linux-toradex.git/include/uapi/linux/netlink.h, branch v6.6-rc5

docs: netlink: clarify the historical baggage of Netlink flags

2022-09-30T01:39:39+00:00

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

netlink: add support for ext_ack missing attributes

2022-08-30T10:20:43+00:00

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 
Signed-off-by: Jakub Kicinski 
Signed-off-by: Paolo Abeni

net: improve and fix netlink kdoc

2022-08-23T23:10:23+00:00

Subsequent patch will render the kdoc from
include/uapi/linux/netlink.h into Documentation.
We need to fix the warnings. While at it move
the comments on struct nlmsghdr to a proper
kdoc comment.

Link: https://lore.kernel.org/r/20220819200221.422801-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski

Remove DECnet support from kernel

2022-08-22T13:26:30+00:00

DECnet is an obsolete network protocol that receives more attention
from kernel janitors than users. It belongs in computer protocol
history museum not in Linux kernel.

It has been "Orphaned" in kernel since 2010. The iproute2 support
for DECnet was dropped in 5.0 release. The documentation link on
Sourceforge says it is abandoned there as well.

Leave the UAPI alone to keep userspace programs compiling.
This means that there is still an empty neighbour table
for AF_DECNET.

The table of /proc/sys/net entries was updated to match
current directories and reformatted to be alphabetical.

Signed-off-by: Stephen Hemminger 
Acked-by: David Ahern 
Acked-by: Nikolay Aleksandrov 
Signed-off-by: David S. Miller

net: netlink: add NLM_F_BULK delete request modifier

2022-04-13T11:46:26+00:00

Add a new delete request modifier called NLM_F_BULK which, when
supported, would cause the request to delete multiple objects. The flag
is a convenient way to signal that a multiple delete operation is
requested which can be gradually added to different delete requests. In
order to make sure older kernels will error out if the operation is not
supported instead of doing something unintended we have to break a
required condition when implementing support for this flag, f.e. for
neighbors we will omit the mandatory mac address attribute.
Initially it will be used to add flush with filtering support for bridge
fdbs, but it also opens the door to add similar support to others.

Signed-off-by: Nikolay Aleksandrov 
Signed-off-by: David S. Miller

netlink: simplify NLMSG_DATA with NLMSG_HDRLEN

2021-06-10T19:51:33+00:00

The NLMSG_LENGTH(0) may confuse the API users,
NLMSG_HDRLEN is much more clear.

Besides, some code style problems are also fixed.
Signed-off-by: Chen Li 
Signed-off-by: David S. Miller

uapi: move constants from to

2020-12-15T20:13:36+00:00

and include  in UAPI headers instead of .

The reason is to avoid indirect  include when using
some network headers:  or others -> 
-> .

This indirect include causes on MUSL redefinition of struct sysinfo when
included both  and some of UAPI headers:

    In file included from x86_64-buildroot-linux-musl/sysroot/usr/include/linux/kernel.h:5,
                     from x86_64-buildroot-linux-musl/sysroot/usr/include/linux/netlink.h:5,
                     from ../include/tst_netlink.h:14,
                     from tst_crypto.c:13:
    x86_64-buildroot-linux-musl/sysroot/usr/include/linux/sysinfo.h:8:8: error: redefinition of `struct sysinfo'
     struct sysinfo {
            ^~~~~~~
    In file included from ../include/tst_safe_macros.h:15,
                     from ../include/tst_test.h:93,
                     from tst_crypto.c:11:
    x86_64-buildroot-linux-musl/sysroot/usr/include/sys/sysinfo.h:10:8: note: originally defined here

Link: https://lkml.kernel.org/r/20201015190013.8901-1-petr.vorel@gmail.com
Signed-off-by: Petr Vorel 
Suggested-by: Rich Felker 
Acked-by: Rich Felker 
Cc: Peter Korsgaard 
Cc: Baruch Siach 
Cc: Florian Weimer 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

netlink: export policy in extended ACK

2020-10-10T03:22:32+00:00

Add a new attribute NLMSGERR_ATTR_POLICY to the extended ACK
to advertise the policy, e.g. if an attribute was out of range,
you'll know the range that's permissible.

Add new NL_SET_ERR_MSG_ATTR_POL() and NL_SET_ERR_MSG_ATTR_POL()
macros to set this, since realistically it's only useful to do
this when the bad attribute (offset) is also returned.

Use it in lib/nlattr.c which practically does all the policy
validation.

v2:
 - add and use netlink_policy_dump_attr_size_estimate()
v3:
 - remove redundant break
v4:
 - really remove redundant break ... sorry

Reviewed-by: Jakub Kicinski 
Signed-off-by: Johannes Berg 
Signed-off-by: Jakub Kicinski

netlink: add mask validation

2020-10-06T13:25:55+00:00

We don't have good validation policy for existing unsigned int attrs
which serve as flags (for new ones we could use NLA_BITFIELD32).
With increased use of policy dumping having the validation be
expressed as part of the policy is important. Add validation
policy in form of a mask of supported/valid bits.

Support u64 in the uAPI to be future-proof, but really for now
the embedded mask member can only hold 32 bits, so anything with
bit 32+ set will always fail validation.

Signed-off-by: Jakub Kicinski 
Signed-off-by: David S. Miller

netlink: add infrastructure to expose policies to userspace

2020-05-01T00:51:42+00:00

Add, and use in generic netlink, helpers to dump out a netlink
policy to userspace, including all the range validation data,
nested policies etc.

This lets userspace discover what the kernel understands.

For families/commands other than generic netlink, the helpers
need to be used directly in an appropriate command, or we can
add some infrastructure (a new netlink family) that those can
register their policies with for introspection. I'm not that
familiar with non-generic netlink, so that's left out for now.

The data exposed to userspace also includes min and max length
for binary/string data, I've done that instead of letting the
userspace tools figure out whether min/max is intended based
on the type so that we can extend this later in the kernel, we
might want to just use the range data for example.

Because of this, I opted to not directly expose the NLA_*
values, even if some of them are already exposed via BPF, as
with min/max length we don't need to have different types here
for NLA_BINARY/NLA_MIN_LEN/NLA_EXACT_LEN, we just make them
all NL_ATTR_TYPE_BINARY with min/max length optionally set.

Similarly, we don't really need NLA_MSECS, and perhaps can
remove it in the future - but not if we encode it into the
userspace API now. It gets mapped to NL_ATTR_TYPE_U64 here.

Note that the exposing here corresponds to the strict policy
interpretation, and NLA_UNSPEC items are omitted entirely.
To get those, change them to NLA_MIN_LEN which behaves in
exactly the same way, but is exposed.

Signed-off-by: Johannes Berg 
Signed-off-by: David S. Miller