[PATCH net 0/4] Netfilter fixes for net

[PATCH net 0/4] Netfilter fixes for net

[Pablo Neira Ayuso]

Hi,

The following patchset contains Netfilter fixes for net:

Patch #1 reject destroy chain command to delete device hooks in netdev
         family, hence, only delchain commands are allowed.

Patch #2 reject table flag update interference with netdev basechain
	 hook updates, this can leave hooks in inconsistent
	 registration/unregistration state.

Patch #3 do not unregister netdev basechain hooks if table is dormant.
	 Otherwise, splat with double unregistration is possible.

Patch #4 fixes Kconfig to allow to restore IP_NF_ARPTABLES,
	 from Kuniyuki Iwashima.

There are a more fixes still in progress on my side that need more work.

Please, pull these changes from:

  git://git.kernel.org/pub/scm/linux/kernel/git/netfilter/nf.git nf-24-03-28

Thanks.

----------------------------------------------------------------

The following changes since commit d24b03535e5eb82e025219c2f632b485409c898f:

  nfc: nci: Fix uninit-value in nci_dev_up and nci_ntf_packet (2024-03-22 09:41:39 +0000)

are available in the Git repository at:

  git://git.kernel.org/pub/scm/linux/kernel/git/netfilter/nf.git tags/nf-24-03-28

for you to fetch changes up to 15fba562f7a9f04322b8bfc8f392e04bb93d81be:

  netfilter: arptables: Select NETFILTER_FAMILY_ARP when building arp_tables.c (2024-03-28 03:54:02 +0100)

----------------------------------------------------------------
netfilter pull request 24-03-28

----------------------------------------------------------------
Kuniyuki Iwashima (1):
      netfilter: arptables: Select NETFILTER_FAMILY_ARP when building arp_tables.c

Pablo Neira Ayuso (3):
      netfilter: nf_tables: reject destroy command to remove basechain hooks
      netfilter: nf_tables: reject table flag and netdev basechain updates
      netfilter: nf_tables: skip netdev hook unregistration if table is dormant

 net/ipv4/netfilter/Kconfig    |  1 +
 net/netfilter/nf_tables_api.c | 50 ++++++++++++++++++++++++++++++++++++-------
 2 files changed, 43 insertions(+), 8 deletions(-)

[PATCH net 1/4] netfilter: nf_tables: reject destroy command to remove basechain hooks

[Pablo Neira Ayuso]

Report EOPNOTSUPP if NFT_MSG_DESTROYCHAIN is used to delete hooks in an
existing netdev basechain, thus, only NFT_MSG_DELCHAIN is allowed.

Fixes: 7d937b107108f ("netfilter: nf_tables: support for deleting devices in an existing netdev chain")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
 net/netfilter/nf_tables_api.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index 5fa3d3540c93..a1a8030e16a5 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -2944,7 +2944,8 @@ static int nf_tables_delchain(struct sk_buff *skb, const struct nfnl_info *info,
 	nft_ctx_init(&ctx, net, skb, info->nlh, family, table, chain, nla);
 
 	if (nla[NFTA_CHAIN_HOOK]) {
-		if (chain->flags & NFT_CHAIN_HW_OFFLOAD)
+		if (NFNL_MSG_TYPE(info->nlh->nlmsg_type) == NFT_MSG_DESTROYCHAIN ||
+		    chain->flags & NFT_CHAIN_HW_OFFLOAD)
 			return -EOPNOTSUPP;
 
 		if (nft_is_base_chain(chain)) {
-- 
2.30.2

Re: [PATCH net 1/4] netfilter: nf_tables: reject destroy command to remove basechain hooks

[patchwork-bot+netdevbpf]

Hello:

This series was applied to netdev/net.git (main)
by Pablo Neira Ayuso <pablo@netfilter.org>:

On Thu, 28 Mar 2024 04:18:52 +0100 you wrote:
> Report EOPNOTSUPP if NFT_MSG_DESTROYCHAIN is used to delete hooks in an
> existing netdev basechain, thus, only NFT_MSG_DELCHAIN is allowed.
> 
> Fixes: 7d937b107108f ("netfilter: nf_tables: support for deleting devices in an existing netdev chain")
> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
> ---
>  net/netfilter/nf_tables_api.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)

