1/*-
2 * Copyright (c) 2016 Yandex LLC
3 * Copyright (c) 2016 Andrey V. Elsukov <ae@FreeBSD.org>
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 */
26
27#include <sys/cdefs.h>
28__FBSDID("$FreeBSD: releng/11.0/sys/netpfil/ipfw/ip_fw_eaction.c 300021 2016-05-17 07:47:23Z ae $");
29
30#include <sys/param.h>
31#include <sys/systm.h>
32#include <sys/malloc.h>
33#include <sys/kernel.h>
34#include <sys/hash.h>
35#include <sys/lock.h>
36#include <sys/rwlock.h>
37#include <sys/rmlock.h>
38#include <sys/socket.h>
39#include <sys/socketvar.h>
40#include <sys/queue.h>
41#include <net/pfil.h>
42
43#include <net/if.h>	/* ip_fw.h requires IFNAMSIZ */
44#include <netinet/in.h>
45#include <netinet/ip_var.h>	/* struct ipfw_rule_ref */
46#include <netinet/ip_fw.h>
47
48#include <netpfil/ipfw/ip_fw_private.h>
49
50#include "opt_ipfw.h"
51
52/*
53 * External actions support for ipfw.
54 *
55 * This code provides KPI for implementing loadable modules, that
56 * can provide handlers for external action opcodes in the ipfw's
57 * rules.
58 * Module should implement opcode handler with type ipfw_eaction_t.
59 * This handler will be called by ipfw_chk() function when
60 * O_EXTERNAL_ACTION opcode will be matched. The handler must return
61 * value used as return value in ipfw_chk(), i.e. IP_FW_PASS,
62 * IP_FW_DENY (see ip_fw_private.h).
63 * Also the last argument must be set by handler. If it is zero,
64 * the search continues to the next rule. If it has non zero value,
65 * the search terminates.
66 *
67 * The module that implements external action should register its
68 * handler and name with ipfw_add_eaction() function.
69 * This function will return eaction_id, that can be used by module.
70 *
71 * It is possible to pass some additional information to external
72 * action handler via the O_EXTERNAL_INSTANCE opcode. This opcode
73 * will be next after the O_EXTERNAL_ACTION opcode. cmd->arg1 will
74 * contain index of named object related to instance of external action.
75 *
76 * In case when eaction module uses named instances, it should register
77 * opcode rewriting routines for O_EXTERNAL_INSTANCE opcode. The
78 * classifier callback can look back into O_EXTERNAL_ACTION opcode (it
79 * must be in the (ipfw_insn *)(cmd - 1)). By arg1 from O_EXTERNAL_ACTION
80 * it can deteremine eaction_id and compare it with its own.
81 * The macro IPFW_TLV_EACTION_NAME(eaction_id) can be used to deteremine
82 * the type of named_object related to external action instance.
83 *
84 * On module unload handler should be deregistered with ipfw_del_eaction()
85 * function using known eaction_id.
86 */
87
88struct eaction_obj {
89	struct named_object	no;
90	ipfw_eaction_t		*handler;
91	char			name[64];
92};
93
94#define	EACTION_OBJ(ch, cmd)			\
95    ((struct eaction_obj *)SRV_OBJECT((ch), (cmd)->arg1))
96
97#if 0
98#define	EACTION_DEBUG(fmt, ...)	do {			\
99	printf("%s: " fmt "\n", __func__, ## __VA_ARGS__);	\
100} while (0)
101#else
102#define	EACTION_DEBUG(fmt, ...)
103#endif
104
105const char *default_eaction_typename = "drop";
106static int
107default_eaction(struct ip_fw_chain *ch, struct ip_fw_args *args,
108    ipfw_insn *cmd, int *done)
109{
110
111	*done = 1; /* terminate the search */
112	return (IP_FW_DENY);
113}
114
115/*
116 * Opcode rewriting callbacks.
117 */
118static int
119eaction_classify(ipfw_insn *cmd, uint16_t *puidx, uint8_t *ptype)
120{
121
122	EACTION_DEBUG("opcode %d, arg1 %d", cmd->opcode, cmd->arg1);
123	*puidx = cmd->arg1;
124	*ptype = 0;
125	return (0);
126}
127
128static void
129eaction_update(ipfw_insn *cmd, uint16_t idx)
130{
131
132	cmd->arg1 = idx;
133	EACTION_DEBUG("opcode %d, arg1 -> %d", cmd->opcode, cmd->arg1);
134}
135
136static int
137eaction_findbyname(struct ip_fw_chain *ch, struct tid_info *ti,
138    struct named_object **pno)
139{
140	ipfw_obj_ntlv *ntlv;
141
142	if (ti->tlvs == NULL)
143		return (EINVAL);
144
145	/* Search ntlv in the buffer provided by user */
146	ntlv = ipfw_find_name_tlv_type(ti->tlvs, ti->tlen, ti->uidx,
147	    IPFW_TLV_EACTION);
148	if (ntlv == NULL)
149		return (EINVAL);
150	EACTION_DEBUG("name %s, uidx %u, type %u", ntlv->name,
151	    ti->uidx, ti->type);
152	/*
153	 * Search named object with corresponding name.
