Quoting reporter:
A race between GRE keymap insertion and destruction can corrupt the
kernel list or use a freed object. `nf_ct_gre_keymap_add()` publishes a
new keymap pointer before the embedded `list_head` is linked, while
`nf_ct_gre_keymap_destroy()` can concurrently delete and free that
same object. An unprivileged user can reach this through the PPTP
conntrack helper by racing PPTP control messages or helper teardown,
leading to KASAN-detectable list corruption/UAF in kernel context.
## Root Cause Analysis
`exp_gre()` installs GRE expectations for a PPTP control flow and then
adds two GRE keymap entries [..]
The add path publishes `ct_pptp_info->keymap[dir]` before linking the
embedded list node [..]
Concurrent teardown deletes that partially initialized object.
Make add/destroy symmetric: install both, destroy both while under lock.
Furthermore, we should refuse to publish a new mapping in case ct is going
away, else we may leak the allocation.
The "retrans" detection is strange: existing mapping is checked for key
equality with the new mapping, then for "is on the list" via list walk.
But I can't see how an existing keymap entry can be NOT on list.
Change this to only check if we're asked to map same tuple again -- if so,
skip re-install, else signal failure.
Last, add a bug trap for the keymap list; it has to be empty when namespace
is going away.
Reported-by: Leo Lin <leo@depthfirst.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Previous change added xtables_unregister_table_pre_exit to detach the
table from the packetpath and to unlink it from the active table list.
In case of rmmod, userspace that is doing set/getsockopt for this table
will not be able to re-instantiate the table:
1. The larval table has been removed already
2. existing instantiated table is no longer on the xt pernet table list.
This adds the second stage helper:
unlink the table from the dying list, free the hook ops (if any) and do
the audit notification. It replaces xt_unregister_table().
Fixes: fdacd57c79 ("netfilter: x_tables: never register tables by default")
Reported-by: Tristan Madani <tristan@talencesecurity.com>
Reviewed-by: Tristan Madani <tristan@talencesecurity.com>
Closes: https://lore.kernel.org/netfilter-devel/20260429175613.1459342-1-tristmd@gmail.com/
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Remove the copypasted variants of _pre_exit and add one single
function in the xtables core. ebtables is not compatible with
x_tables and therefore unchanged.
This is a preparation patch to reduce noise in the followup
bug fixes.
Reviewed-by: Tristan Madani <tristan@talencesecurity.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
arp/ip(6)t_register_table() add the table to the per-netns list via
xt_register_table() before allocating the per-netns hook ops copy
via kmemdup_array(). This leaves a window where the table is
visible in the list with ops=NULL.
If the pernet exit happens runs concurrently the pre_exit callback finds
the table via xt_find_table() and passes the NULL ops pointer to
nf_unregister_net_hooks(), causing a NULL dereference:
general protection fault in nf_unregister_net_hooks+0xbc/0x150
RIP: nf_unregister_net_hooks (net/netfilter/core.c:613)
Call Trace:
ipt_unregister_table_pre_exit
iptable_mangle_net_pre_exit
ops_pre_exit_list
cleanup_net
Fix by moving the ops allocation into the xtables core so the table is
never in the list without valid ops. Also ensure the table is no longer
processing packets before its torn down on error unwind.
nf_register_net_hooks might have published at least one hook; call
synchronize_rcu() if there was an error.
audit log register message gets deferred until all operations have
passed, this avoids need to emit another ureg message in case of
error unwinding.
Based on earlier patch by Tristan Madani.
Fixes: f9006acc8d ("netfilter: arp_tables: pass table pointer via nf_hook_ops")
Fixes: ee177a5441 ("netfilter: ip6_tables: pass table pointer via nf_hook_ops")
Fixes: ae68933422 ("netfilter: ip_tables: pass table pointer via nf_hook_ops")
Link: https://lore.kernel.org/netfilter-devel/20260429175613.1459342-1-tristmd@gmail.com/
Signed-off-by: Tristan Madani <tristan@talencesecurity.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Add a new .check_hooks interface for checking if the match/target is
used from the validate hook according to its configuration.
Move existing conditional hook check based on the match/target
configuration from .checkentry to .check_hooks for the following
matches/targets:
- addrtype
- devgroup
- physdev
- policy
- set
- TCPMSS
- SET
This is a preparation patch to fix nft_compat, not functional changes
are intended.
Based on patch from Florian Westphal.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
After commit 07919126ec ("netfilter: annotate NAT helper hook pointers
with __rcu"), sparse can warn about type/address-space mismatches when
RCU-dereferencing NAT helper hook function pointers.
