The pointer arithmentic for accessing the tail tag only works
for linear skbs.

For nonlinear skbs, it reads uninitialized memory inside the
skb headroom, essentially randomizing the tag. I have observed
it gets set to 6 most of the time.

Example where ksz9477_rcv thinks that the packet from port 1 comes from port 6
(which does not exist for the ksz9896 that's in use), dropping the packet.
Debug prints added by me (not included in this patch):

	[  256.645337] ksz9477_rcv:323 tag0=6
	[  256.645349] skb len=47 headroom=78 headlen=0 tailroom=0
	               mac=(64,14) mac_len=14 net=(78,0) trans=78
	               shinfo(txflags=0 nr_frags=1 gso(size=0 type=0 segs=0))
	               csum(0x0 start=0 offset=0 ip_summed=0 complete_sw=0 valid=0 level=0)
	               hash(0x0 sw=0 l4=0) proto=0x00f8 pkttype=1 iif=3
	               priority=0x0 mark=0x0 alloc_cpu=0 vlan_all=0x0
	               encapsulation=0 inner(proto=0x0000, mac=0, net=0, trans=0)
	[  256.645377] dev name=end1 feat=0x0002e10200114bb3
	[  256.645386] skb headroom: 00000000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
	[  256.645395] skb headroom: 00000010: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
	[  256.645403] skb headroom: 00000020: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
	[  256.645411] skb headroom: 00000030: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
	[  256.645420] skb headroom: 00000040: ff ff ff ff ff ff 00 1c 19 f2 e2 db 08 06
	[  256.645428] skb frag:     00000000: 00 01 08 00 06 04 00 01 00 1c 19 f2 e2 db 0a 02
	[  256.645436] skb frag:     00000010: 00 83 00 00 00 00 00 00 0a 02 a0 2f 00 00 00 00
	[  256.645444] skb frag:     00000020: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 01
	[  256.645452] ksz_common_rcv:92 dsa_conduit_find_user returned NULL

Call skb_linearize before trying to access the tag.

This patch fixes ksz9477_rcv which is used by the ksz9896 I have at
hand, and also applies the same fix to ksz8795_rcv which seems to have
the same problem.

Signed-off-by: Jakob Unterwurzacher <jakob.unterwurzacher@cherry.de>
CC: stable@vger.kernel.org
Fixes: 016e43a26bab ("net: dsa: ksz: Add KSZ8795 tag code")
Fixes: 8b8010fb7876 ("dsa: add support for Microchip KSZ tail tagging")
Reviewed-by: Vladimir Oltean <olteanv@gmail.com>
Link: https://patch.msgid.link/20250515072920.2313014-1-jakob.unterwurzacher@cherry.de
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

This is very similar to the problem and solution from commit
232deb3f9567 ("net: dsa: avoid refcount warnings when
->port_{fdb,mdb}_del returns error"), except for the
dsa_port_do_tag_8021q_vlan_del() operation.

Fixes: c64b9c05045a ("net: dsa: tag_8021q: add proper cross-chip notifier support")
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Link: https://patch.msgid.link/20250414213020.2959021-1-vladimir.oltean@nxp.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

If complete = true in dsa_tree_setup(), it means that we are the last
switch of the tree which is successfully probing, and we should be
setting up all switches from our probe path.

After "complete" becomes true, dsa_tree_setup_cpu_ports() or any
subsequent function may fail. If that happens, the entire tree setup is
in limbo: the first N-1 switches have successfully finished probing
(doing nothing but having allocated persistent memory in the tree's
dst->ports, and maybe dst->rtable), and switch N failed to probe, ending
the tree setup process before anything is tangible from the user's PoV.

If switch N fails to probe, its memory (ports) will be freed and removed
from dst->ports. However, the dst->rtable elements pointing to its ports,
as created by dsa_link_touch(), will remain there, and will lead to
use-after-free if dereferenced.

If dsa_tree_setup_switches() returns -EPROBE_DEFER, which is entirely
possible because that is where ds->ops->setup() is, we get a kasan
report like this:

==================================================================
BUG: KASAN: slab-use-after-free in mv88e6xxx_setup_upstream_port+0x240/0x568
Read of size 8 at addr ffff000004f56020 by task kworker/u8:3/42

Call trace:
 __asan_report_load8_noabort+0x20/0x30
 mv88e6xxx_setup_upstream_port+0x240/0x568
 mv88e6xxx_setup+0xebc/0x1eb0
 dsa_register_switch+0x1af4/0x2ae0
 mv88e6xxx_register_switch+0x1b8/0x2a8
 mv88e6xxx_probe+0xc4c/0xf60
 mdio_probe+0x78/0xb8
 really_probe+0x2b8/0x5a8
 __driver_probe_device+0x164/0x298
 driver_probe_device+0x78/0x258
 __device_attach_driver+0x274/0x350

Allocated by task 42:
 __kasan_kmalloc+0x84/0xa0
 __kmalloc_cache_noprof+0x298/0x490
 dsa_switch_touch_ports+0x174/0x3d8
 dsa_register_switch+0x800/0x2ae0
 mv88e6xxx_register_switch+0x1b8/0x2a8
 mv88e6xxx_probe+0xc4c/0xf60
 mdio_probe+0x78/0xb8
 really_probe+0x2b8/0x5a8
 __driver_probe_device+0x164/0x298
 driver_probe_device+0x78/0x258
 __device_attach_driver+0x274/0x350

Freed by task 42:
 __kasan_slab_free+0x48/0x68
 kfree+0x138/0x418
 dsa_register_switch+0x2694/0x2ae0
 mv88e6xxx_register_switch+0x1b8/0x2a8
 mv88e6xxx_probe+0xc4c/0xf60
 mdio_probe+0x78/0xb8
 really_probe+0x2b8/0x5a8
 __driver_probe_device+0x164/0x298
 driver_probe_device+0x78/0x258
 __device_attach_driver+0x274/0x350

The simplest way to fix the bug is to delete the routing table in its
entirety. dsa_tree_setup_routing_table() has no problem in regenerating
it even if we deleted links between ports other than those of switch N,
because dsa_link_touch() first checks whether the port pair already
exists in dst->rtable, allocating if not.

The deletion of the routing table in its entirety already exists in
dsa_tree_teardown(), so refactor that into a function that can also be
called from the tree setup error path.

In my analysis of the commit to blame, it is the one which added
dsa_link elements to dst->rtable. Prior to that, each switch had its own
ds->rtable which is freed when the switch fails to probe. But the tree
is potentially persistent memory.

Fixes: c5f51765a1f6 ("net: dsa: list DSA links in the fabric")
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Link: https://patch.msgid.link/20250414213001.2957964-1-vladimir.oltean@nxp.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

As explained in many places such as commit b117e1e8a86d ("net: dsa:
delete dsa_legacy_fdb_add and dsa_legacy_fdb_del"), DSA is written given
the assumption that higher layers have balanced additions/deletions.
As such, it only makes sense to be extremely vocal when those
assumptions are violated and the driver unbinds with entries still
present.

But Ido Schimmel points out a very simple situation where that is wrong:
https://lore.kernel.org/netdev/ZDazSM5UsPPjQuKr@shredder/
(also briefly discussed by me in the aforementioned commit).

Basically, while the bridge bypass operations are not something that DSA
explicitly documents, and for the majority of DSA drivers this API
simply causes them to go to promiscuous mode, that isn't the case for
all drivers. Some have the necessary requirements for bridge bypass
operations to do something useful - see dsa_switch_supports_uc_filtering().

Although in tools/testing/selftests/net/forwarding/local_termination.sh,
we made an effort to popularize better mechanisms to manage address
filters on DSA interfaces from user space - namely macvlan for unicast,
and setsockopt(IP_ADD_MEMBERSHIP) - through mtools - for multicast, the
fact is that 'bridge fdb add ... self static local' also exists as
kernel UAPI, and might be useful to someone, even if only for a quick
hack.

It seems counter-productive to block that path by implementing shim
.ndo_fdb_add and .ndo_fdb_del operations which just return -EOPNOTSUPP
in order to prevent the ndo_dflt_fdb_add() and ndo_dflt_fdb_del() from
running, although we could do that.

Accepting that cleanup is necessary seems to be the only option.
Especially since we appear to be coming back at this from a different
angle as well. Russell King is noticing that the WARN_ON() triggers even
for VLANs:
https://lore.kernel.org/netdev/Z_li8Bj8bD4-BYKQ@shell.armlinux.org.uk/

What happens in the bug report above is that dsa_port_do_vlan_del() fails,
then the VLAN entry lingers on, and then we warn on unbind and leak it.

This is not a straight revert of the blamed commit, but we now add an
informational print to the kernel log (to still have a way to see
that bugs exist), and some extra comments gathered from past years'
experience, to justify the logic.

Fixes: 0832cd9f1f02 ("net: dsa: warn if port lists aren't empty in dsa_port_teardown")
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Link: https://patch.msgid.link/20250414212930.2956310-1-vladimir.oltean@nxp.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Move the more esoteric helpers for netdev instance lock to
a dedicated header. This avoids growing netdevice.h to infinity
and makes rebuilding the kernel much faster (after touching
the header with the helpers).

The main netdev_lock() / netdev_unlock() functions are used
in static inlines in netdevice.h and will probably be used
most commonly, so keep them in netdevice.h.

Acked-by: Stanislav Fomichev <sdf@fomichev.me>
Link: https://patch.msgid.link/20250307183006.2312761-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Protect all ethtool callbacks and PHY related state with the netdev
instance lock, for drivers which want / need to have their ops
instance-locked. Basically take the lock everywhere we take rtnl_lock.
It was tempting to take the lock in ethnl_ops_begin(), but turns
out we actually nest those calls (when generating notifications).

Tested-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
Cc: Saeed Mahameed <saeed@kernel.org>
Signed-off-by: Stanislav Fomichev <sdf@fomichev.me>
Link: https://patch.msgid.link/20250305163732.2766420-11-sdf@fomichev.me
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Support hw SCM_TSTAMP_SND case for bpf timestamping.

Add a new sock_ops callback, BPF_SOCK_OPS_TSTAMP_SND_HW_CB. This
callback will occur at the same timestamping point as the user
space's hardware SCM_TSTAMP_SND. The BPF program can use it to
get the same SCM_TSTAMP_SND timestamp without modifying the
user-space application.

To avoid increasing the code complexity, replace SKBTX_HW_TSTAMP
with SKBTX_HW_TSTAMP_NOBPF instead of changing numerous callers
from driver side using SKBTX_HW_TSTAMP. The new definition of
SKBTX_HW_TSTAMP means the combination tests of socket timestamping
and bpf timestamping. After this patch, drivers can work under the
bpf timestamping.

Considering some drivers don't assign the skb with hardware
timestamp, this patch does the assignment and then BPF program
can acquire the hwstamp from skb directly.

Signed-off-by: Jason Xing <kerneljasonxing@gmail.com>
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Link: https://patch.msgid.link/20250220072940.99994-9-kerneljasonxing@gmail.com

In order to allow DSA drivers to use phylink managed EEE, we need to
change the behaviour of the DSA's .set_eee() ethtool method.
Implementation of the DSA .set_mac_eee() method becomes optional with
phylink managed EEE as it is only used to validate the EEE parameters
supplied from userspace. The rest of the EEE state management should
be left to phylink.

Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Link: https://patch.msgid.link/E1thR9l-003vXC-9F@rmk-PC.armlinux.org.uk
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Pull driver core and debugfs updates from Greg KH:
 "Here is the big set of driver core and debugfs updates for 6.14-rc1.

  Included in here is a bunch of driver core, PCI, OF, and platform rust
  bindings (all acked by the different subsystem maintainers), hence the
  merge conflict with the rust tree, and some driver core api updates to
  mark things as const, which will also require some fixups due to new
  stuff coming in through other trees in this merge window.

  There are also a bunch of debugfs updates from Al, and there is at
  least one user that does have a regression with these, but Al is
  working on tracking down the fix for it. In my use (and everyone
  else's linux-next use), it does not seem like a big issue at the
  moment.

  Here's a short list of the things in here:

   - driver core rust bindings for PCI, platform, OF, and some i/o
     functions.

     We are almost at the "write a real driver in rust" stage now,
     depending on what you want to do.

   - misc device rust bindings and a sample driver to show how to use
     them

   - debugfs cleanups in the fs as well as the users of the fs api for
     places where drivers got it wrong or were unnecessarily doing
     things in complex ways.

   - driver core const work, making more of the api take const * for
     different parameters to make the rust bindings easier overall.

   - other small fixes and updates

  All of these have been in linux-next with all of the aforementioned
  merge conflicts, and the one debugfs issue, which looks to be resolved
  "soon""

* tag 'driver-core-6.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core: (95 commits)
  rust: device: Use as_char_ptr() to avoid explicit cast
  rust: device: Replace CString with CStr in property_present()
  devcoredump: Constify 'struct bin_attribute'
  devcoredump: Define 'struct bin_attribute' through macro
  rust: device: Add property_present()
  saner replacement for debugfs_rename()
  orangefs-debugfs: don't mess with ->d_name
  octeontx2: don't mess with ->d_parent or ->d_parent->d_name
  arm_scmi: don't mess with ->d_parent->d_name
  slub: don't mess with ->d_name
  sof-client-ipc-flood-test: don't mess with ->d_name
  qat: don't mess with ->d_name
  xhci: don't mess with ->d_iname
  mtu3: don't mess wiht ->d_iname
  greybus/camera - stop messing with ->d_iname
  mediatek: stop messing with ->d_iname
  netdevsim: don't embed file_operations into your structs
  b43legacy: make use of debugfs_get_aux()
  b43: stop embedding struct file_operations into their objects
  carl9170: stop embedding file_operations into their objects
  ...

Pull networking updates from Paolo Abeni:
 "This is slightly smaller than usual, with the most interesting work
  being still around RTNL scope reduction.

  Core:

   - More core refactoring to reduce the RTNL lock contention, including
     preparatory work for the per-network namespace RTNL lock, replacing
     RTNL lock with a per device-one to protect NAPI-related net device
     data and moving synchronize_net() calls outside such lock.

   - Extend drop reasons usage, adding net scheduler, AF_UNIX, bridge
     and more specific TCP coverage.

   - Reduce network namespace tear-down time by removing per-subsystems
     synchronize_net() in tipc and sched.

   - Add flow label selector support for fib rules, allowing traffic
     redirection based on such header field.

  Netfilter:

   - Do not remove netdev basechain when last device is gone, allowing
     netdev basechains without devices.

   - Revisit the flowtable teardown strategy, dealing better with fin,
     reset and re-open events.

   - Scale-up IP-vs connection dumping by avoiding linear search on each
     restart.

  Protocols:

   - A significant XDP socket refactor, consolidating and optimizing
     several helpers into the core

   - Better scaling of ICMP rate-limiting, by removing false-sharing in
     inet peers handling.

   - Introduces netlink notifications for multicast IPv4 and IPv6
     address changes.

   - Add ipsec support for IP-TFS/AggFrag encapsulation, allowing
     aggregation and fragmentation of the inner IP.

   - Add sysctl to configure TIME-WAIT reuse delay for TCP sockets, to
     avoid local port exhaustion issues when the average connection
     lifetime is very short.

   - Support updating keys (re-keying) for connections using kernel TLS
     (for TLS 1.3 only).

   - Support ipv4-mapped ipv6 address clients in smc-r v2.

   - Add support for jumbo data packet transmission in RxRPC sockets,
     gluing multiple data packets in a single UDP packet.

   - Support RxRPC RACK-TLP to manage packet loss and retransmission in
     conjunction with the congestion control algorithm.

  Driver API:

   - Introduce a unified and structured interface for reporting PHY
     statistics, exposing consistent data across different H/W via
     ethtool.

   - Make timestamping selectable, allow the user to select the desired
     hwtstamp provider (PHY or MAC) administratively.

   - Add support for configuring a header-data-split threshold (HDS)
     value via ethtool, to deal with partial or buggy H/W
     implementation.

   - Consolidate DSA drivers Energy Efficiency Ethernet support.

   - Add EEE management to phylink, making use of the phylib
     implementation.

   - Add phylib support for in-band capabilities negotiation.

   - Simplify how phylib-enabled mac drivers expose the supported
     interfaces.

  Tests and tooling:

   - Make the YNL tool package-friendly to make it easier to deploy it
     separately from the kernel.

   - Increase TCP selftest coverage importing several packetdrill
     test-cases.

   - Regenerate the ethtool uapi header from the YNL spec, to ease
     maintenance and future development.

   - Add YNL support for decoding the link types used in net self-tests,
     allowing a single build to run both net and drivers/net.

  Drivers:

   - Ethernet high-speed NICs:
      - nVidia/Mellanox (mlx5):
         - add cross E-Switch QoS support
         - add SW Steering support for ConnectX-8
         - implement support for HW-Managed Flow Steering, improving the
           rule deletion/insertion rate
         - support for multi-host LAG
      - Intel (ixgbe, ice, igb):
         - ice: add support for devlink health events
         - ixgbe: add initial support for E610 chipset variant
         - igb: add support for AF_XDP zero-copy
      - Meta:
         - add support for basic RSS config
         - allow changing the number of channels
         - add hardware monitoring support
      - Broadcom (bnxt):
         - implement TCP data split and HDS threshold ethtool support,
           enabling Device Memory TCP.
      - Marvell Octeon:
         - implement egress ipsec offload support for the cn10k family
      - Hisilicon (HIBMC):
         - implement unicast MAC filtering

