// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * net/sched/cls_fw.c   Classifier mapping ipchains' fwmark to traffic class.
 *
 * Authors:     Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
 *
 * Changes:
 * Karlis Peisenieks <karlis@mt.lv> : 990415 : fw_walk off by one
 * Karlis Peisenieks <karlis@mt.lv> : 990415 : fw_delete killed all the filter (and kernel).
 * Alex <alex@pilotsoft.com> : 2004xxyy: Added Action extension
 */

#include <linux/module.h>
#include <linux/slab.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/errno.h>
#include <linux/skbuff.h>
#include <net/netlink.h>
#include <net/act_api.h>
#include <net/pkt_cls.h>
#include <net/sch_generic.h>
#include <net/tc_wrapper.h>

#define HTSIZE 256

struct fw_head {
        u32                     mask;
        struct fw_filter __rcu  *ht[HTSIZE];
        struct rcu_head         rcu;
};

struct fw_filter {
        struct fw_filter __rcu  *next;
        u32                     id;
        struct tcf_result       res;
        int                     ifindex;
        struct tcf_exts         exts;
        struct tcf_proto        *tp;
        struct rcu_work         rwork;
};

static u32 fw_hash(u32 handle)
{
        handle ^= (handle >> 16);
        handle ^= (handle >> 8);
        return handle % HTSIZE;
}

TC_INDIRECT_SCOPE int fw_classify(struct sk_buff *skb,
                                  const struct tcf_proto *tp,
                                  struct tcf_result *res)
{
        struct fw_head *head = rcu_dereference_bh(tp->root);
        struct fw_filter *f;
        int r;
        u32 id = skb->mark;

        if (head != NULL) {
                id &= head->mask;

                for (f = rcu_dereference_bh(head->ht[fw_hash(id)]); f;
                     f = rcu_dereference_bh(f->next)) {
                        if (f->id == id) {
                                *res = f->res;
                                if (!tcf_match_indev(skb, f->ifindex))
                                        continue;
                                r = tcf_exts_exec(skb, &f->exts, res);
                                if (r < 0)
                                        continue;

                                return r;
                        }
                }
        } else {
                struct Qdisc *q = tcf_block_q(tp->chain->block);

                /* Old method: classify the packet using its skb mark. */
                if (id && (TC_H_MAJ(id) == 0 ||
                           !(TC_H_MAJ(id ^ q->handle)))) {
                        res->classid = id;
                        res->class = 0;
                        return 0;
                }
        }

        return -1;
}

static void *fw_get(struct tcf_proto *tp, u32 handle)
{
        struct fw_head *head = rtnl_dereference(tp->root);
        struct fw_filter *f;

        if (head == NULL)
                return NULL;

        f = rtnl_dereference(head->ht[fw_hash(handle)]);
        for (; f; f = rtnl_dereference(f->next)) {
                if (f->id == handle)
                        return f;
        }
        return NULL;
}

static int fw_init(struct tcf_proto *tp)
{
        /* We don't allocate fw_head here, because in the old method
         * we don't need it at all.
         */
        return 0;
}

static void __fw_delete_filter(struct fw_filter *f)
{
        tcf_exts_destroy(&f->exts);
        tcf_exts_put_net(&f->exts);
        kfree(f);
}

static void fw_delete_filter_work(struct work_struct *work)
{
        struct fw_filter *f = container_of(to_rcu_work(work),
                                           struct fw_filter,
                                           rwork);
        rtnl_lock();
        __fw_delete_filter(f);
        rtnl_unlock();
}

static void fw_destroy(struct tcf_proto *tp, bool rtnl_held,
                       struct netlink_ext_ack *extack)
{
        struct fw_head *head = rtnl_dereference(tp->root);
        struct fw_filter *f;
        int h;

        if (head == NULL)
                return;

        for (h = 0; h < HTSIZE; h++) {
                while ((f = rtnl_dereference(head->ht[h])) != NULL) {
                        RCU_INIT_POINTER(head->ht[h],
                                         rtnl_dereference(f->next));
                        tcf_unbind_filter(tp, &f->res);
                        if (tcf_exts_get_net(&f->exts))
                                tcf_queue_work(&f->rwork, fw_delete_filter_work);
                        else
                                __fw_delete_filter(f);
                }
        }
        kfree_rcu(head, rcu);
}

static int fw_delete(struct tcf_proto *tp, void *arg, bool *last,
                     bool rtnl_held, struct netlink_ext_ack *extack)
{
        struct fw_head *head = rtnl_dereference(tp->root);
        struct fw_filter *f = arg;
        struct fw_filter __rcu **fp;
        struct fw_filter *pfp;
        int ret = -EINVAL;
        int h;

        if (head == NULL || f == NULL)
                goto out;

        fp = &head->ht[fw_hash(f->id)];

        for (pfp = rtnl_dereference(*fp); pfp;
             fp = &pfp->next, pfp = rtnl_dereference(*fp)) {
                if (pfp == f) {
                        RCU_INIT_POINTER(*fp, rtnl_dereference(f->next));
                        tcf_unbind_filter(tp, &f->res);
                        tcf_exts_get_net(&f->exts);
                        tcf_queue_work(&f->rwork, fw_delete_filter_work);
                        ret = 0;
                        break;
                }
        }

