1//===-- asan_flags.cpp ------------------------------------------*- C++ -*-===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This file is a part of AddressSanitizer, an address sanity checker.
10//
11// ASan flag parsing logic.
12//===----------------------------------------------------------------------===//
13
14#include "asan_flags.h"
15
16#include "asan_activation.h"
17#include "asan_interface_internal.h"
18#include "asan_stack.h"
19#include "lsan/lsan_common.h"
20#include "sanitizer_common/sanitizer_common.h"
21#include "sanitizer_common/sanitizer_flag_parser.h"
22#include "sanitizer_common/sanitizer_flags.h"
23#include "sanitizer_common/sanitizer_win_interception.h"
24#include "ubsan/ubsan_flags.h"
25#include "ubsan/ubsan_platform.h"
26
27namespace __asan {
28
29Flags asan_flags_dont_use_directly; // use via flags().
30
31static const char *MaybeUseAsanDefaultOptionsCompileDefinition() {
32#ifdef ASAN_DEFAULT_OPTIONS
33 return SANITIZER_STRINGIFY(ASAN_DEFAULT_OPTIONS);
34#else
35 return "";
36#endif
37}
38
39void Flags::SetDefaults() {
40#define ASAN_FLAG(Type, Name, DefaultValue, Description) Name = DefaultValue;
41#include "asan_flags.inc"
42#undef ASAN_FLAG
43}
44
45static void RegisterAsanFlags(FlagParser *parser, Flags *f) {
46#define ASAN_FLAG(Type, Name, DefaultValue, Description) \
47 RegisterFlag(parser, #Name, Description, &f->Name);
48#include "asan_flags.inc"
49#undef ASAN_FLAG
50}
51
52static void DisplayHelpMessages(FlagParser *parser) {
53 // TODO(eugenis): dump all flags at verbosity>=2?
54 if (Verbosity()) {
55 ReportUnrecognizedFlags();
56 }
57
58 if (common_flags()->help) {
59 parser->PrintFlagDescriptions();
60 }
61}
62
63static void InitializeDefaultFlags() {
64 Flags *f = flags();
65 FlagParser asan_parser;
66
67 // Set the default values and prepare for parsing ASan and common flags.
68 SetCommonFlagsDefaults();
69 {
70 CommonFlags cf;
71 cf.CopyFrom(other: *common_flags());
72 cf.detect_leaks = cf.detect_leaks && CAN_SANITIZE_LEAKS;
73 cf.external_symbolizer_path = GetEnv(name: "ASAN_SYMBOLIZER_PATH");
74 cf.malloc_context_size = kDefaultMallocContextSize;
75 cf.intercept_tls_get_addr = true;
76 cf.exitcode = 1;
77 OverrideCommonFlags(cf);
78 }
79 f->SetDefaults();
80
81 RegisterAsanFlags(parser: &asan_parser, f);
82 RegisterCommonFlags(parser: &asan_parser);
83
84 // Set the default values and prepare for parsing LSan and UBSan flags
85 // (which can also overwrite common flags).
86#if CAN_SANITIZE_LEAKS
87 __lsan::Flags *lf = __lsan::flags();
88 lf->SetDefaults();
89
90 FlagParser lsan_parser;
91 __lsan::RegisterLsanFlags(parser: &lsan_parser, f: lf);
92 RegisterCommonFlags(parser: &lsan_parser);
93#endif
94
95#if CAN_SANITIZE_UB
96 __ubsan::Flags *uf = __ubsan::flags();
97 uf->SetDefaults();
98
99 FlagParser ubsan_parser;
100 __ubsan::RegisterUbsanFlags(parser: &ubsan_parser, f: uf);
101 RegisterCommonFlags(parser: &ubsan_parser);
102#endif
103
104 if (SANITIZER_APPLE) {
105 // Support macOS MallocScribble and MallocPreScribble:
106 // <https://developer.apple.com/library/content/documentation/Performance/
107 // Conceptual/ManagingMemory/Articles/MallocDebug.html>
108 if (GetEnv(name: "MallocScribble")) {
109 f->max_free_fill_size = 0x1000;
110 }
111 if (GetEnv(name: "MallocPreScribble")) {
112 f->malloc_fill_byte = 0xaa;
113 }
114 }
115
116 // Override from ASan compile definition.
