Document the spec format used by netlink-raw families like rt and tc.
Reviewed-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Donald Hunter <donald.hunter@gmail.com>
Link: https://lore.kernel.org/r/20231215093720.18774-4-donald.hunter@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
In case NLMSG_DONE message is sent as a reply to doit action, multiple
kernel implementation do not send anything else than struct nlmsghdr.
Add this note to the Netlink intro documentation.
Signed-off-by: Jiri Pirko <jiri@nvidia.com>
Reviewed-by: Bagas Sanjaya <bagasdotme@gmail.com>
Link: https://lore.kernel.org/r/20231201180154.864007-1-jiri@resnulli.us
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
To increase the chances of people finding the rendered docs
add a link to specs.rst and index.rst.
Add a label in the generated index.rst and while at it adjust
the title a little bit.
Reviewed-by: Breno Leitao <leitao@debian.org>
Reviewed-by: Donald Hunter <donald.hunter@gmail.com>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Link: https://lore.kernel.org/r/20231129041427.2763074-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Introduce support for attribute type bitfield32.
Note that since the generated code works with struct nla_bitfield32,
the generator adds netlink.h to the list of includes for userspace
headers in case any bitfield32 is present.
Note that this is added only to genetlink-legacy scheme as requested
by Jakub Kicinski.
Signed-off-by: Jiri Pirko <jiri@nvidia.com>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Link: https://lore.kernel.org/r/20231021112711.660606-3-jiri@resnulli.us
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
We currently push everyone to use padding to align 64b values
in netlink. Un-padded nla_put_u64() doesn't even exist any more.
The story behind this possibly start with this thread:
https://lore.kernel.org/netdev/20121204.130914.1457976839967676240.davem@davemloft.net/
where DaveM was concerned about the alignment of a structure
containing 64b stats. If user space tries to access such struct
directly:
struct some_stats *stats = nla_data(attr);
printf("A: %llu", stats->a);
lack of alignment may become problematic for some architectures.
These days we most often put every single member in a separate
attribute, meaning that the code above would use a helper like
nla_get_u64(), which can deal with alignment internally.
Even for arches which don't have good unaligned access - access
aligned to 4B should be pretty efficient.
Kernel and well known libraries deal with unaligned input already.
Padded 64b is quite space-inefficient (64b + pad means at worst 16B
per attr vs 32b which takes 8B). It is also more typing:
if (nla_put_u64_pad(rsp, NETDEV_A_SOMETHING_SOMETHING,
value, NETDEV_A_SOMETHING_PAD))
Create a new attribute type which will use 32 bits at netlink
level if value is small enough (probably most of the time?),
and (4B-aligned) 64 bits otherwise. Kernel API is just:
if (nla_put_uint(rsp, NETDEV_A_SOMETHING_SOMETHING, value))
Calling this new type "just" sint / uint with no specific size
will hopefully also make people more comfortable with using it.
Currently telling people "don't use u8, you may need the bits,
and netlink will round up to 4B, anyway" is the #1 comment
we give to newcomers.
In terms of netlink layout it looks like this:
0 4 8 12 16
32b: [nlattr][ u32 ]
64b: [ pad ][nlattr][ u64 ]
uint(32) [nlattr][ u32 ]
uint(64) [nlattr][ u64 ]
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Acked-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Jiri moved version to legacy specs in commit 0f07415ebb ("netlink:
specs: don't allow version to be specified for genetlink").
Update the documentation.
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Link: https://lore.kernel.org/r/20231016214540.1822392-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Current release - regressions:
- eth: stmmac: fix failure to probe without MAC interface specified
Current release - new code bugs:
- docs: netlink: fix missing classic_netlink doc reference
Previous releases - regressions:
- deal with integer overflows in kmalloc_reserve()
- use sk_forward_alloc_get() in sk_get_meminfo()
- bpf_sk_storage: fix the missing uncharge in sk_omem_alloc
- fib: avoid warn splat in flow dissector after packet mangling
- skb_segment: call zero copy functions before using skbuff frags
- eth: sfc: check for zero length in EF10 RX prefix
Previous releases - always broken:
- af_unix: fix msg_controllen test in scm_pidfd_recv() for
MSG_CMSG_COMPAT
- xsk: fix xsk_build_skb() dereferencing possible ERR_PTR()
- netfilter:
- nft_exthdr: fix non-linear header modification
- xt_u32, xt_sctp: validate user space input
- nftables: exthdr: fix 4-byte stack OOB write
- nfnetlink_osf: avoid OOB read
- one more fix for the garbage collection work from last release
- igmp: limit igmpv3_newpack() packet size to IP_MAX_MTU
- bpf, sockmap: fix preempt_rt splat when using raw_spin_lock_t
- handshake: fix null-deref in handshake_nl_done_doit()
- ip: ignore dst hint for multipath routes to ensure packets
are hashed across the nexthops
- phy: micrel:
- correct bit assignments for cable test errata
- disable EEE according to the KSZ9477 errata
Misc:
- docs/bpf: document compile-once-run-everywhere (CO-RE) relocations
- Revert "net: macsec: preserve ingress frame ordering", it appears
to have been developed against an older kernel, problem doesn't
exist upstream
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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Merge tag 'net-6.6-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net
Pull networking updates from Jakub Kicinski:
"Including fixes from netfilter and bpf.
Current release - regressions:
- eth: stmmac: fix failure to probe without MAC interface specified
Current release - new code bugs:
- docs: netlink: fix missing classic_netlink doc reference
Previous releases - regressions:
- deal with integer overflows in kmalloc_reserve()
- use sk_forward_alloc_get() in sk_get_meminfo()
- bpf_sk_storage: fix the missing uncharge in sk_omem_alloc
- fib: avoid warn splat in flow dissector after packet mangling
- skb_segment: call zero copy functions before using skbuff frags
- eth: sfc: check for zero length in EF10 RX prefix
Previous releases - always broken:
- af_unix: fix msg_controllen test in scm_pidfd_recv() for
MSG_CMSG_COMPAT
- xsk: fix xsk_build_skb() dereferencing possible ERR_PTR()
- netfilter:
- nft_exthdr: fix non-linear header modification
- xt_u32, xt_sctp: validate user space input
- nftables: exthdr: fix 4-byte stack OOB write
- nfnetlink_osf: avoid OOB read
- one more fix for the garbage collection work from last release
- igmp: limit igmpv3_newpack() packet size to IP_MAX_MTU
- bpf, sockmap: fix preempt_rt splat when using raw_spin_lock_t
- handshake: fix null-deref in handshake_nl_done_doit()
- ip: ignore dst hint for multipath routes to ensure packets are
hashed across the nexthops
- phy: micrel:
- correct bit assignments for cable test errata
- disable EEE according to the KSZ9477 errata
Misc:
- docs/bpf: document compile-once-run-everywhere (CO-RE) relocations
- Revert "net: macsec: preserve ingress frame ordering", it appears
to have been developed against an older kernel, problem doesn't
exist upstream"
* tag 'net-6.6-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net: (95 commits)
net: enetc: distinguish error from valid pointers in enetc_fixup_clear_rss_rfs()
Revert "net: team: do not use dynamic lockdep key"
net: hns3: remove GSO partial feature bit
net: hns3: fix the port information display when sfp is absent
net: hns3: fix invalid mutex between tc qdisc and dcb ets command issue
net: hns3: fix debugfs concurrency issue between kfree buffer and read
net: hns3: fix byte order conversion issue in hclge_dbg_fd_tcam_read()
net: hns3: Support query tx timeout threshold by debugfs
net: hns3: fix tx timeout issue
net: phy: Provide Module 4 KSZ9477 errata (DS80000754C)
netfilter: nf_tables: Unbreak audit log reset
netfilter: ipset: add the missing IP_SET_HASH_WITH_NET0 macro for ip_set_hash_netportnet.c
netfilter: nft_set_rbtree: skip sync GC for new elements in this transaction
netfilter: nf_tables: uapi: Describe NFTA_RULE_CHAIN_ID
netfilter: nfnetlink_osf: avoid OOB read
netfilter: nftables: exthdr: fix 4-byte stack OOB write
selftests/bpf: Check bpf_sk_storage has uncharged sk_omem_alloc
bpf: bpf_sk_storage: Fix the missing uncharge in sk_omem_alloc
bpf: bpf_sk_storage: Fix invalid wait context lockdep report
s390/bpf: Pass through tail call counter in trampolines
...
- Work from Carlos Bilbao to integrate rustdoc output into the generated
HTML documentation. This took some work to figure out how to do it
without slowing the docs build and without creating people who don't have
Rust installed, but Carlos got there.
- Move the loongarch and mips architecture documentation under
Documentation/arch/.
- Some more maintainer documentation from Jakub
...plus the usual assortment of updates, translations, and fixes.
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Merge tag 'docs-6.6' of git://git.lwn.net/linux
Pull documentation updates from Jonathan Corbet:
"Documentation work keeps chugging along; this includes:
- Work from Carlos Bilbao to integrate rustdoc output into the
generated HTML documentation. This took some work to figure out how
to do it without slowing the docs build and without creating people
who don't have Rust installed, but Carlos got there
- Move the loongarch and mips architecture documentation under
Documentation/arch/
- Some more maintainer documentation from Jakub
... plus the usual assortment of updates, translations, and fixes"
* tag 'docs-6.6' of git://git.lwn.net/linux: (56 commits)
Docu: genericirq.rst: fix irq-example
input: docs: pxrc: remove reference to phoenix-sim
Documentation: serial-console: Fix literal block marker
docs/mm: remove references to hmm_mirror ops and clean typos
docs/zh_CN: correct regi_chg(),regi_add() to region_chg(),region_add()
Documentation: Fix typos
Documentation/ABI: Fix typos
scripts: kernel-doc: fix macro handling in enums
scripts: kernel-doc: parse DEFINE_DMA_UNMAP_[ADDR|LEN]
Documentation: riscv: Update boot image header since EFI stub is supported
Documentation: riscv: Add early boot document
Documentation: arm: Add bootargs to the table of added DT parameters
docs: kernel-parameters: Refer to the correct bitmap function
doc: update params of memhp_default_state=
docs: Add book to process/kernel-docs.rst
docs: sparse: fix invalid link addresses
docs: vfs: clean up after the iterate() removal
docs: Add a section on surveys to the researcher guidelines
docs: move mips under arch
docs: move loongarch under arch
...
Add a doc page for netlink-raw that describes the schema attributes
needed for netlink-raw.
Signed-off-by: Donald Hunter <donald.hunter@gmail.com>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Link: https://lore.kernel.org/r/20230825122756.7603-5-donald.hunter@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Add documentation for recently added genetlink-legacy schema attributes.
Remove statements about 'work in progress' and 'todo'.
Signed-off-by: Donald Hunter <donald.hunter@gmail.com>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Link: https://lore.kernel.org/r/20230825122756.7603-4-donald.hunter@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Add "fixed" part of the user space Netlink Spec-based library.
This will get linked with the protocol implementations to form
a full API.
Acked-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Add a definition for sub-type to the protocol spec doc and a description of
its usage for C arrays in genetlink-legacy.
Signed-off-by: Donald Hunter <donald.hunter@gmail.com>
Reviewed-by: Bagas Sanjaya <bagasdotme@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Describe the genetlink-legacy support for using struct definitions
for fixed headers and for binary attributes.
