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Diffstat (limited to 'src/openvpn/ssl_verify_mbedtls.c')
-rw-r--r--src/openvpn/ssl_verify_mbedtls.c511
1 files changed, 511 insertions, 0 deletions
diff --git a/src/openvpn/ssl_verify_mbedtls.c b/src/openvpn/ssl_verify_mbedtls.c
new file mode 100644
index 0000000..332f04b
--- /dev/null
+++ b/src/openvpn/ssl_verify_mbedtls.c
@@ -0,0 +1,511 @@
+/*
+ * OpenVPN -- An application to securely tunnel IP networks
+ * over a single TCP/UDP port, with support for SSL/TLS-based
+ * session authentication and key exchange,
+ * packet encryption, packet authentication, and
+ * packet compression.
+ *
+ * Copyright (C) 2002-2010 OpenVPN Technologies, Inc. <sales@openvpn.net>
+ * Copyright (C) 2010 Fox Crypto B.V. <openvpn@fox-it.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program (see the file COPYING included with this
+ * distribution); if not, write to the Free Software Foundation, Inc.,
+ * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ */
+
+/**
+ * @file Control Channel Verification Module mbed TLS backend
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#elif defined(_MSC_VER)
+#include "config-msvc.h"
+#endif
+
+#include "syshead.h"
+
+#if defined(ENABLE_CRYPTO) && defined(ENABLE_CRYPTO_MBEDTLS)
+
+#include "crypto_mbedtls.h"
+#include "ssl_verify.h"
+#include <mbedtls/asn1.h>
+#include <mbedtls/error.h>
+#include <mbedtls/bignum.h>
+#include <mbedtls/oid.h>
+#include <mbedtls/sha1.h>
+
+#define MAX_SUBJECT_LENGTH 256
+
+int
+verify_callback (void *session_obj, mbedtls_x509_crt *cert, int cert_depth,
+ uint32_t *flags)
+{
+ struct tls_session *session = (struct tls_session *) session_obj;
+ struct gc_arena gc = gc_new();
+
+ ASSERT (cert);
+ ASSERT (session);
+
+ session->verified = false;
+
+ /* Remember certificate hash */
+ struct buffer cert_fingerprint = x509_get_sha256_fingerprint (cert, &gc);
+ cert_hash_remember (session, cert_depth, &cert_fingerprint);
+
+ /* did peer present cert which was signed by our root cert? */
+ if (*flags != 0)
+ {
+ int ret = 0;
+ char errstr[512] = { 0 };
+ char *subject = x509_get_subject(cert, &gc);
+
+ ret = mbedtls_x509_crt_verify_info (errstr, sizeof(errstr)-1, "", *flags);
+ if (ret <= 0 && !openvpn_snprintf(errstr, sizeof(errstr),
+ "Could not retrieve error string, flags=%"PRIx32, *flags))
+ {
+ errstr[0] = '\0';
+ }
+ else
+ {
+ chomp(errstr);
+ }
+
+ if (subject)
+ {
+ msg (D_TLS_ERRORS, "VERIFY ERROR: depth=%d, subject=%s: %s",
+ cert_depth, subject, errstr);
+ }
+ else
+ {
+ msg (D_TLS_ERRORS, "VERIFY ERROR: depth=%d, (could not extract X509 "
+ "subject string from certificate): %s", cert_depth, errstr);
+ }
+
+ /* Leave flags set to non-zero to indicate that the cert is not ok */
+ }
+ else if (SUCCESS != verify_cert(session, cert, cert_depth))
+ {
+ *flags |= MBEDTLS_X509_BADCERT_OTHER;
+ }
+
+ gc_free(&gc);
+
+ /*
+ * PolarSSL/mbed TLS-1.2.0+ expects 0 on anything except fatal errors.
