The Design and Implementation of the FreeBSD Operating System, Second Edition
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FreeBSD/Linux Kernel Cross Reference
sys/kern/sysv_sem.c

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    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  * Copyright (c) 2003-2005 McAfee, Inc.
   10  * All rights reserved.
   11  *
   12  * This software was developed for the FreeBSD Project in part by McAfee
   13  * Research, the Security Research Division of McAfee, Inc under DARPA/SPAWAR
   14  * contract N66001-01-C-8035 ("CBOSS"), as part of the DARPA CHATS research
   15  * program.
   16  *
   17  * Redistribution and use in source and binary forms, with or without
   18  * modification, are permitted provided that the following conditions
   19  * are met:
   20  * 1. Redistributions of source code must retain the above copyright
   21  *    notice, this list of conditions and the following disclaimer.
   22  * 2. Redistributions in binary form must reproduce the above copyright
   23  *    notice, this list of conditions and the following disclaimer in the
   24  *    documentation and/or other materials provided with the distribution.
   25  *
   26  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   27  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   28  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   29  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   30  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   31  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   32  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   33  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   34  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   35  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   36  * SUCH DAMAGE.
   37  */
   38 
   39 #include <sys/cdefs.h>
   40 __FBSDID("$FreeBSD: releng/10.2/sys/kern/sysv_sem.c 284665 2015-06-21 06:28:26Z trasz $");
   41 
   42 #include "opt_compat.h"
   43 #include "opt_sysvipc.h"
   44 
   45 #include <sys/param.h>
   46 #include <sys/systm.h>
   47 #include <sys/sysproto.h>
   48 #include <sys/eventhandler.h>
   49 #include <sys/kernel.h>
   50 #include <sys/proc.h>
   51 #include <sys/lock.h>
   52 #include <sys/module.h>
   53 #include <sys/mutex.h>
   54 #include <sys/racct.h>
   55 #include <sys/sem.h>
   56 #include <sys/syscall.h>
   57 #include <sys/syscallsubr.h>
   58 #include <sys/sysent.h>
   59 #include <sys/sysctl.h>
   60 #include <sys/uio.h>
   61 #include <sys/malloc.h>
   62 #include <sys/jail.h>
   63 
   64 #include <security/mac/mac_framework.h>
   65 
   66 FEATURE(sysv_sem, "System V semaphores support");
   67 
   68 static MALLOC_DEFINE(M_SEM, "sem", "SVID compatible semaphores");
   69 
   70 #ifdef SEM_DEBUG
   71 #define DPRINTF(a)      printf a
   72 #else
   73 #define DPRINTF(a)
   74 #endif
   75 
   76 static int seminit(void);
   77 static int sysvsem_modload(struct module *, int, void *);
   78 static int semunload(void);
   79 static void semexit_myhook(void *arg, struct proc *p);
   80 static int sysctl_sema(SYSCTL_HANDLER_ARGS);
   81 static int semvalid(int semid, struct semid_kernel *semakptr);
   82 
   83 #ifndef _SYS_SYSPROTO_H_
   84 struct __semctl_args;
   85 int __semctl(struct thread *td, struct __semctl_args *uap);
   86 struct semget_args;
   87 int semget(struct thread *td, struct semget_args *uap);
   88 struct semop_args;
   89 int semop(struct thread *td, struct semop_args *uap);
   90 #endif
   91 
   92 static struct sem_undo *semu_alloc(struct thread *td);
   93 static int semundo_adjust(struct thread *td, struct sem_undo **supptr,
   94     int semid, int semseq, int semnum, int adjval);
   95 static void semundo_clear(int semid, int semnum);
   96 
   97 static struct mtx       sem_mtx;        /* semaphore global lock */
   98 static struct mtx sem_undo_mtx;
   99 static int      semtot = 0;
  100 static struct semid_kernel *sema;       /* semaphore id pool */
  101 static struct mtx *sema_mtx;    /* semaphore id pool mutexes*/
  102 static struct sem *sem;         /* semaphore pool */
  103 LIST_HEAD(, sem_undo) semu_list;        /* list of active undo structures */
  104 LIST_HEAD(, sem_undo) semu_free_list;   /* list of free undo structures */
  105 static int      *semu;          /* undo structure pool */
  106 static eventhandler_tag semexit_tag;
  107 
  108 #define SEMUNDO_MTX             sem_undo_mtx
  109 #define SEMUNDO_LOCK()          mtx_lock(&SEMUNDO_MTX);
  110 #define SEMUNDO_UNLOCK()        mtx_unlock(&SEMUNDO_MTX);
  111 #define SEMUNDO_LOCKASSERT(how) mtx_assert(&SEMUNDO_MTX, (how));
  112 
  113 struct sem {
  114         u_short semval;         /* semaphore value */
  115         pid_t   sempid;         /* pid of last operation */
  116         u_short semncnt;        /* # awaiting semval > cval */
  117         u_short semzcnt;        /* # awaiting semval = 0 */
  118 };
  119 
  120 /*
  121  * Undo structure (one per process)
  122  */
  123 struct sem_undo {
  124         LIST_ENTRY(sem_undo) un_next;   /* ptr to next active undo structure */
  125         struct  proc *un_proc;          /* owner of this structure */
  126         short   un_cnt;                 /* # of active entries */
  127         struct undo {
  128                 short   un_adjval;      /* adjust on exit values */
  129                 short   un_num;         /* semaphore # */
  130                 int     un_id;          /* semid */
  131                 unsigned short un_seq;
  132         } un_ent[1];                    /* undo entries */
  133 };
  134 
  135 /*
  136  * Configuration parameters
  137  */
  138 #ifndef SEMMNI
  139 #define SEMMNI  50              /* # of semaphore identifiers */
  140 #endif
  141 #ifndef SEMMNS
  142 #define SEMMNS  340             /* # of semaphores in system */
  143 #endif
  144 #ifndef SEMUME
  145 #define SEMUME  50              /* max # of undo entries per process */
  146 #endif
  147 #ifndef SEMMNU
  148 #define SEMMNU  150             /* # of undo structures in system */
  149 #endif
  150 
  151 /* shouldn't need tuning */
  152 #ifndef SEMMSL
  153 #define SEMMSL  SEMMNS          /* max # of semaphores per id */
  154 #endif
  155 #ifndef SEMOPM
  156 #define SEMOPM  100             /* max # of operations per semop call */
  157 #endif
  158 
  159 #define SEMVMX  32767           /* semaphore maximum value */
  160 #define SEMAEM  16384           /* adjust on exit max value */
  161 
  162 /*
  163  * Due to the way semaphore memory is allocated, we have to ensure that
  164  * SEMUSZ is properly aligned.
