sock_diag.c

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#include <linux/mutex.h>
#include <linux/socket.h>
#include <linux/skbuff.h>
#include <net/netlink.h>
#include <net/net_namespace.h>
#include <linux/module.h>
#include <net/sock.h>

#include <linux/inet_diag.h>
#include <linux/sock_diag.h>

static const struct sock_diag_handler *sock_diag_handlers[AF_MAX];
static int (*inet_rcv_compat)(struct sk_buff *skb, struct nlmsghdr *nlh);
static DEFINE_MUTEX(sock_diag_table_mutex);

int sock_diag_check_cookie(void *sk, __u32 *cookie)
{
    if ((cookie[0] != INET_DIAG_NOCOOKIE ||
         cookie[1] != INET_DIAG_NOCOOKIE) &&
        ((u32)(unsigned long)sk != cookie[0] ||
         (u32)((((unsigned long)sk) >> 31) >> 1) != cookie[1]))
        return -ESTALE;
    else
        return 0;
}
EXPORT_SYMBOL_GPL(sock_diag_check_cookie);

void sock_diag_save_cookie(void *sk, __u32 *cookie)
{
    cookie[0] = (u32)(unsigned long)sk;
    cookie[1] = (u32)(((unsigned long)sk >> 31) >> 1);
}
EXPORT_SYMBOL_GPL(sock_diag_save_cookie);

int sock_diag_put_meminfo(struct sock *sk, struct sk_buff *skb, int attrtype)
{
    u32 mem[SK_MEMINFO_VARS];

    mem[SK_MEMINFO_RMEM_ALLOC] = sk_rmem_alloc_get(sk);
    mem[SK_MEMINFO_RCVBUF] = sk->sk_rcvbuf;
    mem[SK_MEMINFO_WMEM_ALLOC] = sk_wmem_alloc_get(sk);
    mem[SK_MEMINFO_SNDBUF] = sk->sk_sndbuf;
    mem[SK_MEMINFO_FWD_ALLOC] = sk->sk_forward_alloc;
    mem[SK_MEMINFO_WMEM_QUEUED] = sk->sk_wmem_queued;
    mem[SK_MEMINFO_OPTMEM] = atomic_read(&sk->sk_omem_alloc);
    mem[SK_MEMINFO_BACKLOG] = sk->sk_backlog.len;

    return nla_put(skb, attrtype, sizeof(mem), &mem);
}
EXPORT_SYMBOL_GPL(sock_diag_put_meminfo);

void sock_diag_register_inet_compat(int (*fn)(struct sk_buff *skb, struct nlmsghdr *nlh))
{
    mutex_lock(&sock_diag_table_mutex);
    inet_rcv_compat = fn;
    mutex_unlock(&sock_diag_table_mutex);
}
EXPORT_SYMBOL_GPL(sock_diag_register_inet_compat);

void sock_diag_unregister_inet_compat(int (*fn)(struct sk_buff *skb, struct nlmsghdr *nlh))
{
    mutex_lock(&sock_diag_table_mutex);
    inet_rcv_compat = NULL;
    mutex_unlock(&sock_diag_table_mutex);
}
EXPORT_SYMBOL_GPL(sock_diag_unregister_inet_compat);

int sock_diag_register(const struct sock_diag_handler *hndl)
{
    int err = 0;

    if (hndl->family >= AF_MAX)
        return -EINVAL;

    mutex_lock(&sock_diag_table_mutex);
    if (sock_diag_handlers[hndl->family])
        err = -EBUSY;
    else
        sock_diag_handlers[hndl->family] = hndl;
    mutex_unlock(&sock_diag_table_mutex);

    return err;
}
EXPORT_SYMBOL_GPL(sock_diag_register);

void sock_diag_unregister(const struct sock_diag_handler *hnld)
{
    int family = hnld->family;

    if (family >= AF_MAX)
        return;

    mutex_lock(&sock_diag_table_mutex);
    BUG_ON(sock_diag_handlers[family] != hnld);
    sock_diag_handlers[family] = NULL;
    mutex_unlock(&sock_diag_table_mutex);
}
EXPORT_SYMBOL_GPL(sock_diag_unregister);

static const inline struct sock_diag_handler *sock_diag_lock_handler(int family)
{
    if (sock_diag_handlers[family] == NULL)
        request_module("net-pf-%d-proto-%d-type-%d", PF_NETLINK,
                NETLINK_SOCK_DIAG, family);

    mutex_lock(&sock_diag_table_mutex);
    return sock_diag_handlers[family];
}

static inline void sock_diag_unlock_handler(const struct sock_diag_handler *h)
{
    mutex_unlock(&sock_diag_table_mutex);
}

static int __sock_diag_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
{
    int err;
    struct sock_diag_req *req = nlmsg_data(nlh);
    const struct sock_diag_handler *hndl;

    if (nlmsg_len(nlh) < sizeof(*req))
        return -EINVAL;

    hndl = sock_diag_lock_handler(req->sdiag_family);
    if (hndl == NULL)
        err = -ENOENT;
    else
        err = hndl->dump(skb, nlh);
    sock_diag_unlock_handler(hndl);

    return err;
}

static int sock_diag_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
{
    int ret;

    switch (nlh->nlmsg_type) {
    case TCPDIAG_GETSOCK:
    case DCCPDIAG_GETSOCK:
        if (inet_rcv_compat == NULL)
            request_module("net-pf-%d-proto-%d-type-%d", PF_NETLINK,
                    NETLINK_SOCK_DIAG, AF_INET);

        mutex_lock(&sock_diag_table_mutex);
        if (inet_rcv_compat != NULL)
            ret = inet_rcv_compat(skb, nlh);
        else
            ret = -EOPNOTSUPP;
        mutex_unlock(&sock_diag_table_mutex);

        return ret;
    case SOCK_DIAG_BY_FAMILY:
        return __sock_diag_rcv_msg(skb, nlh);
    default:
        return -EINVAL;
    }
}

static DEFINE_MUTEX(sock_diag_mutex);

static void sock_diag_rcv(struct sk_buff *skb)
{
    mutex_lock(&sock_diag_mutex);
    netlink_rcv_skb(skb, &sock_diag_rcv_msg);
    mutex_unlock(&sock_diag_mutex);
}

static int __net_init diag_net_init(struct net *net)
{
    struct netlink_kernel_cfg cfg = {
        .input  = sock_diag_rcv,
    };

    net->diag_nlsk = netlink_kernel_create(net, NETLINK_SOCK_DIAG, &cfg);
    return net->diag_nlsk == NULL ? -ENOMEM : 0;
}

static void __net_exit diag_net_exit(struct net *net)
{
    netlink_kernel_release(net->diag_nlsk);
    net->diag_nlsk = NULL;
}

static struct pernet_operations diag_net_ops = {
    .init = diag_net_init,
    .exit = diag_net_exit,
};

static int __init sock_diag_init(void)
{
    return register_pernet_subsys(&diag_net_ops);
}

static void __exit sock_diag_exit(void)
{
    unregister_pernet_subsys(&diag_net_ops);
}

module_init(sock_diag_init);
module_exit(sock_diag_exit);
MODULE_LICENSE("GPL");
MODULE_ALIAS_NET_PF_PROTO(PF_NETLINK, NETLINK_SOCK_DIAG);