2 // Functions in this module handle SSL encryption when WebCit is running
5 // Copyright (c) 1996-2021 by the citadel.org team
7 // This program is open source software. It runs great on the
8 // Linux operating system (and probably elsewhere). You can use,
9 // copy, and run it under the terms of the GNU General Public
12 // This program is distributed in the hope that it will be useful,
13 // but WITHOUT ANY WARRANTY; without even the implied warranty of
14 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 // GNU General Public License for more details.
19 SSL_CTX *ssl_ctx; // SSL context
20 pthread_mutex_t **SSLCritters; // Things needing locking
21 char *ssl_cipher_list = DEFAULT_SSL_CIPHER_LIST;
22 void ssl_lock(int mode, int n, const char *file, int line);
25 // OpenSSL wants a callback function to identify the currently running thread.
26 // Since we are a pthreads program, we convert the output of pthread_self() to a long.
27 static unsigned long id_callback(void) {
28 return (unsigned long) pthread_self();
32 // OpenSSL wants a callback function to set and clear various types of locks.
33 // Since we are a pthreads program, we use mutexes.
34 void ssl_lock(int mode, int n, const char *file, int line) {
35 if (mode & CRYPTO_LOCK) {
36 pthread_mutex_lock(SSLCritters[n]);
39 pthread_mutex_unlock(SSLCritters[n]);
44 // Generate a private key for SSL
45 void generate_key(char *keyfilename) {
50 unsigned long e = RSA_F4;
53 if (access(keyfilename, R_OK) == 0) {
57 syslog(LOG_INFO, "crypto: generating RSA key pair");
61 ret = BN_set_word(bne, e);
67 ret = RSA_generate_key_ex(rsa, bits, bne, NULL);
72 fp = fopen(keyfilename, "w");
74 chmod(keyfilename, 0600);
75 if (PEM_write_RSAPrivateKey(fp, // the file */
78 NULL, // no passphrase
83 syslog(LOG_ERR, "crypto: cannot write key: %s", ERR_reason_error_string(ERR_get_error()));
95 // Initialize ssl engine, load certs and initialize openssl internals
97 const SSL_METHOD *ssl_method;
102 EVP_PKEY *req_pkey = NULL;
103 X509_NAME *name = NULL;
108 SSLCritters = malloc(CRYPTO_num_locks() * sizeof(pthread_mutex_t *));
110 syslog(LOG_ERR, "citserver: can't allocate memory!!");
115 for (a = 0; a < CRYPTO_num_locks(); a++) {
116 SSLCritters[a] = malloc(sizeof(pthread_mutex_t));
117 if (!SSLCritters[a]) {
118 syslog(LOG_INFO, "citserver: can't allocate memory!!");
121 pthread_mutex_init(SSLCritters[a], NULL);
125 // Initialize SSL transport layer
127 SSL_load_error_strings();
128 ssl_method = SSLv23_server_method();
129 if (!(ssl_ctx = SSL_CTX_new(ssl_method))) {
130 syslog(LOG_WARNING, "SSL_CTX_new failed: %s", ERR_reason_error_string(ERR_get_error()));
134 syslog(LOG_INFO, "Requesting cipher list: %s", ssl_cipher_list);
135 if (!(SSL_CTX_set_cipher_list(ssl_ctx, ssl_cipher_list))) {
136 syslog(LOG_WARNING, "SSL_CTX_set_cipher_list failed: %s", ERR_reason_error_string(ERR_get_error()));
140 CRYPTO_set_locking_callback(ssl_lock);
141 CRYPTO_set_id_callback(id_callback);
143 // Get our certificates in order.
144 // First, create the key/cert directory if it's not there already...
145 mkdir(CTDL_CRYPTO_DIR, 0700);
147 // If we still don't have a private key, generate one.
148 generate_key(CTDL_KEY_PATH);
150 // If there is no certificate file on disk, we will be generating a self-signed certificate
151 // in the next step. Therefore, if we have neither a CSR nor a certificate, generate
152 // the CSR in this step so that the next step may commence.
153 if ((access(CTDL_CER_PATH, R_OK) != 0) && (access(CTDL_CSR_PATH, R_OK) != 0)) {
154 syslog(LOG_INFO, "Generating a certificate signing request.");
156 // Read our key from the file. No, we don't just keep this
157 // in memory from the above key-generation function, because
158 // there is the possibility that the key was already on disk
159 // and we didn't just generate it now.
