From 07007c27ceebffcb6e3223768fa876c907b0d55d Mon Sep 17 00:00:00 2001 From: Phil Sutter 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 (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, ðproto, sizeof(ethproto), &inv); - fw->ethproto = ethproto; + __get_cmp_data(e, ðproto, 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