  165  */
  166 
  167 #define SEM_ALIGN(bytes) (((bytes) + (sizeof(long) - 1)) & ~(sizeof(long) - 1))
  168 
  169 /* actual size of an undo structure */
  170 #define SEMUSZ  SEM_ALIGN(offsetof(struct sem_undo, un_ent[SEMUME]))
  171 
  172 /*
  173  * Macro to find a particular sem_undo vector
  174  */
  175 #define SEMU(ix) \
  176         ((struct sem_undo *)(((intptr_t)semu)+ix * seminfo.semusz))
  177 
  178 /*
  179  * semaphore info struct
  180  */
  181 struct seminfo seminfo = {
  182                 SEMMNI,         /* # of semaphore identifiers */
  183                 SEMMNS,         /* # of semaphores in system */
  184                 SEMMNU,         /* # of undo structures in system */
  185                 SEMMSL,         /* max # of semaphores per id */
  186                 SEMOPM,         /* max # of operations per semop call */
  187                 SEMUME,         /* max # of undo entries per process */
  188                 SEMUSZ,         /* size in bytes of undo structure */
  189                 SEMVMX,         /* semaphore maximum value */
  190                 SEMAEM          /* adjust on exit max value */
  191 };
  192 
  193 SYSCTL_INT(_kern_ipc, OID_AUTO, semmni, CTLFLAG_RDTUN, &seminfo.semmni, 0,
  194     "Number of semaphore identifiers");
  195 SYSCTL_INT(_kern_ipc, OID_AUTO, semmns, CTLFLAG_RDTUN, &seminfo.semmns, 0,
  196     "Maximum number of semaphores in the system");
  197 SYSCTL_INT(_kern_ipc, OID_AUTO, semmnu, CTLFLAG_RDTUN, &seminfo.semmnu, 0,
  198     "Maximum number of undo structures in the system");
  199 SYSCTL_INT(_kern_ipc, OID_AUTO, semmsl, CTLFLAG_RW, &seminfo.semmsl, 0,
  200     "Max semaphores per id");
  201 SYSCTL_INT(_kern_ipc, OID_AUTO, semopm, CTLFLAG_RDTUN, &seminfo.semopm, 0,
  202     "Max operations per semop call");
  203 SYSCTL_INT(_kern_ipc, OID_AUTO, semume, CTLFLAG_RDTUN, &seminfo.semume, 0,
  204     "Max undo entries per process");
  205 SYSCTL_INT(_kern_ipc, OID_AUTO, semusz, CTLFLAG_RDTUN, &seminfo.semusz, 0,
  206     "Size in bytes of undo structure");
  207 SYSCTL_INT(_kern_ipc, OID_AUTO, semvmx, CTLFLAG_RW, &seminfo.semvmx, 0,
  208     "Semaphore maximum value");
  209 SYSCTL_INT(_kern_ipc, OID_AUTO, semaem, CTLFLAG_RW, &seminfo.semaem, 0,
  210     "Adjust on exit max value");
  211 SYSCTL_PROC(_kern_ipc, OID_AUTO, sema, CTLTYPE_OPAQUE | CTLFLAG_RD,
  212     NULL, 0, sysctl_sema, "", "Semaphore id pool");
  213 
  214 static struct syscall_helper_data sem_syscalls[] = {
  215         SYSCALL_INIT_HELPER(__semctl),
  216         SYSCALL_INIT_HELPER(semget),
  217         SYSCALL_INIT_HELPER(semop),
  218 #if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \
  219     defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7)
  220         SYSCALL_INIT_HELPER(semsys),
  221         SYSCALL_INIT_HELPER_COMPAT(freebsd7___semctl),
  222 #endif
  223         SYSCALL_INIT_LAST
  224 };
  225 
  226 #ifdef COMPAT_FREEBSD32
  227 #include <compat/freebsd32/freebsd32.h>
  228 #include <compat/freebsd32/freebsd32_ipc.h>
  229 #include <compat/freebsd32/freebsd32_proto.h>
  230 #include <compat/freebsd32/freebsd32_signal.h>
  231 #include <compat/freebsd32/freebsd32_syscall.h>
  232 #include <compat/freebsd32/freebsd32_util.h>
  233 
  234 static struct syscall_helper_data sem32_syscalls[] = {
  235         SYSCALL32_INIT_HELPER(freebsd32_semctl),
  236         SYSCALL32_INIT_HELPER_COMPAT(semget),
  237         SYSCALL32_INIT_HELPER_COMPAT(semop),
  238         SYSCALL32_INIT_HELPER(freebsd32_semsys),
  239 #if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \
  240     defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7)
  241         SYSCALL32_INIT_HELPER(freebsd7_freebsd32_semctl),
  242 #endif
  243         SYSCALL_INIT_LAST
  244 };
  245 #endif
  246 
  247 static int
  248 seminit(void)
  249 {
  250         int i, error;
  251 
  252         TUNABLE_INT_FETCH("kern.ipc.semmni", &seminfo.semmni);
  253         TUNABLE_INT_FETCH("kern.ipc.semmns", &seminfo.semmns);
  254         TUNABLE_INT_FETCH("kern.ipc.semmnu", &seminfo.semmnu);
  255         TUNABLE_INT_FETCH("kern.ipc.semmsl", &seminfo.semmsl);
  256         TUNABLE_INT_FETCH("kern.ipc.semopm", &seminfo.semopm);
  257         TUNABLE_INT_FETCH("kern.ipc.semume", &seminfo.semume);
  258         TUNABLE_INT_FETCH("kern.ipc.semusz", &seminfo.semusz);
  259         TUNABLE_INT_FETCH("kern.ipc.semvmx", &seminfo.semvmx);
  260         TUNABLE_INT_FETCH("kern.ipc.semaem", &seminfo.semaem);
  261 
  262         sem = malloc(sizeof(struct sem) * seminfo.semmns, M_SEM, M_WAITOK);
  263         sema = malloc(sizeof(struct semid_kernel) * seminfo.semmni, M_SEM,
  264             M_WAITOK);
  265         sema_mtx = malloc(sizeof(struct mtx) * seminfo.semmni, M_SEM,
  266             M_WAITOK | M_ZERO);
  267         semu = malloc(seminfo.semmnu * seminfo.semusz, M_SEM, M_WAITOK);
  268 
  269         for (i = 0; i < seminfo.semmni; i++) {
  270                 sema[i].u.sem_base = 0;
  271                 sema[i].u.sem_perm.mode = 0;
  272                 sema[i].u.sem_perm.seq = 0;
  273 #ifdef MAC
  274                 mac_sysvsem_init(&sema[i]);
  275 #endif
  276         }
  277         for (i = 0; i < seminfo.semmni; i++)
  278                 mtx_init(&sema_mtx[i], "semid", NULL, MTX_DEF);
  279         LIST_INIT(&semu_free_list);
  280         for (i = 0; i < seminfo.semmnu; i++) {
  281                 struct sem_undo *suptr = SEMU(i);
  282                 suptr->un_proc = NULL;
  283                 LIST_INSERT_HEAD(&semu_free_list, suptr, un_next);
  284         }
  285         LIST_INIT(&semu_list);
  286         mtx_init(&sem_mtx, "sem", NULL, MTX_DEF);
  287         mtx_init(&sem_undo_mtx, "semu", NULL, MTX_DEF);
  288         semexit_tag = EVENTHANDLER_REGISTER(process_exit, semexit_myhook, NULL,
  289             EVENTHANDLER_PRI_ANY);
  290 
  291         error = syscall_helper_register(sem_syscalls);
  292         if (error != 0)
  293                 return (error);
  294 #ifdef COMPAT_FREEBSD32
  295         error = syscall32_helper_register(sem32_syscalls);
  296         if (error != 0)
  297                 return (error);
  298 #endif
  299         return (0);
  300 }
  301 
  302 static int
  303 semunload(void)
  304 {
  305         int i;
  306 
  307         /* XXXKIB */
  308         if (semtot != 0)
  309                 return (EBUSY);
  310 
  311 #ifdef COMPAT_FREEBSD32
  312         syscall32_helper_unregister(sem32_syscalls);
  313 #endif
  314         syscall_helper_unregister(sem_syscalls);
  315         EVENTHANDLER_DEREGISTER(process_exit, semexit_tag);
  316 #ifdef MAC
  317         for (i = 0; i < seminfo.semmni; i++)
  318                 mac_sysvsem_destroy(&sema[i]);
  319 #endif
  320         free(sem, M_SEM);
  321         free(sema, M_SEM);
  322         free(semu, M_SEM);
  323         for (i = 0; i < seminfo.semmni; i++)
  324                 mtx_destroy(&sema_mtx[i]);
  325         free(sema_mtx, M_SEM);
  326         mtx_destroy(&sem_mtx);
  327         mtx_destroy(&sem_undo_mtx);
  328         return (0);
  329 }
  330 
  331 static int
  332 sysvsem_modload(struct module *module, int cmd, void *arg)
  333 {
  334         int error = 0;
  335 
  336         switch (cmd) {
  337         case MOD_LOAD:
  338                 error = seminit();
  339                 if (error != 0)
  340                         semunload();
  341                 break;
  342         case MOD_UNLOAD:
  343                 error = semunload();
  344                 break;
  345         case MOD_SHUTDOWN:
  346                 break;
  347         default:
  348                 error = EINVAL;
  349                 break;
  350         }
  351         return (error);
  352 }
  353 
  354 static moduledata_t sysvsem_mod = {
  355         "sysvsem",
  356         &sysvsem_modload,
  357         NULL
  358 };
  359 
  360 DECLARE_MODULE(sysvsem, sysvsem_mod, SI_SUB_SYSV_SEM, SI_ORDER_FIRST);
  361 MODULE_VERSION(sysvsem, 1);
  362 
  363 /*
  364  * Allocate a new sem_undo structure for a process
  365  * (returns ptr to structure or NULL if no more room)
  366  */
  367 
  368 static struct sem_undo *
  369 semu_alloc(struct thread *td)
  370 {
  371         struct sem_undo *suptr;
  372 
  373         SEMUNDO_LOCKASSERT(MA_OWNED);
  374         if ((suptr = LIST_FIRST(&semu_free_list)) == NULL)
  375                 return (NULL);
  376         LIST_REMOVE(suptr, un_next);
  377         LIST_INSERT_HEAD(&semu_list, suptr, un_next);
  378         suptr->un_cnt = 0;
  379         suptr->un_proc = td->td_proc;
  380         return (suptr);
  381 }
  382 
  383 static int
  384 semu_try_free(struct sem_undo *suptr)
  385 {
  386 
  387         SEMUNDO_LOCKASSERT(MA_OWNED);
  388 
  389         if (suptr->un_cnt != 0)
  390                 return (0);
  391         LIST_REMOVE(suptr, un_next);
  392         LIST_INSERT_HEAD(&semu_free_list, suptr, un_next);
  393         return (1);
  394 }
  395 
  396 /*
  397  * Adjust a particular entry for a particular proc
  398  */
  399 
  400 static int
  401 semundo_adjust(struct thread *td, struct sem_undo **supptr, int semid,
  402     int semseq, int semnum, int adjval)
  403 {
  404         struct proc *p = td->td_proc;
  405         struct sem_undo *suptr;
  406         struct undo *sunptr;
  407         int i;
  408 
  409         SEMUNDO_LOCKASSERT(MA_OWNED);
  410         /* Look for and remember the sem_undo if the caller doesn't provide
  411            it */
  412 
  413         suptr = *supptr;
  414         if (suptr == NULL) {
  415                 LIST_FOREACH(suptr, &semu_list, un_next) {
  416                         if (suptr->un_proc == p) {
  417                                 *supptr = suptr;
  418                                 break;
  419                         }
  420                 }
  421                 if (suptr == NULL) {
  422                         if (adjval == 0)
  423                                 return(0);
  424                         suptr = semu_alloc(td);
  425                         if (suptr == NULL)
  426                                 return (ENOSPC);
  427                         *supptr = suptr;
  428                 }
  429         }
  430 
  431         /*
  432          * Look for the requested entry and adjust it (delete if adjval becomes
  433          * 0).
