Commit Graph
7063 Commits
Author SHA1 Message Date
Kees Cook 85cb0757d7 net: Convert proto_ops connect() callbacks to use sockaddr_unsized
Update all struct proto_ops connect() callback function prototypes from
"struct sockaddr *" to "struct sockaddr_unsized *" to avoid lying to the
compiler about object sizes. Calls into struct proto handlers gain casts
that will be removed in the struct proto conversion patch.

No binary changes expected.

Signed-off-by: Kees Cook <kees@kernel.org>
Link: https://patch.msgid.link/20251104002617.2752303-3-kees@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2025-11-04 19:10:32 -08:00
Kees Cook 0e50474fa5 net: Convert proto_ops bind() callbacks to use sockaddr_unsized
Update all struct proto_ops bind() callback function prototypes from
"struct sockaddr *" to "struct sockaddr_unsized *" to avoid lying to the
compiler about object sizes. Calls into struct proto handlers gain casts
that will be removed in the struct proto conversion patch.

No binary changes expected.

Signed-off-by: Kees Cook <kees@kernel.org>
Link: https://patch.msgid.link/20251104002617.2752303-2-kees@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2025-11-04 19:10:32 -08:00
Jakub Kicinski 1a2352ad82 Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net
Cross-merge networking fixes after downstream PR (net-6.18-rc4).

No conflicts, adjacent changes:

drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
  ded9813d17 ("net: stmmac: Consider Tx VLAN offload tag length for maxSDU")
  26ab9830be ("net: stmmac: replace has_xxxx with core_type")

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2025-10-31 06:46:03 -07:00
Florian Westphal 2b749f2576 netfilter: conntrack: disable 0 value for conntrack_max setting
Undocumented historical artifact inherited from ip_conntrack.
If value is 0, then no limit is applied at all, conntrack table
can grow to huge value, only limited by size of conntrack hashes and
the kernel-internal upper limit on the hash chain lengths.

This feature makes no sense; users can just set
conntrack_max=2147483647 (INT_MAX).

Disallow a 0 value.  This will make it slightly easier to allow
per-netns constraints for this value in a future patch.

Signed-off-by: Florian Westphal <fw@strlen.de>
2025-10-30 12:52:45 +01:00
Fernando Fernandez Mancera 320d80eeb2 netfilter: nf_tables: use C99 struct initializer for nft_set_iter
Use C99 struct initializer for nft_set_iter, simplifying the code and
preventing future errors due to uninitialized fields if new fields are
added to the struct.

Signed-off-by: Fernando Fernandez Mancera <fmancera@suse.de>
Signed-off-by: Florian Westphal <fw@strlen.de>
2025-10-30 12:52:45 +01:00
Andrii Melnychenko 90918e3b64 netfilter: nft_ct: add seqadj extension for natted connections
Sequence adjustment may be required for FTP traffic with PASV/EPSV modes.
due to need to re-write packet payload (IP, port) on the ftp control
connection. This can require changes to the TCP length and expected
seq / ack_seq.

The easiest way to reproduce this issue is with PASV mode.
Example ruleset:
table inet ftp_nat {
        ct helper ftp_helper {
                type "ftp" protocol tcp
                l3proto inet
        }

        chain prerouting {
                type filter hook prerouting priority 0; policy accept;
                tcp dport 21 ct state new ct helper set "ftp_helper"
        }
}
table ip nat {
        chain prerouting {
                type nat hook prerouting priority -100; policy accept;
                tcp dport 21 dnat ip prefix to ip daddr map {
			192.168.100.1 : 192.168.13.2/32 }
        }

        chain postrouting {
                type nat hook postrouting priority 100 ; policy accept;
                tcp sport 21 snat ip prefix to ip saddr map {
			192.168.13.2 : 192.168.100.1/32 }
        }
}

Note that the ftp helper gets assigned *after* the dnat setup.

The inverse (nat after helper assign) is handled by an existing
check in nf_nat_setup_info() and will not show the problem.

