talos-op-linux/net/mptcp, branch master

mptcp: make the symbol 'mptcp_sk_clone_lock' static

2020-02-10T09:23:00+00:00

Fix the following sparse warning: net/mptcp/protocol.c:646:13: warning: symbol 'mptcp_sk_clone_lock' was not declared. Should it be static? Fixes: b0519de8b3f1 ("mptcp: fix use-after-free for ipv6") Signed-off-by: Chen Wandun Signed-off-by: David S. Miller

mptcp: fix use-after-free for ipv6

2020-02-06T10:25:09+00:00

Turns out that when we accept a new subflow, the newly created inet_sk(tcp_sk)->pinet6 points at the ipv6_pinfo structure of the listener socket. This wasn't caught by the selftest because it closes the accepted fd before the listening one. adding a close(listenfd) after accept returns is enough: BUG: KASAN: use-after-free in inet6_getname+0x6ba/0x790 Read of size 1 at addr ffff88810e310866 by task mptcp_connect/2518 Call Trace: inet6_getname+0x6ba/0x790 __sys_getpeername+0x10b/0x250 __x64_sys_getpeername+0x6f/0xb0 also alter test program to exercise this. Reported-by: Christoph Paasch Signed-off-by: Florian Westphal Signed-off-by: David S. Miller

mptcp: fix use-after-free on tcp fallback

2020-02-05T13:08:03+00:00

When an mptcp socket connects to a tcp peer or when a middlebox interferes with tcp options, mptcp needs to fall back to plain tcp. Problem is that mptcp is trying to be too clever in this case: It attempts to close the mptcp meta sk and transparently replace it with the (only) subflow tcp sk. Unfortunately, this is racy -- the socket is already exposed to userspace. Any parallel calls to send/recv/setsockopt etc. can cause use-after-free: BUG: KASAN: use-after-free in atomic_try_cmpxchg include/asm-generic/atomic-instrumented.h:693 [inline] CPU: 1 PID: 2083 Comm: syz-executor.1 Not tainted 5.5.0 #2 atomic_try_cmpxchg include/asm-generic/atomic-instrumented.h:693 [inline] queued_spin_lock include/asm-generic/qspinlock.h:78 [inline] do_raw_spin_lock include/linux/spinlock.h:181 [inline] __raw_spin_lock_bh include/linux/spinlock_api_smp.h:136 [inline] _raw_spin_lock_bh+0x71/0xd0 kernel/locking/spinlock.c:175 spin_lock_bh include/linux/spinlock.h:343 [inline] __lock_sock+0x105/0x190 net/core/sock.c:2414 lock_sock_nested+0x10f/0x140 net/core/sock.c:2938 lock_sock include/net/sock.h:1516 [inline] mptcp_setsockopt+0x2f/0x1f0 net/mptcp/protocol.c:800 __sys_setsockopt+0x152/0x240 net/socket.c:2130 __do_sys_setsockopt net/socket.c:2146 [inline] __se_sys_setsockopt net/socket.c:2143 [inline] __x64_sys_setsockopt+0xba/0x150 net/socket.c:2143 do_syscall_64+0xb7/0x3d0 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x44/0xa9 While the use-after-free can be resolved, there is another problem: sock->ops and sock->sk assignments are not atomic, i.e. we may get calls into mptcp functions with sock->sk already pointing at the subflow socket, or calls into tcp functions with a mptcp meta sk. Remove the fallback code and call the relevant functions for the (only) subflow in case the mptcp socket is connected to tcp peer. Reported-by: Christoph Paasch Diagnosed-by: Paolo Abeni Signed-off-by: Florian Westphal Reviewed-by: Mat Martineau Tested-by: Christoph Paasch Signed-off-by: David S. Miller

