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

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