From 86a41b921ca5c4bad1d0d7e54f9276046a25e319 Mon Sep 17 00:00:00 2001 From: Pali Rohár Date: Mon, 25 Jan 2021 23:27:22 +0100 Subject: Function dladdr() now retrieve symbol name and symbol address from both export and import tables dladdr tests for Windows now should always pass like on other systems. --- Makefile | 4 +- src/dlfcn.c | 106 ++++++++++++++++++++++++++++++++++++++------------- tests/CMakeLists.txt | 7 ++++ tests/test-dladdr.c | 23 ++++------- 4 files changed, 97 insertions(+), 43 deletions(-) diff --git a/Makefile b/Makefile index 944358f..899334a 100644 --- a/Makefile +++ b/Makefile @@ -65,10 +65,10 @@ test-static.exe: tests/test.c $(TARGETS) $(CC) $(CFLAGS) -o $@ $< libdl.a test-dladdr.exe: tests/test-dladdr.c $(TARGETS) - $(CC) $(CFLAGS) -DDLFCN_WIN32_SHARED -o $@ $< libdl.dll.a + $(CC) $(CFLAGS) -Wl,--export-all-symbols -DDLFCN_WIN32_SHARED -o $@ $< libdl.dll.a test-dladdr-static.exe: tests/test-dladdr.c $(TARGETS) - $(CC) $(CFLAGS) -o $@ $< libdl.a + $(CC) $(CFLAGS) -Wl,--export-all-symbols -o $@ $< libdl.a testdll.dll: tests/testdll.c $(CC) $(CFLAGS) -shared -o $@ $^ diff --git a/src/dlfcn.c b/src/dlfcn.c index 5dd1ccf..b52b307 100644 --- a/src/dlfcn.c +++ b/src/dlfcn.c @@ -512,8 +512,8 @@ static BOOL get_image_section( HMODULE module, int index, void **ptr, DWORD *siz return TRUE; } -/* Return symbol name for a given address */ -static const char *get_symbol_name( HMODULE module, IMAGE_IMPORT_DESCRIPTOR *iid, void *addr, void **func_address ) +/* Return symbol name for a given address from import table */ +static const char *get_import_symbol_name( HMODULE module, IMAGE_IMPORT_DESCRIPTOR *iid, void *addr, void **func_address ) { int i; void *candidateAddr = NULL; @@ -545,6 +545,40 @@ static const char *get_symbol_name( HMODULE module, IMAGE_IMPORT_DESCRIPTOR *iid return candidateName; } +/* Return symbol name for a given address from export table */ +static const char *get_export_symbol_name( HMODULE module, IMAGE_EXPORT_DIRECTORY *ied, void *addr, void **func_address ) +{ + DWORD i; + void *candidateAddr = NULL; + int candidateIndex = -1; + BYTE *base = (BYTE *) module; + DWORD *functionAddressesOffsets = (DWORD *) (base + ied->AddressOfFunctions); + DWORD *functionNamesOffsets = (DWORD *) (base + ied->AddressOfNames); + USHORT *functionNameOrdinalsIndexes = (USHORT *) (base + ied->AddressOfNameOrdinals); + + for( i = 0; i < ied->NumberOfFunctions; i++ ) + { + if( (void *) ( base + functionAddressesOffsets[i] ) > addr || candidateAddr >= (void *) ( base + functionAddressesOffsets[i] ) ) + continue; + + candidateAddr = (void *) ( base + functionAddressesOffsets[i] ); + candidateIndex = i; + } + + if( candidateIndex == -1 ) + return NULL; + + *func_address = candidateAddr; + + for( i = 0; i < ied->NumberOfNames; i++ ) + { + if( functionNameOrdinalsIndexes[i] == candidateIndex ) + return (const char *) ( base + functionNamesOffsets[i] ); + } + + return NULL; +} + static BOOL is_valid_address( void *addr ) { MEMORY_BASIC_INFORMATION info; @@ -608,11 +642,16 @@ static void *get_address_from_import_address_table( void *iat, DWORD iat_size, v /* Holds module filename */ static char module_filename[2*MAX_PATH]; -static BOOL fill_module_info( void *addr, Dl_info *info ) +static BOOL fill_info( HMODULE hModuleImport, void *addr, Dl_info *info ) { HMODULE hModule; DWORD dwSize; + IMAGE_EXPORT_DIRECTORY *ied; + IMAGE_IMPORT_DESCRIPTOR *iid; + const char *name; + void *funcAddress = NULL; + /* Get module of the specified address */ if( !GetModuleHandleExA( GET_MODULE_HANDLE_EX_FLAG_FROM_ADDRESS | GET_MODULE_HANDLE_EX_FLAG_UNCHANGED_REFCOUNT, addr, &hModule ) || hModule == NULL ) return FALSE; @@ -621,8 +660,27 @@ static