From 8dd0350e1607aa30f7a043c8d5ec7a7eeb874115 Mon Sep 17 00:00:00 2001 From: Alberto Gonzalez Iniesta Date: Mon, 5 Nov 2012 16:28:09 +0100 Subject: Imported Upstream version 2.3_rc1 --- src/openvpn/ssl_verify_openssl.c | 622 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 622 insertions(+) create mode 100644 src/openvpn/ssl_verify_openssl.c (limited to 'src/openvpn/ssl_verify_openssl.c') diff --git a/src/openvpn/ssl_verify_openssl.c b/src/openvpn/ssl_verify_openssl.c new file mode 100644 index 0000000..658f5f3 --- /dev/null +++ b/src/openvpn/ssl_verify_openssl.c @@ -0,0 +1,622 @@ +/* + * 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. + * Copyright (C) 2010 Fox Crypto B.V. + * + * 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 OpenSSL implementation + */ + +#ifdef HAVE_CONFIG_H +#include "config.h" +#elif defined(_MSC_VER) +#include "config-msvc.h" +#endif + +#include "syshead.h" + +#if defined(ENABLE_SSL) && defined(ENABLE_CRYPTO_OPENSSL) + +#include "ssl_verify.h" +#include "ssl_verify_backend.h" +#include "ssl_openssl.h" +#include +#include + +int +verify_callback (int preverify_ok, X509_STORE_CTX * ctx) +{ + int ret = 0; + struct tls_session *session; + SSL *ssl; + struct gc_arena gc = gc_new(); + + /* get the tls_session pointer */ + ssl = X509_STORE_CTX_get_ex_data (ctx, SSL_get_ex_data_X509_STORE_CTX_idx()); + ASSERT (ssl); + session = (struct tls_session *) SSL_get_ex_data (ssl, mydata_index); + ASSERT (session); + + cert_hash_remember (session, ctx->error_depth, + x509_get_sha1_hash(ctx->current_cert, &gc)); + + /* did peer present cert which was signed by our root cert? */ + if (!preverify_ok) + { + /* get the X509 name */ + char *subject = x509_get_subject(ctx->current_cert, &gc); + + if (subject) + { + /* Remote site specified a certificate, but it's not correct */ + msg (D_TLS_ERRORS, "VERIFY ERROR: depth=%d, error=%s: %s", + ctx->error_depth, + X509_verify_cert_error_string (ctx->error), + subject); + } + + ERR_clear_error(); + + session->verified = false; + goto cleanup; + } + + if (SUCCESS != verify_cert(session, ctx->current_cert, ctx->error_depth)) + goto cleanup; + + ret = 1; + +cleanup: + gc_free(&gc); + + return ret; +} + +#ifdef ENABLE_X509ALTUSERNAME +static +bool extract_x509_extension(X509 *cert, char *fieldname, char *out, int size) +{ + bool retval = false; + X509_EXTENSION *pExt; + char *buf = 0; + int length = 0; + GENERAL_NAMES *extensions; + int nid = OBJ_txt2nid(fieldname); + + extensions = (GENERAL_NAMES *)X509_get_ext_d2i(cert, nid, NULL, NULL); + if ( extensions ) + { + int numalts; + int i; + /* get amount of alternatives, + * RFC2459 claims there MUST be at least + * one, but we don't depend on it... + */ + + numalts = sk_GENERAL_NAME_num(extensions); + + /* loop through all alternatives */ + for (i=0; itype) + { + case GEN_EMAIL: + ASN1_STRING_to_UTF8((unsigned char**)&buf, name->d.ia5); + if ( strlen (buf) != name->d.ia5->length ) + { + msg (D_TLS_ERRORS, "ASN1 ERROR: string contained terminating zero"); + OPENSSL_free (buf); + } else { + strncpynt(out, buf, size); + OPENSSL_free(buf); + retval = true; + } + break; + default: + msg (D_TLS_ERRORS, "ASN1 ERROR: can not handle field type %i", + name->type); + break; + } + } + sk_GENERAL_NAME_free (extensions); + } + return retval; +} +#endif /* ENABLE_X509ALTUSERNAME */ + +/* + * Extract a field from an X509 subject name. + * + * Example: + * + * /C=US/ST=CO/L=Denver/O=ORG/CN=First-CN/CN=Test-CA/Email=jim@yonan.net + * + * The common name is 'Test-CA' + * + * Return true on success, false on error (insufficient buffer size in 'out' + * to contain result is grounds for error). + */ +static result_t +extract_x509_field_ssl (X509_NAME *x509, const char *field_name, char *out, + int size) +{ + int lastpos = -1; + int tmp = -1; + X509_NAME_ENTRY *x509ne = 0; + ASN1_STRING *asn1 = 0; + unsigned char *buf = (unsigned char *)1; /* bug in OpenSSL 0.9.6b ASN1_STRING_to_UTF8 requires this workaround */ + int nid = OBJ_txt2nid((char *)field_name); + + ASSERT (size > 0); + *out = '\0'; + do { + lastpos = tmp; + tmp = X509_NAME_get_index_by_NID(x509, nid, lastpos); + } while (tmp > -1); + + /* Nothing found */ + if (lastpos == -1) + return FAILURE; + + x509ne = X509_NAME_get_entry(x509, lastpos); + if (!x509ne) + return FAILURE; + + asn1 = X509_NAME_ENTRY_get_data(x509ne); + if (!asn1) + return FAILURE; + tmp = ASN1_STRING_to_UTF8(&buf, asn1); + if (tmp <= 0) + return FAILURE; + + strncpynt(out, (char *)buf, size); + + { + const result_t ret = (strlen ((char *)buf) < size) ? SUCCESS: FAILURE; + OPENSSL_free (buf); + return ret; + } +} + +result_t +x509_get_username (char *common_name, int cn_len, + char * x509_username_field, X509 *peer_cert) +{ +#ifdef ENABLE_X509ALTUSERNAME + if (strncmp("ext:",x509_username_field,4) == 0) + { + if (!extract_x509_extension (peer_cert, x509_username_field+4, common_name, cn_len)) + return FAILURE; + } else +#endif + if (FAILURE == extract_x509_field_ssl (X509_get_subject_name (peer_cert), + x509_username_field, common_name, cn_len)) + return FAILURE; + + return SUCCESS; +} + +char * +x509_get_serial (openvpn_x509_cert_t *cert, struct gc_arena *gc) +{ + ASN1_INTEGER *asn1_i; + BIGNUM *bignum; + char *openssl_serial, *serial; + + asn1_i = X509_get_serialNumber(cert); + bignum = ASN1_INTEGER_to_BN(asn1_i, NULL); + openssl_serial = BN_bn2dec(bignum); + + serial = string_alloc(openssl_serial, gc); + + BN_free(bignum); + OPENSSL_free(openssl_serial); + + return serial; +} + +unsigned char * +x509_get_sha1_hash (X509 *cert, struct gc_arena *gc) +{ + char *hash = gc_malloc(SHA_DIGEST_LENGTH, false, gc); + memcpy(hash, cert->sha1_hash, SHA_DIGEST_LENGTH); + return hash; +} + +char * +x509_get_subject (X509 *cert, struct gc_arena *gc) +{ + BIO *subject_bio = NULL; + BUF_MEM *subject_mem; + char *subject = NULL; + int maxlen = 0; + + /* + * Generate the subject string in OpenSSL proprietary format, + * when in --compat-names mode + */ + if (compat_flag (COMPAT_FLAG_QUERY | COMPAT_NAMES)) + { + subject = gc_malloc (256, false, gc); + X509_NAME_oneline (X509_get_subject_name (cert), subject, 256); + subject[255] = '\0'; + return subject; + } + + subject_bio = BIO_new (BIO_s_mem ()); + if (subject_bio == NULL) + goto err; + + X509_NAME_print_ex (subject_bio, X509_get_subject_name (cert), + 0, XN_FLAG_SEP_CPLUS_SPC | XN_FLAG_FN_SN | + ASN1_STRFLGS_UTF8_CONVERT | ASN1_STRFLGS_ESC_CTRL); + + if (BIO_eof (subject_bio)) + goto err; + + BIO_get_mem_ptr (subject_bio, &subject_mem); + + maxlen = subject_mem->length + 1; + subject = gc_malloc (maxlen, false, gc); + + memcpy (subject, subject_mem->data, maxlen); + subject[maxlen - 1] = '\0'; + +err: + if (subject_bio) + BIO_free (subject_bio); + + return subject; +} + + +#ifdef ENABLE_X509_TRACK + +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->nid = OBJ_txt2nid(name); + if (xt->nid != NID_undef) + { + xt->next = *ll_head; + *ll_head = xt; + } + else + msg(msglevel, "x509_track: no such attribute '%s'", name); +} + +/* worker method for setenv_x509_track */ +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); +} + +void +x509_setenv_track (const struct x509_track *xt, struct env_set *es, const int depth, X509 *x509) +{ + X509_NAME *x509_name = X509_get_subject_name (x509); + const char nullc = '\0'; + int i; + + while (xt) + { + if (depth == 0 || (xt->flags & XT_FULL_CHAIN)) + { + i = X509_NAME_get_index_by_NID(x509_name, xt->nid, -1); + if (i >= 0) + { + X509_NAME_ENTRY *ent = X509_NAME_get_entry(x509_name, i); + if (ent) + { + ASN1_STRING *val = X509_NAME_ENTRY_get_data (ent); + unsigned char *buf; + buf = (unsigned char *)1; /* bug in OpenSSL 0.9.6b ASN1_STRING_to_UTF8 requires this workaround */ + if (ASN1_STRING_to_UTF8 (&buf, val) > 0) + { + do_setenv_x509(es, xt->name, (char *)buf, depth); + OPENSSL_free (buf); + } + } + } + else + { + i = X509_get_ext_by_NID(x509, xt->nid, -1); + if (i >= 0) + { + X509_EXTENSION *ext = X509_get_ext(x509, i); + if (ext) + { + BIO *bio = BIO_new(BIO_s_mem()); + if (bio) + { + if (X509V3_EXT_print(bio, ext, 0, 0)) + { + if (BIO_write(bio, &nullc, 1) == 1) + { + char *str; + BIO_get_mem_data(bio, &str); + do_setenv_x509(es, xt->name, str, depth); + } + } + BIO_free(bio); + } + } + } + } + } + xt = xt->next; + } +} +#endif + +/* + * Save X509 fields to environment, using the naming convention: + * + * X509_{cert_depth}_{name}={value} + */ +void +x509_setenv (struct env_set *es, int cert_depth, openvpn_x509_cert_t *peer_cert) +{ + int i, n; + int fn_nid; + ASN1_OBJECT *fn; + ASN1_STRING *val; + X509_NAME_ENTRY *ent; + const char *objbuf; + unsigned char *buf; + char *name_expand; + size_t name_expand_size; + X509_NAME *x509 = X509_get_subject_name (peer_cert); + + n = X509_NAME_entry_count (x509); + for (i = 0; i < n; ++i) + { + ent = X509_NAME_get_entry (x509, i); + if (!ent) + continue; + fn = X509_NAME_ENTRY_get_object (ent); + if (!fn) + continue; + val = X509_NAME_ENTRY_get_data (ent); + if (!val) + continue; + fn_nid = OBJ_obj2nid (fn); + if (fn_nid == NID_undef) + continue; + objbuf = OBJ_nid2sn (fn_nid); + if (!objbuf) + continue; + buf = (unsigned char *)1; /* bug in OpenSSL 0.9.6b ASN1_STRING_to_UTF8 requires this workaround */ + if (ASN1_STRING_to_UTF8 (&buf, val) <= 0) + continue; + name_expand_size = 64 + strlen (objbuf); + name_expand = (char *) malloc (name_expand_size); + check_malloc_return (name_expand); + openvpn_snprintf (name_expand, name_expand_size, "X509_%d_%s", cert_depth, + objbuf); + string_mod (name_expand, CC_PRINT, CC_CRLF, '_'); + string_mod ((char*)buf, CC_PRINT, CC_CRLF, '_'); + setenv_str (es, name_expand, (char*)buf); + free (name_expand); + OPENSSL_free (buf); + } +} + +result_t +x509_verify_ns_cert_type(const openvpn_x509_cert_t *peer_cert, const int usage) +{ + if (usage == NS_CERT_CHECK_NONE) + return SUCCESS; + if (usage == NS_CERT_CHECK_CLIENT) + return ((peer_cert->ex_flags & EXFLAG_NSCERT) + && (peer_cert->ex_nscert & NS_SSL_CLIENT)) ? SUCCESS: FAILURE; + if (usage == NS_CERT_CHECK_SERVER) + return ((peer_cert->ex_flags & EXFLAG_NSCERT) + && (peer_cert->ex_nscert & NS_SSL_SERVER)) ? SUCCESS: FAILURE; + + return FAILURE; +} + +#if OPENSSL_VERSION_NUMBER >= 0x00907000L + +result_t +x509_verify_cert_ku (X509 *x509, const unsigned * const expected_ku, + int