1 //===-- asan_linux.cpp ----------------------------------------------------===//
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 // Linux-specific details.
12 //===----------------------------------------------------------------------===//
13
14 #include "sanitizer_common/sanitizer_platform.h"
15 #if SANITIZER_FREEBSD || SANITIZER_LINUX || SANITIZER_NETBSD || \
16 SANITIZER_SOLARIS
17
18 #include "asan_interceptors.h"
19 #include "asan_internal.h"
20 #include "asan_premap_shadow.h"
21 #include "asan_thread.h"
22 #include "sanitizer_common/sanitizer_flags.h"
23 #include "sanitizer_common/sanitizer_freebsd.h"
24 #include "sanitizer_common/sanitizer_libc.h"
25 #include "sanitizer_common/sanitizer_procmaps.h"
26
27 #include <sys/time.h>
28 #include <sys/resource.h>
29 #include <sys/mman.h>
30 #include <sys/syscall.h>
31 #include <sys/types.h>
32 #include <dlfcn.h>
33 #include <fcntl.h>
34 #include <limits.h>
35 #include <pthread.h>
36 #include <stdio.h>
37 #include <unistd.h>
38 #include <unwind.h>
39
40 #if SANITIZER_FREEBSD
41 #include <sys/link_elf.h>
42 #endif
43
44 #if SANITIZER_SOLARIS
45 #include <link.h>
46 #endif
47
48 #if SANITIZER_ANDROID || SANITIZER_FREEBSD || SANITIZER_SOLARIS
49 #include <ucontext.h>
50 extern "C" void* _DYNAMIC;
51 #elif SANITIZER_NETBSD
52 #include <link_elf.h>
53 #include <ucontext.h>
54 extern Elf_Dyn _DYNAMIC;
55 #else
56 #include <sys/ucontext.h>
57 #include <link.h>
58 #endif
59
60 // x86-64 FreeBSD 9.2 and older define 'ucontext_t' incorrectly in
61 // 32-bit mode.
62 #if SANITIZER_FREEBSD && (SANITIZER_WORDSIZE == 32) && \
63 __FreeBSD_version <= 902001 // v9.2
64 #define ucontext_t xucontext_t
65 #endif
66
67 typedef enum {
68 ASAN_RT_VERSION_UNDEFINED = 0,
69 ASAN_RT_VERSION_DYNAMIC,
70 ASAN_RT_VERSION_STATIC,
71 } asan_rt_version_t;
72
73 // FIXME: perhaps also store abi version here?
74 extern "C" {
75 SANITIZER_INTERFACE_ATTRIBUTE
76 asan_rt_version_t __asan_rt_version;
77 }
78
79 namespace __asan {
80
InitializePlatformInterceptors()81 void InitializePlatformInterceptors() {}
InitializePlatformExceptionHandlers()82 void InitializePlatformExceptionHandlers() {}
IsSystemHeapAddress(uptr addr)83 bool IsSystemHeapAddress (uptr addr) { return false; }
84
AsanDoesNotSupportStaticLinkage()85 void *AsanDoesNotSupportStaticLinkage() {
86 // This will fail to link with -static.
87 return &_DYNAMIC; // defined in link.h
88 }
89
90 #if ASAN_PREMAP_SHADOW
FindPremappedShadowStart(uptr shadow_size_bytes)91 uptr FindPremappedShadowStart(uptr shadow_size_bytes) {
92 uptr granularity = GetMmapGranularity();
93 uptr shadow_start = reinterpret_cast<uptr>(&__asan_shadow);
94 uptr premap_shadow_size = PremapShadowSize();
95 uptr shadow_size = RoundUpTo(shadow_size_bytes, granularity);
96 // We may have mapped too much. Release extra memory.
97 UnmapFromTo(shadow_start + shadow_size, shadow_start + premap_shadow_size);
98 return shadow_start;
99 }
100 #endif
101
FindDynamicShadowStart()102 uptr FindDynamicShadowStart() {
103 uptr shadow_size_bytes = MemToShadowSize(kHighMemEnd);
104 #if ASAN_PREMAP_SHADOW
105 if (!PremapShadowFailed())
106 return FindPremappedShadowStart(shadow_size_bytes);
107 #endif
108
109 return MapDynamicShadow(shadow_size_bytes, SHADOW_SCALE,
110 /*min_shadow_base_alignment*/ 0, kHighMemEnd);
111 }
112
AsanApplyToGlobals(globals_op_fptr op,const void * needle)113 void AsanApplyToGlobals(globals_op_fptr op, const void *needle) {
114 UNIMPLEMENTED();
115 }
116
FlushUnneededASanShadowMemory(uptr p,uptr size)117 void FlushUnneededASanShadowMemory(uptr p, uptr size) {
118 // Since asan's mapping is compacting, the shadow chunk may be
119 // not page-aligned, so we only flush the page-aligned portion.
120 ReleaseMemoryPagesToOS(MemToShadow(p), MemToShadow(p + size));
121 }
122
123 #if SANITIZER_ANDROID
124 // FIXME: should we do anything for Android?
