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Message-Id: <20250427061706.391920-1-wdhh6@aliyun.com>
Date: Sun, 27 Apr 2025 14:17:06 +0800
From: Chaohai Chen <wdhh6@...yun.com>
To: davem@...emloft.net,
edumazet@...gle.com,
kuba@...nel.org,
pabeni@...hat.com,
horms@...nel.org,
steffen.klassert@...unet.com,
herbert@...dor.apana.org.au,
paul@...l-moore.com,
pablo@...filter.org,
kadlec@...filter.org,
netdev@...r.kernel.org
Cc: linux-kernel@...r.kernel.org,
linux-security-module@...r.kernel.org,
netfilter-devel@...r.kernel.org,
coreteam@...filter.org,
Chaohai Chen <wdhh6@...yun.com>
Subject: [PATCH] net:ipv4: Use shift left 2 to calculate the length of the IPv4 header.
Encapsulate the IPV4_HEADER_LEN macro and use shift left 2 to calculate
the length of the IPv4 header instead of multiplying 4 everywhere.
Signed-off-by: Chaohai Chen <wdhh6@...yun.com>
---
include/net/ip.h | 2 ++
net/ipv4/ah4.c | 8 ++++----
net/ipv4/cipso_ipv4.c | 4 ++--
net/ipv4/ip_input.c | 8 ++++----
net/ipv4/netfilter/nf_reject_ipv4.c | 4 ++--
5 files changed, 14 insertions(+), 12 deletions(-)
diff --git a/include/net/ip.h b/include/net/ip.h
index ba7b43447775..0fa172d73a52 100644
--- a/include/net/ip.h
+++ b/include/net/ip.h
@@ -38,6 +38,8 @@
#define IPV4_MAX_PMTU 65535U /* RFC 2675, Section 5.1 */
#define IPV4_MIN_MTU 68 /* RFC 791 */
+#define IPV4_HEADER_LEN(ihl) (ihl << 2)
+
extern unsigned int sysctl_fib_sync_mem;
extern unsigned int sysctl_fib_sync_mem_min;
extern unsigned int sysctl_fib_sync_mem_max;
diff --git a/net/ipv4/ah4.c b/net/ipv4/ah4.c
index 64aec3dff8ec..d09e07408c2e 100644
--- a/net/ipv4/ah4.c
+++ b/net/ipv4/ah4.c
@@ -77,7 +77,7 @@ static inline struct scatterlist *ah_req_sg(struct crypto_ahash *ahash,
static int ip_clear_mutable_options(const struct iphdr *iph, __be32 *daddr)
{
unsigned char *optptr = (unsigned char *)(iph+1);
- int l = iph->ihl*4 - sizeof(struct iphdr);
+ int l = IPV4_HEADER_LEN(iph->ihl) - sizeof(struct iphdr);
int optlen;
while (l > 0) {
@@ -134,7 +134,7 @@ static void ah_output_done(void *data, int err)
top_iph->frag_off = iph->frag_off;
if (top_iph->ihl != 5) {
top_iph->daddr = iph->daddr;
- memcpy(top_iph+1, iph+1, top_iph->ihl*4 - sizeof(struct iphdr));
+ memcpy(top_iph + 1, iph + 1, IPV4_HEADER_LEN(top_iph->ihl) - sizeof(struct iphdr));
}
kfree(AH_SKB_CB(skb)->tmp);
@@ -194,7 +194,7 @@ static int ah_output(struct xfrm_state *x, struct sk_buff *skb)
if (top_iph->ihl != 5) {
iph->daddr = top_iph->daddr;
- memcpy(iph+1, top_iph+1, top_iph->ihl*4 - sizeof(struct iphdr));
+ memcpy(iph + 1, top_iph + 1, IPV4_HEADER_LEN(top_iph->ihl) - sizeof(struct iphdr));
err = ip_clear_mutable_options(top_iph, &top_iph->daddr);
if (err)
goto out_free;
@@ -250,7 +250,7 @@ static int ah_output(struct xfrm_state *x, struct sk_buff *skb)
top_iph->frag_off = iph->frag_off;
if (top_iph->ihl != 5) {
top_iph->daddr = iph->daddr;
- memcpy(top_iph+1, iph+1, top_iph->ihl*4 - sizeof(struct iphdr));
+ memcpy(top_iph + 1, iph + 1, IPV4_HEADER_LEN(top_iph->ihl) - sizeof(struct iphdr));
