[PATCH nft v3 10/18] evaluate: allow boolean binop expressions with variable righthand arguments.

[Jeremy Sowden <jeremy@azazel.net>]

Hitherto, the kernel has required constant values for the xor and mask
attributes of boolean bitwise expressions.  This has meant that the
righthand argument of a boolean binop must be constant.  Now the kernel
supports passing mask and xor via registers, we can relax this
restriction.

Signed-off-by: Jeremy Sowden <jeremy@azazel.net>
---
 src/evaluate.c | 23 +++++++++++------------
 1 file changed, 11 insertions(+), 12 deletions(-)

diff --git a/src/evaluate.c b/src/evaluate.c
index 4a23b231c74d..1db175007c2d 100644
--- a/src/evaluate.c
+++ b/src/evaluate.c
@@ -1135,7 +1135,7 @@ static int expr_evaluate_bitwise(struct eval_ctx *ctx, struct expr **expr)
 	op->byteorder = left->byteorder;
 	op->len	      = left->len;
 
-	if (expr_is_constant(left))
+	if (expr_is_constant(left) && expr_is_constant(op->right))
 		return constant_binop_simplify(ctx, expr);
 	return 0;
 }
@@ -1179,23 +1179,22 @@ static int expr_evaluate_binop(struct eval_ctx *ctx, struct expr **expr)
 					 "for %s expressions",
 					 sym, expr_name(left));
 
-	if (!expr_is_constant(right))
-		return expr_binary_error(ctx->msgs, right, op,
-					 "Right hand side of binary operation "
-					 "(%s) must be constant", sym);
-
-	if (!expr_is_singleton(right))
-		return expr_binary_error(ctx->msgs, left, op,
-					 "Binary operation (%s) is undefined "
-					 "for %s expressions",
-					 sym, expr_name(right));
-
 	/* The grammar guarantees this */
 	assert(expr_basetype(left) == expr_basetype(right));
 
 	switch (op->op) {
 	case OP_LSHIFT:
 	case OP_RSHIFT:
+		if (!expr_is_constant(right))
+			return expr_binary_error(ctx->msgs, right, op,
+						 "Right hand side of binary operation "
+						 "(%s) must be constant", sym);
+
+		if (!expr_is_singleton(right))
+			return expr_binary_error(ctx->msgs, left, op,
+						 "Binary operation (%s) is undefined "
+						 "for %s expressions",
+						 sym, expr_name(right));
 		return expr_evaluate_shift(ctx, expr);
 	case OP_AND:
 	case OP_XOR:
-- 
2.25.1