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228 lines
8.8 KiB
228 lines
8.8 KiB
2 years ago
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From a6504e3aec5cfa910f96c51319c93cd2761df9e4 Mon Sep 17 00:00:00 2001
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From: Phil Sutter <phil@nwl.cc>
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Date: Tue, 27 Sep 2022 23:19:34 +0200
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Subject: [PATCH] ebtables: Support '-p Length'
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To match on Ethernet frames using the etherproto field as length value,
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ebtables accepts the special protocol name "LENGTH". Implement this in
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ebtables-nft using a native match for 'ether type < 0x0600'.
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Since extension 802_3 matches are valid only with such Ethernet frames,
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add a local add_match() wrapper which complains if the extension is used
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without '-p Length' parameter. Legacy ebtables does this within the
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extension's final_check callback, but it's not possible here due for lack of
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fw->bitmask field access.
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While being at it, add xlate support, adjust tests and make ebtables-nft
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print the case-insensitive argument with capital 'L' like legacy
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ebtables does.
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Signed-off-by: Phil Sutter <phil@nwl.cc>
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(cherry picked from commit aa0b8b03f7c7e741ccd96360bd64d90ea8c3c3aa)
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Conflicts:
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iptables/nft-bridge.c
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- Adjusted to missing commit 7e38890c6b4fb
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("nft: prepare for dynamic register allocation")
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- Context change due to missing commit 0c0cd4340ed88
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("nft: Don't pass command state opaque to family ops callbacks")
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---
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extensions/generic.txlate | 6 +++
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extensions/libebt_802_3.t | 6 ++-
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iptables/nft-bridge.c | 47 +++++++++++++++----
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.../ebtables/0002-ebtables-save-restore_0 | 12 ++---
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4 files changed, 53 insertions(+), 18 deletions(-)
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diff --git a/extensions/generic.txlate b/extensions/generic.txlate
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index 9ae9a5b54c1b9..6779d6f86dec8 100644
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--- a/extensions/generic.txlate
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+++ b/extensions/generic.txlate
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@@ -67,6 +67,12 @@ nft add rule bridge filter FORWARD iifname != "iname" meta ibrname "ilogname" oi
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ebtables-translate -I INPUT -p ip -d 1:2:3:4:5:6/ff:ff:ff:ff:00:00
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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
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+ebtables-translate -I INPUT -p Length
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+nft insert rule bridge filter INPUT ether type < 0x0600 counter
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+
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+ebtables-translate -I INPUT -p ! Length
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+nft insert rule bridge filter INPUT ether type >= 0x0600 counter
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+
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# asterisk is not special in iptables and it is even a valid interface name
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iptables-translate -A FORWARD -i '*' -o 'eth*foo'
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nft add rule ip filter FORWARD iifname "\*" oifname "eth\*foo" counter
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diff --git a/extensions/libebt_802_3.t b/extensions/libebt_802_3.t
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index ddfb2f0a72baf..a138f35d2c756 100644
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--- a/extensions/libebt_802_3.t
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+++ b/extensions/libebt_802_3.t
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@@ -1,3 +1,5 @@
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:INPUT,FORWARD,OUTPUT
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---802_3-sap ! 0x0a -j CONTINUE;=;OK
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---802_3-type 0x000a -j RETURN;=;OK
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+--802_3-sap ! 0x0a -j CONTINUE;=;FAIL
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+--802_3-type 0x000a -j RETURN;=;FAIL
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+-p Length --802_3-sap ! 0x0a -j CONTINUE;=;OK
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+-p Length --802_3-type 0x000a -j RETURN;=;OK
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diff --git a/iptables/nft-bridge.c b/iptables/nft-bridge.c
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index 3fd03fb8de4ff..176304e9f2f23 100644
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--- a/iptables/nft-bridge.c
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+++ b/iptables/nft-bridge.c
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@@ -129,6 +129,18 @@ static int _add_action(struct nftnl_rule *r, struct iptables_command_state *cs)
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return add_action(r, cs, false);
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}
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+static int
