#include <string.h>
#include <strings.h>
#include "openssl-compat.h"
#ifdef OSSL_COMPAT_NEED_X509_CHECK
/* libressl 2.5.5 implementation of X509_check_host() */
typedef int (*equal_fn) (const unsigned char *pattern, size_t pattern_len,
const unsigned char *subject, size_t subject_len, unsigned int flags);
/* Skip pattern prefix to match "wildcard" subject */
static void skip_prefix(const unsigned char **p, size_t *plen,
const unsigned char *subject, size_t subject_len, unsigned int flags)
{
const unsigned char *pattern = *p;
size_t pattern_len = *plen;
/*
* If subject starts with a leading '.' followed by more octets, and
* pattern is longer, compare just an equal-length suffix with the
* full subject (starting at the '.'), provided the prefix contains
* no NULs.
*/
if ((flags & _X509_CHECK_FLAG_DOT_SUBDOMAINS) == 0)
return;
while (pattern_len > subject_len && *pattern) {
if ((flags & X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS) &&
*pattern == '.')
break;
++pattern;
--pattern_len;
}
/* Skip if entire prefix acceptable */
if (pattern_len == subject_len) {
*p = pattern;
*plen = pattern_len;
}
}
/*
* Open/BoringSSL uses memcmp for "equal_case" while their
* "equal_nocase" function is a hand-rolled strncasecmp that does not
* allow \0 in the pattern. Since an embedded \0 is likely a sign of
* problems, we simply don't allow it in either case, and then we use
* standard libc funcitons.
*/
/* Compare using strncasecmp */
static int equal_nocase(const unsigned char *pattern, size_t pattern_len,
const unsigned char *subject, size_t subject_len,
unsigned int flags)
{
if (memchr(pattern, '\0', pattern_len) != NULL)
return 0;
if (memchr(subject, '\0', subject_len) != NULL)
return 0;
skip_prefix(&pattern, &pattern_len, subject, subject_len, flags);
if (pattern_len != subject_len)
return 0;
return (strncasecmp((const char *)pattern, (const char *)subject, pattern_len) == 0);
}
/* Compare using strncmp. */
static int equal_case(const unsigned char *pattern, size_t pattern_len,
const unsigned char *subject, size_t subject_len,
unsigned int flags)
{
if (memchr(pattern, 0, pattern_len) != NULL)
return 0;
if (memchr(subject, 0, subject_len) != NULL)
return 0;
skip_prefix(&pattern, &pattern_len, subject, subject_len, flags);
if (pattern_len != subject_len)
return 0;
return (strncmp((const char *)pattern, (const char *)subject, pattern_len) == 0);
}
/*
* RFC 5280, section 7.5, requires that only the domain is compared in a
* case-insensitive manner.
*/
static int equal_email(const unsigned char *a, size_t a_len,
const unsigned char *b, size_t b_len,
unsigned int unused_flags)
{
size_t pos = a_len;
if (a_len != b_len)
return 0;
/*
* We search backwards for the '@' character, so that we do not have to
* deal with quoted local-parts. The domain part is compared in a
* case-insensitive manner.
*/
while (pos > 0) {
pos--;
if (a[pos] == '@' || b[pos] == '@') {
if (!equal_nocase(a + pos, a_len - pos, b + pos, a_len - pos, 0))
return 0;
break;
}
}
if (pos == 0)
pos = a_len;
return equal_case(a, pos, b, pos, 0);
}
/*
* Compare the prefix and suffix with the subject, and check that the
* characters in-between are valid.
*/
static int wildcard_match(const unsigned char *prefix, size_t prefix_len,
const unsigned char *suffix, size_t suffix_len,
const unsigned char *subject, size_t subject_len, unsigned int flags)
{
const unsigned char *wildcard_start;
const unsigned char *wildcard_end;
const unsigned char *p;
int allow_multi = 0;
int allow_idna = 0;
if (subject_len < prefix_len + suffix_len)
return 0;
if (!equal_nocase(prefix, prefix_len, subject, prefix_len, flags))
return 0;
wildcard_start = subject + prefix_len;
wildcard_end = subject + (subject_len - suffix_len);
if (!equal_nocase(wildcard_end, suffix_len, suffix, suffix_len, flags))
return 0;
/*
* If the wildcard makes up the entire first label, it must match at
* least one character.
