diff mbox series

[iptables] nft: Optimize class-based IP prefix matches

Message ID 20201002090334.29788-1-phil@nwl.cc
State Under Review
Delegated to: Pablo Neira
Headers show
Series [iptables] nft: Optimize class-based IP prefix matches | expand

Commit Message

Phil Sutter Oct. 2, 2020, 9:03 a.m. UTC
Payload expression works on byte-boundaries, leverage this with suitable
prefix lengths.

Signed-off-by: Phil Sutter <phil@nwl.cc>
---
 iptables/nft-ipv4.c   |  6 ++++--
 iptables/nft-ipv6.c   |  6 ++++--
 iptables/nft-shared.c | 14 ++++++++++----
 iptables/nft-shared.h |  4 ++++
 4 files changed, 22 insertions(+), 8 deletions(-)

Comments

Arturo Borrero Gonzalez Oct. 2, 2020, 11:25 a.m. UTC | #1
On 2020-10-02 11:03, Phil Sutter wrote:
> +#define max(x, y) ((x) > (y) ? (x) : (y))

This is unused, right? not sure if on purpose.
Phil Sutter Oct. 2, 2020, 11:34 a.m. UTC | #2
On Fri, Oct 02, 2020 at 01:25:37PM +0200, Arturo Borrero Gonzalez wrote:
> On 2020-10-02 11:03, Phil Sutter wrote:
> > +#define max(x, y) ((x) > (y) ? (x) : (y))
> 
> This is unused, right? not sure if on purpose.

Ah yes, I felt like adding it while being at it. Fine with you or should
I drop it?

Thanks for reviewing!

Phil
Pablo Neira Ayuso Oct. 6, 2020, 8:56 a.m. UTC | #3
On Fri, Oct 02, 2020 at 11:03:34AM +0200, Phil Sutter wrote:
> Payload expression works on byte-boundaries, leverage this with suitable
> prefix lengths.

Interesing. But it kicks in the raw payload expression in nftables.

# nft list ruleset
table ip filter {
        chain INPUT {
                type filter hook input priority filter; policy accept;
                @nh,96,24 8323072 counter packets 0 bytes 0
        }

Would you send a patch for nftables too? There is already approximate
offset matching in the tree, it should not be too hard to amend.

Thanks.
Phil Sutter Oct. 6, 2020, 9:37 a.m. UTC | #4
On Tue, Oct 06, 2020 at 10:56:21AM +0200, Pablo Neira Ayuso wrote:
> On Fri, Oct 02, 2020 at 11:03:34AM +0200, Phil Sutter wrote:
> > Payload expression works on byte-boundaries, leverage this with suitable
> > prefix lengths.
> 
> Interesing. But it kicks in the raw payload expression in nftables.
> 
> # nft list ruleset
> table ip filter {
>         chain INPUT {
>                 type filter hook input priority filter; policy accept;
>                 @nh,96,24 8323072 counter packets 0 bytes 0
>         }
> 
> Would you send a patch for nftables too? There is already approximate
> offset matching in the tree, it should not be too hard to amend.

I had a quick look but it didn't seem trivial to me. It is in
payload_expr_complete() where a template lookup happens based on
expression offset and length which fails due to the unexpected length.
Is this the right place to adjust or am I wrong?

Strictly speaking, this is just a lack of feature in nftables and
nothing breaks due to it. Do you still want to block the iptables change
for it?

Cheers, Phil
Pablo Neira Ayuso Oct. 6, 2020, 9:41 a.m. UTC | #5
On Tue, Oct 06, 2020 at 11:37:44AM +0200, Phil Sutter wrote:
> On Tue, Oct 06, 2020 at 10:56:21AM +0200, Pablo Neira Ayuso wrote:
> > On Fri, Oct 02, 2020 at 11:03:34AM +0200, Phil Sutter wrote:
> > > Payload expression works on byte-boundaries, leverage this with suitable
> > > prefix lengths.
> > 
> > Interesing. But it kicks in the raw payload expression in nftables.
> > 
> > # nft list ruleset
> > table ip filter {
> >         chain INPUT {
> >                 type filter hook input priority filter; policy accept;
> >                 @nh,96,24 8323072 counter packets 0 bytes 0
> >         }
> > 
> > Would you send a patch for nftables too? There is already approximate
> > offset matching in the tree, it should not be too hard to amend.
> 
> I had a quick look but it didn't seem trivial to me. It is in
> payload_expr_complete() where a template lookup happens based on
> expression offset and length which fails due to the unexpected length.
> Is this the right place to adjust or am I wrong?
> 
> Strictly speaking, this is just a lack of feature in nftables and
> nothing breaks due to it. Do you still want to block the iptables change
> for it?

Not block. Just get things aligned. This is a bit of a step back in
the integration between iptables-nft and nft IMO.