+ */
+ return 0;
+}
+
+#ifdef ENABLE_X509ALTUSERNAME
+# warning "X509 alt user name not yet supported for mbed TLS"
+#endif
+
+result_t
+backend_x509_get_username (char *cn, int cn_len,
+ char *x509_username_field, mbedtls_x509_crt *cert)
+{
+ mbedtls_x509_name *name;
+
+ ASSERT( cn != NULL );
+
+ name = &cert->subject;
+
+ /* Find common name */
+ while( name != NULL )
+ {
+ if (0 == memcmp (name->oid.p, MBEDTLS_OID_AT_CN,
+ MBEDTLS_OID_SIZE (MBEDTLS_OID_AT_CN)))
+ break;
+
+ name = name->next;
+ }
+
+ /* Not found, return an error if this is the peer's certificate */
+ if( name == NULL )
+ return FAILURE;
+
+ /* Found, extract CN */
+ if (cn_len > name->val.len)
+ {
+ memcpy( cn, name->val.p, name->val.len );
+ cn[name->val.len] = '\0';
+ }
+ else
+ {
+ memcpy( cn, name->val.p, cn_len);
+ cn[cn_len-1] = '\0';
+ }
+
+ return SUCCESS;
+}
+
+char *
+backend_x509_get_serial (mbedtls_x509_crt *cert, struct gc_arena *gc)
+{
+ char *buf = NULL;
+ size_t buflen = 0;
+ mbedtls_mpi serial_mpi = { 0 };
+
+ /* Transform asn1 integer serial into mbed TLS MPI */
+ mbedtls_mpi_init(&serial_mpi);
+ if (!mbed_ok(mbedtls_mpi_read_binary(&serial_mpi, cert->serial.p,
+ cert->serial.len)))
+ {
+ msg(M_WARN, "Failed to retrieve serial from certificate.");
+ goto end;
+ }
+
+ /* Determine decimal representation length, allocate buffer */
+ mbedtls_mpi_write_string(&serial_mpi, 10, NULL, 0, &buflen);
+ buf = gc_malloc(buflen, true, gc);
+
+ /* Write MPI serial as decimal string into buffer */
+ if (!mbed_ok(mbedtls_mpi_write_string(&serial_mpi, 10, buf, buflen, &buflen)))
+ {
+ msg(M_WARN, "Failed to write serial to string.");
+ buf = NULL;
+ goto end;
+ }
+
+end:
+ mbedtls_mpi_free(&serial_mpi);
+ return buf;
+}
+
+char *
+backend_x509_get_serial_hex (mbedtls_x509_crt *cert, struct gc_arena *gc)
+{
+ char *buf = NULL;
+ size_t len = cert->serial.len * 3 + 1;
+
+ buf = gc_malloc(len, true, gc);
+
+ if(mbedtls_x509_serial_gets(buf, len-1, &cert->serial) < 0)
+ buf = NULL;
+
+ return buf;
+}
+
+static struct buffer
+x509_get_fingerprint (const mbedtls_md_info_t *md_info, mbedtls_x509_crt *cert,
+ struct gc_arena *gc)
+{
+ const size_t md_size = mbedtls_md_get_size (md_info);
+ struct buffer fingerprint = alloc_buf_gc (md_size, gc);
+ mbedtls_md(md_info, cert->raw.p, cert->tbs.len, BPTR (&fingerprint));
+ ASSERT (buf_inc_len(&fingerprint, md_size));
+ return fingerprint;
+}
+
+struct buffer
+x509_get_sha1_fingerprint (mbedtls_x509_crt *cert, struct gc_arena *gc)
+{
+ return x509_get_fingerprint(mbedtls_md_info_from_type(MBEDTLS_MD_SHA1),
+ cert, gc);
+}
+
+struct buffer
+x509_get_sha256_fingerprint (mbedtls_x509_crt *cert, struct gc_arena *gc)
+{
+ return x509_get_fingerprint(mbedtls_md_info_from_type(MBEDTLS_MD_SHA256),
+ cert, gc);
+}
+
+char *
+x509_get_subject(mbedtls_x509_crt *cert, struct gc_arena *gc)
+{
+ char tmp_subject[MAX_SUBJECT_LENGTH] = {0};
+ char *subject = NULL;
+
+ int ret = 0;
+
+ ret = mbedtls_x509_dn_gets( tmp_subject, MAX_SUBJECT_LENGTH-1, &cert->subject );
+ if (ret > 0)
+ {
+ /* Allocate the required space for the subject */
+ subject = string_alloc(tmp_subject, gc);
+ }
+
+ return subject;
+}
+
+static void
+do_setenv_x509 (struct env_set *es, const char *name, char *value, int depth)
+{
+ char *name_expand;
+ size_t name_expand_size;
+
+ string_mod (value, CC_ANY, CC_CRLF, '?');
+ msg (D_X509_ATTR, "X509 ATTRIBUTE name='%s' value='%s' depth=%d", name, value, depth);
+ name_expand_size = 64 + strlen (name);
+ name_expand = (char *) malloc (name_expand_size);
+ check_malloc_return (name_expand);
