diff options
Diffstat (limited to 'Modules/_hashopenssl.c')
| -rw-r--r-- | Modules/_hashopenssl.c | 116 |
1 files changed, 116 insertions, 0 deletions
diff --git a/Modules/_hashopenssl.c b/Modules/_hashopenssl.c index 0b2ef95..adc8653 100644 --- a/Modules/_hashopenssl.c +++ b/Modules/_hashopenssl.c @@ -21,6 +21,7 @@ /* EVP is the preferred interface to hashing in OpenSSL */ #include <openssl/evp.h> #include <openssl/hmac.h> +#include <openssl/crypto.h> /* We use the object interface to discover what hashes OpenSSL supports. */ #include <openssl/objects.h> #include "openssl/err.h" @@ -1833,6 +1834,120 @@ _hashlib_get_fips_mode_impl(PyObject *module) #endif // !LIBRESSL_VERSION_NUMBER +static int +_tscmp(const unsigned char *a, const unsigned char *b, + Py_ssize_t len_a, Py_ssize_t len_b) +{ + /* loop count depends on length of b. Might leak very little timing + * information if sizes are different. + */ + Py_ssize_t length = len_b; + const void *left = a; + const void *right = b; + int result = 0; + + if (len_a != length) { + left = b; + result = 1; + } + + result |= CRYPTO_memcmp(left, right, length); + + return (result == 0); +} + +/* NOTE: Keep in sync with _operator.c implementation. */ + +/*[clinic input] +_hashlib.compare_digest + + a: object + b: object + / + +Return 'a == b'. + +This function uses an approach designed to prevent +timing analysis, making it appropriate for cryptography. + +a and b must both be of the same type: either str (ASCII only), +or any bytes-like object. + +Note: If a and b are of different lengths, or if an error occurs, +a timing attack could theoretically reveal information about the +types and lengths of a and b--but not their values. +[clinic start generated code]*/ + +static PyObject * +_hashlib_compare_digest_impl(PyObject *module, PyObject *a, PyObject *b) +/*[clinic end generated code: output=6f1c13927480aed9 input=9c40c6e566ca12f5]*/ +{ + int rc; + + /* ASCII unicode string */ + if(PyUnicode_Check(a) && PyUnicode_Check(b)) { + if (PyUnicode_READY(a) == -1 || PyUnicode_READY(b) == -1) { + return NULL; + } + if (!PyUnicode_IS_ASCII(a) || !PyUnicode_IS_ASCII(b)) { + PyErr_SetString(PyExc_TypeError, + "comparing strings with non-ASCII characters is " + "not supported"); + return NULL; + } + + rc = _tscmp(PyUnicode_DATA(a), + PyUnicode_DATA(b), + PyUnicode_GET_LENGTH(a), + PyUnicode_GET_LENGTH(b)); + } + /* fallback to buffer interface for bytes, bytesarray and other */ + else { + Py_buffer view_a; + Py_buffer view_b; + + if (PyObject_CheckBuffer(a) == 0 && PyObject_CheckBuffer(b) == 0) { + PyErr_Format(PyExc_TypeError, + "unsupported operand types(s) or combination of types: " + "'%.100s' and '%.100s'", + Py_TYPE(a)->tp_name, Py_TYPE(b)->tp_name); + return NULL; + } + + if (PyObject_GetBuffer(a, &view_a, PyBUF_SIMPLE) == -1) { + return NULL; + } + if (view_a.ndim > 1) { + PyErr_SetString(PyExc_BufferError, + "Buffer must be single dimension"); + PyBuffer_Release(&view_a); + return NULL; + } + + if (PyObject_GetBuffer(b, &view_b, PyBUF_SIMPLE) == -1) { + PyBuffer_Release(&view_a); + return NULL; + } + if (view_b.ndim > 1) { + PyErr_SetString(PyExc_BufferError, + "Buffer must be single dimension"); + PyBuffer_Release(&view_a); + PyBuffer_Release(&view_b); + return NULL; + } + + rc = _tscmp((const unsigned char*)view_a.buf, + (const unsigned char*)view_b.buf, + view_a.len, + view_b.len); + + PyBuffer_Release(&view_a); + PyBuffer_Release(&view_b); + } + + return PyBool_FromLong(rc); +} + /* List of functions exported by this module */ static struct PyMethodDef EVP_functions[] = { @@ -1840,6 +1955,7 @@ static struct PyMethodDef EVP_functions[] = { PBKDF2_HMAC_METHODDEF _HASHLIB_SCRYPT_METHODDEF _HASHLIB_GET_FIPS_MODE_METHODDEF + _HASHLIB_COMPARE_DIGEST_METHODDEF _HASHLIB_HMAC_SINGLESHOT_METHODDEF _HASHLIB_HMAC_NEW_METHODDEF _HASHLIB_OPENSSL_MD5_METHODDEF |