// 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 <uapi/linux/tc_act/tc_ctinfo.h>
  #include <net/tc_act/tc_ctinfo.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 unsigned int ctinfo_net_id;
  
  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 = (((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);
  				ca->stats_dscp_set++;
  			} else {
  				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);
  				ca->stats_dscp_set++;
  			} else {
  				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)
  {
  	ca->stats_cpmark_set++;
  	skb->mark = ct->mark & cp->cpmarkmask;
  }
  
  static 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;
  	int action;
  
  	cp = rcu_dereference_bh(ca->params);
  
  	tcf_lastuse_update(&ca->tcf_tm);
  	bstats_update(&ca->tcf_bstats, skb);
  	action = READ_ONCE(ca->tcf_action);
  
  	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 || (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 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,
  			   int ovr, int bind, bool rtnl_held,

  			   struct tcf_proto *tp, u32 flags,

  			   struct netlink_ext_ack *extack)
  {
  	struct tc_action_net *tn = net_generic(net, ctinfo_net_id);

  	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 = tb[TCA_CTINFO_PARMS_DSCP_STATEMASK] ?
  			nla_get_u32(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(tn, index, est, a,

  				     &act_ctinfo_ops, bind, false, 0);

  		if (ret) {

  			tcf_idr_cleanup(tn, index);

  			return ret;
  		}

  		ret = ACT_P_CREATED;

  	} else if (err > 0) {
  		if (bind) /* don't override defaults */
  			return 0;
  		if (!ovr) {
  			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(sizeof(*cp_new), GFP_KERNEL);
  	if (unlikely(!cp_new)) {
  		err = -ENOMEM;
  		goto put_chain;
  	}
  
  	cp_new->net = net;
  	cp_new->zone = tb[TCA_CTINFO_ZONE] ?
  			nla_get_u16(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;

  	}
  
  	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)
  {
  	struct tcf_ctinfo *ci = to_ctinfo(a);
  	struct tc_ctinfo opt = {
  		.index   = ci->tcf_index,
  		.refcnt  = refcount_read(&ci->tcf_refcnt) - ref,
  		.bindcnt = atomic_read(&ci->tcf_bindcnt) - bind,
  	};
  	unsigned char *b = skb_tail_pointer(skb);
  	struct tcf_ctinfo_params *cp;
  	struct tcf_t t;
  
  	spin_lock_bh(&ci->tcf_lock);
  	cp = rcu_dereference_protected(ci->params,
  				       lockdep_is_held(&ci->tcf_lock));
  
  	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 = ci->tcf_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,
  			      ci->stats_dscp_set, TCA_CTINFO_PAD))
  		goto nla_put_failure;
  
  	if (nla_put_u64_64bit(skb, TCA_CTINFO_STATS_DSCP_ERROR,
  			      ci->stats_dscp_error, TCA_CTINFO_PAD))
  		goto nla_put_failure;
  
  	if (nla_put_u64_64bit(skb, TCA_CTINFO_STATS_CPMARK_SET,
  			      ci->stats_cpmark_set, TCA_CTINFO_PAD))
  		goto nla_put_failure;
  
  	spin_unlock_bh(&ci->tcf_lock);
  	return skb->len;
  
  nla_put_failure:
  	spin_unlock_bh(&ci->tcf_lock);
  	nlmsg_trim(skb, b);
  	return -1;
  }
  
  static int tcf_ctinfo_walker(struct net *net, struct sk_buff *skb,
  			     struct netlink_callback *cb, int type,
  			     const struct tc_action_ops *ops,
  			     struct netlink_ext_ack *extack)
  {
  	struct tc_action_net *tn = net_generic(net, ctinfo_net_id);
  
  	return tcf_generic_walker(tn, skb, cb, type, ops, extack);
  }
  
  static int tcf_ctinfo_search(struct net *net, struct tc_action **a, u32 index)
  {
  	struct tc_action_net *tn = net_generic(net, ctinfo_net_id);
  
  	return tcf_idr_search(tn, a, index);
  }

  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,

  	.walk	= tcf_ctinfo_walker,
  	.lookup	= tcf_ctinfo_search,
  	.size	= sizeof(struct tcf_ctinfo),
  };
  
  static __net_init int ctinfo_init_net(struct net *net)
  {
  	struct tc_action_net *tn = net_generic(net, ctinfo_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, ctinfo_net_id);
  }
  
  static struct pernet_operations ctinfo_net_ops = {
  	.init		= ctinfo_init_net,
  	.exit_batch	= ctinfo_exit_net,
  	.id		= &ctinfo_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");