/*********************************************************************
*
* File : $Source: /cvsroot/ijbswa/current/ssl.c,v $
*
* Purpose : File with TLS/SSL extension. Contains methods for
* creating, using and closing TLS/SSL connections.
*
* Copyright : Written by and Copyright (c) 2017 Vaclav Svec. FIT CVUT.
* Copyright (C) 2018-2020 by Fabian Keil
*
* This program is free software; you can redistribute it
* and/or modify it under the terms of the GNU General
* Public License as published by the Free Software
* Foundation; either version 2 of the License, or (at
* your option) any later version.
*
* This program is distributed in the hope that it will
* be useful, but WITHOUT ANY WARRANTY; without even the
* implied warranty of MERCHANTABILITY or FITNESS FOR A
* PARTICULAR PURPOSE. See the GNU General Public
* License for more details.
*
* The GNU General Public License should be included with
* this file. If not, you can view it at
* http://www.gnu.org/copyleft/gpl.html
* or write to the Free Software Foundation, Inc., 59
* Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*
*********************************************************************/
#include
#include
#if !defined(MBEDTLS_CONFIG_FILE)
# include "mbedtls/config.h"
#else
# include MBEDTLS_CONFIG_FILE
#endif
#include "mbedtls/md5.h"
#include "mbedtls/pem.h"
#include "mbedtls/base64.h"
#include "mbedtls/error.h"
#include "mbedtls/oid.h"
#include "mbedtls/asn1write.h"
#include "config.h"
#include "project.h"
#include "miscutil.h"
#include "errlog.h"
#include "jcc.h"
#include "ssl.h"
#include "encode.h"
/*
* Macros for searching begin and end of certificates.
* Necessary to convert structure mbedtls_x509_crt to crt file.
*/
#define PEM_BEGIN_CRT "-----BEGIN CERTIFICATE-----\n"
#define PEM_END_CRT "-----END CERTIFICATE-----\n"
/*
* Macros for ssl.c
*/
#define ERROR_BUF_SIZE 1024 /* Size of buffer for error messages */
#define CERTIFICATE_BUF_SIZE 16384 /* Size of buffer to save certificate. Value 4096 is mbedtls library buffer size for certificate in DER form */
#define PRIVATE_KEY_BUF_SIZE 16000 /* Size of buffer to save private key. Value 16000 is taken from mbed TLS library examples. */
#define RSA_KEY_PUBLIC_EXPONENT 65537 /* Public exponent for RSA private key generating */
#define RSA_KEYSIZE 2048 /* Size of generated RSA keys */
#define CERT_SIGNATURE_ALGORITHM MBEDTLS_MD_SHA256 /* The MD algorithm to use for the signature */
#define CERT_SERIAL_NUM_LENGTH 4 /* Bytes of hash to be used for creating serial number of certificate. Min=2 and max=16 */
#define INVALID_CERT_INFO_BUF_SIZE 2048 /* Size of buffer for message with information about reason of certificate invalidity. Data after the end of buffer will not be saved */
#define CERT_PARAM_COMMON_NAME "CN="
#define CERT_PARAM_ORGANIZATION ",O="
#define CERT_PARAM_ORG_UNIT ",OU="
#define CERT_PARAM_COUNTRY ",C=CZ"
#define KEY_FILE_TYPE ".pem"
#define CERT_FILE_TYPE ".crt"
#define CERT_SUBJECT_PASSWORD ""
#define CERT_INFO_PREFIX ""
/*
* Properties of cert for generating
*/
typedef struct {
char *issuer_crt; /* filename of the issuer certificate */
char *subject_key; /* filename of the subject key file */
char *issuer_key; /* filename of the issuer key file */
const char *subject_pwd; /* password for the subject key file */
const char *issuer_pwd; /* password for the issuer key file */
char *output_file; /* where to store the constructed key file */
const char *subject_name; /* subject name for certificate */
char issuer_name[ISSUER_NAME_BUF_SIZE]; /* issuer name for certificate */
const char *not_before; /* validity period not before */
const char *not_after; /* validity period not after */
const char *serial; /* serial number string */
int is_ca; /* is a CA certificate */
int max_pathlen; /* maximum CA path length */
} cert_options;
/*
* Properties of key for generating
*/
typedef struct {
mbedtls_pk_type_t type; /* type of key to generate */
int rsa_keysize; /* length of key in bits */
char *key_file_path; /* filename of the key file */
} key_options;
static int generate_webpage_certificate(struct client_state *csp);
static char *make_certs_path(const char *conf_dir, const char *file_name, const char *suffix);
static int file_exists(const char *path);
static int host_to_hash(struct client_state *csp);
static int ssl_verify_callback(void *data, mbedtls_x509_crt *crt, int depth, uint32_t *flags);
static void free_certificate_chain(struct client_state *csp);
static unsigned long get_certificate_serial(struct client_state *csp);
static void free_client_ssl_structures(struct client_state *csp);
static void free_server_ssl_structures(struct client_state *csp);
static int seed_rng(struct client_state *csp);
/*********************************************************************
*
* Function : client_use_ssl
*
* Description : Tests if client in current client state structure
* should use SSL connection or standard connection.
*
* Parameters :
* 1 : csp = Current client state (buffers, headers, etc...)
*
* Returns : If client should use TLS/SSL connection, 1 is returned.
* Otherwise 0 is returned.
*
*********************************************************************/
extern int client_use_ssl(const struct client_state *csp)
{
return csp->http->client_ssl;
}
/*********************************************************************
*
* Function : server_use_ssl
*
* Description : Tests if server in current client state structure
* should use SSL connection or standard connection.
*
* Parameters :
* 1 : csp = Current client state (buffers, headers, etc...)
*
* Returns : If server should use TLS/SSL connection, 1 is returned.
* Otherwise 0 is returned.
*
*********************************************************************/
extern int server_use_ssl(const struct client_state *csp)
{
return csp->http->server_ssl;
}
/*********************************************************************
*
* Function : is_ssl_pending
*
* Description : Tests if there are some waiting data on ssl connection.
* Only considers data that has actually been received
* locally and ignores data that is still on the fly
* or has not yet been sent by the remote end.
*
* Parameters :
* 1 : ssl = SSL context to test
*
* Returns : 0 => No data are pending
* >0 => Pending data length
*
*********************************************************************/
extern size_t is_ssl_pending(mbedtls_ssl_context *ssl)
{
if (ssl == NULL)
{
return 0;
}
return mbedtls_ssl_get_bytes_avail(ssl);
}
/*********************************************************************
*
* Function : ssl_send_data
*
* Description : Sends the content of buf (for n bytes) to given SSL
* connection context.
*
* Parameters :
* 1 : ssl = SSL context to send data to
* 2 : buf = Pointer to data to be sent
* 3 : len = Length of data to be sent to the SSL context
*
* Returns : Length of sent data or negative value on error.
*
*********************************************************************/
extern int ssl_send_data(mbedtls_ssl_context *ssl, const unsigned char *buf, size_t len)
{
int ret = 0;
size_t max_fragment_size = 0; /* Maximal length of data in one SSL fragment*/
int send_len = 0; /* length of one data part to send */
int pos = 0; /* Position of unsent part in buffer */
if (len == 0)
{
return 0;
}
/* Getting maximal length of data sent in one fragment */
max_fragment_size = mbedtls_ssl_get_max_frag_len(ssl);
/*
* Whole buffer must be sent in many fragments, because each fragment
* has its maximal length.
*/
while (pos < len)
{
/* Compute length of data, that can be send in next fragment */
if ((pos + (int)max_fragment_size) > len)
{
send_len = (int)len - pos;
}
else
{
send_len = (int)max_fragment_size;
}
log_error(LOG_LEVEL_WRITING, "TLS: %N", send_len, buf+pos);
/*
* Sending one part of the buffer
*/
while ((ret = mbedtls_ssl_write(ssl,
(const unsigned char *)(buf + pos),
(size_t)send_len)) < 0)
{
if (ret != MBEDTLS_ERR_SSL_WANT_READ &&
ret != MBEDTLS_ERR_SSL_WANT_WRITE)
{
char err_buf[ERROR_BUF_SIZE];
mbedtls_strerror(ret, err_buf, sizeof(err_buf));
log_error(LOG_LEVEL_ERROR,
"Sending data over TLS/SSL failed: %s", err_buf);
return -1;
}
}
/* Adding count of sent bytes to position in buffer */
pos = pos + send_len;
}
return (int)len;
}
/*********************************************************************
*
* Function : ssl_recv_data
*
* Description : Receives data from given SSL context and puts
* it into buffer.
