cls_flow: add sanity check for the packet length

The packet length should be checked before the packet data is dereferenced.

Signed-off-by: Changli Gao <xiaosuo@gmail.com>
Acked-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 56 insertions, 40 deletions

diff --git a/net/sched/cls_flow.c b/net/sched/cls_flow.c
index f73542d2cdd0..e17096e3913c 100644
--- a/net/sched/cls_flow.c
+++ b/net/sched/cls_flow.c
@@ -65,37 +65,47 @@ static inline u32 addr_fold(void *addr)
         return (a & 0xFFFFFFFF) ^ (BITS_PER_LONG > 32 ? a >> 32 : 0);
 }
 
-static u32 flow_get_src(const struct sk_buff *skb)
+static u32 flow_get_src(struct sk_buff *skb)
 {
         switch (skb->protocol) {
         case htons(ETH_P_IP):
-                return ntohl(ip_hdr(skb)->saddr);
+                if (pskb_network_may_pull(skb, sizeof(struct iphdr)))
+                        return ntohl(ip_hdr(skb)->saddr);
+                break;
         case htons(ETH_P_IPV6):
-                return ntohl(ipv6_hdr(skb)->saddr.s6_addr32[3]);
-        default:
-                return addr_fold(skb->sk);
+                if (pskb_network_may_pull(skb, sizeof(struct ipv6hdr)))
+                        return ntohl(ipv6_hdr(skb)->saddr.s6_addr32[3]);
+                break;
         }
+
+        return addr_fold(skb->sk);
 }
 
-static u32 flow_get_dst(const struct sk_buff *skb)
+static u32 flow_get_dst(struct sk_buff *skb)
 {
         switch (skb->protocol) {
         case htons(ETH_P_IP):
-                return ntohl(ip_hdr(skb)->daddr);
+                if (pskb_network_may_pull(skb, sizeof(struct iphdr)))
+                        return ntohl(ip_hdr(skb)->daddr);
+                break;
         case htons(ETH_P_IPV6):
-                return ntohl(ipv6_hdr(skb)->daddr.s6_addr32[3]);
-        default:
-                return addr_fold(skb_dst(skb)) ^ (__force u16)skb->protocol;
+                if (pskb_network_may_pull(skb, sizeof(struct ipv6hdr)))
+                        return ntohl(ipv6_hdr(skb)->daddr.s6_addr32[3]);
+                break;
         }
+
+        return addr_fold(skb_dst(skb)) ^ (__force u16)skb->protocol;
 }
 
-static u32 flow_get_proto(const struct sk_buff *skb)
+static u32 flow_get_proto(struct sk_buff *skb)
 {
         switch (skb->protocol) {
         case htons(ETH_P_IP):
-                return ip_hdr(skb)->protocol;
+                return pskb_network_may_pull(skb, sizeof(struct iphdr)) ?
+                       ip_hdr(skb)->protocol : 0;
         case htons(ETH_P_IPV6):
-                return ipv6_hdr(skb)->nexthdr;
+                return pskb_network_may_pull(skb, sizeof(struct ipv6hdr)) ?
+                       ipv6_hdr(skb)->nexthdr : 0;
         default:
                 return 0;
         }
@@ -116,58 +126,64 @@ static int has_ports(u8 protocol)
         }
 }
 
-static u32 flow_get_proto_src(const struct sk_buff *skb)
+static u32 flow_get_proto_src(struct sk_buff *skb)
 {
-        u32 res = 0;
-
         switch (skb->protocol) {
         case htons(ETH_P_IP): {
-                struct iphdr *iph = ip_hdr(skb);
+                struct iphdr *iph;
 
+                if (!pskb_network_may_pull(skb, sizeof(*iph)))
+                        break;
+                iph = ip_hdr(skb);
                 if (!(iph->frag_off&htons(IP_MF|IP_OFFSET)) &&
-                    has_ports(iph->protocol))
-                        res = ntohs(*(__be16 *)((void *)iph + iph->ihl * 4));
+                    has_ports(iph->protocol) &&
+                    pskb_network_may_pull(skb, iph->ihl * 4 + 2))
+                        return ntohs(*(__be16 *)((void *)iph + iph->ihl * 4));
                 break;
         }
         case htons(ETH_P_IPV6): {
-                struct ipv6hdr *iph = ipv6_hdr(skb);
+                struct ipv6hdr *iph;
 
