netfilter: nf_tables: restore set elements when delete set fails

From abort path, nft_mapelem_activate() needs to restore refcounters to
the original state. Currently, it uses the set->ops->walk() to iterate
over these set elements. The existing set iterator skips inactive
elements in the next generation, this does not work from the abort path
to restore the original state since it has to skip active elements
instead (not inactive ones).

This patch moves the check for inactive elements to the set iterator
callback, then it reverses the logic for the .activate case which
needs to skip active elements.

Toggle next generation bit for elements when delete set command is
invoked and call nft_clear() from .activate (abort) path to restore the
next generation bit.

The splat below shows an object in mappings memleak:

[43929.457523] ------------[ cut here ]------------
[43929.457532] WARNING: CPU: 0 PID: 1139 at include/net/netfilter/nf_tables.h:1237 nft_setelem_data_deactivate+0xe4/0xf0 [nf_tables]
[...]
[43929.458014] RIP: 0010:nft_setelem_data_deactivate+0xe4/0xf0 [nf_tables]
[43929.458076] Code: 83 f8 01 77 ab 49 8d 7c 24 08 e8 37 5e d0 de 49 8b 6c 24 08 48 8d 7d 50 e8 e9 5c d0 de 8b 45 50 8d 50 ff 89 55 50 85 c0 75 86 <0f> 0b eb 82 0f 0b eb b3 0f 1f 40 00 90 90 90 90 90 90 90 90 90 90
[43929.458081] RSP: 0018:ffff888140f9f4b0 EFLAGS: 00010246
[43929.458086] RAX: 0000000000000000 RBX: ffff8881434f5288 RCX: dffffc0000000000
[43929.458090] RDX: 00000000ffffffff RSI: ffffffffa26d28a7 RDI: ffff88810ecc9550
[43929.458093] RBP: ffff88810ecc9500 R08: 0000000000000001 R09: ffffed10281f3e8f
[43929.458096] R10: 0000000000000003 R11: ffff0000ffff0000 R12: ffff8881434f52a0
[43929.458100] R13: ffff888140f9f5f4 R14: ffff888151c7a800 R15: 0000000000000002
[43929.458103] FS: 00007f0c687c4740(0000) GS:ffff888390800000(0000) knlGS:0000000000000000
[43929.458107] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[43929.458111] CR2: 00007f58dbe5b008 CR3: 0000000123602005 CR4: 00000000001706f0
[43929.458114] Call Trace:
[43929.458118] <TASK>
[43929.458121] ? __warn+0x9f/0x1a0
[43929.458127] ? nft_setelem_data_deactivate+0xe4/0xf0 [nf_tables]
[43929.458188] ? report_bug+0x1b1/0x1e0
[43929.458196] ? handle_bug+0x3c/0x70
[43929.458200] ? exc_invalid_op+0x17/0x40
[43929.458211] ? nft_setelem_data_deactivate+0xd7/0xf0 [nf_tables]
[43929.458271] ? nft_setelem_data_deactivate+0xe4/0xf0 [nf_tables]
[43929.458332] nft_mapelem_deactivate+0x24/0x30 [nf_tables]
[43929.458392] nft_rhash_walk+0xdd/0x180 [nf_tables]
[43929.458453] ? __pfx_nft_rhash_walk+0x10/0x10 [nf_tables]
[43929.458512] ? rb_insert_color+0x2e/0x280
[43929.458520] nft_map_deactivate+0xdc/0x1e0 [nf_tables]
[43929.458582] ? __pfx_nft_map_deactivate+0x10/0x10 [nf_tables]
[43929.458642] ? __pfx_nft_mapelem_deactivate+0x10/0x10 [nf_tables]
[43929.458701] ? __rcu_read_unlock+0x46/0x70
[43929.458709] nft_delset+0xff/0x110 [nf_tables]
[43929.458769] nft_flush_table+0x16f/0x460 [nf_tables]
[43929.458830] nf_tables_deltable+0x501/0x580 [nf_tables]

Fixes: 628bd3e49cba ("netfilter: nf_tables: drop map element references from preparation phase")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: nf_tables: missing iterator type in lookup walk

Add missing decorator type to lookup expression and tighten WARN_ON_ONCE
check in pipapo to spot earlier that this is unset.

Fixes: 29b359cf6d95 ("netfilter: nft_set_pipapo: walk over current view on netlink dump")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: nft_set_pipapo: do not free live element

Pablo reports a crash with large batches of elements with a
back-to-back add/remove pattern. Quoting Pablo:

add_elem("00000000") timeout 100 ms
...
add_elem("0000000X") timeout 100 ms
del_elem("0000000X") <---------------- delete one that was just added
...
add_elem("00005000") timeout 100 ms

1) nft_pipapo_remove() removes element 0000000X
Then, KASAN shows a splat.

Looking at the remove function there is a chance that we will drop a
rule that maps to a non-deactivated element.

Removal happens in two steps, first we do a lookup for key k and return the
to-be-removed element and mark it as inactive in the next generation.
Then, in a second step, the element gets removed from the set/map.

The _remove function does not work correctly if we have more than one
element that share the same key.

This can happen if we insert an element into a set when the set already
holds an element with same key, but the element mapping to the existing
key has timed out or is not active in the next generation.

In such case its possible that removal will unmap the wrong element.
If this happens, we will leak the non-deactivated element, it becomes
unreachable.

The element that got deactivated (and will be freed later) will
remain reachable in the set data structure, this can result in
a crash when such an element is retrieved during lookup (stale
pointer).

Add a check that the fully matching key does in fact map to the element
that we have marked as inactive in the deactivation step.
If not, we need to continue searching.

Add a bug/warn trap at the end of the function as well, the remove
function must not ever be called with an invisible/unreachable/non-existent
element.

v2: avoid uneeded temporary variable (Stefano)

Fixes: 3c4287f62044 ("nf_tables: Add set type for arbitrary concatenation of ranges")
Reported-by: Pablo Neira Ayuso <pablo@netfilter.org>
Reviewed-by: Stefano Brivio <sbrivio@redhat.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: nft_set_pipapo: walk over current view on netlink dump

The generation mask can be updated while netlink dump is in progress.
The pipapo set backend walk iterator cannot rely on it to infer what
view of the datastructure is to be used. Add notation to specify if user
wants to read/update the set.

Based on patch from Florian Westphal.

Fixes: 2b84e215f874 ("netfilter: nft_set_pipapo: .walk does not deal with generations")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: nft_set_pipapo: release elements in clone only from destroy path

Clone already always provides a current view of the lookup table, use it
to destroy the set, otherwise it is possible to destroy elements twice.

This fix requires:

212ed75dc5fb ("netfilter: nf_tables: integrate pipapo into commit protocol")

which came after:

9827a0e6e23b ("netfilter: nft_set_pipapo: release elements in clone from abort path").

Fixes: 9827a0e6e23b ("netfilter: nft_set_pipapo: release elements in clone from abort path")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: nft_set_pipapo: use GFP_KERNEL for insertions

An earlier attempt changed this to GFP_KERNEL, but the get helper is
also called for get requests from userspace, which uses rcu.

Let the caller pass in the kmalloc flags to allow insertions
to schedule if needed.

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

netfilter: nft_set_pipapo: speed up bulk element insertions

Insertions into the set are slow when we try to add many elements.
For 800k elements I get:

time nft -f pipapo_800k
real 19m34.849s
user 0m2.390s
sys 19m12.828s

perf stats:
--95.39%--nft_pipapo_insert
|--76.60%--pipapo_insert
| --76.37%--pipapo_resize
| |--72.87%--memcpy_orig
| |--1.88%--__free_pages_ok
| | --0.89%--free_tail_page_prepare
| --1.38%--kvmalloc_node
..
--18.56%--pipapo_get.isra.0
|--13.91%--__bitmap_and
|--3.01%--pipapo_refill
|--0.81%--__kmalloc
| --0.74%--__kmalloc_large_node
| --0.66%--__alloc_pages
..
--0.52%--memset_orig

So lots of time is spent in copying exising elements to make space for
the next one.

Instead of allocating to the exact size of the new rule count, allocate
extra slack to reduce alloc/copy/free overhead.

After:
time nft -f pipapo_800k
real 1m54.110s
user 0m2.515s
sys 1m51.377s

--80.46%--nft_pipapo_insert
|--73.45%--pipapo_get.isra.0
|--57.63%--__bitmap_and
| |--8.52%--pipapo_refill
|--3.45%--__kmalloc
| --3.05%--__kmalloc_large_node
| --2.58%--__alloc_pages
--2.59%--memset_orig
|--6.51%--pipapo_insert
--5.96%--pipapo_resize
|--3.63%--memcpy_orig
--2.13%--kvmalloc_node

The new @rules_alloc fills a hole, so struct size doesn't go up.
Also make it so rule removal doesn't shrink unless the free/extra space
exceeds two pages. This should be safe as well:

When a rule gets removed, the attempt to lower the allocated size is
already allowed to fail.

