[Devel] [PATCH RHEL9 COMMIT] ms/netfilter: bridge: replace physindev with physinif in nf_bridge_info

Konstantin Khorenko khorenko at virtuozzo.com
Tue Jan 23 22:13:53 MSK 2024


The commit is pushed to "branch-rh9-5.14.0-362.8.1.vz9.35.x-ovz" and will appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh9-5.14.0-362.8.1.vz9.35.7
------>
commit ac39f3b02e36b83cc47573c4b6a11d24b5a5d7b1
Author: Pavel Tikhomirov <ptikhomirov at virtuozzo.com>
Date:   Tue Jan 23 11:16:21 2024 +0800

    ms/netfilter: bridge: replace physindev with physinif in nf_bridge_info
    
    An skb can be added to a neigh->arp_queue while waiting for an arp
    reply. Where original skb's skb->dev can be different to neigh's
    neigh->dev. For instance in case of bridging dnated skb from one veth to
    another, the skb would be added to a neigh->arp_queue of the bridge.
    
    As skb->dev can be reset back to nf_bridge->physindev and used, and as
    there is no explicit mechanism that prevents this physindev from been
    freed under us (for instance neigh_flush_dev doesn't cleanup skbs from
    different device's neigh queue) we can crash on e.g. this stack:
    
    arp_process
      neigh_update
        skb = __skb_dequeue(&neigh->arp_queue)
          neigh_resolve_output(..., skb)
            ...
              br_nf_dev_xmit
                br_nf_pre_routing_finish_bridge_slow
                  skb->dev = nf_bridge->physindev
                  br_handle_frame_finish
    
    Let's use plain ifindex instead of net_device link. To peek into the
    original net_device we will use dev_get_by_index_rcu(). Thus either we
    get device and are safe to use it or we don't get it and drop skb.
    
    mFixes: c4e70a87d975 ("netfilter: bridge: rename br_netfilter.c to br_netfilter_hooks.c")
    Suggested-by: Florian Westphal <fw at strlen.de>
    Signed-off-by: Pavel Tikhomirov <ptikhomirov at virtuozzo.com>
    Signed-off-by: Pablo Neira Ayuso <pablo at netfilter.org>
    
    (cherry picked from commit 9874808878d9eed407e3977fd11fee49de1e1d86)
    https://virtuozzo.atlassian.net/browse/PSBM-153269
    Signed-off-by: Pavel Tikhomirov <ptikhomirov at virtuozzo.com>
    
    ======
    Patchset description:
    netlink: bridge: fix nf_bridge->physindev use after free
    
    This is a backport of mainstream version of the fix to vz9:
    https://lore.kernel.org/netdev/20240111150645.85637-1-ptikhomirov@virtuozzo.com/
    
    https://virtuozzo.atlassian.net/browse/PSBM-153269
    
    Feature: fix ms/net
---
 include/linux/netfilter_bridge.h    |  4 ++--
 include/linux/skbuff.h              |  2 +-
 net/bridge/br_netfilter_hooks.c     | 42 ++++++++++++++++++++++++++++++-------
 net/bridge/br_netfilter_ipv6.c      | 14 +++++++++----
 net/ipv4/netfilter/nf_reject_ipv4.c |  9 +++++---
 net/ipv6/netfilter/nf_reject_ipv6.c | 11 +++++++---
 6 files changed, 61 insertions(+), 21 deletions(-)

diff --git a/include/linux/netfilter_bridge.h b/include/linux/netfilter_bridge.h
index e927b9a15a55..743475ca7e9d 100644
--- a/include/linux/netfilter_bridge.h
+++ b/include/linux/netfilter_bridge.h
@@ -42,7 +42,7 @@ static inline int nf_bridge_get_physinif(const struct sk_buff *skb)
 	if (!nf_bridge)
 		return 0;
 