154	 * Since eaction objects are global - ignore the set value
155	 * and use zero instead.
156	 */
157	*pno = ipfw_objhash_lookup_name_type(CHAIN_TO_SRV(ch),
158	    0, IPFW_TLV_EACTION, ntlv->name);
159	if (*pno == NULL)
160		return (ESRCH);
161	return (0);
162}
163
164static struct named_object *
165eaction_findbykidx(struct ip_fw_chain *ch, uint16_t idx)
166{
167
168	EACTION_DEBUG("kidx %u", idx);
169	return (ipfw_objhash_lookup_kidx(CHAIN_TO_SRV(ch), idx));
170}
171
172static struct opcode_obj_rewrite eaction_opcodes[] = {
173	{
174		.opcode = O_EXTERNAL_ACTION,
175		.etlv = IPFW_TLV_EACTION,
176		.classifier = eaction_classify,
177		.update = eaction_update,
178		.find_byname = eaction_findbyname,
179		.find_bykidx = eaction_findbykidx,
180	},
181};
182
183static int
184create_eaction_obj(struct ip_fw_chain *ch, ipfw_eaction_t handler,
185    const char *name, uint16_t *eaction_id)
186{
187	struct namedobj_instance *ni;
188	struct eaction_obj *obj;
189
190	IPFW_UH_UNLOCK_ASSERT(ch);
191
192	ni = CHAIN_TO_SRV(ch);
193	obj = malloc(sizeof(*obj), M_IPFW, M_WAITOK | M_ZERO);
194	obj->no.name = obj->name;
195	obj->no.etlv = IPFW_TLV_EACTION;
196	obj->handler = handler;
197	strlcpy(obj->name, name, sizeof(obj->name));
198
199	IPFW_UH_WLOCK(ch);
200	if (ipfw_objhash_lookup_name_type(ni, 0, IPFW_TLV_EACTION,
201	    name) != NULL) {
202		/*
203		 * Object is already created.
204		 * We don't allow eactions with the same name.
205		 */
206		IPFW_UH_WUNLOCK(ch);
207		free(obj, M_IPFW);
208		EACTION_DEBUG("External action with typename "
209		    "'%s' already exists", name);
210		return (EEXIST);
211	}
212	if (ipfw_objhash_alloc_idx(ni, &obj->no.kidx) != 0) {
213		IPFW_UH_WUNLOCK(ch);
214		free(obj, M_IPFW);
215		EACTION_DEBUG("alloc_idx failed");
216		return (ENOSPC);
217	}
218	ipfw_objhash_add(ni, &obj->no);
219	IPFW_WLOCK(ch);
220	SRV_OBJECT(ch, obj->no.kidx) = obj;
221	IPFW_WUNLOCK(ch);
222	obj->no.refcnt++;
223	IPFW_UH_WUNLOCK(ch);
224
225	if (eaction_id != NULL)
226		*eaction_id = obj->no.kidx;
227	return (0);
228}
229
230static void
231destroy_eaction_obj(struct ip_fw_chain *ch, struct named_object *no)
232{
233	struct namedobj_instance *ni;
234	struct eaction_obj *obj;
235
236	IPFW_UH_WLOCK_ASSERT(ch);
237
238	ni = CHAIN_TO_SRV(ch);
239	IPFW_WLOCK(ch);
240	obj = SRV_OBJECT(ch, no->kidx);
241	SRV_OBJECT(ch, no->kidx) = NULL;
242	IPFW_WUNLOCK(ch);
243	ipfw_objhash_del(ni, no);
244	ipfw_objhash_free_idx(ni, no->kidx);
245	free(obj, M_IPFW);
246}
247
248/*
249 * Resets all eaction opcodes to default handlers.
