The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


[ source navigation ] [ diff markup ] [ identifier search ] [ freetext search ] [ file search ] [ list types ] [ track identifier ]

FreeBSD/Linux Kernel Cross Reference
sys/kern/kern_priv.c

Version: -  FREEBSD  -  FREEBSD-12-STABLE  -  FREEBSD-12-0  -  FREEBSD-11-STABLE  -  FREEBSD-11-2  -  FREEBSD-11-1  -  FREEBSD-11-0  -  FREEBSD-10-STABLE  -  FREEBSD-10-4  -  FREEBSD-10-3  -  FREEBSD-10-2  -  FREEBSD-10-1  -  FREEBSD-10-0  -  FREEBSD-9-STABLE  -  FREEBSD-9-3  -  FREEBSD-9-2  -  FREEBSD-9-1  -  FREEBSD-9-0  -  FREEBSD-8-STABLE  -  FREEBSD-8-4  -  FREEBSD-8-3  -  FREEBSD-8-2  -  FREEBSD-8-1  -  FREEBSD-8-0  -  FREEBSD-7-STABLE  -  FREEBSD-7-4  -  FREEBSD-7-3  -  FREEBSD-7-2  -  FREEBSD-7-1  -  FREEBSD-7-0  -  FREEBSD-6-STABLE  -  FREEBSD-6-4  -  FREEBSD-6-3  -  FREEBSD-6-2  -  FREEBSD-6-1  -  FREEBSD-6-0  -  FREEBSD-5-STABLE  -  FREEBSD-5-5  -  FREEBSD-5-4  -  FREEBSD-5-3  -  FREEBSD-5-2  -  FREEBSD-5-1  -  FREEBSD-5-0  -  FREEBSD-4-STABLE  -  FREEBSD-3-STABLE  -  FREEBSD22  -  linux-2.6  -  linux-2.4.22  -  MK83  -  MK84  -  PLAN9  -  DFBSD  -  NETBSD  -  NETBSD5  -  NETBSD4  -  NETBSD3  -  NETBSD20  -  OPENBSD  -  xnu-517  -  xnu-792  -  xnu-792.6.70  -  xnu-1228  -  xnu-1456.1.26  -  xnu-1699.24.8  -  xnu-2050.18.24  -  OPENSOLARIS  -  minix-3-1-1 
SearchContext: -  none  -  3  -  10 