-	return nf_bridge->physindev ? nf_bridge->physindev->ifindex : 0;
+	return nf_bridge->physinif;
 }
 
 static inline int nf_bridge_get_physoutif(const struct sk_buff *skb)
@@ -60,7 +60,7 @@ nf_bridge_get_physindev(const struct sk_buff *skb, struct net *net)
 {
 	const struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
 
-	return nf_bridge ? nf_bridge->physindev : NULL;
+	return nf_bridge ? dev_get_by_index_rcu(net, nf_bridge->physinif) : NULL;
 }
 
 static inline struct net_device *
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index a6d26a08a255..4714ce0afffb 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -263,7 +263,7 @@ struct nf_bridge_info {
 	u8			bridged_dnat:1;
 	u8			sabotage_in_done:1;
 	__u16			frag_max_size;
-	struct net_device	*physindev;
+	int			physinif;
 
 	/* always valid & non-NULL from FORWARD on, for physdev match */
 	struct net_device	*physoutdev;
diff --git a/net/bridge/br_netfilter_hooks.c b/net/bridge/br_netfilter_hooks.c
index 4bc6761517bb..98598672f938 100644
--- a/net/bridge/br_netfilter_hooks.c
+++ b/net/bridge/br_netfilter_hooks.c
@@ -278,8 +278,17 @@ int br_nf_pre_routing_finish_bridge(struct net *net, struct sock *sk, struct sk_
 		int ret;
 
 		if ((neigh->nud_state & NUD_CONNECTED) && neigh->hh.hh_len) {
+			struct net_device *br_indev;
+
+			br_indev = nf_bridge_get_physindev(skb, net);
+			if (!br_indev) {
+				neigh_release(neigh);
+				goto free_skb;
+			}
+
 			neigh_hh_bridge(&neigh->hh, skb);
-			skb->dev = nf_bridge->physindev;
+			skb->dev = br_indev;
+
 			ret = br_handle_frame_finish(net, sk, skb);
 		} else {
 			/* the neighbour function below overwrites the complete
@@ -351,12 +360,18 @@ br_nf_ipv4_daddr_was_changed(const struct sk_buff *skb,
  */
 static int br_nf_pre_routing_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
 {
-	struct net_device *dev = skb->dev;
+	struct net_device *dev = skb->dev, *br_indev;
 	struct iphdr *iph = ip_hdr(skb);
 	struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
 	struct rtable *rt;
 	int err;
 
+	br_indev = nf_bridge_get_physindev(skb, net);
+	if (!br_indev) {
+		kfree_skb(skb);
+		return 0;
+	}
+
 	nf_bridge->frag_max_size = IPCB(skb)->frag_max_size;
 
 	if (nf_bridge->pkt_otherhost) {
@@ -396,7 +411,7 @@ static int br_nf_pre_routing_finish(struct net *net, struct sock *sk, struct sk_
 		} else {
 			if (skb_dst(skb)->dev == dev) {
 bridged_dnat:
-				skb->dev = nf_bridge->physindev;
+				skb->dev = br_indev;
 				nf_bridge_update_protocol(skb);
 				nf_bridge_push_encap_header(skb);
 				br_nf_hook_thresh(NF_BR_PRE_ROUTING,
@@ -409,7 +424,7 @@ static int br_nf_pre_routing_finish(struct net *net, struct sock *sk, struct sk_
 			skb->pkt_type = PACKET_HOST;
 		}
 	} else {
-		rt = bridge_parent_rtable(nf_bridge->physindev);
+		rt = bridge_parent_rtable(br_indev);
 		if (!rt) {
 			kfree_skb(skb);
 			return 0;
@@ -418,7 +433,7 @@ static int br_nf_pre_routing_finish(struct net *net, struct sock *sk, struct sk_
 		skb_dst_set_noref(skb, &rt->dst);
 	}
 
