[linux-2.6-block.git] / net / core / lwt_bpf.c

/* Copyright (c) 2016 Thomas Graf <tgraf@tgraf.ch>
 *
 * 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();
	bpf_compute_data_pointers(skb);
	ret = bpf_prog_run_save_cb(lwt->prog, skb);

	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 {
			skb_reset_mac_header(skb);
			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_ATOMIC);
	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 <tgraf@tgraf.ch>
	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();
6aaae2b6	53	bpf_compute_data_pointers(skb);
3a0af8fd	54	ret = bpf_prog_run_save_cb(lwt->prog, skb);
3a0af8fd TG	55
	56	switch (ret) {
	57	case BPF_OK:
	58	break;
	59
	60	case BPF_REDIRECT:
	61	if (unlikely(!can_redirect)) {
	62	pr_warn_once("Illegal redirect return code in prog %s\n",
	63	lwt->name ? : "<unknown>");
	64	ret = BPF_OK;
	65	} else {
e7c87bd6	66	skb_reset_mac_header(skb);
3a0af8fd TG	67	ret = skb_do_redirect(skb);
	68	if (ret == 0)
	69	ret = BPF_REDIRECT;
	70	}
	71	break;
	72
	73	case BPF_DROP:
	74	kfree_skb(skb);
	75	ret = -EPERM;
	76	break;
	77
	78	default:
	79	pr_warn_once("bpf-lwt: Illegal return value %u, expect packet loss\n", ret);
	80	kfree_skb(skb);
	81	ret = -EINVAL;
	82	break;
	83	}
	84
	85	preempt_enable();
	86
	87	return ret;
	88	}
	89
	90	static int bpf_input(struct sk_buff *skb)
	91	{
	92	struct dst_entry *dst = skb_dst(skb);
	93	struct bpf_lwt *bpf;
	94	int ret;
	95
	96	bpf = bpf_lwt_lwtunnel(dst->lwtstate);
	97	if (bpf->in.prog) {
	98	ret = run_lwt_bpf(skb, &bpf->in, dst, NO_REDIRECT);
	99	if (ret < 0)
	100	return ret;
	101	}
	102
	103	if (unlikely(!dst->lwtstate->orig_input)) {
	104	pr_warn_once("orig_input not set on dst for prog %s\n",
	105	bpf->out.name);
	106	kfree_skb(skb);
	107	return -EINVAL;
	108	}
	109
	110	return dst->lwtstate->orig_input(skb);
	111	}
	112
	113	static int bpf_output(struct net net, struct sock sk, struct sk_buff *skb)
	114	{
	115	struct dst_entry *dst = skb_dst(skb);
	116	struct bpf_lwt *bpf;
	117	int ret;
	118
	119	bpf = bpf_lwt_lwtunnel(dst->lwtstate);
	120	if (bpf->out.prog) {
	121	ret = run_lwt_bpf(skb, &bpf->out, dst, NO_REDIRECT);
	122	if (ret < 0)
	123	return ret;
	124	}
	125
	126	if (unlikely(!dst->lwtstate->orig_output)) {
	127	pr_warn_once("orig_output not set on dst for prog %s\n",
	128	bpf->out.name);
	129	kfree_skb(skb);
	130	return -EINVAL;
131	}
132
133	return dst->lwtstate->orig_output(net, sk, skb);
134	}
135
136	static int xmit_check_hhlen(struct sk_buff *skb)
137	{
138	int hh_len = skb_dst(skb)->dev->hard_header_len;
139
140	if (skb_headroom(skb) < hh_len) {
141	int nhead = HH_DATA_ALIGN(hh_len - skb_headroom(skb));
142
143	if (pskb_expand_head(skb, nhead, 0, GFP_ATOMIC))
144	return -ENOMEM;
145	}
146
147	return 0;
148	}
149
150	static int bpf_xmit(struct sk_buff *skb)
151	{
152	struct dst_entry *dst = skb_dst(skb);
153	struct bpf_lwt *bpf;
154
155	bpf = bpf_lwt_lwtunnel(dst->lwtstate);
156	if (bpf->xmit.prog) {
157	int ret;
158
159	ret = run_lwt_bpf(skb, &bpf->xmit, dst, CAN_REDIRECT);
160	switch (ret) {
161	case BPF_OK:
162	/* If the header was expanded, headroom might be too
163	* small for L2 header to come, expand as needed.