AsanCheckDynamicRTPrereqs()125 void AsanCheckDynamicRTPrereqs() {}
AsanCheckIncompatibleRT()126 void AsanCheckIncompatibleRT() {}
127 #else
FindFirstDSOCallback(struct dl_phdr_info * info,size_t size,void * data)128 static int FindFirstDSOCallback(struct dl_phdr_info *info, size_t size,
129 void *data) {
130 VReport(2, "info->dlpi_name = %s\tinfo->dlpi_addr = %p\n",
131 info->dlpi_name, info->dlpi_addr);
132
133 // Continue until the first dynamic library is found
134 if (!info->dlpi_name || info->dlpi_name[0] == 0)
135 return 0;
136
137 // Ignore vDSO
138 if (internal_strncmp(info->dlpi_name, "linux-", sizeof("linux-") - 1) == 0)
139 return 0;
140
141 #if SANITIZER_FREEBSD || SANITIZER_NETBSD
142 // Ignore first entry (the main program)
143 char **p = (char **)data;
144 if (!(*p)) {
145 *p = (char *)-1;
146 return 0;
147 }
148 #endif
149
150 #if SANITIZER_SOLARIS
151 // Ignore executable on Solaris
152 if (info->dlpi_addr == 0)
153 return 0;
154 #endif
155
156 *(const char **)data = info->dlpi_name;
157 return 1;
158 }
159
IsDynamicRTName(const char * libname)160 static bool IsDynamicRTName(const char *libname) {
161 return internal_strstr(libname, "libclang_rt.asan") ||
162 internal_strstr(libname, "libasan.so");
163 }
164
ReportIncompatibleRT()165 static void ReportIncompatibleRT() {
166 Report("Your application is linked against incompatible ASan runtimes.\n");
167 Die();
168 }
169
AsanCheckDynamicRTPrereqs()170 void AsanCheckDynamicRTPrereqs() {
171 if (!ASAN_DYNAMIC || !flags()->verify_asan_link_order)
172 return;
173
174 // Ensure that dynamic RT is the first DSO in the list
175 const char *first_dso_name = nullptr;
176 dl_iterate_phdr(FindFirstDSOCallback, &first_dso_name);
177 if (first_dso_name && !IsDynamicRTName(first_dso_name)) {
178 Report("ASan runtime does not come first in initial library list; "
179 "you should either link runtime to your application or "
180 "manually preload it with LD_PRELOAD.\n");
181 Die();
182 }
183 }
184
AsanCheckIncompatibleRT()185 void AsanCheckIncompatibleRT() {
186 if (ASAN_DYNAMIC) {
187 if (__asan_rt_version == ASAN_RT_VERSION_UNDEFINED) {
188 __asan_rt_version = ASAN_RT_VERSION_DYNAMIC;
189 } else if (__asan_rt_version != ASAN_RT_VERSION_DYNAMIC) {
190 ReportIncompatibleRT();
191 }
192 } else {
193 if (__asan_rt_version == ASAN_RT_VERSION_UNDEFINED) {
194 // Ensure that dynamic runtime is not present. We should detect it
195 // as early as possible, otherwise ASan interceptors could bind to
196 // the functions in dynamic ASan runtime instead of the functions in
197 // system libraries, causing crashes later in ASan initialization.
198 MemoryMappingLayout proc_maps(/*cache_enabled*/true);
199 char filename[PATH_MAX];
200 MemoryMappedSegment segment(filename, sizeof(filename));
201 while (proc_maps.Next(&segment)) {
202 if (IsDynamicRTName(segment.filename)) {
203 Report("Your application is linked against "
204 "incompatible ASan runtimes.\n");
205 Die();
206 }
207 }
208 __asan_rt_version = ASAN_RT_VERSION_STATIC;
209 } else if (__asan_rt_version != ASAN_RT_VERSION_STATIC) {
210 ReportIncompatibleRT();
211 }
212 }
213 }
214 #endif // SANITIZER_ANDROID
215
216 #if !SANITIZER_ANDROID
ReadContextStack(void * context,uptr * stack,uptr * ssize)217 void ReadContextStack(void *context, uptr *stack, uptr *ssize) {
218 ucontext_t *ucp = (ucontext_t*)context;
219 *stack = (uptr)ucp->uc_stack.ss_sp;
220 *ssize = ucp->uc_stack.ss_size;
221 }
222 #else
ReadContextStack(void * context,uptr * stack,uptr * ssize)223 void ReadContextStack(void *context, uptr *stack, uptr *ssize) {
224 UNIMPLEMENTED();
225 }
226 #endif
227
AsanDlSymNext(const char * sym)228 void *AsanDlSymNext(const char *sym) {
229 return dlsym(RTLD_NEXT, sym);
230 }
231
HandleDlopenInit()232 bool HandleDlopenInit() {
233 // Not supported on this platform.
234 static_assert(!SANITIZER_SUPPORTS_INIT_FOR_DLOPEN,
235 "Expected SANITIZER_SUPPORTS_INIT_FOR_DLOPEN to be false");
236 return false;
237 }
238
239 } // namespace __asan
240
241 #endif // SANITIZER_FREEBSD || SANITIZER_LINUX || SANITIZER_NETBSD ||
242 // SANITIZER_SOLARIS
243