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iptables/SOURCES/0082-ebtables-Support-p-Len...

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From 07007c27ceebffcb6e3223768fa876c907b0d55d Mon Sep 17 00:00:00 2001
From: Phil Sutter <phil@nwl.cc>
Date: Tue, 27 Sep 2022 23:19:34 +0200
Subject: [PATCH] ebtables: Support '-p Length'
To match on Ethernet frames using the etherproto field as length value,
ebtables accepts the special protocol name "LENGTH". Implement this in
ebtables-nft using a native match for 'ether type < 0x0600'.
Since extension 802_3 matches are valid only with such Ethernet frames,
add a local add_match() wrapper which complains if the extension is used
without '-p Length' parameter. Legacy ebtables does this within the
extension's final_check callback, but it's not possible here due for lack of
fw->bitmask field access.
While being at it, add xlate support, adjust tests and make ebtables-nft
print the case-insensitive argument with capital 'L' like legacy
ebtables does.
Signed-off-by: Phil Sutter <phil@nwl.cc>
(cherry picked from commit aa0b8b03f7c7e741ccd96360bd64d90ea8c3c3aa)
Conflicts:
iptables/nft-bridge.c
-> Adjusted to missing commit 7e38890c6b4fb
("nft: prepare for dynamic register allocation").
-> Context change due to missing commits 0c0cd4340ed88
("nft: Don't pass command state opaque to family ops callbacks") and
b5881e7f22d42 ("nft: Change whitespace printing in save_rule callback").
---
extensions/generic.txlate | 6 +++
extensions/libebt_802_3.t | 6 ++-
iptables/nft-bridge.c | 47 +++++++++++++++----
.../ebtables/0002-ebtables-save-restore_0 | 12 ++---
4 files changed, 53 insertions(+), 18 deletions(-)
diff --git a/extensions/generic.txlate b/extensions/generic.txlate
index 9ae9a5b54c1b9..6779d6f86dec8 100644
--- a/extensions/generic.txlate
+++ b/extensions/generic.txlate
@@ -67,6 +67,12 @@ nft add rule bridge filter FORWARD iifname != "iname" meta ibrname "ilogname" oi
ebtables-translate -I INPUT -p ip -d 1:2:3:4:5:6/ff:ff:ff:ff:00:00
nft insert rule bridge filter INPUT ether type 0x800 ether daddr 01:02:03:04:00:00 and ff:ff:ff:ff:00:00 == 01:02:03:04:00:00 counter
+ebtables-translate -I INPUT -p Length
+nft insert rule bridge filter INPUT ether type < 0x0600 counter
+
+ebtables-translate -I INPUT -p ! Length
+nft insert rule bridge filter INPUT ether type >= 0x0600 counter
+
# asterisk is not special in iptables and it is even a valid interface name
iptables-translate -A FORWARD -i '*' -o 'eth*foo'
nft add rule ip filter FORWARD iifname "\*" oifname "eth\*foo" counter
diff --git a/extensions/libebt_802_3.t b/extensions/libebt_802_3.t
index ddfb2f0a72baf..a138f35d2c756 100644
--- a/extensions/libebt_802_3.t
+++ b/extensions/libebt_802_3.t
@@ -1,3 +1,5 @@
:INPUT,FORWARD,OUTPUT
---802_3-sap ! 0x0a -j CONTINUE;=;OK
---802_3-type 0x000a -j RETURN;=;OK
+--802_3-sap ! 0x0a -j CONTINUE;=;FAIL
+--802_3-type 0x000a -j RETURN;=;FAIL
+-p Length --802_3-sap ! 0x0a -j CONTINUE;=;OK