BOOL fill_module_info( void *addr, Dl_info *info ) if( dwSize == 0 || dwSize == sizeof( module_filename ) ) return FALSE; - info->dli_fbase = (void *) hModule; info->dli_fname = module_filename; + info->dli_fbase = (void *) hModule; + info->dli_sname = NULL; + + /* First try to find function name and function address in module's export table */ + if( get_image_section( hModule, IMAGE_DIRECTORY_ENTRY_EXPORT, (void **) &ied, NULL ) ) + info->dli_sname = get_export_symbol_name( hModule, ied, addr, &funcAddress ); + + /* If symbol name is not known and we know which module is importing this address + * then try to find symbol name in this module's import table as the last resort. */ + if( info->dli_sname == NULL && hModuleImport != NULL ) + { + if( get_image_section( hModuleImport, IMAGE_DIRECTORY_ENTRY_IMPORT, (void **) &iid, NULL ) ) + { + name = get_import_symbol_name( hModuleImport, iid, addr, &funcAddress ); + if( name != NULL ) + info->dli_sname = name; + } + } + + info->dli_saddr = info->dli_sname == NULL ? NULL : funcAddress != NULL ? funcAddress : addr; return TRUE; } @@ -630,36 +688,33 @@ static BOOL fill_module_info( void *addr, Dl_info *info ) DLFCN_EXPORT int dladdr( void *addr, Dl_info *info ) { - void *realAddr, *funcAddress = NULL; - HMODULE hModule; - IMAGE_IMPORT_DESCRIPTOR *iid; - DWORD iidSize = 0; + HMODULE hModule = NULL; if( addr == NULL || info == NULL ) return 0; - hModule = GetModuleHandleA( NULL ); - if( hModule == NULL ) - return 0; - if( !is_valid_address( addr ) ) return 0; - realAddr = addr; - - if( !get_image_section( hModule, IMAGE_DIRECTORY_ENTRY_IMPORT, (void **) &iid, &iidSize ) ) - return 0; - if( is_import_thunk( addr ) ) { void *iat; - void *iatAddr = NULL; - DWORD iatSize = 0; + DWORD iatSize; + + /* Get module of the import thunk address */ + if( !GetModuleHandleExA( GET_MODULE_HANDLE_EX_FLAG_FROM_ADDRESS | GET_MODULE_HANDLE_EX_FLAG_UNCHANGED_REFCOUNT, addr, &hModule ) || hModule == NULL ) + return 0; if( !get_image_section( hModule, IMAGE_DIRECTORY_ENTRY_IAT, &iat, &iatSize ) ) { /* Fallback for cases where the iat is not defined, * for example i586-mingw32msvc-gcc */ + IMAGE_IMPORT_DESCRIPTOR *iid; + DWORD iidSize; + + if( !get_image_section( hModule, IMAGE_DIRECTORY_ENTRY_IMPORT, (void **) &iid, &iidSize ) ) + return 0; + if( iid == NULL || iid->Characteristics == 0 || iid->FirstThunk == 0 ) return 0; @@ -668,19 +723,18 @@ int dladdr( void *addr, Dl_info *info ) iatSize = iidSize - (DWORD) ( (BYTE *) iat - (BYTE *) iid ); } - iatAddr = get_address_from_import_address_table( iat, iatSize, addr ); - if( iatAddr == NULL ) + addr = get_address_from_import_address_table( iat, iatSize, addr ); + + if( addr == NULL ) return 0; - realAddr = iatAddr; + if( !is_valid_address( addr ) ) + return 0; } - if( !fill_module_info( realAddr, info ) ) + if( !fill_info( hModule, addr, info ) ) return 0; - info->dli_sname = get_symbol_name( hModule, iid, realAddr, &funcAddress ); - - info->dli_saddr = !info->dli_sname ? NULL : funcAddress ? funcAddress : realAddr; return 1; } diff --git a/tests/CMakeLists.txt b/tests/CMakeLists.txt index 00b6647..47fef38 100644 --- a/tests/CMakeLists.txt +++ b/tests/CMakeLists.txt @@ -25,6 +25,13 @@ target_link_libraries(test-dladdr dl) if(UNIX) set_target_properties(test-dladdr PROPERTIES COMPILE_FLAGS "-Wl,--export-dynamic -fpie") endif() +if(WIN32 AND NOT BUILD_SHARED_LIBS) + if(MSVC) + set_property(TARGET test-dladdr APPEND_STRING PROPERTY LINK_FLAGS "/EXPORT:dlopen /EXPORT:dladdr") + else() + set_property(TARGET test-dladdr APPEND_STRING PROPERTY LINK_FLAGS "-Wl,--export-all-symbols") + endif() +endif() install(TARGETS test-dladdr EXPORT dlfcn-win32-targets RUNTIME DESTINATION