// SPDX-License-Identifier: GPL-2.0-or-later

  /*
   * net/sched/cls_route.c	ROUTE4 classifier.
   *

   * Authors:	Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
   */
  
  #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/dst.h>
  #include <net/route.h>
  #include <net/netlink.h>

  #include <net/act_api.h>
  #include <net/pkt_cls.h>
  
  /*

   * 1. For now we assume that route tags < 256.
   *    It allows to use direct table lookups, instead of hash tables.
   * 2. For now we assume that "from TAG" and "fromdev DEV" statements
   *    are mutually  exclusive.
   * 3. "to TAG from ANY" has higher priority, than "to ANY from XXX"

   */

  struct route4_fastmap {

  	struct route4_filter		*filter;
  	u32				id;
  	int				iif;

  };

  struct route4_head {

  	struct route4_fastmap		fastmap[16];
  	struct route4_bucket __rcu	*table[256 + 1];
  	struct rcu_head			rcu;

  };

  struct route4_bucket {

  	/* 16 FROM buckets + 16 IIF buckets + 1 wildcard bucket */

  	struct route4_filter __rcu	*ht[16 + 16 + 1];
  	struct rcu_head			rcu;

  };

  struct route4_filter {

  	struct route4_filter __rcu	*next;

  	u32			id;
  	int			iif;
  
  	struct tcf_result	res;
  	struct tcf_exts		exts;
  	u32			handle;
  	struct route4_bucket	*bkt;

  	struct tcf_proto	*tp;

  	struct rcu_work		rwork;

  };

  #define ROUTE4_FAILURE ((struct route4_filter *)(-1L))

  static inline int route4_fastmap_hash(u32 id, int iif)

  {

  	return id & 0xF;

  }

  static DEFINE_SPINLOCK(fastmap_lock);

  static void

  route4_reset_fastmap(struct route4_head *head)

  {

  	spin_lock_bh(&fastmap_lock);

  	memset(head->fastmap, 0, sizeof(head->fastmap));

  	spin_unlock_bh(&fastmap_lock);

  }

  static void

  route4_set_fastmap(struct route4_head *head, u32 id, int iif,
  		   struct route4_filter *f)
  {
  	int h = route4_fastmap_hash(id, iif);

  	/* fastmap updates must look atomic to aling id, iff, filter */
  	spin_lock_bh(&fastmap_lock);

  	head->fastmap[h].id = id;
  	head->fastmap[h].iif = iif;
  	head->fastmap[h].filter = f;

  	spin_unlock_bh(&fastmap_lock);

  }

  static inline int route4_hash_to(u32 id)

  {

  	return id & 0xFF;

  }

  static inline int route4_hash_from(u32 id)

  {

  	return (id >> 16) & 0xF;

  }

  static inline int route4_hash_iif(int iif)

  {

  	return 16 + ((iif >> 16) & 0xF);

  }

  static inline int route4_hash_wild(void)

  {
  	return 32;
  }
  
  #define ROUTE4_APPLY_RESULT()					\
  {								\
  	*res = f->res;						\

  	if (tcf_exts_has_actions(&f->exts)) {			\

  		int r = tcf_exts_exec(skb, &f->exts, res);	\
  		if (r < 0) {					\
  			dont_cache = 1;				\
  			continue;				\
  		}						\
  		return r;					\
  	} else if (!dont_cache)					\
  		route4_set_fastmap(head, id, iif, f);		\
  	return 0;						\
  }

  static int route4_classify(struct sk_buff *skb, const struct tcf_proto *tp,

  			   struct tcf_result *res)
  {

  	struct route4_head *head = rcu_dereference_bh(tp->root);

  	struct dst_entry *dst;
  	struct route4_bucket *b;
  	struct route4_filter *f;
  	u32 id, h;
  	int iif, dont_cache = 0;

  	dst = skb_dst(skb);
  	if (!dst)

  		goto failure;
  
  	id = dst->tclassid;

  	iif = inet_iif(skb);

  
  	h = route4_fastmap_hash(id, iif);

  
  	spin_lock(&fastmap_lock);

  	if (id == head->fastmap[h].id &&
  	    iif == head->fastmap[h].iif &&
  	    (f = head->fastmap[h].filter) != NULL) {

  		if (f == ROUTE4_FAILURE) {
  			spin_unlock(&fastmap_lock);

  			goto failure;

