Re: [PATCH V2 1/2] nvme: add generic helper to store secret

[Sagi Grimberg <sagi@grimberg.me>]

On 6/5/23 09:51, Chaitanya Kulkarni wrote:
> Refactor code to avoid duplication and improve maintainability:
> 
> Consolidate the shared code between the functions
> nvme_ctrl_dhchap_secret_store() and
> nvme_ctrl_dhchap_ctrl_secret_store(). This duplication not only
> increases the likelihood of bugs but also requires additional effort for
> maintenance and testing.
> 
> Introduce a new generic helper function called
> nvme_dhchap_secret_store_common() to handle the storage of the
> dhchap secret. Update nvme_ctrl_dhchap_secret_store() and
> nvme_ctrl_dhchap_ctrl_secret_store() to use newly introduced helper.
> 
> Signed-off-by: Chaitanya Kulkarni <kch@nvidia.com>
> ---
>   drivers/nvme/host/sysfs.c | 96 ++++++++++++++++-----------------------
>   1 file changed, 39 insertions(+), 57 deletions(-)
> 
> diff --git a/drivers/nvme/host/sysfs.c b/drivers/nvme/host/sysfs.c
> index 796e1d373b7c..98becb7a7453 100644
> --- a/drivers/nvme/host/sysfs.c
> +++ b/drivers/nvme/host/sysfs.c
> @@ -418,43 +418,53 @@ static ssize_t nvme_ctrl_dhchap_secret_show(struct device *dev,
>   	return sysfs_emit(buf, "%s\n", opts->dhchap_secret);
>   }
>   
> -static ssize_t nvme_ctrl_dhchap_secret_store(struct device *dev,
> -		struct device_attribute *attr, const char *buf, size_t count)
> +static ssize_t nvme_dhchap_secret_store_common(struct nvme_ctrl *ctrl,
> +		const char *buf, size_t count, bool ctrl_secret)
>   {
> -	struct nvme_ctrl *ctrl = dev_get_drvdata(dev);
> -	struct nvmf_ctrl_options *opts = ctrl->opts;
> -	char *dhchap_secret;
> +	struct nvme_dhchap_key **orig_key;
> +	char **dhchap_secret;
> +	char *new_dhchap_secret;
> +
> +	if (ctrl_secret) {
> +		if (!ctrl->opts->dhchap_ctrl_secret)
> +			return -EINVAL;
> +		dhchap_secret = &ctrl->opts->dhchap_ctrl_secret;
> +		orig_key = &ctrl->ctrl_key;
> +	} else {
> +		if (!ctrl->opts->dhchap_secret)
> +			return -EINVAL;
> +		dhchap_secret = &ctrl->opts->dhchap_secret;
> +		orig_key = &ctrl->host_key;
> +	}
>   
> -	if (!ctrl->opts->dhchap_secret)
> -		return -EINVAL;
>   	if (count < 7)
>   		return -EINVAL;
>   	if (memcmp(buf, "DHHC-1:", 7))
>   		return -EINVAL;
>   
> -	dhchap_secret = kzalloc(count + 1, GFP_KERNEL);
> -	if (!dhchap_secret)
> +	new_dhchap_secret = kzalloc(count + 1, GFP_KERNEL);
> +	if (!new_dhchap_secret)
>   		return -ENOMEM;
> -	memcpy(dhchap_secret, buf, count);
> +	memcpy(new_dhchap_secret, buf, count);
>   	nvme_auth_stop(ctrl);
> -	if (strcmp(dhchap_secret, opts->dhchap_secret)) {
> -		struct nvme_dhchap_key *key, *host_key;
> +	if (strcmp(new_dhchap_secret, *dhchap_secret)) {
> +		struct nvme_dhchap_key *new_key, *prev_key;
>   		int ret;
>   
> -		ret = nvme_auth_generate_key(dhchap_secret, &key);