160 fp = fopen(CTDL_KEY_PATH, "r");
162 rsa = PEM_read_RSAPrivateKey(fp, NULL, NULL, NULL);
167 // Create a public key from the private key
168 if (pk = EVP_PKEY_new(), pk != NULL) {
169 EVP_PKEY_assign_RSA(pk, rsa);
170 if (req = X509_REQ_new(), req != NULL) {
172 // Set the public key
173 X509_REQ_set_pubkey(req, pk);
174 X509_REQ_set_version(req, 0L);
175 name = X509_REQ_get_subject_name(req);
176 X509_NAME_add_entry_by_txt(name, "O", MBSTRING_ASC, (unsigned char *) "Citadel Server", -1, -1, 0);
177 X509_NAME_add_entry_by_txt(name, "OU", MBSTRING_ASC, (unsigned char *) "Default Certificate PLEASE CHANGE", -1, -1, 0);
178 X509_NAME_add_entry_by_txt(name, "CN", MBSTRING_ASC, (unsigned char *) "*", -1, -1, 0);
179 X509_REQ_set_subject_name(req, name);
182 if (!X509_REQ_sign(req, pk, EVP_md5())) {
183 syslog(LOG_WARNING, "X509_REQ_sign(): error");
187 fp = fopen(CTDL_CSR_PATH, "w");
189 chmod(CTDL_CSR_PATH, 0600);
190 PEM_write_X509_REQ(fp, req);
194 syslog(LOG_WARNING, "Cannot write key: %s", CTDL_CSR_PATH);
204 syslog(LOG_WARNING, "Unable to read private key.");
208 // Generate a self-signed certificate if we don't have one.
209 if (access(CTDL_CER_PATH, R_OK) != 0) {
210 syslog(LOG_INFO, "Generating a self-signed certificate.");
212 // Same deal as before: always read the key from disk because
213 // it may or may not have just been generated.
214 fp = fopen(CTDL_KEY_PATH, "r");
216 rsa = PEM_read_RSAPrivateKey(fp, NULL, NULL, NULL);
220 // This also holds true for the CSR
225 if (pk = EVP_PKEY_new(), pk != NULL) {
226 EVP_PKEY_assign_RSA(pk, rsa);
229 fp = fopen(CTDL_CSR_PATH, "r");
231 req = PEM_read_X509_REQ(fp, NULL, NULL, NULL);
236 if (cer = X509_new(), cer != NULL) {
237 ASN1_INTEGER_set(X509_get_serialNumber(cer), 0);
238 X509_set_issuer_name(cer, X509_REQ_get_subject_name(req));
239 X509_set_subject_name(cer, X509_REQ_get_subject_name(req));
240 X509_gmtime_adj(X509_get_notBefore(cer), 0);
241 X509_gmtime_adj(X509_get_notAfter(cer), (long) 60 * 60 * 24 * SIGN_DAYS);
242 req_pkey = X509_REQ_get_pubkey(req);
243 X509_set_pubkey(cer, req_pkey);
244 EVP_PKEY_free(req_pkey);
247 if (!X509_sign(cer, pk, EVP_md5())) {
248 syslog(LOG_WARNING, "X509_sign(): error");
250 else { // Write it to disk
251 fp = fopen(CTDL_CER_PATH, "w");
253 chmod(CTDL_CER_PATH, 0600);
254 PEM_write_X509(fp, cer);
258 syslog(LOG_WARNING, "Cannot write key: %s", CTDL_CER_PATH);
269 // Now try to bind to the key and certificate.
270 // Note that we use SSL_CTX_use_certificate_chain_file() which allows
271 // the certificate file to contain intermediate certificates.
272 SSL_CTX_use_certificate_chain_file(ssl_ctx, CTDL_CER_PATH);
273 SSL_CTX_use_PrivateKey_file(ssl_ctx, CTDL_KEY_PATH, SSL_FILETYPE_PEM);
274 if (!SSL_CTX_check_private_key(ssl_ctx)) {
275 syslog(LOG_WARNING, "Cannot install certificate: %s", ERR_reason_error_string(ERR_get_error()));
281 // starts SSL/TLS encryption for the current session.