  		}

  
  		*res = f->res;

  		spin_unlock(&fastmap_lock);

  		return 0;
  	}

  	spin_unlock(&fastmap_lock);

  
  	h = route4_hash_to(id);
  
  restart:

  	b = rcu_dereference_bh(head->table[h]);

  	if (b) {

  		for (f = rcu_dereference_bh(b->ht[route4_hash_from(id)]);
  		     f;
  		     f = rcu_dereference_bh(f->next))

  			if (f->id == id)
  				ROUTE4_APPLY_RESULT();

  		for (f = rcu_dereference_bh(b->ht[route4_hash_iif(iif)]);
  		     f;
  		     f = rcu_dereference_bh(f->next))

  			if (f->iif == iif)
  				ROUTE4_APPLY_RESULT();

  		for (f = rcu_dereference_bh(b->ht[route4_hash_wild()]);
  		     f;
  		     f = rcu_dereference_bh(f->next))

  			ROUTE4_APPLY_RESULT();

  	}
  	if (h < 256) {
  		h = 256;
  		id &= ~0xFFFF;
  		goto restart;
  	}
  
  	if (!dont_cache)
  		route4_set_fastmap(head, id, iif, ROUTE4_FAILURE);
  failure:
  	return -1;

  }
  
  static inline u32 to_hash(u32 id)
  {

  	u32 h = id & 0xFF;
  
  	if (id & 0x8000)

  		h += 256;
  	return h;
  }
  
  static inline u32 from_hash(u32 id)
  {
  	id &= 0xFFFF;
  	if (id == 0xFFFF)
  		return 32;
  	if (!(id & 0x8000)) {
  		if (id > 255)
  			return 256;

  		return id & 0xF;

  	}

  	return 16 + (id & 0xF);

  }

  static void *route4_get(struct tcf_proto *tp, u32 handle)

  {

  	struct route4_head *head = rtnl_dereference(tp->root);

  	struct route4_bucket *b;
  	struct route4_filter *f;

  	unsigned int h1, h2;

  	h1 = to_hash(handle);
  	if (h1 > 256)

  		return NULL;

  	h2 = from_hash(handle >> 16);

  	if (h2 > 32)

  		return NULL;

  	b = rtnl_dereference(head->table[h1]);

  	if (b) {

  		for (f = rtnl_dereference(b->ht[h2]);
  		     f;
  		     f = rtnl_dereference(f->next))

  			if (f->handle == handle)

  				return f;

  	}

  	return NULL;

  }

  static int route4_init(struct tcf_proto *tp)
  {

  	struct route4_head *head;
  
  	head = kzalloc(sizeof(struct route4_head), GFP_KERNEL);
  	if (head == NULL)
  		return -ENOBUFS;
  
  	rcu_assign_pointer(tp->root, head);

  	return 0;
  }

  static void __route4_delete_filter(struct route4_filter *f)
  {
  	tcf_exts_destroy(&f->exts);
  	tcf_exts_put_net(&f->exts);
  	kfree(f);
  }

  static void route4_delete_filter_work(struct work_struct *work)

  {

  	struct route4_filter *f = container_of(to_rcu_work(work),
  					       struct route4_filter,
  					       rwork);

  	rtnl_lock();

  	__route4_delete_filter(f);

  	rtnl_unlock();
  }

  static void route4_queue_work(struct route4_filter *f)

  {

  	tcf_queue_work(&f->rwork, route4_delete_filter_work);

  }

  static void route4_destroy(struct tcf_proto *tp, bool rtnl_held,
  			   struct netlink_ext_ack *extack)

  {

  	struct route4_head *head = rtnl_dereference(tp->root);

  	int h1, h2;
  
  	if (head == NULL)

  		return;

  	for (h1 = 0; h1 <= 256; h1++) {

  		struct route4_bucket *b;

  		b = rtnl_dereference(head->table[h1]);

  		if (b) {
  			for (h2 = 0; h2 <= 32; h2++) {

  				struct route4_filter *f;

  				while ((f = rtnl_dereference(b->ht[h2])) != NULL) {
  					struct route4_filter *next;
  
  					next = rtnl_dereference(f->next);
  					RCU_INIT_POINTER(b->ht[h2], next);

  					tcf_unbind_filter(tp, &f->res);

  					if (tcf_exts_get_net(&f->exts))

  						route4_queue_work(f);

  					else
  						__route4_delete_filter(f);

