kern_hhook.c revision 251725
1/*- 2 * Copyright (c) 2010 Lawrence Stewart <lstewart@freebsd.org> 3 * Copyright (c) 2010 The FreeBSD Foundation 4 * All rights reserved. 5 * 6 * This software was developed by Lawrence Stewart while studying at the Centre 7 * for Advanced Internet Architectures, Swinburne University of Technology, 8 * made possible in part by grants from the FreeBSD Foundation and Cisco 9 * University Research Program Fund at Community Foundation Silicon Valley. 10 * 11 * Portions of this software were developed at the Centre for Advanced 12 * Internet Architectures, Swinburne University of Technology, Melbourne, 13 * Australia by Lawrence Stewart under sponsorship from the FreeBSD Foundation. 14 * 15 * Redistribution and use in source and binary forms, with or without 16 * modification, are permitted provided that the following conditions 17 * are met: 18 * 1. Redistributions of source code must retain the above copyright 19 * notice, this list of conditions and the following disclaimer. 20 * 2. Redistributions in binary form must reproduce the above copyright 21 * notice, this list of conditions and the following disclaimer in the 22 * documentation and/or other materials provided with the distribution. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34 * SUCH DAMAGE. 35 */ 36 37#include <sys/cdefs.h> 38__FBSDID("$FreeBSD: head/sys/kern/kern_hhook.c 251725 2013-06-14 02:25:40Z lstewart $"); 39 40#include <sys/param.h> 41#include <sys/kernel.h> 42#include <sys/hhook.h> 43#include <sys/khelp.h> 44#include <sys/malloc.h> 45#include <sys/module.h> 46#include <sys/module_khelp.h> 47#include <sys/osd.h> 48#include <sys/queue.h> 49#include <sys/refcount.h> 50#include <sys/systm.h> 51 52#include <net/vnet.h> 53 54struct hhook { 55 hhook_func_t hhk_func; 56 struct helper *hhk_helper; 57 void *hhk_udata; 58 STAILQ_ENTRY(hhook) hhk_next; 59}; 60 61static MALLOC_DEFINE(M_HHOOK, "hhook", "Helper hooks are linked off hhook_head lists"); 62 63LIST_HEAD(hhookheadhead, hhook_head); 64VNET_DEFINE(struct hhookheadhead, hhook_head_list); 65#define V_hhook_head_list VNET(hhook_head_list) 66 67static struct mtx hhook_head_list_lock; 68MTX_SYSINIT(hhookheadlistlock, &hhook_head_list_lock, "hhook_head list lock", 69 MTX_DEF); 70 71/* Private function prototypes. */ 72static void hhook_head_destroy(struct hhook_head *hhh); 73 74#define HHHLIST_LOCK() mtx_lock(&hhook_head_list_lock) 75#define HHHLIST_UNLOCK() mtx_unlock(&hhook_head_list_lock) 76#define HHHLIST_LOCK_ASSERT() mtx_assert(&hhook_head_list_lock, MA_OWNED) 77 78#define HHH_LOCK_INIT(hhh) rm_init(&(hhh)->hhh_lock, "hhook_head rm lock") 79#define HHH_LOCK_DESTROY(hhh) rm_destroy(&(hhh)->hhh_lock) 80#define HHH_WLOCK(hhh) rm_wlock(&(hhh)->hhh_lock) 81#define HHH_WUNLOCK(hhh) rm_wunlock(&(hhh)->hhh_lock) 82#define HHH_RLOCK(hhh, rmpt) rm_rlock(&(hhh)->hhh_lock, (rmpt)) 83#define HHH_RUNLOCK(hhh, rmpt) rm_runlock(&(hhh)->hhh_lock, (rmpt)) 84 85/* 86 * Run all helper hook functions for a given hook point. 