1 /* 2 * Implementation of SVID semaphores 3 * 4 * Author: Daniel Boulet 5 * 6 * This software is provided ``AS IS'' without any warranties of any kind. 7 */ 8 9 #include <sys/cdefs.h> 10 __FBSDID("$FreeBSD$"); 11 12 #include "opt_sysvipc.h" 13 14 #include <sys/param.h> 15 #include <sys/systm.h> 16 #include <sys/sysproto.h> 17 #include <sys/eventhandler.h> 18 #include <sys/kernel.h> 19 #include <sys/proc.h> 20 #include <sys/lock.h> 21 #include <sys/mutex.h> 22 #include <sys/sem.h> 23 #include <sys/syscall.h> 24 #include <sys/sysent.h> 25 #include <sys/sysctl.h> 26 #include <sys/malloc.h> 27 #include <sys/jail.h> 28 29 static MALLOC_DEFINE(M_SEM, "sem", "SVID compatible semaphores"); 30 31 #ifdef SEM_DEBUG 32 #define DPRINTF(a) printf a 33 #else 34 #define DPRINTF(a) 35 #endif 36 37 static void seminit(void); 38 static int sysvsem_modload(struct module *, int, void *); 39 static int semunload(void); 40 static void semexit_myhook(void *arg, struct proc *p); 41 static int sysctl_sema(SYSCTL_HANDLER_ARGS); 42 static int semvalid(int semid, struct semid_ds *semaptr); 43 44 #ifndef _SYS_SYSPROTO_H_ 45 struct __semctl_args; 46 int __semctl(struct thread *td, struct __semctl_args *uap); 47 struct semget_args; 48 int semget(struct thread *td, struct semget_args *uap); 49 struct semop_args; 50 int semop(struct thread *td, struct semop_args *uap); 51 #endif 52 53 static struct sem_undo *semu_alloc(struct thread *td); 54 static int semundo_adjust(struct thread *td, struct sem_undo **supptr, 55 int semid, int semnum, int adjval); 56 static void semundo_clear(int semid, int semnum); 57 58 /* XXX casting to (sy_call_t *) is bogus, as usual. */ 59 static sy_call_t *semcalls[] = { 60 (sy_call_t *)__semctl, (sy_call_t *)semget, 61 (sy_call_t *)semop 62 }; 63 64 static struct mtx sem_mtx; /* semaphore global lock */ 65 static int semtot = 0; 66 static struct semid_ds *sema; /* semaphore id pool */ 67 static struct mtx *sema_mtx; /* semaphore id pool mutexes*/ 68 static struct sem *sem; /* semaphore pool */ 69 SLIST_HEAD(, sem_undo) semu_list; /* list of active undo structures */ 70 static int *semu; /* undo structure pool */ 71 static eventhandler_tag semexit_tag; 72 73 #define SEMUNDO_MTX sem_mtx 74 #define SEMUNDO_LOCK() mtx_lock(&SEMUNDO_MTX); 75 #define SEMUNDO_UNLOCK() mtx_unlock(&SEMUNDO_MTX); 76 #define SEMUNDO_LOCKASSERT(how) mtx_assert(&SEMUNDO_MTX, (how)); 77 78 struct sem { 79 u_short semval; /* semaphore value */ 80 pid_t sempid; /* pid of last operation */ 81 u_short semncnt; /* # awaiting semval > cval */ 82 u_short semzcnt; /* # awaiting semval = 0 */ 83 }; 84 85 /* 86 * Undo structure (one per process) 87 */ 88 struct sem_undo { 89 SLIST_ENTRY(sem_undo) un_next; /* ptr to next active undo structure */ 90 struct proc *un_proc; /* owner of this structure */ 91 short un_cnt; /* # of active entries */ 92 struct undo { 93 short un_adjval; /* adjust on exit values */ 94 short un_num; /* semaphore # */ 95 int un_id; /* semid */ 96 } un_ent[1]; /* undo entries */ 97 }; 98 99 /* 100 * Configuration parameters 101 */ 102 #ifndef SEMMNI 103 #define SEMMNI 10 /* # of semaphore identifiers */ 104 #endif 105 #ifndef SEMMNS 106 #define SEMMNS 60 /* # of semaphores in system */ 107 #endif 108 #ifndef SEMUME 109 #define SEMUME 10 /* max # of undo entries per process */ 110 #endif 111 #ifndef SEMMNU 112 #define SEMMNU 30 /* # of undo structures in system */ 113 #endif 114 115 /* shouldn't need tuning */ 116 #ifndef SEMMAP 117 #define SEMMAP 30 /* # of entries in semaphore map */ 118 #endif 119 #ifndef SEMMSL 120 #define SEMMSL SEMMNS /* max # of semaphores per id */ 121 #endif 122 #ifndef SEMOPM 123 #define SEMOPM 100 /* max # of operations per semop call */ 124 #endif 125 126 #define SEMVMX 32767 /* semaphore maximum value */ 127 #define SEMAEM 16384 /* adjust on exit max value */ 128 129 /* 130 * Due to the way semaphore memory is allocated, we have to ensure that 131 * SEMUSZ is properly aligned. 