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openssl/Avoid-errors-with-a-priori-inapplicable-protocol-bou.patch

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From c6c9f886ae118fffb0591ea0b5c3e4770b176552 Mon Sep 17 00:00:00 2001
From: Viktor Dukhovni <openssl-users@dukhovni.org>
Date: Thu, 16 Jul 2020 23:30:43 -0200
Subject: [PATCH 054/147] Avoid errors with a priori inapplicable protocol
bounds
The 'MinProtocol' and 'MaxProtocol' configuration commands now silently
ignore TLS protocol version bounds when configurign DTLS-based contexts,
and conversely, silently ignore DTLS protocol version bounds when
configuring TLS-based contexts. The commands can be repeated to set
bounds of both types. The same applies with the corresponding
"min_protocol" and "max_protocol" command-line switches, in case some
application uses both TLS and DTLS.
SSL_CTX instances that are created for a fixed protocol version (e.g.
TLSv1_server_method()) also silently ignore version bounds. Previously
attempts to apply bounds to these protocol versions would result in an
error. Now only the "version-flexible" SSL_CTX instances are subject to
limits in configuration files in command-line options.
Expected to resolve #12394
Reviewed-by: Paul Dale <paul.dale@oracle.com>
Reviewed-by: Matt Caswell <matt@openssl.org>
GH: #12507
---
doc/man3/SSL_CONF_cmd.pod | 29 ++++++++++++++++++++---------
doc/man5/config.pod | 15 +++++++++------
ssl/ssl_conf.c | 7 +++++++
ssl/statem/statem_lib.c | 34 +++++++++++++++++++---------------
4 files changed, 55 insertions(+), 30 deletions(-)
diff --git a/doc/man3/SSL_CONF_cmd.pod b/doc/man3/SSL_CONF_cmd.pod
index 7f2449e..c5fed8e 100644
--- a/doc/man3/SSL_CONF_cmd.pod
+++ b/doc/man3/SSL_CONF_cmd.pod
@@ -147,13 +147,16 @@ B<SSL_OP_NO_RENEGOTIATION>.
=item B<-min_protocol>, B<-max_protocol>
Sets the minimum and maximum supported protocol.
-Currently supported protocol values are B<SSLv3>, B<TLSv1>,
-B<TLSv1.1>, B<TLSv1.2>, B<TLSv1.3> for TLS and B<DTLSv1>, B<DTLSv1.2> for DTLS,
-and B<None> for no limit.
-If either bound is not specified then only the other bound applies,
-if specified.
-To restrict the supported protocol versions use these commands rather
-than the deprecated alternative commands below.
+Currently supported protocol values are B<SSLv3>, B<TLSv1>, B<TLSv1.1>,
+B<TLSv1.2>, B<TLSv1.3> for TLS; B<DTLSv1>, B<DTLSv1.2> for DTLS, and B<None>
+for no limit.
+If either the lower or upper bound is not specified then only the other bound
+applies, if specified.
+If your application supports both TLS and DTLS you can specify any of these
+options twice, once with a bound for TLS and again with an appropriate bound
+for DTLS.
+To restrict the supported protocol versions use these commands rather than the
+deprecated alternative commands below.
=item B<-no_ssl3>, B<-no_tls1>, B<-no_tls1_1>, B<-no_tls1_2>, B<-no_tls1_3>
@@ -370,7 +373,11 @@ This sets the minimum supported SSL, TLS or DTLS version.
Currently supported protocol values are B<SSLv3>, B<TLSv1>, B<TLSv1.1>,
B<TLSv1.2>, B<TLSv1.3>, B<DTLSv1> and B<DTLSv1.2>.
-The value B<None> will disable the limit.
+The SSL and TLS bounds apply only to TLS-based contexts, while the DTLS bounds
+apply only to DTLS-based contexts.
+The command can be repeated with one instance setting a TLS bound, and the
+other setting a DTLS bound.
+The value B<None> applies to both types of contexts and disables the limits.
=item B<MaxProtocol>
@@ -378,7 +385,11 @@ This sets the maximum supported SSL, TLS or DTLS version.
Currently supported protocol values are B<SSLv3>, B<TLSv1>, B<TLSv1.1>,
B<TLSv1.2>, B<TLSv1.3>, B<DTLSv1> and B<DTLSv1.2>.
-The value B<None> will disable the limit.
+The SSL and TLS bounds apply only to TLS-based contexts, while the DTLS bounds
+apply only to DTLS-based contexts.
+The command can be repeated with one instance setting a TLS bound, and the
+other setting a DTLS bound.
+The value B<None> applies to both types of contexts and disables the limits.
