hv_kvp.c

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/*
 * An implementation of key value pair (KVP) functionality for Linux.
 *
 *
 * Copyright (C) 2010, Novell, Inc.
 * Author : K. Y. Srinivasan <[email protected]>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 as published
 * by the Free Software Foundation.
 *
 * This program 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, GOOD TITLE or
 * NON INFRINGEMENT.  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., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 */
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/net.h>
#include <linux/nls.h>
#include <linux/connector.h>
#include <linux/workqueue.h>
#include <linux/hyperv.h>



/*
 * Global state maintained for transaction that is being processed.
 * Note that only one transaction can be active at any point in time.
 *
 * This state is set when we receive a request from the host; we
 * cleanup this state when the transaction is completed - when we respond
 * to the host with the key value.
 */

static struct {
    bool active; /* transaction status - active or not */
    int recv_len; /* number of bytes received. */
    struct hv_kvp_msg  *kvp_msg; /* current message */
    struct vmbus_channel *recv_channel; /* chn we got the request */
    u64 recv_req_id; /* request ID. */
    void *kvp_context; /* for the channel callback */
} kvp_transaction;

/*
 * Before we can accept KVP messages from the host, we need
 * to handshake with the user level daemon. This state tracks
 * if we are in the handshake phase.
 */
static bool in_hand_shake = true;

/*
 * This state maintains the version number registered by the daemon.
 */
static int dm_reg_value;

static void kvp_send_key(struct work_struct *dummy);


static void kvp_respond_to_host(struct hv_kvp_msg *msg, int error);
static void kvp_work_func(struct work_struct *dummy);
static void kvp_register(int);

static DECLARE_DELAYED_WORK(kvp_work, kvp_work_func);
static DECLARE_WORK(kvp_sendkey_work, kvp_send_key);

static struct cb_id kvp_id = { CN_KVP_IDX, CN_KVP_VAL };
static const char kvp_name[] = "kvp_kernel_module";
static u8 *recv_buffer;
/*
 * Register the kernel component with the user-level daemon.
 * As part of this registration, pass the LIC version number.
 */

static void
kvp_register(int reg_value)
{

    struct cn_msg *msg;
    struct hv_kvp_msg *kvp_msg;
    char *version;

    msg = kzalloc(sizeof(*msg) + sizeof(struct hv_kvp_msg), GFP_ATOMIC);

    if (msg) {
        kvp_msg = (struct hv_kvp_msg *)msg->data;
        version = kvp_msg->body.kvp_register.version;
        msg->id.idx =  CN_KVP_IDX;
        msg->id.val = CN_KVP_VAL;

        kvp_msg->kvp_hdr.operation = reg_value;
        strcpy(version, HV_DRV_VERSION);
        msg->len = sizeof(struct hv_kvp_msg);
        cn_netlink_send(msg, 0, GFP_ATOMIC);
        kfree(msg);
    }
}
static void
kvp_work_func(struct work_struct *dummy)
{
    /*
     * If the timer fires, the user-mode component has not responded;
     * process the pending transaction.
     */
    kvp_respond_to_host(NULL, HV_E_FAIL);
}

static int kvp_handle_handshake(struct hv_kvp_msg *msg)
{
    int ret = 1;

    switch (msg->kvp_hdr.operation) {
    case KVP_OP_REGISTER:
        dm_reg_value = KVP_OP_REGISTER;
        pr_info("KVP: IP injection functionality not available\n");
        pr_info("KVP: Upgrade the KVP daemon\n");
        break;
    case KVP_OP_REGISTER1:
        dm_reg_value = KVP_OP_REGISTER1;
        break;
    default:
        pr_info("KVP: incompatible daemon\n");
        pr_info("KVP: KVP version: %d, Daemon version: %d\n",
            KVP_OP_REGISTER1, msg->kvp_hdr.operation);
        ret = 0;
    }

    if (ret) {
        /*
         * We have a compatible daemon; complete the handshake.
         */
        pr_info("KVP: user-mode registering done.\n");
        kvp_register(dm_reg_value);
        kvp_transaction.active = false;
        if (kvp_transaction.kvp_context)
            hv_kvp_onchannelcallback(kvp_transaction.kvp_context);
    }
    return ret;
}


