[NETFILTER]: Linearize iptables matches.

Adjusts the IPTables matches to handle non-linear packets.
Untested: ipt_ah and ipt_esp.

net/ipv4/netfilter/ipt_ah.c

@@ -35,14 +35,16 @@ match(const struct sk_buff *skb,
       const struct net_device *out,
       const void *matchinfo,
       int offset,
-      const void *hdr,
-      u_int16_t datalen,
       int *hotdrop)
 {
-	const struct ahhdr *ah = hdr;
+	struct ahhdr ah;
 	const struct ipt_ah *ahinfo = matchinfo;
 
-	if (offset == 0 && datalen < sizeof(struct ahhdr)) {
+	/* Must not be a fragment. */
+	if (offset)
+		return 0;
+
+	if (skb_copy_bits(skb, skb->nh.iph->ihl*4, &ah, sizeof(ah)) < 0) {
 		/* We've been asked to examine this packet, and we
 		   can't.  Hence, no choice but to drop. */
 		duprintf("Dropping evil AH tinygram.\n");
@@ -50,10 +52,8 @@ match(const struct sk_buff *skb,
 		return 0;
 	}
 
-	/* Must not be a fragment. */
-	return !offset
-		&& spi_match(ahinfo->spis[0], ahinfo->spis[1],
-			      ntohl(ah->spi),
+	return spi_match(ahinfo->spis[0], ahinfo->spis[1],
+			 ntohl(ah.spi),
 			 !!(ahinfo->invflags & IPT_AH_INV_SPI));
 }
 

net/ipv4/netfilter/ipt_conntrack.c

@@ -14,8 +14,6 @@ match(const struct sk_buff *skb,
       const struct net_device *out,
       const void *matchinfo,
       int offset,
-      const void *hdr,
-      u_int16_t datalen,
       int *hotdrop)
 {
 	const struct ipt_conntrack_info *sinfo = matchinfo;

net/ipv4/netfilter/ipt_dscp.c

@@ -19,8 +19,7 @@ MODULE_LICENSE("GPL");
 
 static int match(const struct sk_buff *skb, const struct net_device *in,
 		 const struct net_device *out, const void *matchinfo,
-		 int offset, const void *hdr, u_int16_t datalen,
-		 int *hotdrop)
+		 int offset, int *hotdrop)
 {
 	const struct ipt_dscp_info *info = matchinfo;
 	const struct iphdr *iph = skb->nh.iph;

net/ipv4/netfilter/ipt_ecn.c

@@ -19,34 +19,40 @@ MODULE_DESCRIPTION("IP tables ECN matching module");
 MODULE_LICENSE("GPL");
 
 static inline int match_ip(const struct sk_buff *skb,
-			   const struct iphdr *iph,
 			   const struct ipt_ecn_info *einfo)
 {
-	return ((iph->tos&IPT_ECN_IP_MASK) == einfo->ip_ect);
+	return ((skb->nh.iph->tos&IPT_ECN_IP_MASK) == einfo->ip_ect);
 }
 
 static inline int match_tcp(const struct sk_buff *skb,
-			    const struct iphdr *iph,
-			    const struct ipt_ecn_info *einfo)
+			    const struct ipt_ecn_info *einfo,
+			    int *hotdrop)
 {
-	struct tcphdr *tcph = (void *)iph + iph->ihl*4;
+	struct tcphdr tcph;
+
+	/* In practice, TCP match does this, so can't fail.  But let's
+           be good citizens. */
+	if (skb_copy_bits(skb, skb->nh.iph->ihl*4, &tcph, sizeof(tcph)) < 0) {
+		*hotdrop = 0;
+		return 0;
+	}
 
 	if (einfo->operation & IPT_ECN_OP_MATCH_ECE) {
 		if (einfo->invert & IPT_ECN_OP_MATCH_ECE) {
-			if (tcph->ece == 1)
+			if (tcph.ece == 1)
 				return 0;
 		} else {
-			if (tcph->ece == 0)
+			if (tcph.ece == 0)
 				return 0;
 		}
 	}
 
