stub_rx.c

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/*
 * Copyright (C) 2003-2008 Takahiro Hirofuchi
 *
 * This is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
 * USA.
 */

#include <asm/byteorder.h>
#include <linux/kthread.h>
#include <linux/usb.h>
#include <linux/usb/hcd.h>

#include "usbip_common.h"
#include "stub.h"

static int is_clear_halt_cmd(struct urb *urb)
{
    struct usb_ctrlrequest *req;

    req = (struct usb_ctrlrequest *) urb->setup_packet;

     return (req->bRequest == USB_REQ_CLEAR_FEATURE) &&
         (req->bRequestType == USB_RECIP_ENDPOINT) &&
         (req->wValue == USB_ENDPOINT_HALT);
}

static int is_set_interface_cmd(struct urb *urb)
{
    struct usb_ctrlrequest *req;

    req = (struct usb_ctrlrequest *) urb->setup_packet;

    return (req->bRequest == USB_REQ_SET_INTERFACE) &&
        (req->bRequestType == USB_RECIP_INTERFACE);
}

static int is_set_configuration_cmd(struct urb *urb)
{
    struct usb_ctrlrequest *req;

    req = (struct usb_ctrlrequest *) urb->setup_packet;

    return (req->bRequest == USB_REQ_SET_CONFIGURATION) &&
        (req->bRequestType == USB_RECIP_DEVICE);
}

static int is_reset_device_cmd(struct urb *urb)
{
    struct usb_ctrlrequest *req;
    __u16 value;
    __u16 index;

    req = (struct usb_ctrlrequest *) urb->setup_packet;
    value = le16_to_cpu(req->wValue);
    index = le16_to_cpu(req->wIndex);

    if ((req->bRequest == USB_REQ_SET_FEATURE) &&
        (req->bRequestType == USB_RT_PORT) &&
        (value == USB_PORT_FEAT_RESET)) {
        usbip_dbg_stub_rx("reset_device_cmd, port %u\n", index);
        return 1;
    } else
        return 0;
}

static int tweak_clear_halt_cmd(struct urb *urb)
{
    struct usb_ctrlrequest *req;
    int target_endp;
    int target_dir;
    int target_pipe;
    int ret;

    req = (struct usb_ctrlrequest *) urb->setup_packet;

    /*
     * The stalled endpoint is specified in the wIndex value. The endpoint
     * of the urb is the target of this clear_halt request (i.e., control
     * endpoint).
     */
    target_endp = le16_to_cpu(req->wIndex) & 0x000f;

    /* the stalled endpoint direction is IN or OUT?. USB_DIR_IN is 0x80.  */
    target_dir = le16_to_cpu(req->wIndex) & 0x0080;

    if (target_dir)
        target_pipe = usb_rcvctrlpipe(urb->dev, target_endp);
    else
        target_pipe = usb_sndctrlpipe(urb->dev, target_endp);

    ret = usb_clear_halt(urb->dev, target_pipe);
    if (ret < 0)
        dev_err(&urb->dev->dev, "usb_clear_halt error: devnum %d endp "
            "%d ret %d\n", urb->dev->devnum, target_endp, ret);
    else
        dev_info(&urb->dev->dev, "usb_clear_halt done: devnum %d endp "
             "%d\n", urb->dev->devnum, target_endp);

    return ret;
}

static int tweak_set_interface_cmd(struct urb *urb)
{
    struct usb_ctrlrequest *req;
    __u16 alternate;
    __u16 interface;
    int ret;

    req = (struct usb_ctrlrequest *) urb->setup_packet;
    alternate = le16_to_cpu(req->wValue);
    interface = le16_to_cpu(req->wIndex);

    usbip_dbg_stub_rx("set_interface: inf %u alt %u\n",
              interface, alternate);

    ret = usb_set_interface(urb->dev, interface, alternate);
    if (ret < 0)
        dev_err(&urb->dev->dev, "usb_set_interface error: inf %u alt "
            "%u ret %d\n", interface, alternate, ret);
    else
        dev_info(&urb->dev->dev, "usb_set_interface done: inf %u alt "
             "%u\n", interface, alternate);

    return ret;
}

static int tweak_set_configuration_cmd(struct urb *urb)
{
    struct usb_ctrlrequest *req;
    __u16 config;

    req = (struct usb_ctrlrequest *) urb->setup_packet;
    config = le16_to_cpu(req->wValue);