-	skb->dev = nf_bridge->physindev;
+	skb->dev = br_indev;
 	nf_bridge_update_protocol(skb);
 	nf_bridge_push_encap_header(skb);
 	br_nf_hook_thresh(NF_BR_PRE_ROUTING, net, sk, skb, skb->dev, NULL,
@@ -455,7 +470,7 @@ struct net_device *setup_pre_routing(struct sk_buff *skb, const struct net *net)
 	}
 
 	nf_bridge->in_prerouting = 1;
-	nf_bridge->physindev = skb->dev;
+	nf_bridge->physinif = skb->dev->ifindex;
 	skb->dev = brnf_get_logical_dev(skb, skb->dev, net);
 
 	if (skb->protocol == htons(ETH_P_8021Q))
@@ -552,7 +567,11 @@ static int br_nf_forward_finish(struct net *net, struct sock *sk, struct sk_buff
 		if (skb->protocol == htons(ETH_P_IPV6))
 			nf_bridge->frag_max_size = IP6CB(skb)->frag_max_size;
 
-		in = nf_bridge->physindev;
+		in = nf_bridge_get_physindev(skb, net);
+		if (!in) {
+			kfree_skb(skb);
+			return 0;
+		}
 		if (nf_bridge->pkt_otherhost) {
 			skb->pkt_type = PACKET_OTHERHOST;
 			nf_bridge->pkt_otherhost = false;
@@ -896,6 +915,13 @@ static unsigned int ip_sabotage_in(void *priv,
 static void br_nf_pre_routing_finish_bridge_slow(struct sk_buff *skb)
 {
 	struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
+	struct net_device *br_indev;
+
+	br_indev = nf_bridge_get_physindev(skb, dev_net(skb->dev));
+	if (!br_indev) {
+		kfree_skb(skb);
+		return;
+	}
 
 	skb_pull(skb, ETH_HLEN);
 	nf_bridge->bridged_dnat = 0;
@@ -905,7 +931,7 @@ static void br_nf_pre_routing_finish_bridge_slow(struct sk_buff *skb)
 	skb_copy_to_linear_data_offset(skb, -(ETH_HLEN - ETH_ALEN),
 				       nf_bridge->neigh_header,
 				       ETH_HLEN - ETH_ALEN);
-	skb->dev = nf_bridge->physindev;
+	skb->dev = br_indev;
 
 	nf_bridge->physoutdev = NULL;
 	br_handle_frame_finish(dev_net(skb->dev), NULL, skb);
diff --git a/net/bridge/br_netfilter_ipv6.c b/net/bridge/br_netfilter_ipv6.c
index 550039dfc31a..ad268bd19d5b 100644
--- a/net/bridge/br_netfilter_ipv6.c
+++ b/net/bridge/br_netfilter_ipv6.c
@@ -102,9 +102,15 @@ static int br_nf_pre_routing_finish_ipv6(struct net *net, struct sock *sk, struc
 {
 	struct nf_bridge_info *nf_bridge = nf_bridge_info_get(skb);
 	struct rtable *rt;
-	struct net_device *dev = skb->dev;
+	struct net_device *dev = skb->dev, *br_indev;
 	const struct nf_ipv6_ops *v6ops = nf_get_ipv6_ops();
 
+	br_indev = nf_bridge_get_physindev(skb, net);
+	if (!br_indev) {
+		kfree_skb(skb);
+		return 0;
+	}
+
 	nf_bridge->frag_max_size = IP6CB(skb)->frag_max_size;
 
 	if (nf_bridge->pkt_otherhost) {
@@ -122,7 +128,7 @@ static int br_nf_pre_routing_finish_ipv6(struct net *net, struct sock *sk, struc
 		}
 