132 */ 133 134 #define SEM_ALIGN(bytes) (((bytes) + (sizeof(long) - 1)) & ~(sizeof(long) - 1)) 135 136 /* actual size of an undo structure */ 137 #define SEMUSZ SEM_ALIGN(offsetof(struct sem_undo, un_ent[SEMUME])) 138 139 /* 140 * Macro to find a particular sem_undo vector 141 */ 142 #define SEMU(ix) \ 143 ((struct sem_undo *)(((intptr_t)semu)+ix * seminfo.semusz)) 144 145 /* 146 * semaphore info struct 147 */ 148 struct seminfo seminfo = { 149 SEMMAP, /* # of entries in semaphore map */ 150 SEMMNI, /* # of semaphore identifiers */ 151 SEMMNS, /* # of semaphores in system */ 152 SEMMNU, /* # of undo structures in system */ 153 SEMMSL, /* max # of semaphores per id */ 154 SEMOPM, /* max # of operations per semop call */ 155 SEMUME, /* max # of undo entries per process */ 156 SEMUSZ, /* size in bytes of undo structure */ 157 SEMVMX, /* semaphore maximum value */ 158 SEMAEM /* adjust on exit max value */ 159 }; 160 161 SYSCTL_DECL(_kern_ipc); 162 SYSCTL_INT(_kern_ipc, OID_AUTO, semmap, CTLFLAG_RW, &seminfo.semmap, 0, ""); 163 SYSCTL_INT(_kern_ipc, OID_AUTO, semmni, CTLFLAG_RD, &seminfo.semmni, 0, ""); 164 SYSCTL_INT(_kern_ipc, OID_AUTO, semmns, CTLFLAG_RD, &seminfo.semmns, 0, ""); 165 SYSCTL_INT(_kern_ipc, OID_AUTO, semmnu, CTLFLAG_RD, &seminfo.semmnu, 0, ""); 166 SYSCTL_INT(_kern_ipc, OID_AUTO, semmsl, CTLFLAG_RW, &seminfo.semmsl, 0, ""); 167 SYSCTL_INT(_kern_ipc, OID_AUTO, semopm, CTLFLAG_RD, &seminfo.semopm, 0, ""); 168 SYSCTL_INT(_kern_ipc, OID_AUTO, semume, CTLFLAG_RD, &seminfo.semume, 0, ""); 169 SYSCTL_INT(_kern_ipc, OID_AUTO, semusz, CTLFLAG_RD, &seminfo.semusz, 0, ""); 170 SYSCTL_INT(_kern_ipc, OID_AUTO, semvmx, CTLFLAG_RW, &seminfo.semvmx, 0, ""); 171 SYSCTL_INT(_kern_ipc, OID_AUTO, semaem, CTLFLAG_RW, &seminfo.semaem, 0, ""); 172 SYSCTL_PROC(_kern_ipc, OID_AUTO, sema, CTLFLAG_RD, 173 NULL, 0, sysctl_sema, "", ""); 174 175 static void 176 seminit(void) 177 { 178 int i; 179 180 TUNABLE_INT_FETCH("kern.ipc.semmap", &seminfo.semmap); 181 TUNABLE_INT_FETCH("kern.ipc.semmni", &seminfo.semmni); 182 TUNABLE_INT_FETCH("kern.ipc.semmns", &seminfo.semmns); 183 TUNABLE_INT_FETCH("kern.ipc.semmnu", &seminfo.semmnu); 184 TUNABLE_INT_FETCH("kern.ipc.semmsl", &seminfo.semmsl); 185 TUNABLE_INT_FETCH("kern.ipc.semopm", &seminfo.semopm); 186 TUNABLE_INT_FETCH("kern.ipc.semume", &seminfo.semume); 187 TUNABLE_INT_FETCH("kern.ipc.semusz", &seminfo.semusz); 188 TUNABLE_INT_FETCH("kern.ipc.semvmx", &seminfo.semvmx); 189 TUNABLE_INT_FETCH("kern.ipc.semaem", &seminfo.semaem); 190 191 sem = malloc(sizeof(struct sem) * seminfo.semmns, M_SEM, M_WAITOK); 192 sema = malloc(sizeof(struct semid_ds) * seminfo.semmni, M_SEM, 193 M_WAITOK); 194 sema_mtx = malloc(sizeof(struct mtx) * seminfo.semmni, M_SEM, 195 M_WAITOK | M_ZERO); 196 semu = malloc(seminfo.semmnu * seminfo.semusz, M_SEM, M_WAITOK); 197 198 for (i = 0; i < seminfo.semmni; i++) { 199 sema[i].sem_base = 0; 200 sema[i].sem_perm.mode = 0; 201 } 202 for (i = 0; i < seminfo.semmni; i++) 203 mtx_init(&sema_mtx[i], "semid", NULL, MTX_DEF); 204 for (i = 0; i < seminfo.semmnu; i++) { 205 struct sem_undo *suptr = SEMU(i); 206 suptr->un_proc = NULL; 207 } 208 SLIST_INIT(&semu_list); 209 mtx_init(&sem_mtx, "sem", NULL, MTX_DEF); 210 semexit_tag = EVENTHANDLER_REGISTER(process_exit, semexit_myhook, NULL, 211 EVENTHANDLER_PRI_ANY); 212 } 213 214 static int 215 semunload(void) 216 { 217 int i; 218 219 if (semtot != 0) 220 return (EBUSY); 221 222 EVENTHANDLER_DEREGISTER(process_exit, semexit_tag); 223 free(sem, M_SEM); 224 free(sema, M_SEM); 225 free(semu, M_SEM); 226 for (i = 0; i < seminfo.semmni; i++) 227 mtx_destroy(&sema_mtx[i]); 228 mtx_destroy(&sem_mtx); 229 return (0); 230 } 231 232 static int 233 sysvsem_modload(struct module *module, int cmd, void *arg) 234 { 235 int error = 0; 236 237 switch (cmd) { 238 case MOD_LOAD: 239 seminit(); 240 break; 241 case MOD_UNLOAD: 242 error = semunload(); 243 break; 244 case MOD_SHUTDOWN: 245 break; 246 default: 247 error = EINVAL; 248 break; 249 } 250 return (error); 251 } 252 253 static moduledata_t sysvsem_mod = { 254 "sysvsem", 255 &sysvsem_modload, 256 NULL 257 }; 258 259 SYSCALL_MODULE_HELPER(semsys); 260 SYSCALL_MODULE_HELPER(__semctl); 261 SYSCALL_MODULE_HELPER(semget); 262 SYSCALL_MODULE_HELPER(semop); 263 264 DECLARE_MODULE(sysvsem, sysvsem_mod, 265 