From b0cdc5dbcf2ba0d99785da5aabf1b17943805b8a Mon Sep 17 00:00:00 2001 From: Paolo Abeni Date: Sat, 11 Dec 2021 17:11:12 +0100 Subject: mptcp: never allow the PM to close a listener subflow Currently, when deleting an endpoint the netlink PM treverses all the local MPTCP sockets, regardless of their status. If an MPTCP listener socket is bound to the IP matching the delete endpoint, the listener TCP socket will be closed. That is unexpected, the PM should only affect data subflows. Additionally, syzbot was able to trigger a NULL ptr dereference due to the above: general protection fault, probably for non-canonical address 0xdffffc0000000003: 0000 [#1] PREEMPT SMP KASAN KASAN: null-ptr-deref in range [0x0000000000000018-0x000000000000001f] CPU: 1 PID: 6550 Comm: syz-executor122 Not tainted 5.16.0-rc4-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:__lock_acquire+0xd7d/0x54a0 kernel/locking/lockdep.c:4897 Code: 0f 0e 41 be 01 00 00 00 0f 86 c8 00 00 00 89 05 69 cc 0f 0e e9 bd 00 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 da 48 c1 ea 03 <80> 3c 02 00 0f 85 f3 2f 00 00 48 81 3b 20 75 17 8f 0f 84 52 f3 ff RSP: 0018:ffffc90001f2f818 EFLAGS: 00010016 RAX: dffffc0000000000 RBX: 0000000000000018 RCX: 0000000000000000 RDX: 0000000000000003 RSI: 0000000000000000 RDI: 0000000000000001 RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000001 R10: 0000000000000000 R11: 000000000000000a R12: 0000000000000000 R13: ffff88801b98d700 R14: 0000000000000000 R15: 0000000000000001 FS: 00007f177cd3d700(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f177cd1b268 CR3: 000000001dd55000 CR4: 0000000000350ee0 Call Trace: lock_acquire kernel/locking/lockdep.c:5637 [inline] lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5602 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] _raw_spin_lock_irqsave+0x39/0x50 kernel/locking/spinlock.c:162 finish_wait+0xc0/0x270 kernel/sched/wait.c:400 inet_csk_wait_for_connect net/ipv4/inet_connection_sock.c:464 [inline] inet_csk_accept+0x7de/0x9d0 net/ipv4/inet_connection_sock.c:497 mptcp_accept+0xe5/0x500 net/mptcp/protocol.c:2865 inet_accept+0xe4/0x7b0 net/ipv4/af_inet.c:739 mptcp_stream_accept+0x2e7/0x10e0 net/mptcp/protocol.c:3345 do_accept+0x382/0x510 net/socket.c:1773 __sys_accept4_file+0x7e/0xe0 net/socket.c:1816 __sys_accept4+0xb0/0x100 net/socket.c:1846 __do_sys_accept net/socket.c:1864 [inline] __se_sys_accept net/socket.c:1861 [inline] __x64_sys_accept+0x71/0xb0 net/socket.c:1861 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x7f177cd8b8e9 Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 b1 14 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:00007f177cd3d308 EFLAGS: 00000246 ORIG_RAX: 000000000000002b RAX: ffffffffffffffda RBX: 00007f177ce13408 RCX: 00007f177cd8b8e9 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000003 RBP: 00007f177ce13400 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f177ce1340c R13: 00007f177cde1004 R14: 6d705f706374706d R15: 0000000000022000 Fix the issue explicitly skipping MPTCP socket in TCP_LISTEN status. Reported-and-tested-by: syzbot+e4d843bb96a9431e6331@syzkaller.appspotmail.com Reviewed-by: Mat Martineau Fixes: 740d798e8767 ("mptcp: remove id 0 address") Signed-off-by: Paolo Abeni Link: https://lore.kernel.org/r/ebc7594cdd420d241fb2172ddb8542ba64717657.1639238695.git.pabeni@redhat.com Signed-off-by: Jakub Kicinski --- net/mptcp/pm_netlink.c | 3 +++ 1 file changed, 3 insertions(+) (limited to 'net/mptcp') diff --git a/net/mptcp/pm_netlink.c b/net/mptcp/pm_netlink.c index 7b96be1e9f14..f523051f5aef 100644 --- a/net/mptcp/pm_netlink.c +++ b/net/mptcp/pm_netlink.c @@ -700,6 +700,9 @@ static void mptcp_pm_nl_rm_addr_or_subflow(struct mptcp_sock *msk, msk_owned_by_me(msk); + if (sk->sk_state == TCP_LISTEN) + return; + if (!rm_list->nr) return; -- cgit From 404cd9a22150f24acf23a8df2ad0c094ba379f57 Mon Sep 17 00:00:00 2001 From: Florian Westphal Date: Tue, 14 Dec 2021 15:16:01 -0800 Subject: mptcp: remove tcp ulp setsockopt support TCP_ULP setsockopt cannot be used for mptcp because its already used internally to plumb subflow (tcp) sockets to the mptcp layer. syzbot managed to trigger a crash for mptcp connections that are in fallback mode: KASAN: null-ptr-deref in range [0x0000000000000020-0x0000000000000027] CPU: 1 PID: 1083 Comm: syz-executor.3 Not tainted 5.16.0-rc2-syzkaller #0 RIP: 0010:tls_build_proto net/tls/tls_main.c:776 [inline] [..] __tcp_set_ulp net/ipv4/tcp_ulp.c:139 [inline] tcp_set_ulp+0x428/0x4c0 net/ipv4/tcp_ulp.c:160 do_tcp_setsockopt+0x455/0x37c0 net/ipv4/tcp.c:3391 mptcp_setsockopt+0x1b47/0x2400 net/mptcp/sockopt.c:638 Remove support for TCP_ULP setsockopt. Fixes: d9e4c1291810 ("mptcp: only admit explicitly supported sockopt") Reported-by: syzbot+1fd9b69cde42967d1add@syzkaller.appspotmail.com Signed-off-by: Florian Westphal Signed-off-by: Mat Martineau Signed-off-by: Jakub Kicinski --- net/mptcp/sockopt.c | 1 - 1 file changed, 1 deletion(-) (limited to 'net/mptcp') diff --git a/net/mptcp/sockopt.c b/net/mptcp/sockopt.c index 0f1e661c2032..f8efd478ac97 100644 --- a/net/mptcp/sockopt.c +++ b/net/mptcp/sockopt.c @@ -525,7 +525,6 @@ static bool mptcp_supported_sockopt(int level, int optname) case TCP_NODELAY: case TCP_THIN_LINEAR_TIMEOUTS: case TCP_CONGESTION: - case TCP_ULP: case TCP_CORK: case TCP_KEEPIDLE: case TCP_KEEPINTVL: -- cgit From d6692b3b97bdc165d150f4c1505751a323a80717 Mon Sep 17 00:00:00 2001 From: Florian Westphal Date: Tue, 14 Dec 2021 15:16:02 -0800 Subject: mptcp: clear 'kern' flag from fallback sockets The mptcp ULP extension relies on sk->sk_sock_kern being set correctly: It prevents setsockopt(fd, IPPROTO_TCP, TCP_ULP, "mptcp", 6); from working for plain tcp sockets (any userspace-exposed socket). But in case of fallback, accept() can return a plain tcp sk. In such case, sk is still tagged as 'kernel' and setsockopt will work. This will crash the kernel, The subflow extension has a NULL ctx->conn mptcp socket: BUG: KASAN: null-ptr-deref in subflow_data_ready+0x181/0x2b0 Call Trace: tcp_data_ready+0xf8/0x370 [..] Fixes: cf7da0d66cc1 ("mptcp: Create SUBFLOW socket for incoming connections") Signed-off-by: Florian Westphal Signed-off-by: Mat Martineau Signed-off-by: Jakub Kicinski --- net/mptcp/protocol.