   - Ethernet NICs embedded and virtual:
      - Convert UDP tunnel drivers to NETDEV_PCPU_STAT_DSTATS, avoiding
        contented atomic operations for drop counters
      - Freescale:
         - quicc: phylink conversion
         - enetc: support Tx and Rx checksum offload and improve TSO
           performances
      - MediaTek:
         - airoha: introduce support for ETS and HTB Qdisc offload
      - Microchip:
         - lan78XX USB: preparation work for phylink conversion
      - Synopsys (stmmac):
         - support DWMAC IP on NXP Automotive SoCs S32G2xx/S32G3xx/S32R45
         - refactor EEE support to leverage the new driver API
         - optimize DMA and cache access to increase raw RX performances
           by 40%
      - TI:
         - icssg-prueth: add multicast filtering support for VLAN
           interface
      - netkit:
         - add ability to configure head/tailroom
      - VXLAN:
         - accepts packets with user-defined reserved bit

   - Ethernet switches:
      - Microchip:
         - lan969x: add RGMII support
         - lan969x: improve TX and RX performance using the FDMA engine
      - nVidia/Mellanox:
         - move Tx header handling to PCI driver, to ease XDP support

   - Ethernet PHYs:
      - Texas Instruments DP83822:
         - add support for GPIO2 clock output
      - Realtek:
         - 8169: add support for RTL8125D rev.b
         - rtl822x: add hwmon support for the temperature sensor
      - Microchip:
         - add support for RDS PTP hardware
         - consolidate periodic output signal generation

   - CAN:
      - several DT-bindings to DT schema conversions
      - tcan4x5x:
         - add HW standby support
         - support nWKRQ voltage selection
      - kvaser:
         - allowing Bus Error Reporting runtime configuration

   - WiFi:
      - the on-going Multi-Link Operation (MLO) effort continues,
        affecting both the stack and in drivers
      - mac80211/cfg80211:
         - Emergency Preparedness Communication Services (EPCS) station
           mode support
         - support for adding and removing station links for MLO
         - add support for WiFi 7/EHT mesh over 320 MHz channels
         - report Tx power info for each link
      - RealTek (rtw88):
         - enable USB Rx aggregation and USB 3 to improve performance
         - LED support
      - RealTek (rtw89):
         - refactor power save to support Multi-Link Operations
         - add support for RTL8922AE-VS variant
      - MediaTek (mt76):
         - single wiphy multiband support (preparation for MLO)
         - p2p device support
         - add TP-Link TXE50UH USB adapter support
      - Qualcomm (ath10k):
         - support for the QCA6698AQ IP core
      - Qualcomm (ath12k):
         - enable MLO for QCN9274

   - Bluetooth:
      - Allow sysfs to trigger hdev reset, to allow recovering devices
        not responsive from user-space
      - MediaTek: add support for MT7922, MT7925, MT7921e devices
      - Realtek: add support for RTL8851BE devices
      - Qualcomm: add support for WCN785x devices
      - ISO: allow BIG re-sync"

* tag 'net-next-6.14' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next: (1386 commits)
  net/rose: prevent integer overflows in rose_setsockopt()
  net: phylink: fix regression when binding a PHY
  net: ethernet: ti: am65-cpsw: streamline TX queue creation and cleanup
  net: ethernet: ti: am65-cpsw: streamline RX queue creation and cleanup
  net: ethernet: ti: am65-cpsw: ensure proper channel cleanup in error path
  ipv6: Convert inet6_rtm_deladdr() to per-netns RTNL.
  ipv6: Convert inet6_rtm_newaddr() to per-netns RTNL.
  ipv6: Move lifetime validation to inet6_rtm_newaddr().
  ipv6: Set cfg.ifa_flags before device lookup in inet6_rtm_newaddr().
  ipv6: Pass dev to inet6_addr_add().
  ipv6: Convert inet6_ioctl() to per-netns RTNL.
  ipv6: Hold rtnl_net_lock() in addrconf_init() and addrconf_cleanup().
  ipv6: Hold rtnl_net_lock() in addrconf_dad_work().
  ipv6: Hold rtnl_net_lock() in addrconf_verify_work().
  ipv6: Convert net.ipv6.conf.${DEV}.XXX sysctl to per-netns RTNL.
  ipv6: Add __in6_dev_get_rtnl_net().
  net: stmmac: Drop redundant skb_mark_for_recycle() for SKB frags
  net: mii: Fix the Speed display when the network cable is not connected
  sysctl net: Remove macro checks for CONFIG_SYSCTL
  eth: bnxt: update header sizing defaults
  ...