ssl: disallow reading/writing to unstarted SSL socket

OpenSSL::SSL::SSLSocket allowed #read and #write to be called before an
SSL/TLS handshake is completed. They passed unencrypted data to the
underlying socket.

This behavior is very odd to have in this library. A verbose mode
warning "SSL session is not started yet" was emitted whenever this
happened. It also didn't behave well with OpenSSL::Buffering. Let's
just get rid of it.

Fixes: ruby#9

Author: rhenium

ext/openssl/ossl_ssl.c

@@ -1697,8 +1697,7 @@ ossl_start_ssl(VALUE self, int (*func)(), const char *funcname, VALUE opts)
  * call-seq:
  *    ssl.connect => self
  *
- * Initiates an SSL/TLS handshake with a server.  The handshake may be started
- * after unencrypted data has been sent over the socket.
+ * Initiates an SSL/TLS handshake with a server.
  */
 static VALUE
 ossl_ssl_connect(VALUE self)
@@ -1745,8 +1744,7 @@ ossl_ssl_connect_nonblock(int argc, VALUE *argv, VALUE self)
  * call-seq:
  *    ssl.accept => self
  *
- * Waits for a SSL/TLS client to initiate a handshake.  The handshake may be
- * started after unencrypted data has been sent over the socket.
+ * Waits for a SSL/TLS client to initiate a handshake.
  */
 static VALUE
 ossl_ssl_accept(VALUE self)
@@ -1793,7 +1791,7 @@ static VALUE
 ossl_ssl_read_internal(int argc, VALUE *argv, VALUE self, int nonblock)
 {
     SSL *ssl;
-    int ilen, nread = 0;
+    int ilen;
     VALUE len, str;
     rb_io_t *fptr;
     VALUE io, opts = Qnil;
@@ -1803,6 +1801,9 @@ ossl_ssl_read_internal(int argc, VALUE *argv, VALUE self, int nonblock)
     } else {
 	rb_scan_args(argc, argv, "11", &len, &str);
     }
+    GetSSL(self, ssl);
+    if (!ssl_started(ssl))
+        rb_raise(eSSLError, "SSL session is not started yet");
 
     ilen = NUM2INT(len);
     if (NIL_P(str))
@@ -1818,85 +1819,60 @@ ossl_ssl_read_internal(int argc, VALUE *argv, VALUE self, int nonblock)
     if (ilen == 0)
 	return str;
 
