Add kernel infrastructure for network device cloning.

Reviewed by:	ru, ume
Obtained from:	NetBSD
MFC after:	1 week

sys/net/if.c

@@ -56,6 +56,7 @@
 #include <net/if_arp.h>
 #include <net/if_dl.h>
 #include <net/if_types.h>
+#include <net/if_var.h>
 #include <net/radix.h>
 #include <net/route.h>
 
@@ -96,6 +97,12 @@ struct	ifnethead ifnet;	/* depend on static init XXX */
 extern void	nd6_setmtu __P((struct ifnet *));
 #endif
 
+struct if_clone *if_clone_lookup __P((const char *, int *));
+int if_clone_list __P((struct if_clonereq *));
+
+LIST_HEAD(, if_clone) if_cloners = LIST_HEAD_INITIALIZER(if_cloners);
+int if_cloners_count;
+
 /*
  * Network interface utility routines.
  *
@@ -349,6 +356,178 @@ if_rtdel(rn, arg)
 	return (0);
 }
 
+/*
+ * Create a clone network interface.
+ */
+int
+if_clone_create(name, len)
+	char *name;
+	int len;
+{
+	struct if_clone *ifc;
+	char *dp;
+	int wildcard;
+	int unit;
+	int err;
+
+	ifc = if_clone_lookup(name, &unit);
+	if (ifc == NULL)
+		return (EINVAL);
+
+	if (ifunit(name) != NULL)
+		return (EEXIST);
+
+	wildcard = (unit < 0);
+
+	err = (*ifc->ifc_create)(ifc, &unit);
+	if (err != 0)
+		return (err);
+
+	/* 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");
+		}
+			
+	}
+
+	return (0);
+}
+
+/*
+ * Destroy a clone network interface.
+ */
+int
+if_clone_destroy(name)
+	const char *name;
+{
+	struct if_clone *ifc;
+	struct ifnet *ifp;
+
+	ifc = if_clone_lookup(name, NULL);
+	if (ifc == NULL)
+		return (EINVAL);
+
+	ifp = ifunit(name);
+	if (ifp == NULL)
+		return (ENXIO);
+
+	if (ifc->ifc_destroy == NULL)
+		return (EOPNOTSUPP);
+
+	(*ifc->ifc_destroy)(ifp);
+	return (0);
+}
+
+/*
+ * Look up a network interface cloner.
+ */
+struct if_clone *
+if_clone_lookup(name, unitp)
+	const char *name;
+	int *unitp;
+{
+	struct if_clone *ifc;
+	const char *cp;
+	int i;
+
+	for (ifc = LIST_FIRST(&if_cloners); ifc != NULL;) {
+		for (cp = name, i = 0; i < ifc->ifc_namelen; i++, cp++) {
+			if (ifc->ifc_name[i] != *cp)
+				goto next_ifc;
+		}
+		goto found_name;
+ next_ifc:
+		ifc = LIST_NEXT(ifc, ifc_list);
+	}
+
+	/* No match. */
+	return ((struct if_clone *)NULL);
+
+ found_name:
+	if (*cp == '\0') {
+		i = -1;
+	} else {
+		for (i = 0; *cp != '\0'; cp++) {
+			if (*cp < '0' || *cp > '9') {
+				/* Bogus unit number. */
+				return (NULL);
+			}
+			i = (i * 10) + (*cp - '0');
+		}
+	}
+
+	if (unitp != NULL)
+		*unitp = i;
+	return (ifc);
+}
+
+/*
+ * Register a network interface cloner.
+ */
+void
+if_clone_attach(ifc)
+	struct if_clone *ifc;
+{
+
+	LIST_INSERT_HEAD(&if_cloners, ifc, ifc_list);
+	if_cloners_count++;
+}
+
+/*
+ * Unregister a network interface cloner.
+ */
+void
+if_clone_detach(ifc)
+	struct if_clone *ifc;
+{
+
+	LIST_REMOVE(ifc, ifc_list);
+	if_cloners_count--;
+}
+
+/*
+ * Provide list of interface cloners to userspace.
+ */
+int
+if_clone_list(ifcr)
+	struct if_clonereq *ifcr;
+{
+	char outbuf[IFNAMSIZ], *dst;
+	struct if_clone *ifc;
+	int count, error = 0;
+
+	ifcr->ifcr_total = if_cloners_count;
+	if ((dst = ifcr->ifcr_buffer) == NULL) {
+		/* Just asking how many there are. */
+		return (0);
+	}
+
+	if (ifcr->ifcr_count < 0)
+		return (EINVAL);
+
+	count = (if_cloners_count < ifcr->ifcr_count) ?
+	    if_cloners_count : ifcr->ifcr_count;
+
+	for (ifc = LIST_FIRST(&if_cloners); ifc != NULL && count != 0;
+	     ifc = LIST_NEXT(ifc, ifc_list), count--, dst += IFNAMSIZ) {
+		strncpy(outbuf, ifc->ifc_name, IFNAMSIZ);
+		outbuf[IFNAMSIZ - 1] = '\0';	/* sanity */
+		error = copyout(outbuf, dst, IFNAMSIZ);
+		if (error)
+			break;
+	}
+
+	return (error);
+}
+
 /*
  * Locate an interface based on a complete address.
  */
@@ -687,10 +866,10 @@ if_slowtimo(arg)
  * interface structure pointer.
  */
 struct ifnet *
-ifunit(char *name)
+ifunit(const char *name)
 {
 	char namebuf[IFNAMSIZ + 1];
-	char *cp;
+	const char *cp;
 	struct ifnet *ifp;
 	int unit;
 	unsigned len, m;
@@ -781,6 +960,20 @@ ifioctl(so, cmd, data, p)
 		return (ifconf(cmd, data));
 	}
 	ifr = (struct ifreq *)data;
+
+	switch (cmd) {
+	case SIOCIFCREATE:
+	case SIOCIFDESTROY:
+		if ((error = suser(p)) != 0)
+			return (error);
+		return ((cmd == SIOCIFCREATE) ?
+			if_clone_create(ifr->ifr_name, sizeof(ifr->ifr_name)) :
+			if_clone_destroy(ifr->ifr_name));
+	
+	case SIOCIFGCLONERS:
+		return (if_clone_list((struct if_clonereq *)data));
+	}
+
 	ifp = ifunit(ifr->ifr_name);
 	if (ifp == 0)
 		return (ENXIO);

