/* License: GPL */

#include <linux/filter.h>
#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/kernel.h>
#include <linux/tcp.h>
#include <linux/workqueue.h>
#include <linux/nospec.h>
#include <linux/cookie.h>
#include <linux/inet_diag.h>
#include <linux/sock_diag.h>

static const struct sock_diag_handler __rcu *sock_diag_handlers[AF_MAX];

static const struct sock_diag_inet_compat __rcu *inet_rcv_compat;

static struct workqueue_struct *broadcast_wq;

DEFINE_COOKIE(sock_cookie);

u64 __sock_gen_cookie(struct sock *sk)
{
        u64 res = atomic64_read(&sk->sk_cookie);

        if (!res) {
                u64 new = gen_cookie_next(&sock_cookie);

                atomic64_cmpxchg(&sk->sk_cookie, res, new);

                /* Another thread might have changed sk_cookie before us. */
                res = atomic64_read(&sk->sk_cookie);
        }
        return res;
}

int sock_diag_check_cookie(struct sock *sk, const __u32 *cookie)
{
        u64 res;

        if (cookie[0] == INET_DIAG_NOCOOKIE && cookie[1] == INET_DIAG_NOCOOKIE)
                return 0;

        res = sock_gen_cookie(sk);
        if ((u32)res != cookie[0] || (u32)(res >> 32) != cookie[1])
                return -ESTALE;

        return 0;
}
EXPORT_SYMBOL_GPL(sock_diag_check_cookie);

void sock_diag_save_cookie(struct sock *sk, __u32 *cookie)
{
        u64 res = sock_gen_cookie(sk);

        cookie[0] = (u32)res;
        cookie[1] = (u32)(res >> 32);
}
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];

        sk_get_meminfo(sk, mem);

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

int sock_diag_put_filterinfo(bool may_report_filterinfo, struct sock *sk,
                             struct sk_buff *skb, int attrtype)
{
        struct sock_fprog_kern *fprog;
        struct sk_filter *filter;
        struct nlattr *attr;
        unsigned int flen;
        int err = 0;

        if (!may_report_filterinfo) {
                nla_reserve(skb, attrtype, 0);
                return 0;
        }

        rcu_read_lock();
        filter = rcu_dereference(sk->sk_filter);
        if (!filter)
                goto out;

        fprog = filter->prog->orig_prog;
        if (!fprog)
                goto out;

        flen = bpf_classic_proglen(fprog);

        attr = nla_reserve(skb, attrtype, flen);
        if (attr == NULL) {
                err = -EMSGSIZE;
                goto out;
        }

        memcpy(nla_data(attr), fprog->filter, flen);
out:
        rcu_read_unlock();
        return err;
}
EXPORT_SYMBOL(sock_diag_put_filterinfo);

struct broadcast_sk {
        struct sock *sk;
        struct work_struct work;
};

static size_t sock_diag_nlmsg_size(void)
{
        return NLMSG_ALIGN(sizeof(struct inet_diag_msg)
               + nla_total_size(sizeof(u8)) /* INET_DIAG_PROTOCOL */
               + nla_total_size_64bit(sizeof(struct tcp_info))); /* INET_DIAG_INFO */
}

static const struct sock_diag_handler *sock_diag_lock_handler(int family)
{
        const struct sock_diag_handler *handler;

        rcu_read_lock();
        handler = rcu_dereference(sock_diag_handlers[family]);
        if (handler && !try_module_get(handler->owner))
                handler = NULL;
        rcu_read_unlock();

        return handler;
}

static void sock_diag_unlock_handler(const struct sock_diag_handler *handler)
{
        module_put(handler->owner);
}

static void sock_diag_broadcast_destroy_work(struct work_struct *work)
{
        struct broadcast_sk *bsk =
                container_of(work, struct broadcast_sk, work);
        struct sock *sk = bsk->sk;
        const struct sock_diag_handler *hndl;
        struct sk_buff *skb;
        const enum sknetlink_groups group = sock_diag_destroy_group(sk);
        int err = -1;

        WARN_ON(group == SKNLGRP_NONE);

        skb = nlmsg_new(sock_diag_nlmsg_size(), GFP_KERNEL);
        if (!skb)
                goto out;

        hndl = sock_diag_lock_handler(sk->sk_family);
        if (hndl) {
                if (hndl->get_info)
                        err = hndl->get_info(skb, sk);
                sock_diag_unlock_handler(hndl);
        }
        if (!err)
                nlmsg_multicast(sock_net(sk)->diag_nlsk, skb, 0, group,
                                GFP_KERNEL);
        else
                kfree_skb(skb);
out:
        sk_destruct(sk);
        kfree(bsk);
}