/*
 * Callback when data is received from user mode.
 */

static void
kvp_cn_callback(struct cn_msg *msg, struct netlink_skb_parms *nsp)
{
    struct hv_kvp_msg *message;
    struct hv_kvp_msg_enumerate *data;
    int error = 0;

    message = (struct hv_kvp_msg *)msg->data;

    /*
     * If we are negotiating the version information
     * with the daemon; handle that first.
     */

    if (in_hand_shake) {
        if (kvp_handle_handshake(message))
            in_hand_shake = false;
        return;
    }

    /*
     * Based on the version of the daemon, we propagate errors from the
     * daemon differently.
     */

    data = &message->body.kvp_enum_data;

    switch (dm_reg_value) {
    case KVP_OP_REGISTER:
        /*
         * Null string is used to pass back error condition.
         */
        if (data->data.key[0] == 0)
            error = HV_S_CONT;
        break;

    case KVP_OP_REGISTER1:
        /*
         * We use the message header information from
         * the user level daemon to transmit errors.
         */
        error = message->error;
        break;
    }

    /*
     * Complete the transaction by forwarding the key value
     * to the host. But first, cancel the timeout.
     */
    if (cancel_delayed_work_sync(&kvp_work))
        kvp_respond_to_host(message, error);
}


static int process_ob_ipinfo(void *in_msg, void *out_msg, int op)
{
    struct hv_kvp_msg *in = in_msg;
    struct hv_kvp_ip_msg *out = out_msg;
    int len;

    switch (op) {
    case KVP_OP_GET_IP_INFO:
        /*
         * Transform all parameters into utf16 encoding.
         */
        len = utf8s_to_utf16s((char *)in->body.kvp_ip_val.ip_addr,
                strlen((char *)in->body.kvp_ip_val.ip_addr),
                UTF16_HOST_ENDIAN,
                (wchar_t *)out->kvp_ip_val.ip_addr,
                MAX_IP_ADDR_SIZE);
        if (len < 0)
            return len;

        len = utf8s_to_utf16s((char *)in->body.kvp_ip_val.sub_net,
                strlen((char *)in->body.kvp_ip_val.sub_net),
                UTF16_HOST_ENDIAN,
                (wchar_t *)out->kvp_ip_val.sub_net,
                MAX_IP_ADDR_SIZE);
        if (len < 0)
            return len;

        len = utf8s_to_utf16s((char *)in->body.kvp_ip_val.gate_way,
                strlen((char *)in->body.kvp_ip_val.gate_way),
                UTF16_HOST_ENDIAN,
                (wchar_t *)out->kvp_ip_val.gate_way,
                MAX_GATEWAY_SIZE);
        if (len < 0)
            return len;

        len = utf8s_to_utf16s((char *)in->body.kvp_ip_val.dns_addr,
                strlen((char *)in->body.kvp_ip_val.dns_addr),
                UTF16_HOST_ENDIAN,
                (wchar_t *)out->kvp_ip_val.dns_addr,
                MAX_IP_ADDR_SIZE);
        if (len < 0)
            return len;

        len = utf8s_to_utf16s((char *)in->body.kvp_ip_val.adapter_id,
                strlen((char *)in->body.kvp_ip_val.adapter_id),
                UTF16_HOST_ENDIAN,
                (wchar_t *)out->kvp_ip_val.adapter_id,
                MAX_IP_ADDR_SIZE);
        if (len < 0)
            return len;

        out->kvp_ip_val.dhcp_enabled =
            in->body.kvp_ip_val.dhcp_enabled;
        out->kvp_ip_val.addr_family =
            in->body.kvp_ip_val.addr_family;
    }

    return 0;
}

static void process_ib_ipinfo(void *in_msg, void *out_msg, int op)
{
    struct hv_kvp_ip_msg *in = in_msg;
    struct hv_kvp_msg *out = out_msg;

    switch (op) {
    case KVP_OP_SET_IP_INFO:
        /*
         * Transform all parameters into utf8 encoding.
         */
        utf16s_to_utf8s((wchar_t *)in->kvp_ip_val.ip_addr,
                MAX_IP_ADDR_SIZE,
                UTF16_LITTLE_ENDIAN,
                (__u8 *)out->body.kvp_ip_val.ip_addr,
                MAX_IP_ADDR_SIZE);

