On Tue, Jan 14, 2014 at 04:25:32PM +0100, Pablo Neira Ayuso wrote:
> On Tue, Jan 14, 2014 at 12:22:52PM +0000, Patrick McHardy wrote:
> > On Tue, Jan 14, 2014 at 12:30:29PM +0100, Pablo Neira Ayuso wrote:
> > > This allows us to match ifname masks, eg.
> > >
> > > nft add rule filter output meta oifname and eth == eth counter
> > >
> > > I've been investigating other possibility, such as adding
> > > ofiname-mask, which requires several patches and transformations
> > > to make it look binop tree, but I still think this looks like
> > > a natural way (and simple, look at the patch, it's rather small)
> > > to represent this in the nftables.
> >
> > I was just going to suggest adding a shortcut for this since its exposing
> > a lot of low-level detail. The transformation should be quite easy during
> > evaluation, could you elaborate on the problems?
>
> Not really a problem but a bit more specific code to handle this case.
> I started writing support for this following several approaches, but
> after looking at my patchset I thought this approach was smaller and
> it's requiring way less specific code.
>
> The fist of my patches here (the ones that I didn't send) replace all
> NFT_META_* references in the parser by internal META_*, eg. META_MARK,
> just to prepare the addition of META_IIFNAMEMASK and META_OIFNAMEMASK.
> Then, the follow-up patch transforms the following expression that we
> got from that looks like:
>
> relational
> / \
> / \
> meta oifnamemask string
>
> to a binary op expression. These also needs some specific code in the
> delinearize path to transform the binop tree back to the expression
> above.
>
> Let me know if you have any better idea. Thanks.
Well, I think the easiest approach would be to add some code to
expr_evaluate_relational() for OP_EQ for convert the LHS of a
relational meta expression to LHS & RHS:
relational (==)
/ \
meta oifname string
=>
relational (==)
/ \
binop (&) string
/ \
meta oifname string
The attached patch uses '*' as a trigger (and obviously won't work
because the '*' is also used in the mask, but you get the idea.
netlink_delinarize adjustments are missing, but it should be pretty
trivial to add the corresponding code to postprocessing of relational
expressions.
<cmdline>:0:0-33: Evaluate
filter output meta oifname "eth*"
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
<cmdline>:1:15-33: Evaluate
filter output meta oifname "eth*"
^^^^^^^^^^^^^^^^^^^
meta oifname $eth*
<cmdline>:1:15-33: Evaluate
filter output meta oifname "eth*"
^^^^^^^^^^^^^^^^^^^
meta oifname $eth*
<cmdline>:1:15-26: Evaluate
filter output meta oifname "eth*"
^^^^^^^^^^^^
meta oifname
<cmdline>:1:28-33: Evaluate
filter output meta oifname "eth*"
^^^^^^
$eth*
<cmdline>:1:28-33: Evaluate
filter output meta oifname "eth*"
^^^^^^
"eth*"
<cmdline>:1:15-26: Evaluate
filter output meta oifname "eth*"
^^^^^^^^^^^^
meta oifname & "eth*"
<cmdline>:1:15-26: Evaluate
filter output meta oifname "eth*"
^^^^^^^^^^^^
meta oifname
<cmdline>:1:28-33: Evaluate
filter output meta oifname "eth*"
^^^^^^
"eth*"
<cmdline>:0:0-33: Error: Could not process rule: Operation not permitted
filter output meta oifname "eth*"
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
diff --git a/src/evaluate.c b/src/evaluate.c
index 4ca3294..9c659dc 100644
--- a/src/evaluate.c
+++ b/src/evaluate.c
@@ -547,7 +547,8 @@ static int expr_evaluate_binop(struct eval_ctx *ctx, struct expr **expr)
return -1;
right = op->right;
- if (expr_basetype(left)->type != TYPE_INTEGER)
+ if (expr_basetype(left)->type != TYPE_INTEGER &&
+ expr_basetype(left)->type != TYPE_STRING)
return expr_binary_error(ctx, left, op,
"Binary operation (%s) is undefined "
"for %s types",
@@ -936,6 +937,22 @@ static int expr_evaluate_relational(struct eval_ctx *ctx, struct expr **expr)
left->ops->pctx_update)
left->ops->pctx_update(&ctx->pctx, rel);
+ if (left->ops->type == EXPR_META &&
+ (left->meta.key == NFT_META_IIFNAME ||
+ left->meta.key == NFT_META_OIFNAME)) {
+ unsigned int len = div_round_up(right->len, BITS_PER_BYTE);
+ char data[len + 1];
+
+ mpz_export_data(data, right->value, BYTEORDER_HOST_ENDIAN, len);
+ if (strchr(data, '*')) {
+ left = binop_expr_alloc(&left->location, OP_AND,
+ left, expr_clone(right));
+ if (expr_evaluate(ctx, &left) < 0)
+ return -1;
+ (*expr)->left = left;
+ }
+ }
+
if (left->ops->type == EXPR_CONCAT)
return 0;
--
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