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Code Issues Releases Wiki Activity
fb98a436a7
curl/lib/vtls/schannel_verify.c
Patrick Monnerat bbe3aa9f88
vtls: reduce conn->data use 
Closes #6474
2021-01-19 09:14:40 +01:00

700 lines
23 KiB
C
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/***************************************************************************
* _ _ ____ _
* Project ___| | | | _ \| |
* / __| | | | |_) | |
* | (__| |_| | _ <| |___
* \___|\___/|_| \_\_____|
*
* Copyright (C) 2012 - 2016, Marc Hoersken, <info@marc-hoersken.de>
* Copyright (C) 2012, Mark Salisbury, <mark.salisbury@hp.com>
* Copyright (C) 2012 - 2021, Daniel Stenberg, <daniel@haxx.se>, et al.
*
* This software is licensed as described in the file COPYING, which
* you should have received as part of this distribution. The terms
* are also available at https://curl.se/docs/copyright.html.
*
* You may opt to use, copy, modify, merge, publish, distribute and/or sell
* copies of the Software, and permit persons to whom the Software is
* furnished to do so, under the terms of the COPYING file.
*
* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
* KIND, either express or implied.
*
***************************************************************************/
/*
* Source file for Schannel-specific certificate verification. This code should
* only be invoked by code in schannel.c.
*/
#include "curl_setup.h"
#ifdef USE_SCHANNEL
#ifndef USE_WINDOWS_SSPI
# error "Can't compile SCHANNEL support without SSPI."
#endif
#define EXPOSE_SCHANNEL_INTERNAL_STRUCTS
#include "schannel.h"
#ifdef HAS_MANUAL_VERIFY_API
#include "vtls.h"
#include "sendf.h"
#include "strerror.h"
#include "curl_multibyte.h"
#include "curl_printf.h"
#include "hostcheck.h"
#include "version_win32.h"
/* The last #include file should be: */
#include "curl_memory.h"
#include "memdebug.h"
#define BACKEND connssl->backend
#define MAX_CAFILE_SIZE 1048576 /* 1 MiB */
#define BEGIN_CERT "-----BEGIN CERTIFICATE-----"
#define END_CERT "\n-----END CERTIFICATE-----"
struct cert_chain_engine_config_win7 {
DWORD cbSize;
HCERTSTORE hRestrictedRoot;
HCERTSTORE hRestrictedTrust;
HCERTSTORE hRestrictedOther;
DWORD cAdditionalStore;
HCERTSTORE *rghAdditionalStore;
DWORD dwFlags;
DWORD dwUrlRetrievalTimeout;
DWORD MaximumCachedCertificates;
DWORD CycleDetectionModulus;
HCERTSTORE hExclusiveRoot;
HCERTSTORE hExclusiveTrustedPeople;
};
static int is_cr_or_lf(char c)
{
return c == '\r' || c == '\n';
}
static CURLcode add_certs_to_store(HCERTSTORE trust_store,
const char *ca_file,
struct Curl_easy *data)
{
CURLcode result;
HANDLE ca_file_handle = INVALID_HANDLE_VALUE;
LARGE_INTEGER file_size;
char *ca_file_buffer = NULL;
char *current_ca_file_ptr = NULL;
TCHAR *ca_file_tstr = NULL;
size_t ca_file_bufsize = 0;
DWORD total_bytes_read = 0;
bool more_certs = 0;
int num_certs = 0;
size_t END_CERT_LEN;
ca_file_tstr = curlx_convert_UTF8_to_tchar((char *)ca_file);
if(!ca_file_tstr) {
char buffer[STRERROR_LEN];
failf(data,
"schannel: invalid path name for CA file '%s': %s",
ca_file,
Curl_winapi_strerror(GetLastError(), buffer, sizeof(buffer)));
result = CURLE_SSL_CACERT_BADFILE;
goto cleanup;
}
/*
* Read the CA file completely into memory before parsing it. This
* optimizes for the common case where the CA file will be relatively
* small ( < 1 MiB ).
