Add interface description capability as inspired by OpenBSD.

MFC after:	3 months

3 files changed, 45 insertions, 1 deletions

diff --git a/sys/net/if.c b/sys/net/if.c
index 55de666..4ba453a 100644
--- a/sys/net/if.c
+++ b/sys/net/if.c
@@ -463,6 +463,8 @@ if_free_internal(struct ifnet *ifp)
 #ifdef MAC
 	mac_ifnet_destroy(ifp);
 #endif /* MAC */
+	if (ifp->if_description != NULL)
+		sbuf_delete(ifp->if_description);
 	IF_AFDATA_DESTROY(ifp);
 	IF_ADDR_LOCK_DESTROY(ifp);
 	ifq_delete(&ifp->if_snd);
@@ -2090,6 +2092,45 @@ ifhwioctl(u_long cmd, struct ifnet *ifp, caddr_t data, struct thread *td)
 		ifr->ifr_phys = ifp->if_physical;
 		break;
 
+	case SIOCGIFDESCR:
+		IF_AFDATA_RLOCK(ifp);
+		if (ifp->if_description == NULL)
+			error = ENOMSG;
+		else
+			error = copystr(sbuf_data(ifp->if_description),
+					ifr->ifr_buffer.buffer,
+					ifr->ifr_buffer.length, NULL);
+		IF_AFDATA_RUNLOCK(ifp);
+		break;
+
+	case SIOCSIFDESCR:
+		error = priv_check(td, PRIV_NET_SETIFDESCR);
+		if (error)
+			return (error);
+
+		IF_AFDATA_WLOCK(ifp);
+		if (ifp->if_description == NULL) {
+			ifp->if_description = sbuf_new_auto();
+			if (ifp->if_description == NULL) {
+				error = ENOMEM;
+				IF_AFDATA_WUNLOCK(ifp);
+				break;
+			}
+		} else
+			sbuf_clear(ifp->if_description);
+
+		if (sbuf_copyin(ifp->if_description, ifr->ifr_buffer.buffer,
+				ifr->ifr_buffer.length) == -1)
+			error = EFAULT;
+
+		if (error == 0) {
+			sbuf_finish(ifp->if_description);
+			getmicrotime(&ifp->if_lastchange);
+		}
+		IF_AFDATA_WUNLOCK(ifp);
+
+		break;
+
 	case SIOCSIFFLAGS:
 		error = priv_check(td, PRIV_NET_SETIFFLAGS);
 		if (error)
diff --git a/sys/net/if.h b/sys/net/if.h
index 857ab7f..89f172b 100644
--- a/sys/net/if.h
+++ b/sys/net/if.h
@@ -294,6 +294,7 @@ struct	ifreq {
 		struct	sockaddr ifru_addr;
 		struct	sockaddr ifru_dstaddr;
 		struct	sockaddr ifru_broadaddr;
+		struct { size_t length; caddr_t	buffer; } ifru_buffer;
 		short	ifru_flags[2];
 		short	ifru_index;
 		int	ifru_jid;
@@ -307,6 +308,7 @@ struct	ifreq {
 #define	ifr_addr	ifr_ifru.ifru_addr	/* address */
 #define	ifr_dstaddr	ifr_ifru.ifru_dstaddr	/* other end of p-to-p link */
 #define	ifr_broadaddr	ifr_ifru.ifru_broadaddr	/* broadcast address */
+#define	ifr_buffer	ifr_ifru.ifru_buffer	/* user supplied buffer with its length */
 #define	ifr_flags	ifr_ifru.ifru_flags[0]	/* flags (low 16 bits) */
 #define	ifr_flagshigh	ifr_ifru.ifru_flags[1]	/* flags (high 16 bits) */
 #define	ifr_jid		ifr_ifru.ifru_jid	/* jail/vnet */
diff --git a/sys/net/if_var.h b/sys/net/if_var.h
index 523b9e8..82e7aab 100644
--- a/sys/net/if_var.h
+++ b/sys/net/if_var.h
@@ -198,6 +198,7 @@ struct ifnet {
 	void	*if_pf_kif;
 	void	*if_lagg;		/* lagg glue */
 	u_char	 if_alloctype;		/* if_type at time of allocation */
+	struct sbuf *if_description;	/* interface description */
 
 	/*
 	 * Spare fields are added so that we can modify sensitive data
@@ -205,7 +206,7 @@ struct ifnet {
 	 * be used with care where binary compatibility is required.
 	 */
 	char	 if_cspare[3];
-	void	*if_pspare[8];
+	void	*if_pspare[7];
 	int	if_ispare[4];
 };