These methods generally consume ownership of the provided skb, so even
if an error path is encountered, the skb is freed. This is because the
very first thing they do after some initial setup is to unconditionally
consume the skb via consume_skb(skb). Any subsequent errors lead to the
core netlink layer freeing the skb.
However, there is one check that occurs before ownership is passed,
which is the check for the group index. So if this error condition is
encountered, then the skb is leaked. This error condition is generally
considered a violation of the netlink API, so it's not expected to occur
under normal circumstances. For the same reason, no callers check for
this error condition, and no callers need to be adjusted. However, we
should still follow the same ownership semantics of the rest of the
function. Thus, free the skb in this codepath.
Suggested-by: Andrew Lunn <andrew@lunn.ch>
Suggested-by: Matthew Maurer <mmaurer@google.com>
Fixes: 2a94fe48f3 ("genetlink: make multicast groups const, prevent abuse")
Link: https://lore.kernel.org/r/845b36ba-7b3a-41f2-acb2-b284f253e2ca@lunn.ch
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
Link: https://patch.msgid.link/20260506-genlmsg-return-v2-1-a63ee2a055d6@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Cross-merge networking fixes after downstream PR (net-6.12-rc4).
Conflicts:
107a034d5c ("net/mlx5: qos: Store rate groups in a qos domain")
1da9cfd6c4 ("net/mlx5: Unregister notifier on eswitch init failure")
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
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 <sven@narfation.org>
Link: https://lore.kernel.org/r/20240329175710.291749-4-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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 <kuba@kernel.org>
Signed-off-by: Stanislaw Gruszka <stanislaw.gruszka@linux.intel.com>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Link: https://lore.kernel.org/r/20240212161615.161935-2-stanislaw.gruszka@linux.intel.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
As explained in commit e03781879a ("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 44ec98ea5e ("psample: Require
'CAP_NET_ADMIN' when joining "packets" group") and commit e03781879a
("drop_monitor: Require 'CAP_SYS_ADMIN' when joining "events" group").
No functional changes intended.
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Reviewed-by: Mat Martineau <martineau@kernel.org>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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 <jiri@nvidia.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
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 <jiri@nvidia.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
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: 9a8afc8d39 ("Network Drop Monitor: Adding drop monitor implementation & Netlink protocol")
Reported-by: "The UK's National Cyber Security Centre (NCSC)" <security@ncsc.gov.uk>
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Link: https://lore.kernel.org/r/20231206213102.1824398-3-idosch@nvidia.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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 <jiri@nvidia.com>
Link: https://lore.kernel.org/r/20230814214723.2924989-5-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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 <mathew.j.martineau@linux.intel.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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 <kuba@kernel.org>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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 <kuba@kernel.org>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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 <kuba@kernel.org>
Reviewed-by: Johannes Berg <johannes@sipsolutions.net>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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/20221019125745.3f2e7659@kernel.org/
Link: https://lore.kernel.org/r/20221021193532.1511293-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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/20221018231310.1040482-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Alice Ryhl
Asbjørn Sloth Tønnesen
Jakub Kicinski
Paolo Abeni
Eric Dumazet
Stanislaw Gruszka
Ido Schimmel
Jiri Pirko