> That is a valid concern, but the code doesn't actually prevent this. I
> just tried
>
> chmod u+s postgres
> su -
> postmaster -D ...
>
> Then loaded the function
>
> #include <postgres.h>
>
> int32 touch(int32 a) {
> if (setuid(0) == -1)
> elog(ERROR, "setuid: %m");
> elog(DEBUG, "getuid = %d, geteuid = %d", getuid(), geteuid());
> system("touch /tmp/foofile");
> setuid(500); /* my own */
> return a + 1;
> }
>
> and the output was
>
> DEBUG: getuid = 0, geteuid = 0
>
> and I got a file /tmp/foofile owned by root.
>
> ISTM that the best way to prevent this exploit would be to check for both
> geteuid() == 0 and getuid() == 0 in main.c.
Peter, can you check your setuid manual page. Is there a mention of
special handling of saved-uid for root? I don't have it here on BSD/OS
but have heard of some os's that treat setuid differently for root.
--
Bruce Momjian | http://candle.pha.pa.us
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