netfilter: introduce accessor functions for hook entries

This allows easier future refactoring.

Signed-off-by: Aaron Conole <aconole@bytheb.org>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.or

netfilter: introduce accessor functions for hook entries

This allows easier future refactoring.

Signed-off-by: Aaron Conole <aconole@bytheb.org>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

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netfilter: handle NF_REPEAT from nf_conntrack_in()

NF_REPEAT is only needed from nf_conntrack_in() under a very specific
case required by the TCP protocol tracker, we can handle this case
without re

netfilter: handle NF_REPEAT from nf_conntrack_in()

NF_REPEAT is only needed from nf_conntrack_in() under a very specific
case required by the TCP protocol tracker, we can handle this case
without returning to the core hook path. Handling of NF_REPEAT from the
nf_reinject() is left untouched.

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

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netfilter: merge nf_iterate() into nf_hook_slow()

nf_iterate() has become rather simple, we can integrate this code into
nf_hook_slow() to reduce the amount of LOC in the core path.

However, we sti

netfilter: merge nf_iterate() into nf_hook_slow()

nf_iterate() has become rather simple, we can integrate this code into
nf_hook_slow() to reduce the amount of LOC in the core path.

However, we still need nf_iterate() around for nf_queue packet handling,
so move this function there where we only need it. I think it should be
possible to refactor nf_queue code to get rid of it definitely, but
given this is slow path anyway, let's have a look this later.

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

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netfilter: remove hook_entries field from nf_hook_state

This field is only useful for nf_queue, so store it in the
nf_queue_entry structure instead, away from the core path. Pass
hook_head to nf_hoo

netfilter: remove hook_entries field from nf_hook_state

This field is only useful for nf_queue, so store it in the
nf_queue_entry structure instead, away from the core path. Pass
hook_head to nf_hook_slow().

Since we always have a valid entry on the first iteration in
nf_iterate(), we can use 'do { ... } while (entry)' loop instead.

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

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netfilter: use switch() to handle verdict cases from nf_hook_slow()

Use switch() for verdict handling and add explicit handling for
NF_STOLEN and other non-conventional verdicts.

Signed-off-by: Pab

netfilter: use switch() to handle verdict cases from nf_hook_slow()

Use switch() for verdict handling and add explicit handling for
NF_STOLEN and other non-conventional verdicts.

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

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netfilter: deprecate NF_STOP

NF_STOP is only used by br_netfilter these days, and it can be emulated
with a combination of NF_STOLEN plus explicit call to the ->okfn()
function as Florian suggests.

netfilter: deprecate NF_STOP

NF_STOP is only used by br_netfilter these days, and it can be emulated
with a combination of NF_STOLEN plus explicit call to the ->okfn()
function as Florian suggests.

To retain binary compatibility with userspace nf_queue application, we
have to keep NF_STOP around, so libnetfilter_queue userspace userspace
applications still work if they use NF_STOP for some exotic reason.

Out of tree modules using NF_STOP would break, but we don't care about
those.

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

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netfilter: kill NF_HOOK_THRESH() and state->tresh

Patch c5136b15ea36 ("netfilter: bridge: add and use br_nf_hook_thresh")
introduced br_nf_hook_thresh().

Replace NF_HOOK_THRESH() by br_nf_hook_thre

netfilter: kill NF_HOOK_THRESH() and state->tresh

Patch c5136b15ea36 ("netfilter: bridge: add and use br_nf_hook_thresh")
introduced br_nf_hook_thresh().

Replace NF_HOOK_THRESH() by br_nf_hook_thresh from
br_nf_forward_finish(), so we have no more callers for this macro.

As a result, state->thresh and explicit thresh parameter in the hook
state structure is not required anymore. And we can get rid of
skip-hook-under-thresh loop in nf_iterate() in the core path that is
only used by br_netfilter to search for the filter hook.

