nft: Fix add_bitwise_u16() on Big Endian

Type used for 'mask' and 'xor' parameters was wrong, 'int' is four bytes
on 32 or 64 bit architectures. After casting a uint16_t to int, on Big
Endian the first two bytes of data are (the leading) zero which libnftnl
then copies instead of the actual value.

This problem was noticed when using '--fragment' option:

| # iptables-nft -A FORWARD --fragment -j ACCEPT
| # nft list ruleset | grep frag-off
| ip frag-off & 0 != 0 counter packets 0 bytes 0 accept

With this fix in place, the resulting nft rule is correct:

| ip frag-off & 8191 != 0 counter packets 0 bytes 0 accept

Fixes: 2f1fbab671576 ("iptables: nft: add -f support")
Signed-off-by: Phil Sutter <phil@nwl.cc>
Acked-by: Pablo Neira Ayuso <pablo@netfilter.org>

diff --git a/iptables/nft-shared.c b/iptables/nft-shared.c
index 1c09277d85fb5b0dab276d1ab5715b7fd9a304ca..62072520db2aa9f75559e503ebefe01e09c9933c 100644 (file)
--- a/iptables/nft-shared.c
+++ b/iptables/nft-shared.c
@@ -69,7 +69,7 @@ void add_payload(struct nftnl_rule *r, int offset, int len, uint32_t base)
 }
 
 /* bitwise operation is = sreg & mask ^ xor */
-void add_bitwise_u16(struct nftnl_rule *r, int mask, int xor)
+void add_bitwise_u16(struct nftnl_rule *r, uint16_t mask, uint16_t xor)
 {
        struct nftnl_expr *expr;
 

diff --git a/iptables/nft-shared.h b/iptables/nft-shared.h
index de889ead7b60582d0c36ddb227e0e0834ff25beb..9d62913461fa4876c55b88d0e469795d003e4727 100644 (file)
--- a/iptables/nft-shared.h
+++ b/iptables/nft-shared.h
@@ -111,7 +111,7 @@ struct nft_family_ops {
 void add_meta(struct nftnl_rule *r, uint32_t key);
 void add_payload(struct nftnl_rule *r, int offset, int len, uint32_t base);
 void add_bitwise(struct nftnl_rule *r, uint8_t *mask, size_t len);
-void add_bitwise_u16(struct nftnl_rule *r, int mask, int xor);
+void add_bitwise_u16(struct nftnl_rule *r, uint16_t mask, uint16_t xor);
 void add_cmp_ptr(struct nftnl_rule *r, uint32_t op, void *data, size_t len);
 void add_cmp_u8(struct nftnl_rule *r, uint8_t val, uint32_t op);
 void add_cmp_u16(struct nftnl_rule *r, uint16_t val, uint32_t op);