+ openvpn_snprintf (name_expand, name_expand_size, "X509_%d_%s", depth, name);
+ setenv_str (es, name_expand, value);
+ free (name_expand);
+}
+
+static char *
+asn1_buf_to_c_string(const mbedtls_asn1_buf *orig, struct gc_arena *gc)
+{
+ size_t i;
+ char *val;
+
+ for (i = 0; i < orig->len; ++i)
+ if (orig->p[i] == '\0')
+ return "ERROR: embedded null value";
+ val = gc_malloc(orig->len+1, false, gc);
+ memcpy(val, orig->p, orig->len);
+ val[orig->len] = '\0';
+ return val;
+}
+
+static void
+do_setenv_name(struct env_set *es, const struct x509_track *xt,
+ const mbedtls_x509_crt *cert, int depth, struct gc_arena *gc)
+{
+ const mbedtls_x509_name *xn;
+ for (xn = &cert->subject; xn != NULL; xn = xn->next)
+ {
+ const char *xn_short_name = NULL;
+ if (0 == mbedtls_oid_get_attr_short_name (&xn->oid, &xn_short_name) &&
+ 0 == strcmp (xt->name, xn_short_name))
+ {
+ char *val_str = asn1_buf_to_c_string (&xn->val, gc);
+ do_setenv_x509 (es, xt->name, val_str, depth);
+ }
+ }
+}
+
+void
+x509_track_add (const struct x509_track **ll_head, const char *name, int msglevel, struct gc_arena *gc)
+{
+ struct x509_track *xt;
+ ALLOC_OBJ_CLEAR_GC (xt, struct x509_track, gc);
+ if (*name == '+')
+ {
+ xt->flags |= XT_FULL_CHAIN;
+ ++name;
+ }
+ xt->name = name;
+ xt->next = *ll_head;
+ *ll_head = xt;
+}
+
+void
+x509_setenv_track (const struct x509_track *xt, struct env_set *es,
+ const int depth, mbedtls_x509_crt *cert)
+{
+ struct gc_arena gc = gc_new();
+ while (xt)
+ {
+ if (depth == 0 || (xt->flags & XT_FULL_CHAIN))
+ {
+ if (0 == strcmp(xt->name, "SHA1") || 0 == strcmp(xt->name, "SHA256"))
+ {
+ /* Fingerprint is not part of X509 structure */
+ struct buffer cert_hash;
+ char *fingerprint;
+
+ if (0 == strcmp(xt->name, "SHA1"))
+ cert_hash = x509_get_sha1_fingerprint(cert, &gc);
+ else
+ cert_hash = x509_get_sha256_fingerprint(cert, &gc);
+
+ fingerprint = format_hex_ex(BPTR(&cert_hash),
+ BLEN(&cert_hash), 0, 1 | FHE_CAPS, ":", &gc);
+ do_setenv_x509(es, xt->name, fingerprint, depth);
+ }
+ else
+ {
+ do_setenv_name(es, xt, cert, depth, &gc);
+ }
+ }
+ xt = xt->next;
+ }
+ gc_free(&gc);
+}
+
+/*
+ * Save X509 fields to environment, using the naming convention:
+ *
+ * X509_{cert_depth}_{name}={value}
+ */
+void
+x509_setenv (struct env_set *es, int cert_depth, mbedtls_x509_crt *cert)
+{
+ int i;
+ unsigned char c;
+ const mbedtls_x509_name *name;
+ char s[128];
+
+ name = &cert->subject;
+
+ memset( s, 0, sizeof( s ) );
+
+ while( name != NULL )
+ {
+ char name_expand[64+8];
+ const char *shortname;
+
+ if( 0 == mbedtls_oid_get_attr_short_name(&name->oid, &shortname) )
+ {
+ openvpn_snprintf (name_expand, sizeof(name_expand), "X509_%d_%s",
+ cert_depth, shortname);
+ }
+ else
+ {
+ openvpn_snprintf (name_expand, sizeof(name_expand), "X509_%d_\?\?",
+ cert_depth);
+ }
+
+ for( i = 0; i < name->val.len; i++ )
+ {
+ if( i >= (int) sizeof( s ) - 1 )
+ break;
+
+ c = name->val.p[i];
+ if( c < 32 || c == 127 || ( c > 128 && c < 160 ) )
+ s[i] = '?';
+ else s[i] = c;
+ }
+ s[i] = '\0';
+
+ /* Check both strings, set environment variable */
+ string_mod (name_expand, CC_PRINT, CC_CRLF, '_');
+ string_mod ((char*)s, CC_PRINT, CC_CRLF, '_');
+ setenv_str_incr (es, name_expand, (char*)s);
+
+ name = name->next;
+ }
+}
+
+result_t
+x509_verify_ns_cert_type(const mbedtls_x509_crt *cert, const int usage)
+{
+ if (usage == NS_CERT_CHECK_NONE)
+ return SUCCESS;
+ if (usage == NS_CERT_CHECK_CLIENT)
+ return ((cert->ext_types & MBEDTLS_X509_EXT_NS_CERT_TYPE)
+ && (cert->ns_cert_type & MBEDTLS_X509_NS_CERT_TYPE_SSL_CLIENT)) ?