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

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netfilter: remove comments that predate rcu days

We cannot block/sleep on nf_iterate because netfilter runs under rcu
read lock these days, where blocking is well-known to be illegal. So
let's remov

netfilter: remove comments that predate rcu days

We cannot block/sleep on nf_iterate because netfilter runs under rcu
read lock these days, where blocking is well-known to be illegal. So
let's remove these old comments.

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

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netfilter: get rid of useless debugging from core

This patch remove compile time code to catch inconventional verdicts.
We have better ways to handle this case these days, eg. pr_debug() but
even th

netfilter: get rid of useless debugging from core

This patch remove compile time code to catch inconventional verdicts.
We have better ways to handle this case these days, eg. pr_debug() but
even though I don't think this is useful at all, so let's remove this.

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

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netfilter: fix nf_queue handling

nf_queue handling is broken since e3b37f11e6e4 ("netfilter: replace
list_head with single linked list") for two reasons:

1) If the bypass flag is set on, there are

netfilter: fix nf_queue handling

nf_queue handling is broken since e3b37f11e6e4 ("netfilter: replace
list_head with single linked list") for two reasons:

1) If the bypass flag is set on, there are no userspace listeners and
we still have more hook entries to iterate over, then jump to the
next hook. Otherwise accept the packet. On nf_reinject() path, the
okfn() needs to be invoked.

2) We should not re-enter the same hook on packet reinjection. If the
packet is accepted, we have to skip the current hook from where the
packet was enqueued, otherwise the packets gets enqueued over and
over again.

This restores the previous list_for_each_entry_continue() behaviour
happening from nf_iterate() that was dealing with these two cases.
This patch introduces a new nf_queue() wrapper function so this fix
becomes simpler.

Fixes: e3b37f11e6e4 ("netfilter: replace list_head with single linked list")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

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netfilter: Fix slab corruption.

Use the correct pattern for singly linked list insertion and
deletion. We can also calculate the list head outside of the
mutex.

Fixes: e3b37f11e6e4 ("netfilter: re

netfilter: Fix slab corruption.

Use the correct pattern for singly linked list insertion and
deletion. We can also calculate the list head outside of the
mutex.

Fixes: e3b37f11e6e4 ("netfilter: replace list_head with single linked list")
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Reviewed-by: Aaron Conole <aconole@bytheb.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/netfilter/core.c | 108 ++++++++++++++++-----------------------------------
1 file changed, 33 insertions(+), 75 deletions(-)

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netfilter: accommodate different kconfig in nf_set_hooks_head

When CONFIG_NETFILTER_INGRESS is unset (or no), we need to handle
the request for registration properly by dropping the hook. This
rele

netfilter: accommodate different kconfig in nf_set_hooks_head

When CONFIG_NETFILTER_INGRESS is unset (or no), we need to handle
the request for registration properly by dropping the hook. This
releases the entry during the set.

Fixes: e3b37f11e6e4 ("netfilter: replace list_head with single linked list")
Signed-off-by: Aaron Conole <aconole@bytheb.org>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

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netfilter: Fix potential null pointer dereference

It's possible for nf_hook_entry_head to return NULL. If two
nf_unregister_net_hook calls happen simultaneously with a single hook
entry in the list

netfilter: Fix potential null pointer dereference

It's possible for nf_hook_entry_head to return NULL. If two
nf_unregister_net_hook calls happen simultaneously with a single hook
entry in the list, both will enter the nf_hook_mutex critical section.
The first will successfully delete the head, but the second will see
this NULL pointer and attempt to dereference.

This fix ensures that no null pointer dereference could occur when such
a condition happens.

Fixes: e3b37f11e6e4 ("netfilter: replace list_head with single linked list")
Signed-off-by: Aaron Conole <aconole@bytheb.org>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

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netfilter: replace list_head with single linked list

The netfilter hook list never uses the prev pointer, and so can be trimmed to
be a simple singly-linked list.

In addition to having a more light

netfilter: replace list_head with single linked list

The netfilter hook list never uses the prev pointer, and so can be trimmed to
be a simple singly-linked list.

