[linux.git] / net / core / lwt_bpf.c

/* Copyright (c) 2016 Thomas Graf <[email protected]>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of version 2 of the GNU General Public
 * License as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * General Public License for more details.
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/types.h>
#include <linux/bpf.h>
#include <net/lwtunnel.h>

struct bpf_lwt_prog {
	struct bpf_prog *prog;
	char *name;
};

struct bpf_lwt {
	struct bpf_lwt_prog in;
	struct bpf_lwt_prog out;
	struct bpf_lwt_prog xmit;
	int family;
};

#define MAX_PROG_NAME 256

static inline struct bpf_lwt *bpf_lwt_lwtunnel(struct lwtunnel_state *lwt)
{
	return (struct bpf_lwt *)lwt->data;
}

#define NO_REDIRECT false
#define CAN_REDIRECT true

static int run_lwt_bpf(struct sk_buff *skb, struct bpf_lwt_prog *lwt,
		       struct dst_entry *dst, bool can_redirect)
{
	int ret;

	/* Preempt disable is needed to protect per-cpu redirect_info between
	 * BPF prog and skb_do_redirect(). The call_rcu in bpf_prog_put() and
	 * access to maps strictly require a rcu_read_lock() for protection,
	 * mixing with BH RCU lock doesn't work.
	 */
	preempt_disable();
	rcu_read_lock();
	bpf_compute_data_pointers(skb);
	ret = bpf_prog_run_save_cb(lwt->prog, skb);
	rcu_read_unlock();

	switch (ret) {
	case BPF_OK:
		break;

	case BPF_REDIRECT:
		if (unlikely(!can_redirect)) {
			pr_warn_once("Illegal redirect return code in prog %s\n",
				     lwt->name ? : "<unknown>");
			ret = BPF_OK;
		} else {
			ret = skb_do_redirect(skb);
			if (ret == 0)
				ret = BPF_REDIRECT;
		}
		break;

	case BPF_DROP:
		kfree_skb(skb);
		ret = -EPERM;
		break;

	default:
		pr_warn_once("bpf-lwt: Illegal return value %u, expect packet loss\n", ret);
		kfree_skb(skb);
		ret = -EINVAL;
		break;
	}

	preempt_enable();

	return ret;
}

static int bpf_input(struct sk_buff *skb)
{
	struct dst_entry *dst = skb_dst(skb);
	struct bpf_lwt *bpf;
	int ret;

	bpf = bpf_lwt_lwtunnel(dst->lwtstate);
	if (bpf->in.prog) {
		ret = run_lwt_bpf(skb, &bpf->in, dst, NO_REDIRECT);
		if (ret < 0)
			return ret;
	}

	if (unlikely(!dst->lwtstate->orig_input)) {
		pr_warn_once("orig_input not set on dst for prog %s\n",
			     bpf->out.name);
		kfree_skb(skb);
		return -EINVAL;
	}

	return dst->lwtstate->orig_input(skb);
}

static int bpf_output(struct net *net, struct sock *sk, struct sk_buff *skb)
{
	struct dst_entry *dst = skb_dst(skb);
	struct bpf_lwt *bpf;
	int ret;

	bpf = bpf_lwt_lwtunnel(dst->lwtstate);
	if (bpf->out.prog) {
		ret = run_lwt_bpf(skb, &bpf->out, dst, NO_REDIRECT);
		if (ret < 0)
			return ret;
	}

	if (unlikely(!dst->lwtstate->orig_output)) {
		pr_warn_once("orig_output not set on dst for prog %s\n",
			     bpf->out.name);
		kfree_skb(skb);
		return -EINVAL;
	}

	return dst->lwtstate->orig_output(net, sk, skb);
}

static int xmit_check_hhlen(struct sk_buff *skb)
{
	int hh_len = skb_dst(skb)->dev->hard_header_len;

	if (skb_headroom(skb) < hh_len) {
		int nhead = HH_DATA_ALIGN(hh_len - skb_headroom(skb));

