diff options
Diffstat (limited to 'crypto/x509/v3_ncons.c')
-rw-r--r-- | crypto/x509/v3_ncons.c | 700 |
1 files changed, 700 insertions, 0 deletions
diff --git a/crypto/x509/v3_ncons.c b/crypto/x509/v3_ncons.c new file mode 100644 index 0000000000..9a8ca16685 --- /dev/null +++ b/crypto/x509/v3_ncons.c @@ -0,0 +1,700 @@ +/* + * Copyright 2003-2018 The OpenSSL Project Authors. All Rights Reserved. + * + * Licensed under the Apache License 2.0 (the "License"). You may not use + * this file except in compliance with the License. You can obtain a copy + * in the file LICENSE in the source distribution or at + * https://www.openssl.org/source/license.html + */ + +#include "internal/cryptlib.h" +#include "internal/numbers.h" +#include <stdio.h> +#include "internal/asn1_int.h" +#include <openssl/asn1t.h> +#include <openssl/conf.h> +#include <openssl/x509v3.h> +#include <openssl/bn.h> + +#include "internal/x509_int.h" +#include "ext_dat.h" + +static void *v2i_NAME_CONSTRAINTS(const X509V3_EXT_METHOD *method, + X509V3_CTX *ctx, + STACK_OF(CONF_VALUE) *nval); +static int i2r_NAME_CONSTRAINTS(const X509V3_EXT_METHOD *method, void *a, + BIO *bp, int ind); +static int do_i2r_name_constraints(const X509V3_EXT_METHOD *method, + STACK_OF(GENERAL_SUBTREE) *trees, BIO *bp, + int ind, const char *name); +static int print_nc_ipadd(BIO *bp, ASN1_OCTET_STRING *ip); + +static int nc_match(GENERAL_NAME *gen, NAME_CONSTRAINTS *nc); +static int nc_match_single(GENERAL_NAME *sub, GENERAL_NAME *gen); +static int nc_dn(X509_NAME *sub, X509_NAME *nm); +static int nc_dns(ASN1_IA5STRING *sub, ASN1_IA5STRING *dns); +static int nc_email(ASN1_IA5STRING *sub, ASN1_IA5STRING *eml); +static int nc_uri(ASN1_IA5STRING *uri, ASN1_IA5STRING *base); +static int nc_ip(ASN1_OCTET_STRING *ip, ASN1_OCTET_STRING *base); + +const X509V3_EXT_METHOD v3_name_constraints = { + NID_name_constraints, 0, + ASN1_ITEM_ref(NAME_CONSTRAINTS), + 0, 0, 0, 0, + 0, 0, + 0, v2i_NAME_CONSTRAINTS, + i2r_NAME_CONSTRAINTS, 0, + NULL +}; + +ASN1_SEQUENCE(GENERAL_SUBTREE) = { + ASN1_SIMPLE(GENERAL_SUBTREE, base, GENERAL_NAME), + ASN1_IMP_OPT(GENERAL_SUBTREE, minimum, ASN1_INTEGER, 0), + ASN1_IMP_OPT(GENERAL_SUBTREE, maximum, ASN1_INTEGER, 1) +} ASN1_SEQUENCE_END(GENERAL_SUBTREE) + +ASN1_SEQUENCE(NAME_CONSTRAINTS) = { + ASN1_IMP_SEQUENCE_OF_OPT(NAME_CONSTRAINTS, permittedSubtrees, + GENERAL_SUBTREE, 0), + ASN1_IMP_SEQUENCE_OF_OPT(NAME_CONSTRAINTS, excludedSubtrees, + GENERAL_SUBTREE, 1), +} ASN1_SEQUENCE_END(NAME_CONSTRAINTS) + + +IMPLEMENT_ASN1_ALLOC_FUNCTIONS(GENERAL_SUBTREE) +IMPLEMENT_ASN1_ALLOC_FUNCTIONS(NAME_CONSTRAINTS) + +/* + * We cannot use strncasecmp here because that applies locale specific rules. + * For example in Turkish 'I' is not the uppercase character for 'i'. We need to + * do a simple ASCII case comparison ignoring the locale (that is why we use + * numeric constants below). + */ +static int ia5ncasecmp(const char *s1, const char *s2, size_t n) +{ + for (; n > 0; n--, s1++, s2++) { + if (*s1 != *s2) { + unsigned char c1 = (unsigned char)*s1, c2 = (unsigned char)*s2; + + /* Convert to lower case */ + if (c1 >= 0x41 /* A */ && c1 <= 0x5A /* Z */) + c1 += 0x20; + if (c2 >= 0x41 /* A */ && c2 <= 