*/
ca_file_handle = CreateFile(ca_file_tstr,
GENERIC_READ,
FILE_SHARE_READ,
NULL,
OPEN_EXISTING,
FILE_ATTRIBUTE_NORMAL,
NULL);
if(ca_file_handle == INVALID_HANDLE_VALUE) {
char buffer[STRERROR_LEN];
failf(data,
"schannel: failed to open CA file '%s': %s",
ca_file,
Curl_winapi_strerror(GetLastError(), buffer, sizeof(buffer)));
result = CURLE_SSL_CACERT_BADFILE;
goto cleanup;
}
if(!GetFileSizeEx(ca_file_handle, &file_size)) {
char buffer[STRERROR_LEN];
failf(data,
"schannel: failed to determine size of CA file '%s': %s",
ca_file,
Curl_winapi_strerror(GetLastError(), buffer, sizeof(buffer)));
result = CURLE_SSL_CACERT_BADFILE;
goto cleanup;
}
if(file_size.QuadPart > MAX_CAFILE_SIZE) {
failf(data,
"schannel: CA file exceeds max size of %u bytes",
MAX_CAFILE_SIZE);
result = CURLE_SSL_CACERT_BADFILE;
goto cleanup;
}
ca_file_bufsize = (size_t)file_size.QuadPart;
ca_file_buffer = (char *)malloc(ca_file_bufsize + 1);
if(!ca_file_buffer) {
result = CURLE_OUT_OF_MEMORY;
goto cleanup;
}
result = CURLE_OK;
while(total_bytes_read < ca_file_bufsize) {
DWORD bytes_to_read = (DWORD)(ca_file_bufsize - total_bytes_read);
DWORD bytes_read = 0;
if(!ReadFile(ca_file_handle, ca_file_buffer + total_bytes_read,
bytes_to_read, &bytes_read, NULL)) {
char buffer[STRERROR_LEN];
failf(data,
"schannel: failed to read from CA file '%s': %s",
ca_file,
Curl_winapi_strerror(GetLastError(), buffer, sizeof(buffer)));
result = CURLE_SSL_CACERT_BADFILE;
goto cleanup;
}
if(bytes_read == 0) {
/* Premature EOF -- adjust the bufsize to the new value */
ca_file_bufsize = total_bytes_read;
}
else {
total_bytes_read += bytes_read;
}
}
/* Null terminate the buffer */
ca_file_buffer[ca_file_bufsize] = '\0';
if(result != CURLE_OK) {
goto cleanup;
}
END_CERT_LEN = strlen(END_CERT);
more_certs = 1;
current_ca_file_ptr = ca_file_buffer;
while(more_certs && *current_ca_file_ptr != '\0') {
char *begin_cert_ptr = strstr(current_ca_file_ptr, BEGIN_CERT);
if(!begin_cert_ptr || !is_cr_or_lf(begin_cert_ptr[strlen(BEGIN_CERT)])) {
more_certs = 0;
}
else {
char *end_cert_ptr = strstr(begin_cert_ptr, END_CERT);
if(!end_cert_ptr) {
failf(data,
"schannel: CA file '%s' is not correctly formatted",
ca_file);
result = CURLE_SSL_CACERT_BADFILE;
more_certs = 0;
}
else {
CERT_BLOB cert_blob;
CERT_CONTEXT *cert_context = NULL;
BOOL add_cert_result = FALSE;
DWORD actual_content_type = 0;
DWORD cert_size = (DWORD)
((end_cert_ptr + END_CERT_LEN) - begin_cert_ptr);
cert_blob.pbData = (BYTE *)begin_cert_ptr;
cert_blob.cbData = cert_size;
if(!CryptQueryObject(CERT_QUERY_OBJECT_BLOB,
&cert_blob,
CERT_QUERY_CONTENT_FLAG_CERT,
CERT_QUERY_FORMAT_FLAG_ALL,
0,
NULL,
&actual_content_type,
NULL,
NULL,
NULL,
(const void **)&cert_context)) {
char buffer[STRERROR_LEN];
failf(data,
"schannel: failed to extract certificate from CA file "
"'%s': %s",
ca_file,
Curl_winapi_strerror(GetLastError(), buffer, sizeof(buffer)));
result = CURLE_SSL_CACERT_BADFILE;
more_certs = 0;
}
else {
