Add a SYNPROXY for netfilter. The code is split into two parts, the synproxy
core with common functions and an address family specific target.

The SYNPROXY receives the connection request from the client, responds with
a SYN/ACK containing a SYN cookie and announcing a zero window and checks
whether the final ACK from the client contains a valid cookie.

It then establishes a connection to the original destination and, if
successful, sends a window update to the client with the window size
announced by the server.

Support for timestamps, SACK, window scaling and MSS options can be
statically configured as target parameters if the features of the server
are known. If timestamps are used, the timestamp value sent back to
the client in the SYN/ACK will be different from the real timestamp of
the server. In order to now break PAWS, the timestamps are translated in
the direction server->client.
Signed-off-by: NPatrick McHardy <kaber@trash.net>
Tested-by: NMartin Topholm <mph@one.com>
Signed-off-by: NJesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>

Split out sequence number adjustments from NAT and move them to the conntrack
core to make them usable for SYN proxying. The sequence number adjustment
information is moved to a seperate extend. The extend is added to new
conntracks when a NAT mapping is set up for a connection using a helper.

As a side effect, this saves 24 bytes per connection with NAT in the common
case that a connection does not have a helper assigned.
Signed-off-by: NPatrick McHardy <kaber@trash.net>
Tested-by: NMartin Topholm <mph@one.com>
Signed-off-by: NJesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>

This patch adds the capability to attach expectations via nfnetlink_queue.
This is required by conntrack helpers that trigger expectations based on
the first packet seen like the TFTP and the DHCPv6 user-space helpers.
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>

This patch refactors ctnetlink_create_expect by spliting it in two
chunks. As a result, we have a new function ctnetlink_alloc_expect
to allocate and to setup the expectation from ctnetlink.
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>

Currently the conntrack checks if the ending sequence of a packet
falls within the observed receive window. However it does so even
if it has not observe any packet from the remote yet and uses an
uninitialized receive window (td_maxwin).

If a connection uses Fast Open to send a SYN-data packet which is
dropped afterward in the network. The subsequent SYNs retransmits
will all fail this check and be discarded, leading to a connection
timeout. This is because the SYN retransmit does not contain data
payload so

end == initial sequence number (isn) + 1
sender->td_end == isn + syn_data_len
receiver->td_maxwin == 0

The fix is to only apply this check after td_maxwin is initialized.
Reported-by: NMichael Chan <mcfchan@stanford.edu>
Signed-off-by: NYuchung Cheng <ycheng@google.com>
Acked-by: NEric Dumazet <edumazet@google.com>
Acked-by: NJozsef Kadlecsik <kadlec@blackhole.kfki.hu>
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>

Let nf_ct_delete handle delivery of the DESTROY event.

Based on earlier patch from Pablo Neira.
Signed-off-by: NFlorian Westphal <fw@strlen.de>
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>

skb_header_pointer could return NULL, so check for it as we do it
everywhere else in ipvs code. This fixes a coverity warning.
Signed-off-by: NDaniel Borkmann <dborkman@redhat.com>
Acked-by: NJulian Anastasov <ja@ssi.bg>
Signed-off-by: NSimon Horman <horms@verge.net.au>

found using checkpatch.pl
Signed-off-by: NDragos Foianu <dragos.foianu@gmail.com>
Signed-off-by: NSimon Horman <horms@verge.net.au>

These structs have a "_pad" member.  Also the "phw" structs have an 8
byte "hw_addr[]" array but sometimes only the first 6 bytes are
initialized.
Signed-off-by: NDan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>

after commit 93742cf8 (netfilter: tproxy: remove nf_tproxy_core.h)

CONFIG_IPV6=y
CONFIG_IP6_NF_IPTABLES=n

gives us:

net/netfilter/xt_TPROXY.c: In function 'nf_tproxy_get_sock_v6':
net/netfilter/xt_TPROXY.c:178:4: error: implicit declaration of function 'inet6_lookup_listener'
Reported-by: Nkbuild test robot <fengguang.wu@intel.com>
Signed-off-by: NFlorian Westphal <fw@strlen.de>
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>

Fix a possible off by one access since optlen()
touches opt[offset+1] unsafely when i == tcp_hdrlen(skb) - 1.

