Discard carrier messages from non-ethernet devices

IFF_LOWER_UP has no meaning for wireless interfaces, it can mean that an
association has been made with an access point, but it does not mean
that an addressing has been completed.

This patch discards "carrier up" messages from interfaces that do not
look like ethernet devices.

1 files changed, 155 insertions, 3 deletions

diff --git a/src/monitor/monitor_netlink.c b/src/monitor/monitor_netlink.c
index cbf717fc3..737266bfb 100644
--- a/src/monitor/monitor_netlink.c
+++ b/src/monitor/monitor_netlink.c
@@ -24,6 +24,7 @@
 #include <talloc.h>
 #include <tevent.h>
 #include <sys/types.h>
+#include <sys/ioctl.h>
 #define __USE_GNU /* needed for struct ucred */
 #include <sys/socket.h>
 #include <unistd.h>
@@ -36,6 +37,7 @@
 #include <linux/if.h>
 #include <linux/socket.h>
 #include <linux/rtnetlink.h>
+#include <linux/wireless.h>
 #include <netlink/netlink.h>
 #include <netlink/utils.h>
 #include <netlink/route/addr.h>
@@ -55,6 +57,14 @@
 #define nlw_object_match nl_object_match_filter
 #define NLW_OK NL_OK
 
+#define SYSFS_IFACE_TEMPLATE "/sys/class/net/%s/type"
+#define SYSFS_IFACE_PATH_MAX (21+IFNAMSIZ)
+
+#define PHY_80211_SUBDIR   "phy80211"
+#define SYSFS_SUBDIR_PATH_MAX (SYSFS_IFACE_PATH_MAX+9)
+
+#define BUFSIZE 8
+
 struct netlink_ctx {
 #ifdef HAVE_LIBNL
     struct nl_handle *nlh;
@@ -76,6 +86,141 @@ static int netlink_ctx_destructor(void *ptr)
 }
 