        utf16s_to_utf8s((wchar_t *)in->kvp_ip_val.sub_net,
                MAX_IP_ADDR_SIZE,
                UTF16_LITTLE_ENDIAN,
                (__u8 *)out->body.kvp_ip_val.sub_net,
                MAX_IP_ADDR_SIZE);

        utf16s_to_utf8s((wchar_t *)in->kvp_ip_val.gate_way,
                MAX_GATEWAY_SIZE,
                UTF16_LITTLE_ENDIAN,
                (__u8 *)out->body.kvp_ip_val.gate_way,
                MAX_GATEWAY_SIZE);

        utf16s_to_utf8s((wchar_t *)in->kvp_ip_val.dns_addr,
                MAX_IP_ADDR_SIZE,
                UTF16_LITTLE_ENDIAN,
                (__u8 *)out->body.kvp_ip_val.dns_addr,
                MAX_IP_ADDR_SIZE);

        out->body.kvp_ip_val.dhcp_enabled = in->kvp_ip_val.dhcp_enabled;

    default:
        utf16s_to_utf8s((wchar_t *)in->kvp_ip_val.adapter_id,
                MAX_ADAPTER_ID_SIZE,
                UTF16_LITTLE_ENDIAN,
                (__u8 *)out->body.kvp_ip_val.adapter_id,
                MAX_ADAPTER_ID_SIZE);

        out->body.kvp_ip_val.addr_family = in->kvp_ip_val.addr_family;
    }
}




static void
kvp_send_key(struct work_struct *dummy)
{
    struct cn_msg *msg;
    struct hv_kvp_msg *message;
    struct hv_kvp_msg *in_msg;
    __u8 operation = kvp_transaction.kvp_msg->kvp_hdr.operation;
    __u8 pool = kvp_transaction.kvp_msg->kvp_hdr.pool;
    __u32 val32;
    __u64 val64;

    msg = kzalloc(sizeof(*msg) + sizeof(struct hv_kvp_msg) , GFP_ATOMIC);
    if (!msg)
        return;

    msg->id.idx =  CN_KVP_IDX;
    msg->id.val = CN_KVP_VAL;

    message = (struct hv_kvp_msg *)msg->data;
    message->kvp_hdr.operation = operation;
    message->kvp_hdr.pool = pool;
    in_msg = kvp_transaction.kvp_msg;

    /*
     * The key/value strings sent from the host are encoded in
     * in utf16; convert it to utf8 strings.
     * The host assures us that the utf16 strings will not exceed
     * the max lengths specified. We will however, reserve room
     * for the string terminating character - in the utf16s_utf8s()
     * function we limit the size of the buffer where the converted
     * string is placed to HV_KVP_EXCHANGE_MAX_*_SIZE -1 to gaurantee
     * that the strings can be properly terminated!
     */

    switch (message->kvp_hdr.operation) {
    case KVP_OP_SET_IP_INFO:
        process_ib_ipinfo(in_msg, message, KVP_OP_SET_IP_INFO);
        break;
    case KVP_OP_GET_IP_INFO:
        process_ib_ipinfo(in_msg, message, KVP_OP_GET_IP_INFO);
        break;
    case KVP_OP_SET:
        switch (in_msg->body.kvp_set.data.value_type) {
        case REG_SZ:
            /*
             * The value is a string - utf16 encoding.
             */
            message->body.kvp_set.data.value_size =
                utf16s_to_utf8s(
                (wchar_t *)in_msg->body.kvp_set.data.value,
                in_msg->body.kvp_set.data.value_size,
                UTF16_LITTLE_ENDIAN,
                message->body.kvp_set.data.value,
                HV_KVP_EXCHANGE_MAX_VALUE_SIZE - 1) + 1;
                break;

        case REG_U32:
            /*
             * The value is a 32 bit scalar.
             * We save this as a utf8 string.
             */
            val32 = in_msg->body.kvp_set.data.value_u32;
            message->body.kvp_set.data.value_size =
                sprintf(message->body.kvp_set.data.value,
                    "%d", val32) + 1;
            break;

        case REG_U64:
            /*
             * The value is a 64 bit scalar.
             * We save this as a utf8 string.
             */
            val64 = in_msg->body.kvp_set.data.value_u64;
            message->body.kvp_set.data.value_size =
                sprintf(message->body.kvp_set.data.value,
                    "%llu", val64) + 1;
            break;