		if (pskb_expand_head(skb, nhead, 0, GFP_ATOMIC))
			return -ENOMEM;
	}

	return 0;
}

static int bpf_xmit(struct sk_buff *skb)
{
	struct dst_entry *dst = skb_dst(skb);
	struct bpf_lwt *bpf;

	bpf = bpf_lwt_lwtunnel(dst->lwtstate);
	if (bpf->xmit.prog) {
		int ret;

		ret = run_lwt_bpf(skb, &bpf->xmit, dst, CAN_REDIRECT);
		switch (ret) {
		case BPF_OK:
			/* If the header was expanded, headroom might be too
			 * small for L2 header to come, expand as needed.
			 */
			ret = xmit_check_hhlen(skb);
			if (unlikely(ret))
				return ret;

			return LWTUNNEL_XMIT_CONTINUE;
		case BPF_REDIRECT:
			return LWTUNNEL_XMIT_DONE;
		default:
			return ret;
		}
	}

	return LWTUNNEL_XMIT_CONTINUE;
}

static void bpf_lwt_prog_destroy(struct bpf_lwt_prog *prog)
{
	if (prog->prog)
		bpf_prog_put(prog->prog);

	kfree(prog->name);
}

static void bpf_destroy_state(struct lwtunnel_state *lwt)
{
	struct bpf_lwt *bpf = bpf_lwt_lwtunnel(lwt);

	bpf_lwt_prog_destroy(&bpf->in);
	bpf_lwt_prog_destroy(&bpf->out);
	bpf_lwt_prog_destroy(&bpf->xmit);
}

static const struct nla_policy bpf_prog_policy[LWT_BPF_PROG_MAX + 1] = {
	[LWT_BPF_PROG_FD]   = { .type = NLA_U32, },
	[LWT_BPF_PROG_NAME] = { .type = NLA_NUL_STRING,
				.len = MAX_PROG_NAME },
};

static int bpf_parse_prog(struct nlattr *attr, struct bpf_lwt_prog *prog,
			  enum bpf_prog_type type)
{
	struct nlattr *tb[LWT_BPF_PROG_MAX + 1];
	struct bpf_prog *p;
	int ret;
	u32 fd;

	ret = nla_parse_nested(tb, LWT_BPF_PROG_MAX, attr, bpf_prog_policy,
			       NULL);
	if (ret < 0)
		return ret;

	if (!tb[LWT_BPF_PROG_FD] || !tb[LWT_BPF_PROG_NAME])
		return -EINVAL;

	prog->name = nla_memdup(tb[LWT_BPF_PROG_NAME], GFP_KERNEL);
	if (!prog->name)
		return -ENOMEM;

	fd = nla_get_u32(tb[LWT_BPF_PROG_FD]);
	p = bpf_prog_get_type(fd, type);
	if (IS_ERR(p))
		return PTR_ERR(p);

	prog->prog = p;

	return 0;
}

static const struct nla_policy bpf_nl_policy[LWT_BPF_MAX + 1] = {
	[LWT_BPF_IN]		= { .type = NLA_NESTED, },
	[LWT_BPF_OUT]		= { .type = NLA_NESTED, },
	[LWT_BPF_XMIT]		= { .type = NLA_NESTED, },
	[LWT_BPF_XMIT_HEADROOM]	= { .type = NLA_U32 },
};

static int bpf_build_state(struct nlattr *nla,
			   unsigned int family, const void *cfg,
			   struct lwtunnel_state **ts,
			   struct netlink_ext_ack *extack)
{
	struct nlattr *tb[LWT_BPF_MAX + 1];
	struct lwtunnel_state *newts;
	struct bpf_lwt *bpf;
	int ret;

	if (family != AF_INET && family != AF_INET6)
		return -EAFNOSUPPORT;

	ret = nla_parse_nested(tb, LWT_BPF_MAX, nla, bpf_nl_policy, extack);
	if (ret < 0)
		return ret;

	if (!tb[LWT_BPF_IN] && !tb[LWT_BPF_OUT] && !tb[LWT_BPF_XMIT])
		return -EINVAL;

	newts = lwtunnel_state_alloc(sizeof(*bpf));
	if (!newts)
		return -ENOMEM;

