Packets to devices without NETIF_F_SCTP_CSUM (including NETIF_F_NO_CSUM)
should be properly checksummed because the packets can be diverted or
rerouted after construction. This still leaves packets diverted from
NETIF_F_SCTP_CSUM-enabled devices with broken checksums. Fixing this
needs implementing software offload fallback in networking core.
For users of sctp_checksum_disable, skb->ip_summed should be left as
CHECKSUM_NONE and not CHECKSUM_UNNECESSARY as per include/linux/skbuff.h.
Signed-off-by: Michał Mirosław <mirq-linux@rere.qmqm.pl>
Signed-off-by: David S. Miller <davem@davemloft.net>
Trigger user ABORT if application closes a socket which has data
queued on the socket receive queue or chunks waiting on the
reassembly or ordering queue as this would imply data being lost
which defeats the point of a graceful shutdown.
This behavior is already practiced in TCP.
We do not check the input queue because that would mean to parse
all chunks on it to look for unacknowledged data which seems too
much of an effort. Control chunks or duplicated chunks may also
be in the input queue and should not be stopping a graceful
shutdown.
Signed-off-by: Thomas Graf <tgraf@infradead.org>
Acked-by: Vlad Yasevich <vladislav.yasevich@hp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
When initiating a graceful shutdown while having data chunks
on the retransmission queue with a peer which is in zero
window mode the shutdown is never completed because the
retransmission error count is reset periodically by the
following two rules:
- Do not timeout association while doing zero window probe.
- Reset overall error count when a heartbeat request has
been acknowledged.
The graceful shutdown will wait for all outstanding TSN to
be acknowledged before sending the SHUTDOWN request. This
never happens due to the peer's zero window not acknowledging
the continuously retransmitted data chunks. Although the
error counter is incremented for each failed retransmission,
the receiving of the SACK announcing the zero window clears
the error count again immediately. Also heartbeat requests
continue to be sent periodically. The peer acknowledges these
requests causing the error counter to be reset as well.
This patch changes behaviour to only reset the overall error
counter for the above rules while not in shutdown. After
reaching the maximum number of retransmission attempts, the
T5 shutdown guard timer is scheduled to give the receiver
some additional time to recover. The timer is stopped as soon
as the receiver acknowledges any data.
The issue can be easily reproduced by establishing a sctp
association over the loopback device, constantly queueing
data at the sender while not reading any at the receiver.
Wait for the window to reach zero, then initiate a shutdown
by killing both processes simultaneously. The association
will never be freed and the chunks on the retransmission
queue will be retransmitted indefinitely.
Signed-off-by: Thomas Graf <tgraf@infradead.org>
Acked-by: Vlad Yasevich <vladislav.yasevich@hp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
We forgot to send up SCTP_SENDER_DRY_EVENT notification when
user app subscribes to this event, and there is no data to be
sent or retransmit.
This is required by the Socket API and used by the DTLS/SCTP
implementation.
Reported-by: Michael Tüxen <Michael.Tuexen@lurchi.franken.de>
Signed-off-by: Wei Yongjun <yjwei@cn.fujitsu.com>
Tested-by: Robin Seggelmann <seggelmann@fh-muenster.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
Current tcp/udp/sctp global memory limits are not taking into account
hugepages allocations, and allow 50% of ram to be used by buffers of a
single protocol [ not counting space used by sockets / inodes ...]
Lets use nr_free_buffer_pages() and allow a default of 1/8 of kernel ram
per protocol, and a minimum of 128 pages.
Heavy duty machines sysadmins probably need to tweak limits anyway.
References: https://bugzilla.stlinux.com/show_bug.cgi?id=38032
Reported-by: starlight <starlight@binnacle.cx>
Suggested-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Make the case labels the same indent as the switch.
git diff -w shows useless break;s removed after returns
and a comment added to an unnecessary default: break;
because of a dubious gcc warning.
Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Unnecessary casts of void * clutter the code.
These are the remainder casts after several specific
patches to remove netdev_priv and dev_priv.
Done via coccinelle script:
$ cat cast_void_pointer.cocci
@@
type T;
T *pt;
void *pv;
@@
- pt = (T *)pv;
+ pt = pv;
Signed-off-by: Joe Perches <joe@perches.com>
Acked-by: Paul Moore <paul.moore@hp.com>
Signed-off-by: David S. Miller <davem@conan.davemloft.net>
Outside of net/sctp/ipv6.c, IPV6 specific code needs to
be ifdef guarded.
