From 4bb261b015d382a567563571ae4d399a16caebe2 Mon Sep 17 00:00:00 2001 From: "C. McEnroe" Date: Mon, 27 Jul 2020 21:55:29 -0400 Subject: Import LibreSSL 3.2.0 --- tls_verify.c | 280 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 280 insertions(+) create mode 100644 tls_verify.c (limited to 'tls_verify.c') diff --git a/tls_verify.c b/tls_verify.c new file mode 100644 index 0000000..acbe163 --- /dev/null +++ b/tls_verify.c @@ -0,0 +1,280 @@ +/* $OpenBSD: tls_verify.c,v 1.20 2018/02/05 00:52:24 jsing Exp $ */ +/* + * Copyright (c) 2014 Jeremie Courreges-Anglas + * + * 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 + +#include +#include + +#include + +#include + +#include +#include "tls_internal.h" + +static int +tls_match_name(const char *cert_name, const char *name) +{ + const char *cert_domain, *domain, *next_dot; + + if (strcasecmp(cert_name, name) == 0) + return 0; + + /* Wildcard match? */ + if (cert_name[0] == '*') { + /* + * Valid wildcards: + * - "*.domain.tld" + * - "*.sub.domain.tld" + * - etc. + * Reject "*.tld". + * No attempt to prevent the use of eg. "*.co.uk". + */ + cert_domain = &cert_name[1]; + /* Disallow "*" */ + if (cert_domain[0] == '\0') + return -1; + /* Disallow "*foo" */ + if (cert_domain[0] != '.') + return -1; + /* Disallow "*.." */ + if (cert_domain[1] == '.') + return -1; + next_dot = strchr(&cert_domain[1], '.'); + /* Disallow "*.bar" */ + if (next_dot == NULL) + return -1; + /* Disallow "*.bar.." */ + if (next_dot[1] == '.') + return -1; + + domain = strchr(name, '.'); + + /* No wildcard match against a name with no host part. */ + if (name[0] == '.') + return -1; + /* No wildcard match against a name with no domain part. */ + if (domain == NULL || strlen(domain) == 1) + return -1; + + if (strcasecmp(cert_domain, domain) == 0) + return 0; + } + + return -1; +} + +/* + * See RFC 5280 section 4.2.1.6 for SubjectAltName details. + * alt_match is set to 1 if a matching alternate name is found. + * alt_exists is set to 1 if any known alternate name exists in the certificate. + */ +static int +tls_check_subject_altname(struct tls *ctx, X509 *cert, const char *name, + int *alt_match, int *alt_exists) +{ + STACK_OF(GENERAL_NAME) *altname_stack = NULL; + union tls_addr addrbuf; + int addrlen, type; + int count, i; + int rv = 0; + + *alt_match = 0; + *alt_exists = 0; + + altname_stack = X509_get_ext_d2i(cert, NID_subject_alt_name, + NULL, NULL); + if (altname_stack == NULL) + return 0; + + if (inet_pton(AF_INET, name, &addrbuf) == 1) { + type = GEN_IPADD; + addrlen = 4; + } else if (inet_pton(AF_INET6, name, &addrbuf) == 1) { + type = GEN_IPADD; + addrlen = 16; + } else { + type = GEN_DNS; + addrlen = 0; + } + + count = sk_GENERAL_NAME_num(altname_stack); + for (i = 0; i < count; i++) { + GENERAL_NAME *altname; + + altname = sk_GENERAL_NAME_value(altname_stack, i); + + if (altname->type == GEN_DNS || altname->type == GEN_IPADD) + *alt_exists = 1; + + if (altname->type != type) + continue; + + if (type == GEN_DNS) { + unsigned char *data; + int format, len; + + format = ASN1_STRING_type(altname->d.dNSName); + if (format == V_ASN1_IA5STRING) { + data = ASN1_STRING_data(altname->d.dNSName); + len = ASN1_STRING_length(altname->d.dNSName); + + if (len < 0 || (size_t)len != strlen(data)) { + tls_set_errorx(ctx, + "error verifying name '%s': " + "NUL byte in subjectAltName, " + "probably a malicious certificate", + name); + rv = -1; + break; + } + + /* + * Per RFC 5280 section 4.2.1.6: + * " " is a legal domain name, but that + * dNSName must be rejected. + */ + if (strcmp(data, " ") == 0) { + tls_set_errorx(ctx, + "error verifying name '%s': " + "a dNSName of \" \" must not be " + "used", name); + rv = -1; + break; + } + + if (tls_match_name(data, name) == 0) { + *alt_match = 1; + break; + } + } else { +#ifdef DEBUG + fprintf(stdout, "%s: unhandled subjectAltName " + "dNSName encoding (%d)\n", getprogname(), + format); +#endif + } + + } else if (type == GEN_IPADD) { + unsigned char *data; + int datalen; + + datalen = ASN1_STRING_length(altname->d.iPAddress); + data = ASN1_STRING_data(altname->d.iPAddress); + + if (datalen < 0) { + tls_set_errorx(ctx, + "Unexpected negative length for an " + "IP address: %d", datalen); + rv = -1; + break; + } + + /* + * Per RFC 5280 section 4.2.1.6: + * IPv4 must use 4 octets and IPv6 must use 16 octets. + */ + if (datalen == addrlen && + memcmp(data, &addrbuf, addrlen) == 0) { + *alt_match = 1; + break; + } + } + } + + sk_GENERAL_NAME_pop_free(altname_stack, GENERAL_NAME_free); + return rv; +} + +static int +tls_check_common_name(struct tls *ctx, X509 *cert, const char *name, + int *cn_match) +{ + X509_NAME *subject_name; + char *common_name = NULL; + union tls_addr addrbuf; + int common_name_len; + int rv = 0; + + *cn_match = 0; + + subject_name = X509_get_subject_name(cert); + if (subject_name == NULL) + goto done; + + common_name_len = X509_NAME_get_text_by_NID(subject_name, + NID_commonName, NULL, 0); + if (common_name_len < 0) + goto done; + + common_name = calloc(common_name_len + 1, 1); + if (common_name == NULL) + goto done; + + X509_NAME_get_text_by_NID(subject_name, NID_commonName, common_name, + common_name_len + 1); + + /* NUL bytes in CN? */ + if (common_name_len < 0 || + (size_t)common_name_len != strlen(common_name)) { + tls_set_errorx(ctx, "error verifying name '%s': " + "NUL byte in Common Name field, " + "probably a malicious certificate", name); + rv = -1; + goto done; + } + + /* + * We don't want to attempt wildcard matching against IP addresses, + * so perform a simple comparison here. + */ + if (inet_pton(AF_INET, name, &addrbuf) == 1 || + inet_pton(AF_INET6, name, &addrbuf) == 1) { + if (strcmp(common_name, name) == 0) + *cn_match = 1; + goto done; + } + + if (tls_match_name(common_name, name) == 0) + *cn_match = 1; + + done: + free(common_name); + return rv; +} + +int +tls_check_name(struct tls *ctx, X509 *cert, const char *name, int *match) +{ + int alt_exists; + + *match = 0; + + if (tls_check_subject_altname(ctx, cert, name, match, + &alt_exists) == -1) + return -1; + + /* + * As per RFC 6125 section 6.4.4, if any known alternate name existed + * in the certificate, we do not attempt to match on the CN. + */ + if (*match || alt_exists) + return 0; + + return tls_check_common_name(ctx, cert, name, match); +} -- cgit 1.4.1