text: // SPDX-License-Identifier: GPL-2.0-or-later
  /*
   * net/sched/act_pedit.c	Generic packet editor
   *
   * Authors:	Jamal Hadi Salim (2002-4)
   */
  
  #include <linux/types.h>
  #include <linux/kernel.h>
  #include <linux/string.h>
  #include <linux/errno.h>
  #include <linux/skbuff.h>
  #include <linux/rtnetlink.h>
  #include <linux/module.h>
  #include <linux/init.h>
  #include <linux/slab.h>
  #include <net/netlink.h>
  #include <net/pkt_sched.h>
  #include <linux/tc_act/tc_pedit.h>
  #include <net/tc_act/tc_pedit.h>
  #include <uapi/linux/tc_act/tc_pedit.h>
  #include <net/pkt_cls.h>
  
  static unsigned int pedit_net_id;
  static struct tc_action_ops act_pedit_ops;
  
  static const struct nla_policy pedit_policy[TCA_PEDIT_MAX + 1] = {
  	[TCA_PEDIT_PARMS]	= { .len = sizeof(struct tc_pedit) },
  	[TCA_PEDIT_KEYS_EX]   = { .type = NLA_NESTED },
  };
  
  static const struct nla_policy pedit_key_ex_policy[TCA_PEDIT_KEY_EX_MAX + 1] = {
  	[TCA_PEDIT_KEY_EX_HTYPE]  = { .type = NLA_U16 },
  	[TCA_PEDIT_KEY_EX_CMD]	  = { .type = NLA_U16 },
  };
  
  static struct tcf_pedit_key_ex *tcf_pedit_keys_ex_parse(struct nlattr *nla,
  							u8 n)
  {
  	struct tcf_pedit_key_ex *keys_ex;
  	struct tcf_pedit_key_ex *k;
  	const struct nlattr *ka;
  	int err = -EINVAL;
  	int rem;
  
  	if (!nla || !n)
  		return NULL;
  
  	keys_ex = kcalloc(n, sizeof(*k), GFP_KERNEL);
  	if (!keys_ex)
  		return ERR_PTR(-ENOMEM);
  
  	k = keys_ex;
  
  	nla_for_each_nested(ka, nla, rem) {
  		struct nlattr *tb[TCA_PEDIT_KEY_EX_MAX + 1];
  
  		if (!n) {
  			err = -EINVAL;
  			goto err_out;
  		}
  		n--;
  
  		if (nla_type(ka) != TCA_PEDIT_KEY_EX) {
  			err = -EINVAL;
  			goto err_out;
  		}
  
  		err = nla_parse_nested_deprecated(tb, TCA_PEDIT_KEY_EX_MAX,
  						  ka, pedit_key_ex_policy,
  						  NULL);
  		if (err)
  			goto err_out;
  
  		if (!tb[TCA_PEDIT_KEY_EX_HTYPE] ||
  		    !tb[TCA_PEDIT_KEY_EX_CMD]) {
  			err = -EINVAL;
  			goto err_out;
  		}
  
  		k->htype = nla_get_u16(tb[TCA_PEDIT_KEY_EX_HTYPE]);
  		k->cmd = nla_get_u16(tb[TCA_PEDIT_KEY_EX_CMD]);
  
  		if (k->htype > TCA_PEDIT_HDR_TYPE_MAX ||
  		    k->cmd > TCA_PEDIT_CMD_MAX) {
  			err = -EINVAL;
  			goto err_out;
  		}
  
  		k++;
  	}
  
  	if (n) {
  		err = -EINVAL;
  		goto err_out;
  	}
  
  	return keys_ex;
  
  err_out:
  	kfree(keys_ex);
  	return ERR_PTR(err);
  }
  
  static int tcf_pedit_key_ex_dump(struct sk_buff *skb,
  				 struct tcf_pedit_key_ex *keys_ex, int n)
  {
  	struct nlattr *keys_start = nla_nest_start_noflag(skb,
  							  TCA_PEDIT_KEYS_EX);
  
  	if (!keys_start)
  		goto nla_failure;
  	for (; n > 0; n--) {
  		struct nlattr *key_start;
  
  		key_start = nla_nest_start_noflag(skb, TCA_PEDIT_KEY_EX);
  		if (!key_start)
  			goto nla_failure;
  
  		if (nla_put_u16(skb, TCA_PEDIT_KEY_EX_HTYPE, keys_ex->htype) ||
  		    nla_put_u16(skb, TCA_PEDIT_KEY_EX_CMD, keys_ex->cmd))
  			goto nla_failure;
  
  		nla_nest_end(skb, key_start);
  
  		keys_ex++;
  	}
  
  	nla_nest_end(skb, keys_start);
  
