linux/Documentation/ABI
Linus Torvalds fc858a5231 Networking fixes for 5.13-rc1, including fixes from bpf, can
and netfilter trees. Self-contained fixes, nothing risky.
 
 Current release - new code bugs:
 
  - dsa: ksz: fix a few bugs found by static-checker in the new driver
 
  - stmmac: fix frame preemption handshake not triggering after
            interface restart
 
 Previous releases - regressions:
 
  - make nla_strcmp handle more then one trailing null character
 
  - fix stack OOB reads while fragmenting IPv4 packets in openvswitch
    and net/sched
 
  - sctp: do asoc update earlier in sctp_sf_do_dupcook_a
 
  - sctp: delay auto_asconf init until binding the first addr
 
  - stmmac: clear receive all(RA) bit when promiscuous mode is off
 
  - can: mcp251x: fix resume from sleep before interface was brought up
 
 Previous releases - always broken:
 
  - bpf: fix leakage of uninitialized bpf stack under speculation
 
  - bpf: fix masking negation logic upon negative dst register
 
  - netfilter: don't assume that skb_header_pointer() will never fail
 
  - only allow init netns to set default tcp cong to a restricted algo
 
  - xsk: fix xp_aligned_validate_desc() when len == chunk_size to
         avoid false positive errors
 
  - ethtool: fix missing NLM_F_MULTI flag when dumping
 
  - can: m_can: m_can_tx_work_queue(): fix tx_skb race condition
 
  - sctp: fix a SCTP_MIB_CURRESTAB leak in sctp_sf_do_dupcook_b
 
  - bridge: fix NULL-deref caused by a races between assigning
            rx_handler_data and setting the IFF_BRIDGE_PORT bit
 
 Latecomer:
 
  - seg6: add counters support for SRv6 Behaviors
 
 Signed-off-by: Jakub Kicinski <kuba@kernel.org>
 -----BEGIN PGP SIGNATURE-----
 
 iQIzBAABCAAdFiEE6jPA+I1ugmIBA4hXMUZtbf5SIrsFAmCV3YoACgkQMUZtbf5S
 IrsQ2w//Q8/qbl6wGTKUfu6DZHYUU5j5sTwiHR823PKKSgXI+okWMN0KUlZszOsz
 qnPkH6GuojRooOE1s8PFLSlt9axKhQ0y7uzMTrWYafQ+JZTtgg9/MiPxQ8fdiE5i
 uOG1ngttZ+1jlE5tMPL4GAOSegg3rWVDclzqnJTdsPPOco3MWj6SL9xN0LDPxCEL
 BDysRqL/UiOIoh4v6IXQRx2UWjsNGu4biM1po+Jfumnd9T0zKoEpzu6UN6yPShbx
 284LihZSQtughCbhGqkErBOxfjZcvpFOQrqmjEvI+Z/eYg4InfWZemt8Sa92/alE
 yAFjK76MUTaUxaAO/gk8XauhvkYOzJJwKpqhbOmlaM7oj55QdzT5/8JxMxVoA6hV
 pscHOixk15GVse49PdPV8v47cyTLc/Xi69i+/uUdNVVfuORL1wft1w1xbd0S6Pbe
 7Gqax21S7zxcDsrUli7cFheYiqtbQAL0anlIUz8tUOZFz0VQ/zPuFd4rUYZ/o38V
 Mrevdk3t6CXNxS4CRXyUW4UejYB1O6Qw12sUue31e3h73d6LiN3NAiN5Qp7SEk1/
 fvk+jfOf8vvmtimYvcUK2i0D+vqj4Ec/qRIE/XXuUDBcp22tPL9uWMfWavwTdAj1
 Se4SzksTWF+NM0lO0ItonMyPh3ZXcSLhIv/gHrZwEKuWkXCGO4M=
 =JmWS
 -----END PGP SIGNATURE-----

Merge tag 'net-5.13-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net

Pull networking fixes from Jakub Kicinski:
 "Networking fixes for 5.13-rc1, including fixes from bpf, can and
  netfilter trees. Self-contained fixes, nothing risky.

  Current release - new code bugs:

   - dsa: ksz: fix a few bugs found by static-checker in the new driver

   - stmmac: fix frame preemption handshake not triggering after
     interface restart

  Previous releases - regressions:

   - make nla_strcmp handle more then one trailing null character

   - fix stack OOB reads while fragmenting IPv4 packets in openvswitch
     and net/sched

   - sctp: do asoc update earlier in sctp_sf_do_dupcook_a

   - sctp: delay auto_asconf init until binding the first addr

   - stmmac: clear receive all(RA) bit when promiscuous mode is off

   - can: mcp251x: fix resume from sleep before interface was brought up

  Previous releases - always broken:

   - bpf: fix leakage of uninitialized bpf stack under speculation

   - bpf: fix masking negation logic upon negative dst register

   - netfilter: don't assume that skb_header_pointer() will never fail

   - only allow init netns to set default tcp cong to a restricted algo

   - xsk: fix xp_aligned_validate_desc() when len == chunk_size to avoid
     false positive errors

   - ethtool: fix missing NLM_F_MULTI flag when dumping

   - can: m_can: m_can_tx_work_queue(): fix tx_skb race condition

   - sctp: fix a SCTP_MIB_CURRESTAB leak in sctp_sf_do_dupcook_b

   - bridge: fix NULL-deref caused by a races between assigning
     rx_handler_data and setting the IFF_BRIDGE_PORT bit

  Latecomer:

   - seg6: add counters support for SRv6 Behaviors"

* tag 'net-5.13-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net: (73 commits)
  atm: firestream: Use fallthrough pseudo-keyword
  net: stmmac: Do not enable RX FIFO overflow interrupts
  mptcp: fix splat when closing unaccepted socket
  i40e: Remove LLDP frame filters
  i40e: Fix PHY type identifiers for 2.5G and 5G adapters
  i40e: fix the restart auto-negotiation after FEC modified
  i40e: Fix use-after-free in i40e_client_subtask()
  i40e: fix broken XDP support
  netfilter: nftables: avoid potential overflows on 32bit arches
  netfilter: nftables: avoid overflows in nft_hash_buckets()
  tcp: Specify cmsgbuf is user pointer for receive zerocopy.
  mlxsw: spectrum_mr: Update egress RIF list before route's action
  net: ipa: fix inter-EE IRQ register definitions
  can: m_can: m_can_tx_work_queue(): fix tx_skb race condition
  can: mcp251x: fix resume from sleep before interface was brought up
  can: mcp251xfd: mcp251xfd_probe(): add missing can_rx_offload_del() in error path
  can: mcp251xfd: mcp251xfd_probe(): fix an error pointer dereference in probe
  netfilter: nftables: Fix a memleak from userdata error path in new objects
  netfilter: remove BUG_ON() after skb_header_pointer()
  netfilter: nfnetlink_osf: Fix a missing skb_header_pointer() NULL check
  ...
2021-05-08 08:31:46 -07:00
..
obsolete batman-adv: Drop deprecated sysfs support 2020-12-04 08:40:52 +01:00
removed docs: ABI: cleanup several ABI documents 2020-10-30 13:14:29 +01:00
stable audit: drop /proc/PID/loginuid documentation Format field 2021-04-01 18:32:24 -04:00
testing Networking fixes for 5.13-rc1, including fixes from bpf, can 2021-05-08 08:31:46 -07:00
README docs: ABI: README: specify that files should be ReST compatible 2020-10-30 13:07:01 +01:00

README

This directory attempts to document the ABI between the Linux kernel and
userspace, and the relative stability of these interfaces.  Due to the
everchanging nature of Linux, and the differing maturity levels, these
interfaces should be used by userspace programs in different ways.

We have four different levels of ABI stability, as shown by the four
different subdirectories in this location.  Interfaces may change levels
of stability according to the rules described below.

The different levels of stability are:

  stable/
	This directory documents the interfaces that the developer has
	defined to be stable.  Userspace programs are free to use these
	interfaces with no restrictions, and backward compatibility for
	them will be guaranteed for at least 2 years.  Most interfaces
	(like syscalls) are expected to never change and always be
	available.

  testing/
	This directory documents interfaces that are felt to be stable,
	as the main development of this interface has been completed.
	The interface can be changed to add new features, but the
	current interface will not break by doing this, unless grave
	errors or security problems are found in them.  Userspace
	programs can start to rely on these interfaces, but they must be
	aware of changes that can occur before these interfaces move to
	be marked stable.  Programs that use these interfaces are
	strongly encouraged to add their name to the description of
	these interfaces, so that the kernel developers can easily
	notify them if any changes occur (see the description of the
	layout of the files below for details on how to do this.)

  obsolete/
	This directory documents interfaces that are still remaining in
	the kernel, but are marked to be removed at some later point in
	time.  The description of the interface will document the reason
	why it is obsolete and when it can be expected to be removed.

  removed/
	This directory contains a list of the old interfaces that have
	been removed from the kernel.

Every file in these directories will contain the following information:

What:		Short description of the interface
Date:		Date created
KernelVersion:	Kernel version this feature first showed up in.
Contact:	Primary contact for this interface (may be a mailing list)
Description:	Long description of the interface and how to use it.
Users:		All users of this interface who wish to be notified when
		it changes.  This is very important for interfaces in
		the "testing" stage, so that kernel developers can work
		with userspace developers to ensure that things do not
		break in ways that are unacceptable.  It is also
		important to get feedback for these interfaces to make
		sure they are working in a proper way and do not need to
		be changed further.


Note:
   The fields should be use a simple notation, compatible with ReST markup.
   Also, the file **should not** have a top-level index, like::

	===
	foo
	===

How things move between levels:

Interfaces in stable may move to obsolete, as long as the proper
notification is given.

Interfaces may be removed from obsolete and the kernel as long as the
documented amount of time has gone by.

Interfaces in the testing state can move to the stable state when the
developers feel they are finished.  They cannot be removed from the
kernel tree without going through the obsolete state first.

It's up to the developer to place their interfaces in the category they
wish for it to start out in.


Notable bits of non-ABI, which should not under any circumstances be considered
stable:

- Kconfig.  Userspace should not rely on the presence or absence of any
  particular Kconfig symbol, in /proc/config.gz, in the copy of .config
  commonly installed to /boot, or in any invocation of the kernel build
  process.

- Kernel-internal symbols.  Do not rely on the presence, absence, location, or
  type of any kernel symbol, either in System.map files or the kernel binary
  itself.  See Documentation/process/stable-api-nonsense.rst.