From: Jeremy Sowden <jeremy@xxxxxxxxxx>
If we want to left-shift a value of narrower type and assign the result
to a variable of a wider type, we are constrained to only shifting up to
the width of the narrower type. Thus:
add rule t c meta mark set ip dscp << 2
works, but:
add rule t c meta mark set ip dscp << 8
does not, even though the lvalue is large enough to accommodate the
result.
Evaluation of the left-hand operand of a shift overwrites the `len`
field of the evaluation context when `expr_evaluate_primary` is called.
Instead, preserve the `len` value of the evaluation context for shifts,
and support shifts up to that size, even if they are larger than the
length of the left operand.
Update netlink_delinearize.c to handle the case where the length of a
shift expression does not match that of its left-hand operand.
Signed-off-by: Jeremy Sowden <jeremy@xxxxxxxxxx>
Signed-off-by: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx>
---
src/evaluate.c | 23 ++++++++++++++---------
src/netlink_delinearize.c | 4 ++--
2 files changed, 16 insertions(+), 11 deletions(-)
diff --git a/src/evaluate.c b/src/evaluate.c
index 21d360493ceb..06aa71561619 100644
--- a/src/evaluate.c
+++ b/src/evaluate.c
@@ -1289,14 +1289,18 @@ static int constant_binop_simplify(struct eval_ctx *ctx, struct expr **expr)
static int expr_evaluate_shift(struct eval_ctx *ctx, struct expr **expr)
{
struct expr *op = *expr, *left = op->left, *right = op->right;
+ unsigned int shift = mpz_get_uint32(right->value);
+ unsigned int op_len = left->len;
- if (mpz_get_uint32(right->value) >= left->len)
- return expr_binary_error(ctx->msgs, right, left,
- "%s shift of %u bits is undefined "
- "for type of %u bits width",
- op->op == OP_LSHIFT ? "Left" : "Right",
- mpz_get_uint32(right->value),
- left->len);
+ if (shift >= op_len) {
+ if (shift >= ctx->ectx.len)
+ return expr_binary_error(ctx->msgs, right, left,
+ "%s shift of %u bits is undefined for type of %u bits width",
+ op->op == OP_LSHIFT ? "Left" : "Right",
+ shift,
+ op_len);
+ op_len = ctx->ectx.len;
+ }
/* Both sides need to be in host byte order */
if (byteorder_conversion(ctx, &op->left, BYTEORDER_HOST_ENDIAN) < 0)
@@ -1306,7 +1310,7 @@ static int expr_evaluate_shift(struct eval_ctx *ctx, struct expr **expr)
return -1;
op->byteorder = BYTEORDER_HOST_ENDIAN;
- op->len = left->len;
+ op->len = op_len;
if (expr_is_constant(left))
return constant_binop_simplify(ctx, expr);
@@ -1339,6 +1343,7 @@ static int expr_evaluate_binop(struct eval_ctx *ctx, struct expr **expr)
{
struct expr *op = *expr, *left, *right;
const char *sym = expr_op_symbols[op->op];
+ unsigned int ectx_len = ctx->ectx.len;
if (expr_evaluate(ctx, &op->left) < 0)
return -1;
@@ -1346,7 +1351,7 @@ static int expr_evaluate_binop(struct eval_ctx *ctx, struct expr **expr)
if (op->op == OP_LSHIFT || op->op == OP_RSHIFT)
__expr_set_context(&ctx->ectx, &integer_type,
- left->byteorder, ctx->ectx.len, 0);
+ left->byteorder, ectx_len, 0);
if (expr_evaluate(ctx, &op->right) < 0)
return -1;
right = op->right;
diff --git a/src/netlink_delinearize.c b/src/netlink_delinearize.c
index c1b4c1148d33..4dc28ed8e651 100644
--- a/src/netlink_delinearize.c
+++ b/src/netlink_delinearize.c
@@ -489,7 +489,7 @@ static struct expr *netlink_parse_bitwise_bool(struct netlink_parse_ctx *ctx,
mpz_ior(m, m, o);
}
- if (left->len > 0 && mpz_scan0(m, 0) == left->len) {
+ if (left->len > 0 && mpz_scan0(m, 0) >= left->len) {
/* mask encompasses the entire value */
expr_free(mask);
} else {
@@ -537,7 +537,7 @@ static struct expr *netlink_parse_bitwise_shift(struct netlink_parse_ctx *ctx,
right->byteorder = BYTEORDER_HOST_ENDIAN;
expr = binop_expr_alloc(loc, op, left, right);
- expr->len = left->len;
+ expr->len = nftnl_expr_get_u32(nle, NFTNL_EXPR_BITWISE_LEN) * BITS_PER_BYTE;
return expr;
}
--
2.30.2