    /*
     * I have never seen a multi-config device. Very rare.
     * For most devices, this will be called to choose a default
     * configuration only once in an initialization phase.
     *
     * set_configuration may change a device configuration and its device
     * drivers will be unbound and assigned for a new device configuration.
     * This means this usbip driver will be also unbound when called, then
     * eventually reassigned to the device as far as driver matching
     * condition is kept.
     *
     * Unfortunately, an existing usbip connection will be dropped
     * due to this driver unbinding. So, skip here.
     * A user may need to set a special configuration value before
     * exporting the device.
     */
    dev_info(&urb->dev->dev, "usb_set_configuration %d to %s... skip!\n",
         config, dev_name(&urb->dev->dev));

    return 0;
    /* return usb_driver_set_configuration(urb->dev, config); */
}

static int tweak_reset_device_cmd(struct urb *urb)
{
    struct stub_priv *priv = (struct stub_priv *) urb->context;
    struct stub_device *sdev = priv->sdev;

    dev_info(&urb->dev->dev, "usb_queue_reset_device\n");

    /*
     * With the implementation of pre_reset and post_reset the driver no
     * longer unbinds. This allows the use of synchronous reset.
     */

    if (usb_lock_device_for_reset(sdev->udev, sdev->interface) < 0) {
        dev_err(&urb->dev->dev, "could not obtain lock to reset device\n");
        return 0;
    }
    usb_reset_device(sdev->udev);
    usb_unlock_device(sdev->udev);

    return 0;
}

/*
 * clear_halt, set_interface, and set_configuration require special tricks.
 */
static void tweak_special_requests(struct urb *urb)
{
    if (!urb || !urb->setup_packet)
        return;

    if (usb_pipetype(urb->pipe) != PIPE_CONTROL)
        return;

    if (is_clear_halt_cmd(urb))
        /* tweak clear_halt */
         tweak_clear_halt_cmd(urb);

    else if (is_set_interface_cmd(urb))
        /* tweak set_interface */
        tweak_set_interface_cmd(urb);

    else if (is_set_configuration_cmd(urb))
        /* tweak set_configuration */
        tweak_set_configuration_cmd(urb);

    else if (is_reset_device_cmd(urb))
        tweak_reset_device_cmd(urb);
    else
        usbip_dbg_stub_rx("no need to tweak\n");
}

/*
 * stub_recv_unlink() unlinks the URB by a call to usb_unlink_urb().
 * By unlinking the urb asynchronously, stub_rx can continuously
 * process coming urbs.  Even if the urb is unlinked, its completion
 * handler will be called and stub_tx will send a return pdu.
 *
 * See also comments about unlinking strategy in vhci_hcd.c.
 */
static int stub_recv_cmd_unlink(struct stub_device *sdev,
                struct usbip_header *pdu)
{
    unsigned long flags;

    struct stub_priv *priv;

    spin_lock_irqsave(&sdev->priv_lock, flags);

    list_for_each_entry(priv, &sdev->priv_init, list) {
        if (priv->seqnum == pdu->u.cmd_unlink.seqnum) {
            int ret;

            dev_info(&priv->urb->dev->dev, "unlink urb %p\n",
                 priv->urb);

            /*
             * This matched urb is not completed yet (i.e., be in
             * flight in usb hcd hardware/driver). Now we are
             * cancelling it. The unlinking flag means that we are
             * now not going to return the normal result pdu of a
             * submission request, but going to return a result pdu
             * of the unlink request.
             */
            priv->unlinking = 1;

