cpython/Python/pathconfig.c
Victor Stinner b07f546ea3
gh-98978: Fix Py_SetPythonHome(NULL) (#99066)
Fix use-after-free in Py_SetPythonHome(NULL), Py_SetProgramName(NULL)
and _Py_SetProgramFullPath(NULL) function calls.

Issue reported by Benedikt Reinartz.
2022-11-03 18:34:32 +01:00

525 lines
13 KiB
C

/* Path configuration like module_search_path (sys.path) */
#include "Python.h"
#include "marshal.h" // PyMarshal_ReadObjectFromString
#include "osdefs.h" // DELIM
#include "pycore_initconfig.h"
#include "pycore_fileutils.h"
#include "pycore_pathconfig.h"
#include "pycore_pymem.h" // _PyMem_SetDefaultAllocator()
#include <wchar.h>
#ifdef MS_WINDOWS
# include <windows.h> // GetFullPathNameW(), MAX_PATH
# include <pathcch.h>
# include <shlwapi.h>
#endif
#ifdef __cplusplus
extern "C" {
#endif
/* External interface */
/* Stored values set by C API functions */
typedef struct _PyPathConfig {
/* Full path to the Python program */
wchar_t *program_full_path;
wchar_t *prefix;
wchar_t *exec_prefix;
wchar_t *stdlib_dir;
/* Set by Py_SetPath */
wchar_t *module_search_path;
/* Set by _PyPathConfig_UpdateGlobal */
wchar_t *calculated_module_search_path;
/* Python program name */
wchar_t *program_name;
/* Set by Py_SetPythonHome() or PYTHONHOME environment variable */
wchar_t *home;
int _is_python_build;
} _PyPathConfig;
# define _PyPathConfig_INIT \
{.module_search_path = NULL, ._is_python_build = 0}
_PyPathConfig _Py_path_config = _PyPathConfig_INIT;
const wchar_t *
_PyPathConfig_GetGlobalModuleSearchPath(void)
{
return _Py_path_config.module_search_path;
}
void
_PyPathConfig_ClearGlobal(void)
{
PyMemAllocatorEx old_alloc;
_PyMem_SetDefaultAllocator(PYMEM_DOMAIN_RAW, &old_alloc);
#define CLEAR(ATTR) \
do { \
PyMem_RawFree(_Py_path_config.ATTR); \
_Py_path_config.ATTR = NULL; \
} while (0)
CLEAR(program_full_path);
CLEAR(prefix);
CLEAR(exec_prefix);
CLEAR(stdlib_dir);
CLEAR(module_search_path);
CLEAR(calculated_module_search_path);
CLEAR(program_name);
CLEAR(home);
_Py_path_config._is_python_build = 0;
#undef CLEAR
PyMem_SetAllocator(PYMEM_DOMAIN_RAW, &old_alloc);
}
PyStatus
_PyPathConfig_ReadGlobal(PyConfig *config)
{
PyStatus status = _PyStatus_OK();
#define COPY(ATTR) \
do { \
if (_Py_path_config.ATTR && !config->ATTR) { \
status = PyConfig_SetString(config, &config->ATTR, _Py_path_config.ATTR); \
if (_PyStatus_EXCEPTION(status)) goto done; \
} \
} while (0)
#define COPY2(ATTR, SRCATTR) \
do { \
if (_Py_path_config.SRCATTR && !config->ATTR) { \
status = PyConfig_SetString(config, &config->ATTR, _Py_path_config.SRCATTR); \
if (_PyStatus_EXCEPTION(status)) goto done; \
} \
} while (0)
#define COPY_INT(ATTR) \
do { \
assert(_Py_path_config.ATTR >= 0); \
if ((_Py_path_config.ATTR >= 0) && (config->ATTR <= 0)) { \
config->ATTR = _Py_path_config.ATTR; \