 /*******************************************************************
+ *                      Utility functions
+ *******************************************************************/
+
+static bool has_wireless_extension(const char *ifname)
+{
+    int s;
+    errno_t ret;
+    struct iwreq iwr;
+
+    s = socket(PF_INET, SOCK_DGRAM, 0);
+    if (s == -1) {
+        ret = errno;
+        DEBUG(2, ("Could not open socket: [%d] %s\n", ret, strerror(ret)));
+        return false;
+    }
+
+    strncpy(iwr.ifr_ifrn.ifrn_name, ifname, IFNAMSIZ);
+    /* Does the interface support a wireless extension? */
+    ret = ioctl(s, SIOCGIWNAME, &iwr);
+    close(s);
+
+    return ret == 0;
+}
+
+static bool has_ethernet_encapsulation(const char *sysfs_path)
+{
+    errno_t ret;
+    int fd = -1;
+    char buf[BUFSIZE];
+
+    fd = open(sysfs_path, O_RDONLY);
+    if (fd == -1) {
+        ret = errno;
+        DEBUG(SSSDBG_OP_FAILURE, ("Could not open sysfs file %s: [%d] %s\n",
+              sysfs_path, ret, strerror(ret)));
+        return false;
+    }
+
+    memset(buf, 0, BUFSIZE);
+    while ((ret = read(fd, buf, BUFSIZE)) != 0) {
+        if (ret == -1) {
+            ret = errno;
+            if (ret == EINTR || ret == EAGAIN) {
+                continue;
+            }
+            DEBUG(SSSDBG_OP_FAILURE,
+                  ("read failed [%d][%s].\n", ret, strerror(ret)));
+            close(fd);
+            return false;
+        }
+    }
+    close(fd);
+
+    return strncmp(buf, "1\n", BUFSIZE) == 0;
+}
+
+static bool has_phy_80211_subdir(const char *sysfs_path)
+{
+    char phy80211_path[SYSFS_IFACE_PATH_MAX];
+    struct stat statbuf;
+    errno_t ret;
+
+    ret = snprintf(phy80211_path, SYSFS_SUBDIR_PATH_MAX,
+                   "%s/%s", sysfs_path, PHY_80211_SUBDIR);
+    if (ret < 0) {
+        DEBUG(SSSDBG_OP_FAILURE, ("snprintf failed"));
+        return false;
+    } else if (ret >= SYSFS_SUBDIR_PATH_MAX) {
+        DEBUG(SSSDBG_OP_FAILURE, ("path too long?!?!\n"));
+        return false;
+    }
+
+    errno = 0;
+    ret = stat(phy80211_path, &statbuf);
+    if (ret == -1) {
+        ret = errno;
+        if (ret == ENOENT || ret == ENOTDIR) {
+            DEBUG(SSSDBG_TRACE_LIBS, ("No %s directory in sysfs, probably "
+                  "not a wireless interface\n", PHY_80211_SUBDIR));
+        } else {
+            DEBUG(SSSDBG_OP_FAILURE, ("stat failed: [%d] %s\n",
+                  ret, strerror(ret)));
+        }
+        return false;
+    }
+
+    if (statbuf.st_mode & S_IFDIR) {
+        DEBUG(SSSDBG_TRACE_LIBS, ("Directory %s found in sysfs, looks like "
+              "a wireless iface\n", PHY_80211_SUBDIR));
+        return true;
+    }
+
+    return false;
+}
+
+static bool discard_iff_up(const char *ifname)
+{
+    char path[SYSFS_IFACE_PATH_MAX];
+    errno_t ret;
+
+    /* This catches most of the new 80211 drivers */
+    if (has_wireless_extension(ifname)) {
+        DEBUG(SSSDBG_TRACE_FUNC, ("%s has a wireless extension\n", ifname));
+        return true;
+    }
+
+    ret = snprintf(path, SYSFS_IFACE_PATH_MAX, SYSFS_IFACE_TEMPLATE, ifname);
+    if (ret < 0) {
+        DEBUG(SSSDBG_OP_FAILURE, ("snprintf failed"));
+        return false;
+    } else if (ret >= SYSFS_IFACE_PATH_MAX) {
+        DEBUG(SSSDBG_OP_FAILURE, ("path too long?!?!\n"));
+        return false;
+    }
+
+    /* This will filter PPP and such. Both wired and wireless
+     * interfaces have the encapsulation. */
+    if (!has_ethernet_encapsulation(path)) {
+        DEBUG(SSSDBG_TRACE_FUNC, ("%s does not have ethernet encapsulation, "
+              "filtering out\n", ifname));
+        return true;
+    }
+
+    /* This captures old WEXT drivers, the new mac8011 would
+     * be caught by the ioctl check */
+    if (has_phy_80211_subdir(path)) {
+        DEBUG(SSSDBG_TRACE_FUNC, ("%s has a 802_11 subdir, filtering out\n",
+              ifname));
+        return true;
+    }
+
+    return false;
+}
+
+/*******************************************************************
  * Wrappers for different capabilities of different libnl versions
  *******************************************************************/
 
@@ -237,8 +382,10 @@ static void link_msg_handler(struct nl_object *obj, void *arg)
 {
     struct netlink_ctx *ctx = (struct netlink_ctx *) arg;
     struct rtnl_link *link_obj;
-    int flags;
+    unsigned int flags;
+    char str_flags[512];
     int ifidx;
+    const char *ifname;
 
     if (!nlw_is_link_object(obj)) return;
 
@@ -246,10 +393,15 @@ static void link_msg_handler(struct nl_object *obj, void *arg)
     flags = rtnl_link_get_flags(link_obj);
     ifidx = rtnl_link_get_ifindex(link_obj);
 
-    DEBUG(8, ("netlink link message: iface idx %d flags 0x%X\n", ifidx, flags));
+    rtnl_link_flags2str(flags, str_flags, 512);
+
+    ifname = rtnl_link_get_name(link_obj);
+    DEBUG(SSSDBG_TRACE_LIBS, ("netlink link message: iface idx %u (%s) "
+          "flags 0x%X (%s)\n", ifidx, ifname, flags, str_flags));
 
     /* IFF_LOWER_UP is the indicator of carrier status */
-    if (flags & IFF_LOWER_UP) {
+    if ((flags & IFF_RUNNING) && (flags & IFF_LOWER_UP) &&
+         !discard_iff_up(ifname)) {
         ctx->change_cb(ctx->cb_data);
     }
 }