  	return 0;
  nla_failure:
  	nla_nest_cancel(skb, keys_start);
  	return -EINVAL;
  }
  
  static int tcf_pedit_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, struct netlink_ext_ack *extack)
  {
  	struct tc_action_net *tn = net_generic(net, pedit_net_id);
  	struct nlattr *tb[TCA_PEDIT_MAX + 1];
  	struct tcf_chain *goto_ch = NULL;
  	struct tc_pedit_key *keys = NULL;
  	struct tcf_pedit_key_ex *keys_ex;
  	struct tc_pedit *parm;
  	struct nlattr *pattr;
  	struct tcf_pedit *p;
  	int ret = 0, err;
  	int ksize;
  	u32 index;
  
  	if (!nla) {
  		NL_SET_ERR_MSG_MOD(extack, "Pedit requires attributes to be passed");
  		return -EINVAL;
  	}
  
  	err = nla_parse_nested_deprecated(tb, TCA_PEDIT_MAX, nla,
  					  pedit_policy, NULL);
  	if (err < 0)
  		return err;
  
  	pattr = tb[TCA_PEDIT_PARMS];
  	if (!pattr)
  		pattr = tb[TCA_PEDIT_PARMS_EX];
  	if (!pattr) {
  		NL_SET_ERR_MSG_MOD(extack, "Missing required TCA_PEDIT_PARMS or TCA_PEDIT_PARMS_EX pedit attribute");
  		return -EINVAL;
  	}
  
  	parm = nla_data(pattr);
  	ksize = parm->nkeys * sizeof(struct tc_pedit_key);
  	if (nla_len(pattr) < sizeof(*parm) + ksize) {
  		NL_SET_ERR_MSG_ATTR(extack, pattr, "Length of TCA_PEDIT_PARMS or TCA_PEDIT_PARMS_EX pedit attribute is invalid");
  		return -EINVAL;
  	}
  
  	keys_ex = tcf_pedit_keys_ex_parse(tb[TCA_PEDIT_KEYS_EX], parm->nkeys);
  	if (IS_ERR(keys_ex))
  		return PTR_ERR(keys_ex);
  
  	index = parm->index;
  	err = tcf_idr_check_alloc(tn, &index, a, bind);
  	if (!err) {
  		if (!parm->nkeys) {
  			tcf_idr_cleanup(tn, index);
  			NL_SET_ERR_MSG_MOD(extack, "Pedit requires keys to be passed");
  			ret = -EINVAL;
  			goto out_free;
  		}
  		ret = tcf_idr_create(tn, index, est, a,
  				     &act_pedit_ops, bind, false);
  		if (ret) {
  			tcf_idr_cleanup(tn, index);
  			goto out_free;
  		}
  		ret = ACT_P_CREATED;
  	} else if (err > 0) {
  		if (bind)
  			goto out_free;
  		if (!ovr) {
  			ret = -EEXIST;
  			goto out_release;
  		}
  	} else {
  		ret = err;
  		goto out_free;
  	}
  
  	err = tcf_action_check_ctrlact(parm->action, tp, &goto_ch, extack);
  	if (err < 0) {
  		ret = err;
  		goto out_release;
  	}
  	p = to_pedit(*a);
  	spin_lock_bh(&p->tcf_lock);
  
  	if (ret == ACT_P_CREATED ||
  	    (p->tcfp_nkeys && p->tcfp_nkeys != parm->nkeys)) {
  		keys = kmalloc(ksize, GFP_ATOMIC);
  		if (!keys) {
  			spin_unlock_bh(&p->tcf_lock);
  			ret = -ENOMEM;
  			goto put_chain;
  		}
  		kfree(p->tcfp_keys);
  		p->tcfp_keys = keys;
  		p->tcfp_nkeys = parm->nkeys;
  	}
  	memcpy(p->tcfp_keys, parm->keys, ksize);
  
  	p->tcfp_flags = parm->flags;
  	goto_ch = tcf_action_set_ctrlact(*a, parm->action, goto_ch);
  
  	kfree(p->tcfp_keys_ex);
  	p->tcfp_keys_ex = keys_ex;
  
  	spin_unlock_bh(&p->tcf_lock);
  	if (goto_ch)
  		tcf_chain_put_by_act(goto_ch);
  	if (ret == ACT_P_CREATED)
  		tcf_idr_insert(tn, *a);
  	return ret;
  
  put_chain:
  	if (goto_ch)
  		tcf_chain_put_by_act(goto_ch);
  out_release:
  	tcf_idr_release(*a, bind);
  out_free:
  	kfree(keys_ex);
  	return ret;
  