Exception: do exact allocations as long as set is very small (less
than one page needed).

v2: address comments from Stefano:
kdoc comment
formatting changes
remove redundant assignment
switch back to PAGE_SIZE

Link: https://lore.kernel.org/netfilter-devel/20240213141753.17ef27a6@elisabeth/
Reviewed-by: Stefano Brivio <sbrivio@redhat.com>
Signed-off-by: Florian Westphal <fw@strlen.de>

netfilter: nft_set_pipapo: shrink data structures

The set uses a mix of 'int', 'unsigned int', and size_t.

The rule count limit is NFT_PIPAPO_RULE0_MAX, which cannot
exceed INT_MAX (a few helpers use 'int' as return type).

Add a compile-time assertion for this.

Replace size_t usage in structs with unsigned int or u8 where
the stored values are smaller.

Replace signed-int arguments for lengths with 'unsigned int'
where possible.

Last, remove lt_aligned member: its set but never read.

struct nft_pipapo_match 40 bytes -> 32 bytes
struct nft_pipapo_field 56 bytes -> 32 bytes

Reviewed-by: Stefano Brivio <sbrivio@redhat.com>
Signed-off-by: Florian Westphal <fw@strlen.de>

netfilter: nft_set_pipapo: do not rely on ZERO_SIZE_PTR

pipapo relies on kmalloc(0) returning ZERO_SIZE_PTR (i.e., not NULL
but pointer is invalid).

Rework this to not call slab allocator when we'd request a 0-byte
allocation.

Reviewed-by: Stefano Brivio <sbrivio@redhat.com>
Signed-off-by: Florian Westphal <fw@strlen.de>

netfilter: nft_set_pipapo: constify lookup fn args where possible

Those get called from packet path, content must not be modified.
No functional changes intended.

Reviewed-by: Stefano Brivio <sbrivio@redhat.com>
Signed-off-by: Florian Westphal <fw@strlen.de>

netfilter: nft_set_pipapo: remove scratch_aligned pointer

use ->scratch for both avx2 and the generic implementation.

After previous change the scratch->map member is always aligned properly
for AVX2, so we can just use scratch->map in AVX2 too.

The alignoff delta is stored in the scratchpad so we can reconstruct
the correct address to free the area again.

Fixes: 7400b063969b ("nft_set_pipapo: Introduce AVX2-based lookup implementation")
Reviewed-by: Stefano Brivio <sbrivio@redhat.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: nft_set_pipapo: add helper to release pcpu scratch area

After next patch simple kfree() is not enough anymore, so add
a helper for it.

Reviewed-by: Stefano Brivio <sbrivio@redhat.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: nft_set_pipapo: store index in scratch maps

Pipapo needs a scratchpad area to keep state during matching.
This state can be large and thus cannot reside on stack.

Each set preallocates percpu areas for this.

On each match stage, one scratchpad half starts with all-zero and the other
is inited to all-ones.

At the end of each stage, the half that starts with all-ones is
always zero. Before next field is tested, pointers to the two halves
are swapped, i.e. resmap pointer turns into fill pointer and vice versa.

After the last field has been processed, pipapo stashes the
index toggle in a percpu variable, with assumption that next packet
will start with the all-zero half and sets all bits in the other to 1.

This isn't reliable.

There can be multiple sets and we can't be sure that the upper
and lower half of all set scratch map is always in sync (lookups
can be conditional), so one set might have swapped, but other might
not have been queried.

Thus we need to keep the index per-set-and-cpu, just like the
scratchpad.

Note that this bug fix is incomplete, there is a related issue.

avx2 and normal implementation might use slightly different areas of the
map array space due to the avx2 alignment requirements, so
m->scratch (generic/fallback implementation) and ->scratch_aligned
(avx) may partially overlap. scratch and scratch_aligned are not distinct
objects, the latter is just the aligned address of the former.

After this change, write to scratch_align->map_index may write to
scratch->map, so this issue becomes more prominent, we can set to 1
a bit in the supposedly-all-zero area of scratch->map[].

A followup patch will remove the scratch_aligned and makes generic and
avx code use the same (aligned) area.

Its done in a separate change to ease review.

Fixes: 3c4287f62044 ("nf_tables: Add set type for arbitrary concatenation of ranges")
Reviewed-by: Stefano Brivio <sbrivio@redhat.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: nf_tables: use timestamp to check for set element timeout

Add a timestamp field at the beginning of the transaction, store it
in the nftables per-netns area.

Update set backend .insert, .deactivate and sync gc path to use the
timestamp, this avoids that an element expires while control plane
transaction is still unfinished.

.lookup and .update, which are used from packet path, still use the
current time to check if the element has expired. And .get path and dump
also since this runs lockless under rcu read size lock. Then, there is
async gc which also needs to check the current time since it runs
asynchronously from a workqueue.

Fixes: c3e1b005ed1c ("netfilter: nf_tables: add set element timeout support")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: nft_set_pipapo: remove static in nft_pipapo_get()

This has slipped through when reducing memory footprint for set
elements, remove it.

Fixes: 9dad402b89e8 ("netfilter: nf_tables: expose opaque set element as struct nft_elem_priv")
Reported-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: nft_set_pipapo: prefer gfp_kernel allocation

No need to use GFP_ATOMIC here.

Fixes: f6c383b8c31a ("netfilter: nf_tables: adapt set backend to use GC transaction API")
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: nft_set_pipapo: skip inactive elements during set walk

Otherwise set elements can be deactivated twice which will cause a crash.

Reported-by: Xingyuan Mo <hdthky0@gmail.com>
Fixes: 3c4287f62044 ("nf_tables: Add set type for arbitrary concatenation of ranges")
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: nf_tables: set->ops->insert returns opaque set element in case of EEXIST

Return struct nft_elem_priv instead of struct nft_set_ext for
consistency with ("netfilter: nf_tables: expose opaque set element as
struct nft_elem_priv") and to prepare the introduction of element
timeout updates from control path.

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

netfilter: nf_tables: shrink memory consumption of set elements

Instead of copying struct nft_set_elem into struct nft_trans_elem, store
the pointer to the opaque set element object in the transaction. Adapt
set backend API (and set backend implementations) to take the pointer to
opaque set element representation whenever required.

This patch deconstifies .remove() and .activate() set backend API since
these modify the set element opaque object. And it also constify
nft_set_elem_ext() this provides access to the nft_set_ext struct
without updating the object.

According to pahole on x86_64, this patch shrinks struct nft_trans_elem
size from 216 to 24 bytes.

This patch also reduces stack memory consumption by removing the
template struct nft_set_elem object, using the opaque set element object
instead such as from the set iterator API, catchall elements and the get
element command.

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

netfilter: nf_tables: expose opaque set element as struct nft_elem_priv

Add placeholder structure and place it at the beginning of each struct
nft_*_elem for each existing set backend, instead of exposing elements
as void type to the frontend which defeats compiler type checks. Use
this pointer to this new type to replace void *.

This patch updates the following set backend API to use this new struct
nft_elem_priv placeholder structure:

- update
- deactivate
- flush
- get

as well as the following helper functions:

- nft_set_elem_ext()
- nft_set_elem_init()
- nft_set_elem_destroy()
- nf_tables_set_elem_destroy()

This patch adds nft_elem_priv_cast() to cast struct nft_elem_priv to
native element representation from the corresponding set backend.
BUILD_BUG_ON() makes sure this .priv placeholder is always at the top
of the opaque set element representation.

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

netfilter: nf_tables: set backend .flush always succeeds

.flush is always successful since this results from iterating over the
set elements to toggle mark the element as inactive in the next
generation.

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

netfilter: nft_set_pipapo: no need to call pipapo_deactivate() from flush

Use the element object that is already offered instead.

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

netfilter: nf_tables: de-constify set commit ops function argument

The set backend using this already has to work around this via ugly
cast, don't spread this pattern.

Signed-off-by: Florian Westphal <fw@strlen.de>

netfilter: nft_set_pipapo: stop GC iteration if GC transaction allocation fails

nft_trans_gc_queue_sync() enqueues the GC transaction and it allocates a
new one. If this allocation fails, then stop this GC sync run and retry
later.

Fixes: 5f68718b34a5 ("netfilter: nf_tables: GC transaction API to avoid race with control plane")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: nft_set_pipapo: call nft_trans_gc_queue_sync() in catchall GC

pipapo needs to enqueue GC transactions for catchall elements through
nft_trans_gc_queue_sync(). Add nft_trans_gc_catchall_sync() and
nft_trans_gc_catchall_async() to handle GC transaction queueing
accordingly.

Fixes: 5f68718b34a5 ("netfilter: nf_tables: GC transaction API to avoid race with control plane")
Fixes: f6c383b8c31a ("netfilter: nf_tables: adapt set backend to use GC transaction API")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: nf_tables: fix out of memory error handling

Several instances of pipapo_resize() don't propagate allocation failures,
this causes a crash when fault injection is enabled for gfp_kernel slabs.