0x5A /* Z */) + c2 += 0x20; + + if (c1 == c2) + continue; + + if (c1 < c2) + return -1; + + /* c1 > c2 */ + return 1; + } else if (*s1 == 0) { + /* If we get here we know that *s2 == 0 too */ + return 0; + } + } + + return 0; +} + +static int ia5casecmp(const char *s1, const char *s2) +{ + return ia5ncasecmp(s1, s2, SIZE_MAX); +} + +static void *v2i_NAME_CONSTRAINTS(const X509V3_EXT_METHOD *method, + X509V3_CTX *ctx, STACK_OF(CONF_VALUE) *nval) +{ + int i; + CONF_VALUE tval, *val; + STACK_OF(GENERAL_SUBTREE) **ptree = NULL; + NAME_CONSTRAINTS *ncons = NULL; + GENERAL_SUBTREE *sub = NULL; + + ncons = NAME_CONSTRAINTS_new(); + if (ncons == NULL) + goto memerr; + for (i = 0; i < sk_CONF_VALUE_num(nval); i++) { + val = sk_CONF_VALUE_value(nval, i); + if (strncmp(val->name, "permitted", 9) == 0 && val->name[9]) { + ptree = &ncons->permittedSubtrees; + tval.name = val->name + 10; + } else if (strncmp(val->name, "excluded", 8) == 0 && val->name[8]) { + ptree = &ncons->excludedSubtrees; + tval.name = val->name + 9; + } else { + X509V3err(X509V3_F_V2I_NAME_CONSTRAINTS, X509V3_R_INVALID_SYNTAX); + goto err; + } + tval.value = val->value; + sub = GENERAL_SUBTREE_new(); + if (sub == NULL) + goto memerr; + if (!v2i_GENERAL_NAME_ex(sub->base, method, ctx, &tval, 1)) + goto err; + if (*ptree == NULL) + *ptree = sk_GENERAL_SUBTREE_new_null(); + if (*ptree == NULL || !sk_GENERAL_SUBTREE_push(*ptree, sub)) + goto memerr; + sub = NULL; + } + + return ncons; + + memerr: + X509V3err(X509V3_F_V2I_NAME_CONSTRAINTS, ERR_R_MALLOC_FAILURE); + err: + NAME_CONSTRAINTS_free(ncons); + GENERAL_SUBTREE_free(sub); + + return NULL; +} + +static int i2r_NAME_CONSTRAINTS(const X509V3_EXT_METHOD *method, void *a, + BIO *bp, int ind) +{ + NAME_CONSTRAINTS *ncons = a; + do_i2r_name_constraints(method, ncons->permittedSubtrees, + bp, ind, "Permitted"); + if (ncons->permittedSubtrees && ncons->excludedSubtrees) + BIO_puts(bp, "\n"); + do_i2r_name_constraints(method, ncons->excludedSubtrees, + bp, ind, "Excluded"); + return 1; +} + +static int do_i2r_name_constraints(const X509V3_EXT_METHOD *method, + STACK_OF(GENERAL_SUBTREE) *trees, + BIO *bp, int ind, const char *name) +{ + GENERAL_SUBTREE *tree; + int i; + if (sk_GENERAL_SUBTREE_num(trees) > 0) + BIO_printf(bp, "%*s%s:\n", ind, "", name); + for (i = 0; i < sk_GENERAL_SUBTREE_num(trees); i++) { + if (i > 0) + BIO_puts(bp, "\n"); + tree = sk_GENERAL_SUBTREE_value(trees, i); + BIO_printf(bp, "%*s", ind + 2, ""); + if (tree->base->type == GEN_IPADD) + print_nc_ipadd(bp, tree->base->d.ip); + else + GENERAL_NAME_print(bp, tree->base); + } + return 1; +} + +static int print_nc_ipadd(BIO *bp, ASN1_OCTET_STRING *ip) +{ + int i, len; + unsigned char *p; + p = ip->data; + len = ip->length; + BIO_puts(bp, "IP:"); + if (len == 8) { + BIO_printf(bp, "%d.%d.%d.%d/%d.%d.%d.