*
* Parameters :
* 1 : ssl = SSL context to receive data from
* 2 : buf = Pointer to buffer where data will be written
* 3 : max_length = Maximum number of bytes to read
*
* Returns : Number of bytes read, 0 for EOF, or -1
* on error.
*
*********************************************************************/
extern int ssl_recv_data(mbedtls_ssl_context *ssl, unsigned char *buf, size_t max_length)
{
int ret = 0;
memset(buf, 0, max_length);
/*
* Receiving data from SSL context into buffer
*/
do
{
ret = mbedtls_ssl_read(ssl, buf, max_length);
} while (ret == MBEDTLS_ERR_SSL_WANT_READ
|| ret == MBEDTLS_ERR_SSL_WANT_WRITE);
if (ret < 0)
{
char err_buf[ERROR_BUF_SIZE];
if (ret == MBEDTLS_ERR_SSL_PEER_CLOSE_NOTIFY)
{
log_error(LOG_LEVEL_CONNECT,
"The peer notified us that the connection is going to be closed");
return 0;
}
mbedtls_strerror(ret, err_buf, sizeof(err_buf));
log_error(LOG_LEVEL_ERROR,
"Receiving data over TLS/SSL failed: %s", err_buf);
return -1;
}
log_error(LOG_LEVEL_RECEIVED, "TLS: %N", ret, buf);
return ret;
}
/*********************************************************************
*
* Function : ssl_flush_socket
*
* Description : Send any pending "buffered" content with given
* SSL connection. Alternative to function flush_socket.
*
* Parameters :
* 1 : ssl = SSL context to send buffer to
* 2 : iob = The I/O buffer to flush, usually csp->iob.
*
* Returns : On success, the number of bytes send are returned (zero
* indicates nothing was sent). On error, -1 is returned.
*
*********************************************************************/
extern long ssl_flush_socket(mbedtls_ssl_context *ssl, struct iob *iob)
{
/* Computing length of buffer part to send */
long len = iob->eod - iob->cur;
if (len <= 0)
{
return(0);
}
/* Sending data to given SSl context */
if (ssl_send_data(ssl, (const unsigned char *)iob->cur, (size_t)len) < 0)
{
return -1;
}
iob->eod = iob->cur = iob->buf;
return(len);
}
/*********************************************************************
*
* Function : ssl_debug_callback
*
* Description : Debug callback function for mbedtls library.
* Prints info into log file.
*
* Parameters :
* 1 : ctx = File to save log in
* 2 : level = Debug level
* 3 : file = File calling debug message
* 4 : line = Line calling debug message
* 5 : str = Debug message
*
* Returns : N/A
*
*********************************************************************/
static void ssl_debug_callback(void *ctx, int level, const char *file, int line, const char *str)
{
/*
((void)level);
fprintf((FILE *)ctx, "%s:%04d: %s", file, line, str);
fflush((FILE *)ctx);
log_error(LOG_LEVEL_INFO, "SSL debug message: %s:%04d: %s", file, line, str);
*/
}
/*********************************************************************
*
* Function : create_client_ssl_connection
*
* Description : Creates TLS/SSL secured connection with client
*
* Parameters :
* 1 : csp = Current client state (buffers, headers, etc...)
*
* Returns : 0 on success, negative value if connection wasn't created
* successfully.
*
*********************************************************************/
extern int create_client_ssl_connection(struct client_state *csp)
{
/* Paths to certificates file and key file */
char *key_file = NULL;
char *ca_file = NULL;
char *cert_file = NULL;
int ret = 0;
char err_buf[ERROR_BUF_SIZE];
/*
* Initializing mbedtls structures for TLS/SSL connection
*/
mbedtls_net_init(&(csp->mbedtls_client_attr.socket_fd));
mbedtls_ssl_init(&(csp->mbedtls_client_attr.ssl));
mbedtls_ssl_config_init(&(csp->mbedtls_client_attr.conf));
mbedtls_x509_crt_init(&(csp->mbedtls_client_attr.server_cert));
mbedtls_pk_init(&(csp->mbedtls_client_attr.prim_key));
#if defined(MBEDTLS_SSL_CACHE_C)
mbedtls_ssl_cache_init(&(csp->mbedtls_client_attr.cache));
#endif
/*
* Preparing hash of host for creating certificates
*/
ret = host_to_hash(csp);
if (ret != 0)
{
log_error(LOG_LEVEL_ERROR, "Generating hash of host failed: %d", ret);
ret = -1;
goto exit;
}
/*
* Preparing paths to certificates files and key file
*/
ca_file = csp->config->ca_cert_file;
cert_file = make_certs_path(csp->config->certificate_directory,
(const char *)csp->http->hash_of_host_hex, CERT_FILE_TYPE);
key_file = make_certs_path(csp->config->certificate_directory,
(const char *)csp->http->hash_of_host_hex, KEY_FILE_TYPE);
if (cert_file == NULL || key_file == NULL)
{
ret = -1;
goto exit;
}
/*
* Generating certificate for requested host. Mutex to prevent
* certificate and key inconsistence must be locked.
*/
privoxy_mutex_lock(&certificate_mutex);
ret = generate_webpage_certificate(csp);
if (ret < 0)
{
log_error(LOG_LEVEL_ERROR,
"Generate_webpage_certificate failed: %d", ret);
privoxy_mutex_unlock(&certificate_mutex);
ret = -1;
goto exit;
}
privoxy_mutex_unlock(&certificate_mutex);
/*
* Seed the RNG
*/
ret = seed_rng(csp);
if (ret != 0)
{
ret = -1;
goto exit;
}
/*
* Loading CA file, webpage certificate and key files
*/
ret = mbedtls_x509_crt_parse_file(&(csp->mbedtls_client_attr.server_cert),
cert_file);
if (ret != 0)
{
mbedtls_strerror(ret, err_buf, sizeof(err_buf));
log_error(LOG_LEVEL_ERROR,
"Loading webpage certificate %s failed: %s", cert_file, err_buf);
ret = -1;
goto exit;
}
ret = mbedtls_x509_crt_parse_file(&(csp->mbedtls_client_attr.server_cert),
ca_file);
if (ret != 0)
{
mbedtls_strerror(ret, err_buf, sizeof(err_buf));
log_error(LOG_LEVEL_ERROR,
"Loading CA certificate %s failed: %s", ca_file, err_buf);
ret = -1;
goto exit;
}
ret = mbedtls_pk_parse_keyfile(&(csp->mbedtls_client_attr.prim_key),
key_file, NULL);
if (ret != 0)
{
mbedtls_strerror(ret, err_buf, sizeof(err_buf));
log_error(LOG_LEVEL_ERROR,
"Loading and parsing webpage certificate private key %s failed: %s",
key_file, err_buf);
ret = -1;
goto exit;
}
/*
* Setting SSL parameters
*/
ret = mbedtls_ssl_config_defaults(&(csp->mbedtls_client_attr.conf),
MBEDTLS_SSL_IS_SERVER, MBEDTLS_SSL_TRANSPORT_STREAM,
MBEDTLS_SSL_PRESET_DEFAULT);
if (ret != 0)
{
mbedtls_strerror(ret, err_buf, sizeof(err_buf));
log_error(LOG_LEVEL_ERROR,
"mbedtls_ssl_config_defaults failed: %s", err_buf);
ret = -1;
goto exit;
}
mbedtls_ssl_conf_rng(&(csp->mbedtls_client_attr.conf),
mbedtls_ctr_drbg_random, &ctr_drbg);
mbedtls_ssl_conf_dbg(&(csp->mbedtls_client_attr.conf),
ssl_debug_callback, stdout);
#if defined(MBEDTLS_SSL_CACHE_C)
mbedtls_ssl_conf_session_cache(&(csp->mbedtls_client_attr.conf),
&(csp->mbedtls_client_attr.cache), mbedtls_ssl_cache_get,
mbedtls_ssl_cache_set);
#endif
/*
* Setting certificates
*/
ret = mbedtls_ssl_conf_own_cert(&(csp->mbedtls_client_attr.conf),
&(csp->mbedtls_client_attr.server_cert),
&(csp->mbedtls_client_attr.prim_key));
if (ret != 0)
{
mbedtls_strerror(ret, err_buf, sizeof(err_buf));
log_error(LOG_LEVEL_ERROR,
"mbedtls_ssl_conf_own_cert failed: %s", err_buf);
ret = -1;
goto exit;
}
ret = mbedtls_ssl_setup(&(csp->mbedtls_client_attr.ssl),
&(csp->mbedtls_client_attr.conf));
if (ret != 0)
{
mbedtls_strerror(ret, err_buf, sizeof(err_buf));
log_error(LOG_LEVEL_ERROR, "mbedtls_ssl_setup failed: %s", err_buf);
ret = -1;
goto exit;
}
mbedtls_ssl_set_bio(&(csp->mbedtls_client_attr.ssl),
&(csp->mbedtls_client_attr.socket_fd), mbedtls_net_send,
mbedtls_net_recv, NULL);
mbedtls_ssl_session_reset(&(csp->mbedtls_client_attr.ssl));
/*
* Setting socket fd in mbedtls_net_context structure. This structure
* can't be set by mbedtls functions, because we already have created
* a TCP connection when this function is called.