This patch replaces tcp_hdrlen() by the local variable tcp_hdrlen
that stores the TCP header length, to save some cycles.
Reported-by: NJulian Anastasov <ja@ssi.bg>
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>

Make sure the packet has enough room for the TCP header and
that it is not malformed.

While at it, store tcph->doff*4 in a variable, as it is used
several times.

This patch also fixes a possible off by one in case of malformed
TCP options.
Reported-by: NJulian Anastasov <ja@ssi.bg>
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>

Get rid of the global lock and use per-conntrack locks for protecting the
sequencen number adjustment data. Additionally saves one lock/unlock
operation for every TCP packet.
Signed-off-by: NPatrick McHardy <kaber@trash.net>
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>

Using 16 bits is too small, when many adjustments happen the offsets might
overflow and break the connection.
Signed-off-by: NPatrick McHardy <kaber@trash.net>
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>

nf_nat_seq_adjust() needs to grab nf_nat_seqofs_lock to protect against
concurrent changes to the sequence adjustment data.
Signed-off-by: NPatrick McHardy <kaber@trash.net>
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>

ctnetlink contains copy-paste code from death_by_timeout.  In order to
avoid changing both places in upcoming event delivery patch,
export death_by_timeout functionality and use it in the ctnetlink code.

Based on earlier patch from Pablo Neira.
Signed-off-by: NFlorian Westphal <fw@strlen.de>
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>

We've removed nf_tproxy_core.ko, so also remove its header.
The lookup helpers are split and then moved to tproxy target/socket match.
Signed-off-by: NFlorian Westphal <fw@strlen.de>
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>

The module was "permanent", due to the special tproxy skb->destructor.
Nowadays we have tcp early demux and its sock_edemux destructor in
networking core which can be used instead.

Thanks to early demux changes the input path now also handles
"skb->sk is tw socket" correctly, so this no longer needs the special
handling introduced with commit d503b30b
(netfilter: tproxy: do not assign timewait sockets to skb->sk).

Thus:
- move assign_sock function to where its needed
- don't prevent timewait sockets from being assigned to the skb
- remove nf_tproxy_core.
Signed-off-by: NFlorian Westphal <fw@strlen.de>
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>

Allow modifying attributes of the conntrack associated with a packet
without first requesting ct data via CFG_F_CONNTRACK or extra
nfnetlink_conntrack socket.

Also remove unneded rcu_read_lock; the entire function is already
protected by rcu.
Signed-off-by: NFlorian Westphal <fw@strlen.de>
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>

leftovers from the (never merged) v1 patch.
Signed-off-by: NFlorian Westphal <fw@strlen.de>
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>

Signed-off-by: NPatrick McHardy <kaber@trash.net>
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>

Fix typo in error message.
Signed-off-by: NPhil Oester <kernel@linuxace.com>
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>

This patch consolidates the SCTP checksum calculation code from various
places to a single new function, sctp_compute_cksum(skb, offset).
Signed-off-by: NJoe Stringer <joe@wand.net.nz>
Reviewed-by: NJulian Anastasov <ja@ssi.bg>
Acked-by: NSimon Horman <horms@verge.net.au>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

commit 681f130f ("netfilter: xt_socket: add XT_SOCKET_NOWILDCARD
flag") added a potential NULL dereference if an old iptables package
uses v0 of the match.

Fix this by removing the test on @info in fast path.

IPv6 can remove the test as well, as it uses v1 or v2.
Reported-by: NNeal Cardwell <ncardwell@google.com>
Signed-off-by: NEric Dumazet <edumazet@google.com>
Cc: Patrick McHardy <kaber@trash.net>
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>

nf_ct_expect_alloc leaves unset the expectation NAT fields. However,
ctnetlink_exp_dump_expect expects them to be zeroed in case they are
not used, which may not be the case. This results in dumping the NAT
tuple of the expectation when it should not.

