osfmk/prng/entropy.c

   1 /*
   2  * Copyright (c) 2019 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 <kern/zalloc.h>
  30 #include <pexpert/pexpert.h>
  31 #include <prng/entropy.h>
  32 #include <crypto/entropy/diag_entropy_sysctl.h>
  33 #include <machine/machine_routines.h>
  34
  35 // Use a static buffer when the entropy collection boot arg is not present and before the
  36 // RNG has been initialized.
  37 static uint32_t entropy_buffer[ENTROPY_BUFFER_SIZE];
  38
  39 entropy_data_t EntropyData = {
  40         .sample_count = 0,
  41         .buffer = entropy_buffer,
  42         .buffer_size = ENTROPY_BUFFER_SIZE,
  43         .buffer_index_mask = ENTROPY_BUFFER_SIZE - 1,
  44         .ror_mask = -1
  45 };
  46
  47 void
  48 entropy_buffer_init(void)
  49 {
  50         uint32_t ebsz = 0;
  51         uint32_t *bp;
  52
  53         if (PE_parse_boot_argn("ebsz", &ebsz, sizeof(ebsz))) {
  54                 if (((ebsz & (ebsz - 1)) != 0) || (ebsz < 32)) {
  55                         panic("entropy_buffer_init: entropy buffer size must be a power of 2 and >= 32\n");
  56                 }
  57
  58                 register_entropy_sysctl();
  59
  60                 bp = zalloc_permanent(sizeof(uint32_t) * ebsz, ZALIGN(uint32_t));
  61
  62                 boolean_t interrupt_state = ml_set_interrupts_enabled(FALSE);
  63                 EntropyData.buffer = bp;
  64                 EntropyData.sample_count = 0;
  65                 EntropyData.buffer_size = sizeof(uint32_t) * ebsz;
  66                 EntropyData.buffer_index_mask = ebsz - 1;
  67                 EntropyData.ror_mask = 0;
  68                 ml_set_interrupts_enabled(interrupt_state);
  69         }
  70 }