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 /* enable enforcement by default */
  37 static int csr_allow_all = 0;
  38
  39 void
  40 csr_init(void)
  41 {
  42         boot_args *args = (boot_args *)PE_state.bootArgs;
  43         if (args->flags & kBootArgsFlagCSRBoot) {
  44                 /* special booter; allow everything */
  45                 csr_allow_all = 1;
  46         }
  47 }
  48
  49 int
  50 csr_get_active_config(csr_config_t *config)
  51 {
  52         boot_args *args = (boot_args *)PE_state.bootArgs;
  53         if (args->flags & kBootArgsFlagCSRActiveConfig) {
  54                 *config = args->csrActiveConfig & CSR_VALID_FLAGS;
  55         } else {
  56                 *config = 0;
  57         }
  58
  59         return 0;
  60 }
  61
  62 int
  63 csr_check(csr_config_t mask)
  64 {
  65         boot_args *args = (boot_args *)PE_state.bootArgs;
  66         if (mask & CSR_ALLOW_DEVICE_CONFIGURATION)
  67                 return (args->flags & kBootArgsFlagCSRConfigMode) ? 0 : EPERM;
  68
  69         csr_config_t config;
  70         int ret = csr_get_active_config(&config);
  71         if (ret) {
  72                 return ret;
  73         }
  74
  75         ret = (config & mask) ? 0 : EPERM;
  76         if (ret == EPERM) {
  77                 // Override the return value if booted from the BaseSystem and the mask does not contain any flag that should always be enforced.
  78                 if (csr_allow_all && (mask & CSR_ALWAYS_ENFORCED_FLAGS) == 0)
  79                         ret = 0;
  80         }
  81
  82         return ret;
  83 }
  84
  85 /*
  86  * Syscall stubs
  87  */
  88
  89 int syscall_csr_check(struct csrctl_args *args);
  90 int syscall_csr_get_active_config(struct csrctl_args *args);
  91
  92
  93 int
  94 syscall_csr_check(struct csrctl_args *args)
  95 {
  96         csr_config_t mask = 0;
  97         int error = 0;
  98
  99         if (args->useraddr == 0 || args->usersize != sizeof(mask))
 100                 return EINVAL;
 101
 102         error = copyin(args->useraddr, &mask, sizeof(mask));
 103         if (error)
 104                 return error;
 105
 106         return csr_check(mask);
 107 }
 108
 109 int
 110 syscall_csr_get_active_config(struct csrctl_args *args)
 111 {
 112         csr_config_t config = 0;
 113         int error = 0;
 114
 115         if (args->useraddr == 0 || args->usersize != sizeof(config))
 116                 return EINVAL;
 117
 118         error = csr_get_active_config(&config);
 119         if (error)
 120                 return error;
 121
 122         return copyout(&config, args->useraddr, sizeof(config));
 123 }
 124
 125 /*
 126  * Syscall entrypoint
 127  */
 128
 129 int
 130 csrctl(__unused proc_t p, struct csrctl_args *args, __unused int32_t *retval)
 131 {
 132         switch (args->op) {
 133                 case CSR_SYSCALL_CHECK:
 134                         return syscall_csr_check(args);
 135                 case CSR_SYSCALL_GET_ACTIVE_CONFIG:
 136                         return syscall_csr_get_active_config(args);
 137                 default:
 138                         return ENOSYS;
 139         }
 140 }