117 const char *asan_compile_def = MaybeUseAsanDefaultOptionsCompileDefinition();
118 asan_parser.ParseString(s: asan_compile_def);
119
120 // Override from user-specified string.
121 const char *asan_default_options = __asan_default_options();
122 asan_parser.ParseString(s: asan_default_options);
123#if CAN_SANITIZE_UB
124 const char *ubsan_default_options = __ubsan_default_options();
125 ubsan_parser.ParseString(s: ubsan_default_options);
126#endif
127#if CAN_SANITIZE_LEAKS
128 const char *lsan_default_options = __lsan_default_options();
129 lsan_parser.ParseString(s: lsan_default_options);
130#endif
131
132 // Override from command line.
133 asan_parser.ParseStringFromEnv(env_name: "ASAN_OPTIONS");
134#if CAN_SANITIZE_LEAKS
135 lsan_parser.ParseStringFromEnv(env_name: "LSAN_OPTIONS");
136#endif
137#if CAN_SANITIZE_UB
138 ubsan_parser.ParseStringFromEnv(env_name: "UBSAN_OPTIONS");
139#endif
140
141 InitializeCommonFlags();
142
143 // TODO(samsonov): print all of the flags (ASan, LSan, common).
144 DisplayHelpMessages(parser: &asan_parser);
145}
146
147static void ProcessFlags() {
148 Flags *f = flags();
149
150 // Flag validation:
151 if (!CAN_SANITIZE_LEAKS && common_flags()->detect_leaks) {
152 Report(format: "%s: detect_leaks is not supported on this platform.\n",
153 SanitizerToolName);
154 Die();
155 }
156 // Ensure that redzone is at least ASAN_SHADOW_GRANULARITY.
157 if (f->redzone < (int)ASAN_SHADOW_GRANULARITY)
158 f->redzone = ASAN_SHADOW_GRANULARITY;
159 // Make "strict_init_order" imply "check_initialization_order".
160 // TODO(samsonov): Use a single runtime flag for an init-order checker.
161 if (f->strict_init_order) {
162 f->check_initialization_order = true;
163 }
164 CHECK_LE((uptr)common_flags()->malloc_context_size, kStackTraceMax);
165 CHECK_LE(f->min_uar_stack_size_log, f->max_uar_stack_size_log);
166 CHECK_GE(f->redzone, 16);
167 CHECK_GE(f->max_redzone, f->redzone);
168 CHECK_LE(f->max_redzone, 2048);
169 CHECK(IsPowerOfTwo(f->redzone));
170 CHECK(IsPowerOfTwo(f->max_redzone));
171
172 // quarantine_size is deprecated but we still honor it.
173 // quarantine_size can not be used together with quarantine_size_mb.
174 if (f->quarantine_size >= 0 && f->quarantine_size_mb >= 0) {
175 Report(format: "%s: please use either 'quarantine_size' (deprecated) or "
176 "quarantine_size_mb, but not both\n", SanitizerToolName);
177 Die();
178 }
179 if (f->quarantine_size >= 0)
180 f->quarantine_size_mb = f->quarantine_size >> 20;
181 if (f->quarantine_size_mb < 0) {
182 const int kDefaultQuarantineSizeMb =
183 (ASAN_LOW_MEMORY) ? 1UL << 4 : 1UL << 8;
184 f->quarantine_size_mb = kDefaultQuarantineSizeMb;
185 }
186 if (f->thread_local_quarantine_size_kb < 0) {
187 const u32 kDefaultThreadLocalQuarantineSizeKb =
188 // It is not advised to go lower than 64Kb, otherwise quarantine batches
189 // pushed from thread local quarantine to global one will create too
190 // much overhead. One quarantine batch size is 8Kb and it holds up to
191 // 1021 chunk, which amounts to 1/8 memory overhead per batch when
192 // thread local quarantine is set to 64Kb.