  434          */
  435         sunptr = &suptr->un_ent[0];
  436         for (i = 0; i < suptr->un_cnt; i++, sunptr++) {
  437                 if (sunptr->un_id != semid || sunptr->un_num != semnum)
  438                         continue;
  439                 if (adjval != 0) {
  440                         adjval += sunptr->un_adjval;
  441                         if (adjval > seminfo.semaem || adjval < -seminfo.semaem)
  442                                 return (ERANGE);
  443                 }
  444                 sunptr->un_adjval = adjval;
  445                 if (sunptr->un_adjval == 0) {
  446                         suptr->un_cnt--;
  447                         if (i < suptr->un_cnt)
  448                                 suptr->un_ent[i] =
  449                                     suptr->un_ent[suptr->un_cnt];
  450                         if (suptr->un_cnt == 0)
  451                                 semu_try_free(suptr);
  452                 }
  453                 return (0);
  454         }
  455 
  456         /* Didn't find the right entry - create it */
  457         if (adjval == 0)
  458                 return (0);
  459         if (adjval > seminfo.semaem || adjval < -seminfo.semaem)
  460                 return (ERANGE);
  461         if (suptr->un_cnt != seminfo.semume) {
  462                 sunptr = &suptr->un_ent[suptr->un_cnt];
  463                 suptr->un_cnt++;
  464                 sunptr->un_adjval = adjval;
  465                 sunptr->un_id = semid;
  466                 sunptr->un_num = semnum;
  467                 sunptr->un_seq = semseq;
  468         } else
  469                 return (EINVAL);
  470         return (0);
  471 }
  472 
  473 static void
  474 semundo_clear(int semid, int semnum)
  475 {
  476         struct sem_undo *suptr, *suptr1;
  477         struct undo *sunptr;
  478         int i;
  479 
  480         SEMUNDO_LOCKASSERT(MA_OWNED);
  481         LIST_FOREACH_SAFE(suptr, &semu_list, un_next, suptr1) {
  482                 sunptr = &suptr->un_ent[0];
  483                 for (i = 0; i < suptr->un_cnt; i++, sunptr++) {
  484                         if (sunptr->un_id != semid)
  485                                 continue;
  486                         if (semnum == -1 || sunptr->un_num == semnum) {
  487                                 suptr->un_cnt--;
  488                                 if (i < suptr->un_cnt) {
  489                                         suptr->un_ent[i] =
  490                                             suptr->un_ent[suptr->un_cnt];
  491                                         continue;
  492                                 }
  493                                 semu_try_free(suptr);
  494                         }
  495                         if (semnum != -1)
  496                                 break;
  497                 }
  498         }
  499 }
  500 
  501 static int
  502 semvalid(int semid, struct semid_kernel *semakptr)
  503 {
  504 
  505         return ((semakptr->u.sem_perm.mode & SEM_ALLOC) == 0 ||
  506             semakptr->u.sem_perm.seq != IPCID_TO_SEQ(semid) ? EINVAL : 0);
  507 }
  508 
  509 /*
  510  * Note that the user-mode half of this passes a union, not a pointer.
  511  */
  512 #ifndef _SYS_SYSPROTO_H_
  513 struct __semctl_args {
  514         int     semid;
  515         int     semnum;
  516         int     cmd;
  517         union   semun *arg;
  518 };
  519 #endif
  520 int
  521 sys___semctl(struct thread *td, struct __semctl_args *uap)
  522 {
  523         struct semid_ds dsbuf;
  524         union semun arg, semun;
  525         register_t rval;
  526         int error;
  527 
  528         switch (uap->cmd) {
  529         case SEM_STAT:
  530         case IPC_SET:
  531         case IPC_STAT:
  532         case GETALL:
  533         case SETVAL:
  534         case SETALL:
  535                 error = copyin(uap->arg, &arg, sizeof(arg));
  536                 if (error)
  537                         return (error);
  538                 break;
  539         }
  540 
  541         switch (uap->cmd) {
  542         case SEM_STAT:
  543         case IPC_STAT:
  544                 semun.buf = &dsbuf;
  545                 break;
  546         case IPC_SET:
  547                 error = copyin(arg.buf, &dsbuf, sizeof(dsbuf));
  548                 if (error)
  549                         return (error);
  550                 semun.buf = &dsbuf;
  551                 break;
  552         case GETALL:
  553         case SETALL:
  554                 semun.array = arg.array;
  555                 break;
  556         case SETVAL:
  557                 semun.val = arg.val;
  558                 break;          
  559         }
  560 
  561         error = kern_semctl(td, uap->semid, uap->semnum, uap->cmd, &semun,
  562             &rval);
  563         if (error)
  564                 return (error);
  565 
  566         switch (uap->cmd) {
  567         case SEM_STAT:
  568         case IPC_STAT:
  569                 error = copyout(&dsbuf, arg.buf, sizeof(dsbuf));
  570                 break;
  571         }
  572 
  573         if (error == 0)
  574                 td->td_retval[0] = rval;
  575         return (error);
  576 }
  577 
  578 int
  579 kern_semctl(struct thread *td, int semid, int semnum, int cmd,
  580     union semun *arg, register_t *rval)
  581 {
  582         u_short *array;
  583         struct ucred *cred = td->td_ucred;
  584         int i, error;
  585         struct semid_ds *sbuf;
  586         struct semid_kernel *semakptr;
  587         struct mtx *sema_mtxp;
  588         u_short usval, count;
  589         int semidx;
  590 
  591         DPRINTF(("call to semctl(%d, %d, %d, 0x%p)\n",
  592             semid, semnum, cmd, arg));
  593         if (!prison_allow(td->td_ucred, PR_ALLOW_SYSVIPC))
  594                 return (ENOSYS);
  595 
  596         array = NULL;
  597 
  598         switch(cmd) {
  599         case SEM_STAT:
  600                 /*
  601                  * For this command we assume semid is an array index
  602                  * rather than an IPC id.
