// SPDX-License-Identifier: GPL-2.0-only

  /* net/sched/sch_dsmark.c - Differentiated Services field marker */
  
  /* Written 1998-2000 by Werner Almesberger, EPFL ICA */

  #include <linux/module.h>
  #include <linux/init.h>

  #include <linux/slab.h>

  #include <linux/types.h>
  #include <linux/string.h>
  #include <linux/errno.h>
  #include <linux/skbuff.h>

  #include <linux/rtnetlink.h>

  #include <linux/bitops.h>

  #include <net/pkt_sched.h>

  #include <net/pkt_cls.h>

  #include <net/dsfield.h>
  #include <net/inet_ecn.h>
  #include <asm/byteorder.h>

  /*
   * classid	class		marking
   * -------	-----		-------
   *   n/a	  0		n/a
   *   x:0	  1		use entry [0]
   *   ...	 ...		...
   *   x:y y>0	 y+1		use entry [y]
   *   ...	 ...		...
   * x:indices-1	indices		use entry [indices-1]
   *   ...	 ...		...
   *   x:y	 y+1		use entry [y & (indices-1)]
   *   ...	 ...		...
   * 0xffff	0x10000		use entry [indices-1]
   */
  
  
  #define NO_DEFAULT_INDEX	(1 << 16)

  struct mask_value {
  	u8			mask;
  	u8			value;
  };

  struct dsmark_qdisc_data {
  	struct Qdisc		*q;

  	struct tcf_proto __rcu	*filter_list;

  	struct tcf_block	*block;

  	struct mask_value	*mv;

  	u16			indices;

  	u8			set_tc_index;

  	u32			default_index;	/* index range is 0...0xffff */

  #define DSMARK_EMBEDDED_SZ	16
  	struct mask_value	embedded[DSMARK_EMBEDDED_SZ];

  };

  static inline int dsmark_valid_index(struct dsmark_qdisc_data *p, u16 index)
  {

  	return index <= p->indices && index > 0;

  }

  
  /* ------------------------- Class/flow operations ------------------------- */

  static int dsmark_graft(struct Qdisc *sch, unsigned long arg,

  			struct Qdisc *new, struct Qdisc **old,
  			struct netlink_ext_ack *extack)

  {

  	struct dsmark_qdisc_data *p = qdisc_priv(sch);

  	pr_debug("%s(sch %p,[qdisc %p],new %p,old %p)
  ",
  		 __func__, sch, p, new, old);

  
  	if (new == NULL) {

  		new = qdisc_create_dflt(sch->dev_queue, &pfifo_qdisc_ops,

  					sch->handle, NULL);

  		if (new == NULL)
  			new = &noop_qdisc;
  	}

  	*old = qdisc_replace(sch, new, &p->q);

  	return 0;

  }

  static struct Qdisc *dsmark_leaf(struct Qdisc *sch, unsigned long arg)
  {

  	struct dsmark_qdisc_data *p = qdisc_priv(sch);
  	return p->q;

  }

  static unsigned long dsmark_find(struct Qdisc *sch, u32 classid)

  {

  	return TC_H_MIN(classid) + 1;

  }

  static unsigned long dsmark_bind_filter(struct Qdisc *sch,

  					unsigned long parent, u32 classid)

  {

  	pr_debug("%s(sch %p,[qdisc %p],classid %x)
  ",
  		 __func__, sch, qdisc_priv(sch), classid);
  
  	return dsmark_find(sch, classid);

  }

  static void dsmark_unbind_filter(struct Qdisc *sch, unsigned long cl)

  {
  }

  static const struct nla_policy dsmark_policy[TCA_DSMARK_MAX + 1] = {
  	[TCA_DSMARK_INDICES]		= { .type = NLA_U16 },
  	[TCA_DSMARK_DEFAULT_INDEX]	= { .type = NLA_U16 },
  	[TCA_DSMARK_SET_TC_INDEX]	= { .type = NLA_FLAG },
  	[TCA_DSMARK_MASK]		= { .type = NLA_U8 },
  	[TCA_DSMARK_VALUE]		= { .type = NLA_U8 },
  };

  static int dsmark_change(struct Qdisc *sch, u32 classid, u32 parent,

  			 struct nlattr **tca, unsigned long *arg,
  			 struct netlink_ext_ack *extack)

  {

  	struct dsmark_qdisc_data *p = qdisc_priv(sch);

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

  	int err = -EINVAL;

  	pr_debug("%s(sch %p,[qdisc %p],classid %x,parent %x), arg 0x%lx
  ",
  		 __func__, sch, p, classid, parent, *arg);

  
  	if (!dsmark_valid_index(p, *arg)) {
  		err = -ENOENT;

  		goto errout;

