Date:   Thu, 4 Mar 2021 16:50:22 -0800
From:   "Don Bollinger" <don@...bollingers.org>
To:     "'Moshe Shemesh'" <moshe@...dia.com>,
        "'David S. Miller'" <davem@...emloft.net>,
        "'Jakub Kicinski'" <kuba@...nel.org>,
        "'Andrew Lunn'" <andrew@...n.ch>,
        "'Adrian Pop'" <pop.adrian61@...il.com>,
        "'Michal Kubecek'" <mkubecek@...e.cz>, <netdev@...r.kernel.org>
Cc:     "'Vladyslav Tarasiuk'" <vladyslavt@...dia.com>,
        <don@...bollingers.org>
Subject: RE: [RFC PATCH V2 net-next 1/5] ethtool: Allow network drivers to dump arbitrary EEPROM data

On Thu, Mar 04, 2021 at 10:57AM-0800, 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>
> ---
>  include/linux/ethtool.h              |   7 +-
>  include/uapi/linux/ethtool.h         |  26 +++++
>  include/uapi/linux/ethtool_netlink.h |  19 ++++
>  net/ethtool/Makefile                 |   2 +-
>  net/ethtool/eeprom.c                 | 157 +++++++++++++++++++++++++++
>  net/ethtool/netlink.c                |  10 ++
>  net/ethtool/netlink.h                |   2 +
>  7 files changed, 221 insertions(+), 2 deletions(-)  create mode 100644
> net/ethtool/eeprom.c
> 
> diff --git a/include/linux/ethtool.h b/include/linux/ethtool.h index
> ec4cd3921c67..2f65aae5f492 100644
> --- a/include/linux/ethtool.h
> +++ b/include/linux/ethtool.h
> @@ -81,6 +81,7 @@ enum {
>  #define ETH_RSS_HASH_NO_CHANGE	0
> 
>  struct net_device;
> +struct netlink_ext_ack;
> 
>  /* Some generic methods drivers may use in their ethtool_ops */
>  u32 ethtool_op_get_link(struct net_device *dev); @@ -410,6 +411,8 @@
> struct ethtool_pause_stats {
>   * @get_ethtool_phy_stats: Return extended statistics about the PHY
> device.
>   *	This is only useful if the device maintains PHY statistics and
>   *	cannot use the standard PHY library helpers.
> + * @get_module_eeprom_data_by_page: Get a region of plug-in module
> EEPROM data
> + *	from specified page. Returns a negative error code or zero.
>   *
>   * All operations are optional (i.e. the function pointer may be set
>   * to %NULL) and callers must take this into account.  Callers must @@
-515,6
> +518,9 @@ struct ethtool_ops {
>  				   const struct ethtool_tunable *, void *);
>  	int	(*set_phy_tunable)(struct net_device *,
>  				   const struct ethtool_tunable *, const
void
> *);
> +	int	(*get_module_eeprom_data_by_page)(struct net_device
> *dev,
> +						  const struct
> ethtool_eeprom_data *page,
> +						  struct netlink_ext_ack
> *extack);
>  };
> 
>  int ethtool_check_ops(const struct ethtool_ops *ops); @@ -538,7 +544,6
> @@ int ethtool_virtdev_set_link_ksettings(struct net_device *dev,
>  				       const struct ethtool_link_ksettings
*cmd,
>  				       u32 *dev_speed, u8 *dev_duplex);
> 
> -struct netlink_ext_ack;
>  struct phy_device;
>  struct phy_tdr_config;
> 
> diff --git a/include/uapi/linux/ethtool.h b/include/uapi/linux/ethtool.h
index
> cde753bb2093..2459571fc1d1 100644
> --- a/include/uapi/linux/ethtool.h
> +++ b/include/uapi/linux/ethtool.h
> @@ -340,6 +340,28 @@ struct ethtool_eeprom {
>  	__u8	data[0];
>  };
> 
> +/**
> + * struct ethtool_eeprom_data - EEPROM dump from specified page
> + * @offset: Offset within the specified EEPROM page to begin read, in
> bytes.

Note here that bytes at offset 0-127 are the same for every page of the
module, only bytes at offset 128 and higher are actually paged.

> + * @length: Number of bytes to read.
> + * @page: Page number to read from.
> + * @bank: Page bank number to read from, if applicable by EEPROM spec.
> + * @i2c_address: I2C address of a page. Value less than 0x7f expected.
> Most
> + *	EEPROMs use 0x50 or 0x51.