-    GetSSL(self, ssl);
     io = rb_attr_get(self, id_i_io);
     GetOpenFile(io, fptr);
-    if (ssl_started(ssl)) {
-        rb_str_locktmp(str);
-        for (;;) {
-	    nread = SSL_read(ssl, RSTRING_PTR(str), ilen);
-	    switch(ssl_get_error(ssl, nread)){
-	    case SSL_ERROR_NONE:
+
+    rb_str_locktmp(str);
+    for (;;) {
+        int nread = SSL_read(ssl, RSTRING_PTR(str), ilen);
+        switch (ssl_get_error(ssl, nread)) {
+          case SSL_ERROR_NONE:
+            rb_str_unlocktmp(str);
+            rb_str_set_len(str, nread);
+            return str;
+          case SSL_ERROR_ZERO_RETURN:
+            rb_str_unlocktmp(str);
+            if (no_exception_p(opts)) { return Qnil; }
+            rb_eof_error();
+          case SSL_ERROR_WANT_WRITE:
+            if (nonblock) {
                 rb_str_unlocktmp(str);
-		goto end;
-	    case SSL_ERROR_ZERO_RETURN:
+                if (no_exception_p(opts)) { return sym_wait_writable; }
+                write_would_block(nonblock);
+            }
+            io_wait_writable(fptr);
+            continue;
+          case SSL_ERROR_WANT_READ:
+            if (nonblock) {
                 rb_str_unlocktmp(str);
-		if (no_exception_p(opts)) { return Qnil; }
-		rb_eof_error();
-	    case SSL_ERROR_WANT_WRITE:
-                if (nonblock) {
-                    rb_str_unlocktmp(str);
-                    if (no_exception_p(opts)) { return sym_wait_writable; }
-                    write_would_block(nonblock);
-                }
-                io_wait_writable(fptr);
-                continue;
-	    case SSL_ERROR_WANT_READ:
-                if (nonblock) {
-                    rb_str_unlocktmp(str);
-                    if (no_exception_p(opts)) { return sym_wait_readable; }
-                    read_would_block(nonblock);
-                }
-                io_wait_readable(fptr);
-		continue;
-	    case SSL_ERROR_SYSCALL:
-		if (!ERR_peek_error()) {
-                    rb_str_unlocktmp(str);
-		    if (errno)
-			rb_sys_fail(0);
-		    else {
-			/*
-			 * The underlying BIO returned 0. This is actually a
-			 * protocol error. But unfortunately, not all
-			 * implementations cleanly shutdown the TLS connection
-			 * but just shutdown/close the TCP connection. So report
-			 * EOF for now...
-			 */
-			if (no_exception_p(opts)) { return Qnil; }
-			rb_eof_error();
-		    }
-		}
-                /* fall through */
-	    default:
+                if (no_exception_p(opts)) { return sym_wait_readable; }
+                read_would_block(nonblock);
+            }
+            io_wait_readable(fptr);
+            continue;
+          case SSL_ERROR_SYSCALL:
+            if (!ERR_peek_error()) {
                 rb_str_unlocktmp(str);
-		ossl_raise(eSSLError, "SSL_read");
-	    }
-        }
-    }
-    else {
-        ID meth = nonblock ? rb_intern("read_nonblock") : rb_intern("sysread");
-
-        rb_warning("SSL session is not started yet.");
-#if defined(RB_PASS_KEYWORDS)
-        if (nonblock) {
-            VALUE argv[3];
-            argv[0] = len;
-            argv[1] = str;
-            argv[2] = opts;
-            return rb_funcallv_kw(io, meth, 3, argv, RB_PASS_KEYWORDS);
-        }
-#else
-        if (nonblock) {
-            return rb_funcall(io, meth, 3, len, str, opts);
+                if (errno)
+                    rb_sys_fail(0);
+                else {
+                    /*
+                     * The underlying BIO returned 0. This is actually a
+                     * protocol error. But unfortunately, not all
+                     * implementations cleanly shutdown the TLS connection
+                     * but just shutdown/close the TCP connection. So report
+                     * EOF for now...
+                     */
+                    if (no_exception_p(opts)) { return Qnil; }
+                    rb_eof_error();
+                }
+            }
+            /* fall through */
+          default:
+            rb_str_unlocktmp(str);
+            ossl_raise(eSSLError, "SSL_read");
         }
-#endif
-        else
-            return rb_funcall(io, meth, 2, len, str);
     }
-
-  end:
-    rb_str_set_len(str, nread);
-    return str;
 }
 
 /*
@@ -1936,78 +1912,55 @@ static VALUE
 ossl_ssl_write_internal(VALUE self, VALUE str, VALUE opts)
 {
     SSL *ssl;
-    int nwrite = 0;
     rb_io_t *fptr;
-    int nonblock = opts != Qfalse;
+    int num, nonblock = opts != Qfalse;
     VALUE tmp, io;
 