*/
csp->mbedtls_client_attr.socket_fd.fd = csp->cfd;
/*
* Handshake with client
*/
log_error(LOG_LEVEL_CONNECT,
"Performing the TLS/SSL handshake with client. Hash of host: %s",
csp->http->hash_of_host_hex);
while ((ret = mbedtls_ssl_handshake(&(csp->mbedtls_client_attr.ssl))) != 0)
{
if (ret != MBEDTLS_ERR_SSL_WANT_READ &&
ret != MBEDTLS_ERR_SSL_WANT_WRITE)
{
mbedtls_strerror(ret, err_buf, sizeof(err_buf));
log_error(LOG_LEVEL_ERROR,
"medtls_ssl_handshake with client failed: %s", err_buf);
ret = -1;
goto exit;
}
}
log_error(LOG_LEVEL_CONNECT, "Client successfully connected over TLS/SSL");
csp->ssl_with_client_is_opened = 1;
exit:
/*
* Freeing allocated paths to files
*/
freez(cert_file);
freez(key_file);
/* Freeing structures if connection wasn't created successfully */
if (ret < 0)
{
free_client_ssl_structures(csp);
}
return ret;
}
/*********************************************************************
*
* Function : close_client_ssl_connection
*
* Description : Closes TLS/SSL connection with client. This function
* checks if this connection is already created.
*
* Parameters :
* 1 : csp = Current client state (buffers, headers, etc...)
*
* Returns : N/A
*
*********************************************************************/
extern void close_client_ssl_connection(struct client_state *csp)
{
int ret = 0;
if (csp->ssl_with_client_is_opened == 0)
{
return;
}
/*
* Notifying the peer that the connection is being closed.
*/
do {
ret = mbedtls_ssl_close_notify(&(csp->mbedtls_client_attr.ssl));
} while (ret == MBEDTLS_ERR_SSL_WANT_WRITE);
free_client_ssl_structures(csp);
csp->ssl_with_client_is_opened = 0;
}
/*********************************************************************
*
* Function : free_client_ssl_structures
*
* Description : Frees structures used for SSL communication with
* client.
*
* Parameters :
* 1 : csp = Current client state (buffers, headers, etc...)
*
* Returns : N/A
*
*********************************************************************/
static void free_client_ssl_structures(struct client_state *csp)
{
/*
* We can't use function mbedtls_net_free, because this function
* inter alia close TCP connection on set fd. Instead of this
* function, we change fd to -1, which is the same what does
* rest of mbedtls_net_free function.
*/
csp->mbedtls_client_attr.socket_fd.fd = -1;
/* Freeing mbedtls structures */
mbedtls_x509_crt_free(&(csp->mbedtls_client_attr.server_cert));
mbedtls_pk_free(&(csp->mbedtls_client_attr.prim_key));
mbedtls_ssl_free(&(csp->mbedtls_client_attr.ssl));
mbedtls_ssl_config_free(&(csp->mbedtls_client_attr.conf));
#if defined(MBEDTLS_SSL_CACHE_C)
mbedtls_ssl_cache_free(&(csp->mbedtls_client_attr.cache));
#endif
}
/*********************************************************************
*
* Function : create_server_ssl_connection
*
* Description : Creates TLS/SSL secured connection with server.
*
* Parameters :
* 1 : csp = Current client state (buffers, headers, etc...)
*
* Returns : 0 on success, negative value if connection wasn't created
* successfully.
*
*********************************************************************/
extern int create_server_ssl_connection(struct client_state *csp)
{
int ret = 0;
char err_buf[ERROR_BUF_SIZE];
char *trusted_cas_file = NULL;
int auth_mode = MBEDTLS_SSL_VERIFY_REQUIRED;
csp->server_cert_verification_result = SSL_CERT_NOT_VERIFIED;
csp->server_certs_chain.next = NULL;
/* Setting path to file with trusted CAs */
trusted_cas_file = csp->config->trusted_cas_file;
/*
* Initializing mbedtls structures for TLS/SSL connection
*/
mbedtls_net_init(&(csp->mbedtls_server_attr.socket_fd));
mbedtls_ssl_init(&(csp->mbedtls_server_attr.ssl));
mbedtls_ssl_config_init(&(csp->mbedtls_server_attr.conf));
mbedtls_x509_crt_init(&(csp->mbedtls_server_attr.ca_cert));
/*
* Setting socket fd in mbedtls_net_context structure. This structure
* can't be set by mbedtls functions, because we already have created
* TCP connection when calling this function.
*/
csp->mbedtls_server_attr.socket_fd.fd = csp->server_connection.sfd;
/*
* Seed the RNG
*/
ret = seed_rng(csp);
if (ret != 0)
{
ret = -1;
goto exit;
}
/*
* Loading file with trusted CAs
*/
ret = mbedtls_x509_crt_parse_file(&(csp->mbedtls_server_attr.ca_cert),
trusted_cas_file);
if (ret < 0)
{
mbedtls_strerror(ret, err_buf, sizeof(err_buf));
log_error(LOG_LEVEL_ERROR, "Loading trusted CAs file %s failed: %s",
trusted_cas_file, err_buf);
ret = -1;
goto exit;
}
/*
* Set TLS/SSL options
*/
ret = mbedtls_ssl_config_defaults(&(csp->mbedtls_server_attr.conf),
MBEDTLS_SSL_IS_CLIENT,
MBEDTLS_SSL_TRANSPORT_STREAM,
MBEDTLS_SSL_PRESET_DEFAULT);
if (ret != 0)
{
mbedtls_strerror(ret, err_buf, sizeof(err_buf));
log_error(LOG_LEVEL_ERROR, "mbedtls_ssl_config_defaults failed: %s",
err_buf);
ret = -1;
goto exit;
}
/*
* Setting how strict should certificate verification be and other
* parameters for certificate verification
*/
if (csp->dont_verify_certificate)
{
auth_mode = MBEDTLS_SSL_VERIFY_NONE;
}
mbedtls_ssl_conf_authmode(&(csp->mbedtls_server_attr.conf), auth_mode);
mbedtls_ssl_conf_ca_chain(&(csp->mbedtls_server_attr.conf),
&(csp->mbedtls_server_attr.ca_cert), NULL);
/* Setting callback function for certificates verification */
mbedtls_ssl_conf_verify(&(csp->mbedtls_server_attr.conf),
ssl_verify_callback, (void *)csp);
mbedtls_ssl_conf_rng(&(csp->mbedtls_server_attr.conf),
mbedtls_ctr_drbg_random, &ctr_drbg);
mbedtls_ssl_conf_dbg(&(csp->mbedtls_server_attr.conf),
ssl_debug_callback, stdout);
ret = mbedtls_ssl_setup(&(csp->mbedtls_server_attr.ssl),
&(csp->mbedtls_server_attr.conf));
if (ret != 0)
{
mbedtls_strerror(ret, err_buf, sizeof(err_buf));
log_error(LOG_LEVEL_ERROR, "mbedtls_ssl_setup failed: %s", err_buf);
ret = -1;
goto exit;
}
/*
* Set the hostname to check against the received server certificate
*/
ret = mbedtls_ssl_set_hostname(&(csp->mbedtls_server_attr.ssl),
csp->http->host);
if (ret != 0)
{
mbedtls_strerror(ret, err_buf, sizeof(err_buf));
log_error(LOG_LEVEL_ERROR, "mbedtls_ssl_set_hostname failed: %s",
err_buf);
ret = -1;
goto exit;
}
mbedtls_ssl_set_bio(&(csp->mbedtls_server_attr.ssl),
&(csp->mbedtls_server_attr.socket_fd), mbedtls_net_send,
mbedtls_net_recv, NULL);
/*
* Handshake with server
*/
log_error(LOG_LEVEL_CONNECT,
"Performing the TLS/SSL handshake with the server");
while ((ret = mbedtls_ssl_handshake(&(csp->mbedtls_server_attr.ssl))) != 0)
{
if (ret != MBEDTLS_ERR_SSL_WANT_READ
&& ret != MBEDTLS_ERR_SSL_WANT_WRITE)
{
mbedtls_strerror(ret, err_buf, sizeof(err_buf));
if (ret == MBEDTLS_ERR_X509_CERT_VERIFY_FAILED)
{
char reason[INVALID_CERT_INFO_BUF_SIZE];
csp->server_cert_verification_result =
mbedtls_ssl_get_verify_result(&(csp->mbedtls_server_attr.ssl));
mbedtls_x509_crt_verify_info(reason, sizeof(reason), "",
csp->server_cert_verification_result);
/* Log the reason without the trailing new line */
log_error(LOG_LEVEL_ERROR,
"X509 certificate verification for %s failed: %N",
csp->http->hostport, strlen(reason)-1, reason);
ret = -1;
}
else
{
log_error(LOG_LEVEL_ERROR,
"mbedtls_ssl_handshake with server failed: %s", err_buf);
free_certificate_chain(csp);
ret = -1;
}
goto exit;
}
}
log_error(LOG_LEVEL_CONNECT, "Server successfully connected over TLS/SSL");
/*
* Server certificate chain is valid, so we can clean
* chain, because we will not send it to client.
