treewide: Use fallthrough pseudo-keyword

Replace the existing /* fall through */ comments and its variants with
the new pseudo-keyword macro fallthrough[1]. Also, remove unnecessary
fall-through mar

treewide: Use fallthrough pseudo-keyword

Replace the existing /* fall through */ comments and its variants with
the new pseudo-keyword macro fallthrough[1]. Also, remove unnecessary
fall-through markings when it is the case.

[1] https://www.kernel.org/doc/html/v5.7/process/deprecated.html?highlight=fallthrough#implicit-switch-case-fall-through

Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>

show more ...

net: dccp: Convert to use the preferred fallthrough macro

Convert the uses of fallthrough comments to fallthrough macro.

Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Signed-off-by: David S. Mil

net: dccp: Convert to use the preferred fallthrough macro

Convert the uses of fallthrough comments to fallthrough macro.

Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

show more ...

net: dccp: kerneldoc fixes

Simple fixes which require no deep knowledge of the code.

Cc: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Mi

net: dccp: kerneldoc fixes

Simple fixes which require no deep knowledge of the code.

Cc: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

show more ...

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152

Based on 1 normalized pattern(s):

this program is free software you can redistribute it and or modify
it under the terms of th

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152

Based on 1 normalized pattern(s):

this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license as published by
the free software foundation either version 2 of the license or at
your option any later version

extracted by the scancode license scanner the SPDX license identifier

GPL-2.0-or-later

has been chosen to replace the boilerplate/reference in 3029 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190527070032.746973796@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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tcp: Refactor pingpong code

Instead of using pingpong as a single bit information, we refactor the
code to treat it as a counter. When interactive session is detected,
we set pingpong count to TCP_P

tcp: Refactor pingpong code

Instead of using pingpong as a single bit information, we refactor the
code to treat it as a counter. When interactive session is detected,
we set pingpong count to TCP_PINGPONG_THRESH. And when pingpong count
is >= TCP_PINGPONG_THRESH, we consider the session in pingpong mode.

This patch is a pure refactor and sets foundation for the next patch.
This patch itself does not change any pingpong logic.

Signed-off-by: Wei Wang <weiwan@google.com>
Signed-off-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

show more ...

tcp/dccp: fix lockdep issue when SYN is backlogged

In normal SYN processing, packets are handled without listener
lock and in RCU protected ingress path.

But syzkaller is known to be able to trick

tcp/dccp: fix lockdep issue when SYN is backlogged

In normal SYN processing, packets are handled without listener
lock and in RCU protected ingress path.

But syzkaller is known to be able to trick us and SYN
packets might be processed in process context, after being
queued into socket backlog.

In commit 06f877d613be ("tcp/dccp: fix other lockdep splats
accessing ireq_opt") I made a very stupid fix, that happened
to work mostly because of the regular path being RCU protected.

Really the thing protecting ireq->ireq_opt is RCU read lock,
and the pseudo request refcnt is not relevant.

This patch extends what I did in commit 449809a66c1d ("tcp/dccp:
block BH for SYN processing") by adding an extra rcu_read_{lock|unlock}
pair in the paths that might be taken when processing SYN from
socket backlog (thus possibly in process context)

Fixes: 06f877d613be ("tcp/dccp: fix other lockdep splats accessing ireq_opt")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: syzbot <syzkaller@googlegroups.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

show more ...

net: dccp: mark expected switch fall-throughs

In preparation to enabling -Wimplicit-fallthrough, mark switch cases
where we are expecting to fall through.

Notice that for options.c file, I placed t

net: dccp: mark expected switch fall-throughs

In preparation to enabling -Wimplicit-fallthrough, mark switch cases
where we are expecting to fall through.

Notice that for options.c file, I placed the "fall through" comment
on its own line, which is what GCC is expecting to find.