SI_SUB_SYSV_SEM, SI_ORDER_FIRST); 266 MODULE_VERSION(sysvsem, 1); 267 268 /* 269 * Entry point for all SEM calls 270 * 271 * MPSAFE 272 */ 273 int 274 semsys(td, uap) 275 struct thread *td; 276 /* XXX actually varargs. */ 277 struct semsys_args /* { 278 u_int which; 279 int a2; 280 int a3; 281 int a4; 282 int a5; 283 } */ *uap; 284 { 285 int error; 286 287 if (!jail_sysvipc_allowed && jailed(td->td_ucred)) 288 return (ENOSYS); 289 if (uap->which >= sizeof(semcalls)/sizeof(semcalls[0])) 290 return (EINVAL); 291 error = (*semcalls[uap->which])(td, &uap->a2); 292 return (error); 293 } 294 295 /* 296 * Allocate a new sem_undo structure for a process 297 * (returns ptr to structure or NULL if no more room) 298 */ 299 300 static struct sem_undo * 301 semu_alloc(td) 302 struct thread *td; 303 { 304 int i; 305 struct sem_undo *suptr; 306 struct sem_undo **supptr; 307 int attempt; 308 309 SEMUNDO_LOCKASSERT(MA_OWNED); 310 /* 311 * Try twice to allocate something. 312 * (we'll purge any empty structures after the first pass so 313 * two passes are always enough) 314 */ 315 316 for (attempt = 0; attempt < 2; attempt++) { 317 /* 318 * Look for a free structure. 319 * Fill it in and return it if we find one. 320 */ 321 322 for (i = 0; i < seminfo.semmnu; i++) { 323 suptr = SEMU(i); 324 if (suptr->un_proc == NULL) { 325 SLIST_INSERT_HEAD(&semu_list, suptr, un_next); 326 suptr->un_cnt = 0; 327 suptr->un_proc = td->td_proc; 328 return(suptr); 329 } 330 } 331 332 /* 333 * We didn't find a free one, if this is the first attempt 334 * then try to free some structures. 335 */ 336 337 if (attempt == 0) { 338 /* All the structures are in use - try to free some */ 339 int did_something = 0; 340 341 SLIST_FOREACH_PREVPTR(suptr, supptr, &semu_list, 342 un_next) { 343 if (suptr->un_cnt == 0) { 344 suptr->un_proc = NULL; 345 did_something = 1; 346 *supptr = SLIST_NEXT(suptr, un_next); 347 } 348 } 349 350 /* If we didn't free anything then just give-up */ 351 if (!did_something) 352 return(NULL); 353 } else { 354 /* 355 * The second pass failed even though we freed 356 * something after the first pass! 357 * This is IMPOSSIBLE! 358 */ 359 panic("semu_alloc - second attempt failed"); 360 } 361 } 362 return (NULL); 363 } 364 365 /* 366 * Adjust a particular entry for a particular proc 367 */ 368 369 static int 370 semundo_adjust(td, supptr, semid, semnum, adjval) 371 struct thread *td; 372 struct sem_undo **supptr; 373 int semid, semnum; 374 int adjval; 375 { 376 struct proc *p = td->td_proc; 377 struct sem_undo *suptr; 378 struct undo *sunptr; 379 int i; 380 381 SEMUNDO_LOCKASSERT(MA_OWNED); 382 /* Look for and remember the sem_undo if the caller doesn't provide 383 it */ 384 385 suptr = *supptr; 386 if (suptr == NULL) { 387 SLIST_FOREACH(suptr, &semu_list, un_next) { 388 if (suptr->un_proc == p) { 389 *supptr = suptr; 390 break; 391 } 392 } 393 if (suptr == NULL) { 394 if (adjval == 0) 395 return(0); 396 suptr = semu_alloc(td); 397 if (suptr == NULL) 398 return(ENOSPC); 399 *supptr = suptr; 400 } 401 } 402 403 /* 404 * Look for the requested entry and adjust it (delete if adjval becomes 405 * 0). 406 */ 407 sunptr = &suptr->un_ent[0]; 408 for (i = 0; i < suptr->un_cnt; i++, sunptr++) { 409 if (sunptr->un_id != semid || sunptr->un_num != semnum) 410 continue; 411 if (adjval != 0) { 412 adjval += sunptr->un_adjval; 413 if (adjval > seminfo.semaem || adjval < -seminfo.semaem) 414 return (ERANGE); 415 } 416 sunptr->un_adjval = adjval; 417 if (sunptr->un_adjval == 0) { 418 suptr->un_cnt--; 419 if (i < suptr->un_cnt) 420 suptr->un_ent[i] = 421 suptr->un_ent[suptr->un_cnt]; 422 } 423 return(0); 424 } 425 426 /* Didn't find the right entry - create it */ 427 if (adjval == 0) 428 return(0); 429 if (adjval > seminfo.semaem || adjval < -seminfo.semaem) 430 return (ERANGE); 431 if (suptr->un_cnt != seminfo.semume) { 432 sunptr = &suptr->un_ent[suptr->un_cnt]; 433 suptr->un_cnt++; 434 sunptr->un_adjval = adjval; 435 sunptr->un_id = semid; sunptr->un_num = semnum; 436 } else 437 return(EINVAL); 438 return(0); 439 } 440 441 static void 442 semundo_clear(semid, semnum) 443 int semid, semnum; 444 { 445 