net: reformat kdoc return statements

kernel-doc -Wall warns about missing Return: statement for non-void
functions. We have a number of kdocs in our headers which are missing
the colon, IOW they use

net: reformat kdoc return statements

kernel-doc -Wall warns about missing Return: statement for non-void
functions. We have a number of kdocs in our headers which are missing
the colon, IOW they use
* Return some value
or
* Returns some value

Having the colon makes some sense, it should help kdoc parser avoid
false positives. So add them. This is mostly done with a sed script,
and removing the unnecessary cases (mostly the comments which aren't
kdoc).

Acked-by: Johannes Berg <[email protected]>
Acked-by: Richard Cochran <[email protected]>
Acked-by: Sergey Ryazanov <[email protected]>
Reviewed-by: Edward Cree <[email protected]>
Acked-by: Alexandra Winter <[email protected]>
Acked-by: Pablo Neira Ayuso <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

show more ...

genetlink: hold RCU in genlmsg_mcast()

While running net selftests with CONFIG_PROVE_RCU_LIST=y I saw
one lockdep splat [1].

genlmsg_mcast() uses for_each_net_rcu(), and must therefore hold RCU.

I

genetlink: hold RCU in genlmsg_mcast()

While running net selftests with CONFIG_PROVE_RCU_LIST=y I saw
one lockdep splat [1].

genlmsg_mcast() uses for_each_net_rcu(), and must therefore hold RCU.

Instead of letting all callers guard genlmsg_multicast_allns()
with a rcu_read_lock()/rcu_read_unlock() pair, do it in genlmsg_mcast().

This also means the @flags parameter is useless, we need to always use
GFP_ATOMIC.

[1]
[10882.424136] =============================
[10882.424166] WARNING: suspicious RCU usage
[10882.424309] 6.12.0-rc2-virtme #1156 Not tainted
[10882.424400] -----------------------------
[10882.424423] net/netlink/genetlink.c:1940 RCU-list traversed in non-reader section!!
[10882.424469]
other info that might help us debug this:

[10882.424500]
rcu_scheduler_active = 2, debug_locks = 1
[10882.424744] 2 locks held by ip/15677:
[10882.424791] #0: ffffffffb6b491b0 (cb_lock){++++}-{3:3}, at: genl_rcv (net/netlink/genetlink.c:1219)
[10882.426334] #1: ffffffffb6b49248 (genl_mutex){+.+.}-{3:3}, at: genl_rcv_msg (net/netlink/genetlink.c:61 net/netlink/genetlink.c:57 net/netlink/genetlink.c:1209)
[10882.426465]
stack backtrace:
[10882.426805] CPU: 14 UID: 0 PID: 15677 Comm: ip Not tainted 6.12.0-rc2-virtme #1156
[10882.426919] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
[10882.427046] Call Trace:
[10882.427131] <TASK>
[10882.427244] dump_stack_lvl (lib/dump_stack.c:123)
[10882.427335] lockdep_rcu_suspicious (kernel/locking/lockdep.c:6822)
[10882.427387] genlmsg_multicast_allns (net/netlink/genetlink.c:1940 (discriminator 7) net/netlink/genetlink.c:1977 (discriminator 7))
[10882.427436] l2tp_tunnel_notify.constprop.0 (net/l2tp/l2tp_netlink.c:119) l2tp_netlink
[10882.427683] l2tp_nl_cmd_tunnel_create (net/l2tp/l2tp_netlink.c:253) l2tp_netlink
[10882.427748] genl_family_rcv_msg_doit (net/netlink/genetlink.c:1115)
[10882.427834] genl_rcv_msg (net/netlink/genetlink.c:1195 net/netlink/genetlink.c:1210)
[10882.427877] ? __pfx_l2tp_nl_cmd_tunnel_create (net/l2tp/l2tp_netlink.c:186) l2tp_netlink
[10882.427927] ? __pfx_genl_rcv_msg (net/netlink/genetlink.c:1201)
[10882.427959] netlink_rcv_skb (net/netlink/af_netlink.c:2551)
[10882.428069] genl_rcv (net/netlink/genetlink.c:1220)
[10882.428095] netlink_unicast (net/netlink/af_netlink.c:1332 net/netlink/af_netlink.c:1357)
[10882.428140] netlink_sendmsg (net/netlink/af_netlink.c:1901)
[10882.428210] ____sys_sendmsg (net/socket.c:729 (discriminator 1) net/socket.c:744 (discriminator 1) net/socket.c:2607 (discriminator 1))