*/
free_certificate_chain(csp);
csp->ssl_with_server_is_opened = 1;
csp->server_cert_verification_result =
mbedtls_ssl_get_verify_result(&(csp->mbedtls_server_attr.ssl));
exit:
/* Freeing structures if connection wasn't created successfully */
if (ret < 0)
{
free_server_ssl_structures(csp);
}
return ret;
}
/*********************************************************************
*
* Function : close_server_ssl_connection
*
* Description : Closes TLS/SSL connection with server. This function
* checks if this connection is already opened.
*
* Parameters :
* 1 : csp = Current client state (buffers, headers, etc...)
*
* Returns : N/A
*
*********************************************************************/
static void close_server_ssl_connection(struct client_state *csp)
{
int ret = 0;
if (csp->ssl_with_server_is_opened == 0)
{
return;
}
/*
* Notifying the peer that the connection is being closed.
*/
do {
ret = mbedtls_ssl_close_notify(&(csp->mbedtls_server_attr.ssl));
} while (ret == MBEDTLS_ERR_SSL_WANT_WRITE);
free_server_ssl_structures(csp);
csp->ssl_with_server_is_opened = 0;
}
/*********************************************************************
*
* Function : free_server_ssl_structures
*
* Description : Frees structures used for SSL communication with server
*
* Parameters :
* 1 : csp = Current client state (buffers, headers, etc...)
*
* Returns : N/A
*
*********************************************************************/
static void free_server_ssl_structures(struct client_state *csp)
{
/*
* We can't use function mbedtls_net_free, because this function
* inter alia close TCP connection on set fd. Instead of this
* function, we change fd to -1, which is the same what does
* rest of mbedtls_net_free function.
*/
csp->mbedtls_server_attr.socket_fd.fd = -1;
mbedtls_x509_crt_free(&(csp->mbedtls_server_attr.ca_cert));
mbedtls_ssl_free(&(csp->mbedtls_server_attr.ssl));
mbedtls_ssl_config_free(&(csp->mbedtls_server_attr.conf));
}
/*********************************************************************
*
* Function : close_client_and_server_ssl_connections
*
* Description : Checks if client or server should use secured
* connection over SSL and if so, closes all of them.
*
* Parameters :
* 1 : csp = Current client state (buffers, headers, etc...)
*
* Returns : N/A
*
*********************************************************************/
extern void close_client_and_server_ssl_connections(struct client_state *csp)
{
if (client_use_ssl(csp) == 1)
{
close_client_ssl_connection(csp);
}
if (server_use_ssl(csp) == 1)
{
close_server_ssl_connection(csp);
}
}
/*====================== Certificates ======================*/
/*********************************************************************
*
* Function : write_certificate
*
* Description : Writes certificate into file.
*
* Parameters :
* 1 : crt = certificate to write into file
* 2 : output_file = path to save certificate file
* 3 : f_rng = mbedtls_ctr_drbg_random
* 4 : p_rng = mbedtls_ctr_drbg_context
*
* Returns : Length of written certificate on success or negative value
* on error
*
*********************************************************************/
static int write_certificate(mbedtls_x509write_cert *crt, const char *output_file,
int(*f_rng)(void *, unsigned char *, size_t), void *p_rng)
{
FILE *f = NULL;
size_t len = 0;
unsigned char cert_buf[CERTIFICATE_BUF_SIZE + 1]; /* Buffer for certificate in PEM format + terminating NULL */
int ret = 0;
char err_buf[ERROR_BUF_SIZE];
memset(cert_buf, 0, sizeof(cert_buf));
/*
* Writing certificate into PEM string. If buffer is too small, function
* returns specific error and no buffer overflow can happen.
*/
if ((ret = mbedtls_x509write_crt_pem(crt, cert_buf,
sizeof(cert_buf) - 1, f_rng, p_rng)) != 0)
{
mbedtls_strerror(ret, err_buf, sizeof(err_buf));
log_error(LOG_LEVEL_ERROR,
"Writing certificate into buffer failed: %s", err_buf);
return -1;
}
len = strlen((char *)cert_buf);
/*
* Saving certificate into file
*/
if ((f = fopen(output_file, "w")) == NULL)
{
log_error(LOG_LEVEL_ERROR, "Opening file %s to save certificate failed",
output_file);
return -1;
}
if (fwrite(cert_buf, 1, len, f) != len)
{
log_error(LOG_LEVEL_ERROR,
"Writing certificate into file %s failed", output_file);
fclose(f);
return -1;
}
fclose(f);
return (int)len;
}
/*********************************************************************
*
* Function : write_private_key
*
* Description : Writes private key into file and copies saved
* content into given pointer to string. If function
* returns 0 for success, this copy must be freed by
* caller.
*
* Parameters :
* 1 : key = key to write into file
* 2 : ret_buf = pointer to string with created key file content
* 3 : key_file_path = path where to save key file
*
* Returns : Length of written private key on success or negative value
* on error
*
*********************************************************************/
static int write_private_key(mbedtls_pk_context *key, unsigned char **ret_buf,
const char *key_file_path)
{
size_t len = 0; /* Length of created key */
FILE *f = NULL; /* File to save certificate */
int ret = 0;
char err_buf[ERROR_BUF_SIZE];
/* Initializing buffer for key file content */
*ret_buf = zalloc_or_die(PRIVATE_KEY_BUF_SIZE + 1);
/*
* Writing private key into PEM string
*/
if ((ret = mbedtls_pk_write_key_pem(key, *ret_buf, PRIVATE_KEY_BUF_SIZE)) != 0)
{
mbedtls_strerror(ret, err_buf, sizeof(err_buf));
log_error(LOG_LEVEL_ERROR,
"Writing private key into PEM string failed: %s", err_buf);
ret = -1;
goto exit;
}
len = strlen((char *)*ret_buf);
/*
* Saving key into file
*/
if ((f = fopen(key_file_path, "wb")) == NULL)
{
log_error(LOG_LEVEL_ERROR,
"Opening file %s to save private key failed: %E",
key_file_path);
ret = -1;
goto exit;
}
if (fwrite(*ret_buf, 1, len, f) != len)
{
fclose(f);
log_error(LOG_LEVEL_ERROR,
"Writing private key into file %s failed",
key_file_path);
ret = -1;
goto exit;
}
fclose(f);
exit:
if (ret < 0)
{
freez(*ret_buf);
*ret_buf = NULL;
return ret;
}
return (int)len;
}
/*********************************************************************
*
* Function : generate_key
*
* Description : Tests if private key for host saved in csp already
* exists. If this file doesn't exists, a new key is
* generated and saved in a file. The generated key is also
* copied into given parameter key_buf, which must be then
* freed by caller. If file with key exists, key_buf
* contain NULL and no private key is generated.
*
* Parameters :
* 1 : csp = Current client state (buffers, headers, etc...)
* 2 : key_buf = buffer to save new generated key
*
* Returns : -1 => Error while generating private key
* 0 => Key already exists
* >0 => Length of generated private key
*
*********************************************************************/
static int generate_key(struct client_state *csp, unsigned char **key_buf)
{
mbedtls_pk_context key;
key_options key_opt;
int ret = 0;
char err_buf[ERROR_BUF_SIZE];
key_opt.key_file_path = NULL;
/*
* Initializing structures for key generating
*/
mbedtls_pk_init(&key);
/*
* Preparing path for key file and other properties for generating key
*/
key_opt.type = MBEDTLS_PK_RSA;
key_opt.rsa_keysize = RSA_KEYSIZE;
key_opt.key_file_path = make_certs_path(csp->config->certificate_directory,
(char *)csp->http->hash_of_host_hex, KEY_FILE_TYPE);
if (key_opt.key_file_path == NULL)
{
ret = -1;
goto exit;
}
/*
* Test if key already exists. If so, we don't have to create it again.
