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crypt32: Implement name constraint checking.

This commit is contained in:
Juan Lang 2007-10-11 10:59:46 -07:00 committed by Alexandre Julliard
parent c57a084882
commit 9908fe9ac6
2 changed files with 265 additions and 3 deletions
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265
dlls/crypt32/chain.c
View File

@ -22,6 +22,7 @@
#include "winbase.h"
#include "wincrypt.h"
#include "wine/debug.h"
#include "wine/unicode.h"
#include "crypt32_private.h"
WINE_DEFAULT_DEBUG_CHANNEL(crypt);
@ -460,6 +461,267 @@ static BOOL CRYPT_CheckBasicConstraintsForCA(PCCERT_CONTEXT cert,
return validBasicConstraints;
}
static BOOL url_matches(LPCWSTR constraint, LPCWSTR name,
DWORD *trustErrorStatus)
{
BOOL match = FALSE;
TRACE("%s, %s\n", debugstr_w(constraint), debugstr_w(name));
if (!constraint)
*trustErrorStatus |= CERT_TRUST_INVALID_NAME_CONSTRAINTS;
else if (!name)
; /* no match */
else if (constraint[0] == '.')
{
if (lstrlenW(name) > lstrlenW(constraint))
match = !lstrcmpiW(name + lstrlenW(name) - lstrlenW(constraint),
constraint);
}
else
match = !lstrcmpiW(constraint, name);
return match;
}
static BOOL rfc822_name_matches(LPCWSTR constraint, LPCWSTR name,
DWORD *trustErrorStatus)
{
BOOL match = FALSE;
LPCWSTR at;
TRACE("%s, %s\n", debugstr_w(constraint), debugstr_w(name));
if (!constraint)
*trustErrorStatus |= CERT_TRUST_INVALID_NAME_CONSTRAINTS;
else if (!name)
; /* no match */
else if ((at = strchrW(constraint, '@')))
match = !lstrcmpiW(constraint, name);
else
{
if ((at = strchrW(name, '@')))
match = url_matches(constraint, at + 1, trustErrorStatus);
else
match = !lstrcmpiW(constraint, name);
}
return match;
}
static BOOL dns_name_matches(LPCWSTR constraint, LPCWSTR name,
DWORD *trustErrorStatus)
{
BOOL match = FALSE;
TRACE("%s, %s\n", debugstr_w(constraint), debugstr_w(name));
if (!constraint)
*trustErrorStatus |= CERT_TRUST_INVALID_NAME_CONSTRAINTS;
else if (!name)
; /* no match */
else if (lstrlenW(name) >= lstrlenW(constraint))
match = !lstrcmpiW(name + lstrlenW(name) - lstrlenW(constraint),
constraint);
else
; /* name is too short, no match */
return match;
}
static BOOL ip_address_matches(const CRYPT_DATA_BLOB *constraint,
const CRYPT_DATA_BLOB *name, DWORD *trustErrorStatus)
{
BOOL match = FALSE;
TRACE("(%d, %p), (%d, %p)\n", constraint->cbData, constraint->pbData,
name->cbData, name->pbData);
if (constraint->cbData != sizeof(DWORD) * 2)
*trustErrorStatus |= CERT_TRUST_INVALID_NAME_CONSTRAINTS;
else if (name->cbData == sizeof(DWORD))
{
DWORD subnet, mask, addr;
memcpy(&subnet, constraint->pbData, sizeof(subnet));
memcpy(&mask, constraint->pbData + sizeof(subnet), sizeof(mask));
memcpy(&addr, name->pbData, sizeof(addr));
/* These are really in big-endian order, but for equality matching we
* don't need to swap to host order
*/
match = (subnet & mask) == (addr & mask);
}
else
; /* name is wrong size, no match */
return match;
