This nfnl subsystem allows to dump the list of all active netfiler hooks,
e.g. defrag, conntrack, nf/ip/arp/ip6tables and so on.

This helps to see what kind of features are currently enabled in
the network stack.

Sample output from nft tool using this infra:

 $ nft list hook ip input
 family ip hook input {
   +0000000010 nft_do_chain_inet [nf_tables] # nft table firewalld INPUT
   +0000000100 nf_nat_ipv4_local_in [nf_nat]
   +2147483647 ipv4_confirm [nf_conntrack]
 }
Signed-off-by: NFlorian Westphal <fw@strlen.de>
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>

Update the nfnl_info structure to add a pointer to the nfnetlink header.
This simplifies the existing codebase since this header is usually
accessed. Update existing clients to use this new field.
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>

Reported by syzbot :
BUG: sleeping function called from invalid context at include/linux/sched/mm.h:201
in_atomic(): 0, irqs_disabled(): 0, non_block: 0, pid: 26899, name: syz-executor.5
1 lock held by syz-executor.5/26899:
 #0: ffffffff8bf797a0 (rcu_read_lock){....}-{1:2}, at: nfnetlink_get_subsys net/netfilter/nfnetlink.c:148 [inline]
 #0: ffffffff8bf797a0 (rcu_read_lock){....}-{1:2}, at: nfnetlink_rcv_msg+0x1da/0x1300 net/netfilter/nfnetlink.c:226
Preemption disabled at:
[<ffffffff8917799e>] preempt_schedule_irq+0x3e/0x90 kernel/sched/core.c:5533
CPU: 1 PID: 26899 Comm: syz-executor.5 Not tainted 5.12.0-next-20210504-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:79 [inline]
 dump_stack+0x141/0x1d7 lib/dump_stack.c:120
 ___might_sleep.cold+0x1f1/0x237 kernel/sched/core.c:8338
 might_alloc include/linux/sched/mm.h:201 [inline]
 slab_pre_alloc_hook mm/slab.h:500 [inline]
 slab_alloc_node mm/slub.c:2845 [inline]
 kmem_cache_alloc_node+0x33d/0x3e0 mm/slub.c:2960
 __alloc_skb+0x20b/0x340 net/core/skbuff.c:413
 alloc_skb include/linux/skbuff.h:1107 [inline]
 nlmsg_new include/net/netlink.h:953 [inline]
 netlink_ack+0x1ed/0xaa0 net/netlink/af_netlink.c:2437
 netlink_rcv_skb+0x33d/0x420 net/netlink/af_netlink.c:2508
 nfnetlink_rcv+0x1ac/0x420 net/netfilter/nfnetlink.c:650
 netlink_unicast_kernel net/netlink/af_netlink.c:1312 [inline]
 netlink_unicast+0x533/0x7d0 net/netlink/af_netlink.c:1338
 netlink_sendmsg+0x856/0xd90 net/netlink/af_netlink.c:1927
 sock_sendmsg_nosec net/socket.c:654 [inline]
 sock_sendmsg+0xcf/0x120 net/socket.c:674
 ____sys_sendmsg+0x6e8/0x810 net/socket.c:2350
 ___sys_sendmsg+0xf3/0x170 net/socket.c:2404
 __sys_sendmsg+0xe5/0x1b0 net/socket.c:2433
 do_syscall_64+0x3a/0xb0 arch/x86/entry/common.c:47
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x4665f9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fa8a03ee188 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 000000000056bf60 RCX: 00000000004665f9
RDX: 0000000000000000 RSI: 0000000020000480 RDI: 0000000000000004
RBP: 00000000004bfce1 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056bf60
R13: 00007fffe864480f R14: 00007fa8a03ee300 R15: 0000000000022000

