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Code Issues Releases Wiki Activity
e467ea3bd9
curl/lib/vtls/schannel_verify.c
Jay Satiro 7a33c4dff9 schannel: Evaluate CURLOPT_SSL_OPTIONS via SSL_SET_OPTION macro 
- Change use of those options from CURLOPT_SSL_OPTIONS that are not
  already evaluated via SSL_SET_OPTION in schannel and secure transport
  to use that instead of data->set.ssl.optname.

Example:

Evaluate SSL_SET_OPTION(no_revoke) instead of data->set.ssl.no_revoke.

This change is because options set via CURLOPT_SSL_OPTIONS
(data->set.ssl.optname) are separate from those set for HTTPS proxy via
CURLOPT_PROXY_SSL_OPTIONS (data->set.proxy_ssl.optname). The
SSL_SET_OPTION macro determines whether the connection is for HTTPS
proxy and based on that which option to evaluate.

Since neither Schannel nor Secure Transport backends currently support
HTTPS proxy in libcurl, this change is for posterity and has no other
effect.

Closes https://github.com/curl/curl/pull/6690
2021-03-06 02:01:35 -05:00

700 lines
23 KiB
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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,
(SSL_SET_OPTION(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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