87 */ 88void 89hhook_run_hooks(struct hhook_head *hhh, void *ctx_data, struct osd *hosd) 90{ 91 struct hhook *hhk; 92 void *hdata; 93 struct rm_priotracker rmpt; 94 95 KASSERT(hhh->hhh_refcount > 0, ("hhook_head %p refcount is 0", hhh)); 96 97 HHH_RLOCK(hhh, &rmpt); 98 STAILQ_FOREACH(hhk, &hhh->hhh_hooks, hhk_next) { 99 if (hhk->hhk_helper->h_flags & HELPER_NEEDS_OSD) { 100 hdata = osd_get(OSD_KHELP, hosd, hhk->hhk_helper->h_id); 101 if (hdata == NULL) 102 continue; 103 } else 104 hdata = NULL; 105 106 /* 107 * XXXLAS: We currently ignore the int returned by the hook, 108 * but will likely want to handle it in future to allow hhook to 109 * be used like pfil and effect changes at the hhook calling 110 * site e.g. we could define a new hook type of HHOOK_TYPE_PFIL 111 * and standardise what particular return values mean and set 112 * the context data to pass exactly the same information as pfil 113 * hooks currently receive, thus replicating pfil with hhook. 114 */ 115 hhk->hhk_func(hhh->hhh_type, hhh->hhh_id, hhk->hhk_udata, 116 ctx_data, hdata, hosd); 117 } 118 HHH_RUNLOCK(hhh, &rmpt); 119} 120 121/* 122 * Register a new helper hook function with a helper hook point. 123 */ 124int 125hhook_add_hook(struct hhook_head *hhh, struct hookinfo *hki, uint32_t flags) 126{ 127 struct hhook *hhk, *tmp; 128 int error; 129 130 error = 0; 131 132 if (hhh == NULL) 133 return (ENOENT); 134 135 hhk = malloc(sizeof(struct hhook), M_HHOOK, 136 M_ZERO | ((flags & HHOOK_WAITOK) ? M_WAITOK : M_NOWAIT)); 137 138 if (hhk == NULL) 139 return (ENOMEM); 140 141 hhk->hhk_helper = hki->hook_helper; 142 hhk->hhk_func = hki->hook_func; 143 hhk->hhk_udata = hki->hook_udata; 144 145 HHH_WLOCK(hhh); 146 STAILQ_FOREACH(tmp, &hhh->hhh_hooks, hhk_next) { 147 if (tmp->hhk_func == hki->hook_func && 148 tmp->hhk_udata == hki->hook_udata) { 149 /* The helper hook function is already registered. */ 150 error = EEXIST; 151 break; 152 } 153 } 154 155 if (!error) { 156 STAILQ_INSERT_TAIL(&hhh->hhh_hooks, hhk, hhk_next); 157 hhh->hhh_nhooks++; 158 } else 159 free(hhk, M_HHOOK); 160 161 HHH_WUNLOCK(hhh); 162 163 return (error); 164} 165 166/* 167 * Lookup a helper hook point and register a new helper hook function with it. 168 */ 169int 170hhook_add_hook_lookup(struct hookinfo *hki, uint32_t flags) 171{ 172 struct hhook_head *hhh; 173 int error; 174 175 hhh = hhook_head_get(hki->hook_type, hki->hook_id); 176 177 if (hhh == NULL) 178 return (ENOENT); 179 180 error = hhook_add_hook(hhh, hki, flags); 181 hhook_head_release(hhh); 182 183 return (error); 184} 185 186/* 187 * Remove a helper hook function from a helper hook point. 