164	*/
165	ret = xmit_check_hhlen(skb);
166	if (unlikely(ret))
167	return ret;
168
169	return LWTUNNEL_XMIT_CONTINUE;
170	case BPF_REDIRECT:
171	return LWTUNNEL_XMIT_DONE;
172	default:
173	return ret;
174	}
175	}
176
177	return LWTUNNEL_XMIT_CONTINUE;
178	}
179
180	static void bpf_lwt_prog_destroy(struct bpf_lwt_prog *prog)
181	{
182	if (prog->prog)
183	bpf_prog_put(prog->prog);
184
185	kfree(prog->name);
186	}
187
188	static void bpf_destroy_state(struct lwtunnel_state *lwt)
189	{
190	struct bpf_lwt *bpf = bpf_lwt_lwtunnel(lwt);
191
192	bpf_lwt_prog_destroy(&bpf->in);
193	bpf_lwt_prog_destroy(&bpf->out);
194	bpf_lwt_prog_destroy(&bpf->xmit);
195	}
196
197	static const struct nla_policy bpf_prog_policy[LWT_BPF_PROG_MAX + 1] = {
198	[LWT_BPF_PROG_FD] = { .type = NLA_U32, },
199	[LWT_BPF_PROG_NAME] = { .type = NLA_NUL_STRING,
200	.len = MAX_PROG_NAME },
201	};
202
203	static int bpf_parse_prog(struct nlattr attr, struct bpf_lwt_prog prog,
204	enum bpf_prog_type type)
205	{
206	struct nlattr *tb[LWT_BPF_PROG_MAX + 1];
207	struct bpf_prog *p;
208	int ret;
209	u32 fd;
210
fceb6435 JB	211	ret = nla_parse_nested(tb, LWT_BPF_PROG_MAX, attr, bpf_prog_policy,
fceb6435 JB	212	NULL);
3a0af8fd TG	213	if (ret < 0)
	214	return ret;
	215
	216	if (!tb[LWT_BPF_PROG_FD] \|\| !tb[LWT_BPF_PROG_NAME])
	217	return -EINVAL;
	218
71eb5255	219	prog->name = nla_memdup(tb[LWT_BPF_PROG_NAME], GFP_ATOMIC);
3a0af8fd TG	220	if (!prog->name)
	221	return -ENOMEM;
	222
	223	fd = nla_get_u32(tb[LWT_BPF_PROG_FD]);
	224	p = bpf_prog_get_type(fd, type);
	225	if (IS_ERR(p))
	226	return PTR_ERR(p);
	227
	228	prog->prog = p;
	229
	230	return 0;
	231	}
	232
	233	static const struct nla_policy bpf_nl_policy[LWT_BPF_MAX + 1] = {
	234	[LWT_BPF_IN] = { .type = NLA_NESTED, },
	235	[LWT_BPF_OUT] = { .type = NLA_NESTED, },
	236	[LWT_BPF_XMIT] = { .type = NLA_NESTED, },
	237	[LWT_BPF_XMIT_HEADROOM] = { .type = NLA_U32 },
	238	};
	239
30357d7d	240	static int bpf_build_state(struct nlattr *nla,
3a0af8fd	241	unsigned int family, const void *cfg,
9ae28727 DA	242	struct lwtunnel_state **ts,
9ae28727 DA	243	struct netlink_ext_ack *extack)
3a0af8fd TG	244	{
	245	struct nlattr *tb[LWT_BPF_MAX + 1];
	246	struct lwtunnel_state *newts;
	247	struct bpf_lwt *bpf;
	248	int ret;
	249
	250	if (family != AF_INET && family != AF_INET6)
	251	return -EAFNOSUPPORT;
	252
9ae28727	253	ret = nla_parse_nested(tb, LWT_BPF_MAX, nla, bpf_nl_policy, extack);
3a0af8fd TG	254	if (ret < 0)
	255	return ret;
	256
	257	if (!tb[LWT_BPF_IN] && !tb[LWT_BPF_OUT] && !tb[LWT_BPF_XMIT])
	258	return -EINVAL;
	259
	260	newts = lwtunnel_state_alloc(sizeof(*bpf));
	261	if (!newts)
	262	return -ENOMEM;
	263
	264	newts->type = LWTUNNEL_ENCAP_BPF;
	265	bpf = bpf_lwt_lwtunnel(newts);
	266
	267	if (tb[LWT_BPF_IN]) {
	268	newts->flags \|= LWTUNNEL_STATE_INPUT_REDIRECT;
	269	ret = bpf_parse_prog(tb[LWT_BPF_IN], &bpf->in,
	270	BPF_PROG_TYPE_LWT_IN);
	271	if (ret < 0)
	272	goto errout;
	273	}
	274
	275	if (tb[LWT_BPF_OUT]) {
	276	newts->flags \|= LWTUNNEL_STATE_OUTPUT_REDIRECT;
	277	ret = bpf_parse_prog(tb[LWT_BPF_OUT], &bpf->out,
	278	BPF_PROG_TYPE_LWT_OUT);