}
static void CRYPT_FindMatchingNameEntry(const CERT_ALT_NAME_ENTRY *constraint,
const CERT_ALT_NAME_INFO *subjectName, DWORD *trustErrorStatus,
DWORD errorIfFound, DWORD errorIfNotFound)
{
DWORD i;
BOOL defined = FALSE, match = FALSE;
for (i = 0; i < subjectName->cAltEntry; i++)
{
if (subjectName->rgAltEntry[i].dwAltNameChoice ==
constraint->dwAltNameChoice)
{
defined = TRUE;
switch (constraint->dwAltNameChoice)
{
case CERT_ALT_NAME_RFC822_NAME:
match = rfc822_name_matches(constraint->u.pwszURL,
subjectName->rgAltEntry[i].u.pwszURL, trustErrorStatus);
break;
case CERT_ALT_NAME_DNS_NAME:
match = dns_name_matches(constraint->u.pwszURL,
subjectName->rgAltEntry[i].u.pwszURL, trustErrorStatus);
break;
case CERT_ALT_NAME_URL:
match = url_matches(constraint->u.pwszURL,
subjectName->rgAltEntry[i].u.pwszURL, trustErrorStatus);
break;
case CERT_ALT_NAME_IP_ADDRESS:
match = ip_address_matches(&constraint->u.IPAddress,
&subjectName->rgAltEntry[i].u.IPAddress, trustErrorStatus);
break;
case CERT_ALT_NAME_DIRECTORY_NAME:
default:
ERR("name choice %d unsupported in this context\n",
constraint->dwAltNameChoice);
*trustErrorStatus |=
CERT_TRUST_HAS_NOT_SUPPORTED_NAME_CONSTRAINT;
}
}
}
/* Microsoft's implementation of name constraint checking appears at odds
* with RFC 3280:
* According to MSDN, CERT_TRUST_HAS_NOT_DEFINED_NAME_CONSTRAINT is set
* when a name constraint is present, but that name form is not defined in
* the end certificate. According to RFC 3280, "if no name of the type is
* in the certificate, the name is acceptable."
* I follow Microsoft here.
*/
if (!defined)
*trustErrorStatus |= CERT_TRUST_HAS_NOT_DEFINED_NAME_CONSTRAINT;
*trustErrorStatus |= match ? errorIfFound : errorIfNotFound;
}
static void CRYPT_CheckNameConstraints(
const CERT_NAME_CONSTRAINTS_INFO *nameConstraints, const CERT_INFO *cert,
DWORD *trustErrorStatus)
{
/* If there aren't any existing constraints, don't bother checking */
if (nameConstraints->cPermittedSubtree || nameConstraints->cExcludedSubtree)
{
CERT_EXTENSION *ext;
if ((ext = CertFindExtension(szOID_SUBJECT_ALT_NAME, cert->cExtension,
cert->rgExtension)))
{
CERT_ALT_NAME_INFO *subjectName;
DWORD size;
if (CryptDecodeObjectEx(X509_ASN_ENCODING, X509_ALTERNATE_NAME,
ext->Value.pbData, ext->Value.cbData,
CRYPT_DECODE_ALLOC_FLAG | CRYPT_DECODE_NOCOPY_FLAG, NULL,
&subjectName, &size))
{
DWORD i;
for (i = 0; i < nameConstraints->cExcludedSubtree; i++)
CRYPT_FindMatchingNameEntry(
&nameConstraints->rgExcludedSubtree[i].Base, subjectName,
trustErrorStatus,
CERT_TRUST_HAS_EXCLUDED_NAME_CONSTRAINT, 0);
for (i = 0; i < nameConstraints->cPermittedSubtree; i++)
CRYPT_FindMatchingNameEntry(
&nameConstraints->rgPermittedSubtree[i].Base, subjectName,
trustErrorStatus,
0, CERT_TRUST_HAS_NOT_PERMITTED_NAME_CONSTRAINT);
LocalFree(subjectName);
}
}
else
{
/* See above comment on CERT_TRUST_HAS_NOT_DEFINED_NAME_CONSTRAINT.
* I match Microsoft's implementation here as well.