void sock_diag_broadcast_destroy(struct sock *sk)
{
        /* Note, this function is often called from an interrupt context. */
        struct broadcast_sk *bsk =
                kmalloc_obj(struct broadcast_sk, GFP_ATOMIC);
        if (!bsk)
                return sk_destruct(sk);
        bsk->sk = sk;
        INIT_WORK(&bsk->work, sock_diag_broadcast_destroy_work);
        queue_work(broadcast_wq, &bsk->work);
}

void sock_diag_register_inet_compat(const struct sock_diag_inet_compat *ptr)
{
        xchg(&inet_rcv_compat, RCU_INITIALIZER(ptr));
}
EXPORT_SYMBOL_GPL(sock_diag_register_inet_compat);

void sock_diag_unregister_inet_compat(const struct sock_diag_inet_compat *ptr)
{
        const struct sock_diag_inet_compat *old;

        old = unrcu_pointer(xchg(&inet_rcv_compat, NULL));
        WARN_ON_ONCE(old != ptr);
}
EXPORT_SYMBOL_GPL(sock_diag_unregister_inet_compat);

int sock_diag_register(const struct sock_diag_handler *hndl)
{
        int family = hndl->family;

        if (family >= AF_MAX)
                return -EINVAL;

        return !cmpxchg((const struct sock_diag_handler **)
                                &sock_diag_handlers[family],
                        NULL, hndl) ? 0 : -EBUSY;
}
EXPORT_SYMBOL_GPL(sock_diag_register);

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

        if (family >= AF_MAX)
                return;

        xchg((const struct sock_diag_handler **)&sock_diag_handlers[family],
             NULL);
}
EXPORT_SYMBOL_GPL(sock_diag_unregister);

static int __sock_diag_cmd(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;

        if (req->sdiag_family >= AF_MAX)
                return -EINVAL;
        req->sdiag_family = array_index_nospec(req->sdiag_family, AF_MAX);

        if (!rcu_access_pointer(sock_diag_handlers[req->sdiag_family]))
                sock_load_diag_module(req->sdiag_family, 0);

        hndl = sock_diag_lock_handler(req->sdiag_family);
        if (hndl == NULL)
                return -ENOENT;

        if (nlh->nlmsg_type == SOCK_DIAG_BY_FAMILY)
                err = hndl->dump(skb, nlh);
        else if (nlh->nlmsg_type == SOCK_DESTROY && hndl->destroy)
                err = hndl->destroy(skb, nlh);
        else
                err = -EOPNOTSUPP;
        sock_diag_unlock_handler(hndl);

        return err;
}

static int sock_diag_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh,
                             struct netlink_ext_ack *extack)
{
        const struct sock_diag_inet_compat *ptr;
        int ret;

        switch (nlh->nlmsg_type) {
        case TCPDIAG_GETSOCK:
                if (!rcu_access_pointer(inet_rcv_compat))
                        sock_load_diag_module(AF_INET, 0);

                rcu_read_lock();
                ptr = rcu_dereference(inet_rcv_compat);
                if (ptr && !try_module_get(ptr->owner))
                        ptr = NULL;
                rcu_read_unlock();

                ret = -EOPNOTSUPP;
                if (ptr) {
                        ret = ptr->fn(skb, nlh);
                        module_put(ptr->owner);
                }

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

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

static int sock_diag_bind(struct net *net, int group)
{
        switch (group) {
        case SKNLGRP_INET_TCP_DESTROY:
        case SKNLGRP_INET_UDP_DESTROY:
                if (!rcu_access_pointer(sock_diag_handlers[AF_INET]))
                        sock_load_diag_module(AF_INET, 0);
                break;
        case SKNLGRP_INET6_TCP_DESTROY:
        case SKNLGRP_INET6_UDP_DESTROY:
                if (!rcu_access_pointer(sock_diag_handlers[AF_INET6]))
                        sock_load_diag_module(AF_INET6, 0);
                break;
        }
        return 0;
}

int sock_diag_destroy(struct sock *sk, int err)
{
        if (!ns_capable(sock_net(sk)->user_ns, CAP_NET_ADMIN))
                return -EPERM;

        if (!sk->sk_prot->diag_destroy)
                return -EOPNOTSUPP;

        return sk->sk_prot->diag_destroy(sk, err);
}
EXPORT_SYMBOL_GPL(sock_diag_destroy);

static int __net_init diag_net_init(struct net *net)
{
        struct netlink_kernel_cfg cfg = {
                .groups = SKNLGRP_MAX,
                .input  = sock_diag_rcv,
                .bind   = sock_diag_bind,
                .flags  = NL_CFG_F_NONROOT_RECV,
        };

        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)
{
        broadcast_wq = alloc_workqueue("sock_diag_events", WQ_PERCPU, 0);
        BUG_ON(!broadcast_wq);
        return register_pernet_subsys(&diag_net_ops);
}
device_initcall(sock_diag_init);