Signed-off-by: Donald Hunter <donald.hunter@gmail.com>
Reviewed-by: Bagas Sanjaya <bagasdotme@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
I relicensed Netlink spec code to GPL-2.0 OR BSD-3-Clause but
we still put a slightly different license on the uAPI header
than the rest of the code. Use the Linux-syscall-note on all
the specs and all generated code. It's moot for kernel code,
but should not hurt. This way the licenses match everywhere.
Cc: Chuck Lever <chuck.lever@oracle.com>
Fixes: 37d9df224d ("ynl: re-license uniformly under GPL-2.0 OR BSD-3-Clause")
Reviewed-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
I was intending to make all the Netlink Spec code BSD-3-Clause
to ease the adoption but it appears that:
- I fumbled the uAPI and used "GPL WITH uAPI note" there
- it gives people pause as they expect GPL in the kernel
As suggested by Chuck re-license under dual. This gives us benefit
of full BSD freedom while fulfilling the broad "kernel is under GPL"
expectations.
Link: https://lore.kernel.org/all/20230304120108.05dd44c5@kernel.org/
Link: https://lore.kernel.org/r/20230306200457.3903854-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Pretty much all families use value: 1 or reserve as unspec
the first entry in attribute set and the first operation.
Make this the default. Update documentation (the doc for
values of operations just refers back to doc for attrs
so updating only attrs).
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
To avoid having to repeat the entire definition of an attribute
(including the value) use the Attr object from the original set.
In fact this is already the documented expectation.
Fixes: be5bea1cc0 ("net: add basic C code generators for Netlink")
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
We have a bit of documentation about the internals of Netlink
and the specs, but really the goal is for most people to not
worry about those. Add a practical guide for beginners who
want to poke at the specs.
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
I had a (bright?) idea of introducing the concept of enum-models
to account for all the weird ways families enumerate their messages.
I've never finished it because generating C code for each of them
is pretty daunting. But for languages which can use ID values directly
the support is simple enough, so clean this up a bit.
"unified" model is what I recommend going forward.
"directional" model is what ethtool uses.
"notify-split" is used by the proposed DPLL code, but we can just
make them use "unified", it hasn't been merged :)
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Add documentation about the upcoming Netlink protocol specs.
Reviewed-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Reviewed-by: Bagas Sanjaya <bagasdotme@gmail.com>
Acked-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
nlmsg_flags are full of historical baggage, inconsistencies and
strangeness. Try to document it more thoroughly. Explain the meaning
of the ECHO flag (and while at it clarify the comment in the uAPI).
Handwave a little about the NEW request flags and how they make
sense on the surface but cater to really old paradigm before commands
were a thing.
I will add more notes on how to make use of ECHO and discouragement
for reuse of flags to the kernel-side documentation.
Link: https://lore.kernel.org/r/20220927212306.823862-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
There is currently no way to report via extack in a structured way
that an attribute is missing. This leads to families resorting to
string messages.
Add a pair of attributes - @offset and @type for machine-readable
way of reporting missing attributes. The @offset points to the
nest which should have contained the attribute, @type is the
expected nla_type. The offset will be skipped if the attribute
is missing at the message level rather than inside a nest.
User space should be able to figure out which attribute enum
(AKA attribute space AKA attribute set) the nest pointed to by
@offset is using.
Reviewed-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Provide a bit of a brain dump of netlink related information
as documentation. Hopefully this will be useful to people
trying to navigate implementing YAML based parsing in languages
we won't be able to help with.
I started writing this doc while trying to figure out what
it'd take to widen the applicability of YAML to good old rtnl,
but the doc grew beyond that as it usually happens.
In all honesty a lot of this information is new to me as I usually
follow the "copy an existing example, drink to forget" process
of writing netlink user space, so reviews will be much appreciated.
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Acked-by: Jonathan Corbet <corbet@lwn.net>
Link: https://lore.kernel.org/r/20220819200221.422801-2-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Donald Hunter