Fixes: 33f72e6f0c67 ("l2tp : multicast notification to the registered listeners")
Signed-off-by: Eric Dumazet <[email protected]>
Cc: James Chapman <[email protected]>
Cc: Tom Parkin <[email protected]>
Cc: Johannes Berg <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

show more ...

genetlink: extend info user-storage to match NL cb ctx

This allows a more uniform implementation of non-dump and dump
operations, and will be used later in the series to avoid some
per-operation all

genetlink: extend info user-storage to match NL cb ctx

This allows a more uniform implementation of non-dump and dump
operations, and will be used later in the series to avoid some
per-operation allocation.

Additionally rename the NL_ASSERT_DUMP_CTX_FITS macro, to
fit a more extended usage.

Suggested-by: Jakub Kicinski <[email protected]>
Reviewed-by: Jakub Kicinski <[email protected]>
Reviewed-by: Jiri Pirko <[email protected]>
Signed-off-by: Paolo Abeni <[email protected]>
Link: https://patch.msgid.link/1130cc2896626b84587a2a5f96a5c6829638f4da.1728460186.git.pabeni@redhat.com
Signed-off-by: Jakub Kicinski <[email protected]>

show more ...

genetlink: remove linux/genetlink.h

genetlink.h is a shell of what used to be a combined uAPI
and kernel header over a decade ago. It has fewer than
10 lines of code. Merge it into net/genetlink.h.

genetlink: remove linux/genetlink.h

genetlink.h is a shell of what used to be a combined uAPI
and kernel header over a decade ago. It has fewer than
10 lines of code. Merge it into net/genetlink.h.
In some ways it'd be better to keep the combined header
under linux/ but it would make looking through git history
harder.

Acked-by: Sven Eckelmann <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

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genetlink: make info in GENL_REQ_ATTR_CHECK() const

Make the local variable in GENL_REQ_ATTR_CHECK() const.
genl_info_dump() returns a const pointer, so the macro
is currently hard to use in genl du

genetlink: make info in GENL_REQ_ATTR_CHECK() const

Make the local variable in GENL_REQ_ATTR_CHECK() const.
genl_info_dump() returns a const pointer, so the macro
is currently hard to use in genl dumps.

Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

show more ...

genetlink: Add per family bind/unbind callbacks

Add genetlink family bind()/unbind() callbacks when adding/removing
multicast group to/from netlink client socket via setsockopt() or
bind() syscall.

genetlink: Add per family bind/unbind callbacks

Add genetlink family bind()/unbind() callbacks when adding/removing
multicast group to/from netlink client socket via setsockopt() or
bind() syscall.

They can be used to track if consumers of netlink multicast messages
emerge or disappear. Thus, a client implementing callbacks, can now
send events only when there are active consumers, preventing unnecessary
work when none exist.

Suggested-by: Jakub Kicinski <[email protected]>
Signed-off-by: Stanislaw Gruszka <[email protected]>
Reviewed-by: Jiri Pirko <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

show more ...

genetlink: Use internal flags for multicast groups

As explained in commit e03781879a0d ("drop_monitor: Require
'CAP_SYS_ADMIN' when joining "events" group"), the "flags" field in the
multicast group

genetlink: Use internal flags for multicast groups

As explained in commit e03781879a0d ("drop_monitor: Require
'CAP_SYS_ADMIN' when joining "events" group"), the "flags" field in the
multicast group structure reuses uAPI flags despite the field not being
exposed to user space. This makes it impossible to extend its use
without adding new uAPI flags, which is inappropriate for internal
kernel checks.

Solve this by adding internal flags (i.e., "GENL_MCAST_*") and convert
the existing users to use them instead of the uAPI flags.

Tested using the reproducers in commit 44ec98ea5ea9 ("psample: Require
'CAP_NET_ADMIN' when joining "packets" group") and commit e03781879a0d
("drop_monitor: Require 'CAP_SYS_ADMIN' when joining "events" group").

No functional changes intended.

Signed-off-by: Ido Schimmel <[email protected]>
Reviewed-by: Mat Martineau <[email protected]>
Reviewed-by: Andy Shevchenko <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

show more ...

genetlink: introduce helpers to do filtered multicast

Currently it is possible for netlink kernel user to pass custom
filter function to broadcast send function netlink_broadcast_filtered().
However

genetlink: introduce helpers to do filtered multicast

Currently it is possible for netlink kernel user to pass custom
filter function to broadcast send function netlink_broadcast_filtered().
However, this is not exposed to multicast send and to generic
netlink users.

