sys/kern/sysv_shm.c

   1 /* $FreeBSD: src/sys/kern/sysv_shm.c,v 1.45.2.6 2002/10/22 20:45:03 fjoe Exp $ */
   2 /* $DragonFly: src/sys/kern/sysv_shm.c,v 1.20 2006/12/23 23:47:54 swildner Exp $ */
   3 /*      $NetBSD: sysv_shm.c,v 1.23 1994/07/04 23:25:12 glass Exp $      */
   4
   5 /*
   6  * Copyright (c) 1994 Adam Glass and Charles Hannum.  All rights reserved.
   7  *
   8  * Redistribution and use in source and binary forms, with or without
   9  * modification, are permitted provided that the following conditions
  10  * are met:
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  * 3. All advertising materials mentioning features or use of this software
  17  *    must display the following acknowledgement:
  18  *      This product includes software developed by Adam Glass and Charles
  19  *      Hannum.
  20  * 4. The names of the authors may not be used to endorse or promote products
  21  *    derived from this software without specific prior written permission.
  22  *
  23  * THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS OR
  24  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  25  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  26  * IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY DIRECT, INDIRECT,
  27  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  28  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  29  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  30  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  31  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  32  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  33  */
  34
  35 #include "opt_compat.h"
  36 #include "opt_sysvipc.h"
  37
  38 #include <sys/param.h>
  39 #include <sys/systm.h>
  40 #include <sys/sysproto.h>
  41 #include <sys/kernel.h>
  42 #include <sys/sysctl.h>
  43 #include <sys/shm.h>
  44 #include <sys/proc.h>
  45 #include <sys/malloc.h>
  46 #include <sys/mman.h>
  47 #include <sys/stat.h>
  48 #include <sys/sysent.h>
  49 #include <sys/jail.h>
  50
  51 #include <vm/vm.h>
  52 #include <vm/vm_param.h>
  53 #include <sys/lock.h>
  54 #include <vm/pmap.h>
  55 #include <vm/vm_object.h>
  56 #include <vm/vm_map.h>
  57 #include <vm/vm_page.h>
  58 #include <vm/vm_pager.h>
  59
  60 static MALLOC_DEFINE(M_SHM, "shm", "SVID compatible shared memory segments");
  61
  62 struct oshmctl_args;
  63 static int sys_oshmctl (struct proc *p, struct oshmctl_args *uap);
  64
  65 static int shmget_allocate_segment (struct proc *p, struct shmget_args *uap, int mode);
  66 static int shmget_existing (struct proc *p, struct shmget_args *uap, int mode, int segnum);
  67
  68 /* XXX casting to (sy_call_t *) is bogus, as usual. */
  69 static sy_call_t *shmcalls[] = {
  70         (sy_call_t *)sys_shmat, (sy_call_t *)sys_oshmctl,
  71         (sy_call_t *)sys_shmdt, (sy_call_t *)sys_shmget,
  72         (sy_call_t *)sys_shmctl
  73 };
  74
  75 #define SHMSEG_FREE             0x0200
  76 #define SHMSEG_REMOVED          0x0400
  77 #define SHMSEG_ALLOCATED        0x0800
  78 #define SHMSEG_WANTED           0x1000
  79
  80 static int shm_last_free, shm_nused, shm_committed, shmalloced;
  81 static struct shmid_ds  *shmsegs;
  82
  83 struct shm_handle {
  84         /* vm_offset_t kva; */
  85         vm_object_t shm_object;
  86 };
  87
  88 struct shmmap_state {
  89         vm_offset_t va;
  90         int shmid;
  91 };
  92
  93 static void shm_deallocate_segment (struct shmid_ds *);
  94 static int shm_find_segment_by_key (key_t);
  95 static struct shmid_ds *shm_find_segment_by_shmid (int);
  96 static int shm_delete_mapping (struct vmspace *vm, struct shmmap_state *);
  97 static void shmrealloc (void);
  98 static void shminit (void *);
  99
 100 /*
 101  * Tuneable values