        }
    case KVP_OP_GET:
        message->body.kvp_set.data.key_size =
            utf16s_to_utf8s(
            (wchar_t *)in_msg->body.kvp_set.data.key,
            in_msg->body.kvp_set.data.key_size,
            UTF16_LITTLE_ENDIAN,
            message->body.kvp_set.data.key,
            HV_KVP_EXCHANGE_MAX_KEY_SIZE - 1) + 1;
            break;

    case KVP_OP_DELETE:
        message->body.kvp_delete.key_size =
            utf16s_to_utf8s(
            (wchar_t *)in_msg->body.kvp_delete.key,
            in_msg->body.kvp_delete.key_size,
            UTF16_LITTLE_ENDIAN,
            message->body.kvp_delete.key,
            HV_KVP_EXCHANGE_MAX_KEY_SIZE - 1) + 1;
            break;

    case KVP_OP_ENUMERATE:
        message->body.kvp_enum_data.index =
            in_msg->body.kvp_enum_data.index;
            break;
    }

    msg->len = sizeof(struct hv_kvp_msg);
    cn_netlink_send(msg, 0, GFP_ATOMIC);
    kfree(msg);

    return;
}

/*
 * Send a response back to the host.
 */

static void
kvp_respond_to_host(struct hv_kvp_msg *msg_to_host, int error)
{
    struct hv_kvp_msg  *kvp_msg;
    struct hv_kvp_exchg_msg_value  *kvp_data;
    char    *key_name;
    char    *value;
    struct icmsg_hdr *icmsghdrp;
    int keylen = 0;
    int valuelen = 0;
    u32 buf_len;
    struct vmbus_channel *channel;
    u64 req_id;
    int ret;

    /*
     * If a transaction is not active; log and return.
     */

    if (!kvp_transaction.active) {
        /*
         * This is a spurious call!
         */
        pr_warn("KVP: Transaction not active\n");
        return;
    }
    /*
     * Copy the global state for completing the transaction. Note that
     * only one transaction can be active at a time.
     */

    buf_len = kvp_transaction.recv_len;
    channel = kvp_transaction.recv_channel;
    req_id = kvp_transaction.recv_req_id;

    kvp_transaction.active = false;

    icmsghdrp = (struct icmsg_hdr *)
            &recv_buffer[sizeof(struct vmbuspipe_hdr)];

    if (channel->onchannel_callback == NULL)
        /*
         * We have raced with util driver being unloaded;
         * silently return.
         */
        return;

    icmsghdrp->status = error;

    /*
     * If the error parameter is set, terminate the host's enumeration
     * on this pool.
     */
    if (error) {
        /*
         * Something failed or we have timedout;
         * terminate the current host-side iteration.
         */
        goto response_done;
    }

    kvp_msg = (struct hv_kvp_msg *)
            &recv_buffer[sizeof(struct vmbuspipe_hdr) +
            sizeof(struct icmsg_hdr)];

    switch (kvp_transaction.kvp_msg->kvp_hdr.operation) {
    case KVP_OP_GET_IP_INFO:
        ret = process_ob_ipinfo(msg_to_host,
                 (struct hv_kvp_ip_msg *)kvp_msg,
                 KVP_OP_GET_IP_INFO);
        if (ret < 0)
            icmsghdrp->status = HV_E_FAIL;

        goto response_done;
    case KVP_OP_SET_IP_INFO:
        goto response_done;
    case KVP_OP_GET:
        kvp_data = &kvp_msg->body.kvp_get.data;
        goto copy_value;

    case KVP_OP_SET:
    case KVP_OP_DELETE:
        goto response_done;

    default:
        break;
    }

    kvp_data = &kvp_msg->body.kvp_enum_data.data;
    key_name = msg_to_host->body.kvp_enum_data.data.key;

    /*
     * The windows host expects the key/value pair to be encoded
     * in utf16. Ensure that the key/value size reported to the host
     * will be less than or equal to the MAX size (including the
     * terminating character).
     */
    keylen = utf8s_to_utf16s(key_name, strlen(key_name), UTF16_HOST_ENDIAN,
                (wchar_t *) kvp_data->key,
                (HV_KVP_EXCHANGE_MAX_KEY_SIZE / 2) - 2);
    kvp_data->key_size = 2*(keylen + 1); /* utf16 encoding */

copy_value:
    value = msg_to_host->body.kvp_enum_data.data.value;
    valuelen = utf8s_to_utf16s(value, strlen(value), UTF16_HOST_ENDIAN,
                (wchar_t *) kvp_data->value,
                (HV_KVP_EXCHANGE_MAX_VALUE_SIZE / 2) - 2);
    kvp_data->value_size = 2*(valuelen + 1); /* utf16 encoding */

