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/module.h> 22 #include <sys/mutex.h> 23 #include <sys/sem.h> 24 #include <sys/syscall.h> 25 #include <sys/sysent.h> 26 #include <sys/sysctl.h> 27 #include <sys/malloc.h> 28 #include <sys/jail.h> 29 30 static MALLOC_DEFINE(M_SEM, "sem", "SVID compatible semaphores"); 31 32 #ifdef SEM_DEBUG 33 #define DPRINTF(a) printf a 34 #else 35 #define DPRINTF(a) 36 #endif 37 38 static void seminit(void); 39 static int sysvsem_modload(struct module *, int, void *); 40 static int semunload(void); 41 static void semexit_myhook(void *arg, struct proc *p); 42 static int sysctl_sema(SYSCTL_HANDLER_ARGS); 43 static int semvalid(int semid, struct semid_kernel *semakptr); 44 45 #ifndef _SYS_SYSPROTO_H_ 46 struct __semctl_args; 47 int __semctl(struct thread *td, struct __semctl_args *uap); 48 struct semget_args; 49 int semget(struct thread *td, struct semget_args *uap); 50 struct semop_args; 51 int semop(struct thread *td, struct semop_args *uap); 52 #endif 53 54 static struct sem_undo *semu_alloc(struct thread *td); 55 static int semundo_adjust(struct thread *td, struct sem_undo **supptr, 56 int semid, int semnum, int adjval); 57 static void semundo_clear(int semid, int semnum); 58 59 /* XXX casting to (sy_call_t *) is bogus, as usual. */ 60 static sy_call_t *semcalls[] = { 61 (sy_call_t *)__semctl, (sy_call_t *)semget, 62 (sy_call_t *)semop 63 }; 64 65 static struct mtx sem_mtx; /* semaphore global lock */ 66 static int semtot = 0; 67 static struct semid_kernel *sema; /* semaphore id pool */ 68 static struct mtx *sema_mtx; /* semaphore id pool mutexes*/ 69 static struct sem *sem; /* semaphore pool */ 70 SLIST_HEAD(, sem_undo) semu_list; /* list of active undo structures */ 71 static int *semu; /* undo structure pool */ 72 static eventhandler_tag semexit_tag; 73 74 #define SEMUNDO_MTX sem_mtx 75 #define SEMUNDO_LOCK() mtx_lock(&SEMUNDO_MTX); 76 #define SEMUNDO_UNLOCK() mtx_unlock(&SEMUNDO_MTX); 77 #define SEMUNDO_LOCKASSERT(how) mtx_assert(&SEMUNDO_MTX, (how)); 78 79 struct sem { 80 u_short semval; /* semaphore value */ 81 pid_t sempid; /* pid of last operation */ 82 u_short semncnt; /* # awaiting semval > cval */ 83 u_short semzcnt; /* # awaiting semval = 0 */ 84 }; 85 86 /* 87 * Undo structure (one per process) 88 */ 89 struct sem_undo { 90 SLIST_ENTRY(sem_undo) un_next; /* ptr to next active undo structure */ 91 struct proc *un_proc; /* owner of this structure */ 92 short un_cnt; /* # of active entries */ 93 struct undo { 94 short un_adjval; /* adjust on exit values */ 95 short un_num; /* semaphore # */ 96 int un_id; /* semid */ 97 } un_ent[1]; /* undo entries */ 98 }; 99 100 /* 101 * Configuration parameters 102 */ 103 #ifndef SEMMNI 104 #define SEMMNI 10 /* # of semaphore identifiers */ 105 #endif 106 #ifndef SEMMNS 107 #define SEMMNS 60 /* # of semaphores in system */ 108 #endif 109 #ifndef SEMUME 110 #define SEMUME 10 /* max # of undo entries per process */ 111 #endif 112 #ifndef SEMMNU 113 #define SEMMNU 30 /* # of undo structures in system */ 114 #endif 115 116 /* shouldn't need tuning */ 117 #ifndef SEMMAP 118 #define SEMMAP 30 /* # of entries in semaphore map */ 119 #endif 120 #ifndef SEMMSL 121 #define SEMMSL SEMMNS /* max # of semaphores per id */ 122 #endif 123 #ifndef SEMOPM 124 #define SEMOPM 100 /* max # of operations per semop call */ 125 #endif 126 127 #define SEMVMX 32767 /* semaphore maximum value */ 128 #define SEMAEM 16384 /* adjust on exit max value */ 129 130 /* 131 * Due to the way semaphore memory is allocated, we have to ensure that 132 * SEMUSZ is properly aligned. 