[PATCH net-next 14/15] netfilter: nft_exthdr: remove redundant op parsing in tcp_set_init

[Pablo Neira Ayuso <pablo@netfilter.org>]

From: Fernando Fernandez Mancera <fmancera@suse.de>

The nft_exthdr_tcp_set_init() function is exclusively used for TCP
options. Therefore, parsing the NFTA_EXTHDR_OP attribute from user
space is redundant, as the operation type must always be
NFT_EXTHDR_OP_TCPOPT.

Remove the unnecessary netlink attribute parsing and hardcode priv->op
to NFT_EXTHDR_OP_TCPOPT, which simplifies the code and reduces the
object size.

./scripts/bloat-o-meter exthdr_before.o exthdr_after.o
add/remove: 0/0 grow/shrink: 0/1 up/down: 0/-54 (-54)
Function                                     old     new   delta
nft_exthdr_tcp_set_init                      412     358     -54
Total: Before=6581, After=6527, chg -0.82%

Signed-off-by: Fernando Fernandez Mancera <fmancera@suse.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
 net/netfilter/nft_exthdr.c | 8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/net/netfilter/nft_exthdr.c b/net/netfilter/nft_exthdr.c
index 8abf8e8145ce..3492426dccf7 100644
--- a/net/netfilter/nft_exthdr.c
+++ b/net/netfilter/nft_exthdr.c
@@ -551,7 +551,7 @@ static int nft_exthdr_tcp_set_init(const struct nft_ctx *ctx,
 				   const struct nlattr * const tb[])
 {
 	struct nft_exthdr *priv = nft_expr_priv(expr);
-	u32 offset, len, flags = 0, op = NFT_EXTHDR_OP_IPV6;
+	u32 offset, len, flags = 0;
 	int err;
 
 	if (!tb[NFTA_EXTHDR_SREG] ||
@@ -581,15 +581,11 @@ static int nft_exthdr_tcp_set_init(const struct nft_ctx *ctx,
 		return -EOPNOTSUPP;
 	}
 
-	err = nft_parse_u32_check(tb[NFTA_EXTHDR_OP], U8_MAX, &op);
-	if (err < 0)
-		return err;
-
 	priv->type   = nla_get_u8(tb[NFTA_EXTHDR_TYPE]);
 	priv->offset = offset;
 	priv->len    = len;
 	priv->flags  = flags;
-	priv->op     = op;
+	priv->op     = NFT_EXTHDR_OP_TCPOPT;
 
 	return nft_parse_register_load(ctx, tb[NFTA_EXTHDR_SREG], &priv->sreg,
 				       priv->len);
-- 
2.47.3