Here's a patch to libpcap-1.3 to test against. I still need to
include changes to man pages.
g
On Sat, 08 Sep 2012 10:03:35 +0200
Eric Dumazet <eric.duma...@gmail.com> wrote:
> From: Eric Dumazet <eduma...@google.com>
>
> On Fri, 2012-09-07 at 20:03 -0700, Andi Kleen wrote:
> > On Fri, Sep 07, 2012 at 07:49:10AM +0000, George Bakos wrote:
> > > Gents,
> > > Any fundamental reason why the following (, etc.) shouldn't be
> > > included in net/core/filter.c?
> > >
> > > case BPF_S_ALU_MOD_X:
> > > if (X == 0)
> > > return 0;
> > > A %= X;
> > > continue;
> >
> > Copying netdev.
> >
> > In principle no reason against it, but you may need to update
> > the various BPF JITs too that Linux now has too.
>
> Hi Andi, thanks for the forward
>
> In recent commit ffe06c17afbb was added ALU_XOR_X,
> so we could add ALU_MOD_X as well.
>
> ALU_MOD_K is a bit more complex as we cant use an ancillary, and must
> instead use a new BPF_OP code :
>
> /* alu/jmp fields */
> #define BPF_OP(code) ((code) & 0xf0)
> #define BPF_ADD 0x00
> #define BPF_SUB 0x10
> #define BPF_MUL 0x20
> #define BPF_DIV 0x30
> #define BPF_OR 0x40
> #define BPF_AND 0x50
> #define BPF_LSH 0x60
> #define BPF_RSH 0x70
> #define BPF_NEG 0x80
>
> So I guess we could use
>
> #define BPF_MOD 0x90
>
> About the various arches JIT, there is no hurry :
> We can update them later.
>
> At JIT 'compile' time, if we find a not yet handled instruction, we fall
> back to the net/core/filter.c interpreter.
>
> If the following patch is accepted, I'll do the x86 part as a followup.
>
> Thanks !
>
> [PATCH net-next] filter: add MOD operation
>
> Add a new ALU opcode, to compute a modulus.
>
> Commit ffe06c17afbbb used an ancillary to implement XOR_X,
> but here we reserve one of the available ALU opcode to implement both
> MOD_X and MOD_K
>
> Signed-off-by: Eric Dumazet <eduma...@google.com>
> Suggested-by: George Bakos <gba...@alpinista.org>
> Cc: Jay Schulist <jsch...@samba.org>
> Cc: Jiri Pirko <jpi...@redhat.com>
> Cc: Andi Kleen <a...@linux.intel.com>
> ---
> include/linux/filter.h | 4 ++++
> net/core/filter.c | 15 +++++++++++++++
> 2 files changed, 19 insertions(+)
>
> diff --git a/include/linux/filter.h b/include/linux/filter.h
> index 82b0135..3cf5fd5 100644
> --- a/include/linux/filter.h
> +++ b/include/linux/filter.h
> @@ -74,6 +74,8 @@ struct sock_fprog { /* Required for SO_ATTACH_FILTER. */
> #define BPF_LSH 0x60
> #define BPF_RSH 0x70
> #define BPF_NEG 0x80
> +#define BPF_MOD 0x90
> +
> #define BPF_JA 0x00
> #define BPF_JEQ 0x10
> #define BPF_JGT 0x20
> @@ -196,6 +198,8 @@ enum {
> BPF_S_ALU_MUL_K,
> BPF_S_ALU_MUL_X,
> BPF_S_ALU_DIV_X,
> + BPF_S_ALU_MOD_K,
> + BPF_S_ALU_MOD_X,
> BPF_S_ALU_AND_K,
> BPF_S_ALU_AND_X,
> BPF_S_ALU_OR_K,
