Mercurial > hg
changeset 44058:bde1cd4c99d9
sha1dc: initial implementation of Python extension
A future change will use this when available to avoid sha1 collision
issues until we can get moved to something else.
Differential Revision: https://phab.mercurial-scm.org/D7815
| author | Augie Fackler <augie@google.com> |
|---|---|
| date | Wed, 08 Jan 2020 15:59:52 -0500 |
| parents | 7dddc2251365 |
| children | 7126d8b8e0e6 |
| files | mercurial/thirdparty/sha1dc/cext.c setup.py tests/test-hashutil.py |
| diffstat | 3 files changed, 265 insertions(+), 0 deletions(-) [+] |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/mercurial/thirdparty/sha1dc/cext.c Wed Jan 08 15:59:52 2020 -0500 @@ -0,0 +1,197 @@ +#define PY_SSIZE_T_CLEAN +#include <Python.h> + +#include "lib/sha1.h" + +#if PY_MAJOR_VERSION >= 3 +#define IS_PY3K +#endif + +/* helper to switch things like string literal depending on Python version */ +#ifdef IS_PY3K +#define PY23(py2, py3) py3 +#else +#define PY23(py2, py3) py2 +#endif + +static char sha1dc_doc[] = "Efficient detection of SHA1 collision constructs."; + +/* clang-format off */ +typedef struct { + PyObject_HEAD + SHA1_CTX ctx; +} pysha1ctx; +/* clang-format on */ + +static int pysha1ctx_init(pysha1ctx *self, PyObject *args) +{ + const char *data = NULL; + Py_ssize_t len; + + SHA1DCInit(&(self->ctx)); + /* We don't want "safe" sha1s, wherein sha1dc can give you a + different hash for something that's trying to give you a + collision. We just want to detect collisions. + */ + SHA1DCSetSafeHash(&(self->ctx), 0); + if (!PyArg_ParseTuple(args, PY23("|s#", "|y#"), &data, &len)) { + return -1; + } + if (data) { + SHA1DCUpdate(&(self->ctx), data, len); + } + return 0; +} + +static void pysha1ctx_dealloc(pysha1ctx *self) +{ + PyObject_Del(self); +} + +static PyObject *pysha1ctx_update(pysha1ctx *self, PyObject *args) +{ + const char *data; + Py_ssize_t len; + if (!PyArg_ParseTuple(args, PY23("s#", "y#"), &data, &len)) { + return NULL; + } + SHA1DCUpdate(&(self->ctx), data, len); + Py_RETURN_NONE; +} + +/* it is intentional that this take a ctx by value, as that clones the + context so we can keep using .update() without poisoning the state + with padding. +*/ +static int finalize(SHA1_CTX ctx, unsigned char *hash_out) +{ + if (SHA1DCFinal(hash_out, &ctx)) { + PyErr_SetString(PyExc_OverflowError, + "sha1 collision attack detected"); + return 0; + } + return 1; +} + +static PyObject *pysha1ctx_digest(pysha1ctx *self) +{ + unsigned char hash[20]; + if (!finalize(self->ctx, hash)) { + return NULL; + } + return PyBytes_FromStringAndSize((char *)hash, 20); +} + +static PyObject *pysha1ctx_hexdigest(pysha1ctx *self) +{ + unsigned char hash[20]; + if (!finalize(self->ctx, hash)) { + return NULL; + } + char hexhash[40]; + static const char hexdigit[] = "0123456789abcdef"; + for (int i = 0; i < 20; ++i) { + hexhash[i * 2] = hexdigit[hash[i] >> 4]; + hexhash[i * 2 + 1] = hexdigit[hash[i] & 15]; + } + return PyString_FromStringAndSize(hexhash, 40); +} + +static PyTypeObject sha1ctxType; + +static PyObject *pysha1ctx_copy(pysha1ctx *self) +{ + pysha1ctx *clone = (pysha1ctx *)PyObject_New(pysha1ctx, &sha1ctxType); + if (!clone) { + return NULL; + } + clone->ctx = self->ctx; + return (PyObject *)clone; +} + +static PyMethodDef pysha1ctx_methods[] = { + {"update", (PyCFunction)pysha1ctx_update, METH_VARARGS, + "Update this hash object's state with the provided bytes."}, + {"digest", (PyCFunction)pysha1ctx_digest, METH_NOARGS, + "Return the digest value as a string of binary data."}, + {"hexdigest", (PyCFunction)pysha1ctx_hexdigest, METH_NOARGS, + "Return the digest value as a string of hexadecimal digits."