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Code Issues Releases Wiki Activity

SChannel/WinSSL: Fix public key pinning

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This commit is contained in:
Andrey 2017-10-11 12:38:00 +03:00
parent 1d49e25d26
commit a933ac9664
1 changed files with 22 additions and 129 deletions
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149
lib/vtls/schannel.c
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@ -79,22 +79,6 @@
* #define failf(x, y, ...) printf(y, __VA_ARGS__)
*/
/* APIs return rsa keys missing the spki header (not DER) */
static const size_t spkiHeaderLength = 24;
static const unsigned char rsa4096SpkiHeader[] = {
0x30, 0x82, 0x02, 0x22, 0x30, 0x0d,
0x06, 0x09, 0x2a, 0x86, 0x48, 0x86,
0xf7, 0x0d, 0x01, 0x01, 0x01, 0x05,
0x00, 0x03, 0x82, 0x02, 0x0f, 0x00};
static const unsigned char rsa2048SpkiHeader[] = {
0x30, 0x82, 0x01, 0x22, 0x30, 0x0d,
0x06, 0x09, 0x2a, 0x86, 0x48, 0x86,
0xf7, 0x0d, 0x01, 0x01, 0x01, 0x05,
0x00, 0x03, 0x82, 0x01, 0x0f, 0x00};
/* define these here if they aren't already */
#ifndef CALG_SHA_256
# define CALG_SHA_256 0x0000800c
#endif
@ -1617,12 +1601,10 @@ static CURLcode pkp_pin_peer_pubkey(struct connectdata *conn, int sockindex,
struct Curl_easy *data = conn->data;
struct ssl_connect_data *connssl = &conn->ssl[sockindex];
CERT_CONTEXT *pCertContextServer = NULL;
const CERT_CHAIN_CONTEXT *pChainContext = NULL;
HCRYPTPROV hCryptProv = 0;
HCRYPTKEY hCertPubKey = NULL;
size_t bloblen, pubkeylen, realpubkeylen;
unsigned char *blob = NULL, *pubkey = NULL, *realpubkey = NULL,
*spkiHeader = NULL;
const char *x509_der;
int x509_der_len;
curl_X509certificate x509_parsed;
curl_asn1Element *pubkey;
/* Result is returned to caller */
CURLcode result = CURLE_SSL_PINNEDPUBKEYNOTMATCH;
@ -1643,123 +1625,34 @@ static CURLcode pkp_pin_peer_pubkey(struct connectdata *conn, int sockindex,
}
if(!CryptAcquireContext(&hCryptProv, NULL, NULL,
/*PROV_RSA_FULL,*/
PROV_RSA_AES,
CRYPT_VERIFYCONTEXT | CRYPT_SILENT)) {
failf(data, "schannel: Failed to acquire crypto context: %s",
Curl_sspi_strerror(conn, GetLastError()));
break; /* failed */
}
if(!(((pCertContextServer->dwCertEncodingType & X509_ASN_ENCODING) != 0) &&
(pCertContextServer->cbCertEncoded > 0)))
break;
/* Get the public key information for the certificate.
This works for RSA keys, but secp256r1 and secp384r1 gives
this error:
Unknown error (0x8009310B) - ASN1 bad tag value met.
*/
if(!CryptImportPublicKeyInfo(
hCryptProv,
X509_ASN_ENCODING,
&pCertContextServer->pCertInfo->SubjectPublicKeyInfo,
&hCertPubKey)) {
failf(data, "schannel: Failed to import public key info: %s",
Curl_sspi_strerror(conn, GetLastError()));
break; /* failed */
}
x509_der = pCertContextServer->pbCertEncoded;
x509_der_len = pCertContextServer->cbCertEncoded;
memset(&x509_parsed, 0, sizeof x509_parsed);
if(Curl_parseX509(&x509_parsed, x509_der, x509_der + x509_der_len))
break;
/* export to blob */
if(!CryptExportKey(hCertPubKey, 0, PUBLICKEYBLOB, 0, 0, &bloblen)) {
failf(data, "schannel: Failed to get public key blob length: %s",
Curl_sspi_strerror(conn, GetLastError()));
break; /* failed */
}
blob = malloc(bloblen);
if(!blob)
break; /* failed */
if(!CryptExportKey(hCertPubKey, 0, PUBLICKEYBLOB, 0, blob, &bloblen)) {
failf(data, "schannel: Failed to export public key to blob: %s",
Curl_sspi_strerror(conn, GetLastError()));
break; /* failed */
}
/* export to der
not sure what second arg should be,
X509_PUBLIC_KEY_INFO -- fails
RSA_CSP_PUBLICKEYBLOB -- not quite der, missing spki header bytes
CNG_RSA_PUBLIC_KEY_BLOB -- fails
PKCS_CONTENT_INFO -- fails
X509_SEQUENCE_OF_ANY - fails
CRYPT_STRING_BASE64HEADER - fails
*/
if(!CryptEncodeObjectEx(X509_ASN_ENCODING, RSA_CSP_PUBLICKEYBLOB, blob, 0,
NULL, NULL, &pubkeylen)) {
failf(data, "schannel: Failed to get public key der length: %s",
Curl_sspi_strerror(conn, GetLastError()));
pubkey = &x509_parsed.subjectPublicKeyInfo;
if(!pubkey->header || pubkey->end <= pubkey->header) {
failf(data, "SSL: failed retrieving public key from server certificate");
break;
}
pubkey = malloc(pubkeylen);
if(!pubkey)
break;
if(!CryptEncodeObjectEx(X509_ASN_ENCODING, RSA_CSP_PUBLICKEYBLOB, blob, 0,
NULL, pubkey, &pubkeylen)) {
failf(data, "schannel: Failed to export public key to der: %s",
Curl_sspi_strerror(conn, GetLastError()));
break;
result = Curl_pin_peer_pubkey(data,
pinnedpubkey,
(const unsigned char *)pubkey->header,
(size_t)(pubkey->end - pubkey->header));
if(result) {
failf(data, "SSL: public key does not match pinned public key!");
}
FILE *fp;
fp=fopen("windows.key", "wb");
fwrite(pubkey, sizeof(pubkey[0]), pubkeylen, fp);
fclose(fp);
switch(pubkeylen) {
case 526:
/* 4096 bit RSA pubkeylen == 526 */
spkiHeader = rsa4096SpkiHeader;
break;
case 270:
/* 2048 bit RSA pubkeylen == 270 */
spkiHeader = rsa2048SpkiHeader;
break;
default:
infof(data, "SSL: unhandled public key length: %d\n", pubkeylen);
continue; /* break from loop */
}
realpubkeylen = pubkeylen + spkiHeaderLength;
realpubkey = malloc(realpubkeylen);
if(!realpubkey)
break;
memcpy(realpubkey, spkiHeader, spkiHeaderLength);
memcpy(realpubkey + spkiHeaderLength, pubkey, pubkeylen);
fp=fopen("windows.real.key", "wb");
fwrite(realpubkey, sizeof(realpubkey[0]), realpubkeylen, fp);
fclose(fp);
/* The one good exit point */
result = Curl_pin_peer_pubkey(data, pinnedpubkey, realpubkey,
realpubkeylen);
} while(0);
if(pChainContext)
CertFreeCertificateChain(pChainContext);
if(pCertContextServer)
CertFreeCertificateContext(pCertContextServer);
if(hCryptProv != 0)
CryptReleaseContext(hCryptProv, 0UL);
Curl_safefree(blob);
Curl_safefree(pubkey);
Curl_safefree(realpubkey);
return result;
}