struct sem_undo *suptr; 446 447 SEMUNDO_LOCKASSERT(MA_OWNED); 448 SLIST_FOREACH(suptr, &semu_list, un_next) { 449 struct undo *sunptr = &suptr->un_ent[0]; 450 int i = 0; 451 452 while (i < suptr->un_cnt) { 453 if (sunptr->un_id == semid) { 454 if (semnum == -1 || sunptr->un_num == semnum) { 455 suptr->un_cnt--; 456 if (i < suptr->un_cnt) { 457 suptr->un_ent[i] = 458 suptr->un_ent[suptr->un_cnt]; 459 continue; 460 } 461 } 462 if (semnum != -1) 463 break; 464 } 465 i++, sunptr++; 466 } 467 } 468 } 469 470 static int 471 semvalid(semid, semaptr) 472 int semid; 473 struct semid_ds *semaptr; 474 { 475 476 return ((semaptr->sem_perm.mode & SEM_ALLOC) == 0 || 477 semaptr->sem_perm.seq != IPCID_TO_SEQ(semid) ? EINVAL : 0); 478 } 479 480 /* 481 * Note that the user-mode half of this passes a union, not a pointer 482 */ 483 #ifndef _SYS_SYSPROTO_H_ 484 struct __semctl_args { 485 int semid; 486 int semnum; 487 int cmd; 488 union semun *arg; 489 }; 490 #endif 491 492 /* 493 * MPSAFE 494 */ 495 int 496 __semctl(td, uap) 497 struct thread *td; 498 struct __semctl_args *uap; 499 { 500 int semid = uap->semid; 501 int semnum = uap->semnum; 502 int cmd = uap->cmd; 503 u_short *array; 504 union semun *arg = uap->arg; 505 union semun real_arg; 506 struct ucred *cred = td->td_ucred; 507 int i, rval, error; 508 struct semid_ds sbuf; 509 struct semid_ds *semaptr; 510 struct mtx *sema_mtxp; 511 u_short usval, count; 512 513 DPRINTF(("call to semctl(%d, %d, %d, 0x%x)\n", 514 semid, semnum, cmd, arg)); 515 if (!jail_sysvipc_allowed && jailed(td->td_ucred)) 516 return (ENOSYS); 517 518 array = NULL; 519 520 switch(cmd) { 521 case SEM_STAT: 522 if (semid < 0 || semid >= seminfo.semmni) 523 return (EINVAL); 524 if ((error = copyin(arg, &real_arg, sizeof(real_arg))) != 0) 525 return (error); 526 semaptr = &sema[semid]; 527 sema_mtxp = &sema_mtx[semid]; 528 mtx_lock(sema_mtxp); 529 if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0 ) { 530 error = EINVAL; 531 goto done2; 532 } 533 if ((error = ipcperm(td, &semaptr->sem_perm, IPC_R))) 534 goto done2; 535 mtx_unlock(sema_mtxp); 536 error = copyout(semaptr, real_arg.buf, sizeof(struct semid_ds)); 537 rval = IXSEQ_TO_IPCID(semid,semaptr->sem_perm); 538 if (error == 0) 539 td->td_retval[0] = rval; 540 return (error); 541 } 542 543 semid = IPCID_TO_IX(semid); 544 if (semid < 0 || semid >= seminfo.semmni) 545 return (EINVAL); 546 547 semaptr = &sema[semid]; 548 sema_mtxp = &sema_mtx[semid]; 549 550 error = 0; 551 rval = 0; 552 553 switch (cmd) { 554 case IPC_RMID: 555 mtx_lock(sema_mtxp); 556 if ((error = semvalid(uap->semid, semaptr)) != 0) 557 goto done2; 558 if ((error = ipcperm(td, &semaptr->sem_perm, IPC_M))) 559 goto done2; 560 semaptr->sem_perm.cuid = cred->cr_uid; 561 semaptr->sem_perm.uid = cred->cr_uid; 562 semtot -= semaptr->sem_nsems; 563 for (i = semaptr->sem_base - sem; i < semtot; i++) 564 sem[i] = sem[i + semaptr->sem_nsems]; 565 for (i = 0; i < seminfo.semmni; i++) { 566 if ((sema[i].sem_perm.mode & SEM_ALLOC) && 567 sema[i].sem_base > semaptr->sem_base) 568 sema[i].sem_base -= semaptr->sem_nsems; 569 } 570 semaptr->sem_perm.mode = 0; 571 SEMUNDO_LOCK(); 572 semundo_clear(semid, -1); 573 SEMUNDO_UNLOCK(); 574 wakeup(semaptr); 575 break; 576 577 case IPC_SET: 578 if ((error = copyin(arg, &real_arg, sizeof(real_arg))) != 0) 579 goto done2; 580 if ((error = copyin(real_arg.buf, &sbuf, sizeof(sbuf))) != 0) 581 goto done2; 582 mtx_lock(sema_mtxp); 583 if ((error = semvalid(uap->semid, semaptr)) != 0) 584 goto done2; 585 if ((error = ipcperm(td, &semaptr->sem_perm, IPC_M))) 586 goto done2; 587 semaptr->sem_perm.uid = sbuf.sem_perm.uid; 588 semaptr->sem_perm.gid = sbuf.sem_perm.gid; 589 semaptr->sem_perm.mode = (semaptr->sem_perm.mode & ~0777) | 590 (sbuf.sem_perm.mode & 0777); 591 semaptr->sem_ctime = time_second; 592 break; 593 594 case IPC_STAT: 595 if ((error = copyin(arg, &real_arg, sizeof(real_arg))) != 0) 596 goto done2; 597 mtx_lock(sema_mtxp); 598 if ((error = semvalid(uap->semid, semaptr)) != 0) 599 goto done2; 600 if ((error = ipcperm(td, &semaptr->sem_perm, IPC_R))) 601 goto done2; 602 sbuf = *semaptr; 603 