[PATCH net-next v2 1/8] ipv4: cipso: Simplify IP options handling in cipso_v4_error()

[Ido Schimmel <idosch@nvidia.com>]

When __ip_options_compile() is called with an skb, the IP options are
parsed from the skb data into the provided IP option argument. This is
in contrast to the case where the skb argument is NULL and the options
are parsed from opt->__data.

Given that cipso_v4_error() always passes an skb to
__ip_options_compile(), there is no need to allocate an extra 40 bytes
(maximum IP options size).

Therefore, simplify the function by removing these extra bytes and make
the function similar to ipv4_send_dest_unreach() which also calls both
__ip_options_compile() and __icmp_send().

This is a preparation for changing the arguments being passed to
__icmp_send().

No functional changes intended.

Reviewed-by: Petr Machata <petrm@nvidia.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Acked-by: Paul Moore <paul@paul-moore.com>
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
---
 net/ipv4/cipso_ipv4.c | 13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/net/ipv4/cipso_ipv4.c b/net/ipv4/cipso_ipv4.c
index 740af8541d2f..c7c949c37e2d 100644
--- a/net/ipv4/cipso_ipv4.c
+++ b/net/ipv4/cipso_ipv4.c
@@ -1715,8 +1715,7 @@ int cipso_v4_validate(const struct sk_buff *skb, unsigned char **option)
  */
 void cipso_v4_error(struct sk_buff *skb, int error, u32 gateway)
 {
-	unsigned char optbuf[sizeof(struct ip_options) + 40];
-	struct ip_options *opt = (struct ip_options *)optbuf;
+	struct ip_options opt;
 	int res;
 
 	if (ip_hdr(skb)->protocol == IPPROTO_ICMP || error != -EACCES)
@@ -1727,19 +1726,19 @@ void cipso_v4_error(struct sk_buff *skb, int error, u32 gateway)
 	 * so we can not use icmp_send and IPCB here.
 	 */
 
-	memset(opt, 0, sizeof(struct ip_options));
-	opt->optlen = ip_hdr(skb)->ihl*4 - sizeof(struct iphdr);
+	memset(&opt, 0, sizeof(opt));
+	opt.optlen = ip_hdr(skb)->ihl * 4 - sizeof(struct iphdr);
 	rcu_read_lock();
-	res = __ip_options_compile(dev_net(skb->dev), opt, skb, NULL);
+	res = __ip_options_compile(dev_net(skb->dev), &opt, skb, NULL);
 	rcu_read_unlock();
 
 	if (res)
 		return;
 
 	if (gateway)
-		__icmp_send(skb, ICMP_DEST_UNREACH, ICMP_NET_ANO, 0, opt);
+		__icmp_send(skb, ICMP_DEST_UNREACH, ICMP_NET_ANO, 0, &opt);
 	else
-		__icmp_send(skb, ICMP_DEST_UNREACH, ICMP_HOST_ANO, 0, opt);
+		__icmp_send(skb, ICMP_DEST_UNREACH, ICMP_HOST_ANO, 0, &opt);
 }
 
 /**
-- 
2.51.0