*/
if (file_exists(key_opt.key_file_path) == 1)
{
ret = 0;
goto exit;
}
/*
* Seed the RNG
*/
ret = seed_rng(csp);
if (ret != 0)
{
ret = -1;
goto exit;
}
/*
* Setting attributes of private key and generating it
*/
if ((ret = mbedtls_pk_setup(&key,
mbedtls_pk_info_from_type(key_opt.type))) != 0)
{
mbedtls_strerror(ret, err_buf, sizeof(err_buf));
log_error(LOG_LEVEL_ERROR, "mbedtls_pk_setup failed: %s", err_buf);
ret = -1;
goto exit;
}
ret = mbedtls_rsa_gen_key(mbedtls_pk_rsa(key), mbedtls_ctr_drbg_random,
&ctr_drbg, (unsigned)key_opt.rsa_keysize, RSA_KEY_PUBLIC_EXPONENT);
if (ret != 0)
{
mbedtls_strerror(ret, err_buf, sizeof(err_buf));
log_error(LOG_LEVEL_ERROR, "Key generating failed: %s", err_buf);
ret = -1;
goto exit;
}
/*
* Exporting private key into file
*/
if ((ret = write_private_key(&key, key_buf, key_opt.key_file_path)) < 0)
{
log_error(LOG_LEVEL_ERROR,
"Writing private key into file %s failed", key_opt.key_file_path);
ret = -1;
goto exit;
}
exit:
/*
* Freeing used variables
*/
freez(key_opt.key_file_path);
mbedtls_pk_free(&key);
return ret;
}
/*********************************************************************
*
* Function : ssl_certificate_is_invalid
*
* Description : Checks whether or not a certificate is valid.
* Currently only checks that the certificate can be
* parsed and that the "valid to" date is in the future.
*
* Parameters :
* 1 : cert_file = The certificate to check
*
* Returns : 0 => The certificate is valid.
* 1 => The certificate is invalid
*
*********************************************************************/
static int ssl_certificate_is_invalid(const char *cert_file)
{
mbedtls_x509_crt cert;
int ret;
mbedtls_x509_crt_init(&cert);
ret = mbedtls_x509_crt_parse_file(&cert, cert_file);
if (ret != 0)
{
char err_buf[ERROR_BUF_SIZE];
mbedtls_strerror(ret, err_buf, sizeof(err_buf));
log_error(LOG_LEVEL_ERROR,
"Loading certificate %s to check validity failed: %s",
cert_file, err_buf);
mbedtls_x509_crt_free(&cert);
return 1;
}
if (mbedtls_x509_time_is_past(&cert.valid_to))
{
mbedtls_x509_crt_free(&cert);
return 1;
}
mbedtls_x509_crt_free(&cert);
return 0;
}
/*********************************************************************
*
* Function : generate_certificate_valid_date
*
* Description : Turns a time_t into the format expected by mbedTLS.
*
* Parameters :
* 1 : time_spec = The timestamp to convert
* 2 : buffer = The buffer to write the date to
* 3 : buffer_size = The size of the buffer
*
* Returns : 0 => The conversion worked
* 1 => The conversion failed
*
*********************************************************************/
static int generate_certificate_valid_date(time_t time_spec, char *buffer,
size_t buffer_size)
{
struct tm valid_date;
size_t ret;
#ifndef HAVE_GMTIME_R
#error HTTP inspection currently requires gmtime_r() which seems to be missing
#endif
if (NULL == gmtime_r(&time_spec, &valid_date))
{
return 1;
}
ret = strftime(buffer, buffer_size, "%Y%m%d%H%M%S", &valid_date);
if (ret != 14)
{
return 1;
}
return 0;
}
/*********************************************************************
*
* Function : get_certificate_valid_from_date
*
* Description : Generates a "valid from" date in the format
* expected by mbedTLS.
*
* Parameters :
* 1 : buffer = The buffer to write the date to
* 2 : buffer_size = The size of the buffer
*
* Returns : 0 => The generation worked
* 1 => The generation failed
*
*********************************************************************/
static int get_certificate_valid_from_date(char *buffer, size_t buffer_size)
{
time_t time_spec;
time_spec = time(NULL);
/* 1 month in the past */
time_spec -= 30 * 24 * 60 * 60;
return generate_certificate_valid_date(time_spec, buffer, buffer_size);
}
/*********************************************************************
*
* Function : get_certificate_valid_to_date
*
* Description : Generates a "valid to" date in the format
* expected by mbedTLS.
*
* Parameters :
* 1 : buffer = The buffer to write the date to
* 2 : buffer_size = The size of the buffer
*
* Returns : 0 => The generation worked
* 1 => The generation failed
*
*********************************************************************/
static int get_certificate_valid_to_date(char *buffer, size_t buffer_size)
{
time_t time_spec;
time_spec = time(NULL);
/* Three months in the future */
time_spec += 90 * 24 * 60 * 60;
return generate_certificate_valid_date(time_spec, buffer, buffer_size);
}
/*********************************************************************
*
* Function : set_subject_alternative_name
*
* Description : Sets the Subject Alternative Name extension to a cert
*
* Parameters :
* 1 : cert = The certificate to modify
* 2 : hostname = The hostname to add
*
* Returns : <0 => Error while creating certificate.
* 0 => It worked
*
*********************************************************************/
static int set_subject_alternative_name(mbedtls_x509write_cert *cert, const char *hostname)
{
char err_buf[ERROR_BUF_SIZE];
int ret;
char *subject_alternative_name;
size_t subject_alternative_name_len;
#define MBEDTLS_SUBJECT_ALTERNATIVE_NAME_MAX_LEN 255
unsigned char san_buf[MBEDTLS_SUBJECT_ALTERNATIVE_NAME_MAX_LEN + 1];
unsigned char *c;
int len;
subject_alternative_name_len = strlen(hostname) + 1;
subject_alternative_name = zalloc_or_die(subject_alternative_name_len);
strlcpy(subject_alternative_name, hostname, subject_alternative_name_len);
memset(san_buf, 0, sizeof(san_buf));
c = san_buf + sizeof(san_buf);
len = 0;
ret = mbedtls_asn1_write_raw_buffer(&c, san_buf,
(const unsigned char *)subject_alternative_name,
strlen(subject_alternative_name));
if (ret < 0)
{
mbedtls_strerror(ret, err_buf, sizeof(err_buf));
log_error(LOG_LEVEL_ERROR,
"mbedtls_asn1_write_raw_buffer() failed: %s", err_buf);
goto exit;
}
len += ret;
ret = mbedtls_asn1_write_len(&c, san_buf, strlen(subject_alternative_name));
if (ret < 0)
{
mbedtls_strerror(ret, err_buf, sizeof(err_buf));
log_error(LOG_LEVEL_ERROR,
"mbedtls_asn1_write_len() failed: %s", err_buf);
goto exit;
}
len += ret;
ret = mbedtls_asn1_write_tag(&c, san_buf, MBEDTLS_ASN1_CONTEXT_SPECIFIC | 2);
if (ret < 0)
{
mbedtls_strerror(ret, err_buf, sizeof(err_buf));
log_error(LOG_LEVEL_ERROR,
"mbedtls_asn1_write_tag() failed: %s", err_buf);
goto exit;
}
len += ret;
ret = mbedtls_asn1_write_len(&c, san_buf, (size_t)len);
if (ret < 0)
{
mbedtls_strerror(ret, err_buf, sizeof(err_buf));
log_error(LOG_LEVEL_ERROR,
"mbedtls_asn1_write_len() failed: %s", err_buf);
goto exit;
}
len += ret;
ret = mbedtls_asn1_write_tag(&c, san_buf,
MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE);
if (ret < 0)
{
mbedtls_strerror(ret, err_buf, sizeof(err_buf));
log_error(LOG_LEVEL_ERROR,
"mbedtls_asn1_write_tag() failed: %s", err_buf);
goto exit;
}
len += ret;
ret = mbedtls_x509write_crt_set_extension(cert,
MBEDTLS_OID_SUBJECT_ALT_NAME,
MBEDTLS_OID_SIZE(MBEDTLS_OID_SUBJECT_ALT_NAME),
0, san_buf + sizeof(san_buf) - len, (size_t)len);
if (ret < 0)
{
mbedtls_strerror(ret, err_buf, sizeof(err_buf));
log_error(LOG_LEVEL_ERROR,
"mbedtls_x509write_crt_set_extension() failed: %s", err_buf);
}
exit:
freez(subject_alternative_name);
return ret;
}
/*********************************************************************
*
* Function : generate_webpage_certificate
*
* Description : Creates certificate file in presetted directory.
* If certificate already exists, no other certificate
* will be created. Subject of certificate is named
* by csp->http->host from parameter. This function also
* triggers generating of private key for new certificate.