Here is the summary with links:
  - [net,1/4] netfilter: nf_tables: reject destroy command to remove basechain hooks
    https://git.kernel.org/netdev/net/c/b32ca27fa238
  - [net,2/4] netfilter: nf_tables: reject table flag and netdev basechain updates
    https://git.kernel.org/netdev/net/c/1e1fb6f00f52
  - [net,3/4] netfilter: nf_tables: skip netdev hook unregistration if table is dormant
    https://git.kernel.org/netdev/net/c/216e7bf7402c
  - [net,4/4] netfilter: arptables: Select NETFILTER_FAMILY_ARP when building arp_tables.c
    https://git.kernel.org/netdev/net/c/15fba562f7a9

You are awesome, thank you!
-- 
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html

[PATCH net 2/4] netfilter: nf_tables: reject table flag and netdev basechain updates

[Pablo Neira Ayuso]

netdev basechain updates are stored in the transaction object hook list.
When setting on the table dormant flag, it iterates over the existing
hooks in the basechain. Thus, skipping the hooks that are being
added/deleted in this transaction, which leaves hook registration in
inconsistent state.

Reject table flag updates in combination with netdev basechain updates
in the same batch:

- Update table flags and add/delete basechain: Check from basechain update
  path if there are pending flag updates for this table.
- add/delete basechain and update table flags: Iterate over the transaction
  list to search for basechain updates from the table update path.

In both cases, the batch is rejected. Based on suggestion from Florian Westphal.

Fixes: b9703ed44ffb ("netfilter: nf_tables: support for adding new devices to an existing netdev chain")
Fixes: 7d937b107108f ("netfilter: nf_tables: support for deleting devices in an existing netdev chain")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
 net/netfilter/nf_tables_api.c | 31 ++++++++++++++++++++++++++++++-
 1 file changed, 30 insertions(+), 1 deletion(-)

diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index a1a8030e16a5..086d85fffeb1 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -1200,6 +1200,25 @@ static void nf_tables_table_disable(struct net *net, struct nft_table *table)
 					 __NFT_TABLE_F_WAS_AWAKEN | \
 					 __NFT_TABLE_F_WAS_ORPHAN)
 
+static bool nft_table_pending_update(const struct nft_ctx *ctx)
+{
+	struct nftables_pernet *nft_net = nft_pernet(ctx->net);
+	struct nft_trans *trans;
+
+	if (ctx->table->flags & __NFT_TABLE_F_UPDATE)
+		return true;
+
+	list_for_each_entry(trans, &nft_net->commit_list, list) {
+		if ((trans->msg_type == NFT_MSG_NEWCHAIN ||
+		     trans->msg_type == NFT_MSG_DELCHAIN) &&
+		    trans->ctx.table == ctx->table &&
+		    nft_trans_chain_update(trans))
+			return true;
+	}
+
+	return false;
+}
+
 static int nf_tables_updtable(struct nft_ctx *ctx)
 {
 	struct nft_trans *trans;
@@ -1226,7 +1245,7 @@ static int nf_tables_updtable(struct nft_ctx *ctx)
 		return -EOPNOTSUPP;
 
 	/* No dormant off/on/off/on games in single transaction */
-	if (ctx->table->flags & __NFT_TABLE_F_UPDATE)
+	if (nft_table_pending_update(ctx))
 		return -EINVAL;
 
 	trans = nft_trans_alloc(ctx, NFT_MSG_NEWTABLE,
@@ -2631,6 +2650,13 @@ static int nf_tables_updchain(struct nft_ctx *ctx, u8 genmask, u8 policy,
 		}
 	}
 
+	if (table->flags & __NFT_TABLE_F_UPDATE &&
+	    !list_empty(&hook.list)) {
+		NL_SET_BAD_ATTR(extack, attr);
+		err = -EOPNOTSUPP;
+		goto err_hooks;
+	}
+
 	if (!(table->flags & NFT_TABLE_F_DORMANT) &&
 	    nft_is_base_chain(chain) &&
 	    !list_empty(&hook.list)) {
@@ -2860,6 +2886,9 @@ static int nft_delchain_hook(struct nft_ctx *ctx,
 	struct nft_trans *trans;
 	int err;
 
+	if (ctx->table->flags & __NFT_TABLE_F_UPDATE)
+		return -EOPNOTSUPP;
+
 	err = nft_chain_parse_hook(ctx->net, basechain, nla, &chain_hook,
 				   ctx->family, chain->flags, extack);
 	if (err < 0)
-- 
2.30.2

[PATCH net 3/4] netfilter: nf_tables: skip netdev hook unregistration if table is dormant

[Pablo Neira Ayuso]

Skip hook unregistration when adding or deleting devices from an
existing netdev basechain. Otherwise, commit/abort path try to
unregister hooks which not enabled.