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+nft_bridge_add_match(struct nft_handle *h, const struct ebt_entry *fw,
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+ struct nftnl_rule *r, struct xt_entry_match *m)
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+{
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+ if (!strcmp(m->u.user.name, "802_3") &&
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+ !(fw->bitmask & EBT_802_3))
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+ xtables_error(PARAMETER_PROBLEM,
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+ "For 802.3 DSAP/SSAP filtering the protocol must be LENGTH");
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+
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+ return add_match(h, r, m);
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+}
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+
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static int nft_bridge_add(struct nft_handle *h,
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struct nftnl_rule *r, void *data)
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{
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@@ -172,17 +184,25 @@ static int nft_bridge_add(struct nft_handle *h,
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}
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if ((fw->bitmask & EBT_NOPROTO) == 0) {
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+ uint16_t ethproto = fw->ethproto;
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+
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op = nft_invflags2cmp(fw->invflags, EBT_IPROTO);
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add_payload(r, offsetof(struct ethhdr, h_proto), 2,
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NFT_PAYLOAD_LL_HEADER);
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- add_cmp_u16(r, fw->ethproto, op);
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+
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+ if (fw->bitmask & EBT_802_3) {
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+ op = (op == NFT_CMP_EQ ? NFT_CMP_LT : NFT_CMP_GTE);
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+ ethproto = htons(0x0600);
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+ }
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+
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+ add_cmp_u16(r, ethproto, op);
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}
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add_compat(r, fw->ethproto, fw->invflags & EBT_IPROTO);
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for (iter = cs->match_list; iter; iter = iter->next) {
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if (iter->ismatch) {
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- if (add_match(h, r, iter->u.match->m))
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+ if (nft_bridge_add_match(h, fw, r, iter->u.match->m))
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break;
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} else {
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if (add_target(r, iter->u.watcher->t))
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@@ -239,6 +259,7 @@ static void nft_bridge_parse_payload(struct nft_xt_ctx *ctx,
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struct ebt_entry *fw = &cs->eb;
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unsigned char addr[ETH_ALEN];
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unsigned short int ethproto;
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+ uint8_t op;
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bool inv;
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int i;
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@@ -275,8 +296,14 @@ static void nft_bridge_parse_payload(struct nft_xt_ctx *ctx,
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fw->bitmask |= EBT_ISOURCE;
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break;
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case offsetof(struct ethhdr, h_proto):
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- get_cmp_data(e, ðproto, sizeof(ethproto), &inv);
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- fw->ethproto = ethproto;
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+ __get_cmp_data(e, ðproto, sizeof(ethproto), &op);
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+ if (ethproto == htons(0x0600)) {
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+ fw->bitmask |= EBT_802_3;
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+ inv = (op == NFT_CMP_GTE);
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+ } else {
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+ fw->ethproto = ethproto;
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+ inv = (op == NFT_CMP_NEQ);
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+ }
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if (inv)
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fw->invflags |= EBT_IPROTO;
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fw->bitmask &= ~EBT_NOPROTO;
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@@ -611,7 +638,7 @@ static void print_protocol(uint16_t ethproto, bool invert, unsigned int bitmask)
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printf("! ");
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if (bitmask & EBT_802_3) {
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- printf("length ");
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+ printf("Length ");
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return;
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}
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@@ -626,7 +653,7 @@ static void nft_bridge_save_rule(const void *data, unsigned int format)
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{
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const struct iptables_command_state *cs = data;
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- if (cs->eb.ethproto)
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+ if (!(cs->eb.bitmask & EBT_NOPROTO))
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print_protocol(cs->eb.ethproto, cs->eb.invflags & EBT_IPROTO,
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cs->eb.bitmask);
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if (cs->eb.bitmask & EBT_ISOURCE)
