Make ip_len and ip_off unsigned values; don't transmit or accept packets

larger than the maximum IP packet size.  From NetBSD.

6 files changed, 37 insertions, 17 deletions

diff --git a/sys/netinet/ip.h b/sys/netinet/ip.h
index 3214fb3f920..fb866314786 100644
--- a/sys/netinet/ip.h
+++ b/sys/netinet/ip.h
@@ -43,10 +43,6 @@
 
 /*
  * Structure of an internet header, naked of options.
- *
- * We declare ip_len and ip_off to be short, rather than u_short
- * pragmatically since otherwise unsigned comparisons can result
- * against negative integers quite easily, and fail in subtle ways.
  */
 struct ip {
 #if BYTE_ORDER == LITTLE_ENDIAN
@@ -58,9 +54,9 @@ struct ip {
 		  ip_hl:4;		/* header length */
 #endif
 	u_int8_t  ip_tos;		/* type of service */
-	int16_t	  ip_len;		/* total length */
+	u_int16_t ip_len;		/* total length */
 	u_int16_t ip_id;		/* identification */
-	int16_t	  ip_off;		/* fragment offset field */
+	u_int16_t ip_off;		/* fragment offset field */
 #define	IP_RF 0x8000			/* reserved fragment flag */
 #define	IP_DF 0x4000			/* dont fragment flag */
 #define	IP_MF 0x2000			/* more fragments flag */
diff --git a/sys/netinet/ip_input.c b/sys/netinet/ip_input.c
index 89b2beb91be..2d8ab0bedb9 100644
--- a/sys/netinet/ip_input.c
+++ b/sys/netinet/ip_input.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: ip_input.c,v 1.19 1996/10/27 00:47:33 deraadt Exp $	*/
+/*	$OpenBSD: ip_input.c,v 1.20 1997/01/26 01:23:43 tholo Exp $	*/
 /*	$NetBSD: ip_input.c,v 1.30 1996/03/16 23:53:58 christos Exp $	*/
 
 /*
@@ -569,10 +569,16 @@ insert:
 		return (0);
 
 	/*
-	 * Reassembly is complete; concatenate fragments.
+	 * Reassembly is complete.  Check for a bogus message size and
+	 * concatenate fragments.
 	 */
 	q = fp->ipq_fragq.lh_first;
 	ip = q->ipqe_ip;
+	if ((next + (ip->ip_hl << 2)) > IP_MAXPACKET) {
+		ipstat.ips_toolong++;
+		ip_freef(fp);
+		return (0);
+	}
 	m = dtom(q->ipqe_ip);
 	t = m->m_next;
 	m->m_next = 0;
diff --git a/sys/netinet/ip_var.h b/sys/netinet/ip_var.h
index 7caed51f3e9..c79623bd0a8 100644
--- a/sys/netinet/ip_var.h
+++ b/sys/netinet/ip_var.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: ip_var.h,v 1.3 1996/03/03 22:30:42 niklas Exp $	*/
+/*	$OpenBSD: ip_var.h,v 1.4 1997/01/26 01:23:44 tholo Exp $	*/
 /*	$NetBSD: ip_var.h,v 1.16 1996/02/13 23:43:20 christos Exp $	*/
 
 /*
@@ -42,11 +42,11 @@
  * Overlay for ip header used by other protocols (tcp, udp).
  */
 struct ipovly {
-	u_int8_t ih_x1[9];		/* (unused) */
-	u_int8_t ih_pr;			/* protocol */
-	int16_t	 ih_len;		/* protocol length */
-	struct	 in_addr ih_src;	/* source internet address */
-	struct	 in_addr ih_dst;	/* destination internet address */
+	u_int8_t  ih_x1[9];		/* (unused) */
+	u_int8_t  ih_pr;		/* protocol */
+	u_int16_t ih_len;		/* protocol length */
+	struct	  in_addr ih_src;	/* source internet address */
+	struct	  in_addr ih_dst;	/* destination internet address */
 };
 
 /*
@@ -144,6 +144,7 @@ struct	ipstat {
 	u_long	ips_rawout;		/* total raw ip packets generated */
 	u_long	ips_badfrags;		/* malformed fragments (bad length) */
 	u_long	ips_rcvmemdrop;		/* frags dropped for lack of memory */
+	u_long	ips_toolong;		/* ip length > max ip packet size */
 };
 
 #ifdef _KERNEL
diff --git a/sys/netinet/raw_ip.c b/sys/netinet/raw_ip.c
index aaedb610567..97d641fddb4 100644
--- a/sys/netinet/raw_ip.c
+++ b/sys/netinet/raw_ip.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: raw_ip.c,v 1.7 1996/08/14 20:19:20 deraadt Exp $	*/
+/*	$OpenBSD: raw_ip.c,v 1.8 1997/01/26 01:23:44 tholo Exp $	*/
 /*	$NetBSD: raw_ip.c,v 1.25 1996/02/18 18:58:33 christos Exp $	*/
 
 /*
@@ -171,6 +171,10 @@ rip_output(m, va_alist)
 	 * Otherwise, allocate an mbuf for a header and fill it in.
 	 */
 	if ((inp->inp_flags & INP_HDRINCL) == 0) {
+		if ((m->m_pkthdr.len + sizeof(struct ip)) > IP_MAXPACKET) {
+			m_freem(m);
+			return (EMSGSIZE);
+		}
 		M_PREPEND(m, sizeof(struct ip), M_WAIT);
 		ip = mtod(m, struct ip *);
 		ip->ip_tos = 0;
@@ -181,6 +185,10 @@ rip_output(m, va_alist)
 		ip->ip_dst.s_addr = dst;
 		ip->ip_ttl = MAXTTL;
 	} else {
+		if (m->m_pkthdr.len > IP_MAXPACKET) {
+			m_freem(m);
+			return (EMSGSIZE);
+		}
 		ip = mtod(m, struct ip *);
 		/*
 		 * don't allow both user specified and setsockopt options,
diff --git a/sys/netinet/udp.h b/sys/netinet/udp.h
index c7964dfd30f..95bc044f7d9 100644
--- a/sys/netinet/udp.h
+++ b/sys/netinet/udp.h
@@ -42,6 +42,6 @@
 struct udphdr {
 	u_int16_t uh_sport;		/* source port */
 	u_int16_t uh_dport;		/* destination port */
-	int16_t	  uh_ulen;		/* udp length */
+	u_int16_t uh_ulen;		/* udp length */
 	u_int16_t uh_sum;		/* udp checksum */
 };
diff --git a/sys/netinet/udp_usrreq.c b/sys/netinet/udp_usrreq.c
index f78e4be2d7f..31bdf858ac9 100644
--- a/sys/netinet/udp_usrreq.c
+++ b/sys/netinet/udp_usrreq.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: udp_usrreq.c,v 1.7 1996/07/05 20:42:18 deraadt Exp $	*/
+/*	$OpenBSD: udp_usrreq.c,v 1.8 1997/01/26 01:23:46 tholo Exp $	*/
 /*	$NetBSD: udp_usrreq.c,v 1.28 1996/03/16 23:54:03 christos Exp $	*/
 
 /*
@@ -461,6 +461,15 @@ udp_output(m, va_alist)
 	}
 
 	/*
+	 * Compute the packet length of the IP header, and
+	 * punt if the length looks bogus.
+	 */
+	if ((len + sizeof(struct udpiphdr)) > IP_MAXPACKET) {
+		error = EMSGSIZE;
+		goto release;
+	}
+
+	/*
 	 * Fill in mbuf with extended UDP header
 	 * and addresses and length put into network format.
 	 */