I will have a look.
Phil Sutter Oct. 6, 2020, 11:48 a.m. UTC | #6
On Tue, Oct 06, 2020 at 11:41:21AM +0200, Pablo Neira Ayuso wrote:
> On Tue, Oct 06, 2020 at 11:37:44AM +0200, Phil Sutter wrote:
> > On Tue, Oct 06, 2020 at 10:56:21AM +0200, Pablo Neira Ayuso wrote:
> > > On Fri, Oct 02, 2020 at 11:03:34AM +0200, Phil Sutter wrote:
> > > > Payload expression works on byte-boundaries, leverage this with suitable
> > > > prefix lengths.
> > > 
> > > Interesing. But it kicks in the raw payload expression in nftables.
> > > 
> > > # nft list ruleset
> > > table ip filter {
> > >         chain INPUT {
> > >                 type filter hook input priority filter; policy accept;
> > >                 @nh,96,24 8323072 counter packets 0 bytes 0
> > >         }
> > > 
> > > Would you send a patch for nftables too? There is already approximate
> > > offset matching in the tree, it should not be too hard to amend.
> > 
> > I had a quick look but it didn't seem trivial to me. It is in
> > payload_expr_complete() where a template lookup happens based on
> > expression offset and length which fails due to the unexpected length.
> > Is this the right place to adjust or am I wrong?
> > 
> > Strictly speaking, this is just a lack of feature in nftables and
> > nothing breaks due to it. Do you still want to block the iptables change
> > for it?
> 
> Not block. Just get things aligned. This is a bit of a step back in
> the integration between iptables-nft and nft IMO.

Well yes, it takes iptables-nft ahead in that regard. We should
implement the same flexible payload size matching in nftables, too.

> I will have a look.

Thanks!
diff mbox series

Patch

diff --git a/iptables/nft-ipv4.c b/iptables/nft-ipv4.c
index afdecf9711e64..ce702041af0f4 100644
--- a/iptables/nft-ipv4.c
+++ b/iptables/nft-ipv4.c
@@ -199,7 +199,8 @@  static void nft_ipv4_parse_payload(struct nft_xt_ctx *ctx,
 			parse_mask_ipv4(ctx, &cs->fw.ip.smsk);
 			ctx->flags &= ~NFT_XT_CTX_BITWISE;
 		} else {
-			cs->fw.ip.smsk.s_addr = 0xffffffff;
+			memset(&cs->fw.ip.smsk, 0xff,
+			       min(ctx->payload.len, sizeof(struct in_addr)));
 		}
 
 		if (inv)
@@ -212,7 +213,8 @@  static void nft_ipv4_parse_payload(struct nft_xt_ctx *ctx,
 			parse_mask_ipv4(ctx, &cs->fw.ip.dmsk);
 			ctx->flags &= ~NFT_XT_CTX_BITWISE;
 		} else {
-			cs->fw.ip.dmsk.s_addr = 0xffffffff;
+			memset(&cs->fw.ip.dmsk, 0xff,
+			       min(ctx->payload.len, sizeof(struct in_addr)));
 		}
 
 		if (inv)
diff --git a/iptables/nft-ipv6.c b/iptables/nft-ipv6.c
index 4008b7eab4f2a..c877ec6d10887 100644
--- a/iptables/nft-ipv6.c
+++ b/iptables/nft-ipv6.c
@@ -146,7 +146,8 @@  static void nft_ipv6_parse_payload(struct nft_xt_ctx *ctx,
 			parse_mask_ipv6(ctx, &cs->fw6.ipv6.smsk);
 			ctx->flags &= ~NFT_XT_CTX_BITWISE;
 		} else {
-			memset(&cs->fw6.ipv6.smsk, 0xff, sizeof(struct in6_addr));
+			memset(&cs->fw6.ipv6.smsk, 0xff,
+			       min(ctx->payload.len, sizeof(struct in6_addr)));
 		}
 
 		if (inv)
@@ -159,7 +160,8 @@  static void nft_ipv6_parse_payload(struct nft_xt_ctx *ctx,
 			parse_mask_ipv6(ctx, &cs->fw6.ipv6.dmsk);
 			ctx->flags &= ~NFT_XT_CTX_BITWISE;
 		} else {
-			memset(&cs->fw6.ipv6.dmsk, 0xff, sizeof(struct in6_addr));
+			memset(&cs->fw6.ipv6.dmsk, 0xff,
+			       min(ctx->payload.len, sizeof(struct in6_addr)));
 		}
 
 		if (inv)
diff --git a/iptables/nft-shared.c b/iptables/nft-shared.c
index 7741d23befc5a..545e9c60fa015 100644
--- a/iptables/nft-shared.c
+++ b/iptables/nft-shared.c
@@ -166,16 +166,22 @@  void add_addr(struct nftnl_rule *r, int offset,
 	      void *data, void *mask, size_t len, uint32_t op)
 {
 	const unsigned char *m = mask;
+	bool bitwise = false;
 	int i;
 
-	add_payload(r, offset, len, NFT_PAYLOAD_NETWORK_HEADER);
-
 	for (i = 0; i < len; i++) {
-		if (m[i] != 0xff)
+		if (m[i] != 0xff) {
+			bitwise = m[i] != 0;
 			break;
+		}
 	}
 
-	if (i != len)
+	if (!bitwise)
+		len = i;
+
+	add_payload(r, offset, len, NFT_PAYLOAD_NETWORK_HEADER);
+
+	if (bitwise)
 		add_bitwise(r, mask, len);
 
 	add_cmp_ptr(r, op, data, len);
diff --git a/iptables/nft-shared.h b/iptables/nft-shared.h
index 4440fd17bfeac..a52463342b30a 100644
--- a/iptables/nft-shared.h
+++ b/iptables/nft-shared.h
@@ -247,4 +247,8 @@  void xtables_restore_parse(struct nft_handle *h,
 			   const struct nft_xt_restore_parse *p);
 
 void nft_check_xt_legacy(int family, bool is_ipt_save);
+
+#define min(x, y) ((x) < (y) ? (x) : (y))
+#define max(x, y) ((x) > (y) ? (x) : (y))
+
 #endif