250 */
251static void
252reset_eaction_obj(struct ip_fw_chain *ch, uint16_t eaction_id)
253{
254	struct named_object *no;
255	struct ip_fw *rule;
256	ipfw_insn *cmd;
257	int i;
258
259	IPFW_UH_WLOCK_ASSERT(ch);
260
261	no = ipfw_objhash_lookup_name_type(CHAIN_TO_SRV(ch), 0,
262	    IPFW_TLV_EACTION, default_eaction_typename);
263	if (no == NULL)
264		panic("Default external action handler is not found");
265	if (eaction_id == no->kidx)
266		panic("Wrong eaction_id");
267	EACTION_DEBUG("replace id %u with %u", eaction_id, no->kidx);
268	IPFW_WLOCK(ch);
269	for (i = 0; i < ch->n_rules; i++) {
270		rule = ch->map[i];
271		cmd = ACTION_PTR(rule);
272		if (cmd->opcode != O_EXTERNAL_ACTION)
273			continue;
274		if (cmd->arg1 != eaction_id)
275			continue;
276		cmd->arg1 = no->kidx; /* Set to default id */
277		/*
278		 * XXX: we only bump refcount on default_eaction.
279		 * Refcount on the original object will be just
280		 * ignored on destroy. But on default_eaction it
281		 * will be decremented on rule deletion.
282		 */
283		no->refcnt++;
284		/*
285		 * Since named_object related to this instance will be
286		 * also destroyed, truncate the chain of opcodes to
287		 * remove O_EXTERNAL_INSTANCE opcode.
288		 */
289		if (rule->act_ofs < rule->cmd_len - 1) {
290			EACTION_DEBUG("truncate rule %d", rule->rulenum);
291			rule->cmd_len--;
292		}
293	}
294	IPFW_WUNLOCK(ch);
295}
296
297/*
298 * Initialize external actions framework.
299 * Create object with default eaction handler "drop".
300 */
301int
302ipfw_eaction_init(struct ip_fw_chain *ch, int first)
303{
304	int error;
305
306	error = create_eaction_obj(ch, default_eaction,
307	    default_eaction_typename, NULL);
308	if (error != 0)
309		return (error);
310	IPFW_ADD_OBJ_REWRITER(first, eaction_opcodes);
311	EACTION_DEBUG("External actions support initialized");
312	return (0);
313}
314
315void
316ipfw_eaction_uninit(struct ip_fw_chain *ch, int last)
317{
318	struct namedobj_instance *ni;
319	struct named_object *no;
320
321	ni = CHAIN_TO_SRV(ch);
322
323	IPFW_UH_WLOCK(ch);
324	no = ipfw_objhash_lookup_name_type(ni, 0, IPFW_TLV_EACTION,
325	    default_eaction_typename);
326	if (no != NULL)
327		destroy_eaction_obj(ch, no);
328	IPFW_UH_WUNLOCK(ch);
329	IPFW_DEL_OBJ_REWRITER(last, eaction_opcodes);
330	EACTION_DEBUG("External actions support uninitialized");
331}
332
333/*
334 * Registers external action handler to the global array.
335 * On success it returns eaction id, otherwise - zero.
336 */
337uint16_t
338ipfw_add_eaction(struct ip_fw_chain *ch, ipfw_eaction_t handler,
339    const char *name)
340{
341	uint16_t eaction_id;
342
343	eaction_id = 0;
344	if (ipfw_check_object_name_generic(name) == 0) {
345		create_eaction_obj(ch, handler, name, &eaction_id);
346		EACTION_DEBUG("Registered external action '%s' with id %u",
347		    name, eaction_id);
348	}
349	return (eaction_id);
350}
351
352/*
353 * Deregisters external action handler with id eaction_id.
354 */
355int
356ipfw_del_eaction(struct ip_fw_chain *ch, uint16_t eaction_id)
357{
358	struct named_object *no;
359
360	IPFW_UH_WLOCK(ch);
361	no = ipfw_objhash_lookup_kidx(CHAIN_TO_SRV(ch), eaction_id);
362	if (no == NULL || no->etlv != IPFW_TLV_EACTION) {
363		IPFW_UH_WUNLOCK(ch);
364		return (EINVAL);
365	}
366	if (no->refcnt > 1)
367		reset_eaction_obj(ch, eaction_id);
368	EACTION_DEBUG("External action '%s' with id %u unregistered",
369	    no->name, eaction_id);
370	destroy_eaction_obj(ch, no);
371	IPFW_UH_WUNLOCK(ch);
372	return (0);
373}
374
375int
376ipfw_run_eaction(struct ip_fw_chain *ch, struct ip_fw_args *args,
377    ipfw_insn *cmd, int *done)
378{
379
380	return (EACTION_OBJ(ch, cmd)->handler(ch, args, cmd, done));
381}
382