*
* Parameters :
* 1 : csp = Current client state (buffers, headers, etc...)
*
* Returns : -1 => Error while creating certificate.
* 0 => Certificate already exists.
* >0 => Length of created certificate.
*
*********************************************************************/
static int generate_webpage_certificate(struct client_state *csp)
{
mbedtls_x509_crt issuer_cert;
mbedtls_pk_context loaded_issuer_key, loaded_subject_key;
mbedtls_pk_context *issuer_key = &loaded_issuer_key;
mbedtls_pk_context *subject_key = &loaded_subject_key;
mbedtls_x509write_cert cert;
mbedtls_mpi serial;
unsigned char *key_buf = NULL; /* Buffer for created key */
int ret = 0;
char err_buf[ERROR_BUF_SIZE];
cert_options cert_opt;
char cert_valid_from[15];
char cert_valid_to[15];
/* Paths to keys and certificates needed to create certificate */
cert_opt.issuer_key = NULL;
cert_opt.subject_key = NULL;
cert_opt.issuer_crt = NULL;
cert_opt.output_file = make_certs_path(csp->config->certificate_directory,
(const char *)csp->http->hash_of_host_hex, CERT_FILE_TYPE);
if (cert_opt.output_file == NULL)
{
return -1;
}
cert_opt.subject_key = make_certs_path(csp->config->certificate_directory,
(const char *)csp->http->hash_of_host_hex, KEY_FILE_TYPE);
if (cert_opt.subject_key == NULL)
{
freez(cert_opt.output_file);
return -1;
}
if (file_exists(cert_opt.output_file) == 1)
{
/* The file exists, but is it valid? */
if (ssl_certificate_is_invalid(cert_opt.output_file))
{
log_error(LOG_LEVEL_CONNECT,
"Certificate %s is no longer valid. Removing it.",
cert_opt.output_file);
if (unlink(cert_opt.output_file))
{
log_error(LOG_LEVEL_ERROR, "Failed to unlink %s: %E",
cert_opt.output_file);
freez(cert_opt.output_file);
freez(cert_opt.subject_key);
return -1;
}
if (unlink(cert_opt.subject_key))
{
log_error(LOG_LEVEL_ERROR, "Failed to unlink %s: %E",
cert_opt.subject_key);
freez(cert_opt.output_file);
freez(cert_opt.subject_key);
return -1;
}
}
else
{
freez(cert_opt.output_file);
freez(cert_opt.subject_key);
return 0;
}
}
/*
* Create key for requested host
*/
int subject_key_len = generate_key(csp, &key_buf);
if (subject_key_len < 0)
{
freez(cert_opt.output_file);
freez(cert_opt.subject_key);
log_error(LOG_LEVEL_ERROR, "Key generating failed");
return -1;
}
/*
* Initializing structures for certificate generating
*/
mbedtls_x509write_crt_init(&cert);
mbedtls_x509write_crt_set_md_alg(&cert, CERT_SIGNATURE_ALGORITHM);
mbedtls_pk_init(&loaded_issuer_key);
mbedtls_pk_init(&loaded_subject_key);
mbedtls_mpi_init(&serial);
mbedtls_x509_crt_init(&issuer_cert);
/*
* Presetting parameters for certificate. We must compute total length
* of parameters.
*/
size_t cert_params_len = strlen(CERT_PARAM_COMMON_NAME) +
strlen(CERT_PARAM_ORGANIZATION) + strlen(CERT_PARAM_COUNTRY) +
strlen(CERT_PARAM_ORG_UNIT) +
3 * strlen(csp->http->host) + 1;
char cert_params[cert_params_len];
memset(cert_params, 0, cert_params_len);
/*
* Converting unsigned long serial number to char * serial number.
* We must compute length of serial number in string + terminating null.
*/
unsigned long certificate_serial = get_certificate_serial(csp);
unsigned long certificate_serial_time = (unsigned long)time(NULL);
int serial_num_size = snprintf(NULL, 0, "%lu%lu",
certificate_serial_time, certificate_serial) + 1;
if (serial_num_size <= 0)
{
serial_num_size = 1;
}
char serial_num_text[serial_num_size]; /* Buffer for serial number */
ret = snprintf(serial_num_text, (size_t)serial_num_size, "%lu%lu",
certificate_serial_time, certificate_serial);
if (ret < 0 || ret >= serial_num_size)
{
log_error(LOG_LEVEL_ERROR,
"Converting certificate serial number into string failed");
ret = -1;
goto exit;
}
/*
* Preparing parameters for certificate
*/
strlcpy(cert_params, CERT_PARAM_COMMON_NAME, cert_params_len);
strlcat(cert_params, csp->http->host, cert_params_len);
strlcat(cert_params, CERT_PARAM_ORGANIZATION, cert_params_len);
strlcat(cert_params, csp->http->host, cert_params_len);
strlcat(cert_params, CERT_PARAM_ORG_UNIT, cert_params_len);
strlcat(cert_params, csp->http->host, cert_params_len);
strlcat(cert_params, CERT_PARAM_COUNTRY, cert_params_len);
cert_opt.issuer_crt = csp->config->ca_cert_file;
cert_opt.issuer_key = csp->config->ca_key_file;
if (get_certificate_valid_from_date(cert_valid_from, sizeof(cert_valid_from))
|| get_certificate_valid_to_date(cert_valid_to, sizeof(cert_valid_to)))
{
log_error(LOG_LEVEL_ERROR, "Generating one of the validity dates failed");
ret = -1;
goto exit;
}
cert_opt.subject_pwd = CERT_SUBJECT_PASSWORD;
cert_opt.issuer_pwd = csp->config->ca_password;
cert_opt.subject_name = cert_params;
cert_opt.not_before = cert_valid_from;
cert_opt.not_after = cert_valid_to;
cert_opt.serial = serial_num_text;
cert_opt.is_ca = 0;
cert_opt.max_pathlen = -1;
/*
* Test if the private key was already created.
* XXX: Can this still happen?
*/
if (subject_key_len == 0)
{
log_error(LOG_LEVEL_ERROR, "Subject key was already created");
ret = 0;
goto exit;
}
/*
* Seed the PRNG
*/
ret = seed_rng(csp);
if (ret != 0)
{
ret = -1;
goto exit;
}
/*
* Parse serial to MPI
*/
ret = mbedtls_mpi_read_string(&serial, 10, cert_opt.serial);
if (ret != 0)
{
mbedtls_strerror(ret, err_buf, sizeof(err_buf));
log_error(LOG_LEVEL_ERROR,
"mbedtls_mpi_read_string failed: %s", err_buf);
ret = -1;
goto exit;
}
/*
* Loading certificates
*/
ret = mbedtls_x509_crt_parse_file(&issuer_cert, cert_opt.issuer_crt);
if (ret != 0)
{
mbedtls_strerror(ret, err_buf, sizeof(err_buf));
log_error(LOG_LEVEL_ERROR, "Loading issuer certificate %s failed: %s",
cert_opt.issuer_crt, err_buf);
ret = -1;
goto exit;
}
ret = mbedtls_x509_dn_gets(cert_opt.issuer_name,
sizeof(cert_opt.issuer_name), &issuer_cert.subject);
if (ret < 0)
{
mbedtls_strerror(ret, err_buf, sizeof(err_buf));
log_error(LOG_LEVEL_ERROR, "mbedtls_x509_dn_gets failed: %s", err_buf);
ret = -1;
goto exit;
}
/*
* Loading keys from file or from buffer
*/
if (key_buf != NULL && subject_key_len > 0)
{
/* Key was created in this function and is stored in buffer */
ret = mbedtls_pk_parse_key(&loaded_subject_key, key_buf,
(size_t)(subject_key_len + 1), (unsigned const char *)
cert_opt.subject_pwd, strlen(cert_opt.subject_pwd));
}
else
{
/* Key wasn't created in this function, because it already existed */
ret = mbedtls_pk_parse_keyfile(&loaded_subject_key,
cert_opt.subject_key, cert_opt.subject_pwd);
}
if (ret != 0)
{
mbedtls_strerror(ret, err_buf, sizeof(err_buf));
log_error(LOG_LEVEL_ERROR, "Parsing subject key %s failed: %s",
cert_opt.subject_key, err_buf);
ret = -1;
goto exit;
}
ret = mbedtls_pk_parse_keyfile(&loaded_issuer_key, cert_opt.issuer_key,
cert_opt.issuer_pwd);
if (ret != 0)
{
mbedtls_strerror(ret, err_buf, sizeof(err_buf));
