From patchwork Mon Oct 14 14:06:00 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Matthieu Baerts X-Patchwork-Id: 13835092 X-Patchwork-Delegate: matthieu.baerts@tessares.net Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2DEDC1AC45F; Mon, 14 Oct 2024 14:06:51 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728914812; cv=none; b=fj7xHS3mgSmDjPQ0yCc7YEwd+Si9kB43Tdo5GBGcsaVIgCs8R5NWC13CIPHg8I1+NWHTHKPI40yNfBkeBlI1dIpaRJsqpfoj+pQVXCHgQ8TMEKz9dutR+YMvRgDVPz13FmvEyOFD1NA9RI8s9sNk7uYSoL1jRuZRglcaWMlXBEk= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728914812; c=relaxed/simple; bh=4rFBOgxbRxsGSItMVxpTTzO12dDwFek2/2aDpf+2Uh8=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=iVWVUF5uJQFZS8diZPTRuTZ/DvLcZ4TWQ8la8X7b8yw9tAPhEdP2MmjPRezy+24RqRkXKtcLm0rSfi6yGDwQKVFjH4MfUnwFfWAmAweyZCaB+aOOc0RgPexJeKVs/vpQA6kfBz7IS+VeW/6GQlTQlJWRscRqiFhNQQBAP+Ifkm8= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=kLFM+t4W; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="kLFM+t4W" Received: by smtp.kernel.org (Postfix) with ESMTPSA id BDFB4C4CEC6; Mon, 14 Oct 2024 14:06:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1728914811; bh=4rFBOgxbRxsGSItMVxpTTzO12dDwFek2/2aDpf+2Uh8=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=kLFM+t4WsT3A+MtZiQRnQM8GPLsOtEDyKzXG21x5DuiDLp8Ms8PThb0swhh6mc3vn pa25GoGJFfAcrGz7k3EIUe7bzPRuSohORG1+Hs99pnwvFlh0WY5VixE7CM8VCj+83p 1dCYrUPLperbsKbFe90JcgsQIac5DNi24EaMyz+LLx+JdiSyuzjtUyq3iXZ8KtNWpO XkgKJ5I1mv6uLo8LBmhsfWo3DrZpC0qxX6I7QdKLK40bGstSxAV1uCQxMWd6GGu4OQ 0h321UAvwpYeA83V4xF+dRjI4UM62bEgSFD5vVAXHP7y2NJ5cvdiKnf5qThIK6Aj0q l/c63/CZA66Eg== From: "Matthieu Baerts (NGI0)" Date: Mon, 14 Oct 2024 16:06:00 +0200 Subject: [PATCH net v2 1/2] mptcp: prevent MPC handshake on port-based signal endpoints Precedence: bulk X-Mailing-List: mptcp@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-Id: <20241014-net-mptcp-mpc-port-endp-v2-1-7faea8e6b6ae@kernel.org> References: <20241014-net-mptcp-mpc-port-endp-v2-0-7faea8e6b6ae@kernel.org> In-Reply-To: <20241014-net-mptcp-mpc-port-endp-v2-0-7faea8e6b6ae@kernel.org> To: mptcp@lists.linux.dev, Mat Martineau , Geliang Tang , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Shuah Khan Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, Cong Wang , "Matthieu Baerts (NGI0)" , stable@vger.kernel.org, syzbot+f4aacdfef2c6a6529c3e@syzkaller.appspotmail.com X-Mailer: b4 0.14.2 X-Developer-Signature: v=1; a=openpgp-sha256; l=12029; i=matttbe@kernel.org; h=from:subject:message-id; bh=n0ptyci1csBA/gH5/LyBQXyU/aNH+nz6jWKLh20Ti7U=; b=owEBbQKS/ZANAwAIAfa3gk9CaaBzAcsmYgBnDSV0YpPvplI2XYwyN9P52fx1YJPxMgNRJRmak BcukA7cK3WJAjMEAAEIAB0WIQToy4X3aHcFem4n93r2t4JPQmmgcwUCZw0ldAAKCRD2t4JPQmmg c/k6EACDQzdJ1B4LjkPrKTM0IlO4HnWMGFfY+wQiS2/tRCz7HeVWzaR9q95aDz0dI5ik2r34DEA