Signed-off-by: Gustavo A. R. Silva <garsilva@embeddedor.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

show more ...

dccp: make const array error_code static

Don't populate array error_code on the stack but make it static. Makes
the object code smaller by almost 250 bytes:

Before:
text data bss dec

dccp: make const array error_code static

Don't populate array error_code on the stack but make it static. Makes
the object code smaller by almost 250 bytes:

Before:
text data bss dec hex filename
10366 983 0 11349 2c55 net/dccp/input.o

After:
text data bss dec hex filename
10161 1039 0 11200 2bc0 net/dccp/input.o

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

show more ...

tcp/dccp: block BH for SYN processing

SYN processing really was meant to be handled from BH.

When I got rid of BH blocking while processing socket backlog
in commit 5413d1babe8f ("net: do not block

tcp/dccp: block BH for SYN processing

SYN processing really was meant to be handled from BH.

When I got rid of BH blocking while processing socket backlog
in commit 5413d1babe8f ("net: do not block BH while processing socket
backlog"), I forgot that a malicious user could transition to TCP_LISTEN
from a state that allowed (SYN) packets to be parked in the socket
backlog while socket is owned by the thread doing the listen() call.

Sure enough syzkaller found this and reported the bug ;)

=================================
[ INFO: inconsistent lock state ]
4.10.0+ #60 Not tainted
---------------------------------
inconsistent {IN-SOFTIRQ-W} -> {SOFTIRQ-ON-W} usage.
syz-executor0/5090 [HC0[0]:SC0[0]:HE1:SE1] takes:
(&(&hashinfo->ehash_locks[i])->rlock){+.?...}, at:
[<ffffffff83a6a370>] spin_lock include/linux/spinlock.h:299 [inline]
(&(&hashinfo->ehash_locks[i])->rlock){+.?...}, at:
[<ffffffff83a6a370>] inet_ehash_insert+0x240/0xad0
net/ipv4/inet_hashtables.c:407
{IN-SOFTIRQ-W} state was registered at:
mark_irqflags kernel/locking/lockdep.c:2923 [inline]
__lock_acquire+0xbcf/0x3270 kernel/locking/lockdep.c:3295
lock_acquire+0x241/0x580 kernel/locking/lockdep.c:3753
__raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
_raw_spin_lock+0x33/0x50 kernel/locking/spinlock.c:151
spin_lock include/linux/spinlock.h:299 [inline]
inet_ehash_insert+0x240/0xad0 net/ipv4/inet_hashtables.c:407
reqsk_queue_hash_req net/ipv4/inet_connection_sock.c:753 [inline]
inet_csk_reqsk_queue_hash_add+0x1b7/0x2a0 net/ipv4/inet_connection_sock.c:764
tcp_conn_request+0x25cc/0x3310 net/ipv4/tcp_input.c:6399
tcp_v4_conn_request+0x157/0x220 net/ipv4/tcp_ipv4.c:1262
