[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:

1) Remove unused parameters in conntrack_dump_flush.c used by
   selftests, from Liu Jing.

2) Fix possible UaF when removing xtables module via getsockopt()
   interface, from Dong Chenchen.

3) Fix potential crash in nf_send_reset6() reported by syzkaller.
   From Eric Dumazet

4) Validate offset and length before calling skb_checksum()
   in nft_payload, otherwise hitting BUG() is possible.

Please, apply,
Thanks.

Dong Chenchen (1):
  netfilter: Fix use-after-free in get_info()

Eric Dumazet (1):
  netfilter: nf_reject_ipv6: fix potential crash in nf_send_reset6()

Liu Jing (1):
  selftests: netfilter: remove unused parameter

Pablo Neira Ayuso (1):
  netfilter: nft_payload: sanitize offset and length before calling
    skb_checksum()

 net/ipv6/netfilter/nf_reject_ipv6.c               | 15 +++++++--------
 net/netfilter/nft_payload.c                       |  3 +++
 net/netfilter/x_tables.c                          |  2 +-
 .../net/netfilter/conntrack_dump_flush.c          |  6 +++---
 4 files changed, 14 insertions(+), 12 deletions(-)

-- 
2.30.2

Please, pull these changes from:

  git://git.kernel.org/pub/scm/linux/kernel/git/netfilter/nf.git nf-24-10-31

Thanks.

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

The following changes since commit c05c62850a8f035a267151dd86ea3daf887e28b8:

  Merge tag 'wireless-2024-10-29' of https://git.kernel.org/pub/scm/linux/kernel/git/wireless/wireless (2024-10-29 18:57:12 -0700)

are available in the Git repository at:

  git://git.kernel.org/pub/scm/linux/kernel/git/netfilter/nf.git tags/nf-24-10-31

for you to fetch changes up to d5953d680f7e96208c29ce4139a0e38de87a57fe:

  netfilter: nft_payload: sanitize offset and length before calling skb_checksum() (2024-10-31 10:54:49 +0100)

----------------------------------------------------------------
netfilter pull request 24-10-31

----------------------------------------------------------------
Dong Chenchen (1):
      netfilter: Fix use-after-free in get_info()

Eric Dumazet (1):
      netfilter: nf_reject_ipv6: fix potential crash in nf_send_reset6()

Liu Jing (1):
      selftests: netfilter: remove unused parameter

Pablo Neira Ayuso (1):
      netfilter: nft_payload: sanitize offset and length before calling skb_checksum()

 net/ipv6/netfilter/nf_reject_ipv6.c                       | 15 +++++++--------
 net/netfilter/nft_payload.c                               |  3 +++
 net/netfilter/x_tables.c                                  |  2 +-
 .../selftests/net/netfilter/conntrack_dump_flush.c        |  6 +++---
 4 files changed, 14 insertions(+), 12 deletions(-)

[PATCH net 1/4] selftests: netfilter: remove unused parameter

[Pablo Neira Ayuso]

From: Liu Jing <liujing@cmss.chinamobile.com>

err is never used, remove it.

Signed-off-by: Liu Jing <liujing@cmss.chinamobile.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
 .../testing/selftests/net/netfilter/conntrack_dump_flush.c  | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/tools/testing/selftests/net/netfilter/conntrack_dump_flush.c b/tools/testing/selftests/net/netfilter/conntrack_dump_flush.c
index dc056fec993b..254ff03297f0 100644
--- a/tools/testing/selftests/net/netfilter/conntrack_dump_flush.c
+++ b/tools/testing/selftests/net/netfilter/conntrack_dump_flush.c
@@ -98,7 +98,7 @@ static int conntrack_data_insert(struct mnl_socket *sock, struct nlmsghdr *nlh,
 	char buf[MNL_SOCKET_BUFFER_SIZE];
 	struct nlmsghdr *rplnlh;
 	unsigned int portid;
-	int err, ret;
+	int ret;
 
 	portid = mnl_socket_get_portid(sock);
 
@@ -217,7 +217,7 @@ static int conntracK_count_zone(struct mnl_socket *sock, uint16_t zone)
 	struct nfgenmsg *nfh;
 	struct nlattr *nest;
 	unsigned int portid;
-	int err, ret;
+	int ret;
 
 	portid = mnl_socket_get_portid(sock);
 
@@ -264,7 +264,7 @@ static int conntrack_flush_zone(struct mnl_socket *sock, uint16_t zone)
 	struct nfgenmsg *nfh;
 	struct nlattr *nest;
 	unsigned int portid;
-	int err, ret;
+	int ret;
 
 	portid = mnl_socket_get_portid(sock);
 