kNKH657hX1mFQIngEH5KHUh4bLDQm7ewSSrs9dEztSuk+hov6XRCWsLKHcvqJ4tH8oQB8jrXAQE ZuNQuB0A1wRpbwsqi/x1ygHle83jV6dwmf/THrk4eUg9e3+jcI7B63/xX20svWzLOIc3VDfCTCP uOjOpeTQRJ4Pb+zbkLnFcLarzFGN5+lqp89vlh7ngwQbO5+u3U94yHCbOOl99ejgrsJ2tx0IHAb 7Syb4HYkJznathMmNnGyksJgR2lS/z4+LoAUl/mtTI9/bVMvgPlD3KAtIwVnoGT3kHdAeOA6KH1 nK3tPvAJbHO8h+xP2jQKZbXcsVyKoGe+jXPyozAN2SZGIB16Gdeer6XWPeIwRP1fqYnq2YTQRI1 ddKNcTbluEvlZVdTJx2FLJmrkGmrpV2zovR/U9bVZDkx5OEt8CJ5+auEDP8YXvMJc94dw4y21t+ +kmgqK8yl1Ak1wlzlhil+v1b/eMh0ifDq0IfYN+eNmIYLvsPE/OCftMuJu3Ugg5IHRKqgvvCUvw mF/WEeVnavI8yhChxo3R3tlyfGl+GfPl2bOYLSte80S6XYGK4ueDWXXysq6k1xSm2CKzeg0lGB1 0ZhzJdl9/2YfkvQ== X-Developer-Key: i=matttbe@kernel.org; a=openpgp; fpr=E8CB85F76877057A6E27F77AF6B7824F4269A073 From: Paolo Abeni Syzkaller reported a lockdep splat: ============================================ WARNING: possible recursive locking detected 6.11.0-rc6-syzkaller-00019-g67784a74e258 #0 Not tainted -------------------------------------------- syz-executor364/5113 is trying to acquire lock: ffff8880449f1958 (k-slock-AF_INET){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline] ffff8880449f1958 (k-slock-AF_INET){+.-.}-{2:2}, at: sk_clone_lock+0x2cd/0xf40 net/core/sock.c:2328 but task is already holding lock: ffff88803fe3cb58 (k-slock-AF_INET){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline] ffff88803fe3cb58 (k-slock-AF_INET){+.-.}-{2:2}, at: sk_clone_lock+0x2cd/0xf40 net/core/sock.c:2328 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(k-slock-AF_INET); lock(k-slock-AF_INET); *** DEADLOCK *** May be due to missing lock nesting notation 7 locks held by syz-executor364/5113: #0: ffff8880449f0e18 (sk_lock-AF_INET){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1607 [inline] #0: ffff8880449f0e18 (sk_lock-AF_INET){+.+.}-{0:0}, at: mptcp_sendmsg+0x153/0x1b10 net/mptcp/protocol.c:1806 #1: ffff88803fe39ad8 (k-sk_lock-AF_INET){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1607 [inline] #1: ffff88803fe39ad8 (k-sk_lock-AF_INET){+.+.}-{0:0}, at: mptcp_sendmsg_fastopen+0x11f/0x530 net/mptcp/protocol.c:1727 #2: ffffffff8e938320 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:326 [inline] #2: ffffffff8e938320 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:838 [inline] #2: ffffffff8e938320 (rcu_read_lock){....}-{1:2}, at: __ip_queue_xmit+0x5f/0x1b80 net/ipv4/ip_output.c:470 #3: ffffffff8e938320 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:326 [inline] #3: ffffffff8e938320 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:838 [inline] #3: ffffffff8e938320 (rcu_read_lock){....}-{1:2}, at: ip_finish_output2+0x45f/0x1390 net/ipv4/ip_output.c:228 #4: ffffffff8e938320 (rcu_read_lock){....}-{1:2}, at: local_lock_acquire include/linux/local_lock_internal.h:29 [inline] #4: ffffffff8e938320 (rcu_read_lock){....