[PATCH net 0/5] Netfilter fixes for net

[PATCH net 0/5] Netfilter fixes for net

[Pablo Neira Ayuso]

Hi,

The following patchset contains Netfilter fixes for net:

1) Missing nul-check in basechain hook netlink dump path, from Gavrilov Ilia.

2) Fix bitwise register tracking, from Jeremy Sowden.

3) Null pointer dereference when accessing conntrack helper,
   from Tijs Van Buggenhout.

4) Add schedule point to ipset's call_ad, from Kuniyuki Iwashima.

5) Incorrect boundary check when building chain blob.

Please, pull these changes from:

  git://git.kernel.org/pub/scm/linux/kernel/git/netfilter/nf.git nf-23-06-07

Thanks.

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

The following changes since commit 9025944fddfed5966c8f102f1fe921ab3aee2c12:

  net: fec: add dma_wmb to ensure correct descriptor values (2023-05-19 09:17:53 +0100)

are available in the Git repository at:

  git://git.kernel.org/pub/scm/linux/kernel/git/netfilter/nf.git tags/nf-23-06-07

for you to fetch changes up to 08e42a0d3ad30f276f9597b591f975971a1b0fcf:

  netfilter: nf_tables: out-of-bound check in chain blob (2023-06-07 00:43:44 +0200)

----------------------------------------------------------------
netfilter pull request 23-06-07

----------------------------------------------------------------
Gavrilov Ilia (1):
      netfilter: nf_tables: Add null check for nla_nest_start_noflag() in nft_dump_basechain_hook()

Jeremy Sowden (1):
      netfilter: nft_bitwise: fix register tracking

Kuniyuki Iwashima (1):
      netfilter: ipset: Add schedule point in call_ad().

Pablo Neira Ayuso (1):
      netfilter: nf_tables: out-of-bound check in chain blob

Tijs Van Buggenhout (1):
      netfilter: conntrack: fix NULL pointer dereference in nf_confirm_cthelper

 net/netfilter/ipset/ip_set_core.c | 8 ++++++++
 net/netfilter/nf_conntrack_core.c | 3 +++
 net/netfilter/nf_tables_api.c     | 4 +++-
 net/netfilter/nft_bitwise.c       | 2 +-
 4 files changed, 15 insertions(+), 2 deletions(-)

[PATCH net 1/5] netfilter: nf_tables: Add null check for nla_nest_start_noflag() in nft_dump_basechain_hook()

[Pablo Neira Ayuso]

From: Gavrilov Ilia <Ilia.Gavrilov@infotecs.ru>

The nla_nest_start_noflag() function may fail and return NULL;
the return value needs to be checked.

Found by InfoTeCS on behalf of Linux Verification Center
(linuxtesting.org) with SVACE.

Fixes: d54725cd11a5 ("netfilter: nf_tables: support for multiple devices per netdev hook")
Signed-off-by: Gavrilov Ilia <Ilia.Gavrilov@infotecs.ru>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
 net/netfilter/nf_tables_api.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index dc5675962de4..3445b8e1f462 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -1600,6 +1600,8 @@ static int nft_dump_basechain_hook(struct sk_buff *skb, int family,
 
 	if (nft_base_chain_netdev(family, ops->hooknum)) {
 		nest_devs = nla_nest_start_noflag(skb, NFTA_HOOK_DEVS);
+		if (!nest_devs)
+			goto nla_put_failure;
 
 		if (!hook_list)
 			hook_list = &basechain->hook_list;
-- 
2.30.2

[PATCH net 2/5] netfilter: nft_bitwise: fix register tracking

[Pablo Neira Ayuso]

From: Jeremy Sowden <jeremy@azazel.net>

At the end of `nft_bitwise_reduce`, there is a loop which is intended to
update the bitwise expression associated with each tracked destination
register.  However, currently, it just updates the first register
repeatedly.  Fix it.

Fixes: 34cc9e52884a ("netfilter: nf_tables: cancel tracking for clobbered destination registers")
Signed-off-by: Jeremy Sowden <jeremy@azazel.net>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
 net/netfilter/nft_bitwise.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/netfilter/nft_bitwise.c b/net/netfilter/nft_bitwise.c
index 84eae7cabc67..2527a01486ef 100644
--- a/net/netfilter/nft_bitwise.c
+++ b/net/netfilter/nft_bitwise.c
@@ -323,7 +323,7 @@ static bool nft_bitwise_reduce(struct nft_regs_track *track,
 	dreg = priv->dreg;
 	regcount = DIV_ROUND_UP(priv->len, NFT_REG32_SIZE);
 	for (i = 0; i < regcount; i++, dreg++)
-		track->regs[priv->dreg].bitwise = expr;
+		track->regs[dreg].bitwise = expr;
 
 	return false;
 }
-- 
2.30.2

[PATCH net 3/5] netfilter: conntrack: fix NULL pointer dereference in nf_confirm_cthelper

[Pablo Neira Ayuso]

From: Tijs Van Buggenhout <tijs.van.buggenhout@axsguard.com>

An nf_conntrack_helper from nf_conn_help may become NULL after DNAT.

