Pablo Neira Ayuso says:
====================
Netfilter fixes for net
The following patchset contains Netfilter fixes for net:
1) Use DEBUG_NET_WARN_ON_ONCE() instead of WARN_ON() from the tproxy
datapath, a recent bug found a way to reach WARN_ON from datapath
due to insufficient validation of xt_TPROTO checkentry.
From Fernando F. Mancera.
2) Similar to previous patch to replace WARN_ON_ONCE by
DEBUG_NET_WARN_ON_ONCE() for connlimit. Not known issue, but
since this patch has been around for a while, let's merge it.
Also from Fernando.
3) Move nf_tables harware offload commit path after chain blob
and audit to reduce chances of leaving the hardware in
inconsistent state.
4) Add missing vzeroupper to nf_tables pipapo AVX2 to address
performace degradation to later user of SSE code,
from Eric Biggers.
5) Remove pr_debug() in x_tables extensions, a recent bogus found a
way to print a unsanitized string in xt_IDLETIMER, many of these
pr_debug() calls are there for historical reasons.
6) Use pr_info_ratelimited() in x_tables .checkentry.
7) Fix an imbalance in module refcount due to incorrect override
expression logic with sets. Remove unnecessary clone in control
plane, use the existing expressions provided by set or dynset
expression. Release override expressions only.
8) Tigthen nf_tables device name removal, it is possible to remove
prefix strings with exact device name. From Fernando F. Mancera.
9) Set on the set dead bit earlier, otherwise it is possible to
call .commit on deleted sets. This also addresses the
re-introduction of a bug.
* tag 'nf-26-08-27' of git://git.kernel.org/pub/scm/linux/kernel/git/netfilter/nf:
netfilter: nf_tables: remove leftover set_update_list
netfilter: nf_tables: set on dead bit when performing early element removal
netfilter: nf_tables: skip double clone set expressions on element insert
netfilter: x_tables: replace pr_{info,err}() by pr_info_ratelimited()
netfilter: x_tables: remove pr_debug
netfilter: nft_set_pipapo_avx2: add missing vzeroupper
netfilter: nf_tables: move hardware offload step after building the chain blob
netfilter: conncount: use DEBUG_NET_WARN_ON_ONCE on reaching count limit
netfilter: tproxy: use DEBUG_NET_WARN_ON_ONCE for protocol fallbacks
====================
Link: https://patch.msgid.link/20260827141733.423453-1-pablo@netfilter.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
A virtio_net_hdr (tun/tap, or AF_PACKET with PACKET_VNET_HDR) can mark
an IPv4 or IPv6 fragment as GSO; nothing relates gso_type to frag_off.
inet_frag_reasm_prepare()/inet_frag_reasm_finish() keep the first
fragment's skb as the head of the reassembled datagram, including its
shinfo->gso_size/gso_type/gso_segs, and chain the remaining fragments
on frag_list with whatever linear/paged layout they arrived with.
After ip_defrag() (ip_local_deliver(), nf_defrag_ipv4, ...) the
reassembled skb therefore still claims to be GSO (SKB_GSO_DODGY), and
the next software segmentation point - udp_rcv_segment() on local
delivery, validate_xmit_skb(), or the ip_finish_output_gso() slow
path - hands it to skb_segment(). skb_segment()'s frag_list walk
assumes GRO-shaped input and hits one of its BUG_ON()s. Two writes to
a tap by an unprivileged user in its own userns are enough:
kernel BUG at net/core/skbuff.c:4899!