sys/net/if.h

@@ -37,6 +37,8 @@
 #ifndef _NET_IF_H_
 #define	_NET_IF_H_
 
+#include <sys/queue.h>
+
 /*
  * <net/if.h> does not depend on <sys/time.h> on most other systems.  This
  * helps userland compatibility.  (struct timeval ifi_lastchange)
@@ -45,6 +47,40 @@
 #include <sys/time.h>
 #endif
 
+struct ifnet;
+
+/*
+ * Length of interface external name, including terminating '\0'.
+ * Note: this is the same size as a generic device's external name.
+ */
+#define		IFNAMSIZ	16
+#define		IF_NAMESIZE	IFNAMSIZ
+
+/*
+ * Structure describing a `cloning' interface.
+ */
+struct if_clone {
+	LIST_ENTRY(if_clone) ifc_list;	/* on list of cloners */
+	const char *ifc_name;		/* name of device, e.g. `gif' */
+	size_t ifc_namelen;		/* length of name */
+
+	int	(*ifc_create)(struct if_clone *, int *);
+	void	(*ifc_destroy)(struct ifnet *);
+};
+
+#define IF_CLONE_INITIALIZER(name, create, destroy)			\
+	{ { 0 }, name, sizeof(name) - 1, create, destroy }
+
+/*
+ * Structure used to query names of interface cloners.
+ */
+
+struct if_clonereq {
+	int	ifcr_total;		/* total cloners (out) */
+	int	ifcr_count;		/* room for this many in user buffer */
+	char	*ifcr_buffer;		/* buffer for cloner names */
+};
+
 /*
  * Structure describing information about an interface
  * which may be of interest to management entities.
@@ -151,8 +187,6 @@ struct ifma_msghdr {
  * remainder may be interface specific.
  */
 struct	ifreq {
-#define	IFNAMSIZ	16
-#define	IF_NAMESIZE	IFNAMSIZ
 	char	ifr_name[IFNAMSIZ];		/* if name, e.g. "en0" */
 	union {
 		struct	sockaddr ifru_addr;

sys/net/if_var.h

@@ -401,7 +401,7 @@ void	if_up __P((struct ifnet *));
 /*void	ifinit __P((void));*/ /* declared in systm.h for main() */
 int	ifioctl __P((struct socket *, u_long, caddr_t, struct proc *));
 int	ifpromisc __P((struct ifnet *, int));
-struct	ifnet *ifunit __P((char *));
+struct	ifnet *ifunit __P((const char *));
 struct	ifnet *if_withname __P((struct sockaddr *));
 
 int	if_poll_recv_slow __P((struct ifnet *ifp, int *quotap));
@@ -423,6 +423,12 @@ struct	ifmultiaddr *ifmaof_ifpforaddr __P((struct sockaddr *,
 					    struct ifnet *));
 int	if_simloop __P((struct ifnet *ifp, struct mbuf *m, int af, int hlen));
 
+void	if_clone_attach __P((struct if_clone *));
+void	if_clone_detach __P((struct if_clone *));
+
+int	if_clone_create __P((char *, int));
+int	if_clone_destroy __P((const char *));
+
 #endif /* _KERNEL */
 
 #endif /* !_NET_IF_VAR_H_ */

sys/sys/sockio.h

@@ -100,4 +100,8 @@
 #define	SIOCGIFSTATUS	_IOWR('i', 59, struct ifstat)	/* get IF status */
 #define	SIOCSIFLLADDR	_IOW('i', 60, struct ifreq)	/* set link level addr */
 
+#define SIOCIFCREATE	_IOWR('i', 122, struct ifreq)	/* create clone if */
+#define SIOCIFDESTROY	 _IOW('i', 121, struct ifreq)	/* destroy clone if */
+#define SIOCIFGCLONERS	_IOWR('i', 120, struct if_clonereq) /* get cloners */
+
 #endif /* !_SYS_SOCKIO_H_ */