current_ca_file_ptr = begin_cert_ptr + cert_size;
/* Sanity check that the cert_context object is the right type */
if(CERT_QUERY_CONTENT_CERT != actual_content_type) {
failf(data,
"schannel: unexpected content type '%d' when extracting "
"certificate from CA file '%s'",
actual_content_type, ca_file);
result = CURLE_SSL_CACERT_BADFILE;
more_certs = 0;
}
else {
add_cert_result =
CertAddCertificateContextToStore(trust_store,
cert_context,
CERT_STORE_ADD_ALWAYS,
NULL);
CertFreeCertificateContext(cert_context);
if(!add_cert_result) {
char buffer[STRERROR_LEN];
failf(data,
"schannel: failed to add certificate from CA file '%s' "
"to certificate store: %s",
ca_file,
Curl_winapi_strerror(GetLastError(), buffer,
sizeof(buffer)));
result = CURLE_SSL_CACERT_BADFILE;
more_certs = 0;
}
else {
num_certs++;
}
}
}
}
}
}
if(result == CURLE_OK) {
if(!num_certs) {
infof(data,
"schannel: did not add any certificates from CA file '%s'\n",
ca_file);
}
else {
infof(data,
"schannel: added %d certificate(s) from CA file '%s'\n",
num_certs, ca_file);
}
}
cleanup:
if(ca_file_handle != INVALID_HANDLE_VALUE) {
CloseHandle(ca_file_handle);
}
Curl_safefree(ca_file_buffer);
curlx_unicodefree(ca_file_tstr);
return result;
}
/*
* Returns the number of characters necessary to populate all the host_names.
* If host_names is not NULL, populate it with all the host names. Each string
* in the host_names is null-terminated and the last string is double
* null-terminated. If no DNS names are found, a single null-terminated empty
* string is returned.
*/
static DWORD cert_get_name_string(struct Curl_easy *data,
CERT_CONTEXT *cert_context,
LPTSTR host_names,
DWORD length)
{
DWORD actual_length = 0;
BOOL compute_content = FALSE;
CERT_INFO *cert_info = NULL;
CERT_EXTENSION *extension = NULL;
CRYPT_DECODE_PARA decode_para = {0, 0, 0};
CERT_ALT_NAME_INFO *alt_name_info = NULL;
DWORD alt_name_info_size = 0;
BOOL ret_val = FALSE;
LPTSTR current_pos = NULL;
DWORD i;
/* CERT_NAME_SEARCH_ALL_NAMES_FLAG is available from Windows 8 onwards. */
if(curlx_verify_windows_version(6, 2, PLATFORM_WINNT,
VERSION_GREATER_THAN_EQUAL)) {
#ifdef CERT_NAME_SEARCH_ALL_NAMES_FLAG
/* CertGetNameString will provide the 8-bit character string without
* any decoding */
DWORD name_flags =
CERT_NAME_DISABLE_IE4_UTF8_FLAG | CERT_NAME_SEARCH_ALL_NAMES_FLAG;
actual_length = CertGetNameString(cert_context,
CERT_NAME_DNS_TYPE,
name_flags,
NULL,
host_names,
length);
return actual_length;
#endif
}
compute_content = host_names != NULL && length != 0;
/* Initialize default return values. */
actual_length = 1;
if(compute_content) {
*host_names = '\0';
}
if(!cert_context) {
failf(data, "schannel: Null certificate context.");
return actual_length;
}
cert_info = cert_context->pCertInfo;
if(!cert_info) {
failf(data, "schannel: Null certificate info.");
return actual_length;
}
extension = CertFindExtension(szOID_SUBJECT_ALT_NAME2,
cert_info->cExtension,
cert_info->rgExtension);
if(!extension) {