Extend the api and introduce a netlink helper nlmsg_multicast_filtered()
and a generic netlink helper genlmsg_multicast_netns_filtered()
to allow generic netlink families to specify filter function
while sending multicast messages.

Signed-off-by: Jiri Pirko <[email protected]>
Signed-off-by: Paolo Abeni <[email protected]>

show more ...

genetlink: introduce per-sock family private storage

Introduce an xarray for Generic netlink family to store per-socket
private. Initialize this xarray only if family uses per-socket privs.

Introdu

genetlink: introduce per-sock family private storage

Introduce an xarray for Generic netlink family to store per-socket
private. Initialize this xarray only if family uses per-socket privs.

Introduce genl_sk_priv_get() to get the socket priv pointer for a family
and initialize it in case it does not exist.
Introduce __genl_sk_priv_get() to obtain socket priv pointer for a
family under RCU read lock.

Allow family to specify the priv size, init() and destroy() callbacks.

Signed-off-by: Jiri Pirko <[email protected]>
Signed-off-by: Paolo Abeni <[email protected]>

show more ...

drop_monitor: Require 'CAP_SYS_ADMIN' when joining "events" group

The "NET_DM" generic netlink family notifies drop locations over the
"events" multicast group. This is problematic since by default

drop_monitor: Require 'CAP_SYS_ADMIN' when joining "events" group

The "NET_DM" generic netlink family notifies drop locations over the
"events" multicast group. This is problematic since by default generic
netlink allows non-root users to listen to these notifications.

Fix by adding a new field to the generic netlink multicast group
structure that when set prevents non-root users or root without the
'CAP_SYS_ADMIN' capability (in the user namespace owning the network
namespace) from joining the group. Set this field for the "events"
group. Use 'CAP_SYS_ADMIN' rather than 'CAP_NET_ADMIN' because of the
nature of the information that is shared over this group.

Note that the capability check in this case will always be performed
against the initial user namespace since the family is not netns aware
and only operates in the initial network namespace.

A new field is added to the structure rather than using the "flags"
field because the existing field uses uAPI flags and it is inappropriate
to add a new uAPI flag for an internal kernel check. In net-next we can
rework the "flags" field to use internal flags and fold the new field
into it. But for now, in order to reduce the amount of changes, add a
new field.

Since the information can only be consumed by root, mark the control
plane operations that start and stop the tracing as root-only using the
'GENL_ADMIN_PERM' flag.

Tested using [1].

Before:

# capsh -- -c ./dm_repo
# capsh --drop=cap_sys_admin -- -c ./dm_repo

After:

# capsh -- -c ./dm_repo
# capsh --drop=cap_sys_admin -- -c ./dm_repo
Failed to join "events" multicast group

[1]
$ cat dm.c
#include <stdio.h>
#include <netlink/genl/ctrl.h>
#include <netlink/genl/genl.h>
#include <netlink/socket.h>

int main(int argc, char **argv)
{
struct nl_sock *sk;
int grp, err;

sk = nl_socket_alloc();
if (!sk) {
fprintf(stderr, "Failed to allocate socket\n");
return -1;
}

err = genl_connect(sk);
if (err) {
fprintf(stderr, "Failed to connect socket\n");
return err;
}

grp = genl_ctrl_resolve_grp(sk, "NET_DM", "events");
if (grp < 0) {
fprintf(stderr,
"Failed to resolve \"events\" multicast group\n");
return grp;
}

err = nl_socket_add_memberships(sk, grp, NFNLGRP_NONE);
if (err) {
fprintf(stderr, "Failed to join \"events\" multicast group\n");
return err;
}

return 0;
}
$ gcc -I/usr/include/libnl3 -lnl-3 -lnl-genl-3 -o dm_repo dm.c

Fixes: 9a8afc8d3962 ("Network Drop Monitor: Adding drop monitor implementation & Netlink protocol")
Reported-by: "The UK's National Cyber Security Centre (NCSC)" <[email protected]>
Signed-off-by: Ido Schimmel <[email protected]>
Reviewed-by: Jacob Keller <[email protected]>
Reviewed-by: Jiri Pirko <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

show more ...

genetlink: add genlmsg_iput() API

Add some APIs and helpers required for convenient construction
of replies and notifications based on struct genl_info.