mptcp: Fix undefined mptcp_handle_ipv6_mapped for modular IPV6

2020-01-30T09:55:54+00:00

If CONFIG_MPTCP=y, CONFIG_MPTCP_IPV6=n, and CONFIG_IPV6=m: ERROR: "mptcp_handle_ipv6_mapped" [net/ipv6/ipv6.ko] undefined! This does not happen if CONFIG_MPTCP_IPV6=y, as CONFIG_MPTCP_IPV6 selects CONFIG_IPV6, and thus forces CONFIG_IPV6 builtin. As exporting a symbol for an empty function would be a bit wasteful, fix this by providing a dummy version of mptcp_handle_ipv6_mapped() for the CONFIG_MPTCP_IPV6=n case. Rename mptcp_handle_ipv6_mapped() to mptcpv6_handle_mapped(), to make it clear this is a pure-IPV6 function, just like mptcpv6_init(). Fixes: cec37a6e41aae7bf ("mptcp: Handle MP_CAPABLE options for outgoing connections") Signed-off-by: Geert Uytterhoeven Signed-off-by: David S. Miller

mptcp: MPTCP_HMAC_TEST should depend on MPTCP

2020-01-30T08:55:37+00:00

As the MPTCP HMAC test is integrated into the MPTCP code, it can be built only when MPTCP is enabled. Hence when MPTCP is disabled, asking the user if the test code should be enabled is futile. Wrap the whole block of MPTCP-specific config options inside a check for MPTCP. While at it, drop the "default n" for MPTCP_HMAC_TEST, as that is the default anyway. Fixes: 65492c5a6ab5df50 ("mptcp: move from sha1 (v0) to sha256 (v1)") Signed-off-by: Geert Uytterhoeven Reviewed-by: Mat Martineau Signed-off-by: David S. Miller

mptcp: Fix incorrect IPV6 dependency check

2020-01-30T08:55:37+00:00

If CONFIG_MPTCP=y, CONFIG_MPTCP_IPV6=n, and CONFIG_IPV6=m: net/mptcp/protocol.o: In function `__mptcp_tcp_fallback': protocol.c:(.text+0x786): undefined reference to `inet6_stream_ops' Fix this by checking for CONFIG_MPTCP_IPV6 instead of CONFIG_IPV6, like is done in all other places in the mptcp code. Fixes: 8ab183deb26a3b79 ("mptcp: cope with later TCP fallback") Signed-off-by: Geert Uytterhoeven Reviewed-by: Mat Martineau Signed-off-by: David S. Miller

mptcp: handle tcp fallback when using syn cookies

2020-01-29T16:45:20+00:00

We can't deal with syncookie mode yet, the syncookie rx path will create tcp reqsk, i.e. we get OOB access because we treat tcp reqsk as mptcp reqsk one: TCP: SYN flooding on port 20002. Sending cookies. BUG: KASAN: slab-out-of-bounds in subflow_syn_recv_sock+0x451/0x4d0 net/mptcp/subflow.c:191 Read of size 1 at addr ffff8881167bc148 by task syz-executor099/2120 subflow_syn_recv_sock+0x451/0x4d0 net/mptcp/subflow.c:191 tcp_get_cookie_sock+0xcf/0x520 net/ipv4/syncookies.c:209 cookie_v6_check+0x15a5/0x1e90 net/ipv6/syncookies.c:252 tcp_v6_cookie_check net/ipv6/tcp_ipv6.c:1123 [inline] [..] Bug can be reproduced via "sysctl net.ipv4.tcp_syncookies=2". Note that MPTCP should work with syncookies (4th ack would carry needed state), but it appears better to sort that out in -next so do tcp fallback for now. I removed the MPTCP ifdef for tcp_rsk "is_mptcp" member because if (IS_ENABLED()) is easier to read than "#ifdef IS_ENABLED()/#endif" pair. Cc: Eric Dumazet Fixes: cec37a6e41aae7bf ("mptcp: Handle MP_CAPABLE options for outgoing connections") Reported-by: Christoph Paasch Tested-by: Christoph Paasch Signed-off-by: Florian Westphal Signed-off-by: David S. Miller

