native_support.c in colouringcode-passenger-0.2

- old
+ new

@@ -28,10 +28,11 @@
 #include <sys/socket.h>
 #include <stdio.h>
 #include <string.h>
 #include <unistd.h>
 #include <errno.h>
+#include <grp.h>
 #ifdef __OpenBSD__
 	// OpenBSD needs this for 'struct iovec'. Apparently it isn't
 	// always included by unistd.h and sys/types.h.
 	#include <sys/uio.h>
 #endif
@@ -156,14 +157,18 @@
 		rb_sys_fail("Cannot read file descriptor with recvmsg()");
 		return Qnil;
 	}
 	
 	control_header = CMSG_FIRSTHDR(&msg);
+	if (control_header == NULL) {
+		rb_raise(rb_eIOError, "No valid file descriptor received.");
+		return Qnil;
+	}
 	if (control_header->cmsg_len   != EXPECTED_CMSG_LEN
 	 || control_header->cmsg_level != SOL_SOCKET
 	 || control_header->cmsg_type  != SCM_RIGHTS) {
-		rb_sys_fail("No valid file descriptor received.");
+		rb_raise(rb_eIOError, "No valid file descriptor received.");
 		return Qnil;
 	}
 	#if defined(__APPLE__) || defined(__SOLARIS__) || defined(__arm__)
 		return INT2NUM(control_data.fd);
 	#else
@@ -280,10 +285,33 @@
 	setvbuf(stdout, NULL, _IONBF, 0);
 	setvbuf(stderr, NULL, _IONBF, 0);
 	return Qnil;
 }
 
+/**
+ * Ruby's implementations of initgroups, setgid and setuid are broken various ways,
+ * sigh...
+ * Ruby's setgid and setuid can't handle negative UIDs and initgroups is just broken.
+ * Work around it by using our own implementation.
+ */
+static VALUE
+switch_user(VALUE self, VALUE username, VALUE uid, VALUE gid) {
+	uid_t the_uid = NUM2LL(uid);
+	gid_t the_gid = NUM2LL(gid);
+
+	if (initgroups(RSTRING_PTR(username), the_gid) == -1) {
+		rb_sys_fail("initgroups");
+	}
+	if (setgid(the_gid) == -1) {
+		rb_sys_fail("setgid");
+	}
+	if (setuid(the_uid) == -1) {
+		rb_sys_fail("setuid");
+	}
+	return Qnil;
+}
+
 /***************************/
 
 void
 Init_native_support() {
 	struct sockaddr_un addr;
@@ -300,9 +328,10 @@
 	rb_define_singleton_method(mNativeSupport, "recv_fd", recv_fd, 1);
 	rb_define_singleton_method(mNativeSupport, "create_unix_socket", create_unix_socket, 2);
 	rb_define_singleton_method(mNativeSupport, "accept", f_accept, 1);
 	rb_define_singleton_method(mNativeSupport, "close_all_file_descriptors", close_all_file_descriptors, 1);
 	rb_define_singleton_method(mNativeSupport, "disable_stdio_buffering", disable_stdio_buffering, 0);
+	rb_define_singleton_method(mNativeSupport, "switch_user", switch_user, 3);
 	
 	/* The maximum length of a Unix socket path, including terminating null. */
 	rb_define_const(mNativeSupport, "UNIX_PATH_MAX", INT2NUM(sizeof(addr.sun_path)));
 }