log_error(LOG_LEVEL_ERROR,
"Parsing issuer key %s failed: %s", cert_opt.issuer_key, err_buf);
ret = -1;
goto exit;
}
/*
* Check if key and issuer certificate match
*/
if (!mbedtls_pk_can_do(&issuer_cert.pk, MBEDTLS_PK_RSA) ||
mbedtls_mpi_cmp_mpi(&mbedtls_pk_rsa(issuer_cert.pk)->N,
&mbedtls_pk_rsa(*issuer_key)->N) != 0 ||
mbedtls_mpi_cmp_mpi(&mbedtls_pk_rsa(issuer_cert.pk)->E,
&mbedtls_pk_rsa(*issuer_key)->E) != 0)
{
log_error(LOG_LEVEL_ERROR,
"Issuer key doesn't match issuer certificate");
ret = -1;
goto exit;
}
mbedtls_x509write_crt_set_subject_key(&cert, subject_key);
mbedtls_x509write_crt_set_issuer_key(&cert, issuer_key);
/*
* Setting parameters of signed certificate
*/
ret = mbedtls_x509write_crt_set_subject_name(&cert, cert_opt.subject_name);
if (ret != 0)
{
mbedtls_strerror(ret, err_buf, sizeof(err_buf));
log_error(LOG_LEVEL_ERROR,
"Setting subject name in signed certificate failed: %s", err_buf);
ret = -1;
goto exit;
}
ret = mbedtls_x509write_crt_set_issuer_name(&cert, cert_opt.issuer_name);
if (ret != 0)
{
mbedtls_strerror(ret, err_buf, sizeof(err_buf));
log_error(LOG_LEVEL_ERROR,
"Setting issuer name in signed certificate failed: %s", err_buf);
ret = -1;
goto exit;
}
ret = mbedtls_x509write_crt_set_serial(&cert, &serial);
if (ret != 0)
{
mbedtls_strerror(ret, err_buf, sizeof(err_buf));
log_error(LOG_LEVEL_ERROR,
"Setting serial number in signed certificate failed: %s", err_buf);
ret = -1;
goto exit;
}
ret = mbedtls_x509write_crt_set_validity(&cert, cert_opt.not_before,
cert_opt.not_after);
if (ret != 0)
{
mbedtls_strerror(ret, err_buf, sizeof(err_buf));
log_error(LOG_LEVEL_ERROR,
"Setting validity in signed certificate failed: %s", err_buf);
ret = -1;
goto exit;
}
/*
* Setting the basicConstraints extension for certificate
*/
ret = mbedtls_x509write_crt_set_basic_constraints(&cert, cert_opt.is_ca,
cert_opt.max_pathlen);
if (ret != 0)
{
mbedtls_strerror(ret, err_buf, sizeof(err_buf));
log_error(LOG_LEVEL_ERROR, "Setting the basicConstraints extension "
"in signed certificate failed: %s", err_buf);
ret = -1;
goto exit;
}
#if defined(MBEDTLS_SHA1_C)
/* Setting the subjectKeyIdentifier extension for certificate */
ret = mbedtls_x509write_crt_set_subject_key_identifier(&cert);
if (ret != 0)
{
mbedtls_strerror(ret, err_buf, sizeof(err_buf));
log_error(LOG_LEVEL_ERROR, "mbedtls_x509write_crt_set_subject_key_"
"identifier failed: %s", err_buf);
ret = -1;
goto exit;
}
/* Setting the authorityKeyIdentifier extension for certificate */
ret = mbedtls_x509write_crt_set_authority_key_identifier(&cert);
if (ret != 0)
{
mbedtls_strerror(ret, err_buf, sizeof(err_buf));
log_error(LOG_LEVEL_ERROR, "mbedtls_x509write_crt_set_authority_key_"
"identifier failed: %s", err_buf);
ret = -1;
goto exit;
}
#endif /* MBEDTLS_SHA1_C */
if (set_subject_alternative_name(&cert, csp->http->host))
{
/* Errors are already logged by set_subject_alternative_name() */
ret = -1;
goto exit;
}
/*
* Writing certificate into file
*/
ret = write_certificate(&cert, cert_opt.output_file,
mbedtls_ctr_drbg_random, &ctr_drbg);
if (ret < 0)
{
log_error(LOG_LEVEL_ERROR, "Writing certificate into file failed");
goto exit;
}
exit:
/*
* Freeing used structures
*/
mbedtls_x509write_crt_free(&cert);
mbedtls_pk_free(&loaded_subject_key);
mbedtls_pk_free(&loaded_issuer_key);
mbedtls_mpi_free(&serial);
mbedtls_x509_crt_free(&issuer_cert);
freez(cert_opt.subject_key);
freez(cert_opt.output_file);
freez(key_buf);
return ret;
}
/*********************************************************************
*
* Function : make_certs_path
*
* Description : Creates path to file from three pieces. This function
* takes parameters and puts them in one new mallocated
* char * in correct order. Returned variable must be freed
* by caller. This function is mainly used for creating
* paths of certificates and keys files.
*
* Parameters :
* 1 : conf_dir = Name/path of directory where is the file.
* '.' can be used for current directory.
* 2 : file_name = Name of file in conf_dir without suffix.
* 3 : suffix = Suffix of given file_name.
*
* Returns : path => Path was built up successfully
* NULL => Path can't be built up
*
*********************************************************************/
static char *make_certs_path(const char *conf_dir, const char *file_name,
const char *suffix)
{
/* Test if all given parameters are valid */
if (conf_dir == NULL || *conf_dir == '\0' || file_name == NULL ||
*file_name == '\0' || suffix == NULL || *suffix == '\0')
{
log_error(LOG_LEVEL_ERROR,
"make_certs_path failed: bad input parameters");
return NULL;
}
char *path = NULL;
size_t path_size = strlen(conf_dir)
+ strlen(file_name) + strlen(suffix) + 2;
/* Setting delimiter and editing path length */
#if defined(_WIN32) || defined(__OS2__)
char delim[] = "\\";
path_size += 1;
#else /* ifndef _WIN32 || __OS2__ */
char delim[] = "/";
#endif /* ifndef _WIN32 || __OS2__ */
/*
* Building up path from many parts
*/
#if defined(unix)
if (*conf_dir != '/' && basedir && *basedir)
{
/*
* Replacing conf_dir with basedir. This new variable contains
* absolute path to cwd.
*/
path_size += strlen(basedir) + 2;
path = zalloc_or_die(path_size);
strlcpy(path, basedir, path_size);
strlcat(path, delim, path_size);
strlcat(path, conf_dir, path_size);
strlcat(path, delim, path_size);
strlcat(path, file_name, path_size);
strlcat(path, suffix, path_size);
}
else
#endif /* defined unix */
{
path = zalloc_or_die(path_size);
strlcpy(path, conf_dir, path_size);
strlcat(path, delim, path_size);
strlcat(path, file_name, path_size);
strlcat(path, suffix, path_size);
}
return path;
}
/*********************************************************************
*
* Function : get_certificate_serial
*
* Description : Computes serial number for new certificate from host
* name hash. This hash must be already saved in csp
* structure.
*
* Parameters :
* 1 : csp = Current client state (buffers, headers, etc...)
*
* Returns : Serial number for new certificate
*
*********************************************************************/
static unsigned long get_certificate_serial(struct client_state *csp)
{
unsigned long exp = 1;
unsigned long serial = 0;
int i = CERT_SERIAL_NUM_LENGTH;
for (; i >= 0; i--)
{
serial += exp * (unsigned)csp->http->hash_of_host[i];
exp *= 256;
}
return serial;
}
/*********************************************************************
*
* Function : ssl_send_certificate_error
*
* Description : Sends info about invalid server certificate to client.
* Sent message is including all trusted chain certificates,
* that can be downloaded in web browser.
*
* Parameters :
* 1 : csp = Current client state (buffers, headers, etc...)