================================================
WARNING: lock held when returning to user space!
5.12.0-next-20210504-syzkaller #0 Tainted: G        W
------------------------------------------------
syz-executor.5/26899 is leaving the kernel with locks still held!
1 lock held by syz-executor.5/26899:
 #0: ffffffff8bf797a0 (rcu_read_lock){....}-{1:2}, at: nfnetlink_get_subsys net/netfilter/nfnetlink.c:148 [inline]
 #0: ffffffff8bf797a0 (rcu_read_lock){....}-{1:2}, at: nfnetlink_rcv_msg+0x1da/0x1300 net/netfilter/nfnetlink.c:226
------------[ cut here ]------------
WARNING: CPU: 0 PID: 26899 at kernel/rcu/tree_plugin.h:359 rcu_note_context_switch+0xfd/0x16e0 kernel/rcu/tree_plugin.h:359
Modules linked in:
CPU: 0 PID: 26899 Comm: syz-executor.5 Tainted: G        W         5.12.0-next-20210504-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:rcu_note_context_switch+0xfd/0x16e0 kernel/rcu/tree_plugin.h:359
Code: 48 89 fa 48 c1 ea 03 0f b6 14 02 48 89 f8 83 e0 07 83 c0 03 38 d0 7c 08 84 d2 0f 85 2e 0d 00 00 8b bd cc 03 00 00 85 ff 7e 02 <0f> 0b 65 48 8b 2c 25 00 f0 01 00 48 8d bd cc 03 00 00 48 b8 00 00
RSP: 0000:ffffc90002fffdb0 EFLAGS: 00010002
RAX: 0000000000000007 RBX: ffff8880b9c36080 RCX: ffffffff8dc99bac
RDX: 0000000000000000 RSI: 0000000000000008 RDI: 0000000000000001
RBP: ffff88808b9d1c80 R08: 0000000000000000 R09: ffffffff8dc96917
R10: fffffbfff1b92d22 R11: 0000000000000000 R12: 0000000000000000
R13: ffff88808b9d1c80 R14: ffff88808b9d1c80 R15: ffffc90002ff8000
FS:  00007fa8a03ee700(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f09896ed000 CR3: 0000000032070000 CR4: 00000000001526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 __schedule+0x214/0x23e0 kernel/sched/core.c:5044
 schedule+0xcf/0x270 kernel/sched/core.c:5226
 exit_to_user_mode_loop kernel/entry/common.c:162 [inline]
 exit_to_user_mode_prepare+0x13e/0x280 kernel/entry/common.c:208
 irqentry_exit_to_user_mode+0x5/0x40 kernel/entry/common.c:314
 asm_sysvec_reschedule_ipi+0x12/0x20 arch/x86/include/asm/idtentry.h:637
RIP: 0033:0x4665f9

Fixes: 50f2db9e ("netfilter: nfnetlink: consolidate callback types")
Signed-off-by: NEric Dumazet <edumazet@google.com>
Reported-by: Nsyzbot <syzkaller@googlegroups.com>
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>

Add enum nfnl_callback_type to identify the callback type to provide one
single callback.
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>

Update batch callbacks to use the nfnl_info structure. Rename one
clashing info variable to expr_info.
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>

Update rcu callbacks to use the nfnl_info structure.
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>

Add a new structure to reduce callback footprint and to facilite
extensions of the nfnetlink callback interface in the future.
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>

No need to place it in struct net, nfnetlink is a module and usage
doesn't occur in fastpath.

Also remove rcu usage:

Not a single reader of net->nfnl uses rcu accessors.

When exit_batch callbacks are executed the net namespace is already dead
so no calls to these functions are possible anymore (else we'd get NULL
deref crash too).

If the module is removed, then modules that call any of those functions
have been removed too so no calls to nfnl functions are possible either.

The nfnl and nfl_stash pointers in struct net are no longer used, they
will be removed in a followup patch to minimize changes to struct net
(causes rebuild for entire network stack).
Signed-off-by: NFlorian Westphal <fw@strlen.de>
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>

This removes the only reference of net->nfnl outside of the nfnetlink
module.  This allows to move net->nfnl to net_generic infra.
Signed-off-by: NFlorian Westphal <fw@strlen.de>
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>

If userspace does not include the trailing end of batch message, then
nfnetlink aborts the transaction. This allows to check that ruleset
updates trigger no errors.