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@@ -892,7 +919,10 @@ static int nft_bridge_xlate(const void *data, struct xt_xlate *xl)
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xlate_ifname(xl, "meta obrname", cs->eb.logical_out,
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cs->eb.invflags & EBT_ILOGICALOUT);
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- if ((cs->eb.bitmask & EBT_NOPROTO) == 0) {
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+ if (cs->eb.bitmask & EBT_802_3) {
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+ xt_xlate_add(xl, "ether type %s 0x0600 ",
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+ cs->eb.invflags & EBT_IPROTO ? ">=" : "<");
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+ } else if ((cs->eb.bitmask & EBT_NOPROTO) == 0) {
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const char *implicit = NULL;
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switch (ntohs(cs->eb.ethproto)) {
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@@ -915,9 +945,6 @@ static int nft_bridge_xlate(const void *data, struct xt_xlate *xl)
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ntohs(cs->eb.ethproto));
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}
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- if (cs->eb.bitmask & EBT_802_3)
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- return 0;
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-
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if (cs->eb.bitmask & EBT_ISOURCE)
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nft_bridge_xlate_mac(xl, "saddr", cs->eb.invflags & EBT_ISOURCE,
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cs->eb.sourcemac, cs->eb.sourcemsk);
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diff --git a/iptables/tests/shell/testcases/ebtables/0002-ebtables-save-restore_0 b/iptables/tests/shell/testcases/ebtables/0002-ebtables-save-restore_0
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index b84f63a7c3672..a4fc31548e323 100755
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--- a/iptables/tests/shell/testcases/ebtables/0002-ebtables-save-restore_0
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+++ b/iptables/tests/shell/testcases/ebtables/0002-ebtables-save-restore_0
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@@ -13,8 +13,8 @@ $XT_MULTI ebtables -A INPUT -p IPv4 -i lo -j ACCEPT
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$XT_MULTI ebtables -P FORWARD DROP
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$XT_MULTI ebtables -A OUTPUT -s ff:ff:ff:ff:ff:ff/ff:ff:ff:ff:ff:ff -j DROP
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$XT_MULTI ebtables -N foo
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-$XT_MULTI ebtables -A foo --802_3-sap 0x23 -j ACCEPT
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-$XT_MULTI ebtables -A foo --802_3-sap 0xaa --802_3-type 0x1337 -j ACCEPT
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+$XT_MULTI ebtables -A foo -p length --802_3-sap 0x23 -j ACCEPT
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+$XT_MULTI ebtables -A foo -p length --802_3-sap 0xaa --802_3-type 0x1337 -j ACCEPT
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#$XT_MULTI ebtables -A foo --among-dst fe:ed:ba:be:00:01,fe:ed:ba:be:00:02,fe:ed:ba:be:00:03 -j ACCEPT
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$XT_MULTI ebtables -A foo -p ARP --arp-gratuitous -j ACCEPT
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$XT_MULTI ebtables -A foo -p ARP --arp-opcode Request -j ACCEPT
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@@ -44,7 +44,7 @@ $XT_MULTI ebtables -A foo --pkttype-type multicast -j ACCEPT
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$XT_MULTI ebtables -A foo --stp-type config -j ACCEPT
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#$XT_MULTI ebtables -A foo --vlan-id 42 -j ACCEPT
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-$XT_MULTI ebtables -A foo --802_3-sap 0x23 --limit 100 -j ACCEPT
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+$XT_MULTI ebtables -A foo -p length --802_3-sap 0x23 --limit 100 -j ACCEPT
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$XT_MULTI ebtables -A foo --pkttype-type multicast --log
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$XT_MULTI ebtables -A foo --pkttype-type multicast --limit 100 -j ACCEPT
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@@ -75,8 +75,8 @@ DUMP='*filter
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-A INPUT -p IPv4 -i lo -j ACCEPT
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-A FORWARD -j foo
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-A OUTPUT -s Broadcast -j DROP
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--A foo --802_3-sap 0x23 -j ACCEPT
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--A foo --802_3-sap 0xaa --802_3-type 0x1337 -j ACCEPT
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+-A foo -p Length --802_3-sap 0x23 -j ACCEPT
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+-A foo -p Length --802_3-sap 0xaa --802_3-type 0x1337 -j ACCEPT
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-A foo -p ARP --arp-gratuitous -j ACCEPT
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-A foo -p ARP --arp-op Request -j ACCEPT
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-A foo -p ARP --arp-ip-src 10.0.0.1 -j ACCEPT
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@@ -96,7 +96,7 @@ DUMP='*filter
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-A foo --nflog-group 1 -j CONTINUE
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-A foo --pkttype-type multicast -j ACCEPT
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-A foo --stp-type config -j ACCEPT
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--A foo --802_3-sap 0x23 --limit 100/sec --limit-burst 5 -j ACCEPT
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+-A foo -p Length --802_3-sap 0x23 --limit 100/sec --limit-burst 5 -j ACCEPT
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-A foo --pkttype-type multicast --log-level notice --log-prefix "" -j CONTINUE
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-A foo --pkttype-type multicast --limit 100/sec --limit-burst 5 -j ACCEPT
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*nat
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--
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2.38.0
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