            /*
             * In the case that unlinking flag is on, prev->seqnum
             * is changed from the seqnum of the cancelling urb to
             * the seqnum of the unlink request. This will be used
             * to make the result pdu of the unlink request.
             */
            priv->seqnum = pdu->base.seqnum;

            spin_unlock_irqrestore(&sdev->priv_lock, flags);

            /*
             * usb_unlink_urb() is now out of spinlocking to avoid
             * spinlock recursion since stub_complete() is
             * sometimes called in this context but not in the
             * interrupt context.  If stub_complete() is executed
             * before we call usb_unlink_urb(), usb_unlink_urb()
             * will return an error value. In this case, stub_tx
             * will return the result pdu of this unlink request
             * though submission is completed and actual unlinking
             * is not executed. OK?
             */
            /* In the above case, urb->status is not -ECONNRESET,
             * so a driver in a client host will know the failure
             * of the unlink request ?
             */
            ret = usb_unlink_urb(priv->urb);
            if (ret != -EINPROGRESS)
                dev_err(&priv->urb->dev->dev,
                    "failed to unlink a urb %p, ret %d\n",
                    priv->urb, ret);
            return 0;
        }
    }

    usbip_dbg_stub_rx("seqnum %d is not pending\n",
              pdu->u.cmd_unlink.seqnum);

    /*
     * The urb of the unlink target is not found in priv_init queue. It was
     * already completed and its results is/was going to be sent by a
     * CMD_RET pdu. In this case, usb_unlink_urb() is not needed. We only
     * return the completeness of this unlink request to vhci_hcd.
     */
    stub_enqueue_ret_unlink(sdev, pdu->base.seqnum, 0);

    spin_unlock_irqrestore(&sdev->priv_lock, flags);

    return 0;
}

static int valid_request(struct stub_device *sdev, struct usbip_header *pdu)
{
    struct usbip_device *ud = &sdev->ud;
    int valid = 0;

    if (pdu->base.devid == sdev->devid) {
        spin_lock(&ud->lock);
        if (ud->status == SDEV_ST_USED) {
            /* A request is valid. */
            valid = 1;
        }
        spin_unlock(&ud->lock);
    }

    return valid;
}

static struct stub_priv *stub_priv_alloc(struct stub_device *sdev,
                     struct usbip_header *pdu)
{
    struct stub_priv *priv;
    struct usbip_device *ud = &sdev->ud;
    unsigned long flags;

    spin_lock_irqsave(&sdev->priv_lock, flags);

    priv = kmem_cache_zalloc(stub_priv_cache, GFP_ATOMIC);
    if (!priv) {
        dev_err(&sdev->interface->dev, "alloc stub_priv\n");
        spin_unlock_irqrestore(&sdev->priv_lock, flags);
        usbip_event_add(ud, SDEV_EVENT_ERROR_MALLOC);
        return NULL;
    }

    priv->seqnum = pdu->base.seqnum;
    priv->sdev = sdev;

    /*
     * After a stub_priv is linked to a list_head,
     * our error handler can free allocated data.
     */
    list_add_tail(&priv->list, &sdev->priv_init);

    spin_unlock_irqrestore(&sdev->priv_lock, flags);

    return priv;
}

static int get_pipe(struct stub_device *sdev, int epnum, int dir)
{
    struct usb_device *udev = sdev->udev;
    struct usb_host_endpoint *ep;
    struct usb_endpoint_descriptor *epd = NULL;

    if (dir == USBIP_DIR_IN)
        ep = udev->ep_in[epnum & 0x7f];
    else
        ep = udev->ep_out[epnum & 0x7f];
    if (!ep) {
        dev_err(&sdev->interface->dev, "no such endpoint?, %d\n",
            epnum);
        BUG();
    }