  }
  
  static void tcf_pedit_cleanup(struct tc_action *a)
  {
  	struct tcf_pedit *p = to_pedit(a);
  	struct tc_pedit_key *keys = p->tcfp_keys;
  
  	kfree(keys);
  	kfree(p->tcfp_keys_ex);
  }
  
  static bool offset_valid(struct sk_buff *skb, int offset)
  {
  	if (offset > 0 && offset > skb->len)
  		return false;
  
  	if  (offset < 0 && -offset > skb_headroom(skb))
  		return false;
  
  	return true;
  }
  
  static int pedit_skb_hdr_offset(struct sk_buff *skb,
  				enum pedit_header_type htype, int *hoffset)
  {
  	int ret = -EINVAL;
  
  	switch (htype) {
  	case TCA_PEDIT_KEY_EX_HDR_TYPE_ETH:
  		if (skb_mac_header_was_set(skb)) {
  			*hoffset = skb_mac_offset(skb);
  			ret = 0;
  		}
  		break;
  	case TCA_PEDIT_KEY_EX_HDR_TYPE_NETWORK:
  	case TCA_PEDIT_KEY_EX_HDR_TYPE_IP4:
  	case TCA_PEDIT_KEY_EX_HDR_TYPE_IP6:
  		*hoffset = skb_network_offset(skb);
  		ret = 0;
  		break;
  	case TCA_PEDIT_KEY_EX_HDR_TYPE_TCP:
  	case TCA_PEDIT_KEY_EX_HDR_TYPE_UDP:
  		if (skb_transport_header_was_set(skb)) {
  			*hoffset = skb_transport_offset(skb);
  			ret = 0;
  		}
  		break;
  	default:
  		ret = -EINVAL;
  		break;
  	}
  
  	return ret;
  }
  
  static int tcf_pedit_act(struct sk_buff *skb, const struct tc_action *a,
  			 struct tcf_result *res)
  {
  	struct tcf_pedit *p = to_pedit(a);
  	int i;
  
  	if (skb_unclone(skb, GFP_ATOMIC))
  		return p->tcf_action;
  
  	spin_lock(&p->tcf_lock);
  
  	tcf_lastuse_update(&p->tcf_tm);
  
  	if (p->tcfp_nkeys > 0) {
  		struct tc_pedit_key *tkey = p->tcfp_keys;
  		struct tcf_pedit_key_ex *tkey_ex = p->tcfp_keys_ex;
  		enum pedit_header_type htype =
  			TCA_PEDIT_KEY_EX_HDR_TYPE_NETWORK;
  		enum pedit_cmd cmd = TCA_PEDIT_KEY_EX_CMD_SET;
  
  		for (i = p->tcfp_nkeys; i > 0; i--, tkey++) {
  			u32 *ptr, hdata;
  			int offset = tkey->off;
  			int hoffset;
  			u32 val;
  			int rc;
  
  			if (tkey_ex) {
  				htype = tkey_ex->htype;
  				cmd = tkey_ex->cmd;
  
  				tkey_ex++;
  			}
  
  			rc = pedit_skb_hdr_offset(skb, htype, &hoffset);
  			if (rc) {
  				pr_info("tc action pedit bad header type specified (0x%x)\n",
  					htype);
  				goto bad;
  			}
  
  			if (tkey->offmask) {
  				u8 *d, _d;
  
  				if (!offset_valid(skb, hoffset + tkey->at)) {
  					pr_info("tc action pedit 'at' offset %d out of bounds\n",
  						hoffset + tkey->at);
  					goto bad;
  				}
  				d = skb_header_pointer(skb, hoffset + tkey->at,
  						       sizeof(_d), &_d);
  				if (!d)
  					goto bad;
  				offset += (*d & tkey->offmask) >> tkey->shift;
  			}
  
  			if (offset % 4) {
  				pr_info("tc action pedit offset must be on 32 bit boundaries\n");
  				goto bad;
  			}
  
  			if (!offset_valid(skb, hoffset + offset)) {
  				pr_info("tc action pedit offset %d out of bounds\n",
  					hoffset + offset);
  				goto bad;
  			}
  
  			ptr = skb_header_pointer(skb, hoffset + offset,
  						 sizeof(hdata), &hdata);
  			if (!ptr)
  				goto bad;
  			/* just do it, baby */
  			switch (cmd) {
  			case TCA_PEDIT_KEY_EX_CMD_SET:
  				val = tkey->val;
  				break;
  			case TCA_PEDIT_KEY_EX_CMD_ADD:
  				val = (*ptr + tkey->val) & ~tkey->mask;
  				break;
  			default:
  				pr_info("tc action pedit bad command (%d)\n",
  					cmd);
  				goto bad;
  			}
  
