1 /* 2 * Copyright (c) 2021 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 #if (DEVELOPMENT || DEBUG) && !KASAN 30 31 #include <sys/sysctl.h> 32 #include <libkern/stack_protector.h> 33 34 __attribute__((noinline)) 35 static int 36 check_for_cookie(size_t len) 37 { 38 long buf[4]; 39 long *search = (long *)(void *)&buf[0]; 40 size_t n; 41 42 assert(len < sizeof(buf)); 43 assert(__stack_chk_guard != 0); 44 assert(((uintptr_t)search & (sizeof(long) - 1)) == 0); 45 46 /* force compiler to insert stack cookie check: */ 47 memset_s(buf, len, 0, len); 48 49 /* 32 x sizeof(long) should be plenty to find the cookie: */ 50 for (n = 0; n < 32; ++n) { 51 if (*(search++) == __stack_chk_guard) { 52 return 0; 53 } 54 } 55 56 return ESRCH; 57 } 58 59 static int 60 sysctl_run_stack_chk_tests SYSCTL_HANDLER_ARGS 61 { 62 #pragma unused(arg1, arg2, oidp) 63 64 unsigned int dummy = 0; 65 int error, changed = 0, kr; 66 error = sysctl_io_number(req, 0, sizeof(dummy), &dummy, &changed); 67 if (error || !changed) { 68 return error; 69 } 70 71 kr = check_for_cookie(3); 72 return kr; 73 } 74 75 SYSCTL_PROC(_kern, OID_AUTO, run_stack_chk_tests, 76 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_LOCKED | CTLFLAG_MASKED, 77 0, 0, sysctl_run_stack_chk_tests, "I", ""); 78 79 #endif /* (DEVELOPMENT || DEBUG) && !KASAN */ 80