Fixes: 3c4287f62044 ("nf_tables: Add set type for arbitrary concatenation of ranges")
Signed-off-by: Florian Westphal <fw@strlen.de>
Reviewed-by: Stefano Brivio <sbrivio@redhat.com>

netfilter: nf_tables: don't fail inserts if duplicate has expired

nftables selftests fail:
run-tests.sh testcases/sets/0044interval_overlap_0
Expected: 0-2 . 0-3, got:
W: [FAILED] ./testcases/sets/0044interval_overlap_0: got 1

Insertion must ignore duplicate but expired entries.

Moreover, there is a strange asymmetry in nft_pipapo_activate:

It refetches the current element, whereas the other ->activate callbacks
(bitmap, hash, rhash, rbtree) use elem->priv.
Same for .remove: other set implementations take elem->priv,
nft_pipapo_remove fetches elem->priv, then does a relookup,
remove this.

I suspect this was the reason for the change that prompted the
removal of the expired check in pipapo_get() in the first place,
but skipping exired elements there makes no sense to me, this helper
is used for normal get requests, insertions (duplicate check)
and deactivate callback.

In first two cases expired elements must be skipped.

For ->deactivate(), this gets called for DELSETELEM, so it
seems to me that expired elements should be skipped as well, i.e.
delete request should fail with -ENOENT error.

Fixes: 24138933b97b ("netfilter: nf_tables: don't skip expired elements during walk")
Signed-off-by: Florian Westphal <fw@strlen.de>

netfilter: nf_tables: fix kdoc warnings after gc rework

Jakub Kicinski says:
We've got some new kdoc warnings here:
net/netfilter/nft_set_pipapo.c:1557: warning: Function parameter or member '_set' not described in 'pipapo_gc'
net/netfilter/nft_set_pipapo.c:1557: warning: Excess function parameter 'set' description in 'pipapo_gc'
include/net/netfilter/nf_tables.h:577: warning: Function parameter or member 'dead' not described in 'nft_set'

Fixes: 5f68718b34a5 ("netfilter: nf_tables: GC transaction API to avoid race with control plane")
Fixes: f6c383b8c31a ("netfilter: nf_tables: adapt set backend to use GC transaction API")
Reported-by: Jakub Kicinski <kuba@kernel.org>
Closes: https://lore.kernel.org/netdev/20230810104638.746e46f1@kernel.org/
Signed-off-by: Florian Westphal <fw@strlen.de>

netfilter: nf_tables: fix false-positive lockdep splat

->abort invocation may cause splat on debug kernels:

WARNING: suspicious RCU usage
net/netfilter/nft_set_pipapo.c:1697 suspicious rcu_dereference_check() usage!
[..]
rcu_scheduler_active = 2, debug_locks = 1
1 lock held by nft/133554: [..] (nft_net->commit_mutex){+.+.}-{3:3}, at: nf_tables_valid_genid
[..]
lockdep_rcu_suspicious+0x1ad/0x260
nft_pipapo_abort+0x145/0x180
__nf_tables_abort+0x5359/0x63d0
nf_tables_abort+0x24/0x40
nfnetlink_rcv+0x1a0a/0x22c0
netlink_unicast+0x73c/0x900
netlink_sendmsg+0x7f0/0xc20
____sys_sendmsg+0x48d/0x760

Transaction mutex is held, so parallel updates are not possible.
Switch to _protected and check mutex is held for lockdep enabled builds.

Fixes: 212ed75dc5fb ("netfilter: nf_tables: integrate pipapo into commit protocol")
Signed-off-by: Florian Westphal <fw@strlen.de>

netfilter: nf_tables: adapt set backend to use GC transaction API

Use the GC transaction API to replace the old and buggy gc API and the
busy mark approach.

No set elements are removed from async garbage collection anymore,
instead the _DEAD bit is set on so the set element is not visible from
lookup path anymore. Async GC enqueues transaction work that might be
aborted and retried later.

rbtree and pipapo set backends does not set on the _DEAD bit from the
sync GC path since this runs in control plane path where mutex is held.
In this case, set elements are deactivated, removed and then released
via RCU callback, sync GC never fails.

Fixes: 3c4287f62044 ("nf_tables: Add set type for arbitrary concatenation of ranges")
Fixes: 8d8540c4f5e0 ("netfilter: nft_set_rbtree: add timeout support")
Fixes: 9d0982927e79 ("netfilter: nft_hash: add support for timeouts")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: nf_tables: don't skip expired elements during walk

There is an asymmetry between commit/abort and preparation phase if the
following conditions are met:

1. set is a verdict map ("1.2.3.4 : jump foo")
2. timeouts are enabled

In this case, following sequence is problematic:

1. element E in set S refers to chain C
2. userspace requests removal of set S
3. kernel does a set walk to decrement chain->use count for all elements
from preparation phase
4. kernel does another set walk to remove elements from the commit phase
(or another walk to do a chain->use increment for all elements from
abort phase)

If E has already expired in 1), it will be ignored during list walk, so its use count
won't have been changed.

Then, when set is culled, ->destroy callback will zap the element via
nf_tables_set_elem_destroy(), but this function is only safe for
elements that have been deactivated earlier from the preparation phase:
lack of earlier deactivate removes the element but leaks the chain use
count, which results in a WARN splat when the chain gets removed later,
plus a leak of the nft_chain structure.

Update pipapo_get() not to skip expired elements, otherwise flush
command reports bogus ENOENT errors.

Fixes: 3c4287f62044 ("nf_tables: Add set type for arbitrary concatenation of ranges")
Fixes: 8d8540c4f5e0 ("netfilter: nft_set_rbtree: add timeout support")
Fixes: 9d0982927e79 ("netfilter: nft_hash: add support for timeouts")
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: nft_set_pipapo: fix improper element removal

end key should be equal to start unless NFT_SET_EXT_KEY_END is present.

Its possible to add elements that only have a start key
("{ 1.0.0.0 . 2.0.0.0 }") without an internval end.

Insertion treats this via:

if (nft_set_ext_exists(ext, NFT_SET_EXT_KEY_END))
end = (const u8 *)nft_set_ext_key_end(ext)->data;
else
end = start;

but removal side always uses nft_set_ext_key_end().
This is wrong and leads to garbage remaining in the set after removal
next lookup/insert attempt will give:

BUG: KASAN: slab-use-after-free in pipapo_get+0x8eb/0xb90
Read of size 1 at addr ffff888100d50586 by task nft-pipapo_uaf_/1399
Call Trace:
kasan_report+0x105/0x140
pipapo_get+0x8eb/0xb90
nft_pipapo_insert+0x1dc/0x1710
nf_tables_newsetelem+0x31f5/0x4e00
..

Fixes: 3c4287f62044 ("nf_tables: Add set type for arbitrary concatenation of ranges")
Reported-by: lonial con <kongln9170@gmail.com>
Reviewed-by: Stefano Brivio <sbrivio@redhat.com>
Signed-off-by: Florian Westphal <fw@strlen.de>

netfilter: nft_set_pipapo: .walk does not deal with generations

The .walk callback iterates over the current active set, but it might be
useful to iterate over the next generation set. Use the generation mask
to determine what set view (either current or next generation) is use
for the walk iteration.

Fixes: 3c4287f62044 ("nf_tables: Add set type for arbitrary concatenation of ranges")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: nf_tables: drop map element references from preparation phase

set .destroy callback releases the references to other objects in maps.
This is very late and it results in spurious EBUSY errors. Drop refcount
from the preparation phase instead, update set backend not to drop
reference counter from set .destroy path.

Exceptions: NFT_TRANS_PREPARE_ERROR does not require to drop the
reference counter because the transaction abort path releases the map
references for each element since the set is unbound. The abort path
also deals with releasing reference counter for new elements added to
unbound sets.

Fixes: 591054469b3e ("netfilter: nf_tables: revisit chain/object refcounting from elements")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: nf_tables: integrate pipapo into commit protocol

The pipapo set backend follows copy-on-update approach, maintaining one
clone of the existing datastructure that is being updated. The clone
and current datastructures are swapped via rcu from the commit step.

The existing integration with the commit protocol is flawed because
there is no operation to clean up the clone if the transaction is
aborted. Moreover, the datastructure swap happens on set element
activation.

This patch adds two new operations for sets: commit and abort, these new
operations are invoked from the commit and abort steps, after the
transactions have been digested, and it updates the pipapo set backend
to use it.

This patch adds a new ->pending_update field to sets to maintain a list
of sets that require this new commit and abort operations.

Fixes: 3c4287f62044 ("nf_tables: Add set type for arbitrary concatenation of ranges")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: nft_set_pipapo: Use struct_size()

Use struct_size() instead of hand writing it.
This is less verbose and more informative.

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Signed-off-by: Florian Westphal <fw@strlen.de>

netfilter: nft_set_pipapo: Actually validate intervals in fields after the first one

Embarrassingly, nft_pipapo_insert() checked for interval validity in
the first field only.

The start_p and end_p pointers were reset to key data from the first
field at every iteration of the loop which was supposed to go over
the set fields.

Fixes: 3c4287f62044 ("nf_tables: Add set type for arbitrary concatenation of ranges")
Reported-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: nft_set_pipapo: release elements in clone from abort path

New elements that reside in the clone are not released in case that the
transaction is aborted.

