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 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 < 0 || 290 uap->which >= sizeof(semcalls)/sizeof(semcalls[0])) 291 return (EINVAL); 292 error = (*semcalls[uap->which])(td, &uap->a2); 293 return (error); 294 } 295 296 /* 297 * Allocate a new sem_undo structure for a process 298 * (returns ptr to structure or NULL if no more room) 299 */ 300 301 static struct sem_undo * 302 semu_alloc(td) 303 struct thread *td; 304 { 305 int i; 306 struct sem_undo *suptr; 307 struct sem_undo **supptr; 308 int attempt; 309 310 SEMUNDO_LOCKASSERT(MA_OWNED); 311 /* 312 * Try twice to allocate something. 313 * (we'll purge any empty structures after the first pass so 314 * two passes are always enough) 315 */ 316 317 for (attempt = 0; attempt < 2; attempt++) { 318 /* 319 * Look for a free structure. 320 * Fill it in and return it if we find one. 321 */ 322 323 for (i = 0; i < seminfo.semmnu; i++) { 324 suptr = SEMU(i); 325 if (suptr->un_proc == NULL) { 326 SLIST_INSERT_HEAD(&semu_list, suptr, un_next); 327 suptr->un_cnt = 0; 328 suptr->un_proc = td->td_proc; 329 return(suptr); 330 } 331 } 332 333 /* 334 * We didn't find a free one, if this is the first attempt 335 * then try to free some structures. 336 */ 337 338 if (attempt == 0) { 339 /* All the structures are in use - try to free some */ 340 int did_something = 0; 341 342 SLIST_FOREACH_PREVPTR(suptr, supptr, &semu_list, 343 un_next) { 344 if (suptr->un_cnt == 0) { 345 suptr->un_proc = NULL; 346 did_something = 1; 347 *supptr = SLIST_NEXT(suptr, un_next); 348 } 349 } 350 351 /* If we didn't free anything then just give-up */ 352 if (!did_something) 353 return(NULL); 354 } else { 355 /* 356 * The second pass failed even though we freed 357 * something after the first pass! 358 * This is IMPOSSIBLE! 359 */ 360 panic("semu_alloc - second attempt failed"); 361 } 362 } 363 return (NULL); 364 } 365 366 /* 367 * Adjust a particular entry for a particular proc 368 */ 369 370 static int 371 semundo_adjust(td, supptr, semid, semnum, adjval) 372 struct thread *td; 373 struct sem_undo **supptr; 374 int semid, semnum; 375 int adjval; 376 { 377 struct proc *p = td->td_proc; 378 struct sem_undo *suptr; 379 struct undo *sunptr; 380 int i; 381 382 SEMUNDO_LOCKASSERT(MA_OWNED); 383 /* Look for and remember the sem_undo if the caller doesn't provide 384 it */ 385 386 suptr = *supptr; 387 if (suptr == NULL) { 388 SLIST_FOREACH(suptr, &semu_list, un_next) { 389 if (suptr->un_proc == p) { 390 *supptr = suptr; 391 break; 392 } 393 } 394 if (suptr == NULL) { 395 if (adjval == 0) 396 return(0); 397 suptr = semu_alloc(td); 398 if (suptr == NULL) 399 return(ENOSPC); 400 *supptr = suptr; 401 } 402 } 403 404 /* 405 * Look for the requested entry and adjust it (delete if adjval becomes 406 * 0). 