Fix it by zeroing the NAT fields of the expectation.
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>

The common case is that TCP/IP checksums have already been
verified, e.g. by hardware (rx checksum offload), or conntrack.

Userspace can use this flag to determine when the checksum
has not been validated yet.

If the flag is set, this doesn't necessarily mean that the packet has
an invalid checksum, e.g. if NIC doesn't support rx checksum.

Userspace that sucessfully enabled NFQA_CFG_F_GSO queue feature flag can
infer that IP/TCP checksum has already been validated if either the
SKB_INFO attribute is not present or the NFQA_SKB_CSUM_NOTVERIFIED
flag is unset.
Signed-off-by: NFlorian Westphal <fw@strlen.de>
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>

Add sync_persist_mode flag to reduce sync traffic
by syncing only persistent templates.
Signed-off-by: NJulian Anastasov <ja@ssi.bg>
Tested-by: NAleksey Chudov <aleksey.chudov@gmail.com>
Signed-off-by: NSimon Horman <horms@verge.net.au>

By default the SH scheduler rejects connections that are hashed onto a
realserver of weight 0.  This patch adds a flag to make SH choose a
different realserver in this case, instead of rejecting the connection.

The patch also adds a flag to make SH include the source port (TCP, UDP,
SCTP) in the hash as well as the source address.  This basically allows
for deterministic round-robin load balancing (i.e., where any director
in a cluster of directors with identical config will send the same
packet the same way).

The flags are service flags (IP_VS_SVC_F_SCHED*) so that these options
can be set per service.  They are set using a new option to ipvsadm.
Signed-off-by: NAlexander Frolkin <avf@eldamar.org.uk>
Acked-by: NJulian Anastasov <ja@ssi.bg>
Signed-off-by: NSimon Horman <horms@verge.net.au>

Drop SCTP connections under load (dropentry context) depending
on the protocol state, just like for TCP: INIT conns are
dropped immediately, established are dropped randomly while
connections in progress or shutdown are skipped.
Signed-off-by: NJulian Anastasov <ja@ssi.bg>
Signed-off-by: NSimon Horman <horms@verge.net.au>

Convert the SCTP state table, so that it is more readable.
Change the states to be according to the diagram in RFC 2960
and add more states suitable for middle box. Still, such
change in states adds incompatibility if systems in sync
setup include this change and others do not include it.

With this change we also have proper transitions in INPUT-ONLY
mode (DR/TUN) where we see packets only from client. Now
we should not switch to 10-second CLOSED state at a time
when we should stay in ESTABLISHED state.

The short names for states are because we have 16-char space
in ipvsadm and 11-char limit for the connection list format.
It is a sequence of the TCP implementation where the longest
state name is ESTABLISHED.
Signed-off-by: NJulian Anastasov <ja@ssi.bg>
Signed-off-by: NSimon Horman <horms@verge.net.au>

This adds support for sloppy TCP and SCTP modes to IPVS.

When enabled (sysctls net.ipv4.vs.sloppy_tcp and
net.ipv4.vs.sloppy_sctp), allows IPVS to create connection state on any
packet, not just a TCP SYN (or SCTP INIT).

This allows connections to fail over from one IPVS director to another
mid-flight.
Signed-off-by: NAlexander Frolkin <avf@eldamar.org.uk>
Signed-off-by: NJulian Anastasov <ja@ssi.bg>
Signed-off-by: NSimon Horman <horms@verge.net.au>

Before now the schedulers needed access only to IP
addresses and it was easy to get them from skb by
using ip_vs_fill_iph_addr_only.

New changes for the SH scheduler will need the protocol
and ports which is difficult to get from skb for the
IPv6 case. As we have all the data in the iph structure,
to avoid the same slow lookups provide the iph to schedulers.
Signed-off-by: NJulian Anastasov <ja@ssi.bg>
Acked-by: NHans Schillstrom <hans@schillstrom.com>
Signed-off-by: NSimon Horman <horms@verge.net.au>

commit 0ceabd83
(netfilter: ctnetlink: deliver labels to userspace) sets the event bit
when we raced with another packet, instead of raising the event bit
when the label bit is set for the first time.

commit 9b21f6a9
(netfilter: ctnetlink: allow userspace to modify labels) forgot to update
the event mask in the "conntrack already exists" case.