[16302.231754] ------------[ cut here ]------------
[16302.231756] WARNING: CPU: 0 PID: 100509 at net/netfilter/nf_tables_api.c:1864 nf_tables_chain_destroy+0x26/0x127 [nf_tables]
[...]
[16302.231882] CPU: 0 PID: 100509 Comm: nft Tainted: G W 5.19.0-rc3+ #155
[...]
[16302.231887] RIP: 0010:nf_tables_chain_destroy+0x26/0x127 [nf_tables]
[16302.231899] Code: f3 fe ff ff 41 55 41 54 55 53 48 8b 6f 10 48 89 fb 48 c7 c7 82 96 d9 a0 8b 55 50 48 8b 75 58 e8 de f5 92 e0 83 7d 50 00 74 09 <0f> 0b 5b 5d 41 5c 41 5d c3 4c 8b 65 00 48 8b 7d 08 49 39 fc 74 05
[...]
[16302.231917] Call Trace:
[16302.231919] <TASK>
[16302.231921] __nf_tables_abort.cold+0x23/0x28 [nf_tables]
[16302.231934] nf_tables_abort+0x30/0x50 [nf_tables]
[16302.231946] nfnetlink_rcv_batch+0x41a/0x840 [nfnetlink]
[16302.231952] ? __nla_validate_parse+0x48/0x190
[16302.231959] nfnetlink_rcv+0x110/0x129 [nfnetlink]
[16302.231963] netlink_unicast+0x211/0x340
[16302.231969] netlink_sendmsg+0x21e/0x460

Add nft_set_pipapo_match_destroy() helper function to release the
elements in the lookup tables.

Stefano Brivio says: "We additionally look for elements pointers in the
cloned matching data if priv->dirty is set, because that means that
cloned data might point to additional elements we did not commit to the
working copy yet (such as the abort path case, but perhaps not limited
to it)."

Fixes: 3c4287f62044 ("nf_tables: Add set type for arbitrary concatenation of ranges")
Reviewed-by: Stefano Brivio <sbrivio@redhat.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: nft_set_pipapo: allocate pcpu scratch maps on clone

This is needed in case a new transaction is made that doesn't insert any
new elements into an already existing set.

Else, after second 'nft -f ruleset.txt', lookups in such a set will fail
because ->lookup() encounters raw_cpu_ptr(m->scratch) == NULL.

For the initial rule load, insertion of elements takes care of the
allocation, but for rule reloads this isn't guaranteed: we might not
have additions to the set.

Fixes: 3c4287f62044a90e ("nf_tables: Add set type for arbitrary concatenation of ranges")
Reported-by: etkaar <lists.netfilter.org@prvy.eu>
Signed-off-by: Florian Westphal <fw@strlen.de>
Reviewed-by: Stefano Brivio <sbrivio@redhat.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: nft_set_pipapo_avx2: Add irq_fpu_usable() check, fallback to non-AVX2 version

Arturo reported this backtrace:

[709732.358791] WARNING: CPU: 3 PID: 456 at arch/x86/kernel/fpu/core.c:128 kernel_fpu_begin_mask+0xae/0xe0
[709732.358793] Modules linked in: binfmt_misc nft_nat nft_chain_nat nf_nat nft_counter nft_ct nf_tables nf_conntrack_netlink nfnetlink 8021q garp stp mrp llc vrf intel_rapl_msr intel_rapl_common skx_edac nfit libnvdimm ipmi_ssif x86_pkg_temp_thermal intel_powerclamp coretemp crc32_pclmul mgag200 ghash_clmulni_intel drm_kms_helper cec aesni_intel drm libaes crypto_simd cryptd glue_helper mei_me dell_smbios iTCO_wdt evdev intel_pmc_bxt iTCO_vendor_support dcdbas pcspkr rapl dell_wmi_descriptor wmi_bmof sg i2c_algo_bit watchdog mei acpi_ipmi ipmi_si button nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 ipmi_devintf ipmi_msghandler ip_tables x_tables autofs4 ext4 crc16 mbcache jbd2 dm_mod raid10 raid456 async_raid6_recov async_memcpy async_pq async_xor async_tx xor sd_mod t10_pi crc_t10dif crct10dif_generic raid6_pq libcrc32c crc32c_generic raid1 raid0 multipath linear md_mod ahci libahci tg3 libata xhci_pci libphy xhci_hcd ptp usbcore crct10dif_pclmul crct10dif_common bnxt_en crc32c_intel scsi_mod
[709732.358941] pps_core i2c_i801 lpc_ich i2c_smbus wmi usb_common
[709732.358957] CPU: 3 PID: 456 Comm: jbd2/dm-0-8 Not tainted 5.10.0-0.bpo.5-amd64 #1 Debian 5.10.24-1~bpo10+1
[709732.358959] Hardware name: Dell Inc. PowerEdge R440/04JN2K, BIOS 2.9.3 09/23/2020
[709732.358964] RIP: 0010:kernel_fpu_begin_mask+0xae/0xe0
[709732.358969] Code: ae 54 24 04 83 e3 01 75 38 48 8b 44 24 08 65 48 33 04 25 28 00 00 00 75 33 48 83 c4 10 5b c3 65 8a 05 5e 21 5e 76 84 c0 74 92 <0f> 0b eb 8e f0 80 4f 01 40 48 81 c7 00 14 00 00 e8 dd fb ff ff eb
[709732.358972] RSP: 0018:ffffbb9700304740 EFLAGS: 00010202
[709732.358976] RAX: 0000000000000001 RBX: 0000000000000003 RCX: 0000000000000001
[709732.358979] RDX: ffffbb9700304970 RSI: ffff922fe1952e00 RDI: 0000000000000003
[709732.358981] RBP: ffffbb9700304970 R08: ffff922fc868a600 R09: ffff922fc711e462
[709732.358984] R10: 000000000000005f R11: ffff922ff0b27180 R12: ffffbb9700304960
[709732.358987] R13: ffffbb9700304b08 R14: ffff922fc664b6c8 R15: ffff922fc664b660
[709732.358990] FS: 0000000000000000(0000) GS:ffff92371fec0000(0000) knlGS:0000000000000000
[709732.358993] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[709732.358996] CR2: 0000557a6655bdd0 CR3: 000000026020a001 CR4: 00000000007706e0
[709732.358999] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[709732.359001] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[709732.359003] PKRU: 55555554
[709732.359005] Call Trace:
[709732.359009] <IRQ>
[709732.359035] nft_pipapo_avx2_lookup+0x4c/0x1cba [nf_tables]
[709732.359046] ? sched_clock+0x5/0x10
[709732.359054] ? sched_clock_cpu+0xc/0xb0
[709732.359061] ? record_times+0x16/0x80
[709732.359068] ? plist_add+0xc1/0x100
[709732.359073] ? psi_group_change+0x47/0x230
[709732.359079] ? skb_clone+0x4d/0xb0
[709732.359085] ? enqueue_task_rt+0x22b/0x310
[709732.359098] ? bnxt_start_xmit+0x1e8/0xaf0 [bnxt_en]
[709732.359102] ? packet_rcv+0x40/0x4a0
[709732.359121] nft_lookup_eval+0x59/0x160 [nf_tables]
[709732.359133] nft_do_chain+0x350/0x500 [nf_tables]
[709732.359152] ? nft_lookup_eval+0x59/0x160 [nf_tables]
[709732.359163] ? nft_do_chain+0x364/0x500 [nf_tables]
[709732.359172] ? fib4_rule_action+0x6d/0x80
[709732.359178] ? fib_rules_lookup+0x107/0x250
[709732.359184] nft_nat_do_chain+0x8a/0xf2 [nft_chain_nat]
[709732.359193] nf_nat_inet_fn+0xea/0x210 [nf_nat]
[709732.359202] nf_nat_ipv4_out+0x14/0xa0 [nf_nat]
[709732.359207] nf_hook_slow+0x44/0xc0
[709732.359214] ip_output+0xd2/0x100
[709732.359221] ? __ip_finish_output+0x210/0x210
[709732.359226] ip_forward+0x37d/0x4a0
[709732.359232] ? ip4_key_hashfn+0xb0/0xb0
[709732.359238] ip_sublist_rcv_finish+0x4f/0x60
[709732.359243] ip_sublist_rcv+0x196/0x220
[709732.359250] ? ip_rcv_finish_core.isra.22+0x400/0x400
[709732.359255] ip_list_rcv+0x137/0x160
[709732.359264] __netif_receive_skb_list_core+0x29b/0x2c0
[709732.359272] netif_receive_skb_list_internal+0x1a6/0x2d0
[709732.359280] gro_normal_list.part.156+0x19/0x40
[709732.359286] napi_complete_done+0x67/0x170
[709732.359298] bnxt_poll+0x105/0x190 [bnxt_en]
[709732.359304] ? irqentry_exit+0x29/0x30
[709732.359309] ? asm_common_interrupt+0x1e/0x40
[709732.359315] net_rx_action+0x144/0x3c0
[709732.359322] __do_softirq+0xd5/0x29c
[709732.359329] asm_call_irq_on_stack+0xf/0x20
[709732.359332] </IRQ>
[709732.359339] do_softirq_own_stack+0x37/0x40
[709732.359346] irq_exit_rcu+0x9d/0xa0
[709732.359353] common_interrupt+0x78/0x130
[709732.359358] asm_common_interrupt+0x1e/0x40
[709732.359366] RIP: 0010:crc_41+0x0/0x1e [crc32c_intel]
[709732.359370] Code: ff ff f2 4d 0f 38 f1 93 a8 fe ff ff f2 4c 0f 38 f1 81 b0 fe ff ff f2 4c 0f 38 f1 8a b0 fe ff ff f2 4d 0f 38 f1 93 b0 fe ff ff <f2> 4c 0f 38 f1 81 b8 fe ff ff f2 4c 0f 38 f1 8a b8 fe ff ff f2 4d
[709732.359373] RSP: 0018:ffffbb97008dfcd0 EFLAGS: 00000246
[709732.359377] RAX: 000000000000002a RBX: 0000000000000400 RCX: ffff922fc591dd50
[709732.359379] RDX: ffff922fc591dea0 RSI: 0000000000000a14 RDI: ffffffffc00dddc0
[709732.359382] RBP: 0000000000001000 R08: 000000000342d8c3 R09: 0000000000000000
[709732.359384] R10: 0000000000000000 R11: ffff922fc591dff0 R12: ffffbb97008dfe58
[709732.359386] R13: 000000000000000a R14: ffff922fd2b91e80 R15: ffff922fef83fe38
[709732.359395] ? crc_43+0x1e/0x1e [crc32c_intel]
[709732.359403] ? crc32c_pcl_intel_update+0x97/0xb0 [crc32c_intel]
[709732.359419] ? jbd2_journal_commit_transaction+0xaec/0x1a30 [jbd2]
[709732.359425] ? irq_exit_rcu+0x3e/0xa0
[709732.359447] ? kjournald2+0xbd/0x270 [jbd2]
[709732.359454] ? finish_wait+0x80/0x80
[709732.359470] ? commit_timeout+0x10/0x10 [jbd2]
[709732.359476] ? kthread+0x116/0x130
[709732.359481] ? kthread_park+0x80/0x80
[709732.359488] ? ret_from_fork+0x1f/0x30
[709732.359494] ---[ end trace 081a19978e5f09f5 ]---