Oops: invalid opcode: 0000 [#1] SMP KASAN NOPTI
CPU: 0 UID: 1000 PID: 82 Comm: poc Not tainted 7.2.0-pentest+ #2
RIP: 0010:skb_segment+0x20ca/0x48b0
Call Trace:
<TASK>
__udp_gso_segment+0x29a/0x27d0
udp4_ufo_fragment+0x458/0x6c0
inet_gso_segment+0x429/0x1340
skb_mac_gso_segment+0x233/0x4f0
__skb_gso_segment+0x308/0x660
udp_queue_rcv_skb+0x440/0xad0
udp_unicast_rcv_skb+0xc7/0x2c0
udp_rcv+0x16ce/0x2260
ip_protocol_deliver_rcu+0x197/0x2d0
ip_local_deliver+0x430/0x690
ip_rcv+0x16f/0x1f0
__netif_receive_skb_one_core+0x15e/0x1c0
__netif_receive_skb+0x1e/0x110
netif_receive_skb+0xf6/0x5c0
tun_rx_batched.isra.0+0x3ab/0x790
tun_get_user+0x17c3/0x3550
tun_chr_write_iter+0xba/0x1b0
vfs_write+0x646/0x1130
</TASK>
Kernel panic - not syncing: Fatal exception in interrupt
This runs with BH disabled, so it is a panic rather than an oops. The
same is reachable with CAP_NET_RAW in a netns where a defrag point
precedes a GSO point, and from a guest whose VMM forwards
virtio_net_hdr to a tap. The SKB_GSO_DODGY frag_list checks added by
commit 3dcbdb134f32 ("net: gso: Fix skb_segment splat when splitting
gso_size mangled skb having linear-headed frag_list") and by
commit 9e4b7a99a03a ("net: gso: fix panic on frag_list with mixed head
alloc types") do not cover it: page-backed heads skip them, and kmalloc
heads skip them when gso_size == skb_headlen(head), which the sender
controls.
An skb entering a frag queue is an IP fragment by definition and
cannot legitimately carry GSO state: GRO does not merge fragments and
the stack segments before it fragments, so only untrusted sources are
affected. This has been reachable since
commit f43798c27684 ("tun: Allow GSO using virtio_net_hdr"), the first
path that let userspace attach GSO metadata to an IP fragment. Reset
the GSO fields of every fragment as it is queued, in
inet_frag_queue_insert(), which IPv4, IPv6, nf_conntrack_reasm and
6lowpan reassembly share; then neither the head nor the frag_list
members of the reassembled skb carry them (the members matter too:
the ip_do_fragment()/ip6_fragment() fast paths send them out as they
are). The head may remain CHECKSUM_PARTIAL; that is already accepted
on receive and resolved by skb_checksum_help() in
ip_do_fragment()/ip6_fragment() on forward.
Tested on top of net.git (dc4b95b8fee9), x86_64: the tap reproducer
above, two further IPv4 frag_list geometries that reach
BUG_ON(i >= nfrags) and BUG_ON(!list_skb->head_frag), and an IPv6
fragment-header variant (udp6_ufo_fragment()) each panic the unpatched
kernel; with this patch all four datagrams are delivered intact and
nothing is logged.
Fixes: f43798c27684 ("tun: Allow GSO using virtio_net_hdr")
Cc: stable@kernel.org
Suggested-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Xinyang Ge <xinyang@anthropic.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/937926e509f2acd8e0e66520dc2b30fd6b4d1687.1787839506.git.pabeni@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
On the normal xmit path, while in urgent mode we refuse to build a
multi-segment TSO packet, so every segment gets its own urg_ptr:
/* tcp_write_xmit() */
limit = mss_now;
if (tso_segs > 1 && !tcp_urg_mode(tp))
limit = tcp_mss_split_point(...);
The retransmit path has no such guard. __tcp_retransmit_skb() builds a
segs > 1 skb and hands it to the GSO layer, which only advances th->seq
per segment and copies urg_ptr verbatim:
/* __tcp_retransmit_skb() */
len = cur_mss * segs; /* segs > 1, no urg_mode check */
...
/* tcp_gso_segment(): bumps seq only, urg_ptr is copied */
urg_ptr is an offset from the segment's own seq, so a copied value points
at a different place on each segment. The receiver rebuilds the absolute
urgent seq as seg.seq + urg_ptr, so it walks a moving urgent point instead
of the one OOB byte:
seg1 seq 1 urg_ptr 5001 -> urgent @ 5001 (ok)
seg2 seq 1001 urg_ptr 5001 -> urgent @ 6001 (wrong, +MSS)
seg3 seq 2001 urg_ptr 5001 -> urgent @ 7001 (wrong, +2*MSS)
The real OOB byte is never pointed at, so the receiver stops splicing it
out and delivers it as normal in-band data, corrupting the stream.