tcp_rcv_state_process+0x802/0x4130 net/ipv4/tcp_input.c:5889
tcp_v4_do_rcv+0x56b/0x940 net/ipv4/tcp_ipv4.c:1433
tcp_v4_rcv+0x2e12/0x3210 net/ipv4/tcp_ipv4.c:1711
ip_local_deliver_finish+0x4ce/0xc40 net/ipv4/ip_input.c:216
NF_HOOK include/linux/netfilter.h:257 [inline]
ip_local_deliver+0x1ce/0x710 net/ipv4/ip_input.c:257
dst_input include/net/dst.h:492 [inline]
ip_rcv_finish+0xb1d/0x2110 net/ipv4/ip_input.c:396
NF_HOOK include/linux/netfilter.h:257 [inline]
ip_rcv+0xd90/0x19c0 net/ipv4/ip_input.c:487
__netif_receive_skb_core+0x1ad1/0x3400 net/core/dev.c:4179
__netif_receive_skb+0x2a/0x170 net/core/dev.c:4217
netif_receive_skb_internal+0x1d6/0x430 net/core/dev.c:4245
napi_skb_finish net/core/dev.c:4602 [inline]
napi_gro_receive+0x4e6/0x680 net/core/dev.c:4636
e1000_receive_skb drivers/net/ethernet/intel/e1000/e1000_main.c:4033 [inline]
e1000_clean_rx_irq+0x5e0/0x1490
drivers/net/ethernet/intel/e1000/e1000_main.c:4489
e1000_clean+0xb9a/0x2910 drivers/net/ethernet/intel/e1000/e1000_main.c:3834
napi_poll net/core/dev.c:5171 [inline]
net_rx_action+0xe70/0x1900 net/core/dev.c:5236
__do_softirq+0x2fb/0xb7d kernel/softirq.c:284
invoke_softirq kernel/softirq.c:364 [inline]
irq_exit+0x19e/0x1d0 kernel/softirq.c:405
exiting_irq arch/x86/include/asm/apic.h:658 [inline]
do_IRQ+0x81/0x1a0 arch/x86/kernel/irq.c:250
ret_from_intr+0x0/0x20
native_safe_halt+0x6/0x10 arch/x86/include/asm/irqflags.h:53
arch_safe_halt arch/x86/include/asm/paravirt.h:98 [inline]
default_idle+0x8f/0x410 arch/x86/kernel/process.c:271
arch_cpu_idle+0xa/0x10 arch/x86/kernel/process.c:262
default_idle_call+0x36/0x60 kernel/sched/idle.c:96
cpuidle_idle_call kernel/sched/idle.c:154 [inline]
do_idle+0x348/0x440 kernel/sched/idle.c:243
cpu_startup_entry+0x18/0x20 kernel/sched/idle.c:345
start_secondary+0x344/0x440 arch/x86/kernel/smpboot.c:272
verify_cpu+0x0/0xfc
irq event stamp: 1741
hardirqs last enabled at (1741): [<ffffffff84d49d77>]
__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:160
[inline]
hardirqs last enabled at (1741): [<ffffffff84d49d77>]
_raw_spin_unlock_irqrestore+0xf7/0x1a0 kernel/locking/spinlock.c:191
hardirqs last disabled at (1740): [<ffffffff84d4a732>]
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:108 [inline]
hardirqs last disabled at (1740): [<ffffffff84d4a732>]
_raw_spin_lock_irqsave+0xa2/0x110 kernel/locking/spinlock.c:159
softirqs last enabled at (1738): [<ffffffff84d4deff>]
__do_softirq+0x7cf/0xb7d kernel/softirq.c:310
softirqs last disabled at (1571): [<ffffffff84d4b92c>]
do_softirq_own_stack+0x1c/0x30 arch/x86/entry/entry_64.S:902