  603                  */
  604                 if (semid < 0 || semid >= seminfo.semmni)
  605                         return (EINVAL);
  606                 semakptr = &sema[semid];
  607                 sema_mtxp = &sema_mtx[semid];
  608                 mtx_lock(sema_mtxp);
  609                 if ((semakptr->u.sem_perm.mode & SEM_ALLOC) == 0) {
  610                         error = EINVAL;
  611                         goto done2;
  612                 }
  613                 if ((error = ipcperm(td, &semakptr->u.sem_perm, IPC_R)))
  614                         goto done2;
  615 #ifdef MAC
  616                 error = mac_sysvsem_check_semctl(cred, semakptr, cmd);
  617                 if (error != 0)
  618                         goto done2;
  619 #endif
  620                 bcopy(&semakptr->u, arg->buf, sizeof(struct semid_ds));
  621                 *rval = IXSEQ_TO_IPCID(semid, semakptr->u.sem_perm);
  622                 mtx_unlock(sema_mtxp);
  623                 return (0);
  624         }
  625 
  626         semidx = IPCID_TO_IX(semid);
  627         if (semidx < 0 || semidx >= seminfo.semmni)
  628                 return (EINVAL);
  629 
  630         semakptr = &sema[semidx];
  631         sema_mtxp = &sema_mtx[semidx];
  632         if (cmd == IPC_RMID)
  633                 mtx_lock(&sem_mtx);
  634         mtx_lock(sema_mtxp);
  635 #ifdef MAC
  636         error = mac_sysvsem_check_semctl(cred, semakptr, cmd);
  637         if (error != 0)
  638                 goto done2;
  639 #endif
  640 
  641         error = 0;
  642         *rval = 0;
  643 
  644         switch (cmd) {
  645         case IPC_RMID:
  646                 if ((error = semvalid(semid, semakptr)) != 0)
  647                         goto done2;
  648                 if ((error = ipcperm(td, &semakptr->u.sem_perm, IPC_M)))
  649                         goto done2;
  650                 semakptr->u.sem_perm.cuid = cred->cr_uid;
  651                 semakptr->u.sem_perm.uid = cred->cr_uid;
  652                 semakptr->u.sem_perm.mode = 0;
  653                 racct_sub_cred(semakptr->cred, RACCT_NSEM, semakptr->u.sem_nsems);
  654                 crfree(semakptr->cred);
  655                 semakptr->cred = NULL;
  656                 SEMUNDO_LOCK();
  657                 semundo_clear(semidx, -1);
  658                 SEMUNDO_UNLOCK();
  659 #ifdef MAC
  660                 mac_sysvsem_cleanup(semakptr);
  661 #endif
  662                 wakeup(semakptr);
  663                 for (i = 0; i < seminfo.semmni; i++) {
  664                         if ((sema[i].u.sem_perm.mode & SEM_ALLOC) &&
  665                             sema[i].u.sem_base > semakptr->u.sem_base)
  666                                 mtx_lock_flags(&sema_mtx[i], LOP_DUPOK);
  667                 }
  668                 for (i = semakptr->u.sem_base - sem; i < semtot; i++)
  669                         sem[i] = sem[i + semakptr->u.sem_nsems];
  670                 for (i = 0; i < seminfo.semmni; i++) {
  671                         if ((sema[i].u.sem_perm.mode & SEM_ALLOC) &&
  672                             sema[i].u.sem_base > semakptr->u.sem_base) {
  673                                 sema[i].u.sem_base -= semakptr->u.sem_nsems;
  674                                 mtx_unlock(&sema_mtx[i]);
  675                         }
  676                 }
  677                 semtot -= semakptr->u.sem_nsems;
  678                 break;
  679 
  680         case IPC_SET:
  681                 if ((error = semvalid(semid, semakptr)) != 0)
  682                         goto done2;
  683                 if ((error = ipcperm(td, &semakptr->u.sem_perm, IPC_M)))
  684                         goto done2;
  685                 sbuf = arg->buf;
  686                 semakptr->u.sem_perm.uid = sbuf->sem_perm.uid;
  687                 semakptr->u.sem_perm.gid = sbuf->sem_perm.gid;
  688                 semakptr->u.sem_perm.mode = (semakptr->u.sem_perm.mode &
  689                     ~0777) | (sbuf->sem_perm.mode & 0777);
  690                 semakptr->u.sem_ctime = time_second;
  691                 break;
  692 
  693         case IPC_STAT:
  694                 if ((error = semvalid(semid, semakptr)) != 0)
  695                         goto done2;
  696                 if ((error = ipcperm(td, &semakptr->u.sem_perm, IPC_R)))
  697                         goto done2;
  698                 bcopy(&semakptr->u, arg->buf, sizeof(struct semid_ds));
  699                 break;
  700 
  701         case GETNCNT:
  702                 if ((error = semvalid(semid, semakptr)) != 0)
  703                         goto done2;
  704                 if ((error = ipcperm(td, &semakptr->u.sem_perm, IPC_R)))
  705                         goto done2;
  706                 if (semnum < 0 || semnum >= semakptr->u.sem_nsems) {
  707                         error = EINVAL;
  708                         goto done2;
  709                 }
  710                 *rval = semakptr->u.sem_base[semnum].semncnt;
  711                 break;
  712 
  713         case GETPID:
  714                 if ((error = semvalid(semid, semakptr)) != 0)
  715                         goto done2;
  716                 if ((error = ipcperm(td, &semakptr->u.sem_perm, IPC_R)))
  717                         goto done2;
  718                 if (semnum < 0 || semnum >= semakptr->u.sem_nsems) {
  719                         error = EINVAL;
  720                         goto done2;
  721                 }
  722                 *rval = semakptr->u.sem_base[semnum].sempid;
  723                 break;
  724 
  725         case GETVAL:
  726                 if ((error = semvalid(semid, semakptr)) != 0)
  727                         goto done2;
  728                 if ((error = ipcperm(td, &semakptr->u.sem_perm, IPC_R)))
  729                         goto done2;
  730                 if (semnum < 0 || semnum >= semakptr->u.sem_nsems) {
  731                         error = EINVAL;
  732                         goto done2;
  733                 }
  734                 *rval = semakptr->u.sem_base[semnum].semval;
  735                 break;
  736 
  737         case GETALL:
  738                 /*
  739                  * Unfortunately, callers of this function don't know
  740                  * in advance how many semaphores are in this set.
  741                  * While we could just allocate the maximum size array
  742                  * and pass the actual size back to the caller, that
  743                  * won't work for SETALL since we can't copyin() more
  744                  * data than the user specified as we may return a
  745                  * spurious EFAULT.
  746                  * 
  747                  * Note that the number of semaphores in a set is
  748                  * fixed for the life of that set.  The only way that
  749                  * the 'count' could change while are blocked in
  750                  * malloc() is if this semaphore set were destroyed
  751                  * and a new one created with the same index.
  752                  * However, semvalid() will catch that due to the
  753                  * sequence number unless exactly 0x8000 (or a
  754                  * multiple thereof) semaphore sets for the same index
  755                  * are created and destroyed while we are in malloc!
  756                  *
  757                  */
  758                 count = semakptr->u.sem_nsems;
  759                 mtx_unlock(sema_mtxp);              
  760                 array = malloc(sizeof(*array) * count, M_TEMP, M_WAITOK);
  761                 mtx_lock(sema_mtxp);
  762                 if ((error = semvalid(semid, semakptr)) != 0)
  763                         goto done2;
  764                 KASSERT(count == semakptr->u.sem_nsems, ("nsems changed"));
  765                 if ((error = ipcperm(td, &semakptr->u.sem_perm, IPC_R)))
  766                         goto done2;
  767                 for (i = 0; i < semakptr->u.sem_nsems; i++)
  768                         array[i] = semakptr->u.sem_base[i].semval;
  769                 mtx_unlock(sema_mtxp);
  770                 error = copyout(array, arg->array, count * sizeof(*array));
  771                 mtx_lock(sema_mtxp);
  772                 break;
  773 
  774         case GETZCNT:
  775                 if ((error = semvalid(semid, semakptr)) != 0)
  776                         goto done2;
  777                 if ((error = ipcperm(td, &semakptr->u.sem_perm, IPC_R)))
  778                         goto done2;
  779                 if (semnum < 0 || semnum >= semakptr->u.sem_nsems) {
  780                         error = EINVAL;
  781                         goto done2;
  782                 }
  783                 *rval = semakptr->u.sem_base[semnum].semzcnt;
  784                 break;
  785 
  786         case SETVAL:
  787                 if ((error = semvalid(semid, semakptr)) != 0)
  788                         goto done2;
  789                 if ((error = ipcperm(td, &semakptr->u.sem_perm, IPC_W)))
  790                         goto done2;
  791                 if (semnum < 0 || semnum >= semakptr->u.sem_nsems) {
  792                         error = EINVAL;
  793                         goto done2;
  794                 }
  795                 if (arg->val < 0 || arg->val > seminfo.semvmx) {
  796                         error = ERANGE;
  797                         goto done2;
  798                 }
  799                 semakptr->u.sem_base[semnum].semval = arg->val;
  800                 SEMUNDO_LOCK();
  801                 semundo_clear(semidx, semnum);
  802                 SEMUNDO_UNLOCK();
  803                 wakeup(semakptr);
  804                 break;
  805 
  806         case SETALL:
  807                 /*
  808                  * See comment on GETALL for why 'count' shouldn't change
  809                  * and why we require a userland buffer.
