* [PATCH nft] netlink_delinearize: only remove protocol if equal cmp is used
@ 2016-01-27 13:42 Florian Westphal
2016-01-27 15:45 ` Pablo Neira Ayuso
0 siblings, 1 reply; 2+ messages in thread
From: Florian Westphal @ 2016-01-27 13:42 UTC (permalink / raw
To: netfilter-devel; +Cc: Florian Westphal
Check for OP_EQ before removing a dependency, else we may zap wrong one,
changing the meaning of the rule.
Listing without patch:
ip protocol udp udp dport ssh
ip protocol udp udp dport ssh
counter packets 1 bytes 308 ip protocol udp udp dport ssh
With patch:
ip protocol != tcp udp dport ssh
ip protocol != udp udp dport ssh
ip protocol != tcp counter packets 1 bytes 308 udp dport ssh
Signed-off-by: Florian Westphal <fw@strlen.de>
---
NB: ip protocol != udp udp dport ... is nonsensical, not sure
if its worth the hassle to try to reject stuff like this.
src/netlink_delinearize.c | 1 +
tests/py/ip/tcp.t | 6 ++++++
tests/py/ip/tcp.t.payload | 18 ++++++++++++++++++
3 files changed, 25 insertions(+)
create mode 100644 tests/py/ip/tcp.t
create mode 100644 tests/py/ip/tcp.t.payload
diff --git a/src/netlink_delinearize.c b/src/netlink_delinearize.c
index 76d598c..2732c96 100644
--- a/src/netlink_delinearize.c
+++ b/src/netlink_delinearize.c
@@ -1042,6 +1042,7 @@ static void payload_match_expand(struct rule_pp_ctx *ctx,
* payload expression.
*/
if (ctx->pbase == PROTO_BASE_INVALID &&
+ expr->op == OP_EQ &&
left->flags & EXPR_F_PROTOCOL) {
unsigned int proto = mpz_get_be16(tmp->value);
const struct proto_desc *desc, *next;
diff --git a/tests/py/ip/tcp.t b/tests/py/ip/tcp.t
new file mode 100644
index 0000000..4dcfcb6
--- /dev/null
+++ b/tests/py/ip/tcp.t
@@ -0,0 +1,6 @@
+:input;type filter hook input priority 0
+
+*ip;test-ip;input
+
+ip protocol tcp tcp dport ssh accept;ok;tcp dport 22 accept
+ip protocol ne tcp udp dport ssh accept;ok;ip protocol != 6 udp dport 22 accept
diff --git a/tests/py/ip/tcp.t.payload b/tests/py/ip/tcp.t.payload
new file mode 100644
index 0000000..ed0dcc8
--- /dev/null
+++ b/tests/py/ip/tcp.t.payload
@@ -0,0 +1,18 @@
+# ip protocol tcp tcp dport ssh accept
+ip test-ip input
+ [ payload load 1b @ network header + 9 => reg 1 ]
+ [ cmp eq reg 1 0x00000006 ]
+ [ payload load 2b @ transport header + 2 => reg 1 ]
+ [ cmp eq reg 1 0x00001600 ]
+ [ immediate reg 0 accept ]
+
+# ip protocol ne tcp udp dport ssh accept
+ip test-ip input
+ [ payload load 1b @ network header + 9 => reg 1 ]
+ [ cmp neq reg 1 0x00000006 ]
+ [ payload load 1b @ network header + 9 => reg 1 ]
+ [ cmp eq reg 1 0x00000011 ]
+ [ payload load 2b @ transport header + 2 => reg 1 ]
+ [ cmp eq reg 1 0x00001600 ]
+ [ immediate reg 0 accept ]
+
--
2.4.10
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH nft] netlink_delinearize: only remove protocol if equal cmp is used
2016-01-27 13:42 [PATCH nft] netlink_delinearize: only remove protocol if equal cmp is used Florian Westphal
@ 2016-01-27 15:45 ` Pablo Neira Ayuso
0 siblings, 0 replies; 2+ messages in thread
From: Pablo Neira Ayuso @ 2016-01-27 15:45 UTC (permalink / raw
To: Florian Westphal; +Cc: netfilter-devel
On Wed, Jan 27, 2016 at 02:42:35PM +0100, Florian Westphal wrote:
> Check for OP_EQ before removing a dependency, else we may zap wrong one,
> changing the meaning of the rule.
>
> Listing without patch:
> ip protocol udp udp dport ssh
> ip protocol udp udp dport ssh
> counter packets 1 bytes 308 ip protocol udp udp dport ssh
>
> With patch:
> ip protocol != tcp udp dport ssh
> ip protocol != udp udp dport ssh
> ip protocol != tcp counter packets 1 bytes 308 udp dport ssh
Acked-by: Pablo Neira Ayuso <pablo@netfilter.org>
> Signed-off-by: Florian Westphal <fw@strlen.de>
> ---
> NB: ip protocol != udp udp dport ... is nonsensical, not sure
> if its worth the hassle to try to reject stuff like this.
I agree this is not worth. We'll have more advanced tools to perform
transformations and more in-depth semantic evaluation of the ruleset
at some point, but not now ;-)
^ permalink raw reply [flat|nested] 2+ messages in thread
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2016-01-27 13:42 [PATCH nft] netlink_delinearize: only remove protocol if equal cmp is used Florian Westphal
2016-01-27 15:45 ` Pablo Neira Ayuso
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