Commit 3cc8a3f2 authored by Viktor Dukhovni's avatar Viktor Dukhovni Committed by Dr. Stephen Henson
Browse files

Client-side namecheck wildcards. 

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)
parent 3d860774

crypto/x509v3/v3_utl.c

+53 −6
Original line number Diff line number Diff line
@@ -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;

crypto/x509v3/v3nametest.c

+11 −0
Original line number Diff line number Diff line
@@ -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]",

crypto/x509v3/x509v3.h

+8 −0
Original line number Diff line number Diff line
@@ -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);

doc/crypto/X509_check_host.pod

+18 −5
Original line number Diff line number Diff line
@@ -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