	newts->type = LWTUNNEL_ENCAP_BPF;
	bpf = bpf_lwt_lwtunnel(newts);

	if (tb[LWT_BPF_IN]) {
		newts->flags |= LWTUNNEL_STATE_INPUT_REDIRECT;
		ret = bpf_parse_prog(tb[LWT_BPF_IN], &bpf->in,
				     BPF_PROG_TYPE_LWT_IN);
		if (ret  < 0)
			goto errout;
	}

	if (tb[LWT_BPF_OUT]) {
		newts->flags |= LWTUNNEL_STATE_OUTPUT_REDIRECT;
		ret = bpf_parse_prog(tb[LWT_BPF_OUT], &bpf->out,
				     BPF_PROG_TYPE_LWT_OUT);
		if (ret < 0)
			goto errout;
	}

	if (tb[LWT_BPF_XMIT]) {
		newts->flags |= LWTUNNEL_STATE_XMIT_REDIRECT;
		ret = bpf_parse_prog(tb[LWT_BPF_XMIT], &bpf->xmit,
				     BPF_PROG_TYPE_LWT_XMIT);
		if (ret < 0)
			goto errout;
	}

	if (tb[LWT_BPF_XMIT_HEADROOM]) {
		u32 headroom = nla_get_u32(tb[LWT_BPF_XMIT_HEADROOM]);

		if (headroom > LWT_BPF_MAX_HEADROOM) {
			ret = -ERANGE;
			goto errout;
		}

		newts->headroom = headroom;
	}

	bpf->family = family;
	*ts = newts;

	return 0;

errout:
	bpf_destroy_state(newts);
	kfree(newts);
	return ret;
}

static int bpf_fill_lwt_prog(struct sk_buff *skb, int attr,
			     struct bpf_lwt_prog *prog)
{
	struct nlattr *nest;

	if (!prog->prog)
		return 0;

	nest = nla_nest_start(skb, attr);
	if (!nest)
		return -EMSGSIZE;

	if (prog->name &&
	    nla_put_string(skb, LWT_BPF_PROG_NAME, prog->name))
		return -EMSGSIZE;

	return nla_nest_end(skb, nest);
}

static int bpf_fill_encap_info(struct sk_buff *skb, struct lwtunnel_state *lwt)
{
	struct bpf_lwt *bpf = bpf_lwt_lwtunnel(lwt);

	if (bpf_fill_lwt_prog(skb, LWT_BPF_IN, &bpf->in) < 0 ||
	    bpf_fill_lwt_prog(skb, LWT_BPF_OUT, &bpf->out) < 0 ||
	    bpf_fill_lwt_prog(skb, LWT_BPF_XMIT, &bpf->xmit) < 0)
		return -EMSGSIZE;

	return 0;
}

static int bpf_encap_nlsize(struct lwtunnel_state *lwtstate)
{
	int nest_len = nla_total_size(sizeof(struct nlattr)) +
		       nla_total_size(MAX_PROG_NAME) + /* LWT_BPF_PROG_NAME */
		       0;

	return nest_len + /* LWT_BPF_IN */
	       nest_len + /* LWT_BPF_OUT */
	       nest_len + /* LWT_BPF_XMIT */
	       0;
}

static int bpf_lwt_prog_cmp(struct bpf_lwt_prog *a, struct bpf_lwt_prog *b)
{
	/* FIXME:
	 * The LWT state is currently rebuilt for delete requests which
	 * results in a new bpf_prog instance. Comparing names for now.
	 */
	if (!a->name && !b->name)
		return 0;

	if (!a->name || !b->name)
		return 1;

	return strcmp(a->name, b->name);
}

static int bpf_encap_cmp(struct lwtunnel_state *a, struct lwtunnel_state *b)
{
	struct bpf_lwt *a_bpf = bpf_lwt_lwtunnel(a);
	struct bpf_lwt *b_bpf = bpf_lwt_lwtunnel(b);

	return bpf_lwt_prog_cmp(&a_bpf->in, &b_bpf->in) ||
	       bpf_lwt_prog_cmp(&a_bpf->out, &b_bpf->out) ||
	       bpf_lwt_prog_cmp(&a_bpf->xmit, &b_bpf->xmit);
}