 	if (einfo->operation & IPT_ECN_OP_MATCH_CWR) {
 		if (einfo->invert & IPT_ECN_OP_MATCH_CWR) {
-			if (tcph->cwr == 1)
+			if (tcph.cwr == 1)
 				return 0;
 		} else {
-			if (tcph->cwr == 0)
+			if (tcph.cwr == 0)
 				return 0;
 		}
 	}
@@ -56,20 +62,18 @@ static inline int match_tcp(const struct sk_buff *skb,
 
 static int match(const struct sk_buff *skb, const struct net_device *in,
 		 const struct net_device *out, const void *matchinfo,
-		 int offset, const void *hdr, u_int16_t datalen,
-		 int *hotdrop)
+		 int offset, int *hotdrop)
 {
 	const struct ipt_ecn_info *info = matchinfo;
-	const struct iphdr *iph = skb->nh.iph;
 
 	if (info->operation & IPT_ECN_OP_MATCH_IP)
-		if (!match_ip(skb, iph, info))
+		if (!match_ip(skb, info))
 			return 0;
 
 	if (info->operation & (IPT_ECN_OP_MATCH_ECE|IPT_ECN_OP_MATCH_CWR)) {
-		if (iph->protocol != IPPROTO_TCP)
+		if (skb->nh.iph->protocol != IPPROTO_TCP)
 			return 0;
-		if (!match_tcp(skb, iph, info))
+		if (!match_tcp(skb, info, hotdrop))
 			return 0;
 	}
 

net/ipv4/netfilter/ipt_esp.c

@@ -35,14 +35,16 @@ match(const struct sk_buff *skb,
       const struct net_device *out,
       const void *matchinfo,
       int offset,
-      const void *hdr,
-      u_int16_t datalen,
       int *hotdrop)
 {
-	const struct esphdr *esp = hdr;
+	struct esphdr esp;
 	const struct ipt_esp *espinfo = matchinfo;
 
-	if (offset == 0 && datalen < sizeof(struct esphdr)) {
+	/* Must not be a fragment. */
+	if (offset)
+		return 0;
+
+	if (skb_copy_bits(skb, skb->nh.iph->ihl*4, &esp, sizeof(esp)) < 0) {
 		/* We've been asked to examine this packet, and we
 		   can't.  Hence, no choice but to drop. */
 		duprintf("Dropping evil ESP tinygram.\n");
@@ -50,10 +52,8 @@ match(const struct sk_buff *skb,
 		return 0;
 	}
 
-	/* Must not be a fragment. */
-	return !offset
-		&& spi_match(espinfo->spis[0], espinfo->spis[1],
-			      ntohl(esp->spi),
+	return spi_match(espinfo->spis[0], espinfo->spis[1],
+			 ntohl(esp.spi),
 			 !!(espinfo->invflags & IPT_ESP_INV_SPI));
 }
 

net/ipv4/netfilter/ipt_helper.c

@@ -28,8 +28,6 @@ match(const struct sk_buff *skb,
       const struct net_device *out,
       const void *matchinfo,
       int offset,
-      const void *hdr,
-      u_int16_t datalen,
       int *hotdrop)
 {
 	const struct ipt_helper_info *info = matchinfo;

net/ipv4/netfilter/ipt_length.c

@@ -15,8 +15,6 @@ match(const struct sk_buff *skb,
       const struct net_device *out,
       const void *matchinfo,
       int offset,
-      const void *hdr,
-      u_int16_t datalen,
       int *hotdrop)
 {
 	const struct ipt_length_info *info = matchinfo;

net/ipv4/netfilter/ipt_limit.c

@@ -47,8 +47,6 @@ ipt_limit_match(const struct sk_buff *skb,
 		const struct net_device *out,
 		const void *matchinfo,
 		int offset,
-		const void *hdr,
-		u_int16_t datalen,
 		int *hotdrop)
 {
 	struct ipt_rateinfo *r = ((struct ipt_rateinfo *)matchinfo)->master;

net/ipv4/netfilter/ipt_mac.c

@@ -12,8 +12,6 @@ match(const struct sk_buff *skb,
       const struct net_device *out,
       const void *matchinfo,
       int offset,
-      const void *hdr,
-      u_int16_t datalen,
       int *hotdrop)
 {
     const struct ipt_mac_info *info = matchinfo;