Guard the retransmit length like the xmit path: keep segs = 1 while in
urgent mode.
Fixes: 10d3be569243 ("tcp-tso: do not split TSO packets at retransmit time")
Signed-off-by: Jiayuan Chen <jiayuan.chen@linux.dev>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20260826141145.67823-1-jiayuan.chen@linux.dev
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Remove pr_debug() for these xtables extensions, these have no use these days. Still, turn pr_debug() into pr_info_ratelimited() in the .checkentry path since this helps provide a hint via dmesg in legacy iptables. Exception is xt_IDLETIMER in the module init path, where pr_err() is used. Add missing pr_fmt() definition in xt_REDIRECT, xt_NETMAP and xt_MASQUERADE. Add missing \n to several pr_debug() that were translated to use pr_info_ratelimited(). Link: https://patch.msgid.link/cover.1786933680.git.rakukuip@gmail.com/ Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Replace WARN_ON calls with DEBUG_NET_WARN_ON_ONCE in the default switch blocks of nf_tproxy_get_sock_v4 and v6. Unsupported transport protocols are already safely handled by returning a NULL socket pointer. This prevents unnecessary system panics when panic_on_warn=1 is enabled in production systems. Link: https://patch.msgid.link/cover.1786968834.git.zhilinz@nebusec.ai/ Signed-off-by: Fernando Fernandez Mancera <fmancera@suse.de> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
tcp_v4_connect() adds a SYN-SENT socket to the ehash before calling
tcp_connect(). If TCP-AO is configured, tcp_connect() first verifies that
a key matches the peer and the bound device's current L3 master.
tcp_ao_connect_init() later resolves the L3 master again and removes keys
which do not match it.
The socket lock does not stabilize the bound device's VRF membership.
Detaching the device from its VRF between the initial validation and the
L3-master calculation in tcp_ao_connect_init() can therefore make the
validation succeed while initialization observes the default L3 domain and
removes the only key. The subsequent AO lookup then fails, so the no-key
path clears tp->ao_info and frees it directly.
The receive path can find the socket in the ehash and load tp->ao_info
under RCU before acquiring the socket lock. A reader which loaded the old
pointer can thus continue into tcp_inbound_ao_hash() after the direct free.
The issue was found during a static audit of TCP-AO object lifetime. An
unprivileged reproducer in self-created user and network namespaces raced
connect() with detaching a veth from its VRF while sending TCP-AO segments.
It triggered the same KASAN report on two fresh boots:
BUG: KASAN: slab-use-after-free in tcp_inbound_ao_hash+0x585/0x19f0
Write of size 8 at addr ffff88800bf88128 by task tcp_ao_vrf_race/232
Call Trace:
tcp_inbound_ao_hash+0x585/0x19f0
tcp_inbound_hash+0x677/0xa80
tcp_v4_rcv+0x1c3e/0x3ab0
Allocated by task 235:
tcp_ao_alloc_info+0x43/0xf0
tcp_ao_add_cmd+0xdf7/0x13b0
do_tcp_setsockopt+0x168c/0x2640
Freed by task 235:
kfree+0x1b8/0x550
tcp_connect+0x252/0x4f00
tcp_v4_connect+0x1114/0x1720
The bad address is 40 bytes inside the freed 128-byte object, matching the
tcp_ao_info counters.key_not_found field. The two runs used 1000 attempts
each, reached the no-key path 366 and 411 times, and produced one and two
KASAN reports respectively. With this change, the same reproducer reached
the no-key path 366 times in 1000 attempts without a KASAN report or oops.
Use tcp_ao_destroy_sock() for the no-key path. It unpublishes the AO info,
updates the socket memory and static-key accounting, and defers the free
until after an RCU grace period.
Also drop the WARN_ON_ONCE() and its stale comment. The VRF detach race
makes the no-key state reachable during normal operation, so it is a
handled condition rather than an impossible assertion. On panic_on_warn
kernels the WARN would turn this handled race into a kernel panic.