  810                  */
  811                 count = semakptr->u.sem_nsems;
  812                 mtx_unlock(sema_mtxp);              
  813                 array = malloc(sizeof(*array) * count, M_TEMP, M_WAITOK);
  814                 error = copyin(arg->array, array, count * sizeof(*array));
  815                 mtx_lock(sema_mtxp);
  816                 if (error)
  817                         break;
  818                 if ((error = semvalid(semid, semakptr)) != 0)
  819                         goto done2;
  820                 KASSERT(count == semakptr->u.sem_nsems, ("nsems changed"));
  821                 if ((error = ipcperm(td, &semakptr->u.sem_perm, IPC_W)))
  822                         goto done2;
  823                 for (i = 0; i < semakptr->u.sem_nsems; i++) {
  824                         usval = array[i];
  825                         if (usval > seminfo.semvmx) {
  826                                 error = ERANGE;
  827                                 break;
  828                         }
  829                         semakptr->u.sem_base[i].semval = usval;
  830                 }
  831                 SEMUNDO_LOCK();
  832                 semundo_clear(semidx, -1);
  833                 SEMUNDO_UNLOCK();
  834                 wakeup(semakptr);
  835                 break;
  836 
  837         default:
  838                 error = EINVAL;
  839                 break;
  840         }
  841 
  842 done2:
  843         mtx_unlock(sema_mtxp);
  844         if (cmd == IPC_RMID)
  845                 mtx_unlock(&sem_mtx);
  846         if (array != NULL)
  847                 free(array, M_TEMP);
  848         return(error);
  849 }
  850 
  851 #ifndef _SYS_SYSPROTO_H_
  852 struct semget_args {
  853         key_t   key;
  854         int     nsems;
  855         int     semflg;
  856 };
  857 #endif
  858 int
  859 sys_semget(struct thread *td, struct semget_args *uap)
  860 {
  861         int semid, error = 0;
  862         int key = uap->key;
  863         int nsems = uap->nsems;
  864         int semflg = uap->semflg;
  865         struct ucred *cred = td->td_ucred;
  866 
  867         DPRINTF(("semget(0x%x, %d, 0%o)\n", key, nsems, semflg));
  868         if (!prison_allow(td->td_ucred, PR_ALLOW_SYSVIPC))
  869                 return (ENOSYS);
  870 
  871         mtx_lock(&sem_mtx);
  872         if (key != IPC_PRIVATE) {
  873                 for (semid = 0; semid < seminfo.semmni; semid++) {
  874                         if ((sema[semid].u.sem_perm.mode & SEM_ALLOC) &&
  875                             sema[semid].u.sem_perm.key == key)
  876                                 break;
  877                 }
  878                 if (semid < seminfo.semmni) {
  879                         DPRINTF(("found public key\n"));
  880                         if ((error = ipcperm(td, &sema[semid].u.sem_perm,
  881                             semflg & 0700))) {
  882                                 goto done2;
  883                         }
  884                         if (nsems > 0 && sema[semid].u.sem_nsems < nsems) {
  885                                 DPRINTF(("too small\n"));
  886                                 error = EINVAL;
  887                                 goto done2;
  888                         }
  889                         if ((semflg & IPC_CREAT) && (semflg & IPC_EXCL)) {
  890                                 DPRINTF(("not exclusive\n"));
  891                                 error = EEXIST;
  892                                 goto done2;
  893                         }
  894 #ifdef MAC
  895                         error = mac_sysvsem_check_semget(cred, &sema[semid]);
  896                         if (error != 0)
  897                                 goto done2;
  898 #endif
  899                         goto found;
  900                 }
  901         }
  902 
  903         DPRINTF(("need to allocate the semid_kernel\n"));
  904         if (key == IPC_PRIVATE || (semflg & IPC_CREAT)) {
  905                 if (nsems <= 0 || nsems > seminfo.semmsl) {
  906                         DPRINTF(("nsems out of range (0<%d<=%d)\n", nsems,
  907                             seminfo.semmsl));
  908                         error = EINVAL;
  909                         goto done2;
  910                 }
  911                 if (nsems > seminfo.semmns - semtot) {
  912                         DPRINTF((
  913                             "not enough semaphores left (need %d, got %d)\n",
  914                             nsems, seminfo.semmns - semtot));
  915                         error = ENOSPC;
  916                         goto done2;
  917                 }
  918                 for (semid = 0; semid < seminfo.semmni; semid++) {
  919                         if ((sema[semid].u.sem_perm.mode & SEM_ALLOC) == 0)
  920                                 break;
  921                 }
  922                 if (semid == seminfo.semmni) {
  923                         DPRINTF(("no more semid_kernel's available\n"));
  924                         error = ENOSPC;
  925                         goto done2;
  926                 }
  927 #ifdef RACCT
  928                 if (racct_enable) {
  929                         PROC_LOCK(td->td_proc);
  930                         error = racct_add(td->td_proc, RACCT_NSEM, nsems);
  931                         PROC_UNLOCK(td->td_proc);
  932                         if (error != 0) {
  933                                 error = ENOSPC;
  934                                 goto done2;
  935                         }
  936                 }
  937 #endif
  938                 DPRINTF(("semid %d is available\n", semid));
  939                 mtx_lock(&sema_mtx[semid]);
  940                 KASSERT((sema[semid].u.sem_perm.mode & SEM_ALLOC) == 0,
  941                     ("Lost semaphore %d", semid));
  942                 sema[semid].u.sem_perm.key = key;
  943                 sema[semid].u.sem_perm.cuid = cred->cr_uid;
  944                 sema[semid].u.sem_perm.uid = cred->cr_uid;
  945                 sema[semid].u.sem_perm.cgid = cred->cr_gid;
  946                 sema[semid].u.sem_perm.gid = cred->cr_gid;
  947                 sema[semid].u.sem_perm.mode = (semflg & 0777) | SEM_ALLOC;
  948                 sema[semid].cred = crhold(cred);
  949                 sema[semid].u.sem_perm.seq =
  950                     (sema[semid].u.sem_perm.seq + 1) & 0x7fff;
  951                 sema[semid].u.sem_nsems = nsems;
  952                 sema[semid].u.sem_otime = 0;
  953                 sema[semid].u.sem_ctime = time_second;
  954                 sema[semid].u.sem_base = &sem[semtot];
  955                 semtot += nsems;
  956                 bzero(sema[semid].u.sem_base,
  957                     sizeof(sema[semid].u.sem_base[0])*nsems);
  958 #ifdef MAC
  959                 mac_sysvsem_create(cred, &sema[semid]);
  960 #endif
  961                 mtx_unlock(&sema_mtx[semid]);
  962                 DPRINTF(("sembase = %p, next = %p\n",
  963                     sema[semid].u.sem_base, &sem[semtot]));
  964         } else {
  965                 DPRINTF(("didn't find it and wasn't asked to create it\n"));
  966                 error = ENOENT;
  967                 goto done2;
  968         }
  969 
  970 found:
  971         td->td_retval[0] = IXSEQ_TO_IPCID(semid, sema[semid].u.sem_perm);
  972 done2:
  973         mtx_unlock(&sem_mtx);
  974         return (error);
  975 }
  976 
  977 #ifndef _SYS_SYSPROTO_H_
  978 struct semop_args {
  979         int     semid;
  980         struct  sembuf *sops;
  981         size_t  nsops;
  982 };
  983 #endif
  984 int
  985 sys_semop(struct thread *td, struct semop_args *uap)
  986 {
  987 #define SMALL_SOPS      8
  988         struct sembuf small_sops[SMALL_SOPS];
  989         int semid = uap->semid;
  990         size_t nsops = uap->nsops;
  991         struct sembuf *sops;
  992         struct semid_kernel *semakptr;
  993         struct sembuf *sopptr = 0;
  994         struct sem *semptr = 0;
  995         struct sem_undo *suptr;
  996         struct mtx *sema_mtxp;
  997         size_t i, j, k;
  998         int error;
  999         int do_wakeup, do_undos;
 1000         unsigned short seq;
 1001 
 1002 #ifdef SEM_DEBUG
 1003         sops = NULL;
 1004 #endif
 1005         DPRINTF(("call to semop(%d, %p, %u)\n", semid, sops, nsops));
 1006 
 1007         if (!prison_allow(td->td_ucred, PR_ALLOW_SYSVIPC))
 1008                 return (ENOSYS);
 1009 
 1010         semid = IPCID_TO_IX(semid);     /* Convert back to zero origin */
 1011 
 1012         if (semid < 0 || semid >= seminfo.semmni)
 1013                 return (EINVAL);
 1014 
 1015         /* Allocate memory for sem_ops */
 1016         if (nsops <= SMALL_SOPS)
 1017                 sops = small_sops;
 1018         else if (nsops > seminfo.semopm) {
 1019                 DPRINTF(("too many sops (max=%d, nsops=%d)\n", seminfo.semopm,
 1020                     nsops));
 1021                 return (E2BIG);
 1022         } else {
 1023 #ifdef RACCT
 1024                 if (racct_enable) {
 1025                         PROC_LOCK(td->td_proc);
 1026                         if (nsops >
 1027                             racct_get_available(td->td_proc, RACCT_NSEMOP)) {
 1028                                 PROC_UNLOCK(td->td_proc);
 1029                                 return (E2BIG);
 1030                         }
 1031                         PROC_UNLOCK(td->td_proc);
 1032                 }
 1033 #endif
 1034 
 1035                 sops = malloc(nsops * sizeof(*sops), M_TEMP, M_WAITOK);
 1036         }
 1037         if ((error = copyin(uap->sops, sops, nsops * sizeof(sops[0]))) != 0) {
 1038                 DPRINTF(("error = %d from copyin(%p, %p, %d)\n", error,
 1039                     uap->sops, sops, nsops * sizeof(sops[0])));
 1040                 if (sops != small_sops)
 1041                         free(sops, M_SEM);
 1042                 return (error);
 1043         }
 1044 
 1045         semakptr = &sema[semid];
 1046         sema_mtxp = &sema_mtx[semid];
 1047         mtx_lock(sema_mtxp);
 1048         if ((semakptr->u.sem_perm.mode & SEM_ALLOC) == 0) {
 1049                 error = EINVAL;
 1050                 goto done2;
 1051         }
 1052         seq = semakptr->u.sem_perm.seq;
 1053         if (seq != IPCID_TO_SEQ(uap->semid)) {
 1054                 error = EINVAL;
 1055                 goto done2;
 1056         }
 1057         /*
 1058          * Initial pass thru sops to see what permissions are needed.