Topoloy:

 +-------------------+     +----------------------------------+
 | FTP: 192.168.13.2 | <-> | NAT: 192.168.13.3, 192.168.100.1 |
 +-------------------+     +----------------------------------+
                                      |
                         +-----------------------+
                         | Client: 192.168.100.2 |
                         +-----------------------+

ftp nat changes do not work as expected in this case:
Connected to 192.168.100.1.
[..]
ftp> epsv
EPSV/EPRT on IPv4 off.
ftp> ls
227 Entering passive mode (192,168,100,1,209,129).
421 Service not available, remote server has closed connection.

Kernel logs:
Missing nfct_seqadj_ext_add() setup call
WARNING: CPU: 1 PID: 0 at net/netfilter/nf_conntrack_seqadj.c:41
[..]
 __nf_nat_mangle_tcp_packet+0x100/0x160 [nf_nat]
 nf_nat_ftp+0x142/0x280 [nf_nat_ftp]
 help+0x4d1/0x880 [nf_conntrack_ftp]
 nf_confirm+0x122/0x2e0 [nf_conntrack]
 nf_hook_slow+0x3c/0xb0
 ..

Fix this by adding the required extension when a conntrack helper is assigned
to a connection that has a nat binding.

Fixes: 1a64edf54f ("netfilter: nft_ct: add helper set support")
Signed-off-by: Andrii Melnychenko <a.melnychenko@vyos.io>
Signed-off-by: Florian Westphal <fw@strlen.de>
2025-10-29 14:47:59 +01:00
Fernando Fernandez Mancera 8d96dfdcab netfilter: nft_connlimit: fix possible data race on connection count
nft_connlimit_eval() reads priv->list->count to check if the connection
limit has been exceeded. This value is being read without a lock and can
be modified by a different process. Use READ_ONCE() for correctness.

Fixes: df4a902509 ("netfilter: nf_conncount: merge lookup and add functions")
Signed-off-by: Fernando Fernandez Mancera <fmancera@suse.de>
Signed-off-by: Florian Westphal <fw@strlen.de>
2025-10-29 14:47:59 +01:00
Florian Westphal 514f1dc8f2 netfilter: nft_ct: enable labels for get case too
conntrack labels can only be set when the conntrack has been created
with the "ctlabel" extension.

For older iptables (connlabel match), adding an "-m connlabel" rule
turns on the ctlabel extension allocation for all future conntrack
entries.

For nftables, its only enabled for 'ct label set foo', but not for
'ct label foo' (i.e. check).
But users could have a ruleset that only checks for presence, and rely
on userspace to set a label bit via ctnetlink infrastructure.

This doesn't work without adding a dummy 'ct label set' rule.
We could also enable extension infra for the first (failing) ctnetlink
request, but unlike ruleset we would not be able to disable the
extension again.

Therefore turn on ctlabel extension allocation if an nftables ruleset
checks for a connlabel too.

Fixes: 1ad8f48df6 ("netfilter: nftables: add connlabel set support")
Reported-by: Antonio Ojea <aojea@google.com>
Closes: https://lore.kernel.org/netfilter-devel/aPi_VdZpVjWujZ29@strlen.de/
Signed-off-by: Florian Westphal <fw@strlen.de>
2025-10-29 14:47:59 +01:00
Fernando Fernandez Mancera f359b809d5 netfilter: nft_objref: validate objref and objrefmap expressions
Referencing a synproxy stateful object from OUTPUT hook causes kernel
crash due to infinite recursive calls:

BUG: TASK stack guard page was hit at 000000008bda5b8c (stack is 000000003ab1c4a5..00000000494d8b12)
[...]
Call Trace:
 __find_rr_leaf+0x99/0x230
 fib6_table_lookup+0x13b/0x2d0
 ip6_pol_route+0xa4/0x400
 fib6_rule_lookup+0x156/0x240
 ip6_route_output_flags+0xc6/0x150
 __nf_ip6_route+0x23/0x50
 synproxy_send_tcp_ipv6+0x106/0x200
 synproxy_send_client_synack_ipv6+0x1aa/0x1f0
 nft_synproxy_do_eval+0x263/0x310
 nft_do_chain+0x5a8/0x5f0 [nf_tables
 nft_do_chain_inet+0x98/0x110
 nf_hook_slow+0x43/0xc0
 __ip6_local_out+0xf0/0x170
 ip6_local_out+0x17/0x70
 synproxy_send_tcp_ipv6+0x1a2/0x200
 synproxy_send_client_synack_ipv6+0x1aa/0x1f0
[...]