-- 
2.30.2

[PATCH net 2/4] netfilter: Fix use-after-free in get_info()

[Pablo Neira Ayuso]

From: Dong Chenchen <dongchenchen2@huawei.com>

ip6table_nat module unload has refcnt warning for UAF. call trace is:

WARNING: CPU: 1 PID: 379 at kernel/module/main.c:853 module_put+0x6f/0x80
Modules linked in: ip6table_nat(-)
CPU: 1 UID: 0 PID: 379 Comm: ip6tables Not tainted 6.12.0-rc4-00047-gc2ee9f594da8-dirty #205
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996),
BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014
RIP: 0010:module_put+0x6f/0x80
Call Trace:
 <TASK>
 get_info+0x128/0x180
 do_ip6t_get_ctl+0x6a/0x430
 nf_getsockopt+0x46/0x80
 ipv6_getsockopt+0xb9/0x100
 rawv6_getsockopt+0x42/0x190
 do_sock_getsockopt+0xaa/0x180
 __sys_getsockopt+0x70/0xc0
 __x64_sys_getsockopt+0x20/0x30
 do_syscall_64+0xa2/0x1a0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Concurrent execution of module unload and get_info() trigered the warning.
The root cause is as follows:

cpu0				      cpu1
module_exit
//mod->state = MODULE_STATE_GOING
  ip6table_nat_exit
    xt_unregister_template
	kfree(t)
	//removed from templ_list
				      getinfo()
					  t = xt_find_table_lock
						list_for_each_entry(tmpl, &xt_templates[af]...)
							if (strcmp(tmpl->name, name))
								continue;  //table not found
							try_module_get
						list_for_each_entry(t, &xt_net->tables[af]...)
							return t;  //not get refcnt
					  module_put(t->me) //uaf
    unregister_pernet_subsys
    //remove table from xt_net list

While xt_table module was going away and has been removed from
xt_templates list, we couldnt get refcnt of xt_table->me. Check
module in xt_net->tables list re-traversal to fix it.

Fixes: fdacd57c79b7 ("netfilter: x_tables: never register tables by default")
Signed-off-by: Dong Chenchen <dongchenchen2@huawei.com>
Reviewed-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
 net/netfilter/x_tables.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/netfilter/x_tables.c b/net/netfilter/x_tables.c
index da5d929c7c85..709840612f0d 100644
--- a/net/netfilter/x_tables.c
+++ b/net/netfilter/x_tables.c
@@ -1269,7 +1269,7 @@ struct xt_table *xt_find_table_lock(struct net *net, u_int8_t af,
 
 	/* and once again: */
 	list_for_each_entry(t, &xt_net->tables[af], list)
-		if (strcmp(t->name, name) == 0)
+		if (strcmp(t->name, name) == 0 && owner == t->me)
 			return t;
 
 	module_put(owner);
-- 
2.30.2

[PATCH net 3/4] netfilter: nf_reject_ipv6: fix potential crash in nf_send_reset6()

[Pablo Neira Ayuso]

From: Eric Dumazet <edumazet@google.com>

I got a syzbot report without a repro [1] crashing in nf_send_reset6()

I think the issue is that dev->hard_header_len is zero, and we attempt
later to push an Ethernet header.

Use LL_MAX_HEADER, as other functions in net/ipv6/netfilter/nf_reject_ipv6.c.

[1]

