From 2c3c1048746a4622d8c89a29670120dc8fab93c4 Mon Sep 17 00:00:00 2001
From: Daniel Baumann <daniel.baumann@progress-linux.org>
Date: Sun, 7 Apr 2024 20:49:45 +0200
Subject: Adding upstream version 6.1.76.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
---
 net/netfilter/xt_HL.c | 159 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 159 insertions(+)
 create mode 100644 net/netfilter/xt_HL.c

(limited to 'net/netfilter/xt_HL.c')

diff --git a/net/netfilter/xt_HL.c b/net/netfilter/xt_HL.c
new file mode 100644
index 000000000..7873b834c
--- /dev/null
+++ b/net/netfilter/xt_HL.c
@@ -0,0 +1,159 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * TTL modification target for IP tables
+ * (C) 2000,2005 by Harald Welte <laforge@netfilter.org>
+ *
+ * Hop Limit modification target for ip6tables
+ * Maciej Soltysiak <solt@dns.toxicfilms.tv>
+ */
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+#include <linux/module.h>
+#include <linux/skbuff.h>
+#include <linux/ip.h>
+#include <linux/ipv6.h>
+#include <net/checksum.h>
+
+#include <linux/netfilter/x_tables.h>
+#include <linux/netfilter_ipv4/ipt_TTL.h>
+#include <linux/netfilter_ipv6/ip6t_HL.h>
+
+MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
+MODULE_AUTHOR("Maciej Soltysiak <solt@dns.toxicfilms.tv>");
+MODULE_DESCRIPTION("Xtables: Hoplimit/TTL Limit field modification target");
+MODULE_LICENSE("GPL");
+
+static unsigned int
+ttl_tg(struct sk_buff *skb, const struct xt_action_param *par)
+{
+	struct iphdr *iph;
+	const struct ipt_TTL_info *info = par->targinfo;
+	int new_ttl;
+
+	if (skb_ensure_writable(skb, sizeof(*iph)))
+		return NF_DROP;
+
+	iph = ip_hdr(skb);
+
+	switch (info->mode) {
+	case IPT_TTL_SET:
+		new_ttl = info->ttl;
+		break;
+	case IPT_TTL_INC:
+		new_ttl = iph->ttl + info->ttl;
+		if (new_ttl > 255)
+			new_ttl = 255;
+		break;
+	case IPT_TTL_DEC:
+		new_ttl = iph->ttl - info->ttl;
+		if (new_ttl < 0)
+			new_ttl = 0;
+		break;
+	default:
+		new_ttl = iph->ttl;
+		break;
+	}
+
+	if (new_ttl != iph->ttl) {
+		csum_replace2(&iph->check, htons(iph->ttl << 8),
+					   htons(new_ttl << 8));
+		iph->ttl = new_ttl;
+	}
+
+	return XT_CONTINUE;
+}
+
+static unsigned int
+hl_tg6(struct sk_buff *skb, const struct xt_action_param *par)
+{
+	struct ipv6hdr *ip6h;
+	const struct ip6t_HL_info *info = par->targinfo;
+	int new_hl;
+
+	if (skb_ensure_writable(skb, sizeof(*ip6h)))
+		return NF_DROP;
+
+	ip6h = ipv6_hdr(skb);
+
+	switch (info->mode) {
+	case IP6T_HL_SET:
+		new_hl = info->hop_limit;
+		break;
+	case IP6T_HL_INC:
+		new_hl = ip6h->hop_limit + info->hop_limit;
+		if (new_hl > 255)
+			new_hl = 255;
+		break;
+	case IP6T_HL_DEC:
+		new_hl = ip6h->hop_limit - info->hop_limit;
+		if (new_hl < 0)
+			new_hl = 0;
+		break;
+	default:
+		new_hl = ip6h->hop_limit;
+		break;
+	}
+
+	ip6h->hop_limit = new_hl;
+
+	return XT_CONTINUE;
+}
+
+static int ttl_tg_check(const struct xt_tgchk_param *par)
+{
+	const struct ipt_TTL_info *info = par->targinfo;
+
+	if (info->mode > IPT_TTL_MAXMODE)
+		return -EINVAL;
+	if (info->mode != IPT_TTL_SET && info->ttl == 0)
+		return -EINVAL;
+	return 0;
+}
+
+static int hl_tg6_check(const struct xt_tgchk_param *par)
+{
+	const struct ip6t_HL_info *info = par->targinfo;
+
+	if (info->mode > IP6T_HL_MAXMODE)
+		return -EINVAL;
+	if (info->mode != IP6T_HL_SET && info->hop_limit == 0)
+		return -EINVAL;
+	return 0;
+}
+
+static struct xt_target hl_tg_reg[] __read_mostly = {
+	{
+		.name       = "TTL",
+		.revision   = 0,
+		.family     = NFPROTO_IPV4,
+		.target     = ttl_tg,
+		.targetsize = sizeof(struct ipt_TTL_info),
+		.table      = "mangle",
+		.checkentry = ttl_tg_check,
+		.me         = THIS_MODULE,
+	},
+	{
+		.name       = "HL",
+		.revision   = 0,
+		.family     = NFPROTO_IPV6,
+		.target     = hl_tg6,
+		.targetsize = sizeof(struct ip6t_HL_info),
+		.table      = "mangle",
+		.checkentry = hl_tg6_check,
+		.me         = THIS_MODULE,
+	},
+};
+
+static int __init hl_tg_init(void)
+{
+	return xt_register_targets(hl_tg_reg, ARRAY_SIZE(hl_tg_reg));
+}
+
+static void __exit hl_tg_exit(void)
+{
+	xt_unregister_targets(hl_tg_reg, ARRAY_SIZE(hl_tg_reg));
+}
+
+module_init(hl_tg_init);
+module_exit(hl_tg_exit);
+MODULE_ALIAS("ipt_TTL");
+MODULE_ALIAS("ip6t_HL");
-- 
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