linux.git/net/netfilter/xt_NFLOG.c, branch v6.9

netfilter: log: work around missing softdep backend module

2021-09-21T01:46:56+00:00

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 
Signed-off-by: Florian Westphal 
Signed-off-by: Pablo Neira Ayuso

netfilter: nf_log: add module softdeps

2021-03-31T20:34:10+00:00

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 
Signed-off-by: Pablo Neira Ayuso

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

2019-06-19T15:09:55+00:00

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 
Reviewed-by: Enrico Weigelt 
Reviewed-by: Kate Stewart 
Reviewed-by: Allison Randal 
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190604081206.933168790@linutronix.de
Signed-off-by: Greg Kroah-Hartman

netfilter: xt_NFLOG: use nf_log_packet instead of nfulnl_log_packet.

2018-04-19T11:02:44+00:00

The nfulnl_log_packet() is added to make sure that the NFLOG target
works as only user-space logger. but now, nf_log_packet() can find proper
log function using NF_LOG_TYPE_ULOG and NF_LOG_TYPE_LOG.

Signed-off-by: Taehee Yoo 
Signed-off-by: Pablo Neira Ayuso

netfilter: x_tables: move hook state into xt_action_param structure

2016-11-03T09:56:21+00:00

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

netfilter: xt_NFLOG: fix unexpected truncated packet

2016-10-17T15:38:19+00:00

Justin and Chris spotted that iptables NFLOG target was broken when they
upgraded the kernel to 4.8: "ulogd-2.0.5- IPs are no longer logged" or
"results in segfaults in ulogd-2.0.5".

Because "struct nf_loginfo li;" is a local variable, and flags will be
filled with garbage value, not inited to zero. So if it contains 0x1,
packets will not be logged to the userspace anymore.

Fixes: 7643507fe8b5 ("netfilter: xt_NFLOG: nflog-range does not truncate packets")
Reported-by: Justin Piszcz 
Reported-by: Chris Caputo 
Tested-by: Chris Caputo 
Signed-off-by: Liping Zhang 
Signed-off-by: Pablo Neira Ayuso

netfilter: xt_NFLOG: nflog-range does not truncate packets

2016-06-24T09:03:23+00:00

li->u.ulog.copy_len is currently ignored by the kernel, we should truncate
the packet to either li->u.ulog.copy_len (if set) or copy_range before
sending it to userspace. 0 is a valid input for copy_len, so add a new
flag to indicate whether this was option was specified by the user or not.

Add two flags to indicate whether nflog-size/copy_len was set or not.
XT_NFLOG_F_COPY_LEN is for XT_NFLOG and NFLOG_F_COPY_LEN for nfnetlink_log

On the userspace side, this was initially represented by the option
nflog-range, this will be replaced by --nflog-size now. --nflog-range would
still exist but does not do anything.

Reported-by: Joe Dollard 
Reviewed-by: Josh Hunt 
Signed-off-by: Vishwanath Pai 
Signed-off-by: Pablo Neira Ayuso

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

2015-09-18T19:58:25+00:00

Signed-off-by: "Eric W. Biederman" 
Signed-off-by: Pablo Neira Ayuso

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

2013-05-15T12:11:07+00:00

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: [] 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 
Signed-off-by: Hans Schillstrom 
Signed-off-by: Pablo Neira Ayuso

netfilter: xtables: substitute temporary defines by final name

2010-05-11T16:31:17+00:00

Signed-off-by: Jan Engelhardt