[nft PATCH 2/3] meta: Reject nfproto value 0xffff

[Phil Sutter <phil@nwl.cc>]

Since parsing of arphrd_type happens via sym_tbl, there is no dedicated
parser function to perform the check in. So instead make use of maxval
in expr_ctx to reject the value.

While being at it, introduce a switch() to check for meta.key value in a
single place.

Signed-off-by: Phil Sutter <phil@nwl.cc>
---
 src/evaluate.c | 24 ++++++++++++++++++------
 1 file changed, 18 insertions(+), 6 deletions(-)

diff --git a/src/evaluate.c b/src/evaluate.c
index 55cd9d00d274c..ff52aefc669e0 100644
--- a/src/evaluate.c
+++ b/src/evaluate.c
@@ -23,6 +23,7 @@
 #include <netinet/icmp6.h>
 #include <net/ethernet.h>
 #include <net/if.h>
+#include <net/if_arp.h>
 #include <errno.h>
 
 #include <expression.h>
@@ -1795,14 +1796,25 @@ static int expr_evaluate_fib(struct eval_ctx *ctx, struct expr **exprp)
 static int expr_evaluate_meta(struct eval_ctx *ctx, struct expr **exprp)
 {
 	struct expr *meta = *exprp;
+	unsigned int maxval = 0;
 
-	if (ctx->pctx.family != NFPROTO_INET &&
-	    meta->flags & EXPR_F_PROTOCOL &&
-	    meta->meta.key == NFT_META_NFPROTO)
+	switch (meta->meta.key) {
+	case NFT_META_NFPROTO:
+		if (ctx->pctx.family == NFPROTO_INET ||
+		    !(meta->flags & EXPR_F_PROTOCOL))
+			break;
 		return expr_error(ctx->msgs, meta,
-					  "meta nfproto is only useful in the inet family");
-
-	return expr_evaluate_primary(ctx, exprp);
+				  "meta nfproto is only useful in the inet family");
+	case NFT_META_IIFTYPE:
+	case NFT_META_OIFTYPE:
+		maxval = ARPHRD_VOID - 1;
+		break;
+	default:
+		break;
+	}
+	__expr_set_context(&ctx->ectx, (*exprp)->dtype, (*exprp)->byteorder,
+			   (*exprp)->len, maxval);
+	return 0;
 }
 
 static int expr_evaluate_socket(struct eval_ctx *ctx, struct expr **expr)
-- 
2.22.0