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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#include <stdio.h>
#include <stdlib.h>
#include <windows.h>
#include <softpub.h>
#include <wintrust.h>
#include "certificatecheck.h"
#include "updatecommon.h"
static const int ENCODING = X509_ASN_ENCODING | PKCS_7_ASN_ENCODING;
/**
* Checks to see if a file stored at filePath matches the specified info.
*
* @param filePath The PE file path to check
* @param infoToMatch The acceptable information to match
* @return ERROR_SUCCESS if successful, ERROR_NOT_FOUND if the info
* does not match, or the last error otherwise.
*/
DWORD
CheckCertificateForPEFile(LPCWSTR filePath, CertificateCheckInfo& infoToMatch) {
HCERTSTORE certStore = nullptr;
HCRYPTMSG cryptMsg = nullptr;
PCCERT_CONTEXT certContext = nullptr;
PCMSG_SIGNER_INFO signerInfo = nullptr;
DWORD lastError = ERROR_SUCCESS;
// Get the HCERTSTORE and HCRYPTMSG from the signed file.
DWORD encoding, contentType, formatType;
BOOL result = CryptQueryObject(
CERT_QUERY_OBJECT_FILE, filePath,
CERT_QUERY_CONTENT_FLAG_PKCS7_SIGNED_EMBED, CERT_QUERY_CONTENT_FLAG_ALL,
0, &encoding, &contentType, &formatType, &certStore, &cryptMsg, nullptr);
if (!result) {
lastError = GetLastError();
LOG_WARN(("CryptQueryObject failed. (%lu)", lastError));
goto cleanup;
}
// Pass in nullptr to get the needed signer information size.
DWORD signerInfoSize;
result = CryptMsgGetParam(cryptMsg, CMSG_SIGNER_INFO_PARAM, 0, nullptr,
&signerInfoSize);
if (!result) {
lastError = GetLastError();
LOG_WARN(("CryptMsgGetParam failed. (%lu)", lastError));
goto cleanup;
}
// Allocate the needed size for the signer information.
signerInfo = (PCMSG_SIGNER_INFO)LocalAlloc(LPTR, signerInfoSize);
if (!signerInfo) {
lastError = GetLastError();
LOG_WARN(("Unable to allocate memory for Signer Info. (%lu)", lastError));
goto cleanup;
}
// Get the signer information (PCMSG_SIGNER_INFO).
// In particular we want the issuer and serial number.
result = CryptMsgGetParam(cryptMsg, CMSG_SIGNER_INFO_PARAM, 0,
(PVOID)signerInfo, &signerInfoSize);
if (!result) {
lastError = GetLastError();
LOG_WARN(("CryptMsgGetParam failed. (%lu)", lastError));
goto cleanup;
}
// Search for the signer certificate in the certificate store.
CERT_INFO certInfo;
certInfo.Issuer = signerInfo->Issuer;
certInfo.SerialNumber = signerInfo->SerialNumber;
certContext =
CertFindCertificateInStore(certStore, ENCODING, 0, CERT_FIND_SUBJECT_CERT,
(PVOID)&certInfo, nullptr);
if (!certContext) {
lastError = GetLastError();
LOG_WARN(("CertFindCertificateInStore failed. (%lu)", lastError));
goto cleanup;
}
if (!DoCertificateAttributesMatch(certContext, infoToMatch)) {
lastError = ERROR_NOT_FOUND;
LOG_WARN(("Certificate did not match issuer or name. (%lu)", lastError));
goto cleanup;
}
cleanup:
if (signerInfo) {
LocalFree(signerInfo);
}
if (certContext) {
CertFreeCertificateContext(certContext);
}
if (certStore) {
CertCloseStore(certStore, 0);
}
if (cryptMsg) {
CryptMsgClose(cryptMsg);
}
return lastError;
}
/**
* Checks to see if a file stored at filePath matches the specified info.