Fixes: 248411b8cb89 ("net/tcp: Wire up l3index to TCP-AO")
Cc: stable@vger.kernel.org
Assisted-by: Codex:gpt-5
Signed-off-by: Qing Ming <a0yami@mailbox.org>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20260825072033.6921-1-a0yami@mailbox.org
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
TCP-AO keys with TCP_AO_KEYF_IFINDEX store the VRF L3 interface index in
l3index. tcp_ao_del_cmd() validates the supplied ifindex, but does not
assign it to its local l3index before matching keys.
As a result, deleting a key scoped to a non-default VRF always fails with
ENOENT because it is matched against l3index 0.
Fixes: 248411b8cb89 ("net/tcp: Wire up l3index to TCP-AO")
Cc: stable@vger.kernel.org
Signed-off-by: Rastislav Szabo <rastislav.szabo@isovalent.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Acked-by: Dmitry Safonov <0x7f454c46@gmail.com>
Link: https://patch.msgid.link/20260822201119.272269-1-rastislav.szabo@isovalent.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
tcp_select_initial_window() assumes that callers never pass an MSS
smaller than 1, but route-derived advmss values can violate that
assumption.
A too-small explicit RTAX_ADVMSS is one way to get there, but it is not
the only one. The same divide-by-zero can also be reached through the
"default advmss" path when RTAX_ADVMSS is left at 0 and the effective
advmss is later driven down by route MTU and min_adv_mss.
Introduce a tcp_dst_advmss() helper that clamps route advmss to
TCP_MIN_MSS before TCP consumes it, and use it in the TCP paths that
derive advmss from dst metrics. This keeps the effective MSS from
dropping to zero before tcp_select_initial_window() rounds the receive
window.
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Cc: stable@vger.kernel.org
Reported-by: Vega <vega@nebusec.ai>
Signed-off-by: Yong Wang <edragain@163.com>
Signed-off-by: Ren Wei <weir@nebusec.ai>
Link: https://patch.msgid.link/251eaf8277fa7c66364c9815c5da01662d269181.1787074852.git.edragain@163.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
In collect_md mode ipip_tunnel_rcv() returns 0 without freeing the skb
when ip_tun_rx_dst() fails to allocate the metadata_dst. ipip_rcv() and
mplsip_rcv() are registered as xfrm_tunnel handlers, so tunnel4_rcv()
and tunnelmpls4_rcv() read the zero return as "the packet has been
consumed" and do not free it either. The skb is leaked.
The other tunnel drivers all dispose of the packet at this point:
ip6_tunnel.c jumps to its drop label, ip_gre.c and ip6_gre.c return
PACKET_REJECT, which makes gre_rcv() free the skb. Only ipip returns 0.
Jump to the existing drop label instead. It frees the skb and still
returns 0, so the packet keeps being reported as consumed, which is what
we want here: the outer header has already been pulled, and neither the
remaining handlers nor an ICMP unreachable have any use for it.
Triggering this needs an ipip or mplsip tunnel in collect_md mode and an
atomic allocation failure, which is why it has gone unnoticed.
Fixes: cfc7381b3002 ("ip_tunnel: add collect_md mode to IPIP tunnel")
Cc: stable@vger.kernel.org
Signed-off-by: Anton Danilov <littlesmilingcloud@gmail.com>
Reviewed-by: Fernando Fernandez Mancera <fmancera@suse.de>
Link: https://patch.msgid.link/20260819104338.432631-2-littlesmilingcloud@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Protect tcp_sendmsg_locked() from mistakenly mixing readable and
unreadable page fragments in the same SKB.
Check that the devmem binding matches the existing SKB's readability.
If a mismatch is detected, avoid collapsing and create a new segment.
Fixes: bd61848900bff ("net: devmem: Implement TX path")
Suggested-by: Eric Dumazet <edumazet@google.com>
Cc: Pavel Begunkov <asml.silence@gmail.com>
Cc: Stanislav Fomichev <sdf@fomichev.me>
Cc: Bobby Eshleman <bobbyeshleman@gmail.com>
Signed-off-by: Mina Almasry <almasrymina@google.com>
Link: https://patch.msgid.link/20260814191336.187243-2-almasrymina@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>