that is, nft_pipapo_avx2_lookup() uses the FPU running from a softirq
that interrupted a kthread, also using the FPU.

That's exactly the reason why irq_fpu_usable() is there: use it, and
if we can't use the FPU, fall back to the non-AVX2 version of the
lookup operation, i.e. nft_pipapo_lookup().

Reported-by: Arturo Borrero Gonzalez <arturo@netfilter.org>
Cc: <stable@vger.kernel.org> # 5.6.x
Fixes: 7400b063969b ("nft_set_pipapo: Introduce AVX2-based lookup implementation")
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: nftables: add catch-all set element support

This patch extends the set infrastructure to add a special catch-all set
element. If the lookup fails to find an element (or range) in the set,
then the catch-all element is selected. Users can specify a mapping,
expression(s) and timeout to be attached to the catch-all element.

This patch adds a catchall list to the set, this list might contain more
than one single catch-all element (e.g. in case that the catch-all
element is removed and a new one is added in the same transaction).
However, most of the time, there will be either one element or no
elements at all in this list.

The catch-all element is identified via NFT_SET_ELEM_CATCHALL flag and
such special element has no NFTA_SET_ELEM_KEY attribute. There is a new
nft_set_elem_catchall object that stores a reference to the dummy
catch-all element (catchall->elem) whose layout is the same of the set
element type to reuse the existing set element codebase.

The set size does not apply to the catch-all element, users can define a
catch-all element even if the set is full.

The check for valid set element flags hava been updates to report
EOPNOTSUPP in case userspace requests flags that are not supported when
using new userspace nftables and old kernel.

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

netfilter: Replace HTTP links with HTTPS ones

Rationale:
Reduces attack surface on kernel devs opening the links for MITM
as HTTPS traffic is much harder to manipulate.

Deterministic algorithm:
For each file:
If not .svg:
For each line:
If doesn't contain `\bxmlns\b`:
For each link, `\bhttp://[^# \t\r\n]*(?:\w|/)`:
If neither `\bgnu\.org/license`, nor `\bmozilla\.org/MPL\b`:
If both the HTTP and HTTPS versions
return 200 OK and serve the same content:
Replace HTTP with HTTPS.

Signed-off-by: Alexander A. Klimov <grandmaster@al2klimov.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

net: netfilter: kerneldoc fixes

Simple fixes which require no deep knowledge of the code.

Cc: Pablo Neira Ayuso <pablo@netfilter.org>
Cc: Jozsef Kadlecsik <kadlec@netfilter.org>
Cc: Florian Westphal <fw@strlen.de>
Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

netfilter: nft_set_pipapo: Drop useless assignment of scratch map index on insert

In nft_pipapo_insert(), we need to reallocate scratch maps that will
be used for matching by lookup functions, if they have never been
allocated or if the bucket size changes as a result of the insertion.

As pipapo_realloc_scratch() provides a pair of fresh, zeroed out
maps, there's no need to select a particular one after reallocation.

Other than being useless, the existing assignment was also troubled
by the fact that the index was set only on the CPU performing the
actual insertion, as spotted by Florian.

Simply drop the assignment.

Reported-by: Florian Westphal <fw@strlen.de>
Fixes: 3c4287f62044 ("nf_tables: Add set type for arbitrary concatenation of ranges")
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: nft_set_pipapo: Disable preemption before getting per-CPU pointer

The lkp kernel test robot reports, with CONFIG_DEBUG_PREEMPT enabled:

[ 165.316525] BUG: using smp_processor_id() in preemptible [00000000] code: nft/6247
[ 165.319547] caller is nft_pipapo_insert+0x464/0x610 [nf_tables]
[ 165.321846] CPU: 1 PID: 6247 Comm: nft Not tainted 5.6.0-rc5-01595-ge32a4dc6512ce3 #1
[ 165.332128] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014
[ 165.334892] Call Trace:
[ 165.336435] dump_stack+0x8f/0xcb
[ 165.338128] debug_smp_processor_id+0xb2/0xc0
[ 165.340117] nft_pipapo_insert+0x464/0x610 [nf_tables]
[ 165.342290] ? nft_trans_alloc_gfp+0x1c/0x60 [nf_tables]
[ 165.344420] ? rcu_read_lock_sched_held+0x52/0x80
[ 165.346460] ? nft_trans_alloc_gfp+0x1c/0x60 [nf_tables]
[ 165.348543] ? __mmu_interval_notifier_insert+0xa0/0xf0
[ 165.350629] nft_add_set_elem+0x5ff/0xa90 [nf_tables]
[ 165.352699] ? __lock_acquire+0x241/0x1400
[ 165.354573] ? __lock_acquire+0x241/0x1400
[ 165.356399] ? reacquire_held_locks+0x12f/0x200
[ 165.358384] ? nf_tables_valid_genid+0x1f/0x40 [nf_tables]
[ 165.360502] ? nla_strcmp+0x10/0x50
[ 165.362199] ? nft_table_lookup+0x4f/0xa0 [nf_tables]
[ 165.364217] ? nla_strcmp+0x10/0x50
[ 165.365891] ? nf_tables_newsetelem+0xd5/0x150 [nf_tables]
[ 165.367997] nf_tables_newsetelem+0xd5/0x150 [nf_tables]
[ 165.370083] nfnetlink_rcv_batch+0x4fd/0x790 [nfnetlink]
[ 165.372205] ? __lock_acquire+0x241/0x1400
[ 165.374058] ? __nla_validate_parse+0x57/0x8a0
[ 165.375989] ? cap_inode_getsecurity+0x230/0x230
[ 165.377954] ? security_capable+0x38/0x50
[ 165.379795] nfnetlink_rcv+0x11d/0x140 [nfnetlink]
[ 165.381779] netlink_unicast+0x1b2/0x280
[ 165.383612] netlink_sendmsg+0x351/0x470
[ 165.385439] sock_sendmsg+0x5b/0x60
[ 165.387133] ____sys_sendmsg+0x200/0x280
[ 165.388871] ? copy_msghdr_from_user+0xd9/0x160
[ 165.390805] ___sys_sendmsg+0x88/0xd0
[ 165.392524] ? __might_fault+0x3e/0x90
[ 165.394273] ? sock_getsockopt+0x3d5/0xbb0
[ 165.396021] ? __handle_mm_fault+0x545/0x6a0
[ 165.397822] ? find_held_lock+0x2d/0x90
[ 165.399593] ? __sys_sendmsg+0x5e/0xa0
[ 165.401338] __sys_sendmsg+0x5e/0xa0
[ 165.402979] do_syscall_64+0x60/0x280
[ 165.404680] entry_SYSCALL_64_after_hwframe+0x49/0xbe
[ 165.406621] RIP: 0033:0x7ff1fa46e783
[ 165.408299] Code: c7 c0 ff ff ff ff eb bb 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 64 8b 04 25 18 00 00 00 85 c0 75 14 b8 2e 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 55 c3 0f 1f 40 00 48 83 ec 28 89 54 24 1c 48
[ 165.414163] RSP: 002b:00007ffedf59ea78 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
[ 165.416804] RAX: ffffffffffffffda RBX: 00007ffedf59fc60 RCX: 00007ff1fa46e783
[ 165.419419] RDX: 0000000000000000 RSI: 00007ffedf59fb10 RDI: 0000000000000005
[ 165.421886] RBP: 00007ffedf59fc10 R08: 00007ffedf59ea54 R09: 0000000000000001
[ 165.424445] R10: 00007ff1fa630c6c R11: 0000000000000246 R12: 0000000000020000
[ 165.426954] R13: 0000000000000280 R14: 0000000000000005 R15: 00007ffedf59ea90

Disable preemption before accessing the lookup scratch area in
nft_pipapo_insert().