Fixes: b9703ed44ffb ("netfilter: nf_tables: support for adding new devices to an existing netdev chain")
Fixes: 7d937b107108 ("netfilter: nf_tables: support for deleting devices in an existing netdev chain")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
 net/netfilter/nf_tables_api.c | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index 086d85fffeb1..fd86f2720c9e 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -10212,9 +10212,11 @@ static int nf_tables_commit(struct net *net, struct sk_buff *skb)
 			if (nft_trans_chain_update(trans)) {
 				nf_tables_chain_notify(&trans->ctx, NFT_MSG_DELCHAIN,
 						       &nft_trans_chain_hooks(trans));
-				nft_netdev_unregister_hooks(net,
-							    &nft_trans_chain_hooks(trans),
-							    true);
+				if (!(trans->ctx.table->flags & NFT_TABLE_F_DORMANT)) {
+					nft_netdev_unregister_hooks(net,
+								    &nft_trans_chain_hooks(trans),
+								    true);
+				}
 			} else {
 				nft_chain_del(trans->ctx.chain);
 				nf_tables_chain_notify(&trans->ctx, NFT_MSG_DELCHAIN,
@@ -10490,9 +10492,11 @@ static int __nf_tables_abort(struct net *net, enum nfnl_abort_action action)
 			break;
 		case NFT_MSG_NEWCHAIN:
 			if (nft_trans_chain_update(trans)) {
-				nft_netdev_unregister_hooks(net,
-							    &nft_trans_chain_hooks(trans),
-							    true);
+				if (!(trans->ctx.table->flags & NFT_TABLE_F_DORMANT)) {
+					nft_netdev_unregister_hooks(net,
+								    &nft_trans_chain_hooks(trans),
+								    true);
+				}
 				free_percpu(nft_trans_chain_stats(trans));
 				kfree(nft_trans_chain_name(trans));
 				nft_trans_destroy(trans);
-- 
2.30.2

[PATCH net 4/4] netfilter: arptables: Select NETFILTER_FAMILY_ARP when building arp_tables.c

[Pablo Neira Ayuso]

From: Kuniyuki Iwashima <kuniyu@amazon.com>

syzkaller started to report a warning below [0] after consuming the
commit 4654467dc7e1 ("netfilter: arptables: allow xtables-nft only
builds").

The change accidentally removed the dependency on NETFILTER_FAMILY_ARP
from IP_NF_ARPTABLES.

If NF_TABLES_ARP is not enabled on Kconfig, NETFILTER_FAMILY_ARP will
be removed and some code necessary for arptables will not be compiled.

  $ grep -E "(NETFILTER_FAMILY_ARP|IP_NF_ARPTABLES|NF_TABLES_ARP)" .config
  CONFIG_NETFILTER_FAMILY_ARP=y
  # CONFIG_NF_TABLES_ARP is not set
  CONFIG_IP_NF_ARPTABLES=y

  $ make olddefconfig

  $ grep -E "(NETFILTER_FAMILY_ARP|IP_NF_ARPTABLES|NF_TABLES_ARP)" .config
  # CONFIG_NF_TABLES_ARP is not set
  CONFIG_IP_NF_ARPTABLES=y

So, when nf_register_net_hooks() is called for arptables, it will
trigger the splat below.

Now IP_NF_ARPTABLES is only enabled by IP_NF_ARPFILTER, so let's
restore the dependency on NETFILTER_FAMILY_ARP in IP_NF_ARPFILTER.