static const struct lwtunnel_encap_ops bpf_encap_ops = {
	.build_state	= bpf_build_state,
	.destroy_state	= bpf_destroy_state,
	.input		= bpf_input,
	.output		= bpf_output,
	.xmit		= bpf_xmit,
	.fill_encap	= bpf_fill_encap_info,
	.get_encap_size = bpf_encap_nlsize,
	.cmp_encap	= bpf_encap_cmp,
	.owner		= THIS_MODULE,
};

static int __init bpf_lwt_init(void)
{
	return lwtunnel_encap_add_ops(&bpf_encap_ops, LWTUNNEL_ENCAP_BPF);
}

subsys_initcall(bpf_lwt_init)
Commit	Line	Data
3a0af8fd TG	1	/* Copyright (c) 2016 Thomas Graf <[email protected]>
	2	*
	3	* This program is free software; you can redistribute it and/or
	4	* modify it under the terms of version 2 of the GNU General Public
	5	* License as published by the Free Software Foundation.
	6	*
	7	* This program is distributed in the hope that it will be useful, but
	8	* WITHOUT ANY WARRANTY; without even the implied warranty of
	9	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	10	* General Public License for more details.
	11	*/
	12
	13	#include <linux/kernel.h>
	14	#include <linux/module.h>
	15	#include <linux/skbuff.h>
	16	#include <linux/types.h>
	17	#include <linux/bpf.h>
	18	#include <net/lwtunnel.h>
	19
	20	struct bpf_lwt_prog {
	21	struct bpf_prog *prog;
	22	char *name;
	23	};
	24
	25	struct bpf_lwt {
	26	struct bpf_lwt_prog in;
	27	struct bpf_lwt_prog out;
	28	struct bpf_lwt_prog xmit;
	29	int family;
	30	};
	31
	32	#define MAX_PROG_NAME 256
	33
	34	static inline struct bpf_lwt bpf_lwt_lwtunnel(struct lwtunnel_state lwt)
	35	{
	36	return (struct bpf_lwt *)lwt->data;
	37	}
	38
	39	#define NO_REDIRECT false
	40	#define CAN_REDIRECT true
	41
	42	static int run_lwt_bpf(struct sk_buff skb, struct bpf_lwt_prog lwt,
	43	struct dst_entry *dst, bool can_redirect)
	44	{
	45	int ret;
	46
	47	/* Preempt disable is needed to protect per-cpu redirect_info between
	48	* BPF prog and skb_do_redirect(). The call_rcu in bpf_prog_put() and
	49	* access to maps strictly require a rcu_read_lock() for protection,
	50	* mixing with BH RCU lock doesn't work.
	51	*/
	52	preempt_disable();
	53	rcu_read_lock();
6aaae2b6	54	bpf_compute_data_pointers(skb);
3a0af8fd TG	55	ret = bpf_prog_run_save_cb(lwt->prog, skb);
	56	rcu_read_unlock();
	57
	58	switch (ret) {
	59	case BPF_OK:
	60	break;
	61
	62	case BPF_REDIRECT:
	63	if (unlikely(!can_redirect)) {
	64	pr_warn_once("Illegal redirect return code in prog %s\n",
	65	lwt->name ? : "<unknown>");
	66	ret = BPF_OK;
	67	} else {
	68	ret = skb_do_redirect(skb);
	69	if (ret == 0)
	70	ret = BPF_REDIRECT;
	71	}
	72	break;
	73
	74	case BPF_DROP:
	75	kfree_skb(skb);
	76	ret = -EPERM;
	77	break;
	78
	79	default:
	80	pr_warn_once("bpf-lwt: Illegal return value %u, expect packet loss\n", ret);
	81	kfree_skb(skb);