+-p Length --802_3-type 0x000a -j RETURN;=;OK
diff --git a/iptables/nft-bridge.c b/iptables/nft-bridge.c
index 9cc6f87b28fe0..fbed1616253a6 100644
--- a/iptables/nft-bridge.c
+++ b/iptables/nft-bridge.c
@@ -129,6 +129,18 @@ static int _add_action(struct nftnl_rule *r, struct iptables_command_state *cs)
return add_action(r, cs, false);
}
+static int
+nft_bridge_add_match(struct nft_handle *h, const struct ebt_entry *fw,
+ struct nftnl_rule *r, struct xt_entry_match *m)
+{
+ if (!strcmp(m->u.user.name, "802_3") &&
+ !(fw->bitmask & EBT_802_3))
+ xtables_error(PARAMETER_PROBLEM,
+ "For 802.3 DSAP/SSAP filtering the protocol must be LENGTH");
+
+ return add_match(h, r, m);
+}
+
static int nft_bridge_add(struct nft_handle *h,
struct nftnl_rule *r, void *data)
{
@@ -172,17 +184,25 @@ static int nft_bridge_add(struct nft_handle *h,
}
if ((fw->bitmask & EBT_NOPROTO) == 0) {
+ uint16_t ethproto = fw->ethproto;
+
op = nft_invflags2cmp(fw->invflags, EBT_IPROTO);
add_payload(r, offsetof(struct ethhdr, h_proto), 2,
NFT_PAYLOAD_LL_HEADER);
- add_cmp_u16(r, fw->ethproto, op);
+
+ if (fw->bitmask & EBT_802_3) {
+ op = (op == NFT_CMP_EQ ? NFT_CMP_LT : NFT_CMP_GTE);
+ ethproto = htons(0x0600);
+ }
+
+ add_cmp_u16(r, ethproto, op);
}
add_compat(r, fw->ethproto, fw->invflags & EBT_IPROTO);
for (iter = cs->match_list; iter; iter = iter->next) {
if (iter->ismatch) {
- if (add_match(h, r, iter->u.match->m))
+ if (nft_bridge_add_match(h, fw, r, iter->u.match->m))
break;
} else {
if (add_target(r, iter->u.watcher->t))
@@ -239,6 +259,7 @@ static void nft_bridge_parse_payload(struct nft_xt_ctx *ctx,
struct ebt_entry *fw = &cs->eb;
unsigned char addr[ETH_ALEN];
unsigned short int ethproto;
+ uint8_t op;
bool inv;
int i;
@@ -275,8 +296,14 @@ static void nft_bridge_parse_payload(struct nft_xt_ctx *ctx,
fw->bitmask |= EBT_ISOURCE;
break;
case offsetof(struct ethhdr, h_proto):
- get_cmp_data(e, &ethproto, sizeof(ethproto), &inv);
- fw->ethproto = ethproto;
+ __get_cmp_data(e, &ethproto, sizeof(ethproto), &op);
+ if (ethproto == htons(0x0600)) {
+ fw->bitmask |= EBT_802_3;
+ inv = (op == NFT_CMP_GTE);
+ } else {
+ fw->ethproto = ethproto;
+ inv = (op == NFT_CMP_NEQ);
+ }
if (inv)
fw->invflags |= EBT_IPROTO;
fw->bitmask &= ~EBT_NOPROTO;
@@ -620,7 +647,7 @@ static void print_protocol(uint16_t ethproto, bool invert, unsigned int bitmask)
printf("! ");
if (bitmask & EBT_802_3) {
- printf("length ");
+ printf("Length ");
return;
}
@@ -635,7 +662,7 @@ static void nft_bridge_save_rule(const void *data, unsigned int format)
{
const struct iptables_command_state *cs = data;
- if (cs->eb.ethproto)
+ if (!(cs->eb.bitmask & EBT_NOPROTO))
print_protocol(cs->eb.ethproto, cs->eb.invflags & EBT_IPROTO,
cs->eb.bitmask);
if (cs->eb.bitmask & EBT_ISOURCE)
@@ -866,7 +893,10 @@ static int nft_bridge_xlate(const void *data, struct xt_xlate *xl)
xlate_ifname(xl, "meta obrname", cs->eb.logical_out,
cs->eb.invflags & EBT_ILOGICALOUT);
- if ((cs->eb.bitmask & EBT_NOPROTO) == 0) {
+ if (cs->eb.bitmask & EBT_802_3) {