*
* Returns : N/A
*
*********************************************************************/
extern void ssl_send_certificate_error(struct client_state *csp)
{
size_t message_len = 0;
int ret = 0;
struct certs_chain *cert = NULL;
/* Header of message with certificate information */
const char message_begin[] =
"HTTP/1.1 200 OK\r\n"
"Content-Type: text/html\r\n"
"Connection: close\r\n\r\n"
"Server certificate verification failed
Reason: ";
const char message_end[] = "\r\n\r\n";
char reason[INVALID_CERT_INFO_BUF_SIZE];
memset(reason, 0, sizeof(reason));
/* Get verification message from verification return code */
mbedtls_x509_crt_verify_info(reason, sizeof(reason), " ",
csp->server_cert_verification_result);
/*
* Computing total length of message with all certificates inside
*/
message_len = strlen(message_begin) + strlen(message_end)
+ strlen(reason) + strlen("
") + 1;
cert = &(csp->server_certs_chain);
while (cert->next != NULL)
{
size_t base64_len = 4 * ((strlen(cert->file_buf) + 2) / 3) + 1;
message_len += strlen(cert->text_buf) + strlen("\n")
+ base64_len + strlen("Download certificate");
cert = cert->next;
}
/*
* Joining all blocks in one long message
*/
char message[message_len];
memset(message, 0, message_len);
strlcpy(message, message_begin, message_len);
strlcat(message, reason , message_len);
strlcat(message, "
" , message_len);
cert = &(csp->server_certs_chain);
while (cert->next != NULL)
{
size_t olen = 0;
size_t base64_len = 4 * ((strlen(cert->file_buf) + 2) / 3) + 1; /* +1 for terminating null*/
char base64_buf[base64_len];
memset(base64_buf, 0, base64_len);
/* Encoding certificate into base64 code */
ret = mbedtls_base64_encode((unsigned char*)base64_buf,
base64_len, &olen, (const unsigned char*)cert->file_buf,
strlen(cert->file_buf));
if (ret != 0)
{
log_error(LOG_LEVEL_ERROR,
"Encoding to base64 failed, buffer is to small");
}
strlcat(message, "", message_len);
strlcat(message, cert->text_buf, message_len);
strlcat(message, "
\n", message_len);
if (ret == 0)
{
strlcat(message, "Download certificate", message_len);
}
cert = cert->next;
}
strlcat(message, message_end, message_len);
/*
* Sending final message to client
*/
ssl_send_data(&(csp->mbedtls_client_attr.ssl),
(const unsigned char *)message, strlen(message));
free_certificate_chain(csp);
}
/*********************************************************************
*
* Function : ssl_verify_callback
*
* Description : This is a callback function for certificate verification.
* It's called once for each certificate in the server's
* certificate trusted chain and prepares information about
* the certificate. The information can be used to inform
* the user about invalid certificates.
*
* Parameters :
* 1 : csp_void = Current client state (buffers, headers, etc...)
* 2 : crt = certificate from trusted chain
* 3 : depth = depth in trusted chain
* 4 : flags = certificate flags
*
* Returns : 0 on success and negative value on error
*
*********************************************************************/
static int ssl_verify_callback(void *csp_void, mbedtls_x509_crt *crt,
int depth, uint32_t *flags)
{
struct client_state *csp = (struct client_state *)csp_void;
struct certs_chain *last = &(csp->server_certs_chain);
size_t olen = 0;
int ret = 0;
/*
* Searching for last item in certificates linked list
*/
while (last->next != NULL)
{
last = last->next;
}
/*
* Preparing next item in linked list for next certificate
*/
last->next = malloc_or_die(sizeof(struct certs_chain));
last->next->next = NULL;
memset(last->next->text_buf, 0, sizeof(last->next->text_buf));
memset(last->next->file_buf, 0, sizeof(last->next->file_buf));
/*
* Saving certificate file into buffer
*/
if ((ret = mbedtls_pem_write_buffer(PEM_BEGIN_CRT, PEM_END_CRT,
crt->raw.p, crt->raw.len, (unsigned char *)last->file_buf,
sizeof(last->file_buf)-1, &olen)) != 0)
{
char err_buf[ERROR_BUF_SIZE];
mbedtls_strerror(ret, err_buf, sizeof(err_buf));
log_error(LOG_LEVEL_ERROR, "mbedtls_pem_write_buffer() failed: %s",
err_buf);
return(ret);
}
/*
* Saving certificate information into buffer
*/
{
char buf[CERT_INFO_BUF_SIZE];
char *encoded_text;
mbedtls_x509_crt_info(buf, sizeof(buf), CERT_INFO_PREFIX, crt);
encoded_text = html_encode(buf);
strlcpy(last->text_buf, encoded_text, sizeof(last->text_buf));
freez(encoded_text);
}
return 0;
}
/*********************************************************************
*
* Function : free_certificate_chain
*
* Description : Frees certificates linked list. This linked list is
* used to save information about certificates in
* trusted chain.
*
* Parameters :
* 1 : csp = Current client state (buffers, headers, etc...)
*
* Returns : N/A
*
*********************************************************************/
static void free_certificate_chain(struct client_state *csp)
{
struct certs_chain *cert = csp->server_certs_chain.next;
/* Cleaning buffers */
memset(csp->server_certs_chain.text_buf, 0,
sizeof(csp->server_certs_chain.text_buf));
memset(csp->server_certs_chain.file_buf, 0,
sizeof(csp->server_certs_chain.file_buf));
csp->server_certs_chain.next = NULL;
/* Freeing memory in whole linked list */
while (cert != NULL)
{
struct certs_chain *cert_for_free = cert;
cert = cert->next;
freez(cert_for_free);
}
}
/*********************************************************************
*
* Function : file_exists
*
* Description : Tests if file exists and is readable.
*
* Parameters :
* 1 : path = Path to tested file.
*
* Returns : 1 => File exists and is readable.
* 0 => File doesn't exist or is not readable.
*
*********************************************************************/
static int file_exists(const char *path)
{
FILE *f;
if ((f = fopen(path, "r")) != NULL)
{
fclose(f);
return 1;
}
return 0;
}
/*********************************************************************
*
* Function : host_to_hash
*
* Description : Creates MD5 hash from host name. Host name is loaded
* from structure csp and saved again into it.
*
* Parameters :
* 1 : csp = Current client state (buffers, headers, etc...)
*
* Returns : 1 => Error while creating hash
* 0 => Hash created successfully
*
*********************************************************************/
static int host_to_hash(struct client_state *csp)
{
int ret = 0;
#if !defined(MBEDTLS_MD5_C)
#error mbedTLS needs to be compiled with md5 support
#else
memset(csp->http->hash_of_host, 0, sizeof(csp->http->hash_of_host));
mbedtls_md5((unsigned char *)csp->http->host, strlen(csp->http->host),
csp->http->hash_of_host);
/* Converting hash into string with hex */
size_t i = 0;
for (; i < 16; i++)
{
if ((ret = sprintf((char *)csp->http->hash_of_host_hex + 2 * i, "%02x",
csp->http->hash_of_host[i])) < 0)
{
log_error(LOG_LEVEL_ERROR, "Sprintf return value: %d", ret);
return -1;
}
}
return 0;
#endif /* MBEDTLS_MD5_C */
}
/*********************************************************************
*
* Function : tunnel_established_successfully
*
* Description : Check if parent proxy server response contains
* information about successfully created connection with
* destination server. (HTTP/... 2xx ...)
*
* Parameters :
* 1 : server_response = Buffer with parent proxy server response
* 2 : response_len = Length of server_response
*
* Returns : 1 => Connection created successfully
* 0 => Connection wasn't created successfully
*
*********************************************************************/
extern int tunnel_established_successfully(const char *server_response,
unsigned int response_len)
{
unsigned int pos = 0;
if (server_response == NULL)
{
return 0;
}
/* Tests if "HTTP/" string is at the begin of received response */
if (strncmp(server_response, "HTTP/", 5) != 0)
{
return 0;
}
for (pos = 0; pos < response_len; pos++)
{
if (server_response[pos] == ' ')
{
break;
}
}
/*
* response_len -3 because of buffer end, response structure and 200 code.
* There must be at least 3 chars after space.
* End of buffer: ... 2xx'\0'
* pos = |
*/
if (pos >= (response_len - 3))
{
return 0;
}
/* Test HTTP status code */
if (server_response[pos + 1] != '2')
{
return 0;
}
return 1;
}
/*********************************************************************
*
* Function : seed_rng
*
* Description : Seeding the RNG for all SSL uses
*
* Parameters :
* 1 : csp = Current client state (buffers, headers, etc...)
*
* Returns : -1 => RNG wasn't seed successfully
* 0 => RNG is seeded successfully
*
*********************************************************************/
static int seed_rng(struct client_state *csp)
{
int ret = 0;
char err_buf[ERROR_BUF_SIZE];
if (rng_seeded == 0)
{
privoxy_mutex_lock(&rng_mutex);
if (rng_seeded == 0)
{
mbedtls_ctr_drbg_init(&ctr_drbg);
mbedtls_entropy_init(&entropy);
ret = mbedtls_ctr_drbg_seed(&ctr_drbg, mbedtls_entropy_func,
&entropy, NULL, 0);
if (ret != 0)
{
mbedtls_strerror(ret, err_buf, sizeof(err_buf));
log_error(LOG_LEVEL_ERROR,
"mbedtls_ctr_drbg_seed failed: %s", err_buf);
privoxy_mutex_unlock(&rng_mutex);
return -1;
}
rng_seeded = 1;
}
privoxy_mutex_unlock(&rng_mutex);
}
return 0;
}