1 /* 2 * Copyright (c) 2016-2020 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/backtrace.h> 30 #include <kern/kalloc.h> 31 #include <sys/errno.h> 32 #include <sys/sysctl.h> 33 #include <sys/systm.h> 34 35 #if DEVELOPMENT || DEBUG 36 37 /* 38 * Ignore -Wxnu-typed-allocators for this file, as it implements 39 * sysctls that are only available for DEVELOPMENT || DEBUG builds. 40 */ 41 __typed_allocators_ignore_push 42 43 #define MAX_BACKTRACE (128) 44 45 #define BACKTRACE_USER (0) 46 #define BACKTRACE_USER_RESUME (1) 47 static int backtrace_user_sysctl SYSCTL_HANDLER_ARGS; 48 49 #define BACKTRACE_KERN_TEST_PACK_UNPACK (0) 50 #define BACKTRACE_KERN_TEST_PACKED (1) 51 static int backtrace_kernel_sysctl SYSCTL_HANDLER_ARGS; 52 53 SYSCTL_NODE(_kern, OID_AUTO, backtrace, CTLFLAG_RW | CTLFLAG_LOCKED, 0, 54 "backtrace"); 55 56 SYSCTL_PROC(_kern_backtrace, OID_AUTO, user, 57 CTLFLAG_RW | CTLFLAG_LOCKED, (void *)BACKTRACE_USER, 58 sizeof(uint64_t), backtrace_user_sysctl, "O", 59 "take user backtrace of current thread"); 60 61 SYSCTL_PROC(_kern_backtrace, OID_AUTO, kernel_tests, 62 CTLFLAG_RW | CTLFLAG_LOCKED, (void *)BACKTRACE_USER, 63 sizeof(uint64_t), backtrace_kernel_sysctl, "O", 64 "take user backtrace of current thread"); 65 66 static int 67 backtrace_kernel_sysctl SYSCTL_HANDLER_ARGS 68 { 69 unsigned int scenario = (unsigned int)req->newlen; 70 uintptr_t *bt = NULL; 71 uint8_t *packed_bt = NULL; 72 uintptr_t *unpacked_bt = NULL; 73 unsigned int bt_len = 0; 74 size_t bt_size = 0; 75 errno_t error = 0; 76 77 bt_len = 24; 78 bt_size = sizeof(bt[0]) * bt_len; 79 bt = kalloc_data(bt_size, Z_WAITOK | Z_ZERO); 80 packed_bt = kalloc_data(bt_size, Z_WAITOK | Z_ZERO); 81 unpacked_bt = kalloc_data(bt_size, Z_WAITOK | Z_ZERO); 82 if (!bt || !packed_bt || !unpacked_bt) { 83 error = ENOBUFS; 84 goto out; 85 } 86 backtrace_info_t info = BTI_NONE; 87 unsigned int len = backtrace(bt, bt_len, NULL, &info); 88 backtrace_info_t packed_info = BTI_NONE; 89 size_t packed_size = 0; 90 if (scenario == BACKTRACE_KERN_TEST_PACK_UNPACK) { 91 packed_size = backtrace_pack(BTP_KERN_OFFSET_32, packed_bt, bt_size, 92 bt, len); 93 } else { 94 packed_size = backtrace_packed(BTP_KERN_OFFSET_32, packed_bt, bt_size, 95 NULL, &packed_info); 96 } 97 unsigned int unpacked_len = backtrace_unpack(BTP_KERN_OFFSET_32, 98 unpacked_bt, bt_len, packed_bt, packed_size); 99 if (unpacked_len != len) { 100 printf("backtrace_tests: length %u != %u unpacked\n", len, 101 unpacked_len); 102 error = ERANGE; 103 goto out; 104 } 105 for (unsigned int i = 0; i < len; i++) { 106 if (unpacked_bt[i] != bt[i]) { 107 printf("backtrace_tests: bad address %u: 0x%lx != 0x%lx unpacked", 108 i, bt[i], unpacked_bt[i]); 109 error = EINVAL; 110 } 111 } 112 113 out: 114 if (bt) { 115 kfree_data(bt, bt_size); 116 } 117 if (packed_bt) { 118 kfree_data(packed_bt, bt_size); 119 } 120 if (unpacked_bt) { 121 kfree_data(unpacked_bt, bt_size); 122 } 123 return error; 124 } 125 126 static int 127 backtrace_user_sysctl SYSCTL_HANDLER_ARGS 128 { 129 #pragma unused(oidp, arg1, arg2) 130 unsigned int scenario = (unsigned int)req->newlen; 131 uintptr_t *bt = NULL; 132 unsigned int bt_len = 0, bt_filled = 0, bt_space = 0; 133 size_t bt_size = 0; 134 errno_t error = 0; 135 136 bool user_scenario = scenario == BACKTRACE_USER; 137 bool resume_scenario = scenario == BACKTRACE_USER_RESUME; 138 if (!user_scenario && !resume_scenario) { 139 return ENOTSUP; 140 } 141 142 if (req->oldptr == USER_ADDR_NULL || req->oldlen == 0) { 143 return EFAULT; 144 } 145 146 bt_len = req->oldlen > MAX_BACKTRACE ? MAX_BACKTRACE : 147 (unsigned int)req->oldlen; 148 bt_size = sizeof(bt[0]) * bt_len; 149 bt = kalloc_data(bt_size, Z_WAITOK | Z_ZERO); 150 if (!bt) { 151 return ENOBUFS; 152 } 153 bt_space = resume_scenario ? bt_len / 2 : bt_len; 154 struct backtrace_user_info btinfo = BTUINFO_INIT; 155 bt_filled = backtrace_user(bt, bt_space, NULL, &btinfo); 156 error = btinfo.btui_error; 157 if (error != 0) { 158 goto out; 159 } 160 if (resume_scenario) { 161 if (!(btinfo.btui_info & BTI_TRUNCATED)) { 162 error = ENOSPC; 163 goto out; 164 } 165 struct backtrace_control ctl = { 166 .btc_frame_addr = btinfo.btui_next_frame_addr, 167 }; 168 btinfo = BTUINFO_INIT; 169 unsigned int bt_more = backtrace_user(bt + bt_filled, bt_space, &ctl, 170 &btinfo); 171 error = btinfo.btui_error; 172 if (error != 0) { 173 goto out; 174 } 175 bt_filled += bt_more; 176 } 177 bt_filled = min(bt_filled, bt_len); 178 if (btinfo.btui_async_frame_addr != 0 && 179 btinfo.btui_async_start_index != 0) { 180 // Put the async call stack inline after the real call stack. 181 unsigned int start_index = btinfo.btui_async_start_index; 182 uintptr_t frame_addr = btinfo.btui_async_frame_addr; 183 unsigned int bt_left = bt_len - start_index; 184 struct backtrace_control ctl = { .btc_frame_addr = frame_addr, }; 185 btinfo = BTUINFO_INIT; 186 unsigned int async_filled = backtrace_user(bt + start_index, bt_left, 187 &ctl, &btinfo); 188 error = btinfo.btui_error; 189 if (error != 0) { 190 goto out; 191 } 192 bt_filled = min(start_index + async_filled, bt_len); 193 } 194 195 error = copyout(bt, req->oldptr, sizeof(bt[0]) * bt_filled); 196 if (error) { 197 goto out; 198 } 199 req->oldidx = bt_filled; 200 201 out: 202 kfree_data(bt, bt_size); 203 return error; 204 } 205 206 __typed_allocators_ignore_pop 207 208 #endif /* DEVELOPMENT || DEBUG */ 209