[nft PATCH 1/3] evaluate: fix a crash if we specify ether type or meta nfproto in reject

[Alvaro Neira Ayuso]

If we use a rule:
nft add rule bridge filter input \
ether type ip reject with icmp type host-unreachable

or this:

nft add rule inet filter input \
meta nfproto ipv4 reject with icmp type host-unreachable

we have a segfault because we add a network dependency when we already have
network context.

Signed-off-by: Alvaro Neira Ayuso <***@gmail.com>
---
src/evaluate.c | 51 ++++++++++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 50 insertions(+), 1 deletion(-)

diff --git a/src/evaluate.c b/src/evaluate.c
index 83ef749..3e4471e 100644
--- a/src/evaluate.c
+++ b/src/evaluate.c
@@ -19,6 +19,7 @@
#include <linux/netfilter/nf_tables.h>
#include <netinet/ip_icmp.h>
#include <netinet/icmp6.h>
+#include <net/ethernet.h>

#include <expression.h>
#include <statement.h>
@@ -1204,6 +1205,9 @@ static int stmt_reject_gen_dependency(struct eval_ctx *ctx, struct stmt *stmt,
static int stmt_evaluate_reject_family(struct eval_ctx *ctx, struct stmt *stmt,
struct expr *expr)
{
+ const struct proto_desc *desc, *base;
+ int protocol;
+
switch (ctx->pctx.family) {
case NFPROTO_ARP:
return stmt_error(ctx, stmt, "cannot use reject with arp");
@@ -1224,8 +1228,53 @@ static int stmt_evaluate_reject_family(struct eval_ctx *ctx, struct stmt *stmt,
break;
}
break;
- case NFPROTO_INET:
case NFPROTO_BRIDGE:
+ base = ctx->pctx.protocol[PROTO_BASE_LL_HDR].desc;
+ desc = ctx->pctx.protocol[PROTO_BASE_NETWORK_HDR].desc;
+ if (desc != NULL) {
+ protocol = proto_find_num(base, desc);
+ switch (protocol) {
+ case __constant_htons(ETH_P_IP):
+ if (NFPROTO_IPV4 == stmt->reject.family)
+ break;
+ case __constant_htons(ETH_P_IPV6):
+ if (NFPROTO_IPV6 == stmt->reject.family)
+ break;
+ return stmt_error(ctx, stmt,
+ "conflicting protocols specified: ip vs ip6");
+ default:
+ return stmt_error(ctx, stmt,
+ "cannot reject this ether type");
+ }
+ break;
+ }
+ if (stmt->reject.type == NFT_REJECT_ICMPX_UNREACH)
+ break;
+ if (stmt_reject_gen_dependency(ctx, stmt, expr) < 0)
+ return -1;
+ break;
+ case NFPROTO_INET:
+ base = ctx->pctx.protocol[PROTO_BASE_LL_HDR].desc;
+ desc = ctx->pctx.protocol[PROTO_BASE_NETWORK_HDR].desc;
+ if (desc != NULL) {
+ protocol = proto_find_num(base, desc);
+ switch (protocol) {
+ case NFPROTO_IPV4:
+ if (stmt->reject.family == NFPROTO_IPV4)
+ break;
+ return stmt_error(ctx, stmt,
+ "conflicting protocols specified: ip vs ip6");
+ break;
+ case NFPROTO_IPV6:
+ if (stmt->reject.family == NFPROTO_IPV6)
+ break;
+ return stmt_error(ctx, stmt,
+ "conflicting protocols specified: ip vs ip6");
+ default:
+ BUG("unsupported family");
+ }
+ break;
+ }
if (stmt->reject.type == NFT_REJECT_ICMPX_UNREACH)
break;
if (stmt_reject_gen_dependency(ctx, stmt, expr) < 0)