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Client-side namecheck wildcards.

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A client reference identity of ".example.com" matches a server
certificate presented identity that is any sub-domain of "example.com"
(e.g. "www.sub.example.com).

With the X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS flag, it matches
only direct child sub-domains (e.g. "www.sub.example.com").
This commit is contained in:
Viktor Dukhovni
2014-06-12 01:56:31 -04:00
committed by Dr. Stephen Henson
parent abfb989fe0
commit a09e4d24ad
4 changed files with 90 additions and 11 deletions
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59
crypto/x509v3/v3_utl.c
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@@ -572,11 +572,50 @@ 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. (We check again that subject starts with '.' and
* contains at least one subsequent character, just in case the
* internal _X509_CHECK_FLAG_DOT_SUBDOMAINS flag was erroneously
* set by the user).
*/
if ((flags & _X509_CHECK_FLAG_DOT_SUBDOMAINS) == 0 ||
subject_len <= 1 || subject[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;
}
}
/* Compare while ASCII ignoring case. */
static int equal_nocase(const unsigned char *pattern, size_t pattern_len,
const unsigned char *subject, size_t subject_len,
unsigned int unused_flags)
unsigned int flags)
{
skip_prefix(&pattern, &pattern_len, subject, subject_len, flags);
if (pattern_len != subject_len)
return 0;
while (pattern_len)
@@ -605,11 +644,9 @@ static int equal_nocase(const unsigned char *pattern, size_t pattern_len,
/* Compare using memcmp. */
static int equal_case(const unsigned char *pattern, size_t pattern_len,
const unsigned char *subject, size_t subject_len,
unsigned int unused_flags)
unsigned int flags)
{
/* The pattern must not contain NUL characters. */
if (memchr(pattern, '\0', pattern_len) != NULL)
return 0;
skip_prefix(&pattern, &pattern_len, subject, subject_len, flags);
if (pattern_len != subject_len)
return 0;
return !memcmp(pattern, subject, pattern_len);
@@ -797,7 +834,14 @@ 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 = valid_star(pattern, pattern_len, 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);
@@ -860,6 +904,9 @@ static int do_x509_check(X509 *x, const unsigned char *chk, size_t chklen,
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;