other info that might help us debug this:
Possible unsafe locking scenario:

CPU0
----
lock(&(&hashinfo->ehash_locks[i])->rlock);
<Interrupt>
lock(&(&hashinfo->ehash_locks[i])->rlock);

*** DEADLOCK ***

1 lock held by syz-executor0/5090:
#0: (sk_lock-AF_INET6){+.+.+.}, at: [<ffffffff83406b43>] lock_sock
include/net/sock.h:1460 [inline]
#0: (sk_lock-AF_INET6){+.+.+.}, at: [<ffffffff83406b43>]
sock_setsockopt+0x233/0x1e40 net/core/sock.c:683

stack backtrace:
CPU: 1 PID: 5090 Comm: syz-executor0 Not tainted 4.10.0+ #60
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:15 [inline]
dump_stack+0x292/0x398 lib/dump_stack.c:51
print_usage_bug+0x3ef/0x450 kernel/locking/lockdep.c:2387
valid_state kernel/locking/lockdep.c:2400 [inline]
mark_lock_irq kernel/locking/lockdep.c:2602 [inline]
mark_lock+0xf30/0x1410 kernel/locking/lockdep.c:3065
mark_irqflags kernel/locking/lockdep.c:2941 [inline]
__lock_acquire+0x6dc/0x3270 kernel/locking/lockdep.c:3295
lock_acquire+0x241/0x580 kernel/locking/lockdep.c:3753
__raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
_raw_spin_lock+0x33/0x50 kernel/locking/spinlock.c:151
spin_lock include/linux/spinlock.h:299 [inline]
inet_ehash_insert+0x240/0xad0 net/ipv4/inet_hashtables.c:407
reqsk_queue_hash_req net/ipv4/inet_connection_sock.c:753 [inline]
inet_csk_reqsk_queue_hash_add+0x1b7/0x2a0 net/ipv4/inet_connection_sock.c:764
dccp_v6_conn_request+0xada/0x11b0 net/dccp/ipv6.c:380
dccp_rcv_state_process+0x51e/0x1660 net/dccp/input.c:606
dccp_v6_do_rcv+0x213/0x350 net/dccp/ipv6.c:632
sk_backlog_rcv include/net/sock.h:896 [inline]
__release_sock+0x127/0x3a0 net/core/sock.c:2052
release_sock+0xa5/0x2b0 net/core/sock.c:2539
sock_setsockopt+0x60f/0x1e40 net/core/sock.c:1016
SYSC_setsockopt net/socket.c:1782 [inline]
SyS_setsockopt+0x2fb/0x3a0 net/socket.c:1765
entry_SYSCALL_64_fastpath+0x1f/0xc2
RIP: 0033:0x4458b9
RSP: 002b:00007fe8b26c2b58 EFLAGS: 00000292 ORIG_RAX: 0000000000000036
RAX: ffffffffffffffda RBX: 0000000000000006 RCX: 00000000004458b9
RDX: 000000000000001a RSI: 0000000000000001 RDI: 0000000000000006
RBP: 00000000006e2110 R08: 0000000000000010 R09: 0000000000000000
R10: 00000000208c3000 R11: 0000000000000292 R12: 0000000000708000
R13: 0000000020000000 R14: 0000000000001000 R15: 0000000000000000

Fixes: 5413d1babe8f ("net: do not block BH while processing socket backlog")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Andrey Konovalov <andreyknvl@google.com>
Acked-by: Soheil Hassas Yeganeh <soheil@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

show more ...

dccp: fix freeing skb too early for IPV6_RECVPKTINFO

In the current DCCP implementation an skb for a DCCP_PKT_REQUEST packet
is forcibly freed via __kfree_skb in dccp_rcv_state_process if
dccp_v6_co

dccp: fix freeing skb too early for IPV6_RECVPKTINFO

In the current DCCP implementation an skb for a DCCP_PKT_REQUEST packet
is forcibly freed via __kfree_skb in dccp_rcv_state_process if
dccp_v6_conn_request successfully returns.

However, if IPV6_RECVPKTINFO is set on a socket, the address of the skb
is saved to ireq->pktopts and the ref count for skb is incremented in
dccp_v6_conn_request, so skb is still in use. Nevertheless, it gets freed
in dccp_rcv_state_process.

Fix by calling consume_skb instead of doing goto discard and therefore
calling __kfree_skb.

Similar fixes for TCP:

fb7e2399ec17f1004c0e0ccfd17439f8759ede01 [TCP]: skb is unexpectedly freed.
0aea76d35c9651d55bbaf746e7914e5f9ae5a25d tcp: SYN packets are now
simply consumed

Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

show more ...

dccp: do not assume DCCP code is non preemptible

DCCP uses the generic backlog code, and this will soon
be changed to not disable BH when protocol is called back.