The hooks are __rcu-annotated and accessed via rcu_dereference(), but the
combination of complex function pointer declarators and the WRITE_ONCE()
machinery used by RCU_INIT_POINTER()/rcu_assign_pointer() can confuse
sparse and trigger false positives.
Introduce typedefs for the NAT helper function types, so __rcu applies to
a simple "fn_t __rcu *" pointer form. Also replace local typeof(hook)
variables with "fn_t *" to avoid propagating __rcu address space into
temporaries.
No functional change intended.
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202603022359.3dGE9fwI-lkp@intel.com/
Signed-off-by: Sun Jian <sun.jian.kdev@gmail.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
IPSET_ATTR_NAME and IPSET_ATTR_NAMEREF are of NLA_STRING type, they
cannot be treated like a c-string.
They either have to be switched to NLA_NUL_STRING, or the compare
operations need to use the nla functions.
Fixes: f830837f0e ("netfilter: ipset: list:set set type support")
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
The NAT helper hook pointers are updated and dereferenced under RCU rules,
but lack the proper __rcu annotation.
This makes sparse report address space mismatches when the hooks are used
with rcu_dereference().
Add the missing __rcu annotations to the global hook pointer declarations
and definitions in Amanda, FTP, IRC, SNMP and TFTP.
No functional change intended.
Suggested-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Sun Jian <sun.jian.kdev@gmail.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
several netfilter compilation units rely on implicit includes
coming from nf_conntrack_proto_gre.h.
Clean this up and add the required dependencies where needed.
nf_conntrack.h requires net_generic() helper.
Place various gre/ppp/vlan includes to where they are needed.
Signed-off-by: Florian Westphal <fw@strlen.de>
Since commit 2173c519d5 ("audit: normalize NETFILTER_PKT")
these are unused, so can be removed.
Signed-off-by: Yue Haibing <yuehaibing@huawei.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
The DCCP socket family has now been removed from this tree, see:
8bb3212be4 ("Merge branch 'net-retire-dccp-socket'")
Remove connection tracking and NAT support for this protocol, this
should not pose a problem because no DCCP traffic is expected to be seen
on the wire.
As for the code for matching on dccp header for iptables and nftables,
mark it as deprecated and keep it in place. Ruleset restoration is an
atomic operation. Without dccp matching support, an astray match on dccp
could break this operation leaving your computer with no policy in
place, so let's follow a more conservative approach for matches.
Add CONFIG_NFT_EXTHDR_DCCP which is set to 'n' by default to deprecate
dccp extension support. Similarly, label CONFIG_NETFILTER_XT_MATCH_DCCP
as deprecated too and also set it to 'n' by default.
Code to match on DCCP protocol from ebtables also remains in place, this
is just a few checks on IPPROTO_DCCP from _check() path which is
exercised when ruleset is loaded. There is another use of IPPROTO_DCCP
from the _check() path in the iptables multiport match. Another check
for IPPROTO_DCCP from the packet in the reject target is also removed.
So let's schedule removal of the dccp matching for a second stage, this
should not interfer with the dccp retirement since this is only matching
on the dccp header.
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
The patch "netfilter: ipset: fix race condition between swap/destroy
and kernel side add/del/test", commit 28628fa9 fixes a race condition.
But the synchronize_rcu() added to the swap function unnecessarily slows
it down: it can safely be moved to destroy and use call_rcu() instead.
Eric Dumazet pointed out that simply calling the destroy functions as
rcu callback does not work: sets with timeout use garbage collectors
which need cancelling at destroy which can wait. Therefore the destroy
functions are split into two: cancelling garbage collectors safely at
executing the command received by netlink and moving the remaining
part only into the rcu callback.
Link: https://lore.kernel.org/lkml/C0829B10-EAA6-4809-874E-E1E9C05A8D84@automattic.com/
Fixes: 28628fa952 ("netfilter: ipset: fix race condition between swap/destroy and kernel side add/del/test")
Reported-by: Ale Crismani <ale.crismani@automattic.com>
Reported-by: David Wang <00107082@163.com>
Tested-by: David Wang <00107082@163.com>
Signed-off-by: Jozsef Kadlecsik <kadlec@netfilter.org>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Steps on the way to 6.6-rc1
Resolves trivial merge conflicts in:
kernel/bpf/syscall.c
net/core/dev.c
Change-Id: If35a5d19c7a7cbe958878f050d55878a7b60be9a
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
In Scenario A and B below, as the delayed INIT_ACK always changes the peer
vtag, SCTP ct with the incorrect vtag may cause packet loss.