Implement objref and objrefmap expression validate functions.

Currently, only NFT_OBJECT_SYNPROXY object type requires validation.
This will also handle a jump to a chain using a synproxy object from the
OUTPUT hook.

Now when trying to reference a synproxy object in the OUTPUT hook, nft
will produce the following error:

synproxy_crash.nft: Error: Could not process rule: Operation not supported
  synproxy name mysynproxy
  ^^^^^^^^^^^^^^^^^^^^^^^^

Fixes: ee394f96ad ("netfilter: nft_synproxy: add synproxy stateful object support")
Reported-by: Georg Pfuetzenreuter <georg.pfuetzenreuter@suse.com>
Closes: https://bugzilla.suse.com/1250237
Signed-off-by: Fernando Fernandez Mancera <fmancera@suse.de>
Reviewed-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Florian Westphal <fw@strlen.de>
2025-10-08 13:17:25 +02:00
Eric Dumazet c5ba345b2d netfilter: nf_conntrack: do not skip entries in /proc/net/nf_conntrack
ct_seq_show() has an opportunistic garbage collector :

if (nf_ct_should_gc(ct)) {
    nf_ct_kill(ct);
    goto release;
}

So if one nf_conn is killed there, next time ct_get_next() runs,
we skip the following item in the bucket, even if it should have
been displayed if gc did not take place.

We can decrement st->skip_elems to tell ct_get_next() one of the items
was removed from the chain.

Fixes: 58e207e498 ("netfilter: evict stale entries when user reads /proc/net/nf_conntrack")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
2025-09-24 11:50:28 +02:00
Florian Westphal 5823699a11 netfilter: nft_set_pipapo_avx2: fix skip of expired entries
KASAN reports following splat:
BUG: KASAN: slab-out-of-bounds in pipapo_get_avx2+0x941/0x25d0
Read of size 1 at addr ffff88814c561be0 by task nft/3944
Call Trace:
 pipapo_get_avx2+0x941/0x25d0
 nft_pipapo_insert+0x440/0x11b0
 nf_tables_newsetelem+0x220a/0x3a00
 ..

This bisects to commit 84c1da7b38 ("netfilter: nft_set_pipapo: use AVX2
algorithm for insertions too").

However, that change merely uncovers this bug.

When we find a match but that match has expired or timed out, the AVX2
implementation restarts the full match loop.

At that point, the pointer to the key data has already been changed and
points to the keys last field.
This will then result in out-of-bounds read once its incremented again
for the next field.

The restart logic in AVX2 is different compared to the plain C
implementation, but both should follow the same logic.

The C implementation just calls pipapo_refill() again do check the next
entry.  Do the same in the AVX2 implementation.

Note that with this change, due to implementation differences of
pipapo_refill vs. nft_pipapo_avx2_refill, the refill call will return
the same element again. Then, on the next call, it will move to the next
entry as expected.  This is because avx2_refill doesn't clear the bitmap
in the 'last' conditional.  This is harmless. Expired/timed out elements
are also not expected to be frequent.

selftest is added in a followup commit.

Fixes: 7400b06396 ("nft_set_pipapo: Introduce AVX2-based lookup implementation")
Reviewed-by: Stefano Brivio <sbrivio@redhat.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
2025-09-24 11:50:28 +02:00
Florian Westphal 4dbac7db17 netfilter: nft_set_pipapo: use 0 genmask for packetpath lookups
In commit c4eaca2e10 ("netfilter: nft_set_pipapo: don't check genbit from
packetpath lookups") I replaced genmask_cur() with NFT_GENMASK_ANY, but
this change has no effect in the pipapo set type.

New entries are unreachable from the active copy, so NFT_GENMASK_ANY has
same result as genmask_cur():

current-gen elements are disabled and the new-generation
elements cannot be found.

Tests did not catch this incomplete fix because the change also dropped
the genmask test from the AVX2 version of the algorithm, so test only
fails if host cpu lacks AVX2 support.

Use genmask test only from the control plane (inserts, deletions, ..).

Packet path has to skip the check, use of 0 is enough for this because
ext->genmask has a the relevant bit set when the element is INACTIVE
in that generation: using a 0 genmask thus makes nft_set_elem_active()
always return true.