407 */ 408 sunptr = &suptr->un_ent[0]; 409 for (i = 0; i < suptr->un_cnt; i++, sunptr++) { 410 if (sunptr->un_id != semid || sunptr->un_num != semnum) 411 continue; 412 if (adjval != 0) { 413 adjval += sunptr->un_adjval; 414 if (adjval > seminfo.semaem || adjval < -seminfo.semaem) 415 return (ERANGE); 416 } 417 sunptr->un_adjval = adjval; 418 if (sunptr->un_adjval == 0) { 419 suptr->un_cnt--; 420 if (i < suptr->un_cnt) 421 suptr->un_ent[i] = 422 suptr->un_ent[suptr->un_cnt]; 423 } 424 return(0); 425 } 426 427 /* Didn't find the right entry - create it */ 428 if (adjval == 0) 429 return(0); 430 if (adjval > seminfo.semaem || adjval < -seminfo.semaem) 431 return (ERANGE); 432 if (suptr->un_cnt != seminfo.semume) { 433 sunptr = &suptr->un_ent[suptr->un_cnt]; 434 suptr->un_cnt++; 435 sunptr->un_adjval = adjval; 436 sunptr->un_id = semid; sunptr->un_num = semnum; 437 } else 438 return(EINVAL); 439 return(0); 440 } 441 442 static void 443 semundo_clear(semid, semnum) 444 int semid, semnum; 445 { 446 struct sem_undo *suptr; 447 448 SEMUNDO_LOCKASSERT(MA_OWNED); 449 SLIST_FOREACH(suptr, &semu_list, un_next) { 450 struct undo *sunptr = &suptr->un_ent[0]; 451 int i = 0; 452 453 while (i < suptr->un_cnt) { 454 if (sunptr->un_id == semid) { 455 if (semnum == -1 || sunptr->un_num == semnum) { 456 suptr->un_cnt--; 457 if (i < suptr->un_cnt) { 458 suptr->un_ent[i] = 459 suptr->un_ent[suptr->un_cnt]; 460 continue; 461 } 462 } 463 if (semnum != -1) 464 break; 465 } 466 i++, sunptr++; 467 } 468 } 469 } 470 471 static int 472 semvalid(semid, semaptr) 473 int semid; 474 struct semid_ds *semaptr; 475 { 476 477 return ((semaptr->sem_perm.mode & SEM_ALLOC) == 0 || 478 semaptr->sem_perm.seq != IPCID_TO_SEQ(semid) ? EINVAL : 0); 479 } 480 481 /* 482 * Note that the user-mode half of this passes a union, not a pointer 483 */ 484 #ifndef _SYS_SYSPROTO_H_ 485 struct __semctl_args { 486 int semid; 487 int semnum; 488 int cmd; 489 union semun *arg; 490 }; 491 #endif 492 493 /* 494 * MPSAFE 495 */ 496 int 497 __semctl(td, uap) 498 struct thread *td; 499 struct __semctl_args *uap; 500 { 501 int semid = uap->semid; 502 int semnum = uap->semnum; 503 int cmd = uap->cmd; 504 u_short *array; 505 union semun *arg = uap->arg; 506 union semun real_arg; 507 struct ucred *cred = td->td_ucred; 508 int i, rval, error; 509 struct semid_ds sbuf; 510 struct semid_ds *semaptr; 511 struct mtx *sema_mtxp; 512 u_short usval, count; 513 514 DPRINTF(("call to semctl(%d, %d, %d, 0x%x)\n", 515 semid, semnum, cmd, arg)); 516 if (!jail_sysvipc_allowed && jailed(td->td_ucred)) 517 return (ENOSYS); 518 519 array = NULL; 520 521 switch(cmd) { 522 case SEM_STAT: 523 if (semid < 0 || semid >= seminfo.semmni) 524 return (EINVAL); 525 if ((error = copyin(arg, &real_arg, sizeof(real_arg))) != 0) 526 return (error); 527 semaptr = &sema[semid]; 528 sema_mtxp = &sema_mtx[semid]; 529 mtx_lock(sema_mtxp); 530 if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0 ) { 531 error = EINVAL; 532 goto done2; 533 } 534 if ((error = ipcperm(td, &semaptr->sem_perm, IPC_R))) 535 goto done2; 536 mtx_unlock(sema_mtxp); 537 error = copyout(semaptr, real_arg.buf, sizeof(struct semid_ds)); 538 rval = IXSEQ_TO_IPCID(semid,semaptr->sem_perm); 539 if (error == 0) 540 td->td_retval[0] = rval; 541 return (error); 542 } 543 544 semid = IPCID_TO_IX(semid); 545 if (semid < 0 || semid >= seminfo.semmni) 546 return (EINVAL); 547 548 semaptr = &sema[semid]; 549 sema_mtxp = &sema_mtx[semid]; 550 551 error = 0; 552 rval = 0; 553 554 switch (cmd) { 555 case IPC_RMID: 556 mtx_lock(sema_mtxp); 557 if ((error = semvalid(uap->semid, semaptr)) != 0) 558 goto done2; 559 if ((error = ipcperm(td, &semaptr->sem_perm, IPC_M))) 560 goto done2; 561 semaptr->sem_perm.cuid = cred->cr_uid; 562 semaptr->sem_perm.uid = cred->cr_uid; 563 semtot -= semaptr->sem_nsems; 564 for (i = semaptr->sem_base - sem; i < semtot; i++) 565 sem[i] = sem[i + semaptr->sem_nsems]; 566 for (i = 0; i < seminfo.semmni; i++) { 567 if ((sema[i].sem_perm.mode & SEM_ALLOC) && 568 sema[i].sem_base > semaptr->sem_base) 569 sema[i].sem_base -= semaptr->sem_nsems; 570 } 571 semaptr->sem_perm.mode = 0; 572 SEMUNDO_LOCK(); 573 semundo_clear(semid, -1); 574 SEMUNDO_UNLOCK(); 575 wakeup(semaptr); 576 break; 577 578 case IPC_SET: 579 if ((error = copyin(arg, &real_arg, sizeof(real_arg))) != 0) 580 goto done2; 581 if ((error = copyin(real_arg.buf, &sbuf, sizeof(sbuf))) != 0) 582 goto done2; 583 mtx_lock(sema_mtxp); 584 if ((error = semvalid(uap->semid, semaptr)) != 0) 585 goto done2; 586 if ((error = ipcperm(td, &semaptr->sem_perm, IPC_M))) 587 goto done2; 588 semaptr->sem_perm.uid = sbuf.sem_perm.uid; 589 semaptr->sem_perm.gid = sbuf.sem_perm.gid; 590 semaptr->sem_perm.mode = (semaptr->sem_perm.mode & ~0777) | 591 (sbuf.sem_perm.mode & 0777); 592 semaptr->sem_ctime = time_second; 593 break; 594 595 case IPC_STAT: 596 if ((error = copyin(arg, &real_arg, sizeof(real_arg))) != 0) 597 goto done2; 598 mtx_lock(sema_mtxp); 599 if ((error = semvalid(uap->semid, semaptr)) != 0) 600 goto done2; 601 if ((error = ipcperm(td, &semaptr->sem_perm, IPC_R))) 602 goto done2; 603 sbuf = *semaptr; 604 mtx_unlock(sema_mtxp); 605 error = copyout(semaptr, real_arg.buf, 606 sizeof(struct semid_ds)); 607 break; 608 609 case GETNCNT: 610 mtx_lock(sema_mtxp); 611 if ((error = semvalid(uap->semid, semaptr)) != 0) 612 goto done2; 613 if ((error = ipcperm(td, &semaptr->sem_perm, IPC_R))) 614 goto done2; 615 if (semnum < 0 || semnum >= semaptr->sem_nsems) { 616 error = EINVAL; 617 goto done2; 618 } 619 rval = semaptr->sem_base[semnum].semncnt; 620 break; 621 622 case GETPID: 623 mtx_lock(sema_mtxp); 624 if ((error = semvalid(uap->semid, semaptr)) != 0) 625 goto done2; 626 if ((error = ipcperm(td, &semaptr->sem_perm, IPC_R))) 627 goto done2; 628 if (semnum < 0 || semnum >= semaptr->sem_nsems) { 629 error = EINVAL; 630 goto done2; 631 } 632 rval = semaptr->sem_base[semnum].sempid; 633 break; 634 635 case GETVAL: 636 mtx_lock(sema_mtxp); 637 if ((error = semvalid(uap->semid, semaptr)) != 0) 638 goto done2; 639 if ((error = ipcperm(td, &semaptr->sem_perm, IPC_R))) 640 goto done2; 641 if (semnum < 0 || semnum >= semaptr->sem_nsems) { 642 error = EINVAL; 643 goto done2; 644 } 645 rval = semaptr->sem_base[semnum].semval; 646 break; 647 648 case GETALL: 649 if ((error = copyin(arg, &real_arg, sizeof(real_arg))) != 0) 650 goto done2; 651 