}-{1:2}, at: process_backlog+0x33b/0x15b0 net/core/dev.c:6104 #5: ffffffff8e938320 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:326 [inline] #5: ffffffff8e938320 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:838 [inline] #5: ffffffff8e938320 (rcu_read_lock){....}-{1:2}, at: ip_local_deliver_finish+0x230/0x5f0 net/ipv4/ip_input.c:232 #6: ffff88803fe3cb58 (k-slock-AF_INET){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline] #6: ffff88803fe3cb58 (k-slock-AF_INET){+.-.}-{2:2}, at: sk_clone_lock+0x2cd/0xf40 net/core/sock.c:2328 stack backtrace: CPU: 0 UID: 0 PID: 5113 Comm: syz-executor364 Not tainted 6.11.0-rc6-syzkaller-00019-g67784a74e258 #0 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014 Call Trace: __dump_stack lib/dump_stack.c:93 [inline] dump_stack_lvl+0x241/0x360 lib/dump_stack.c:119 check_deadlock kernel/locking/lockdep.c:3061 [inline] validate_chain+0x15d3/0x5900 kernel/locking/lockdep.c:3855 __lock_acquire+0x137a/0x2040 kernel/locking/lockdep.c:5142 lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5759 __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline] _raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154 spin_lock include/linux/spinlock.h:351 [inline] sk_clone_lock+0x2cd/0xf40 net/core/sock.c:2328 mptcp_sk_clone_init+0x32/0x13c0 net/mptcp/protocol.c:3279 subflow_syn_recv_sock+0x931/0x1920 net/mptcp/subflow.c:874 tcp_check_req+0xfe4/0x1a20 net/ipv4/tcp_minisocks.c:853 tcp_v4_rcv+0x1c3e/0x37f0 net/ipv4/tcp_ipv4.c:2267 ip_protocol_deliver_rcu+0x22e/0x440 net/ipv4/ip_input.c:205 ip_local_deliver_finish+0x341/0x5f0 net/ipv4/ip_input.c:233 NF_HOOK+0x3a4/0x450 include/linux/netfilter.h:314 NF_HOOK+0x3a4/0x450 include/linux/netfilter.h:314 __netif_receive_skb_one_core net/core/dev.c:5661 [inline] __netif_receive_skb+0x2bf/0x650 net/core/dev.c:5775 process_backlog+0x662/0x15b0 net/core/dev.c:6108 __napi_poll+0xcb/0x490 net/core/dev.c:6772 napi_poll net/core/dev.c:6841 [inline] net_rx_action+0x89b/0x1240 net/core/dev.c:6963 handle_softirqs+0x2c4/0x970 kernel/softirq.c:554 do_softirq+0x11b/0x1e0 kernel/softirq.c:455 __local_bh_enable_ip+0x1bb/0x200 kernel/softirq.c:382 local_bh_enable include/linux/bottom_half.h:33 [inline] rcu_read_unlock_bh include/linux/rcupdate.h:908 [inline] __dev_queue_xmit+0x1763/0x3e90 net/core/dev.c:4450 dev_queue_xmit include/linux/netdevice.h:3105 [inline] neigh_hh_output include/net/neighbour.h:526 [inline] neigh_output include/net/neighbour.h:540 [inline] ip_finish_output2+0xd41/0x1390 net/ipv4/ip_output.c:235 ip_local_out net/ipv4/ip_output.c:129 [inline] __ip_queue_xmit+0x118c/0x1b80 net/ipv4/ip_output.c:535 __tcp_transmit_skb+0x2544/0x3b30 net/ipv4/tcp_output.c:1466 tcp_rcv_synsent_state_process net/ipv4/tcp_input.c:6542 [inline] tcp_rcv_state_process+0x2c32/0x4570 net/ipv4/tcp_input.c:6729 tcp_v4_do_rcv+0x77d/0xc70 