Re: [patch] let CONFIG_SECCOMP default to n

Bodo Eggert
2006-07-17T11:38:37Z

Ingo Molnar <mingo@elte.hu> wrote:
> * Jeff Dike <jdike@addtoit.com> wrote:

>> Now, there were a couple of ways to legitimately escape from UML, and
>> they *did* involve ptrace. Things like single-stepping a system call
>> instruction or putting a breakpoint on a system call instruction and
>> single-stepping from the breakpoint. As far as I know, these were
>> discovered and fixed by UML developers before there was any outside
>> awareness of these bugs.
>
> also, UML 'ptrace clients' are allowed alot more leeway than what a
> seccomp-alike ptrace/utrace based syscall filter would allow. It would
> clearly exclude activities like 'setting a breakpoint' or
> 'single-stepping' - valid syscalls would be limited to
> read/write/sigreturn/exit.

So instead of breakpointing (using int3), you'd have to write
'mv flag I_AM_HERE;self:jmp self' and resort to polling?
This would not prevent (ab)use except for some corner cases.
--
Ich danke GMX dafür, die Verwendung meiner Adressen mittels per SPF
verbreiteten Lügen zu sabotieren.