[exim-cvs] OpenSSL: fail the handshake when SNI processing h…

Gitweb: https://git.exim.org/exim.git/commitdiff/5a2a0989efb831472f8edf5c4991953e6140c3ad

Commit:     5a2a0989efb831472f8edf5c4991953e6140c3ad
Parent:     6aac3239b4ce9638c2c5647684dc4ff2a6afbb42
Author:     Jeremy Harris <jgh146exb@???>
AuthorDate: Wed Nov 28 20:54:53 2018 +0000
Committer:  Jeremy Harris <jgh146exb@???>
CommitDate: Wed Nov 28 21:41:25 2018 +0000

    OpenSSL: fail the handshake when SNI processing hits a problem
---
 doc/doc-txt/ChangeLog |  3 +++
 src/src/tls-openssl.c | 23 +++++++++++++----------
 2 files changed, 16 insertions(+), 10 deletions(-)

diff --git a/doc/doc-txt/ChangeLog b/doc/doc-txt/ChangeLog
index 1bf6110..d006d9d 100644
--- a/doc/doc-txt/ChangeLog
+++ b/doc/doc-txt/ChangeLog
@@ -160,6 +160,9 @@ JH/34 Increase RSA keysize of autogen selfsign cert from 1024 to 2048.  RHEL 8.0
       more-modern GnuTLS move from GNUTLS_SEC_PARAM_LOW to
       GNUTLS_SEC_PARAM_MEDIUM.

+JH/35 OpenSSL: fail the handshake when SNI processing hits a problem, server
+      side.  Previously we would continue as if no SNI had been received.
+

Exim version 4.91
-----------------
diff --git a/src/src/tls-openssl.c b/src/src/tls-openssl.c
index cd11f65..8a1fec6 100644
--- a/src/src/tls-openssl.c
+++ b/src/src/tls-openssl.c
@@ -370,7 +370,9 @@ if (!msg)
msg = US ssl_errstring;
}

-if (errstr) *errstr = string_sprintf("(%s): %s", prefix, msg);
+msg = string_sprintf("(%s): %s", prefix, msg);
+DEBUG(D_tls) debug_printf("TLS error '%s'\n", msg);
+if (errstr) *errstr = msg;
return host ? FAIL : DEFER;
}

@@ -1302,8 +1304,8 @@ else
       if ((err = tls_add_certfile(sctx, cbinfo, expanded, errstr)))
     return err;

-  if (cbinfo->privatekey != NULL &&
-      !expand_check(cbinfo->privatekey, US"tls_privatekey", &expanded, errstr))
+  if (  cbinfo->privatekey
+     && !expand_check(cbinfo->privatekey, US"tls_privatekey", &expanded, errstr))
     return DEFER;

/* If expansion was forced to fail, key_expanded will be NULL. If the result
@@ -1406,7 +1408,7 @@ if (!(server_sni = SSL_CTX_new(SSLv23_server_method())))
{
ERR_error_string_n(ERR_get_error(), ssl_errstring, sizeof(ssl_errstring));
DEBUG(D_tls) debug_printf("SSL_CTX_new() failed: %s\n", ssl_errstring);
- return SSL_TLSEXT_ERR_NOACK;
+ goto bad;
}

 /* Not sure how many of these are actually needed, since SSL object
@@ -1422,11 +1424,11 @@ SSL_CTX_set_tlsext_servername_arg(server_sni, cbinfo);
 if (  !init_dh(server_sni, cbinfo->dhparam, NULL, &dummy_errstr)
    || !init_ecdh(server_sni, NULL, &dummy_errstr)
    )
-  return SSL_TLSEXT_ERR_NOACK;
+  goto bad;

 if (  cbinfo->server_cipher_list
    && !SSL_CTX_set_cipher_list(server_sni, CS cbinfo->server_cipher_list))
-  return SSL_TLSEXT_ERR_NOACK;
+  goto bad;

#ifndef DISABLE_OCSP
if (cbinfo->u_ocsp.server.file)
@@ -1438,17 +1440,18 @@ if (cbinfo->u_ocsp.server.file)

 if ((rc = setup_certs(server_sni, tls_verify_certificates, tls_crl, NULL, FALSE,
               verify_callback_server, &dummy_errstr)) != OK)
-  return SSL_TLSEXT_ERR_NOACK;
+  goto bad;

/* do this after setup_certs, because this can require the certs for verifying
OCSP information. */
if ((rc = tls_expand_session_files(server_sni, cbinfo, &dummy_errstr)) != OK)
- return SSL_TLSEXT_ERR_NOACK;
+ goto bad;

DEBUG(D_tls) debug_printf("Switching SSL context.\n");
SSL_set_SSL_CTX(s, server_sni);
-
return SSL_TLSEXT_ERR_OK;
+
+bad: return SSL_TLSEXT_ERR_ALERT_FATAL;
}
#endif /* EXIM_HAVE_OPENSSL_TLSEXT */

@@ -2124,7 +2127,7 @@ if (expcerts && *expcerts)
/* If verification is optional, don't fail if no certificate */

   SSL_CTX_set_verify(sctx,
-    SSL_VERIFY_PEER | (optional? 0 : SSL_VERIFY_FAIL_IF_NO_PEER_CERT),
+    SSL_VERIFY_PEER | (optional ? 0 : SSL_VERIFY_FAIL_IF_NO_PEER_CERT),
     cert_vfy_cb);
   }