netdev - Re: [PATCH] filter: Optimize instruction revalidation code.

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Message-ID: <20101116221310.GA3058@nuttenaction>
Date:	Tue, 16 Nov 2010 23:13:10 +0100
From:	Hagen Paul Pfeifer <hagen@...u.net>
To:	Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>
Cc:	davem@...emloft.net, eric.dumazet@...il.com,
	drosenberg@...curity.com, netdev@...r.kernel.org
Subject: Re: [PATCH] filter: Optimize instruction revalidation code.

* Tetsuo Handa | 2010-11-16 22:08:50 [+0900]:

>--- a/net/core/filter.c
>+++ b/net/core/filter.c
>@@ -383,7 +383,57 @@ EXPORT_SYMBOL(sk_run_filter);
>  */
> int sk_chk_filter(struct sock_filter *filter, int flen)
> {
>-	struct sock_filter *ftest;
>+	/*
>+	 * Valid instructions are initialized to non-0.
>+	 * Invalid instructions are initialized to 0.
>+	 */
>+	static u16 codes[] = {
>+		[BPF_ALU|BPF_ADD|BPF_K]  = BPF_S_ALU_ADD_K + 1,
>+		[BPF_ALU|BPF_ADD|BPF_X]  = BPF_S_ALU_ADD_X + 1,
>+		[BPF_ALU|BPF_SUB|BPF_K]  = BPF_S_ALU_SUB_K + 1,
[...]

Maybe I don't get it, but you increment the opcode by one, but you never
increment the opcode in sk_run_filter() - do I miss something? Did you test
the your patch (a trivial tcpdump rule should be sufficient)?

If this question is answered (or fixed):

Signed-off-by: Hagen Paul Pfeifer <hagen@...u.net>

HGN
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