act_pedit.c

// 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;

	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);

	err = tcf_idr_check_alloc(tn, &parm->index, a, bind);
	if (!err) {
		if (!parm->nkeys) {
			tcf_idr_cleanup(tn, parm->index);
			NL_SET_ERR_MSG_MOD(extack, "Pedit requires keys to be passed");
			ret = -EINVAL;
			goto out_free;
		}
		ret = tcf_idr_create(tn, parm->index, est, a,
				     &act_pedit_ops, bind, false);
		if (ret) {
			tcf_idr_cleanup(tn, parm->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(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);