Reviewed-by: Jiri Pirko <[email protected]>
Li

genetlink: add genlmsg_iput() API

Add some APIs and helpers required for convenient construction
of replies and notifications based on struct genl_info.

Reviewed-by: Jiri Pirko <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

show more ...

genetlink: add a family pointer to struct genl_info

Having family in struct genl_info is quite useful. It cuts
down the number of arguments which need to be passed to
helpers which already take stru

genetlink: add a family pointer to struct genl_info

Having family in struct genl_info is quite useful. It cuts
down the number of arguments which need to be passed to
helpers which already take struct genl_info.

Reviewed-by: Jiri Pirko <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

show more ...

genetlink: use attrs from struct genl_info

Since dumps carry struct genl_info now, use the attrs pointer
from genl_info and remove the one in struct genl_dumpit_info.

Reviewed-by: Johannes Berg <jo

genetlink: use attrs from struct genl_info

Since dumps carry struct genl_info now, use the attrs pointer
from genl_info and remove the one in struct genl_dumpit_info.

Reviewed-by: Johannes Berg <[email protected]>
Reviewed-by: Miquel Raynal <[email protected]>
Reviewed-by: Jiri Pirko <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

show more ...

genetlink: add struct genl_info to struct genl_dumpit_info

Netlink GET implementations must currently juggle struct genl_info
and struct netlink_callback, depending on whether they were called
from

genetlink: add struct genl_info to struct genl_dumpit_info

Netlink GET implementations must currently juggle struct genl_info
and struct netlink_callback, depending on whether they were called
from doit or dumpit.

Add genl_info to the dump state and populate the fields.
This way implementations can simply pass struct genl_info around.

Reviewed-by: Jiri Pirko <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

show more ...

genetlink: remove userhdr from struct genl_info

Only three families use info->userhdr today and going forward
we discourage using fixed headers in new families.
So having the pointer to user header

genetlink: remove userhdr from struct genl_info

Only three families use info->userhdr today and going forward
we discourage using fixed headers in new families.
So having the pointer to user header in struct genl_info
is an overkill. Compute the header pointer at runtime.

Reviewed-by: Johannes Berg <[email protected]>
Reviewed-by: Jiri Pirko <[email protected]>
Reviewed-by: Aaron Conole <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

show more ...

genetlink: make genl_info->nlhdr const

struct netlink_callback has a const nlh pointer, make the
pointer in struct genl_info const as well, to make copying
between the two easier.

Reviewed-by: Jiri

genetlink: make genl_info->nlhdr const

struct netlink_callback has a const nlh pointer, make the
pointer in struct genl_info const as well, to make copying
between the two easier.

Reviewed-by: Jiri Pirko <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

show more ...

mptcp: more detailed error reporting on endpoint creation

Endpoint creation can fail for a number of reasons; in case of failure
append the error number to the extended ack message, using a newly
in

mptcp: more detailed error reporting on endpoint creation

Endpoint creation can fail for a number of reasons; in case of failure
append the error number to the extended ack message, using a newly
introduced generic helper.

Additionally let mptcp_pm_nl_append_new_local_addr() report different
error reasons.

Reviewed-by: Mat Martineau <[email protected]>
Signed-off-by: Paolo Abeni <[email protected]>
Signed-off-by: Mat Martineau <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

show more ...

genetlink: allow families to use split ops directly

Let families to hook in the new split ops.

They are more flexible and should not be much larger than
full ops. Each split op is 40B while full op

genetlink: allow families to use split ops directly

Let families to hook in the new split ops.

They are more flexible and should not be much larger than
full ops. Each split op is 40B while full op is 48B.
Devlink for example has 54 dos and 19 dumps, 2 of the dumps
do not have a do -> 56 full commands = 2688B.
Split ops would have taken 2920B, so 9% more space while
allowing individual per/post doit and per-type policies.

Signed-off-by: Jakub Kicinski <[email protected]>
Reviewed-by: Jacob Keller <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

show more ...

genetlink: introduce split op representation

We currently have two forms of operations - small ops and "full" ops
(or just ops). The former does not have pointers for some of the less
commonly used

genetlink: introduce split op representation

We currently have two forms of operations - small ops and "full" ops
(or just ops). The former does not have pointers for some of the less
commonly used features (namely dump start/done and policy).