  			*ptr = ((*ptr & tkey->mask) ^ val);
  			if (ptr == &hdata)
  				skb_store_bits(skb, hoffset + offset, ptr, 4);
  		}
  
  		goto done;
  	} else {
  		WARN(1, "pedit BUG: index %d\n", p->tcf_index);
  	}
  
  bad:
  	p->tcf_qstats.overlimits++;
  done:
  	bstats_update(&p->tcf_bstats, skb);
  	spin_unlock(&p->tcf_lock);
  	return p->tcf_action;
  }
  
  static int tcf_pedit_dump(struct sk_buff *skb, struct tc_action *a,
  			  int bind, int ref)
  {
  	unsigned char *b = skb_tail_pointer(skb);
  	struct tcf_pedit *p = to_pedit(a);
  	struct tc_pedit *opt;
  	struct tcf_t t;
  	int s;
  
  	s = struct_size(opt, keys, p->tcfp_nkeys);
  
  	/* netlink spinlocks held above us - must use ATOMIC */
  	opt = kzalloc(s, GFP_ATOMIC);
  	if (unlikely(!opt))
  		return -ENOBUFS;
  
  	spin_lock_bh(&p->tcf_lock);
  	memcpy(opt->keys, p->tcfp_keys,
  	       p->tcfp_nkeys * sizeof(struct tc_pedit_key));
  	opt->index = p->tcf_index;
  	opt->nkeys = p->tcfp_nkeys;
  	opt->flags = p->tcfp_flags;
  	opt->action = p->tcf_action;
  	opt->refcnt = refcount_read(&p->tcf_refcnt) - ref;
  	opt->bindcnt = atomic_read(&p->tcf_bindcnt) - bind;
  
  	if (p->tcfp_keys_ex) {
  		if (tcf_pedit_key_ex_dump(skb,
  					  p->tcfp_keys_ex,
  					  p->tcfp_nkeys))
  			goto nla_put_failure;
  
  		if (nla_put(skb, TCA_PEDIT_PARMS_EX, s, opt))
  			goto nla_put_failure;
  	} else {
  		if (nla_put(skb, TCA_PEDIT_PARMS, s, opt))
  			goto nla_put_failure;
  	}
  
  	tcf_tm_dump(&t, &p->tcf_tm);
  	if (nla_put_64bit(skb, TCA_PEDIT_TM, sizeof(t), &t, TCA_PEDIT_PAD))
  		goto nla_put_failure;
  	spin_unlock_bh(&p->tcf_lock);
  
  	kfree(opt);
  	return skb->len;
  
  nla_put_failure:
  	spin_unlock_bh(&p->tcf_lock);
  	nlmsg_trim(skb, b);
  	kfree(opt);
  	return -1;
  }
  
  static int tcf_pedit_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, pedit_net_id);
  
  	return tcf_generic_walker(tn, skb, cb, type, ops, extack);
  }
  
  static int tcf_pedit_search(struct net *net, struct tc_action **a, u32 index)
  {
  	struct tc_action_net *tn = net_generic(net, pedit_net_id);
  
  	return tcf_idr_search(tn, a, index);
  }
  
  static struct tc_action_ops act_pedit_ops = {
  	.kind		=	"pedit",
  	.id		=	TCA_ID_PEDIT,
  	.owner		=	THIS_MODULE,
  	.act		=	tcf_pedit_act,
  	.dump		=	tcf_pedit_dump,
  	.cleanup	=	tcf_pedit_cleanup,
  	.init		=	tcf_pedit_init,
  	.walk		=	tcf_pedit_walker,
  	.lookup		=	tcf_pedit_search,
  	.size		=	sizeof(struct tcf_pedit),
  };
  
  static __net_init int pedit_init_net(struct net *net)
  {
  	struct tc_action_net *tn = net_generic(net, pedit_net_id);
  
  	return tc_action_net_init(net, tn, &act_pedit_ops);
  }
  
  static void __net_exit pedit_exit_net(struct list_head *net_list)
  {
  	tc_action_net_exit(net_list, pedit_net_id);
  }
  
  static struct pernet_operations pedit_net_ops = {
  	.init = pedit_init_net,
  	.exit_batch = pedit_exit_net,
  	.id   = &pedit_net_id,
  	.size = sizeof(struct tc_action_net),
  };
  
  MODULE_AUTHOR("Jamal Hadi Salim(2002-4)");
  MODULE_DESCRIPTION("Generic Packet Editor actions");
  MODULE_LICENSE("GPL");
  
  static int __init pedit_init_module(void)
  {
  	return tcf_register_action(&act_pedit_ops, &pedit_net_ops);
  }
  
  static void __exit pedit_cleanup_module(void)
  {
  	tcf_unregister_action(&act_pedit_ops, &pedit_net_ops);
  }
  
  module_init(pedit_init_module);
  module_exit(pedit_cleanup_module);
  