> +		ret = nvme_auth_generate_key(new_dhchap_secret, &new_key);
>   		if (ret) {
> -			kfree(dhchap_secret);
> +			kfree(new_dhchap_secret);
>   			return ret;
>   		}
> -		kfree(opts->dhchap_secret);
> -		opts->dhchap_secret = dhchap_secret;
> -		host_key = ctrl->host_key;
> +		kfree(*dhchap_secret);
> +		*dhchap_secret = new_dhchap_secret;
> +		prev_key = *orig_key;
>   		mutex_lock(&ctrl->dhchap_auth_mutex);
> -		ctrl->host_key = key;
> +		*orig_key = new_key;
>   		mutex_unlock(&ctrl->dhchap_auth_mutex);
> -		nvme_auth_free_key(host_key);
> +		nvme_auth_free_key(prev_key);
>   	} else
> -		kfree(dhchap_secret);
> +		kfree(new_dhchap_secret);
>   	/* Start re-authentication */
>   	dev_info(ctrl->device, "re-authenticating controller\n");
>   	queue_work(nvme_wq, &ctrl->dhchap_auth_work);
> @@ -462,6 +472,14 @@ static ssize_t nvme_ctrl_dhchap_secret_store(struct device *dev,
>   	return count;
>   }
>   
> +static ssize_t nvme_ctrl_dhchap_secret_store(struct device *dev,
> +		struct device_attribute *attr, const char *buf, size_t count)
> +{
> +	struct nvme_ctrl *ctrl = dev_get_drvdata(dev);
> +
> +	return nvme_dhchap_secret_store_common(ctrl, buf, count, false);
> +}
> +
>   static DEVICE_ATTR(dhchap_secret, S_IRUGO | S_IWUSR,
>   	nvme_ctrl_dhchap_secret_show, nvme_ctrl_dhchap_secret_store);
>   
> @@ -480,44 +498,8 @@ static ssize_t nvme_ctrl_dhchap_ctrl_secret_store(struct device *dev,
>   		struct device_attribute *attr, const char *buf, size_t count)
>   {
>   	struct nvme_ctrl *ctrl = dev_get_drvdata(dev);
> -	struct nvmf_ctrl_options *opts = ctrl->opts;
> -	char *dhchap_secret;
>   
> -	if (!ctrl->opts->dhchap_ctrl_secret)
> -		return -EINVAL;
> -	if (count < 7)
> -		return -EINVAL;
> -	if (memcmp(buf, "DHHC-1:", 7))
> -		return -EINVAL;
> -
> -	dhchap_secret = kzalloc(count + 1, GFP_KERNEL);
> -	if (!dhchap_secret)
> -		return -ENOMEM;
> -	memcpy(dhchap_secret, buf, count);
> -	nvme_auth_stop(ctrl);
> -	if (strcmp(dhchap_secret, opts->dhchap_ctrl_secret)) {
> -		struct nvme_dhchap_key *key, *ctrl_key;
> -		int ret;
> -
> -		ret = nvme_auth_generate_key(dhchap_secret, &key);
> -		if (ret) {
> -			kfree(dhchap_secret);
> -			return ret;
> -		}
> -		kfree(opts->dhchap_ctrl_secret);
> -		opts->dhchap_ctrl_secret = dhchap_secret;
> -		ctrl_key = ctrl->ctrl_key;
> -		mutex_lock(&ctrl->dhchap_auth_mutex);
> -		ctrl->ctrl_key = key;
> -		mutex_unlock(&ctrl->dhchap_auth_mutex);
> -		nvme_auth_free_key(ctrl_key);
> -	} else
> -		kfree(dhchap_secret);
> -	/* Start re-authentication */
> -	dev_info(ctrl->device, "re-authenticating controller\n");
> -	queue_work(nvme_wq, &ctrl->dhchap_auth_work);
> -
> -	return count;
> +	return nvme_dhchap_secret_store_common(ctrl, buf, count, false);

Both call with ctrl_secret=false?

I think it conveys the point that this is confusing...