133 */ 134 135 #define SEM_ALIGN(bytes) (((bytes) + (sizeof(long) - 1)) & ~(sizeof(long) - 1)) 136 137 /* actual size of an undo structure */ 138 #define SEMUSZ SEM_ALIGN(offsetof(struct sem_undo, un_ent[SEMUME])) 139 140 /* 141 * Macro to find a particular sem_undo vector 142 */ 143 #define SEMU(ix) \ 144 ((struct sem_undo *)(((intptr_t)semu)+ix * seminfo.semusz)) 145 146 /* 147 * semaphore info struct 148 */ 149 struct seminfo seminfo = { 150 SEMMAP, /* # of entries in semaphore map */ 151 SEMMNI, /* # of semaphore identifiers */ 152 SEMMNS, /* # of semaphores in system */ 153 SEMMNU, /* # of undo structures in system */ 154 SEMMSL, /* max # of semaphores per id */ 155 SEMOPM, /* max # of operations per semop call */ 156 SEMUME, /* max # of undo entries per process */ 157 SEMUSZ, /* size in bytes of undo structure */ 158 SEMVMX, /* semaphore maximum value */ 159 SEMAEM /* adjust on exit max value */ 160 }; 161 162 SYSCTL_DECL(_kern_ipc); 163 SYSCTL_INT(_kern_ipc, OID_AUTO, semmap, CTLFLAG_RW, &seminfo.semmap, 0, ""); 164 SYSCTL_INT(_kern_ipc, OID_AUTO, semmni, CTLFLAG_RDTUN, &seminfo.semmni, 0, ""); 165 SYSCTL_INT(_kern_ipc, OID_AUTO, semmns, CTLFLAG_RDTUN, &seminfo.semmns, 0, ""); 166 SYSCTL_INT(_kern_ipc, OID_AUTO, semmnu, CTLFLAG_RDTUN, &seminfo.semmnu, 0, ""); 167 SYSCTL_INT(_kern_ipc, OID_AUTO, semmsl, CTLFLAG_RW, &seminfo.semmsl, 0, ""); 168 SYSCTL_INT(_kern_ipc, OID_AUTO, semopm, CTLFLAG_RDTUN, &seminfo.semopm, 0, ""); 169 SYSCTL_INT(_kern_ipc, OID_AUTO, semume, CTLFLAG_RDTUN, &seminfo.semume, 0, ""); 170 SYSCTL_INT(_kern_ipc, OID_AUTO, semusz, CTLFLAG_RDTUN, &seminfo.semusz, 0, ""); 171 SYSCTL_INT(_kern_ipc, OID_AUTO, semvmx, CTLFLAG_RW, &seminfo.semvmx, 0, ""); 172 SYSCTL_INT(_kern_ipc, OID_AUTO, semaem, CTLFLAG_RW, &seminfo.semaem, 0, ""); 173 SYSCTL_PROC(_kern_ipc, OID_AUTO, sema, CTLFLAG_RD, 174 NULL, 0, sysctl_sema, "", ""); 175 176 static void 177 seminit(void) 178 { 179 int i; 180 181 TUNABLE_INT_FETCH("kern.ipc.semmap", &seminfo.semmap); 182 TUNABLE_INT_FETCH("kern.ipc.semmni", &seminfo.semmni); 183 TUNABLE_INT_FETCH("kern.ipc.semmns", &seminfo.semmns); 184 TUNABLE_INT_FETCH("kern.ipc.semmnu", &seminfo.semmnu); 185 TUNABLE_INT_FETCH("kern.ipc.semmsl", &seminfo.semmsl); 186 TUNABLE_INT_FETCH("kern.ipc.semopm", &seminfo.semopm); 187 TUNABLE_INT_FETCH("kern.ipc.semume", &seminfo.semume); 188 TUNABLE_INT_FETCH("kern.ipc.semusz", &seminfo.semusz); 189 TUNABLE_INT_FETCH("kern.ipc.semvmx", &seminfo.semvmx); 190 TUNABLE_INT_FETCH("kern.ipc.semaem", &seminfo.semaem); 191 192 sem = malloc(sizeof(struct sem) * seminfo.semmns, M_SEM, M_WAITOK); 193 sema = malloc(sizeof(struct semid_kernel) * seminfo.semmni, M_SEM, 194 M_WAITOK); 195 sema_mtx = malloc(sizeof(struct mtx) * seminfo.semmni, M_SEM, 196 M_WAITOK | M_ZERO); 197 semu = malloc(seminfo.semmnu * seminfo.semusz, M_SEM, M_WAITOK); 198 199 for (i = 0; i < seminfo.semmni; i++) { 200 sema[i].u.sem_base = 0; 201 sema[i].u.sem_perm.mode = 0; 202 sema[i].u.sem_perm.seq = 0; 203 } 204 for (i = 0; i < seminfo.semmni; i++) 205 mtx_init(&sema_mtx[i], "semid", NULL, MTX_DEF); 206 for (i = 0; i < seminfo.semmnu; i++) { 207 struct sem_undo *suptr = SEMU(i); 208 suptr->un_proc = NULL; 209 } 210 SLIST_INIT(&semu_list); 211 mtx_init(&sem_mtx, "sem", NULL, MTX_DEF); 212 semexit_tag = EVENTHANDLER_REGISTER(process_exit, semexit_myhook, NULL, 213 EVENTHANDLER_PRI_ANY); 214 } 215 216 static int 217 semunload(void) 218 { 219 int i; 220 221 if (semtot != 0) 222 return (EBUSY); 223 224 EVENTHANDLER_DEREGISTER(process_exit, semexit_tag); 225 free(sem, M_SEM); 226 free(sema, M_SEM); 227 free(semu, M_SEM); 228 for (i = 0; i < seminfo.semmni; i++) 229 mtx_destroy(&sema_mtx[i]); 230 mtx_destroy(&sem_mtx); 231 return (0); 232 } 233 234 static int 235 sysvsem_modload(struct module *module, int cmd, void *arg) 236 { 237 int error = 0; 238 239 switch (cmd) { 240 case MOD_LOAD: 241 seminit(); 242 break; 243 case MOD_UNLOAD: 244 error = semunload(); 245 break; 246 case MOD_SHUTDOWN: 247 break; 248 default: 249 error = EINVAL; 250 break; 251 } 252 return (error); 253 } 254 255 static moduledata_t sysvsem_mod = { 256 "sysvsem", 257 &sysvsem_modload, 258 NULL 259 }; 260 261 SYSCALL_MODULE_HELPER(semsys); 262 SYSCALL_MODULE_HELPER(__semctl); 263 SYSCALL_MODULE_HELPER(semget); 264 SYSCALL_MODULE_HELPER(semop); 265 266 DECLARE_MODULE(sysvsem, sysvsem_mod, 267 SI_SUB_SYSV_SEM, SI_ORDER_FIRST); 268 MODULE_VERSION(sysvsem, 1); 269 270 /* 271 * Entry point for all SEM calls 272 * 273 * MPSAFE 274 */ 275 int 276 semsys(td, uap) 277 struct thread *td; 278 /* XXX actually varargs. */ 279 struct semsys_args /* { 280 int which; 281 int a2; 282 int a3; 283 int a4; 284 int a5; 285 } */ *uap; 286 { 287 int error; 288 289 if (!jail_sysvipc_allowed && jailed(td->td_ucred)) 290 return (ENOSYS); 291 if (uap->which < 0 || 292 uap->which >= sizeof(semcalls)/sizeof(semcalls[0])) 293 return (EINVAL); 294 error = (*semcalls[uap->which])(td, &uap->a2); 295 return (error); 296 } 297 298 /* 299 * Allocate a new sem_undo structure for a process 300 * (returns ptr to structure or NULL if no more room) 301 */ 302 303 static struct sem_undo * 304 semu_alloc(td) 305 struct thread *td; 306 { 307 int i; 308 struct sem_undo *suptr; 309 struct sem_undo **supptr; 310 int attempt; 311 312 SEMUNDO_LOCKASSERT(MA_OWNED); 313 /* 314 * Try twice to allocate something. 