 102  */
 103 #ifndef SHMMAXPGS
 104 #define SHMMAXPGS       8192    /* note: sysv shared memory is swap backed */
 105 #endif
 106 #ifndef SHMMAX
 107 #define SHMMAX  (SHMMAXPGS*PAGE_SIZE)
 108 #endif
 109 #ifndef SHMMIN
 110 #define SHMMIN  1
 111 #endif
 112 #ifndef SHMMNI
 113 #define SHMMNI  192
 114 #endif
 115 #ifndef SHMSEG
 116 #define SHMSEG  128
 117 #endif
 118 #ifndef SHMALL
 119 #define SHMALL  (SHMMAXPGS)
 120 #endif
 121
 122 struct  shminfo shminfo = {
 123         SHMMAX,
 124         SHMMIN,
 125         SHMMNI,
 126         SHMSEG,
 127         SHMALL
 128 };
 129
 130 static int shm_use_phys;
 131
 132 TUNABLE_INT("kern.ipc.shmmin", &shminfo.shmmin);
 133 TUNABLE_INT("kern.ipc.shmmni", &shminfo.shmmni);
 134 TUNABLE_INT("kern.ipc.shmseg", &shminfo.shmseg);
 135 TUNABLE_INT("kern.ipc.shmmaxpgs", &shminfo.shmall);
 136 TUNABLE_INT("kern.ipc.shm_use_phys", &shm_use_phys);
 137
 138 SYSCTL_INT(_kern_ipc, OID_AUTO, shmmax, CTLFLAG_RW, &shminfo.shmmax, 0, "");
 139 SYSCTL_INT(_kern_ipc, OID_AUTO, shmmin, CTLFLAG_RW, &shminfo.shmmin, 0, "");
 140 SYSCTL_INT(_kern_ipc, OID_AUTO, shmmni, CTLFLAG_RD, &shminfo.shmmni, 0, "");
 141 SYSCTL_INT(_kern_ipc, OID_AUTO, shmseg, CTLFLAG_RW, &shminfo.shmseg, 0, "");
 142 SYSCTL_INT(_kern_ipc, OID_AUTO, shmall, CTLFLAG_RW, &shminfo.shmall, 0, "");
 143 SYSCTL_INT(_kern_ipc, OID_AUTO, shm_use_phys, CTLFLAG_RW, &shm_use_phys, 0, "");
 144
 145 static int
 146 shm_find_segment_by_key(key_t key)
 147 {
 148         int i;
 149
 150         for (i = 0; i < shmalloced; i++)
 151                 if ((shmsegs[i].shm_perm.mode & SHMSEG_ALLOCATED) &&
 152                     shmsegs[i].shm_perm.key == key)
 153                         return i;
 154         return -1;
 155 }
 156
 157 static struct shmid_ds *
 158 shm_find_segment_by_shmid(int shmid)
 159 {
 160         int segnum;
 161         struct shmid_ds *shmseg;
 162
 163         segnum = IPCID_TO_IX(shmid);
 164         if (segnum < 0 || segnum >= shmalloced)
 165                 return NULL;
 166         shmseg = &shmsegs[segnum];
 167         if ((shmseg->shm_perm.mode & (SHMSEG_ALLOCATED | SHMSEG_REMOVED))
 168             != SHMSEG_ALLOCATED ||
 169             shmseg->shm_perm.seq != IPCID_TO_SEQ(shmid))
 170                 return NULL;
 171         return shmseg;
 172 }
 173
 174 static void
 175 shm_deallocate_segment(struct shmid_ds *shmseg)
 176 {
 177         struct shm_handle *shm_handle;
 178         size_t size;
 179
 180         shm_handle = shmseg->shm_internal;
 181         vm_object_deallocate(shm_handle->shm_object);
 182         kfree((caddr_t)shm_handle, M_SHM);
 183         shmseg->shm_internal = NULL;
 184         size = round_page(shmseg->shm_segsz);
 185         shm_committed -= btoc(size);
 186         shm_nused--;
 187         shmseg->shm_perm.mode = SHMSEG_FREE;
 188 }
 189
 190 static int
 191 shm_delete_mapping(struct vmspace *vm, struct shmmap_state *shmmap_s)
 192 {
 193         struct shmid_ds *shmseg;
 194         int segnum, result;
 195         size_t size;
 196
 197         segnum = IPCID_TO_IX(shmmap_s->shmid);
 198         shmseg = &shmsegs[segnum];
 199         size = round_page(shmseg->shm_segsz);
 200         result = vm_map_remove(&vm->vm_map, shmmap_s->va, shmmap_s->va + size);
 201         if (result != KERN_SUCCESS)
 202                 return EINVAL;
 203         shmmap_s->shmid = -1;
 204         shmseg->shm_dtime = time_second;
 205         if ((--shmseg->shm_nattch <= 0) &&
 206             (shmseg->shm_perm.mode & SHMSEG_REMOVED)) {
 207                 shm_deallocate_segment(shmseg);
 208                 shm_last_free = segnum;
 209         }
 210         return 0;
 211 }
 212
 213 int
 214 sys_shmdt(struct shmdt_args *uap)
 215 {
 216         struct proc *p = curproc;
