Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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FreeBSD/Linux Kernel Cross Reference
sys/kern/sysv_ipc.c
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1 /* $NetBSD: sysv_ipc.c,v 1.42 2022/03/27 16:23:08 christos Exp $ */ 2 3 /*- 4 * Copyright (c) 1998, 2007 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * This code is derived from software contributed to The NetBSD Foundation 8 * by Charles M. Hannum. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 22 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 29 * POSSIBILITY OF SUCH DAMAGE. 30 */ 31 32 #include <sys/cdefs.h> 33 __KERNEL_RCSID(0, "$NetBSD: sysv_ipc.c,v 1.42 2022/03/27 16:23:08 christos Exp $"); 34 35 #ifdef _KERNEL_OPT 36 #include "opt_sysv.h" 37 #include "opt_sysvparam.h" 38 #include "opt_compat_netbsd.h" 39 #endif 40 41 #include <sys/syscall.h> 42 #include <sys/syscallargs.h> 43 #include <sys/syscallvar.h> 44 #include <sys/param.h> 45 #include <sys/kernel.h> 46 #include <sys/proc.h> 47 #include <sys/ipc.h> 48 #ifdef SYSVMSG 49 #include <sys/msg.h> 50 #endif 51 #ifdef SYSVSEM 52 #include <sys/sem.h> 53 #endif 54 #ifdef SYSVSHM 55 #include <sys/shm.h> 56 #endif 57 #include <sys/systm.h> 58 #include <sys/kmem.h> 59 #include <sys/module.h> 60 #include <sys/mount.h> 61 #include <sys/vnode.h> 62 #include <sys/stat.h> 63 #include <sys/sysctl.h> 64 #include <sys/kauth.h> 65 #include <sys/compat_stub.h> 66 67 #include <compat/common/compat_sysv_mod.h> /* for sysctl routine vector */ 68 69 /* 70 * Values in support of System V compatible shared memory. XXX 71 * (originally located in sys/conf/param.c) 72 */ 73 #ifdef SYSVSHM 74 #if !defined(SHMMAX) && defined(SHMMAXPGS) 75 #define SHMMAX SHMMAXPGS /* shminit() performs a `*= PAGE_SIZE' */ 76 #elif !defined(SHMMAX) 77 #define SHMMAX 0 78 #endif 79 #ifndef SHMMIN 80 #define SHMMIN 1 81 #endif 82 #ifndef SHMMNI 83 #define SHMMNI 128 /* <64k, see IPCID_TO_IX in ipc.h */ 84 #endif 85 #ifndef SHMSEG 86 #define SHMSEG 128 87 #endif 88 89 struct shminfo shminfo = { 90 SHMMAX, 91 SHMMIN, 92 SHMMNI, 93 SHMSEG, 94 0 95 }; 96 #endif 97 98 /* 99 * Values in support of System V compatible semaphores. 100 */ 101 #ifdef SYSVSEM 102 struct seminfo seminfo = { 103 SEMMAP, /* # of entries in semaphore map */ 104 SEMMNI, /* # of semaphore identifiers */ 105 SEMMNS, /* # of semaphores in system */ 106 SEMMNU, /* # of undo structures in system */ 107 SEMMSL, /* max # of semaphores per id */ 108 SEMOPM, /* max # of operations per semop call */ 109 SEMUME, /* max # of undo entries per process */ 110 SEMUSZ, /* size in bytes of undo structure */ 111 SEMVMX, /* semaphore maximum value */ 112 SEMAEM /* adjust on exit max value */ 113 }; 114 #endif 115 116 /* 117 * Values in support of System V compatible messages. 