=item B<Protocol>
diff --git a/doc/man5/config.pod b/doc/man5/config.pod
index 7b50b09..7a0459d 100644
--- a/doc/man5/config.pod
+++ b/doc/man5/config.pod
@@ -262,13 +262,11 @@ Example of a configuration with the system default:
ssl_conf = ssl_sect
[ssl_sect]
-
system_default = system_default_sect
[system_default_sect]
-
MinProtocol = TLSv1.2
-
+ MinProtocol = DTLSv1.2
=head1 NOTES
@@ -355,8 +353,8 @@ Simple OpenSSL library configuration example to enter FIPS mode:
Note: in the above example you will get an error in non FIPS capable versions
of OpenSSL.
-Simple OpenSSL library configuration to make TLS 1.3 the system-default
-minimum TLS version:
+Simple OpenSSL library configuration to make TLS 1.2 and DTLS 1.2 the
+system-default minimum TLS and DTLS versions, respectively:
# Toplevel section for openssl (including libssl)
openssl_conf = default_conf_section
@@ -369,7 +367,12 @@ minimum TLS version:
system_default = system_default_section
[system_default_section]
- MinProtocol = TLSv1.3
+ MinProtocol = TLSv1.2
+ MinProtocol = DTLSv1.2
+
+The minimum TLS protocol is applied to B<SSL_CTX> objects that are TLS-based,
+and the minimum DTLS protocol to those are DTLS-based.
+The same applies also to maximum versions set with B<MaxProtocol>.
More complex OpenSSL library configuration. Add OID and don't enter FIPS mode:
diff --git a/ssl/ssl_conf.c b/ssl/ssl_conf.c
index 8ef29bb..3890d16 100644
--- a/ssl/ssl_conf.c
+++ b/ssl/ssl_conf.c
@@ -305,6 +305,13 @@ static int protocol_from_string(const char *value)
const char *name;
int version;
};
+ /*
+ * Note: To avoid breaking previously valid configurations, we must retain
+ * legacy entries in this table even if the underlying protocol is no
+ * longer supported. This also means that the constants SSL3_VERSION, ...
+ * need to be retained indefinitely. This table can only grow, never
+ * shrink.
+ */
static const struct protocol_versions versions[] = {
{"None", 0},
{"SSLv3", SSL3_VERSION},
diff --git a/ssl/statem/statem_lib.c b/ssl/statem/statem_lib.c
index 43d6fd5..0c5ba28 100644
--- a/ssl/statem/statem_lib.c
+++ b/ssl/statem/statem_lib.c
@@ -1656,11 +1656,22 @@ int ssl_check_version_downgrade(SSL *s)
*/
int ssl_set_version_bound(int method_version, int version, int *bound)
{
+ int valid_tls;
+ int valid_dtls;
+
if (version == 0) {
*bound = version;
return 1;
}
+ valid_tls = version >= SSL3_VERSION && version <= TLS_MAX_VERSION;
+ valid_dtls =
+ DTLS_VERSION_LE(version, DTLS_MAX_VERSION) &&
+ DTLS_VERSION_GE(version, DTLS1_BAD_VER);
+
+ if (!valid_tls && !valid_dtls)
+ return 0;
+
/*-
* Restrict TLS methods to TLS protocol versions.
* Restrict DTLS methods to DTLS protocol versions.
@@ -1671,31 +1682,24 @@ int ssl_set_version_bound(int method_version, int version, int *bound)
* configurations. If the MIN (supported) version ever rises, the user's
* "floor" remains valid even if no longer available. We don't expect the
* MAX ceiling to ever get lower, so making that variable makes sense.
+ *
+ * We ignore attempts to set bounds on version-inflexible methods,
+ * returning success.
*/
switch (method_version) {
default:
- /*
- * XXX For fixed version methods, should we always fail and not set any
- * bounds, always succeed and not set any bounds, or set the bounds and
- * arrange to fail later if they are not met? At present fixed-version
- * methods are not subject to controls that disable individual protocol
- * versions.
- */
- return 0;
+ break;
case TLS_ANY_VERSION:
- if (version < SSL3_VERSION || version > TLS_MAX_VERSION)
- return 0;
+ if (valid_tls)
+ *bound = version;
break;
case DTLS_ANY_VERSION:
- if (DTLS_VERSION_GT(version, DTLS_MAX_VERSION) ||
- DTLS_VERSION_LT(version, DTLS1_BAD_VER))
- return 0;
+ if (valid_dtls)
+ *bound = version;
break;
}
-
- *bound = version;
return 1;
}
--
1.8.3.1
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