	279	if (ret < 0)
	280	goto errout;
	281	}
	282
	283	if (tb[LWT_BPF_XMIT]) {
	284	newts->flags \|= LWTUNNEL_STATE_XMIT_REDIRECT;
	285	ret = bpf_parse_prog(tb[LWT_BPF_XMIT], &bpf->xmit,
	286	BPF_PROG_TYPE_LWT_XMIT);
	287	if (ret < 0)
	288	goto errout;
	289	}
	290
	291	if (tb[LWT_BPF_XMIT_HEADROOM]) {
	292	u32 headroom = nla_get_u32(tb[LWT_BPF_XMIT_HEADROOM]);
	293
	294	if (headroom > LWT_BPF_MAX_HEADROOM) {
	295	ret = -ERANGE;
	296	goto errout;
	297	}
	298
	299	newts->headroom = headroom;
	300	}
	301
	302	bpf->family = family;
	303	*ts = newts;
	304
	305	return 0;
	306
	307	errout:
	308	bpf_destroy_state(newts);
	309	kfree(newts);
	310	return ret;
	311	}
	312
	313	static int bpf_fill_lwt_prog(struct sk_buff *skb, int attr,
	314	struct bpf_lwt_prog *prog)
	315	{
	316	struct nlattr *nest;
	317
318	if (!prog->prog)
319	return 0;
320
321	nest = nla_nest_start(skb, attr);
322	if (!nest)
323	return -EMSGSIZE;
324
325	if (prog->name &&
326	nla_put_string(skb, LWT_BPF_PROG_NAME, prog->name))
327	return -EMSGSIZE;
328
329	return nla_nest_end(skb, nest);
330	}
331
332	static int bpf_fill_encap_info(struct sk_buff skb, struct lwtunnel_state lwt)
333	{
334	struct bpf_lwt *bpf = bpf_lwt_lwtunnel(lwt);
335
336	if (bpf_fill_lwt_prog(skb, LWT_BPF_IN, &bpf->in) < 0 \|\|
337	bpf_fill_lwt_prog(skb, LWT_BPF_OUT, &bpf->out) < 0 \|\|
338	bpf_fill_lwt_prog(skb, LWT_BPF_XMIT, &bpf->xmit) < 0)
339	return -EMSGSIZE;
340
341	return 0;
342	}
343
344	static int bpf_encap_nlsize(struct lwtunnel_state *lwtstate)
345	{
346	int nest_len = nla_total_size(sizeof(struct nlattr)) +
347	nla_total_size(MAX_PROG_NAME) + /* LWT_BPF_PROG_NAME */
348	0;
349
350	return nest_len + /* LWT_BPF_IN */
351	nest_len + /* LWT_BPF_OUT */
352	nest_len + /* LWT_BPF_XMIT */
353	0;
354	}
355
79471b10	356	static int bpf_lwt_prog_cmp(struct bpf_lwt_prog a, struct bpf_lwt_prog b)
3a0af8fd TG	357	{
	358	/* FIXME:
	359	* The LWT state is currently rebuilt for delete requests which
	360	* results in a new bpf_prog instance. Comparing names for now.
	361	*/
	362	if (!a->name && !b->name)
	363	return 0;
	364
	365	if (!a->name \|\| !b->name)
	366	return 1;
	367
	368	return strcmp(a->name, b->name);
	369	}
	370
	371	static int bpf_encap_cmp(struct lwtunnel_state a, struct lwtunnel_state b)
	372	{
	373	struct bpf_lwt *a_bpf = bpf_lwt_lwtunnel(a);
	374	struct bpf_lwt *b_bpf = bpf_lwt_lwtunnel(b);
	375
	376	return bpf_lwt_prog_cmp(&a_bpf->in, &b_bpf->in) \|\|
	377	bpf_lwt_prog_cmp(&a_bpf->out, &b_bpf->out) \|\|
	378	bpf_lwt_prog_cmp(&a_bpf->xmit, &b_bpf->xmit);
	379	}
	380
	381	static const struct lwtunnel_encap_ops bpf_encap_ops = {
	382	.build_state = bpf_build_state,
	383	.destroy_state = bpf_destroy_state,
	384	.input = bpf_input,
	385	.output = bpf_output,
	386	.xmit = bpf_xmit,
	387	.fill_encap = bpf_fill_encap_info,
	388	.get_encap_size = bpf_encap_nlsize,
	389	.cmp_encap = bpf_encap_cmp,
88ff7334	390	.owner = THIS_MODULE,
3a0af8fd TG	391	};
	392
	393	static int __init bpf_lwt_init(void)
	394	{
	395	return lwtunnel_encap_add_ops(&bpf_encap_ops, LWTUNNEL_ENCAP_BPF);
	396	}
	397
	398	subsys_initcall(bpf_lwt_init)