%d", + p[0], p[1], p[2], p[3], p[4], p[5], p[6], p[7]); + } else if (len == 32) { + for (i = 0; i < 16; i++) { + BIO_printf(bp, "%X", p[0] << 8 | p[1]); + p += 2; + if (i == 7) + BIO_puts(bp, "/"); + else if (i != 15) + BIO_puts(bp, ":"); + } + } else + BIO_printf(bp, "IP Address:<invalid>"); + return 1; +} + +#define NAME_CHECK_MAX (1 << 20) + +static int add_lengths(int *out, int a, int b) +{ + /* sk_FOO_num(NULL) returns -1 but is effectively 0 when iterating. */ + if (a < 0) + a = 0; + if (b < 0) + b = 0; + + if (a > INT_MAX - b) + return 0; + *out = a + b; + return 1; +} + +/*- + * Check a certificate conforms to a specified set of constraints. + * Return values: + * X509_V_OK: All constraints obeyed. + * X509_V_ERR_PERMITTED_VIOLATION: Permitted subtree violation. + * X509_V_ERR_EXCLUDED_VIOLATION: Excluded subtree violation. + * X509_V_ERR_SUBTREE_MINMAX: Min or max values present and matching type. + * X509_V_ERR_UNSUPPORTED_CONSTRAINT_TYPE: Unsupported constraint type. + * X509_V_ERR_UNSUPPORTED_CONSTRAINT_SYNTAX: bad unsupported constraint syntax. + * X509_V_ERR_UNSUPPORTED_NAME_SYNTAX: bad or unsupported syntax of name + */ + +int NAME_CONSTRAINTS_check(X509 *x, NAME_CONSTRAINTS *nc) +{ + int r, i, name_count, constraint_count; + X509_NAME *nm; + + nm = X509_get_subject_name(x); + + /* + * Guard against certificates with an excessive number of names or + * constraints causing a computationally expensive name constraints check. + */ + if (!add_lengths(&name_count, X509_NAME_entry_count(nm), + sk_GENERAL_NAME_num(x->altname)) + || !add_lengths(&constraint_count, + sk_GENERAL_SUBTREE_num(nc->permittedSubtrees), + sk_GENERAL_SUBTREE_num(nc->excludedSubtrees)) + || (name_count > 0 && constraint_count > NAME_CHECK_MAX / name_count)) + return X509_V_ERR_UNSPECIFIED; + + if (X509_NAME_entry_count(nm) > 0) { + GENERAL_NAME gntmp; + gntmp.type = GEN_DIRNAME; + gntmp.d.directoryName = nm; + + r = nc_match(&gntmp, nc); + + if (r != X509_V_OK) + return r; + + gntmp.type = GEN_EMAIL; + + /* Process any email address attributes in subject name */ + + for (i = -1;;) { + const X509_NAME_ENTRY *ne; + + i = X509_NAME_get_index_by_NID(nm, NID_pkcs9_emailAddress, i); + if (i == -1) + break; + ne = X509_NAME_get_entry(nm, i); + gntmp.d.rfc822Name = X509_NAME_ENTRY_get_data(ne); + if (gntmp.d.rfc822Name->type != V_ASN1_IA5STRING) + return X509_V_ERR_UNSUPPORTED_NAME_SYNTAX; + + r = nc_match(&gntmp, nc); + + if (r != X509_V_OK) + return r; + } + + } + + for (i = 0; i < sk_GENERAL_NAME_num(x->altname); i++) { + GENERAL_NAME *gen = sk_GENERAL_NAME_value(x->altname, i); + r = nc_match(gen, nc); + if (r != X509_V_OK) + return r; + } + + return X509_V_OK; + +} + +static int cn2dnsid(ASN1_STRING *cn, unsigned char **dnsid, size_t *idlen) +{ + int utf8_length; + unsigned char *utf8_value; + int i; + int isdnsname = 0; + + /* Don't leave outputs uninitialized */ + *dnsid = NULL; + *idlen = 0; + + /*- + * Per RFC 6125, DNS-IDs representing internationalized domain names appear + * in certificates in A-label encoded form: + * + * https://tools.ietf.org/html/rfc6125#section-6.4.2 + * + * The same applies to CNs which are intended to represent DNS names. + * However, while in the SAN DNS-IDs are IA5Strings, as CNs they may be + * needlessly encoded in 16-bit Unicode. We perform a conversion to UTF-8 + * to ensure that we get an ASCII representation of any CNs that are + * representable as ASCII, but just not encoded as ASCII. The UTF-8 form + * may contain some non-ASCII octets, and that's fine, such CNs are not + * valid legacy DNS