  	}

  	if (!opt)

  		goto errout;

  	err = nla_parse_nested_deprecated(tb, TCA_DSMARK_MAX, opt,
  					  dsmark_policy, NULL);

  	if (err < 0)

  		goto errout;

  	if (tb[TCA_DSMARK_VALUE])

  		p->mv[*arg - 1].value = nla_get_u8(tb[TCA_DSMARK_VALUE]);

  	if (tb[TCA_DSMARK_MASK])

  		p->mv[*arg - 1].mask = nla_get_u8(tb[TCA_DSMARK_MASK]);

  
  	err = 0;

  errout:

  	return err;
  }

  static int dsmark_delete(struct Qdisc *sch, unsigned long arg)

  {

  	struct dsmark_qdisc_data *p = qdisc_priv(sch);

  	if (!dsmark_valid_index(p, arg))

  		return -EINVAL;

  	p->mv[arg - 1].mask = 0xff;
  	p->mv[arg - 1].value = 0;

  	return 0;
  }

  static void dsmark_walk(struct Qdisc *sch, struct qdisc_walker *walker)

  {

  	struct dsmark_qdisc_data *p = qdisc_priv(sch);

  	int i;

  	pr_debug("%s(sch %p,[qdisc %p],walker %p)
  ",
  		 __func__, sch, p, walker);

  	if (walker->stop)
  		return;

  	for (i = 0; i < p->indices; i++) {

  		if (p->mv[i].mask == 0xff && !p->mv[i].value)

  			goto ignore;

  		if (walker->count >= walker->skip) {

  			if (walker->fn(sch, i + 1, walker) < 0) {

  				walker->stop = 1;
  				break;
  			}
  		}

  ignore:

  		walker->count++;

  	}

  }

  static struct tcf_block *dsmark_tcf_block(struct Qdisc *sch, unsigned long cl,
  					  struct netlink_ext_ack *extack)

  {

  	struct dsmark_qdisc_data *p = qdisc_priv(sch);

  
  	return p->block;

  }

  /* --------------------------- Qdisc operations ---------------------------- */

  static int dsmark_enqueue(struct sk_buff *skb, struct Qdisc *sch,
  			  struct sk_buff **to_free)

  {

  	unsigned int len = qdisc_pkt_len(skb);

  	struct dsmark_qdisc_data *p = qdisc_priv(sch);

  	int err;

  	pr_debug("%s(skb %p,sch %p,[qdisc %p])
  ", __func__, skb, sch, p);

  	if (p->set_tc_index) {

  		int 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) ||
  			    skb_try_make_writable(skb, wlen))

  				goto drop;

  			skb->tc_index = ipv4_get_dsfield(ip_hdr(skb))
  				& ~INET_ECN_MASK;
  			break;

  		case htons(ETH_P_IPV6):

  			wlen += sizeof(struct ipv6hdr);
  			if (!pskb_may_pull(skb, wlen) ||
  			    skb_try_make_writable(skb, wlen))

  				goto drop;

  			skb->tc_index = ipv6_get_dsfield(ipv6_hdr(skb))
  				& ~INET_ECN_MASK;
  			break;
  		default:
  			skb->tc_index = 0;
  			break;

  		}

  	}

  
  	if (TC_H_MAJ(skb->priority) == sch->handle)

  		skb->tc_index = TC_H_MIN(skb->priority);

  	else {
  		struct tcf_result res;

  		struct tcf_proto *fl = rcu_dereference_bh(p->filter_list);

  		int result = tcf_classify(skb, fl, &res, false);

  		pr_debug("result %d class 0x%04x
  ", result, res.classid);

  		switch (result) {

  #ifdef CONFIG_NET_CLS_ACT
  		case TC_ACT_QUEUED:
  		case TC_ACT_STOLEN:

  		case TC_ACT_TRAP:

  			__qdisc_drop(skb, to_free);

  			return NET_XMIT_SUCCESS | __NET_XMIT_STOLEN;

  		case TC_ACT_SHOT:

  			goto drop;

  #endif

  		case TC_ACT_OK:

  			skb->tc_index = TC_H_MIN(res.classid);
  			break;

  		default:
  			if (p->default_index != NO_DEFAULT_INDEX)
  				skb->tc_index = p->default_index;
  			break;

  		}

  	}

  	err = qdisc_enqueue(skb, p->q, to_free);

  	if (err != NET_XMIT_SUCCESS) {

  		if (net_xmit_drop_count(err))

  			qdisc_qstats_drop(sch);

  		return err;

