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From 7f65a63b60c6ea86db683ac00e221939f3bb1d47 Mon Sep 17 00:00:00 2001
From: Jeremy Harris <jgh146exb@wizmail.org>
Date: Tue, 25 Oct 2022 21:26:30 +0100
Subject: [PATCH 1/2] OpenSSL: when preloading creds do the server certs before
the OCSP proofs so that the latter can ve verified before loading
---
src/tls-openssl.c | 113 ++++++++++++++++++++++--------------------
1 file changed, 58 insertions(+), 55 deletions(-)
diff --git a/src/tls-openssl.c b/src/tls-openssl.c
index 68ad6f15b..fdf0d92b2 100644
--- a/src/tls-openssl.c
+++ b/src/tls-openssl.c
@@ -441,14 +441,16 @@ exim_openssl_state_st state_server = {.is_server = TRUE};
static int
setup_certs(SSL_CTX *sctx, uschar *certs, uschar *crl, host_item *host,
uschar ** errstr );
/* Callbacks */
#ifndef DISABLE_OCSP
static int tls_server_stapling_cb(SSL *s, void *arg);
+static void x509_stack_dump_cert_s_names(const STACK_OF(X509) * sk);
+static void x509_store_dump_cert_s_names(X509_STORE * store);
#endif
/* Daemon-called, before every connection, key create/rotate */
#ifndef DISABLE_TLS_RESUME
static void tk_init(void);
@@ -1307,15 +1309,14 @@ ocsp_load_response(exim_openssl_state_st * state, const uschar * filename,
{
BIO * bio;
OCSP_RESPONSE * resp;
OCSP_BASICRESP * basic_response;
OCSP_SINGLERESP * single_response;
ASN1_GENERALIZEDTIME * rev, * thisupd, * nextupd;
STACK_OF(X509) * sk;
-unsigned long verify_flags;
int status, reason, i;
DEBUG(D_tls)
debug_printf("tls_ocsp_file (%s) '%s'\n", is_pem ? "PEM" : "DER", filename);
if (!filename || !*filename) return;
@@ -1372,28 +1373,28 @@ if ((status = OCSP_response_status(resp)) != OCSP_RESPONSE_STATUS_SUCCESSFUL)
if (!(basic_response = OCSP_response_get1_basic(resp)))
{
DEBUG(D_tls)
debug_printf("OCSP response parse error: unable to extract basic response.\n");
goto bad;
}
-sk = state->verify_stack;
-verify_flags = OCSP_NOVERIFY; /* check sigs, but not purpose */
+sk = state->verify_stack; /* set by setup_certs() / chain_from_pem_file() */
/* May need to expose ability to adjust those flags?
OCSP_NOSIGS OCSP_NOVERIFY OCSP_NOCHAIN OCSP_NOCHECKS OCSP_NOEXPLICIT
OCSP_TRUSTOTHER OCSP_NOINTERN */
-/* This does a full verify on the OCSP proof before we load it for serving
-up; possibly overkill - just date-checks might be nice enough.
+/* This does a partial verify (only the signer link, not the whole chain-to-CA)
+on the OCSP proof before we load it for serving up; possibly overkill -
+just date-checks might be nice enough.
OCSP_basic_verify takes a "store" arg, but does not
-use it for the chain verification, which is all we do
-when OCSP_NOVERIFY is set. The content from the wire
-"basic_response" and a cert-stack "sk" are all that is used.
+use it for the chain verification, when OCSP_NOVERIFY is set.
+The content from the wire "basic_response" and a cert-stack "sk" are all
+that is used.
We have a stack, loaded in setup_certs() if tls_verify_certificates
was a file (not a directory, or "system"). It is unfortunate we
cannot used the connection context store, as that would neatly
handle the "system" case too, but there seems to be no library
function for getting a stack from a store.
[ In OpenSSL 1.1 - ? X509_STORE_CTX_get0_chain(ctx) ? ]
@@ -1402,15 +1403,15 @@ SNI handling.
Separately we might try to replace using OCSP_basic_verify() - which seems to not
be a public interface into the OpenSSL library (there's no manual entry) -
But what with? We also use OCSP_basic_verify in the client stapling callback.
