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Message-Id: <1280905687-8463-1-git-send-email-xiaosuo@gmail.com>
Date: Wed, 4 Aug 2010 15:08:07 +0800
From: Changli Gao <xiaosuo@...il.com>
To: Patrick McHardy <kaber@...sh.net>
Cc: Jamal Hadi Salim <hadi@...erus.ca>,
"David S. Miller" <davem@...emloft.net>, netdev@...r.kernel.org,
Changli Gao <xiaosuo@...il.com>
Subject: [PATCH] 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@...il.com>
---
include/linux/skbuff.h | 6 ++--
net/sched/cls_flow.c | 69 +++++++++++++++++++++++++++++++++----------------
2 files changed, 50 insertions(+), 25 deletions(-)
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index d20d9e7..3f0ac50 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -1210,12 +1210,12 @@ static inline unsigned char *pskb_pull(struct sk_buff *skb, unsigned int len)
return unlikely(len > skb->len) ? NULL : __pskb_pull(skb, len);
}
-static inline int pskb_may_pull(struct sk_buff *skb, unsigned int len)
+static inline bool pskb_may_pull(struct sk_buff *skb, unsigned int len)
{
if (likely(len <= skb_headlen(skb)))
- return 1;
+ return true;
if (unlikely(len > skb->len))
- return 0;
+ return false;
return __pskb_pull_tail(skb, len - skb_headlen(skb)) != NULL;
}
diff --git a/net/sched/cls_flow.c b/net/sched/cls_flow.c
index f73542d..d63a374 100644
--- a/net/sched/cls_flow.c
+++ b/net/sched/cls_flow.c
@@ -65,37 +65,48 @@ 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 inline bool flow_pskb_may_pull(struct sk_buff *skb, unsigned int len)
+{
+ return pskb_may_pull(skb, skb_network_offset(skb) + len);
+}
+
+static u32 flow_get_src(struct sk_buff *skb)
{
switch (skb->protocol) {
case htons(ETH_P_IP):
- return ntohl(ip_hdr(skb)->saddr);
+ return flow_pskb_may_pull(skb, sizeof(struct iphdr)) ?
+ ntohl(ip_hdr(skb)->saddr) : 0;
case htons(ETH_P_IPV6):
- return ntohl(ipv6_hdr(skb)->saddr.s6_addr32[3]);
+ return flow_pskb_may_pull(skb, sizeof(struct ipv6hdr)) ?
+ ntohl(ipv6_hdr(skb)->saddr.s6_addr32[3]) : 0;
default:
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);
+ return flow_pskb_may_pull(skb, sizeof(struct iphdr)) ?
+ ntohl(ip_hdr(skb)->daddr) : 0;
case htons(ETH_P_IPV6):
- return ntohl(ipv6_hdr(skb)->daddr.s6_addr32[3]);
+ return flow_pskb_may_pull(skb, sizeof(struct ipv6hdr)) ?
+ ntohl(ipv6_hdr(skb)->daddr.s6_addr32[3]) : 0;
default:
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 flow_pskb_may_pull(skb, sizeof(struct iphdr)) ?
+ ip_hdr(skb)->protocol : 0;
case htons(ETH_P_IPV6):
- return ipv6_hdr(skb)->nexthdr;
+ return flow_pskb_may_pull(skb, sizeof(struct ipv6hdr)) ?
+ ipv6_hdr(skb)->nexthdr : 0;
default:
return 0;
}
@@ -116,22 +127,29 @@ 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 (!flow_pskb_may_pull(skb, sizeof(*iph)))
+ break;
+ iph = ip_hdr(skb);
if (!(iph->frag_off&htons(IP_MF|IP_OFFSET)) &&
- has_ports(iph->protocol))
+ has_ports(iph->protocol) &&
+ flow_pskb_may_pull(skb, iph->ihl * 4 + 2))
res = ntohs(*(__be16 *)((void *)iph + iph->ihl * 4));
break;
}
case htons(ETH_P_IPV6): {
- struct ipv6hdr *iph = ipv6_hdr(skb);
+ struct ipv6hdr *iph;
+ if (!flow_pskb_may_pull(skb, sizeof(*iph) + 2))
+ break;
+ iph = ipv6_hdr(skb);
if (has_ports(iph->nexthdr))
res = ntohs(*(__be16 *)&iph[1]);
break;
@@ -143,22 +161,29 @@ static u32 flow_get_proto_src(const struct sk_buff *skb)
return res;
}
-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 (!flow_pskb_may_pull(skb, sizeof(*iph)))
+ break;
+ iph = ip_hdr(skb);
if (!(iph->frag_off&htons(IP_MF|IP_OFFSET)) &&
- has_ports(iph->protocol))
+ has_ports(iph->protocol) &&
+ flow_pskb_may_pull(skb, iph->ihl * 4 + 4))
res = ntohs(*(__be16 *)((void *)iph + iph->ihl * 4 + 2));
break;
}
case htons(ETH_P_IPV6): {
- struct ipv6hdr *iph = ipv6_hdr(skb);
+ struct ipv6hdr *iph;
+ if (!flow_pskb_may_pull(skb, sizeof(*iph) + 4))
+ break;
+ iph = ipv6_hdr(skb);
if (has_ports(iph->nexthdr))
res = ntohs(*(__be16 *)((void *)&iph[1] + 2));
break;
@@ -211,7 +236,7 @@ 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 +248,7 @@ 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 +260,14 @@ 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 +306,7 @@ 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:
--
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