*/
if (prefix_len == 0 && *suffix == '.') {
if (wildcard_start == wildcard_end)
return 0;
allow_idna = 1;
if (flags & X509_CHECK_FLAG_MULTI_LABEL_WILDCARDS)
allow_multi = 1;
}
/* IDNA labels cannot match partial wildcards */
if (!allow_idna &&
subject_len >= 4
&& strncasecmp((const char *)subject, "xn--", 4) == 0)
return 0;
/* The wildcard may match a literal '*' */
if (wildcard_end == wildcard_start + 1 && *wildcard_start == '*')
return 1;
/*
* Check that the part matched by the wildcard contains only
* permitted characters and only matches a single label unless
* allow_multi is set.
*/
for (p = wildcard_start; p != wildcard_end; ++p)
if (!(('0' <= *p && *p <= '9') || ('A' <= *p && *p <= 'Z') ||
('a' <= *p && *p <= 'z') || *p == '-' ||
(allow_multi && *p == '.')))
return 0;
return 1;
}
#define LABEL_START (1 << 0)
#define LABEL_END (1 << 1)
#define LABEL_HYPHEN (1 << 2)
#define LABEL_IDNA (1 << 3)
static const unsigned char *valid_star(const unsigned char *p, size_t len,
unsigned int flags)
{
const unsigned char *star = 0;
size_t i;
int state = LABEL_START;
int dots = 0;
for (i = 0; i < len; ++i) {
/*
* Locate first and only legal wildcard, either at the start
* or end of a non-IDNA first and not final label.
*/
if (p[i] == '*') {
int atstart = (state & LABEL_START);
int atend = (i == len - 1 || p[i + 1] == '.');
/*
* At most one wildcard per pattern.
* No wildcards in IDNA labels.
* No wildcards after the first label.
*/
if (star != NULL || (state & LABEL_IDNA) != 0 || dots)
return NULL;
/* Only full-label '*.example.com' wildcards? */
if ((flags & X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS)
&& (!atstart || !atend))
return NULL;
/* No 'foo*bar' wildcards */
if (!atstart && !atend)
return NULL;
star = &p[i];
state &= ~LABEL_START;
} else if ((state & LABEL_START) != 0) {
/*
* At the start of a label, skip any "xn--" and
* remain in the LABEL_START state, but set the
* IDNA label state
*/
if ((state & LABEL_IDNA) == 0 && len - i >= 4
&& strncasecmp((const char *)&p[i], "xn--", 4) == 0) {
i += 3;
state |= LABEL_IDNA;
continue;
}
/* Labels must start with a letter or digit */
state &= ~LABEL_START;
if (('a' <= p[i] && p[i] <= 'z')
|| ('A' <= p[i] && p[i] <= 'Z')
|| ('0' <= p[i] && p[i] <= '9'))
continue;
return NULL;
} else if (('a' <= p[i] && p[i] <= 'z')
|| ('A' <= p[i] && p[i] <= 'Z')
|| ('0' <= p[i] && p[i] <= '9')) {
state &= LABEL_IDNA;
continue;
} else if (p[i] == '.') {
if (state & (LABEL_HYPHEN | LABEL_START))
return NULL;
state = LABEL_START;
++dots;
} else if (p[i] == '-') {
/* no domain/subdomain starts with '-' */
if ((state & LABEL_START) != 0)
return NULL;
state |= LABEL_HYPHEN;
} else
return NULL;
}
/*
* The final label must not end in a hyphen or ".", and
* there must be at least two dots after the star.
*/
if ((state & (LABEL_START | LABEL_HYPHEN)) != 0 || dots < 2)
return NULL;
return star;
}
/* Compare using wildcards. */
static int equal_wildcard(const unsigned char *pattern, size_t pattern_len,
const unsigned char *subject, size_t subject_len, unsigned int flags)
{
const unsigned char *star = NULL;
/*
* Subject names starting with '.' can only match a wildcard pattern
* via a subject sub-domain pattern suffix match.
*/
if (!(subject_len > 1 && subject[0] == '.'))
star = valid_star(pattern, pattern_len, flags);
if (star == NULL)
return equal_nocase(pattern, pattern_len,
subject, subject_len, flags);
return wildcard_match(pattern, star - pattern,
star + 1, (pattern + pattern_len) - star - 1,
subject, subject_len, flags);
}
/*
* Compare an ASN1_STRING to a supplied string. If they match return 1. If
* cmp_type > 0 only compare if string matches the type, otherwise convert it
* to UTF8.
