path: root/src
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authorFlorian Westphal <>2023-01-23 19:03:28 +0100
committerFlorian Westphal <>2023-01-26 17:59:22 +0100
commit4cc6b20d31498d90e90ff574ce8b70276afcee8f (patch)
tree66cc2c15155ef7b90d29c9e17fa8a1e792e4db84 /src
parent6fca08c6340b0dfed1f1c0f426d86f69446c0732 (diff)
evaluate: set eval ctx for add/update statements with integer constantsHEADmaster
Eric reports that nft asserts when using integer basetype constants with 'typeof' sets. Example: table netdev t { set s { typeof ether saddr . vlan id flags dynamic,timeout } chain c { } } loads fine. But adding a rule with add/update statement fails: nft 'add rule netdev t c set update ether saddr . 0 @s' nft: netlink_linearize.c:867: netlink_gen_expr: Assertion `dreg < ctx->reg_low' failed. When the 'ether saddr . 0' concat expression is processed, there is no set definition available anymore to deduce the required size of the integer constant. nft eval step then derives the required length using the data types. '0' has integer basetype, so the deduced length is 0. The assertion triggers because serialization step finds that it needs one more register. 2 are needed to store the ethernet address, another register is needed for the vlan id. Update eval step to make the expression context store the set key information when processing the preceeding set reference, then let stmt_evaluate_set() preserve the existing context instead of zeroing it again via stmt_evaluate_arg(). This makes concat expression evaluation compute the total size needed based on the sets key definition. Reported-by: Eric Garver <> Signed-off-by: Florian Westphal <>
Diffstat (limited to 'src')
1 files changed, 30 insertions, 2 deletions
diff --git a/src/evaluate.c b/src/evaluate.c
index 61ebcbfc..2182d8f1 100644
--- a/src/evaluate.c
+++ b/src/evaluate.c
@@ -1690,6 +1690,14 @@ static int interval_set_eval(struct eval_ctx *ctx, struct set *set,
return ret;
+static void expr_evaluate_set_ref(struct eval_ctx *ctx, struct expr *expr)
+ struct set *set = expr->set;
+ expr_set_context(&ctx->ectx, set->key->dtype, set->key->len);
+ ctx->ectx.key = set->key;
static int expr_evaluate_set(struct eval_ctx *ctx, struct expr **expr)
struct expr *set = *expr, *i, *next;
@@ -2557,6 +2565,7 @@ static int expr_evaluate(struct eval_ctx *ctx, struct expr **expr)
return expr_evaluate_variable(ctx, expr);
+ expr_evaluate_set_ref(ctx, *expr);
return 0;
return expr_evaluate_value(ctx, expr);
@@ -2719,6 +2728,25 @@ static int stmt_evaluate_arg(struct eval_ctx *ctx, struct stmt *stmt,
return __stmt_evaluate_arg(ctx, stmt, dtype, len, byteorder, expr);
+/* like stmt_evaluate_arg, but keep existing context created
+ * by previous expr_evaluate().
+ *
+ * This is needed for add/update statements:
+ * ctx->ectx.key has the set key, which may be needed for 'typeof'
+ * sets: the 'add/update' expression might contain integer data types.
+ *
+ * Without the key we cannot derive the element size.
+ */
+static int stmt_evaluate_key(struct eval_ctx *ctx, struct stmt *stmt,
+ const struct datatype *dtype, unsigned int len,
+ enum byteorder byteorder, struct expr **expr)
+ if (expr_evaluate(ctx, expr) < 0)
+ return -1;
+ return __stmt_evaluate_arg(ctx, stmt, dtype, len, byteorder, expr);
static int stmt_evaluate_verdict(struct eval_ctx *ctx, struct stmt *stmt)
if (stmt_evaluate_arg(ctx, stmt, &verdict_type, 0, 0, &stmt->expr) < 0)
@@ -3952,7 +3980,7 @@ static int stmt_evaluate_set(struct eval_ctx *ctx, struct stmt *stmt)
return expr_error(ctx->msgs, stmt->set.set,
"Expression does not refer to a set");
- if (stmt_evaluate_arg(ctx, stmt,
+ if (stmt_evaluate_key(ctx, stmt,
@@ -3995,7 +4023,7 @@ static int stmt_evaluate_map(struct eval_ctx *ctx, struct stmt *stmt)
return expr_error(ctx->msgs, stmt->map.set,
"Expression does not refer to a set");
- if (stmt_evaluate_arg(ctx, stmt,
+ if (stmt_evaluate_key(ctx, stmt,