mptcp: avoid a lockdep splat when mcast group was joined

2020-01-29T16:45:20+00:00

syzbot triggered following lockdep splat: ffffffff82d2cd40 (rtnl_mutex){+.+.}, at: ip_mc_drop_socket+0x52/0x180 but task is already holding lock: ffff8881187a2310 (sk_lock-AF_INET){+.+.}, at: mptcp_close+0x18/0x30 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (sk_lock-AF_INET){+.+.}: lock_acquire+0xee/0x230 lock_sock_nested+0x89/0xc0 do_ip_setsockopt.isra.0+0x335/0x22f0 ip_setsockopt+0x35/0x60 tcp_setsockopt+0x5d/0x90 __sys_setsockopt+0xf3/0x190 __x64_sys_setsockopt+0x61/0x70 do_syscall_64+0x72/0x300 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #0 (rtnl_mutex){+.+.}: check_prevs_add+0x2b7/0x1210 __lock_acquire+0x10b6/0x1400 lock_acquire+0xee/0x230 __mutex_lock+0x120/0xc70 ip_mc_drop_socket+0x52/0x180 inet_release+0x36/0xe0 __sock_release+0xfd/0x130 __mptcp_close+0xa8/0x1f0 inet_release+0x7f/0xe0 __sock_release+0x69/0x130 sock_close+0x18/0x20 __fput+0x179/0x400 task_work_run+0xd5/0x110 do_exit+0x685/0x1510 do_group_exit+0x7e/0x170 __x64_sys_exit_group+0x28/0x30 do_syscall_64+0x72/0x300 entry_SYSCALL_64_after_hwframe+0x49/0xbe The trigger is: socket(AF_INET, SOCK_STREAM, 0x106 /* IPPROTO_MPTCP */) = 4 setsockopt(4, SOL_IP, MCAST_JOIN_GROUP, {gr_interface=7, gr_group={sa_family=AF_INET, sin_port=htons(20003), sin_addr=inet_addr("224.0.0.2")}}, 136) = 0 exit(0) Which results in a call to rtnl_lock while we are holding the parent mptcp socket lock via mptcp_close -> lock_sock(msk) -> inet_release -> ip_mc_drop_socket -> rtnl_lock(). >From lockdep point of view we thus have both 'rtnl_lock; lock_sock' and 'lock_sock; rtnl_lock'. Fix this by stealing the msk conn_list and doing the subflow close without holding the msk lock. Fixes: cec37a6e41aae7bf ("mptcp: Handle MP_CAPABLE options for outgoing connections") Reported-by: Christoph Paasch Signed-off-by: Florian Westphal Signed-off-by: David S. Miller