    1 /*-
    2  * Copyright (c) 2006 nCircle Network Security, Inc.
    3  * Copyright (c) 2009 Robert N. M. Watson
    4  * All rights reserved.
    5  *
    6  * This software was developed by Robert N. M. Watson for the TrustedBSD
    7  * Project under contract to nCircle Network Security, Inc.
    8  *
    9  * Redistribution and use in source and binary forms, with or without
   10  * modification, are permitted provided that the following conditions
   11  * are met:
   12  * 1. Redistributions of source code must retain the above copyright
   13  *    notice, this list of conditions and the following disclaimer.
   14  * 2. Redistributions in binary form must reproduce the above copyright
   15  *    notice, this list of conditions and the following disclaimer in the
   16  *    documentation and/or other materials provided with the distribution.
   17  *
   18  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   19  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   20  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   21  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR, NCIRCLE NETWORK SECURITY,
   22  * INC., OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
   23  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
   24  * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
   25  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
   26  * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
   27  * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
   28  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   29  */
   30 
   31 #include "opt_kdtrace.h"
   32 
   33 #include <sys/cdefs.h>
   34 __FBSDID("$FreeBSD: stable/10/sys/kern/kern_priv.c 260817 2014-01-17 10:58:59Z avg $");
   35 
   36 #include <sys/param.h>
   37 #include <sys/jail.h>
   38 #include <sys/kernel.h>
   39 #include <sys/priv.h>
   40 #include <sys/proc.h>
   41 #include <sys/sdt.h>
   42 #include <sys/sysctl.h>
   43 #include <sys/systm.h>
   44 
   45 #include <security/mac/mac_framework.h>
   46 
   47 /*
   48  * `suser_enabled' (which can be set by the security.bsd.suser_enabled
   49  * sysctl) determines whether the system 'super-user' policy is in effect.  If
   50  * it is nonzero, an effective uid of 0 connotes special privilege,
   51  * overriding many mandatory and discretionary protections.  If it is zero,
   52  * uid 0 is offered no special privilege in the kernel security policy.
   53  * Setting it to zero may seriously impact the functionality of many existing
   54  * userland programs, and should not be done without careful consideration of
   55  * the consequences.
   56  */
   57 static int      suser_enabled = 1;
   58 SYSCTL_INT(_security_bsd, OID_AUTO, suser_enabled, CTLFLAG_RW,
   59     &suser_enabled, 0, "processes with uid 0 have privilege");
   60 TUNABLE_INT("security.bsd.suser_enabled", &suser_enabled);
   61 
   62 static int      unprivileged_mlock = 1;
   63 SYSCTL_INT(_security_bsd, OID_AUTO, unprivileged_mlock, CTLFLAG_RW|CTLFLAG_TUN,
   64     &unprivileged_mlock, 0, "Allow non-root users to call mlock(2)");
   65 TUNABLE_INT("security.bsd.unprivileged_mlock", &unprivileged_mlock);
   66 
   67 SDT_PROVIDER_DEFINE(priv);
   68 SDT_PROBE_DEFINE1(priv, kernel, priv_check, priv__ok, "int");
   69 SDT_PROBE_DEFINE1(priv, kernel, priv_check, priv__err, "int");
   70 
   71 /*
   72  * Check a credential for privilege.  Lots of good reasons to deny privilege;
   73  * only a few to grant it.
   74  */
   75 int
   76 priv_check_cred(struct ucred *cred, int priv, int flags)
   77 {
   78         int error;
   79 
   80         KASSERT(PRIV_VALID(priv), ("priv_check_cred: invalid privilege %d",
   81             priv));
   82 
   83         /*
   84          * We first evaluate policies that may deny the granting of
   85          * privilege unilaterally.
   86          */
   87 #ifdef MAC
   88         error = mac_priv_check(cred, priv);
   89         if (error)
   90                 goto out;
   91 #endif
   92 
   93         /*
   94          * Jail policy will restrict certain privileges that may otherwise be
   95          * be granted.
   96          */
   97         error = prison_priv_check(cred, priv);
   98         if (error)
   99                 goto out;
  100 
  101         if (unprivileged_mlock) {
  102                 /*
  103                  * Allow unprivileged users to call mlock(2)/munlock(2) and
  104                  * mlockall(2)/munlockall(2).
  105                  */
  106                 switch (priv) {
  107                 case PRIV_VM_MLOCK:
  108                 case PRIV_VM_MUNLOCK:
  109                         error = 0;
  110                         goto out;
  111                 }
  112         }
  113 
  114         /*
  115          * Having determined if privilege is restricted by various policies,
  116          * now determine if privilege is granted.  At this point, any policy
  117          * may grant privilege.  For now, we allow short-circuit boolean
  118          * evaluation, so may not call all policies.  Perhaps we should.
  119          *
  120          * Superuser policy grants privilege based on the effective (or in
  121          * the case of specific privileges, real) uid being 0.  We allow the
  122          * superuser policy to be globally disabled, although this is
  123          * currenty of limited utility.
  124          */
  125         if (suser_enabled) {
  126                 switch (priv) {
  127                 case PRIV_MAXFILES:
  128                 case PRIV_MAXPROC:
  129                 case PRIV_PROC_LIMIT:
  130                         if (cred->cr_ruid == 0) {
  131                                 error = 0;
  132                                 goto out;
  133                         }
  134                         break;
  135                 default:
  136                         if (cred->cr_uid == 0) {
  137                                 error = 0;
  138                                 goto out;
  139                         }
  140                         break;
  141                 }
  142         }
  143 
  144         /*
  145          * Writes to kernel/physical memory are a typical root-only operation,
  146          * but non-root users are expected to be able to read it (provided they
  147          * have permission to access /dev/[k]mem).
  148          */
  149         if (priv == PRIV_KMEM_READ) {
  150                 error = 0;
  151                 goto out;
  152         }
  153 
  154         /*
  155          * Now check with MAC, if enabled, to see if a policy module grants
  156          * privilege.
  157          */
  158 #ifdef MAC
  159         if (mac_priv_grant(cred, priv) == 0) {
  160                 error = 0;
  161                 goto out;
  162         }
  163 #endif
  164 
  165         /*
  166          * The default is deny, so if no policies have granted it, reject
  167          * with a privilege error here.
  168          */
  169         error = EPERM;
  170 out:
  171         if (error)
  172                 SDT_PROBE1(priv, kernel, priv_check, priv__err, priv);
  173         else
  174                 SDT_PROBE1(priv, kernel, priv_check, priv__ok, priv);
  175         return (error);
  176 }
  177 
  178 int
  179 priv_check(struct thread *td, int priv)
  180 {
  181 
  182         KASSERT(td == curthread, ("priv_check: td != curthread"));
  183 
  184         return (priv_check_cred(td->td_ucred, priv, 0));
  185 }

Cache object: 5cde70b14c969e3df5916a63917bf8f1


[ source navigation ] [ diff markup ] [ identifier search ] [ freetext search ] [ file search ] [ list types ] [ track identifier ]


This page is part of the FreeBSD/Linux Linux Kernel Cross-Reference, and was automatically generated using a modified version of the LXR engine.