After this patch, invoking this command from the prerouting chain:

 # nft -c add rule x y fib saddr . oif type local

fails since oif is not supported there.

This patch fixes the lack of rule validation from the abort/check path
to catch configuration errors such as the one above.

Fixes: a654de8f ("netfilter: nf_tables: fix chain dependency validation")
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>

From time to time there are lockdep reports similar to this one:

 WARNING: possible circular locking dependency detected
 ------------------------------------------------------
 000000004f61aa56 (&table[i].mutex){+.+.}, at: nfnl_lock [nfnetlink]
 but task is already holding lock:
 [..] (&net->nft.commit_mutex){+.+.}, at: nf_tables_valid_genid [nf_tables]
 which lock already depends on the new lock.
 the existing dependency chain (in reverse order) is:
 -> #1 (&net->nft.commit_mutex){+.+.}:
 [..]
        nf_tables_valid_genid+0x18/0x60 [nf_tables]
        nfnetlink_rcv_batch+0x24c/0x620 [nfnetlink]
        nfnetlink_rcv+0x110/0x140 [nfnetlink]
        netlink_unicast+0x12c/0x1e0
 [..]
        sys_sendmsg+0x18/0x40
        linux_sparc_syscall+0x34/0x44
 -> #0 (&table[i].mutex){+.+.}:
 [..]
        nfnl_lock+0x24/0x40 [nfnetlink]
        ip_set_nfnl_get_byindex+0x19c/0x280 [ip_set]
        set_match_v1_checkentry+0x14/0xc0 [xt_set]
        xt_check_match+0x238/0x260 [x_tables]
        __nft_match_init+0x160/0x180 [nft_compat]
 [..]
        sys_sendmsg+0x18/0x40
        linux_sparc_syscall+0x34/0x44
 other info that might help us debug this:
  Possible unsafe locking scenario:
        CPU0                    CPU1
        ----                    ----
   lock(&net->nft.commit_mutex);
                                lock(&table[i].mutex);
                                lock(&net->nft.commit_mutex);
   lock(&table[i].mutex);

Lockdep considers this an ABBA deadlock because the different nfnl subsys
mutexes reside in the same lockdep class, but this is a false positive.

CPU1 table[i] refers to the nftables subsys mutex, whereas CPU1 locks
the ipset subsys mutex.

Yi Che reported a similar lockdep splat, this time between ipset and
ctnetlink subsys mutexes.

Time to place them in distinct classes to avoid these warnings.
Signed-off-by: NFlorian Westphal <fw@strlen.de>
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>

Frontend callback reports EAGAIN to nfnetlink to retry a command, this
is used to signal that module autoloading is required. Unfortunately,
nlmsg_unicast() reports EAGAIN in case the receiver socket buffer gets
full, so it enters a busy-loop.

This patch updates nfnetlink_unicast() to turn EAGAIN into ENOBUFS and
to use nlmsg_unicast(). Remove the flags field in nfnetlink_unicast()
since this is always MSG_DONTWAIT in the existing code which is exactly
what nlmsg_unicast() passes to netlink_unicast() as parameter.

Fixes: 96518518 ("netfilter: add nftables")
Reported-by: NPhil Sutter <phil@nwl.cc>
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>

The user tool modinfo is used to get information on kernel modules, including a
description where it is available.

This patch adds a brief MODULE_DESCRIPTION to netfilter kernel modules
(descriptions taken from Kconfig file or code comments)
Signed-off-by: NRob Gill <rrobgill@protonmail.com>
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>

This patch introduces a list of pending module requests. This new module
list is composed of nft_module_request objects that contain the module
name and one status field that tells if the module has been already
loaded (the 'done' field).