	82	ret = -EINVAL;
	83	break;
	84	}
	85
	86	preempt_enable();
	87
	88	return ret;
	89	}
	90
	91	static int bpf_input(struct sk_buff *skb)
	92	{
	93	struct dst_entry *dst = skb_dst(skb);
	94	struct bpf_lwt *bpf;
	95	int ret;
	96
	97	bpf = bpf_lwt_lwtunnel(dst->lwtstate);
	98	if (bpf->in.prog) {
	99	ret = run_lwt_bpf(skb, &bpf->in, dst, NO_REDIRECT);
	100	if (ret < 0)
	101	return ret;
	102	}
	103
	104	if (unlikely(!dst->lwtstate->orig_input)) {
	105	pr_warn_once("orig_input not set on dst for prog %s\n",
	106	bpf->out.name);
	107	kfree_skb(skb);
	108	return -EINVAL;
	109	}
	110
	111	return dst->lwtstate->orig_input(skb);
	112	}
	113
	114	static int bpf_output(struct net net, struct sock sk, struct sk_buff *skb)
	115	{
	116	struct dst_entry *dst = skb_dst(skb);
	117	struct bpf_lwt *bpf;
	118	int ret;
119
120	bpf = bpf_lwt_lwtunnel(dst->lwtstate);
121	if (bpf->out.prog) {
122	ret = run_lwt_bpf(skb, &bpf->out, dst, NO_REDIRECT);
123	if (ret < 0)
124	return ret;
125	}
126
127	if (unlikely(!dst->lwtstate->orig_output)) {
128	pr_warn_once("orig_output not set on dst for prog %s\n",
129	bpf->out.name);
130	kfree_skb(skb);
131	return -EINVAL;
132	}
133
134	return dst->lwtstate->orig_output(net, sk, skb);
135	}
136
137	static int xmit_check_hhlen(struct sk_buff *skb)
138	{
139	int hh_len = skb_dst(skb)->dev->hard_header_len;
140
141	if (skb_headroom(skb) < hh_len) {
142	int nhead = HH_DATA_ALIGN(hh_len - skb_headroom(skb));
143
144	if (pskb_expand_head(skb, nhead, 0, GFP_ATOMIC))
145	return -ENOMEM;
146	}
147
148	return 0;
149	}
150
151	static int bpf_xmit(struct sk_buff *skb)
152	{
153	struct dst_entry *dst = skb_dst(skb);
154	struct bpf_lwt *bpf;
155
156	bpf = bpf_lwt_lwtunnel(dst->lwtstate);
157	if (bpf->xmit.prog) {
158	int ret;
159
160	ret = run_lwt_bpf(skb, &bpf->xmit, dst, CAN_REDIRECT);
161	switch (ret) {
162	case BPF_OK:
163	/* If the header was expanded, headroom might be too
164	* small for L2 header to come, expand as needed.
165	*/
166	ret = xmit_check_hhlen(skb);
167	if (unlikely(ret))
168	return ret;
169
170	return LWTUNNEL_XMIT_CONTINUE;
171	case BPF_REDIRECT:
172	return LWTUNNEL_XMIT_DONE;
173	default:
174	return ret;
175	}
176	}
177
178	return LWTUNNEL_XMIT_CONTINUE;
179	}
180
181	static void bpf_lwt_prog_destroy(struct bpf_lwt_prog *prog)
182	{
183	if (prog->prog)
184	bpf_prog_put(prog->prog);
185
186	kfree(prog->name);
187	}
188
189	static void bpf_destroy_state(struct lwtunnel_state *lwt)
190	{
191	struct bpf_lwt *bpf = bpf_lwt_lwtunnel(lwt);
192
193	bpf_lwt_prog_destroy(&bpf->in);
194	bpf_lwt_prog_destroy(&bpf->out);
195	bpf_lwt_prog_destroy(&bpf->xmit);
196	}
197
198	static const struct nla_policy bpf_prog_policy[LWT_BPF_PROG_MAX + 1] = {
