tcpm_key is an array inside struct tcp_md5sig, there is no need to check it
against NULL.
Signed-off-by: Dmitry Popov <ixaphire@qrator.net>
Acked-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Use kmem_cache to allocate/free inet_frag_queue objects since they're
all the same size per inet_frags user and are alloced/freed in high volumes
thus making it a perfect case for kmem_cache.
Signed-off-by: Nikolay Aleksandrov <nikolay@redhat.com>
Acked-by: Florian Westphal <fw@strlen.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
Now that we have INET_FRAG_EVICTED we might as well use it to stop
sending icmp messages in the "frag_expire" functions instead of
stripping INET_FRAG_FIRST_IN from their flags when evicting.
Also fix the comment style in ip6_expire_frag_queue().
Signed-off-by: Nikolay Aleksandrov <nikolay@redhat.com>
Reviewed-by: Florian Westphal <fw@strlen.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
Fix a couple of functions' declaration alignments.
Signed-off-by: Nikolay Aleksandrov <nikolay@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
The last_in field has been used to store various flags different from
first/last frag in so give it a more descriptive name: flags.
Signed-off-by: Nikolay Aleksandrov <nikolay@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
ip_local_deliver_finish() already have a rcu_read_lock/unlock, so
the rcu_read_lock/unlock is unnecessary.
See the stack below:
ip_local_deliver_finish
|
|
->icmp_rcv
|
|
->icmp_socket_deliver
Suggested-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: Duan Jiong <duanj.fnst@cn.fujitsu.com>
Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
When dealing with ICMPv[46] Error Message, function icmp_socket_deliver()
and icmpv6_notify() do some valid checks on packet's length, but then some
protocols check packet's length redaudantly. So remove those duplicated
statements, and increase counter ICMP_MIB_INERRORS/ICMP6_MIB_INERRORS in
function icmp_socket_deliver() and icmpv6_notify() respectively.
In addition, add missed counter in udp6/udplite6 when socket is NULL.
Signed-off-by: Duan Jiong <duanj.fnst@cn.fujitsu.com>
Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Pablo Neira Ayuso says:
====================
Netfilter updates for net-next
The following patchset contains netfilter updates for net-next, they are:
1) Add the reject expression for the nf_tables bridge family, this
allows us to send explicit reject (TCP RST / ICMP dest unrech) to
the packets matching a rule.
2) Simplify and consolidate the nf_tables set dumping logic. This uses
netlink control->data to filter out depending on the request.
3) Perform garbage collection in xt_hashlimit using a workqueue instead
of a timer, which is problematic when many entries are in place in
the tables, from Eric Dumazet.
4) Remove leftover code from the removed ulog target support, from
Paul Bolle.
5) Dump unmodified flags in the netfilter packet accounting when resetting
counters, so userspace knows that a counter was in overquota situation,
from Alexey Perevalov.
6) Fix wrong usage of the bitwise functions in nfnetlink_acct, also from
Alexey.
7) Fix a crash when adding new set element with an empty NFTA_SET_ELEM_LIST
attribute.
This patchset also includes a couple of cleanups for xt_LED from
Duan Jiong and for nf_conntrack_ipv4 (using coccinelle) from
Himangi Saraogi.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>
commit d23ff7016 (tcp: add generic netlink support for tcp_metrics) introduced
netlink support for the new tcp_metrics, however it restricted getting of
tcp_metrics to root user only. This is a change from how these values could
have been fetched when in the old route cache. Unless there's a legitimate
reason to restrict the reading of these values it would be better if normal
users could fetch them.
Cc: Julian Anastasov <ja@ssi.bg>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Debabrata Banerjee <dbanerje@akamai.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Steffen Klassert says:
====================
pull request (net-next): ipsec-next 2014-07-30
This is the last pull request for ipsec-next before I'll be
off for two weeks starting on friday. David, can you please
take urgent ipsec patches directly into net/net-next during
this time?
1) Error handling simplifications for vti and vti6.
From Mathias Krause.
2) Remove a duplicate semicolon after a return statement.
From Christoph Paasch.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>
Sparse warns because of implicit pointer cast.
v2: subject line correction, space between "void" and "*"
Signed-off-by: Karoly Kemeny <karoly.kemeny@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch introduces the use of the macro IS_ERR_OR_NULL in place of
tests for NULL and IS_ERR.
The following Coccinelle semantic patch was used for making the change:
@@
expression e;
@@
- e == NULL || IS_ERR(e)
+ IS_ERR_OR_NULL(e)
|| ...