In the first pass, from the preparation phase, the netlink command finds
that a module is missing on this list. Then, a module request is
allocated and added to this list and nft_request_module() returns
-EAGAIN. This triggers the abort path with the autoload parameter set on
from nfnetlink, request_module() is called and the module request enters
the 'done' state. Since the mutex is released when loading modules from
the abort phase, the module list is zapped so this is iteration occurs
over a local list. Therefore, the request_module() calls happen when
object lists are in consistent state (after fulling aborting the
transaction) and the commit list is empty.

On the second pass, the netlink command will find that it already tried
to load the module, so it does not request it again and
nft_request_module() returns 0. Then, there is a look up to find the
object that the command was missing. If the module was successfully
loaded, the command proceeds normally since it finds the missing object
in place, otherwise -ENOENT is reported to userspace.

This patch also updates nfnetlink to include the reason to enter the
abort phase, which is required for this new autoload module rationale.

Fixes: ec7470b8 ("netfilter: nf_tables: store transaction list locally while requesting module")
Reported-by: syzbot+29125d208b3dae9a7019@syzkaller.appspotmail.com
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>

Thomas and Juliana report a deadlock when running:

(rmmod nf_conntrack_netlink/xfrm_user)

  conntrack -e NEW -E &
  modprobe -v xfrm_user

They provided following analysis:

conntrack -e NEW -E
    netlink_bind()
        netlink_lock_table() -> increases "nl_table_users"
            nfnetlink_bind()
            # does not unlock the table as it's locked by netlink_bind()
                __request_module()
                    call_usermodehelper_exec()

This triggers "modprobe nf_conntrack_netlink" from kernel, netlink_bind()
won't return until modprobe process is done.

"modprobe xfrm_user":
    xfrm_user_init()
        register_pernet_subsys()
            -> grab pernet_ops_rwsem
                ..
                netlink_table_grab()
                    calls schedule() as "nl_table_users" is non-zero

so modprobe is blocked because netlink_bind() increased
nl_table_users while also holding pernet_ops_rwsem.

"modprobe nf_conntrack_netlink" runs and inits nf_conntrack_netlink:
    ctnetlink_init()
        register_pernet_subsys()
            -> blocks on "pernet_ops_rwsem" thanks to xfrm_user module

both modprobe processes wait on one another -- neither can make
progress.

Switch netlink_bind() to "nowait" modprobe -- this releases the netlink
table lock, which then allows both modprobe instances to complete.
Reported-by: NThomas Jarosch <thomas.jarosch@intra2net.com>
Reported-by: NJuliana Rodrigueiro <juliana.rodrigueiro@intra2net.com>
Signed-off-by: NFlorian Westphal <fw@strlen.de>
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>

We currently have two levels of strict validation:

 1) liberal (default)
     - undefined (type >= max) & NLA_UNSPEC attributes accepted
     - attribute length >= expected accepted
     - garbage at end of message accepted
 2) strict (opt-in)
     - NLA_UNSPEC attributes accepted
     - attribute length >= expected accepted

Split out parsing strictness into four different options:
 * TRAILING     - check that there's no trailing data after parsing
                  attributes (in message or nested)
 * MAXTYPE      - reject attrs > max known type
 * UNSPEC       - reject attributes with NLA_UNSPEC policy entries
 * STRICT_ATTRS - strictly validate attribute size

The default for future things should be *everything*.
The current *_strict() is a combination of TRAILING and MAXTYPE,
and is renamed to _deprecated_strict().
The current regular parsing has none of this, and is renamed to
*_parse_deprecated().

Additionally it allows us to selectively set one of the new flags
even on old policies. Notably, the UNSPEC flag could be useful in
this case, since it can be arranged (by filling in the policy) to
not be an incompatible userspace ABI change, but would then going
forward prevent forgetting attribute entries. Similar can apply
to the POLICY flag.

