bpo-9216: Add usedforsecurity to hashlib constructors (GH-16044)

The usedforsecurity keyword only argument added to the hash constructors is useful for FIPS builds and similar restrictive environment with non-technical requirements that legacy algorithms be forbidden by their implementations without being explicitly annotated as not being used for any security related purposes.  Linux distros with FIPS support benefit from this being standard rather than making up their own way(s) to do it.

Contributed and Signed-off-by: Christian Heimes christian@python.org

1 files changed, 41 insertions, 13 deletions

diff --git a/Modules/clinic/sha256module.c.h b/Modules/clinic/sha256module.c.h
index 658abb1..2a788ea 100644
--- a/Modules/clinic/sha256module.c.h
+++ b/Modules/clinic/sha256module.c.h
@@ -66,7 +66,7 @@ PyDoc_STRVAR(SHA256Type_update__doc__,
     {"update", (PyCFunction)SHA256Type_update, METH_O, SHA256Type_update__doc__},
 
 PyDoc_STRVAR(_sha256_sha256__doc__,
-"sha256($module, /, string=b\'\')\n"
+"sha256($module, /, string=b\'\', *, usedforsecurity=True)\n"
 "--\n"
 "\n"
 "Return a new SHA-256 hash object; optionally initialized with a string.");
@@ -75,17 +75,18 @@ PyDoc_STRVAR(_sha256_sha256__doc__,
     {"sha256", (PyCFunction)(void(*)(void))_sha256_sha256, METH_FASTCALL|METH_KEYWORDS, _sha256_sha256__doc__},
 
 static PyObject *
-_sha256_sha256_impl(PyObject *module, PyObject *string);
+_sha256_sha256_impl(PyObject *module, PyObject *string, int usedforsecurity);
 
 static PyObject *
 _sha256_sha256(PyObject *module, PyObject *const *args, Py_ssize_t nargs, PyObject *kwnames)
 {
     PyObject *return_value = NULL;
-    static const char * const _keywords[] = {"string", NULL};
+    static const char * const _keywords[] = {"string", "usedforsecurity", NULL};
     static _PyArg_Parser _parser = {NULL, _keywords, "sha256", 0};
-    PyObject *argsbuf[1];
+    PyObject *argsbuf[2];
     Py_ssize_t noptargs = nargs + (kwnames ? PyTuple_GET_SIZE(kwnames) : 0) - 0;
     PyObject *string = NULL;
+    int usedforsecurity = 1;
 
     args = _PyArg_UnpackKeywords(args, nargs, NULL, kwnames, &_parser, 0, 1, 0, argsbuf);
     if (!args) {
@@ -94,16 +95,29 @@ _sha256_sha256(PyObject *module, PyObject *const *args, Py_ssize_t nargs, PyObje
     if (!noptargs) {
         goto skip_optional_pos;
     }
-    string = args[0];
+    if (args[0]) {
+        string = args[0];
+        if (!--noptargs) {
+            goto skip_optional_pos;
+        }
+    }
 skip_optional_pos:
-    return_value = _sha256_sha256_impl(module, string);
+    if (!noptargs) {
+        goto skip_optional_kwonly;
+    }
+    usedforsecurity = PyObject_IsTrue(args[1]);
+    if (usedforsecurity < 0) {
+        goto exit;
+    }
+skip_optional_kwonly:
+    return_value = _sha256_sha256_impl(module, string, usedforsecurity);
 
 exit:
     return return_value;
 }
 
 PyDoc_STRVAR(_sha256_sha224__doc__,
-"sha224($module, /, string=b\'\')\n"
+"sha224($module, /, string=b\'\', *, usedforsecurity=True)\n"
 "--\n"
 "\n"
 "Return a new SHA-224 hash object; optionally initialized with a string.");
@@ -112,17 +126,18 @@ PyDoc_STRVAR(_sha256_sha224__doc__,
     {"sha224", (PyCFunction)(void(*)(void))_sha256_sha224, METH_FASTCALL|METH_KEYWORDS, _sha256_sha224__doc__},
 
 static PyObject *
-_sha256_sha224_impl(PyObject *module, PyObject *string);
+_sha256_sha224_impl(PyObject *module, PyObject *string, int usedforsecurity);
 
 static PyObject *
 _sha256_sha224(PyObject *module, PyObject *const *args, Py_ssize_t nargs, PyObject *kwnames)
 {
     PyObject *return_value = NULL;
-    static const char * const _keywords[] = {"string", NULL};
+    static const char * const _keywords[] = {"string", "usedforsecurity", NULL};
     static _PyArg_Parser _parser = {NULL, _keywords, "sha224", 0};
-    PyObject *argsbuf[1];
+    PyObject *argsbuf[2];
     Py_ssize_t noptargs = nargs + (kwnames ? PyTuple_GET_SIZE(kwnames) : 0) - 0;
     PyObject *string = NULL;
+    int usedforsecurity = 1;
 
     args = _PyArg_UnpackKeywords(args, nargs, NULL, kwnames, &_parser, 0, 1, 0, argsbuf);
     if (!args) {
@@ -131,11 +146,24 @@ _sha256_sha224(PyObject *module, PyObject *const *args, Py_ssize_t nargs, PyObje
     if (!noptargs) {
         goto skip_optional_pos;
     }
-    string = args[0];
+    if (args[0]) {
+        string = args[0];
+        if (!--noptargs) {
+            goto skip_optional_pos;
+        }
+    }
 skip_optional_pos:
-    return_value = _sha256_sha224_impl(module, string);
+    if (!noptargs) {
+        goto skip_optional_kwonly;
+    }
+    usedforsecurity = PyObject_IsTrue(args[1]);
+    if (usedforsecurity < 0) {
+        goto exit;
+    }
+skip_optional_kwonly:
+    return_value = _sha256_sha224_impl(module, string, usedforsecurity);
 
 exit:
     return return_value;
 }
-/*[clinic end generated code: output=c54d0956ec88409d input=a9049054013a1b77]*/
+/*[clinic end generated code: output=c8cca8adbe72ec9a input=a9049054013a1b77]*/