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("$FreeBSD$"); 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 88 struct 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 104 105 const char *default_eaction_typename = "drop"; 106 static int 107 default_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 */ 118 static int 119 eaction_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 } 127 128 static void 129 eaction_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 } 135 136 static int 137 eaction_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 } 163 164 static struct named_object * 165 eaction_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 } 171 172 static 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 }; 182 183 static int 184 create_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 } 229 230 static void 231 destroy_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 */ 251 static void 252 reset_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 */ 301 int 302 ipfw_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 } 314 315 void 316 ipfw_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 */ 337 uint16_t 338 ipfw_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 */ 355 int 356 ipfw_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 } 374 375 int 376 ipfw_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