mtx_unlock(sema_mtxp); 604 error = copyout(semaptr, real_arg.buf, 605 sizeof(struct semid_ds)); 606 break; 607 608 case GETNCNT: 609 mtx_lock(sema_mtxp); 610 if ((error = semvalid(uap->semid, semaptr)) != 0) 611 goto done2; 612 if ((error = ipcperm(td, &semaptr->sem_perm, IPC_R))) 613 goto done2; 614 if (semnum < 0 || semnum >= semaptr->sem_nsems) { 615 error = EINVAL; 616 goto done2; 617 } 618 rval = semaptr->sem_base[semnum].semncnt; 619 break; 620 621 case GETPID: 622 mtx_lock(sema_mtxp); 623 if ((error = semvalid(uap->semid, semaptr)) != 0) 624 goto done2; 625 if ((error = ipcperm(td, &semaptr->sem_perm, IPC_R))) 626 goto done2; 627 if (semnum < 0 || semnum >= semaptr->sem_nsems) { 628 error = EINVAL; 629 goto done2; 630 } 631 rval = semaptr->sem_base[semnum].sempid; 632 break; 633 634 case GETVAL: 635 mtx_lock(sema_mtxp); 636 if ((error = semvalid(uap->semid, semaptr)) != 0) 637 goto done2; 638 if ((error = ipcperm(td, &semaptr->sem_perm, IPC_R))) 639 goto done2; 640 if (semnum < 0 || semnum >= semaptr->sem_nsems) { 641 error = EINVAL; 642 goto done2; 643 } 644 rval = semaptr->sem_base[semnum].semval; 645 break; 646 647 case GETALL: 648 if ((error = copyin(arg, &real_arg, sizeof(real_arg))) != 0) 649 goto done2; 650 array = malloc(sizeof(*array) * semaptr->sem_nsems, M_TEMP, 651 M_WAITOK); 652 mtx_lock(sema_mtxp); 653 if ((error = semvalid(uap->semid, semaptr)) != 0) 654 goto done2; 655 if ((error = ipcperm(td, &semaptr->sem_perm, IPC_R))) 656 goto done2; 657 for (i = 0; i < semaptr->sem_nsems; i++) 658 array[i] = semaptr->sem_base[i].semval; 659 mtx_unlock(sema_mtxp); 660 error = copyout(array, real_arg.array, 661 i * sizeof(real_arg.array[0])); 662 break; 663 664 case GETZCNT: 665 mtx_lock(sema_mtxp); 666 if ((error = semvalid(uap->semid, semaptr)) != 0) 667 goto done2; 668 if ((error = ipcperm(td, &semaptr->sem_perm, IPC_R))) 669 goto done2; 670 if (semnum < 0 || semnum >= semaptr->sem_nsems) { 671 error = EINVAL; 672 goto done2; 673 } 674 rval = semaptr->sem_base[semnum].semzcnt; 675 break; 676 677 case SETVAL: 678 if ((error = copyin(arg, &real_arg, sizeof(real_arg))) != 0) 679 goto done2; 680 mtx_lock(sema_mtxp); 681 if ((error = semvalid(uap->semid, semaptr)) != 0) 682 goto done2; 683 if ((error = ipcperm(td, &semaptr->sem_perm, IPC_W))) 684 goto done2; 685 if (semnum < 0 || semnum >= semaptr->sem_nsems) { 686 error = EINVAL; 687 goto done2; 688 } 689 if (real_arg.val < 0 || real_arg.val > seminfo.semvmx) { 690 error = ERANGE; 691 goto done2; 692 } 693 semaptr->sem_base[semnum].semval = real_arg.val; 694 SEMUNDO_LOCK(); 695 semundo_clear(semid, semnum); 696 SEMUNDO_UNLOCK(); 697 wakeup(semaptr); 698 break; 699 700 case SETALL: 701 mtx_lock(sema_mtxp); 702 raced: 703 if ((error = semvalid(uap->semid, semaptr)) != 0) 704 goto done2; 705 count = semaptr->sem_nsems; 706 mtx_unlock(sema_mtxp); 707 if ((error = copyin(arg, &real_arg, sizeof(real_arg))) != 0) 708 goto done2; 709 array = malloc(sizeof(*array) * count, M_TEMP, M_WAITOK); 710 copyin(real_arg.array, array, count * sizeof(*array)); 711 if (error) 712 break; 713 mtx_lock(sema_mtxp); 714 if ((error = semvalid(uap->semid, semaptr)) != 0) 715 goto done2; 716 /* we could have raced? */ 717 if (count != semaptr->sem_nsems) { 718 free(array, M_TEMP); 719 array = NULL; 720 goto raced; 721 } 722 if ((error = ipcperm(td, &semaptr->sem_perm, IPC_W))) 723 goto done2; 724 for (i = 0; i < semaptr->sem_nsems; i++) { 725 usval = array[i]; 726 if (usval > seminfo.semvmx) { 727 error = ERANGE; 728 break; 729 } 730 semaptr->sem_base[i].semval = usval; 731 } 732 SEMUNDO_LOCK(); 733 semundo_clear(semid, -1); 734 SEMUNDO_UNLOCK(); 735 wakeup(semaptr); 736 break; 737 738 default: 739 error = EINVAL; 740 break; 741 } 742 743 if (error == 0) 744 td->td_retval[0] = rval; 745 done2: 746 if (mtx_owned(sema_mtxp)) 747 mtx_unlock(sema_mtxp); 748 if (array != NULL) 749 free(array, M_TEMP); 750 return(error); 751 } 752 753 #ifndef _SYS_SYSPROTO_H_ 754 struct semget_args { 755 key_t key; 756 int nsems; 757 int semflg; 758 }; 759 #endif 760 761 /* 762 * MPSAFE 763 */ 764 int 765 semget(td, uap) 766 struct thread *td; 767 struct