} \
} while (0)
COPY(prefix);
COPY(exec_prefix);
COPY(stdlib_dir);
COPY(program_name);
COPY(home);
COPY2(executable, program_full_path);
COPY_INT(_is_python_build);
// module_search_path must be initialised - not read
#undef COPY
#undef COPY2
#undef COPY_INT
done:
return status;
}
PyStatus
_PyPathConfig_UpdateGlobal(const PyConfig *config)
{
PyMemAllocatorEx old_alloc;
_PyMem_SetDefaultAllocator(PYMEM_DOMAIN_RAW, &old_alloc);
#define COPY(ATTR) \
do { \
if (config->ATTR) { \
PyMem_RawFree(_Py_path_config.ATTR); \
_Py_path_config.ATTR = _PyMem_RawWcsdup(config->ATTR); \
if (!_Py_path_config.ATTR) goto error; \
} \
} while (0)
#define COPY2(ATTR, SRCATTR) \
do { \
if (config->SRCATTR) { \
PyMem_RawFree(_Py_path_config.ATTR); \
_Py_path_config.ATTR = _PyMem_RawWcsdup(config->SRCATTR); \
if (!_Py_path_config.ATTR) goto error; \
} \
} while (0)
#define COPY_INT(ATTR) \
do { \
if (config->ATTR > 0) { \
_Py_path_config.ATTR = config->ATTR; \
} \
} while (0)
COPY(prefix);
COPY(exec_prefix);
COPY(stdlib_dir);
COPY(program_name);
COPY(home);
COPY2(program_full_path, executable);
COPY_INT(_is_python_build);
#undef COPY
#undef COPY2
#undef COPY_INT
PyMem_RawFree(_Py_path_config.module_search_path);
_Py_path_config.module_search_path = NULL;
PyMem_RawFree(_Py_path_config.calculated_module_search_path);
_Py_path_config.calculated_module_search_path = NULL;
do {
size_t cch = 1;
for (Py_ssize_t i = 0; i < config->module_search_paths.length; ++i) {
cch += 1 + wcslen(config->module_search_paths.items[i]);
}
wchar_t *path = (wchar_t*)PyMem_RawMalloc(sizeof(wchar_t) * cch);
if (!path) {
goto error;
}
wchar_t *p = path;
for (Py_ssize_t i = 0; i < config->module_search_paths.length; ++i) {
wcscpy(p, config->module_search_paths.items[i]);
p = wcschr(p, L'\0');
*p++ = DELIM;
*p = L'\0';
}
do {
*p = L'\0';
} while (p != path && *--p == DELIM);
_Py_path_config.calculated_module_search_path = path;
} while (0);
PyMem_SetAllocator(PYMEM_DOMAIN_RAW, &old_alloc);
return _PyStatus_OK();
error:
PyMem_SetAllocator(PYMEM_DOMAIN_RAW, &old_alloc);
return _PyStatus_NO_MEMORY();
}
static void _Py_NO_RETURN
path_out_of_memory(const char *func)
{
_Py_FatalErrorFunc(func, "out of memory");
}
void
Py_SetPath(const wchar_t *path)
{
if (path == NULL) {
_PyPathConfig_ClearGlobal();
return;
}
PyMemAllocatorEx old_alloc;
_PyMem_SetDefaultAllocator(PYMEM_DOMAIN_RAW, &old_alloc);
PyMem_RawFree(_Py_path_config.prefix);
PyMem_RawFree(_Py_path_config.exec_prefix);
PyMem_RawFree(_Py_path_config.stdlib_dir);
PyMem_RawFree(_Py_path_config.module_search_path);
PyMem_RawFree(_Py_path_config.calculated_module_search_path);
_Py_path_config.prefix = _PyMem_RawWcsdup(L"");
_Py_path_config.exec_prefix = _PyMem_RawWcsdup(L"");
// XXX Copy this from the new module_search_path?