+                if (!pskb_network_may_pull(skb, sizeof(*iph) + 2))
+                        break;
+                iph = ipv6_hdr(skb);
                 if (has_ports(iph->nexthdr))
-                        res = ntohs(*(__be16 *)&iph[1]);
+                        return ntohs(*(__be16 *)&iph[1]);
                 break;
         }
-        default:
-                res = addr_fold(skb->sk);
         }
 
-        return res;
+        return addr_fold(skb->sk);
 }
 
-static u32 flow_get_proto_dst(const struct sk_buff *skb)
+static u32 flow_get_proto_dst(struct sk_buff *skb)
 {
-        u32 res = 0;
-
         switch (skb->protocol) {
         case htons(ETH_P_IP): {
-                struct iphdr *iph = ip_hdr(skb);
+                struct iphdr *iph;
 
+                if (!pskb_network_may_pull(skb, sizeof(*iph)))
+                        break;
+                iph = ip_hdr(skb);
                 if (!(iph->frag_off&htons(IP_MF|IP_OFFSET)) &&
-                    has_ports(iph->protocol))
-                        res = ntohs(*(__be16 *)((void *)iph + iph->ihl * 4 + 2));
+                    has_ports(iph->protocol) &&
+                    pskb_network_may_pull(skb, iph->ihl * 4 + 4))
+                        return ntohs(*(__be16 *)((void *)iph + iph->ihl * 4 + 2));
                 break;
         }
         case htons(ETH_P_IPV6): {
-                struct ipv6hdr *iph = ipv6_hdr(skb);
+                struct ipv6hdr *iph;
 
+                if (!pskb_network_may_pull(skb, sizeof(*iph) + 4))
+                        break;
+                iph = ipv6_hdr(skb);
                 if (has_ports(iph->nexthdr))
-                        res = ntohs(*(__be16 *)((void *)&iph[1] + 2));
+                        return ntohs(*(__be16 *)((void *)&iph[1] + 2));
                 break;
         }
-        default:
-                res = addr_fold(skb_dst(skb)) ^ (__force u16)skb->protocol;
         }
 
-        return res;
+        return addr_fold(skb_dst(skb)) ^ (__force u16)skb->protocol;
 }
 
 static u32 flow_get_iif(const struct sk_buff *skb)
@@ -211,7 +227,7 @@ static u32 flow_get_nfct(const struct sk_buff *skb)
 })
 #endif
 
-static u32 flow_get_nfct_src(const struct sk_buff *skb)
+static u32 flow_get_nfct_src(struct sk_buff *skb)
 {
         switch (skb->protocol) {
         case htons(ETH_P_IP):
@@ -223,7 +239,7 @@ fallback:
         return flow_get_src(skb);
 }
 
-static u32 flow_get_nfct_dst(const struct sk_buff *skb)
+static u32 flow_get_nfct_dst(struct sk_buff *skb)
 {
         switch (skb->protocol) {
         case htons(ETH_P_IP):
@@ -235,14 +251,14 @@ fallback:
         return flow_get_dst(skb);
 }
 
-static u32 flow_get_nfct_proto_src(const struct sk_buff *skb)
+static u32 flow_get_nfct_proto_src(struct sk_buff *skb)
 {
         return ntohs(CTTUPLE(skb, src.u.all));
 fallback:
         return flow_get_proto_src(skb);
 }
 
-static u32 flow_get_nfct_proto_dst(const struct sk_buff *skb)
+static u32 flow_get_nfct_proto_dst(struct sk_buff *skb)
 {
         return ntohs(CTTUPLE(skb, dst.u.all));
 fallback:
@@ -281,7 +297,7 @@ static u32 flow_get_vlan_tag(const struct sk_buff *skb)
         return tag & VLAN_VID_MASK;
 }
 
-static u32 flow_key_get(const struct sk_buff *skb, int key)
+static u32 flow_key_get(struct sk_buff *skb, int key)
 {
         switch (key) {
         case FLOW_KEY_SRC: