This reverts 28ee1b746f49 ("secure_seq: downgrade to per-host timestamp offsets")

tcp_tw_recycle went away in 2017.

Zhouyan Deng reported off-path TCP source port leakage via
SYN cookie side-channel that can be fixed in multiple ways.

One of them is to bring back TCP ports in TS offset randomization.

As a bonus, we perform a single siphash() computation
to provide both an ISN and a TS offset.

Fixes: 28ee1b746f49 ("secure_seq: downgrade to per-host timestamp offsets")
Reported-by: Zhouyan Deng <dengzhouyan_nwpu@163.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@google.com>
Acked-by: Florian Westphal <fw@strlen.de>
Link: https://patch.msgid.link/20260302205527.1982836-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

To prevent timing attacks, MACs need to be compared in constant
time.  Use the appropriate helper function for this.

Fixes: cfb6eeb4c860 ("[TCP]: MD5 Signature Option (RFC2385) support.")
Fixes: 658ddaaf6694 ("tcp: md5: RST: getting md5 key from listener")
Cc: stable@vger.kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
Link: https://patch.msgid.link/20260302203409.13388-1-ebiggers@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

`struct sysctl_fib_multipath_hash_seed` contains two u32 fields
(user_seed and mp_seed), making it an 8-byte structure with a 4-byte
alignment requirement.

In `fib_multipath_hash_from_keys()`, the code evaluates the entire
struct atomically via `READ_ONCE()`:

    mp_seed = READ_ONCE(net->ipv4.sysctl_fib_multipath_hash_seed).mp_seed;

While this silently works on GCC by falling back to unaligned regular
loads which the ARM64 kernel tolerates, it causes a fatal kernel panic
when compiled with Clang and LTO enabled.

Commit e35123d83ee3 ("arm64: lto: Strengthen READ_ONCE() to acquire
when CONFIG_LTO=y") strengthens `READ_ONCE()` to use Load-Acquire
instructions (`ldar` / `ldapr`) to prevent compiler reordering bugs
under Clang LTO. Since the macro evaluates the full 8-byte struct,
Clang emits a 64-bit `ldar` instruction. ARM64 architecture strictly
requires `ldar` to be naturally aligned, thus executing it on a 4-byte
aligned address triggers a strict Alignment Fault (FSC = 0x21).

Fix the read side by moving the `READ_ONCE()` directly to the `u32`
member, which emits a safe 32-bit `ldar Wn`.

Furthermore, Eric Dumazet pointed out that `WRITE_ONCE()` on the entire
struct in `proc_fib_multipath_hash_set_seed()` is also flawed. Analysis
shows that Clang splits this 8-byte write into two separate 32-bit
`str` instructions. While this avoids an alignment fault, it destroys
atomicity and exposes a tear-write vulnerability. Fix this by
explicitly splitting the write into two 32-bit `WRITE_ONCE()`
operations.

Finally, add the missing `READ_ONCE()` when reading `user_seed` in
`proc_fib_multipath_hash_seed()` to ensure proper pairing and
concurrency safety.

Fixes: 4ee2a8cace3f ("net: ipv4: Add a sysctl to set multipath hash seed")
Signed-off-by: Yung Chih Su <yuuchihsu@gmail.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20260302060247.7066-1-yuuchihsu@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

To prevent timing attacks, MACs need to be compared in constant
time.  Use the appropriate helper function for this.

Fixes: 0a3a809089eb ("net/tcp: Verify inbound TCP-AO signed segments")
Cc: stable@vger.kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
Reviewed-by: Dmitry Safonov <0x7f454c46@gmail.com>
Link: https://patch.msgid.link/20260302203600.13561-1-ebiggers@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

We hit another corner case which leads to TcpExtTCPRcvQDrop

Connections which send RPCs in the 20-80kB range over loopback
experience spurious drops. The exact conditions for most of
the drops I investigated are that:
 - socket exchanged >1MB of data so its not completely fresh
 - rcvbuf is around 128kB (default, hasn't grown)
 - there is ~60kB of data in rcvq
 - skb > 64kB arrives

The sum of skb->len (!) of both of the skbs (the one already
in rcvq and the arriving one) is larger than rwnd.
My suspicion is that this happens because __tcp_select_window()
rounds the rwnd up to (1 << wscale) if less than half of
the rwnd has been consumed.

Eric suggests that given the number of Fixes we already have
pointing to 1d2fbaad7cd8 it's probably time to give up on it,
until a bigger revamp of rmem management.

Also while we could risk tweaking the rwnd math, there are other
drops on workloads I investigated, after the commit in question,
not explained by this phenomenon.

Suggested-by: Eric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/20260225122355.585fd57b@kernel.org
Fixes: 1d2fbaad7cd8 ("tcp: stronger sk_rcvbuf checks")
Reviewed-by: Kuniyuki Iwashima <kuniyu@google.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20260227003359.2391017-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Let's say we bind() an UDP socket to the wildcard address with a
non-zero port, connect() it to an address, and disconnect it from
the address.

bind() sets SOCK_BINDPORT_LOCK on sk->sk_userlocks (but not
SOCK_BINDADDR_LOCK), and connect() calls udp_lib_hash4() to put
the socket into the 4-tuple hash table.

Then, __udp_disconnect() calls sk->sk_prot->rehash(sk).

It computes a new hash based on the wildcard address and moves
the socket to a new slot in the 4-tuple hash table, leaving a
garbage in the chain that no packet hits.

Let's remove such a socket from 4-tuple hash table when disconnected.

Note that udp_sk(sk)->udp_portaddr_hash needs to be udpated after
udp_hash4_dec(hslot2) in udp_unhash4().

