[PATCH] net core: Some interface flags not returned by SIOCGIFFLAGS

Commit b00055aacdb172c05067612278ba27265fcd05ce " [NET] core: add
RFC2863 operstate" defined new interface flag values.  Its
documentation specified that these flags could be accessed from user
space via SIOCGIFFLAGS.  However, this does not work because the new
flags do not fit in that ioctl's argument width.

Change the documentation to match the code's behavior.  Also change
the source to explicitly show the truncation.  This _should_ have no
effect on executable code, and did not with gcc 4.2.4 generating x86
code.

A new ioctl could be defined to return all interface flags to user
space.  However, since this has been broken for three years with no
one complaining, there doesn't seem much need.  They are still
accessible via netlink.

Reported-by:  "Fredrik Arnerup" <fredrik.arnerup@edgeware.tv>
Signed-off-by: John Dykstra <john.dykstra1@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/Documentation/networking/operstates.txt b/Documentation/networking/operstates.txt
index c9074f9b78bb7f2b25df1607c37953fdc7b6aa47..1a77a3cfae540795d1d2ae0074cde85f15113f42 100644 (file)
--- a/Documentation/networking/operstates.txt
+++ b/Documentation/networking/operstates.txt
@@ -38,9 +38,6 @@ ifinfomsg::if_flags & IFF_LOWER_UP:
 ifinfomsg::if_flags & IFF_DORMANT:
  Driver has signaled netif_dormant_on()
 
-These interface flags can also be queried without netlink using the
-SIOCGIFFLAGS ioctl.
-
 TLV IFLA_OPERSTATE
 
 contains RFC2863 state of the interface in numeric representation:

diff --git a/net/core/dev.c b/net/core/dev.c
index 11560e3258b525ace5b5c328bf7cbbc9dd1f0677..a09bf658970f6b48d8c59a231df6367ce356abbc 100644 (file)
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -4209,7 +4209,7 @@ static int dev_ifsioc_locked(struct net *net, struct ifreq *ifr, unsigned int cm
 
        switch (cmd) {
                case SIOCGIFFLAGS:      /* Get interface flags */
-                       ifr->ifr_flags = dev_get_flags(dev);
+                       ifr->ifr_flags = (short) dev_get_flags(dev);
                        return 0;
 
                case SIOCGIFMETRIC:     /* Get the metric on the interface