Fix the comment and replace NFT_GENMASK_ANY with 0.

Fixes: c4eaca2e10 ("netfilter: nft_set_pipapo: don't check genbit from packetpath lookups")
Signed-off-by: Florian Westphal <fw@strlen.de>
2025-09-24 11:50:28 +02:00
Fernando Fernandez Mancera 09efbac953 netfilter: nfnetlink: reset nlh pointer during batch replay
During a batch replay, the nlh pointer is not reset until the parsing of
the commands. Since commit bf2ac490d2 ("netfilter: nfnetlink: Handle
ACK flags for batch messages") that is problematic as the condition to
add an ACK for batch begin will evaluate to true even if NLM_F_ACK
wasn't used for batch begin message.

If there is an error during the command processing, netlink is sending
an ACK despite that. This misleads userspace tools which think that the
return code was 0. Reset the nlh pointer to the original one when a
replay is triggered.

Fixes: bf2ac490d2 ("netfilter: nfnetlink: Handle ACK flags for batch messages")
Signed-off-by: Fernando Fernandez Mancera <fmancera@suse.de>
Signed-off-by: Florian Westphal <fw@strlen.de>
2025-09-24 11:50:28 +02:00
Slavin Liu 134121bfd9 ipvs: Defer ip_vs_ftp unregister during netns cleanup
On the netns cleanup path, __ip_vs_ftp_exit() may unregister ip_vs_ftp
before connections with valid cp->app pointers are flushed, leading to a
use-after-free.

Fix this by introducing a global `exiting_module` flag, set to true in
ip_vs_ftp_exit() before unregistering the pernet subsystem. In
__ip_vs_ftp_exit(), skip ip_vs_ftp unregister if called during netns
cleanup (when exiting_module is false) and defer it to
__ip_vs_cleanup_batch(), which unregisters all apps after all connections
are flushed. If called during module exit, unregister ip_vs_ftp
immediately.

Fixes: 61b1ab4583 ("IPVS: netns, add basic init per netns.")
Suggested-by: Julian Anastasov <ja@ssi.bg>
Signed-off-by: Slavin Liu <slavin452@gmail.com>
Signed-off-by: Julian Anastasov <ja@ssi.bg>
Signed-off-by: Florian Westphal <fw@strlen.de>
2025-09-24 11:50:28 +02:00
Marco Crivellari 5fd8bb982e net: replace use of system_wq with system_percpu_wq
Currently if a user enqueue a work item using schedule_delayed_work() the
used wq is "system_wq" (per-cpu wq) while queue_delayed_work() use
WORK_CPU_UNBOUND (used when a cpu is not specified). The same applies to
schedule_work() that is using system_wq and queue_work(), that makes use
again of WORK_CPU_UNBOUND.

This lack of consistentcy cannot be addressed without refactoring the API.

system_unbound_wq should be the default workqueue so as not to enforce
locality constraints for random work whenever it's not required.

Adding system_dfl_wq to encourage its use when unbound work should be used.

The old system_unbound_wq will be kept for a few release cycles.

Suggested-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Marco Crivellari <marco.crivellari@suse.com>
Link: https://patch.msgid.link/20250918142427.309519-3-marco.crivellari@suse.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2025-09-22 17:40:30 -07:00
Jakub Kicinski bd569dd935 Merge tag 'nf-next-25-09-11' of https://git.kernel.org/pub/scm/linux/kernel/git/netfilter/nf-next
Florian Westphal says:

====================
netfilter: updates for net-next

1) Don't respond to ICMP_UNREACH errors with another ICMP_UNREACH
   error.
2) Support fetching the current bridge ethernet address.
   This allows a more flexible approach to packet redirection
   on bridges without need to use hardcoded addresses. From
   Fernando Fernandez Mancera.
3) Zap a few no-longer needed conditionals from ipvs packet path
   and convert to READ/WRITE_ONCE to avoid KCSAN warnings.
   From Zhang Tengfei.
4) Remove a no-longer-used macro argument in ipset, from Zhen Ni.