  				}
  			}

  			RCU_INIT_POINTER(head->table[h1], NULL);
  			kfree_rcu(b, rcu);

  		}
  	}

  	kfree_rcu(head, rcu);

  }

  static int route4_delete(struct tcf_proto *tp, void *arg, bool *last,

  			 bool rtnl_held, struct netlink_ext_ack *extack)

  {

  	struct route4_head *head = rtnl_dereference(tp->root);

  	struct route4_filter *f = arg;

  	struct route4_filter __rcu **fp;
  	struct route4_filter *nf;

  	struct route4_bucket *b;

  	unsigned int h = 0;

  	int i, h1;

  
  	if (!head || !f)
  		return -EINVAL;
  
  	h = f->handle;
  	b = f->bkt;

  	fp = &b->ht[from_hash(h >> 16)];
  	for (nf = rtnl_dereference(*fp); nf;
  	     fp = &nf->next, nf = rtnl_dereference(*fp)) {
  		if (nf == f) {
  			/* unlink it */
  			RCU_INIT_POINTER(*fp, rtnl_dereference(f->next));

  			/* Remove any fastmap lookups that might ref filter
  			 * notice we unlink'd the filter so we can't get it
  			 * back in the fastmap.
  			 */
  			route4_reset_fastmap(head);

  			/* Delete it */

  			tcf_unbind_filter(tp, &f->res);

  			tcf_exts_get_net(&f->exts);

  			tcf_queue_work(&f->rwork, route4_delete_filter_work);

  			/* Strip RTNL protected tree */
  			for (i = 0; i <= 32; i++) {
  				struct route4_filter *rt;
  
  				rt = rtnl_dereference(b->ht[i]);
  				if (rt)

  					goto out;

  			}

  
  			/* OK, session has no flows */

  			RCU_INIT_POINTER(head->table[to_hash(h)], NULL);
  			kfree_rcu(b, rcu);

  			break;
  		}
  	}

  out:
  	*last = true;
  	for (h1 = 0; h1 <= 256; h1++) {
  		if (rcu_access_pointer(head->table[h1])) {
  			*last = false;
  			break;

  		}
  	}

  	return 0;
  }

  static const struct nla_policy route4_policy[TCA_ROUTE4_MAX + 1] = {
  	[TCA_ROUTE4_CLASSID]	= { .type = NLA_U32 },
  	[TCA_ROUTE4_TO]		= { .type = NLA_U32 },
  	[TCA_ROUTE4_FROM]	= { .type = NLA_U32 },
  	[TCA_ROUTE4_IIF]	= { .type = NLA_U32 },
  };

  static int route4_set_parms(struct net *net, struct tcf_proto *tp,
  			    unsigned long base, struct route4_filter *f,
  			    u32 handle, struct route4_head *head,

  			    struct nlattr **tb, struct nlattr *est, int new,

  			    bool ovr, struct netlink_ext_ack *extack)

  {

  	u32 id = 0, to = 0, nhandle = 0x8000;
  	struct route4_filter *fp;
  	unsigned int h1;
  	struct route4_bucket *b;

  	int err;

  	err = tcf_exts_validate(net, tp, tb, est, &f->exts, ovr, true, extack);

  	if (err < 0)
  		return err;

  	if (tb[TCA_ROUTE4_TO]) {

  		if (new && handle & 0x8000)

  			return -EINVAL;

  		to = nla_get_u32(tb[TCA_ROUTE4_TO]);

  		if (to > 0xFF)

  			return -EINVAL;

  		nhandle = to;
  	}

  	if (tb[TCA_ROUTE4_FROM]) {
  		if (tb[TCA_ROUTE4_IIF])

  			return -EINVAL;

  		id = nla_get_u32(tb[TCA_ROUTE4_FROM]);

  		if (id > 0xFF)

  			return -EINVAL;

  		nhandle |= id << 16;

