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|
/*
* SPDX-License-Identifier: ISC
*
* Copyright (c) 2019-2022 Todd C. Miller <Todd.Miller@sudo.ws>
*
* 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.
*/
/*
* This is an open source non-commercial project. Dear PVS-Studio, please check it.
* PVS-Studio Static Code Analyzer for C, C++ and C#: http://www.viva64.com
*/
#include <config.h>
#ifdef HAVE_STDBOOL_H
# include <stdbool.h>
#else
# include "compat/stdbool.h"
#endif /* HAVE_STDBOOL_H */
#if defined(HAVE_STDINT_H)
# include <stdint.h>
#elif defined(HAVE_INTTYPES_H)
# include <inttypes.h>
#endif
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#include <unistd.h>
#include "sudo_compat.h"
#include "sudo_debug.h"
#include "sudo_event.h"
#include "sudo_fatal.h"
#include "sudo_gettext.h"
#include "tls_common.h"
#include "hostcheck.h"
#define DEFAULT_CIPHER_LST12 "HIGH:!aNULL"
#define DEFAULT_CIPHER_LST13 "TLS_AES_256_GCM_SHA384"
#if defined(HAVE_OPENSSL)
# include <openssl/bio.h>
# include <openssl/dh.h>
static bool
verify_cert_chain(SSL_CTX *ctx, const char *cert_file)
{
#ifdef HAVE_SSL_CTX_GET0_CERTIFICATE
const char *errstr;
bool ret = false;
X509_STORE_CTX *store_ctx = NULL;
X509_STORE *ca_store;
STACK_OF(X509) *chain_certs;
X509 *x509;
debug_decl(verify_cert_chain, SUDO_DEBUG_UTIL);
if ((x509 = SSL_CTX_get0_certificate(ctx)) == NULL) {
errstr = ERR_reason_error_string(ERR_get_error());
sudo_warnx("SSL_CTX_get0_certificate: %s",
errstr ? errstr : strerror(errno));
goto done;
}
if ((store_ctx = X509_STORE_CTX_new()) == NULL) {
errstr = ERR_reason_error_string(ERR_get_error());
sudo_warnx("X509_STORE_CTX_new: %s",
errstr ? errstr : strerror(errno));
goto done;
}
if (!SSL_CTX_get0_chain_certs(ctx, &chain_certs)) {
errstr = ERR_reason_error_string(ERR_get_error());
sudo_warnx("SSL_CTX_get0_chain_certs: %s: %s", cert_file,
errstr ? errstr : strerror(errno));
goto done;
}
ca_store = SSL_CTX_get_cert_store(ctx);
#ifdef X509_V_FLAG_X509_STRICT
if (ca_store != NULL)
X509_STORE_set_flags(ca_store, X509_V_FLAG_X509_STRICT);
#endif
if (!X509_STORE_CTX_init(store_ctx, ca_store, x509, chain_certs)) {
errstr = ERR_reason_error_string(ERR_get_error());
sudo_warnx("X509_STORE_CTX_init: %s",
errstr ? errstr : strerror(errno));
goto done;
}
if (X509_verify_cert(store_ctx) <= 0) {
errstr =
X509_verify_cert_error_string(X509_STORE_CTX_get_error(store_ctx));
sudo_warnx("X509_verify_cert: %s: %s", cert_file, errstr);
goto done;
}
ret = true;
done:
X509_STORE_CTX_free(store_ctx);
debug_return_bool(ret);
#else
/* TODO: verify server cert with old OpenSSL */
return true;
#endif /* HAVE_SSL_CTX_GET0_CERTIFICATE */
}
static bool
init_tls_ciphersuites(SSL_CTX *ctx, const char *ciphers_v12,
const char *ciphers_v13)
{
const char *errstr;
int success = 0;
debug_decl(init_tls_ciphersuites, SUDO_DEBUG_UTIL);
if (ciphers_v12 != NULL) {
/* try to set TLS v1.2 ciphersuite list from config if given */
success = SSL_CTX_set_cipher_list(ctx, ciphers_v12);
if (success) {
sudo_debug_printf(SUDO_DEBUG_INFO|SUDO_DEBUG_LINENO,
