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 extern ElfW(Dyn) _DYNAMIC[]; 59 #endif 60 61 // x86-64 FreeBSD 9.2 and older define 'ucontext_t' incorrectly in 62 // 32-bit mode. 63 #if SANITIZER_FREEBSD && (SANITIZER_WORDSIZE == 32) && \ 64 __FreeBSD_version <= 902001 // v9.2 65 #define ucontext_t xucontext_t 66 #endif 67 68 typedef enum { 69 ASAN_RT_VERSION_UNDEFINED = 0, 70 ASAN_RT_VERSION_DYNAMIC, 71 ASAN_RT_VERSION_STATIC, 72 } asan_rt_version_t; 73 74 // FIXME: perhaps also store abi version here? 75 extern "C" { 76 SANITIZER_INTERFACE_ATTRIBUTE 77 asan_rt_version_t __asan_rt_version; 78 } 79 80 namespace __asan { 81 82 void InitializePlatformInterceptors() {} 83 void InitializePlatformExceptionHandlers() {} 84 bool IsSystemHeapAddress (uptr addr) { return false; } 85 86 void *AsanDoesNotSupportStaticLinkage() { 87 // This will fail to link with -static. 88 return &_DYNAMIC; 89 } 90 91 #if ASAN_PREMAP_SHADOW 92 uptr FindPremappedShadowStart(uptr shadow_size_bytes) { 93 uptr granularity = GetMmapGranularity(); 94 uptr shadow_start = reinterpret_cast<uptr>(&__asan_shadow); 95 uptr premap_shadow_size = PremapShadowSize(); 96 uptr shadow_size = RoundUpTo(shadow_size_bytes, granularity); 97 // We may have mapped too much. Release extra memory. 98 UnmapFromTo(shadow_start + shadow_size, shadow_start + premap_shadow_size); 99 return shadow_start; 100 } 101 #endif 102 103 uptr FindDynamicShadowStart() { 104 uptr shadow_size_bytes = MemToShadowSize(kHighMemEnd); 105 #if ASAN_PREMAP_SHADOW 106 if (!PremapShadowFailed()) 107 return FindPremappedShadowStart(shadow_size_bytes); 108 #endif 109 110 return MapDynamicShadow(shadow_size_bytes, ASAN_SHADOW_SCALE, 111 /*min_shadow_base_alignment*/ 0, kHighMemEnd); 112 } 113 114 void AsanApplyToGlobals(globals_op_fptr op, const void *needle) { 115 UNIMPLEMENTED(); 116 } 117 118 void FlushUnneededASanShadowMemory(uptr p, uptr size) { 119 // Since asan's mapping is compacting, the shadow chunk may be 120 // not page-aligned, so we only flush the page-aligned portion. 121 ReleaseMemoryPagesToOS(MemToShadow(p), MemToShadow(p + size)); 122 } 123 124 #if SANITIZER_ANDROID 125 // FIXME: should we do anything for Android? 126 void AsanCheckDynamicRTPrereqs() {} 127 void AsanCheckIncompatibleRT() {} 128 #else 129 static int FindFirstDSOCallback(struct dl_phdr_info *info, size_t size, 130 void *data) { 131 VReport(2, "info->dlpi_name = %s\tinfo->dlpi_addr = %p\n", info->dlpi_name, 132 (void *)info->dlpi_addr); 133 134 const char **name = (const char **)data; 135 136 // Ignore first entry (the main program) 137 if (!*name) { 138 *name = ""; 139 return 0; 140 } 141 142 # if SANITIZER_LINUX 143 // Ignore vDSO. glibc versions earlier than 2.15 (and some patched 144 // by distributors) return an empty name for the vDSO entry, so 145 // detect this as well. 146 if (!info->dlpi_name[0] || 147 internal_strncmp(info->dlpi_name, "linux-", sizeof("linux-") - 1) == 0) 148 return 0; 149 # endif 150 151 *name = info->dlpi_name; 152 return 1; 153 } 154 155 static bool IsDynamicRTName(const char *libname) { 156 return internal_strstr(libname, "libclang_rt.asan") || 157 internal_strstr(libname, "libasan.so"); 158 } 159 160 static void ReportIncompatibleRT() { 161 Report("Your application is linked against incompatible ASan runtimes.