array = malloc(sizeof(*array) * semaptr->sem_nsems, M_TEMP, 652 M_WAITOK); 653 mtx_lock(sema_mtxp); 654 if ((error = semvalid(uap->semid, semaptr)) != 0) 655 goto done2; 656 if ((error = ipcperm(td, &semaptr->sem_perm, IPC_R))) 657 goto done2; 658 for (i = 0; i < semaptr->sem_nsems; i++) 659 array[i] = semaptr->sem_base[i].semval; 660 mtx_unlock(sema_mtxp); 661 error = copyout(array, real_arg.array, 662 i * sizeof(real_arg.array[0])); 663 break; 664 665 case GETZCNT: 666 mtx_lock(sema_mtxp); 667 if ((error = semvalid(uap->semid, semaptr)) != 0) 668 goto done2; 669 if ((error = ipcperm(td, &semaptr->sem_perm, IPC_R))) 670 goto done2; 671 if (semnum < 0 || semnum >= semaptr->sem_nsems) { 672 error = EINVAL; 673 goto done2; 674 } 675 rval = semaptr->sem_base[semnum].semzcnt; 676 break; 677 678 case SETVAL: 679 if ((error = copyin(arg, &real_arg, sizeof(real_arg))) != 0) 680 goto done2; 681 mtx_lock(sema_mtxp); 682 if ((error = semvalid(uap->semid, semaptr)) != 0) 683 goto done2; 684 if ((error = ipcperm(td, &semaptr->sem_perm, IPC_W))) 685 goto done2; 686 if (semnum < 0 || semnum >= semaptr->sem_nsems) { 687 error = EINVAL; 688 goto done2; 689 } 690 if (real_arg.val < 0 || real_arg.val > seminfo.semvmx) { 691 error = ERANGE; 692 goto done2; 693 } 694 semaptr->sem_base[semnum].semval = real_arg.val; 695 SEMUNDO_LOCK(); 696 semundo_clear(semid, semnum); 697 SEMUNDO_UNLOCK(); 698 wakeup(semaptr); 699 break; 700 701 case SETALL: 702 mtx_lock(sema_mtxp); 703 raced: 704 if ((error = semvalid(uap->semid, semaptr)) != 0) 705 goto done2; 706 count = semaptr->sem_nsems; 707 mtx_unlock(sema_mtxp); 708 if ((error = copyin(arg, &real_arg, sizeof(real_arg))) != 0) 709 goto done2; 710 array = malloc(sizeof(*array) * count, M_TEMP, M_WAITOK); 711 copyin(real_arg.array, array, count * sizeof(*array)); 712 if (error) 713 break; 714 mtx_lock(sema_mtxp); 715 if ((error = semvalid(uap->semid, semaptr)) != 0) 716 goto done2; 717 /* we could have raced? */ 718 if (count != semaptr->sem_nsems) { 719 free(array, M_TEMP); 720 array = NULL; 721 goto raced; 722 } 723 if ((error = ipcperm(td, &semaptr->sem_perm, IPC_W))) 724 goto done2; 725 for (i = 0; i < semaptr->sem_nsems; i++) { 726 usval = array[i]; 727 if (usval > seminfo.semvmx) { 728 error = ERANGE; 729 break; 730 } 731 semaptr->sem_base[i].semval = usval; 732 } 733 SEMUNDO_LOCK(); 734 semundo_clear(semid, -1); 735 SEMUNDO_UNLOCK(); 736 wakeup(semaptr); 737 break; 738 739 default: 740 error = EINVAL; 741 break; 742 } 743 744 if (error == 0) 745 td->td_retval[0] = rval; 746 done2: 747 if (mtx_owned(sema_mtxp)) 748 mtx_unlock(sema_mtxp); 749 if (array != NULL) 750 free(array, M_TEMP); 751 return(error); 752 } 753 754 #ifndef _SYS_SYSPROTO_H_ 755 struct semget_args { 756 key_t key; 757 int nsems; 758 int semflg; 759 }; 760 #endif 761 762 /* 763 * MPSAFE 764 */ 765 int 766 semget(td, uap) 767 struct thread *td; 768 struct semget_args *uap; 769 { 770 int semid, error = 0; 771 int key = uap->key; 772 int nsems = uap->nsems; 773 int semflg = uap->semflg; 774 struct ucred *cred = td->td_ucred; 775 776 DPRINTF(("semget(0x%x, %d, 0%o)\n", key, nsems, semflg)); 777 if (!jail_sysvipc_allowed && jailed(td->td_ucred)) 778 return (ENOSYS); 779 780 mtx_lock(&Giant); 781 if (key != IPC_PRIVATE) { 782 for (semid = 0; semid < seminfo.semmni; semid++) { 783 if ((sema[semid].sem_perm.mode & SEM_ALLOC) && 784 sema[semid].sem_perm.key == key) 785 break; 786 } 787 if (semid < seminfo.semmni) { 788 DPRINTF(("found public key\n")); 789 if ((error = ipcperm(td, &sema[semid].sem_perm, 790 semflg & 0700))) { 791 goto done2; 792 } 793 if (nsems > 0 && sema[semid].sem_nsems < nsems) { 794 DPRINTF(("too small\n")); 795 error = EINVAL; 796 goto done2; 797 } 798 if ((semflg & IPC_CREAT) && (semflg & IPC_EXCL)) { 799 DPRINTF(("not exclusive\n")); 800 error = EEXIST; 801 goto done2; 802 } 803 goto found; 804 } 805 } 806 807 DPRINTF(("need to allocate the semid_ds\n")); 808 if (key == IPC_PRIVATE || (semflg & IPC_CREAT)) { 809 if (nsems <= 0 || nsems > seminfo.semmsl) { 810 DPRINTF(("nsems out of range (0<%d<=%d)\n", nsems, 811 seminfo.semmsl)); 812 error = EINVAL; 813 goto done2; 814 } 815 if (nsems > seminfo.semmns - semtot) { 816 DPRINTF(( 817 "not enough semaphores left (need %d, got %d)\n", 818 nsems, seminfo.semmns - semtot)); 819 error = ENOSPC; 820 goto done2; 821 } 822 for (semid = 0; semid < seminfo.semmni; semid++) { 823 if ((sema[semid].sem_perm.mode & SEM_ALLOC) == 0) 824 break; 825 } 826 if (semid == seminfo.semmni) { 827 DPRINTF(("no more semid_ds's available\n")); 828 error = ENOSPC; 829 goto done2; 830 } 831 DPRINTF(("semid %d is available\n", semid)); 832 sema[semid].sem_perm.key = key; 833 sema[semid].sem_perm.cuid = cred->cr_uid; 834 sema[semid].sem_perm.uid = cred->cr_uid; 835 sema[semid].sem_perm.cgid = cred->cr_gid; 836 sema[semid].sem_perm.gid = cred->cr_gid; 837 sema[semid].sem_perm.mode = (semflg & 0777) | SEM_ALLOC; 838 sema[semid].sem_perm.seq = 839 (sema[semid].sem_perm.seq + 1) & 0x7fff; 840 sema[semid].sem_nsems = nsems; 841 sema[semid].sem_otime = 0; 842 sema[semid].sem_ctime = time_second; 843 sema[semid].sem_base = &sem[semtot]; 844 semtot += nsems; 845 bzero(sema[semid].sem_base, 846 sizeof(sema[semid].sem_base[0])*nsems); 847 DPRINTF(("sembase = 0x%x, next = 0x%x\n", sema[semid].sem_base, 848 &sem[semtot])); 849 } else { 850 DPRINTF(("didn't find it and wasn't asked to create it\n")); 851 error = ENOENT; 852 goto done2; 853 } 854 855 found: 856 td->td_retval[0] = IXSEQ_TO_IPCID(semid, sema[semid].sem_perm); 857 done2: 858 mtx_unlock(&Giant); 859 return (error); 860 } 861 862 #ifndef _SYS_SYSPROTO_H_ 863 struct semop_args { 864 int semid; 865 struct sembuf *sops; 866 size_t nsops; 867 }; 868 #endif 869 870 /* 871 * MPSAFE 872 */ 873 int 874 semop(td, uap) 875 struct thread *td; 876 struct semop_args *uap; 877 { 878 int semid = uap->semid; 879 size_t nsops = uap->nsops; 880 struct sembuf *sops; 881 struct semid_ds *semaptr; 882 struct sembuf *sopptr = 0; 883 struct sem *semptr = 0; 884 struct sem_undo *suptr; 885 struct mtx *sema_mtxp; 886 size_t i, j, k; 887 int error; 888 int