skbuff: skb_under_panic: text:ffffffff89b1d008 len:74 put:14 head:ffff88803123aa00 data:ffff88803123a9f2 tail:0x3c end:0x140 dev:syz_tun
 kernel BUG at net/core/skbuff.c:206 !
Oops: invalid opcode: 0000 [#1] PREEMPT SMP KASAN PTI
CPU: 0 UID: 0 PID: 7373 Comm: syz.1.568 Not tainted 6.12.0-rc2-syzkaller-00631-g6d858708d465 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
 RIP: 0010:skb_panic net/core/skbuff.c:206 [inline]
 RIP: 0010:skb_under_panic+0x14b/0x150 net/core/skbuff.c:216
Code: 0d 8d 48 c7 c6 60 a6 29 8e 48 8b 54 24 08 8b 0c 24 44 8b 44 24 04 4d 89 e9 50 41 54 41 57 41 56 e8 ba 30 38 02 48 83 c4 20 90 <0f> 0b 0f 1f 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3
RSP: 0018:ffffc900045269b0 EFLAGS: 00010282
RAX: 0000000000000088 RBX: dffffc0000000000 RCX: cd66dacdc5d8e800
RDX: 0000000000000000 RSI: 0000000000000200 RDI: 0000000000000000
RBP: ffff88802d39a3d0 R08: ffffffff8174afec R09: 1ffff920008a4ccc
R10: dffffc0000000000 R11: fffff520008a4ccd R12: 0000000000000140
R13: ffff88803123aa00 R14: ffff88803123a9f2 R15: 000000000000003c
FS:  00007fdbee5ff6c0(0000) GS:ffff8880b8600000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 000000005d322000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
  skb_push+0xe5/0x100 net/core/skbuff.c:2636
  eth_header+0x38/0x1f0 net/ethernet/eth.c:83
  dev_hard_header include/linux/netdevice.h:3208 [inline]
  nf_send_reset6+0xce6/0x1270 net/ipv6/netfilter/nf_reject_ipv6.c:358
  nft_reject_inet_eval+0x3b9/0x690 net/netfilter/nft_reject_inet.c:48
  expr_call_ops_eval net/netfilter/nf_tables_core.c:240 [inline]
  nft_do_chain+0x4ad/0x1da0 net/netfilter/nf_tables_core.c:288
  nft_do_chain_inet+0x418/0x6b0 net/netfilter/nft_chain_filter.c:161
  nf_hook_entry_hookfn include/linux/netfilter.h:154 [inline]
  nf_hook_slow+0xc3/0x220 net/netfilter/core.c:626
  nf_hook include/linux/netfilter.h:269 [inline]
  NF_HOOK include/linux/netfilter.h:312 [inline]
  br_nf_pre_routing_ipv6+0x63e/0x770 net/bridge/br_netfilter_ipv6.c:184
  nf_hook_entry_hookfn include/linux/netfilter.h:154 [inline]
  nf_hook_bridge_pre net/bridge/br_input.c:277 [inline]
  br_handle_frame+0x9fd/0x1530 net/bridge/br_input.c:424
  __netif_receive_skb_core+0x13e8/0x4570 net/core/dev.c:5562
  __netif_receive_skb_one_core net/core/dev.c:5666 [inline]
  __netif_receive_skb+0x12f/0x650 net/core/dev.c:5781
  netif_receive_skb_internal net/core/dev.c:5867 [inline]
  netif_receive_skb+0x1e8/0x890 net/core/dev.c:5926
  tun_rx_batched+0x1b7/0x8f0 drivers/net/tun.c:1550
  tun_get_user+0x3056/0x47e0 drivers/net/tun.c:2007
  tun_chr_write_iter+0x10d/0x1f0 drivers/net/tun.c:2053
  new_sync_write fs/read_write.c:590 [inline]
  vfs_write+0xa6d/0xc90 fs/read_write.c:683
  ksys_write+0x183/0x2b0 fs/read_write.c:736
  do_syscall_x64 arch/x86/entry/common.c:52 [inline]
  do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fdbeeb7d1ff
Code: 89 54 24 18 48 89 74 24 10 89 7c 24 08 e8 c9 8d 02 00 48 8b 54 24 18 48 8b 74 24 10 41 89 c0 8b 7c 24 08 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 31 44 89 c7 48 89 44 24 08 e8 1c 8e 02 00 48
RSP: 002b:00007fdbee5ff000 EFLAGS: 00000293 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007fdbeed36058 RCX: 00007fdbeeb7d1ff
RDX: 000000000000008e RSI: 0000000020000040 RDI: 00000000000000c8
RBP: 00007fdbeebf12be R08: 0000000000000000 R09: 0000000000000000
R10: 000000000000008e R11: 0000000000000293 R12: 0000000000000000
R13: 0000000000000000 R14: 00007fdbeed36058 R15: 00007ffc38de06e8
 </TASK>