semget_args *uap; 768 { 769 int semid, error = 0; 770 int key = uap->key; 771 int nsems = uap->nsems; 772 int semflg = uap->semflg; 773 struct ucred *cred = td->td_ucred; 774 775 DPRINTF(("semget(0x%x, %d, 0%o)\n", key, nsems, semflg)); 776 if (!jail_sysvipc_allowed && jailed(td->td_ucred)) 777 return (ENOSYS); 778 779 mtx_lock(&Giant); 780 if (key != IPC_PRIVATE) { 781 for (semid = 0; semid < seminfo.semmni; semid++) { 782 if ((sema[semid].sem_perm.mode & SEM_ALLOC) && 783 sema[semid].sem_perm.key == key) 784 break; 785 } 786 if (semid < seminfo.semmni) { 787 DPRINTF(("found public key\n")); 788 if ((error = ipcperm(td, &sema[semid].sem_perm, 789 semflg & 0700))) { 790 goto done2; 791 } 792 if (nsems > 0 && sema[semid].sem_nsems < nsems) { 793 DPRINTF(("too small\n")); 794 error = EINVAL; 795 goto done2; 796 } 797 if ((semflg & IPC_CREAT) && (semflg & IPC_EXCL)) { 798 DPRINTF(("not exclusive\n")); 799 error = EEXIST; 800 goto done2; 801 } 802 goto found; 803 } 804 } 805 806 DPRINTF(("need to allocate the semid_ds\n")); 807 if (key == IPC_PRIVATE || (semflg & IPC_CREAT)) { 808 if (nsems <= 0 || nsems > seminfo.semmsl) { 809 DPRINTF(("nsems out of range (0<%d<=%d)\n", nsems, 810 seminfo.semmsl)); 811 error = EINVAL; 812 goto done2; 813 } 814 if (nsems > seminfo.semmns - semtot) { 815 DPRINTF(( 816 "not enough semaphores left (need %d, got %d)\n", 817 nsems, seminfo.semmns - semtot)); 818 error = ENOSPC; 819 goto done2; 820 } 821 for (semid = 0; semid < seminfo.semmni; semid++) { 822 if ((sema[semid].sem_perm.mode & SEM_ALLOC) == 0) 823 break; 824 } 825 if (semid == seminfo.semmni) { 826 DPRINTF(("no more semid_ds's available\n")); 827 error = ENOSPC; 828 goto done2; 829 } 830 DPRINTF(("semid %d is available\n", semid)); 831 sema[semid].sem_perm.key = key; 832 sema[semid].sem_perm.cuid = cred->cr_uid; 833 sema[semid].sem_perm.uid = cred->cr_uid; 834 sema[semid].sem_perm.cgid = cred->cr_gid; 835 sema[semid].sem_perm.gid = cred->cr_gid; 836 sema[semid].sem_perm.mode = (semflg & 0777) | SEM_ALLOC; 837 sema[semid].sem_perm.seq = 838 (sema[semid].sem_perm.seq + 1) & 0x7fff; 839 sema[semid].sem_nsems = nsems; 840 sema[semid].sem_otime = 0; 841 sema[semid].sem_ctime = time_second; 842 sema[semid].sem_base = &sem[semtot]; 843 semtot += nsems; 844 bzero(sema[semid].sem_base, 845 sizeof(sema[semid].sem_base[0])*nsems); 846 DPRINTF(("sembase = 0x%x, next = 0x%x\n", sema[semid].sem_base, 847 &sem[semtot])); 848 } else { 849 DPRINTF(("didn't find it and wasn't asked to create it\n")); 850 error = ENOENT; 851 goto done2; 852 } 853 854 found: 855 td->td_retval[0] = IXSEQ_TO_IPCID(semid, sema[semid].sem_perm); 856 done2: 857 mtx_unlock(&Giant); 858 return (error); 859 } 860 861 #ifndef _SYS_SYSPROTO_H_ 862 struct semop_args { 863 int semid; 864 struct sembuf *sops; 865 size_t nsops; 866 }; 867 #endif 868 869 /* 870 * MPSAFE 871 */ 872 int 873 semop(td, uap) 874 struct thread *td; 875 struct semop_args *uap; 876 { 877 int semid = uap->semid; 878 size_t nsops = uap->nsops; 879 struct sembuf *sops; 880 struct semid_ds *semaptr; 881 struct sembuf *sopptr = 0; 882 struct sem *semptr = 0; 883 struct sem_undo *suptr; 884 struct mtx *sema_mtxp; 885 size_t i, j, k; 886 int error; 887 int do_wakeup, do_undos; 888 889 DPRINTF(("call to semop(%d, 0x%x, %u)\n", semid, sops, nsops)); 890 891 if (!jail_sysvipc_allowed && jailed(td->td_ucred)) 892 return (ENOSYS); 893 894 semid = IPCID_TO_IX(semid); /* Convert back to zero origin */ 895 896 if (semid < 0 || semid >= seminfo.semmni) 897 return (EINVAL); 898 899 /* Allocate memory for sem_ops */ 900 if (nsops > seminfo.semopm) { 901 DPRINTF(("too many sops (max=%d, nsops=%d)\n", seminfo.semopm, 902 nsops)); 903 return (E2BIG); 904 } 905 sops = malloc(nsops * sizeof(sops[0]), M_SEM, M_WAITOK); 906 if ((error = copyin(uap->sops, sops, nsops * sizeof(sops[0]))) != 0) { 907 DPRINTF(("error = %d from copyin(%08x, %08x, %d)\n", error, 908 uap->sops, sops, nsops * sizeof(sops[0]))); 909 free(sops, M_SEM); 910 return (error); 911 } 912 913 semaptr = &sema[semid]; 914 sema_mtxp = &sema_mtx[semid]; 915 mtx_lock(sema_mtxp); 916 if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0) { 917 error = EINVAL; 918 goto done2; 919 } 920 if (semaptr->sem_perm.seq != IPCID_TO_SEQ(uap->semid)) { 921 error = EINVAL; 922 goto done2; 923 } 924 /* 925 * Initial pass thru sops to see what permissions are needed. 