expected_len) +{ + ASN1_BIT_STRING *ku = NULL; + result_t fFound = FAILURE; + + if ((ku = (ASN1_BIT_STRING *) X509_get_ext_d2i (x509, NID_key_usage, NULL, + NULL)) == NULL) + { + msg (D_HANDSHAKE, "Certificate does not have key usage extension"); + } + else + { + unsigned nku = 0; + int i; + for (i = 0; i < 8; i++) + { + if (ASN1_BIT_STRING_get_bit (ku, i)) + nku |= 1 << (7 - i); + } + + /* + * Fixup if no LSB bits + */ + if ((nku & 0xff) == 0) + { + nku >>= 8; + } + + msg (D_HANDSHAKE, "Validating certificate key usage"); + for (i = 0; fFound != SUCCESS && 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; + } + } + } + + if (ku != NULL) + ASN1_BIT_STRING_free (ku); + + return fFound; +} + +result_t +x509_verify_cert_eku (X509 *x509, const char * const expected_oid) +{ + EXTENDED_KEY_USAGE *eku = NULL; + result_t fFound = FAILURE; + + if ((eku = (EXTENDED_KEY_USAGE *) X509_get_ext_d2i (x509, NID_ext_key_usage, + NULL, NULL)) == NULL) + { + msg (D_HANDSHAKE, "Certificate does not have extended key usage extension"); + } + else + { + int i; + + msg (D_HANDSHAKE, "Validating certificate extended key usage"); + for (i = 0; SUCCESS != fFound && i < sk_ASN1_OBJECT_num (eku); i++) + { + ASN1_OBJECT *oid = sk_ASN1_OBJECT_value (eku, i); + char szOid[1024]; + + if (SUCCESS != fFound && OBJ_obj2txt (szOid, sizeof(szOid), oid, 0) != -1) + { + msg (D_HANDSHAKE, "++ Certificate has EKU (str) %s, expects %s", + szOid, expected_oid); + if (!strcmp (expected_oid, szOid)) + fFound = SUCCESS; + } + if (SUCCESS != fFound && OBJ_obj2txt (szOid, sizeof(szOid), oid, 1) != -1) + { + msg (D_HANDSHAKE, "++ Certificate has EKU (oid) %s, expects %s", + szOid, expected_oid); + if (!strcmp (expected_oid, szOid)) + fFound = SUCCESS; + } + } + } + + if (eku != NULL) + sk_ASN1_OBJECT_pop_free (eku, ASN1_OBJECT_free); + + return fFound; +} + +result_t +x509_write_pem(FILE *peercert_file, X509 *peercert) +{ + if (PEM_write_X509(peercert_file, peercert) < 0) + { + msg (M_ERR, "Failed to write peer certificate in PEM format"); + return FAILURE; + } + return SUCCESS; +} + +#endif /* OPENSSL_VERSION_NUMBER */ + +/* + * check peer cert against CRL + */ +result_t +x509_verify_crl(const char *crl_file, X509 *peer_cert, const char *subject) +{ + X509_CRL *crl=NULL; + X509_REVOKED *revoked; + BIO *in=NULL; + int n,i; + result_t retval = FAILURE; + + in = BIO_new_file (crl_file, "r"); + + if (in == NULL) { + msg (M_ERR, "CRL: cannot read: %s", crl_file); + goto end; + } + crl=PEM_read_bio_X509_CRL(in,NULL,NULL,NULL); + if (crl == NULL) { + msg (M_ERR, "CRL: cannot read CRL from file %s", crl_file); + goto end; + } + + if (X509_NAME_cmp(X509_CRL_get_issuer(crl), X509_get_issuer_name(peer_cert)) != 0) { + msg (M_WARN, "CRL: CRL %s is from a different issuer than the issuer of " + "certificate %s", crl_file, subject); + retval = SUCCESS; + goto end; + } + + n = sk_X509_REVOKED_num(X509_CRL_get_REVOKED(crl)); + for (i = 0; i < n; i++) { + revoked = (X509_REVOKED *)sk_X509_REVOKED_value(X509_CRL_get_REVOKED(crl), i); + if (ASN1_INTEGER_cmp(revoked->serialNumber, X509_get_serialNumber(peer_cert)) == 0) { + msg (D_HANDSHAKE, "CRL CHECK FAILED: %s is REVOKED",subject); + goto end; + } + } + + retval = SUCCESS; + msg (D_HANDSHAKE, "CRL CHECK OK: %s",subject); + +end: + BIO_free(in); + if (crl) + X509_CRL_free (crl); + + return retval; +} + +#endif /* defined(ENABLE_SSL) && defined(ENABLE_CRYPTO_OPENSSL) */ -- cgit v1.2.3