linux.git/include/trace/events/rxrpc.h, branch v5.7

rxrpc: Trace discarded ACKs

2020-05-20T14:33:41+00:00

Add a tracepoint to track received ACKs that are discarded due to being
outside of the Tx window.

Signed-off-by: David Howells

rxrpc: Fix the excessive initial retransmission timeout

2020-05-11T15:42:28+00:00

rxrpc currently uses a fixed 4s retransmission timeout until the RTT is
sufficiently sampled. This can cause problems with some fileservers with
calls to the cache manager in the afs filesystem being dropped from the
fileserver because a packet goes missing and the retransmission timeout is
greater than the call expiry timeout.

Fix this by:

(1) Copying the RTT/RTO calculation code from Linux's TCP implementation
and altering it to fit rxrpc.

(2) Altering the various users of the RTT to make use of the new SRTT
value.

(3) Replacing the use of rxrpc_resend_timeout to use the calculated RTO
value instead (which is needed in jiffies), along with a backoff.

Notes:

(1) rxrpc provides RTT samples by matching the serial numbers on outgoing
DATA packets that have the RXRPC_REQUEST_ACK set and PING ACK packets
against the reference serial number in incoming REQUESTED ACK and
PING-RESPONSE ACK packets.

(2) Each packet that is transmitted on an rxrpc connection gets a new
per-connection serial number, even for retransmissions, so an ACK can
be cross-referenced to a specific trigger packet. This allows RTT
information to be drawn from retransmitted DATA packets also.

(3) rxrpc maintains the RTT/RTO state on the rxrpc_peer record rather than
on an rxrpc_call because many RPC calls won't live long enough to
generate more than one sample.

(4) The calculated SRTT value is in units of 8ths of a microsecond rather
than nanoseconds.

The (S)RTT and RTO values are displayed in /proc/net/rxrpc/peers.

Fixes: 17926a79320a ([AF_RXRPC]: Provide secure RxRPC sockets for use by userspace and kernel both"")
Signed-off-by: David Howells

rxrpc: Fix trace-after-put looking at the put call record

2019-10-07T10:05:05+00:00

rxrpc_put_call() calls trace_rxrpc_call() after it has done the decrement
of the refcount - which looks at the debug_id in the call record.  But
unless the refcount was reduced to zero, we no longer have the right to
look in the record and, indeed, it may be deleted by some other thread.

Fix this by getting the debug_id out before decrementing the refcount and
then passing that into the tracepoint.

Fixes: e34d4234b0b7 ("rxrpc: Trace rxrpc_call usage")
Signed-off-by: David Howells

rxrpc: Fix trace-after-put looking at the put connection record

2019-10-07T10:05:05+00:00

rxrpc_put_*conn() calls trace_rxrpc_conn() after they have done the
decrement of the refcount - which looks at the debug_id in the connection
record.  But unless the refcount was reduced to zero, we no longer have the
right to look in the record and, indeed, it may be deleted by some other
thread.

Fix this by getting the debug_id out before decrementing the refcount and
then passing that into the tracepoint.

Fixes: 363deeab6d0f ("rxrpc: Add connection tracepoint and client conn state tracepoint")
Signed-off-by: David Howells

rxrpc: Fix trace-after-put looking at the put peer record

2019-10-07T10:05:05+00:00

rxrpc_put_peer() calls trace_rxrpc_peer() after it has done the decrement
of the refcount - which looks at the debug_id in the peer record.  But
unless the refcount was reduced to zero, we no longer have the right to
look in the record and, indeed, it may be deleted by some other thread.

Fix this by getting the debug_id out before decrementing the refcount and
then passing that into the tracepoint.

This can cause the following symptoms:

    BUG: KASAN: use-after-free in __rxrpc_put_peer net/rxrpc/peer_object.c:411
    [inline]
    BUG: KASAN: use-after-free in rxrpc_put_peer+0x685/0x6a0
    net/rxrpc/peer_object.c:435
    Read of size 8 at addr ffff888097ec0058 by task syz-executor823/24216

Fixes: 1159d4b496f5 ("rxrpc: Add a tracepoint to track rxrpc_peer refcounting")
Reported-by: syzbot+b9be979c55f2bea8ed30@syzkaller.appspotmail.com
Signed-off-by: David Howells

rxrpc: Fix rxrpc_recvmsg tracepoint

2019-10-04T20:57:14+00:00

Fix the rxrpc_recvmsg tracepoint to handle being called with a NULL call
parameter.

Fixes: a25e21f0bcd2 ("rxrpc, afs: Use debug_ids rather than pointers in traces")
Signed-off-by: David Howells 
Signed-off-by: David S. Miller

rxrpc: Use skb_unshare() rather than skb_cow_data()

2019-08-27T09:13:46+00:00

The in-place decryption routines in AF_RXRPC's rxkad security module
currently call skb_cow_data() to make sure the data isn't shared and that
the skb can be written over.  This has a problem, however, as the softirq
handler may be still holding a ref or the Rx ring may be holding multiple
refs when skb_cow_data() is called in rxkad_verify_packet() - and so
skb_shared() returns true and __pskb_pull_tail() dislikes that.  If this
occurs, something like the following report will be generated.

