[PATCH nft 3/4] netlink_delinearize: and/shift postprocessing

[Florian Westphal <fw@strlen.de>]

Before this patch:
in:  frag frag-off @s4
in:  ip version @s8

out: (@nh,0,8 & 0xf0) >> 4 == @s8
out: (frag unknown & 0xfff8 [invalid type]) >> 3 == @s4

after:
out: frag frag-off >> 0 == @s4
out: ip version >> 0 == @s8

Next patch adds support for zero-shift removal.

Signed-off-by: Florian Westphal <fw@strlen.de>
---
 src/netlink_delinearize.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/src/netlink_delinearize.c b/src/netlink_delinearize.c
index 1f820e68e9f1..e37a34f37ba2 100644
--- a/src/netlink_delinearize.c
+++ b/src/netlink_delinearize.c
@@ -2414,6 +2414,13 @@ static void relational_binop_postprocess(struct rule_pp_ctx *ctx,
 		 * templates.
 		 */
 		binop_postprocess(ctx, expr, &expr->left);
+	} else if (binop->op == OP_RSHIFT && binop->left->op == OP_AND &&
+		   binop->right->etype == EXPR_VALUE && binop->left->right->etype == EXPR_VALUE) {
+		/* Handle 'ip version @s4' and similar, i.e. set lookups where the lhs needs
+		 * fixups to mask out unwanted bits AND a shift.
+		 */
+
+		binop_postprocess(ctx, binop, &binop->left);
 	}
 }
 
-- 
2.32.0