ethtool: netlink: always pass genl_info to .prepare_data

We had a number of bugs in the past because developers forgot
to fully test dumps, which pass NULL as info to .prepare_data.
.prepare_data implementations would try to access info->extack
leading to a null-deref.

Now that dumps and notifications can access struct genl_info
we can pass it in, and remove the info null checks.

Reviewed-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Tested-by: Vladimir Oltean <vladimir.oltean@nxp.com> # pause
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Link: https://lore.kernel.org/r/20230814214723.2924989-11-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

ethtool: link up ethnl_header_policy as a nested policy

To get the most out of parsing by the core, and to allow dumping
full policies we need to specify which policy applies to nested
attrs. For headers it's ethnl_header_policy.

$ sed -i 's@\(ETHTOOL_A_.*HEADER\].*=\) { .type = NLA_NESTED },@\1\n\t\tNLA_POLICY_NESTED(ethnl_header_policy),@' net/ethtool/*

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

ethtool: trim policy tables

Since ethtool uses strict attribute validation there's no need
to initialize all attributes in policy tables. 0 is NLA_UNSPEC
which is going to be rejected. Remove the NLA_REJECTs.

Similarly attributes above maxattrs are rejected, so there's
no need to always size the policy tables to ETHTOOL_A_..._MAX.

v2: - new patch

Suggested-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

ethtool: wire up get policies to ops

Wire up policies for get commands in struct nla_policy of the ethtool
family. Make use of genetlink code attr validation and parsing, as well
as allow dumping policies to user space.

For every ETHTOOL_MSG_*_GET:
- add 'ethnl_' prefix to policy name
- add extern declaration in net/ethtool/netlink.h
- wire up the policy & attr in ethtool_genl_ops[].
- remove .request_policy and .max_attr from ethnl_request_ops.

Obviously core only records the first "layer" of parsed attrs
so we still need to parse the sub-attrs of the nested header
attribute.

v2:
- merge of patches 1 and 2 from v1
- remove stray empty lines in ops
- also remove .max_attr

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

ethtool: provide timestamping information with TSINFO_GET request

Implement TSINFO_GET request to get timestamping information for a network
device. This is traditionally available via ETHTOOL_GET_TS_INFO ioctl
request.

Move part of ethtool_get_ts_info() into common.c so that ioctl and netlink
code use the same logic to get timestamping information from the device.

v3: use "TSINFO" rather than "TIMESTAMP", suggested by Richard Cochran

Signed-off-by: Michal Kubecek <mkubecek@suse.cz>
Acked-by: Richard Cochran <richardcochran@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>