netfilter: log: work around missing softdep backend module

iptables/nftables has two types of log modules:

1. backend, e.g. nf_log_syslog, which implement the functionality
2. frontend, e.g. xt_LOG or nft_log, which call the functionality
provided by backend based on nf_tables or xtables rule set.

Problem is that the request_module() call to load the backed in
nf_logger_find_get() might happen with nftables transaction mutex held
in case the call path is via nf_tables/nft_compat.

This can cause deadlocks (see 'Fixes' tags for details).

The chosen solution as to let modprobe deal with this by adding 'pre: '
soft dep tag to xt_LOG (to load the syslog backend) and xt_NFLOG (to
load nflog backend).

Eric reports that this breaks on systems with older modprobe that
doesn't support softdeps.

Another, similar issue occurs when someone either insmods xt_(NF)LOG
directly or unloads the backend module (possible if no log frontend
is in use): because the frontend module is already loaded, modprobe is
not invoked again so the softdep isn't evaluated.

Add a workaround: If nf_logger_find_get() returns -ENOENT and call
is not via nft_compat, load the backend explicitly and try again.

Else, let nft_compat ask for deferred request_module via nf_tables
infra.

Softdeps are kept in-place, so with newer modprobe the dependencies
are resolved from userspace.

Fixes: cefa31a9d461 ("netfilter: nft_log: perform module load from nf_tables")
Fixes: a38b5b56d6f4 ("netfilter: nf_log: add module softdeps")
Reported-and-tested-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: nf_log: add module softdeps

xt_LOG has no direct dependency on the syslog-based logger, it relies
on the nf_log core to probe the requested backend.

Now that all syslog-based loggers reside in the same module, we can
just add a soft dependency on nf_log_syslog and let modprobe take
care of it.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500

Based on 2 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 version 2 as
published by the free software foundation

this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license version 2 as
published by the free software foundation #

extracted by the scancode license scanner the SPDX license identifier

GPL-2.0-only

has been chosen to replace the boilerplate/reference in 4122 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Enrico Weigelt <info@metux.net>
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190604081206.933168790@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

netfilter: x_tables: move hook state into xt_action_param structure

Place pointer to hook state in xt_action_param structure instead of
copying the fields that we need. After this change xt_action_param fits
into one cacheline.

This patch also adds a set of new wrapper functions to fetch relevant
hook state structure fields.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: x_tables: Use par->net instead of computing from the passed net devices

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: xt_LOG: add missing string format in nf_log_packet()

net/netfilter/xt_LOG.c: In function 'log_tg':
>> net/netfilter/xt_LOG.c:43: error: format not a string literal and no format arguments

Fixes: fab4085 ("netfilter: log: nf_log_packet() as real unified interface")
Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: log: nf_log_packet() as real unified interface

Before this patch, the nf_loginfo parameter specified the logging
configuration in case the specified default logger was loaded. This
patch updates the semantics of the nf_loginfo parameter in
nf_log_packet() which now indicates the logger that you explicitly
want to use.

Thus, nf_log_packet() is exposed as an unified interface which
internally routes the log message to the corresponding logger type
by family.

The module dependencies are expressed by the new nf_logger_find_get()
and nf_logger_put() functions which bump the logger module refcount.
Thus, you can not remove logger modules that are used by rules anymore.

Another important effect of this change is that the family specific
module is only loaded when required. Therefore, xt_LOG and nft_log
will just trigger the autoload of the nf_log_{ip,ip6} modules
according to the family.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: log: split family specific code to nf_log_{ip,ip6,common}.c files

The plain text logging is currently embedded into the xt_LOG target.
In order to be able to use the plain text logging from nft_log, as a
first step, this patch moves the family specific code to the following
files and Kconfig symbols:

1) net/ipv4/netfilter/nf_log_ip.c: CONFIG_NF_LOG_IPV4
2) net/ipv6/netfilter/nf_log_ip6.c: CONFIG_NF_LOG_IPV6
3) net/netfilter/nf_log_common.c: CONFIG_NF_LOG_COMMON

These new modules will be required by xt_LOG and nft_log. This patch
is based on original patch from Arturo Borrero Gonzalez.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: nf_log: move log buffering to core logging

This patch moves Eric Dumazet's log buffer implementation from the
xt_log.h header file to the core net/netfilter/nf_log.c. This also
includes the renaming of the structure and functions to avoid possible
undesired namespace clashes.

This change allows us to use it from the arp and bridge packet logging
implementation in follow up patches.

netfilter: nf_log: use an array of loggers instead of list

Now that legacy ulog targets are not available anymore in the tree, we
can have up to two possible loggers:

1) The plain text logging via kernel logging ring.
2) The nfnetlink_log infrastructure which delivers log messages
to userspace.

This patch replaces the list of loggers by an array of two pointers
per family for each possible logger and it also introduces a new field
to the nf_logger structure which indicates the position in the logger
array (based on the logger type).