188 */ 189int 190hhook_remove_hook(struct hhook_head *hhh, struct hookinfo *hki) 191{ 192 struct hhook *tmp; 193 194 if (hhh == NULL) 195 return (ENOENT); 196 197 HHH_WLOCK(hhh); 198 STAILQ_FOREACH(tmp, &hhh->hhh_hooks, hhk_next) { 199 if (tmp->hhk_func == hki->hook_func && 200 tmp->hhk_udata == hki->hook_udata) { 201 STAILQ_REMOVE(&hhh->hhh_hooks, tmp, hhook, hhk_next); 202 free(tmp, M_HHOOK); 203 hhh->hhh_nhooks--; 204 break; 205 } 206 } 207 HHH_WUNLOCK(hhh); 208 209 return (0); 210} 211 212/* 213 * Lookup a helper hook point and remove a helper hook function from it. 214 */ 215int 216hhook_remove_hook_lookup(struct hookinfo *hki) 217{ 218 struct hhook_head *hhh; 219 220 hhh = hhook_head_get(hki->hook_type, hki->hook_id); 221 222 if (hhh == NULL) 223 return (ENOENT); 224 225 hhook_remove_hook(hhh, hki); 226 hhook_head_release(hhh); 227 228 return (0); 229} 230 231/* 232 * Register a new helper hook point. 233 */ 234int 235hhook_head_register(int32_t hhook_type, int32_t hhook_id, struct hhook_head **hhh, 236 uint32_t flags) 237{ 238 struct hhook_head *tmphhh; 239 240 tmphhh = hhook_head_get(hhook_type, hhook_id); 241 242 if (tmphhh != NULL) { 243 /* Hook point previously registered. */ 244 hhook_head_release(tmphhh); 245 return (EEXIST); 246 } 247 248 /* XXXLAS: Need to implement support for non-virtualised hooks. */ 249 if ((flags & HHOOK_HEADISINVNET) == 0) { 250 printf("%s: only vnet-style virtualised hooks can be used\n", 251 __func__); 252 return (EINVAL); 253 } 254 255 tmphhh = malloc(sizeof(struct hhook_head), M_HHOOK, 256 M_ZERO | ((flags & HHOOK_WAITOK) ? M_WAITOK : M_NOWAIT)); 257 258 if (tmphhh == NULL) 259 return (ENOMEM); 260 261 tmphhh->hhh_type = hhook_type; 262 tmphhh->hhh_id = hhook_id; 263 tmphhh->hhh_nhooks = 0; 264 STAILQ_INIT(&tmphhh->hhh_hooks); 265 HHH_LOCK_INIT(tmphhh); 266 267 if (hhh != NULL) { 268 refcount_init(&tmphhh->hhh_refcount, 1); 269 *hhh = tmphhh; 270 } else 271 refcount_init(&tmphhh->hhh_refcount, 0); 272 273 if (flags & HHOOK_HEADISINVNET) { 274 tmphhh->hhh_flags |= HHH_ISINVNET; 275 HHHLIST_LOCK(); 276 LIST_INSERT_HEAD(&V_hhook_head_list, tmphhh, hhh_next); 277 HHHLIST_UNLOCK(); 278 } else { 279 /* XXXLAS: Add tmphhh to the non-virtualised list. */ 280 } 281 282 return (0); 283} 284 285static void 286hhook_head_destroy(struct hhook_head *hhh) 287{ 288 struct hhook *tmp, *tmp2; 289 290 HHHLIST_LOCK_ASSERT(); 291 292 LIST_REMOVE(hhh, hhh_next); 293 HHH_WLOCK(hhh); 294 STAILQ_FOREACH_SAFE(tmp, &hhh->hhh_hooks, hhk_next, tmp2) 295 free(tmp, M_HHOOK); 296 HHH_WUNLOCK(hhh); 297 HHH_LOCK_DESTROY(hhh); 298 free(hhh, M_HHOOK); 299} 300 301/* 302 * Remove a helper hook point. 303 */ 304int 305hhook_head_deregister(struct hhook_head *hhh) 306{ 307 int error; 308 309 error = 0; 310 311 HHHLIST_LOCK(); 312 if (hhh == NULL) 313 error = ENOENT; 314 else if (hhh->hhh_refcount > 1) 315 error = EBUSY; 316 else 317 hhook_head_destroy(hhh); 318 HHHLIST_UNLOCK(); 319 320 return (error); 321} 322 323/* 324 * Remove a helper hook point via a hhook_head lookup. 325 */ 326int 327hhook_head_deregister_lookup(int32_t hhook_type, int32_t hhook_id) 328{ 329 struct hhook_head *hhh; 330 int error; 331 332 hhh = hhook_head_get(hhook_type, hhook_id); 333 error = hhook_head_deregister(hhh); 334 335 if (error == EBUSY) 336 hhook_head_release(hhh); 337 338 return (error); 339} 340 341/* 342 * Lookup and return the hhook_head struct associated with the specified type 343 * and id, or NULL if not found. If found, the hhook_head's refcount is bumped. 344 */ 345struct hhook_head * 346hhook_head_get(int32_t hhook_type, int32_t hhook_id) 347{ 348 struct hhook_head *hhh; 349 350 /* XXXLAS: Pick hhook_head_list based on hhook_head flags. */ 351 HHHLIST_LOCK(); 352 LIST_FOREACH(hhh, &V_hhook_head_list, hhh_next) { 353 if (hhh->hhh_type == hhook_type && hhh->hhh_id == hhook_id) { 354 refcount_acquire(&hhh->hhh_refcount); 355 break; 356 } 357 } 358 HHHLIST_UNLOCK(); 359 360 return (hhh); 361} 362 363void 364hhook_head_release(struct hhook_head *hhh) 365{ 366 367 refcount_release(&hhh->hhh_refcount); 368} 369 370/* 371 * Check the hhook_head private flags and return the appropriate public 372 * representation of the flag to the caller. The function is implemented in a 373 * way that allows us to cope with other subsystems becoming virtualised in the 374 * future. 375 */ 376uint32_t 377hhook_head_is_virtualised(struct hhook_head *hhh) 378{ 379 uint32_t ret; 380 381 ret = 0; 382 383 if (hhh != NULL) { 384 if (hhh->hhh_flags & HHH_ISINVNET) 385 ret = HHOOK_HEADISINVNET; 386 } 387 388 return (ret); 389} 390 391uint32_t 392hhook_head_is_virtualised_lookup(int32_t hook_type, int32_t hook_id) 393{ 394 struct hhook_head *hhh; 395 uint32_t ret; 396 397 hhh = hhook_head_get(hook_type, hook_id); 398 399 if (hhh == NULL) 400 return (0); 401 402 ret = hhook_head_is_virtualised(hhh); 403 hhook_head_release(hhh); 404 405 return (ret); 406} 407 408/* 409 * Vnet created and being initialised. 410 */ 411static void 412hhook_vnet_init(const void *unused __unused) 413{ 414 415 LIST_INIT(&V_hhook_head_list); 416} 417 418/* 419 * Vnet being torn down and destroyed. 420 */ 421static void 422hhook_vnet_uninit(const void *unused __unused) 423{ 424 struct hhook_head *hhh, *tmphhh; 425 426 /* 427 * If subsystems which export helper hook points use the hhook KPI 428 * correctly, the loop below should have no work to do because the 429 * subsystem should have already called hhook_head_deregister(). 430 */ 431 HHHLIST_LOCK(); 432 LIST_FOREACH_SAFE(hhh, &V_hhook_head_list, hhh_next, tmphhh) { 433 printf("%s: hhook_head type=%d, id=%d cleanup required\n", 434 __func__, hhh->hhh_type, hhh->hhh_id); 435 hhook_head_destroy(hhh); 436 } 437 HHHLIST_UNLOCK(); 438} 439 440 441/* 442 * When a vnet is created and being initialised, init the V_hhook_head_list. 443 */ 444VNET_SYSINIT(hhook_vnet_init, SI_SUB_PROTO_BEGIN, SI_ORDER_FIRST, 445 hhook_vnet_init, NULL); 446 447/* 448 * The hhook KPI provides a mechanism for subsystems which export helper hook 449 * points to clean up on vnet tear down, but in case the KPI is misused, 450 * provide a function to clean up and free memory for a vnet being destroyed. 451 */ 452VNET_SYSUNINIT(hhook_vnet_uninit, SI_SUB_PROTO_BEGIN, SI_ORDER_FIRST, 453 hhook_vnet_uninit, NULL); 454