> diff --git a/net/core/filter.c b/net/core/filter.c
> index 907efd2..fbe3a8d 100644
> --- a/net/core/filter.c
> +++ b/net/core/filter.c
> @@ -167,6 +167,14 @@ unsigned int sk_run_filter(const struct sk_buff *skb,
> case BPF_S_ALU_DIV_K:
> A = reciprocal_divide(A, K);
> continue;
> + case BPF_S_ALU_MOD_X:
> + if (X == 0)
> + return 0;
> + A %= X;
> + continue;
> + case BPF_S_ALU_MOD_K:
> + A %= K;
> + continue;
> case BPF_S_ALU_AND_X:
> A &= X;
> continue;
> @@ -469,6 +477,8 @@ int sk_chk_filter(struct sock_filter *filter, unsigned
> int flen)
> [BPF_ALU|BPF_MUL|BPF_K] = BPF_S_ALU_MUL_K,
> [BPF_ALU|BPF_MUL|BPF_X] = BPF_S_ALU_MUL_X,
> [BPF_ALU|BPF_DIV|BPF_X] = BPF_S_ALU_DIV_X,
> + [BPF_ALU|BPF_MOD|BPF_K] = BPF_S_ALU_MOD_K,
> + [BPF_ALU|BPF_MOD|BPF_X] = BPF_S_ALU_MOD_X,
> [BPF_ALU|BPF_AND|BPF_K] = BPF_S_ALU_AND_K,
> [BPF_ALU|BPF_AND|BPF_X] = BPF_S_ALU_AND_X,
> [BPF_ALU|BPF_OR|BPF_K] = BPF_S_ALU_OR_K,
> @@ -531,6 +541,11 @@ int sk_chk_filter(struct sock_filter *filter, unsigned
> int flen)
> return -EINVAL;
> ftest->k = reciprocal_value(ftest->k);
> break;
> + case BPF_S_ALU_MOD_K:
> + /* check for division by zero */
> + if (ftest->k == 0)
> + return -EINVAL;
> + break;
> case BPF_S_LD_MEM:
> case BPF_S_LDX_MEM:
> case BPF_S_ST:
>
>
--
diff -Naur libpcap-1.3.0/bpf/net/bpf_filter.c libpcap-1.3.0-with-modulus/bpf/net/bpf_filter.c
--- libpcap-1.3.0/bpf/net/bpf_filter.c 2012-03-29 12:57:32.000000000 +0000
+++ libpcap-1.3.0-with-modulus/bpf/net/bpf_filter.c 2012-08-31 01:36:53.206825554 +0000
@@ -469,6 +469,12 @@
A /= X;
continue;
+ case BPF_ALU|BPF_MOD|BPF_X:
+ if (X == 0)
+ return 0;
+ A %= X;
+ continue;
+
case BPF_ALU|BPF_AND|BPF_X:
A &= X;
continue;
@@ -501,6 +507,10 @@
A /= pc->k;
continue;
+ case BPF_ALU|BPF_MOD|BPF_K:
+ A %= pc->k;
+ continue;
+
case BPF_ALU|BPF_AND|BPF_K:
A &= pc->k;
continue;
@@ -621,6 +631,13 @@
*/
if (BPF_SRC(p->code) == BPF_K && p->k == 0)
return 0;
+ break;
+ case BPF_MOD:
+ /*
+ * Check for illegal modulus 0.
+ */
+ if (BPF_SRC(p->code) == BPF_K && p->k == 0)
+ return 0;
break;
default:
return 0;
diff -Naur libpcap-1.3.0/bpf_image.c libpcap-1.3.0-with-modulus/bpf_image.c
--- libpcap-1.3.0/bpf_image.c 2012-03-29 12:57:32.000000000 +0000
+++ libpcap-1.3.0-with-modulus/bpf_image.c 2012-08-31 01:36:53.225825770 +0000
@@ -216,6 +216,11 @@
fmt = "x";
break;
+ case BPF_ALU|BPF_MOD|BPF_X:
+ op = "mod";
+ fmt = "x";
+ break;
+
case BPF_ALU|BPF_AND|BPF_X:
op = "and";
fmt = "x";
@@ -256,6 +261,11 @@
fmt = "#%d";
break;
+ case BPF_ALU|BPF_MOD|BPF_K:
+ op = "mod";
+ fmt = "#%d";
+ break;
+
case BPF_ALU|BPF_AND|BPF_K:
op = "and";
fmt = "#0x%x";
diff -Naur libpcap-1.3.0/grammar.y libpcap-1.3.0-with-modulus/grammar.y
--- libpcap-1.3.0/grammar.y 2012-03-29 12:57:32.000000000 +0000