315 * (we'll purge an empty structure after the first pass so 316 * two passes are always enough) 317 */ 318 319 for (attempt = 0; attempt < 2; attempt++) { 320 /* 321 * Look for a free structure. 322 * Fill it in and return it if we find one. 323 */ 324 325 for (i = 0; i < seminfo.semmnu; i++) { 326 suptr = SEMU(i); 327 if (suptr->un_proc == NULL) { 328 SLIST_INSERT_HEAD(&semu_list, suptr, un_next); 329 suptr->un_cnt = 0; 330 suptr->un_proc = td->td_proc; 331 return(suptr); 332 } 333 } 334 335 /* 336 * We didn't find a free one, if this is the first attempt 337 * then try to free a structure. 338 */ 339 340 if (attempt == 0) { 341 /* All the structures are in use - try to free one */ 342 int did_something = 0; 343 344 SLIST_FOREACH_PREVPTR(suptr, supptr, &semu_list, 345 un_next) { 346 if (suptr->un_cnt == 0) { 347 suptr->un_proc = NULL; 348 did_something = 1; 349 *supptr = SLIST_NEXT(suptr, un_next); 350 break; 351 } 352 } 353 354 /* If we didn't free anything then just give-up */ 355 if (!did_something) 356 return(NULL); 357 } else { 358 /* 359 * The second pass failed even though we freed 360 * something after the first pass! 361 * This is IMPOSSIBLE! 362 */ 363 panic("semu_alloc - second attempt failed"); 364 } 365 } 366 return (NULL); 367 } 368 369 /* 370 * Adjust a particular entry for a particular proc 371 */ 372 373 static int 374 semundo_adjust(td, supptr, semid, semnum, adjval) 375 struct thread *td; 376 struct sem_undo **supptr; 377 int semid, semnum; 378 int adjval; 379 { 380 struct proc *p = td->td_proc; 381 struct sem_undo *suptr; 382 struct undo *sunptr; 383 int i; 384 385 SEMUNDO_LOCKASSERT(MA_OWNED); 386 /* Look for and remember the sem_undo if the caller doesn't provide 387 it */ 388 389 suptr = *supptr; 390 if (suptr == NULL) { 391 SLIST_FOREACH(suptr, &semu_list, un_next) { 392 if (suptr->un_proc == p) { 393 *supptr = suptr; 394 break; 395 } 396 } 397 if (suptr == NULL) { 398 if (adjval == 0) 399 return(0); 400 suptr = semu_alloc(td); 401 if (suptr == NULL) 402 return(ENOSPC); 403 *supptr = suptr; 404 } 405 } 406 407 /* 408 * Look for the requested entry and adjust it (delete if adjval becomes 409 * 0). 410 */ 411 sunptr = &suptr->un_ent[0]; 412 for (i = 0; i < suptr->un_cnt; i++, sunptr++) { 413 if (sunptr->un_id != semid || sunptr->un_num != semnum) 414 continue; 415 if (adjval != 0) { 416 adjval += sunptr->un_adjval; 417 if (adjval > seminfo.semaem || adjval < -seminfo.semaem) 418 return (ERANGE); 419 } 420 sunptr->un_adjval = adjval; 421 if (sunptr->un_adjval == 0) { 422 suptr->un_cnt--; 423 if (i < suptr->un_cnt) 424 suptr->un_ent[i] = 425 suptr->un_ent[suptr->un_cnt]; 426 } 427 return(0); 428 } 429 430 /* Didn't find the right entry - create it */ 431 if (adjval == 0) 432 return(0); 433 if (adjval > seminfo.semaem || adjval < -seminfo.semaem) 434 return (ERANGE); 435 if (suptr->un_cnt != seminfo.semume) { 436 sunptr = &suptr->un_ent[suptr->un_cnt]; 437 suptr->un_cnt++; 438 sunptr->un_adjval = adjval; 439 sunptr->un_id = semid; sunptr->un_num = semnum; 440 } else 441 return(EINVAL); 442 return(0); 443 } 444 445 static void 446 semundo_clear(semid, semnum) 447 int semid, semnum; 448 { 449 struct sem_undo *suptr; 450 451 SEMUNDO_LOCKASSERT(MA_OWNED); 452 SLIST_FOREACH(suptr, &semu_list, un_next) { 453 struct undo *sunptr = &suptr->un_ent[0]; 454 int i = 0; 455 456 while (i < suptr->un_cnt) { 457 if (sunptr->un_id == semid) { 458 if (semnum == -1 || sunptr->un_num == semnum) { 459 suptr->un_cnt--; 460 if (i < suptr->un_cnt) { 461 suptr->un_ent[i] = 462 suptr->un_ent[suptr->un_cnt]; 463 continue; 464 } 465 } 466 if (semnum != -1) 