
		    || atomic_read(&current->fs->count) > 1
		    || atomic_read(&current->files->count) > 1
		    || atomic_read(&current->sig->count) > 1) {
			if(!capable(CAP_SETUID)) {
				bprm->e_uid = current->uid;
				bprm->e_gid = current->gid;
			}
			if(!capable(CAP_SETPCAP)) {
				new_permitted = cap_intersect(new_permitted,
							current->cap_permitted);
			}
		}
		do_unlock = 1;

Regards, Olaf.