mptcp: fix panic on user pointer access

2020-01-29T16:45:19+00:00

Its not possible to call the kernel_(s|g)etsockopt functions here, the address points to user memory: General protection fault in user access. Non-canonical address? WARNING: CPU: 1 PID: 5352 at arch/x86/mm/extable.c:77 ex_handler_uaccess+0xba/0xe0 arch/x86/mm/extable.c:77 Kernel panic - not syncing: panic_on_warn set ... [..] Call Trace: fixup_exception+0x9d/0xcd arch/x86/mm/extable.c:178 general_protection+0x2d/0x40 arch/x86/entry/entry_64.S:1202 do_ip_getsockopt+0x1f6/0x1860 net/ipv4/ip_sockglue.c:1323 ip_getsockopt+0x87/0x1c0 net/ipv4/ip_sockglue.c:1561 tcp_getsockopt net/ipv4/tcp.c:3691 [inline] tcp_getsockopt+0x8c/0xd0 net/ipv4/tcp.c:3685 kernel_getsockopt+0x121/0x1f0 net/socket.c:3736 mptcp_getsockopt+0x69/0x90 net/mptcp/protocol.c:830 __sys_getsockopt+0x13a/0x220 net/socket.c:2175 We can call tcp_get/setsockopt functions instead. Doing so fixes crashing, but still leaves rtnl related lockdep splat: WARNING: possible circular locking dependency detected 5.5.0-rc6 #2 Not tainted ------------------------------------------------------ syz-executor.0/16334 is trying to acquire lock: ffffffff84f7a080 (rtnl_mutex){+.+.}, at: do_ip_setsockopt.isra.0+0x277/0x3820 net/ipv4/ip_sockglue.c:644 but task is already holding lock: ffff888116503b90 (sk_lock-AF_INET){+.+.}, at: lock_sock include/net/sock.h:1516 [inline] ffff888116503b90 (sk_lock-AF_INET){+.+.}, at: mptcp_setsockopt+0x28/0x90 net/mptcp/protocol.c:1284 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (sk_lock-AF_INET){+.+.}: lock_sock_nested+0xca/0x120 net/core/sock.c:2944 lock_sock include/net/sock.h:1516 [inline] do_ip_setsockopt.isra.0+0x281/0x3820 net/ipv4/ip_sockglue.c:645 ip_setsockopt+0x44/0xf0 net/ipv4/ip_sockglue.c:1248 udp_setsockopt+0x5d/0xa0 net/ipv4/udp.c:2639 __sys_setsockopt+0x152/0x240 net/socket.c:2130 __do_sys_setsockopt net/socket.c:2146 [inline] __se_sys_setsockopt net/socket.c:2143 [inline] __x64_sys_setsockopt+0xba/0x150 net/socket.c:2143 do_syscall_64+0xbd/0x5b0 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #0 (rtnl_mutex){+.+.}: check_prev_add kernel/locking/lockdep.c:2475 [inline] check_prevs_add kernel/locking/lockdep.c:2580 [inline] validate_chain kernel/locking/lockdep.c:2970 [inline] __lock_acquire+0x1fb2/0x4680 kernel/locking/lockdep.c:3954 lock_acquire+0x127/0x330 kernel/locking/lockdep.c:4484 __mutex_lock_common kernel/locking/mutex.c:956 [inline] __mutex_lock+0x158/0x1340 kernel/locking/mutex.c:1103 do_ip_setsockopt.isra.0+0x277/0x3820 net/ipv4/ip_sockglue.c:644 ip_setsockopt+0x44/0xf0 net/ipv4/ip_sockglue.c:1248 tcp_setsockopt net/ipv4/tcp.c:3159 [inline] tcp_setsockopt+0x8c/0xd0 net/ipv4/tcp.c:3153 kernel_setsockopt+0x121/0x1f0 net/socket.c:3767 mptcp_setsockopt+0x69/0x90 net/mptcp/protocol.c:1288 __sys_setsockopt+0x152/0x240 net/socket.c:2130 __do_sys_setsockopt net/socket.c:2146 [inline] __se_sys_setsockopt net/socket.c:2143 [inline] __x64_sys_setsockopt+0xba/0x150 net/socket.c:2143 do_syscall_64+0xbd/0x5b0 arch/x86/entry/common.c:294 entry_SYSCALL_64_after_hwframe+0x49/0xbe other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(sk_lock-AF_INET); lock(rtnl_mutex); lock(sk_lock-AF_INET); lock(rtnl_mutex); The lockdep complaint is because we hold mptcp socket lock when calling the sk_prot get/setsockopt handler, and those might need to acquire the rtnl mutex. Normally, order is: rtnl_lock(sk) -> lock_sock Whereas for mptcp the order is lock_sock(mptcp_sk) rtnl_lock -> lock_sock(subflow_sk) We can avoid this by releasing the mptcp socket lock early, but, as Paolo points out, we need to get/put the subflow socket refcount before doing so to avoid race with concurrent close(). Fixes: 717e79c867ca5 ("mptcp: Add setsockopt()/getsockopt() socket operations") Reported-by: Christoph Paasch Signed-off-by: Florian Westphal Signed-off-by: David S. Miller

mptcp: defer freeing of cached ext until last moment

2020-01-29T16:45:19+00:00

access to msk->cached_ext is only legal if the msk is locked or all concurrent accesses are impossible. Furthermore, once we start to tear down, we must make sure nothing else can step in and allocate a new cached ext. So place this code in the destroy callback where it belongs. Signed-off-by: Florian Westphal Signed-off-by: David S. Miller