And there we NEED it; we must verify that status... unless the
library does it for us anyway? */
-if ((i = OCSP_basic_verify(basic_response, sk, NULL, verify_flags)) < 0)
+if ((i = OCSP_basic_verify(basic_response, sk, NULL, OCSP_NOVERIFY)) < 0)
{
DEBUG(D_tls)
{
ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
debug_printf("OCSP response verify failure: %s\n", US ssl_errstring);
}
goto bad;
@@ -1747,61 +1748,18 @@ if (opt_unset_or_noexpand(tls_eccurve))
if (init_ecdh(ctx, &dummy_errstr))
state_server.lib_state.ecdh = TRUE;
}
else
DEBUG(D_tls) debug_printf("TLS: not preloading ECDH curve for server\n");
#if defined(EXIM_HAVE_INOTIFY) || defined(EXIM_HAVE_KEVENT)
-/* If we can, preload the server-side cert, key and ocsp */
-
-if ( opt_set_and_noexpand(tls_certificate)
-# ifndef DISABLE_OCSP
- && opt_unset_or_noexpand(tls_ocsp_file)
-#endif
- && opt_unset_or_noexpand(tls_privatekey))
- {
- /* Set watches on the filenames. The implementation does de-duplication
- so we can just blindly do them all. */
-
- if ( tls_set_watch(tls_certificate, TRUE)
-# ifndef DISABLE_OCSP
- && tls_set_watch(tls_ocsp_file, TRUE)
-#endif
- && tls_set_watch(tls_privatekey, TRUE))
- {
- state_server.certificate = tls_certificate;
- state_server.privatekey = tls_privatekey;
-#ifndef DISABLE_OCSP
- state_server.u_ocsp.server.file = tls_ocsp_file;
-#endif
-
- DEBUG(D_tls) debug_printf("TLS: preloading server certs\n");
- if (tls_expand_session_files(ctx, &state_server, &dummy_errstr) == OK)
- state_server.lib_state.conn_certs = TRUE;
- }
- }
-else if ( !tls_certificate && !tls_privatekey
-# ifndef DISABLE_OCSP
- && !tls_ocsp_file
-#endif
- )
- { /* Generate & preload a selfsigned cert. No files to watch. */
- if (tls_expand_session_files(ctx, &state_server, &dummy_errstr) == OK)
- {
- state_server.lib_state.conn_certs = TRUE;
- lifetime = f.running_in_test_harness ? 2 : 60 * 60; /* 1 hour */
- }
- }
-else
- DEBUG(D_tls) debug_printf("TLS: not preloading server certs\n");
-
-
/* If we can, preload the Authorities for checking client certs against.
Actual choice to do verify is made (tls_{,try_}verify_hosts)
-at TLS conn startup */
+at TLS conn startup.
+Do this before the server ocsp so that its info can verify the ocsp. */
if ( opt_set_and_noexpand(tls_verify_certificates)
&& opt_unset_or_noexpand(tls_crl))
{
/* Watch the default dir also as they are always included */
if ( tls_set_watch(CUS X509_get_default_cert_file(), FALSE)
@@ -1809,18 +1767,63 @@ if ( opt_set_and_noexpand(tls_verify_certificates)
&& tls_set_watch(tls_crl, FALSE))
{
DEBUG(D_tls) debug_printf("TLS: preloading CA bundle for server\n");
if (setup_certs(ctx, tls_verify_certificates, tls_crl, NULL, &dummy_errstr)
== OK)
state_server.lib_state.cabundle = TRUE;
- }
+
+ /* If we can, preload the server-side cert, key and ocsp */
+
+ if ( opt_set_and_noexpand(tls_certificate)
+# ifndef DISABLE_OCSP
+ && opt_unset_or_noexpand(tls_ocsp_file)
+# endif
+ && opt_unset_or_noexpand(tls_privatekey))
+ {
+ /* Set watches on the filenames. The implementation does de-duplication
+ so we can just blindly do them all. */
+
+ if ( tls_set_watch(tls_certificate, TRUE)
+# ifndef DISABLE_OCSP
+ && tls_set_watch(tls_ocsp_file, TRUE)
+# endif
+ && tls_set_watch(tls_privatekey, TRUE))
+ {
+ state_server.certificate = tls_certificate;
+ state_server.privatekey = tls_privatekey;
+#ifndef DISABLE_OCSP
+ state_server.u_ocsp.server.file = tls_ocsp_file;
+# endif
+
+ DEBUG(D_tls) debug_printf("TLS: preloading server certs\n");
+ if (tls_expand_session_files(ctx, &state_server, &dummy_errstr) == OK)
+ state_server.lib_state.conn_certs = TRUE;
+ }
+ }
+ else if ( !tls_certificate && !tls_privatekey
+# ifndef DISABLE_OCSP
+ && !tls_ocsp_file
+# endif
+ )
+ { /* Generate & preload a selfsigned cert. No files to watch. */
+ if (tls_expand_session_files(ctx, &state_server, &dummy_errstr) == OK)
+ {
+ state_server.lib_state.conn_certs = TRUE;
+ lifetime = f.running_in_test_harness ? 2 : 60 * 60; /* 1 hour */
+ }
+ }
+ else
+ DEBUG(D_tls) debug_printf("TLS: not preloading server certs\n");
+ }
}
else
DEBUG(D_tls) debug_printf("TLS: not preloading CA bundle for server\n");
+
+
#endif /* EXIM_HAVE_INOTIFY */
/* If we can, preload the ciphers control string */
if (opt_set_and_noexpand(tls_require_ciphers))
{
--
2.35.1
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