  	} else if (tb[TCA_ROUTE4_IIF]) {

  		id = nla_get_u32(tb[TCA_ROUTE4_IIF]);

  		if (id > 0x7FFF)

  			return -EINVAL;

  		nhandle |= (id | 0x8000) << 16;
  	} else
  		nhandle |= 0xFFFF << 16;
  
  	if (handle && new) {
  		nhandle |= handle & 0x7F00;
  		if (nhandle != handle)

  			return -EINVAL;

  	}
  
  	h1 = to_hash(nhandle);

  	b = rtnl_dereference(head->table[h1]);

  	if (!b) {

  		b = kzalloc(sizeof(struct route4_bucket), GFP_KERNEL);

  		if (b == NULL)

  			return -ENOBUFS;

  		rcu_assign_pointer(head->table[h1], b);

  	} else {
  		unsigned int h2 = from_hash(nhandle >> 16);

  		for (fp = rtnl_dereference(b->ht[h2]);
  		     fp;
  		     fp = rtnl_dereference(fp->next))

  			if (fp->handle == f->handle)

  				return -EEXIST;

  	}

  	if (tb[TCA_ROUTE4_TO])

  		f->id = to;

  	if (tb[TCA_ROUTE4_FROM])

  		f->id = to | id<<16;

  	else if (tb[TCA_ROUTE4_IIF])

  		f->iif = id;
  
  	f->handle = nhandle;
  	f->bkt = b;

  	f->tp = tp;

  	if (tb[TCA_ROUTE4_CLASSID]) {

  		f->res.classid = nla_get_u32(tb[TCA_ROUTE4_CLASSID]);

  		tcf_bind_filter(tp, &f->res, base);
  	}

  	return 0;

  }

  static int route4_change(struct net *net, struct sk_buff *in_skb,

  			 struct tcf_proto *tp, unsigned long base, u32 handle,

  			 struct nlattr **tca, void **arg, bool ovr,

  			 bool rtnl_held, struct netlink_ext_ack *extack)

  {

  	struct route4_head *head = rtnl_dereference(tp->root);
  	struct route4_filter __rcu **fp;
  	struct route4_filter *fold, *f1, *pfp, *f = NULL;

  	struct route4_bucket *b;

  	struct nlattr *opt = tca[TCA_OPTIONS];
  	struct nlattr *tb[TCA_ROUTE4_MAX + 1];

  	unsigned int h, th;

  	int err;

  	bool new = true;

  
  	if (opt == NULL)
  		return handle ? -EINVAL : 0;

  	err = nla_parse_nested_deprecated(tb, TCA_ROUTE4_MAX, opt,
  					  route4_policy, NULL);

  	if (err < 0)
  		return err;

  	fold = *arg;

  	if (fold && handle && fold->handle != handle)

  			return -EINVAL;

  	err = -ENOBUFS;

  	f = kzalloc(sizeof(struct route4_filter), GFP_KERNEL);

  	if (!f)

  		goto errout;

  	err = tcf_exts_init(&f->exts, net, TCA_ROUTE4_ACT, TCA_ROUTE4_POLICE);

  	if (err < 0)
  		goto errout;

  	if (fold) {
  		f->id = fold->id;
  		f->iif = fold->iif;
  		f->res = fold->res;
  		f->handle = fold->handle;
  
  		f->tp = fold->tp;
  		f->bkt = fold->bkt;
  		new = false;
  	}

  	err = route4_set_parms(net, tp, base, f, handle, head, tb,

  			       tca[TCA_RATE], new, ovr, extack);

  	if (err < 0)
  		goto errout;

  	h = from_hash(f->handle >> 16);

  	fp = &f->bkt->ht[h];
  	for (pfp = rtnl_dereference(*fp);
  	     (f1 = rtnl_dereference(*fp)) != NULL;
  	     fp = &f1->next)

  		if (f->handle < f1->handle)
  			break;

  	tcf_block_netif_keep_dst(tp->chain->block);

  	rcu_assign_pointer(f->next, f1);
  	rcu_assign_pointer(*fp, f);

  	if (fold && fold->handle && f->handle != fold->handle) {
  		th = to_hash(fold->handle);
  		h = from_hash(fold->handle >> 16);
  		b = rtnl_dereference(head->table[th]);

  		if (b) {

  			fp = &b->ht[h];
  			for (pfp = rtnl_dereference(*fp); pfp;
  			     fp = &pfp->next, pfp = rtnl_dereference(*fp)) {
  				if (pfp == f) {