*
* @param certContext The certificate context of the file
* @param infoToMatch The acceptable information to match
* @return FALSE if the info does not match or if any error occurs in the check
*/
BOOL DoCertificateAttributesMatch(PCCERT_CONTEXT certContext,
CertificateCheckInfo& infoToMatch) {
DWORD dwData;
LPWSTR szName = nullptr;
if (infoToMatch.issuer) {
// Pass in nullptr to get the needed size of the issuer buffer.
dwData = CertGetNameString(certContext, CERT_NAME_SIMPLE_DISPLAY_TYPE,
CERT_NAME_ISSUER_FLAG, nullptr, nullptr, 0);
if (!dwData) {
LOG_WARN(("CertGetNameString failed. (%lu)", GetLastError()));
return FALSE;
}
// Allocate memory for Issuer name buffer.
szName = (LPWSTR)LocalAlloc(LPTR, dwData * sizeof(WCHAR));
if (!szName) {
LOG_WARN(("Unable to allocate memory for issuer name. (%lu)",
GetLastError()));
return FALSE;
}
// Get Issuer name.
if (!CertGetNameStringW(certContext, CERT_NAME_SIMPLE_DISPLAY_TYPE,
CERT_NAME_ISSUER_FLAG, nullptr, szName, dwData)) {
LOG_WARN(("CertGetNameString failed. (%lu)", GetLastError()));
LocalFree(szName);
return FALSE;
}
// If the issuer does not match, return a failure.
if (!infoToMatch.issuer || wcscmp(szName, infoToMatch.issuer)) {
LocalFree(szName);
return FALSE;
}
LocalFree(szName);
szName = nullptr;
}
if (infoToMatch.name) {
// Pass in nullptr to get the needed size of the name buffer.
dwData = CertGetNameString(certContext, CERT_NAME_SIMPLE_DISPLAY_TYPE, 0,
nullptr, nullptr, 0);
if (!dwData) {
LOG_WARN(("CertGetNameString failed. (%lu)", GetLastError()));
return FALSE;
}
// Allocate memory for the name buffer.
szName = (LPWSTR)LocalAlloc(LPTR, dwData * sizeof(WCHAR));
if (!szName) {
LOG_WARN(("Unable to allocate memory for subject name. (%lu)",
GetLastError()));
return FALSE;
}
// Obtain the name.
if (!(CertGetNameStringW(certContext, CERT_NAME_SIMPLE_DISPLAY_TYPE, 0,
nullptr, szName, dwData))) {
LOG_WARN(("CertGetNameString failed. (%lu)", GetLastError()));
LocalFree(szName);
return FALSE;
}
// If the issuer does not match, return a failure.
if (!infoToMatch.name || wcscmp(szName, infoToMatch.name)) {
LocalFree(szName);
return FALSE;
}
// We have a match!
LocalFree(szName);
}
// If there were any errors we would have aborted by now.
return TRUE;
}
/**
* Verifies the trust of the specified file path.
*
* @param filePath The file path to check.
* @return ERROR_SUCCESS if successful, or the last error code otherwise.
*/
DWORD
VerifyCertificateTrustForFile(LPCWSTR filePath) {
// Setup the file to check.
WINTRUST_FILE_INFO fileToCheck;
ZeroMemory(&fileToCheck, sizeof(fileToCheck));
fileToCheck.cbStruct = sizeof(WINTRUST_FILE_INFO);
fileToCheck.pcwszFilePath = filePath;
// Setup what to check, we want to check it is signed and trusted.
WINTRUST_DATA trustData;
ZeroMemory(&trustData, sizeof(trustData));
trustData.cbStruct = sizeof(trustData);
trustData.pPolicyCallbackData = nullptr;
trustData.pSIPClientData = nullptr;
trustData.dwUIChoice = WTD_UI_NONE;
trustData.fdwRevocationChecks = WTD_REVOKE_NONE;
trustData.dwUnionChoice = WTD_CHOICE_FILE;
trustData.dwStateAction = 0;
trustData.hWVTStateData = nullptr;
trustData.pwszURLReference = nullptr;
// no UI
trustData.dwUIContext = 0;
trustData.pFile = &fileToCheck;
GUID policyGUID = WINTRUST_ACTION_GENERIC_VERIFY_V2;
// Check if the file is signed by something that is trusted.
LONG ret = WinVerifyTrust(nullptr, &policyGUID, &trustData);
if (ERROR_SUCCESS == ret) {
// The hash that represents the subject is trusted and there were no
// verification errors. No publisher nor time stamp chain errors.
LOG(("The file \"%ls\" is signed and the signature was verified.",
filePath));
return ERROR_SUCCESS;
}
DWORD lastError = GetLastError();
LOG_WARN(
("There was an error validating trust of the certificate for file"
" \"%ls\". Returned: %ld. (%lu)",
filePath, ret, lastError));
return ret;
}
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