// SPDX-License-Identifier: GPL-2.0+
/* net/sched/act_ctinfo.c  netfilter ctinfo connmark actions
 *
 * Copyright (c) 2019 Kevin Darbyshire-Bryant <ldir@darbyshire-bryant.me.uk>
 */

#include <linux/module.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/skbuff.h>
#include <linux/rtnetlink.h>
#include <linux/pkt_cls.h>
#include <linux/ip.h>
#include <linux/ipv6.h>
#include <net/netlink.h>
#include <net/pkt_sched.h>
#include <net/act_api.h>
#include <net/pkt_cls.h>
#include <net/inet_ecn.h>
#include <uapi/linux/tc_act/tc_ctinfo.h>
#include <net/tc_act/tc_ctinfo.h>
#include <net/tc_wrapper.h>

#include <net/netfilter/nf_conntrack.h>
#include <net/netfilter/nf_conntrack_core.h>
#include <net/netfilter/nf_conntrack_ecache.h>
#include <net/netfilter/nf_conntrack_zones.h>

static struct tc_action_ops act_ctinfo_ops;

static void tcf_ctinfo_dscp_set(struct nf_conn *ct, struct tcf_ctinfo *ca,
                                struct tcf_ctinfo_params *cp,
                                struct sk_buff *skb, int wlen, int proto)
{
        u8 dscp, newdscp;

        newdscp = (((READ_ONCE(ct->mark) & cp->dscpmask) >> cp->dscpmaskshift) << 2) &
                     ~INET_ECN_MASK;

        switch (proto) {
        case NFPROTO_IPV4:
                dscp = ipv4_get_dsfield(ip_hdr(skb)) & ~INET_ECN_MASK;
                if (dscp != newdscp) {
                        if (likely(!skb_try_make_writable(skb, wlen))) {
                                ipv4_change_dsfield(ip_hdr(skb),
                                                    INET_ECN_MASK,
                                                    newdscp);
                                atomic64_inc(&ca->stats_dscp_set);
                        } else {
                                atomic64_inc(&ca->stats_dscp_error);
                        }
                }
                break;
        case NFPROTO_IPV6:
                dscp = ipv6_get_dsfield(ipv6_hdr(skb)) & ~INET_ECN_MASK;
                if (dscp != newdscp) {
                        if (likely(!skb_try_make_writable(skb, wlen))) {
                                ipv6_change_dsfield(ipv6_hdr(skb),
                                                    INET_ECN_MASK,
                                                    newdscp);
                                atomic64_inc(&ca->stats_dscp_set);
                        } else {
                                atomic64_inc(&ca->stats_dscp_error);
                        }
                }
                break;
        default:
                break;
        }
}

static void tcf_ctinfo_cpmark_set(struct nf_conn *ct, struct tcf_ctinfo *ca,
                                  struct tcf_ctinfo_params *cp,
                                  struct sk_buff *skb)
{
        atomic64_inc(&ca->stats_cpmark_set);
        skb->mark = READ_ONCE(ct->mark) & cp->cpmarkmask;
}

TC_INDIRECT_SCOPE int tcf_ctinfo_act(struct sk_buff *skb,
                                     const struct tc_action *a,
                                     struct tcf_result *res)
{
        const struct nf_conntrack_tuple_hash *thash = NULL;
        struct tcf_ctinfo *ca = to_ctinfo(a);
        struct nf_conntrack_tuple tuple;
        struct nf_conntrack_zone zone;
        enum ip_conntrack_info ctinfo;
        struct tcf_ctinfo_params *cp;
        struct nf_conn *ct;
        int proto, wlen;

        cp = rcu_dereference_bh(ca->params);

        tcf_lastuse_update(&ca->tcf_tm);
        tcf_action_update_bstats(&ca->common, skb);

        wlen = skb_network_offset(skb);
        switch (skb_protocol(skb, true)) {
        case htons(ETH_P_IP):
                wlen += sizeof(struct iphdr);
                if (!pskb_may_pull(skb, wlen))
                        goto out;

