kernel/net/rxrpc/recvmsg.c, branch linux-5.1.y

rxrpc: bad unlock balance in rxrpc_recvmsg

2019-02-06T18:54:07Z

When either "goto wait_interrupted;" or "goto wait_error;" paths are taken, socket lock has already been released. This patch fixes following syzbot splat : WARNING: bad unlock balance detected! 5.0.0-rc4+ #59 Not tainted ------------------------------------- syz-executor223/8256 is trying to release lock (sk_lock-AF_RXRPC) at: [] rxrpc_recvmsg+0x6d3/0x3099 net/rxrpc/recvmsg.c:598 but there are no more locks to release! other info that might help us debug this: 1 lock held by syz-executor223/8256: #0: 00000000fa9ed0f4 (slock-AF_RXRPC){+...}, at: spin_lock_bh include/linux/spinlock.h:334 [inline] #0: 00000000fa9ed0f4 (slock-AF_RXRPC){+...}, at: release_sock+0x20/0x1c0 net/core/sock.c:2798 stack backtrace: CPU: 1 PID: 8256 Comm: syz-executor223 Not tainted 5.0.0-rc4+ #59 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x172/0x1f0 lib/dump_stack.c:113 print_unlock_imbalance_bug kernel/locking/lockdep.c:3391 [inline] print_unlock_imbalance_bug.cold+0x114/0x123 kernel/locking/lockdep.c:3368 __lock_release kernel/locking/lockdep.c:3601 [inline] lock_release+0x67e/0xa00 kernel/locking/lockdep.c:3860 sock_release_ownership include/net/sock.h:1471 [inline] release_sock+0x183/0x1c0 net/core/sock.c:2808 rxrpc_recvmsg+0x6d3/0x3099 net/rxrpc/recvmsg.c:598 sock_recvmsg_nosec net/socket.c:794 [inline] sock_recvmsg net/socket.c:801 [inline] sock_recvmsg+0xd0/0x110 net/socket.c:797 __sys_recvfrom+0x1ff/0x350 net/socket.c:1845 __do_sys_recvfrom net/socket.c:1863 [inline] __se_sys_recvfrom net/socket.c:1859 [inline] __x64_sys_recvfrom+0xe1/0x1a0 net/socket.c:1859 do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x446379 Code: e8 2c b3 02 00 48 83 c4 18 c3 0f 1f 80 00 00 00 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 0f 83 2b 09 fc ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007fe5da89fd98 EFLAGS: 00000246 ORIG_RAX: 000000000000002d RAX: ffffffffffffffda RBX: 00000000006dbc28 RCX: 0000000000446379 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000003 RBP: 00000000006dbc20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006dbc2c R13: 0000000000000000 R14: 0000000000000000 R15: 20c49ba5e353f7cf Fixes: 248f219cb8bc ("rxrpc: Rewrite the data and ack handling code") Signed-off-by: Eric Dumazet Cc: David Howells Reported-by: syzbot Signed-off-by: David S. Miller

rxrpc: Allow the reply time to be obtained on a client call

2018-10-04T08:42:29Z

Allow the timestamp on the sk_buff holding the first DATA packet of a reply to be queried. This can then be used as a base for the expiry time calculation on the callback promise duration indicated by an operation result. Signed-off-by: David Howells

rxrpc: Push iov_iter up from rxrpc_kernel_recv_data() to caller

2018-08-03T19:46:20Z

Push iov_iter up from rxrpc_kernel_recv_data() to its caller to allow non-contiguous iovs to be passed down, thereby permitting file reading to be simplified in the AFS filesystem in a future patch. Signed-off-by: David Howells Signed-off-by: David S. Miller

rxrpc: Transmit more ACKs during data reception

2018-08-01T12:28:24Z

Immediately flush any outstanding ACK on entry to rxrpc_recvmsg_data() - which transfers data to the target buffers - if we previously had an Rx underrun (ie. we returned -EAGAIN because we ran out of received data). This lets the server know what we've managed to receive something. Also flush any outstanding ACK after calling the function if it hit -EAGAIN to let the server know we processed some data. It might be better to send more ACKs, possibly on a time-based scheme, but that needs some more consideration. With this and some additional AFS patches, it is possible to get large unencrypted O_DIRECT reads to be almost as fast as NFS over TCP. It looks like it might be theoretically possible to improve performance yet more for a server running a single operation as investigation of packet timestamps indicates that the server keeps stalling. The issue appears to be that rxrpc runs in to trouble with ACK packets getting batched together (up to ~32 at a time) somewhere between the IP transmit queue on the client and the ethernet receive queue on the server. However, this case isn't too much of a worry as even a lightly loaded server should be receiving sufficient packet flux to flush the ACK packets to the UDP socket. Signed-off-by: David Howells

rxrpc: Propose, but don't immediately transmit, the final ACK for a call

2018-08-01T12:28:24Z

The final ACK that closes out an rxrpc call needs to be transmitted by the client unless we're going to follow up with a DATA packet for a new call on the same channel (which implicitly ACK's the previous call, thereby saving an ACK). Currently, we don't do that, so if no follow on call is immediately forthcoming, the server will resend the last DATA packet - at which point rxrpc_conn_retransmit_call() will be triggered and will (re)send the final ACK. But the server has to hold on to the last packet until the ACK is received, thereby holding up its resources. Fix the client side to propose a delayed final ACK, to be transmitted after a short delay, assuming the call isn't superseded by a new one. Signed-off-by: David Howells

rxrpc: remove redundant initialization of variable 'len'