Both issues result in CTA_LABELS attribute not getting included in the
conntrack event.
Signed-off-by: NFlorian Westphal <fw@strlen.de>
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>

In (b20ab9cc netfilter: nf_ct_helper: better logging for dropped packets)
there were some missing brackets around the logging information, thus
always returning drop.

Closes https://bugzilla.kernel.org/show_bug.cgi?id=60061Signed-off-by: NBalazs Peter Odor <balazs@obiserver.hu>
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>

xt_socket module can be a nice replacement to conntrack module
in some cases (SYN filtering for example)

But it lacks the ability to match the 3rd packet of TCP
handshake (ACK coming from the client).

Add a XT_SOCKET_NOWILDCARD flag to disable the wildcard mechanism.

The wildcard is the legacy socket match behavior, that ignores
LISTEN sockets bound to INADDR_ANY (or ipv6 equivalent)

iptables -I INPUT -p tcp --syn -j SYN_CHAIN
iptables -I INPUT -m socket --nowildcard -j ACCEPT
Signed-off-by: NEric Dumazet <edumazet@google.com>
Cc: Patrick McHardy <kaber@trash.net>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>

When loose tracking is enabled (default), non-syn packets cause
creation of new conntracks in established state with default timeout for
established state (5 days).  This causes the table to fill up with UNREPLIED
when the 'new ack' packet happened to be the last-ack of a previous,
already timed-out connection.

Consider:

A 192.168.x.52792 > 10.184.y.80: F, 426:426(0) ack 9237 win 255
B 10.184.y.80 > 192.168.x.52792: ., ack 427 win 123
<61 second pause>
C 10.184.y.80 > 192.168.x.52792: F, 9237:9237(0) ack 427 win 123
D 192.168.x.52792 > 10.184.y.80: ., ack 9238 win 255

B moves conntrack to CLOSE_WAIT and will kill it after 60 second timeout,
C is ignored (FIN set), but last packet (D) causes new ct with 5-days timeout.

Use UNACK timeout (5 minutes) instead to get rid of these entries sooner
when in ESTABLISHED state without having seen traffic in both directions.
Signed-off-by: NFlorian Westphal <fw@strlen.de>
Acked-by: NJozsef Kadlecsik <kadlec@blackhole.kfki.hu>
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>

These are the only calls under net/ that do not check nla_parse_nested()
for its error code, but simply continue execution. If parsing of netlink
attributes fails, we should return with an error instead of continuing.
In nearly all of these calls we have a policy attached, that is being
type verified during nla_parse_nested(), which we would miss checking
for otherwise.
Signed-off-by: NDaniel Borkmann <dborkman@redhat.com>
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>

Make sure that SCTP ports are writable when embedded in ICMP
from client, so that ip_vs_nat_icmp can translate them safely.
Signed-off-by: NJulian Anastasov <ja@ssi.bg>
Signed-off-by: NSimon Horman <horms@verge.net.au>

Reduce the uses of this unnecessary typedef.

Done via perl script:

$ git grep --name-only -w ctl_table net | \
  xargs perl -p -i -e '\
	sub trim { my ($local) = @_; $local =~ s/(^\s+|\s+$)//g; return $local; } \
        s/\b(?<!struct\s)ctl_table\b(\s*\*\s*|\s+\w+)/"struct ctl_table " . trim($1)/ge'

Reflow the modified lines that now exceed 80 columns.
Signed-off-by: NJoe Perches <joe@perches.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Similar to commit bc6bcb59 ("netfilter: xt_TCPOPTSTRIP: fix
possible mangling beyond packet boundary"), add safe fragment
handling to xt_TCPMSS.
Signed-off-by: NPhil Oester <kernel@linuxace.com>
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>