This fixes build failures with IPV6 disabled.
Reported-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
In this case, the SCTP association transmits an ASCONF packet
including addition of the new IP address and deletion of the old
address. This patch implements this functionality.
In this case, the ASCONF chunk is added to the beginning of the
queue, because the other chunks cannot be transmitted in this state.
Signed-off-by: Michio Honda <micchie@sfc.wide.ad.jp>
Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Acked-by: Wei Yongjun <yjwei@cn.fujitsu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch allows the application to operate Auto-ASCONF on/off
behavior via setsockopt() and getsockopt().
Signed-off-by: Michio Honda <micchie@sfc.wide.ad.jp>
Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Acked-by: Wei Yongjun <yjwei@cn.fujitsu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch allows the system administrator to change default
Auto-ASCONF on/off behavior via an sysctl value.
Signed-off-by: Michio Honda <micchie@sfc.wide.ad.jp>
Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Acked-by: Wei Yongjun <yjwei@cn.fujitsu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
SCTP reconfigure the IP addresses in the association by using
ASCONF chunks as mentioned in RFC5061. For example, we can
start to use the newly configured IP address in the existing
association. This patch implements automatic ASCONF operation
in the SCTP stack with address events in the host computer,
which is called auto_asconf.
Signed-off-by: Michio Honda <micchie@sfc.wide.ad.jp>
Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Acked-by: Wei Yongjun <yjwei@cn.fujitsu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch fixes the problem that the original code cannot delete
the remote address where the corresponding transport is currently
directed, even when the ASCONF is sent from the other address (this
situation happens when the single-homed sender transmits ASCONF
with ADD and DEL.)
Signed-off-by: Michio Honda <micchie@sfc.wide.ad.jp>
Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Acked-by: Wei Yongjun <yjwei@cn.fujitsu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
If the peer restart the asoc, we should not only fail any unsent/unacked
data, but also stop the T3-rtx, SACK, T4-rto timers, and teardown ASCONF
queues.
Signed-off-by: Wei Yongjun <yjwei@cn.fujitsu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
If an ASCONF chunk is outstanding, then the following ASCONF
chunk will be queued for later transmission. But when we free
the asoc, we forget to free the ASCONF queue at the same time,
this will cause memory leak.
Signed-off-by: Wei Yongjun <yjwei@cn.fujitsu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
The %pK format specifier is designed to hide exposed kernel pointers,
specifically via /proc interfaces. Exposing these pointers provides an
easy target for kernel write vulnerabilities, since they reveal the
locations of writable structures containing easily triggerable function
pointers. The behavior of %pK depends on the kptr_restrict sysctl.
If kptr_restrict is set to 0, no deviation from the standard %p behavior
occurs. If kptr_restrict is set to 1, the default, if the current user
(intended to be a reader via seq_printf(), etc.) does not have CAP_SYSLOG
(currently in the LSM tree), kernel pointers using %pK are printed as 0's.
If kptr_restrict is set to 2, kernel pointers using %pK are printed as
0's regardless of privileges. Replacing with 0's was chosen over the
default "(null)", which cannot be parsed by userland %p, which expects
"(nil)".
The supporting code for kptr_restrict and %pK are currently in the -mm
tree. This patch converts users of %p in net/ to %pK. Cases of printing
pointers to the syslog are not covered, since this would eliminate useful
information for postmortem debugging and the reading of the syslog is
already optionally protected by the dmesg_restrict sysctl.
Signed-off-by: Dan Rosenberg <drosenberg@vsecurity.com>
Cc: James Morris <jmorris@namei.org>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Thomas Graf <tgraf@infradead.org>
Cc: Eugene Teo <eugeneteo@kernel.org>
Cc: Kees Cook <kees.cook@canonical.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: David S. Miller <davem@davemloft.net>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Eric Paris <eparis@parisplace.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Commit c182f90bc1 ("SCTP: fix race
between sctp_bind_addr_free() and sctp_bind_addr_conflict()") and
commit 1231f0baa5 ("net,rcu: convert
call_rcu(sctp_local_addr_free) to kfree_rcu()"), happening in
different trees, introduced a build failure.
Simply make the SCTP race fix use kfree_rcu() too.