*/
static int
do_check_string(ASN1_STRING *a, int cmp_type, equal_fn equal,
unsigned int flags, const char *b, size_t blen, char **peername)
{
int rv = 0;
if (!a->data || !a->length)
return 0;
if (cmp_type > 0) {
if (cmp_type != a->type)
return 0;
if (cmp_type == V_ASN1_IA5STRING)
rv = equal(a->data, a->length, (unsigned char *)b,
blen, flags);
else if (a->length == (int)blen && !memcmp(a->data, b, blen))
rv = 1;
if (rv > 0 && peername &&
(*peername = strndup((char *)a->data, a->length)) == NULL)
rv = -1;
} else {
int astrlen;
unsigned char *astr;
astrlen = ASN1_STRING_to_UTF8(&astr, a);
if (astrlen < 0)
return -1;
rv = equal(astr, astrlen, (unsigned char *)b, blen, flags);
if (rv > 0 && peername &&
(*peername = strndup((char *)astr, astrlen)) == NULL)
rv = -1;
free(astr);
}
return rv;
}
static int do_x509_check(X509 *x, const char *chk, size_t chklen,
unsigned int flags, int check_type, char **peername)
{
GENERAL_NAMES *gens = NULL;
X509_NAME *name = NULL;
size_t i;
int j;
int cnid = NID_undef;
int alt_type;
int san_present = 0;
int rv = 0;
equal_fn equal;
/* See below, this flag is internal-only */
flags &= ~_X509_CHECK_FLAG_DOT_SUBDOMAINS;
if (check_type == GEN_EMAIL) {
cnid = NID_pkcs9_emailAddress;
alt_type = V_ASN1_IA5STRING;
equal = equal_email;
} else if (check_type == GEN_DNS) {
cnid = NID_commonName;
/* Implicit client-side DNS sub-domain pattern */
if (chklen > 1 && chk[0] == '.')
flags |= _X509_CHECK_FLAG_DOT_SUBDOMAINS;
alt_type = V_ASN1_IA5STRING;
if (flags & X509_CHECK_FLAG_NO_WILDCARDS)
equal = equal_nocase;
else
equal = equal_wildcard;
} else {
alt_type = V_ASN1_OCTET_STRING;
equal = equal_case;
}
gens = X509_get_ext_d2i(x, NID_subject_alt_name, NULL, NULL);
if (gens != NULL) {
for (i = 0; i < sk_GENERAL_NAME_num(gens); i++) {
GENERAL_NAME *gen;
ASN1_STRING *cstr;
gen = sk_GENERAL_NAME_value(gens, i);
if (gen->type != check_type)
continue;
san_present = 1;
if (check_type == GEN_EMAIL)
cstr = gen->d.rfc822Name;
else if (check_type == GEN_DNS)
cstr = gen->d.dNSName;
else
cstr = gen->d.iPAddress;
/* Positive on success, negative on error! */
if ((rv = do_check_string(cstr, alt_type, equal, flags,
chk, chklen, peername)) != 0)
break;
}
GENERAL_NAMES_free(gens);
if (rv != 0)
return rv;
if (cnid == NID_undef ||
(san_present &&
!(flags & X509_CHECK_FLAG_ALWAYS_CHECK_SUBJECT)))
return 0;
}
/* We're done if CN-ID is not pertinent */
if (cnid == NID_undef)
return 0;
j = -1;
name = X509_get_subject_name(x);
while ((j = X509_NAME_get_index_by_NID(name, cnid, j)) >= 0) {
X509_NAME_ENTRY *ne;
ASN1_STRING *str;
if ((ne = X509_NAME_get_entry(name, j)) == NULL)
return -1;
if ((str = X509_NAME_ENTRY_get_data(ne)) == NULL)
return -1;
/* Positive on success, negative on error! */
if ((rv = do_check_string(str, -1, equal, flags,
chk, chklen, peername)) != 0)
return rv;
}
return 0;
}
int X509_check_host(X509 *x, const char *chk, size_t chklen,
unsigned int flags, char **peername)
{
if (chk == NULL)
return -2;
if (memchr(chk, '\0', chklen))
return -2;
return do_x509_check(x, chk, chklen, flags, GEN_DNS, peername);
}
#endif