}
out_free:
diff --git a/net/ipv4/cipso_ipv4.c b/net/ipv4/cipso_ipv4.c
index 740af8541d2f..9134d31bd64b 100644
--- a/net/ipv4/cipso_ipv4.c
+++ b/net/ipv4/cipso_ipv4.c
@@ -1501,7 +1501,7 @@ unsigned char *cipso_v4_optptr(const struct sk_buff *skb)
int optlen;
int taglen;
- for (optlen = iph->ihl*4 - sizeof(struct iphdr); optlen > 1; ) {
+ for (optlen = IPV4_HEADER_LEN(iph->ihl) - sizeof(struct iphdr); optlen > 1; ) {
switch (optptr[0]) {
case IPOPT_END:
return NULL;
@@ -1728,7 +1728,7 @@ void cipso_v4_error(struct sk_buff *skb, int error, u32 gateway)
*/
memset(opt, 0, sizeof(struct ip_options));
- opt->optlen = ip_hdr(skb)->ihl*4 - sizeof(struct iphdr);
+ opt->optlen = IPV4_HEADER_LEN(ip_hdr(skb)->ihl) - sizeof(struct iphdr);
rcu_read_lock();
res = __ip_options_compile(dev_net(skb->dev), opt, skb, NULL);
rcu_read_unlock();
diff --git a/net/ipv4/ip_input.c b/net/ipv4/ip_input.c
index 30a5e9460d00..235553f50b6c 100644
--- a/net/ipv4/ip_input.c
+++ b/net/ipv4/ip_input.c
@@ -276,7 +276,7 @@ static inline bool ip_rcv_options(struct sk_buff *skb, struct net_device *dev)
iph = ip_hdr(skb);
opt = &(IPCB(skb)->opt);
- opt->optlen = iph->ihl*4 - sizeof(struct iphdr);
+ opt->optlen = IPV4_HEADER_LEN(iph->ihl) - sizeof(struct iphdr);
if (ip_options_compile(dev_net(dev), opt, skb)) {
__IP_INC_STATS(dev_net(dev), IPSTATS_MIB_INHDRERRORS);
@@ -501,7 +501,7 @@ static struct sk_buff *ip_rcv_core(struct sk_buff *skb, struct net *net)
IPSTATS_MIB_NOECTPKTS + (iph->tos & INET_ECN_MASK),
max_t(unsigned short, 1, skb_shinfo(skb)->gso_segs));
- if (!pskb_may_pull(skb, iph->ihl*4))
+ if (!pskb_may_pull(skb, IPV4_HEADER_LEN(iph->ihl)))
goto inhdr_error;
iph = ip_hdr(skb);
@@ -514,7 +514,7 @@ static struct sk_buff *ip_rcv_core(struct sk_buff *skb, struct net *net)
drop_reason = SKB_DROP_REASON_PKT_TOO_SMALL;
__IP_INC_STATS(net, IPSTATS_MIB_INTRUNCATEDPKTS);
goto drop;
- } else if (len < (iph->ihl*4))
+ } else if (len < IPV4_HEADER_LEN(iph->ihl))
goto inhdr_error;
/* Our transport medium may have padded the buffer out. Now we know it
@@ -527,7 +527,7 @@ static struct sk_buff *ip_rcv_core(struct sk_buff *skb, struct net *net)
}
iph = ip_hdr(skb);
- skb->transport_header = skb->network_header + iph->ihl*4;
+ skb->transport_header = skb->network_header + IPV4_HEADER_LEN(iph->ihl);
/* Remove any debris in the socket control block */
memset(IPCB(skb), 0, sizeof(struct inet_skb_parm));
diff --git a/net/ipv4/netfilter/nf_reject_ipv4.c b/net/ipv4/netfilter/nf_reject_ipv4.c
index 87fd945a0d27..ec2d8d93c241 100644
--- a/net/ipv4/netfilter/nf_reject_ipv4.c
+++ b/net/ipv4/netfilter/nf_reject_ipv4.c
@@ -27,10 +27,10 @@ static int nf_reject_iphdr_validate(struct sk_buff *skb)
len = ntohs(iph->tot_len);
if (skb->len < len)
return 0;
- else if (len < (iph->ihl*4))
+ else if (len < IPV4_HEADER_LEN(iph->ihl))
return 0;
- if (!pskb_may_pull(skb, iph->ihl*4))
+ if (!pskb_may_pull(skb, IPV4_HEADER_LEN(iph->ihl)))
return 0;
return 1;
--
2.34.1
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