Signed-off-by: Himangi Saraogi <himangi774@gmail.com>
Acked-by: Julia Lawall <julia.lawall@lip6.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch introduces the use of the macro IS_ERR_OR_NULL in place of
tests for NULL and IS_ERR.
The following Coccinelle semantic patch was used for making the change:
@@
expression e;
@@
- e == NULL || IS_ERR(e)
+ IS_ERR_OR_NULL(e)
|| ...
Signed-off-by: Himangi Saraogi <himangi774@gmail.com>
Acked-by: Julia Lawall <julia.lawall@lip6.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>
We create a proc dir for each network device, this will cause
conflicts when the devices have name "all" or "default".
Rather than emitting an ugly kernel warning, we could just
fail earlier by checking the device name.
Reported-by: Stephane Chazelas <stephane.chazelas@gmail.com>
Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
In "Counting Packets Sent Between Arbitrary Internet Hosts", Jeffrey and
Jedidiah describe ways exploiting linux IP identifier generation to
infer whether two machines are exchanging packets.
With commit 73f156a6e8 ("inetpeer: get rid of ip_id_count"), we
changed IP id generation, but this does not really prevent this
side-channel technique.
This patch adds a random amount of perturbation so that IP identifiers
for a given destination [1] are no longer monotonically increasing after
an idle period.
Note that prandom_u32_max(1) returns 0, so if generator is used at most
once per jiffy, this patch inserts no hole in the ID suite and do not
increase collision probability.
This is jiffies based, so in the worst case (HZ=1000), the id can
rollover after ~65 seconds of idle time, which should be fine.
We also change the hash used in __ip_select_ident() to not only hash
on daddr, but also saddr and protocol, so that ICMP probes can not be
used to infer information for other protocols.
For IPv6, adds saddr into the hash as well, but not nexthdr.
If I ping the patched target, we can see ID are now hard to predict.
21:57:11.008086 IP (...)
A > target: ICMP echo request, seq 1, length 64
21:57:11.010752 IP (... id 2081 ...)
target > A: ICMP echo reply, seq 1, length 64
21:57:12.013133 IP (...)
A > target: ICMP echo request, seq 2, length 64
21:57:12.015737 IP (... id 3039 ...)
target > A: ICMP echo reply, seq 2, length 64
21:57:13.016580 IP (...)
A > target: ICMP echo request, seq 3, length 64
21:57:13.019251 IP (... id 3437 ...)
target > A: ICMP echo reply, seq 3, length 64
[1] TCP sessions uses a per flow ID generator not changed by this patch.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Jeffrey Knockel <jeffk@cs.unm.edu>
Reported-by: Jedidiah R. Crandall <crandall@cs.unm.edu>
Cc: Willy Tarreau <w@1wt.eu>
Cc: Hannes Frederic Sowa <hannes@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch makes init_net's high_thresh limit to be the maximum for all
namespaces, thus introducing a global memory limit threshold equal to the
sum of the individual high_thresh limits which are capped.
It also introduces some sane minimums for low_thresh as it shouldn't be
able to drop below 0 (or > high_thresh in the unsigned case), and
overall low_thresh should not ever be above high_thresh, so we make the
following relations for a namespace:
init_net:
high_thresh - max(not capped), min(init_net low_thresh)
low_thresh - max(init_net high_thresh), min (0)
all other namespaces:
high_thresh = max(init_net high_thresh), min(namespace's low_thresh)
low_thresh = max(namespace's high_thresh), min(0)
The major issue with having low_thresh > high_thresh is that we'll
schedule eviction but never evict anything and thus rely only on the
timers.
Signed-off-by: Nikolay Aleksandrov <nikolay@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
rehash is rare operation, don't force readers to take
the read-side rwlock.
Instead, we only have to detect the (rare) case where
the secret was altered while we are trying to insert
a new inetfrag queue into the table.
If it was changed, drop the bucket lock and recompute
the hash to get the 'new' chain bucket that we have to
insert into.
Joint work with Nikolay Aleksandrov.
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Nikolay Aleksandrov <nikolay@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
merge functionality into the eviction workqueue.
Instead of rebuilding every n seconds, take advantage of the upper
hash chain length limit.
If we hit it, mark table for rebuild and schedule workqueue.
To prevent frequent rebuilds when we're completely overloaded,
don't rebuild more than once every 5 seconds.
ipfrag_secret_interval sysctl is now obsolete and has been marked as
deprecated, it still can be changed so scripts won't be broken but it
won't have any effect. A comment is left above each unused secret_timer
variable to avoid confusion.