    epd = &ep->desc;
    if (usb_endpoint_xfer_control(epd)) {
        if (dir == USBIP_DIR_OUT)
            return usb_sndctrlpipe(udev, epnum);
        else
            return usb_rcvctrlpipe(udev, epnum);
    }

    if (usb_endpoint_xfer_bulk(epd)) {
        if (dir == USBIP_DIR_OUT)
            return usb_sndbulkpipe(udev, epnum);
        else
            return usb_rcvbulkpipe(udev, epnum);
    }

    if (usb_endpoint_xfer_int(epd)) {
        if (dir == USBIP_DIR_OUT)
            return usb_sndintpipe(udev, epnum);
        else
            return usb_rcvintpipe(udev, epnum);
    }

    if (usb_endpoint_xfer_isoc(epd)) {
        if (dir == USBIP_DIR_OUT)
            return usb_sndisocpipe(udev, epnum);
        else
            return usb_rcvisocpipe(udev, epnum);
    }

    /* NOT REACHED */
    dev_err(&sdev->interface->dev, "get pipe, epnum %d\n", epnum);
    return 0;
}

static void masking_bogus_flags(struct urb *urb)
{
    int             xfertype;
    struct usb_device       *dev;
    struct usb_host_endpoint    *ep;
    int             is_out;
    unsigned int    allowed;

    if (!urb || urb->hcpriv || !urb->complete)
        return;
    dev = urb->dev;
    if ((!dev) || (dev->state < USB_STATE_UNAUTHENTICATED))
        return;

    ep = (usb_pipein(urb->pipe) ? dev->ep_in : dev->ep_out)
        [usb_pipeendpoint(urb->pipe)];
    if (!ep)
        return;

    xfertype = usb_endpoint_type(&ep->desc);
    if (xfertype == USB_ENDPOINT_XFER_CONTROL) {
        struct usb_ctrlrequest *setup =
            (struct usb_ctrlrequest *) urb->setup_packet;

        if (!setup)
            return;
        is_out = !(setup->bRequestType & USB_DIR_IN) ||
            !setup->wLength;
    } else {
        is_out = usb_endpoint_dir_out(&ep->desc);
    }

    /* enforce simple/standard policy */
    allowed = (URB_NO_TRANSFER_DMA_MAP | URB_NO_INTERRUPT |
           URB_DIR_MASK | URB_FREE_BUFFER);
    switch (xfertype) {
    case USB_ENDPOINT_XFER_BULK:
        if (is_out)
            allowed |= URB_ZERO_PACKET;
        /* FALLTHROUGH */
    case USB_ENDPOINT_XFER_CONTROL:
        allowed |= URB_NO_FSBR; /* only affects UHCI */
        /* FALLTHROUGH */
    default:            /* all non-iso endpoints */
        if (!is_out)
            allowed |= URB_SHORT_NOT_OK;
        break;
    case USB_ENDPOINT_XFER_ISOC:
        allowed |= URB_ISO_ASAP;
        break;
    }
    urb->transfer_flags &= allowed;
}

static void stub_recv_cmd_submit(struct stub_device *sdev,
                 struct usbip_header *pdu)
{
    int ret;
    struct stub_priv *priv;
    struct usbip_device *ud = &sdev->ud;
    struct usb_device *udev = sdev->udev;
    int pipe = get_pipe(sdev, pdu->base.ep, pdu->base.direction);

    priv = stub_priv_alloc(sdev, pdu);
    if (!priv)
        return;

    /* setup a urb */
    if (usb_pipeisoc(pipe))
        priv->urb = usb_alloc_urb(pdu->u.cmd_submit.number_of_packets,
                      GFP_KERNEL);
    else
        priv->urb = usb_alloc_urb(0, GFP_KERNEL);

    if (!priv->urb) {
        dev_err(&sdev->interface->dev, "malloc urb\n");
        usbip_event_add(ud, SDEV_EVENT_ERROR_MALLOC);
        return;
    }