The standards are all very clear, the only legal values are 0x50 and 0x51.
It isn't 'expected', it is required.  I suggest that 0xA0 and 0xA2 also be
silently accepted, and translated to 0x50 and 0x51 respectively.  Some
of the specs use A0/A2 instead of 0x50/0x51.  They actually mean the
same thing.

> + * @data: Pointer to buffer with EEPROM data of @length size.
> + *
> + * This can be used to manage pages during EEPROM dump in ethtool and
> +pass
> + * required information to the driver.
> + */
> +struct ethtool_eeprom_data {
> +	__u32	offset;
> +	__u32	length;
> +	__u32	page;
> +	__u32	bank;
> +	__u32	i2c_address;
> +	__u8	*data;
> +};
> +
>  /**
>   * struct ethtool_eee - Energy Efficient Ethernet information
>   * @cmd: ETHTOOL_{G,S}EEE
> @@ -1865,6 +1887,10 @@ static inline int ethtool_validate_duplex(__u8
> duplex)
>  #define ETH_MODULE_SFF_8636_MAX_LEN     640
>  #define ETH_MODULE_SFF_8436_MAX_LEN     640
> 
> +#define ETH_MODULE_EEPROM_MAX_LEN	640

Please don't add this MAX_LEN constant.  Even better, remove
the two above it as well.

The proper value for all 3 of these MAX_LEN items is the
architectural limit imposed by the 8 bit page register plus the constant
lower page (hence 257*128 bytes).  The 8436 and 8636
specs do not actually limit these devices to 640 bytes (3 pages). 

There is no MAX_LEN listed for SFF_8472.  If there is one, it should
actually be 259 * 128 bytes (to account for 256 more bytes on the
unpaged 0x50 i2c address). 

 Nor is there one for CMIS.  The maximum
architected length for CMIS is (257*128) + (127 * 16 * 128).  That's
the QSFP max length plus 127 more banks of 16 pages.

> +#define ETH_MODULE_EEPROM_PAGE_LEN	256
> +#define ETH_MODULE_MAX_I2C_ADDRESS	0x7f

Actually there are only two legal values for the i2c address (0x50, 0x51).
Rather than defining a MAX address, consider defining the legal values,
or...  is it used at all?  Leave it out?