        *last = true;
        for (h = 0; h < HTSIZE; h++) {
                if (rcu_access_pointer(head->ht[h])) {
                        *last = false;
                        break;
                }
        }

out:
        return ret;
}

static const struct nla_policy fw_policy[TCA_FW_MAX + 1] = {
        [TCA_FW_CLASSID]        = { .type = NLA_U32 },
        [TCA_FW_INDEV]          = { .type = NLA_STRING, .len = IFNAMSIZ },
        [TCA_FW_MASK]           = { .type = NLA_U32 },
};

static int fw_set_parms(struct net *net, struct tcf_proto *tp,
                        struct fw_filter *f, struct nlattr **tb,
                        struct nlattr **tca, unsigned long base, u32 flags,
                        struct netlink_ext_ack *extack)
{
        struct fw_head *head = rtnl_dereference(tp->root);
        u32 mask;
        int err;

        err = tcf_exts_validate(net, tp, tb, tca[TCA_RATE], &f->exts, flags,
                                extack);
        if (err < 0)
                return err;

        if (tb[TCA_FW_INDEV]) {
                int ret;
                ret = tcf_change_indev(net, tb[TCA_FW_INDEV], extack);
                if (ret < 0)
                        return ret;
                f->ifindex = ret;
        }

        err = -EINVAL;
        if (tb[TCA_FW_MASK]) {
                mask = nla_get_u32(tb[TCA_FW_MASK]);
                if (mask != head->mask)
                        return err;
        } else if (head->mask != 0xFFFFFFFF)
                return err;

        if (tb[TCA_FW_CLASSID]) {
                f->res.classid = nla_get_u32(tb[TCA_FW_CLASSID]);
                tcf_bind_filter(tp, &f->res, base);
        }

        return 0;
}

static int fw_change(struct net *net, struct sk_buff *in_skb,
                     struct tcf_proto *tp, unsigned long base,
                     u32 handle, struct nlattr **tca, void **arg,
                     u32 flags, struct netlink_ext_ack *extack)
{
        struct fw_head *head = rtnl_dereference(tp->root);
        struct fw_filter *f = *arg;
        struct nlattr *opt = tca[TCA_OPTIONS];
        struct nlattr *tb[TCA_FW_MAX + 1];
        int err;

        if (!opt) {
                if (handle)
                        return -EINVAL;

                if (tcf_block_shared(tp->chain->block)) {
                        NL_SET_ERR_MSG(extack,
                                       "Must specify mark when attaching fw filter to block");
                        return -EINVAL;
                }

                return 0; /* Succeed if it is old method. */
        }

        err = nla_parse_nested_deprecated(tb, TCA_FW_MAX, opt, fw_policy,
                                          NULL);
        if (err < 0)
                return err;

        if (f) {
                struct fw_filter *pfp, *fnew;
                struct fw_filter __rcu **fp;

                if (f->id != handle && handle)
                        return -EINVAL;

                fnew = kzalloc_obj(struct fw_filter);
                if (!fnew)
                        return -ENOBUFS;

                fnew->id = f->id;
                fnew->ifindex = f->ifindex;
                fnew->tp = f->tp;

                err = tcf_exts_init(&fnew->exts, net, TCA_FW_ACT,
                                    TCA_FW_POLICE);
                if (err < 0) {
                        kfree(fnew);
                        return err;
                }

                err = fw_set_parms(net, tp, fnew, tb, tca, base, flags, extack);
                if (err < 0) {
                        tcf_exts_destroy(&fnew->exts);
                        kfree(fnew);
                        return err;
                }

                fp = &head->ht[fw_hash(fnew->id)];
                for (pfp = rtnl_dereference(*fp); pfp;
                     fp = &pfp->next, pfp = rtnl_dereference(*fp))
                        if (pfp == f)
                                break;

