linux.git/net/netfilter/nft_objref.c, branch v7.0 Linux kernel source tree netfilter: nft_objref: validate objref and objrefmap expressions 2025-10-08T11:17:25+00:00 Fernando Fernandez Mancera fmancera@suse.de 2025-10-08T10:08:16+00:00 f359b809d54c6e3dd1d039b97e0b68390b0e53e4 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: ee394f96ad75 ("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> 
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: ee394f96ad75 ("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>
netfilter: nft_set: remove one argument from lookup and update functions 2025-07-25T16:40:16+00:00 Florian Westphal fw@strlen.de 2025-07-09T17:05:13+00:00 17a20e09f086f2c574ac87f3cf6e14c4377f65f6 Return the extension pointer instead of passing it as a function argument to be filled in by the callee. As-is, whenever false is returned, the extension pointer is not used. For all set types, when true is returned, the extension pointer was set to the matching element. Only exception: nft_set_bitmap doesn't support extensions. Return a pointer to a static const empty element extension container. return false -> return NULL return true -> return the elements' extension pointer. This saves one function argument. Signed-off-by: Florian Westphal <fw@strlen.de> Reviewed-by: Stefano Brivio <sbrivio@redhat.com> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org> 
Return the extension pointer instead of passing it as a function
argument to be filled in by the callee.

As-is, whenever false is returned, the extension pointer is not used.

For all set types, when true is returned, the extension pointer was set
to the matching element.

Only exception: nft_set_bitmap doesn't support extensions.
Return a pointer to a static const empty element extension container.

return false -> return NULL
return true -> return the elements' extension pointer.

This saves one function argument.

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: nf_tables: pass context structure to nft_parse_register_load 2024-08-20T10:37:24+00:00 Florian Westphal fw@strlen.de 2024-08-20T09:56:12+00:00 7ea0522ef81a335c2d3a0ab1c8a4fab9a23c4a03 Mechanical transformation, no logical changes intended. Signed-off-by: Florian Westphal <fw@strlen.de> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org> 
Mechanical transformation, no logical changes intended.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
netfilter: nf_tables: report use refcount overflow 2023-07-05T12:42:15+00:00 Pablo Neira Ayuso pablo@netfilter.org 2023-06-28T14:24:27+00:00 1689f25924ada8fe14a4a82c38925d04994c7142 Overflow use refcount checks are not complete. Add helper function to deal with object reference counter tracking. Report -EMFILE in case UINT_MAX is reached. nft_use_dec() splats in case that reference counter underflows, which should not ever happen. Add nft_use_inc_restore() and nft_use_dec_restore() which are used to restore reference counter from error and abort paths. Use u32 in nft_flowtable and nft_object since helper functions cannot work on bitfields. Remove the few early incomplete checks now that the helper functions are in place and used to check for refcount overflow. Fixes: 96518518cc41 ("netfilter: add nftables") Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org> 
Overflow use refcount checks are not complete.

Add helper function to deal with object reference counter tracking.
Report -EMFILE in case UINT_MAX is reached.

nft_use_dec() splats in case that reference counter underflows,
which should not ever happen.

Add nft_use_inc_restore() and nft_use_dec_restore() which are used
to restore reference counter from error and abort paths.

Use u32 in nft_flowtable and nft_object since helper functions cannot
work on bitfields.

Remove the few early incomplete checks now that the helper functions
are in place and used to check for refcount overflow.

Fixes: 96518518cc41 ("netfilter: add nftables")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
netfilter: nf_tables: deactivate anonymous set from preparation phase 2023-05-03T06:24:32+00:00 Pablo Neira Ayuso pablo@netfilter.org 2023-05-02T08:25:24+00:00 c1592a89942e9678f7d9c8030efa777c0d57edab Toggle deleted anonymous sets as inactive in the next generation, so users cannot perform any update on it. Clear the generation bitmask in case the transaction is aborted. The following KASAN splat shows a set element deletion for a bound anonymous set that has been already removed in the same transaction. [ 64.921510] ================================================================== [ 64.923123] BUG: KASAN: wild-memory-access in nf_tables_commit+0xa24/0x1490 [nf_tables] [ 64.924745] Write of size 8 at addr dead000000000122 by task test/890 [ 64.927903] CPU: 3 PID: 890 Comm: test Not tainted 6.3.0+ #253 [ 64.931120] Call Trace: [ 64.932699] <TASK> [ 64.934292] dump_stack_lvl+0x33/0x50 [ 64.935908] ? nf_tables_commit+0xa24/0x1490 [nf_tables] [ 64.937551] kasan_report+0xda/0x120 [ 64.939186] ? nf_tables_commit+0xa24/0x1490 [nf_tables] [ 64.940814] nf_tables_commit+0xa24/0x1490 [nf_tables] [ 64.942452] ? __kasan_slab_alloc+0x2d/0x60 [ 64.944070] ? nf_tables_setelem_notify+0x190/0x190 [nf_tables] [ 64.945710] ? kasan_set_track+0x21/0x30 [ 64.947323] nfnetlink_rcv_batch+0x709/0xd90 [nfnetlink] [ 64.948898] ? nfnetlink_rcv_msg+0x480/0x480 [nfnetlink] Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org> 
Toggle deleted anonymous sets as inactive in the next generation, so
users cannot perform any update on it. Clear the generation bitmask
in case the transaction is aborted.