In addition to having a more light weight structure for hook traversal,
struct net becomes 5568 bytes (down from 6400) and struct net_device becomes
2176 bytes (down from 2240).

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

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netfilter: Only allow sane values in nf_register_net_hook

This commit adds an upfront check for sane values to be passed when
registering a netfilter hook. This will be used in a future patch for a

netfilter: Only allow sane values in nf_register_net_hook

This commit adds an upfront check for sane values to be passed when
registering a netfilter hook. This will be used in a future patch for a
simplified hook list traversal.

Signed-off-by: Aaron Conole <aconole@bytheb.org>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

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netfilter: Remove explicit rcu_read_lock in nf_hook_slow

All of the callers of nf_hook_slow already hold the rcu_read_lock, so this
cleanup removes the recursive call. This is just a cleanup, as th

netfilter: Remove explicit rcu_read_lock in nf_hook_slow

All of the callers of nf_hook_slow already hold the rcu_read_lock, so this
cleanup removes the recursive call. This is just a cleanup, as the locking
code gracefully handles this situation.

Signed-off-by: Aaron Conole <aconole@bytheb.org>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

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net: Add _nf_(un)register_hooks symbols

Add _nf_register_hooks() and _nf_unregister_hooks() calls which allow
caller to hold RTNL mutex.

Signed-off-by: Mahesh Bandewar <maheshb@google.com>
CC: Pabl

net: Add _nf_(un)register_hooks symbols

Add _nf_register_hooks() and _nf_unregister_hooks() calls which allow
caller to hold RTNL mutex.

Signed-off-by: Mahesh Bandewar <maheshb@google.com>
CC: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

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netfilter: make nf_queue_entry_get_refs return void

We don't care if module is being unloaded anymore since hook unregister
handling will destroy queue entries using that hook.

Signed-off-by: Flori

netfilter: make nf_queue_entry_get_refs return void

We don't care if module is being unloaded anymore since hook unregister
handling will destroy queue entries using that hook.

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

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netfilter: sync with packet rx also after removing queue entries

We need to sync packet rx again after flushing the queue entries.
Otherwise, the following race could happen:

cpu1: nf_unregister_ho

netfilter: sync with packet rx also after removing queue entries

We need to sync packet rx again after flushing the queue entries.
Otherwise, the following race could happen:

cpu1: nf_unregister_hook(H) called, H unliked from lists, calls
synchronize_net() to wait for packet rx completion.

Problem is that while no new nf_queue_entry structs that use H can be
allocated, another CPU might receive a verdict from userspace just before
cpu1 calls nf_queue_nf_hook_drop to remove this entry:

cpu2: receive verdict from userspace, lock queue
cpu2: unlink nf_queue_entry struct E, which references H, from queue list
cpu1: calls nf_queue_nf_hook_drop, blocks on queue spinlock
cpu2: unlock queue
cpu1: nf_queue_nf_hook_drop drops affected queue entries
cpu2: call nf_reinject for E
cpu1: kfree(H)
cpu2: potential use-after-free for H

Cc: Eric W. Biederman <ebiederm@xmission.com>
Fixes: 085db2c04557 ("netfilter: Per network namespace netfilter hooks.")
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

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netfilter: nfnetlink_queue: rename related to nfqueue attaching conntrack info

The idea of this series of patch is to attach conntrack information to
nflog like nfqueue has already done. nfqueue con

netfilter: nfnetlink_queue: rename related to nfqueue attaching conntrack info

The idea of this series of patch is to attach conntrack information to
nflog like nfqueue has already done. nfqueue conntrack info attaching
basis is generic, rename those names to generic one, glue.

Signed-off-by: Ken-ichirou MATSUZAWA <chamas@h4.dion.ne.jp>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

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netfilter: nfnetlink_queue: get rid of nfnetlink_queue_ct.c

The original intention was to avoid dependencies between nfnetlink_queue and
conntrack without ifdef pollution. However, we can achieve th

netfilter: nfnetlink_queue: get rid of nfnetlink_queue_ct.c

The original intention was to avoid dependencies between nfnetlink_queue and
conntrack without ifdef pollution. However, we can achieve this by moving the
conntrack dependent code into ctnetlink and keep some glue code to access the
nfq_ct indirection from nfqueue.