[0]:
WARNING: CPU: 0 PID: 242 at net/netfilter/core.c:316 nf_hook_entry_head+0x1e1/0x2c0 net/netfilter/core.c:316
Modules linked in:
CPU: 0 PID: 242 Comm: syz-executor.0 Not tainted 6.8.0-12821-g537c2e91d354 #10
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.0-0-gd239552ce722-prebuilt.qemu.org 04/01/2014
RIP: 0010:nf_hook_entry_head+0x1e1/0x2c0 net/netfilter/core.c:316
Code: 83 fd 04 0f 87 bc 00 00 00 e8 5b 84 83 fd 4d 8d ac ec a8 0b 00 00 e8 4e 84 83 fd 4c 89 e8 5b 5d 41 5c 41 5d c3 e8 3f 84 83 fd <0f> 0b e8 38 84 83 fd 45 31 ed 5b 5d 4c 89 e8 41 5c 41 5d c3 e8 26
RSP: 0018:ffffc90000b8f6e8 EFLAGS: 00010293
RAX: 0000000000000000 RBX: 0000000000000003 RCX: ffffffff83c42164
RDX: ffff888106851180 RSI: ffffffff83c42321 RDI: 0000000000000005
RBP: 0000000000000000 R08: 0000000000000005 R09: 000000000000000a
R10: 0000000000000003 R11: ffff8881055c2f00 R12: ffff888112b78000
R13: 0000000000000000 R14: ffff8881055c2f00 R15: ffff8881055c2f00
FS:  00007f377bd78800(0000) GS:ffff88811b000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000496068 CR3: 000000011298b003 CR4: 0000000000770ef0
PKRU: 55555554
Call Trace:
 <TASK>
 __nf_register_net_hook+0xcd/0x7a0 net/netfilter/core.c:428
 nf_register_net_hook+0x116/0x170 net/netfilter/core.c:578
 nf_register_net_hooks+0x5d/0xc0 net/netfilter/core.c:594
 arpt_register_table+0x250/0x420 net/ipv4/netfilter/arp_tables.c:1553
 arptable_filter_table_init+0x41/0x60 net/ipv4/netfilter/arptable_filter.c:39
 xt_find_table_lock+0x2e9/0x4b0 net/netfilter/x_tables.c:1260
 xt_request_find_table_lock+0x2b/0xe0 net/netfilter/x_tables.c:1285
 get_info+0x169/0x5c0 net/ipv4/netfilter/arp_tables.c:808
 do_arpt_get_ctl+0x3f9/0x830 net/ipv4/netfilter/arp_tables.c:1444
 nf_getsockopt+0x76/0xd0 net/netfilter/nf_sockopt.c:116
 ip_getsockopt+0x17d/0x1c0 net/ipv4/ip_sockglue.c:1777
 tcp_getsockopt+0x99/0x100 net/ipv4/tcp.c:4373
 do_sock_getsockopt+0x279/0x360 net/socket.c:2373
 __sys_getsockopt+0x115/0x1e0 net/socket.c:2402
 __do_sys_getsockopt net/socket.c:2412 [inline]
 __se_sys_getsockopt net/socket.c:2409 [inline]
 __x64_sys_getsockopt+0xbd/0x150 net/socket.c:2409
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0x4f/0x110 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x46/0x4e
RIP: 0033:0x7f377beca6fe
Code: 1f 44 00 00 48 8b 15 01 97 0a 00 f7 d8 64 89 02 b8 ff ff ff ff eb b8 0f 1f 44 00 00 f3 0f 1e fa 49 89 ca b8 37 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 0a c3 66 0f 1f 84 00 00 00 00 00 48 8b 15 c9
RSP: 002b:00000000005df728 EFLAGS: 00000246 ORIG_RAX: 0000000000000037
RAX: ffffffffffffffda RBX: 00000000004966e0 RCX: 00007f377beca6fe
RDX: 0000000000000060 RSI: 0000000000000000 RDI: 0000000000000003
RBP: 000000000042938a R08: 00000000005df73c R09: 00000000005df800
R10: 00000000004966e8 R11: 0000000000000246 R12: 0000000000000003
R13: 0000000000496068 R14: 0000000000000003 R15: 00000000004bc9d8
 </TASK>

Fixes: 4654467dc7e1 ("netfilter: arptables: allow xtables-nft only builds")
Reported-by: syzkaller <syzkaller@googlegroups.com>
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
 net/ipv4/netfilter/Kconfig | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/ipv4/netfilter/Kconfig b/net/ipv4/netfilter/Kconfig
index 8f6e950163a7..1b991b889506 100644
--- a/net/ipv4/netfilter/Kconfig
+++ b/net/ipv4/netfilter/Kconfig
@@ -329,6 +329,7 @@ config NFT_COMPAT_ARP
 config IP_NF_ARPFILTER
 	tristate "arptables-legacy packet filtering support"
 	select IP_NF_ARPTABLES
+	select NETFILTER_FAMILY_ARP
 	depends on NETFILTER_XTABLES
 	help
 	  ARP packet filtering defines a table `filter', which has a series of
-- 
2.30.2