"TLS 1.2 ciphersuite list set to %s", ciphers_v12);
} else {
errstr = ERR_reason_error_string(ERR_get_error());
sudo_warnx(U_("unable to set TLS 1.2 ciphersuite to %s: %s"),
ciphers_v12, errstr ? errstr : strerror(errno));
}
}
if (!success) {
/* fallback to default ciphersuites for TLS v1.2 */
if (SSL_CTX_set_cipher_list(ctx, DEFAULT_CIPHER_LST12) <= 0) {
errstr = ERR_reason_error_string(ERR_get_error());
sudo_warnx(U_("unable to set TLS 1.2 ciphersuite to %s: %s"),
DEFAULT_CIPHER_LST12, errstr ? errstr : strerror(errno));
debug_return_bool(false);
} else {
sudo_debug_printf(SUDO_DEBUG_INFO|SUDO_DEBUG_LINENO,
"TLS v1.2 ciphersuite list set to %s (default)",
DEFAULT_CIPHER_LST12);
}
}
# if defined(HAVE_SSL_CTX_SET_CIPHERSUITES)
success = 0;
if (ciphers_v13 != NULL) {
/* try to set TLSv1.3 ciphersuite list from config */
success = SSL_CTX_set_ciphersuites(ctx, ciphers_v13);
if (success) {
sudo_debug_printf(SUDO_DEBUG_INFO|SUDO_DEBUG_LINENO,
"TLS v1.3 ciphersuite list set to %s", ciphers_v13);
} else {
errstr = ERR_reason_error_string(ERR_get_error());
sudo_warnx(U_("unable to set TLS 1.3 ciphersuite to %s: %s"),
ciphers_v13, errstr ? errstr : strerror(errno));
}
}
if (!success) {
/* fallback to default ciphersuites for TLS v1.3 */
if (SSL_CTX_set_ciphersuites(ctx, DEFAULT_CIPHER_LST13) <= 0) {
errstr = ERR_reason_error_string(ERR_get_error());
sudo_warnx(U_("unable to set TLS 1.3 ciphersuite to %s: %s"),
DEFAULT_CIPHER_LST13, errstr ? errstr : strerror(errno));
debug_return_bool(false);
} else {
sudo_debug_printf(SUDO_DEBUG_INFO|SUDO_DEBUG_LINENO,
"TLS v1.3 ciphersuite list set to %s (default)",
DEFAULT_CIPHER_LST13);
}
}
# endif
debug_return_bool(true);
}
/*
* Load diffie-hellman parameters from bio and store in ctx.
* Returns true on success, else false.
*/
#ifdef HAVE_SSL_CTX_SET0_TMP_DH_PKEY
static bool
set_dhparams_bio(SSL_CTX *ctx, BIO *bio)
{
EVP_PKEY *dhparams;
bool ret = false;
debug_decl(set_dhparams_bio, SUDO_DEBUG_UTIL);
dhparams = PEM_read_bio_Parameters(bio, NULL);
if (dhparams != NULL) {
/* dhparams is owned by ctx on success. */
ret = SSL_CTX_set0_tmp_dh_pkey(ctx, dhparams);
if (!ret) {
const char *errstr = ERR_reason_error_string(ERR_get_error());
sudo_warnx(U_("unable to set diffie-hellman parameters: %s"),
errstr ? errstr : strerror(errno));
EVP_PKEY_free(dhparams);
}
}
debug_return_bool(ret);
}
#else
static bool
set_dhparams_bio(SSL_CTX *ctx, BIO *bio)
{
DH *dhparams;
bool ret = false;
debug_decl(set_dhparams_bio, SUDO_DEBUG_UTIL);
dhparams = PEM_read_bio_DHparams(bio, NULL, NULL, NULL);
if (dhparams != NULL) {
/* LEAK: dhparams leaked on config reload */
ret = SSL_CTX_set_tmp_dh(ctx, dhparams);
if (!ret) {
const char *errstr = ERR_reason_error_string(ERR_get_error());
sudo_warnx(U_("unable to set diffie-hellman parameters: %s"),
errstr ? errstr : strerror(errno));
DH_free(dhparams);
}
}
debug_return_bool(ret);
}
#endif /* HAVE_SSL_CTX_SET0_TMP_DH_PKEY */
/*
* Load diffie-hellman parameters from the specified file and store in ctx.
* Returns true on success, else false.
