[PATCH 6.6 035/158] netfilter: br_netfilter: skip conntrack input hook for promisc packets

Greg Kroah-Hartman
2024-04-23T21:43:00Z

From: Pablo Neira Ayuso <pablo@netfilter.org>

[ Upstream commit 751de2012eafa4d46d8081056761fa0e9cc8a178 ]

For historical reasons, when bridge device is in promisc mode, packets
that are directed to the taps follow bridge input hook path. This patch
adds a workaround to reset conntrack for these packets.

Jianbo Liu reports warning splats in their test infrastructure where
cloned packets reach the br_netfilter input hook to confirm the
conntrack object.

Scratch one bit from BR_INPUT_SKB_CB to annotate that this packet has
reached the input hook because it is passed up to the bridge device to
reach the taps.

[ 57.571874] WARNING: CPU: 1 PID: 0 at net/bridge/br_netfilter_hooks.c:616 br_nf_local_in+0x157/0x180 [br_netfilter]
[ 57.572749] Modules linked in: xt_MASQUERADE nf_conntrack_netlink nfnetlink iptable_nat xt_addrtype xt_conntrack nf_nat br_netfilter rpcsec_gss_krb5 auth_rpcgss oid_registry overlay rpcrdma rdma_ucm ib_iser libiscsi scsi_transport_isc si ib_umad rdma_cm ib_ipoib iw_cm ib_cm mlx5_ib ib_uverbs ib_core mlx5ctl mlx5_core
[ 57.575158] CPU: 1 PID: 0 Comm: swapper/1 Not tainted 6.8.0+ #19
[ 57.575700] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014
[ 57.576662] RIP: 0010:br_nf_local_in+0x157/0x180 [br_netfilter]
[ 57.577195] Code: fe ff ff 41 bd 04 00 00 00 be 04 00 00 00 e9 4a ff ff ff be 04 00 00 00 48 89 ef e8 f3 a9 3c e1 66 83 ad b4 00 00 00 04 eb 91 <0f> 0b e9 f1 fe ff ff 0f 0b e9 df fe ff ff 48 89 df e8 b3 53 47 e1
[ 57.578722] RSP: 0018:ffff88885f845a08 EFLAGS: 00010202
[ 57.579207] RAX: 0000000000000002 RBX: ffff88812dfe8000 RCX: 0000000000000000
[ 57.579830] RDX: ffff88885f845a60 RSI: ffff8881022dc300 RDI: 0000000000000000
[ 57.580454] RBP: ffff88885f845a60 R08: 0000000000000001 R09: 0000000000000003
[ 57.581076] R10: 00000000ffff1300 R11: 0000000000000002 R12: 0000000000000000
[ 57.581695] R13: ffff8881047ffe00 R14: ffff888108dbee00 R15: ffff88814519b800
[ 57.582313] FS: 0000000000000000(0000) GS:ffff88885f840000(0000) knlGS:0000000000000000
[ 57.583040] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 57.583564] CR2: 000000c4206aa000 CR3: 0000000103847001 CR4: 0000000000370eb0
[ 57.584194] DR0: 0000000000000000 DR1: 0000000000000000 DR2:
0000000000000000
[ 57.584820] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7:
0000000000000400
[ 57.585440] Call Trace:
[ 57.585721] <IRQ>
[ 57.585976] ? __warn+0x7d/0x130
[ 57.586323] ? br_nf_local_in+0x157/0x180 [br_netfilter]
[ 57.586811] ? report_bug+0xf1/0x1c0
[ 57.587177] ? handle_bug+0x3f/0x70
[ 57.587539] ? exc_invalid_op+0x13/0x60
[ 57.587929] ? asm_exc_invalid_op+0x16/0x20
[ 57.588336] ? br_nf_local_in+0x157/0x180 [br_netfilter]
[ 57.588825] nf_hook_slow+0x3d/0xd0
[ 57.589188] ? br_handle_vlan+0x4b/0x110
[ 57.589579] br_pass_frame_up+0xfc/0x150
[ 57.589970] ? br_port_flags_change+0x40/0x40
[ 57.590396] br_handle_frame_finish+0x346/0x5e0
[ 57.590837] ? ipt_do_table+0x32e/0x430
[ 57.591221] ? br_handle_local_finish+0x20/0x20
[ 57.591656] br_nf_hook_thresh+0x4b/0xf0 [br_netfilter]
[ 57.592286] ? br_handle_local_finish+0x20/0x20
[ 57.592802] br_nf_pre_routing_finish+0x178/0x480 [br_netfilter]
[ 57.593348] ? br_handle_local_finish+0x20/0x20
[ 57.593782] ? nf_nat_ipv4_pre_routing+0x25/0x60 [nf_nat]
[ 57.594279] br_nf_pre_routing+0x24c/0x550 [br_netfilter]
[ 57.594780] ? br_nf_hook_thresh+0xf0/0xf0 [br_netfilter]
[ 57.595280] br_handle_frame+0x1f3/0x3d0
[ 57.595676] ? br_handle_local_finish+0x20/0x20
[ 57.596118] ? br_handle_frame_finish+0x5e0/0x5e0
[ 57.596566] __netif_receive_skb_core+0x25b/0xfc0
[ 57.597017] ? __napi_build_skb+0x37/0x40
[ 57.597418] __netif_receive_skb_list_core+0xfb/0x220

