From 529311e4390a72bf500662ee9567d9113c1d0aec Mon Sep 17 00:00:00 2001 From: David Benjamin Date: Sat, 6 Jan 2024 23:01:08 -0500 Subject: [PATCH 1/4] gh-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 https://github.com/openssl/openssl/pull/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. --- Modules/_ssl.c | 58 +++++++++++++++++++++++++++++++++++++++++++++----- 1 file changed, 53 insertions(+), 5 deletions(-) diff --git a/Modules/_ssl.c b/Modules/_ssl.c index bc302909424227..c1461bcd5902e4 100644 --- a/Modules/_ssl.c +++ b/Modules/_ssl.c @@ -4553,6 +4553,48 @@ set_sni_callback(PySSLContext *self, PyObject *arg, void *c) return 0; } +#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: + ok = X509_OBJECT_set1_X509_CRL(ret, X509_OBJECT_get0_X509_CRL(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\ @@ -4582,7 +4624,12 @@ _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)) { @@ -4596,12 +4643,11 @@ _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); } @@ -4633,7 +4679,7 @@ _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); for (i = 0; i < sk_X509_OBJECT_num(objs); i++) { X509_OBJECT *obj; X509 *cert; @@ -4661,9 +4707,11 @@ _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; From 27d984a9f9357e1334a7110ed68358f673a9cbf5 Mon Sep 17 00:00:00 2001 From: David Benjamin Date: Fri, 26 Jan 2024 22:07:45 -0500 Subject: [PATCH 2/4] Work around const-correctness problem --- Modules/_ssl.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/Modules/_ssl.c b/Modules/_ssl.c index c1461bcd5902e4..9f897a2892eb8e 100644 --- a/Modules/_ssl.c +++ b/Modules/_ssl.c @@ -4566,7 +4566,9 @@ static X509_OBJECT *x509_object_dup(const X509_OBJECT *obj) ok = X509_OBJECT_set1_X509(ret, X509_OBJECT_get0_X509(obj)); break; case X509_LU_CRL: - ok = X509_OBJECT_set1_X509_CRL(ret, X509_OBJECT_get0_X509_CRL(obj)); + /* 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 From a0b15011f53f207c655fe18e0a0d74214b867d82 Mon Sep 17 00:00:00 2001 From: David Benjamin Date: Fri, 26 Jan 2024 22:09:42 -0500 Subject: [PATCH 3/4] Add missing X509_STORE_get1_objects failure check --- Modules/_ssl.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/Modules/_ssl.c b/Modules/_ssl.c index 9f897a2892eb8e..950ee3663080e1 100644 --- a/Modules/_ssl.c +++ b/Modules/_ssl.c @@ -4682,6 +4682,11 @@ _ssl__SSLContext_get_ca_certs_impl(PySSLContext *self, int binary_form) store = SSL_CTX_get_cert_store(self->ctx); 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; From 549ae877540243458fcd7951164e3d736fe92b42 Mon Sep 17 00:00:00 2001 From: David Benjamin Date: Fri, 26 Jan 2024 22:14:20 -0500 Subject: [PATCH 4/4] Add blurb --- .../Security/2024-01-26-22-14-09.gh-issue-114572.t1QMQD.rst | 4 ++++ 1 file changed, 4 insertions(+) create mode 100644 Misc/NEWS.d/next/Security/2024-01-26-22-14-09.gh-issue-114572.t1QMQD.rst diff --git a/Misc/NEWS.d/next/Security/2024-01-26-22-14-09.gh-issue-114572.t1QMQD.rst b/Misc/NEWS.d/next/Security/2024-01-26-22-14-09.gh-issue-114572.t1QMQD.rst new file mode 100644 index 00000000000000..b4f9fe64db0615 --- /dev/null +++ b/Misc/NEWS.d/next/Security/2024-01-26-22-14-09.gh-issue-114572.t1QMQD.rst @@ -0,0 +1,4 @@ +:meth:`ssl.SSLContext.cert_store_stats` and +:meth:`ssl.SSLContext.get_ca_certs` now correctly lock access to the +certificate store, when the :class:`ssl.SSLContext` is shared across +multiple threads.