netlink.c

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/*
 * Copyright (c) 2010 Voltaire Inc.  All rights reserved.
 *
 * This software is available to you under a choice of one of two
 * licenses.  You may choose to be licensed under the terms of the GNU
 * General Public License (GPL) Version 2, available from the file
 * COPYING in the main directory of this source tree, or the
 * OpenIB.org BSD license below:
 *
 *     Redistribution and use in source and binary forms, with or
 *     without modification, are permitted provided that the following
 *     conditions are met:
 *
 *      - Redistributions of source code must retain the above
 *        copyright notice, this list of conditions and the following
 *        disclaimer.
 *
 *      - Redistributions in binary form must reproduce the above
 *        copyright notice, this list of conditions and the following
 *        disclaimer in the documentation and/or other materials
 *        provided with the distribution.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

#define pr_fmt(fmt) "%s:%s: " fmt, KBUILD_MODNAME, __func__

#include <linux/export.h>
#include <net/netlink.h>
#include <net/net_namespace.h>
#include <net/sock.h>
#include <rdma/rdma_netlink.h>

struct ibnl_client {
    struct list_head        list;
    int             index;
    int             nops;
    const struct ibnl_client_cbs   *cb_table;
};

static DEFINE_MUTEX(ibnl_mutex);
static struct sock *nls;
static LIST_HEAD(client_list);

int ibnl_add_client(int index, int nops,
            const struct ibnl_client_cbs cb_table[])
{
    struct ibnl_client *cur;
    struct ibnl_client *nl_client;

    nl_client = kmalloc(sizeof *nl_client, GFP_KERNEL);
    if (!nl_client)
        return -ENOMEM;

    nl_client->index    = index;
    nl_client->nops     = nops;
    nl_client->cb_table = cb_table;

    mutex_lock(&ibnl_mutex);

    list_for_each_entry(cur, &client_list, list) {
        if (cur->index == index) {
            pr_warn("Client for %d already exists\n", index);
            mutex_unlock(&ibnl_mutex);
            kfree(nl_client);
            return -EINVAL;
        }
    }

    list_add_tail(&nl_client->list, &client_list);

    mutex_unlock(&ibnl_mutex);

    return 0;
}
EXPORT_SYMBOL(ibnl_add_client);

int ibnl_remove_client(int index)
{
    struct ibnl_client *cur, *next;

    mutex_lock(&ibnl_mutex);
    list_for_each_entry_safe(cur, next, &client_list, list) {
        if (cur->index == index) {
            list_del(&(cur->list));
            mutex_unlock(&ibnl_mutex);
            kfree(cur);
            return 0;
        }
    }
    pr_warn("Can't remove callback for client idx %d. Not found\n", index);
    mutex_unlock(&ibnl_mutex);

    return -EINVAL;
}
EXPORT_SYMBOL(ibnl_remove_client);

void *ibnl_put_msg(struct sk_buff *skb, struct nlmsghdr **nlh, int seq,
           int len, int client, int op)
{
    unsigned char *prev_tail;

    prev_tail = skb_tail_pointer(skb);
    *nlh = nlmsg_put(skb, 0, seq, RDMA_NL_GET_TYPE(client, op),
             len, NLM_F_MULTI);
    if (!*nlh)
        goto out_nlmsg_trim;
    (*nlh)->nlmsg_len = skb_tail_pointer(skb) - prev_tail;
    return nlmsg_data(*nlh);

out_nlmsg_trim:
    nlmsg_trim(skb, prev_tail);
    return NULL;
}
EXPORT_SYMBOL(ibnl_put_msg);

int ibnl_put_attr(struct sk_buff *skb, struct nlmsghdr *nlh,
          int len, void *data, int type)
{
    unsigned char *prev_tail;

    prev_tail = skb_tail_pointer(skb);
    if (nla_put(skb, type, len, data))
        goto nla_put_failure;
    nlh->nlmsg_len += skb_tail_pointer(skb) - prev_tail;
    return 0;

nla_put_failure:
    nlmsg_trim(skb, prev_tail - nlh->nlmsg_len);
    return -EMSGSIZE;
}
EXPORT_SYMBOL(ibnl_put_attr);

static int ibnl_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
{
    struct ibnl_client *client;
    int type = nlh->nlmsg_type;
    int index = RDMA_NL_GET_CLIENT(type);
    int op = RDMA_NL_GET_OP(type);

    list_for_each_entry(client, &client_list, list) {
        if (client->index == index) {
            if (op < 0 || op >= client->nops ||
                !client->cb_table[RDMA_NL_GET_OP(op)].dump)
                return -EINVAL;

            {
                struct netlink_dump_control c = {
                    .dump = client->cb_table[op].dump,
                    .module = client->cb_table[op].module,
                };
                return netlink_dump_start(nls, skb, nlh, &c);
            }
        }
    }

    pr_info("Index %d wasn't found in client list\n", index);
    return -EINVAL;
}

static void ibnl_rcv(struct sk_buff *skb)
{
    mutex_lock(&ibnl_mutex);
    netlink_rcv_skb(skb, &ibnl_rcv_msg);
    mutex_unlock(&ibnl_mutex);
}

int __init ibnl_init(void)
{
    struct netlink_kernel_cfg cfg = {
        .input  = ibnl_rcv,
    };

    nls = netlink_kernel_create(&init_net, NETLINK_RDMA, &cfg);
    if (!nls) {
        pr_warn("Failed to create netlink socket\n");
        return -ENOMEM;
    }

    return 0;
}

void ibnl_cleanup(void)
{
    struct ibnl_client *cur, *next;

    mutex_lock(&ibnl_mutex);
    list_for_each_entry_safe(cur, next, &client_list, list) {
        list_del(&(cur->list));
        kfree(cur);
    }
    mutex_unlock(&ibnl_mutex);

    netlink_kernel_release(nls);
}