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/* $OpenBSD: ssl_versions.c,v 1.6 2020/05/31 18:03:32 jsing Exp $ */
/*
* Copyright (c) 2016, 2017 Joel Sing <jsing@openbsd.org>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#include "ssl_locl.h"
static int
ssl_clamp_version_range(uint16_t *min_ver, uint16_t *max_ver,
uint16_t clamp_min, uint16_t clamp_max)
{
if (clamp_min > clamp_max || *min_ver > *max_ver)
return 0;
if (clamp_max < *min_ver || clamp_min > *max_ver)
return 0;
if (*min_ver < clamp_min)
*min_ver = clamp_min;
if (*max_ver > clamp_max)
*max_ver = clamp_max;
return 1;
}
int
ssl_version_set_min(const SSL_METHOD *meth, uint16_t ver, uint16_t max_ver,
uint16_t *out_ver)
{
uint16_t min_version, max_version;
if (ver == 0) {
*out_ver = meth->internal->min_version;
return 1;
}
min_version = ver;
max_version = max_ver;
if (!ssl_clamp_version_range(&min_version, &max_version,
meth->internal->min_version, meth->internal->max_version))
return 0;
*out_ver = min_version;
return 1;
}
int
ssl_version_set_max(const SSL_METHOD *meth, uint16_t ver, uint16_t min_ver,
uint16_t *out_ver)
{
uint16_t min_version, max_version;
if (ver == 0) {
*out_ver = meth->internal->max_version;
return 1;
}
min_version = min_ver;
max_version = ver;
if (!ssl_clamp_version_range(&min_version, &max_version,
meth->internal->min_version, meth->internal->max_version))
return 0;
*out_ver = max_version;
return 1;
}
int
ssl_enabled_version_range(SSL *s, uint16_t *min_ver, uint16_t *max_ver)
{
uint16_t min_version, max_version;
/*
* The enabled versions have to be a contiguous range, which means we
* cannot enable and disable single versions at our whim, even though
* this is what the OpenSSL flags allow. The historical way this has
* been handled is by making a flag mean that all higher versions
* are disabled, if any version lower than the flag is enabled.
*/
min_version = 0;
max_version = TLS1_3_VERSION;
if ((s->internal->options & SSL_OP_NO_TLSv1) == 0)
min_version = TLS1_VERSION;
else if ((s->internal->options & SSL_OP_NO_TLSv1_1) == 0)
min_version = TLS1_1_VERSION;
else if ((s->internal->options & SSL_OP_NO_TLSv1_2) == 0)
min_version = TLS1_2_VERSION;
else if ((s->internal->options & SSL_OP_NO_TLSv1_3) == 0)
min_version = TLS1_3_VERSION;
if ((s->internal->options & SSL_OP_NO_TLSv1_3) && min_version < TLS1_3_VERSION)
max_version = TLS1_2_VERSION;
if ((s->internal->options & SSL_OP_NO_TLSv1_2) && min_version < TLS1_2_VERSION)
max_version = TLS1_1_VERSION;
if ((s->internal->options & SSL_OP_NO_TLSv1_1) && min_version < TLS1_1_VERSION)
max_version = TLS1_VERSION;
if ((s->internal->options & SSL_OP_NO_TLSv1) && min_version < TLS1_VERSION)
max_version = 0;
/* Everything has been disabled... */
if (min_version == 0 || max_version == 0)
return 0;
/* Limit to configured version range. */
if (!ssl_clamp_version_range(&min_version, &max_version,
s->internal->min_version, s->internal->max_version))
return 0;
if (min_ver != NULL)
*min_ver = min_version;
if (max_ver != NULL)
*max_ver = max_version;
return 1;
}
int
ssl_supported_version_range(SSL *s, uint16_t *min_ver, uint16_t *max_ver)
{
uint16_t min_version, max_version;
/* DTLS cannot currently be disabled... */
if (SSL_IS_DTLS(s)) {
min_version = max_version = DTLS1_VERSION;
goto done;
}
if (!ssl_enabled_version_range(s, &min_version, &max_version))
return 0;
/* Limit to the versions supported by this method. */
if (!ssl_clamp_version_range(&min_version, &max_version,
s->method->internal->min_version,
s->method->internal->max_version))
return 0;
done:
if (min_ver != NULL)
*min_ver = min_version;
if (max_ver != NULL)
*max_ver = max_version;
return 1;
}
int
ssl_max_shared_version(SSL *s, uint16_t peer_ver, uint16_t *max_ver)
{
uint16_t min_version, max_version, shared_version;
*max_ver = 0;
if (SSL_IS_DTLS(s)) {
if (peer_ver >= DTLS1_VERSION) {
*max_ver = DTLS1_VERSION;
return 1;
}
return 0;
}
if (peer_ver >= TLS1_3_VERSION)
shared_version = TLS1_3_VERSION;
else if (peer_ver >= TLS1_2_VERSION)
shared_version = TLS1_2_VERSION;
else if (peer_ver >= TLS1_1_VERSION)
shared_version = TLS1_1_VERSION;
else if (peer_ver >= TLS1_VERSION)
shared_version = TLS1_VERSION;
else
return 0;
if (!ssl_supported_version_range(s, &min_version, &max_version))
return 0;
if (shared_version < min_version)
return 0;
if (shared_version > max_version)
shared_version = max_version;
*max_ver = shared_version;
return 1;
}
int
ssl_downgrade_max_version(SSL *s, uint16_t *max_ver)
{
uint16_t min_version, max_version;
/*
* The downgrade maximum version is based on the versions that are
* enabled, however we also have to then limit to the versions
* supported by the method. The SSL method will be changed during
* version negotiation and when switching from the new stack to
* the legacy context, as such we want to use the method from the
* context.
*/
if (SSL_IS_DTLS(s)) {
*max_ver = DTLS1_VERSION;
return 1;
}
if (!ssl_enabled_version_range(s, &min_version, &max_version))
return 0;
if (!ssl_clamp_version_range(&min_version, &max_version,
s->ctx->method->internal->min_version,
s->ctx->method->internal->max_version))
return 0;
*max_ver = max_version;
return 1;
}
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