+ SUCCESS : FAILURE;
+ if (usage == NS_CERT_CHECK_SERVER)
+ return ((cert->ext_types & MBEDTLS_X509_EXT_NS_CERT_TYPE)
+ && (cert->ns_cert_type & MBEDTLS_X509_NS_CERT_TYPE_SSL_SERVER)) ?
+ SUCCESS : FAILURE;
+
+ return FAILURE;
+}
+
+result_t
+x509_verify_cert_ku (mbedtls_x509_crt *cert, const unsigned * const expected_ku,
+ int expected_len)
+{
+ result_t fFound = FAILURE;
+
+ if(!(cert->ext_types & MBEDTLS_X509_EXT_KEY_USAGE))
+ {
+ msg (D_HANDSHAKE, "Certificate does not have key usage extension");
+ }
+ else
+ {
+ int i;
+ unsigned nku = cert->key_usage;
+
+ msg (D_HANDSHAKE, "Validating certificate key usage");
+ for (i=0; SUCCESS != fFound && i<expected_len; i++)
+ {
+ if (expected_ku[i] != 0)
+ {
+ msg (D_HANDSHAKE, "++ Certificate has key usage %04x, expects "
+ "%04x", nku, expected_ku[i]);
+
+ if (nku == expected_ku[i])
+ {
+ fFound = SUCCESS;
+ }
+ }
+ }
+ }
+ return fFound;
+}
+
+result_t
+x509_verify_cert_eku (mbedtls_x509_crt *cert, const char * const expected_oid)
+{
+ result_t fFound = FAILURE;
+
+ if (!(cert->ext_types & MBEDTLS_X509_EXT_EXTENDED_KEY_USAGE))
+ {
+ msg (D_HANDSHAKE, "Certificate does not have extended key usage extension");
+ }
+ else
+ {
+ mbedtls_x509_sequence *oid_seq = &(cert->ext_key_usage);
+
+ msg (D_HANDSHAKE, "Validating certificate extended key usage");
+ while (oid_seq != NULL)
+ {
+ mbedtls_x509_buf *oid = &oid_seq->buf;
+ char oid_num_str[1024];
+ const char *oid_str;
+
+ if (0 == mbedtls_oid_get_extended_key_usage( oid, &oid_str ))
+ {
+ msg (D_HANDSHAKE, "++ Certificate has EKU (str) %s, expects %s",
+ oid_str, expected_oid);
+ if (!strcmp (expected_oid, oid_str))
+ {
+ fFound = SUCCESS;
+ break;
+ }
+ }
+
+ if (0 < mbedtls_oid_get_numeric_string( oid_num_str,
+ sizeof (oid_num_str), oid))
+ {
+ msg (D_HANDSHAKE, "++ Certificate has EKU (oid) %s, expects %s",
+ oid_num_str, expected_oid);
+ if (!strcmp (expected_oid, oid_num_str))
+ {
+ fFound = SUCCESS;
+ break;
+ }
+ }
+ oid_seq = oid_seq->next;
+ }
+ }
+
+ return fFound;
+}
+
+result_t
+x509_write_pem(FILE *peercert_file, mbedtls_x509_crt *peercert)
+{
+ msg (M_WARN, "mbed TLS does not support writing peer certificate in PEM format");
+ return FAILURE;
+}
+
+bool
+tls_verify_crl_missing(const struct tls_options *opt)
+{
+ if (opt->crl_file && !(opt->ssl_flags & SSLF_CRL_VERIFY_DIR)
+ && (opt->ssl_ctx.crl == NULL || opt->ssl_ctx.crl->version == 0))
+ {
+ return true;
+ }
+ return false;
+}
+
+#endif /* #if defined(ENABLE_CRYPTO) && defined(ENABLE_CRYPTO_MBEDTLS) */
generated by cgit v1.2.3 (git 2.25.1) at 2024-05-15 19:02:50 +0000