*/
*trustErrorStatus |= CERT_TRUST_HAS_NOT_DEFINED_NAME_CONSTRAINT;
if (nameConstraints->cPermittedSubtree)
*trustErrorStatus |=
CERT_TRUST_HAS_NOT_PERMITTED_NAME_CONSTRAINT;
if (nameConstraints->cExcludedSubtree)
*trustErrorStatus |=
CERT_TRUST_HAS_EXCLUDED_NAME_CONSTRAINT;
}
}
}
/* Gets cert's name constraints, if any. Free with LocalFree. */
static CERT_NAME_CONSTRAINTS_INFO *CRYPT_GetNameConstraints(CERT_INFO *cert)
{
CERT_NAME_CONSTRAINTS_INFO *info = NULL;
CERT_EXTENSION *ext;
if ((ext = CertFindExtension(szOID_NAME_CONSTRAINTS, cert->cExtension,
cert->rgExtension)))
{
DWORD size;
CryptDecodeObjectEx(X509_ASN_ENCODING, X509_NAME_CONSTRAINTS,
ext->Value.pbData, ext->Value.cbData,
CRYPT_DECODE_ALLOC_FLAG | CRYPT_DECODE_NOCOPY_FLAG, NULL, &info,
&size);
}
return info;
}
static void CRYPT_CheckChainNameConstraints(PCERT_SIMPLE_CHAIN chain)
{
int i, j;
/* Microsoft's implementation appears to violate RFC 3280: according to
* MSDN, the various CERT_TRUST_*_NAME_CONSTRAINT errors are set if a CA's
* name constraint is violated in the end cert. According to RFC 3280,
* the constraints should be checked against every subsequent certificate
* in the chain, not just the end cert.
* Microsoft's implementation also sets the name constraint errors on the
* certs whose constraints were violated, not on the certs that violated
* them.
* In order to be error-compatible with Microsoft's implementation, while
* still adhering to RFC 3280, I use a O(n ^ 2) algorithm to check name
* constraints.
*/
for (i = chain->cElement - 1; i > 0; i--)
{
CERT_NAME_CONSTRAINTS_INFO *nameConstraints;
if ((nameConstraints = CRYPT_GetNameConstraints(
chain->rgpElement[i]->pCertContext->pCertInfo)))
{
for (j = i - 1; j >= 0; j--)
{
DWORD errorStatus = 0;
/* According to RFC 3280, self-signed certs don't have name
* constraints checked unless they're the end cert.
*/
if (j == 0 || !CRYPT_IsCertificateSelfSigned(
chain->rgpElement[j]->pCertContext))
{
CRYPT_CheckNameConstraints(nameConstraints,
chain->rgpElement[i]->pCertContext->pCertInfo,
&errorStatus);
chain->rgpElement[i]->TrustStatus.dwErrorStatus |=
errorStatus;
}
}
LocalFree(nameConstraints);
}
}
}
static void CRYPT_CheckSimpleChain(PCertificateChainEngine engine,
PCERT_SIMPLE_CHAIN chain, LPFILETIME time)
{
@ -502,10 +764,11 @@ static void CRYPT_CheckSimpleChain(PCertificateChainEngine engine,
constraints.dwPathLenConstraint--;
}
}
/* FIXME: check valid usages and name constraints */
/* FIXME: check valid usages */
CRYPT_CombineTrustStatus(&chain->TrustStatus,
&chain->rgpElement[i]->TrustStatus);
}
CRYPT_CheckChainNameConstraints(chain);
if (CRYPT_IsCertificateSelfSigned(rootElement->pCertContext))
{
rootElement->TrustStatus.dwInfoStatus |=

3
dlls/crypt32/tests/chain.c
View File

@ -1488,8 +1488,7 @@ static ChainCheck chainCheck[] = {
{ { 0, CERT_TRUST_HAS_PREFERRED_ISSUER },
{ CERT_TRUST_HAS_NOT_DEFINED_NAME_CONSTRAINT |
CERT_TRUST_HAS_NOT_PERMITTED_NAME_CONSTRAINT |
CERT_TRUST_IS_UNTRUSTED_ROOT, 0 }, 1, simpleStatus5 },
TODO_ERROR },
CERT_TRUST_IS_UNTRUSTED_ROOT, 0 }, 1, simpleStatus5 }, 0 },
{ { sizeof(chain6) / sizeof(chain6[0]), chain6 },
{ { 0, CERT_TRUST_HAS_PREFERRED_ISSUER },
{ CERT_TRUST_IS_UNTRUSTED_ROOT, 0 }, 1, simpleStatus6 }, 0 },