Re: Signal security

Linus Torvalds (torvalds@transmeta.com)
Tue, 19 May 1998 14:46:05 -0700 (PDT)


On Tue, 19 May 1998, Pavel Machek wrote:
>
> On linux, any user may kill setuid program he ran with any signal. I
> think that this is dangerous:

Linux implements the strict POSIX requirements, as far as I know. There
isn't anything we can do to change this without breaking standards
compliance.

In order to get around getting killed by the user that started the binary,
a setuid binary needs to do something like

setuid(0);

in case it is root suid, and if it is not root suid then it can do
something like

uid = getuid();
setresuid(uid,uid,uid);

or similar (don't take my word for this, there are probably better ways to
do this, and the above might be broken - check with somebody else to make
sure).

Linus

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.rutgers.edu