Observed when TCP port 1720 (Q931_PORT), associated with h323 conntrack
helper, is DNAT'ed to another destination port (e.g. 1730), while
nfqueue is being used for final acceptance (e.g. snort).

This happenned after transition from kernel 4.14 to 5.10.161.

Workarounds:
 * keep the same port (1720) in DNAT
 * disable nfqueue
 * disable/unload h323 NAT helper

$ linux-5.10/scripts/decode_stacktrace.sh vmlinux < /tmp/kernel.log
BUG: kernel NULL pointer dereference, address: 0000000000000084
[..]
RIP: 0010:nf_conntrack_update (net/netfilter/nf_conntrack_core.c:2080 net/netfilter/nf_conntrack_core.c:2134) nf_conntrack
[..]
nfqnl_reinject (net/netfilter/nfnetlink_queue.c:237) nfnetlink_queue
nfqnl_recv_verdict (net/netfilter/nfnetlink_queue.c:1230) nfnetlink_queue
nfnetlink_rcv_msg (net/netfilter/nfnetlink.c:241) nfnetlink
[..]

Fixes: ee04805ff54a ("netfilter: conntrack: make conntrack userspace helpers work again")
Signed-off-by: Tijs Van Buggenhout <tijs.van.buggenhout@axsguard.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
 net/netfilter/nf_conntrack_core.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c
index c4ccfec6cb98..d119f1d4c2fc 100644
--- a/net/netfilter/nf_conntrack_core.c
+++ b/net/netfilter/nf_conntrack_core.c
@@ -2260,6 +2260,9 @@ static int nf_confirm_cthelper(struct sk_buff *skb, struct nf_conn *ct,
 		return 0;
 
 	helper = rcu_dereference(help->helper);
+	if (!helper)
+		return 0;
+
 	if (!(helper->flags & NF_CT_HELPER_F_USERSPACE))
 		return 0;
 
-- 
2.30.2

[PATCH net 4/5] netfilter: ipset: Add schedule point in call_ad().

[Pablo Neira Ayuso]

From: Kuniyuki Iwashima <kuniyu@amazon.com>

syzkaller found a repro that causes Hung Task [0] with ipset.  The repro
first creates an ipset and then tries to delete a large number of IPs
from the ipset concurrently:

  IPSET_ATTR_IPADDR_IPV4 : 172.20.20.187
  IPSET_ATTR_CIDR        : 2

The first deleting thread hogs a CPU with nfnl_lock(NFNL_SUBSYS_IPSET)
held, and other threads wait for it to be released.

Previously, the same issue existed in set->variant->uadt() that could run
so long under ip_set_lock(set).  Commit 5e29dc36bd5e ("netfilter: ipset:
Rework long task execution when adding/deleting entries") tried to fix it,
but the issue still exists in the caller with another mutex.

While adding/deleting many IPs, we should release the CPU periodically to
prevent someone from abusing ipset to hang the system.

Note we need to increment the ipset's refcnt to prevent the ipset from
being destroyed while rescheduling.

[0]:
INFO: task syz-executor174:268 blocked for more than 143 seconds.
      Not tainted 6.4.0-rc1-00145-gba79e9a73284 #1
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor174 state:D stack:0     pid:268   ppid:260    flags:0x0000000d
Call trace:
 __switch_to+0x308/0x714 arch/arm64/kernel/process.c:556
 context_switch kernel/sched/core.c:5343 [inline]
 __schedule+0xd84/0x1648 kernel/sched/core.c:6669
 schedule+0xf0/0x214 kernel/sched/core.c:6745
 schedule_preempt_disabled+0x58/0xf0 kernel/sched/core.c:6804
 __mutex_lock_common kernel/locking/mutex.c:679 [inline]
 __mutex_lock+0x6fc/0xdb0 kernel/locking/mutex.c:747
 __mutex_lock_slowpath+0x14/0x20 kernel/locking/mutex.c:1035
 mutex_lock+0x98/0xf0 kernel/locking/mutex.c:286
 nfnl_lock net/netfilter/nfnetlink.c:98 [inline]
 nfnetlink_rcv_msg+0x480/0x70c net/netfilter/nfnetlink.c:295
 netlink_rcv_skb+0x1c0/0x350 net/netlink/af_netlink.c:2546
 nfnetlink_rcv+0x18c/0x199c net/netfilter/nfnetlink.c:658
 netlink_unicast_kernel net/netlink/af_netlink.c:1339 [inline]
 netlink_unicast+0x664/0x8cc net/netlink/af_netlink.c:1365
 netlink_sendmsg+0x6d0/0xa4c net/netlink/af_netlink.c:1913
 sock_sendmsg_nosec net/socket.c:724 [inline]
 sock_sendmsg net/socket.c:747 [inline]
 ____sys_sendmsg+0x4b8/0x810 net/socket.c:2503
 ___sys_sendmsg net/socket.c:2557 [inline]
 __sys_sendmsg+0x1f8/0x2a4 net/socket.c:2586
 __do_sys_sendmsg net/socket.c:2595 [inline]
 __se_sys_sendmsg net/socket.c:2593 [inline]
 __arm64_sys_sendmsg+0x80/0x94 net/socket.c:2593
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x84/0x270 arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x134/0x24c arch/arm64/kernel/syscall.c:142
 do_el0_svc+0x64/0x198 arch/arm64/kernel/syscall.c:193
 el0_svc+0x2c/0x7c arch/arm64/kernel/entry-common.c:637
 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
 el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:591

