Set the "Subject Alt Name" extension to when generating certificates
[privoxy.git] / ssl.c
diff --git a/ssl.c b/ssl.c
index a49dbf3..4d94b2e 100644 (file)
--- a/ssl.c
+++ b/ssl.c
@@ -41,6 +41,8 @@
 #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"
@@ -1344,6 +1346,112 @@ static int get_certificate_valid_to_date(char *buffer, size_t 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
@@ -1383,7 +1491,59 @@ static int generate_webpage_certificate(struct client_state *csp)
    cert_opt.issuer_key  = NULL;
    cert_opt.subject_key = NULL;
    cert_opt.issuer_crt  = NULL;
-   cert_opt.output_file = 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
@@ -1391,6 +1551,8 @@ static int generate_webpage_certificate(struct client_state *csp)
    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;
    }
@@ -1421,14 +1583,17 @@ static int generate_webpage_certificate(struct client_state *csp)
     * We must compute length of serial number in string + terminating null.
     */
    unsigned long certificate_serial = get_certificate_serial(csp);
-   int serial_num_size = snprintf(NULL, 0, "%lu", certificate_serial) + 1;
+   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", certificate_serial);
+   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,
@@ -1450,16 +1615,6 @@ static int generate_webpage_certificate(struct client_state *csp)
 
    cert_opt.issuer_crt = csp->config->ca_cert_file;
    cert_opt.issuer_key = csp->config->ca_key_file;
-   cert_opt.subject_key = make_certs_path(csp->config->certificate_directory,
-      (const char *)csp->http->hash_of_host_hex, KEY_FILE_TYPE);
-   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.subject_key == NULL || cert_opt.output_file == NULL)
-   {
-      ret = -1;
-      goto exit;
-   }
 
    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)))
@@ -1479,29 +1634,14 @@ static int generate_webpage_certificate(struct client_state *csp)
    cert_opt.max_pathlen   = -1;
 
    /*
-    * Test if certificate exists and private key was already created
+    * Test if the private key was already created.
+    * XXX: Can this still happen?
     */
-   if (file_exists(cert_opt.output_file) == 1 && subject_key_len == 0)
+   if (subject_key_len == 0)
    {
-      /* 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.",
-            cert_opt.output_file);
-         if (unlink(cert_opt.output_file))
-         {
-            log_error(LOG_LEVEL_ERROR, "Failed to unlink %s: %E",
-               cert_opt.output_file);
-            ret = -1;
-            goto exit;
-         }
-      }
-      else
-      {
-         ret = 0;
-         goto exit;
-      }
+      log_error(LOG_LEVEL_ERROR, "Subject key was already created");
+      ret = 0;
+      goto exit;
    }
 
    /*
@@ -1687,6 +1827,13 @@ static int generate_webpage_certificate(struct client_state *csp)
    }
 #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
     */
@@ -1815,15 +1962,6 @@ static unsigned long get_certificate_serial(struct client_state *csp)
    unsigned long serial = 0;
 
    int i = CERT_SERIAL_NUM_LENGTH;
-   /* Length of hash is 16 bytes, we must avoid to read next chars */
-   if (i > 16)
-   {
-      i = 16;
-   }
-   if (i < 2)
-   {
-      i = 2;
-   }
 
    for (; i >= 0; i--)
    {