* tag 'nf-next-25-09-11' of https://git.kernel.org/pub/scm/linux/kernel/git/netfilter/nf-next:
  netfilter: nf_reject: don't reply to icmp error messages
  ipvs: Use READ_ONCE/WRITE_ONCE for ipvs->enable
  netfilter: nft_meta_bridge: introduce NFT_META_BRI_IIFHWADDR support
  netfilter: ipset: Remove unused htable_bits in macro ahash_region
  selftest:net: fixed spelling mistakes
====================

Link: https://patch.msgid.link/20250911143819.14753-1-fw@strlen.de
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2025-09-12 17:06:25 -07:00
Jakub Kicinski fc3a281041 Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net
Cross-merge networking fixes after downstream PR (net-6.17-rc6).

Conflicts:

net/netfilter/nft_set_pipapo.c
net/netfilter/nft_set_pipapo_avx2.c
  c4eaca2e10 ("netfilter: nft_set_pipapo: don't check genbit from packetpath lookups")
  84c1da7b38 ("netfilter: nft_set_pipapo: use avx2 algorithm for insertions too")

Only trivial adjacent changes (in a doc and a Makefile).

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2025-09-11 17:40:13 -07:00
Zhang Tengfei 944b6b216c ipvs: Use READ_ONCE/WRITE_ONCE for ipvs->enable
KCSAN reported a data-race on the `ipvs->enable` flag, which is
written in the control path and read concurrently from many other
contexts.

Following a suggestion by Julian, this patch fixes the race by
converting all accesses to use `WRITE_ONCE()/READ_ONCE()`.
This lightweight approach ensures atomic access and acts as a
compiler barrier, preventing unsafe optimizations where the flag
is checked in loops (e.g., in ip_vs_est.c).

Additionally, the `enable` checks in the fast-path hooks
(`ip_vs_in_hook`, `ip_vs_out_hook`, `ip_vs_forward_icmp`) are
removed. These are unnecessary since commit 857ca89711
("ipvs: register hooks only with services"). The `enable=0`
condition they check for can only occur in two rare and non-fatal
scenarios: 1) after hooks are registered but before the flag is set,
and 2) after hooks are unregistered on cleanup_net. In the worst
case, a single packet might be mishandled (e.g., dropped), which
does not lead to a system crash or data corruption. Adding a check
in the performance-critical fast-path to handle this harmless
condition is not a worthwhile trade-off.

Fixes: 857ca89711 ("ipvs: register hooks only with services")
Reported-by: syzbot+1651b5234028c294c339@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=1651b5234028c294c339
Suggested-by: Julian Anastasov <ja@ssi.bg>
Link: https://lore.kernel.org/lvs-devel/2189fc62-e51e-78c9-d1de-d35b8e3657e3@ssi.bg/
Signed-off-by: Zhang Tengfei <zhtfdev@gmail.com>
Acked-by: Julian Anastasov <ja@ssi.bg>
Signed-off-by: Florian Westphal <fw@strlen.de>
2025-09-11 15:40:55 +02:00
Zhen Ni ba941796d7 netfilter: ipset: Remove unused htable_bits in macro ahash_region
Since the ahash_region() macro was redefined to calculate the region
index solely from HTABLE_REGION_BITS, the htable_bits parameter became
unused.

Remove the unused htable_bits argument and its call sites, simplifying
the code without changing semantics.

Fixes: 8478a729c0 ("netfilter: ipset: fix region locking in hash types")
Signed-off-by: Zhen Ni <zhen.ni@easystack.cn>
Reviewed-by: Phil Sutter <phil@nwl.cc>
Signed-off-by: Florian Westphal <fw@strlen.de>
2025-09-11 15:40:55 +02:00
Florian Westphal b2f742c846 netfilter: nf_tables: restart set lookup on base_seq change
The hash, hash_fast, rhash and bitwise sets may indicate no result even
though a matching element exists during a short time window while other
cpu is finalizing the transaction.

This happens when the hash lookup/bitwise lookup function has picked up
the old genbit, right before it was toggled by nf_tables_commit(), but
then the same cpu managed to unlink the matching old element from the
hash table:

cpu0					cpu1
  has added new elements to clone
  has marked elements as being
  inactive in new generation
					perform lookup in the set
  enters commit phase:
					A) observes old genbit
   increments base_seq
I) increments the genbit
II) removes old element from the set
					B) finds matching element
					C) returns no match: found
					element is not valid in old
					generation

					Next lookup observes new genbit and
					finds matching e2.