                RCU_INIT_POINTER(fnew->next, rtnl_dereference(pfp->next));
                rcu_assign_pointer(*fp, fnew);
                tcf_unbind_filter(tp, &f->res);
                tcf_exts_get_net(&f->exts);
                tcf_queue_work(&f->rwork, fw_delete_filter_work);

                *arg = fnew;
                return err;
        }

        if (!handle)
                return -EINVAL;

        if (!head) {
                u32 mask = 0xFFFFFFFF;
                if (tb[TCA_FW_MASK])
                        mask = nla_get_u32(tb[TCA_FW_MASK]);

                head = kzalloc_obj(*head);
                if (!head)
                        return -ENOBUFS;
                head->mask = mask;

                rcu_assign_pointer(tp->root, head);
        }

        f = kzalloc_obj(struct fw_filter);
        if (f == NULL)
                return -ENOBUFS;

        err = tcf_exts_init(&f->exts, net, TCA_FW_ACT, TCA_FW_POLICE);
        if (err < 0)
                goto errout;
        f->id = handle;
        f->tp = tp;

        err = fw_set_parms(net, tp, f, tb, tca, base, flags, extack);
        if (err < 0)
                goto errout;

        RCU_INIT_POINTER(f->next, head->ht[fw_hash(handle)]);
        rcu_assign_pointer(head->ht[fw_hash(handle)], f);

        *arg = f;
        return 0;

errout:
        tcf_exts_destroy(&f->exts);
        kfree(f);
        return err;
}

static void fw_walk(struct tcf_proto *tp, struct tcf_walker *arg,
                    bool rtnl_held)
{
        struct fw_head *head = rtnl_dereference(tp->root);
        int h;

        if (head == NULL)
                arg->stop = 1;

        if (arg->stop)
                return;

        for (h = 0; h < HTSIZE; h++) {
                struct fw_filter *f;

                for (f = rtnl_dereference(head->ht[h]); f;
                     f = rtnl_dereference(f->next)) {
                        if (!tc_cls_stats_dump(tp, arg, f))
                                return;
                }
        }
}

static int fw_dump(struct net *net, struct tcf_proto *tp, void *fh,
                   struct sk_buff *skb, struct tcmsg *t, bool rtnl_held)
{
        struct fw_head *head = rtnl_dereference(tp->root);
        struct fw_filter *f = fh;
        struct nlattr *nest;

        if (f == NULL)
                return skb->len;

        t->tcm_handle = f->id;

        if (!f->res.classid && !tcf_exts_has_actions(&f->exts))
                return skb->len;

        nest = nla_nest_start_noflag(skb, TCA_OPTIONS);
        if (nest == NULL)
                goto nla_put_failure;

        if (f->res.classid &&
            nla_put_u32(skb, TCA_FW_CLASSID, f->res.classid))
                goto nla_put_failure;
        if (f->ifindex) {
                struct net_device *dev;
                dev = __dev_get_by_index(net, f->ifindex);
                if (dev && nla_put_string(skb, TCA_FW_INDEV, dev->name))
                        goto nla_put_failure;
        }
        if (head->mask != 0xFFFFFFFF &&
            nla_put_u32(skb, TCA_FW_MASK, head->mask))
                goto nla_put_failure;

        if (tcf_exts_dump(skb, &f->exts) < 0)
                goto nla_put_failure;

        nla_nest_end(skb, nest);

        if (tcf_exts_dump_stats(skb, &f->exts) < 0)
                goto nla_put_failure;

        return skb->len;

nla_put_failure:
        nla_nest_cancel(skb, nest);
        return -1;
}

static void fw_bind_class(void *fh, u32 classid, unsigned long cl, void *q,
                          unsigned long base)
{
        struct fw_filter *f = fh;

        tc_cls_bind_class(classid, cl, q, &f->res, base);
}

static struct tcf_proto_ops cls_fw_ops __read_mostly = {
        .kind           =       "fw",
        .classify       =       fw_classify,
        .init           =       fw_init,
        .destroy        =       fw_destroy,
        .get            =       fw_get,
        .change         =       fw_change,
        .delete         =       fw_delete,
        .walk           =       fw_walk,
        .dump           =       fw_dump,
        .bind_class     =       fw_bind_class,
        .owner          =       THIS_MODULE,
};
MODULE_ALIAS_NET_CLS("fw");

static int __init init_fw(void)
{
        return register_tcf_proto_ops(&cls_fw_ops);
}

static void __exit exit_fw(void)
{
        unregister_tcf_proto_ops(&cls_fw_ops);
}

module_init(init_fw)
module_exit(exit_fw)
MODULE_DESCRIPTION("SKB mark based TC classifier");
MODULE_LICENSE("GPL");