	kernel BUG at net/core/skbuff.c:1463!
	...
	RIP: 0010:pskb_expand_head+0x253/0x2b0
	...
	Call Trace:
	 __pskb_pull_tail+0x49/0x460
	 skb_cow_data+0x6f/0x300
	 rxkad_verify_packet+0x18b/0xb10 [rxrpc]
	 rxrpc_recvmsg_data.isra.11+0x4a8/0xa10 [rxrpc]
	 rxrpc_kernel_recv_data+0x126/0x240 [rxrpc]
	 afs_extract_data+0x51/0x2d0 [kafs]
	 afs_deliver_fs_fetch_data+0x188/0x400 [kafs]
	 afs_deliver_to_call+0xac/0x430 [kafs]
	 afs_wait_for_call_to_complete+0x22f/0x3d0 [kafs]
	 afs_make_call+0x282/0x3f0 [kafs]
	 afs_fs_fetch_data+0x164/0x300 [kafs]
	 afs_fetch_data+0x54/0x130 [kafs]
	 afs_readpages+0x20d/0x340 [kafs]
	 read_pages+0x66/0x180
	 __do_page_cache_readahead+0x188/0x1a0
	 ondemand_readahead+0x17d/0x2e0
	 generic_file_read_iter+0x740/0xc10
	 __vfs_read+0x145/0x1a0
	 vfs_read+0x8c/0x140
	 ksys_read+0x4a/0xb0
	 do_syscall_64+0x43/0xf0
	 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Fix this by using skb_unshare() instead in the input path for DATA packets
that have a security index != 0.  Non-DATA packets don't need in-place
encryption and neither do unencrypted DATA packets.

Fixes: 248f219cb8bc ("rxrpc: Rewrite the data and ack handling code")
Reported-by: Julian Wollrath 
Signed-off-by: David Howells

rxrpc: Use the tx-phase skb flag to simplify tracing

2019-08-27T09:04:18+00:00

Use the previously-added transmit-phase skbuff private flag to simplify the
socket buffer tracing a bit.  Which phase the skbuff comes from can now be
divined from the skb rather than having to be guessed from the call state.

We can also reduce the number of rxrpc_skb_trace values by eliminating the
difference between Tx and Rx in the symbols.

Signed-off-by: David Howells

rxrpc: Fix read-after-free in rxrpc_queue_local()

2019-08-14T10:37:51+00:00

rxrpc_queue_local() attempts to queue the local endpoint it is given and
then, if successful, prints a trace line.  The trace line includes the
current usage count - but we're not allowed to look at the local endpoint
at this point as we passed our ref on it to the workqueue.

Fix this by reading the usage count before queuing the work item.

Also fix the reading of local->debug_id for trace lines, which must be done
with the same consideration as reading the usage count.

Fixes: 09d2bf595db4 ("rxrpc: Add a tracepoint to track rxrpc_local refcounting")
Reported-by: syzbot+78e71c5bab4f76a6a719@syzkaller.appspotmail.com
Signed-off-by: David Howells

rxrpc: Fix oops in tracepoint

2019-07-02T22:29:57+00:00

If the rxrpc_eproto tracepoint is enabled, an oops will be cause by the
trace line that rxrpc_extract_header() tries to emit when a protocol error
occurs (typically because the packet is short) because the call argument is
NULL.

Fix this by using ?: to assume 0 as the debug_id if call is NULL.

This can then be induced by:

	echo -e '\0\0\0\0\0\0\0\0' | ncat -4u --send-only  20001

where addr has the following program running on it:

	#include 
	#include 
	#include 
	#include 
	#include 
	#include 
	#include 
	int main(void)
	{
		struct sockaddr_rxrpc srx;
		int fd;
		memset(&srx, 0, sizeof(srx));
		srx.srx_family			= AF_RXRPC;
		srx.srx_service			= 0;
		srx.transport_type		= AF_INET;
		srx.transport_len		= sizeof(srx.transport.sin);
		srx.transport.sin.sin_family	= AF_INET;
		srx.transport.sin.sin_port	= htons(0x4e21);
		fd = socket(AF_RXRPC, SOCK_DGRAM, AF_INET6);
		bind(fd, (struct sockaddr *)&srx, sizeof(srx));
		sleep(20);
		return 0;
	}

It results in the following oops.

	BUG: kernel NULL pointer dereference, address: 0000000000000340
	#PF: supervisor read access in kernel mode
	#PF: error_code(0x0000) - not-present page
	...
	RIP: 0010:trace_event_raw_event_rxrpc_rx_eproto+0x47/0xac
	...
	Call Trace:
	 
	 rxrpc_extract_header+0x86/0x171
	 ? rcu_read_lock_sched_held+0x5d/0x63
	 ? rxrpc_new_skb+0xd4/0x109
	 rxrpc_input_packet+0xef/0x14fc
	 ? rxrpc_input_data+0x986/0x986
	 udp_queue_rcv_one_skb+0xbf/0x3d0
	 udp_unicast_rcv_skb.isra.8+0x64/0x71
	 ip_protocol_deliver_rcu+0xe4/0x1b4
	 ip_local_deliver+0xf0/0x154
	 __netif_receive_skb_one_core+0x50/0x6c
	 netif_receive_skb_internal+0x26b/0x2e9
	 napi_gro_receive+0xf8/0x1da
	 rtl8169_poll+0x303/0x4c4
	 net_rx_action+0x10e/0x333
	 __do_softirq+0x1a5/0x38f
	 irq_exit+0x54/0xc4
	 do_IRQ+0xda/0xf8
	 common_interrupt+0xf/0xf
	 
	 ...
	 ? cpuidle_enter_state+0x23c/0x34d
	 cpuidle_enter+0x2a/0x36
	 do_idle+0x163/0x1ea
	 cpu_startup_entry+0x1d/0x1f
	 start_secondary+0x157/0x172
	 secondary_startup_64+0xa4/0xb0

Fixes: a25e21f0bcd2 ("rxrpc, afs: Use debug_ids rather than pointers in traces")
Signed-off-by: David Howells 
Reviewed-by: Marc Dionne 
Signed-off-by: David S. Miller