bsd/kern/kern_csr.c

   1 /*
   2  * Copyright (c) 2014 Apple Inc. All rights reserved.
   3  *
   4  * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. The rights granted to you under the License
  10  * may not be used to create, or enable the creation or redistribution of,
  11  * unlawful or unlicensed copies of an Apple operating system, or to
  12  * circumvent, violate, or enable the circumvention or violation of, any
  13  * terms of an Apple operating system software license agreement.
  14  *
  15  * Please obtain a copy of the License at
  16  * http://www.opensource.apple.com/apsl/ and read it before using this file.
  17  *
  18  * The Original Code and all software distributed under the License are
  19  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  20  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  21  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  22  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  23  * Please see the License for the specific language governing rights and
  24  * limitations under the License.
  25  *
  26  * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
  27  */
  28
  29 #include <pexpert/pexpert.h>
  30 #include <sys/csr.h>
  31 #include <sys/errno.h>
  32 #include <sys/sysproto.h>
  33 #include <sys/systm.h>
  34 #include <sys/types.h>
  35
  36 /* allow everything by default? */
  37 /* XXX: set this to 0 later: <rdar://problem/16040413> */
  38 static int csr_allow_all = 1;
  39
  40 /* allow everything if CSR_ALLOW_APPLE_INTERNAL is set */
  41 static int csr_allow_internal = 1;
  42
  43 /* Current boot-arg policy:
  44  * rootless=0
  45  *    csr_allow_all = 1
  46  * rootless=1
  47  *    csr_allow_all = 0
  48  *    csr_allow_internal = 0
  49  *
  50  * After <rdar://problem/16239861>:
  51  * rootless=0
  52  *    no effect
  53  * rootless=1
  54  *    csr_allow_internal = 0
  55  *
  56  * Enforcement policy:
  57  * ===============================
  58  *            | csr_allow_internal
  59  *            |   0         1
  60  * ===============================
  61  *   csr_   0 | always   customer
  62  *  allow_    |
  63  *   all    1 | never    never
  64  * ===============================
  65  * NB: "customer" means enforce when
  66  * CSR_ALLOW_APPLE_INTERNAL not set */
  67
  68 void
  69 csr_init(void)
  70 {
  71         boot_args *args = (boot_args *)PE_state.bootArgs;
  72         if (args->flags & kBootArgsFlagCSRBoot) {
  73                 /* special booter; allow everything */
  74                 csr_allow_all = 1;
  75         }
  76
  77         int rootless_boot_arg;
  78         if (PE_parse_boot_argn("rootless", &rootless_boot_arg, sizeof(rootless_boot_arg))) {
  79                 /* XXX: set csr_allow_all to boot arg value for now
  80                  * (to be removed by <rdar://problem/16239861>) */
  81                 csr_allow_all = !rootless_boot_arg;
  82                 /* if rootless=1, do not allow everything when CSR_ALLOW_APPLE_INTERNAL is set */
  83                 csr_allow_internal &= !rootless_boot_arg;
  84         }
  85 }
  86
  87 int
  88 csrctl(__unused proc_t p, struct csrctl_args *uap, __unused int32_t *retval)
  89 {
  90         int error = 0;
  91
  92         if (uap->useraddr == 0)
  93                 return EINVAL;
  94         if (uap->usersize != sizeof(csr_config_t))
  95                 return EINVAL;
  96
  97         switch (uap->op) {
  98                 case CSR_OP_CHECK:
  99                 {
 100                         csr_config_t mask;
 101                         error = copyin(uap->useraddr, &mask, sizeof(csr_config_t));
 102
 103                         if (error)
 104                                 return error;
 105
 106                         error = csr_check(mask);
 107                         break;
 108                 }
 109
 110                 case CSR_OP_GET_ACTIVE_CONFIG:
 111                 case CSR_OP_GET_PENDING_CONFIG: /* fall through */
 112                 {
 113                         csr_config_t config = 0;
 114                         if (uap->op == CSR_OP_GET_ACTIVE_CONFIG)
 115                                 error = csr_get_active_config(&config);
 116                         else
 117                                 error = csr_get_pending_config(&config);
 118
 119                         if (error)
 120                                 return error;
 121
 122                         error = copyout(&config, uap->useraddr, sizeof(csr_config_t));
 123                         break;
 124                 }
 125
 126                 default:
 127                         error = EINVAL;
 128                         break;
 129         }
 130
 131         return error;
 132 }
 133
 134 int
 135 csr_get_active_config(csr_config_t *config)
 136 {
 137         boot_args *args = (boot_args *)PE_state.bootArgs;
 138         if (args->flags & kBootArgsFlagCSRActiveConfig) {
 139                 *config = args->csrActiveConfig & CSR_VALID_FLAGS;
 140         } else {
 141                 /* XXX: change to 0 when <rdar://problem/16239698> is in the build */
 142                 *config = CSR_ALLOW_APPLE_INTERNAL;
 143         }
 144
 145         return 0;
 146 }
 147
 148 int
 149 csr_get_pending_config(csr_config_t *config)
 150 {
 151         boot_args *args = (boot_args *)PE_state.bootArgs;
 152         if (args->flags & kBootArgsFlagCSRPendingConfig) {
 153                 *config = args->csrPendingConfig & CSR_VALID_FLAGS;
 154                 return 0;
 155         } else {
 156                 return ENOENT;
 157         }
 158 }
 159
 160 int
 161 csr_check(csr_config_t mask)
 162 {
 163         if (csr_allow_all) {
 164                 return 0;
 165         }
 166
 167         csr_config_t config;
 168         int error = csr_get_active_config(&config);
 169         if (error) {
 170                 return error;
 171         }
 172
 173         if (csr_allow_internal && (config & CSR_ALLOW_APPLE_INTERNAL)) {
 174                 return 0;
 175         }
 176
 177         if (mask == 0) {
 178                 /* pass 0 to check if Rootless enforcement is active */
 179                 return -1;
 180         }
 181
 182         error = (config & mask) ? 0 : EPERM;
 183         return error;
 184 }
 185
 186 void
 187 csr_set_allow_all(int value)
 188 {
 189         csr_allow_all = !!value; // force value to 0 or 1
 190 }