282 void starttls(struct client_handle *ch) {
283 int retval, bits, alg_bits;
288 if (!(ch->ssl_handle = SSL_new(ssl_ctx))) {
289 syslog(LOG_WARNING, "SSL_new failed: %s", ERR_reason_error_string(ERR_get_error()));
292 if (!(SSL_set_fd(ch->ssl_handle, ch->sock))) {
293 syslog(LOG_WARNING, "SSL_set_fd failed: %s", ERR_reason_error_string(ERR_get_error()));
294 SSL_free(ch->ssl_handle);
297 retval = SSL_accept(ch->ssl_handle);
300 const char *ssl_error_reason = NULL;
302 errval = SSL_get_error(ch->ssl_handle, retval);
303 ssl_error_reason = ERR_reason_error_string(ERR_get_error());
304 if (ssl_error_reason == NULL) {
305 syslog(LOG_WARNING, "SSL_accept failed: errval=%ld, retval=%d %s", errval, retval, strerror(errval));
308 syslog(LOG_WARNING, "SSL_accept failed: %s\n", ssl_error_reason);
311 retval = SSL_accept(ch->ssl_handle);
315 const char *ssl_error_reason = NULL;
317 errval = SSL_get_error(ch->ssl_handle, retval);
318 ssl_error_reason = ERR_reason_error_string(ERR_get_error());
319 if (ssl_error_reason == NULL) {
320 syslog(LOG_WARNING, "SSL_accept failed: errval=%ld, retval=%d (%s)", errval, retval, strerror(errval));
323 syslog(LOG_WARNING, "SSL_accept failed: %s", ssl_error_reason);
325 SSL_free(ch->ssl_handle);
326 ch->ssl_handle = NULL;
330 syslog(LOG_INFO, "SSL_accept success");
332 bits = SSL_CIPHER_get_bits(SSL_get_current_cipher(ch->ssl_handle), &alg_bits);
333 syslog(LOG_INFO, "SSL/TLS using %s on %s (%d of %d bits)",
334 SSL_CIPHER_get_name(SSL_get_current_cipher(ch->ssl_handle)),
335 SSL_CIPHER_get_version(SSL_get_current_cipher(ch->ssl_handle)), bits, alg_bits);
337 syslog(LOG_INFO, "SSL started");
341 // shuts down the TLS connection
342 void endtls(struct client_handle *ch) {
343 syslog(LOG_INFO, "Ending SSL/TLS");
344 if (ch->ssl_handle != NULL) {
345 SSL_shutdown(ch->ssl_handle);
346 SSL_get_SSL_CTX(ch->ssl_handle);
347 SSL_free(ch->ssl_handle);
349 ch->ssl_handle = NULL;
353 // Send binary data to the client encrypted.
354 int client_write_ssl(struct client_handle *ch, char *buf, int nbytes) {
359 if (ch->ssl_handle == NULL)
363 while (nremain > 0) {
364 if (SSL_want_write(ch->ssl_handle)) {
365 if ((SSL_read(ch->ssl_handle, junk, 0)) < 1) {
366 syslog(LOG_WARNING, "SSL_read in client_write: %s", ERR_reason_error_string(ERR_get_error()));
369 retval = SSL_write(ch->ssl_handle, &buf[nbytes - nremain], nremain);
373 errval = SSL_get_error(ch->ssl_handle, retval);
374 if (errval == SSL_ERROR_WANT_READ || errval == SSL_ERROR_WANT_WRITE) {
378 syslog(LOG_WARNING, "SSL_write got error %ld, ret %d", errval, retval);
380 syslog(LOG_WARNING, "errno is %d", errno);
391 // read data from the encrypted layer
392 int client_read_ssl(struct client_handle *ch, char *buf, int nbytes) {
397 if (ch->ssl_handle == NULL)
400 while (bytes_read < nbytes) {
401 if (SSL_want_read(ch->ssl_handle)) {
402 if ((SSL_write(ch->ssl_handle, junk, 0)) < 1) {
403 syslog(LOG_WARNING, "SSL_write in client_read");
406 rlen = SSL_read(ch->ssl_handle, &buf[bytes_read], nbytes - bytes_read);
409 errval = SSL_get_error(ch->ssl_handle, rlen);
410 if (errval == SSL_ERROR_WANT_READ || errval == SSL_ERROR_WANT_WRITE) {
414 syslog(LOG_WARNING, "SSL_read error %ld", errval);