failf(data, "schannel: CertFindExtension() returned no extension.");
return actual_length;
}
decode_para.cbSize = sizeof(CRYPT_DECODE_PARA);
ret_val =
CryptDecodeObjectEx(X509_ASN_ENCODING | PKCS_7_ASN_ENCODING,
szOID_SUBJECT_ALT_NAME2,
extension->Value.pbData,
extension->Value.cbData,
CRYPT_DECODE_ALLOC_FLAG | CRYPT_DECODE_NOCOPY_FLAG,
&decode_para,
&alt_name_info,
&alt_name_info_size);
if(!ret_val) {
failf(data,
"schannel: CryptDecodeObjectEx() returned no alternate name "
"information.");
return actual_length;
}
current_pos = host_names;
/* Iterate over the alternate names and populate host_names. */
for(i = 0; i < alt_name_info->cAltEntry; i++) {
const CERT_ALT_NAME_ENTRY *entry = &alt_name_info->rgAltEntry[i];
wchar_t *dns_w = NULL;
size_t current_length = 0;
if(entry->dwAltNameChoice != CERT_ALT_NAME_DNS_NAME) {
continue;
}
if(entry->pwszDNSName == NULL) {
infof(data, "schannel: Empty DNS name.");
continue;
}
current_length = wcslen(entry->pwszDNSName) + 1;
if(!compute_content) {
actual_length += (DWORD)current_length;
continue;
}
/* Sanity check to prevent buffer overrun. */
if((actual_length + current_length) > length) {
failf(data, "schannel: Not enough memory to list all host names.");
break;
}
dns_w = entry->pwszDNSName;
/* pwszDNSName is in ia5 string format and hence doesn't contain any
* non-ascii characters. */
while(*dns_w != '\0') {
*current_pos++ = (char)(*dns_w++);
}
*current_pos++ = '\0';
actual_length += (DWORD)current_length;
}
if(compute_content) {
/* Last string has double null-terminator. */
*current_pos = '\0';
}
return actual_length;
}
static CURLcode verify_host(struct Curl_easy *data,
CERT_CONTEXT *pCertContextServer,
const char * const conn_hostname)
{
CURLcode result = CURLE_PEER_FAILED_VERIFICATION;
TCHAR *cert_hostname_buff = NULL;
size_t cert_hostname_buff_index = 0;
DWORD len = 0;
DWORD actual_len = 0;
/* Determine the size of the string needed for the cert hostname */
len = cert_get_name_string(data, pCertContextServer, NULL, 0);
if(len == 0) {
failf(data,
"schannel: CertGetNameString() returned no "
"certificate name information");
result = CURLE_PEER_FAILED_VERIFICATION;
goto cleanup;
}
/* CertGetNameString guarantees that the returned name will not contain
* embedded null bytes. This appears to be undocumented behavior.
*/
cert_hostname_buff = (LPTSTR)malloc(len * sizeof(TCHAR));
if(!cert_hostname_buff) {
result = CURLE_OUT_OF_MEMORY;
goto cleanup;
}
actual_len = cert_get_name_string(
data, pCertContextServer, (LPTSTR)cert_hostname_buff, len);
/* Sanity check */
if(actual_len != len) {
failf(data,
"schannel: CertGetNameString() returned certificate "
"name information of unexpected size");
result = CURLE_PEER_FAILED_VERIFICATION;
goto cleanup;
}
/* If HAVE_CERT_NAME_SEARCH_ALL_NAMES is available, the output
* will contain all DNS names, where each name is null-terminated
* and the last DNS name is double null-terminated. Due to this
* encoding, use the length of the buffer to iterate over all names.