Reported-by: kernel test robot <lkp@intel.com>
Analysed-by: Florian Westphal <fw@strlen.de>
Cc: <stable@vger.kernel.org> # 5.6.x
Fixes: 3c4287f62044 ("nf_tables: Add set type for arbitrary concatenation of ranges")
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

x86: update AS_* macros to binutils >=2.23, supporting ADX and AVX2

Now that the kernel specifies binutils 2.23 as the minimum version, we
can remove ifdefs for AVX2 and ADX throughout.

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

netfilter: nft_set_pipapo: Separate partial and complete overlap cases on insertion

...and return -ENOTEMPTY to the front-end on collision, -EEXIST if
an identical element already exists. Together with the previous patch,
element collision will now be returned to the user as -EEXIST.

Reported-by: Phil Sutter <phil@nwl.cc>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

nft_set_pipapo: Prepare for single ranged field usage

A few adjustments in nft_pipapo_init() are needed to allow usage of
this set back-end for a single, ranged field.

Provide a convenient NFT_PIPAPO_MIN_FIELDS definition that currently
makes sure that the rbtree back-end is selected instead, for sets
with a single field.

This finally allows a fair comparison with rbtree sets, by defining
NFT_PIPAPO_MIN_FIELDS as 0 and skipping rbtree back-end initialisation:

---------------.--------------------------.-------------------------.
AMD Epyc 7402 | baselines, Mpps | Mpps, % over rbtree |
1 thread |__________________________|_________________________|
3.35GHz | | | | | |
768KiB L1D$ | netdev | hash | rbtree | | pipapo |
---------------| hook | no | single | pipapo |single field|
type entries | drop | ranges | field |single field| AVX2 |
---------------|--------|--------|--------|------------|------------|
net,port | | | | | |
1000 | 19.0 | 10.4 | 3.8 | 6.0 +58% | 9.6 +153% |
---------------|--------|--------|--------|------------|------------|
port,net | | | | | |
100 | 18.8 | 10.3 | 5.8 | 9.1 +57% |11.6 +100% |
---------------|--------|--------|--------|------------|------------|
net6,port | | | | | |
1000 | 16.4 | 7.6 | 1.8 | 2.8 +55% | 6.5 +261% |
---------------|--------|--------|--------|------------|------------|
port,proto | | | | [1] | [1] |
30000 | 19.6 | 11.6 | 3.9 | 0.9 -77% | 2.7 -31% |
---------------|--------|--------|--------|------------|------------|
port,proto | | | | | |
10000 | 19.6 | 11.6 | 4.4 | 2.1 -52% | 5.6 +27% |
---------------|--------|--------|--------|------------|------------|
port,proto | | | | | |
4 threads 10000| 77.9 | 45.1 | 17.4 | 8.3 -52% |22.4 +29% |
---------------|--------|--------|--------|------------|------------|
net6,port,mac | | | | | |
10 | 16.5 | 5.4 | 4.3 | 4.5 +5% | 8.2 +91% |
---------------|--------|--------|--------|------------|------------|
net6,port,mac, | | | | | |
proto 1000 | 16.5 | 5.7 | 1.9 | 2.8 +47% | 6.6 +247% |
---------------|--------|--------|--------|------------|------------|
net,mac | | | | | |
1000 | 19.0 | 8.4 | 3.9 | 6.0 +54% | 9.9 +154% |
---------------'--------'--------'--------'------------'------------'
[1] Causes switch of lookup table buckets for 'port' to 4-bit groups

Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

nft_set_pipapo: Introduce AVX2-based lookup implementation

If the AVX2 set is available, we can exploit the repetitive
characteristic of this algorithm to provide a fast, vectorised
version by using 256-bit wide AVX2 operations for bucket loads and
bitwise intersections.

In most cases, this implementation consistently outperforms rbtree
set instances despite the fact they are configured to use a given,
single, ranged data type out of the ones used for performance
measurements by the nft_concat_range.sh kselftest.

That script, injecting packets directly on the ingoing device path
with pktgen, reports, averaged over five runs on a single AMD Epyc
7402 thread (3.35GHz, 768 KiB L1D$, 12 MiB L2$), the figures below.
CONFIG_RETPOLINE was not set here.

Note that this is not a fair comparison over hash and rbtree set
types: non-ranged entries (used to have a reference for hash types)
would be matched faster than this, and matching on a single field
only (which is the case for rbtree) is also significantly faster.

However, it's not possible at the moment to choose this set type
for non-ranged entries, and the current implementation also needs
a few minor adjustments in order to match on less than two fields.

---------------.-----------------------------------.------------.
AMD Epyc 7402 | baselines, Mpps | this patch |
1 thread |___________________________________|____________|
3.35GHz | | | | | |
768KiB L1D$ | netdev | hash | rbtree | | |
---------------| hook | no | single | | pipapo |
type entries | drop | ranges | field | pipapo | AVX2 |
---------------|--------|--------|--------|--------|------------|
net,port | | | | | |
1000 | 19.0 | 10.4 | 3.8 | 4.0 | 7.5 +87% |
---------------|--------|--------|--------|--------|------------|
port,net | | | | | |
100 | 18.8 | 10.3 | 5.8 | 6.3 | 8.1 +29% |
---------------|--------|--------|--------|--------|------------|
net6,port | | | | | |
1000 | 16.4 | 7.6 | 1.8 | 2.1 | 4.8 +128% |
---------------|--------|--------|--------|--------|------------|
port,proto | | | | | |
30000 | 19.6 | 11.6 | 3.9 | 0.5 | 2.6 +420% |
---------------|--------|--------|--------|--------|------------|
net6,port,mac | | | | | |
10 | 16.5 | 5.4 | 4.3 | 3.4 | 4.7 +38% |
---------------|--------|--------|--------|--------|------------|
net6,port,mac, | | | | | |
proto 1000 | 16.5 | 5.7 | 1.9 | 1.4 | 3.6 +26% |
---------------|--------|--------|--------|--------|------------|
net,mac | | | | | |
1000 | 19.0 | 8.4 | 3.9 | 2.5 | 6.4 +156% |
---------------'--------'--------'--------'--------'------------'

A similar strategy could be easily reused to implement specialised
versions for other SIMD sets, and I plan to post at least a NEON
version at a later time.

Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

nft_set_pipapo: Prepare for vectorised implementation: helpers

Move most macros and helpers to a header file, so that they can be
conveniently used by related implementations.

No functional changes are intended here.

Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

nft_set_pipapo: Prepare for vectorised implementation: alignment

SIMD vector extension sets require stricter alignment than native
instruction sets to operate efficiently (AVX, NEON) or for some
instructions to work at all (AltiVec).

Provide facilities to define arbitrary alignment for lookup tables
and scratch maps. By defining byte alignment with NFT_PIPAPO_ALIGN,
lt_aligned and scratch_aligned pointers become available.

Additional headroom is allocated, and pointers to the possibly
unaligned, originally allocated areas are kept so that they can
be freed.

Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

nft_set_pipapo: Add support for 8-bit lookup groups and dynamic switch

While grouping matching bits in groups of four saves memory compared
to the more natural choice of 8-bit words (lookup table size is one
eighth), it comes at a performance cost, as the number of lookup
comparisons is doubled, and those also needs bitshifts and masking.

Introduce support for 8-bit lookup groups, together with a mapping
mechanism to dynamically switch, based on defined per-table size
thresholds and hysteresis, between 8-bit and 4-bit groups, as tables
grow and shrink. Empty sets start with 8-bit groups, and per-field
tables are converted to 4-bit groups if they get too big.

An alternative approach would have been to swap per-set lookup
operation functions as needed, but this doesn't allow for different
group sizes in the same set, which looks desirable if some fields
need significantly more matching data compared to others due to
heavier impact of ranges (e.g. a big number of subnets with
relatively simple port specifications).

Allowing different group sizes for the same lookup functions implies
the need for further conditional clauses, whose cost, however,
appears to be negligible in tests.