                proto = NFPROTO_IPV4;
                break;
        case htons(ETH_P_IPV6):
                wlen += sizeof(struct ipv6hdr);
                if (!pskb_may_pull(skb, wlen))
                        goto out;

                proto = NFPROTO_IPV6;
                break;
        default:
                goto out;
        }

        ct = nf_ct_get(skb, &ctinfo);
        if (!ct) { /* look harder, usually ingress */
                if (!nf_ct_get_tuplepr(skb, skb_network_offset(skb),
                                       proto, cp->net, &tuple))
                        goto out;
                zone.id = cp->zone;
                zone.dir = NF_CT_DEFAULT_ZONE_DIR;

                thash = nf_conntrack_find_get(cp->net, &zone, &tuple);
                if (!thash)
                        goto out;

                ct = nf_ct_tuplehash_to_ctrack(thash);
        }

        if (cp->mode & CTINFO_MODE_DSCP)
                if (!cp->dscpstatemask || (READ_ONCE(ct->mark) & cp->dscpstatemask))
                        tcf_ctinfo_dscp_set(ct, ca, cp, skb, wlen, proto);

        if (cp->mode & CTINFO_MODE_CPMARK)
                tcf_ctinfo_cpmark_set(ct, ca, cp, skb);

        if (thash)
                nf_ct_put(ct);
out:
        return cp->action;
}

static const struct nla_policy ctinfo_policy[TCA_CTINFO_MAX + 1] = {
        [TCA_CTINFO_ACT]                  =
                NLA_POLICY_EXACT_LEN(sizeof(struct tc_ctinfo)),
        [TCA_CTINFO_ZONE]                 = { .type = NLA_U16 },
        [TCA_CTINFO_PARMS_DSCP_MASK]      = { .type = NLA_U32 },
        [TCA_CTINFO_PARMS_DSCP_STATEMASK] = { .type = NLA_U32 },
        [TCA_CTINFO_PARMS_CPMARK_MASK]    = { .type = NLA_U32 },
};

static int tcf_ctinfo_init(struct net *net, struct nlattr *nla,
                           struct nlattr *est, struct tc_action **a,
                           struct tcf_proto *tp, u32 flags,
                           struct netlink_ext_ack *extack)
{
        struct tc_action_net *tn = net_generic(net, act_ctinfo_ops.net_id);
        bool bind = flags & TCA_ACT_FLAGS_BIND;
        u32 dscpmask = 0, dscpstatemask, index;
        struct nlattr *tb[TCA_CTINFO_MAX + 1];
        struct tcf_ctinfo_params *cp_new;
        struct tcf_chain *goto_ch = NULL;
        struct tc_ctinfo *actparm;
        struct tcf_ctinfo *ci;
        u8 dscpmaskshift;
        int ret = 0, err;

        if (!nla) {
                NL_SET_ERR_MSG_MOD(extack, "ctinfo requires attributes to be passed");
                return -EINVAL;
        }

        err = nla_parse_nested(tb, TCA_CTINFO_MAX, nla, ctinfo_policy, extack);
        if (err < 0)
                return err;

        if (!tb[TCA_CTINFO_ACT]) {
                NL_SET_ERR_MSG_MOD(extack,
                                   "Missing required TCA_CTINFO_ACT attribute");
                return -EINVAL;
        }
        actparm = nla_data(tb[TCA_CTINFO_ACT]);