 217         struct shmmap_state *shmmap_s;
 218         int i;
 219
 220         if (!jail_sysvipc_allowed && p->p_ucred->cr_prison != NULL)
 221                 return (ENOSYS);
 222
 223         shmmap_s = (struct shmmap_state *)p->p_vmspace->vm_shm;
 224         if (shmmap_s == NULL)
 225             return EINVAL;
 226         for (i = 0; i < shminfo.shmseg; i++, shmmap_s++)
 227                 if (shmmap_s->shmid != -1 &&
 228                     shmmap_s->va == (vm_offset_t)uap->shmaddr)
 229                         break;
 230         if (i == shminfo.shmseg)
 231                 return EINVAL;
 232         return shm_delete_mapping(p->p_vmspace, shmmap_s);
 233 }
 234
 235 int
 236 sys_shmat(struct shmat_args *uap)
 237 {
 238         struct proc *p = curproc;
 239         int error, i, flags;
 240         struct shmid_ds *shmseg;
 241         struct shmmap_state *shmmap_s = NULL;
 242         struct shm_handle *shm_handle;
 243         vm_offset_t attach_va;
 244         vm_prot_t prot;
 245         vm_size_t size;
 246         int rv;
 247
 248         if (!jail_sysvipc_allowed && p->p_ucred->cr_prison != NULL)
 249                 return (ENOSYS);
 250
 251         shmmap_s = (struct shmmap_state *)p->p_vmspace->vm_shm;
 252         if (shmmap_s == NULL) {
 253                 size = shminfo.shmseg * sizeof(struct shmmap_state);
 254                 shmmap_s = kmalloc(size, M_SHM, M_WAITOK);
 255                 for (i = 0; i < shminfo.shmseg; i++)
 256                         shmmap_s[i].shmid = -1;
 257                 p->p_vmspace->vm_shm = (caddr_t)shmmap_s;
 258         }
 259         shmseg = shm_find_segment_by_shmid(uap->shmid);
 260         if (shmseg == NULL)
 261                 return EINVAL;
 262         error = ipcperm(p, &shmseg->shm_perm,
 263             (uap->shmflg & SHM_RDONLY) ? IPC_R : IPC_R|IPC_W);
 264         if (error)
 265                 return error;
 266         for (i = 0; i < shminfo.shmseg; i++) {
 267                 if (shmmap_s->shmid == -1)
 268                         break;
 269                 shmmap_s++;
 270         }
 271         if (i >= shminfo.shmseg)
 272                 return EMFILE;
 273         size = round_page(shmseg->shm_segsz);
 274 #ifdef VM_PROT_READ_IS_EXEC
 275         prot = VM_PROT_READ | VM_PROT_EXECUTE;
 276 #else
 277         prot = VM_PROT_READ;
 278 #endif
 279         if ((uap->shmflg & SHM_RDONLY) == 0)
 280                 prot |= VM_PROT_WRITE;
 281         flags = MAP_ANON | MAP_SHARED;
 282         if (uap->shmaddr) {
 283                 flags |= MAP_FIXED;
 284                 if (uap->shmflg & SHM_RND)
 285                         attach_va = (vm_offset_t)uap->shmaddr & ~(SHMLBA-1);
 286                 else if (((vm_offset_t)uap->shmaddr & (SHMLBA-1)) == 0)
 287                         attach_va = (vm_offset_t)uap->shmaddr;
 288                 else
 289                         return EINVAL;
 290         } else {
 291                 /* This is just a hint to vm_map_find() about where to put it. */
 292                 attach_va = round_page((vm_offset_t)p->p_vmspace->vm_taddr + maxtsiz + maxdsiz);
 293         }
 294
 295         shm_handle = shmseg->shm_internal;
 296         vm_object_reference(shm_handle->shm_object);
 297         rv = vm_map_find(&p->p_vmspace->vm_map,
 298                          shm_handle->shm_object, 0,
 299                          &attach_va, size,
 300                          ((flags & MAP_FIXED) ? 0 : 1),
 301                          VM_MAPTYPE_NORMAL,
 302                          prot, prot,
 303                          0);
 304         if (rv != KERN_SUCCESS) {
 305                 vm_object_deallocate(shm_handle->shm_object);
 306                 return ENOMEM;
 307         }
 308         vm_map_inherit(&p->p_vmspace->vm_map,