After this patch, the nfq_ct indirection is always compiled in the netfilter
core to avoid polluting nfqueue with ifdefs. Thus, if nf_conntrack is not
compiled this results in only 8-bytes of memory waste in x86_64.

This patch also adds ctnetlink_nfqueue_seqadj() to avoid that the nf_conn
structure layout if exposed to nf_queue, which creates another dependency with
nf_conntrack at compilation time.

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

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netfilter: Pass priv instead of nf_hook_ops to netfilter hooks

Only pass the void *priv parameter out of the nf_hook_ops. That is
all any of the functions are interested now, and by limiting what i

netfilter: Pass priv instead of nf_hook_ops to netfilter hooks

Only pass the void *priv parameter out of the nf_hook_ops. That is
all any of the functions are interested now, and by limiting what is
passed it becomes simpler to change implementation details.

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

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netfilter: nf_conntrack: make nf_ct_zone_dflt built-in

Fengguang reported, that some randconfig generated the following linker
issue with nf_ct_zone_dflt object involved:

[...]
CC init/ver

netfilter: nf_conntrack: make nf_ct_zone_dflt built-in

Fengguang reported, that some randconfig generated the following linker
issue with nf_ct_zone_dflt object involved:

[...]
CC init/version.o
LD init/built-in.o
net/built-in.o: In function `ipv4_conntrack_defrag':
nf_defrag_ipv4.c:(.text+0x93e95): undefined reference to `nf_ct_zone_dflt'
net/built-in.o: In function `ipv6_defrag':
nf_defrag_ipv6_hooks.c:(.text+0xe3ffe): undefined reference to `nf_ct_zone_dflt'
make: *** [vmlinux] Error 1

Given that configurations exist where we have a built-in part, which is
accessing nf_ct_zone_dflt such as the two handlers nf_ct_defrag_user()
and nf_ct6_defrag_user(), and a part that configures nf_conntrack as a
module, we must move nf_ct_zone_dflt into a fixed, guaranteed built-in
area when netfilter is configured in general.

Therefore, split the more generic parts into a common header under
include/linux/netfilter/ and move nf_ct_zone_dflt into the built-in
section that already holds parts related to CONFIG_NF_CONNTRACK in the
netfilter core. This fixes the issue on my side.

Fixes: 308ac9143ee2 ("netfilter: nf_conntrack: push zone object into functions")
Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

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netfilter: reduce sparse warnings

bridge/netfilter/ebtables.c:290:26: warning: incorrect type in assignment (different modifiers)
-> remove __pure annotation.

ipv6/netfilter/ip6t_SYNPROXY.c:240:27:

netfilter: reduce sparse warnings

bridge/netfilter/ebtables.c:290:26: warning: incorrect type in assignment (different modifiers)
-> remove __pure annotation.

ipv6/netfilter/ip6t_SYNPROXY.c:240:27: warning: cast from restricted __be16
-> switch ntohs to htons and vice versa.

netfilter/core.c:391:30: warning: symbol 'nfq_ct_nat_hook' was not declared. Should it be static?
-> delete it, got removed

net/netfilter/nf_synproxy_core.c:221:48: warning: cast to restricted __be32
-> Use __be32 instead of u32.

Tested with objdiff that these changes do not affect generated code.

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

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netfilter: rename local nf_hook_list to hook_list

085db2c04557 ("netfilter: Per network namespace netfilter hooks.") introduced a
new nf_hook_list that is global, so let's avoid this overlap.

Signe

netfilter: rename local nf_hook_list to hook_list

085db2c04557 ("netfilter: Per network namespace netfilter hooks.") introduced a
new nf_hook_list that is global, so let's avoid this overlap.

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

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