    /* set priv->urb->transfer_buffer */
    if (pdu->u.cmd_submit.transfer_buffer_length > 0) {
        priv->urb->transfer_buffer =
            kzalloc(pdu->u.cmd_submit.transfer_buffer_length,
                GFP_KERNEL);
        if (!priv->urb->transfer_buffer) {
            dev_err(&sdev->interface->dev, "malloc x_buff\n");
            usbip_event_add(ud, SDEV_EVENT_ERROR_MALLOC);
            return;
        }
    }

    /* set priv->urb->setup_packet */
    priv->urb->setup_packet = kmemdup(&pdu->u.cmd_submit.setup, 8,
                      GFP_KERNEL);
    if (!priv->urb->setup_packet) {
        dev_err(&sdev->interface->dev, "allocate setup_packet\n");
        usbip_event_add(ud, SDEV_EVENT_ERROR_MALLOC);
        return;
    }

    /* set other members from the base header of pdu */
    priv->urb->context                = (void *) priv;
    priv->urb->dev                    = udev;
    priv->urb->pipe                   = pipe;
    priv->urb->complete               = stub_complete;

    usbip_pack_pdu(pdu, priv->urb, USBIP_CMD_SUBMIT, 0);


    if (usbip_recv_xbuff(ud, priv->urb) < 0)
        return;

    if (usbip_recv_iso(ud, priv->urb) < 0)
        return;

    /* no need to submit an intercepted request, but harmless? */
    tweak_special_requests(priv->urb);

    masking_bogus_flags(priv->urb);
    /* urb is now ready to submit */
    ret = usb_submit_urb(priv->urb, GFP_KERNEL);

    if (ret == 0)
        usbip_dbg_stub_rx("submit urb ok, seqnum %u\n",
                  pdu->base.seqnum);
    else {
        dev_err(&sdev->interface->dev, "submit_urb error, %d\n", ret);
        usbip_dump_header(pdu);
        usbip_dump_urb(priv->urb);

        /*
         * Pessimistic.
         * This connection will be discarded.
         */
        usbip_event_add(ud, SDEV_EVENT_ERROR_SUBMIT);
    }

    usbip_dbg_stub_rx("Leave\n");
    return;
}

/* recv a pdu */
static void stub_rx_pdu(struct usbip_device *ud)
{
    int ret;
    struct usbip_header pdu;
    struct stub_device *sdev = container_of(ud, struct stub_device, ud);
    struct device *dev = &sdev->interface->dev;

    usbip_dbg_stub_rx("Enter\n");

    memset(&pdu, 0, sizeof(pdu));

    /* 1. receive a pdu header */
    ret = usbip_recv(ud->tcp_socket, &pdu, sizeof(pdu));
    if (ret != sizeof(pdu)) {
        dev_err(dev, "recv a header, %d\n", ret);
        usbip_event_add(ud, SDEV_EVENT_ERROR_TCP);
        return;
    }

    usbip_header_correct_endian(&pdu, 0);

    if (usbip_dbg_flag_stub_rx)
        usbip_dump_header(&pdu);

    if (!valid_request(sdev, &pdu)) {
        dev_err(dev, "recv invalid request\n");
        usbip_event_add(ud, SDEV_EVENT_ERROR_TCP);
        return;
    }

    switch (pdu.base.command) {
    case USBIP_CMD_UNLINK:
        stub_recv_cmd_unlink(sdev, &pdu);
        break;

    case USBIP_CMD_SUBMIT:
        stub_recv_cmd_submit(sdev, &pdu);
        break;

    default:
        /* NOTREACHED */
        dev_err(dev, "unknown pdu\n");
        usbip_event_add(ud, SDEV_EVENT_ERROR_TCP);
        break;
    }
}

int stub_rx_loop(void *data)
{
    struct usbip_device *ud = data;

    while (!kthread_should_stop()) {
        if (usbip_event_happened(ud))
            break;

        stub_rx_pdu(ud);
    }

    return 0;
}