do_wakeup, do_undos; 889 890 DPRINTF(("call to semop(%d, 0x%x, %u)\n", semid, sops, nsops)); 891 892 if (!jail_sysvipc_allowed && jailed(td->td_ucred)) 893 return (ENOSYS); 894 895 semid = IPCID_TO_IX(semid); /* Convert back to zero origin */ 896 897 if (semid < 0 || semid >= seminfo.semmni) 898 return (EINVAL); 899 900 /* Allocate memory for sem_ops */ 901 if (nsops > seminfo.semopm) { 902 DPRINTF(("too many sops (max=%d, nsops=%d)\n", seminfo.semopm, 903 nsops)); 904 return (E2BIG); 905 } 906 sops = malloc(nsops * sizeof(sops[0]), M_SEM, M_WAITOK); 907 if ((error = copyin(uap->sops, sops, nsops * sizeof(sops[0]))) != 0) { 908 DPRINTF(("error = %d from copyin(%08x, %08x, %d)\n", error, 909 uap->sops, sops, nsops * sizeof(sops[0]))); 910 free(sops, M_SEM); 911 return (error); 912 } 913 914 semaptr = &sema[semid]; 915 sema_mtxp = &sema_mtx[semid]; 916 mtx_lock(sema_mtxp); 917 if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0) { 918 error = EINVAL; 919 goto done2; 920 } 921 if (semaptr->sem_perm.seq != IPCID_TO_SEQ(uap->semid)) { 922 error = EINVAL; 923 goto done2; 924 } 925 /* 926 * Initial pass thru sops to see what permissions are needed. 927 * Also perform any checks that don't need repeating on each 928 * attempt to satisfy the request vector. 929 */ 930 j = 0; /* permission needed */ 931 do_undos = 0; 932 for (i = 0; i < nsops; i++) { 933 sopptr = &sops[i]; 934 if (sopptr->sem_num >= semaptr->sem_nsems) { 935 error = EFBIG; 936 goto done2; 937 } 938 if (sopptr->sem_flg & SEM_UNDO && sopptr->sem_op != 0) 939 do_undos = 1; 940 j |= (sopptr->sem_op == 0) ? SEM_R : SEM_A; 941 } 942 943 if ((error = ipcperm(td, &semaptr->sem_perm, j))) { 944 DPRINTF(("error = %d from ipaccess\n", error)); 945 goto done2; 946 } 947 948 /* 949 * Loop trying to satisfy the vector of requests. 950 * If we reach a point where we must wait, any requests already 951 * performed are rolled back and we go to sleep until some other 952 * process wakes us up. At this point, we start all over again. 953 * 954 * This ensures that from the perspective of other tasks, a set 955 * of requests is atomic (never partially satisfied). 956 */ 957 for (;;) { 958 do_wakeup = 0; 959 error = 0; /* error return if necessary */ 960 961 for (i = 0; i < nsops; i++) { 962 sopptr = &sops[i]; 963 semptr = &semaptr->sem_base[sopptr->sem_num]; 964 965 DPRINTF(( 966 "semop: semaptr=%x, sem_base=%x, " 967 "semptr=%x, sem[%d]=%d : op=%d, flag=%s\n", 968 semaptr, semaptr->sem_base, semptr, 969 sopptr->sem_num, semptr->semval, sopptr->sem_op, 970 (sopptr->sem_flg & IPC_NOWAIT) ? 971 "nowait" : "wait")); 972 973 if (sopptr->sem_op < 0) { 974 if (semptr->semval + sopptr->sem_op < 0) { 975 DPRINTF(("semop: can't do it now\n")); 976 break; 977 } else { 978 semptr->semval += sopptr->sem_op; 979 if (semptr->semval == 0 && 980 semptr->semzcnt > 0) 981 do_wakeup = 1; 982 } 983 } else if (sopptr->sem_op == 0) { 984 if (semptr->semval != 0) { 985 DPRINTF(("semop: not zero now\n")); 986 break; 987 } 988 } else if (semptr->semval + sopptr->sem_op > 989 seminfo.semvmx) { 990 error = ERANGE; 991 break; 992 } else { 993 if (semptr->semncnt > 0) 994 do_wakeup = 1; 995 semptr->semval += sopptr->sem_op; 996 } 997 } 998 999 /* 1000 * Did we get through the entire vector? 