467 break; 468 } 469 i++, sunptr++; 470 } 471 } 472 } 473 474 static int 475 semvalid(semid, semakptr) 476 int semid; 477 struct semid_kernel *semakptr; 478 { 479 480 return ((semakptr->u.sem_perm.mode & SEM_ALLOC) == 0 || 481 semakptr->u.sem_perm.seq != IPCID_TO_SEQ(semid) ? EINVAL : 0); 482 } 483 484 /* 485 * Note that the user-mode half of this passes a union, not a pointer 486 */ 487 #ifndef _SYS_SYSPROTO_H_ 488 struct __semctl_args { 489 int semid; 490 int semnum; 491 int cmd; 492 union semun *arg; 493 }; 494 #endif 495 496 /* 497 * MPSAFE 498 */ 499 int 500 __semctl(td, uap) 501 struct thread *td; 502 struct __semctl_args *uap; 503 { 504 int semid = uap->semid; 505 int semnum = uap->semnum; 506 int cmd = uap->cmd; 507 u_short *array; 508 union semun *arg = uap->arg; 509 union semun real_arg; 510 struct ucred *cred = td->td_ucred; 511 int i, rval, error; 512 struct semid_ds sbuf; 513 struct semid_kernel *semakptr; 514 struct mtx *sema_mtxp; 515 u_short usval, count; 516 517 DPRINTF(("call to semctl(%d, %d, %d, 0x%x)\n", 518 semid, semnum, cmd, arg)); 519 if (!jail_sysvipc_allowed && jailed(td->td_ucred)) 520 return (ENOSYS); 521 522 array = NULL; 523 524 switch(cmd) { 525 case SEM_STAT: 526 if (semid < 0 || semid >= seminfo.semmni) 527 return (EINVAL); 528 if ((error = copyin(arg, &real_arg, sizeof(real_arg))) != 0) 529 return (error); 530 semakptr = &sema[semid]; 531 sema_mtxp = &sema_mtx[semid]; 532 mtx_lock(sema_mtxp); 533 if ((semakptr->u.sem_perm.mode & SEM_ALLOC) == 0) { 534 error = EINVAL; 535 goto done2; 536 } 537 if ((error = ipcperm(td, &semakptr->u.sem_perm, IPC_R))) 538 goto done2; 539 mtx_unlock(sema_mtxp); 540 error = copyout(&semakptr->u, real_arg.buf, 541 sizeof(struct semid_ds)); 542 rval = IXSEQ_TO_IPCID(semid, semakptr->u.sem_perm); 543 if (error == 0) 544 td->td_retval[0] = rval; 545 return (error); 546 } 547 548 semid = IPCID_TO_IX(semid); 549 if (semid < 0 || semid >= seminfo.semmni) 550 return (EINVAL); 551 552 semakptr = &sema[semid]; 553 sema_mtxp = &sema_mtx[semid]; 554 555 error = 0; 556 rval = 0; 557 558 switch (cmd) { 559 case IPC_RMID: 560 mtx_lock(sema_mtxp); 561 if ((error = semvalid(uap->semid, semakptr)) != 0) 562 goto done2; 563 if ((error = ipcperm(td, &semakptr->u.sem_perm, IPC_M))) 564 goto done2; 565 semakptr->u.sem_perm.cuid = cred->cr_uid; 566 semakptr->u.sem_perm.uid = cred->cr_uid; 567 semtot -= semakptr->u.sem_nsems; 568 for (i = semakptr->u.sem_base - sem; i < semtot; i++) 569 sem[i] = sem[i + semakptr->u.sem_nsems]; 570 for (i = 0; i < seminfo.semmni; i++) { 571 if ((sema[i].u.sem_perm.mode & SEM_ALLOC) && 572 sema[i].u.sem_base > semakptr->u.sem_base) 573 sema[i].u.sem_base -= semakptr->u.sem_nsems; 574 } 575 semakptr->u.sem_perm.mode = 0; 576 SEMUNDO_LOCK(); 577 semundo_clear(semid, -1); 578 SEMUNDO_UNLOCK(); 579 wakeup(semakptr); 580 break; 581 582 case IPC_SET: 583 if ((error = copyin(arg, &real_arg, sizeof(real_arg))) != 0) 584 goto done2; 585 if ((error = copyin(real_arg.buf, &sbuf, sizeof(sbuf))) != 0) 586 goto done2; 587 mtx_lock(sema_mtxp); 588 if ((error = semvalid(uap->semid, semakptr)) != 0) 589 goto done2; 590 if ((error = ipcperm(td, &semakptr->u.sem_perm, IPC_M))) 591 goto done2; 592 semakptr->u.sem_perm.uid = sbuf.sem_perm.uid; 593 semakptr->u.sem_perm.gid = sbuf.sem_perm.gid; 594 semakptr->u.sem_perm.mode = (semakptr->u.sem_perm.mode & 595 ~0777) | (sbuf.sem_perm.mode & 0777); 596 semakptr->u.sem_ctime = time_second; 597 break; 598 599 case IPC_STAT: 600 if ((error = copyin(arg, &real_arg, sizeof(real_arg))) != 0) 601 goto done2; 602 mtx_lock(sema_mtxp); 603 if ((error = semvalid(uap->semid, semakptr)) != 0) 604 goto done2; 605 if ((error = ipcperm(td, &semakptr->u.sem_perm, IPC_R))) 606 goto done2; 607 sbuf = semakptr->u; 608 mtx_unlock(sema_mtxp); 609 error = copyout(&semakptr->u, real_arg.buf, 610 sizeof(struct semid_ds)); 611 break; 612 613 case GETNCNT: 614 mtx_lock(sema_mtxp); 615 if ((error = semvalid(uap->semid, semakptr)) != 0) 616 goto done2; 617 if ((error = ipcperm(td, &semakptr->u.sem_perm, IPC_R))) 618 goto done2; 619 if (semnum < 0 || semnum >= semakptr->u.sem_nsems) { 620 error = EINVAL; 621 goto done2; 622 } 623 rval = semakptr->u.sem_base[semnum].semncnt; 624 break; 625 626 case GETPID: 627 mtx_lock(sema_mtxp); 628 if ((error = semvalid(uap->semid, semakptr)) != 0) 629 goto done2; 630 if ((error = ipcperm(td, &semakptr->u.sem_perm, IPC_R))) 631 goto done2; 632 if (semnum < 0 || semnum >= semakptr->u.sem_nsems) { 633 error = EINVAL; 634 goto done2; 635 } 636 rval = semakptr->u.sem_base[semnum].sempid; 637 break; 638 639 case GETVAL: 640 mtx_lock(sema_mtxp); 641 if ((error = semvalid(uap->semid, semakptr)) != 0) 642 goto done2; 643 if ((error = ipcperm(td, &semakptr->u.sem_perm, IPC_R))) 644 goto done2; 645 if (semnum < 0 || semnum >= semakptr->u.sem_nsems) { 646 error = EINVAL; 647 goto done2; 648 } 649 rval = semakptr->u.sem_base[semnum].semval; 650 break; 651 652 case GETALL: 653 if ((error = copyin(arg, &real_arg, sizeof(real_arg))) != 0) 654 goto done2; 655 array = malloc(sizeof(*array) * semakptr->u.sem_nsems, M_TEMP, 656 M_WAITOK); 657 mtx_lock(sema_mtxp); 658 if ((error = semvalid(uap->semid, semakptr)) != 0) 659 goto done2; 660 if ((error = ipcperm(td, &semakptr->u.sem_perm, IPC_R))) 661 goto done2; 662 for (i = 0; i < semakptr->u.sem_nsems; i++) 663 array[i] = semakptr->u.sem_base[i].semval; 664 mtx_unlock(sema_mtxp); 665 error = copyout(array, real_arg.array, 666 i * sizeof(real_arg.array[0])); 667 break; 668 669 case GETZCNT: 670 mtx_lock(sema_mtxp); 671 if ((error = semvalid(uap->semid, semakptr)) != 0) 672 goto done2; 673 if ((error = ipcperm(td, &semakptr->u.sem_perm, IPC_R))) 674 goto done2; 675 if (semnum < 0 || semnum >= semakptr->u.sem_nsems) { 676 error = EINVAL; 677 goto done2; 678 } 679 rval = semakptr->u.sem_base[semnum].semzcnt; 680 break; 681 682 case SETVAL: 683 if ((error = copyin(arg, &real_arg, sizeof(real_arg))) != 0) 684 goto done2; 685 mtx_lock(sema_mtxp); 686 if ((error = semvalid(uap->semid, semakptr)) != 0) 687 goto done2; 688 if ((error = ipcperm(td, &semakptr->u.sem_perm, IPC_W))) 689 goto done2; 690 if (semnum < 0 || semnum >= semakptr->u.sem_nsems) { 691 error = EINVAL; 692 goto done2; 693 } 694 if (real_arg.val < 0 || real_arg.val > seminfo.semvmx) { 695 error = ERANGE; 696 goto done2; 697 } 698 semakptr->u.sem_base[semnum].semval = real_arg.val; 699 SEMUNDO_LOCK(); 700 semundo_clear(semid, semnum); 701 SEMUNDO_UNLOCK(); 702 wakeup(semakptr); 703 break; 704 705 case SETALL: 706 mtx_lock(sema_mtxp); 707 raced: 708 if ((error = semvalid(uap->semid, semakptr)) != 0) 709 goto done2; 710 count = semakptr->u.sem_nsems; 711 mtx_unlock(sema_mtxp); 712 if ((error = copyin(arg, &real_arg, sizeof(real_arg))) != 0) 713 goto done2; 714 array = malloc(sizeof(*array) * count, M_TEMP, M_WAITOK); 715 copyin(real_arg.array, array, count * sizeof(*array)); 716 if (error) 717 break; 718 mtx_lock(sema_mtxp); 719 if ((error = semvalid(uap->semid, semakptr)) != 0) 720 goto done2; 721 /* we could have raced? */ 722 if (count != semakptr->u.sem_nsems) { 723 free(array, M_TEMP); 724 array = NULL; 725 goto raced; 726 } 727 if ((error = ipcperm(td, &semakptr->u.sem_perm, IPC_W))) 728 goto done2; 729 for (i = 0; i < semakptr->u.sem_nsems; i++) { 730 usval = array[i]; 731 if (usval > seminfo.semvmx) { 732 error = ERANGE; 733 break; 734 } 735 semakptr->u.sem_base[i].semval = usval; 736 } 737 SEMUNDO_LOCK(); 738 semundo_clear(semid, -1); 739 SEMUNDO_UNLOCK(); 740 wakeup(semakptr); 741 break; 742 743 default: 744 error = EINVAL; 745 break; 746 } 747 748 if (error == 0) 749 td->td_retval[0] = rval; 750 done2: 751 if (mtx_owned(sema_mtxp)) 752 mtx_unlock(sema_mtxp); 753 if (array != NULL) 754 free(array, M_TEMP); 755 return(error); 756 } 757 758 #ifndef _SYS_SYSPROTO_H_ 759 struct semget_args { 760 key_t key; 761 int nsems; 762 int semflg; 763 }; 764 #endif 765 766 /* 767 * MPSAFE 768 */ 769 int 770 semget(td, uap) 771 struct thread *td; 772 struct semget_args *uap; 773 { 774 int semid, error = 0; 775 int key = uap->key; 776 int nsems = uap->nsems; 777 int semflg = uap->semflg; 778 struct ucred *cred = td->td_ucred; 779 780 DPRINTF(("semget(0x%x, %d, 0%o)\n", key, nsems, semflg)); 781 if (!jail_sysvipc_allowed && jailed(td->td_ucred)) 782 return (ENOSYS); 783 784 mtx_lock(&Giant); 785 if (key != IPC_PRIVATE) { 786 for (semid = 0; semid < seminfo.semmni; semid++) { 787 if ((sema[semid].u.sem_perm.mode & SEM_ALLOC) && 788 sema[semid].u.sem_perm.key == key) 789 break; 790 } 791 if (semid < seminfo.semmni) { 792 DPRINTF(("found public key\n")); 793 if ((error = ipcperm(td, &sema[semid].u.sem_perm, 794 semflg & 0700))) { 795 goto done2; 796 } 797 if (nsems > 0 && sema[semid].u.sem_nsems < nsems) { 798 DPRINTF(("too small\n")); 799 error = EINVAL; 800 goto done2; 801 } 802 if ((semflg & IPC_CREAT) && (semflg & IPC_EXCL)) { 803 DPRINTF(("not exclusive\n")); 804 error = EEXIST; 805 goto done2; 806 } 807 goto found; 808 } 809 } 810 811 DPRINTF(("need to allocate the semid_kernel\n")); 812 if (key == IPC_PRIVATE || (semflg & IPC_CREAT)) { 813 if (nsems <= 0 || nsems > seminfo.semmsl) { 814 DPRINTF(("nsems out of range (0<%d<=%d)\n", nsems, 815 seminfo.semmsl)); 816 error = EINVAL; 817 goto done2; 818 } 819 if (nsems > seminfo.semmns - semtot) { 820 DPRINTF(( 821 "not enough semaphores left (need %d, got %d)\n", 822 nsems, seminfo.semmns - semtot)); 823 error = ENOSPC; 824 goto done2; 825 } 826 for (semid = 0; semid < seminfo.semmni; semid++) { 827 if ((sema[semid].u.sem_perm.mode & SEM_ALLOC) == 0) 828 break; 829 } 830 if (semid == seminfo.semmni) { 831 DPRINTF(("no more semid_kernel's available\n")); 832 error = ENOSPC; 833 goto done2; 834 } 835 DPRINTF(("semid %d is available\n", semid)); 836 sema[semid].u.sem_perm.key = key; 837 sema[semid].u.sem_perm.cuid = cred->cr_uid; 838 sema[semid].u.sem_perm.uid = cred->cr_uid; 839 sema[semid].u.sem_perm.cgid = cred->cr_gid; 840 sema[semid].u.sem_perm.gid = cred->cr_gid; 841 sema[semid].u.sem_perm.mode = (semflg & 0777) | SEM_ALLOC; 842 sema[semid].u.sem_perm.seq = 843 (sema[semid].u.sem_perm.seq + 1) & 0x7fff; 844 sema[semid].u.sem_nsems = nsems; 845 sema[semid].u.sem_otime = 0; 846 sema[semid].u.sem_ctime = time_second; 847 sema[semid].u.sem_base = &sem[semtot]; 848 semtot += nsems; 849 bzero(sema[semid].u.sem_base, 850 sizeof(sema[semid].u.sem_base[0])*nsems); 851 DPRINTF(("sembase = 0x%x, next = 0x%x\n", 852 sema[semid].u.sem_base, &sem[semtot])); 853 } else { 854 DPRINTF(("didn't find it and wasn't asked to create it\n")); 855 error = ENOENT; 856 goto done2; 857 } 858 859 found: 860 td->td_retval[0] = IXSEQ_TO_IPCID(semid, sema[semid].u.sem_perm); 861 done2: 862 mtx_unlock(&Giant); 863 return (error); 864 } 865 866 #ifndef _SYS_SYSPROTO_H_ 867 struct semop_args { 868 int semid; 869 struct sembuf *sops; 870 size_t nsops; 871 }; 872 #endif 873 874 /* 875 * MPSAFE 876 */ 877 int 878 semop(td, uap) 879 struct thread *td; 880 struct semop_args *uap; 881 { 882 #define SMALL_SOPS 8 883 struct sembuf small_sops[SMALL_SOPS]; 884 int semid = uap->semid; 885 size_t nsops = uap->nsops; 886 struct sembuf *sops; 887 struct semid_kernel *semakptr; 888 struct sembuf *sopptr = 0; 889 struct sem *semptr = 0; 890 struct sem_undo *suptr; 891 struct mtx *sema_mtxp; 892 size_t i, j, k; 893 int error; 894 int do_wakeup, do_undos; 895 896 DPRINTF(("call to semop(%d, 0x%x, %u)\n", semid, sops, nsops)); 897 898 if (!jail_sysvipc_allowed && jailed(td->td_ucred)) 899 return (ENOSYS); 900 901 semid = IPCID_TO_IX(semid); /* Convert back to zero origin */ 902 903 if (semid < 0 || semid >= seminfo.semmni) 904 return (EINVAL); 905 906 /* Allocate memory for sem_ops */ 907 if (nsops <= SMALL_SOPS) 908 sops = small_sops; 909 else if (nsops <= seminfo.semopm) 910 sops = malloc(nsops * sizeof(*sops), M_TEMP, M_WAITOK); 911 else { 912 DPRINTF(("too many sops (max=%d, nsops=%d)\n", seminfo.semopm, 913 nsops)); 914 return (E2BIG); 915 } 916 if ((error = copyin(uap->sops, sops, nsops * sizeof(sops[0]))) != 0) { 917 DPRINTF(("error = %d from copyin(%08x, %08x, %d)\n", error, 918 uap->sops, sops, nsops * sizeof(sops[0]))); 919 if (sops != small_sops) 920 free(sops, M_SEM); 921 return (error); 922 } 923 924 semakptr = &sema[semid]; 925 sema_mtxp = &sema_mtx[semid]; 926 mtx_lock(sema_mtxp); 927 if ((semakptr->u.sem_perm.mode & SEM_ALLOC) == 0) { 928 error = EINVAL; 929 goto done2; 930 } 931 if (semakptr->u.sem_perm.seq != IPCID_TO_SEQ(uap->semid)) { 932 error = EINVAL; 933 goto done2; 934 } 935 /* 936 * Initial pass thru sops to see what permissions are needed. 