From: Daniel Borkmann <dborkman@redhat.com>
To: Chema Gonzalez <chema@google.com>
Cc: David Miller <davem@davemloft.net>,
Eric Dumazet <edumazet@google.com>,
netdev@vger.kernel.org, ast@plumgrid.com
Subject: Re: [PATCH] filter: added BPF random opcode
Date: Tue, 15 Apr 2014 18:44:29 +0200 [thread overview]
Message-ID: <534D61ED.9070203@redhat.com> (raw)
In-Reply-To: <CA+ZOOTMmRiACgBtMSWm-Barr_MZS446Z5M2Z6B+HmZYwqcvh6A@mail.gmail.com>
On 04/15/2014 06:30 PM, Chema Gonzalez wrote:
> On Tue, Apr 15, 2014 at 12:24 AM, Daniel Borkmann <dborkman@redhat.com> wrote:
>> Hi Chema,
>>
>> [cc'ing Alexei as well]
>>
>> note, net-next is still closed, so you might need to resend this later
>> on again when it opens up.
> I will. Thanks!
Great, thanks.
>> On 04/15/2014 01:02 AM, Chema Gonzalez wrote:
>>> diff --git a/tools/net/bpf_exp.l b/tools/net/bpf_exp.l
>>> index bf7be77..804256f 100644
>>> --- a/tools/net/bpf_exp.l
>>> +++ b/tools/net/bpf_exp.l
>>> @@ -92,6 +92,7 @@ extern void yyerror(const char *str);
>>> "#"?("cpu") { return K_CPU; }
>>> "#"?("vlan_tci") { return K_VLANT; }
>>> "#"?("vlan_pr") { return K_VLANP; }
>>> +"#"?("random") { return K_RAND; }
>>
>>
>> Thanks for also updating bpf_asm ! :)
> bpf_asm was key in ensuring this worked. In fact, we should modify the
> Makefile so that it relies on the local filter.h before the
> /usr/include/ one (my Ubuntu Precise /usr/include/linux/filter.h does
> not define BPF_MOD, BPF_XOR, SKF_AD_VLAN_TAG, SKF_AD_VLAN_TAG_PRESENT,
> or SKF_AD_PAY_OFFSET).
Good point, feel free to send a patch. :)
>> I think using just "rnd" is cleaner here.
> I think using always random (in fact I may s/K_RAND/K_RANDOM/g) allows
> easier grepping.
I know it's just nitpicking, but I'd be happier if that would
either be rnd or rand in bpf_asm.
>>> diff --git a/tools/net/icmp_random.bpf b/tools/net/icmp_random.bpf
>>> new file mode 100644
>>> index 0000000..b9adcbf
>>> --- /dev/null
>>> +++ b/tools/net/icmp_random.bpf
>>> @@ -0,0 +1,12 @@
>>> +# icmp random packet sampling, 1 in 4
>>> +ldh [12]
>>> +jne #0x800, drop
>>> +ldb [23]
>>> +jneq #1, drop
>>> +# get a random uint32 number
>>> +ld random
>>> +mod #4
>>> +jneq #1, drop
>>> +ret #-1
>>> +drop: ret #0
>>> +
>>>
>>
>> This example should rather go into Documentation/networking/filter.txt's
>> example section, rather than tools/net/ .
> I'll add it there.
Ok, thanks.
> Now, I'd like to add a new directory for BPF programs (tools/net/bpf/
> ?). It allows playing with bpf_asm.
For 'playing', I'd rather be happy to add that to the documentation file
in Documentation/networking/filter.txt where we have other examples, or
alternatively, if there is really no other way around, a new folder inside
of Documentation/networking/ .
next prev parent reply other threads:[~2014-04-15 16:44 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-04-14 23:02 [PATCH] filter: added BPF random opcode Chema Gonzalez
2014-04-15 7:24 ` Daniel Borkmann
2014-04-15 14:41 ` Eric Dumazet
2014-04-15 15:04 ` Daniel Borkmann
2014-04-15 16:22 ` Chema Gonzalez
2014-04-15 16:30 ` Chema Gonzalez
2014-04-15 16:44 ` Daniel Borkmann [this message]
2014-04-15 18:19 ` Chema Gonzalez
2014-04-15 18:16 Chema Gonzalez
2014-04-16 6:24 ` Alexei Starovoitov
2014-04-16 8:32 ` Daniel Borkmann
2014-04-17 0:19 ` Chema Gonzalez
2014-04-17 1:38 ` Eric Dumazet
2014-04-18 20:21 ` Alexei Starovoitov
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