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'net/mptcp') diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index c82a76d2d0bf..6dc1ff07994c 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -2879,7 +2879,7 @@ static struct sock *mptcp_accept(struct sock *sk, int flags, int *err, */ if (WARN_ON_ONCE(!new_mptcp_sock)) { tcp_sk(newsk)->is_mptcp = 0; - return newsk; + goto out; } /* acquire the 2nd reference for the owning socket */ @@ -2891,6 +2891,8 @@ static struct sock *mptcp_accept(struct sock *sk, int flags, int *err, MPTCP_MIB_MPCAPABLEPASSIVEFALLBACK); } +out: + newsk->sk_kern_sock = kern; return newsk; } -- cgit From 3d79e3756ca90f7a6087b77b62c1d9c0801e0820 Mon Sep 17 00:00:00 2001 From: Maxim Galaganov Date: Tue, 14 Dec 2021 15:16:03 -0800 Subject: mptcp: fix deadlock in __mptcp_push_pending() __mptcp_push_pending() may call mptcp_flush_join_list() with subflow socket lock held. If such call hits mptcp_sockopt_sync_all() then subsequently __mptcp_sockopt_sync() could try to lock the subflow socket for itself, causing a deadlock. sysrq: Show Blocked State task:ss-server state:D stack: 0 pid: 938 ppid: 1 flags:0x00000000 Call Trace: __schedule+0x2d6/0x10c0 ? __mod_memcg_state+0x4d/0x70 ? csum_partial+0xd/0x20 ? _raw_spin_lock_irqsave+0x26/0x50 schedule+0x4e/0xc0 __lock_sock+0x69/0x90 ? do_wait_intr_irq+0xa0/0xa0 __lock_sock_fast+0x35/0x50 mptcp_sockopt_sync_all+0x38/0xc0 __mptcp_push_pending+0x105/0x200 mptcp_sendmsg+0x466/0x490 sock_sendmsg+0x57/0x60 __sys_sendto+0xf0/0x160 ? do_wait_intr_irq+0xa0/0xa0 ? fpregs_restore_userregs+0x12/0xd0 __x64_sys_sendto+0x20/0x30 do_syscall_64+0x38/0x90 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x7f9ba546c2d0 RSP: 002b:00007ffdc3b762d8 EFLAGS: 00000246 ORIG_RAX: 000000000000002c RAX: ffffffffffffffda RBX: 00007f9ba56c8060 RCX: 00007f9ba546c2d0 RDX: 000000000000077a RSI: 0000000000e5e180 RDI: 0000000000000234 RBP: 0000000000cc57f0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f9ba56c8060 R13: 0000000000b6ba60 R14: 0000000000cc7840 R15: 41d8685b1d7901b8 Fix the issue by using __mptcp_flush_join_list() instead of plain mptcp_flush_join_list() inside __mptcp_push_pending(), as suggested by Florian. The sockopt sync will be deferred to the workqueue. Fixes: 1b3e7ede1365 ("mptcp: setsockopt: handle SO_KEEPALIVE and SO_PRIORITY") Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/244 Suggested-by: Florian Westphal Reviewed-by: Florian Westphal Signed-off-by: Maxim Galaganov Signed-off-by: Mat Martineau Signed-off-by: Jakub Kicinski --- net/mptcp/protocol.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'net/mptcp') diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index 6dc1ff07994c..54613f5b7521 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -1524,7 +1524,7 @@ void __mptcp_push_pending(struct sock *sk, unsigned int flags) int ret = 0; prev_ssk = ssk; - mptcp_flush_join_list(msk); + __mptcp_flush_join_list(msk); ssk = mptcp_subflow_get_send(msk); /* First check. If the ssk has changed since -- cgit