[PATCH nft 3/3] evaluate: remove table from cache on delete table

[Pablo Neira Ayuso <pablo@netfilter.org>]

The following ruleset crashes nft if loaded twice, via nft -ef:

 add table inet filter
 delete table inet filter

 table inet filter {
        chain input {
                type filter hook input priority filter; policy drop;
                iifname { "eth0" } counter accept
        }
 }

If the table contains anonymous sets, such as __set0, then delete + add
table might result in nft reusing the existing stale __set0 in the cache.
The problem is that nft gets confused and it reuses the existing stale
__set0 instead of the new anonymous set __set0 with the same name.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
 src/evaluate.c                                  | 15 +++++++++++++++
 tests/shell/testcases/sets/0053echo_0           | 16 ++++++++++++++++
 tests/shell/testcases/sets/dumps/0053echo_0.nft |  6 ++++++
 3 files changed, 37 insertions(+)
 create mode 100755 tests/shell/testcases/sets/0053echo_0
 create mode 100644 tests/shell/testcases/sets/dumps/0053echo_0.nft

diff --git a/src/evaluate.c b/src/evaluate.c
index 26d73959db58..a84e9609c1ff 100644
--- a/src/evaluate.c
+++ b/src/evaluate.c
@@ -4172,6 +4172,18 @@ static int cmd_evaluate_add(struct eval_ctx *ctx, struct cmd *cmd)
 	}
 }
 
+static void table_del_cache(struct eval_ctx *ctx, struct cmd *cmd)
+{
+	struct table *table;
+
+	table = table_lookup(&cmd->handle, &ctx->nft->cache);
+	if (!table)
+		return;
+
+	list_del(&table->list);
+	table_free(table);
+}
+
 static int cmd_evaluate_delete(struct eval_ctx *ctx, struct cmd *cmd)
 {
 	switch (cmd->obj) {
@@ -4180,7 +4192,10 @@ static int cmd_evaluate_delete(struct eval_ctx *ctx, struct cmd *cmd)
 	case CMD_OBJ_SET:
 	case CMD_OBJ_RULE:
 	case CMD_OBJ_CHAIN:
+		return 0;
 	case CMD_OBJ_TABLE:
+		table_del_cache(ctx, cmd);
+		return 0;
 	case CMD_OBJ_FLOWTABLE:
 	case CMD_OBJ_COUNTER:
 	case CMD_OBJ_QUOTA:
diff --git a/tests/shell/testcases/sets/0053echo_0 b/tests/shell/testcases/sets/0053echo_0
new file mode 100755
index 000000000000..6bb03c28b268
--- /dev/null
+++ b/tests/shell/testcases/sets/0053echo_0
@@ -0,0 +1,16 @@
+#!/bin/bash
+
+set -e
+
+EXPECTED="add table inet filter
+delete table inet filter
+
+table inet filter {
+        chain input {
+                type filter hook input priority filter; policy drop;
+                iifname { lo } ip saddr { 10.0.0.0/8 } ip daddr { 192.168.100.62 } tcp dport { 2001 } counter accept
+        }
+}
+"
+
+$NFT -ef - <<< "$EXPECTED"
diff --git a/tests/shell/testcases/sets/dumps/0053echo_0.nft b/tests/shell/testcases/sets/dumps/0053echo_0.nft
new file mode 100644
index 000000000000..6a8166360ceb
--- /dev/null
+++ b/tests/shell/testcases/sets/dumps/0053echo_0.nft
@@ -0,0 +1,6 @@
+table inet filter {
+	chain input {
+		type filter hook input priority filter; policy drop;
+		iifname { "lo" } ip saddr { 10.0.0.0/8 } ip daddr { 192.168.100.62 } tcp dport { 2001 } counter packets 0 bytes 0 accept
+	}
+}
-- 
2.20.1