why is intercepting system calls considerred bad?

why is intercepting system calls considerred bad?

[Irfan Habib]

HI,

I recently met a kernel janitor, who told me that intercepting system
calls is undesirable, why?

Re: why is intercepting system calls considerred bad?

[Joshua Hudson]

On 7/20/06, Irfan Habib <irfan.habib@gmail.com> wrote:
> HI,
>
> I recently met a kernel janitor, who told me that intercepting system
> calls is undesirable, why?

I'll bite.

You intercept. Somebody else intercepts. You want to stop intercepting.

For this reason, anybody who intercepts a system call must be compiled
in, and if two intercept the same system call, than the link order
dictates behavior.

Obviously not desirable.

RE: why is intercepting system calls considerred bad?

[David Schwartz]

> I recently met a kernel janitor, who told me that intercepting system
> calls is undesirable, why?

	It's a club. Software development should be done with scalpels.

	DS

Re: why is intercepting system calls considerred bad?

[Bodo Eggert]

Joshua Hudson <joshudson@gmail.com> wrote:
> On 7/20/06, Irfan Habib <irfan.habib@gmail.com> wrote:

>> I recently met a kernel janitor, who told me that intercepting system
>> calls is undesirable, why?
> 
> I'll bite.
> 
> You intercept. Somebody else intercepts. You want to stop intercepting.

Use a double-linked list.

Having a mechanism to intercept syscalls will slow down syscall processing,
and there was no legit user in the history of linux. If you need something
like that, there is ptrace.

> For this reason, anybody who intercepts a system call must be compiled
> in,

No, but they may need to be compiled in for other reasons.

> and if two intercept the same system call, than the link order
> dictates behavior.
> 
> Obviously not desirable.

ACK.
-- 
Ich danke GMX dafür, die Verwendung meiner Adressen mittels per SPF
verbreiteten Lügen zu sabotieren.

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