 309                 attach_va, attach_va + size, VM_INHERIT_SHARE);
 310
 311         shmmap_s->va = attach_va;
 312         shmmap_s->shmid = uap->shmid;
 313         shmseg->shm_lpid = p->p_pid;
 314         shmseg->shm_atime = time_second;
 315         shmseg->shm_nattch++;
 316         uap->sysmsg_result = attach_va;
 317         return 0;
 318 }
 319
 320 struct oshmid_ds {
 321         struct  ipc_perm shm_perm;      /* operation perms */
 322         int     shm_segsz;              /* size of segment (bytes) */
 323         ushort  shm_cpid;               /* pid, creator */
 324         ushort  shm_lpid;               /* pid, last operation */
 325         short   shm_nattch;             /* no. of current attaches */
 326         time_t  shm_atime;              /* last attach time */
 327         time_t  shm_dtime;              /* last detach time */
 328         time_t  shm_ctime;              /* last change time */
 329         void    *shm_handle;            /* internal handle for shm segment */
 330 };
 331
 332 struct oshmctl_args {
 333         struct sysmsg sysmsg;
 334         int shmid;
 335         int cmd;
 336         struct oshmid_ds *ubuf;
 337 };
 338
 339 static int
 340 sys_oshmctl(struct proc *p, struct oshmctl_args *uap)
 341 {
 342 #ifdef COMPAT_43
 343         int error;
 344         struct shmid_ds *shmseg;
 345         struct oshmid_ds outbuf;
 346
 347         if (!jail_sysvipc_allowed && p->p_ucred->cr_prison != NULL)
 348                 return (ENOSYS);
 349
 350         shmseg = shm_find_segment_by_shmid(uap->shmid);
 351         if (shmseg == NULL)
 352                 return EINVAL;
 353         switch (uap->cmd) {
 354         case IPC_STAT:
 355                 error = ipcperm(p, &shmseg->shm_perm, IPC_R);
 356                 if (error)
 357                         return error;
 358                 outbuf.shm_perm = shmseg->shm_perm;
 359                 outbuf.shm_segsz = shmseg->shm_segsz;
 360                 outbuf.shm_cpid = shmseg->shm_cpid;
 361                 outbuf.shm_lpid = shmseg->shm_lpid;
 362                 outbuf.shm_nattch = shmseg->shm_nattch;
 363                 outbuf.shm_atime = shmseg->shm_atime;
 364                 outbuf.shm_dtime = shmseg->shm_dtime;
 365                 outbuf.shm_ctime = shmseg->shm_ctime;
 366                 outbuf.shm_handle = shmseg->shm_internal;
 367                 error = copyout((caddr_t)&outbuf, uap->ubuf, sizeof(outbuf));
 368                 if (error)
 369                         return error;
 370                 break;
 371         default:
 372                 /* XXX casting to (sy_call_t *) is bogus, as usual. */
 373                 return (sys_shmctl((struct shmctl_args *)uap));
 374         }
 375         return 0;
 376 #else
 377         return EINVAL;
 378 #endif
 379 }
 380
 381 int
 382 sys_shmctl(struct shmctl_args *uap)
 383 {
 384         struct proc *p = curproc;
 385         int error;
 386         struct shmid_ds inbuf;
 387         struct shmid_ds *shmseg;
 388
 389         if (!jail_sysvipc_allowed && p->p_ucred->cr_prison != NULL)
 390                 return (ENOSYS);
 391
 392         shmseg = shm_find_segment_by_shmid(uap->shmid);
 393         if (shmseg == NULL)
 394                 return EINVAL;
 395         switch (uap->cmd) {
 396         case IPC_STAT:
 397                 error = ipcperm(p, &shmseg->shm_perm, IPC_R);
 398                 if (error)
 399                         return error;
 400                 error = copyout((caddr_t)shmseg, uap->buf, sizeof(inbuf));
 401                 if (error)
 402                         return error;
 403                 break;
 404         case IPC_SET:
 405                 error = ipcperm(p, &shmseg->shm_perm, IPC_M);
