From patchwork Wed Oct 2 20:24:20 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Pablo Neira Ayuso X-Patchwork-Id: 13820345 X-Patchwork-Delegate: kuba@kernel.org Received: from mail.netfilter.org (mail.netfilter.org [217.70.188.207]) by smtp.subspace.kernel.org (Postfix) with ESMTP id AC18E216A34; Wed, 2 Oct 2024 20:24:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.70.188.207 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1727900676; cv=none; b=ID+iA6q3cunEy+ifwOiqKcpjDEAEtHbcIeWUJ7dneNcUIgOWOso9j9OTCqN3cm7PLQ6Tl8CEaTqu8LnNBKLGpJgc+FwZ3aQu0b2ZmgcxmVE7M41C/jj/4jqGpoFE1j6gsq3BA/ArIf1KbkwNpwucuywQS+OCCEKWRrwb6CB70Hs= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1727900676; c=relaxed/simple; bh=uwKj2zMKYcIcKX/KbwZG7DFo9TtsETS6E5OFSoXekEU=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=kHOc41Ft2w3+JK1nb3Nnh3VGBF/RvKzx1bsspjCCHAdNJEfuZvPY+1G5Rlyja00K/M7ldNu2b9x4Q7qLawQ87KZsNcZgeRXpQtfXvK3MYyzp5wcHtaw27lthxTIkokJY/ir/Q0FBBnb662AqqrS9HAlt4SbwD8ecAYVvyPGkaaM= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=netfilter.org; spf=pass smtp.mailfrom=netfilter.org; arc=none smtp.client-ip=217.70.188.207 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=netfilter.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=netfilter.org From: Pablo Neira Ayuso To: netfilter-devel@vger.kernel.org Cc: davem@davemloft.net, netdev@vger.kernel.org, kuba@kernel.org, pabeni@redhat.com, edumazet@google.com, fw@strlen.de Subject: [PATCH net 3/4] netfilter: nf_tables: prevent nf_skb_duplicated corruption Date: Wed, 2 Oct 2024 22:24:20 +0200 Message-Id: <20241002202421.1281311-4-pablo@netfilter.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20241002202421.1281311-1-pablo@netfilter.org> References: <20241002202421.1281311-1-pablo@netfilter.org> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Patchwork-Delegate: kuba@kernel.org From: Eric Dumazet syzbot found that nf_dup_ipv4() or nf_dup_ipv6() could write per-cpu variable nf_skb_duplicated in an unsafe way [1]. Disabling preemption as hinted by the splat is not enough, we have to disable soft interrupts as well. [1] BUG: using __this_cpu_write() in preemptible [00000000] code: syz.4.282/6316 caller is nf_dup_ipv4+0x651/0x8f0 net/ipv4/netfilter/nf_dup_ipv4.c:87 CPU: 0 UID: 0 PID: 6316 Comm: syz.4.282 Not tainted 6.11.0-rc7-syzkaller-00104-g7052622fccb1 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/06/2024 Call Trace: __dump_stack lib/dump_stack.c:93 [inline] dump_stack_lvl+0x241/0x360 lib/dump_stack.c:119 check_preemption_disabled+0x10e/0x120 lib/smp_processor_id.c:49 nf_dup_ipv4+0x651/0x8f0 net/ipv4/netfilter/nf_dup_ipv4.c:87 nft_dup_ipv4_eval+0x1db/0x300 net/ipv4/netfilter/nft_dup_ipv4.c:30 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_ipv4+0x202/0x320 net/netfilter/nft_chain_filter.c:23 nf_hook_entry_hookfn include/linux/netfilter.h:154 [inline] nf_hook_slow+0xc3/0x220 net/netfilter/core.c:626 nf_hook+0x2c4/0x450 include/linux/netfilter.h:269 NF_HOOK_COND include/linux/netfilter.h:302 [inline] ip_output+0x185/0x230 net/ipv4/ip_output.c:433 