199	[LWT_BPF_PROG_FD] = { .type = NLA_U32, },
200	[LWT_BPF_PROG_NAME] = { .type = NLA_NUL_STRING,
201	.len = MAX_PROG_NAME },
202	};
203
204	static int bpf_parse_prog(struct nlattr attr, struct bpf_lwt_prog prog,
205	enum bpf_prog_type type)
206	{
207	struct nlattr *tb[LWT_BPF_PROG_MAX + 1];
208	struct bpf_prog *p;
209	int ret;
210	u32 fd;
211
fceb6435 JB	212	ret = nla_parse_nested(tb, LWT_BPF_PROG_MAX, attr, bpf_prog_policy,
fceb6435 JB	213	NULL);
3a0af8fd TG	214	if (ret < 0)
	215	return ret;
	216
	217	if (!tb[LWT_BPF_PROG_FD] \|\| !tb[LWT_BPF_PROG_NAME])
	218	return -EINVAL;
	219
	220	prog->name = nla_memdup(tb[LWT_BPF_PROG_NAME], GFP_KERNEL);
	221	if (!prog->name)
	222	return -ENOMEM;
	223
	224	fd = nla_get_u32(tb[LWT_BPF_PROG_FD]);
	225	p = bpf_prog_get_type(fd, type);
	226	if (IS_ERR(p))
	227	return PTR_ERR(p);
	228
	229	prog->prog = p;
	230
	231	return 0;
	232	}
	233
	234	static const struct nla_policy bpf_nl_policy[LWT_BPF_MAX + 1] = {
	235	[LWT_BPF_IN] = { .type = NLA_NESTED, },
	236	[LWT_BPF_OUT] = { .type = NLA_NESTED, },
	237	[LWT_BPF_XMIT] = { .type = NLA_NESTED, },
	238	[LWT_BPF_XMIT_HEADROOM] = { .type = NLA_U32 },
	239	};
	240
30357d7d	241	static int bpf_build_state(struct nlattr *nla,
3a0af8fd	242	unsigned int family, const void *cfg,
9ae28727 DA	243	struct lwtunnel_state **ts,
9ae28727 DA	244	struct netlink_ext_ack *extack)
3a0af8fd TG	245	{
	246	struct nlattr *tb[LWT_BPF_MAX + 1];
	247	struct lwtunnel_state *newts;
	248	struct bpf_lwt *bpf;
	249	int ret;
	250
	251	if (family != AF_INET && family != AF_INET6)
	252	return -EAFNOSUPPORT;
	253
9ae28727	254	ret = nla_parse_nested(tb, LWT_BPF_MAX, nla, bpf_nl_policy, extack);
3a0af8fd TG	255	if (ret < 0)
	256	return ret;
	257
	258	if (!tb[LWT_BPF_IN] && !tb[LWT_BPF_OUT] && !tb[LWT_BPF_XMIT])
	259	return -EINVAL;
	260
	261	newts = lwtunnel_state_alloc(sizeof(*bpf));
	262	if (!newts)
	263	return -ENOMEM;
	264
	265	newts->type = LWTUNNEL_ENCAP_BPF;
	266	bpf = bpf_lwt_lwtunnel(newts);
	267
	268	if (tb[LWT_BPF_IN]) {
	269	newts->flags \|= LWTUNNEL_STATE_INPUT_REDIRECT;
	270	ret = bpf_parse_prog(tb[LWT_BPF_IN], &bpf->in,
	271	BPF_PROG_TYPE_LWT_IN);
	272	if (ret < 0)
	273	goto errout;
	274	}
	275
	276	if (tb[LWT_BPF_OUT]) {
	277	newts->flags \|= LWTUNNEL_STATE_OUTPUT_REDIRECT;
	278	ret = bpf_parse_prog(tb[LWT_BPF_OUT], &bpf->out,
	279	BPF_PROG_TYPE_LWT_OUT);
	280	if (ret < 0)
	281	goto errout;
	282	}
	283
	284	if (tb[LWT_BPF_XMIT]) {
	285	newts->flags \|= LWTUNNEL_STATE_XMIT_REDIRECT;
	286	ret = bpf_parse_prog(tb[LWT_BPF_XMIT], &bpf->xmit,
	287	BPF_PROG_TYPE_LWT_XMIT);
	288	if (ret < 0)
	289	goto errout;
	290	}
	291
	292	if (tb[LWT_BPF_XMIT_HEADROOM]) {
	293	u32 headroom = nla_get_u32(tb[LWT_BPF_XMIT_HEADROOM]);
	294
