linux.git/net/sctp/protocol.c, branch v4.13

net: Work around lockdep limitation in sockets that use sockets

2017-03-10T02:23:27+00:00

Lockdep issues a circular dependency warning when AFS issues an operation
through AF_RXRPC from a context in which the VFS/VM holds the mmap_sem.

The theory lockdep comes up with is as follows:

 (1) If the pagefault handler decides it needs to read pages from AFS, it
     calls AFS with mmap_sem held and AFS begins an AF_RXRPC call, but
     creating a call requires the socket lock:

	mmap_sem must be taken before sk_lock-AF_RXRPC

 (2) afs_open_socket() opens an AF_RXRPC socket and binds it.  rxrpc_bind()
     binds the underlying UDP socket whilst holding its socket lock.
     inet_bind() takes its own socket lock:

	sk_lock-AF_RXRPC must be taken before sk_lock-AF_INET

 (3) Reading from a TCP socket into a userspace buffer might cause a fault
     and thus cause the kernel to take the mmap_sem, but the TCP socket is
     locked whilst doing this:

	sk_lock-AF_INET must be taken before mmap_sem

However, lockdep's theory is wrong in this instance because it deals only
with lock classes and not individual locks.  The AF_INET lock in (2) isn't
really equivalent to the AF_INET lock in (3) as the former deals with a
socket entirely internal to the kernel that never sees userspace.  This is
a limitation in the design of lockdep.

Fix the general case by:

 (1) Double up all the locking keys used in sockets so that one set are
     used if the socket is created by userspace and the other set is used
     if the socket is created by the kernel.

 (2) Store the kern parameter passed to sk_alloc() in a variable in the
     sock struct (sk_kern_sock).  This informs sock_lock_init(),
     sock_init_data() and sk_clone_lock() as to the lock keys to be used.

     Note that the child created by sk_clone_lock() inherits the parent's
     kern setting.

 (3) Add a 'kern' parameter to ->accept() that is analogous to the one
     passed in to ->create() that distinguishes whether kernel_accept() or
     sys_accept4() was the caller and can be passed to sk_alloc().

     Note that a lot of accept functions merely dequeue an already
     allocated socket.  I haven't touched these as the new socket already
     exists before we get the parameter.

     Note also that there are a couple of places where I've made the accepted
     socket unconditionally kernel-based:

	irda_accept()
	rds_rcp_accept_one()
	tcp_accept_from_sock()

     because they follow a sock_create_kern() and accept off of that.

Whilst creating this, I noticed that lustre and ocfs don't create sockets
through sock_create_kern() and thus they aren't marked as for-kernel,
though they appear to be internal.  I wonder if these should do that so
that they use the new set of lock keys.

Signed-off-by: David Howells 
Signed-off-by: David S. Miller

sctp: set sin_port for addr param when checking duplicate address

2017-02-27T02:24:05+00:00

Commit b8607805dd15 ("sctp: not copying duplicate addrs to the assoc's
bind address list") tried to check for duplicate address before copying
to asoc's bind_addr list from global addr list.

But all the addrs' sin_ports in global addr list are 0 while the addrs'
sin_ports are bp->port in asoc's bind_addr list. It means even if it's
a duplicate address, af->cmp_addr will still return 0 as the their
sin_ports are different.

This patch is to fix it by setting the sin_port for addr param with
bp->port before comparing the addrs.

Fixes: b8607805dd15 ("sctp: not copying duplicate addrs to the assoc's bind address list")
Reported-by: Wei Chen 
Signed-off-by: Xin Long 
Signed-off-by: David S. Miller

sctp: add reconf_enable in asoc ep and netns

2017-01-18T19:55:10+00:00

This patch is to add reconf_enable field in all of asoc ep and netns
to indicate if they support stream reset.

When initializing, asoc reconf_enable get the default value from ep
reconf_enable which is from netns netns reconf_enable by default.

It is also to add reconf_capable in asoc peer part to know if peer
supports reconf_enable, the value is set if ext params have reconf
chunk support when processing init chunk, just as rfc6525 section
5.1.1 demands.

Signed-off-by: Xin Long 
Signed-off-by: David S. Miller

sctp: simplify addr copy

2016-12-28T19:06:31+00:00

Make it a bit easier to read.

Signed-off-by: Marcelo Ricardo Leitner 
Signed-off-by: David S. Miller

sctp: not copying duplicate addrs to the assoc's bind address list

2016-12-20T19:15:45+00:00

sctp.local_addr_list is a global address list that is supposed to include
all the local addresses. sctp updates this list according to NETDEV_UP/
NETDEV_DOWN notifications.

However, if multiple NICs have the same address, the global list would
have duplicate addresses. Even if for one NIC, promote secondaries in
__inet_del_ifa can also lead to accumulating duplicate addresses.

