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openssl/crypto/x509v3/v3_ncons.c
Matt Caswell 9cde5f8122 Don't use strcasecmp and strncasecmp for IA5 strings 
The functions strcasecmp() and strncasecmp() will use locale specific rules
when performing comparison. This could cause some problems in certain
locales. For example in the Turkish locale an 'I' character is not the
uppercase version of 'i'. However IA5 strings should not use locale specific
rules, i.e. for an IA5 string 'I' is uppercase 'i' even if using the
Turkish locale.

This fixes a bug in name constraints checking reported by Thomas Pornin
(NCCGroup).

This is not considered a security issue because it would require both a
Turkish locale (or other locale with similar issues) and malfeasance by
a trusted name-constrained CA for a certificate to pass name constraints
in error. The constraints also have to be for excluded sub-trees which are
extremely rare. Failure to match permitted subtrees is a bug, not a
vulnerability.

Reviewed-by: Richard Levitte <levitte@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/4569)
2017-10-26 14:43:57 +01:00

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/*
* Copyright 2003-2017 The OpenSSL Project Authors. All Rights Reserved.
*
* Licensed under the OpenSSL license (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 "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");
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++) {
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);
BIO_puts(bp, "\n");
}
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;
}
int NAME_CONSTRAINTS_check_CN(X509 *x, NAME_CONSTRAINTS *nc)
{
int r, i;
X509_NAME *nm;
ASN1_STRING stmp;
GENERAL_NAME gntmp;
stmp.flags = 0;
stmp.type = V_ASN1_IA5STRING;
gntmp.type = GEN_DNS;
gntmp.d.dNSName = &stmp;
nm = X509_get_subject_name(x);
/* Process any commonName attributes in subject name */
for (i = -1;;) {
X509_NAME_ENTRY *ne;
ASN1_STRING *hn;
i = X509_NAME_get_index_by_NID(nm, NID_commonName, i);
if (i == -1)
break;
ne = X509_NAME_get_entry(nm, i);
hn = X509_NAME_ENTRY_get_data(ne);
/* Only process attributes that look like host names */
if (asn1_valid_host(hn)) {
unsigned char *h;
int hlen = ASN1_STRING_to_UTF8(&h, hn);
if (hlen <= 0)
return X509_V_ERR_OUT_OF_MEM;
stmp.length = hlen;
stmp.data = h;
r = nc_match(&gntmp, nc);
OPENSSL_free(h);
if (r != X509_V_OK)
return r;
}
}
return X509_V_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 (sub->minimum || sub->maximum)
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 (sub->minimum || sub->maximum)
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;
}
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