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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").
(cherry picked from commit e52c52f10bb8e34aaf8f28f3e5b56939e8f6b357)
This commit is contained in:
Viktor Dukhovni 2014-06-12 01:56:31 -04:00 committed by Dr. Stephen Henson
parent 3d86077427
commit 3cc8a3f234
4 changed files with 90 additions and 11 deletions
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59
crypto/x509v3/v3_utl.c
View File

@ -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;

11
crypto/x509v3/v3nametest.c
View File

@ -11,6 +11,7 @@ static const char *const names[] =
"*@example.com", "test@*.example.com", "example.com", "www.example.com",
"test.www.example.com", "*.example.com", "*.www.example.com",
"test.*.example.com", "www.*.com",
".www.example.com", "*www.example.com",
"example.net", "xn--rger-koa.example.com",
"a.example.com", "b.example.com",
"postmaster@example.com", "Postmaster@example.com",
@ -25,6 +26,11 @@ static const char *const exceptions[] =
"set CN: host: [*.example.com] matches [www.example.com]",
"set CN: host: [*.example.com] matches [xn--rger-koa.example.com]",
"set CN: host: [*.www.example.com] matches [test.www.example.com]",
"set CN: host: [*.www.example.com] matches [.www.example.com]",
"set CN: host: [*www.example.com] matches [www.example.com]",
"set CN: host: [test.www.example.com] matches [.www.example.com]",
"set CN: host-no-wildcards: [*.www.example.com] matches [.www.example.com]",
"set CN: host-no-wildcards: [test.www.example.com] matches [.www.example.com]",
"set emailAddress: email: [postmaster@example.com] does not match [Postmaster@example.com]",
"set emailAddress: email: [postmaster@EXAMPLE.COM] does not match [Postmaster@example.com]",
"set emailAddress: email: [Postmaster@example.com] does not match [postmaster@example.com]",
@ -34,6 +40,11 @@ static const char *const exceptions[] =
"set dnsName: host: [*.example.com] matches [b.example.com]",
"set dnsName: host: [*.example.com] matches [xn--rger-koa.example.com]",
"set dnsName: host: [*.www.example.com] matches [test.www.example.com]",
"set dnsName: host-no-wildcards: [*.www.example.com] matches [.www.example.com]",
"set dnsName: host-no-wildcards: [test.www.example.com] matches [.www.example.com]",
"set dnsName: host: [*.www.example.com] matches [.www.example.com]",
"set dnsName: host: [*www.example.com] matches [www.example.com]",
"set dnsName: host: [test.www.example.com] matches [.www.example.com]",
"set rfc822Name: email: [postmaster@example.com] does not match [Postmaster@example.com]",
"set rfc822Name: email: [Postmaster@example.com] does not match [postmaster@example.com]",
"set rfc822Name: email: [Postmaster@example.com] does not match [postmaster@EXAMPLE.COM]",

8
crypto/x509v3/x509v3.h
View File

@ -710,6 +710,14 @@ STACK_OF(OPENSSL_STRING) *X509_get1_ocsp(X509 *x);
#define X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS 0x4
/* Allow (non-partial) wildcards to match multiple labels. */
#define X509_CHECK_FLAG_MULTI_LABEL_WILDCARDS 0x8
/* Constraint verifier subdomain patterns to match a single labels. */
#define X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS 0x10
/*
* Match reference identifiers starting with "." to any sub-domain.
* This is a non-public flag, turned on implicitly when the subject
* reference identity is a DNS name.
*/
#define _X509_CHECK_FLAG_DOT_SUBDOMAINS 0x8000
int X509_check_host(X509 *x, const unsigned char *chk, size_t chklen,
unsigned int flags);

23
doc/crypto/X509_check_host.pod
View File

@ -27,7 +27,10 @@ X509_check_host() checks if the certificate matches the specified
host name, which must be encoded in the preferred name syntax
described in section 3.5 of RFC 1034. The B<namelen> argument must be
the number of characters in the name string or zero in which case the
length is calculated with strlen(name).
length is calculated with strlen(name). When B<name> starts with
a dot (e.g ".example.com"), it will be matched by a certificate
valid for any sub-domain of B<name>, (see also
B<X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS> below).
X509_check_email() checks if the certificate matches the specified
email address. Only the mailbox syntax of RFC 822 is supported,
@ -59,6 +62,8 @@ flags:
=item B<X509_CHECK_FLAG_MULTI_LABEL_WILDCARDS>.
=item B<X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS>.
=back
The B<X509_CHECK_FLAG_ALWAYS_CHECK_SUBJECT> flag causes the function
@ -74,10 +79,18 @@ If set, B<X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS> suppresses support
for "*" as wildcard pattern in labels that have a prefix or suffix,
such as: "www*" or "*www"; this only aplies to B<X509_check_host>.
If set, B<X509_CHECK_FLAG_MULTI_LABEL_WILDCARDS>, allows a "*"
that constitutes the complete label of a DNS name (e.g.
"*.example.com") to match more than one label in B<name>;
this only applies to B<X509_check_host>.
If set, B<X509_CHECK_FLAG_MULTI_LABEL_WILDCARDS> allows a "*" that
constitutes the complete label of a DNS name (e.g. "*.example.com")
to match more than one label in B<name>; this flag only applies
to B<X509_check_host>.
If set, B<X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS> restricts B<name>
values which start with ".", that would otherwise match any sub-domain
in the peer certificate, to only match direct child sub-domains.
Thus, for instance, with this flag set a B<name> of ".example.com"
would match a peer certificate with a DNS name of "www.example.com",
but would not match a peer certificate with a DNS name of
"www.sub.example.com"; this flag only applies to B<X509_check_host>.
=head1 RETURN VALUES