Re: [patch] let CONFIG_SECCOMP default to n

[Bodo Eggert]

Ingo Molnar <mingo@xxxxxxx> wrote:
> * Jeff Dike <jdike@xxxxxxxxxxx> 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.

http://david.woodhou.se/why-not-spf.html
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