> +
>  /* Reset flags */
>  /* The reset() operation must clear the flags for the components which
>   * were actually reset.  On successful return, the flags indicate the
diff --git
> a/include/uapi/linux/ethtool_netlink.h
> b/include/uapi/linux/ethtool_netlink.h
> index a286635ac9b8..60dd848d0b54 100644
> --- a/include/uapi/linux/ethtool_netlink.h
> +++ b/include/uapi/linux/ethtool_netlink.h
> @@ -42,6 +42,7 @@ enum {
>  	ETHTOOL_MSG_CABLE_TEST_ACT,
>  	ETHTOOL_MSG_CABLE_TEST_TDR_ACT,
>  	ETHTOOL_MSG_TUNNEL_INFO_GET,
> +	ETHTOOL_MSG_EEPROM_DATA_GET,
> 
>  	/* add new constants above here */
>  	__ETHTOOL_MSG_USER_CNT,
> @@ -80,6 +81,7 @@ enum {
>  	ETHTOOL_MSG_CABLE_TEST_NTF,
>  	ETHTOOL_MSG_CABLE_TEST_TDR_NTF,
>  	ETHTOOL_MSG_TUNNEL_INFO_GET_REPLY,
> +	ETHTOOL_MSG_EEPROM_DATA_GET_REPLY,
> 
>  	/* add new constants above here */
>  	__ETHTOOL_MSG_KERNEL_CNT,
> @@ -629,6 +631,23 @@ enum {
>  	ETHTOOL_A_TUNNEL_INFO_MAX =
> (__ETHTOOL_A_TUNNEL_INFO_CNT - 1)  };
> 
> +/* MODULE EEPROM DATA */
> +
> +enum {
> +	ETHTOOL_A_EEPROM_DATA_UNSPEC,
> +	ETHTOOL_A_EEPROM_DATA_HEADER,
> +
> +	ETHTOOL_A_EEPROM_DATA_OFFSET,
> +	ETHTOOL_A_EEPROM_DATA_LENGTH,
> +	ETHTOOL_A_EEPROM_DATA_PAGE,
> +	ETHTOOL_A_EEPROM_DATA_BANK,
> +	ETHTOOL_A_EEPROM_DATA_I2C_ADDRESS,
> +	ETHTOOL_A_EEPROM_DATA,
> +
> +	__ETHTOOL_A_EEPROM_DATA_CNT,
> +	ETHTOOL_A_EEPROM_DATA_MAX =
> (__ETHTOOL_A_EEPROM_DATA_CNT - 1) };
> +
>  /* generic netlink info */
>  #define ETHTOOL_GENL_NAME "ethtool"
>  #define ETHTOOL_GENL_VERSION 1
> diff --git a/net/ethtool/Makefile b/net/ethtool/Makefile index
> 7a849ff22dad..d604346bc074 100644
> --- a/net/ethtool/Makefile
> +++ b/net/ethtool/Makefile
> @@ -7,4 +7,4 @@ obj-$(CONFIG_ETHTOOL_NETLINK)	+= ethtool_nl.o
>  ethtool_nl-y	:= netlink.o bitset.o strset.o linkinfo.o linkmodes.o \
>  		   linkstate.o debug.o wol.o features.o privflags.o rings.o
\
>  		   channels.o coalesce.o pause.o eee.o tsinfo.o cabletest.o
\
> -		   tunnels.o
> +		   tunnels.o eeprom.o
> diff --git a/net/ethtool/eeprom.c b/net/ethtool/eeprom.c new file mode
> 100644 index 000000000000..2618a55b9a40
> --- /dev/null
> +++ b/net/ethtool/eeprom.c
> @@ -0,0 +1,157 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +
> +#include <linux/ethtool.h>
> +#include "netlink.h"
> +#include "common.h"
> +
> +struct eeprom_data_req_info {
> +	struct ethnl_req_info	base;
> +	u32			offset;
> +	u32			length;
> +	u32			page;
> +	u32			bank;
> +	u32			i2c_address;
> +};
> +
> +struct eeprom_data_reply_data {
> +	struct ethnl_reply_data base;
> +	u32			length;
> +	u32			i2c_address;
> +	u8			*data;
> +};
> +
> +#define EEPROM_DATA_REQINFO(__req_base) \
> +	container_of(__req_base, struct eeprom_data_req_info, base)
> +
> +#define EEPROM_DATA_REPDATA(__reply_base) \
> +	container_of(__reply_base, struct eeprom_data_reply_data, base)
> +
> +static int eeprom_data_prepare_data(const struct ethnl_req_info
> *req_base,
> +				    struct ethnl_reply_data *reply_base,
> +				    struct genl_info *info)
> +{
> +	struct eeprom_data_reply_data *reply =
> EEPROM_DATA_REPDATA(reply_base);
> +	struct eeprom_data_req_info *request =
> EEPROM_DATA_REQINFO(req_base);
> +	struct ethtool_eeprom_data page_data = {0};
> +	struct net_device *dev = reply_base->dev;
> +	int err;
> +
> +	if (!dev->ethtool_ops->get_module_eeprom_data_by_page)
> +		return -EOPNOTSUPP;
> +
> +	page_data.offset = request->offset;
> +	page_data.length = request->length;
> +	page_data.i2c_address = request->i2c_address;
> +	page_data.page = request->page;
> +	page_data.bank = request->bank;
> +	page_data.data = kmalloc(page_data.length, GFP_KERNEL);
> +	if (!page_data.data)
> +		return -ENOMEM;
> +	err = ethnl_ops_begin(dev);
> +	if (err)
> +		goto err_free;
> +
> +	err = dev->ethtool_ops->get_module_eeprom_data_by_page(dev,
> &page_data,
> +
info->extack);
> +	if (err)
> +		goto err_ops;
> +
> +	reply->length = page_data.length;
> +	reply->i2c_address = page_data.i2c_address;
> +	reply->data = page_data.data;
> +
> +	ethnl_ops_complete(dev);

The two error paths below kfree(page_data.data).  Does someone else
free this memory when there is no error?

> +	return 0;
> +
> +err_ops:
> +	ethnl_ops_complete(dev);
> +err_free:
> +	kfree(page_data.data);
> +	return err;
> +}
> +
> +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);
> +
> +	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_u32(tb[ETHTOOL_A_EEPROM_DATA_I2C_ADDRESS]);
> +	if (request->i2c_address > ETH_MODULE_MAX_I2C_ADDRESS)
> +		return -EINVAL;

I would be much more restrictive, with one flexibility...

        if (request->i2c_address == 0xA0) request->i2c_address = 0x50;
        if (request->i2c_address == 0xA2) request->i2c_address = 0x51;
        if (request->i2c_address < 0x50) || (request->i2c_address > 0x51)
                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 (request->length > ETH_MODULE_EEPROM_MAX_LEN)
> +		return -EINVAL;	

This is really problematic as there are MANY different max values, within
the specs, for the various EEPROMs being generically supported here.
I would leave it to the drivers to handle out-of-range requests.  If you
really want to check, you need to know which spec the module supports,
whether it supports pages, and whether it supports banks.  I have not
found a register that actually reports the number of supported pages
that an eeprom supports.  The specs should have included that :-(.