This prepares a follow up patch that consolidates the nf_log_packet()
interface by allowing to specify the logger as parameter.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: xt_LOG: fix mark logging for IPv6 packets

In dump_ipv6_packet(), the "recurse" parameter is zero only if
dumping contents of a packet embedded into an ICMPv6 error
message. Therefore we want to log packet mark if recurse is
non-zero, not when it is zero.

Signed-off-by: Michal Kubecek <mkubecek@suse.cz>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: log: netns NULL ptr bug when calling from conntrack

Since (69b34fb netfilter: xt_LOG: add net namespace support
for xt_LOG), we hit this:

[ 4224.708977] BUG: unable to handle kernel NULL pointer dereference at 0000000000000388
[ 4224.709074] IP: [<ffffffff8147f699>] ipt_log_packet+0x29/0x270

when callling log functions from conntrack both in and out
are NULL i.e. the net pointer is invalid.

Adding struct net *net in call to nf_logfn() will secure that
there always is a vaild net ptr.

Reported as netfilter's bugzilla bug 818:
https://bugzilla.netfilter.org/show_bug.cgi?id=818

Reported-by: Ronald <ronald645@gmail.com>
Signed-off-by: Hans Schillstrom <hans@schillstrom.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: xt_LOG: add net namespace support for xt_LOG

Add pernet support to xt_LOG by means of the new nf_log_set
function added in (30e0c6a netfilter: nf_log: prepare net
namespace support for loggers).

Since syslog ns has yet not been implemented, we don't want
the containers to DDOS host's syslogd. So only enable ebt_log
only from init_net and wait for syslog ns support

Signed-off-by: Gao feng <gaofeng@cn.fujitsu.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: log: Fix log-level processing

auto75914331@hushmail.com reports that iptables does not correctly
output the KERN_<level>.

$IPTABLES -A RULE_0_in -j LOG --log-level notice --log-prefix "DENY in: "

result with linux 3.6-rc5
Sep 12 06:37:29 xxxxx kernel: <5>DENY in: IN=eth0 OUT= MAC=.......

result with linux 3.5.3 and older:
Sep 9 10:43:01 xxxxx kernel: DENY in: IN=eth0 OUT= MAC......

commit 04d2c8c83d0
("printk: convert the format for KERN_<LEVEL> to a 2 byte pattern")
updated the syslog header style but did not update netfilter uses.

Do so.

Use KERN_SOH and string concatenation instead of "%c" KERN_SOH_ASCII
as suggested by Eric Dumazet.

Signed-off-by: Joe Perches <joe@perches.com>
cc: auto75914331@hushmail.com
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: take care of timewait sockets

Sami Farin reported crashes in xt_LOG because it assumes skb->sk is a
full blown socket.

Since (41063e9 ipv4: Early TCP socket demux), we can have skb->sk
pointing to a timewait socket.

Same fix is needed in nfnetlink_log.

Diagnosed-by: Florian Westphal <fw@strlen.de>
Reported-by: Sami Farin <hvtaifwkbgefbaei@gmail.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

userns: Convert xt_LOG to print socket kuids and kgids as uids and gids

xt_LOG always writes messages via sb_add via printk. Therefore when
xt_LOG logs the uid and gid of a socket a packet came from the
values should be converted to be in the initial user namespace.

Thus making xt_LOG as user namespace safe as possible.

Cc: Pablo Neira Ayuso <pablo@netfilter.org>
Cc: Patrick McHardy <kaber@trash.net>
Acked-by: David S. Miller <davem@davemloft.net>
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>

netfilter: xt_LOG: use CONFIG_IP6_NF_IPTABLES instead of CONFIG_IPV6

This fixes the following linking error:

xt_LOG.c:(.text+0x789b1): undefined reference to `ip6t_ext_hdr'

ifdefs have to use CONFIG_IP6_NF_IPTABLES instead of CONFIG_IPV6.

Acked-by: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: xt_LOG: fix bogus extra layer-4 logging information

In 16059b5 netfilter: merge ipt_LOG and ip6_LOG into xt_LOG, we have
merged ipt_LOG and ip6t_LOG.

However:

IN=wlan0 OUT= MAC=xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx:xx
SRC=213.150.61.61 DST=192.168.1.133 LEN=40 TOS=0x00 PREC=0x00 TTL=117
ID=10539 DF PROTO=TCP SPT=80 DPT=49013 WINDOW=0 RES=0x00 ACK RST
URGP=0 PROTO=UDPLITE SPT=80 DPT=49013 LEN=45843 PROTO=ICMP TYPE=0
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Several missing break in the code led to including bogus layer-4
information. This patch fixes this problem.

Signed-off-by: Richard Weinberger <richard@nod.at>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: merge ipt_LOG and ip6_LOG into xt_LOG

ipt_LOG and ip6_LOG have a lot of common code, merge them
to reduce duplicate code.

Signed-off-by: Richard Weinberger <richard@nod.at>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>