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Date:   Fri, 8 Feb 2019 22:58:24 +0000
From:   "Derrick, Jonathan" <jonathan.derrick@...el.com>
To:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "zub@...ux.fjfi.cvut.cz" <zub@...ux.fjfi.cvut.cz>,
        "linux-block@...r.kernel.org" <linux-block@...r.kernel.org>,
        "sbauer@...donthack.me" <sbauer@...donthack.me>,
        "axboe@...nel.dk" <axboe@...nel.dk>
CC:     "jonas.rabenstein@...dium.uni-erlangen.de" 
        <jonas.rabenstein@...dium.uni-erlangen.de>
Subject: Re: [PATCH v4 11/16] block: sed-opal: ioctl for writing to shadow
 mbr

On Fri, 2019-02-01 at 21:50 +0100, David Kozub wrote:
> From: Jonas Rabenstein <jonas.rabenstein@...dium.uni-erlangen.de>
> 
> Allow modification of the shadow mbr. If the shadow mbr is not marked as
> done, this data will be presented read only as the device content. Only
> after marking the shadow mbr as done and unlocking a locking range the
> actual content is accessible.
> 
> Co-authored-by: David Kozub <zub@...ux.fjfi.cvut.cz>
> Signed-off-by: Jonas Rabenstein <jonas.rabenstein@...dium.uni-erlangen.de>
> Signed-off-by: David Kozub <zub@...ux.fjfi.cvut.cz>
> Reviewed-by: Scott Bauer <sbauer@...donthack.me>
> ---
>  block/sed-opal.c              | 89 ++++++++++++++++++++++++++++++++++-
>  include/linux/sed-opal.h      |  1 +
>  include/uapi/linux/sed-opal.h |  8 ++++
>  3 files changed, 97 insertions(+), 1 deletion(-)
> 
> diff --git a/block/sed-opal.c b/block/sed-opal.c
> index e03838cfd31b..88c84906ce98 100644
> --- a/block/sed-opal.c
> +++ b/block/sed-opal.c
> @@ -34,6 +34,9 @@
>  #define IO_BUFFER_LENGTH 2048
>  #define MAX_TOKS 64
>  
> +/* Number of bytes needed by cmd_finalize. */
> +#define CMD_FINALIZE_BYTES_NEEDED 7
> +
>  struct opal_step {
>  	int (*fn)(struct opal_dev *dev, void *data);
>  	void *data;
> @@ -668,7 +671,11 @@ static int cmd_finalize(struct opal_dev *cmd, u32 hsn, u32 tsn)
>  	struct opal_header *hdr;
>  	int err = 0;
>  
> -	/* close the parameter list opened from cmd_start */
> +	/*
> +	 * Close the parameter list opened from cmd_start.
> +	 * The number of bytes added must be equal to
> +	 * CMD_FINALIZE_BYTES_NEEDED.
> +	 */
>  	add_token_u8(&err, cmd, OPAL_ENDLIST);
>  
>  	add_token_u8(&err, cmd, OPAL_ENDOFDATA);
> @@ -1500,6 +1507,58 @@ static int set_mbr_enable_disable(struct opal_dev *dev, void *data)
>  	return finalize_and_send(dev, parse_and_check_status);
>  }
>  
> +static int write_shadow_mbr(struct opal_dev *dev, void *data)
> +{
> +	struct opal_shadow_mbr *shadow = data;
> +	const u8 __user *src;
> +	u8 *dst;
> +	size_t off = 0;
> +	u64 len;
> +	int err = 0;
> +
> +	/* do the actual transmission(s) */
> +	src = (u8 *) shadow->data;
> +	while (off < shadow->size) {
> +		err = cmd_start(dev, opaluid[OPAL_MBR], opalmethod[OPAL_SET]);
> +		add_token_u8(&err, dev, OPAL_STARTNAME);
> +		add_token_u8(&err, dev, OPAL_WHERE);
> +		add_token_u64(&err, dev, shadow->offset + off);
> +		add_token_u8(&err, dev, OPAL_ENDNAME);
> +
> +		add_token_u8(&err, dev, OPAL_STARTNAME);
> +		add_token_u8(&err, dev, OPAL_VALUES);
> +
> +		/*
> +		 * The bytestring header is either 1 or 2 bytes, so assume 2.
> +		 * There also needs to be enough space to accommodate the
> +		 * trailing OPAL_ENDNAME (1 byte) and tokens added by
> +		 * cmd_finalize.
> +		 */
> +		len = min(remaining_size(dev) - (2+1+CMD_FINALIZE_BYTES_NEEDED),
> +			  (size_t)(shadow->size - off));
> +		pr_debug("MBR: write bytes %zu+%llu/%llu\n",
> +			 off, len, shadow->size);
> +
> +		dst = add_bytestring_header(&err, dev, len);
> +		if (!dst)
> +			break;
> +		if (copy_from_user(dst, src + off, len))
> +			err = -EFAULT;
> +		dev->pos += len;
> +
> +		add_token_u8(&err, dev, OPAL_ENDNAME);
> +		if (err)
> +			break;
> +
> +		err = finalize_and_send(dev, parse_and_check_status);
> +		if (err)
> +			break;
> +
> +		off += len;
> +	}
> +	return err;
> +}
> +
>  static int generic_pw_cmd(u8 *key, size_t key_len, u8 *cpin_uid,
>  			  struct opal_dev *dev)
>  {
> @@ -2045,6 +2104,31 @@ static int opal_mbr_status(struct opal_dev *dev, struct opal_mbr_data *opal_mbr)
>  	return ret;
>  }
>  
> +static int opal_write_shadow_mbr(struct opal_dev *dev,
> +				 struct opal_shadow_mbr *info)
> +{
> +	const struct opal_step mbr_steps[] = {
> +		{ opal_discovery0, },
> +		{ start_admin1LSP_opal_session, &info->key },
> +		{ write_shadow_mbr, info },
> +		{ end_opal_session, },
> +		{ NULL, }
> +	};
> +	int ret;
> +
> +	if (info->size == 0)
> +		return 0;
> +
> +	if (!access_ok(info->data, info->size))
> +		return -EINVAL;
-EFAULT?