Reported-by: syzkaller <syzkaller@googlegroups.com>
Fixes: a7b4f989a629 ("netfilter: ipset: IP set core support")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Acked-by: Jozsef Kadlecsik <kadlec@netfilter.org>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
 net/netfilter/ipset/ip_set_core.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/net/netfilter/ipset/ip_set_core.c b/net/netfilter/ipset/ip_set_core.c
index 46ebee9400da..9a6b64779e64 100644
--- a/net/netfilter/ipset/ip_set_core.c
+++ b/net/netfilter/ipset/ip_set_core.c
@@ -1694,6 +1694,14 @@ call_ad(struct net *net, struct sock *ctnl, struct sk_buff *skb,
 	bool eexist = flags & IPSET_FLAG_EXIST, retried = false;
 
 	do {
+		if (retried) {
+			__ip_set_get(set);
+			nfnl_unlock(NFNL_SUBSYS_IPSET);
+			cond_resched();
+			nfnl_lock(NFNL_SUBSYS_IPSET);
+			__ip_set_put(set);
+		}
+
 		ip_set_lock(set);
 		ret = set->variant->uadt(set, tb, adt, &lineno, flags, retried);
 		ip_set_unlock(set);
-- 
2.30.2

[PATCH net 5/5] netfilter: nf_tables: out-of-bound check in chain blob

[Pablo Neira Ayuso]

Add current size of rule expressions to the boundary check.

Fixes: 2c865a8a28a1 ("netfilter: nf_tables: add rule blob layout")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
 net/netfilter/nf_tables_api.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index 3445b8e1f462..0519d45ede6b 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -9007,7 +9007,7 @@ static int nf_tables_commit_chain_prepare(struct net *net, struct nft_chain *cha
 				continue;
 			}
 
-			if (WARN_ON_ONCE(data + expr->ops->size > data_boundary))
+			if (WARN_ON_ONCE(data + size + expr->ops->size > data_boundary))
 				return -ENOMEM;
 
 			memcpy(data + size, expr, expr->ops->size);
-- 
2.30.2

Re: [PATCH net 1/5] netfilter: nf_tables: Add null check for nla_nest_start_noflag() in nft_dump_basechain_hook()

[patchwork-bot+netdevbpf]

Hello:

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

On Wed,  7 Jun 2023 00:58:47 +0200 you wrote:
> From: Gavrilov Ilia <Ilia.Gavrilov@infotecs.ru>
> 
> The nla_nest_start_noflag() function may fail and return NULL;
> the return value needs to be checked.
> 
> Found by InfoTeCS on behalf of Linux Verification Center
> (linuxtesting.org) with SVACE.
> 
> [...]

Here is the summary with links:
  - [net,1/5] netfilter: nf_tables: Add null check for nla_nest_start_noflag() in nft_dump_basechain_hook()
    https://git.kernel.org/netdev/net/c/bd058763a624
  - [net,2/5] netfilter: nft_bitwise: fix register tracking
    https://git.kernel.org/netdev/net/c/14e8b2939037
  - [net,3/5] netfilter: conntrack: fix NULL pointer dereference in nf_confirm_cthelper
    https://git.kernel.org/netdev/net/c/e1f543dc660b
  - [net,4/5] netfilter: ipset: Add schedule point in call_ad().
    https://git.kernel.org/netdev/net/c/24e227896bbf
  - [net,5/5] netfilter: nf_tables: out-of-bound check in chain blob
    https://git.kernel.org/netdev/net/c/08e42a0d3ad3

You are awesome, thank you!
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