linux-toradex.git/net/dccp/ipv4.c, branch v4.4.31

tcp/dccp: remove obsolete WARN_ON() in icmp handlers

2016-04-20T06:42:04+00:00

[ Upstream commit e316ea62e3203d524ff0239a40c56d3a39ad1b5c ]

Now SYN_RECV request sockets are installed in ehash table, an ICMP
handler can find a request socket while another cpu handles an incoming
packet transforming this SYN_RECV request socket into an ESTABLISHED
socket.

We need to remove the now obsolete WARN_ON(req->sk), since req->sk
is set when a new child is created and added into listener accept queue.

If this race happens, the ICMP will do nothing special.

Fixes: 079096f103fa ("tcp/dccp: install syn_recv requests into ehash table")
Signed-off-by: Eric Dumazet 
Reported-by: Ben Lazarus 
Reported-by: Neal Cardwell 
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman

tcp/dccp: fix another race at listener dismantle

2016-03-03T23:07:07+00:00

[ Upstream commit 7716682cc58e305e22207d5bb315f26af6b1e243 ]

Ilya reported following lockdep splat:

kernel: =========================
kernel: [ BUG: held lock freed! ]
kernel: 4.5.0-rc1-ceph-00026-g5e0a311 #1 Not tainted
kernel: -------------------------
kernel: swapper/5/0 is freeing memory
ffff880035c9d200-ffff880035c9dbff, with a lock still held there!
kernel: (&(&queue->rskq_lock)->rlock){+.-...}, at:
[] inet_csk_reqsk_queue_add+0x28/0xa0
kernel: 4 locks held by swapper/5/0:
kernel: #0:  (rcu_read_lock){......}, at: []
netif_receive_skb_internal+0x4b/0x1f0
kernel: #1:  (rcu_read_lock){......}, at: []
ip_local_deliver_finish+0x3f/0x380
kernel: #2:  (slock-AF_INET){+.-...}, at: []
sk_clone_lock+0x19b/0x440
kernel: #3:  (&(&queue->rskq_lock)->rlock){+.-...}, at:
[] inet_csk_reqsk_queue_add+0x28/0xa0

To properly fix this issue, inet_csk_reqsk_queue_add() needs
to return to its callers if the child as been queued
into accept queue.

We also need to make sure listener is still there before
calling sk->sk_data_ready(), by holding a reference on it,
since the reference carried by the child can disappear as
soon as the child is put on accept queue.

Reported-by: Ilya Dryomov 
Fixes: ebb516af60e1 ("tcp/dccp: fix race at listener dismantle phase")
Signed-off-by: Eric Dumazet 
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman

tcp/dccp: fix hashdance race for passive sessions

2015-10-23T12:42:21+00:00

Multiple cpus can process duplicates of incoming ACK messages
matching a SYN_RECV request socket. This is a rare event under
normal operations, but definitely can happen.

Only one must win the race, otherwise corruption would occur.

To fix this without adding new atomic ops, we use logic in
inet_ehash_nolisten() to detect the request was present in the same
ehash bucket where we try to insert the new child.

If request socket was not found, we have to undo the child creation.

This actually removes a spin_lock()/spin_unlock() pair in
reqsk_queue_unlink() for the fast path.

Fixes: e994b2f0fb92 ("tcp: do not lock listener to process SYN packets")
Fixes: 079096f103fa ("tcp/dccp: install syn_recv requests into ehash table")
Signed-off-by: Eric Dumazet 
Signed-off-by: David S. Miller

tcp/dccp: add inet_csk_reqsk_queue_drop_and_put() helper

2015-10-16T07:52:18+00:00

Let's reduce the confusion about inet_csk_reqsk_queue_drop() :
In many cases we also need to release reference on request socket,
so add a helper to do this, reducing code size and complexity.

Fixes: 4bdc3d66147b ("tcp/dccp: fix behavior of stale SYN_RECV request sockets")
Signed-off-by: Eric Dumazet 
Signed-off-by: David S. Miller

Revert "inet: fix double request socket freeing"

2015-10-16T07:52:17+00:00

This reverts commit c69736696cf3742b37d850289dc0d7ead177bb14.

At the time of above commit, tcp_req_err() and dccp_req_err()
were dead code, as SYN_RECV request sockets were not yet in ehash table.

Real bug was fixed later in a different commit.

We need to revert to not leak a refcount on request socket.

inet_csk_reqsk_queue_drop_and_put() will be added
in following commit to make clean inet_csk_reqsk_queue_drop()
does not release the reference owned by caller.

Signed-off-by: Eric Dumazet 
Signed-off-by: David S. Miller

tcp/dccp: fix behavior of stale SYN_RECV request sockets

2015-10-14T01:26:34+00:00

When a TCP/DCCP listener is closed, its pending SYN_RECV request sockets
become stale, meaning 3WHS can not complete.

But current behavior is wrong :
incoming packets finding such stale sockets are dropped.

We need instead to cleanup the request socket and perform another
lookup :
- Incoming ACK will give a RST answer,
- SYN rtx might find another listener if available.
- We expedite cleanup of request sockets and old listener socket.

Fixes: 079096f103fa ("tcp/dccp: install syn_recv requests into ehash table")
Signed-off-by: Eric Dumazet 
Signed-off-by: David S. Miller

tcp: avoid two atomic ops for syncookies

2015-10-05T09:45:27+00:00

inet_reqsk_alloc() is used to allocate a temporary request
in order to generate a SYNACK with a cookie. Then later,
syncookie validation also uses a temporary request.

These paths already took a reference on listener refcount,
we can avoid a couple of atomic operations.

Signed-off-by: Eric Dumazet 
Signed-off-by: David S. Miller

tcp/dccp: install syn_recv requests into ehash table

2015-10-03T11:32:41+00:00

In this patch, we insert request sockets into TCP/DCCP
regular ehash table (where ESTABLISHED and TIMEWAIT sockets
are) instead of using the per listener hash table.

ACK packets find SYN_RECV pseudo sockets without having
to find and lock the listener.

In nominal conditions, this halves pressure on listener lock.

Note that this will allow for SO_REUSEPORT refinements,
so that we can select a listener using cpu/numa affinities instead
of the prior 'consistent hash', since only SYN packets will
apply this selection logic.

We will shrink listen_sock in the following patch to ease
code review.

Signed-off-by: Eric Dumazet 
Cc: Ying Cai 
Cc: Willem de Bruijn 
Signed-off-by: David S. Miller

tcp/dccp: constify syn_recv_sock() method sock argument

2015-09-29T23:53:09+00:00

We'll soon no longer hold listener socket lock, these
functions do not modify the socket in any way.

Signed-off-by: Eric Dumazet 
Signed-off-by: David S. Miller

tcp/dccp: constify send_synack and send_reset socket argument

2015-09-29T23:53:07+00:00

None of these functions need to change the socket, make it
const.

Signed-off-by: Eric Dumazet 
Signed-off-by: David S. Miller