 1059          * Also perform any checks that don't need repeating on each
 1060          * attempt to satisfy the request vector.
 1061          */
 1062         j = 0;          /* permission needed */
 1063         do_undos = 0;
 1064         for (i = 0; i < nsops; i++) {
 1065                 sopptr = &sops[i];
 1066                 if (sopptr->sem_num >= semakptr->u.sem_nsems) {
 1067                         error = EFBIG;
 1068                         goto done2;
 1069                 }
 1070                 if (sopptr->sem_flg & SEM_UNDO && sopptr->sem_op != 0)
 1071                         do_undos = 1;
 1072                 j |= (sopptr->sem_op == 0) ? SEM_R : SEM_A;
 1073         }
 1074 
 1075         if ((error = ipcperm(td, &semakptr->u.sem_perm, j))) {
 1076                 DPRINTF(("error = %d from ipaccess\n", error));
 1077                 goto done2;
 1078         }
 1079 #ifdef MAC
 1080         error = mac_sysvsem_check_semop(td->td_ucred, semakptr, j);
 1081         if (error != 0)
 1082                 goto done2;
 1083 #endif
 1084 
 1085         /*
 1086          * Loop trying to satisfy the vector of requests.
 1087          * If we reach a point where we must wait, any requests already
 1088          * performed are rolled back and we go to sleep until some other
 1089          * process wakes us up.  At this point, we start all over again.
 1090          *
 1091          * This ensures that from the perspective of other tasks, a set
 1092          * of requests is atomic (never partially satisfied).
 1093          */
 1094         for (;;) {
 1095                 do_wakeup = 0;
 1096                 error = 0;      /* error return if necessary */
 1097 
 1098                 for (i = 0; i < nsops; i++) {
 1099                         sopptr = &sops[i];
 1100                         semptr = &semakptr->u.sem_base[sopptr->sem_num];
 1101 
 1102                         DPRINTF((
 1103                             "semop:  semakptr=%p, sem_base=%p, "
 1104                             "semptr=%p, sem[%d]=%d : op=%d, flag=%s\n",
 1105                             semakptr, semakptr->u.sem_base, semptr,
 1106                             sopptr->sem_num, semptr->semval, sopptr->sem_op,
 1107                             (sopptr->sem_flg & IPC_NOWAIT) ?
 1108                             "nowait" : "wait"));
 1109 
 1110                         if (sopptr->sem_op < 0) {
 1111                                 if (semptr->semval + sopptr->sem_op < 0) {
 1112                                         DPRINTF(("semop:  can't do it now\n"));
 1113                                         break;
 1114                                 } else {
 1115                                         semptr->semval += sopptr->sem_op;
 1116                                         if (semptr->semval == 0 &&
 1117                                             semptr->semzcnt > 0)
 1118                                                 do_wakeup = 1;
 1119                                 }
 1120                         } else if (sopptr->sem_op == 0) {
 1121                                 if (semptr->semval != 0) {
 1122                                         DPRINTF(("semop:  not zero now\n"));
 1123                                         break;
 1124                                 }
 1125                         } else if (semptr->semval + sopptr->sem_op >
 1126                             seminfo.semvmx) {
 1127                                 error = ERANGE;
 1128                                 break;
 1129                         } else {
 1130                                 if (semptr->semncnt > 0)
 1131                                         do_wakeup = 1;
 1132                                 semptr->semval += sopptr->sem_op;
 1133                         }
 1134                 }
 1135 
 1136                 /*
 1137                  * Did we get through the entire vector?
 1138                  */
 1139                 if (i >= nsops)
 1140                         goto done;
 1141 
 1142                 /*
 1143                  * No ... rollback anything that we've already done
 1144                  */
 1145                 DPRINTF(("semop:  rollback 0 through %d\n", i-1));
 1146                 for (j = 0; j < i; j++)
 1147                         semakptr->u.sem_base[sops[j].sem_num].semval -=
 1148                             sops[j].sem_op;
 1149 
 1150                 /* If we detected an error, return it */
 1151                 if (error != 0)
 1152                         goto done2;
 1153 
 1154                 /*
 1155                  * If the request that we couldn't satisfy has the
 1156                  * NOWAIT flag set then return with EAGAIN.
 1157                  */
 1158                 if (sopptr->sem_flg & IPC_NOWAIT) {
 1159                         error = EAGAIN;
 1160                         goto done2;
 1161                 }
 1162 
 1163                 if (sopptr->sem_op == 0)
 1164                         semptr->semzcnt++;
 1165                 else
 1166                         semptr->semncnt++;
 1167 
 1168                 DPRINTF(("semop:  good night!\n"));
 1169                 error = msleep(semakptr, sema_mtxp, (PZERO - 4) | PCATCH,
 1170                     "semwait", 0);
 1171                 DPRINTF(("semop:  good morning (error=%d)!\n", error));
 1172                 /* return code is checked below, after sem[nz]cnt-- */
 1173 
 1174                 /*
 1175                  * Make sure that the semaphore still exists
 1176                  */
 1177                 seq = semakptr->u.sem_perm.seq;
 1178                 if ((semakptr->u.sem_perm.mode & SEM_ALLOC) == 0 ||
 1179                     seq != IPCID_TO_SEQ(uap->semid)) {
 1180                         error = EIDRM;
 1181                         goto done2;
 1182                 }
 1183 
 1184                 /*
 1185                  * Renew the semaphore's pointer after wakeup since
 1186                  * during msleep sem_base may have been modified and semptr
 1187                  * is not valid any more
 1188                  */
 1189                 semptr = &semakptr->u.sem_base[sopptr->sem_num];
 1190 
 1191                 /*
 1192                  * The semaphore is still alive.  Readjust the count of
 1193                  * waiting processes.
 1194                  */
 1195                 if (sopptr->sem_op == 0)
 1196                         semptr->semzcnt--;
 1197                 else
 1198                         semptr->semncnt--;
 1199 
 1200                 /*
 1201                  * Is it really morning, or was our sleep interrupted?
 1202                  * (Delayed check of msleep() return code because we
 1203                  * need to decrement sem[nz]cnt either way.)
 1204                  */
 1205                 if (error != 0) {
 1206                         error = EINTR;
 1207                         goto done2;
 1208                 }
 1209                 DPRINTF(("semop:  good morning!\n"));
 1210         }
 1211 
 1212 done:
 1213         /*
 1214          * Process any SEM_UNDO requests.
 1215          */
 1216         if (do_undos) {
 1217                 SEMUNDO_LOCK();
 1218                 suptr = NULL;
 1219                 for (i = 0; i < nsops; i++) {
 1220                         /*
 1221                          * We only need to deal with SEM_UNDO's for non-zero
 1222                          * op's.
 1223                          */
 1224                         int adjval;
 1225 
 1226                         if ((sops[i].sem_flg & SEM_UNDO) == 0)
 1227                                 continue;
 1228                         adjval = sops[i].sem_op;
 1229                         if (adjval == 0)
 1230                                 continue;
 1231                         error = semundo_adjust(td, &suptr, semid, seq,
 1232                             sops[i].sem_num, -adjval);
 1233                         if (error == 0)
 1234                                 continue;
 1235 
 1236                         /*
 1237                          * Oh-Oh!  We ran out of either sem_undo's or undo's.