*/
result = CURLE_PEER_FAILED_VERIFICATION;
while(cert_hostname_buff_index < len &&
cert_hostname_buff[cert_hostname_buff_index] != TEXT('\0') &&
result == CURLE_PEER_FAILED_VERIFICATION) {
char *cert_hostname;
/* Comparing the cert name and the connection hostname encoded as UTF-8
* is acceptable since both values are assumed to use ASCII
* (or some equivalent) encoding
*/
cert_hostname = curlx_convert_tchar_to_UTF8(
&cert_hostname_buff[cert_hostname_buff_index]);
if(!cert_hostname) {
result = CURLE_OUT_OF_MEMORY;
}
else {
int match_result;
match_result = Curl_cert_hostcheck(cert_hostname, conn_hostname);
if(match_result == CURL_HOST_MATCH) {
infof(data,
"schannel: connection hostname (%s) validated "
"against certificate name (%s)\n",
conn_hostname, cert_hostname);
result = CURLE_OK;
}
else {
size_t cert_hostname_len;
infof(data,
"schannel: connection hostname (%s) did not match "
"against certificate name (%s)\n",
conn_hostname, cert_hostname);
cert_hostname_len =
_tcslen(&cert_hostname_buff[cert_hostname_buff_index]);
/* Move on to next cert name */
cert_hostname_buff_index += cert_hostname_len + 1;
result = CURLE_PEER_FAILED_VERIFICATION;
}
curlx_unicodefree(cert_hostname);
}
}
if(result == CURLE_PEER_FAILED_VERIFICATION) {
failf(data,
"schannel: CertGetNameString() failed to match "
"connection hostname (%s) against server certificate names",
conn_hostname);
}
else if(result != CURLE_OK)
failf(data, "schannel: server certificate name verification failed");
cleanup:
Curl_safefree(cert_hostname_buff);
return result;
}
CURLcode Curl_verify_certificate(struct Curl_easy *data,
struct connectdata *conn, int sockindex)
{
SECURITY_STATUS sspi_status;
struct ssl_connect_data *connssl = &conn->ssl[sockindex];
CURLcode result = CURLE_OK;
CERT_CONTEXT *pCertContextServer = NULL;
const CERT_CHAIN_CONTEXT *pChainContext = NULL;
HCERTCHAINENGINE cert_chain_engine = NULL;
HCERTSTORE trust_store = NULL;
#ifndef CURL_DISABLE_PROXY
const char * const conn_hostname = SSL_IS_PROXY() ?
conn->http_proxy.host.name :
conn->host.name;
#else
const char * const conn_hostname = conn->host.name;
#endif
sspi_status =
s_pSecFn->QueryContextAttributes(&BACKEND->ctxt->ctxt_handle,
SECPKG_ATTR_REMOTE_CERT_CONTEXT,
&pCertContextServer);
if((sspi_status != SEC_E_OK) || (pCertContextServer == NULL)) {
char buffer[STRERROR_LEN];
failf(data, "schannel: Failed to read remote certificate context: %s",
Curl_sspi_strerror(sspi_status, buffer, sizeof(buffer)));
result = CURLE_PEER_FAILED_VERIFICATION;
}
if(result == CURLE_OK && SSL_CONN_CONFIG(CAfile) &&
BACKEND->use_manual_cred_validation) {
/*
* Create a chain engine that uses the certificates in the CA file as
* trusted certificates. This is only supported on Windows 7+.
*/
if(curlx_verify_windows_version(6, 1, PLATFORM_WINNT, VERSION_LESS_THAN)) {
failf(data, "schannel: this version of Windows is too old to support "
"certificate verification via CA bundle file.");
result = CURLE_SSL_CACERT_BADFILE;
}
else {
/* Open the certificate store */
trust_store = CertOpenStore(CERT_STORE_PROV_MEMORY,
0,
(HCRYPTPROV)NULL,
CERT_STORE_CREATE_NEW_FLAG,
NULL);
if(!trust_store) {
char buffer[STRERROR_LEN];
failf(data, "schannel: failed to create certificate store: %s",
Curl_winapi_strerror(GetLastError(), buffer, sizeof(buffer)));
result = CURLE_SSL_CACERT_BADFILE;
}
else {
result = add_certs_to_store(trust_store, SSL_CONN_CONFIG(CAfile),
data);
}
}
if(result == CURLE_OK) {
struct cert_chain_engine_config_win7 engine_config;
BOOL create_engine_result;
memset(&engine_config, 0, sizeof(engine_config));
engine_config.cbSize = sizeof(engine_config);
engine_config.hExclusiveRoot = trust_store;
/* CertCreateCertificateChainEngine will check the expected size of the
* CERT_CHAIN_ENGINE_CONFIG structure and fail if the specified size
* does not match the expected size. When this occurs, it indicates that
* CAINFO is not supported on the version of Windows in use.
*/
create_engine_result =
CertCreateCertificateChainEngine(
(CERT_CHAIN_ENGINE_CONFIG *)&engine_config, &cert_chain_engine);
if(!create_engine_result) {
char buffer[STRERROR_LEN];
failf(data,
"schannel: failed to create certificate chain engine: %s",
Curl_winapi_strerror(GetLastError(), buffer, sizeof(buffer)));
result = CURLE_SSL_CACERT_BADFILE;
}
}
}
if(result == CURLE_OK) {
CERT_CHAIN_PARA ChainPara;
memset(&ChainPara, 0, sizeof(ChainPara));
ChainPara.cbSize = sizeof(ChainPara);
if(!CertGetCertificateChain(cert_chain_engine,
pCertContextServer,
NULL,
pCertContextServer->hCertStore,
&ChainPara,
(data->set.ssl.no_revoke ? 0 :
CERT_CHAIN_REVOCATION_CHECK_CHAIN),
NULL,
&pChainContext)) {
char buffer[STRERROR_LEN];
failf(data, "schannel: CertGetCertificateChain failed: %s",
Curl_winapi_strerror(GetLastError(), buffer, sizeof(buffer)));
pChainContext = NULL;
result = CURLE_PEER_FAILED_VERIFICATION;
}
if(result == CURLE_OK) {
CERT_SIMPLE_CHAIN *pSimpleChain = pChainContext->rgpChain[0];
DWORD dwTrustErrorMask = ~(DWORD)(CERT_TRUST_IS_NOT_TIME_NESTED);
dwTrustErrorMask &= pSimpleChain->TrustStatus.dwErrorStatus;
if(data->set.ssl.revoke_best_effort) {
/* Ignore errors when root certificates are missing the revocation
* list URL, or when the list could not be downloaded because the
* server is currently unreachable. */
dwTrustErrorMask &= ~(DWORD)(CERT_TRUST_REVOCATION_STATUS_UNKNOWN |
CERT_TRUST_IS_OFFLINE_REVOCATION);
}
if(dwTrustErrorMask) {
if(dwTrustErrorMask & CERT_TRUST_IS_REVOKED)
failf(data, "schannel: CertGetCertificateChain trust error"
" CERT_TRUST_IS_REVOKED");
else if(dwTrustErrorMask & CERT_TRUST_IS_PARTIAL_CHAIN)
failf(data, "schannel: CertGetCertificateChain trust error"
" CERT_TRUST_IS_PARTIAL_CHAIN");
else if(dwTrustErrorMask & CERT_TRUST_IS_UNTRUSTED_ROOT)
failf(data, "schannel: CertGetCertificateChain trust error"
" CERT_TRUST_IS_UNTRUSTED_ROOT");
else if(dwTrustErrorMask & CERT_TRUST_IS_NOT_TIME_VALID)
failf(data, "schannel: CertGetCertificateChain trust error"
" CERT_TRUST_IS_NOT_TIME_VALID");
else if(dwTrustErrorMask & CERT_TRUST_REVOCATION_STATUS_UNKNOWN)
failf(data, "schannel: CertGetCertificateChain trust error"
" CERT_TRUST_REVOCATION_STATUS_UNKNOWN");
else
failf(data, "schannel: CertGetCertificateChain error mask: 0x%08x",
dwTrustErrorMask);
result = CURLE_PEER_FAILED_VERIFICATION;
}
}
}
if(result == CURLE_OK) {
if(SSL_CONN_CONFIG(verifyhost)) {
result = verify_host(data, pCertContextServer, conn_hostname);
}
}
if(cert_chain_engine) {
CertFreeCertificateChainEngine(cert_chain_engine);
}
if(trust_store) {
CertCloseStore(trust_store, 0);
}
if(pChainContext)
CertFreeCertificateChain(pChainContext);
if(pCertContextServer)
CertFreeCertificateContext(pCertContextServer);
return result;
}
#endif /* HAS_MANUAL_VERIFY_API */
#endif /* USE_SCHANNEL */
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