Fixes: c8d7b98bec43 ("netfilter: move nf_send_resetX() code to nf_reject_ipvX modules")
Reported-by: syzbot <syzkaller@googlegroups.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
 net/ipv6/netfilter/nf_reject_ipv6.c | 15 +++++++--------
 1 file changed, 7 insertions(+), 8 deletions(-)

diff --git a/net/ipv6/netfilter/nf_reject_ipv6.c b/net/ipv6/netfilter/nf_reject_ipv6.c
index 7db0437140bf..9ae2b2725bf9 100644
--- a/net/ipv6/netfilter/nf_reject_ipv6.c
+++ b/net/ipv6/netfilter/nf_reject_ipv6.c
@@ -268,12 +268,12 @@ 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 sk_buff *nskb;
-	struct tcphdr _otcph;
-	const struct tcphdr *otcph;
-	unsigned int otcplen, hh_len;
 	const struct ipv6hdr *oip6h = ipv6_hdr(oldskb);
 	struct dst_entry *dst = NULL;
+	const struct tcphdr *otcph;
+	struct sk_buff *nskb;
+	struct tcphdr _otcph;
+	unsigned int otcplen;
 	struct flowi6 fl6;
 
 	if ((!(ipv6_addr_type(&oip6h->saddr) & IPV6_ADDR_UNICAST)) ||
@@ -312,9 +312,8 @@ void nf_send_reset6(struct net *net, struct sock *sk, struct sk_buff *oldskb,
 	if (IS_ERR(dst))
 		return;
 
-	hh_len = (dst->dev->hard_header_len + 15)&~15;
-	nskb = alloc_skb(hh_len + 15 + dst->header_len + sizeof(struct ipv6hdr)
-			 + sizeof(struct tcphdr) + dst->trailer_len,
+	nskb = alloc_skb(LL_MAX_HEADER + sizeof(struct ipv6hdr) +
+			 sizeof(struct tcphdr) + dst->trailer_len,
 			 GFP_ATOMIC);
 
 	if (!nskb) {
@@ -327,7 +326,7 @@ void nf_send_reset6(struct net *net, struct sock *sk, struct sk_buff *oldskb,
 
 	nskb->mark = fl6.flowi6_mark;
 
-	skb_reserve(nskb, hh_len + dst->header_len);
+	skb_reserve(nskb, LL_MAX_HEADER);
 	nf_reject_ip6hdr_put(nskb, oldskb, IPPROTO_TCP, ip6_dst_hoplimit(dst));
 	nf_reject_ip6_tcphdr_put(nskb, oldskb, otcph, otcplen);
 
-- 
2.30.2

[PATCH net 4/4] netfilter: nft_payload: sanitize offset and length before calling skb_checksum()

[Pablo Neira Ayuso]

If access to offset + length is larger than the skbuff length, then
skb_checksum() triggers BUG_ON().

skb_checksum() internally subtracts the length parameter while iterating
over skbuff, BUG_ON(len) at the end of it checks that the expected
length to be included in the checksum calculation is fully consumed.

Fixes: 7ec3f7b47b8d ("netfilter: nft_payload: add packet mangling support")
Reported-by: Slavin Liu <slavin-ayu@qq.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
 net/netfilter/nft_payload.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/net/netfilter/nft_payload.c b/net/netfilter/nft_payload.c
index 330609a76fb2..7dfc5343dae4 100644
--- a/net/netfilter/nft_payload.c
+++ b/net/netfilter/nft_payload.c
@@ -904,6 +904,9 @@ static void nft_payload_set_eval(const struct nft_expr *expr,
 	    ((priv->base != NFT_PAYLOAD_TRANSPORT_HEADER &&
 	      priv->base != NFT_PAYLOAD_INNER_HEADER) ||
 	     skb->ip_summed != CHECKSUM_PARTIAL)) {
+		if (offset + priv->len > skb->len)
+			goto err;
+
 		fsum = skb_checksum(skb, offset, priv->len, 0);
 		tsum = csum_partial(src, priv->len, 0);
 
-- 
2.30.2

Re: [PATCH net 0/4] Netfilter fixes for net

[patchwork-bot+netdevbpf]

Hello:

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

On Thu, 31 Oct 2024 11:01:13 +0100 you wrote:
> Hi,
> 
> The following patchset contains Netfilter fixes for net:
> 
> 1) Remove unused parameters in conntrack_dump_flush.c used by
>    selftests, from Liu Jing.
> 
> [...]

Here is the summary with links:
  - [net,1/4] selftests: netfilter: remove unused parameter
    https://git.kernel.org/netdev/net/c/76342e842587
  - [net,2/4] netfilter: Fix use-after-free in get_info()
    https://git.kernel.org/netdev/net/c/f48d258f0ac5
  - [net,3/4] netfilter: nf_reject_ipv6: fix potential crash in nf_send_reset6()
    https://git.kernel.org/netdev/net/c/4ed234fe793f
  - [net,4/4] netfilter: nft_payload: sanitize offset and length before calling skb_checksum()
    https://git.kernel.org/netdev/net/c/d5953d680f7e

You are awesome, thank you!
-- 
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