Re: A few thoughts..

From: Peter Jeremy (PeterJeremy_at_optushome.com.au)
Date: 03/30/05

  • Next message: David Leimbach: "Re: organization" 
    Date: Thu, 31 Mar 2005 04:42:25 +1000
To: "H. S." <security@revolutionsp.com>

    On Wed, 2005-Mar-30 11:06:53 -0600, H. S. wrote:
    >As I stated previously, I'm not much of a C programmer, but I can do some
    >coding. I've been thinking into changing the core of the system a bit to
    >return errors if some information is accessed by a normal user.

    Wouldn't making /sbin and /usr/sbin mode 750 be enough?

    > I'd like
    >to know if getuid() would work that deep in the system?

    In general, system calls can't be used within the kernel. The uid and
    gid could be determined by directly dereferencing curproc or the
    thread pointer passed around in most kernel internal calls. Note that
    the only checks the (non-MAC) kernel currently does is "root" or
    "not-root" using suser(9) (apart from the checks in kill(2)).
    Restrictions for non-root users are implemented using file
    permissions.

    > And how can I register sysctl mibs in the kernel ?

    Look at sysctl(3), /sys/sys/sysctl.h and (eg) /sys/kern/subr_msgbuf.c 

    -- 
Peter Jeremy
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