The following KASAN splat shows a set element deletion for a bound
anonymous set that has been already removed in the same transaction.

[   64.921510] ==================================================================
[   64.923123] BUG: KASAN: wild-memory-access in nf_tables_commit+0xa24/0x1490 [nf_tables]
[   64.924745] Write of size 8 at addr dead000000000122 by task test/890
[   64.927903] CPU: 3 PID: 890 Comm: test Not tainted 6.3.0+ #253
[   64.931120] Call Trace:
[   64.932699]  <TASK>
[   64.934292]  dump_stack_lvl+0x33/0x50
[   64.935908]  ? nf_tables_commit+0xa24/0x1490 [nf_tables]
[   64.937551]  kasan_report+0xda/0x120
[   64.939186]  ? nf_tables_commit+0xa24/0x1490 [nf_tables]
[   64.940814]  nf_tables_commit+0xa24/0x1490 [nf_tables]
[   64.942452]  ? __kasan_slab_alloc+0x2d/0x60
[   64.944070]  ? nf_tables_setelem_notify+0x190/0x190 [nf_tables]
[   64.945710]  ? kasan_set_track+0x21/0x30
[   64.947323]  nfnetlink_rcv_batch+0x709/0xd90 [nfnetlink]
[   64.948898]  ? nfnetlink_rcv_msg+0x480/0x480 [nfnetlink]

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
netfilter: nf_tables: avoid retpoline overhead for objref calls 2023-01-18T12:05:25+00:00 Florian Westphal fw@strlen.de 2023-01-03T12:47:16+00:00 2032e907d8d498fcabfe24b43550c50947817c6d objref expression is builtin, so avoid calls to it for RETOLINE=y builds. Signed-off-by: Florian Westphal <fw@strlen.de> 
objref expression is builtin, so avoid calls to it for
RETOLINE=y builds.

Signed-off-by: Florian Westphal <fw@strlen.de>
netfilter: nf_tables: Extend nft_expr_ops::dump callback parameters 2022-11-15T09:46:34+00:00 Phil Sutter phil@nwl.cc 2022-10-14T21:45:58+00:00 7d34aa3e03b6a56306296bd98b26c6a1710cd57b Add a 'reset' flag just like with nft_object_ops::dump. This will be useful to reset "anonymous stateful objects", e.g. simple rule counters. No functional change intended. Signed-off-by: Phil Sutter <phil@nwl.cc> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org> 
Add a 'reset' flag just like with nft_object_ops::dump. This will be
useful to reset "anonymous stateful objects", e.g. simple rule counters.

No functional change intended.

Signed-off-by: Phil Sutter <phil@nwl.cc>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
netfilter: nft_objref: make it builtin 2022-10-25T11:48:35+00:00 Florian Westphal fw@strlen.de 2022-10-21T14:17:53+00:00 d037abc2414b4539401e0e6aa278bedc4628ad69 nft_objref is needed to reference named objects, it makes no sense to disable it. Before: text data bss dec filename 4014 424 0 4438 nft_objref.o 4174 1128 0 5302 nft_objref.ko 359351 15276 864 375491 nf_tables.ko After: text data bss dec filename 3815 408 0 4223 nft_objref.o 363161 15692 864 379717 nf_tables.ko Signed-off-by: Florian Westphal <fw@strlen.de> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org> 
nft_objref is needed to reference named objects, it makes
no sense to disable it.

Before:
   text	   data	    bss	    dec	 filename
  4014	    424	      0	   4438	 nft_objref.o
  4174	   1128	      0	   5302	 nft_objref.ko
359351	  15276	    864	 375491	 nf_tables.ko
After:
  text	   data	    bss	    dec	 filename
  3815	    408	      0	   4223	 nft_objref.o
363161	  15692	    864	 379717	 nf_tables.ko

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
netfilter: nf_tables: do not reduce read-only expressions 2022-03-19T23:29:46+00:00 Pablo Neira Ayuso pablo@netfilter.org 2022-03-14T17:23:00+00:00 b2d306542ff935a4edf7a88ba8145c108193442a Skip register tracking for expressions that perform read-only operations on the registers. Define and use a cookie pointer NFT_REDUCE_READONLY to avoid defining stubs for these expressions. This patch re-enables register tracking which was disabled in ed5f85d42290 ("netfilter: nf_tables: disable register tracking"). Follow up patches add remaining register tracking for existing expressions. Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org> 
Skip register tracking for expressions that perform read-only operations
on the registers. Define and use a cookie pointer NFT_REDUCE_READONLY to
avoid defining stubs for these expressions.

This patch re-enables register tracking which was disabled in ed5f85d42290
("netfilter: nf_tables: disable register tracking"). Follow up patches
add remaining register tracking for existing expressions.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
netfilter: add and use nft_set_do_lookup helper 2021-05-28T19:11:41+00:00 Florian Westphal fw@strlen.de 2021-05-13T20:29:55+00:00 0974cff3eb66764cc86b60f1071958acc432a4e8 Followup patch will add a CONFIG_RETPOLINE wrapper to avoid the ops->lookup() indirection cost for retpoline builds. Signed-off-by: Florian Westphal <fw@strlen.de> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org> 
Followup patch will add a CONFIG_RETPOLINE wrapper to avoid
the ops->lookup() indirection cost for retpoline builds.

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