  					*fp = f->next;
  					break;
  				}
  			}
  		}
  	}

  	route4_reset_fastmap(head);

  	*arg = f;

  	if (fold) {
  		tcf_unbind_filter(tp, &fold->res);

  		tcf_exts_get_net(&fold->exts);

  		tcf_queue_work(&fold->rwork, route4_delete_filter_work);

  	}

  	return 0;
  
  errout:

  	if (f)
  		tcf_exts_destroy(&f->exts);

  	kfree(f);

  	return err;
  }

  static void route4_walk(struct tcf_proto *tp, struct tcf_walker *arg,
  			bool rtnl_held)

  {

  	struct route4_head *head = rtnl_dereference(tp->root);

  	unsigned int h, h1;

  	if (head == NULL || arg->stop)

  		return;
  
  	for (h = 0; h <= 256; h++) {

  		struct route4_bucket *b = rtnl_dereference(head->table[h]);

  
  		if (b) {
  			for (h1 = 0; h1 <= 32; h1++) {
  				struct route4_filter *f;

  				for (f = rtnl_dereference(b->ht[h1]);
  				     f;
  				     f = rtnl_dereference(f->next)) {

  					if (arg->count < arg->skip) {
  						arg->count++;
  						continue;
  					}

  					if (arg->fn(tp, f, arg) < 0) {

  						arg->stop = 1;
  						return;
  					}
  					arg->count++;
  				}
  			}
  		}
  	}
  }

  static int route4_dump(struct net *net, struct tcf_proto *tp, void *fh,

  		       struct sk_buff *skb, struct tcmsg *t, bool rtnl_held)

  {

  	struct route4_filter *f = fh;

  	struct nlattr *nest;

  	u32 id;
  
  	if (f == NULL)
  		return skb->len;
  
  	t->tcm_handle = f->handle;

  	nest = nla_nest_start_noflag(skb, TCA_OPTIONS);

  	if (nest == NULL)
  		goto nla_put_failure;

  	if (!(f->handle & 0x8000)) {
  		id = f->id & 0xFF;

  		if (nla_put_u32(skb, TCA_ROUTE4_TO, id))
  			goto nla_put_failure;

  	}

  	if (f->handle & 0x80000000) {

  		if ((f->handle >> 16) != 0xFFFF &&
  		    nla_put_u32(skb, TCA_ROUTE4_IIF, f->iif))
  			goto nla_put_failure;

  	} else {

  		id = f->id >> 16;

  		if (nla_put_u32(skb, TCA_ROUTE4_FROM, id))
  			goto nla_put_failure;

  	}

  	if (f->res.classid &&
  	    nla_put_u32(skb, TCA_ROUTE4_CLASSID, f->res.classid))
  		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 route4_bind_class(void *fh, u32 classid, unsigned long cl, void *q,
  			      unsigned long base)

  {
  	struct route4_filter *f = fh;

  	if (f && f->res.classid == classid) {
  		if (cl)
  			__tcf_bind_filter(q, &f->res, base);
  		else
  			__tcf_unbind_filter(q, &f->res);
  	}

  }

  static struct tcf_proto_ops cls_route4_ops __read_mostly = {

  	.kind		=	"route",
  	.classify	=	route4_classify,
  	.init		=	route4_init,
  	.destroy	=	route4_destroy,
  	.get		=	route4_get,

  	.change		=	route4_change,
  	.delete		=	route4_delete,
  	.walk		=	route4_walk,
  	.dump		=	route4_dump,

  	.bind_class	=	route4_bind_class,

  	.owner		=	THIS_MODULE,
  };
  
  static int __init init_route4(void)
  {
  	return register_tcf_proto_ops(&cls_route4_ops);
  }
  
  static void __exit exit_route4(void)
  {
  	unregister_tcf_proto_ops(&cls_route4_ops);
  }
  
  module_init(init_route4)
  module_exit(exit_route4)
  MODULE_LICENSE("GPL");