  	}

  	sch->qstats.backlog += len;

  	sch->q.qlen++;

  	return NET_XMIT_SUCCESS;

  
  drop:

  	qdisc_drop(skb, sch, to_free);

  	return NET_XMIT_SUCCESS | __NET_XMIT_BYPASS;

  }

  
  static struct sk_buff *dsmark_dequeue(struct Qdisc *sch)
  {

  	struct dsmark_qdisc_data *p = qdisc_priv(sch);

  	struct sk_buff *skb;

  	u32 index;

  	pr_debug("%s(sch %p,[qdisc %p])
  ", __func__, sch, p);

  	skb = qdisc_dequeue_peeked(p->q);

  	if (skb == NULL)

  		return NULL;

  	qdisc_bstats_update(sch, skb);

  	qdisc_qstats_backlog_dec(sch, skb);

  	sch->q.qlen--;

  
  	index = skb->tc_index & (p->indices - 1);

  	pr_debug("index %d->%d
  ", skb->tc_index, index);

  	switch (skb_protocol(skb, true)) {

  	case htons(ETH_P_IP):

  		ipv4_change_dsfield(ip_hdr(skb), p->mv[index].mask,
  				    p->mv[index].value);

  			break;

  	case htons(ETH_P_IPV6):

  		ipv6_change_dsfield(ipv6_hdr(skb), p->mv[index].mask,
  				    p->mv[index].value);

  			break;

  	default:
  		/*
  		 * Only complain if a change was actually attempted.
  		 * This way, we can send non-IP traffic through dsmark
  		 * and don't need yet another qdisc as a bypass.
  		 */

  		if (p->mv[index].mask != 0xff || p->mv[index].value)

  			pr_warn("%s: unsupported protocol %d
  ",

  				__func__, ntohs(skb_protocol(skb, true)));

  		break;

  	}

  	return skb;
  }

  static struct sk_buff *dsmark_peek(struct Qdisc *sch)
  {
  	struct dsmark_qdisc_data *p = qdisc_priv(sch);

  	pr_debug("%s(sch %p,[qdisc %p])
  ", __func__, sch, p);

  
  	return p->q->ops->peek(p->q);
  }

  static int dsmark_init(struct Qdisc *sch, struct nlattr *opt,
  		       struct netlink_ext_ack *extack)

  {

  	struct dsmark_qdisc_data *p = qdisc_priv(sch);

  	struct nlattr *tb[TCA_DSMARK_MAX + 1];

  	int err = -EINVAL;

  	u32 default_index = NO_DEFAULT_INDEX;
  	u16 indices;

  	int i;

  	pr_debug("%s(sch %p,[qdisc %p],opt %p)
  ", __func__, sch, p, opt);

  	if (!opt)
  		goto errout;

  	err = tcf_block_get(&p->block, &p->filter_list, sch, extack);

  	if (err)
  		return err;

  	err = nla_parse_nested_deprecated(tb, TCA_DSMARK_MAX, opt,
  					  dsmark_policy, NULL);

  	if (err < 0)

  		goto errout;

  	err = -EINVAL;

  	if (!tb[TCA_DSMARK_INDICES])
  		goto errout;

  	indices = nla_get_u16(tb[TCA_DSMARK_INDICES]);

  
  	if (hweight32(indices) != 1)

  		goto errout;

  	if (tb[TCA_DSMARK_DEFAULT_INDEX])

  		default_index = nla_get_u16(tb[TCA_DSMARK_DEFAULT_INDEX]);

  	if (indices <= DSMARK_EMBEDDED_SZ)
  		p->mv = p->embedded;
  	else
  		p->mv = kmalloc_array(indices, sizeof(*p->mv), GFP_KERNEL);
  	if (!p->mv) {

  		err = -ENOMEM;
  		goto errout;

  	}

  	for (i = 0; i < indices; i++) {
  		p->mv[i].mask = 0xff;
  		p->mv[i].value = 0;
  	}

  	p->indices = indices;
  	p->default_index = default_index;

  	p->set_tc_index = nla_get_flag(tb[TCA_DSMARK_SET_TC_INDEX]);

  	p->q = qdisc_create_dflt(sch->dev_queue, &pfifo_qdisc_ops, sch->handle,
  				 NULL);

  	if (p->q == NULL)

  		p->q = &noop_qdisc;

  	else
  		qdisc_hash_add(p->q, true);

  	pr_debug("%s: qdisc %p
  ", __func__, p->q);

  
  	err = 0;
  errout:

  	return err;

