Validate the offset to read from module EEPROM as part of the netlink
policy and remove the corresponding check from the code.

This also makes it possible to query the offset range from user space:

 $ genl ctrl policy name ethtool
 ...
 ID: 0x14  policy[32]:attr[2]: type=U32 range:[0,255]
 ...

Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Validate the number of bytes to read from the module EEPROM as part of
the netlink policy and remove the corresponding check from the code.

This also makes it possible to query the length range from user space:

 $ genl ctrl policy name ethtool
 ...
 ID: 0x14  policy[32]:attr[3]: type=U32 range:[1,128]
 ...

Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

When get_module_eeprom_by_page() is not implemented by the driver, NULL
pointer dereference can occur [1].

Fix by testing if get_module_eeprom_by_page() is implemented instead of
get_module_info().

[1]
 BUG: kernel NULL pointer dereference, address: 0000000000000000
 [...]
 CPU: 0 PID: 251 Comm: ethtool Not tainted 5.13.0-rc3-custom-00940-g3822d0670c9d #989
 Call Trace:
  eeprom_prepare_data+0x101/0x2d0
  ethnl_default_doit+0xc2/0x290
  genl_family_rcv_msg_doit+0xdc/0x140
  genl_rcv_msg+0xd7/0x1d0
  netlink_rcv_skb+0x49/0xf0
  genl_rcv+0x1f/0x30
  netlink_unicast+0x1f6/0x2c0
  netlink_sendmsg+0x1f9/0x400
  __sys_sendto+0xe1/0x130
  __x64_sys_sendto+0x1b/0x20
  do_syscall_64+0x3a/0x70
  entry_SYSCALL_64_after_hwframe+0x44/0xae

Fixes: c97a31f66ebc ("ethtool: wire in generic SFP module access")
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Acked-by: Moshe Shemesh <moshe@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

If the device has a sfp bus attached, call its
sfp_get_module_eeprom_by_page() function, otherwise use the ethtool op
for the device. This follows how the IOCTL works.

Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

In case netlink get_module_eeprom_by_page() callback is not implemented
by the driver, try to call old get_module_info() and get_module_eeprom()
pair. Recalculate parameters to get_module_eeprom() offset and len using
page number and their sizes. Return error if this can't be done.

Signed-off-by: Vladyslav Tarasiuk <vladyslavt@nvidia.com>
Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

Define get_module_eeprom_by_page() ethtool callback and implement
netlink infrastructure.

get_module_eeprom_by_page() allows network drivers to dump a part of
module's EEPROM specified by page and bank numbers along with offset and
length. It is effectively a netlink replacement for get_module_info()
and get_module_eeprom() pair, which is needed due to emergence of
complex non-linear EEPROM layouts.

Signed-off-by: Vladyslav Tarasiuk <vladyslavt@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>