netdev - Re: [RFC PATCH V3 net-next 1/5] ethtool: Allow network drivers to dump arbitrary EEPROM data

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Date:   Thu, 18 Mar 2021 16:25:33 +0200
From:   Moshe Shemesh <moshe@...dia.com>
To:     Andrew Lunn <andrew@...n.ch>
CC:     "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Adrian Pop <pop.adrian61@...il.com>,
        Michal Kubecek <mkubecek@...e.cz>,
        "Don Bollinger" <don@...bollingers.org>, <netdev@...r.kernel.org>,
        "Vladyslav Tarasiuk" <vladyslavt@...dia.com>
Subject: Re: [RFC PATCH V3 net-next 1/5] ethtool: Allow network drivers to
 dump arbitrary EEPROM data


On 3/18/2021 3:03 PM, Andrew Lunn wrote:
>
> On Mon, Mar 15, 2021 at 07:12:39PM +0200, Moshe Shemesh wrote:
>> From: Vladyslav Tarasiuk <vladyslavt@...dia.com>
>>
>> Define get_module_eeprom_data_by_page() ethtool callback and implement
>> netlink infrastructure.
>>
>> get_module_eeprom_data_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@...dia.com>
>> ---
>>   Documentation/networking/ethtool-netlink.rst |  34 ++++-
>>   include/linux/ethtool.h                      |   8 +-
>>   include/uapi/linux/ethtool.h                 |  25 +++
>>   include/uapi/linux/ethtool_netlink.h         |  19 +++
>>   net/ethtool/Makefile                         |   2 +-
>>   net/ethtool/eeprom.c                         | 153 +++++++++++++++++++
>>   net/ethtool/netlink.c                        |  10 ++
>>   net/ethtool/netlink.h                        |   2 +
>>   8 files changed, 249 insertions(+), 4 deletions(-)
>>   create mode 100644 net/ethtool/eeprom.c
>>
>> diff --git a/Documentation/networking/ethtool-netlink.rst b/Documentation/networking/ethtool-netlink.rst
>> index 05073482db05..25846b97632a 100644
>> --- a/Documentation/networking/ethtool-netlink.rst
>> +++ b/Documentation/networking/ethtool-netlink.rst
>> @@ -1280,6 +1280,36 @@ Kernel response contents:
>>   For UDP tunnel table empty ``ETHTOOL_A_TUNNEL_UDP_TABLE_TYPES`` indicates that
>>   the table contains static entries, hard-coded by the NIC.
>>
>> +EEPROM_DATA
>> +===========
>> +
>> +Fetch module EEPROM data dump.
>> +
>> +Request contents:
>> +
>> +  =====================================  ======  ==========================
>> +  ``ETHTOOL_A_EEPROM_DATA_HEADER``       nested  request header
>> +  ``ETHTOOL_A_EEPROM_DATA_OFFSET``       u32     offset within a page
>> +  ``ETHTOOL_A_EEPROM_DATA_LENGTH``       u32     amount of bytes to read
> I wonder if offset and length should be u8. At most, we should only be
> returning a 1/2 page, so 128 bytes. We don't need a u32.


That's right when page is given, but user may have commands that used to 
work on the ioctl KAPI with offset higher than one page.

>>   Request translation
>>   ===================
>>
>> @@ -1357,8 +1387,8 @@ are netlink only.
>>     ``ETHTOOL_GET_DUMP_FLAG``           n/a
>>     ``ETHTOOL_GET_DUMP_DATA``           n/a
>>     ``ETHTOOL_GET_TS_INFO``             ``ETHTOOL_MSG_TSINFO_GET``
>> -  ``ETHTOOL_GMODULEINFO``             n/a
>> -  ``ETHTOOL_GMODULEEEPROM``           n/a
>> +  ``ETHTOOL_GMODULEINFO``             ``ETHTOOL_MSG_MODULE_EEPROM_GET``
>> +  ``ETHTOOL_GMODULEEEPROM``           ``ETHTOOL_MSG_MODULE_EEPROM_GET``
>>     ``ETHTOOL_GEEE``                    ``ETHTOOL_MSG_EEE_GET``
>>     ``ETHTOOL_SEEE``                    ``ETHTOOL_MSG_EEE_SET``
>>     ``ETHTOOL_GRSSH``                   n/a
> We should check with Michal about this. It is not a direct replacement
> of the old IOCTL API, it is new API. He may want it documented
> differently.
Michal, please comment on where it should be.
>> +static int eeprom_data_parse_request(struct ethnl_req_info *req_info, struct nlattr **tb,
>> +                                  struct netlink_ext_ack *extack)
>> +{
>> +     struct eeprom_data_req_info *request = EEPROM_DATA_REQINFO(req_info);
>> +     struct net_device *dev = req_info->dev;
>> +
>> +     if (!tb[ETHTOOL_A_EEPROM_DATA_OFFSET] ||
>> +         !tb[ETHTOOL_A_EEPROM_DATA_LENGTH] ||
>> +         !tb[ETHTOOL_A_EEPROM_DATA_I2C_ADDRESS])
>> +             return -EINVAL;
>> +
>> +     request->i2c_address = nla_get_u8(tb[ETHTOOL_A_EEPROM_DATA_I2C_ADDRESS]);
>> +     if (request->i2c_address > ETH_MODULE_MAX_I2C_ADDRESS)
>> +             return -EINVAL;
>> +
>> +     request->offset = nla_get_u32(tb[ETHTOOL_A_EEPROM_DATA_OFFSET]);
>> +     request->length = nla_get_u32(tb[ETHTOOL_A_EEPROM_DATA_LENGTH]);
>> +     if (tb[ETHTOOL_A_EEPROM_DATA_PAGE] &&
>> +         dev->ethtool_ops->get_module_eeprom_data_by_page &&
>> +         request->offset + request->length > ETH_MODULE_EEPROM_PAGE_LEN)
>> +             return -EINVAL;
> You need to watch out for overflows here. 0xfffffff0 + 0x20 is less
> than ETH_MODULE_EEPROM_PAGE_LEN when it wraps around, but will cause
> bad things to happen.
Ack.
>        Andrew