net/ipv4/tcp_ipv4.c:1934 sk_backlog_rcv include/net/sock.h:1111 [inline] __release_sock+0x214/0x350 net/core/sock.c:3004 release_sock+0x61/0x1f0 net/core/sock.c:3558 mptcp_sendmsg_fastopen+0x1ad/0x530 net/mptcp/protocol.c:1733 mptcp_sendmsg+0x1884/0x1b10 net/mptcp/protocol.c:1812 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: 0033:0x7f04fb13a6b9 Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 01 1a 00 00 90 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 b8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007ffd651f42d8 EFLAGS: 00000246 ORIG_RAX: 0000000000000133 RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00007f04fb13a6b9 RDX: 0000000000000001 RSI: 0000000020000d00 RDI: 0000000000000004 RBP: 00007ffd651f4310 R08: 0000000000000001 R09: 0000000000000001 R10: 0000000020000080 R11: 0000000000000246 R12: 00000000000f4240 R13: 00007f04fb187449 R14: 00007ffd651f42f4 R15: 00007ffd651f4300 As noted by Cong Wang, the splat is false positive, but the code path leading to the report is an unexpected one: a client is attempting an MPC handshake towards the in-kernel listener created by the in-kernel PM for a port based signal endpoint. Such connection will be never accepted; many of them can make the listener queue full and preventing the creation of MPJ subflow via such listener - its intended role. Explicitly detect this scenario at initial-syn time and drop the incoming MPC request. Fixes: 1729cf186d8a ("mptcp: create the listening socket for new port") Cc: stable@vger.kernel.org Reported-by: syzbot+f4aacdfef2c6a6529c3e@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=f4aacdfef2c6a6529c3e Cc: Cong Wang Signed-off-by: Paolo Abeni Reviewed-by: Matthieu Baerts (NGI0) Reviewed-by: Mat Martineau Signed-off-by: Matthieu Baerts (NGI0) --- net/mptcp/mib.c | 1 + net/mptcp/mib.h | 1 + net/mptcp/pm_netlink.c | 1 + net/mptcp/protocol.h | 1 + net/mptcp/subflow.c | 11 +++++++++++ 5 files changed, 15 insertions(+) diff --git a/net/mptcp/mib.c b/net/mptcp/mib.c index ad88bd3c58dffed8335eedb43ca6290418e3c4f4..19eb9292bd6093a760b41f98c1774fd2490c48e3 100644 --- a/net/mptcp/mib.c +++ b/net/mptcp/mib.c @@ -17,6 +17,7 @@ static const struct snmp_mib mptcp_snmp_list[] = { SNMP_MIB_ITEM("MPCapableFallbackSYNACK", MPTCP_MIB_MPCAPABLEACTIVEFALLBACK), SNMP_MIB_ITEM("MPCapableSYNTXDrop", MPTCP_MIB_MPCAPABLEACTIVEDROP), SNMP_MIB_ITEM("MPCapableSYNTXDisabled", MPTCP_MIB_MPCAPABLEACTIVEDISABLED), + SNMP_MIB_ITEM("MPCapableEndpAttempt", MPTCP_MIB_MPCAPABLEENDPATTEMPT), SNMP_MIB_ITEM("MPFallbackTokenInit", MPTCP_MIB_TOKENFALLBACKINIT), SNMP_MIB_ITEM("MPTCPRetrans", MPTCP_MIB_RETRANSSEGS), SNMP_MIB_ITEM("MPJoinNoTokenFound", MPTCP_MIB_JOINNOTOKEN), diff --git a/net/mptcp/mib.h b/net/mptcp/mib.h index 3206cdda8bb1067f9a8354fd45deed86b67ac7da..128282982843a07614a46f9b2c2f7c708306c769 