Fixes: 78c91ae2c6de ("ipv4/udp: Add 4-tuple hash for connected socket")
Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20260227035547.3321327-1-kuniyu@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

UDP/TCP lookups are using RCU, thus isk->inet_num accesses
should use READ_ONCE() and WRITE_ONCE() where needed.

Fixes: 3ab5aee7fe84 ("net: Convert TCP & DCCP hash tables to use RCU / hlist_nulls")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@google.com>
Link: https://patch.msgid.link/20260225203545.1512417-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

skmsg (and probably other layers) are changing these pointers
while other cpus might read them concurrently.

Add corresponding READ_ONCE()/WRITE_ONCE() annotations
for UDP, TCP and AF_UNIX.

Fixes: 604326b41a6f ("bpf, sockmap: convert to generic sk_msg interface")
Reported-by: syzbot+87f770387a9e5dc6b79b@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/netdev/699ee9fc.050a0220.1cd54b.0009.GAE@google.com/
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: John Fastabend <john.fastabend@gmail.com>
Cc: Jakub Sitnicki <jakub@cloudflare.com>
Cc: Willem de Bruijn <willemdebruijn.kernel@gmail.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@google.com>
Link: https://patch.msgid.link/20260225131547.1085509-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Pull networking fixes from Paolo Abeni:
 "Including fixes from IPsec, Bluetooth and netfilter

  Current release - regressions:

   - wifi: fix dev_alloc_name() return value check

   - rds: fix recursive lock in rds_tcp_conn_slots_available

  Current release - new code bugs:

   - vsock: lock down child_ns_mode as write-once

  Previous releases - regressions:

   - core:
      - do not pass flow_id to set_rps_cpu()
      - consume xmit errors of GSO frames

   - netconsole: avoid OOB reads, msg is not nul-terminated

   - netfilter: h323: fix OOB read in decode_choice()

   - tcp: re-enable acceptance of FIN packets when RWIN is 0

   - udplite: fix null-ptr-deref in __udp_enqueue_schedule_skb().

   - wifi: brcmfmac: fix potential kernel oops when probe fails

   - phy: register phy led_triggers during probe to avoid AB-BA deadlock

   - eth:
      - bnxt_en: fix deleting of Ntuple filters
      - wan: farsync: fix use-after-free bugs caused by unfinished tasklets
      - xscale: check for PTP support properly

  Previous releases - always broken:

   - tcp: fix potential race in tcp_v6_syn_recv_sock()

   - kcm: fix zero-frag skb in frag_list on partial sendmsg error

   - xfrm:
      - fix race condition in espintcp_close()
      - always flush state and policy upon NETDEV_UNREGISTER event

   - bluetooth:
      - purge error queues in socket destructors
      - fix response to L2CAP_ECRED_CONN_REQ

   - eth:
      - mlx5:
         - fix circular locking dependency in dump
         - fix "scheduling while atomic" in IPsec MAC address query
      - gve: fix incorrect buffer cleanup for QPL
      - team: avoid NETDEV_CHANGEMTU event when unregistering slave
      - usb: validate USB endpoints"

* tag 'net-7.0-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net: (72 commits)
  netfilter: nf_conntrack_h323: fix OOB read in decode_choice()
  dpaa2-switch: validate num_ifs to prevent out-of-bounds write
  net: consume xmit errors of GSO frames
  vsock: document write-once behavior of the child_ns_mode sysctl
  vsock: lock down child_ns_mode as write-once
  selftests/vsock: change tests to respect write-once child ns mode
  net/mlx5e: Fix "scheduling while atomic" in IPsec MAC address query
  net/mlx5: Fix missing devlink lock in SRIOV enable error path
  net/mlx5: E-switch, Clear legacy flag when moving to switchdev
  net/mlx5: LAG, disable MPESW in lag_disable_change()
  net/mlx5: DR, Fix circular locking dependency in dump
  selftests: team: Add a reference count leak test
  team: avoid NETDEV_CHANGEMTU event when unregistering slave
  net: mana: Fix double destroy_workqueue on service rescan PCI path
  MAINTAINERS: Update maintainer entry for QUALCOMM ETHQOS ETHERNET DRIVER
  dpll: zl3073x: Remove redundant cleanup in devm_dpll_init()
  selftests/net: packetdrill: Verify acceptance of FIN packets when RWIN is 0
  tcp: re-enable acceptance of FIN packets when RWIN is 0
  vsock: Use container_of() to get net namespace in sysctl handlers
  net: usb: kaweth: validate USB endpoints
  ...

Commit 2bd99aef1b19 ("tcp: accept bare FIN packets under memory
pressure") allowed accepting FIN packets in tcp_data_queue() even when
the receive window was closed, to prevent ACK/FIN loops with broken
clients.

Such a FIN packet is in sequence, but because the FIN consumes a
sequence number, it extends beyond the window. Before commit
9ca48d616ed7 ("tcp: do not accept packets beyond window"),
tcp_sequence() only required the seq to be within the window. After
that change, the entire packet (including the FIN) must fit within the
window. As a result, such FIN packets are now dropped and the handling
path is no longer reached.

Be more lenient by not counting the sequence number consumed by the
FIN when calling tcp_sequence(), restoring the previous behavior for
cases where only the FIN extends beyond the window.

Fixes: 9ca48d616ed7 ("tcp: do not accept packets beyond window")
Signed-off-by: Simon Baatz <gmbnomis@gmail.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@google.com>
Link: https://patch.msgid.link/20260224-fix_zero_wnd_fin-v2-1-a16677ea7cea@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>