 1238                          * Rollback the adjustments to this point and then
 1239                          * rollback the semaphore ups and down so we can return
 1240                          * with an error with all structures restored.  We
 1241                          * rollback the undo's in the exact reverse order that
 1242                          * we applied them.  This guarantees that we won't run
 1243                          * out of space as we roll things back out.
 1244                          */
 1245                         for (j = 0; j < i; j++) {
 1246                                 k = i - j - 1;
 1247                                 if ((sops[k].sem_flg & SEM_UNDO) == 0)
 1248                                         continue;
 1249                                 adjval = sops[k].sem_op;
 1250                                 if (adjval == 0)
 1251                                         continue;
 1252                                 if (semundo_adjust(td, &suptr, semid, seq,
 1253                                     sops[k].sem_num, adjval) != 0)
 1254                                         panic("semop - can't undo undos");
 1255                         }
 1256 
 1257                         for (j = 0; j < nsops; j++)
 1258                                 semakptr->u.sem_base[sops[j].sem_num].semval -=
 1259                                     sops[j].sem_op;
 1260 
 1261                         DPRINTF(("error = %d from semundo_adjust\n", error));
 1262                         SEMUNDO_UNLOCK();
 1263                         goto done2;
 1264                 } /* loop through the sops */
 1265                 SEMUNDO_UNLOCK();
 1266         } /* if (do_undos) */
 1267 
 1268         /* We're definitely done - set the sempid's and time */
 1269         for (i = 0; i < nsops; i++) {
 1270                 sopptr = &sops[i];
 1271                 semptr = &semakptr->u.sem_base[sopptr->sem_num];
 1272                 semptr->sempid = td->td_proc->p_pid;
 1273         }
 1274         semakptr->u.sem_otime = time_second;
 1275 
 1276         /*
 1277          * Do a wakeup if any semaphore was up'd whilst something was
 1278          * sleeping on it.
 1279          */
 1280         if (do_wakeup) {
 1281                 DPRINTF(("semop:  doing wakeup\n"));
 1282                 wakeup(semakptr);
 1283                 DPRINTF(("semop:  back from wakeup\n"));
 1284         }
 1285         DPRINTF(("semop:  done\n"));
 1286         td->td_retval[0] = 0;
 1287 done2:
 1288         mtx_unlock(sema_mtxp);
 1289         if (sops != small_sops)
 1290                 free(sops, M_SEM);
 1291         return (error);
 1292 }
 1293 
 1294 /*
 1295  * Go through the undo structures for this process and apply the adjustments to
 1296  * semaphores.
 1297  */
 1298 static void
 1299 semexit_myhook(void *arg, struct proc *p)
 1300 {
 1301         struct sem_undo *suptr;
 1302         struct semid_kernel *semakptr;
 1303         struct mtx *sema_mtxp;
 1304         int semid, semnum, adjval, ix;
 1305         unsigned short seq;
 1306 
 1307         /*
 1308          * Go through the chain of undo vectors looking for one
 1309          * associated with this process.
 1310          */
 1311         SEMUNDO_LOCK();
 1312         LIST_FOREACH(suptr, &semu_list, un_next) {
 1313                 if (suptr->un_proc == p)
 1314                         break;
 1315         }
 1316         if (suptr == NULL) {
 1317                 SEMUNDO_UNLOCK();
 1318                 return;
 1319         }
 1320         LIST_REMOVE(suptr, un_next);
 1321 
 1322         DPRINTF(("proc @%p has undo structure with %d entries\n", p,
 1323             suptr->un_cnt));
 1324 
 1325         /*
 1326          * If there are any active undo elements then process them.
 1327          */
 1328         if (suptr->un_cnt > 0) {
 1329                 SEMUNDO_UNLOCK();
 1330                 for (ix = 0; ix < suptr->un_cnt; ix++) {
 1331                         semid = suptr->un_ent[ix].un_id;
 1332                         semnum = suptr->un_ent[ix].un_num;
 1333                         adjval = suptr->un_ent[ix].un_adjval;
 1334                         seq = suptr->un_ent[ix].un_seq;
 1335                         semakptr = &sema[semid];
 1336                         sema_mtxp = &sema_mtx[semid];
 1337 
 1338                         mtx_lock(sema_mtxp);
 1339                         if ((semakptr->u.sem_perm.mode & SEM_ALLOC) == 0 ||
 1340                             (semakptr->u.sem_perm.seq != seq)) {
 1341                                 mtx_unlock(sema_mtxp);
 1342                                 continue;
 1343                         }
 1344                         if (semnum >= semakptr->u.sem_nsems)
 1345                                 panic("semexit - semnum out of range");
 1346 
 1347                         DPRINTF((
 1348                             "semexit:  %p id=%d num=%d(adj=%d) ; sem=%d\n",
 1349                             suptr->un_proc, suptr->un_ent[ix].un_id,
 1350                             suptr->un_ent[ix].un_num,
 1351                             suptr->un_ent[ix].un_adjval,
 1352                             semakptr->u.sem_base[semnum].semval));
 1353 
 1354                         if (adjval < 0 && semakptr->u.sem_base[semnum].semval <
 1355                             -adjval)
 1356                                 semakptr->u.sem_base[semnum].semval = 0;
 1357                         else
 1358                                 semakptr->u.sem_base[semnum].semval += adjval;
 1359 
 1360                         wakeup(semakptr);
 1361                         DPRINTF(("semexit:  back from wakeup\n"));
 1362                         mtx_unlock(sema_mtxp);
 1363                 }
 1364                 SEMUNDO_LOCK();
 1365         }
 1366 
 1367         /*
 1368          * Deallocate the undo vector.
 1369          */
 1370         DPRINTF(("removing vector\n"));
 1371         suptr->un_proc = NULL;
 1372         suptr->un_cnt = 0;
 1373         LIST_INSERT_HEAD(&semu_free_list, suptr, un_next);
 1374         SEMUNDO_UNLOCK();
 1375 }
 1376 
 1377 static int
 1378 sysctl_sema(SYSCTL_HANDLER_ARGS)
 1379 {
 1380 
 1381         return (SYSCTL_OUT(req, sema,
 1382             sizeof(struct semid_kernel) * seminfo.semmni));
 1383 }
 1384 
 1385 #if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \
 1386     defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7)
 1387 
 1388 /* XXX casting to (sy_call_t *) is bogus, as usual. */
 1389 static sy_call_t *semcalls[] = {
 1390         (sy_call_t *)freebsd7___semctl, (sy_call_t *)sys_semget,
 1391         (sy_call_t *)sys_semop
 1392 };
 1393 
 1394 /*
 1395  * Entry point for all SEM calls.