names. + * + * Note, 'int' is the return type of ASN1_STRING_to_UTF8() so that's what + * we must use for 'utf8_length'. + */ + if ((utf8_length = ASN1_STRING_to_UTF8(&utf8_value, cn)) < 0) + return X509_V_ERR_OUT_OF_MEM; + + /* + * Some certificates have had names that include a *trailing* NUL byte. + * Remove these harmless NUL characters. They would otherwise yield false + * alarms with the following embedded NUL check. + */ + while (utf8_length > 0 && utf8_value[utf8_length - 1] == '\0') + --utf8_length; + + /* Reject *embedded* NULs */ + if ((size_t)utf8_length != strlen((char *)utf8_value)) { + OPENSSL_free(utf8_value); + return X509_V_ERR_UNSUPPORTED_NAME_SYNTAX; + } + + /* + * XXX: Deviation from strict DNS name syntax, also check names with '_' + * Check DNS name syntax, any '-' or '.' must be internal, + * and on either side of each '.' we can't have a '-' or '.'. + * + * If the name has just one label, we don't consider it a DNS name. This + * means that "CN=sometld" cannot be precluded by DNS name constraints, but + * that is not a problem. + */ + for (i = 0; i < utf8_length; ++i) { + unsigned char c = utf8_value[i]; + + if ((c >= 'a' && c <= 'z') + || (c >= 'A' && c <= 'Z') + || (c >= '0' && c <= '9') + || c == '_') + continue; + + /* Dot and hyphen cannot be first or last. */ + if (i > 0 && i < utf8_length - 1) { + if (c == '-') + continue; + /* + * Next to a dot the preceding and following characters must not be + * another dot or a hyphen. Otherwise, record that the name is + * plausible, since it has two or more labels. + */ + if (c == '.' + && utf8_value[i + 1] != '.' + && utf8_value[i - 1] != '-' + && utf8_value[i + 1] != '-') { + isdnsname = 1; + continue; + } + } + isdnsname = 0; + break; + } + + if (isdnsname) { + *dnsid = utf8_value; + *idlen = (size_t)utf8_length; + return X509_V_OK; + } + OPENSSL_free(utf8_value); + return X509_V_OK; +} + +/* + * Check CN against DNS-ID name constraints. + */ +int NAME_CONSTRAINTS_check_CN(X509 *x, NAME_CONSTRAINTS *nc) +{ + int r, i; + X509_NAME *nm = X509_get_subject_name(x); + ASN1_STRING stmp; + GENERAL_NAME gntmp; + + stmp.flags = 0; + stmp.type = V_ASN1_IA5STRING; + gntmp.type = GEN_DNS; + gntmp.d.dNSName = &stmp; + + /* Process any commonName attributes in subject name */ + + for (i = -1;;) { + X509_NAME_ENTRY *ne; + ASN1_STRING *cn; + unsigned char *idval; + size_t idlen; + + i = X509_NAME_get_index_by_NID(nm, NID_commonName, i); + if (i == -1) + break; + ne = X509_NAME_get_entry(nm, i); + cn = X509_NAME_ENTRY_get_data(ne); + + /* Only process attributes that look like host names */ + if ((r = cn2dnsid(cn, &idval, &idlen)) != X509_V_OK) + return r; + if (idlen == 0) + continue; + + stmp.length = idlen; + stmp.data = idval; + r = nc_match(&gntmp, nc); + OPENSSL_free(idval); + if (r != X509_V_OK) + return r; + } + return X509_V_OK; +} + +/* + * Return nonzero if the GeneralSubtree has valid 'minimum' field + * (must be absent or 0) and valid 'maximum' field (must be absent). + */ +static int nc_minmax_valid(GENERAL_SUBTREE *sub) { + BIGNUM *bn = NULL; + int ok = 1; + + if (sub->maximum) + ok = 0; + + if (sub->minimum) { + bn = ASN1_INTEGER_to_BN(sub->minimum, NULL); + if (bn == NULL || !BN_is_zero(bn)) + ok = 0; + BN_free(bn); + } + + return ok; +} + +static int nc_match(GENERAL_NAME *gen, NAME_CONSTRAINTS *nc) +{ + GENERAL_SUBTREE *sub; + int i, r, match = 0; + + /* + * Permitted subtrees: if any subtrees exist of matching the type at + * least one subtree must match. + */ + + for (i = 0; i < sk_GENERAL_SUBTREE_num(nc->permittedSubtrees); i++) { + sub = sk_GENERAL_SUBTREE_value(nc->permittedSubtrees, i); + if (gen->type != sub->base->type) + continue; + if (!nc_minmax_valid(sub)) + return X509_V_ERR_SUBTREE_MINMAX; + /* If we already have a match don't bother trying any more */ + if (match == 2) + continue; + if (match == 0) + match = 1; + r = nc_match_single(gen, sub->base); + if (r == X509_V_OK) + match = 2; + else if (r != X509_V_ERR_PERMITTED_VIOLATION) + return r; + } + + if (match == 1) + return X509_V_ERR_PERMITTED_VIOLATION; + + /* Excluded subtrees: must not match any of these */ + + for (i = 0; i < sk_GENERAL_SUBTREE_num(nc->excludedSubtrees); i++) { + sub = sk_GENERAL_SUBTREE_value(nc->excludedSubtrees, i); + if (gen->type != sub->base->type) + continue; + if (!nc_minmax_valid(sub)) + return X509_V_ERR_SUBTREE_MINMAX; + + r = nc_match_single(gen, sub->base); + if (r == X509_V_OK) + return X509_V_ERR_EXCLUDED_VIOLATION; + else if (r != X509_V_ERR_PERMITTED_VIOLATION) + return r; + + } + + return X509_V_OK; + +} + +static int nc_match_single(GENERAL_NAME *gen, GENERAL_NAME *base) +{ + switch (base->type) { + case GEN_DIRNAME: + return nc_dn(gen->d.directoryName, base->d.directoryName); + + case GEN_DNS: + return nc_dns(gen->d.dNSName, base->d.dNSName); + + case GEN_EMAIL: + return nc_email(gen->d.rfc822Name, base->d.rfc822Name); + + case GEN_URI: + return nc_uri(gen->d.uniformResourceIdentifier, + base->d.uniformResourceIdentifier); + + case GEN_IPADD: + return nc_ip(gen->d.iPAddress, base->d.iPAddress); + + default: + return X509_V_ERR_UNSUPPORTED_CONSTRAINT_TYPE; + } + +} + +/* + * directoryName name constraint matching. The canonical encoding of + * X509_NAME makes this comparison easy. It is matched if the subtree is a + * subset of the name. + */ + +static int nc_dn(X509_NAME *nm, X509_NAME *base) +{ + /* Ensure canonical encodings are up to date. */ + if (nm->modified && i2d_X509_NAME(nm, NULL) < 0) + return X509_V_ERR_OUT_OF_MEM; + if (base->modified && i2d_X509_NAME(base, NULL) < 0) + return X509_V_ERR_OUT_OF_MEM; + if (base->canon_enclen > nm->canon_enclen) + return X509_V_ERR_PERMITTED_VIOLATION; + if (memcmp(base->canon_enc, nm->canon_enc, base->canon_enclen)) + return X509_V_ERR_PERMITTED_VIOLATION; + return X509_V_OK; +} + +static int nc_dns(ASN1_IA5STRING *dns, ASN1_IA5STRING *base) +{ + char *baseptr = (char *)base->data; + char *dnsptr = (char *)dns->data; + /* Empty matches everything */ + if (!