Detect NULs in common name.

[wget] / src / openssl.c

diff --git a/src/openssl.c b/src/openssl.c
index 21dbc3b845858ae9cf44dfeeac363f92c7247d63..dd3a62a4ee0cf594f97cc35655be548e259dd3c4 100644 (file)
--- a/src/openssl.c
+++ b/src/openssl.c
@@ -210,6 +210,13 @@ ssl_init ()
      than examining the error stack after a failed SSL_connect.  */
   SSL_CTX_set_verify (ssl_ctx, SSL_VERIFY_NONE, NULL);
 
+  /* Use the private key from the cert file unless otherwise specified. */
+  if (opt.cert_file && !opt.private_key)
+    {
+      opt.private_key = opt.cert_file;
+      opt.private_key_type = opt.cert_type;
+    }
+
   if (opt.cert_file)
     if (SSL_CTX_use_certificate_file (ssl_ctx, opt.cert_file,
                                       key_type_to_ssl_type (opt.cert_type))
@@ -495,7 +502,7 @@ ssl_check_certificate (int fd, const char *host)
   if (!cert)
     {
       logprintf (LOG_NOTQUIET, _("%s: No certificate presented by %s.\n"),
-                 severity, escnonprint (host));
+                 severity, quotearg_style (escape_quoting_style, host));
       success = false;
       goto no_cert;             /* must bail out since CERT is NULL */
     }
@@ -505,7 +512,8 @@ ssl_check_certificate (int fd, const char *host)
       char *subject = X509_NAME_oneline (X509_get_subject_name (cert), 0, 0);
       char *issuer = X509_NAME_oneline (X509_get_issuer_name (cert), 0, 0);
       DEBUGP (("certificate:\n  subject: %s\n  issuer:  %s\n",
-               escnonprint (subject), escnonprint (issuer)));
+               quotearg_style (escape_quoting_style, subject), 
+               quotearg_style (escape_quoting_style, issuer)));
       OPENSSL_free (subject);
       OPENSSL_free (issuer);
     }
@@ -515,8 +523,9 @@ ssl_check_certificate (int fd, const char *host)
     {
       char *issuer = X509_NAME_oneline (X509_get_issuer_name (cert), 0, 0);
       logprintf (LOG_NOTQUIET,
-                 _("%s: cannot verify %s's certificate, issued by `%s':\n"),
-                 severity, escnonprint (host), escnonprint (issuer));
+                 _("%s: cannot verify %s's certificate, issued by %s:\n"),
+                 severity, quotearg_style (escape_quoting_style, host), 
+                 quote (issuer));
       /* Try to print more user-friendly (and translated) messages for
          the frequent verification errors.  */
       switch (vresult)
@@ -560,27 +569,53 @@ ssl_check_certificate (int fd, const char *host)
      - Ensure that ASN1 strings from the certificate are encoded as
        UTF-8 which can be meaningfully compared to HOST.  */
 
+  X509_NAME *xname = X509_get_subject_name(cert);
   common_name[0] = '\0';
-  X509_NAME_get_text_by_NID (X509_get_subject_name (cert),
+  X509_NAME_get_text_by_NID (xname,
                              NID_commonName, common_name, sizeof (common_name));
+
+  /* We now determine the length of the ASN1 string. If it differs from
+   * common_name's length, then there is a \0 before the string terminates.
+   * This can be an instance of a null-prefix attack [0].
+   *
+   * [0] https://www.blackhat.com/html/bh-usa-09/bh-usa-09-archives.html#Marlinspike
+   * */
+
+  int i=-1,j;
+  if(xname) {
+         for(;(j=X509_NAME_get_index_by_NID (xname, NID_commonName, i))!=-1;i=j);
+  }
+
+  X509_NAME_ENTRY *xentry = X509_NAME_get_entry(xname,i);
+  ASN1_STRING *sdata = X509_NAME_ENTRY_get_data(xentry);
+
+  if (strlen(common_name) != ASN1_STRING_length(sdata)) 
+    {
+      logprintf (LOG_NOTQUIET, _("\
+%s: certificate common name is invalid. It is possible that someone is \
+eavesdropping on you (man-in-the-middle attack)!\n"),
+                 severity);
+      success = false;
+    }
+
   if (!pattern_match (common_name, host))
     {
       logprintf (LOG_NOTQUIET, _("\
-%s: certificate common name `%s' doesn't match requested host name `%s'.\n"),
-                 severity, escnonprint (common_name), escnonprint (host));
+%s: certificate common name %s doesn't match requested host name %s.\n"),
+                 severity, quote (common_name), quote (host));
       success = false;
     }
 
   if (success)
     DEBUGP (("X509 certificate successfully verified and matches host %s\n",
-             escnonprint (host)));
+             quotearg_style (escape_quoting_style, host)));
   X509_free (cert);
 
  no_cert:
   if (opt.check_cert && !success)
     logprintf (LOG_NOTQUIET, _("\
 To connect to %s insecurely, use `--no-check-certificate'.\n"),
-               escnonprint (host));
+               quotearg_style (escape_quoting_style, host));
 
   /* Allow --no-check-cert to disable certificate checking. */
   return opt.check_cert ? success : true;