118 */ 119 #ifdef SYSVMSG 120 struct msginfo msginfo = { 121 MSGMAX, /* max chars in a message */ 122 MSGMNI, /* # of message queue identifiers */ 123 MSGMNB, /* max chars in a queue */ 124 MSGTQL, /* max messages in system */ 125 MSGSSZ, /* size of a message segment */ 126 /* (must be small power of 2 greater than 4) */ 127 MSGSEG /* number of message segments */ 128 }; 129 #endif 130 131 MODULE(MODULE_CLASS_EXEC, sysv_ipc, NULL); 132 133 SYSCTL_SETUP_PROTO(sysctl_ipc_setup); 134 135 static const struct syscall_package sysvipc_syscalls[] = { 136 #if defined(SYSVSHM) 137 { SYS___shmctl50, 0, (sy_call_t *)sys___shmctl50 }, 138 { SYS_shmat, 0, (sy_call_t *)sys_shmat }, 139 { SYS_shmdt, 0, (sy_call_t *)sys_shmdt }, 140 { SYS_shmget, 0, (sy_call_t *)sys_shmget }, 141 #endif /* SYSVSHM */ 142 143 #if defined(SYSVSEM) 144 { SYS_____semctl50, 0, (sy_call_t *)sys_____semctl50 }, 145 { SYS_semget, 0, (sy_call_t *)sys_semget }, 146 { SYS_semop, 0, (sy_call_t *)sys_semop }, 147 { SYS_semconfig, 0, (sy_call_t *)sys_semconfig }, 148 #endif /* SYSVSEM */ 149 150 #if defined(SYSVMSG) 151 { SYS___msgctl50, 0, (sy_call_t *)sys___msgctl50 }, 152 { SYS_msgget, 0, (sy_call_t *)sys_msgget }, 153 { SYS_msgsnd, 0, (sy_call_t *)sys_msgsnd }, 154 { SYS_msgrcv, 0, (sy_call_t *)sys_msgrcv }, 155 #endif /* SYSVMSG */ 156 { 0, 0, NULL } 157 }; 158 159 static int 160 sysv_ipc_modcmd(modcmd_t cmd, void *arg) 161 { 162 int error = 0; 163 164 switch (cmd) { 165 case MODULE_CMD_INIT: 166 /* Set up the kauth listener */ 167 sysvipcinit(); 168 169 /* Link the system calls */ 170 error = syscall_establish(NULL, sysvipc_syscalls); 171 if (error) { 172 sysvipcfini(); 173 return error; 174 } 175 176 /* 177 * Initialize each sub-component, including their 178 * sysctl data 179 */ 180 #ifdef SYSVSHM 181 error = shminit(); 182 if (error != 0) 183 return error; 184 #endif 185 #ifdef SYSVSEM 186 error = seminit(); 187 if (error != 0) { 188 #ifdef SYSVSHM 189 shmfini(); 190 #endif 191 return error; 192 } 193 #endif 194 #ifdef SYSVMSG 195 error = msginit(); 196 if (error != 0) { 197 #ifdef SYSVSEM 198 semfini(); 199 #endif 200 #ifdef SYSVSHM 201 shmfini(); 202 #endif 203 return error; 204 } 205 #endif 206 break; 207 case MODULE_CMD_FINI: 208 /* 209 * Make sure no subcomponents are active. Each one 210 * tells us if it is busy, and if it was _not_ busy, 211 * we assume it has already done its own clean-up. 212 * So we might need to re-init any components that 213 * are successfully fini'd if we find one that is 214 * still busy. 215 */ 216 #ifdef SYSVSHM 217 if (shmfini()) { 218 return EBUSY; 219 } 220 #endif 221 #ifdef SYSVSEM 222 if (semfini()) { 223 #ifdef SYSVSHM 224 shminit(); 225 #endif 226 return EBUSY; 227 } 228 #endif 229 #ifdef SYSVMSG 230 if (msgfini()) { 231 #ifdef SYSVSEM 232 seminit(); 233 #endif 234 #ifdef SYSVSHM 235 shminit(); 236 #endif 237 return EBUSY; 238 } 239 #endif 240 /* Unlink the system calls. */ 241 error = syscall_disestablish(NULL, sysvipc_syscalls); 242 if (error) 243 return error; 244 245 /* Remove the kauth listener */ 246 sysvipcfini(); 247 break; 248 default: 249 return ENOTTY; 250 } 251 return error; 252 } 253 254 static kauth_listener_t sysvipc_listener = NULL; 255 256 static int 257 sysvipc_listener_cb(kauth_cred_t cred, kauth_action_t action, void *cookie, 258 void *arg0, void *arg1, void *arg2, void *arg3) 259 { 260 mode_t mask; 261 struct ipc_perm *perm; 262 int mode; 263 enum kauth_system_req req; 264 265 req = (enum kauth_system_req)(uintptr_t)arg0; 266 267 if (!