We end up with the following renames:
 * nla_parse           -> nla_parse_deprecated
 * nla_parse_strict    -> nla_parse_deprecated_strict
 * nlmsg_parse         -> nlmsg_parse_deprecated
 * nlmsg_parse_strict  -> nlmsg_parse_deprecated_strict
 * nla_parse_nested    -> nla_parse_nested_deprecated
 * nla_validate_nested -> nla_validate_nested_deprecated

Using spatch, of course:
    @@
    expression TB, MAX, HEAD, LEN, POL, EXT;
    @@
    -nla_parse(TB, MAX, HEAD, LEN, POL, EXT)
    +nla_parse_deprecated(TB, MAX, HEAD, LEN, POL, EXT)

    @@
    expression NLH, HDRLEN, TB, MAX, POL, EXT;
    @@
    -nlmsg_parse(NLH, HDRLEN, TB, MAX, POL, EXT)
    +nlmsg_parse_deprecated(NLH, HDRLEN, TB, MAX, POL, EXT)

    @@
    expression NLH, HDRLEN, TB, MAX, POL, EXT;
    @@
    -nlmsg_parse_strict(NLH, HDRLEN, TB, MAX, POL, EXT)
    +nlmsg_parse_deprecated_strict(NLH, HDRLEN, TB, MAX, POL, EXT)

    @@
    expression TB, MAX, NLA, POL, EXT;
    @@
    -nla_parse_nested(TB, MAX, NLA, POL, EXT)
    +nla_parse_nested_deprecated(TB, MAX, NLA, POL, EXT)

    @@
    expression START, MAX, POL, EXT;
    @@
    -nla_validate_nested(START, MAX, POL, EXT)
    +nla_validate_nested_deprecated(START, MAX, POL, EXT)

    @@
    expression NLH, HDRLEN, MAX, POL, EXT;
    @@
    -nlmsg_validate(NLH, HDRLEN, MAX, POL, EXT)
    +nlmsg_validate_deprecated(NLH, HDRLEN, MAX, POL, EXT)

For this patch, don't actually add the strict, non-renamed versions
yet so that it breaks compile if I get it wrong.

Also, while at it, make nla_validate and nla_parse go down to a
common __nla_validate_parse() function to avoid code duplication.

Ultimately, this allows us to have very strict validation for every
new caller of nla_parse()/nlmsg_parse() etc as re-introduced in the
next patch, while existing things will continue to work as is.

In effect then, this adds fully strict validation for any new command.
Signed-off-by: NJohannes Berg <johannes.berg@intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Continue to use nftnl subsys mutex to protect (un)registration of hook types,
expressions and so on, but force batch operations to do their own
locking.

This allows distinct net namespaces to perform transactions in parallel.
Signed-off-by: NFlorian Westphal <fw@strlen.de>
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>

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

always call this function, followup patch can use this to
aquire a per-netns transaction log to guard the entire batch
instead of using the nfnl susbsys mutex (which is shared among all
namespaces).
Signed-off-by: NFlorian Westphal <fw@strlen.de>
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>

We must first remove the nfnetlink protocol handler when nf_tables module
is unloaded -- we don't want userspace to submit new change requests once
we've started to tear down nft state.

Furthermore, nfnetlink must not call any subsystem function after
call_batch returned -EAGAIN.

EAGAIN means the subsys mutex was dropped, so its unlikely but possible that
nf_tables subsystem was removed due to 'rmmod nf_tables' on another cpu.

Therefore, we must abort batch completely and not move on to next part of
the batch.

Last, we can't invoke ->abort unless we've checked that the subsystem is
still registered.

Change netns exit path of nf_tables to make sure any incompleted
transaction gets removed on exit.
Signed-off-by: NFlorian Westphal <fw@strlen.de>
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>

In the quest to remove all stack VLA usage from the kernel[1], this
allocates the maximum size expected for all possible attrs and adds
sanity-checks at both registration and usage to make sure nothing
gets out of sync.