937 * Also perform any checks that don't need repeating on each 938 * attempt to satisfy the request vector. 939 */ 940 j = 0; /* permission needed */ 941 do_undos = 0; 942 for (i = 0; i < nsops; i++) { 943 sopptr = &sops[i]; 944 if (sopptr->sem_num >= semakptr->u.sem_nsems) { 945 error = EFBIG; 946 goto done2; 947 } 948 if (sopptr->sem_flg & SEM_UNDO && sopptr->sem_op != 0) 949 do_undos = 1; 950 j |= (sopptr->sem_op == 0) ? SEM_R : SEM_A; 951 } 952 953 if ((error = ipcperm(td, &semakptr->u.sem_perm, j))) { 954 DPRINTF(("error = %d from ipaccess\n", error)); 955 goto done2; 956 } 957 958 /* 959 * Loop trying to satisfy the vector of requests. 960 * If we reach a point where we must wait, any requests already 961 * performed are rolled back and we go to sleep until some other 962 * process wakes us up. At this point, we start all over again. 963 * 964 * This ensures that from the perspective of other tasks, a set 965 * of requests is atomic (never partially satisfied). 966 */ 967 for (;;) { 968 do_wakeup = 0; 969 error = 0; /* error return if necessary */ 970 971 for (i = 0; i < nsops; i++) { 972 sopptr = &sops[i]; 973 semptr = &semakptr->u.sem_base[sopptr->sem_num]; 974 975 DPRINTF(( 976 "semop: semakptr=%x, sem_base=%x, " 977 "semptr=%x, sem[%d]=%d : op=%d, flag=%s\n", 978 semakptr, semakptr->u.sem_base, semptr, 979 sopptr->sem_num, semptr->semval, sopptr->sem_op, 980 (sopptr->sem_flg & IPC_NOWAIT) ? 981 "nowait" : "wait")); 982 983 if (sopptr->sem_op < 0) { 984 if (semptr->semval + sopptr->sem_op < 0) { 985 DPRINTF(("semop: can't do it now\n")); 986 break; 987 } else { 988 semptr->semval += sopptr->sem_op; 989 if (semptr->semval == 0 && 990 semptr->semzcnt > 0) 991 do_wakeup = 1; 992 } 993 } else if (sopptr->sem_op == 0) { 994 if (semptr->semval != 0) { 995 DPRINTF(("semop: not zero now\n")); 996 break; 997 } 998 } else if (semptr->semval + sopptr->sem_op > 999 seminfo.semvmx) { 1000 error = ERANGE; 1001 break; 1002 } else { 1003 if (semptr->semncnt > 0) 1004 do_wakeup = 1; 1005 semptr->semval += sopptr->sem_op; 1006 } 1007 } 1008 1009 /* 1010 * Did we get through the entire vector? 1011 */ 1012 if (i >= nsops) 1013 goto done; 1014 1015 /* 1016 * No ... rollback anything that we've already done 1017 */ 1018 DPRINTF(("semop: rollback 0 through %d\n", i-1)); 1019 for (j = 0; j < i; j++) 1020 semakptr->u.sem_base[sops[j].sem_num].semval -= 1021 sops[j].sem_op; 1022 1023 /* If we detected an error, return it */ 1024 if (error != 0) 1025 goto done2; 1026 1027 /* 1028 * If the request that we couldn't satisfy has the 1029 * NOWAIT flag set then return with EAGAIN. 1030 */ 1031 if (sopptr->sem_flg & IPC_NOWAIT) { 1032 error = EAGAIN; 1033 goto done2; 1034 } 1035 1036 if (sopptr->sem_op == 0) 1037 semptr->semzcnt++; 1038 else 1039 semptr->semncnt++; 1040 1041 DPRINTF(("semop: good night!\n")); 1042 error = msleep(semakptr, sema_mtxp, (PZERO - 4) | PCATCH, 1043 "semwait", 0); 1044 DPRINTF(("semop: good morning (error=%d)!\n", error)); 1045 /* return code is checked below, after sem[nz]cnt-- */ 1046 1047 /* 1048 * Make sure that the semaphore still exists 1049 */ 1050 if ((semakptr->u.sem_perm.mode & SEM_ALLOC) == 0 || 1051 semakptr->u.sem_perm.seq != IPCID_TO_SEQ(uap->semid)) { 1052 error = EIDRM; 1053 goto done2; 1054 } 1055 1056 /* 1057 * The semaphore is still alive. Readjust the count of 1058 * waiting processes. 1059 */ 1060 if (sopptr->sem_op == 0) 1061 semptr->semzcnt--; 1062 else 1063 semptr->semncnt--; 1064 1065 /* 1066 * Is it really morning, or was our sleep interrupted? 1067 * (Delayed check of msleep() return code because we 1068 * need to decrement sem[nz]cnt either way.) 1069 */ 1070 if (error != 0) { 1071 error = EINTR; 1072 goto done2; 1073 } 1074 DPRINTF(("semop: good morning!\n")); 1075 } 1076 1077 done: 1078 /* 1079 * Process any SEM_UNDO requests. 