Signed-off-by: Eric Dumazet <eduma

dccp: do not assume DCCP code is non preemptible

DCCP uses the generic backlog code, and this will soon
be changed to not disable BH when protocol is called back.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Soheil Hassas Yeganeh <soheil@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

show more ...

dccp: rename DCCP_INC_STATS_BH()

Rename DCCP_INC_STATS_BH() to __DCCP_INC_STATS()

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

dccp: spelling s/reseting/resetting

Signed-off-by: Fabian Frederick <fabf@skynet.be>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: Fix use after free by removing length arg from sk_data_ready callbacks.

Several spots in the kernel perform a sequence like:

skb_queue_tail(&sk->s_receive_queue, skb);
sk->sk_data_ready(sk,

net: Fix use after free by removing length arg from sk_data_ready callbacks.

Several spots in the kernel perform a sequence like:

skb_queue_tail(&sk->s_receive_queue, skb);
sk->sk_data_ready(sk, skb->len);

But at the moment we place the SKB onto the socket receive queue it
can be consumed and freed up. So this skb->len access is potentially
to freed up memory.

Furthermore, the skb->len can be modified by the consumer so it is
possible that the value isn't accurate.

And finally, no actual implementation of this callback actually uses
the length argument. And since nobody actually cared about it's
value, lots of call sites pass arbitrary values in such as '0' and
even '1'.

So just remove the length argument from the callback, that way there
is no confusion whatsoever and all of these use-after-free cases get
fixed as a side effect.

Based upon a patch by Eric Dumazet and his suggestion to audit this
issue tree-wide.

Signed-off-by: David S. Miller <davem@davemloft.net>

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net: Fix (nearly-)kernel-doc comments for various functions

Fix incorrect start markers, wrapped summary lines, missing section
breaks, incorrect separators, and some name mismatches.

Signed-off-by

net: Fix (nearly-)kernel-doc comments for various functions

Fix incorrect start markers, wrapped summary lines, missing section
breaks, incorrect separators, and some name mismatches.

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

show more ...

net: cleanup unsigned to unsigned int

Use of "unsigned int" is preferred to bare "unsigned" in net tree.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@d

net: cleanup unsigned to unsigned int

Use of "unsigned int" is preferred to bare "unsigned" in net tree.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

show more ...

dccp: Clean up slow-path input processing

This patch rearranges the order of statements of the slow-path input processing
(i.e. any other state than OPEN), to resolve the following issues.

1. Depe

dccp: Clean up slow-path input processing

This patch rearranges the order of statements of the slow-path input processing
(i.e. any other state than OPEN), to resolve the following issues.

1. Dependencies: the order of statements now better matches RFC 4340, 8.5, i.e.
step 7 is before step 9 (previously 9 was before 7), and parsing options in
step 8 (which may consume resources) now comes after step 7.
2. Sequence number checks are omitted if in state LISTEN/REQUEST, due to the
note underneath the table in RFC 4340, 7.5.3.
As a result, CCID processing is now indeed confined to OPEN/PARTOPEN states,
i.e. congestion control is performed only on the flow of data packets. This
avoids pathological cases of doing congestion control on those messages
which set up and terminate the connection.
3. Packets are now passed on to Ack Vector / CCID processing only after
- step 7 (receive unexpected packets),
- step 9 (receive Reset),
- step 13 (receive CloseReq),
- step 14 (receive Close)
and only if the state is PARTOPEN. This simplifies CCID processing:
- in LISTEN/CLOSED the CCIDs are non-existent;
- in RESPOND/REQUEST the CCIDs have not yet been negotiated;
- in CLOSEREQ and active-CLOSING the node has already closed this socket;
- in passive-CLOSING the client is waiting for its Reset.
In the last case, RFC 4340, 8.3 leaves it open to ignore further incoming
data, which is the approach taken here.

Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>

show more ...

dccp: fix oops on Reset after close

This fixes a bug in the order of dccp_rcv_state_process() that still permitted
reception even after closing the socket. A Reset after close thus causes a NULL
poi

dccp: fix oops on Reset after close

This fixes a bug in the order of dccp_rcv_state_process() that still permitted
reception even after closing the socket. A Reset after close thus causes a NULL
pointer dereference by not preventing operations on an already torn-down socket.

dccp_v4_do_rcv()
|
| state other than OPEN
v
dccp_rcv_state_process()
|
| DCCP_PKT_RESET
v
dccp_rcv_reset()
|
v
dccp_time_wait()

WARNING: at net/ipv4/inet_timewait_sock.c:141 __inet_twsk_hashdance+0x48/0x128()
Modules linked in: arc4 ecb carl9170 rt2870sta(C) mac80211 r8712u(C) crc_ccitt ah
[<c0038850>] (unwind_backtrace+0x0/0xec) from [<c0055364>] (warn_slowpath_common)
[<c0055364>] (warn_slowpath_common+0x4c/0x64) from [<c0055398>] (warn_slowpath_n)
[<c0055398>] (warn_slowpath_null+0x1c/0x24) from [<c02b72d0>] (__inet_twsk_hashd)
[<c02b72d0>] (__inet_twsk_hashdance+0x48/0x128) from [<c031caa0>] (dccp_time_wai)
[<c031caa0>] (dccp_time_wait+0x40/0xc8) from [<c031c15c>] (dccp_rcv_state_proces)
[<c031c15c>] (dccp_rcv_state_process+0x120/0x538) from [<c032609c>] (dccp_v4_do_)
[<c032609c>] (dccp_v4_do_rcv+0x11c/0x14c) from [<c0286594>] (release_sock+0xac/0)
[<c0286594>] (release_sock+0xac/0x110) from [<c031fd34>] (dccp_close+0x28c/0x380)
[<c031fd34>] (dccp_close+0x28c/0x380) from [<c02d9a78>] (inet_release+0x64/0x70)

The fix is by testing the socket state first. Receiving a packet in Closed state
now also produces the required "No connection" Reset reply of RFC 4340, 8.3.1.

Reported-and-tested-by: Johan Hovold <jhovold@gmail.com>
Cc: stable@kernel.org
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>

show more ...

dccp: fix return value for sequence-invalid packets

Currently dccp_check_seqno returns 0 (indicating a valid packet) if the
acknowledgment number is out of bounds and the sync that RFC 4340 mandates

dccp: fix return value for sequence-invalid packets

Currently dccp_check_seqno returns 0 (indicating a valid packet) if the
acknowledgment number is out of bounds and the sync that RFC 4340 mandates at
this point is currently being rate-limited. This function should return -1,
indicating an invalid packet.

Signed-off-by: Samuel Jero <sj323707@ohio.edu>
Acked-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>

show more ...

dccp: fix error in updating the GAR

This fixes a bug in updating the Greatest Acknowledgment number Received (GAR):
the current implementation does not track the greatest received value -
lower valu

dccp: fix error in updating the GAR

This fixes a bug in updating the Greatest Acknowledgment number Received (GAR):
the current implementation does not track the greatest received value -
lower values in the range AWL..AWH (RFC 4340, 7.5.1) erase higher ones.

Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>

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dccp ccid-2: Consolidate Ack-Vector processing within main DCCP module

This aggregates Ack Vector processing (handling input and clearing old state)
into one function, for the following reasons and

dccp ccid-2: Consolidate Ack-Vector processing within main DCCP module

This aggregates Ack Vector processing (handling input and clearing old state)
into one function, for the following reasons and benefits:
* all Ack Vector-specific processing is now in one place;
* duplicated code is removed;
* ensuring sanity: from an Ack Vector point of view, it is better to clear the
old state first before entering new state;
* Ack Event handling happens mostly within the CCIDs, not the main DCCP module.

Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>

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dccp ccid-2: Algorithm to update buffer state

This provides a routine to consistently update the buffer state when the
peer acknowledges receipt of Ack Vectors; updating state in the list of Ack
Vec

dccp ccid-2: Algorithm to update buffer state

This provides a routine to consistently update the buffer state when the
peer acknowledges receipt of Ack Vectors; updating state in the list of Ack
Vectors as well as in the circular buffer.