Consider a packet matching element e1, e2.

cpu0 processes following transaction:
1. remove e1
2. adds e2, which has same key as e1.

P matches both e1 and e2.  Therefore, cpu1 should always find a match
for P. Due to above race, this is not the case:

cpu1 observed the old genbit.  e2 will not be considered once it is found.
The element e1 is not found anymore if cpu0 managed to unlink it from the
hlist before cpu1 found it during list traversal.

The situation only occurs for a brief time period, lookups happening
after I) observe new genbit and return e2.

This problem exists in all set types except nft_set_pipapo, so fix it once
in nft_lookup rather than each set ops individually.

Sample the base sequence counter, which gets incremented right before the
genbit is changed.

Then, if no match is found, retry the lookup if the base sequence was
altered in between.

If the base sequence hasn't changed:
 - No update took place: no-match result is expected.
   This is the common case.  or:
 - nf_tables_commit() hasn't progressed to genbit update yet.
   Old elements were still visible and nomatch result is expected, or:
 - nf_tables_commit updated the genbit:
   We picked up the new base_seq, so the lookup function also picked
   up the new genbit, no-match result is expected.

If the old genbit was observed, then nft_lookup also picked up the old
base_seq: nft_lookup_should_retry() returns true and relookup is performed
in the new generation.

This problem was added when the unconditional synchronize_rcu() call
that followed the current/next generation bit toggle was removed.

Thanks to Pablo Neira Ayuso for reviewing an earlier version of this
patchset, for suggesting re-use of existing base_seq and placement of
the restart loop in nft_set_do_lookup().

Fixes: 0cbc06b3fa ("netfilter: nf_tables: remove synchronize_rcu in commit phase")
Signed-off-by: Florian Westphal <fw@strlen.de>
2025-09-10 20:30:37 +02:00
Florian Westphal 11fe5a82e5 netfilter: nf_tables: make nft_set_do_lookup available unconditionally
This function was added for retpoline mitigation and is replaced by a
static inline helper if mitigations are not enabled.

Enable this helper function unconditionally so next patch can add a lookup
restart mechanism to fix possible false negatives while transactions are
in progress.

Adding lookup restarts in nft_lookup_eval doesn't work as nft_objref would
then need the same copypaste loop.

This patch is separate to ease review of the actual bug fix.

Suggested-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Florian Westphal <fw@strlen.de>
2025-09-10 20:30:37 +02:00
Florian Westphal 64102d9bbc netfilter: nf_tables: place base_seq in struct net
This will soon be read from packet path around same time as the gencursor.

Both gencursor and base_seq get incremented almost at the same time, so
it makes sense to place them in the same structure.

This doesn't increase struct net size on 64bit due to padding.

Signed-off-by: Florian Westphal <fw@strlen.de>
2025-09-10 20:30:37 +02:00
Florian Westphal a60f7bf4a1 netfilter: nft_set_rbtree: continue traversal if element is inactive
When the rbtree lookup function finds a match in the rbtree, it sets the
range start interval to a potentially inactive element.

Then, after tree lookup, if the matching element is inactive, it returns
NULL and suppresses a matching result.

This is wrong and leads to false negative matches when a transaction has
already entered the commit phase.

cpu0					cpu1
  has added new elements to clone
  has marked elements as being
  inactive in new generation
					perform lookup in the set
  enters commit phase:
I) increments the genbit
					A) observes new genbit
					B) finds matching range
					C) returns no match: found
					range invalid in new generation
II) removes old elements from the tree
					C New nft_lookup happening now
				       	  will find matching element,
					  because it is no longer
					  obscured by old, inactive one.

Consider a packet matching range r1-r2:

cpu0 processes following transaction:
1. remove r1-r2
2. add r1-r3

P is contained in both ranges. Therefore, cpu1 should always find a match
for P.  Due to above race, this is not the case:

cpu1 does find r1-r2, but then ignores it due to the genbit indicating
the range has been removed.  It does NOT test for further matches.

The situation persists for all lookups until after cpu0 hits II) after
which r1-r3 range start node is tested for the first time.

Move the "interval start is valid" check ahead so that tree traversal
continues if the starting interval is not valid in this generation.

Thanks to Stefan Hanreich for providing an initial reproducer for this
bug.