1080 */ 1081 if (do_undos) { 1082 SEMUNDO_LOCK(); 1083 suptr = NULL; 1084 for (i = 0; i < nsops; i++) { 1085 /* 1086 * We only need to deal with SEM_UNDO's for non-zero 1087 * op's. 1088 */ 1089 int adjval; 1090 1091 if ((sops[i].sem_flg & SEM_UNDO) == 0) 1092 continue; 1093 adjval = sops[i].sem_op; 1094 if (adjval == 0) 1095 continue; 1096 error = semundo_adjust(td, &suptr, semid, 1097 sops[i].sem_num, -adjval); 1098 if (error == 0) 1099 continue; 1100 1101 /* 1102 * Oh-Oh! We ran out of either sem_undo's or undo's. 1103 * Rollback the adjustments to this point and then 1104 * rollback the semaphore ups and down so we can return 1105 * with an error with all structures restored. We 1106 * rollback the undo's in the exact reverse order that 1107 * we applied them. This guarantees that we won't run 1108 * out of space as we roll things back out. 1109 */ 1110 for (j = 0; j < i; j++) { 1111 k = i - j - 1; 1112 if ((sops[k].sem_flg & SEM_UNDO) == 0) 1113 continue; 1114 adjval = sops[k].sem_op; 1115 if (adjval == 0) 1116 continue; 1117 if (semundo_adjust(td, &suptr, semid, 1118 sops[k].sem_num, adjval) != 0) 1119 panic("semop - can't undo undos"); 1120 } 1121 1122 for (j = 0; j < nsops; j++) 1123 semakptr->u.sem_base[sops[j].sem_num].semval -= 1124 sops[j].sem_op; 1125 1126 DPRINTF(("error = %d from semundo_adjust\n", error)); 1127 SEMUNDO_UNLOCK(); 1128 goto done2; 1129 } /* loop through the sops */ 1130 SEMUNDO_UNLOCK(); 1131 } /* if (do_undos) */ 1132 1133 /* We're definitely done - set the sempid's and time */ 1134 for (i = 0; i < nsops; i++) { 1135 sopptr = &sops[i]; 1136 semptr = &semakptr->u.sem_base[sopptr->sem_num]; 1137 semptr->sempid = td->td_proc->p_pid; 1138 } 1139 semakptr->u.sem_otime = time_second; 1140 1141 /* 1142 * Do a wakeup if any semaphore was up'd whilst something was 1143 * sleeping on it. 1144 */ 1145 if (do_wakeup) { 1146 DPRINTF(("semop: doing wakeup\n")); 1147 wakeup(semakptr); 1148 DPRINTF(("semop: back from wakeup\n")); 1149 } 1150 DPRINTF(("semop: done\n")); 1151 td->td_retval[0] = 0; 1152 done2: 1153 mtx_unlock(sema_mtxp); 1154 if (sops != small_sops) 1155 free(sops, M_SEM); 1156 return (error); 1157 } 1158 1159 /* 1160 * Go through the undo structures for this process and apply the adjustments to 1161 * semaphores. 1162 */ 1163 static void 1164 semexit_myhook(arg, p) 1165 void *arg; 1166 struct proc *p; 1167 { 1168 struct sem_undo *suptr; 1169 struct sem_undo **supptr; 1170 1171 /* 1172 * Go through the chain of undo vectors looking for one 1173 * associated with this process. 1174 */ 1175 SEMUNDO_LOCK(); 1176 SLIST_FOREACH_PREVPTR(suptr, supptr, &semu_list, un_next) { 1177 if (suptr->un_proc == p) 1178 break; 1179 } 1180 SEMUNDO_UNLOCK(); 1181 1182 if (suptr == NULL) 1183 return; 1184 1185 DPRINTF(("proc @%08x has undo structure with %d entries\n", p, 1186 suptr->un_cnt)); 1187 1188 /* 1189 * If there are any active undo elements then process them. 1190 */ 1191 if (suptr->un_cnt > 0) { 1192 int ix; 1193 1194 for (ix = 0; ix < suptr->un_cnt; ix++) { 1195 int semid = suptr->un_ent[ix].un_id; 1196 int semnum = suptr->un_ent[ix].un_num; 1197 int adjval = suptr->un_ent[ix].un_adjval; 1198 struct semid_kernel *semakptr; 1199 struct mtx *sema_mtxp; 1200 1201 semakptr = &sema[semid]; 1202 sema_mtxp = &sema_mtx[semid]; 1203 mtx_lock(sema_mtxp); 1204 SEMUNDO_LOCK(); 1205 if ((semakptr->u.sem_perm.mode & SEM_ALLOC) == 0) 1206 panic("semexit - semid not allocated"); 1207 if (semnum >= semakptr->u.sem_nsems) 1208 panic("semexit - semnum out of range"); 1209 1210 DPRINTF(( 1211 "semexit: %08x id=%d num=%d(adj=%d) ; sem=%d\n", 1212 suptr->un_proc, suptr->un_ent[ix].un_id, 1213 suptr->un_ent[ix].un_num, 1214 suptr->un_ent[ix].un_adjval, 1215 semakptr->u.sem_base[semnum].semval)); 1216 1217 if (adjval < 0) { 1218 if (semakptr->u.sem_base[semnum].semval < 1219 -adjval) 1220 semakptr->u.sem_base[semnum].semval = 0; 1221 else 1222 semakptr->u.sem_base[semnum].semval += 1223 adjval; 1224 } else 1225 semakptr->u.sem_base[semnum].semval += adjval; 1226 1227 wakeup(semakptr); 1228 DPRINTF(("semexit: back from wakeup\n")); 1229 mtx_unlock(sema_mtxp); 1230 SEMUNDO_UNLOCK(); 1231 } 1232 } 1233 1234 /* 1235 * Deallocate the undo vector. 1236 */ 1237 DPRINTF(("removing vector\n")); 1238 suptr->un_proc = NULL; 1239 *supptr = SLIST_NEXT(suptr, un_next); 1240 } 1241 1242 static int 1243 sysctl_sema(SYSCTL_HANDLER_ARGS) 1244 { 1245 1246 return (SYSCTL_OUT(req, sema, 1247 sizeof(struct semid_kernel) * seminfo.semmni)); 1248 } 1249