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

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Date:	Wed, 17 Nov 2010 00:45:05 +0100
From:	Hagen Paul Pfeifer <hagen@...u.net>
To:	Changli Gao <xiaosuo@...il.com>
Cc:	Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>,
	davem@...emloft.net, eric.dumazet@...il.com,
	drosenberg@...curity.com, netdev@...r.kernel.org
Subject: Re: [PATCH] filter: Optimize instruction revalidation code.

* Changli Gao | 2010-11-17 07:31:51 [+0800]:

>> 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)?
>>
>
>+               code = codes[code];
>+               if (!code--)
>+                       return -EINVAL;

Right, temporary in sk_chk_filter() but as I wrote earlier not in sk_run_filter().

>But how about this:
>
>enum {
>        BPF_S_RET_K = 1,

better.

Best regards, Hagen

BTW: you can verify your code by construct some artificial filter rules via

struct sock_filter {
	uint16_t  code;   /* Actual filter code */
	uint8_t   jt;     /* Jump true */
	uint8_t   jf;     /* Jump false */
	uint32_t  k;      /* Generic multiuse field
};

and attach them to a socket with setsockopt.
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