2018-03-16T13:48:39Z

The variable 'len' is being initialized with a value that is never read and it is re-assigned later, hence the initialization is redundant and can be removed. Cleans up clang warning: net/rxrpc/recvmsg.c:275:15: warning: Value stored to 'len' during its initialization is never read Signed-off-by: Colin Ian King Signed-off-by: David S. Miller

rxrpc: Work around usercopy check

2018-02-16T21:22:27Z

Due to a check recently added to copy_to_user(), it's now not permitted to copy from slab-held data to userspace unless the slab is whitelisted. This affects rxrpc_recvmsg() when it attempts to place an RXRPC_USER_CALL_ID control message in the userspace control message buffer. A warning is generated by usercopy_warn() because the source is the copy of the user_call_ID retained in the rxrpc_call struct. Work around the issue by copying the user_call_ID to a variable on the stack and passing that to put_cmsg(). The warning generated looks like: Bad or missing usercopy whitelist? Kernel memory exposure attempt detected from SLUB object 'dmaengine-unmap-128' (offset 680, size 8)! WARNING: CPU: 0 PID: 1401 at mm/usercopy.c:81 usercopy_warn+0x7e/0xa0 ... RIP: 0010:usercopy_warn+0x7e/0xa0 ... Call Trace: __check_object_size+0x9c/0x1a0 put_cmsg+0x98/0x120 rxrpc_recvmsg+0x6fc/0x1010 [rxrpc] ? finish_wait+0x80/0x80 ___sys_recvmsg+0xf8/0x240 ? __clear_rsb+0x25/0x3d ? __clear_rsb+0x15/0x3d ? __clear_rsb+0x25/0x3d ? __clear_rsb+0x15/0x3d ? __clear_rsb+0x25/0x3d ? __clear_rsb+0x15/0x3d ? __clear_rsb+0x25/0x3d ? __clear_rsb+0x15/0x3d ? finish_task_switch+0xa6/0x2b0 ? trace_hardirqs_on_caller+0xed/0x180 ? _raw_spin_unlock_irq+0x29/0x40 ? __sys_recvmsg+0x4e/0x90 __sys_recvmsg+0x4e/0x90 do_syscall_64+0x7a/0x220 entry_SYSCALL_64_after_hwframe+0x26/0x9b Reported-by: Jonathan Billings Signed-off-by: David Howells Acked-by: Kees Cook Tested-by: Jonathan Billings Signed-off-by: David S. Miller

rxrpc: Add a timeout for detecting lost ACKs/lost DATA

2017-11-24T10:18:42Z

Add an extra timeout that is set/updated when we send a DATA packet that has the request-ack flag set. This allows us to detect if we don't get an ACK in response to the latest flagged packet. The ACK packet is adjudged to have been lost if it doesn't turn up within 2*RTT of the transmission. If the timeout occurs, we schedule the sending of a PING ACK to find out the state of the other side. If a new DATA packet is ready to go sooner, we cancel the sending of the ping and set the request-ack flag on that instead. If we get back a PING-RESPONSE ACK that indicates a lower tx_top than what we had at the time of the ping transmission, we adjudge all the DATA packets sent between the response tx_top and the ping-time tx_top to have been lost and retransmit immediately. Rather than sending a PING ACK, we could just pick a DATA packet and speculatively retransmit that with request-ack set. It should result in either a REQUESTED ACK or a DUPLICATE ACK which we can then use in lieu the a PING-RESPONSE ACK mentioned above. Signed-off-by: David Howells

rxrpc: Don't transmit DELAY ACKs immediately on proposal

2017-11-24T10:18:41Z

Don't transmit a DELAY ACK immediately on proposal when the Rx window is rotated, but rather defer it to the work function. This means that we have a chance to queue/consume more received packets before we actually send the DELAY ACK, or even cancel it entirely, thereby reducing the number of packets transmitted. We do, however, want to continue sending other types of packet immediately, particularly REQUESTED ACKs, as they may be used for RTT calculation by the other side. Signed-off-by: David Howells

rxrpc: Fix call timeouts

2017-11-24T10:18:41Z

Fix the rxrpc call expiration timeouts and make them settable from userspace. By analogy with other rx implementations, there should be three timeouts: (1) "Normal timeout" This is set for all calls and is triggered if we haven't received any packets from the peer in a while. It is measured from the last time we received any packet on that call. This is not reset by any connection packets (such as CHALLENGE/RESPONSE packets). If a service operation takes a long time, the server should generate PING ACKs at a duration that's substantially less than the normal timeout so is to keep both sides alive. This is set at 1/6 of normal timeout. (2) "Idle timeout" This is set only for a service call and is triggered if we stop receiving the DATA packets that comprise the request data. It is measured from the last time we received a DATA packet. (3) "Hard timeout" This can be set for a call and specified the maximum lifetime of that call. It should not be specified by default. Some operations (such as volume transfer) take a long time. Allow userspace to set/change the timeouts on a call with sendmsg, using a control message: RXRPC_SET_CALL_TIMEOUTS The data to the message is a number of 32-bit words, not all of which need be given: u32 hard_timeout; /* sec from first packet */ u32 idle_timeout; /* msec from packet Rx */ u32 normal_timeout; /* msec from data Rx */ This can be set in combination with any other sendmsg() that affects a call. Signed-off-by: David Howells