Reported-by: Stefan Hanreich <s.hanreich@proxmox.com>
Fixes: c1eda3c639 ("netfilter: nft_rbtree: ignore inactive matching element with no descendants")
Signed-off-by: Florian Westphal <fw@strlen.de>
2025-09-10 20:30:37 +02:00
Florian Westphal c4eaca2e10 netfilter: nft_set_pipapo: don't check genbit from packetpath lookups
The pipapo set type is special in that it has two copies of its
datastructure: one live copy containing only valid elements and one
on-demand clone used during transaction where adds/deletes happen.

This clone is not visible to the datapath.

This is unlike all other set types in nftables, those all link new
elements into their live hlist/tree.

For those sets, the lookup functions must skip the new elements while the
transaction is ongoing to ensure consistency.

As the clone is shallow, removal does have an effect on the packet path:
once the transaction enters the commit phase the 'gencursor' bit that
determines which elements are active and which elements should be ignored
(because they are no longer valid) is flipped.

This causes the datapath lookup to ignore these elements if they are found
during lookup.

This opens up a small race window where pipapo has an inconsistent view of
the dataset from when the transaction-cpu flipped the genbit until the
transaction-cpu calls nft_pipapo_commit() to swap live/clone pointers:

cpu0					cpu1
  has added new elements to clone
  has marked elements as being
  inactive in new generation
					perform lookup in the set
  enters commit phase:

I) increments the genbit
					A) observes new genbit
  removes elements from the clone so
  they won't be found anymore
					B) lookup in datastructure
					   can't see new elements yet,
					   but old elements are ignored
					   -> Only matches elements that
					   were not changed in the
					   transaction
II) calls nft_pipapo_commit(), clone
    and live pointers are swapped.
					C New nft_lookup happening now
				       	  will find matching elements.

Consider a packet matching range r1-r2:

cpu0 processes following transaction:
1. remove r1-r2
2. add r1-r3

P is contained in both ranges. Therefore, cpu1 should always find a match
for P.  Due to above race, this is not the case:

cpu1 does find r1-r2, but then ignores it due to the genbit indicating
the range has been removed.

At the same time, r1-r3 is not visible yet, because it can only be found
in the clone.

The situation persists for all lookups until after cpu0 hits II).

The fix is easy: Don't check the genbit from pipapo lookup functions.
This is possible because unlike the other set types, the new elements are
not reachable from the live copy of the dataset.

The clone/live pointer swap is enough to avoid matching on old elements
while at the same time all new elements are exposed in one go.

After this change, step B above returns a match in r1-r2.
This is fine: r1-r2 only becomes truly invalid the moment they get freed.
This happens after a synchronize_rcu() call and rcu read lock is held
via netfilter hook traversal (nf_hook_slow()).

Cc: Stefano Brivio <sbrivio@redhat.com>
Fixes: 3c4287f620 ("nf_tables: Add set type for arbitrary concatenation of ranges")
Signed-off-by: Florian Westphal <fw@strlen.de>
2025-09-10 20:30:37 +02:00
Florian Westphal 5e13f2c491 netfilter: nft_set_bitmap: fix lockdep splat due to missing annotation
Running new 'set_flush_add_atomic_bitmap' test case for nftables.git
with CONFIG_PROVE_RCU_LIST=y yields:

net/netfilter/nft_set_bitmap.c:231 RCU-list traversed in non-reader section!!
rcu_scheduler_active = 2, debug_locks = 1
1 lock held by nft/4008:
 #0: ffff888147f79cd8 (&nft_net->commit_mutex){+.+.}-{4:4}, at: nf_tables_valid_genid+0x2f/0xd0

 lockdep_rcu_suspicious+0x116/0x160
 nft_bitmap_walk+0x22d/0x240
 nf_tables_delsetelem+0x1010/0x1a00
 ..

This is a false positive, the list cannot be altered while the
transaction mutex is held, so pass the relevant argument to the iterator.

Fixes tag intentionally wrong; no point in picking this up if earlier
false-positive-fixups were not applied.

Fixes: 28b7a6b84c ("netfilter: nf_tables: avoid false-positive lockdep splats in set walker")
Signed-off-by: Florian Westphal <fw@strlen.de>
2025-09-10 20:28:24 +02:00