ip_local_out net/ipv4/ip_output.c:129 [inline] ip_send_skb+0x74/0x100 net/ipv4/ip_output.c:1495 udp_send_skb+0xacf/0x1650 net/ipv4/udp.c:981 udp_sendmsg+0x1c21/0x2a60 net/ipv4/udp.c:1269 sock_sendmsg_nosec net/socket.c:730 [inline] __sock_sendmsg+0x1a6/0x270 net/socket.c:745 ____sys_sendmsg+0x525/0x7d0 net/socket.c:2597 ___sys_sendmsg net/socket.c:2651 [inline] __sys_sendmmsg+0x3b2/0x740 net/socket.c:2737 __do_sys_sendmmsg net/socket.c:2766 [inline] __se_sys_sendmmsg net/socket.c:2763 [inline] __x64_sys_sendmmsg+0xa0/0xb0 net/socket.c:2763 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: 0033:0x7f4ce4f7def9 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f4ce5d4a038 EFLAGS: 00000246 ORIG_RAX: 0000000000000133 RAX: ffffffffffffffda RBX: 00007f4ce5135f80 RCX: 00007f4ce4f7def9 RDX: 0000000000000001 RSI: 0000000020005d40 RDI: 0000000000000006 RBP: 00007f4ce4ff0b76 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 00007f4ce5135f80 R15: 00007ffd4cbc6d68 Fixes: d877f07112f1 ("netfilter: nf_tables: add nft_dup expression") Reported-by: syzbot Signed-off-by: Eric Dumazet Signed-off-by: Pablo Neira Ayuso --- net/ipv4/netfilter/nf_dup_ipv4.c | 7 +++++-- net/ipv6/netfilter/nf_dup_ipv6.c | 7 +++++-- 2 files changed, 10 insertions(+), 4 deletions(-) diff --git a/net/ipv4/netfilter/nf_dup_ipv4.c b/net/ipv4/netfilter/nf_dup_ipv4.c index f4aed0789d69..ec94ee1051c7 100644 --- a/net/ipv4/netfilter/nf_dup_ipv4.c +++ b/net/ipv4/netfilter/nf_dup_ipv4.c @@ -53,8 +53,9 @@ void nf_dup_ipv4(struct net *net, struct sk_buff *skb, unsigned int hooknum, { struct iphdr *iph; + local_bh_disable(); if (this_cpu_read(nf_skb_duplicated)) - return; + goto out; /* * Copy the skb, and route the copy. Will later return %XT_CONTINUE for * the original skb, which should continue on its way as if nothing has @@ -62,7 +63,7 @@ void nf_dup_ipv4(struct net *net, struct sk_buff *skb, unsigned int hooknum, */ skb = pskb_copy(skb, GFP_ATOMIC); if (skb == NULL) - return; + goto out; #if IS_ENABLED(CONFIG_NF_CONNTRACK) /* Avoid counting cloned packets towards the original connection. */ @@ -91,6 +92,8 @@ void nf_dup_ipv4(struct net *net, struct sk_buff *skb, unsigned int hooknum, } else { kfree_skb(skb); } +out: + local_bh_enable(); } EXPORT_SYMBOL_GPL(nf_dup_ipv4); diff --git a/net/ipv6/netfilter/nf_dup_ipv6.c b/net/ipv6/netfilter/nf_dup_ipv6.c index a0a2de30be3e..0c39c77fe8a8 100644 --- a/net/ipv6/netfilter/nf_dup_ipv6.c +++ b/net/ipv6/netfilter/nf_dup_ipv6.c @@ -47,11 +47,12 @@ static bool nf_dup_ipv6_route(struct net *net, struct sk_buff *skb, void nf_dup_ipv6(struct net *net, struct sk_buff *skb, unsigned int hooknum, const struct in6_addr *gw, int oif) { + local_bh_disable(); if (this_cpu_read(nf_skb_duplicated)) - return; + goto out; skb = pskb_copy(skb, GFP_ATOMIC); if (skb == NULL) - return; + goto out; #if IS_ENABLED(CONFIG_NF_CONNTRACK) nf_reset_ct(skb); @@ -69,6 +70,8 @@ void nf_dup_ipv6(struct net *net, struct sk_buff *skb, unsigned int hooknum, } else { kfree_skb(skb); } +out: + local_bh_enable(); } EXPORT_SYMBOL_GPL(nf_dup_ipv6);