diff options
authorFlorian Westphal <>2018-11-05 17:51:18 +0100
committerFlorian Westphal <>2018-11-12 16:30:22 +0100
commit5aecb2d8bfdda4a6eea9d93079e33fc414afd8d0 (patch)
parent9677ed12a93f165fa9840fd9f8fa183390a3bd04 (diff)
arptables: pre-init hlen and ethertype
to check -s, we need to add the size of the hardware address to the arp header to obtain the offset where the ipv4 address begins: base_arphdr HW_ADDR IP_ADDR (src) IP_ADDR (target) In arptables-classic, the kernel will add dev->addr_len to the arp header base address to obtain the correct location, but we cannot do this in nf_tables, at least not at this time (we need a fixed offset value). code does: op = nft_invflags2cmp(fw->arp.invflags, ARPT_INV_TGTIP); add_addr(r, sizeof(struct arphdr) + fw->arp.arhln + ... but if user did not provide "--h-length 6" argument, then this won't work even for ethernet, as the payload expression will be told to load the first 4 bytes of arp header source mac address (sender hw address). Fix this by pre-initialising arhlen to 6. We also need to set up arhrd. Otherwise, src/dst mac can't be used: arptables -A INPUT -i lo --destination-mac 11:22:33:44:55:66 arptables v1.8.1 (nf_tables): RULE_APPEND failed (Invalid argument): rule in chain INPUT This means that matching won't work for AX25, NETROM etc, however, arptables "classic" can't parse non-ethernet addresses, and makes ETH_ALEN assumptions in several spots, so this should be fine from compatibility point of view. Signed-off-by: Florian Westphal <>
2 files changed, 20 insertions, 14 deletions
diff --git a/iptables/tests/shell/testcases/arptables/0001-arptables-save-restore_0 b/iptables/tests/shell/testcases/arptables/0001-arptables-save-restore_0
index 67265c83..73b3b0cf 100755
--- a/iptables/tests/shell/testcases/arptables/0001-arptables-save-restore_0
+++ b/iptables/tests/shell/testcases/arptables/0001-arptables-save-restore_0
@@ -11,11 +11,12 @@ set -e
$XT_MULTI arptables -F
$XT_MULTI arptables -A INPUT -s -j ACCEPT
$XT_MULTI arptables -A INPUT -d -j ACCEPT
-#$XT_MULTI arptables -A INPUT --source-mac fe:ed:ba:be:00:01 -j ACCEPT
-#$XT_MULTI arptables -A INPUT --destination-mac fe:ed:ba:be:00:01 -j ACCEPT
+$XT_MULTI arptables -A INPUT --source-mac fe:ed:ba:be:00:01 -j ACCEPT
+$XT_MULTI arptables -A INPUT --destination-mac fe:ed:ba:be:00:01 -j ACCEPT
$XT_MULTI arptables -N foo
$XT_MULTI arptables -A foo -i lo -j ACCEPT
$XT_MULTI arptables -A foo -l 6 -j ACCEPT
+$XT_MULTI arptables -A foo -j MARK --set-mark 12345
$XT_MULTI arptables -A foo --opcode Request -j ACCEPT
$XT_MULTI arptables -A foo --h-type 1 --proto-type 0x800 -j ACCEPT
$XT_MULTI arptables -A foo -l 6 --h-type 1 --proto-type 0x800 -i lo --opcode Request -j ACCEPT
@@ -34,18 +35,21 @@ DUMP='*filter
:foo -
--A INPUT -j foo
--A OUTPUT -o lo -j ACCEPT
--A OUTPUT -o eth134 -j mangle --mangle-ip-s
--A OUTPUT -o eth432 -j CLASSIFY --set-class feed:babe
--A OUTPUT -o eth432 --opcode 1 -j CLASSIFY --set-class feed:babe
--A foo -i lo -j ACCEPT
--A foo --h-length 6 -j ACCEPT
--A foo --opcode 1 -j ACCEPT
--A foo --h-type 1 --proto-type 0x800 -j ACCEPT
+-A INPUT -s --h-length 6 --h-type 1 -j ACCEPT
+-A INPUT -d --h-length 6 --h-type 1 -j ACCEPT
+-A INPUT --src-mac fe:ed:ba:be:00:01 --h-length 6 --h-type 1 -j ACCEPT
+-A INPUT --dst-mac fe:ed:ba:be:00:01 --h-length 6 --h-type 1 -j ACCEPT
+-A INPUT --h-length 6 --h-type 1 -j foo
+-A INPUT --h-length 6 --h-type 1
+-A OUTPUT -o lo --h-length 6 --h-type 1 -j ACCEPT
+-A OUTPUT -o eth134 --h-length 6 --h-type 1 -j mangle --mangle-ip-s
+-A OUTPUT -o eth432 --h-length 6 --h-type 1 -j CLASSIFY --set-class feed:babe
+-A OUTPUT -o eth432 --h-length 6 --opcode 1 --h-type 1 -j CLASSIFY --set-class feed:babe
+-A foo -i lo --h-length 6 --h-type 1 -j ACCEPT
+-A foo --h-length 6 --h-type 1 -j ACCEPT
+-A foo --h-length 6 --h-type 1 -j MARK --set-xmark 0x3039/0xffffffff
+-A foo --h-length 6 --opcode 1 --h-type 1 -j ACCEPT
+-A foo --h-length 6 --h-type 1 --proto-type 0x800 -j ACCEPT
-A foo -i lo --h-length 6 --opcode 1 --h-type 1 --proto-type 0x800 -j ACCEPT
diff --git a/iptables/xtables-arp.c b/iptables/xtables-arp.c
index a791ecce..bde35e5d 100644
--- a/iptables/xtables-arp.c
+++ b/iptables/xtables-arp.c
@@ -905,6 +905,8 @@ int do_commandarp(struct nft_handle *h, int argc, char *argv[], char **table,
struct iptables_command_state cs = {
.jumpto = "",
+ .arp.arp.arhln = 6,
+ .arp.arp.arhrd = htons(ARPHRD_ETHER),
int invert = 0;
unsigned int nsaddrs = 0, ndaddrs = 0;