(action == KAUTH_SYSTEM_SYSVIPC && 268 req == KAUTH_REQ_SYSTEM_SYSVIPC_BYPASS)) 269 return KAUTH_RESULT_DEFER; 270 271 perm = arg1; 272 mode = (int)(uintptr_t)arg2; 273 274 if (mode == IPC_M) { 275 if (kauth_cred_geteuid(cred) == perm->uid || 276 kauth_cred_geteuid(cred) == perm->cuid) 277 return (KAUTH_RESULT_ALLOW); 278 return (KAUTH_RESULT_DEFER); /* EPERM */ 279 } 280 281 mask = 0; 282 283 if (kauth_cred_geteuid(cred) == perm->uid || 284 kauth_cred_geteuid(cred) == perm->cuid) { 285 if (mode & IPC_R) 286 mask |= S_IRUSR; 287 if (mode & IPC_W) 288 mask |= S_IWUSR; 289 return ((perm->mode & mask) == mask ? KAUTH_RESULT_ALLOW : KAUTH_RESULT_DEFER /* EACCES */); 290 } 291 292 if (kauth_cred_groupmember(cred, perm->gid) == 0 || 293 kauth_cred_groupmember(cred, perm->cgid) == 0) { 294 if (mode & IPC_R) 295 mask |= S_IRGRP; 296 if (mode & IPC_W) 297 mask |= S_IWGRP; 298 return ((perm->mode & mask) == mask ? KAUTH_RESULT_ALLOW : KAUTH_RESULT_DEFER /* EACCES */); 299 } 300 301 if (mode & IPC_R) 302 mask |= S_IROTH; 303 if (mode & IPC_W) 304 mask |= S_IWOTH; 305 return ((perm->mode & mask) == mask ? KAUTH_RESULT_ALLOW : KAUTH_RESULT_DEFER /* EACCES */); 306 } 307 308 /* 309 * Check for ipc permission 310 */ 311 312 int 313 ipcperm(kauth_cred_t cred, struct ipc_perm *perm, int mode) 314 { 315 int error; 316 317 error = kauth_authorize_system(cred, KAUTH_SYSTEM_SYSVIPC, 318 KAUTH_REQ_SYSTEM_SYSVIPC_BYPASS, perm, KAUTH_ARG(mode), NULL); 319 if (error == 0) 320 return (0); 321 322 /* Adjust EPERM and EACCES errors until there's a better way to do this. */ 323 if (mode != IPC_M) 324 error = EACCES; 325 326 return error; 327 } 328 329 void 330 sysvipcfini(void) 331 { 332 333 KASSERT(sysvipc_listener != NULL); 334 kauth_unlisten_scope(sysvipc_listener); 335 sysvipc_listener = NULL; 336 } 337 338 void 339 sysvipcinit(void) 340 { 341 342 KASSERT(sysvipc_listener == NULL); 343 344 sysvipc_listener = kauth_listen_scope(KAUTH_SCOPE_SYSTEM, 345 sysvipc_listener_cb, NULL); 346 } 347 348 static int 349 stub_sysvipc50_sysctl(SYSCTLFN_ARGS) 350 { 351 return EPASSTHROUGH; 352 } 353 354 static int 355 sysctl_kern_sysvipc(SYSCTLFN_ARGS) 356 { 357 void *where = oldp; 358 size_t sz, *sizep = oldlenp; 359 #ifdef SYSVMSG 360 struct msg_sysctl_info *msgsi = NULL; 361 #endif 362 #ifdef SYSVSEM 363 struct sem_sysctl_info *semsi = NULL; 364 #endif 365 #ifdef SYSVSHM 366 struct shm_sysctl_info *shmsi = NULL; 367 #endif 368 size_t infosize, dssize, tsize, buflen; 369 void *bf = NULL; 370 char *start; 371 int32_t nds; 372 int i, error, ret; 373 374 /* 375 * If present, call the compat sysctl() code. If it handles the request 376 * completely (either success or error), return. Otherwise fallthrough 377 * to the non-compat sysctl code. 378 */ 379 380 MODULE_HOOK_CALL(sysvipc_sysctl_50_hook, (SYSCTLFN_CALL(rnode)), 381 stub_sysvipc50_sysctl(SYSCTLFN_CALL(rnode)), error); 382 if (error != EPASSTHROUGH) 383 return error; 384 385 if (namelen != 1) 386 return EINVAL; 387 388 start = where; 389 buflen = *sizep; 390 391 switch (*name) { 392 case KERN_SYSVIPC_MSG_INFO: 393 #ifdef