Signed-off-by: David S. Miller <davem@davemloft.net>
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next-2.6: (1446 commits)
macvlan: fix panic if lowerdev in a bond
tg3: Add braces around 5906 workaround.
tg3: Fix NETIF_F_LOOPBACK error
macvlan: remove one synchronize_rcu() call
networking: NET_CLS_ROUTE4 depends on INET
irda: Fix error propagation in ircomm_lmp_connect_response()
irda: Kill set but unused variable 'bytes' in irlan_check_command_param()
irda: Kill set but unused variable 'clen' in ircomm_connect_indication()
rxrpc: Fix set but unused variable 'usage' in rxrpc_get_transport()
be2net: Kill set but unused variable 'req' in lancer_fw_download()
irda: Kill set but unused vars 'saddr' and 'daddr' in irlan_provider_connect_indication()
atl1c: atl1c_resume() is only used when CONFIG_PM_SLEEP is defined.
rxrpc: Fix set but unused variable 'usage' in rxrpc_get_peer().
rxrpc: Kill set but unused variable 'local' in rxrpc_UDP_error_handler()
rxrpc: Kill set but unused variable 'sp' in rxrpc_process_connection()
rxrpc: Kill set but unused variable 'sp' in rxrpc_rotate_tx_window()
pkt_sched: Kill set but unused variable 'protocol' in tc_classify()
isdn: capi: Use pr_debug() instead of ifdefs.
tg3: Update version to 3.119
tg3: Apply rx_discards fix to 5719/5720
...
Fix up trivial conflicts in arch/x86/Kconfig and net/mac80211/agg-tx.c
as per Davem.
During the sctp_close() call, we do not use rcu primitives to
destroy the address list attached to the endpoint. At the same
time, we do the removal of addresses from this list before
attempting to remove the socket from the port hash
As a result, it is possible for another process to find the socket
in the port hash that is in the process of being closed. It then
proceeds to traverse the address list to find the conflict, only
to have that address list suddenly disappear without rcu() critical
section.
Fix issue by closing address list removal inside RCU critical
section.
Race can result in a kernel crash with general protection fault or
kernel NULL pointer dereference:
kernel: general protection fault: 0000 [#1] SMP
kernel: RIP: 0010:[<ffffffffa02f3dde>] [<ffffffffa02f3dde>] sctp_bind_addr_conflict+0x64/0x82 [sctp]
kernel: Call Trace:
kernel: [<ffffffffa02f415f>] ? sctp_get_port_local+0x17b/0x2a3 [sctp]
kernel: [<ffffffffa02f3d45>] ? sctp_bind_addr_match+0x33/0x68 [sctp]
kernel: [<ffffffffa02f4416>] ? sctp_do_bind+0xd3/0x141 [sctp]
kernel: [<ffffffffa02f5030>] ? sctp_bindx_add+0x4d/0x8e [sctp]
kernel: [<ffffffffa02f5183>] ? sctp_setsockopt_bindx+0x112/0x4a4 [sctp]
kernel: [<ffffffff81089e82>] ? generic_file_aio_write+0x7f/0x9b
kernel: [<ffffffffa02f763e>] ? sctp_setsockopt+0x14f/0xfee [sctp]
kernel: [<ffffffff810c11fb>] ? do_sync_write+0xab/0xeb
kernel: [<ffffffff810e82ab>] ? fsnotify+0x239/0x282
kernel: [<ffffffff810c2462>] ? alloc_file+0x18/0xb1
kernel: [<ffffffff8134a0b1>] ? compat_sys_setsockopt+0x1a5/0x1d9
kernel: [<ffffffff8134aaf1>] ? compat_sys_socketcall+0x143/0x1a4
kernel: [<ffffffff810467dc>] ? sysenter_dispatch+0x7/0x32
Signed-off-by: Jacek Luczak <luczak.jacek@gmail.com>
Acked-by: Vlad Yasevich <vladislav.yasevich@hp.com>
CC: Eric Dumazet <eric.dumazet@gmail.com>
Reviewed-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This variable only needs initialization when cmsgs.info
is NULL.
Use memset to ensure padding is also zeroed so
kernel doesn't leak any data.
Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
I messed things up when I converted over to the transport
flow, I passed the ipv4 address value instead of it's address.
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
This allows us to acquire the exact route keying information from the
protocol, however that might be managed.