When sctp binds address 'ANY' and creates a connection, it copies all
the addresses from global list into asoc's bind addr list, which makes
sctp pack the duplicate addresses into INIT/INIT_ACK packets.

This patch is to filter the duplicate addresses when copying the addrs
from global list in sctp_copy_local_addr_list and unpacking addr_param
from cookie in sctp_raw_to_bind_addrs to asoc's bind addr list.

Note that we can't filter the duplicate addrs when global address list
gets updated, As NETDEV_DOWN event may remove an addr that still exists
in another NIC.

Signed-off-by: Xin Long 
Acked-by: Marcelo Ricardo Leitner 
Signed-off-by: David S. Miller

sctp: reduce indent level in sctp_copy_local_addr_list

2016-12-20T19:15:44+00:00

This patch is to reduce indent level by using continue when the addr
is not allowed, and also drop end_copy by using break.

Signed-off-by: Xin Long 
Acked-by: Marcelo Ricardo Leitner 
Signed-off-by: David S. Miller

sctp: use inet_recvmsg to support sctp RFS well

2016-07-25T17:56:28+00:00

Commit 486bdee0134c ("sctp: add support for RPS and RFS")
saves skb->hash into sk->sk_rxhash so that the inet_* can
record it to flow table.

But sctp uses sock_common_recvmsg as .recvmsg instead
of inet_recvmsg, sock_common_recvmsg doesn't invoke
sock_rps_record_flow to record the flow. It may cause
that the receiver has no chances to record the flow if
it doesn't send msg or poll the socket.

So this patch fixes it by using inet_recvmsg as .recvmsg
in sctp.

Fixes: 486bdee0134c ("sctp: add support for RPS and RFS")
Signed-off-by: Xin Long 
Acked-by: Marcelo Ricardo Leitner 
Signed-off-by: David S. Miller

sctp: allow GSO frags to access the chunk too

2016-07-14T01:10:14+00:00

SCTP will try to access original IP headers on sctp_recvmsg in order to
copy the addresses used. There are also other places that do similar access
to IP or even SCTP headers. But after 90017accff61 ("sctp: Add GSO
support") they aren't always there because they are only present in the
header skb.

SCTP handles the queueing of incoming data by cloning the incoming skb
and limiting to only the relevant payload. This clone has its cb updated
to something different and it's then queued on socket rx queue. Thus we
need to fix this in two moments.

For rx path, not related to socket queue yet, this patch uses a
partially copied sctp_input_cb to such GSO frags. This restores the
ability to access the headers for this part of the code.

Regarding the socket rx queue, it removes iif member from sctp_event and
also add a chunk pointer on it.

With these changes we're always able to reach the headers again.

The biggest change here is that now the sctp_chunk struct and the
original skb are only freed after the application consumed the buffer.
Note however that the original payload was already like this due to the
skb cloning.

For iif, SCTP's IPv4 code doesn't use it, so no change is necessary.
IPv6 now can fetch it directly from original's IPv6 CB as the original
skb is still accessible.

In the future we probably can simplify sctp_v*_skb_iif() stuff, as
sctp_v4_skb_iif() was called but it's return value not used, and now
it's not even called, but such cleanup is out of scope for this change.

Fixes: 90017accff61 ("sctp: Add GSO support")
Signed-off-by: Marcelo Ricardo Leitner 
Signed-off-by: David S. Miller

sctp: fix error return code in sctp_init()

2016-06-15T06:45:42+00:00

Fix to return a negative error code from the error handling
case instead of 0, as done elsewhere in this function.

Signed-off-by: Wei Yongjun 
Acked-by: Xin Long 
Acked-by: Neil Horman 
Signed-off-by: David S. Miller

sctp: Add GSO support

2016-06-03T23:37:21+00:00

SCTP has this pecualiarity that its packets cannot be just segmented to
(P)MTU. Its chunks must be contained in IP segments, padding respected.
So we can't just generate a big skb, set gso_size to the fragmentation
point and deliver it to IP layer.

This patch takes a different approach. SCTP will now build a skb as it
would be if it was received using GRO. That is, there will be a cover
skb with protocol headers and children ones containing the actual
segments, already segmented to a way that respects SCTP RFCs.

With that, we can tell skb_segment() to just split based on frag_list,
trusting its sizes are already in accordance.

This way SCTP can benefit from GSO and instead of passing several
packets through the stack, it can pass a single large packet.

v2:
- Added support for receiving GSO frames, as requested by Dave Miller.
- Clear skb->cb if packet is GSO (otherwise it's not used by SCTP)
- Added heuristics similar to what we have in TCP for not generating
  single GSO packets that fills cwnd.
v3:
- consider sctphdr size in skb_gso_transport_seglen()
- rebased due to 5c7cdf339af5 ("gso: Remove arbitrary checks for
  unsupported GSO")

Signed-off-by: Marcelo Ricardo Leitner 
Tested-by: Xin Long 
Signed-off-by: David S. Miller