[1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@mail.gmail.comSigned-off-by: NKees Cook <keescook@chromium.org>
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>

The following ruleset:

 add table ip filter
 add chain ip filter input { type filter hook input priority 4; }
 add chain ip filter ap
 add rule ip filter input jump ap
 add rule ip filter ap masquerade

results in a panic, because the masquerade extension should be rejected
from the filter chain. The existing validation is missing a chain
dependency check when the rule is added to the non-base chain.

This patch fixes the problem by walking down the rules from the
basechains, searching for either immediate or lookup expressions, then
jumping to non-base chains and again walking down the rules to perform
the expression validation, so we make sure the full ruleset graph is
validated. This is done only once from the commit phase, in case of
problem, we abort the transaction and perform fine grain validation for
error reporting. This patch requires 00308791 ("netfilter:
nfnetlink: allow commit to fail") to achieve this behaviour.

This patch also adds a cleanup callback to nfnl batch interface to reset
the validate state from the exit path.

As a result of this patch, nf_tables_check_loops() doesn't use
->validate to check for loops, instead it just checks for immediate
expressions.
Reported-by: NTaehee Yoo <ap420073@gmail.com>
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>

abort batch processing and return so task can exit faster.
Otherwise even SIGKILL has no immediate effect.
Signed-off-by: NFlorian Westphal <fw@strlen.de>
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>

->commit() cannot fail at the moment.

Followup-patch adds kmalloc calls in the commit phase, so we'll need
to be able to handle errors.

Make it so that -EGAIN causes a full replay, and make other errors
cause the transaction to fail.

Failing is ok from a consistency point of view as long as we
perform all actions that could return an error before
we increment the generation counter and the base seq.
Signed-off-by: NFlorian Westphal <fw@strlen.de>
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>

Synchronous pernet_operations are not allowed anymore.
All are asynchronous. So, drop the structure member.
Signed-off-by: NKirill Tkhai <ktkhai@virtuozzo.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

These pernet_operations create and destroy net::nfnl
socket of NETLINK_NETFILTER code. There are no other
places, where such type the socket is created, except
these pernet_operations. It seem other pernet_operations
depending on CONFIG_NETFILTER_NETLINK send messages
to this socket. So, we mark it async.
Signed-off-by: NKirill Tkhai <ktkhai@virtuozzo.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Several reasons for this:

* Several modules maintain internal version numbers, that they print at
  boot/module load time, that are not exposed to userspace, as a
  primitive mechanism to make revision number control from the earlier
  days of Netfilter.

* IPset shows the protocol version at boot/module load time, instead
  display this via module description, as Jozsef suggested.

* Remove copyright notice at boot/module load time in two spots, the
  Netfilter codebase is a collective development effort, if we would
  have to display copyrights for each contributor at boot/module load
  time for each extensions we have, we would probably fill up logs with
  lots of useless information - from a technical standpoint.

So let's be consistent and remove them all.
Acked-by: NFlorian Westphal <fw@strlen.de>
Acked-by: NJozsef Kadlecsik <kadlec@blackhole.kfki.hu>
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>

Verify that the length of the socket buffer is sufficient to cover the
nlmsghdr structure before accessing the nlh->nlmsg_len field for further
input sanitization. If the client only supplies 1-3 bytes of data in
sk_buff, then nlh->nlmsg_len remains partially uninitialized and
contains leftover memory from the corresponding kernel allocation.
Operating on such data may result in indeterminate evaluation of the
nlmsg_len < NLMSG_HDRLEN expression.

The bug was discovered by a runtime instrumentation designed to detect
use of uninitialized memory in the kernel. The patch prevents this and
other similar tools (e.g. KMSAN) from flagging this behavior in the future.
Signed-off-by: NMateusz Jurczyk <mjurczyk@google.com>
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>

Pass down struct netlink_ext_ack as parameter to all of our nfnetlink
subsystem callbacks, so we can work on follow up patches to provide
finer grain error reporting using the new infrastructure that
2d4bc933 ("netlink: extended ACK reporting") provides.