1001 */ 1002 if (i >= nsops) 1003 goto done; 1004 1005 /* 1006 * No ... rollback anything that we've already done 1007 */ 1008 DPRINTF(("semop: rollback 0 through %d\n", i-1)); 1009 for (j = 0; j < i; j++) 1010 semaptr->sem_base[sops[j].sem_num].semval -= 1011 sops[j].sem_op; 1012 1013 /* If we detected an error, return it */ 1014 if (error != 0) 1015 goto done2; 1016 1017 /* 1018 * If the request that we couldn't satisfy has the 1019 * NOWAIT flag set then return with EAGAIN. 1020 */ 1021 if (sopptr->sem_flg & IPC_NOWAIT) { 1022 error = EAGAIN; 1023 goto done2; 1024 } 1025 1026 if (sopptr->sem_op == 0) 1027 semptr->semzcnt++; 1028 else 1029 semptr->semncnt++; 1030 1031 DPRINTF(("semop: good night!\n")); 1032 error = msleep(semaptr, sema_mtxp, (PZERO - 4) | PCATCH, 1033 "semwait", 0); 1034 DPRINTF(("semop: good morning (error=%d)!\n", error)); 1035 1036 if (error != 0) { 1037 error = EINTR; 1038 goto done2; 1039 } 1040 DPRINTF(("semop: good morning!\n")); 1041 1042 /* 1043 * Make sure that the semaphore still exists 1044 */ 1045 if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0 || 1046 semaptr->sem_perm.seq != IPCID_TO_SEQ(uap->semid)) { 1047 error = EIDRM; 1048 goto done2; 1049 } 1050 1051 /* 1052 * The semaphore is still alive. Readjust the count of 1053 * waiting processes. 1054 */ 1055 if (sopptr->sem_op == 0) 1056 semptr->semzcnt--; 1057 else 1058 semptr->semncnt--; 1059 } 1060 1061 done: 1062 /* 1063 * Process any SEM_UNDO requests. 1064 */ 1065 if (do_undos) { 1066 SEMUNDO_LOCK(); 1067 suptr = NULL; 1068 for (i = 0; i < nsops; i++) { 1069 /* 1070 * We only need to deal with SEM_UNDO's for non-zero 1071 * op's. 1072 */ 1073 int adjval; 1074 1075 if ((sops[i].sem_flg & SEM_UNDO) == 0) 1076 continue; 1077 adjval = sops[i].sem_op; 1078 if (adjval == 0) 1079 continue; 1080 error = semundo_adjust(td, &suptr, semid, 1081 sops[i].sem_num, -adjval); 1082 if (error == 0) 1083 continue; 1084 1085 /* 1086 * Oh-Oh! We ran out of either sem_undo's or undo's. 1087 * Rollback the adjustments to this point and then 1088 * rollback the semaphore ups and down so we can return 1089 * with an error with all structures restored. We 1090 * rollback the undo's in the exact reverse order that 1091 * we applied them. This guarantees that we won't run 1092 * out of space as we roll things back out. 1093 */ 1094 for (j = 0; j < i; j++) { 1095 k = i - j - 1; 1096 if ((sops[k].sem_flg & SEM_UNDO) == 0) 1097 continue; 1098 adjval = sops[k].sem_op; 1099 if (adjval == 0) 1100 continue; 1101 if (semundo_adjust(td, &suptr, semid, 1102 sops[k].sem_num, adjval) != 0) 1103 panic("semop - can't undo undos"); 1104 } 1105 1106 for (j = 0; j < nsops; j++) 1107 semaptr->sem_base[sops[j].sem_num].semval -= 1108 sops[j].sem_op; 1109 1110 DPRINTF(("error = %d from semundo_adjust\n", error)); 1111 SEMUNDO_UNLOCK(); 1112 goto done2; 1113 } /* loop through the sops */ 1114 SEMUNDO_UNLOCK(); 1115 } /* if (do_undos) */ 1116 1117 /* We're definitely done - set the sempid's and time */ 1118 for (i = 0; i < nsops; i++) { 1119 sopptr = &sops[i]; 1120 semptr = &semaptr->sem_base[sopptr->sem_num]; 1121 semptr->sempid = td->td_proc->p_pid; 1122 } 1123 semaptr->sem_otime = time_second; 1124 1125 /* 1126 * Do a wakeup if any semaphore was up'd whilst something was 1127 * sleeping on it. 1128 */ 1129 if (do_wakeup) { 1130 DPRINTF(("semop: doing wakeup\n")); 1131 wakeup(semaptr); 1132 DPRINTF(("semop: back from wakeup\n")); 1133 } 1134 DPRINTF(("semop: done\n")); 1135 td->td_retval[0] = 0; 1136 done2: 1137 mtx_unlock(sema_mtxp); 1138 free(sops, M_SEM); 1139 return (error); 1140 } 1141 1142 /* 1143 * Go through the undo structures for this process and apply the adjustments to 1144 * semaphores. 1145 */ 1146 static void 1147 semexit_myhook(arg, p) 1148 void *arg; 1149 struct proc *p; 1150 { 1151 struct sem_undo *suptr; 1152 struct sem_undo **supptr; 1153 1154 /* 1155 * Go through the chain of undo vectors looking for one 1156 * associated with this process. 1157 */ 1158 SEMUNDO_LOCK(); 1159 SLIST_FOREACH_PREVPTR(suptr, supptr, &semu_list, un_next) { 1160 if (suptr->un_proc == p) 1161 break; 1162 } 1163 SEMUNDO_UNLOCK(); 1164 1165 if (suptr == NULL) 1166 return; 1167 1168 DPRINTF(("proc @%08x has undo structure with %d entries\n", p, 1169 suptr->un_cnt)); 1170 1171 /* 1172 * If there are any active undo elements then process them. 1173 */ 1174 if (suptr->un_cnt > 0) { 1175 int ix; 1176 1177 for (ix = 0; ix < suptr->un_cnt; ix++) { 1178 int semid = suptr->un_ent[ix].un_id; 1179 int semnum = suptr->un_ent[ix].un_num; 1180 int adjval = suptr->un_ent[ix].un_adjval; 1181 struct semid_ds *semaptr; 1182 struct mtx *sema_mtxp; 1183 1184 semaptr = &sema[semid]; 1185 sema_mtxp = &sema_mtx[semid]; 1186 mtx_lock(sema_mtxp); 1187 SEMUNDO_LOCK(); 1188 if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0) 1189 panic("semexit - semid not allocated"); 1190 if (semnum >= semaptr->sem_nsems) 1191 panic("semexit - semnum out of range"); 1192 1193 DPRINTF(( 1194 "semexit: %08x id=%d num=%d(adj=%d) ; sem=%d\n", 1195 suptr->un_proc, suptr->un_ent[ix].un_id, 1196 suptr->un_ent[ix].un_num, 1197 suptr->un_ent[ix].un_adjval, 1198 semaptr->sem_base[semnum].semval)); 1199 1200 if (adjval < 0) { 1201 if (semaptr->sem_base[semnum].semval < -adjval) 1202 semaptr->sem_base[semnum].semval = 0; 1203 else 1204 semaptr->sem_base[semnum].semval += 1205 adjval; 1206 } else 1207 semaptr->sem_base[semnum].semval += adjval; 1208 1209 wakeup(semaptr); 1210 DPRINTF(("semexit: back from wakeup\n")); 1211 mtx_unlock(sema_mtxp); 1212 SEMUNDO_UNLOCK(); 1213 } 1214 } 1215 1216 /* 1217 * Deallocate the undo vector. 1218 */ 1219 DPRINTF(("removing vector\n")); 1220 suptr->un_proc = NULL; 1221 *supptr = SLIST_NEXT(suptr, un_next); 1222 } 1223 1224 static int 1225 sysctl_sema(SYSCTL_HANDLER_ARGS) 1226 { 1227 1228 return (SYSCTL_OUT(req, sema, 1229 sizeof(struct semid_ds) * seminfo.semmni)); 1230 } 1231