    /*
     * If the utf8s to utf16s conversion failed; notify host
     * of the error.
     */
    if ((keylen < 0) || (valuelen < 0))
        icmsghdrp->status = HV_E_FAIL;

    kvp_data->value_type = REG_SZ; /* all our values are strings */

response_done:
    icmsghdrp->icflags = ICMSGHDRFLAG_TRANSACTION | ICMSGHDRFLAG_RESPONSE;

    vmbus_sendpacket(channel, recv_buffer, buf_len, req_id,
                VM_PKT_DATA_INBAND, 0);

}

/*
 * This callback is invoked when we get a KVP message from the host.
 * The host ensures that only one KVP transaction can be active at a time.
 * KVP implementation in Linux needs to forward the key to a user-mde
 * component to retrive the corresponding value. Consequently, we cannot
 * respond to the host in the conext of this callback. Since the host
 * guarantees that at most only one transaction can be active at a time,
 * we stash away the transaction state in a set of global variables.
 */

void hv_kvp_onchannelcallback(void *context)
{
    struct vmbus_channel *channel = context;
    u32 recvlen;
    u64 requestid;

    struct hv_kvp_msg *kvp_msg;

    struct icmsg_hdr *icmsghdrp;
    struct icmsg_negotiate *negop = NULL;

    if (kvp_transaction.active) {
        /*
         * We will defer processing this callback once
         * the current transaction is complete.
         */
        kvp_transaction.kvp_context = context;
        return;
    }

    vmbus_recvpacket(channel, recv_buffer, PAGE_SIZE * 2, &recvlen,
             &requestid);

    if (recvlen > 0) {
        icmsghdrp = (struct icmsg_hdr *)&recv_buffer[
            sizeof(struct vmbuspipe_hdr)];

        if (icmsghdrp->icmsgtype == ICMSGTYPE_NEGOTIATE) {
            vmbus_prep_negotiate_resp(icmsghdrp, negop,
                 recv_buffer, MAX_SRV_VER, MAX_SRV_VER);
        } else {
            kvp_msg = (struct hv_kvp_msg *)&recv_buffer[
                sizeof(struct vmbuspipe_hdr) +
                sizeof(struct icmsg_hdr)];

            /*
             * Stash away this global state for completing the
             * transaction; note transactions are serialized.
             */

            kvp_transaction.recv_len = recvlen;
            kvp_transaction.recv_channel = channel;
            kvp_transaction.recv_req_id = requestid;
            kvp_transaction.active = true;
            kvp_transaction.kvp_msg = kvp_msg;

            /*
             * Get the information from the
             * user-mode component.
             * component. This transaction will be
             * completed when we get the value from
             * the user-mode component.
             * Set a timeout to deal with
             * user-mode not responding.
             */
            schedule_work(&kvp_sendkey_work);
            schedule_delayed_work(&kvp_work, 5*HZ);

            return;

        }

        icmsghdrp->icflags = ICMSGHDRFLAG_TRANSACTION
            | ICMSGHDRFLAG_RESPONSE;

        vmbus_sendpacket(channel, recv_buffer,
                       recvlen, requestid,
                       VM_PKT_DATA_INBAND, 0);
    }

}

int
hv_kvp_init(struct hv_util_service *srv)
{
    int err;

    err = cn_add_callback(&kvp_id, kvp_name, kvp_cn_callback);
    if (err)
        return err;
    recv_buffer = srv->recv_buffer;

    /*
     * When this driver loads, the user level daemon that
     * processes the host requests may not yet be running.
     * Defer processing channel callbacks until the daemon
     * has registered.
     */
    kvp_transaction.active = true;

    return 0;
}

void hv_kvp_deinit(void)
{
    cn_del_callback(&kvp_id);
    cancel_delayed_work_sync(&kvp_work);
    cancel_work_sync(&kvp_sendkey_work);
}