Joint work with Nikolay Aleksandrov.
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Nikolay Aleksandrov <nikolay@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
The 'nqueues' counter is protected by the lru list lock,
once thats removed this needs to be converted to atomic
counter. Given this isn't used for anything except for
reporting it to userspace via /proc, just remove it.
We still report the memory currently used by fragment
reassembly queues.
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
When the high_thresh limit is reached we try to toss the 'oldest'
incomplete fragment queues until memory limits are below the low_thresh
value. This happens in softirq/packet processing context.
This has two drawbacks:
1) processors might evict a queue that was about to be completed
by another cpu, because they will compete wrt. resource usage and
resource reclaim.
2) LRU list maintenance is expensive.
But when constantly overloaded, even the 'least recently used' element is
recent, so removing 'lru' queue first is not 'fairer' than removing any
other fragment queue.
This moves eviction out of the fast path:
When the low threshold is reached, a work queue is scheduled
which then iterates over the table and removes the queues that exceed
the memory limits of the namespace. It sets a new flag called
INET_FRAG_EVICTED on the evicted queues so the proper counters will get
incremented when the queue is forcefully expired.
When the high threshold is reached, no more fragment queues are
created until we're below the limit again.
The LRU list is now unused and will be removed in a followup patch.
Joint work with Nikolay Aleksandrov.
Suggested-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Nikolay Aleksandrov <nikolay@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
First step to move eviction handling into a work queue.
We lose two spots that accounted evicted fragments in MIB counters.
Accounting will be restored since the upcoming work-queue evictor
invokes the frag queue timer callbacks instead.
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
hide actual hash size from individual users: The _find
function will now fold the given hash value into the required range.
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
The ulog targets were recently killed. A few references to the Kconfig
macros CONFIG_IP_NF_TARGET_ULOG and CONFIG_BRIDGE_EBT_ULOG were left
untouched. Kill these too.
Signed-off-by: Paul Bolle <pebolle@tiscali.nl>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
In this file, function names are otherwise used as pointers without &.
A simplified version of the Coccinelle semantic patch that makes this
change is as follows:
// <smpl>
@r@
identifier f;
@@
f(...) { ... }
@@
identifier r.f;
@@
- &f
+ f
// </smpl>
Signed-off-by: Himangi Saraogi <himangi774@gmail.com>
Acked-by: Julia Lawall <julia.lawall@lip6.fr>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
In this file, function names are otherwise used as pointers without &.
A simplified version of the Coccinelle semantic patch that makes this
change is as follows:
// <smpl>
@r@
identifier f;
@@
f(...) { ... }
@@
identifier r.f;
@@
- &f
+ f
// </smpl>
Signed-off-by: Himangi Saraogi <himangi774@gmail.com>
Acked-by: Julia Lawall <julia.lawall@lip6.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>
Currently, although IP_MULTICAST_ALL and IP_MSFILTER ioctl calls succeed on
raw sockets, there is no code to implement the functionality on received
packets; it is only implemented for UDP sockets. The raw(7) man page states:
"In addition, all ip(7) IPPROTO_IP socket options valid for datagram sockets
are supported", which implies these ioctls should work on raw sockets.
To fix this, add a call to ip_mc_sf_allow on raw sockets.
This should not break any existing code, since the current position of
not calling ip_mc_sf_filter makes it behave as if neither the IP_MULTICAST_ALL
nor the IP_MSFILTER ioctl had been called. Adding the call to ip_mc_sf_allow
will therefore maintain the current behaviour so long as IP_MULTICAST_ALL and
IP_MSFILTER ioctls are not called. Any code that currently is calling
IP_MULTICAST_ALL or IP_MSFILTER ioctls on raw sockets presumably is wanting
the filter to be applied, although no filtering will currently be occurring.
Signed-off-by: Quentin Armitage <quentin@armitage.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>
It hasn't been used since commit 0fd7bac(net: relax rcvbuf limits).
Signed-off-by: Sorin Dumitru <sorin@returnze.ro>
Signed-off-by: David S. Miller <davem@davemloft.net>
Conflicts:
drivers/infiniband/hw/cxgb4/device.c
The cxgb4 conflict was simply overlapping changes.
Signed-off-by: David S. Miller <davem@davemloft.net>
Pablo Neira Ayuso says:
====================
Netfilter updates for net-next
The following patchset contains updates for your net-next tree,
they are:
1) Use kvfree() helper function from x_tables, from Eric Dumazet.
