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[3.10] pythongh-114572: Fix locking in cert_store_stats and get_ca_ce…
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…rts (pythonGH-114573) (python#115548)

pythongh-114572: Fix locking in cert_store_stats and get_ca_certs (pythonGH-114573)

* pythongh-114572: Fix locking in cert_store_stats and get_ca_certs

cert_store_stats and get_ca_certs query the SSLContext's X509_STORE with
X509_STORE_get0_objects, but reading the result requires a lock. See
openssl/openssl#23224 for details.

Instead, use X509_STORE_get1_objects, newly added in that PR.
X509_STORE_get1_objects does not exist in current OpenSSLs, but we can
polyfill it with X509_STORE_lock and X509_STORE_unlock.

* Work around const-correctness problem

* Add missing X509_STORE_get1_objects failure check

* Add blurb
(cherry picked from commit bce6931)

Co-authored-by: David Benjamin <davidben@google.com>
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2 people authored and mgorny committed Apr 10, 2024
1 parent c8be6c6 commit 8ed9d5e
Showing 1 changed file with 60 additions and 5 deletions.
65 changes: 60 additions & 5 deletions Modules/_ssl.c
Original file line number Diff line number Diff line change
Expand Up @@ -4715,6 +4715,50 @@ set_sni_callback(PySSLContext *self, PyObject *arg, void *c)
#endif
}

#if OPENSSL_VERSION_NUMBER < 0x30300000L
static X509_OBJECT *x509_object_dup(const X509_OBJECT *obj)
{
int ok;
X509_OBJECT *ret = X509_OBJECT_new();
if (ret == NULL) {
return NULL;
}
switch (X509_OBJECT_get_type(obj)) {
case X509_LU_X509:
ok = X509_OBJECT_set1_X509(ret, X509_OBJECT_get0_X509(obj));
break;
case X509_LU_CRL:
/* X509_OBJECT_get0_X509_CRL was not const-correct prior to 3.0.*/
ok = X509_OBJECT_set1_X509_CRL(
ret, X509_OBJECT_get0_X509_CRL((X509_OBJECT *)obj));
break;
default:
/* We cannot duplicate unrecognized types in a polyfill, but it is
* safe to leave an empty object. The caller will ignore it. */
ok = 1;
break;
}
if (!ok) {
X509_OBJECT_free(ret);
return NULL;
}
return ret;
}

static STACK_OF(X509_OBJECT) *
X509_STORE_get1_objects(X509_STORE *store)
{
STACK_OF(X509_OBJECT) *ret;
if (!X509_STORE_lock(store)) {
return NULL;
}
ret = sk_X509_OBJECT_deep_copy(X509_STORE_get0_objects(store),
x509_object_dup, X509_OBJECT_free);
X509_STORE_unlock(store);
return ret;
}
#endif

PyDoc_STRVAR(PySSLContext_sni_callback_doc,
"Set a callback that will be called when a server name is provided by the SSL/TLS client in the SNI extension.\n\
\n\
Expand Down Expand Up @@ -4744,7 +4788,12 @@ _ssl__SSLContext_cert_store_stats_impl(PySSLContext *self)
int x509 = 0, crl = 0, ca = 0, i;

store = SSL_CTX_get_cert_store(self->ctx);
objs = X509_STORE_get0_objects(store);
objs = X509_STORE_get1_objects(store);
if (objs == NULL) {
PyErr_SetString(PyExc_MemoryError, "failed to query cert store");
return NULL;
}

for (i = 0; i < sk_X509_OBJECT_num(objs); i++) {
obj = sk_X509_OBJECT_value(objs, i);
switch (X509_OBJECT_get_type(obj)) {
Expand All @@ -4758,12 +4807,11 @@ _ssl__SSLContext_cert_store_stats_impl(PySSLContext *self)
crl++;
break;
default:
/* Ignore X509_LU_FAIL, X509_LU_RETRY, X509_LU_PKEY.
* As far as I can tell they are internal states and never
* stored in a cert store */
/* Ignore unrecognized types. */
break;
}
}
sk_X509_OBJECT_pop_free(objs, X509_OBJECT_free);
return Py_BuildValue("{sisisi}", "x509", x509, "crl", crl,
"x509_ca", ca);
}
Expand Down Expand Up @@ -4795,7 +4843,12 @@ _ssl__SSLContext_get_ca_certs_impl(PySSLContext *self, int binary_form)
}

store = SSL_CTX_get_cert_store(self->ctx);
objs = X509_STORE_get0_objects(store);
objs = X509_STORE_get1_objects(store);
if (objs == NULL) {
PyErr_SetString(PyExc_MemoryError, "failed to query cert store");
goto error;
}

for (i = 0; i < sk_X509_OBJECT_num(objs); i++) {
X509_OBJECT *obj;
X509 *cert;
Expand Down Expand Up @@ -4823,9 +4876,11 @@ _ssl__SSLContext_get_ca_certs_impl(PySSLContext *self, int binary_form)
}
Py_CLEAR(ci);
}
sk_X509_OBJECT_pop_free(objs, X509_OBJECT_free);
return rlist;

error:
sk_X509_OBJECT_pop_free(objs, X509_OBJECT_free);
Py_XDECREF(ci);
Py_XDECREF(rlist);
return NULL;
Expand Down

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