if (_Py_path_config.home != NULL) {
_Py_path_config.stdlib_dir = _PyMem_RawWcsdup(_Py_path_config.home);
}
else {
_Py_path_config.stdlib_dir = _PyMem_RawWcsdup(L"");
}
_Py_path_config.module_search_path = _PyMem_RawWcsdup(path);
_Py_path_config.calculated_module_search_path = NULL;
PyMem_SetAllocator(PYMEM_DOMAIN_RAW, &old_alloc);
if (_Py_path_config.prefix == NULL
|| _Py_path_config.exec_prefix == NULL
|| _Py_path_config.stdlib_dir == NULL
|| _Py_path_config.module_search_path == NULL)
{
path_out_of_memory(__func__);
}
}
void
Py_SetPythonHome(const wchar_t *home)
{
int has_value = home && home[0];
PyMemAllocatorEx old_alloc;
_PyMem_SetDefaultAllocator(PYMEM_DOMAIN_RAW, &old_alloc);
PyMem_RawFree(_Py_path_config.home);
_Py_path_config.home = NULL;
if (has_value) {
_Py_path_config.home = _PyMem_RawWcsdup(home);
}
PyMem_SetAllocator(PYMEM_DOMAIN_RAW, &old_alloc);
if (has_value && _Py_path_config.home == NULL) {
path_out_of_memory(__func__);
}
}
void
Py_SetProgramName(const wchar_t *program_name)
{
int has_value = program_name && program_name[0];
PyMemAllocatorEx old_alloc;
_PyMem_SetDefaultAllocator(PYMEM_DOMAIN_RAW, &old_alloc);
PyMem_RawFree(_Py_path_config.program_name);
_Py_path_config.program_name = NULL;
if (has_value) {
_Py_path_config.program_name = _PyMem_RawWcsdup(program_name);
}
PyMem_SetAllocator(PYMEM_DOMAIN_RAW, &old_alloc);
if (has_value && _Py_path_config.program_name == NULL) {
path_out_of_memory(__func__);
}
}
void
_Py_SetProgramFullPath(const wchar_t *program_full_path)
{
int has_value = program_full_path && program_full_path[0];
PyMemAllocatorEx old_alloc;
_PyMem_SetDefaultAllocator(PYMEM_DOMAIN_RAW, &old_alloc);
PyMem_RawFree(_Py_path_config.program_full_path);
_Py_path_config.program_full_path = NULL;
if (has_value) {
_Py_path_config.program_full_path = _PyMem_RawWcsdup(program_full_path);
}
PyMem_SetAllocator(PYMEM_DOMAIN_RAW, &old_alloc);
if (has_value && _Py_path_config.program_full_path == NULL) {
path_out_of_memory(__func__);
}
}
wchar_t *
Py_GetPath(void)
{
/* If the user has provided a path, return that */
if (_Py_path_config.module_search_path) {
return _Py_path_config.module_search_path;
}
/* If we have already done calculations, return the calculated path */
return _Py_path_config.calculated_module_search_path;
}
wchar_t *
_Py_GetStdlibDir(void)
{
wchar_t *stdlib_dir = _Py_path_config.stdlib_dir;
if (stdlib_dir != NULL && stdlib_dir[0] != L'\0') {
return stdlib_dir;
}
return NULL;
}
wchar_t *
Py_GetPrefix(void)
{
return _Py_path_config.prefix;
}
wchar_t *
Py_GetExecPrefix(void)
{
return _Py_path_config.exec_prefix;
}
wchar_t *
Py_GetProgramFullPath(void)
{
return _Py_path_config.program_full_path;
}
wchar_t*
Py_GetPythonHome(void)
{
return _Py_path_config.home;
}
wchar_t *
Py_GetProgramName(void)
{
return _Py_path_config.program_name;
}
/* Compute module search path from argv[0] or the current working
directory ("-m module" case) which will be prepended to sys.argv:
sys.path[0].
Return 1 if the path is correctly resolved and written into *path0_p.
