On Tue, Sep 19, 2017 at 12:24:32PM +0200, Paolo Bonzini wrote:
> Introduce a privileged helper to run persistent reservation commands.
> This lets virtual machines send persistent reservations without using
> CAP_SYS_RAWIO or out-of-tree patches. The helper uses Unix permissions
> and SCM_RIGHTS to restrict access to processes that can access its socket
> and prove that they have an open file descriptor for a raw SCSI device.
>
> The next patch will also correct the usage of persistent reservations
> with multipath devices.
>
> It would also be possible to support for Linux's IOC_PR_* ioctls in
> the future, to support NVMe devices. For now, however, only SCSI is
> supported.
>
> Signed-off-by: Paolo Bonzini <[email protected]>
> ---
> +
> +#define PR_HELPER_CDB_SIZE 16
> +#define PR_HELPER_SENSE_SIZE 96
> +#define PR_HELPER_DATA_SIZE 8192
> +
> +typedef struct PRHelperResponse {
> + int32_t result;
> + int32_t sz;
> + uint8_t sense[PR_HELPER_SENSE_SIZE];
> +} PRHelperResponse;
Should we annotate this with 'packed' to ensure its immune to compiler
padding ?
> +typedef struct PRHelperRequest {
> + int fd;
> + size_t sz;
> + uint8_t cdb[PR_HELPER_CDB_SIZE];
> +} PRHelperRequest;
Same q here ?
> +static int coroutine_fn prh_write_response(PRHelperClient *client,
> + PRHelperRequest *req,
> + PRHelperResponse *resp, Error
> **errp)
> +{
> + ssize_t r;
Can just be int
> + size_t sz;
> +
> + if (req->cdb[0] == PERSISTENT_RESERVE_IN && resp->result == GOOD) {
> + assert(resp->sz <= req->sz && resp->sz <= sizeof(client->data));
> + } else {
> + assert(resp->sz == 0);
> + }
> +
> + sz = resp->sz;
> +
> + resp->result = cpu_to_be32(resp->result);
> + resp->sz = cpu_to_be32(resp->sz);
> + r = qio_channel_write_all(QIO_CHANNEL(client->ioc),
> + (char *) resp, sizeof(*resp), errp);
> + if (r < 0) {
> + return r;
> + }
> +
> + r = qio_channel_write_all(QIO_CHANNEL(client->ioc),
> + (char *) client->data,
> + sz, errp);
> + return r < 0 ? r : 0;
Just return 'r' directly, its only ever -1 or 0
Regards,
Daniel
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