926 * Also perform any checks that don't need repeating on each 927 * attempt to satisfy the request vector. 928 */ 929 j = 0; /* permission needed */ 930 do_undos = 0; 931 for (i = 0; i < nsops; i++) { 932 sopptr = &sops[i]; 933 if (sopptr->sem_num >= semaptr->sem_nsems) { 934 error = EFBIG; 935 goto done2; 936 } 937 if (sopptr->sem_flg & SEM_UNDO && sopptr->sem_op != 0) 938 do_undos = 1; 939 j |= (sopptr->sem_op == 0) ? SEM_R : SEM_A; 940 } 941 942 if ((error = ipcperm(td, &semaptr->sem_perm, j))) { 943 DPRINTF(("error = %d from ipaccess\n", error)); 944 goto done2; 945 } 946 947 /* 948 * Loop trying to satisfy the vector of requests. 949 * If we reach a point where we must wait, any requests already 950 * performed are rolled back and we go to sleep until some other 951 * process wakes us up. At this point, we start all over again. 952 * 953 * This ensures that from the perspective of other tasks, a set 954 * of requests is atomic (never partially satisfied). 955 */ 956 for (;;) { 957 do_wakeup = 0; 958 error = 0; /* error return if necessary */ 959 960 for (i = 0; i < nsops; i++) { 961 sopptr = &sops[i]; 962 semptr = &semaptr->sem_base[sopptr->sem_num]; 963 964 DPRINTF(( 965 "semop: semaptr=%x, sem_base=%x, " 966 "semptr=%x, sem[%d]=%d : op=%d, flag=%s\n", 967 semaptr, semaptr->sem_base, semptr, 968 sopptr->sem_num, semptr->semval, sopptr->sem_op, 969 (sopptr->sem_flg & IPC_NOWAIT) ? 970 "nowait" : "wait")); 971 972 if (sopptr->sem_op < 0) { 973 if (semptr->semval + sopptr->sem_op < 0) { 974 DPRINTF(("semop: can't do it now\n")); 975 break; 976 } else { 977 semptr->semval += sopptr->sem_op; 978 if (semptr->semval == 0 && 979 semptr->semzcnt > 0) 980 do_wakeup = 1; 981 } 982 } else if (sopptr->sem_op == 0) { 983 if (semptr->semval != 0) { 984 DPRINTF(("semop: not zero now\n")); 985 break; 986 } 987 } else if (semptr->semval + sopptr->sem_op > 988 seminfo.semvmx) { 989 error = ERANGE; 990 break; 991 } else { 992 if (semptr->semncnt > 0) 993 do_wakeup = 1; 994 semptr->semval += sopptr->sem_op; 995 } 996 } 997 998 /* 999 * Did we get through the entire vector? 1000 */ 1001 if (i >= nsops) 1002 goto done; 1003 1004 /* 1005 * No ... rollback anything that we've already done 1006 */ 1007 DPRINTF(("semop: rollback 0 through %d\n", i-1)); 1008 for (j = 0; j < i; j++) 1009 semaptr->sem_base[sops[j].sem_num].semval -= 1010 sops[j].sem_op; 1011 1012 /* If we detected an error, return it */ 1013 if (error != 0) 1014 goto done2; 1015 1016 /* 1017 * If the request that we couldn't satisfy has the 1018 * NOWAIT flag set then return with EAGAIN. 1019 */ 1020 if (sopptr->sem_flg & IPC_NOWAIT) { 1021 error = EAGAIN; 1022 goto done2; 1023 } 1024 1025 if (sopptr->sem_op == 0) 1026 semptr->semzcnt++; 1027 else 1028 semptr->semncnt++; 1029 1030 DPRINTF(("semop: good night!\n")); 1031 error = msleep(semaptr, sema_mtxp, (PZERO - 4) | PCATCH, 1032 "semwait", 0); 1033 DPRINTF(("semop: good morning (error=%d)!\n", error)); 1034 1035 if (error != 0) { 1036 error = EINTR; 1037 goto done2; 1038 } 1039 DPRINTF(("semop: good morning!\n")); 1040 1041 /* 1042 * Make sure that the semaphore still exists 1043 */ 1044 if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0 || 1045 semaptr->sem_perm.seq != IPCID_TO_SEQ(uap->semid)) { 1046 error = EIDRM; 1047 goto done2; 1048 } 1049 1050 /* 1051 * The semaphore is still alive. Readjust the count of 1052 * waiting processes. 1053 */ 1054 if (sopptr->sem_op == 0) 1055 semptr->semzcnt--; 1056 else 1057 semptr->semncnt--; 1058 } 1059 1060 done: 1061 /* 1062 * Process any SEM_UNDO requests. 