> +	if (tb[ETHTOOL_A_EEPROM_DATA_PAGE] &&
> +	    request->offset + request->length >
> ETH_MODULE_EEPROM_PAGE_LEN)
> +		return -EINVAL;

Why does this stanza depend on DATA_PAGE?  In this new data 
structure, no requests can cross the 256 byte page boundary.

I suggest, rather then -EINVAL, you should reduce the length to reach
the end of the page:

        if (request->offset + request->length) > ETH_MODULE_EEPROM_PAGE_LEN)
                request->length = ETH_MODULE_EEPROM_PAGE_LEN - 
                                                      request->offset.

Note that this matches the choice you made to truncate rather than
error out in fallback_set_parms().

> +
> +	if (tb[ETHTOOL_A_EEPROM_DATA_PAGE])
> +		request->page =
> nla_get_u32(tb[ETHTOOL_A_EEPROM_DATA_PAGE]);
> +	if (tb[ETHTOOL_A_EEPROM_DATA_BANK])
> +		request->bank =
> nla_get_u32(tb[ETHTOOL_A_EEPROM_DATA_BANK]);

Other checks:

Page and bank have to be between 0 and 255 (inclusive), they
go into an 8 bit register in the eeprom.

Offset and length can't be negative.

> +
> +	return 0;
> +}
> +
> +static int eeprom_data_reply_size(const struct ethnl_req_info *req_base,
> +				  const struct ethnl_reply_data *reply_base)
{
> +	const struct eeprom_data_req_info *request =
> +EEPROM_DATA_REQINFO(req_base);
> +
> +	return nla_total_size(sizeof(u32)) + /* _EEPROM_DATA_LENGTH */
> +	       nla_total_size(sizeof(u32)) + /* _EEPROM_DATA_I2C_ADDRESS
> */
> +	       nla_total_size(sizeof(u8) * request->length); /* _EEPROM_DATA
> +*/ }
> +
> +static int eeprom_data_fill_reply(struct sk_buff *skb,
> +				  const struct ethnl_req_info *req_base,
> +				  const struct ethnl_reply_data *reply_base)
{
> +	struct eeprom_data_reply_data *reply =
> +EEPROM_DATA_REPDATA(reply_base);
> +
> +	if (nla_put_u32(skb, ETHTOOL_A_EEPROM_DATA_LENGTH, reply-
> >length) ||
> +	    nla_put_u32(skb, ETHTOOL_A_EEPROM_DATA_I2C_ADDRESS,
> reply->i2c_address) ||
> +	    nla_put(skb, ETHTOOL_A_EEPROM_DATA, reply->length, reply-
> >data))
> +		return -EMSGSIZE;
> +
> +	return 0;
> +}
> +
> +static void eeprom_data_cleanup_data(struct ethnl_reply_data
> +*reply_base) {
> +	struct eeprom_data_reply_data *reply =
> +EEPROM_DATA_REPDATA(reply_base);
> +
> +	kfree(reply->data);
> +}
> +
> +const struct ethnl_request_ops ethnl_eeprom_data_request_ops = {
> +	.request_cmd		= ETHTOOL_MSG_EEPROM_DATA_GET,
> +	.reply_cmd		=
> ETHTOOL_MSG_EEPROM_DATA_GET_REPLY,
> +	.hdr_attr		= ETHTOOL_A_EEPROM_DATA_HEADER,
> +	.req_info_size		= sizeof(struct eeprom_data_req_info),
> +	.reply_data_size	= sizeof(struct eeprom_data_reply_data),
> +
> +	.parse_request		= eeprom_data_parse_request,
> +	.prepare_data		= eeprom_data_prepare_data,
> +	.reply_size		= eeprom_data_reply_size,
> +	.fill_reply		= eeprom_data_fill_reply,
> +	.cleanup_data		= eeprom_data_cleanup_data,
> +};
> +
> +const struct nla_policy ethnl_eeprom_data_get_policy[] = {
> +	[ETHTOOL_A_EEPROM_DATA_HEADER]		=