-    tmp = rb_str_new_frozen(StringValue(str));
     GetSSL(self, ssl);
+    if (!ssl_started(ssl))
+        rb_raise(eSSLError, "SSL session is not started yet");
+
+    tmp = rb_str_new_frozen(StringValue(str));
     io = rb_attr_get(self, id_i_io);
     GetOpenFile(io, fptr);
-    if (ssl_started(ssl)) {
-	for (;;) {
-	    int num = RSTRING_LENINT(tmp);
-
-	    /* SSL_write(3ssl) manpage states num == 0 is undefined */
-	    if (num == 0)
-		goto end;
-
-	    nwrite = SSL_write(ssl, RSTRING_PTR(tmp), num);
-	    switch(ssl_get_error(ssl, nwrite)){
-	    case SSL_ERROR_NONE:
-		goto end;
-	    case SSL_ERROR_WANT_WRITE:
-		if (no_exception_p(opts)) { return sym_wait_writable; }
-                write_would_block(nonblock);
-                io_wait_writable(fptr);
-                continue;
-	    case SSL_ERROR_WANT_READ:
-		if (no_exception_p(opts)) { return sym_wait_readable; }
-                read_would_block(nonblock);
-                io_wait_readable(fptr);
-                continue;
-	    case SSL_ERROR_SYSCALL:
+
+    /* SSL_write(3ssl) manpage states num == 0 is undefined */
+    num = RSTRING_LENINT(tmp);
+    if (num == 0)
+        return INT2FIX(0);
+
+    for (;;) {
+        int nwritten = SSL_write(ssl, RSTRING_PTR(tmp), num);
+        switch (ssl_get_error(ssl, nwritten)) {
+          case SSL_ERROR_NONE:
+            return INT2NUM(nwritten);
+          case SSL_ERROR_WANT_WRITE:
+            if (no_exception_p(opts)) { return sym_wait_writable; }
+            write_would_block(nonblock);
+            io_wait_writable(fptr);
+            continue;
+          case SSL_ERROR_WANT_READ:
+            if (no_exception_p(opts)) { return sym_wait_readable; }
+            read_would_block(nonblock);
+            io_wait_readable(fptr);
+            continue;
+          case SSL_ERROR_SYSCALL:
 #ifdef __APPLE__
-                /*
-                 * It appears that send syscall can return EPROTOTYPE if the
-                 * socket is being torn down. Retry to get a proper errno to
-                 * make the error handling in line with the socket library.
-                 * [Bug #14713] https://bugs.ruby-lang.org/issues/14713
-                 */
-                if (errno == EPROTOTYPE)
-                    continue;
+            /*
+             * It appears that send syscall can return EPROTOTYPE if the
+             * socket is being torn down. Retry to get a proper errno to
+             * make the error handling in line with the socket library.
+             * [Bug #14713] https://bugs.ruby-lang.org/issues/14713
+             */
+            if (errno == EPROTOTYPE)
+                continue;
 #endif
-		if (errno) rb_sys_fail(0);
-		/* fallthrough */
-	    default:
-		ossl_raise(eSSLError, "SSL_write");
-	    }
+            if (errno) rb_sys_fail(0);
+            /* fallthrough */
+          default:
+            ossl_raise(eSSLError, "SSL_write");
         }
     }
-    else {
-	ID meth = nonblock ?
-	    rb_intern("write_nonblock") : rb_intern("syswrite");
-
-        rb_warning("SSL session is not started yet.");
-#if defined(RB_PASS_KEYWORDS)
-        if (nonblock) {
-            VALUE argv[2];
-            argv[0] = str;
-            argv[1] = opts;
-            return rb_funcallv_kw(io, meth, 2, argv, RB_PASS_KEYWORDS);
-        }
-#else
-        if (nonblock) {
-            return rb_funcall(io, meth, 2, str, opts);
-        }
-#endif
-        else
-            return rb_funcall(io, meth, 1, str);
-    }
-
-  end:
-    return INT2NUM(nwrite);
 }
 
 /*

test/openssl/test_ssl.rb

@@ -373,59 +373,20 @@ def test_client_ca
     }
   end
 
-  def test_read_nonblock_without_session
-    EnvUtil.suppress_warning do
-      start_server(start_immediately: false) { |port|
-        sock = TCPSocket.new("127.0.0.1", port)
-        ssl = OpenSSL::SSL::SSLSocket.new(sock)
-        ssl.sync_close = true
-
-        assert_equal :wait_readable, ssl.read_nonblock(100, exception: false)
-        ssl.write("abc\n")
-        IO.select [ssl]
-        assert_equal('a', ssl.read_nonblock(1))
-        assert_equal("bc\n", ssl.read_nonblock(100))
-        assert_equal :wait_readable, ssl.read_nonblock(100, exception: false)
-        ssl.close
-      }
-    end
-  end
-
-  def test_starttls
-    server_proc = -> (ctx, ssl) {
-      while line = ssl.gets
-        if line =~ /^STARTTLS$/
-          ssl.write("x")
-          ssl.flush
-          ssl.accept
-          break
-        end
-        ssl.write(line)
-      end
-      readwrite_loop(ctx, ssl)
-    }
-
-    EnvUtil.suppress_warning do # read/write on not started session
-      start_server(start_immediately: false,
-                   server_proc: server_proc) { |port|
-        begin
-          sock = TCPSocket.new("127.0.0.1", port)
-          ssl = OpenSSL::SSL::SSLSocket.new(sock)
-
-          ssl.puts "plaintext"
-          assert_equal "plaintext\n", ssl.gets
+  def test_unstarted_session
+    start_server do |port|
+      sock = TCPSocket.new("127.0.0.1", port)
+      ssl = OpenSSL::SSL::SSLSocket.new(sock)
 
-          ssl.puts("STARTTLS")
-          ssl.read(1)
-          ssl.connect
+      assert_raise(OpenSSL::SSL::SSLError) { ssl.syswrite("data") }
+      assert_raise(OpenSSL::SSL::SSLError) { ssl.sysread(1) }
 
-          ssl.puts "over-tls"
-          assert_equal "over-tls\n", ssl.gets
-        ensure
-          ssl&.close
-          sock&.close
-        end
-      }
+      ssl.connect
+      ssl.puts "abc"
+      assert_equal "abc\n", ssl.gets
+    ensure
+      ssl&.close
+      sock&.close
     end
   end