In verdict map, string values are accidentally treated as verdicts.
For example:
table t {
map foo {
type ipv4_addr : verdict
elements = {
192.168.0.1 : bar
}
}
chain output {
type filter hook output priority mangle;
ip daddr vmap @foo
}
}
Though "bar" is not a valid verdict (should be "jump bar" or something),
the string is taken as the element value. Then NFTA_DATA_VALUE is sent
to the kernel instead of NFTA_DATA_VERDICT. This would be rejected by
recent kernels. On older ones (e.g. v5.4.x) that don't validate the
type, a warning can be seen when the rule is hit, because of the
corrupted verdict value:
[5120263.467627] WARNING: CPU: 12 PID: 303303 at net/netfilter/nf_tables_core.c:229 nft_do_chain+0x394/0x500 [nf_tables]
Indeed, we don't parse verdicts during evaluation, but only chain names,
which is of type string rather than verdict. For example, "jump $var" is
a verdict while "$var" is a string.
Fixes: c64457cff967 ("src: Allow goto and jump to a variable")
Signed-off-by: Xiao Liang <shaw.leon@xxxxxxxxx>
---
src/datatype.c | 12 -----------
src/evaluate.c | 3 ++-
tests/shell/testcases/nft-f/0031vmap_string_0 | 21 +++++++++++++++++++
3 files changed, 23 insertions(+), 13 deletions(-)
create mode 100755 tests/shell/testcases/nft-f/0031vmap_string_0
diff --git a/src/datatype.c b/src/datatype.c
index 2e31c858..002ed46a 100644
--- a/src/datatype.c
+++ b/src/datatype.c
@@ -321,23 +321,11 @@ static void verdict_type_print(const struct expr *expr, struct output_ctx *octx)
}
}
-static struct error_record *verdict_type_parse(struct parse_ctx *ctx,
- const struct expr *sym,
- struct expr **res)
-{
- *res = constant_expr_alloc(&sym->location, &string_type,
- BYTEORDER_HOST_ENDIAN,
- (strlen(sym->identifier) + 1) * BITS_PER_BYTE,
- sym->identifier);
- return NULL;
-}
-
const struct datatype verdict_type = {
.type = TYPE_VERDICT,
.name = "verdict",
.desc = "netfilter verdict",
.print = verdict_type_print,
- .parse = verdict_type_parse,
};
static const struct symbol_table nfproto_tbl = {
diff --git a/src/evaluate.c b/src/evaluate.c
index 919c38c5..d9c9ca28 100644
--- a/src/evaluate.c
+++ b/src/evaluate.c
@@ -2575,7 +2575,8 @@ static int stmt_evaluate_verdict(struct eval_ctx *ctx, struct stmt *stmt)
if (stmt->expr->verdict != NFT_CONTINUE)
stmt->flags |= STMT_F_TERMINAL;
if (stmt->expr->chain != NULL) {
- if (expr_evaluate(ctx, &stmt->expr->chain) < 0)
+ if (stmt_evaluate_arg(ctx, stmt, &string_type, 0, 0,
+ &stmt->expr->chain) < 0)
return -1;
if (stmt->expr->chain->etype != EXPR_VALUE) {
return expr_error(ctx->msgs, stmt->expr->chain,
diff --git a/tests/shell/testcases/nft-f/0031vmap_string_0 b/tests/shell/testcases/nft-f/0031vmap_string_0
new file mode 100755
index 00000000..2af846a4
--- /dev/null
+++ b/tests/shell/testcases/nft-f/0031vmap_string_0
@@ -0,0 +1,21 @@
+#!/bin/bash
+
+# Tests parse of corrupted verdicts
+
+set -e
+
+RULESET="
+table ip foo {
+ map bar {
+ type ipv4_addr : verdict
+ elements = {
+ 192.168.0.1 : ber
+ }
+ }
+
+ chain ber {
+ }
+}"
+
+$NFT -f - <<< "$RULESET" && exit 1
+exit 0
--
2.37.1
