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Date: Tue, 15 Apr 2014 09:30:49 -0700 From: Chema Gonzalez <chema@...gle.com> To: Daniel Borkmann <dborkman@...hat.com> Cc: David Miller <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, netdev@...r.kernel.org, ast@...mgrid.com Subject: Re: [PATCH] filter: added BPF random opcode On Tue, Apr 15, 2014 at 12:24 AM, Daniel Borkmann <dborkman@...hat.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! > 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). > 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. >> 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. Now, I'd like to add a new directory for BPF programs (tools/net/bpf/ ?). It allows playing with bpf_asm. -Chema -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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