vulnerability workaround (included in SSL_OP_ALL).
PR: #90
By default, clients may request session resumption even during
renegotiation (if session ID contexts permit); with this option,
session resumption is possible only in the first handshake.
+
+ SSL_OP_ALL is now 0x00000FFFL instead of 0x000FFFFFL. This makes
+ more bits available for options that should not be part of
+ SSL_OP_ALL (such as SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION).
[Bodo Moeller]
*) Add some demos for certificate and certificate request creation.
*) Fix EVP_dsa_sha macro.
[Nils Larsch]
+ *) New option
+ SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS
+ for disabling the SSL 3.0/TLS 1.0 CBC vulnerability countermeasure
+ that was added in OpenSSL 0.9.6d.
+
+ As the countermeasure turned out to be incompatible with some
+ broken SSL implementations, the new option is part of SSL_OP_ALL.
+ SSL_OP_ALL is usually employed when compatibility with weird SSL
+ implementations is desired (e.g. '-bugs' option to 's_client' and
+ 's_server'), so the new option is automatically set in many
+ applications.
+ [Bodo Moeller]
+
Changes between 0.9.6c and 0.9.6d [9 May 2002]
*) Fix crypto/asn1/a_sign.c so that 'parameters' is omitted (not
...
+=item SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS
+
+Disables a countermeasure against a SSL 3.0/TLS 1.0 protocol
+vulnerability affecting CBC ciphers, which cannot be handled by some
+broken SSL implementations. This option has no effect for connections
+using other ciphers.
+
=item SSL_OP_ALL
All of the above bug workarounds.
=back
-It is safe and recommended to use B<SSL_OP_ALL> to enable the bug workaround
-options.
+It is usually safe to use B<SSL_OP_ALL> to enable the bug workaround
+options if compatibility with somewhat broken implementations is
+desired.
The following B<modifying> options are available:
enabled with B<SSL_OP_ALL>. As of 0.9.7, it is no longer included in B<SSL_OP_ALL>
and must be explicitly set.
+B<SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS> has been added in OpenSSL 0.9.6e.
+Versions up to OpenSSL 0.9.6c do not include the countermeasure that
+can be disabled with this option (in OpenSSL 0.9.6d, it was always
+enabled).
+
=cut
ret = ssl3_generate_key_block(s,p,num);
- /* enable vulnerability countermeasure for CBC ciphers with
- * known-IV problem (http://www.openssl.org/~bodo/tls-cbc.txt) */
- s->s3->need_empty_fragments = 1;
+ if (!(s->options & SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS))
+ {
+ /* enable vulnerability countermeasure for CBC ciphers with
+ * known-IV problem (http://www.openssl.org/~bodo/tls-cbc.txt)
+ */
+ s->s3->need_empty_fragments = 1;
+
#ifndef OPENSSL_NO_RC4
- if ((s->session->cipher != NULL) && ((s->session->cipher->algorithms & SSL_ENC_MASK) == SSL_RC4))
- s->s3->need_empty_fragments = 0;
+ if ((s->session->cipher != NULL) && ((s->session->cipher->algorithms & SSL_ENC_MASK) == SSL_RC4))
+ s->s3->need_empty_fragments = 0;
#endif
+ }
return ret;
struct ssl_session_st *prev,*next;
} SSL_SESSION;
+
#define SSL_OP_MICROSOFT_SESS_ID_BUG 0x00000001L
#define SSL_OP_NETSCAPE_CHALLENGE_BUG 0x00000002L
#define SSL_OP_NETSCAPE_REUSE_CIPHER_CHANGE_BUG 0x00000008L
#define SSL_OP_TLS_D5_BUG 0x00000100L
#define SSL_OP_TLS_BLOCK_PADDING_BUG 0x00000200L
+/* Disable SSL 3.0/TLS 1.0 CBC vulnerability workaround that was added
+ * in OpenSSL 0.9.6d. Usually (depending on the application protocol)
+ * the workaround is not needed. Unfortunately some broken SSL/TLS
+ * implementations cannot handle it at all, which is why we include
+ * it in SSL_OP_ALL. */
+#define SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS 0x00000800L /* added in 0.9.6e */
+
+/* SSL_OP_ALL: various bug workarounds that should be rather harmless.
+ * This used to be 0x000FFFFFL before 0.9.7. */
+#define SSL_OP_ALL 0x00000FFFL
+
+/* As server, disallow session resumption on renegotiation */
+#define SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION 0x00010000L
/* If set, always create a new key when using tmp_dh parameters */
#define SSL_OP_SINGLE_DH_USE 0x00100000L
/* Set to always use the tmp_rsa key when doing RSA operations,
* (version 3.1) was announced in the client hello. Normally this is
* forbidden to prevent version rollback attacks. */
#define SSL_OP_TLS_ROLLBACK_BUG 0x00800000L
-/* As server, disallow session resumption on renegotiation */
-#define SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION 0x01000000L
+
+#define SSL_OP_NO_SSLv2 0x01000000L
+#define SSL_OP_NO_SSLv3 0x02000000L
+#define SSL_OP_NO_TLSv1 0x04000000L
/* The next flag deliberately changes the ciphertest, this is a check
* for the PKCS#1 attack */
#define SSL_OP_PKCS1_CHECK_2 0x10000000L
#define SSL_OP_NETSCAPE_CA_DN_BUG 0x20000000L
#define SSL_OP_NETSCAPE_DEMO_CIPHER_CHANGE_BUG 0x40000000L
-#define SSL_OP_ALL 0x000FFFFFL
-#define SSL_OP_NO_SSLv2 0x01000000L
-#define SSL_OP_NO_SSLv3 0x02000000L
-#define SSL_OP_NO_TLSv1 0x04000000L
/* Allow SSL_write(..., n) to return r with 0 < r < n (i.e. report success
* when just a single record has been written): */
* is blocking: */
#define SSL_MODE_AUTO_RETRY 0x00000004L
+
/* Note: SSL[_CTX]_set_{options,mode} use |= op on the previous value,
* they cannot be used to clear bits. */
{ int z; for (z=0; z<num; z++) printf("%02X%c",p1[z],((z+1)%16)?' ':'\n'); }
#endif
- /* enable vulnerability countermeasure for CBC ciphers with
- * known-IV problem (http://www.openssl.org/~bodo/tls-cbc.txt) */
- s->s3->need_empty_fragments = 1;
+ if (!(s->options & SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS))
+ {
+ /* enable vulnerability countermeasure for CBC ciphers with
+ * known-IV problem (http://www.openssl.org/~bodo/tls-cbc.txt)
+ */
+ s->s3->need_empty_fragments = 1;
+
#ifndef NO_RC4
- if ((s->session->cipher != NULL) && ((s->session->cipher->algorithms & SSL_ENC_MASK) == SSL_RC4))
- s->s3->need_empty_fragments = 0;
+ if ((s->session->cipher != NULL) && ((s->session->cipher->algorithms & SSL_ENC_MASK) == SSL_RC4))
+ s->s3->need_empty_fragments = 0;
#endif
+ }
return(1);
err:
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