> NLA_POLICY_NESTED(ethnl_header_policy),
> +	[ETHTOOL_A_EEPROM_DATA_OFFSET]		= { .type =
> NLA_U32 },
> +	[ETHTOOL_A_EEPROM_DATA_LENGTH]		= { .type =
> NLA_U32 },
> +	[ETHTOOL_A_EEPROM_DATA_PAGE]		= { .type = NLA_U32 },
> +	[ETHTOOL_A_EEPROM_DATA_BANK]		= { .type = NLA_U32 },
> +	[ETHTOOL_A_EEPROM_DATA_I2C_ADDRESS]	= { .type = NLA_U32 },
> +	[ETHTOOL_A_EEPROM_DATA]			= { .type =
> NLA_BINARY },
> +};
> +
> diff --git a/net/ethtool/netlink.c b/net/ethtool/netlink.c index
> 50d3c8896f91..ff2528bee192 100644
> --- a/net/ethtool/netlink.c
> +++ b/net/ethtool/netlink.c
> @@ -245,6 +245,7 @@
> ethnl_default_requests[__ETHTOOL_MSG_USER_CNT] = {
>  	[ETHTOOL_MSG_PAUSE_GET]		=
> &ethnl_pause_request_ops,
>  	[ETHTOOL_MSG_EEE_GET]		= &ethnl_eee_request_ops,
>  	[ETHTOOL_MSG_TSINFO_GET]	= &ethnl_tsinfo_request_ops,
> +	[ETHTOOL_MSG_EEPROM_DATA_GET]	=
> &ethnl_eeprom_data_request_ops,
>  };
> 
>  static struct ethnl_dump_ctx *ethnl_dump_context(struct netlink_callback
> *cb) @@ -912,6 +913,15 @@ static const struct genl_ops ethtool_genl_ops[]
> = {
>  		.policy = ethnl_tunnel_info_get_policy,
>  		.maxattr = ARRAY_SIZE(ethnl_tunnel_info_get_policy) - 1,
>  	},
> +	{
> +		.cmd	= ETHTOOL_MSG_EEPROM_DATA_GET,
> +		.doit	= ethnl_default_doit,
> +		.start	= ethnl_default_start,
> +		.dumpit	= ethnl_default_dumpit,
> +		.done	= ethnl_default_done,
> +		.policy = ethnl_eeprom_data_get_policy,
> +		.maxattr = ARRAY_SIZE(ethnl_eeprom_data_get_policy) - 1,
> +	},
>  };
> 
>  static const struct genl_multicast_group ethtool_nl_mcgrps[] = { diff
--git
> a/net/ethtool/netlink.h b/net/ethtool/netlink.h index
> 6eabd58d81bf..60954c7b4dfe 100644
> --- a/net/ethtool/netlink.h
> +++ b/net/ethtool/netlink.h
> @@ -344,6 +344,7 @@ extern const struct ethnl_request_ops
> ethnl_coalesce_request_ops;  extern const struct ethnl_request_ops
> ethnl_pause_request_ops;  extern const struct ethnl_request_ops
> ethnl_eee_request_ops;  extern const struct ethnl_request_ops
> ethnl_tsinfo_request_ops;
> +extern const struct ethnl_request_ops ethnl_eeprom_data_request_ops;
> 
>  extern const struct nla_policy
> ethnl_header_policy[ETHTOOL_A_HEADER_FLAGS + 1];  extern const struct
> nla_policy ethnl_header_policy_stats[ETHTOOL_A_HEADER_FLAGS + 1]; @@
> -375,6 +376,7 @@ extern const struct nla_policy
> ethnl_tsinfo_get_policy[ETHTOOL_A_TSINFO_HEADER +  extern const struct
> nla_policy ethnl_cable_test_act_policy[ETHTOOL_A_CABLE_TEST_HEADER +
> 1];  extern const struct nla_policy
> ethnl_cable_test_tdr_act_policy[ETHTOOL_A_CABLE_TEST_TDR_CFG + 1];
> extern const struct nla_policy
> ethnl_tunnel_info_get_policy[ETHTOOL_A_TUNNEL_INFO_HEADER + 1];
> +extern const struct nla_policy
> +ethnl_eeprom_data_get_policy[ETHTOOL_A_EEPROM_DATA + 1];
> 
>  int ethnl_set_linkinfo(struct sk_buff *skb, struct genl_info *info);  int
> ethnl_set_linkmodes(struct sk_buff *skb, struct genl_info *info);
> --
> 2.18.2

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