While based on RFC 4340, several additional (and necessary) precautions were
added to protect the consistency of the buffer state. These additions are
essential, since analysis and experience showed that the basic algorithm was
insufficient for this task (which lead to problems that were hard to debug).

The algorithm now
* deals with HC-sender acknowledging to HC-receiver and vice versa,
* keeps track of the last unacknowledged but received seqno in tail_ackno,
* has special cases to reset the overflow condition when appropriate,
* is protected against receiving older information (would mess up buffer state).

Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>

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dccp ccid-2: Ack Vector interface clean-up

This patch brings the Ack Vector interface up to date. Its main purpose is
to lay the basis for the subsequent patches of this set, which will use the
new

dccp ccid-2: Ack Vector interface clean-up

This patch brings the Ack Vector interface up to date. Its main purpose is
to lay the basis for the subsequent patches of this set, which will use the
new data structure fields and routines.

There are no real algorithmic changes, rather an adaptation:

(1) Replaced the static Ack Vector size (2) with a #define so that it can
be adapted (with low loss / Ack Ratio, a value of 1 works, so 2 seems
to be sufficient for the moment) and added a solution so that computing
the ECN nonce will continue to work - even with larger Ack Vectors.

(2) Replaced the #defines for Ack Vector states with a complete enum.

(3) Replaced #defines to compute Ack Vector length and state with general
purpose routines (inlines), and updated code to use these.

(4) Added a `tail' field (conversion to circular buffer in subsequent patch).

(5) Updated the (outdated) documentation for Ack Vector struct.

(6) All sequence number containers now trimmed to 48 bits.

(7) Removal of unused bits:
* removed dccpav_ack_nonce from struct dccp_ackvec, since this is already
redundantly stored in the `dccpavr_ack_nonce' (of Ack Vector record);
* removed Elapsed Time for Ack Vectors (it was nowhere used);
* replaced semantics of dccpavr_sent_len with dccpavr_ack_runlen, since
the code needs to be able to remember the old run length;
* reduced the de-/allocation routines (redundant / duplicate tests).

Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>

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dccp: cosmetics - warning format

This omits the redundant "DCCP:" in warning messages, since DCCP_WARN() already
echoes the function name, avoiding messages like

kernel: [10988.766503] dccp_clo

dccp: cosmetics - warning format

This omits the redundant "DCCP:" in warning messages, since DCCP_WARN() already
echoes the function name, avoiding messages like

kernel: [10988.766503] dccp_close: DCCP: ABORT -- 209 bytes unread

Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>

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dccp: fix the adjustments to AWL and SWL

This fixes a problem and a potential loophole with regard to seqno/ackno
validity: currently the initial adjustments to AWL/SWL are only performed
once at th

dccp: fix the adjustments to AWL and SWL

This fixes a problem and a potential loophole with regard to seqno/ackno
validity: currently the initial adjustments to AWL/SWL are only performed
once at the begin of the connection, during the handshake.

Since the Sequence Window feature is always greater than Wmin=32 (7.5.2),
it is however necessary to perform these adjustments at least for the first
W/W' (variables as per 7.5.1) packets in the lifetime of a connection.

This requirement is complicated by the fact that W/W' can change at any time
during the lifetime of a connection.

Therefore it is better to perform that safety check each time SWL/AWL are
updated, as implemented by the patch.

A second problem solved by this patch is that the remote/local Sequence Window
feature values (which set the bounds for AWL/SWL/SWH) are undefined until the
feature negotiation has completed.

During the initial handshake we have more stringent sequence number protection;
the changes added by this patch effect that {A,S}W{L,H} are within the correct
bounds at the instant that feature negotiation completes (since the SeqWin
feature activation handlers call dccp_update_gsr/gss()).

Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>

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