2) Remove extra timer from the conntrack ecache extension, use a
workqueue instead to redeliver lost events to userspace instead,
from Florian Westphal.
3) Removal of the ulog targets for ebtables and iptables. The nflog
infrastructure superseded this almost 9 years ago, time to get rid
of this code.
4) Replace the list of loggers by an array now that we can only have
two possible non-overlapping logger flavours, ie. kernel ring buffer
and netlink logging.
5) Move Eric Dumazet's log buffer code to nf_log to reuse it from
all of the supported per-family loggers.
6) Consolidate nf_log_packet() as an unified interface for packet logging.
After this patch, if the struct nf_loginfo is available, it explicitly
selects the logger that is used.
7) Move ip and ip6 logging code from xt_LOG to the corresponding
per-family loggers. Thus, x_tables and nf_tables share the same code
for packet logging.
8) Add generic ARP packet logger, which is used by nf_tables. The
format aims to be consistent with the output of xt_LOG.
9) Add generic bridge packet logger. Again, this is used by nf_tables
and it routes the packets to the real family loggers. As a result,
we get consistent logging format for the bridge family. The ebt_log
logging code has been intentionally left in place not to break
backward compatibility since the logging output differs from xt_LOG.
10) Update nft_log to explicitly request the required family logger when
needed.
11) Finish nft_log so it supports arp, ip, ip6, bridge and inet families.
Allowing selection between netlink and kernel buffer ring logging.
12) Several fixes coming after the netfilter core logging changes spotted
by robots.
13) Use IS_ENABLED() macros whenever possible in the netfilter tree,
from Duan Jiong.
14) Removal of a couple of unnecessary branch before kfree, from Fabian
Frederick.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>
Many multicast sources can have the same port which can result in a very
large list when hashing by port only. Hash by address and port instead
if this is the case. This makes multicast more similar to unicast.
On a 24-core machine receiving from 500 multicast sockets on the same
port, before this patch 80% of system CPU was used up by spin locking
and only ~25% of packets were successfully delivered.
With this patch, all packets are delivered and kernel overhead is ~8%
system CPU on spinlocks.
Signed-off-by: David Held <drheld@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Switch to using sk_nulls_for_each which shortens the code and makes it
easier to update.
Signed-off-by: David Held <drheld@google.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Fixed a bug that was introduced by my GRE-GRO patch
(bf5a755f5e net-gre-gro: Add GRE
support to the GRO stack) that breaks the forwarding path
because various GSO related fields were not set. The bug will
cause on the egress path either the GSO code to fail, or a
GRE-TSO capable (NETIF_F_GSO_GRE) NICs to choke. The following
fix has been tested for both cases.
Signed-off-by: H.K. Jerry Chu <hkchu@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Add SO_TIMESTAMPING to sockets of type PF_INET[6]/SOCK_RAW:
Add the necessary sock_tx_timestamp calls to the datapath for RAW
sockets (ping sockets already had these calls).
Fix the IP output path to pass the timestamp flags on the first
fragment also for these sockets. The existing code relies on
transhdrlen != 0 to indicate a first fragment. For these sockets,
that assumption does not hold.
This fixes http://bugzilla.kernel.org/show_bug.cgi?id=77221
Tested SOCK_RAW on IPv4 and IPv6, not PING.
Signed-off-by: Willem de Bruijn <willemb@google.com>
Acked-by: Richard Cochran <richardcochran@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Since Yuchung's 9b44190dc1 (tcp: refactor F-RTO), tcp_enter_cwr is always
called with set_ssthresh = 1. Thus, we can remove this argument from
tcp_enter_cwr. Further, as we remove this one, tcp_init_cwnd_reduction
is then always called with set_ssthresh = true, and so we can get rid of
this argument as well.
Cc: Yuchung Cheng <ycheng@google.com>
Signed-off-by: Christoph Paasch <christoph.paasch@uclouvain.be>
Acked-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Added udp_tunnel.c which can contain some common functions for UDP
tunnels. The first function in this is udp_sock_create which is used
to open the listener port for a UDP tunnel.
Signed-off-by: Tom Herbert <therbert@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
To get offloads to work with Generic Routing Encapsulation (GRE), the
outer transport header has to be reset after skb_push is done. This
patch has the support for this fix and hence GRE offloading.