        /* do some basic validation here before dynamically allocating things */
        /* that we would otherwise have to clean up.                          */
        if (tb[TCA_CTINFO_PARMS_DSCP_MASK]) {
                dscpmask = nla_get_u32(tb[TCA_CTINFO_PARMS_DSCP_MASK]);
                /* need contiguous 6 bit mask */
                dscpmaskshift = dscpmask ? __ffs(dscpmask) : 0;
                if ((~0 & (dscpmask >> dscpmaskshift)) != 0x3f) {
                        NL_SET_ERR_MSG_ATTR(extack,
                                            tb[TCA_CTINFO_PARMS_DSCP_MASK],
                                            "dscp mask must be 6 contiguous bits");
                        return -EINVAL;
                }
                dscpstatemask =
                        nla_get_u32_default(tb[TCA_CTINFO_PARMS_DSCP_STATEMASK],
                                            0);
                /* mask & statemask must not overlap */
                if (dscpmask & dscpstatemask) {
                        NL_SET_ERR_MSG_ATTR(extack,
                                            tb[TCA_CTINFO_PARMS_DSCP_STATEMASK],
                                            "dscp statemask must not overlap dscp mask");
                        return -EINVAL;
                }
        }

        /* done the validation:now to the actual action allocation */
        index = actparm->index;
        err = tcf_idr_check_alloc(tn, &index, a, bind);
        if (!err) {
                ret = tcf_idr_create_from_flags(tn, index, est, a,
                                                &act_ctinfo_ops, bind, flags);
                if (ret) {
                        tcf_idr_cleanup(tn, index);
                        return ret;
                }
                ret = ACT_P_CREATED;
        } else if (err > 0) {
                if (bind) /* don't override defaults */
                        return ACT_P_BOUND;
                if (!(flags & TCA_ACT_FLAGS_REPLACE)) {
                        tcf_idr_release(*a, bind);
                        return -EEXIST;
                }
        } else {
                return err;
        }

        err = tcf_action_check_ctrlact(actparm->action, tp, &goto_ch, extack);
        if (err < 0)
                goto release_idr;

        ci = to_ctinfo(*a);

        cp_new = kzalloc_obj(*cp_new);
        if (unlikely(!cp_new)) {
                err = -ENOMEM;
                goto put_chain;
        }

        cp_new->net = net;
        cp_new->zone = nla_get_u16_default(tb[TCA_CTINFO_ZONE], 0);
        if (dscpmask) {
                cp_new->dscpmask = dscpmask;
                cp_new->dscpmaskshift = dscpmaskshift;
                cp_new->dscpstatemask = dscpstatemask;
                cp_new->mode |= CTINFO_MODE_DSCP;
        }

        if (tb[TCA_CTINFO_PARMS_CPMARK_MASK]) {
                cp_new->cpmarkmask =
                                nla_get_u32(tb[TCA_CTINFO_PARMS_CPMARK_MASK]);
                cp_new->mode |= CTINFO_MODE_CPMARK;
        }

        cp_new->action = actparm->action;

        spin_lock_bh(&ci->tcf_lock);
        goto_ch = tcf_action_set_ctrlact(*a, actparm->action, goto_ch);
        cp_new = rcu_replace_pointer(ci->params, cp_new,
                                     lockdep_is_held(&ci->tcf_lock));
        spin_unlock_bh(&ci->tcf_lock);

        if (goto_ch)
                tcf_chain_put_by_act(goto_ch);
        if (cp_new)
                kfree_rcu(cp_new, rcu);

        return ret;

put_chain:
        if (goto_ch)
                tcf_chain_put_by_act(goto_ch);
release_idr:
        tcf_idr_release(*a, bind);
        return err;
}

static int tcf_ctinfo_dump(struct sk_buff *skb, struct tc_action *a,
                           int bind, int ref)
{
        const struct tcf_ctinfo *ci = to_ctinfo(a);
        unsigned char *b = skb_tail_pointer(skb);
        const struct tcf_ctinfo_params *cp;
        struct tc_ctinfo opt = {
                .index   = ci->tcf_index,
                .refcnt  = refcount_read(&ci->tcf_refcnt) - ref,
                .bindcnt = atomic_read(&ci->tcf_bindcnt) - bind,
        };
        struct tcf_t t;

        rcu_read_lock();
        cp = rcu_dereference(ci->params);

        tcf_tm_dump(&t, &ci->tcf_tm);
        if (nla_put_64bit(skb, TCA_CTINFO_TM, sizeof(t), &t, TCA_CTINFO_PAD))
                goto nla_put_failure;