The "full" ops, however, still don't contain all the necessary
information. In particular the policy is per command ID, while
do and dump often accept different attributes. It's also not
possible to define different pre_doit and post_doit callbacks
for different commands within the family.

At the same time a lot of commands do not support dumping and
therefore all the dump-related information is wasted space.

Create a new command representation which can hold info about
a do implementation or a dump implementation, but not both at
the same time.

Use this new representation on the command execution path
(genl_family_rcv_msg) as we either run a do or a dump and
don't have to create a "full" op there.

Signed-off-by: Jakub Kicinski <[email protected]>
Reviewed-by: Jacob Keller <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

show more ...

genetlink: move the private fields in struct genl_family

Move the private fields down to form a "private section".
Use the kdoc "private:" label comment thing to hide them
from the main kdoc comment

genetlink: move the private fields in struct genl_family

Move the private fields down to form a "private section".
Use the kdoc "private:" label comment thing to hide them
from the main kdoc comment.

Signed-off-by: Jakub Kicinski <[email protected]>
Reviewed-by: Johannes Berg <[email protected]>
Reviewed-by: Jacob Keller <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

show more ...

genetlink: piggy back on resv_op to default to a reject policy

To keep backward compatibility we used to leave attribute parsing
to the family if no policy is specified. This becomes tedious as
we m

genetlink: piggy back on resv_op to default to a reject policy

To keep backward compatibility we used to leave attribute parsing
to the family if no policy is specified. This becomes tedious as
we move to more strict validation. Families must define reject all
policies if they don't want any attributes accepted.

Piggy back on the resv_start_op field as the switchover point.
AFAICT only ethtool has added new commands since the resv_start_op
was defined, and it has per-op policies so this should be a no-op.

Nonetheless the patch should still go into v6.1 for consistency.

Link: https://lore.kernel.org/all/[email protected]/
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

show more ...

genetlink: fix kdoc warnings

Address a bunch of kdoc warnings:

include/net/genetlink.h:81: warning: Function parameter or member 'module' not described in 'genl_family'
include/net/genetlink.h:243:

genetlink: fix kdoc warnings

Address a bunch of kdoc warnings:

include/net/genetlink.h:81: warning: Function parameter or member 'module' not described in 'genl_family'
include/net/genetlink.h:243: warning: expecting prototype for struct genl_info. Prototype was for struct genl_dumpit_info instead
include/net/genetlink.h:419: warning: Function parameter or member 'net' not described in 'genlmsg_unicast'
include/net/genetlink.h:438: warning: expecting prototype for gennlmsg_data(). Prototype was for genlmsg_data() instead
include/net/genetlink.h:244: warning: Function parameter or member 'op' not described in 'genl_dumpit_info'

Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

show more ...

netlink: add helpers for extack attr presence checking

Being able to check attribute presence and set extack
if not on one line is handy, add helpers.

Reviewed-by: Johannes Berg <johannes@sipsoluti

netlink: add helpers for extack attr presence checking

Being able to check attribute presence and set extack
if not on one line is handy, add helpers.

Reviewed-by: Johannes Berg <[email protected]>
Signed-off-by: Jakub Kicinski <[email protected]>
Signed-off-by: Paolo Abeni <[email protected]>

show more ...

genetlink: start to validate reserved header bytes

We had historically not checked that genlmsghdr.reserved
is 0 on input which prevents us from using those precious
bytes in the future.

One use ca

genetlink: start to validate reserved header bytes

We had historically not checked that genlmsghdr.reserved
is 0 on input which prevents us from using those precious
bytes in the future.

One use case would be to extend the cmd field, which is
currently just 8 bits wide and 256 is not a lot of commands
for some core families.

To make sure that new families do the right thing by default
put the onus of opting out of validation on existing families.

Signed-off-by: Jakub Kicinski <[email protected]>
Acked-by: Paul Moore <[email protected]> (NetLabel)
Signed-off-by: David S. Miller <[email protected]>

show more ...

net: add missing kdoc for struct genl_multicast_group::flags

Multicast group flags were added in commit 4d54cc32112d ("mptcp: avoid
lock_fast usage in accept path"), but it missed adding the kdoc.

net: add missing kdoc for struct genl_multicast_group::flags

Multicast group flags were added in commit 4d54cc32112d ("mptcp: avoid
lock_fast usage in accept path"), but it missed adding the kdoc.

Mention which flags go into that field, and do the same for
op structs.

Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

show more ...