Return 0 if it fails to resolve the full path. For example, return 0 if the
current working directory has been removed (bpo-36236) or if argv is empty.
Raise an exception and return -1 on error.
*/
int
_PyPathConfig_ComputeSysPath0(const PyWideStringList *argv, PyObject **path0_p)
{
assert(_PyWideStringList_CheckConsistency(argv));
if (argv->length == 0) {
/* Leave sys.path unchanged if sys.argv is empty */
return 0;
}
wchar_t *argv0 = argv->items[0];
int have_module_arg = (wcscmp(argv0, L"-m") == 0);
int have_script_arg = (!have_module_arg && (wcscmp(argv0, L"-c") != 0));
wchar_t *path0 = argv0;
Py_ssize_t n = 0;
#ifdef HAVE_REALPATH
wchar_t fullpath[MAXPATHLEN];
#elif defined(MS_WINDOWS)
wchar_t fullpath[MAX_PATH];
#endif
if (have_module_arg) {
#if defined(HAVE_REALPATH) || defined(MS_WINDOWS)
if (!_Py_wgetcwd(fullpath, Py_ARRAY_LENGTH(fullpath))) {
return 0;
}
path0 = fullpath;
#else
path0 = L".";
#endif
n = wcslen(path0);
}
#ifdef HAVE_READLINK
wchar_t link[MAXPATHLEN + 1];
int nr = 0;
wchar_t path0copy[2 * MAXPATHLEN + 1];
if (have_script_arg) {
nr = _Py_wreadlink(path0, link, Py_ARRAY_LENGTH(link));
}
if (nr > 0) {
/* It's a symlink */
link[nr] = '\0';
if (link[0] == SEP) {
path0 = link; /* Link to absolute path */
}
else if (wcschr(link, SEP) == NULL) {
/* Link without path */
}
else {
/* Must join(dirname(path0), link) */
wchar_t *q = wcsrchr(path0, SEP);
if (q == NULL) {
/* path0 without path */
path0 = link;
}
else {
/* Must make a copy, path0copy has room for 2 * MAXPATHLEN */
wcsncpy(path0copy, path0, MAXPATHLEN);
q = wcsrchr(path0copy, SEP);
wcsncpy(q+1, link, MAXPATHLEN);
q[MAXPATHLEN + 1] = L'\0';
path0 = path0copy;
}
}
}
#endif /* HAVE_READLINK */
wchar_t *p = NULL;
#if SEP == '\\'
/* Special case for Microsoft filename syntax */
if (have_script_arg) {
wchar_t *q;
#if defined(MS_WINDOWS)
/* Replace the first element in argv with the full path. */
wchar_t *ptemp;
if (GetFullPathNameW(path0,
Py_ARRAY_LENGTH(fullpath),
fullpath,
&ptemp)) {
path0 = fullpath;
}
#endif
p = wcsrchr(path0, SEP);
/* Test for alternate separator */
q = wcsrchr(p ? p : path0, '/');
if (q != NULL)
p = q;
if (p != NULL) {
n = p + 1 - path0;
if (n > 1 && p[-1] != ':')
n--; /* Drop trailing separator */
}
}
#else
/* All other filename syntaxes */
if (have_script_arg) {
#if defined(HAVE_REALPATH)
if (_Py_wrealpath(path0, fullpath, Py_ARRAY_LENGTH(fullpath))) {
path0 = fullpath;
}
#endif
p = wcsrchr(path0, SEP);
}
if (p != NULL) {
n = p + 1 - path0;
#if SEP == '/' /* Special case for Unix filename syntax */
if (n > 1) {
/* Drop trailing separator */
n--;
}
#endif /* Unix */
}
#endif /* All others */
PyObject *path0_obj = PyUnicode_FromWideChar(path0, n);
if (path0_obj == NULL) {
return -1;
}
*path0_p = path0_obj;
return 1;
}
#ifdef __cplusplus
}
#endif