        opt.action = cp->action;
        if (nla_put(skb, TCA_CTINFO_ACT, sizeof(opt), &opt))
                goto nla_put_failure;

        if (nla_put_u16(skb, TCA_CTINFO_ZONE, cp->zone))
                goto nla_put_failure;

        if (cp->mode & CTINFO_MODE_DSCP) {
                if (nla_put_u32(skb, TCA_CTINFO_PARMS_DSCP_MASK,
                                cp->dscpmask))
                        goto nla_put_failure;
                if (nla_put_u32(skb, TCA_CTINFO_PARMS_DSCP_STATEMASK,
                                cp->dscpstatemask))
                        goto nla_put_failure;
        }

        if (cp->mode & CTINFO_MODE_CPMARK) {
                if (nla_put_u32(skb, TCA_CTINFO_PARMS_CPMARK_MASK,
                                cp->cpmarkmask))
                        goto nla_put_failure;
        }

        if (nla_put_u64_64bit(skb, TCA_CTINFO_STATS_DSCP_SET,
                              atomic64_read(&ci->stats_dscp_set),
                              TCA_CTINFO_PAD))
                goto nla_put_failure;

        if (nla_put_u64_64bit(skb, TCA_CTINFO_STATS_DSCP_ERROR,
                              atomic64_read(&ci->stats_dscp_error),
                              TCA_CTINFO_PAD))
                goto nla_put_failure;

        if (nla_put_u64_64bit(skb, TCA_CTINFO_STATS_CPMARK_SET,
                              atomic64_read(&ci->stats_cpmark_set),
                              TCA_CTINFO_PAD))
                goto nla_put_failure;

        rcu_read_unlock();
        return skb->len;

nla_put_failure:
        rcu_read_unlock();
        nlmsg_trim(skb, b);
        return -1;
}

static void tcf_ctinfo_cleanup(struct tc_action *a)
{
        struct tcf_ctinfo *ci = to_ctinfo(a);
        struct tcf_ctinfo_params *cp;

        cp = rcu_dereference_protected(ci->params, 1);
        if (cp)
                kfree_rcu(cp, rcu);
}

static struct tc_action_ops act_ctinfo_ops = {
        .kind   = "ctinfo",
        .id     = TCA_ID_CTINFO,
        .owner  = THIS_MODULE,
        .act    = tcf_ctinfo_act,
        .dump   = tcf_ctinfo_dump,
        .init   = tcf_ctinfo_init,
        .cleanup= tcf_ctinfo_cleanup,
        .size   = sizeof(struct tcf_ctinfo),
};
MODULE_ALIAS_NET_ACT("ctinfo");

static __net_init int ctinfo_init_net(struct net *net)
{
        struct tc_action_net *tn = net_generic(net, act_ctinfo_ops.net_id);

        return tc_action_net_init(net, tn, &act_ctinfo_ops);
}

static void __net_exit ctinfo_exit_net(struct list_head *net_list)
{
        tc_action_net_exit(net_list, act_ctinfo_ops.net_id);
}

static struct pernet_operations ctinfo_net_ops = {
        .init           = ctinfo_init_net,
        .exit_batch     = ctinfo_exit_net,
        .id             = &act_ctinfo_ops.net_id,
        .size           = sizeof(struct tc_action_net),
};

static int __init ctinfo_init_module(void)
{
        return tcf_register_action(&act_ctinfo_ops, &ctinfo_net_ops);
}

static void __exit ctinfo_cleanup_module(void)
{
        tcf_unregister_action(&act_ctinfo_ops, &ctinfo_net_ops);
}

module_init(ctinfo_init_module);
module_exit(ctinfo_cleanup_module);
MODULE_AUTHOR("Kevin Darbyshire-Bryant <ldir@darbyshire-bryant.me.uk>");
MODULE_DESCRIPTION("Connection tracking mark actions");
MODULE_LICENSE("GPL");