No functional change, just pass down this new object to callbacks.
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>

This is an add-on to the previous patch that passes the extended ACK
structure where it's already available by existing genl_info or extack
function arguments.

This was done with this spatch (with some manual adjustment of
indentation):

@@
expression A, B, C, D, E;
identifier fn, info;
@@
fn(..., struct genl_info *info, ...) {
...
-nlmsg_parse(A, B, C, D, E, NULL)
+nlmsg_parse(A, B, C, D, E, info->extack)
...
}

@@
expression A, B, C, D, E;
identifier fn, info;
@@
fn(..., struct genl_info *info, ...) {
<...
-nla_parse_nested(A, B, C, D, NULL)
+nla_parse_nested(A, B, C, D, info->extack)
...>
}

@@
expression A, B, C, D, E;
identifier fn, extack;
@@
fn(..., struct netlink_ext_ack *extack, ...) {
<...
-nlmsg_parse(A, B, C, D, E, NULL)
+nlmsg_parse(A, B, C, D, E, extack)
...>
}

@@
expression A, B, C, D, E;
identifier fn, extack;
@@
fn(..., struct netlink_ext_ack *extack, ...) {
<...
-nla_parse(A, B, C, D, E, NULL)
+nla_parse(A, B, C, D, E, extack)
...>
}

@@
expression A, B, C, D, E;
identifier fn, extack;
@@
fn(..., struct netlink_ext_ack *extack, ...) {
...
-nlmsg_parse(A, B, C, D, E, NULL)
+nlmsg_parse(A, B, C, D, E, extack)
...
}

@@
expression A, B, C, D;
identifier fn, extack;
@@
fn(..., struct netlink_ext_ack *extack, ...) {
<...
-nla_parse_nested(A, B, C, D, NULL)
+nla_parse_nested(A, B, C, D, extack)
...>
}

@@
expression A, B, C, D;
identifier fn, extack;
@@
fn(..., struct netlink_ext_ack *extack, ...) {
<...
-nlmsg_validate(A, B, C, D, NULL)
+nlmsg_validate(A, B, C, D, extack)
...>
}

@@
expression A, B, C, D;
identifier fn, extack;
@@
fn(..., struct netlink_ext_ack *extack, ...) {
<...
-nla_validate(A, B, C, D, NULL)
+nla_validate(A, B, C, D, extack)
...>
}

@@
expression A, B, C;
identifier fn, extack;
@@
fn(..., struct netlink_ext_ack *extack, ...) {
<...
-nla_validate_nested(A, B, C, NULL)
+nla_validate_nested(A, B, C, extack)
...>
}
Signed-off-by: NJohannes Berg <johannes.berg@intel.com>
Reviewed-by: NJiri Pirko <jiri@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Pass the new extended ACK reporting struct to all of the generic
netlink parsing functions. For now, pass NULL in almost all callers
(except for some in the core.)
Signed-off-by: NJohannes Berg <johannes.berg@intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Add the base infrastructure and UAPI for netlink extended ACK
reporting. All "manual" calls to netlink_ack() pass NULL for now and
thus don't get extended ACK reporting.

Big thanks goes to Pablo Neira Ayuso for not only bringing up the
whole topic at netconf (again) but also coming up with the nlattr
passing trick and various other ideas.
Signed-off-by: NJohannes Berg <johannes.berg@intel.com>
Reviewed-by: NDavid Ahern <dsa@cumulusnetworks.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Remove & from function pointers to conform to the style found elsewhere
in the file. Done using the following semantic patch

// <smpl>
@r@
identifier f;
@@

f(...) { ... }
@@
identifier r.f;
@@

- &f
+ f
// </smpl>
Signed-off-by: NArushi Singhal <arushisinghal19971997@gmail.com>
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>

Otherwise, different subsys will race to access the err_list, with holding
the different nfnl_lock(subsys_id).