+ xt_xlate_add(xl, "ether type %s 0x0600 ",
+ cs->eb.invflags & EBT_IPROTO ? ">=" : "<");
+ } else if ((cs->eb.bitmask & EBT_NOPROTO) == 0) {
const char *implicit = NULL;
switch (ntohs(cs->eb.ethproto)) {
@@ -889,9 +919,6 @@ static int nft_bridge_xlate(const void *data, struct xt_xlate *xl)
ntohs(cs->eb.ethproto));
}
- if (cs->eb.bitmask & EBT_802_3)
- return 0;
-
if (cs->eb.bitmask & EBT_ISOURCE)
nft_bridge_xlate_mac(xl, "saddr", cs->eb.invflags & EBT_ISOURCE,
cs->eb.sourcemac, cs->eb.sourcemsk);
diff --git a/iptables/tests/shell/testcases/ebtables/0002-ebtables-save-restore_0 b/iptables/tests/shell/testcases/ebtables/0002-ebtables-save-restore_0
index b84f63a7c3672..a4fc31548e323 100755
--- a/iptables/tests/shell/testcases/ebtables/0002-ebtables-save-restore_0
+++ b/iptables/tests/shell/testcases/ebtables/0002-ebtables-save-restore_0
@@ -13,8 +13,8 @@ $XT_MULTI ebtables -A INPUT -p IPv4 -i lo -j ACCEPT
$XT_MULTI ebtables -P FORWARD DROP
$XT_MULTI ebtables -A OUTPUT -s ff:ff:ff:ff:ff:ff/ff:ff:ff:ff:ff:ff -j DROP
$XT_MULTI ebtables -N foo
-$XT_MULTI ebtables -A foo --802_3-sap 0x23 -j ACCEPT
-$XT_MULTI ebtables -A foo --802_3-sap 0xaa --802_3-type 0x1337 -j ACCEPT
+$XT_MULTI ebtables -A foo -p length --802_3-sap 0x23 -j ACCEPT
+$XT_MULTI ebtables -A foo -p length --802_3-sap 0xaa --802_3-type 0x1337 -j ACCEPT
#$XT_MULTI ebtables -A foo --among-dst fe:ed:ba:be:00:01,fe:ed:ba:be:00:02,fe:ed:ba:be:00:03 -j ACCEPT
$XT_MULTI ebtables -A foo -p ARP --arp-gratuitous -j ACCEPT
$XT_MULTI ebtables -A foo -p ARP --arp-opcode Request -j ACCEPT
@@ -44,7 +44,7 @@ $XT_MULTI ebtables -A foo --pkttype-type multicast -j ACCEPT
$XT_MULTI ebtables -A foo --stp-type config -j ACCEPT
#$XT_MULTI ebtables -A foo --vlan-id 42 -j ACCEPT
-$XT_MULTI ebtables -A foo --802_3-sap 0x23 --limit 100 -j ACCEPT
+$XT_MULTI ebtables -A foo -p length --802_3-sap 0x23 --limit 100 -j ACCEPT
$XT_MULTI ebtables -A foo --pkttype-type multicast --log
$XT_MULTI ebtables -A foo --pkttype-type multicast --limit 100 -j ACCEPT
@@ -75,8 +75,8 @@ DUMP='*filter
-A INPUT -p IPv4 -i lo -j ACCEPT
-A FORWARD -j foo
-A OUTPUT -s Broadcast -j DROP
--A foo --802_3-sap 0x23 -j ACCEPT
--A foo --802_3-sap 0xaa --802_3-type 0x1337 -j ACCEPT
+-A foo -p Length --802_3-sap 0x23 -j ACCEPT
+-A foo -p Length --802_3-sap 0xaa --802_3-type 0x1337 -j ACCEPT
-A foo -p ARP --arp-gratuitous -j ACCEPT
-A foo -p ARP --arp-op Request -j ACCEPT
-A foo -p ARP --arp-ip-src 10.0.0.1 -j ACCEPT
@@ -96,7 +96,7 @@ DUMP='*filter
-A foo --nflog-group 1 -j CONTINUE
-A foo --pkttype-type multicast -j ACCEPT
-A foo --stp-type config -j ACCEPT
--A foo --802_3-sap 0x23 --limit 100/sec --limit-burst 5 -j ACCEPT
+-A foo -p Length --802_3-sap 0x23 --limit 100/sec --limit-burst 5 -j ACCEPT
-A foo --pkttype-type multicast --log-level notice --log-prefix "" -j CONTINUE
-A foo --pkttype-type multicast --limit 100/sec --limit-burst 5 -j ACCEPT
*nat
--
2.40.0
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