Scenario A: INIT_ACK is delayed until the peer receives its own INIT_ACK
192.168.1.2 > 192.168.1.1: [INIT] [init tag: 1328086772]
192.168.1.1 > 192.168.1.2: [INIT] [init tag: 1414468151]
192.168.1.2 > 192.168.1.1: [INIT ACK] [init tag: 1328086772]
192.168.1.1 > 192.168.1.2: [INIT ACK] [init tag: 1650211246] *
192.168.1.2 > 192.168.1.1: [COOKIE ECHO]
192.168.1.1 > 192.168.1.2: [COOKIE ECHO]
192.168.1.2 > 192.168.1.1: [COOKIE ACK]
Scenario B: INIT_ACK is delayed until the peer completes its own handshake
192.168.1.2 > 192.168.1.1: sctp (1) [INIT] [init tag: 3922216408]
192.168.1.1 > 192.168.1.2: sctp (1) [INIT] [init tag: 144230885]
192.168.1.2 > 192.168.1.1: sctp (1) [INIT ACK] [init tag: 3922216408]
192.168.1.1 > 192.168.1.2: sctp (1) [COOKIE ECHO]
192.168.1.2 > 192.168.1.1: sctp (1) [COOKIE ACK]
192.168.1.1 > 192.168.1.2: sctp (1) [INIT ACK] [init tag: 3914796021] *
This patch fixes it as below:
In SCTP_CID_INIT processing:
- clear ct->proto.sctp.init[!dir] if ct->proto.sctp.init[dir] &&
ct->proto.sctp.init[!dir]. (Scenario E)
- set ct->proto.sctp.init[dir].
In SCTP_CID_INIT_ACK processing:
- drop it if !ct->proto.sctp.init[!dir] && ct->proto.sctp.vtag[!dir] &&
ct->proto.sctp.vtag[!dir] != ih->init_tag. (Scenario B, Scenario C)
- drop it if ct->proto.sctp.init[dir] && ct->proto.sctp.init[!dir] &&
ct->proto.sctp.vtag[!dir] != ih->init_tag. (Scenario A)
In SCTP_CID_COOKIE_ACK processing:
- clear ct->proto.sctp.init[dir] and ct->proto.sctp.init[!dir].
(Scenario D)
Also, it's important to allow the ct state to move forward with cookie_echo
and cookie_ack from the opposite dir for the collision scenarios.
There are also other Scenarios where it should allow the packet through,
addressed by the processing above:
Scenario C: new CT is created by INIT_ACK.
Scenario D: start INIT on the existing ESTABLISHED ct.
Scenario E: start INIT after the old collision on the existing ESTABLISHED
ct.
192.168.1.2 > 192.168.1.1: sctp (1) [INIT] [init tag: 3922216408]
192.168.1.1 > 192.168.1.2: sctp (1) [INIT] [init tag: 144230885]
(both side are stopped, then start new connection again in hours)
192.168.1.2 > 192.168.1.1: sctp (1) [INIT] [init tag: 242308742]
Fixes: 9fb9cbb108 ("[NETFILTER]: Add nf_conntrack subsystem.")
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
The ->cleanup callback needs to be removed, this doesn't work anymore as
the transaction mutex is already released in the ->abort function.
Just do it after a successful validation pass, this either happens
from commit or abort phases where transaction mutex is held.
Fixes: f102d66b33 ("netfilter: nf_tables: use dedicated mutex to guard transactions")
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
When adding/deleting large number of elements in one step in ipset, it can
take a reasonable amount of time and can result in soft lockup errors. The
patch 5f7b51bf09 ("netfilter: ipset: Limit the maximal range of
consecutive elements to add/delete") tried to fix it by limiting the max
elements to process at all. However it was not enough, it is still possible
that we get hung tasks. Lowering the limit is not reasonable, so the
approach in this patch is as follows: rely on the method used at resizing
sets and save the state when we reach a smaller internal batch limit,
unlock/lock and proceed from the saved state. Thus we can avoid long
continuous tasks and at the same time removed the limit to add/delete large
number of elements in one step.
The nfnl mutex is held during the whole operation which prevents one to
issue other ipset commands in parallel.
Fixes: 5f7b51bf09 ("netfilter: ipset: Limit the maximal range of consecutive elements to add/delete")
Reported-by: syzbot+9204e7399656300bf271@syzkaller.appspotmail.com
Signed-off-by: Jozsef Kadlecsik <kadlec@netfilter.org>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Add a new parameter to complement the existing 'netmask' option. The
main difference between netmask and bitmask is that bitmask takes any
arbitrary ip address as input, it does not have to be a valid netmask.
