FreeBSD/Linux Kernel Cross Reference
sys/security/mac_seeotheruids/mac_seeotheruids.c

     /*-
      * Copyright (c) 1999-2002, 2007 Robert N. M. Watson
      * Copyright (c) 2001-2002 Networks Associates Technology, Inc.
      * Copyright (c) 2006 SPARTA, Inc.
      * All rights reserved.
      *
      * This software was developed by Robert Watson for the TrustedBSD Project.
      *
      * This software was developed for the FreeBSD Project in part by Network
     * Associates Laboratories, the Security Research Division of Network
     * Associates, Inc. under DARPA/SPAWAR contract N66001-01-C-8035 ("CBOSS"),
     * as part of the DARPA CHATS research program.
     *
     * This software was enhanced by SPARTA ISSO under SPAWAR contract
     * N66001-04-C-6019 ("SEFOS").
     *
     * Redistribution and use in source and binary forms, with or without
     * modification, are permitted provided that the following conditions
     * are met:
     * 1. Redistributions of source code must retain the above copyright
     *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     *
     * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
     * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
     * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     * SUCH DAMAGE.
     *
     * $FreeBSD$
     */
    
    /*
     * Developed by the TrustedBSD Project.
     *
     * Prevent processes owned by a particular uid from seeing various transient
     * kernel objects associated with other uids.
     */
    
    #include <sys/param.h>
    #include <sys/kernel.h>
    #include <sys/module.h>
    #include <sys/priv.h>
    #include <sys/proc.h>
    #include <sys/systm.h>
    #include <sys/socket.h>
    #include <sys/socketvar.h>
    #include <sys/sysctl.h>
    
    #include <net/route.h>
    #include <netinet/in.h>
    #include <netinet/in_pcb.h>
    
    #include <security/mac/mac_policy.h>
    
    SYSCTL_DECL(_security_mac);
    
    static SYSCTL_NODE(_security_mac, OID_AUTO, seeotheruids,
        CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
        "TrustedBSD mac_seeotheruids policy controls");
    
    static int      seeotheruids_enabled = 1;
    SYSCTL_INT(_security_mac_seeotheruids, OID_AUTO, enabled, CTLFLAG_RW,
        &seeotheruids_enabled, 0, "Enforce seeotheruids policy");
    
    /*
     * Exception: allow credentials to be aware of other credentials with the
     * same primary gid.
     */
    static int      primarygroup_enabled = 0;
    SYSCTL_INT(_security_mac_seeotheruids, OID_AUTO, primarygroup_enabled,
        CTLFLAG_RW, &primarygroup_enabled, 0, "Make an exception for credentials "
        "with the same real primary group id");
    
    /*
     * Exception: allow the root user to be aware of other credentials by virtue
     * of privilege.
     */
    static int      suser_privileged = 1;
    SYSCTL_INT(_security_mac_seeotheruids, OID_AUTO, suser_privileged,
        CTLFLAG_RW, &suser_privileged, 0, "Make an exception for superuser");
    
    /*
     * Exception: allow processes with a specific gid to be exempt from the
     * policy.  One sysctl enables this functionality; the other sets the
     * exempt gid.
     */
    static int      specificgid_enabled = 0;
    SYSCTL_INT(_security_mac_seeotheruids, OID_AUTO, specificgid_enabled,
        CTLFLAG_RW, &specificgid_enabled, 0, "Make an exception for credentials "
        "with a specific gid as their real primary group id or group set");
   
   static gid_t    specificgid = 0;
   SYSCTL_UINT(_security_mac_seeotheruids, OID_AUTO, specificgid, CTLFLAG_RW,
       &specificgid, 0, "Specific gid to be exempt from seeotheruids policy");
   
   static int
   seeotheruids_check(struct ucred *cr1, struct ucred *cr2)
   {
   
           if (!seeotheruids_enabled)
                   return (0);
   
           if (primarygroup_enabled) {
                   if (cr1->cr_rgid == cr2->cr_rgid)
                           return (0);
           }
   
           if (specificgid_enabled) {
                   if (cr1->cr_rgid == specificgid ||
                       groupmember(specificgid, cr1))
                           return (0);
           }
   
           if (cr1->cr_ruid == cr2->cr_ruid)
                   return (0);
   
           if (suser_privileged) {
                   if (priv_check_cred(cr1, PRIV_SEEOTHERUIDS) == 0)
                           return (0);
           }
   
           return (ESRCH);
   }
   
   static int
   seeotheruids_proc_check_debug(struct ucred *cred, struct proc *p)
   {
   
           return (seeotheruids_check(cred, p->p_ucred));
   }
   
   static int
   seeotheruids_proc_check_sched(struct ucred *cred, struct proc *p)
   {
   
           return (seeotheruids_check(cred, p->p_ucred));
   }
   
   static int
   seeotheruids_proc_check_signal(struct ucred *cred, struct proc *p,
       int signum)
   {
   
           return (seeotheruids_check(cred, p->p_ucred));
   }
   
   static int
   seeotheruids_cred_check_visible(struct ucred *cr1, struct ucred *cr2)
   {
   
           return (seeotheruids_check(cr1, cr2));
   }
   
   static int
   seeotheruids_inpcb_check_visible(struct ucred *cred, struct inpcb *inp,
       struct label *inplabel)
   {
   
           return (seeotheruids_check(cred, inp->inp_cred));
   }
   
   static int
   seeotheruids_socket_check_visible(struct ucred *cred, struct socket *so,
       struct label *solabel)
   {
   
           return (seeotheruids_check(cred, so->so_cred));
   }
   
   static struct mac_policy_ops seeotheruids_ops =
   {
           .mpo_proc_check_debug = seeotheruids_proc_check_debug,
           .mpo_proc_check_sched = seeotheruids_proc_check_sched,
           .mpo_proc_check_signal = seeotheruids_proc_check_signal,
           .mpo_cred_check_visible = seeotheruids_cred_check_visible,
           .mpo_inpcb_check_visible = seeotheruids_inpcb_check_visible,
           .mpo_socket_check_visible = seeotheruids_socket_check_visible,
   };
   
   MAC_POLICY_SET(&seeotheruids_ops, mac_seeotheruids,
       "TrustedBSD MAC/seeotheruids", MPC_LOADTIME_FLAG_UNLOADOK, NULL);

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