> +
> +	mutex_lock(&dev->dev_lock);
> +	setup_opal_dev(dev, mbr_steps);
> +	ret = next(dev);
> +	mutex_unlock(&dev->dev_lock);
> +	return ret;
> +}
> +
>  static int opal_save(struct opal_dev *dev, struct opal_lock_unlock *lk_unlk)
>  {
>  	struct opal_suspend_data *suspend;
> @@ -2378,6 +2462,9 @@ int sed_ioctl(struct opal_dev *dev, unsigned int cmd, void __user *arg)
>  	case IOC_OPAL_MBR_STATUS:
>  		ret = opal_mbr_status(dev, p);
>  		break;
> +	case IOC_OPAL_WRITE_SHADOW_MBR:
> +		ret = opal_write_shadow_mbr(dev, p);
> +		break;
>  	case IOC_OPAL_ERASE_LR:
>  		ret = opal_erase_locking_range(dev, p);
>  		break;
> diff --git a/include/linux/sed-opal.h b/include/linux/sed-opal.h
> index b38dc602cae3..cf08cdc13cbd 100644
> --- a/include/linux/sed-opal.h
> +++ b/include/linux/sed-opal.h
> @@ -47,6 +47,7 @@ static inline bool is_sed_ioctl(unsigned int cmd)
>  	case IOC_OPAL_ENABLE_DISABLE_MBR:
>  	case IOC_OPAL_ERASE_LR:
>  	case IOC_OPAL_SECURE_ERASE_LR:
> +	case IOC_OPAL_WRITE_SHADOW_MBR:
>  	case IOC_OPAL_MBR_STATUS:
>  		return true;
>  	}
> diff --git a/include/uapi/linux/sed-opal.h b/include/uapi/linux/sed-opal.h
> index 0cb9890cdc04..8e84307f66d4 100644
> --- a/include/uapi/linux/sed-opal.h
> +++ b/include/uapi/linux/sed-opal.h
> @@ -104,6 +104,13 @@ struct opal_mbr_data {
>  	__u8 __align[7];
>  };
>  
> +struct opal_shadow_mbr {
> +	struct opal_key key;
> +	const __u64 data;
> +	__u64 offset;
> +	__u64 size;
> +};
> +
>  #define IOC_OPAL_SAVE		    _IOW('p', 220, struct opal_lock_unlock)
>  #define IOC_OPAL_LOCK_UNLOCK	    _IOW('p', 221, struct opal_lock_unlock)
>  #define IOC_OPAL_TAKE_OWNERSHIP	    _IOW('p', 222, struct opal_key)
> @@ -117,5 +124,6 @@ struct opal_mbr_data {
>  #define IOC_OPAL_ERASE_LR           _IOW('p', 230, struct opal_session_info)
>  #define IOC_OPAL_SECURE_ERASE_LR    _IOW('p', 231, struct opal_session_info)
>  #define IOC_OPAL_MBR_STATUS         _IOW('p', 232, struct opal_mbr_data)
> +#define IOC_OPAL_WRITE_SHADOW_MBR   _IOW('p', 233, struct opal_shadow_mbr)
>  
>  #endif /* _UAPI_SED_OPAL_H */
Otherwise looks good

Reviewed-by: Jon Derrick <jonathan.derrick@...el.com>


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