	295	if (headroom > LWT_BPF_MAX_HEADROOM) {
	296	ret = -ERANGE;
	297	goto errout;
	298	}
	299
	300	newts->headroom = headroom;
	301	}
	302
	303	bpf->family = family;
	304	*ts = newts;
	305
	306	return 0;
	307
	308	errout:
	309	bpf_destroy_state(newts);
	310	kfree(newts);
	311	return ret;
	312	}
	313
	314	static int bpf_fill_lwt_prog(struct sk_buff *skb, int attr,
	315	struct bpf_lwt_prog *prog)
	316	{
	317	struct nlattr *nest;
	318
319	if (!prog->prog)
320	return 0;
321
322	nest = nla_nest_start(skb, attr);
323	if (!nest)
324	return -EMSGSIZE;
325
326	if (prog->name &&
327	nla_put_string(skb, LWT_BPF_PROG_NAME, prog->name))
328	return -EMSGSIZE;
329
330	return nla_nest_end(skb, nest);
331	}
332
333	static int bpf_fill_encap_info(struct sk_buff skb, struct lwtunnel_state lwt)
334	{
335	struct bpf_lwt *bpf = bpf_lwt_lwtunnel(lwt);
336
337	if (bpf_fill_lwt_prog(skb, LWT_BPF_IN, &bpf->in) < 0 \|\|
338	bpf_fill_lwt_prog(skb, LWT_BPF_OUT, &bpf->out) < 0 \|\|
339	bpf_fill_lwt_prog(skb, LWT_BPF_XMIT, &bpf->xmit) < 0)
340	return -EMSGSIZE;
341
342	return 0;
343	}
344
345	static int bpf_encap_nlsize(struct lwtunnel_state *lwtstate)
346	{
347	int nest_len = nla_total_size(sizeof(struct nlattr)) +
348	nla_total_size(MAX_PROG_NAME) + /* LWT_BPF_PROG_NAME */
349	0;
350
351	return nest_len + /* LWT_BPF_IN */
352	nest_len + /* LWT_BPF_OUT */
353	nest_len + /* LWT_BPF_XMIT */
354	0;
355	}
356
79471b10	357	static int bpf_lwt_prog_cmp(struct bpf_lwt_prog a, struct bpf_lwt_prog b)
3a0af8fd TG	358	{
	359	/* FIXME:
	360	* The LWT state is currently rebuilt for delete requests which
	361	* results in a new bpf_prog instance. Comparing names for now.
	362	*/
	363	if (!a->name && !b->name)
	364	return 0;
	365
	366	if (!a->name \|\| !b->name)
	367	return 1;
	368
	369	return strcmp(a->name, b->name);
	370	}
	371
	372	static int bpf_encap_cmp(struct lwtunnel_state a, struct lwtunnel_state b)
	373	{
	374	struct bpf_lwt *a_bpf = bpf_lwt_lwtunnel(a);
	375	struct bpf_lwt *b_bpf = bpf_lwt_lwtunnel(b);
	376
	377	return bpf_lwt_prog_cmp(&a_bpf->in, &b_bpf->in) \|\|
	378	bpf_lwt_prog_cmp(&a_bpf->out, &b_bpf->out) \|\|
	379	bpf_lwt_prog_cmp(&a_bpf->xmit, &b_bpf->xmit);
	380	}
	381
	382	static const struct lwtunnel_encap_ops bpf_encap_ops = {
	383	.build_state = bpf_build_state,
	384	.destroy_state = bpf_destroy_state,
	385	.input = bpf_input,
	386	.output = bpf_output,
	387	.xmit = bpf_xmit,
	388	.fill_encap = bpf_fill_encap_info,
	389	.get_encap_size = bpf_encap_nlsize,
	390	.cmp_encap = bpf_encap_cmp,
88ff7334	391	.owner = THIS_MODULE,
3a0af8fd TG	392	};
	393
	394	static int __init bpf_lwt_init(void)
	395	{
	396	return lwtunnel_encap_add_ops(&bpf_encap_ops, LWTUNNEL_ENCAP_BPF);
	397	}
	398
	399	subsys_initcall(bpf_lwt_init)