svn commit: r312953 - head/sys/net

[Luiz Otavio O Souza]

Author: loos
Date: Sun Jan 29 18:41:09 2017
New Revision: 312953
URL: https://svnweb.freebsd.org/changeset/base/312953

Log:
  The stf(4) interface name does not conform with the default naming
  convention for interfaces, because only one stf(4) interface can exist
  in the system.
  
  This disallow the use of unit numbers different than 0, however, it is
  possible to create the clone without specify the unit number (wildcard).
  
  In the wildcard case we must update the interface name before return.
  
  This fix an infinite recursion in pf code that keeps track of network
  interfaces and groups:
  
  1 - a group for the cloned type of the interface is added (stf in this
      case);
  2 - the system will now try to add an interface named stf (instead of
      stf0) to stf group;
  3 - when pfi_kif_attach() tries to search for an already existing 'stf'
      interface, the 'stf' group is returned and thus the group is added
      as an interface of itself;
  
  This will now cause a crash at the first attempt to traverse the groups
  which the stf interface belongs (which loops over itself).
  
  Obtained from:	pfSense
  MFC after:	2 weeks
  Sponsored by:	Rubicon Communications, LLC (Netgate)

Modified:
  head/sys/net/if_stf.c

Modified: head/sys/net/if_stf.c
==============================================================================
--- head/sys/net/if_stf.c	Sun Jan 29 16:54:55 2017	(r312952)
+++ head/sys/net/if_stf.c	Sun Jan 29 18:41:09 2017	(r312953)
@@ -202,10 +202,16 @@ stf_clone_match(struct if_clone *ifc, co
 static int
 stf_clone_create(struct if_clone *ifc, char *name, size_t len, caddr_t params)
 {
-	int err, unit;
+	char *dp;
+	int err, unit, wildcard;
 	struct stf_softc *sc;
 	struct ifnet *ifp;
 
+	err = ifc_name2unit(name, &unit);
+	if (err != 0)
+		return (err);
+	wildcard = (unit < 0);
+
 	/*
 	 * We can only have one unit, but since unit allocation is
 	 * already locked, we use it to keep from allocating extra
@@ -229,7 +235,20 @@ stf_clone_create(struct if_clone *ifc, c
 	/*
 	 * Set the name manually rather then using if_initname because
 	 * we don't conform to the default naming convention for interfaces.
+	 * In the wildcard case, we need to update the name.
 	 */
+	if (wildcard) {
+		for (dp = name; *dp != '\0'; dp++);
+		if (snprintf(dp, len - (dp-name), "%d", unit) >
+		    len - (dp-name) - 1) {
+			/*
+			 * This can only be a programmer error and
+			 * there's no straightforward way to recover if
+			 * it happens.
+			 */
+			panic("if_clone_create(): interface name too long");
+		}
+	}
 	strlcpy(ifp->if_xname, name, IFNAMSIZ);
 	ifp->if_dname = stfname;
 	ifp->if_dunit = IF_DUNIT_NONE;