Fixes: 62e7151ae3eb ("netfilter: bridge: confirm multicast packets before passing them up the stack")
Reported-by: Jianbo Liu <jianbol@nvidia.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/bridge/br_input.c | 15 +++++++++++----
net/bridge/br_netfilter_hooks.c | 6 ++++++
net/bridge/br_private.h | 1 +
net/bridge/netfilter/nf_conntrack_bridge.c | 14 ++++++++++----
4 files changed, 28 insertions(+), 8 deletions(-)

diff --git a/net/bridge/br_input.c b/net/bridge/br_input.c
index c729528b5e85f..e09000e38d071 100644
--- a/net/bridge/br_input.c
+++ b/net/bridge/br_input.c
@@ -30,7 +30,7 @@ br_netif_receive_skb(struct net *net, struct sock *sk, struct sk_buff *skb)
return netif_receive_skb(skb);
}

-static int br_pass_frame_up(struct sk_buff *skb)
+static int br_pass_frame_up(struct sk_buff *skb, bool promisc)
{
struct net_device *indev, *brdev = BR_INPUT_SKB_CB(skb)->brdev;
struct net_bridge *br = netdev_priv(brdev);
@@ -65,6 +65,8 @@ static int br_pass_frame_up(struct sk_buff *skb)
br_multicast_count(br, NULL, skb, br_multicast_igmp_type(skb),
BR_MCAST_DIR_TX);

+ BR_INPUT_SKB_CB(skb)->promisc = promisc;
+
return NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN,
dev_net(indev), NULL, skb, indev, NULL,
br_netif_receive_skb);
@@ -82,6 +84,7 @@ int br_handle_frame_finish(struct net *net, struct sock *sk, struct sk_buff *skb
struct net_bridge_mcast *brmctx;
struct net_bridge_vlan *vlan;
struct net_bridge *br;
+ bool promisc;
u16 vid = 0;
u8 state;

@@ -137,7 +140,9 @@ int br_handle_frame_finish(struct net *net, struct sock *sk, struct sk_buff *skb
if (p->flags & BR_LEARNING)
br_fdb_update(br, p, eth_hdr(skb)->h_source, vid, 0);