+++ libpcap-1.3.0-with-modulus/grammar.y 2012-08-31 01:36:53.196825439 +0000
@@ -617,6 +617,7 @@
| arth '*' arth { $$ = gen_arth(BPF_MUL, $1, $3); }
| arth '/' arth { $$ = gen_arth(BPF_DIV, $1, $3); }
| arth '&' arth { $$ = gen_arth(BPF_AND, $1, $3); }
+ | arth '%' arth { $$ = gen_arth(BPF_MOD, $1, $3); }
| arth '|' arth { $$ = gen_arth(BPF_OR, $1, $3); }
| arth LSH arth { $$ = gen_arth(BPF_LSH, $1, $3); }
| arth RSH arth { $$ = gen_arth(BPF_RSH, $1, $3); }
diff -Naur libpcap-1.3.0/optimize.c libpcap-1.3.0-with-modulus/optimize.c
--- libpcap-1.3.0/optimize.c 2012-03-29 12:57:32.000000000 +0000
+++ libpcap-1.3.0-with-modulus/optimize.c 2012-08-31 01:36:53.188825347 +0000
@@ -666,6 +666,12 @@
a /= b;
break;
+ case BPF_MOD:
+ if (b == 0)
+ bpf_error("illegal modulus 0");
+ a %= b;
+ break;
+
case BPF_AND:
a &= b;
break;
@@ -1044,6 +1050,7 @@
case BPF_ALU|BPF_SUB|BPF_K:
case BPF_ALU|BPF_MUL|BPF_K:
case BPF_ALU|BPF_DIV|BPF_K:
+ case BPF_ALU|BPF_MOD|BPF_K:
case BPF_ALU|BPF_AND|BPF_K:
case BPF_ALU|BPF_OR|BPF_K:
case BPF_ALU|BPF_LSH|BPF_K:
@@ -1079,6 +1086,7 @@
case BPF_ALU|BPF_SUB|BPF_X:
case BPF_ALU|BPF_MUL|BPF_X:
case BPF_ALU|BPF_DIV|BPF_X:
+ case BPF_ALU|BPF_MOD|BPF_X:
case BPF_ALU|BPF_AND|BPF_X:
case BPF_ALU|BPF_OR|BPF_X:
case BPF_ALU|BPF_LSH|BPF_X:
@@ -1112,7 +1120,7 @@
vstore(s, &val[A_ATOM], val[X_ATOM], alter);
break;
}
- else if (op == BPF_MUL || op == BPF_DIV ||
+ else if (op == BPF_MUL || op == BPF_DIV || op == BPF_MOD ||
op == BPF_AND || op == BPF_LSH || op == BPF_RSH) {
s->code = BPF_LD|BPF_IMM;
s->k = 0;
diff -Naur libpcap-1.3.0/pcap/bpf.h libpcap-1.3.0-with-modulus/pcap/bpf.h
--- libpcap-1.3.0/pcap/bpf.h 2012-06-12 16:55:36.000000000 +0000
+++ libpcap-1.3.0-with-modulus/pcap/bpf.h 2012-08-31 01:36:53.199825471 +0000
@@ -1235,6 +1235,7 @@
#define BPF_LSH 0x60
#define BPF_RSH 0x70
#define BPF_NEG 0x80
+#define BPF_MOD 0x90
#define BPF_JA 0x00
#define BPF_JEQ 0x10
#define BPF_JGT 0x20
diff -Naur libpcap-1.3.0/scanner.l libpcap-1.3.0-with-modulus/scanner.l
--- libpcap-1.3.0/scanner.l 2012-03-29 12:57:32.000000000 +0000
+++ libpcap-1.3.0-with-modulus/scanner.l 2012-08-31 01:36:53.225825770 +0000
@@ -329,7 +329,7 @@
sls return SLS;
[ \r\n\t] ;
-[+\-*/:\[\]!<>()&|=] return yytext[0];
+[+\-*/:\[\]!<>()&|=%] return yytext[0];
">=" return GEQ;
"<=" return LEQ;
"!=" return NEQ;
@@ -387,7 +387,7 @@
[A-Za-z0-9]([-_.A-Za-z0-9]*[.A-Za-z0-9])? {
yylval.s = sdup((char *)yytext); return ID; }
"\\"[^ !()\n\t]+ { yylval.s = sdup((char *)yytext + 1); return ID; }
-[^ \[\]\t\n\-_.A-Za-z0-9!<>()&|=]+ {
+[^ \[\]\t\n\-_.A-Za-z0-9!<>()&|=%]+ {
bpf_error("illegal token: %s", yytext); }
. { bpf_error("illegal char '%c'", *yytext); }
%%
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