}, + {"copy", (PyCFunction)pysha1ctx_copy, METH_NOARGS, + "Return a copy of the hash object."}, + {NULL}, +}; + +/* clang-format off */ +static PyTypeObject sha1ctxType = { + PyVarObject_HEAD_INIT(NULL, 0) /* header */ + "sha1dc.sha1", /* tp_name */ + sizeof(pysha1ctx), /* tp_basicsize */ + 0, /* tp_itemsize */ + (destructor)pysha1ctx_dealloc, /* tp_dealloc */ + 0, /* tp_print */ + 0, /* tp_getattr */ + 0, /* tp_setattr */ + 0, /* tp_compare */ + 0, /* tp_repr */ + 0, /* tp_as_number */ + 0, /* tp_as_sequence */ + 0, /* tp_as_mapping */ + 0, /* tp_hash */ + 0, /* tp_call */ + 0, /* tp_str */ + 0, /* tp_getattro */ + 0, /* tp_setattro */ + 0, /* tp_as_buffer */ + Py_TPFLAGS_DEFAULT, /* tp_flags */ + "sha1 implementation that looks for collisions", /* tp_doc */ + 0, /* tp_traverse */ + 0, /* tp_clear */ + 0, /* tp_richcompare */ + 0, /* tp_weaklistoffset */ + 0, /* tp_iter */ + 0, /* tp_iternext */ + pysha1ctx_methods, /* tp_methods */ + 0, /* tp_members */ + 0, /* tp_getset */ + 0, /* tp_base */ + 0, /* tp_dict */ + 0, /* tp_descr_get */ + 0, /* tp_descr_set */ + 0, /* tp_dictoffset */ + (initproc)pysha1ctx_init, /* tp_init */ + 0, /* tp_alloc */ +}; +/* clang-format on */ + +static PyMethodDef methods[] = { + {NULL, NULL}, +}; + +static void module_init(PyObject *mod) +{ + sha1ctxType.tp_new = PyType_GenericNew; + if (PyType_Ready(&sha1ctxType) < 0) { + return; + } + Py_INCREF(&sha1ctxType); + + PyModule_AddObject(mod, "sha1", (PyObject *)&sha1ctxType); +} + +#ifdef IS_PY3K +static struct PyModuleDef sha1dc_module = {PyModuleDef_HEAD_INIT, "sha1dc", + sha1dc_doc, -1, methods}; + +PyMODINIT_FUNC PyInit_sha1dc(void) +{ + PyObject *mod = PyModule_Create(&sha1dc_module); + module_init(mod); + return mod; +} +#else +PyMODINIT_FUNC initsha1dc(void) +{ + PyObject *mod = Py_InitModule3("sha1dc", methods, sha1dc_doc); + module_init(mod); +} +#endif
--- a/setup.py Wed Jan 08 15:09:01 2020 -0500 +++ b/setup.py Wed Jan 08 15:59:52 2020 -0500 @@ -1481,6 +1481,14 @@ ], ), Extension( + 'mercurial.thirdparty.sha1dc', + [ + 'mercurial/thirdparty/sha1dc/cext.c', + 'mercurial/thirdparty/sha1dc/lib/sha1.c', + 'mercurial/thirdparty/sha1dc/lib/ubc_check.c', + ], + ), + Extension( 'hgext.fsmonitor.pywatchman.bser', ['hgext/fsmonitor/pywatchman/bser.c'] ), RustStandaloneExtension(
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/tests/test-hashutil.py Wed Jan 08 15:59:52 2020 -0500 @@ -0,0 +1,60 @@ +# Tests to ensure that sha1dc.sha1 is exactly a drop-in for +# hashlib.sha1 for our needs. +from __future__ import absolute_import + +import hashlib +import unittest + +import silenttestrunner + +try: + from mercurial.thirdparty import sha1dc +except ImportError: + sha1dc = None + + +class hashertestsbase(object): + def test_basic_hash(self): + h = self.hasher() + h.update(b'foo') + self.assertEqual( + '0beec7b5ea3f0fdbc95d0dd47f3c5bc275da8a33', h.hexdigest() + ) + h.update(b'bar') + self.assertEqual( + '8843d7f92416211de9ebb963ff4ce28125932878', h.hexdigest() + ) + + def test_copy_hasher(self): + h = self.hasher() + h.update(b'foo') + h2 = h.copy() + h.update(b'baz') + h2.update(b'bar') + self.assertEqual( + '21eb6533733a5e4763acacd1d45a60c2e0e404e1', h.hexdigest() + ) + self.assertEqual( + '8843d7f92416211de9ebb963ff4ce28125932878', h2.hexdigest() + ) + + def test_init_hasher(self): + h = self.hasher(b'initial string') + self.assertEqual( + b'\xc9y|n\x1f3S\xa4:\xbaJ\xca,\xc1\x1a\x9e\xb8\xd8\xdd\x86', + h.digest(), + ) + + +class hashlibtests(unittest.TestCase, hashertestsbase): + hasher = hashlib.sha1 + + +if sha1dc: + + class sha1dctests(unittest.TestCase, hashertestsbase): + hasher = sha1dc.sha1 + + +if __name__ == '__main__': + silenttestrunner.main(__name__)