net/ipv4/netfilter/ipt_mark.c

@@ -11,8 +11,6 @@ match(const struct sk_buff *skb,
       const struct net_device *out,
       const void *matchinfo,
       int offset,
-      const void *hdr,
-      u_int16_t datalen,
       int *hotdrop)
 {
 	const struct ipt_mark_info *info = matchinfo;

net/ipv4/netfilter/ipt_multiport.c

@@ -39,15 +39,18 @@ match(const struct sk_buff *skb,
       const struct net_device *out,
       const void *matchinfo,
       int offset,
-      const void *hdr,
-      u_int16_t datalen,
       int *hotdrop)
 {
-	const struct udphdr *udp = hdr;
+	u16 ports[2];
 	const struct ipt_multiport *multiinfo = matchinfo;
 
-	/* Must be big enough to read ports. */
-	if (offset == 0 && datalen < sizeof(struct udphdr)) {
+	/* Must not be a fragment. */
+	if (offset)
+		return 0;
+
+	/* Must be big enough to read ports (both UDP and TCP have
+           them at the start). */
+	if (skb_copy_bits(skb, skb->nh.iph->ihl*4, ports, sizeof(ports)) < 0) {
 		/* We've been asked to examine this packet, and we
 		   can't.  Hence, no choice but to drop. */
 			duprintf("ipt_multiport:"
@@ -56,11 +59,9 @@ match(const struct sk_buff *skb,
 			return 0;
 	}
 
-	/* Must not be a fragment. */
-	return !offset
-		&& ports_match(multiinfo->ports,
+	return ports_match(multiinfo->ports,
 			   multiinfo->flags, multiinfo->count,
-			       ntohs(udp->source), ntohs(udp->dest));
+			   ntohs(ports[0]), ntohs(ports[1]));
 }
 
 /* Called when user tries to insert an entry of this type. */

net/ipv4/netfilter/ipt_owner.c

@@ -115,8 +115,6 @@ match(const struct sk_buff *skb,
       const struct net_device *out,
       const void *matchinfo,
       int offset,
-      const void *hdr,
-      u_int16_t datalen,
       int *hotdrop)
 {
 	const struct ipt_owner_info *info = matchinfo;
@@ -170,8 +168,11 @@ checkentry(const char *tablename,
                 return 0;
         }
 
-	if (matchsize != IPT_ALIGN(sizeof(struct ipt_owner_info)))
+	if (matchsize != IPT_ALIGN(sizeof(struct ipt_owner_info))) {
+		printk("Matchsize %u != %u\n", matchsize,
+		       IPT_ALIGN(sizeof(struct ipt_owner_info)));
 		return 0;
+	}
 
 	return 1;
 }

net/ipv4/netfilter/ipt_pkttype.c

@@ -13,8 +13,6 @@ static int match(const struct sk_buff *skb,
       const struct net_device *out,
       const void *matchinfo,
       int offset,
-      const void *hdr,
-      u_int16_t datalen,
       int *hotdrop)
 {
     const struct ipt_pkttype_info *info = matchinfo;

net/ipv4/netfilter/ipt_state.c

@@ -13,8 +13,6 @@ match(const struct sk_buff *skb,
       const struct net_device *out,
       const void *matchinfo,
       int offset,
-      const void *hdr,
-      u_int16_t datalen,
       int *hotdrop)
 {
 	const struct ipt_state_info *sinfo = matchinfo;

net/ipv4/netfilter/ipt_tcpmss.c

@@ -11,24 +11,32 @@
 /* Returns 1 if the mss option is set and matched by the range, 0 otherwise */
 static inline int
 mssoption_match(u_int16_t min, u_int16_t max,
-		const struct tcphdr *tcp,
-		u_int16_t datalen,
+		const struct sk_buff *skb,
 		int invert,
 		int *hotdrop)
 {
-	unsigned int i;
-	const u_int8_t *opt = (u_int8_t *)tcp;
+	struct tcphdr tcph;
+	/* tcp.doff is only 4 bits, ie. max 15 * 4 bytes */
+	u8 opt[15 * 4 - sizeof(tcph)];
+	unsigned int i, optlen;
 