It handles all of the possibilities, from the simplest case of storing
the key in inet->cork.fl to the more complex setup SCTP has where
individual transports determine the flow.
Signed-off-by: David S. Miller <davem@davemloft.net>
Several future simplifications are possible now because of this.
For example, the sctp_addr unions can simply refer directly to
the flowi information.
Signed-off-by: David S. Miller <davem@davemloft.net>
The rcu callback sctp_local_addr_free() just calls a kfree(),
so we use kfree_rcu() instead of the call_rcu(sctp_local_addr_free).
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Change the call to take the transport parameter and set the
cached 'dst' appropriately inside the get_dst() function calls.
This will allow us in the future to clean up source address
storage as well.
Signed-off-by: Vlad Yasevich <vladislav.yasevich@hp.com>
Signed-off-by: Wei Yongjun <yjwei@cn.fujitsu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
There is no point in passing a destination address to
a get_saddr() call.
Signed-off-by: Vlad Yasevich <vladislav.yasevich@hp.com>
Signed-off-by: Wei Yongjun <yjwei@cn.fujitsu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
SCTP never called xfrm_output after it's v6 route lookups so
that never really worked with ipsec. Additioanlly, we never
passed port nubmers and protocol in the flowi, so any port
based policies were never applied as well. Now that we can
fixed ipv6 routing lookup code, using ip6_dst_lookup_flow()
and pass port numbers.
Signed-off-by: Vlad Yasevich <vladislav.yasevich@hp.com>
Signed-off-by: Wei Yongjun <yjwei@cn.fujitsu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
The ipv6 routing lookup does give us a source address,
but instead of filling it into the dst, it's stored in
the flowi. We can use that instead of going through the
entire source address selection again.
Also the useless ->dst_saddr member of sctp_pf is removed.
And sctp_v6_dst_saddr() is removed, instead by introduce
sctp_v6_to_addr(), which can be reused to cleanup some dup
code.
Signed-off-by: Vlad Yasevich <vladislav.yasevich@hp.com>
Signed-off-by: Wei Yongjun <yjwei@cn.fujitsu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
In the below test case, using the source address routing,
sctp can not work.
Node-A
1)ifconfig eth0 inet6 add 2001:1::1/64
2)ip -6 rule add from 2001:1::1 table 100 pref 100
3)ip -6 route add 2001:2::1 dev eth0 table 100
4)sctp_darn -H 2001:1::1 -P 250 -l &
Node-B
1)ifconfig eth0 inet6 add 2001:2::1/64
2)ip -6 rule add from 2001:2::1 table 100 pref 100
3)ip -6 route add 2001:1::1 dev eth0 table 100
4)sctp_darn -H 2001:2::1 -P 250 -h 2001:1::1 -p 250 -s
root cause:
Node-A and Node-B use the source address routing, and
at begining, source address will be NULL,sctp will
search the routing table by the destination address,
because using the source address routing table, and
the result dst_entry will be NULL.
solution:
walk through the bind address list to get the source
address and then lookup the routing table again to get
the correct dst_entry.
Signed-off-by: Weixing Shi <Weixing.Shi@windriver.com>
Signed-off-by: Vlad Yasevich <vladislav.yasevich@hp.com>
Signed-off-by: Wei Yongjun <yjwei@cn.fujitsu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Add const qualifiers to structs iphdr, ipv6hdr and in6_addr pointers
where possible, to make code intention more obvious.
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch implement event notification SCTP_SENDER_DRY_EVENT.
SCTP Socket API Extensions:
6.1.9. SCTP_SENDER_DRY_EVENT
When the SCTP stack has no more user data to send or retransmit, this
notification is given to the user. Also, at the time when a user app
subscribes to this event, if there is no data to be sent or
retransmit, the stack will immediately send up this notification.
Signed-off-by: Wei Yongjun <yjwei@cn.fujitsu.com>
Signed-off-by: Vlad Yasevich <vladislav.yasevich@hp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch change the auth event type name to SCTP_AUTHENTICATION_EVENT,
which is based on API extension compliance.
Signed-off-by: Wei Yongjun <yjwei@cn.fujitsu.com>
Signed-off-by: Vlad Yasevich <vladislav.yasevich@hp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch Implement socket option SCTP_GET_ASSOC_ID_LIST.