\n"); 162 Die(); 163 } 164 165 void AsanCheckDynamicRTPrereqs() { 166 if (!ASAN_DYNAMIC || !flags()->verify_asan_link_order) 167 return; 168 169 // Ensure that dynamic RT is the first DSO in the list 170 const char *first_dso_name = nullptr; 171 dl_iterate_phdr(FindFirstDSOCallback, &first_dso_name); 172 if (first_dso_name && first_dso_name[0] && !IsDynamicRTName(first_dso_name)) { 173 Report("ASan runtime does not come first in initial library list; " 174 "you should either link runtime to your application or " 175 "manually preload it with LD_PRELOAD.\n"); 176 Die(); 177 } 178 } 179 180 void AsanCheckIncompatibleRT() { 181 if (ASAN_DYNAMIC) { 182 if (__asan_rt_version == ASAN_RT_VERSION_UNDEFINED) { 183 __asan_rt_version = ASAN_RT_VERSION_DYNAMIC; 184 } else if (__asan_rt_version != ASAN_RT_VERSION_DYNAMIC) { 185 ReportIncompatibleRT(); 186 } 187 } else { 188 if (__asan_rt_version == ASAN_RT_VERSION_UNDEFINED) { 189 // Ensure that dynamic runtime is not present. We should detect it 190 // as early as possible, otherwise ASan interceptors could bind to 191 // the functions in dynamic ASan runtime instead of the functions in 192 // system libraries, causing crashes later in ASan initialization. 193 MemoryMappingLayout proc_maps(/*cache_enabled*/true); 194 char filename[PATH_MAX]; 195 MemoryMappedSegment segment(filename, sizeof(filename)); 196 while (proc_maps.Next(&segment)) { 197 if (IsDynamicRTName(segment.filename)) { 198 Report("Your application is linked against " 199 "incompatible ASan runtimes.\n"); 200 Die(); 201 } 202 } 203 __asan_rt_version = ASAN_RT_VERSION_STATIC; 204 } else if (__asan_rt_version != ASAN_RT_VERSION_STATIC) { 205 ReportIncompatibleRT(); 206 } 207 } 208 } 209 #endif // SANITIZER_ANDROID 210 211 #if !SANITIZER_ANDROID 212 void ReadContextStack(void *context, uptr *stack, uptr *ssize) { 213 ucontext_t *ucp = (ucontext_t*)context; 214 *stack = (uptr)ucp->uc_stack.ss_sp; 215 *ssize = ucp->uc_stack.ss_size; 216 } 217 218 void ResetContextStack(void *context) { 219 ucontext_t *ucp = (ucontext_t *)context; 220 ucp->uc_stack.ss_sp = nullptr; 221 ucp->uc_stack.ss_size = 0; 222 } 223 # else 224 void ReadContextStack(void *context, uptr *stack, uptr *ssize) { 225 UNIMPLEMENTED(); 226 } 227 228 void ResetContextStack(void *context) { UNIMPLEMENTED(); } 229 # endif 230 231 void *AsanDlSymNext(const char *sym) { 232 return dlsym(RTLD_NEXT, sym); 233 } 234 235 bool HandleDlopenInit() { 236 // Not supported on this platform. 237 static_assert(!SANITIZER_SUPPORTS_INIT_FOR_DLOPEN, 238 "Expected SANITIZER_SUPPORTS_INIT_FOR_DLOPEN to be false"); 239 return false; 240 } 241 242 } // namespace __asan 243 244 #endif // SANITIZER_FREEBSD || SANITIZER_LINUX || SANITIZER_NETBSD || 245 // SANITIZER_SOLARIS 246