The matching rate figures below were obtained for x86_64 running
the nft_concat_range.sh "performance" cases, averaged over five
runs, on a single thread of an AMD Epyc 7402 CPU, and for aarch64
on a single thread of a BCM2711 (Raspberry Pi 4 Model B 4GB),
clocked at a stable 2147MHz frequency:

---------------.-----------------------------------.------------.
AMD Epyc 7402 | baselines, Mpps | this patch |
1 thread |___________________________________|____________|
3.35GHz | | | | | |
768KiB L1D$ | netdev | hash | rbtree | | |
---------------| hook | no | single | pipapo | pipapo |
type entries | drop | ranges | field | 4 bits | bit switch |
---------------|--------|--------|--------|--------|------------|
net,port | | | | | |
1000 | 19.0 | 10.4 | 3.8 | 2.8 | 4.0 +43% |
---------------|--------|--------|--------|--------|------------|
port,net | | | | | |
100 | 18.8 | 10.3 | 5.8 | 5.5 | 6.3 +14% |
---------------|--------|--------|--------|--------|------------|
net6,port | | | | | |
1000 | 16.4 | 7.6 | 1.8 | 1.3 | 2.1 +61% |
---------------|--------|--------|--------|--------|------------|
port,proto | | | | | [1] |
30000 | 19.6 | 11.6 | 3.9 | 0.3 | 0.5 +66% |
---------------|--------|--------|--------|--------|------------|
net6,port,mac | | | | | |
10 | 16.5 | 5.4 | 4.3 | 2.6 | 3.4 +31% |
---------------|--------|--------|--------|--------|------------|
net6,port,mac, | | | | | |
proto 1000 | 16.5 | 5.7 | 1.9 | 1.0 | 1.4 +40% |
---------------|--------|--------|--------|--------|------------|
net,mac | | | | | |
1000 | 19.0 | 8.4 | 3.9 | 1.7 | 2.5 +47% |
---------------'--------'--------'--------'--------'------------'
[1] Causes switch of lookup table buckets for 'port', not 'proto',
to 4-bit groups

---------------.-----------------------------------.------------.
BCM2711 | baselines, Mpps | this patch |
1 thread |___________________________________|____________|
2147MHz | | | | | |
32KiB L1D$ | netdev | hash | rbtree | | |
---------------| hook | no | single | pipapo | pipapo |
type entries | drop | ranges | field | 4 bits | bit switch |
---------------|--------|--------|--------|--------|------------|
net,port | | | | | |
1000 | 1.63 | 1.37 | 0.87 | 0.61 | 0.70 +17% |
---------------|--------|--------|--------|--------|------------|
port,net | | | | | |
100 | 1.64 | 1.36 | 1.02 | 0.78 | 0.81 +4% |
---------------|--------|--------|--------|--------|------------|
net6,port | | | | | |
1000 | 1.56 | 1.27 | 0.65 | 0.34 | 0.50 +47% |
---------------|--------|--------|--------|--------|------------|
port,proto [2] | | | | | |
10000 | 1.68 | 1.43 | 0.84 | 0.30 | 0.40 +13% |
---------------|--------|--------|--------|--------|------------|
net6,port,mac | | | | | |
10 | 1.56 | 1.14 | 1.02 | 0.62 | 0.66 +6% |
---------------|--------|--------|--------|--------|------------|
net6,port,mac, | | | | | |
proto 1000 | 1.56 | 1.12 | 0.64 | 0.27 | 0.40 +48% |
---------------|--------|--------|--------|--------|------------|
net,mac | | | | | |
1000 | 1.63 | 1.26 | 0.87 | 0.41 | 0.53 +29% |
---------------'--------'--------'--------'--------'------------'
[2] Using 10000 entries instead of 30000 as it would take way too
long for the test script to generate all of them

Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

nft_set_pipapo: Generalise group size for buckets

Get rid of all hardcoded assumptions that buckets in lookup tables
correspond to four-bit groups, and replace them with appropriate
calculations based on a variable group size, now stored in struct
field.

The group size could now be in principle any divisor of eight. Note,
though, that lookup and get functions need an implementation
intimately depending on the group size, and the only supported size
there, currently, is four bits, which is also the initial and only
used size at the moment.

While at it, drop 'groups' from struct nft_pipapo: it was never used.

Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: Replace zero-length array with flexible-array member

The current codebase makes use of the zero-length array language
extension to the C90 standard, but the preferred mechanism to declare
variable-length types such as these ones is a flexible array member[1][2],
introduced in C99:

struct foo {
int stuff;
struct boo array[];
};

By making use of the mechanism above, we will get a compiler warning
in case the flexible array does not occur last in the structure, which
will help us prevent some kind of undefined behavior bugs from being
inadvertently introduced[3] to the codebase from now on.

Also, notice that, dynamic memory allocations won't be affected by
this change:

"Flexible array members have incomplete type, and so the sizeof operator
may not be applied. As a quirk of the original implementation of
zero-length arrays, sizeof evaluates to zero."[1]

Lastly, fix checkpatch.pl warning
WARNING: __aligned(size) is preferred over __attribute__((aligned(size)))
in net/bridge/netfilter/ebtables.c

This issue was found with the help of Coccinelle.

[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] https://github.com/KSPP/linux/issues/21
[3] commit 76497732932f ("cxgb3/l2t: Fix undefined behaviour")

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: nft_set_pipapo: make the symbol 'nft_pipapo_get' static

Fix the following sparse warning:

net/netfilter/nft_set_pipapo.c:739:6: warning: symbol 'nft_pipapo_get' was not declared. Should it be static?

Fixes: 3c4287f62044 ("nf_tables: Add set type for arbitrary concatenation of ranges")
Signed-off-by: Chen Wandun <chenwandun@huawei.com>
Acked-by: Stefano Brivio <sbrivio@redhat.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: nf_tables: make all set structs const

They do not need to be writeable anymore.

v2: remove left-over __read_mostly annotation in set_pipapo.c (Stefano)

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

nft_set_pipapo: Actually fetch key data in nft_pipapo_remove()

Phil reports that adding elements, flushing and re-adding them
right away:

nft add table t '{ set s { type ipv4_addr . inet_service; flags interval; }; }'
nft add element t s '{ 10.0.0.1 . 22-25, 10.0.0.1 . 10-20 }'
nft flush set t s
nft add element t s '{ 10.0.0.1 . 10-20, 10.0.0.1 . 22-25 }'

triggers, almost reliably, a crash like this one:

[ 71.319848] general protection fault, probably for non-canonical address 0x6f6b6e696c2e756e: 0000 [#1] PREEMPT SMP PTI
[ 71.321540] CPU: 3 PID: 1201 Comm: kworker/3:2 Not tainted 5.6.0-rc1-00377-g2bb07f4e1d861 #192
[ 71.322746] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS ?-20190711_202441-buildvm-armv7-10.arm.fedoraproject.org-2.fc31 04/01/2014
[ 71.324430] Workqueue: events nf_tables_trans_destroy_work [nf_tables]
[ 71.325387] RIP: 0010:nft_set_elem_destroy+0xa5/0x110 [nf_tables]
[ 71.326164] Code: 89 d4 84 c0 74 0e 8b 77 44 0f b6 f8 48 01 df e8 41 ff ff ff 45 84 e4 74 36 44 0f b6 63 08 45 84 e4 74 2c 49 01 dc 49 8b 04 24 <48> 8b 40 38 48 85 c0 74 4f 48 89 e7 4c 8b
[ 71.328423] RSP: 0018:ffffc9000226fd90 EFLAGS: 00010282
[ 71.329225] RAX: 6f6b6e696c2e756e RBX: ffff88813ab79f60 RCX: ffff88813931b5a0
[ 71.330365] RDX: 0000000000000001 RSI: 0000000000000000 RDI: ffff88813ab79f9a
[ 71.331473] RBP: ffff88813ab79f60 R08: 0000000000000008 R09: 0000000000000000
[ 71.332627] R10: 000000000000021c R11: 0000000000000000 R12: ffff88813ab79fc2
[ 71.333615] R13: ffff88813b3adf50 R14: dead000000000100 R15: ffff88813931b8a0
[ 71.334596] FS: 0000000000000000(0000) GS:ffff88813bd80000(0000) knlGS:0000000000000000
[ 71.335780] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 71.336577] CR2: 000055ac683710f0 CR3: 000000013a222003 CR4: 0000000000360ee0
[ 71.337533] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 71.338557] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[ 71.339718] Call Trace:
[ 71.340093] nft_pipapo_destroy+0x7a/0x170 [nf_tables_set]
[ 71.340973] nft_set_destroy+0x20/0x50 [nf_tables]
[ 71.341879] nf_tables_trans_destroy_work+0x246/0x260 [nf_tables]
[ 71.342916] process_one_work+0x1d5/0x3c0
[ 71.343601] worker_thread+0x4a/0x3c0
[ 71.344229] kthread+0xfb/0x130
[ 71.344780] ? process_one_work+0x3c0/0x3c0
[ 71.345477] ? kthread_park+0x90/0x90
[ 71.346129] ret_from_fork+0x35/0x40
[ 71.346748] Modules linked in: nf_tables_set nf_tables nfnetlink 8021q [last unloaded: nfnetlink]
[ 71.348153] ---[ end trace 2eaa8149ca759bcc ]---
[ 71.349066] RIP: 0010:nft_set_elem_destroy+0xa5/0x110 [nf_tables]
[ 71.350016] Code: 89 d4 84 c0 74 0e 8b 77 44 0f b6 f8 48 01 df e8 41 ff ff ff 45 84 e4 74 36 44 0f b6 63 08 45 84 e4 74 2c 49 01 dc 49 8b 04 24 <48> 8b 40 38 48 85 c0 74 4f 48 89 e7 4c 8b
[ 71.350017] RSP: 0018:ffffc9000226fd90 EFLAGS: 00010282
[ 71.350019] RAX: 6f6b6e696c2e756e RBX: ffff88813ab79f60 RCX: ffff88813931b5a0
[ 71.350019] RDX: 0000000000000001 RSI: 0000000000000000 RDI: ffff88813ab79f9a
[ 71.350020] RBP: ffff88813ab79f60 R08: 0000000000000008 R09: 0000000000000000
[ 71.350021] R10: 000000000000021c R11: 0000000000000000 R12: ffff88813ab79fc2
[ 71.350022] R13: ffff88813b3adf50 R14: dead000000000100 R15: ffff88813931b8a0
[ 71.350025] FS: 0000000000000000(0000) GS:ffff88813bd80000(0000) knlGS:0000000000000000
[ 71.350026] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 71.350027] CR2: 000055ac683710f0 CR3: 000000013a222003 CR4: 0000000000360ee0
[ 71.350028] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 71.350028] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[ 71.350030] Kernel panic - not syncing: Fatal exception
[ 71.350412] Kernel Offset: disabled
[ 71.365922] ---[ end Kernel panic - not syncing: Fatal exception ]---