bin) diff --git a/tests/test-dladdr.c b/tests/test-dladdr.c index 57914cb..e2f6c01 100644 --- a/tests/test-dladdr.c +++ b/tests/test-dladdr.c @@ -1,4 +1,6 @@ /* On Unix like os compile with "-Wl,--export-dynamic -fpie" (default with cmake) */ +/* On Windows gcc compile with "-Wl,--export-all-symbols" (default with cmake) */ +/* On Windows msvc compile with "/EXPORT:dlopen /EXPORT:dladdr" (default with cmake) */ /* required for non Windows builds, must be set in front of the first system include */ #define _GNU_SOURCE @@ -131,20 +133,11 @@ __declspec(dllimport) int __cdecl atoi(const char *_Str); #endif #endif -#ifdef _WIN32 -#define FailOnWin Fail -#else -#define FailOnWin Pass -#endif - -#if defined(_WIN32) && !defined(DLFCN_WIN32_SHARED) -#define PassOnSharedBuild Fail -#else -#define PassOnSharedBuild Pass -#endif - #define UNUSED(x) (void)x +#ifdef _WIN32 +__declspec(dllexport) +#endif int main(int argc, char **argv) { /* points to non reachable address */ @@ -161,10 +154,10 @@ int main(int argc, char **argv) result = check_dladdr( "null pointer", (void*)0, NULL , NoInfo); result |= check_dladdr( "invalid pointer", (void*)0x125, NULL , NoInfo); - result |= check_dladdr( "function from dl library", (void*)dladdr, "dladdr" , PassOnSharedBuild ); - result |= check_dladdr( "function from dl library", (void*)dlopen, "dlopen", PassOnSharedBuild ); + result |= check_dladdr( "function from dl library", (void*)dladdr, "dladdr" , Pass ); + result |= check_dladdr( "function from dl library", (void*)dlopen, "dlopen", Pass ); result |= check_dladdr( "function from glibc/msvcrt library", (void*)atoi, "atoi", Pass ); - result |= check_dladdr( "function from executable", (void*)main, "main", FailOnWin ); + result |= check_dladdr( "function from executable", (void*)main, "main", Pass ); result |= check_dladdr( "static function from executable", (void*)print_dl_info, "print_dl_info", Fail ); result |= check_dladdr( "address with positive offset", ((char*)atoi)+1, "atoi", PassWithDifferentAddress ); result |= check_dladdr( "zero address from import thunk", zero_thunk_address, "", NoInfo ); -- cgit v1.2.3-55-g6feb From e53ecd53bafbe2ee856ac4775b39679c5e5266f4 Mon Sep 17 00:00:00 2001 From: Pali Rohár Date: Fri, 29 Jan 2021 13:59:41 +0100 Subject: Remove code for finding symbol name in import table It is not required as import table can use only symbols which are exported and therefore are in export table. So if symbol is not found in export table it cannot be in import table. --- src/dlfcn.c | 59 ++++++----------------------------------------------------- 1 file changed, 6 insertions(+), 53 deletions(-) diff --git a/src/dlfcn.c b/src/dlfcn.c index b52b307..2b2ea07 100644 --- a/src/dlfcn.c +++ b/src/dlfcn.c @@ -512,39 +512,6 @@ static BOOL get_image_section( HMODULE module, int index, void **ptr, DWORD *siz return TRUE; } -/* Return symbol name for a given address from import table */ -static const char *get_import_symbol_name( HMODULE module, IMAGE_IMPORT_DESCRIPTOR *iid, void *addr, void **func_address ) -{ - int i; - void *candidateAddr = NULL; - const char *candidateName = NULL; - BYTE *base = (BYTE *) module; /* Required to have correct calculations */ - - for( i = 0; iid[i].Characteristics != 0 && iid[i].FirstThunk != 0; i++ ) - { - IMAGE_THUNK_DATA *thunkILT = (IMAGE_THUNK_DATA *)( base + iid[i].Characteristics ); - IMAGE_THUNK_DATA *thunkIAT = (IMAGE_THUNK_DATA *)( base + iid[i].FirstThunk ); - - for( ; thunkILT->u1.AddressOfData != 0; thunkILT++, thunkIAT++ ) - { - IMAGE_IMPORT_BY_NAME *nameData; - - if( IMAGE_SNAP_BY_ORDINAL( thunkILT->u1.Ordinal ) ) - continue; - - if( (void *) thunkIAT->u1.Function > addr || candidateAddr >= (void *) thunkIAT->u1.Function ) - continue; - - candidateAddr = (void *) thunkIAT->u1.Function; - nameData = (IMAGE_IMPORT_BY_NAME *)( base + (ULONG_PTR) thunkILT->u1.AddressOfData ); - candidateName = (const char *) nameData->Name; - } - } - - *func_address = candidateAddr; - return candidateName; -} - /* Return symbol name for a given address from export table */ static const char *get_export_symbol_name( HMODULE module, IMAGE_EXPORT_DIRECTORY *ied, void *addr, void **func_address ) { @@ -642,13 +609,11 @@ static void *get_address_from_import_address_table( void *iat, DWORD iat_size, v /* Holds module filename */ static char module_filename[2*MAX_PATH]; -static BOOL fill_info( HMODULE hModuleImport, void *addr, Dl_info *info ) +static BOOL fill_info( void *addr, Dl_info *info ) { HMODULE hModule; DWORD dwSize; IMAGE_EXPORT_DIRECTORY *ied; - IMAGE_IMPORT_DESCRIPTOR *iid; - const char *name; void *funcAddress = NULL; /* Get module of the specified address */ @@ -662,23 +627,12 @@ static BOOL fill_info( HMODULE hModuleImport, void *addr, Dl_info *info ) info->dli_fname = module_filename; info->dli_fbase = (void *) hModule; - info->dli_sname = NULL; - /* First try to find function name and function address in module's export table */ + /* Find function name and function address in module's export table */ if( get_image_section( hModule, IMAGE_DIRECTORY_ENTRY_EXPORT, (void **) &ied, NULL ) ) info->dli_sname = get_export_symbol_name( hModule, ied, addr, &funcAddress ); - - /* If symbol name is not known and we know which module is importing this address - * then try to find symbol name in this module's import table as the last resort. */ - if( info->dli_sname == NULL && hModuleImport != NULL ) - { - if( get_image_section( hModuleImport, IMAGE_DIRECTORY_ENTRY_IMPORT, (void **) &iid, NULL ) ) - { - name = get_import_symbol_name( hModuleImport, iid, addr, &funcAddress ); - if( name != NULL ) - info->dli_sname = name; - } - } + else + info->dli_sname = NULL; info->dli_saddr = info->dli_sname == NULL ? NULL : funcAddress != NULL ? funcAddress : addr; @@ -688,8 +642,6 @@ static BOOL fill_info( HMODULE hModuleImport, void *addr, Dl_info *info ) DLFCN_EXPORT int dladdr( void *addr, Dl_info *info ) { - HMODULE hModule = NULL; - if( addr == NULL || info == NULL ) return 0; @@ -700,6 +652,7 @@ int dladdr( void *addr, Dl_info *info ) { void *iat; DWORD iatSize; + HMODULE hModule; /* Get module of the import thunk address */ if( !GetModuleHandleExA( GET_MODULE_HANDLE_EX_FLAG_FROM_ADDRESS | GET_MODULE_HANDLE_EX_FLAG_UNCHANGED_REFCOUNT, addr, &hModule ) || hModule == NULL ) @@ -732,7 +685,7 @@ int dladdr( void *addr, Dl_info *info ) return 0; } - if( !fill_info( hModule, addr, info ) ) + if( !fill_info( addr, info ) ) return 0; return 1; -- cgit v1.2.3-55-g6feb From b46da88412444a7a22b7378402cabadf6689cea2 Mon Sep 17 00:00:00 2001 From: Pali Rohár Date: Fri, 29 Jan 2021 14:00:30 +0100 Subject: Remove duplicate checks for NULL pointers is_valid_address() already rejects NULL addresses, so there is no need to check address for NULL. --- src/dlfcn.c | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-) diff --git a/src/dlfcn.c b/src/dlfcn.c index 2b2ea07..abbd58d 100644 --- a/src/dlfcn.c +++ b/src/dlfcn.c @@ -642,7 +642,7 @@ static BOOL fill_info( void *addr, Dl_info *info ) DLFCN_EXPORT int dladdr( void *addr, Dl_info *info ) { - if( addr == NULL || info == NULL ) + if( info == NULL ) return 0; if( !is_valid_address( addr ) ) @@ -678,9 +678,6 @@ int dladdr( void *addr, Dl_info *info ) addr = get_address_from_import_address_table( iat, iatSize, addr ); - if( addr == NULL ) - return 0; - if( !is_valid_address( addr ) ) return 0; } -- cgit v1.2.3-55-g6feb