SCTP Socket API Extension:
8.2.6. Get the Current Identifiers of Associations
(SCTP_GET_ASSOC_ID_LIST)
This option gets the current list of SCTP association identifiers of
the SCTP associations handled by a one-to-many style socket.
Signed-off-by: Wei Yongjun <yjwei@cn.fujitsu.com>
Signed-off-by: Vlad Yasevich <vladislav.yasevich@hp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
If there is still data waiting to retransmit and remain in
retransmit queue, while doing the next retransmit, if the
chunk is abandoned, we should move it to abandoned list.
Signed-off-by: Wei Yongjun <yjwei@cn.fujitsu.com>
Signed-off-by: Vlad Yasevich <vladislav.yasevich@hp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Make heartbeat information in sctp_make_heartbeat() instead
of make it in sctp_sf_heartbeat() directly for common using.
Signed-off-by: Wei Yongjun <yjwei@cn.fujitsu.com>
Signed-off-by: Vlad Yasevich <vladislav.yasevich@hp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
SCTP does not check whether the source address of COOKIE-ECHO
chunk is the original address of INIT chunk or part of the any
address parameters saved in COOKIE in CLOSED state. So even if
the COOKIE-ECHO chunk is from any address but with correct COOKIE,
the COOKIE-ECHO chunk still be accepted. If the COOKIE is not from
a valid address, the assoc should not be established.
Signed-off-by: Wei Yongjun <yjwei@cn.fujitsu.com>
Signed-off-by: Vlad Yasevich <vladislav.yasevich@hp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Changed the order of processing SHUTDOWN ACK and COOKIE ACK
refer to section 8.4:Handle "Out of the Blue" Packets.
SHUTDOWN ACK chunk should be processed before processing
"Stale Cookie" ERROR or a COOKIE ACK.
Signed-off-by: Wei Yongjun <yjwei@cn.fujitsu.com>
Signed-off-by: Shan Wei <shanwei@cn.fujitsu.com>
Signed-off-by: Vlad Yasevich <vladislav.yasevich@hp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
The sctp_endpoint_lookup_assoc() function uses a port hash
to lookup the association and then checks to see if any of
them are on the current endpoint. However, if the current
endpoint is not bound, there can't be any associations on
it, thus we can bail early.
Signed-off-by: Vlad Yasevich <vladislav.yasevich@hp.com>
Signed-off-by: Wei Yongjun <yjwei@cn.fujitsu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
SCTP does not SCTP_STATE_EMPTY and we can never be in
that state. Remove useless code.
Signed-off-by: Vlad Yasevich <vladislav.yasevich@hp.com>
Signed-off-by: Wei Yongjun <yjwei@cn.fujitsu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
RFC4960, section 3.3.7 said:
If an endpoint receives an ABORT with a format error or no TCB is
found, it MUST silently discard it.
When an endpoint receives ABORT that parameter value is invalid,
drop it.
Signed-off-by: Shan Wei <shanwei@cn.fujitsu.com>
Signed-off-by: Vlad Yasevich <vladislav.yasevich@hp.com>
Signed-off-by: Wei Yongjun <yjwei@cn.fujitsu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
When an endpoint receives ERROR that parameter value is invalid,
send an ABORT to peer with a Protocol Violation error code.
Signed-off-by: Shan Wei <shanwei@cn.fujitsu.com>
Signed-off-by: Vlad Yasevich <vladislav.yasevich@hp.com>
Signed-off-by: Wei Yongjun <yjwei@cn.fujitsu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
When processing an ACK for ADD_IP parameter, we only release
the routes on non-active transports. This can cause a wrong
source address to be used. We can release the routes and
cause new route lookups and source address selection so that
new addresses can be used as source. Additionally, we don't need
to lookup routes for all transports at the same time. We can let
the transmit code path update the cached route when the transport
actually sends something.
Signed-off-by: Vlad Yasevich <vladislav.yasevich@hp.com>
Signed-off-by: Wei Yongjun <yjwei@cn.fujitsu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
David S. Miller
Michał Mirosław
Thomas Graf
Wei Yongjun
Eric Dumazet
Joe Perches
Michio Honda
Dan Rosenberg
Linus Torvalds
Jacek Luczak
Lai Jiangshan
Vlad Yasevich
Weixing Shi
Lucas De Marchi
Shan Wei