*baseptr) + return X509_V_OK; + /* + * Otherwise can add zero or more components on the left so compare RHS + * and if dns is longer and expect '.' as preceding character. + */ + if (dns->length > base->length) { + dnsptr += dns->length - base->length; + if (*baseptr != '.' && dnsptr[-1] != '.') + return X509_V_ERR_PERMITTED_VIOLATION; + } + + if (ia5casecmp(baseptr, dnsptr)) + return X509_V_ERR_PERMITTED_VIOLATION; + + return X509_V_OK; + +} + +static int nc_email(ASN1_IA5STRING *eml, ASN1_IA5STRING *base) +{ + const char *baseptr = (char *)base->data; + const char *emlptr = (char *)eml->data; + + const char *baseat = strchr(baseptr, '@'); + const char *emlat = strchr(emlptr, '@'); + if (!emlat) + return X509_V_ERR_UNSUPPORTED_NAME_SYNTAX; + /* Special case: initial '.' is RHS match */ + if (!baseat && (*baseptr == '.')) { + if (eml->length > base->length) { + emlptr += eml->length - base->length; + if (ia5casecmp(baseptr, emlptr) == 0) + return X509_V_OK; + } + return X509_V_ERR_PERMITTED_VIOLATION; + } + + /* If we have anything before '@' match local part */ + + if (baseat) { + if (baseat != baseptr) { + if ((baseat - baseptr) != (emlat - emlptr)) + return X509_V_ERR_PERMITTED_VIOLATION; + /* Case sensitive match of local part */ + if (strncmp(baseptr, emlptr, emlat - emlptr)) + return X509_V_ERR_PERMITTED_VIOLATION; + } + /* Position base after '@' */ + baseptr = baseat + 1; + } + emlptr = emlat + 1; + /* Just have hostname left to match: case insensitive */ + if (ia5casecmp(baseptr, emlptr)) + return X509_V_ERR_PERMITTED_VIOLATION; + + return X509_V_OK; + +} + +static int nc_uri(ASN1_IA5STRING *uri, ASN1_IA5STRING *base) +{ + const char *baseptr = (char *)base->data; + const char *hostptr = (char *)uri->data; + const char *p = strchr(hostptr, ':'); + int hostlen; + /* Check for foo:// and skip past it */ + if (!p || (p[1] != '/') || (p[2] != '/')) + return X509_V_ERR_UNSUPPORTED_NAME_SYNTAX; + hostptr = p + 3; + + /* Determine length of hostname part of URI */ + + /* Look for a port indicator as end of hostname first */ + + p = strchr(hostptr, ':'); + /* Otherwise look for trailing slash */ + if (!p) + p = strchr(hostptr, '/'); + + if (!p) + hostlen = strlen(hostptr); + else + hostlen = p - hostptr; + + if (hostlen == 0) + return X509_V_ERR_UNSUPPORTED_NAME_SYNTAX; + + /* Special case: initial '.' is RHS match */ + if (*baseptr == '.') { + if (hostlen > base->length) { + p = hostptr + hostlen - base->length; + if (ia5ncasecmp(p, baseptr, base->length) == 0) + return X509_V_OK; + } + return X509_V_ERR_PERMITTED_VIOLATION; + } + + if ((base->length != (int)hostlen) + || ia5ncasecmp(hostptr, baseptr, hostlen)) + return X509_V_ERR_PERMITTED_VIOLATION; + + return X509_V_OK; + +} + +static int nc_ip(ASN1_OCTET_STRING *ip, ASN1_OCTET_STRING *base) +{ + int hostlen, baselen, i; + unsigned char *hostptr, *baseptr, *maskptr; + hostptr = ip->data; + hostlen = ip->length; + baseptr = base->data; + baselen = base->length; + + /* Invalid if not IPv4 or IPv6 */ + if (!((hostlen == 4) || (hostlen == 16))) + return X509_V_ERR_UNSUPPORTED_NAME_SYNTAX; + if (!((baselen == 8) || (baselen == 32))) + return X509_V_ERR_UNSUPPORTED_NAME_SYNTAX; + + /* Do not match IPv4 with IPv6 */ + if (hostlen * 2 != baselen) + return X509_V_ERR_PERMITTED_VIOLATION; + + maskptr = base->data + hostlen; + + /* Considering possible not aligned base ipAddress */ + /* Not checking for wrong mask definition: i.e.: 255.0.255.0 */ + for (i = 0; i < hostlen; i++) + if ((hostptr[i] & maskptr[i]) != (baseptr[i] & maskptr[i])) + return X509_V_ERR_PERMITTED_VIOLATION; + + return X509_V_OK; + +} |