  }

  static void dsmark_reset(struct Qdisc *sch)
  {

  	struct dsmark_qdisc_data *p = qdisc_priv(sch);

  	pr_debug("%s(sch %p,[qdisc %p])
  ", __func__, sch, p);

  	qdisc_reset(p->q);

  	sch->qstats.backlog = 0;

  	sch->q.qlen = 0;
  }

  static void dsmark_destroy(struct Qdisc *sch)
  {

  	struct dsmark_qdisc_data *p = qdisc_priv(sch);

  	pr_debug("%s(sch %p,[qdisc %p])
  ", __func__, sch, p);

  	tcf_block_put(p->block);

  	qdisc_put(p->q);

  	if (p->mv != p->embedded)
  		kfree(p->mv);

  }

  static int dsmark_dump_class(struct Qdisc *sch, unsigned long cl,

  			     struct sk_buff *skb, struct tcmsg *tcm)

  {

  	struct dsmark_qdisc_data *p = qdisc_priv(sch);

  	struct nlattr *opts = NULL;

  	pr_debug("%s(sch %p,[qdisc %p],class %ld
  ", __func__, sch, p, cl);

  
  	if (!dsmark_valid_index(p, cl))

  		return -EINVAL;

  	tcm->tcm_handle = TC_H_MAKE(TC_H_MAJ(sch->handle), cl - 1);

  	tcm->tcm_info = p->q->handle;

  	opts = nla_nest_start_noflag(skb, TCA_OPTIONS);

  	if (opts == NULL)
  		goto nla_put_failure;

  	if (nla_put_u8(skb, TCA_DSMARK_MASK, p->mv[cl - 1].mask) ||
  	    nla_put_u8(skb, TCA_DSMARK_VALUE, p->mv[cl - 1].value))

  		goto nla_put_failure;

  	return nla_nest_end(skb, opts);

  nla_put_failure:

  	nla_nest_cancel(skb, opts);
  	return -EMSGSIZE;

  }
  
  static int dsmark_dump(struct Qdisc *sch, struct sk_buff *skb)
  {

  	struct dsmark_qdisc_data *p = qdisc_priv(sch);

  	struct nlattr *opts = NULL;

  	opts = nla_nest_start_noflag(skb, TCA_OPTIONS);

  	if (opts == NULL)
  		goto nla_put_failure;

  	if (nla_put_u16(skb, TCA_DSMARK_INDICES, p->indices))
  		goto nla_put_failure;

  	if (p->default_index != NO_DEFAULT_INDEX &&
  	    nla_put_u16(skb, TCA_DSMARK_DEFAULT_INDEX, p->default_index))
  		goto nla_put_failure;

  	if (p->set_tc_index &&
  	    nla_put_flag(skb, TCA_DSMARK_SET_TC_INDEX))
  		goto nla_put_failure;

  	return nla_nest_end(skb, opts);

  nla_put_failure:

  	nla_nest_cancel(skb, opts);
  	return -EMSGSIZE;

  }

  static const struct Qdisc_class_ops dsmark_class_ops = {

  	.graft		=	dsmark_graft,
  	.leaf		=	dsmark_leaf,

  	.find		=	dsmark_find,

  	.change		=	dsmark_change,
  	.delete		=	dsmark_delete,
  	.walk		=	dsmark_walk,

  	.tcf_block	=	dsmark_tcf_block,

  	.bind_tcf	=	dsmark_bind_filter,

  	.unbind_tcf	=	dsmark_unbind_filter,

  	.dump		=	dsmark_dump_class,
  };

  static struct Qdisc_ops dsmark_qdisc_ops __read_mostly = {

  	.next		=	NULL,
  	.cl_ops		=	&dsmark_class_ops,
  	.id		=	"dsmark",
  	.priv_size	=	sizeof(struct dsmark_qdisc_data),
  	.enqueue	=	dsmark_enqueue,
  	.dequeue	=	dsmark_dequeue,

  	.peek		=	dsmark_peek,

  	.init		=	dsmark_init,
  	.reset		=	dsmark_reset,
  	.destroy	=	dsmark_destroy,
  	.change		=	NULL,
  	.dump		=	dsmark_dump,
  	.owner		=	THIS_MODULE,
  };
  
  static int __init dsmark_module_init(void)
  {
  	return register_qdisc(&dsmark_qdisc_ops);
  }

  static void __exit dsmark_module_exit(void)

  {
  	unregister_qdisc(&dsmark_qdisc_ops);
  }

  module_init(dsmark_module_init)
  module_exit(dsmark_module_exit)

  MODULE_LICENSE("GPL");