which is caused by dangling elements that have been deactivated, but
never removed.

On a flush operation, nft_pipapo_walk() walks through all the elements
in the mapping table, which are then deactivated by nft_flush_set(),
one by one, and added to the commit list for removal. Element data is
then freed.

On transaction commit, nft_pipapo_remove() is called, and failed to
remove these elements, leading to the stale references in the mapping.
The first symptom of this, revealed by KASan, is a one-byte
use-after-free in subsequent calls to nft_pipapo_walk(), which is
usually not enough to trigger a panic. When stale elements are used
more heavily, though, such as double-free via nft_pipapo_destroy()
as in Phil's case, the problem becomes more noticeable.

The issue comes from that fact that, on a flush operation,
nft_pipapo_remove() won't get the actual key data via elem->key,
elements to be deleted upon commit won't be found by the lookup via
pipapo_get(), and removal will be skipped. Key data should be fetched
via nft_set_ext_key(), instead.

Reported-by: Phil Sutter <phil@nwl.cc>
Fixes: 3c4287f62044 ("nf_tables: Add set type for arbitrary concatenation of ranges")
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: nft_set_pipapo: Don't abuse unlikely() in pipapo_refill()

I originally used unlikely() in the if (match_only) clause, which
we hit on the mapping table for the last field in a set, to ensure
we avoid branching to the rest of for loop body, which is executed
more frequently.

However, Pablo reports, this is confusing as it gives the impression
that this is not a common case, and it's actually not the intended
usage of unlikely().

I couldn't observe any statistical difference in matching rates on
x864_64 and aarch64 without it, so just drop it.

Reported-by: Pablo Neira Ayuso <pablo@netfilter.org>
Fixes: 3c4287f62044 ("nf_tables: Add set type for arbitrary concatenation of ranges")
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

netfilter: nft_set_pipapo: Fix mapping table example in comments

In both insertion and lookup examples, the two element pointers
of rule mapping tables were swapped. Fix that.

Reported-by: Pablo Neira Ayuso <pablo@netfilter.org>
Fixes: 3c4287f62044 ("nf_tables: Add set type for arbitrary concatenation of ranges")
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

nf_tables: Add set type for arbitrary concatenation of ranges

This new set type allows for intervals in concatenated fields,
which are expressed in the usual way, that is, simple byte
concatenation with padding to 32 bits for single fields, and
given as ranges by specifying start and end elements containing,
each, the full concatenation of start and end values for the
single fields.

Ranges are expanded to composing netmasks, for each field: these
are inserted as rules in per-field lookup tables. Bits to be
classified are divided in 4-bit groups, and for each group, the
lookup table contains 4^2 buckets, representing all the possible
values of a bit group. This approach was inspired by the Grouper
algorithm:
http://www.cse.usf.edu/~ligatti/projects/grouper/

Matching is performed by a sequence of AND operations between
bucket values, with buckets selected according to the value of
packet bits, for each group. The result of this sequence tells
us which rules matched for a given field.

In order to concatenate several ranged fields, per-field rules
are mapped using mapping arrays, one per field, that specify
which rules should be considered while matching the next field.
The mapping array for the last field contains a reference to
the element originally inserted.

The notes in nft_set_pipapo.c cover the algorithm in deeper
detail.

A pure hash-based approach is of no use here, as ranges need
to be classified. An implementation based on "proxying" the
existing red-black tree set type, creating a tree for each
field, was considered, but deemed impractical due to the fact
that elements would need to be shared between trees, at least
as long as we want to keep UAPI changes to a minimum.

A stand-alone implementation of this algorithm is available at:
https://pipapo.lameexcu.se
together with notes about possible future optimisations
(in pipapo.c).

This algorithm was designed with data locality in mind, and can
be highly optimised for SIMD instruction sets, as the bulk of
the matching work is done with repetitive, simple bitwise
operations.

At this point, without further optimisations, nft_concat_range.sh
reports, for one AMD Epyc 7351 thread (2.9GHz, 512 KiB L1D$, 8 MiB
L2$):

TEST: performance
net,port [ OK ]
baseline (drop from netdev hook): 10190076pps
baseline hash (non-ranged entries): 6179564pps
baseline rbtree (match on first field only): 2950341pps
set with 1000 full, ranged entries: 2304165pps
port,net [ OK ]
baseline (drop from netdev hook): 10143615pps
baseline hash (non-ranged entries): 6135776pps
baseline rbtree (match on first field only): 4311934pps
set with 100 full, ranged entries: 4131471pps
net6,port [ OK ]
baseline (drop from netdev hook): 9730404pps
baseline hash (non-ranged entries): 4809557pps
baseline rbtree (match on first field only): 1501699pps
set with 1000 full, ranged entries: 1092557pps
port,proto [ OK ]
baseline (drop from netdev hook): 10812426pps
baseline hash (non-ranged entries): 6929353pps
baseline rbtree (match on first field only): 3027105pps
set with 30000 full, ranged entries: 284147pps
net6,port,mac [ OK ]
baseline (drop from netdev hook): 9660114pps
baseline hash (non-ranged entries): 3778877pps
baseline rbtree (match on first field only): 3179379pps
set with 10 full, ranged entries: 2082880pps
net6,port,mac,proto [ OK ]
baseline (drop from netdev hook): 9718324pps
baseline hash (non-ranged entries): 3799021pps
baseline rbtree (match on first field only): 1506689pps
set with 1000 full, ranged entries: 783810pps
net,mac [ OK ]
baseline (drop from netdev hook): 10190029pps
baseline hash (non-ranged entries): 5172218pps
baseline rbtree (match on first field only): 2946863pps
set with 1000 full, ranged entries: 1279122pps

v4:
- fix build for 32-bit architectures: 64-bit division needs
div_u64() (kbuild test robot <lkp@intel.com>)
v3:
- rework interface for field length specification,
NFT_SET_SUBKEY disappears and information is stored in
description
- remove scratch area to store closing element of ranges,
as elements now come with an actual attribute to specify
the upper range limit (Pablo Neira Ayuso)
- also remove pointer to 'start' element from mapping table,
closing key is now accessible via extension data
- use bytes right away instead of bits for field lengths,
this way we can also double the inner loop of the lookup
function to take care of upper and lower bits in a single
iteration (minor performance improvement)
- make it clearer that set operations are actually atomic
API-wise, but we can't e.g. implement flush() as one-shot
action
- fix type for 'dup' in nft_pipapo_insert(), check for
duplicates only in the next generation, and in general take
care of differentiating generation mask cases depending on
the operation (Pablo Neira Ayuso)
- report C implementation matching rate in commit message, so
that AVX2 implementation can be compared (Pablo Neira Ayuso)
v2:
- protect access to scratch maps in nft_pipapo_lookup() with
local_bh_disable/enable() (Florian Westphal)
- drop rcu_read_lock/unlock() from nft_pipapo_lookup(), it's
already implied (Florian Westphal)
- explain why partial allocation failures don't need handling
in pipapo_realloc_scratch(), rename 'm' to clone and update
related kerneldoc to make it clear we're not operating on
the live copy (Florian Westphal)
- add expicit check for priv->start_elem in
nft_pipapo_insert() to avoid ending up in nft_pipapo_walk()
with a NULL start element, and also zero it out in every
operation that might make it invalid, so that insertion
doesn't proceed with an invalid element (Florian Westphal)

Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>