- local_rcv = !!(br->dev->flags & IFF_PROMISC);
+ promisc = !!(br->dev->flags & IFF_PROMISC);
+ local_rcv = promisc;
+
if (is_multicast_ether_addr(eth_hdr(skb)->h_dest)) {
/* by definition the broadcast is also a multicast address */
if (is_broadcast_ether_addr(eth_hdr(skb)->h_dest)) {
@@ -200,7 +205,7 @@ int br_handle_frame_finish(struct net *net, struct sock *sk, struct sk_buff *skb
unsigned long now = jiffies;

if (test_bit(BR_FDB_LOCAL, &dst->flags))
- return br_pass_frame_up(skb);
+ return br_pass_frame_up(skb, false);

if (now != dst->used)
dst->used = now;
@@ -213,7 +218,7 @@ int br_handle_frame_finish(struct net *net, struct sock *sk, struct sk_buff *skb
}

if (local_rcv)
- return br_pass_frame_up(skb);
+ return br_pass_frame_up(skb, promisc);

out:
return 0;
@@ -386,6 +391,8 @@ static rx_handler_result_t br_handle_frame(struct sk_buff **pskb)
goto forward;
}

+ BR_INPUT_SKB_CB(skb)->promisc = false;
+
/* The else clause should be hit when nf_hook():
* - returns < 0 (drop/error)
* - returns = 0 (stolen/nf_queue)
diff --git a/net/bridge/br_netfilter_hooks.c b/net/bridge/br_netfilter_hooks.c
index 6ef67030b4db3..d848c84ed030d 100644
--- a/net/bridge/br_netfilter_hooks.c
+++ b/net/bridge/br_netfilter_hooks.c
@@ -600,11 +600,17 @@ static unsigned int br_nf_local_in(void *priv,
struct sk_buff *skb,
const struct nf_hook_state *state)
{
+ bool promisc = BR_INPUT_SKB_CB(skb)->promisc;
struct nf_conntrack *nfct = skb_nfct(skb);
const struct nf_ct_hook *ct_hook;
struct nf_conn *ct;
int ret;

+ if (promisc) {
+ nf_reset_ct(skb);
+ return NF_ACCEPT;
+ }
+
if (!nfct || skb->pkt_type == PACKET_HOST)
return NF_ACCEPT;

diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h
index 82e63908dce8a..e4f1a08322da9 100644
--- a/net/bridge/br_private.h
+++ b/net/bridge/br_private.h
@@ -583,6 +583,7 @@ struct br_input_skb_cb {
#endif
u8 proxyarp_replied:1;
u8 src_port_isolated:1;
+ u8 promisc:1;
#ifdef CONFIG_BRIDGE_VLAN_FILTERING
u8 vlan_filtered:1;
#endif
diff --git a/net/bridge/netfilter/nf_conntrack_bridge.c b/net/bridge/netfilter/nf_conntrack_bridge.c
index d32fce70d797d..6ef04f9fe481b 100644
--- a/net/bridge/netfilter/nf_conntrack_bridge.c
+++ b/net/bridge/netfilter/nf_conntrack_bridge.c
@@ -294,18 +294,24 @@ static unsigned int nf_ct_bridge_pre(void *priv, struct sk_buff *skb,
static unsigned int nf_ct_bridge_in(void *priv, struct sk_buff *skb,
const struct nf_hook_state *state)
{
- enum ip_conntrack_info ctinfo;
+ bool promisc = BR_INPUT_SKB_CB(skb)->promisc;
+ struct nf_conntrack *nfct = skb_nfct(skb);
struct nf_conn *ct;

- if (skb->pkt_type == PACKET_HOST)
+ if (promisc) {
+ nf_reset_ct(skb);
+ return NF_ACCEPT;
+ }
+
+ if (!nfct || skb->pkt_type == PACKET_HOST)
return NF_ACCEPT;

/* nf_conntrack_confirm() cannot handle concurrent clones,
* this happens for broad/multicast frames with e.g. macvlan on top
* of the bridge device.
*/
- ct = nf_ct_get(skb, &ctinfo);
- if (!ct || nf_ct_is_confirmed(ct) || nf_ct_is_template(ct))
+ ct = container_of(nfct, struct nf_conn, ct_general);
+ if (nf_ct_is_confirmed(ct) || nf_ct_is_template(ct))
return NF_ACCEPT;

/* let inet prerouting call conntrack again */
--
2.43.0