193 (ASAN_LOW_MEMORY) ? 1 << 6 : FIRST_32_SECOND_64(1 << 8, 1 << 10);
194 f->thread_local_quarantine_size_kb = kDefaultThreadLocalQuarantineSizeKb;
195 }
196 if (f->thread_local_quarantine_size_kb == 0 && f->quarantine_size_mb > 0) {
197 Report(format: "%s: thread_local_quarantine_size_kb can be set to 0 only when "
198 "quarantine_size_mb is set to 0\n", SanitizerToolName);
199 Die();
200 }
201 if (!f->replace_str && common_flags()->intercept_strlen) {
202 Report(format: "WARNING: strlen interceptor is enabled even though replace_str=0. "
203 "Use intercept_strlen=0 to disable it.");
204 }
205 if (!f->replace_str && common_flags()->intercept_strchr) {
206 Report(format: "WARNING: strchr* interceptors are enabled even though "
207 "replace_str=0. Use intercept_strchr=0 to disable them.");
208 }
209 if (!f->replace_str && common_flags()->intercept_strndup) {
210 Report(format: "WARNING: strndup* interceptors are enabled even though "
211 "replace_str=0. Use intercept_strndup=0 to disable them.");
212 }
213}
214
215void InitializeFlags() {
216 InitializeDefaultFlags();
217 ProcessFlags();
218
219#if SANITIZER_WINDOWS
220 // On Windows, weak symbols are emulated by having the user program
221 // register which weak functions are defined.
222 // The ASAN DLL will initialize flags prior to user module initialization,
223 // so __asan_default_options will not point to the user definition yet.
224 // We still want to ensure we capture when options are passed via
225 // __asan_default_options, so we add a callback to be run
226 // when it is registered with the runtime.
227
228 // There is theoretically time between the initial ProcessFlags and
229 // registering the weak callback where a weak function could be added and we
230 // would miss it, but in practice, InitializeFlags will always happen under
231 // the loader lock (if built as a DLL) and so will any calls to
232 // __sanitizer_register_weak_function.
233 AddRegisterWeakFunctionCallback(
234 reinterpret_cast<uptr>(__asan_default_options), []() {
235 FlagParser asan_parser;
236
237 RegisterAsanFlags(&asan_parser, flags());
238 RegisterCommonFlags(&asan_parser);
239 asan_parser.ParseString(__asan_default_options());
240
241 DisplayHelpMessages(&asan_parser);
242 ProcessFlags();
243
244 // TODO: Update other globals and data structures that may need to change
245 // after initialization due to new flags potentially being set changing after
246 // `__asan_default_options` is registered.
247 // See GH issue 'https://github.com/llvm/llvm-project/issues/117925' for
248 // details.
249 SetAllocatorMayReturnNull(common_flags()->allocator_may_return_null);
250 });
251
252# if CAN_SANITIZE_UB
253 AddRegisterWeakFunctionCallback(
254 reinterpret_cast<uptr>(__ubsan_default_options), []() {
255 FlagParser ubsan_parser;
256
257 __ubsan::RegisterUbsanFlags(&ubsan_parser, __ubsan::flags());
258 RegisterCommonFlags(&ubsan_parser);
259 ubsan_parser.ParseString(__ubsan_default_options());
260
261 // To match normal behavior, do not print UBSan help.
262 ProcessFlags();
263 });
264# endif
265
266# if CAN_SANITIZE_LEAKS
267 AddRegisterWeakFunctionCallback(
268 reinterpret_cast<uptr>(__lsan_default_options), []() {
269 FlagParser lsan_parser;
270
271 __lsan::RegisterLsanFlags(&lsan_parser, __lsan::flags());
272 RegisterCommonFlags(&lsan_parser);
273 lsan_parser.ParseString(__lsan_default_options());
274
275 // To match normal behavior, do not print LSan help.
276 ProcessFlags();
277 });
278# endif
279
280#endif
281}
282
283} // namespace __asan
284
285SANITIZER_INTERFACE_WEAK_DEF(const char*, __asan_default_options, void) {
286 return "";
287}
288

source code of compiler-rt/lib/asan/asan_flags.cpp