From e7011813a2b8f078182d29c252ea728b1ef163d8 Mon Sep 17 00:00:00 2001 From: Seth Michael Larson Date: Fri, 19 Apr 2024 11:21:40 -0700 Subject: [PATCH] [CVE-2024-0397] 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 gh#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. From-PR: gh#python/cpython!114573 Fixes: gh#python/cpython#114572 Fixes: bsc#1226447 (CVE-2024-0397) Patch: CVE-2024-0397-memrace_ssl.SSLContext_cert_store.patch --- ...-04-19-11-21-13.gh-issue-114572.t1QMQD.rst | 4 + Modules/_ssl.c | 98 ++++++++++++++++++- 2 files changed, 99 insertions(+), 3 deletions(-) create mode 100644 Misc/NEWS.d/next/Security/2024-04-19-11-21-13.gh-issue-114572.t1QMQD.rst diff --git a/Misc/NEWS.d/next/Security/2024-04-19-11-21-13.gh-issue-114572.t1QMQD.rst b/Misc/NEWS.d/next/Security/2024-04-19-11-21-13.gh-issue-114572.t1QMQD.rst new file mode 100644 index 00000000000000..b4f9fe64db0615 --- /dev/null +++ b/Misc/NEWS.d/next/Security/2024-04-19-11-21-13.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. diff --git a/Modules/_ssl.c b/Modules/_ssl.c index 7365630a5eaf1c..aafca11016ea40 100644 --- a/Modules/_ssl.c +++ b/Modules/_ssl.c @@ -124,6 +124,10 @@ struct py_ssl_library_code { # define HAVE_TLSv1_2 0 #endif +#if (OPENSSL_VERSION_NUMBER >= 0x30300000L) && !defined(LIBRESSL_VERSION_NUMBER) +# define OPENSSL_VERSION_3_3 1 +#endif + /* SNI support (client- and server-side) appeared in OpenSSL 1.0.0 and 0.9.8f * This includes the SSL_set_SSL_CTX() function. */ @@ -164,6 +168,16 @@ struct py_ssl_library_code { #define HAVE_OPENSSL_CRYPTO_LOCK #endif +/* OpenSSL 1.1+ allows locking X509_STORE, 1.0.2 doesn't. */ +#ifdef OPENSSL_VERSION_1_1 +#define HAVE_OPENSSL_X509_STORE_LOCK +#endif + +/* OpenSSL 3.3 added the X509_STORE_get1_objects API */ +#ifdef OPENSSL_VERSION_3_3 +#define HAVE_OPENSSL_X509_STORE_GET1_OBJECTS 1 +#endif + #if defined(OPENSSL_VERSION_1_1) && !defined(OPENSSL_NO_SSL2) #define OPENSSL_NO_SSL2 #endif @@ -4096,6 +4110,61 @@ _ssl__SSLContext_set_servername_callback(PySSLContext *self, PyObject *cb) #endif } +/* Shim of X509_STORE_get1_objects API from OpenSSL 3.3 + * Only available with the X509_STORE_lock() API */ +#if defined(HAVE_OPENSSL_X509_STORE_LOCK) && !defined(OPENSSL_VERSION_3_3) +#define HAVE_OPENSSL_X509_STORE_GET1_OBJECTS 1 + +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\ +If the argument is None then the callback is disabled. The method is called\n\ +with the SSLSocket, the server name as a string, and the SSLContext object.\n\ +See RFC 6066 for details of the SNI extension."); + /*[clinic input] _ssl._SSLContext.cert_store_stats @@ -4118,7 +4187,15 @@ _ssl__SSLContext_cert_store_stats_impl(PySSLContext *self) int x509 = 0, crl = 0, ca = 0, i; store = SSL_CTX_get_cert_store(self->ctx); +#if HAVE_OPENSSL_X509_STORE_GET1_OBJECTS + objs = X509_STORE_get1_objects(store); + if (objs == NULL) { + PyErr_SetString(PyExc_MemoryError, "failed to query cert store"); + return NULL; + } +#else objs = X509_STORE_get0_objects(store); +#endif for (i = 0; i < sk_X509_OBJECT_num(objs); i++) { obj = sk_X509_OBJECT_value(objs, i); switch (X509_OBJECT_get_type(obj)) { @@ -4132,12 +4209,13 @@ _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; } } +#if HAVE_OPENSSL_X509_STORE_GET1_OBJECTS + sk_X509_OBJECT_pop_free(objs, X509_OBJECT_free); +#endif return Py_BuildValue("{sisisi}", "x509", x509, "crl", crl, "x509_ca", ca); } @@ -4169,7 +4247,15 @@ _ssl__SSLContext_get_ca_certs_impl(PySSLContext *self, int binary_form) } store = SSL_CTX_get_cert_store(self->ctx); +#if HAVE_OPENSSL_X509_STORE_GET1_OBJECTS + objs = X509_STORE_get1_objects(store); + if (objs == NULL) { + PyErr_SetString(PyExc_MemoryError, "failed to query cert store"); + return NULL; + } +#else objs = X509_STORE_get0_objects(store); +#endif for (i = 0; i < sk_X509_OBJECT_num(objs); i++) { X509_OBJECT *obj; X509 *cert; @@ -4197,9 +4283,15 @@ _ssl__SSLContext_get_ca_certs_impl(PySSLContext *self, int binary_form) } Py_CLEAR(ci); } +#if HAVE_OPENSSL_X509_STORE_GET1_OBJECTS + sk_X509_OBJECT_pop_free(objs, X509_OBJECT_free); +#endif return rlist; error: +#if HAVE_OPENSSL_X509_STORE_GET1_OBJECTS + sk_X509_OBJECT_pop_free(objs, X509_OBJECT_free); +#endif Py_XDECREF(ci); Py_XDECREF(rlist); return NULL;