 1396  */
 1397 int
 1398 sys_semsys(td, uap)
 1399         struct thread *td;
 1400         /* XXX actually varargs. */
 1401         struct semsys_args /* {
 1402                 int     which;
 1403                 int     a2;
 1404                 int     a3;
 1405                 int     a4;
 1406                 int     a5;
 1407         } */ *uap;
 1408 {
 1409         int error;
 1410 
 1411         if (!prison_allow(td->td_ucred, PR_ALLOW_SYSVIPC))
 1412                 return (ENOSYS);
 1413         if (uap->which < 0 ||
 1414             uap->which >= sizeof(semcalls)/sizeof(semcalls[0]))
 1415                 return (EINVAL);
 1416         error = (*semcalls[uap->which])(td, &uap->a2);
 1417         return (error);
 1418 }
 1419 
 1420 #ifndef CP
 1421 #define CP(src, dst, fld)       do { (dst).fld = (src).fld; } while (0)
 1422 #endif
 1423 
 1424 #ifndef _SYS_SYSPROTO_H_
 1425 struct freebsd7___semctl_args {
 1426         int     semid;
 1427         int     semnum;
 1428         int     cmd;
 1429         union   semun_old *arg;
 1430 };
 1431 #endif
 1432 int
 1433 freebsd7___semctl(struct thread *td, struct freebsd7___semctl_args *uap)
 1434 {
 1435         struct semid_ds_old dsold;
 1436         struct semid_ds dsbuf;
 1437         union semun_old arg;
 1438         union semun semun;
 1439         register_t rval;
 1440         int error;
 1441 
 1442         switch (uap->cmd) {
 1443         case SEM_STAT:
 1444         case IPC_SET:
 1445         case IPC_STAT:
 1446         case GETALL:
 1447         case SETVAL:
 1448         case SETALL:
 1449                 error = copyin(uap->arg, &arg, sizeof(arg));
 1450                 if (error)
 1451                         return (error);
 1452                 break;
 1453         }
 1454 
 1455         switch (uap->cmd) {
 1456         case SEM_STAT:
 1457         case IPC_STAT:
 1458                 semun.buf = &dsbuf;
 1459                 break;
 1460         case IPC_SET:
 1461                 error = copyin(arg.buf, &dsold, sizeof(dsold));
 1462                 if (error)
 1463                         return (error);
 1464                 ipcperm_old2new(&dsold.sem_perm, &dsbuf.sem_perm);
 1465                 CP(dsold, dsbuf, sem_base);
 1466                 CP(dsold, dsbuf, sem_nsems);
 1467                 CP(dsold, dsbuf, sem_otime);
 1468                 CP(dsold, dsbuf, sem_ctime);
 1469                 semun.buf = &dsbuf;
 1470                 break;
 1471         case GETALL:
 1472         case SETALL:
 1473                 semun.array = arg.array;
 1474                 break;
 1475         case SETVAL:
 1476                 semun.val = arg.val;
 1477                 break;          
 1478         }
 1479 
 1480         error = kern_semctl(td, uap->semid, uap->semnum, uap->cmd, &semun,
 1481             &rval);
 1482         if (error)
 1483                 return (error);
 1484 
 1485         switch (uap->cmd) {
 1486         case SEM_STAT:
 1487         case IPC_STAT:
 1488                 bzero(&dsold, sizeof(dsold));
 1489                 ipcperm_new2old(&dsbuf.sem_perm, &dsold.sem_perm);
 1490                 CP(dsbuf, dsold, sem_base);
 1491                 CP(dsbuf, dsold, sem_nsems);
 1492                 CP(dsbuf, dsold, sem_otime);
 1493                 CP(dsbuf, dsold, sem_ctime);
 1494                 error = copyout(&dsold, arg.buf, sizeof(dsold));
 1495                 break;
 1496         }
 1497 
 1498         if (error == 0)
 1499                 td->td_retval[0] = rval;
 1500         return (error);
 1501 }
 1502 
 1503 #endif /* COMPAT_FREEBSD{4,5,6,7} */
 1504 
 1505 #ifdef COMPAT_FREEBSD32
 1506 
 1507 int
 1508 freebsd32_semsys(struct thread *td, struct freebsd32_semsys_args *uap)
 1509 {
 1510 
 1511 #if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \
 1512     defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7)
 1513         switch (uap->which) {
 1514         case 0:
 1515                 return (freebsd7_freebsd32_semctl(td,
 1516                     (struct freebsd7_freebsd32_semctl_args *)&uap->a2));
 1517         default:
 1518                 return (sys_semsys(td, (struct semsys_args *)uap));
 1519         }
 1520 #else
 1521         return (nosys(td, NULL));
 1522 #endif
 1523 }
 1524 
 1525 #if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \
 1526     defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7)
 1527 int
 1528 freebsd7_freebsd32_semctl(struct thread *td,
 1529     struct freebsd7_freebsd32_semctl_args *uap)
 1530 {
 1531         struct semid_ds32_old dsbuf32;
 1532         struct semid_ds dsbuf;
 1533         union semun semun;
 1534         union semun32 arg;
 1535         register_t rval;
 1536         int error;
 1537 
 1538         switch (uap->cmd) {
 1539         case SEM_STAT:
 1540         case IPC_SET:
 1541         case IPC_STAT:
 1542         case GETALL:
 1543         case SETVAL:
 1544         case SETALL:
 1545                 error = copyin(uap->arg, &arg, sizeof(arg));
 1546                 if (error)
 1547                         return (error);         
 1548                 break;
 1549         }
 1550 
 1551         switch (uap->cmd) {
 1552         case SEM_STAT:
 1553         case IPC_STAT:
 1554                 semun.buf = &dsbuf;
 1555                 break;
 1556         case IPC_SET:
 1557                 error = copyin(PTRIN(arg.buf), &dsbuf32, sizeof(dsbuf32));
 1558                 if (error)
 1559                         return (error);
 1560                 freebsd32_ipcperm_old_in(&dsbuf32.sem_perm, &dsbuf.sem_perm);
 1561                 PTRIN_CP(dsbuf32, dsbuf, sem_base);
 1562                 CP(dsbuf32, dsbuf, sem_nsems);
 1563                 CP(dsbuf32, dsbuf, sem_otime);
 1564                 CP(dsbuf32, dsbuf, sem_ctime);
 1565                 semun.buf = &dsbuf;
 1566                 break;
 1567         case GETALL:
 1568         case SETALL:
 1569                 semun.array = PTRIN(arg.array);
 1570                 break;
 1571         case SETVAL:
 1572                 semun.val = arg.val;
 1573                 break;
 1574         }
 1575 
 1576         error = kern_semctl(td, uap->semid, uap->semnum, uap->cmd, &semun,
 1577             &rval);
 1578         if (error)
 1579                 return (error);
 1580 
 1581         switch (uap->cmd) {
 1582         case SEM_STAT:
 1583         case IPC_STAT:
 1584                 bzero(&dsbuf32, sizeof(dsbuf32));
 1585                 freebsd32_ipcperm_old_out(&dsbuf.sem_perm, &dsbuf32.sem_perm);
 1586                 PTROUT_CP(dsbuf, dsbuf32, sem_base);
 1587                 CP(dsbuf, dsbuf32, sem_nsems);
 1588                 CP(dsbuf, dsbuf32, sem_otime);
 1589                 CP(dsbuf, dsbuf32, sem_ctime);
 1590                 error = copyout(&dsbuf32, PTRIN(arg.buf), sizeof(dsbuf32));
 1591                 break;
 1592         }
 1593 
 1594         if (error == 0)
 1595                 td->td_retval[0] = rval;
 1596         return (error);
 1597 }
 1598 #endif
 1599 
 1600 int
 1601 freebsd32_semctl(struct thread *td, struct freebsd32_semctl_args *uap)
 1602 {
 1603         struct semid_ds32 dsbuf32;
 1604         struct semid_ds dsbuf;
 1605         union semun semun;
 1606         union semun32 arg;
 1607         register_t rval;
 1608         int error;
 1609 
 1610         switch (uap->cmd) {
 1611         case SEM_STAT:
 1612         case IPC_SET:
 1613         case IPC_STAT:
 1614         case GETALL:
 1615         case SETVAL:
 1616         case SETALL:
 1617                 error = copyin(uap->arg, &arg, sizeof(arg));
 1618                 if (error)
 1619                         return (error);         
 1620                 break;
 1621         }
 1622 
 1623         switch (uap->cmd) {
 1624         case SEM_STAT:
 1625         case IPC_STAT:
 1626                 semun.buf = &dsbuf;
 1627                 break;
 1628         case IPC_SET:
 1629                 error = copyin(PTRIN(arg.buf), &dsbuf32, sizeof(dsbuf32));
 1630                 if (error)
 1631                         return (error);
 1632                 freebsd32_ipcperm_in(&dsbuf32.sem_perm, &dsbuf.sem_perm);
 1633                 PTRIN_CP(dsbuf32, dsbuf, sem_base);
 1634                 CP(dsbuf32, dsbuf, sem_nsems);
 1635                 CP(dsbuf32, dsbuf, sem_otime);
 1636                 CP(dsbuf32, dsbuf, sem_ctime);
 1637                 semun.buf = &dsbuf;
 1638                 break;
 1639         case GETALL:
 1640         case SETALL:
 1641                 semun.array = PTRIN(arg.array);
 1642                 break;
 1643         case SETVAL:
 1644                 semun.val = arg.val;
 1645                 break;          
 1646         }
 1647 
 1648         error = kern_semctl(td, uap->semid, uap->semnum, uap->cmd, &semun,
 1649             &rval);
 1650         if (error)
 1651                 return (error);
 1652 
 1653         switch (uap->cmd) {
 1654         case SEM_STAT:
 1655         case IPC_STAT:
 1656                 bzero(&dsbuf32, sizeof(dsbuf32));
 1657                 freebsd32_ipcperm_out(&dsbuf.sem_perm, &dsbuf32.sem_perm);
 1658                 PTROUT_CP(dsbuf, dsbuf32, sem_base);
 1659                 CP(dsbuf, dsbuf32, sem_nsems);
 1660                 CP(dsbuf, dsbuf32, sem_otime);
 1661                 CP(dsbuf, dsbuf32, sem_ctime);
 1662                 error = copyout(&dsbuf32, PTRIN(arg.buf), sizeof(dsbuf32));
 1663                 break;
 1664         }
 1665 
 1666         if (error == 0)
 1667                 td->td_retval[0] = rval;
 1668         return (error);
 1669 }
 1670 
 1671 #endif /* COMPAT_FREEBSD32 */

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