*/
static bool
set_dhparams(SSL_CTX *ctx, const char *dhparam_file)
{
BIO *bio;
bool ret = false;
debug_decl(set_dhparams, SUDO_DEBUG_UTIL);
bio = BIO_new_file(dhparam_file, "r");
if (bio != NULL) {
if (set_dhparams_bio(ctx, bio)) {
sudo_debug_printf(SUDO_DEBUG_INFO|SUDO_DEBUG_LINENO,
"loaded diffie-hellman parameters from %s", dhparam_file);
ret = true;
}
BIO_free(bio);
} else {
sudo_warn(U_("unable to open %s"), dhparam_file);
}
debug_return_bool(ret);
}
SSL_CTX *
init_tls_context(const char *ca_bundle_file, const char *cert_file,
const char *key_file, const char *dhparam_file, const char *ciphers_v12,
const char *ciphers_v13, bool verify_cert)
{
SSL_CTX *ctx = NULL;
const char *errstr;
static bool initialized;
debug_decl(init_tls_context, SUDO_DEBUG_UTIL);
/* Only initialize the SSL library once. */
if (!initialized) {
SSL_library_init();
OpenSSL_add_all_algorithms();
SSL_load_error_strings();
initialized = true;
}
/* Create the ssl context and enforce TLS 1.2 or higher. */
if ((ctx = SSL_CTX_new(TLS_method())) == NULL) {
errstr = ERR_reason_error_string(ERR_get_error());
sudo_warnx(U_("unable to create TLS context: %s"),
errstr ? errstr : strerror(errno));
goto bad;
}
#ifdef HAVE_SSL_CTX_SET_MIN_PROTO_VERSION
if (!SSL_CTX_set_min_proto_version(ctx, TLS1_2_VERSION)) {
errstr = ERR_reason_error_string(ERR_get_error());
sudo_warnx(U_("unable to set minimum protocol version to TLS 1.2: %s"),
errstr ? errstr : strerror(errno));
goto bad;
}
#else
SSL_CTX_set_options(ctx,
SSL_OP_NO_SSLv2|SSL_OP_NO_SSLv3|SSL_OP_NO_TLSv1|SSL_OP_NO_TLSv1_1);
#endif
if (ca_bundle_file != NULL) {
STACK_OF(X509_NAME) *cacerts =
SSL_load_client_CA_file(ca_bundle_file);
if (cacerts == NULL) {
errstr = ERR_reason_error_string(ERR_get_error());
sudo_warnx(U_("%s: %s"), ca_bundle_file,
errstr ? errstr : strerror(errno));
goto bad;
}
SSL_CTX_set_client_CA_list(ctx, cacerts);
if (SSL_CTX_load_verify_locations(ctx, ca_bundle_file, NULL) <= 0) {
errstr = ERR_reason_error_string(ERR_get_error());
sudo_warnx("SSL_CTX_load_verify_locations: %s: %s", ca_bundle_file,
errstr ? errstr : strerror(errno));
goto bad;
}
} else {
if (!SSL_CTX_set_default_verify_paths(ctx)) {
errstr = ERR_reason_error_string(ERR_get_error());
sudo_warnx("SSL_CTX_set_default_verify_paths: %s",
errstr ? errstr : strerror(errno));
goto bad;
}
}
if (cert_file != NULL) {
if (!SSL_CTX_use_certificate_chain_file(ctx, cert_file)) {
errstr = ERR_reason_error_string(ERR_get_error());
sudo_warnx(U_("%s: %s"), cert_file,
errstr ? errstr : strerror(errno));
goto bad;
}
if (key_file == NULL) {
/* No explicit key file set, try to use the cert file. */
key_file = cert_file;
}
if (!SSL_CTX_use_PrivateKey_file(ctx, key_file, SSL_FILETYPE_PEM) ||
!SSL_CTX_check_private_key(ctx)) {
errstr = ERR_reason_error_string(ERR_get_error());
sudo_warnx(U_("%s: %s"), key_file,
errstr ? errstr : strerror(errno));
goto bad;
}
/* Optionally verify the certificate we are using. */
if (verify_cert) {
if (!verify_cert_chain(ctx, cert_file))
goto bad;
} else {
sudo_debug_printf(SUDO_DEBUG_INFO|SUDO_DEBUG_LINENO,
"skipping local cert check");
}
}
/* Initialize TLS 1.2 1.3 ciphersuites. */
if (!init_tls_ciphersuites(ctx, ciphers_v12, ciphers_v13)) {
goto bad;
}
/*
* Load diffie-hellman parameters from a file if specified.
* Failure to open the file is not a fatal error.
*/
if (dhparam_file != NULL) {
if (!set_dhparams(ctx, dhparam_file)) {
sudo_debug_printf(SUDO_DEBUG_INFO|SUDO_DEBUG_LINENO,
"unable to load dhparam file, using default parameters");
}
} else {
sudo_debug_printf(SUDO_DEBUG_INFO|SUDO_DEBUG_LINENO,
"dhparam file not specified, using default parameters");
}
goto done;
bad:
SSL_CTX_free(ctx);
ctx = NULL;
done:
debug_return_ptr(ctx);
}
#endif /* HAVE_OPENSSL */
|