 	/* If we don't have the whole header, drop packet. */
-	if (tcp->doff * 4 > datalen) {
-		*hotdrop = 1;
-		return 0;
-	}
-
-	for (i = sizeof(struct tcphdr); i < tcp->doff * 4; ) {
-		if ((opt[i] == TCPOPT_MSS)
-		    && ((tcp->doff * 4 - i) >= TCPOLEN_MSS)
-		    && (opt[i+1] == TCPOLEN_MSS)) {
+	if (skb_copy_bits(skb, skb->nh.iph->ihl*4, &tcph, sizeof(tcph)) < 0)
+		goto dropit;
+
+	/* Malformed. */
+	if (tcph.doff*4 < sizeof(tcph))
+		goto dropit;
+
+	optlen = tcph.doff*4 - sizeof(tcph);
+	/* Truncated options. */
+	if (skb_copy_bits(skb, skb->nh.iph->ihl*4+sizeof(tcph), opt, optlen)<0)
+		goto dropit;
+
+	for (i = 0; i < optlen; ) {
+		if (opt[i] == TCPOPT_MSS
+		    && (optlen - i) >= TCPOLEN_MSS
+		    && opt[i+1] == TCPOLEN_MSS) {
 			u_int16_t mssval;
 
 			mssval = (opt[i+2] << 8) | opt[i+3];
@@ -38,8 +46,11 @@ mssoption_match(u_int16_t min, u_int16_t max,
 		if (opt[i] < 2) i++;
 		else i += opt[i+1]?:1;
 	}
-
 	return invert;
+
+ dropit:
+	*hotdrop = 1;
+	return 0;
 }
 
 static int
@@ -48,15 +59,11 @@ match(const struct sk_buff *skb,
       const struct net_device *out,
       const void *matchinfo,
       int offset,
-      const void *hdr,
-      u_int16_t datalen,
       int *hotdrop)
 {
 	const struct ipt_tcpmss_match_info *info = matchinfo;
-	const struct tcphdr *tcph = (void *)skb->nh.iph + skb->nh.iph->ihl*4;
 
-	return mssoption_match(info->mss_min, info->mss_max, tcph,
-			       skb->len - skb->nh.iph->ihl*4,
+	return mssoption_match(info->mss_min, info->mss_max, skb,
 			       info->invert, hotdrop);
 }
 

net/ipv4/netfilter/ipt_tos.c

@@ -11,14 +11,11 @@ match(const struct sk_buff *skb,
       const struct net_device *out,
       const void *matchinfo,
       int offset,
-      const void *hdr,
-      u_int16_t datalen,
       int *hotdrop)
 {
 	const struct ipt_tos_info *info = matchinfo;
-	const struct iphdr *iph = skb->nh.iph;
 
-	return (iph->tos == info->tos) ^ info->invert;
+	return (skb->nh.iph->tos == info->tos) ^ info->invert;
 }
 
 static int

net/ipv4/netfilter/ipt_ttl.c

@@ -19,24 +19,22 @@ MODULE_LICENSE("GPL");
 
 static int match(const struct sk_buff *skb, const struct net_device *in,
 		 const struct net_device *out, const void *matchinfo,
-		 int offset, const void *hdr, u_int16_t datalen,
-		 int *hotdrop)
+		 int offset, int *hotdrop)
 {
 	const struct ipt_ttl_info *info = matchinfo;
-	const struct iphdr *iph = skb->nh.iph;
 
 	switch (info->mode) {
 		case IPT_TTL_EQ:
-			return (iph->ttl == info->ttl);
+			return (skb->nh.iph->ttl == info->ttl);
 			break;
 		case IPT_TTL_NE:
-			return (!(iph->ttl == info->ttl));
+			return (!(skb->nh.iph->ttl == info->ttl));
 			break;
 		case IPT_TTL_LT:
-			return (iph->ttl < info->ttl);
+			return (skb->nh.iph->ttl < info->ttl);
 			break;
 		case IPT_TTL_GT:
-			return (iph->ttl > info->ttl);
+			return (skb->nh.iph->ttl > info->ttl);
 			break;
 		default:
 			printk(KERN_WARNING "ipt_ttl: unknown mode %d\n",