The name of the new parameter is 'bitmask'. This lets us mask out
arbitrary bits in the ip address, for example:
ipset create set1 hash:ip bitmask 255.128.255.0
ipset create set2 hash:ip,port family inet6 bitmask ffff::ff80
Signed-off-by: Vishwanath Pai <vpai@akamai.com>
Signed-off-by: Joshua Hunt <johunt@akamai.com>
Signed-off-by: Jozsef Kadlecsik <kadlec@netfilter.org>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
sparse complains about incorrect rcu usage.
Code uses the correct rcu access primitives, but the function pointers
lack rcu annotations.
Collapse all of them into a single structure, then annotate the pointer.
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Access to the hook pointers use correct helpers but the pointers lack
the needed __rcu annotation.
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Instead of exposing the four hooks individually use a sinle hook ops
structure.
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
nf_ct_put() results in a usesless indirection:
nf_ct_put -> nf_conntrack_put -> nf_conntrack_destroy -> rcu readlock +
indirect call of ct_hooks->destroy().
There are two _put helpers:
nf_ct_put and nf_conntrack_put. The latter is what should be used in
code that MUST NOT cause a linker dependency on the conntrack module
(e.g. calls from core network stack).
Everyone else should call nf_ct_put() instead.
A followup patch will convert a few nf_conntrack_put() calls to
nf_ct_put(), in particular from modules that already have a conntrack
dependency such as act_ct or even nf_conntrack itself.
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Convert nf_conn reference counting from atomic_t to refcount_t based api.
refcount_t api provides more runtime sanity checks and will warn on
certain constructs, e.g. refcount_inc() on a zero reference count, which
usually indicates use-after-free.
For this reason template allocation is changed to init the refcount to
1, the subsequenct add operations are removed.
Likewise, init_conntrack() is changed to set the initial refcount to 1
instead refcount_inc().
This is safe because the new entry is not (yet) visible to other cpus.
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Pablo Neira Ayuso says:
====================
Netfilter fixes for net
1) Protect nft_ct template with global mutex, from Pavel Skripkin.
2) Two recent commits switched inet rt and nexthop exception hashes
from jhash to siphash. If those two spots are problematic then
conntrack is affected as well, so switch voer to siphash too.
While at it, add a hard upper limit on chain lengths and reject
insertion if this is hit. Patches from Florian Westphal.
3) Fix use-after-scope in nf_socket_ipv6 reported by KASAN,
from Benjamin Hesmans.
* git://git.kernel.org/pub/scm/linux/kernel/git/pablo/nf:
netfilter: socket: icmp6: fix use-after-scope
netfilter: refuse insertion if chain has grown too large
netfilter: conntrack: switch to siphash
netfilter: conntrack: sanitize table size default settings
netfilter: nft_ct: protect nft_ct_pcpu_template_refcnt with mutex
====================
Link: https://lore.kernel.org/r/20210903163020.13741-1-pablo@netfilter.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Also add a stat counter for this that gets exported both via old /proc
interface and ctnetlink.
Assuming the old default size of 16536 buckets and max hash occupancy of
64k, this results in 128k insertions (origin+reply), so ~8 entries per
chain on average.
The revised settings in this series will result in about two entries per
bucket on average.
This allows a hard-limit ceiling of 64.
This is not tunable at the moment, but its possible to either increase
nf_conntrack_buckets or decrease nf_conntrack_max to reduce average
lengths.
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
For historical reasons x_tables still register tables by default in the
initial namespace.
Only newly created net namespaces add the hook on demand.
This means that the init_net always pays hook cost, even if no filtering
rules are added (e.g. only used inside a single netns).
Note that the hooks are added even when 'iptables -L' is called.
This is because there is no way to tell 'iptables -A' and 'iptables -L'
apart at kernel level.
The only solution would be to register the table, but delay hook
registration until the first rule gets added (or policy gets changed).
That however means that counters are not hooked either, so 'iptables -L'
would always show 0-counters even when traffic is flowing which might be
unexpected.
This keeps table and hook registration consistent with what is already done
in non-init netns: first iptables(-save) invocation registers both table
and hooks.
This applies the same solution adopted for ebtables.
All tables register a template that contains the l3 family, the name
and a constructor function that is called when the initial table has to
be added.
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
The range size of consecutive elements were not limited. Thus one could
define a huge range which may result soft lockup errors due to the long
execution time. Now the range size is limited to 2^20 entries.
Reported-by: Brad Spengler <spender@grsecurity.net>
Signed-off-by: Jozsef Kadlecsik <kadlec@netfilter.org>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Carlos Llamas
Florian Westphal
Pablo Neira Ayuso
Sun Jian
Yue Haibing
Greg Kroah-Hartman
Jakub Kicinski
Lee Jones
Jozsef Kadlecsik
Xin Long
Vishwanath Pai
Lee Jones