avoid leaking netlink socket fd to external programs

[elogind.git] / udev / lib / libudev-monitor.c

diff --git a/udev/lib/libudev-monitor.c b/udev/lib/libudev-monitor.c
index e4cb80769cff4e86a792efe2a2c84d84169ccd1a..a8b1a4e2e51195a6dd71e04776d6400bdf0a70e4 100644 (file)
--- a/udev/lib/libudev-monitor.c
+++ b/udev/lib/libudev-monitor.c
@@ -3,18 +3,10 @@
  *
  * Copyright (C) 2008 Kay Sievers <kay.sievers@vrfy.org>
  *
- * This program is free software: you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
  */
 
 #include <stdio.h>
@@ -37,10 +29,16 @@ struct udev_monitor {
        int refcount;
        int sock;
        struct sockaddr_nl snl;
+       struct sockaddr_nl snl_peer;
        struct sockaddr_un sun;
        socklen_t addrlen;
 };
 
+enum udev_monitor_netlink_group {
+       UDEV_MONITOR_KERNEL     = 1,
+       UDEV_MONITOR_UDEV       = 2,
+};
+
 /**
  * udev_monitor_new_from_socket:
  * @udev: udev library context
@@ -94,16 +92,29 @@ struct udev_monitor *udev_monitor_new_from_socket(struct udev *udev, const char
                free(udev_monitor);
                return NULL;
        }
+       util_set_fd_cloexec(udev_monitor->sock);
+
        dbg(udev, "monitor %p created with '%s'\n", udev_monitor, socket_path);
        return udev_monitor;
 }
 
-struct udev_monitor *udev_monitor_new_from_netlink(struct udev *udev)
+struct udev_monitor *udev_monitor_new_from_netlink(struct udev *udev, const char *name)
 {
        struct udev_monitor *udev_monitor;
+       unsigned int group;
 
        if (udev == NULL)
                return NULL;
+
+       if (name == NULL)
+               return NULL;
+       if (strcmp(name, "kernel") == 0)
+               group = UDEV_MONITOR_KERNEL;
+       else if (strcmp(name, "udev") == 0)
+               group = UDEV_MONITOR_UDEV;
+       else
+               return NULL;
+
        udev_monitor = calloc(1, sizeof(struct udev_monitor));
        if (udev_monitor == NULL)
                return NULL;
@@ -116,12 +127,14 @@ struct udev_monitor *udev_monitor_new_from_netlink(struct udev *udev)
                free(udev_monitor);
                return NULL;
        }
+       util_set_fd_cloexec(udev_monitor->sock);
 
        udev_monitor->snl.nl_family = AF_NETLINK;
-       udev_monitor->snl.nl_pid = getpid();
-       udev_monitor->snl.nl_groups = 1;
+       udev_monitor->snl.nl_groups = group;
+       udev_monitor->snl_peer.nl_family = AF_NETLINK;
+       udev_monitor->snl_peer.nl_groups = UDEV_MONITOR_UDEV;
 
-       dbg(udev, "monitor %p created with NETLINK_KOBJECT_UEVENT\n", udev_monitor);
+       dbg(udev, "monitor %p created with NETLINK_KOBJECT_UEVENT (%u)\n", udev_monitor, group);
        return udev_monitor;
 }
 
@@ -131,14 +144,16 @@ int udev_monitor_enable_receiving(struct udev_monitor *udev_monitor)
        const int on = 1;
 
        if (udev_monitor->snl.nl_family != 0) {
-               err = bind(udev_monitor->sock, (struct sockaddr *)&udev_monitor->snl, sizeof(struct sockaddr_nl));
+               err = bind(udev_monitor->sock,
+                          (struct sockaddr *)&udev_monitor->snl, sizeof(struct sockaddr_nl));
                if (err < 0) {
                        err(udev_monitor->udev, "bind failed: %m\n");
                        return err;
                }
                dbg(udev_monitor->udev, "monitor %p listening on netlink\n", udev_monitor);
        } else if (udev_monitor->sun.sun_family != 0) {
-               err = bind(udev_monitor->sock, (struct sockaddr *)&udev_monitor->sun, udev_monitor->addrlen);
+               err = bind(udev_monitor->sock,
+                          (struct sockaddr *)&udev_monitor->sun, udev_monitor->addrlen);
                if (err < 0) {
                        err(udev_monitor->udev, "bind failed: %m\n");
                        return err;
@@ -389,9 +404,18 @@ int udev_monitor_send_device(struct udev_monitor *udev_monitor, struct udev_devi
        len = udev_device_get_properties_monitor_buf(udev_device, &buf);
        if (len < 32)
                return -1;
-       count = sendto(udev_monitor->sock,
-                      buf, len, 0,
-                      (struct sockaddr *)&udev_monitor->sun, udev_monitor->addrlen);
+       if (udev_monitor->sun.sun_family != 0) {
+               count = sendto(udev_monitor->sock,
+                              buf, len, 0,
+                              (struct sockaddr *)&udev_monitor->sun,
+                              udev_monitor->addrlen);
+       } else {
+               /* no destination besides the muticast group, we will always get -1 ECONNREFUSED */
+               count = sendto(udev_monitor->sock,
+                              buf, len, 0,
+                              (struct sockaddr *)&udev_monitor->snl_peer,
+                              sizeof(struct sockaddr_nl));
+       }
        info(udev_monitor->udev, "passed %zi bytes to monitor %p, \n", count, udev_monitor);
        return count;
 }