1063 */ 1064 if (do_undos) { 1065 SEMUNDO_LOCK(); 1066 suptr = NULL; 1067 for (i = 0; i < nsops; i++) { 1068 /* 1069 * We only need to deal with SEM_UNDO's for non-zero 1070 * op's. 1071 */ 1072 int adjval; 1073 1074 if ((sops[i].sem_flg & SEM_UNDO) == 0) 1075 continue; 1076 adjval = sops[i].sem_op; 1077 if (adjval == 0) 1078 continue; 1079 error = semundo_adjust(td, &suptr, semid, 1080 sops[i].sem_num, -adjval); 1081 if (error == 0) 1082 continue; 1083 1084 /* 1085 * Oh-Oh! We ran out of either sem_undo's or undo's. 1086 * Rollback the adjustments to this point and then 1087 * rollback the semaphore ups and down so we can return 1088 * with an error with all structures restored. We 1089 * rollback the undo's in the exact reverse order that 1090 * we applied them. This guarantees that we won't run 1091 * out of space as we roll things back out. 1092 */ 1093 for (j = 0; j < i; j++) { 1094 k = i - j - 1; 1095 if ((sops[k].sem_flg & SEM_UNDO) == 0) 1096 continue; 1097 adjval = sops[k].sem_op; 1098 if (adjval == 0) 1099 continue; 1100 if (semundo_adjust(td, &suptr, semid, 1101 sops[k].sem_num, adjval) != 0) 1102 panic("semop - can't undo undos"); 1103 } 1104 1105 for (j = 0; j < nsops; j++) 1106 semaptr->sem_base[sops[j].sem_num].semval -= 1107 sops[j].sem_op; 1108 1109 DPRINTF(("error = %d from semundo_adjust\n", error)); 1110 SEMUNDO_UNLOCK(); 1111 goto done2; 1112 } /* loop through the sops */ 1113 SEMUNDO_UNLOCK(); 1114 } /* if (do_undos) */ 1115 1116 /* We're definitely done - set the sempid's and time */ 1117 for (i = 0; i < nsops; i++) { 1118 sopptr = &sops[i]; 1119 semptr = &semaptr->sem_base[sopptr->sem_num]; 1120 semptr->sempid = td->td_proc->p_pid; 1121 } 1122 semaptr->sem_otime = time_second; 1123 1124 /* 1125 * Do a wakeup if any semaphore was up'd whilst something was 1126 * sleeping on it. 1127 */ 1128 if (do_wakeup) { 1129 DPRINTF(("semop: doing wakeup\n")); 1130 wakeup(semaptr); 1131 DPRINTF(("semop: back from wakeup\n")); 1132 } 1133 DPRINTF(("semop: done\n")); 1134 td->td_retval[0] = 0; 1135 done2: 1136 mtx_unlock(sema_mtxp); 1137 free(sops, M_SEM); 1138 return (error); 1139 } 1140 1141 /* 1142 * Go through the undo structures for this process and apply the adjustments to 1143 * semaphores. 1144 */ 1145 static void 1146 semexit_myhook(arg, p) 1147 void *arg; 1148 struct proc *p; 1149 { 1150 struct sem_undo *suptr; 1151 struct sem_undo **supptr; 1152 1153 /* 1154 * Go through the chain of undo vectors looking for one 1155 * associated with this process. 1156 */ 1157 SEMUNDO_LOCK(); 1158 SLIST_FOREACH_PREVPTR(suptr, supptr, &semu_list, un_next) { 1159 if (suptr->un_proc == p) 1160 break; 1161 } 1162 SEMUNDO_UNLOCK(); 1163 1164 if (suptr == NULL) 1165 return; 1166 1167 DPRINTF(("proc @%08x has undo structure with %d entries\n", p, 1168 suptr->un_cnt)); 1169 1170 /* 1171 * If there are any active undo elements then process them. 1172 */ 1173 if (suptr->un_cnt > 0) { 1174 int ix; 1175 1176 for (ix = 0; ix < suptr->un_cnt; ix++) { 1177 int semid = suptr->un_ent[ix].un_id; 1178 int semnum = suptr->un_ent[ix].un_num; 1179 int adjval = suptr->un_ent[ix].un_adjval; 1180 struct semid_ds *semaptr; 1181 struct mtx *sema_mtxp; 1182 1183 semaptr = &sema[semid]; 1184 sema_mtxp = &sema_mtx[semid]; 1185 mtx_lock(sema_mtxp); 1186 SEMUNDO_LOCK(); 1187 if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0) 1188 panic("semexit - semid not allocated"); 1189 if (semnum >= semaptr->sem_nsems) 1190 panic("semexit - semnum out of range"); 1191 1192 DPRINTF(( 1193 "semexit: %08x id=%d num=%d(adj=%d) ; sem=%d\n", 1194 suptr->un_proc, suptr->un_ent[ix].un_id, 1195 suptr->un_ent[ix].un_num, 1196 suptr->un_ent[ix].un_adjval, 1197 semaptr->sem_base[semnum].semval)); 1198 1199 if (adjval < 0) { 1200 if (semaptr->sem_base[semnum].semval < -adjval) 1201 semaptr->sem_base[semnum].semval = 0; 1202 else 1203 semaptr->sem_base[semnum].semval += 1204 adjval; 1205 } else 1206 semaptr->sem_base[semnum].semval += adjval; 1207 1208 wakeup(semaptr); 1209 DPRINTF(("semexit: back from wakeup\n")); 1210 mtx_unlock(sema_mtxp); 1211 SEMUNDO_UNLOCK(); 1212 } 1213 } 1214 1215 /* 1216 * Deallocate the undo vector. 1217 */ 1218 DPRINTF(("removing vector\n")); 1219 suptr->un_proc = NULL; 1220 *supptr = SLIST_NEXT(suptr, un_next); 1221 } 1222 1223 static int 1224 sysctl_sema(SYSCTL_HANDLER_ARGS) 1225 { 1226 1227 return (SYSCTL_OUT(req, sema, 1228 sizeof(struct semid_ds) * seminfo.semmni)); 1229 } 1230