Signed-off-by: Amritha Nambiar <amritha.nambiar@intel.com>
Signed-off-by: Joseph Gasparakis <joseph.gasparakis@intel.com>
Tested-By: Jim Young <jamesx.m.young@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
It is only tested, and declared, in the bootp code.
So, in ic_dynamic() guard it's setting with IPCONFIG_BOOTP.
Signed-off-by: David S. Miller <davem@davemloft.net>
ic_dev_xid is only used in __init ic_bootp_recv under IPCONFIG_BOOTP
and __init ic_dynamic under IPCONFIG_DYNAMIC(which is itself defined
with the same IPCONFIG_BOOTP)
This patch fixes the following warning when IPCONFIG_BOOTP is not set:
>> net/ipv4/ipconfig.c:146:15: warning: 'ic_dev_xid' defined but not used [-Wunused-variable]
static __be32 ic_dev_xid; /* Device under configuration */
Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Cc: Fengguang Wu <fengguang.wu@intel.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
Cc: netdev@vger.kernel.org
Signed-off-by: Fabian Frederick <fabf@skynet.be>
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch fixes 3 similar bugs where incoming packets might be routed into
wrong non-wildcard tunnels:
1) Consider the following setup:
ip address add 1.1.1.1/24 dev eth0
ip address add 1.1.1.2/24 dev eth0
ip tunnel add ipip1 remote 2.2.2.2 local 1.1.1.1 mode ipip dev eth0
ip link set ipip1 up
Incoming ipip packets from 2.2.2.2 were routed into ipip1 even if it has dst =
1.1.1.2. Moreover even if there was wildcard tunnel like
ip tunnel add ipip0 remote 2.2.2.2 local any mode ipip dev eth0
but it was created before explicit one (with local 1.1.1.1), incoming ipip
packets with src = 2.2.2.2 and dst = 1.1.1.2 were still routed into ipip1.
Same issue existed with all tunnels that use ip_tunnel_lookup (gre, vti)
2) ip address add 1.1.1.1/24 dev eth0
ip tunnel add ipip1 remote 2.2.146.85 local 1.1.1.1 mode ipip dev eth0
ip link set ipip1 up
Incoming ipip packets with dst = 1.1.1.1 were routed into ipip1, no matter what
src address is. Any remote ip address which has ip_tunnel_hash = 0 raised this
issue, 2.2.146.85 is just an example, there are more than 4 million of them.
And again, wildcard tunnel like
ip tunnel add ipip0 remote any local 1.1.1.1 mode ipip dev eth0
wouldn't be ever matched if it was created before explicit tunnel like above.
Gre & vti tunnels had the same issue.
3) ip address add 1.1.1.1/24 dev eth0
ip tunnel add gre1 remote 2.2.146.84 local 1.1.1.1 key 1 mode gre dev eth0
ip link set gre1 up
Any incoming gre packet with key = 1 were routed into gre1, no matter what
src/dst addresses are. Any remote ip address which has ip_tunnel_hash = 0 raised
the issue, 2.2.146.84 is just an example, there are more than 4 million of them.
Wildcard tunnel like
ip tunnel add gre2 remote any local any key 1 mode gre dev eth0
wouldn't be ever matched if it was created before explicit tunnel like above.
All this stuff happened because while looking for a wildcard tunnel we didn't
check that matched tunnel is a wildcard one. Fixed.
Signed-off-by: Dmitry Popov <ixaphire@qrator.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
ic_dev_xid is only used in ipconfig.c
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
Cc: netdev@vger.kernel.org
Signed-off-by: Fabian Frederick <fabf@skynet.be>
Signed-off-by: David S. Miller <davem@davemloft.net>
The undo code assumes that, upon entering loss recovery, TCP
1) always retransmit something
2) the retransmission never fails locally (e.g., qdisc drop)
so undo_marker is set in tcp_enter_recovery() and undo_retrans is
incremented only when tcp_retransmit_skb() is successful.
When the assumption is broken because TCP's cwnd is too small to
retransmit or the retransmit fails locally. The next (DUP)ACK
would incorrectly revert the cwnd and the congestion state in
tcp_try_undo_dsack() or tcp_may_undo(). Subsequent (DUP)ACKs
may enter the recovery state. The sender repeatedly enter and
(incorrectly) exit recovery states if the retransmits continue to
fail locally while receiving (DUP)ACKs.
The fix is to initialize undo_retrans to -1 and start counting on
the first retransmission. Always increment undo_retrans even if the
retransmissions fail locally because they couldn't cause DSACKs to
undo the cwnd reduction.
Signed-off-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