But this will not happen now, since ->call_batch is only implemented by
nftables, so the err_list is protected by nfnl_lock(NFNL_SUBSYS_NFTABLES).
Signed-off-by: NLiping Zhang <zlpnobody@gmail.com>
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>

This patch allows userspace to specify the generation ID that has been
used to build an incremental batch update.

If userspace specifies the generation ID in the batch message as
attribute, then nfnetlink compares it to the current generation ID so
you make sure that you work against the right baseline. Otherwise, bail
out with ERESTART so userspace knows that its changeset is stale and
needs to respin. Userspace can do this transparently at the cost of
taking slightly more time to refresh caches and rework the changeset.

This check is optional, if there is no NFNL_BATCH_GENID attribute in the
batch begin message, then no check is performed.
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>

Add new nfnetlink_rcv_skb_batch() to wrap initial nfnetlink batch
handling.
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>

Use uX types instead.
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>

This was entirely automated, using the script by Al:

  PATT='^[[:blank:]]*#[[:blank:]]*include[[:blank:]]*<asm/uaccess.h>'
  sed -i -e "s!$PATT!#include <linux/uaccess.h>!" \
        $(git grep -l "$PATT"|grep -v ^include/linux/uaccess.h)

to do the replacement at the end of the merge window.
Requested-by: NAl Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Following mmapped netlink removal this code can be simplified by
removing the alloc wrapper.
Signed-off-by: NFlorian Westphal <fw@strlen.de>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

If nlh->nlmsg_len is zero then an infinite loop is triggered because
'skb_pull(skb, msglen);' pulls zero bytes.

The calculation in nlmsg_len() underflows if 'nlh->nlmsg_len <
NLMSG_HDRLEN' which bypasses the length validation and will later
trigger an out-of-bound read.

If the length validation does fail then the malformed batch message is
copied back to userspace. However, we cannot do this because the
nlh->nlmsg_len can be invalid. This leads to an out-of-bounds read in
netlink_ack:

    [   41.455421] ==================================================================
    [   41.456431] BUG: KASAN: slab-out-of-bounds in memcpy+0x1d/0x40 at addr ffff880119e79340
    [   41.456431] Read of size 4294967280 by task a.out/987
    [   41.456431] =============================================================================
    [   41.456431] BUG kmalloc-512 (Not tainted): kasan: bad access detected
    [   41.456431] -----------------------------------------------------------------------------
    ...
    [   41.456431] Bytes b4 ffff880119e79310: 00 00 00 00 d5 03 00 00 b0 fb fe ff 00 00 00 00  ................
    [   41.456431] Object ffff880119e79320: 20 00 00 00 10 00 05 00 00 00 00 00 00 00 00 00   ...............
    [   41.456431] Object ffff880119e79330: 14 00 0a 00 01 03 fc 40 45 56 11 22 33 10 00 05  .......@EV."3...
    [   41.456431] Object ffff880119e79340: f0 ff ff ff 88 99 aa bb 00 14 00 0a 00 06 fe fb  ................
                                            ^^ start of batch nlmsg with
                                               nlmsg_len=4294967280
    ...
    [   41.456431] Memory state around the buggy address:
    [   41.456431]  ffff880119e79400: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
    [   41.456431]  ffff880119e79480: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
    [   41.456431] >ffff880119e79500: 00 00 00 00 fc fc fc fc fc fc fc fc fc fc fc fc
    [   41.456431]                                ^
    [   41.456431]  ffff880119e79580: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
    [   41.456431]  ffff880119e79600: fc fc fc fc fc fc fc fc fc fc fb fb fb fb fb fb
    [   41.456431] ==================================================================

Fix this with better validation of nlh->nlmsg_len and by setting
NFNL_BATCH_FAILURE if any batch message fails length validation.

CAP_NET_ADMIN is required to trigger the bugs.

Fixes: 9ea2aa8b ("netfilter: nfnetlink: validate nfnetlink header from batch")
Signed-off-by: NPhil Turnbull <phil.turnbull@oracle.com>
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>