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Add support for ttl translation

PATCH In review Shivani Bhardwaj 2 participants 6 messages Jan 4, 2016 netfilter

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Shivani Bhardwaj

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#0 lore raw

cover Add support for ttl translation

This patchset adds ttl translation to nftables by adding ip ttl to the buffer everytime a ttl match is hit as it is necessary to mention the protocol version with ttl, that is,

$ sudo nft .. ttl 3 ..             won't work but
$ sudo nft .. ip ttl 3 ..          would work.
Also, since adding ip to the buffer in the code for ttl won't look
suitable, some amendments have been done in the nft-ipv4 code.

Shivani Bhardwaj (2):
iptables: nft-ipv4: Add ip ttl to the buffer
extensions: libipt_ttl: Add translation to nft

 extensions/libipt_ttl.c | 28 ++++++++++++++++++++++++++++
 iptables/nft-ipv4.c     |  3 +++
 2 files changed, 31 insertions(+)
Signature · 1 line
1.9.1
author
#1 lore raw

PATCH 1/2 iptables: nft-ipv4: Add ip ttl to the buffer

Add the string "ip ttl" to the buffer whenever a match for ttl is found as ttl needs to be specified with the version of protocol being used.

Signed-off-by Shivani Bhardwaj <[email protected]>
---
 iptables/nft-ipv4.c | 3 +++
 1 file changed, 3 insertions(+)
iptables/nft-ipv4.c +3 -0
index ede8f17..684096f 100644
@@ -477,6 +477,9 @@ static int nft_ipv4_xlate(const void *data, struct xt_buf *buf)
 			   inet_ntoa(cs->fw.ip.dst));
 	}
 
+	if (xlate_find_match(cs, "ttl"))
+		xt_buf_add(buf, "ip ttl ");
+
 	ret = xlate_matches(cs, buf);
 	if (!ret)
 		return ret;
Signature · 1 line
1.9.1
author
#2 lore raw

PATCH 2/2 extensions: libipt_ttl: Add translation to nft

In reply to Shivani Bhardwaj

Add translation for module ttl to nftables.

Examples:

$ sudo iptables-translate -A INPUT -m ttl --ttl-eq 3 -j ACCEPT
nft add rule ip filter INPUT ip ttl 3 counter accept
$ sudo iptables-translate -A INPUT -m ttl --ttl-gt 5 -j ACCEPT
nft add rule ip filter INPUT ip ttl \> 5 counter accept
Signed-off-by Shivani Bhardwaj <[email protected]>
---
 extensions/libipt_ttl.c | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)
extensions/libipt_ttl.c +28 -0
index 5fe08cc..5df014b 100644
@@ -100,6 +100,33 @@ static void ttl_save(const void *ip, const struct xt_entry_match *match)
 	printf(" %u", info->ttl);
 }
 
+static int ttl_xlate(const struct xt_entry_match *match,
+		     struct xt_buf *buf, int numeric)
+{
+	const struct ipt_ttl_info *info =
+			(struct ipt_ttl_info *) match->data;
+
+		switch (info->mode) {
+		case IPT_TTL_EQ:
+			xt_buf_add(buf, "%u ", info->ttl);
+			break;
+		case IPT_TTL_NE:
+			xt_buf_add(buf, "!= %u ", info->ttl);
+			break;
+		case IPT_TTL_LT:
+			xt_buf_add(buf, "\\< %u ", info->ttl);
+			break;
+		case IPT_TTL_GT:
+			xt_buf_add(buf, "\\> %u ", info->ttl);
+			break;
+		default:
+			/* error */
+			break;
+	}
+
+	return 1;
+}
+
 #define s struct ipt_ttl_info
 static const struct xt_option_entry ttl_opts[] = {
 	{.name = "ttl-lt", .id = O_TTL_LT, .excl = F_ANY, .type = XTTYPE_UINT8,

@@ -126,6 +153,7 @@ static struct xtables_match ttl_mt_reg = {
 	.x6_parse	= ttl_parse,
 	.x6_fcheck	= ttl_check,
 	.x6_options	= ttl_opts,
+	.xlate		= ttl_xlate,
 };
Signature · 1 line
1.9.1
maintainer
#3 lore raw
In reply to Shivani Bhardwaj
Quoted 5 lines · Shivani Bhardwaj

This patchset adds ttl translation to nftables by adding ip ttl to the buffer everytime a ttl match is hit as it is necessary to mention the protocol version with ttl, that is,

$ sudo nft .. ttl 3 ..             won't work but
$ sudo nft .. ip ttl 3 ..          would work.

This above is the right syntax.

Quoted 5 lines

Also, since adding ip to the buffer in the code for ttl won't look suitable, some amendments have been done in the nft-ipv4 code.

Shivani Bhardwaj (2):
iptables: nft-ipv4: Add ip ttl to the buffer

I don't think you need this change for nft-ipv4.

author
#4 lore raw
Quoted 9 lines · Pablo Neira Ayuso
Quoted 5 lines · Shivani Bhardwaj

This patchset adds ttl translation to nftables by adding ip ttl to the buffer everytime a ttl match is hit as it is necessary to mention the protocol version with ttl, that is,

$ sudo nft .. ttl 3 ..             won't work but
$ sudo nft .. ip ttl 3 ..          would work.

This above is the right syntax.

Quoted 7 lines
Quoted 5 lines

Also, since adding ip to the buffer in the code for ttl won't look suitable, some amendments have been done in the nft-ipv4 code.

Shivani Bhardwaj (2):
iptables: nft-ipv4: Add ip ttl to the buffer

I don't think you need this change for nft-ipv4.

Hi Pablo,

Should I be doing xt_buf_add("ip ttl") in the code for ttl?

maintainer
#5 lore raw
Quoted 13 lines · Shivani Bhardwaj
Quoted 12 lines · Pablo Neira Ayuso
Quoted 5 lines · Shivani Bhardwaj

This patchset adds ttl translation to nftables by adding ip ttl to the buffer everytime a ttl match is hit as it is necessary to mention the protocol version with ttl, that is,

$ sudo nft .. ttl 3 ..             won't work but
$ sudo nft .. ip ttl 3 ..          would work.

This above is the right syntax.

Quoted 3 lines

Also, since adding ip to the buffer in the code for ttl won't look suitable, some amendments have been done in the nft-ipv4 code.

Quoted 8 lines
Quoted 4 lines
Quoted 2 lines

Shivani Bhardwaj (2):
iptables: nft-ipv4: Add ip ttl to the buffer

I don't think you need this change for nft-ipv4.

Hi Pablo,

Should I be doing xt_buf_add("ip ttl") in the code for ttl?

Yes, that should be fine.