 		if (skb_dst(skb)->dev == dev) {
-			skb->dev = nf_bridge->physindev;
+			skb->dev = br_indev;
 			nf_bridge_update_protocol(skb);
 			nf_bridge_push_encap_header(skb);
 			br_nf_hook_thresh(NF_BR_PRE_ROUTING,
@@ -133,7 +139,7 @@ static int br_nf_pre_routing_finish_ipv6(struct net *net, struct sock *sk, struc
 		ether_addr_copy(eth_hdr(skb)->h_dest, dev->dev_addr);
 		skb->pkt_type = PACKET_HOST;
 	} else {
-		rt = bridge_parent_rtable(nf_bridge->physindev);
+		rt = bridge_parent_rtable(br_indev);
 		if (!rt) {
 			kfree_skb(skb);
 			return 0;
@@ -142,7 +148,7 @@ static int br_nf_pre_routing_finish_ipv6(struct net *net, struct sock *sk, struc
 		skb_dst_set_noref(skb, &rt->dst);
 	}
 
-	skb->dev = nf_bridge->physindev;
+	skb->dev = br_indev;
 	nf_bridge_update_protocol(skb);
 	nf_bridge_push_encap_header(skb);
 	br_nf_hook_thresh(NF_BR_PRE_ROUTING, net, sk, skb,
diff --git a/net/ipv4/netfilter/nf_reject_ipv4.c b/net/ipv4/netfilter/nf_reject_ipv4.c
index 63c91aa2375f..4aac392f9891 100644
--- a/net/ipv4/netfilter/nf_reject_ipv4.c
+++ b/net/ipv4/netfilter/nf_reject_ipv4.c
@@ -237,7 +237,6 @@ static int nf_reject_fill_skb_dst(struct sk_buff *skb_in)
 void nf_send_reset(struct net *net, struct sock *sk, struct sk_buff *oldskb,
 		   int hook)
 {
-	struct net_device *br_indev __maybe_unused;
 	struct sk_buff *nskb;
 	struct iphdr *niph;
 	const struct tcphdr *oth;
@@ -286,9 +285,13 @@ void nf_send_reset(struct net *net, struct sock *sk, struct sk_buff *oldskb,
 	 * build the eth header using the original destination's MAC as the
 	 * source, and send the RST packet directly.
 	 */
-	br_indev = nf_bridge_get_physindev(oldskb, net);
-	if (br_indev) {
+	if (nf_bridge_info_exists(oldskb)) {
 		struct ethhdr *oeth = eth_hdr(oldskb);
+		struct net_device *br_indev;
+
+		br_indev = nf_bridge_get_physindev(oldskb, net);
+		if (!br_indev)
+			goto free_nskb;
 
 		nskb->dev = br_indev;
 		niph->tot_len = htons(nskb->len);
diff --git a/net/ipv6/netfilter/nf_reject_ipv6.c b/net/ipv6/netfilter/nf_reject_ipv6.c
index b138ee4ebc6a..cda37265bd39 100644
--- a/net/ipv6/netfilter/nf_reject_ipv6.c
+++ b/net/ipv6/netfilter/nf_reject_ipv6.c
@@ -278,7 +278,6 @@ static int nf_reject6_fill_skb_dst(struct sk_buff *skb_in)
 void nf_send_reset6(struct net *net, struct sock *sk, struct sk_buff *oldskb,
 		    int hook)
 {
-	struct net_device *br_indev __maybe_unused;
 	struct sk_buff *nskb;
 	struct tcphdr _otcph;
 	const struct tcphdr *otcph;
@@ -353,9 +352,15 @@ void nf_send_reset6(struct net *net, struct sock *sk, struct sk_buff *oldskb,
 	 * build the eth header using the original destination's MAC as the
 	 * source, and send the RST packet directly.
 	 */
-	br_indev = nf_bridge_get_physindev(oldskb, net);
-	if (br_indev) {
+	if (nf_bridge_info_exists(oldskb)) {
 		struct ethhdr *oeth = eth_hdr(oldskb);
+		struct net_device *br_indev;
+
+		br_indev = nf_bridge_get_physindev(oldskb, net);
+		if (!br_indev) {
+			kfree_skb(nskb);
+			return;
+		}
 
 		nskb->dev = br_indev;
 		nskb->protocol = htons(ETH_P_IPV6);


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