Re: Linux 2.2.18pre21

From: Matthias Andree (matthias.andree@stud.uni-dortmund.de)
Date: Fri Nov 17 2000 - 06:34:01 EST


On Thu, 16 Nov 2000, H. Peter Anvin wrote:

> BUG: you *MUST* chdir() into the chroot jail before it does you any
> good at all!
>
> I usually recommend:

  #include <sysexits.h>
  /* for EX_NOUSER */

> mkdir("foo");
> chdir("foo");
> chroot(".");

add this:

  /* DO REPLACE 500 BY AN EXISTING USER ID */
  /* DO NOT REPLACE IT BY 0! */
  /* DO NOT USE OTHER FUNCTIONS THAN setuid() */
  if(setuid(500)) { _exit(EX_NOUSER); }

(For the records and search engines, most people should know that, but
to have it all in one mail.)
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