SYSVMSG 394 infosize = sizeof(msgsi->msginfo); 395 nds = msginfo.msgmni; 396 dssize = sizeof(msgsi->msgids[0]); 397 break; 398 #else 399 return EINVAL; 400 #endif 401 case KERN_SYSVIPC_SEM_INFO: 402 #ifdef SYSVSEM 403 infosize = sizeof(semsi->seminfo); 404 nds = seminfo.semmni; 405 dssize = sizeof(semsi->semids[0]); 406 break; 407 #else 408 return EINVAL; 409 #endif 410 case KERN_SYSVIPC_SHM_INFO: 411 #ifdef SYSVSHM 412 infosize = sizeof(shmsi->shminfo); 413 nds = shminfo.shmmni; 414 dssize = sizeof(shmsi->shmids[0]); 415 break; 416 #else 417 return EINVAL; 418 #endif 419 default: 420 return EINVAL; 421 } 422 /* 423 * Round infosize to 64 bit boundary if requesting more than just 424 * the info structure or getting the total data size. 425 */ 426 if (where == NULL || *sizep > infosize) 427 infosize = roundup(infosize, sizeof(quad_t)); 428 tsize = infosize + nds * dssize; 429 430 /* Return just the total size required. */ 431 if (where == NULL) { 432 *sizep = tsize; 433 return 0; 434 } 435 436 /* Not enough room for even the info struct. */ 437 if (buflen < infosize) { 438 *sizep = 0; 439 return ENOMEM; 440 } 441 sz = uimin(tsize, buflen); 442 bf = kmem_zalloc(sz, KM_SLEEP); 443 444 switch (*name) { 445 #ifdef SYSVMSG 446 case KERN_SYSVIPC_MSG_INFO: 447 msgsi = (struct msg_sysctl_info *)bf; 448 msgsi->msginfo = msginfo; 449 break; 450 #endif 451 #ifdef SYSVSEM 452 case KERN_SYSVIPC_SEM_INFO: 453 semsi = (struct sem_sysctl_info *)bf; 454 semsi->seminfo = seminfo; 455 break; 456 #endif 457 #ifdef SYSVSHM 458 case KERN_SYSVIPC_SHM_INFO: 459 shmsi = (struct shm_sysctl_info *)bf; 460 shmsi->shminfo = shminfo; 461 break; 462 #endif 463 } 464 buflen -= infosize; 465 466 ret = 0; 467 if (buflen > 0) { 468 /* Fill in the IPC data structures. */ 469 for (i = 0; i < nds; i++) { 470 if (buflen < dssize) { 471 ret = ENOMEM; 472 break; 473 } 474 switch (*name) { 475 #ifdef SYSVMSG 476 case KERN_SYSVIPC_MSG_INFO: 477 mutex_enter(&msgmutex); 478 SYSCTL_FILL_MSG(msqs[i].msq_u, msgsi->msgids[i]); 479 mutex_exit(&msgmutex); 480 break; 481 #endif 482 #ifdef SYSVSEM 483 case KERN_SYSVIPC_SEM_INFO: 484 SYSCTL_FILL_SEM(sema[i], semsi->semids[i]); 485 break; 486 #endif 487 #ifdef SYSVSHM 488 case KERN_SYSVIPC_SHM_INFO: 489 SYSCTL_FILL_SHM(shmsegs[i], shmsi->shmids[i]); 490 break; 491 #endif 492 } 493 buflen -= dssize; 494 } 495 } 496 *sizep -= buflen; 497 error = copyout(bf, start, *sizep); 498 /* If copyout succeeded, use return code set earlier. */ 499 if (error == 0) 500 error = ret; 501 if (bf) 502 kmem_free(bf, sz); 503 return error; 504 } 505 506 SYSCTL_SETUP(sysctl_ipc_setup, "sysctl kern.ipc subtree setup") 507 { 508 509 sysctl_createv(clog, 0, NULL, NULL, 510 CTLFLAG_PERMANENT, 511 CTLTYPE_NODE, "ipc", 512 SYSCTL_DESCR("SysV IPC options"), 513 NULL, 0, NULL, 0, 514 CTL_KERN, KERN_SYSVIPC, CTL_EOL); 515 516 sysctl_createv(clog, 0, NULL, NULL, 517 CTLFLAG_PERMANENT, 518 CTLTYPE_STRUCT, "sysvipc_info", 519 SYSCTL_DESCR("System V style IPC information"), 520 sysctl_kern_sysvipc, 0, NULL, 0, 521 CTL_KERN, KERN_SYSVIPC, KERN_SYSVIPC_INFO, CTL_EOL); 522 }
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