100644 --- a/net/mptcp/mib.h +++ b/net/mptcp/mib.h @@ -12,6 +12,7 @@ enum linux_mptcp_mib_field { MPTCP_MIB_MPCAPABLEACTIVEFALLBACK, /* Client-side fallback during 3-way handshake */ MPTCP_MIB_MPCAPABLEACTIVEDROP, /* Client-side fallback due to a MPC drop */ MPTCP_MIB_MPCAPABLEACTIVEDISABLED, /* Client-side disabled due to past issues */ + MPTCP_MIB_MPCAPABLEENDPATTEMPT, /* Prohibited MPC to port-based endp */ MPTCP_MIB_TOKENFALLBACKINIT, /* Could not init/allocate token */ MPTCP_MIB_RETRANSSEGS, /* Segments retransmitted at the MPTCP-level */ MPTCP_MIB_JOINNOTOKEN, /* Received MP_JOIN but the token was not found */ diff --git a/net/mptcp/pm_netlink.c b/net/mptcp/pm_netlink.c index f6f0a38a0750f82bc909f02a75beec980d951f1f..1a78998fe1f49510ef1f487c8cd5b369a37fb20d 100644 --- a/net/mptcp/pm_netlink.c +++ b/net/mptcp/pm_netlink.c @@ -1121,6 +1121,7 @@ static int mptcp_pm_nl_create_listen_socket(struct sock *sk, */ inet_sk_state_store(newsk, TCP_LISTEN); lock_sock(ssk); + WRITE_ONCE(mptcp_subflow_ctx(ssk)->pm_listener, true); err = __inet_listen_sk(ssk, backlog); if (!err) mptcp_event_pm_listener(ssk, MPTCP_EVENT_LISTENER_CREATED); diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h index 74417aae08d0f488bc358ce6cd931540650bb7be..568a72702b080d7610425ce5c3a409c7b88da13a 100644 --- a/net/mptcp/protocol.h +++ b/net/mptcp/protocol.h @@ -535,6 +535,7 @@ struct mptcp_subflow_context { __unused : 8; bool data_avail; bool scheduled; + bool pm_listener; /* a listener managed by the kernel PM? */ u32 remote_nonce; u64 thmac; u32 local_nonce; diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c index 25dde81bcb7575958635aaf14a5b8e9a5005e05f..6170f2fff71e4f9d64837f2ebf4d81bba224fafb 100644 --- a/net/mptcp/subflow.c +++ b/net/mptcp/subflow.c @@ -132,6 +132,13 @@ static void subflow_add_reset_reason(struct sk_buff *skb, u8 reason) } } +static int subflow_reset_req_endp(struct request_sock *req, struct sk_buff *skb) +{ + SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_MPCAPABLEENDPATTEMPT); + subflow_add_reset_reason(skb, MPTCP_RST_EPROHIBIT); + return -EPERM; +} + /* Init mptcp request socket. * * Returns an error code if a JOIN has failed and a TCP reset @@ -165,6 +172,8 @@ static int subflow_check_req(struct request_sock *req, if (opt_mp_capable) { SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_MPCAPABLEPASSIVE); + if (unlikely(listener->pm_listener)) + return subflow_reset_req_endp(req, skb); if (opt_mp_join) return 0; } else if (opt_mp_join) { @@ -172,6 +181,8 @@ static int subflow_check_req(struct request_sock *req, if (mp_opt.backup) SUBFLOW_REQ_INC_STATS(req, MPTCP_MIB_JOINSYNBACKUPRX); + } else if (unlikely(listener->pm_listener)) { + return subflow_reset_req_endp(req, skb); } if (opt_mp_capable && listener->request_mptcp) {