 406                 if (error)
 407                         return error;
 408                 error = copyin(uap->buf, (caddr_t)&inbuf, sizeof(inbuf));
 409                 if (error)
 410                         return error;
 411                 shmseg->shm_perm.uid = inbuf.shm_perm.uid;
 412                 shmseg->shm_perm.gid = inbuf.shm_perm.gid;
 413                 shmseg->shm_perm.mode =
 414                     (shmseg->shm_perm.mode & ~ACCESSPERMS) |
 415                     (inbuf.shm_perm.mode & ACCESSPERMS);
 416                 shmseg->shm_ctime = time_second;
 417                 break;
 418         case IPC_RMID:
 419                 error = ipcperm(p, &shmseg->shm_perm, IPC_M);
 420                 if (error)
 421                         return error;
 422                 shmseg->shm_perm.key = IPC_PRIVATE;
 423                 shmseg->shm_perm.mode |= SHMSEG_REMOVED;
 424                 if (shmseg->shm_nattch <= 0) {
 425                         shm_deallocate_segment(shmseg);
 426                         shm_last_free = IPCID_TO_IX(uap->shmid);
 427                 }
 428                 break;
 429 #if 0
 430         case SHM_LOCK:
 431         case SHM_UNLOCK:
 432 #endif
 433         default:
 434                 return EINVAL;
 435         }
 436         return 0;
 437 }
 438
 439 static int
 440 shmget_existing(struct proc *p, struct shmget_args *uap, int mode, int segnum)
 441 {
 442         struct shmid_ds *shmseg;
 443         int error;
 444
 445         shmseg = &shmsegs[segnum];
 446         if (shmseg->shm_perm.mode & SHMSEG_REMOVED) {
 447                 /*
 448                  * This segment is in the process of being allocated.  Wait
 449                  * until it's done, and look the key up again (in case the
 450                  * allocation failed or it was freed).
 451                  */
 452                 shmseg->shm_perm.mode |= SHMSEG_WANTED;
 453                 error = tsleep((caddr_t)shmseg, PCATCH, "shmget", 0);
 454                 if (error)
 455                         return error;
 456                 return EAGAIN;
 457         }
 458         if ((uap->shmflg & (IPC_CREAT | IPC_EXCL)) == (IPC_CREAT | IPC_EXCL))
 459                 return EEXIST;
 460         error = ipcperm(p, &shmseg->shm_perm, mode);
 461         if (error)
 462                 return error;
 463         if (uap->size && uap->size > shmseg->shm_segsz)
 464                 return EINVAL;
 465         uap->sysmsg_result = IXSEQ_TO_IPCID(segnum, shmseg->shm_perm);
 466         return 0;
 467 }
 468
 469 static int
 470 shmget_allocate_segment(struct proc *p, struct shmget_args *uap, int mode)
 471 {
 472         int i, segnum, shmid, size;
 473         struct ucred *cred = p->p_ucred;
 474         struct shmid_ds *shmseg;
 475         struct shm_handle *shm_handle;
 476
 477         if (uap->size < shminfo.shmmin || uap->size > shminfo.shmmax)
 478                 return EINVAL;
 479         if (shm_nused >= shminfo.shmmni) /* any shmids left? */
 480                 return ENOSPC;
 481         size = round_page(uap->size);
 482         if (shm_committed + btoc(size) > shminfo.shmall)
 483                 return ENOMEM;
 484         if (shm_last_free < 0) {
 485                 shmrealloc();   /* maybe expand the shmsegs[] array */
 486                 for (i = 0; i < shmalloced; i++)
 487                         if (shmsegs[i].shm_perm.mode & SHMSEG_FREE)
 488                                 break;
 489                 if (i == shmalloced)
 490                         return ENOSPC;
 491                 segnum = i;
 492         } else  {
 493                 segnum = shm_last_free;
 494                 shm_last_free = -1;
 495         }
 496         shmseg = &shmsegs[segnum];
 497         /*
 498          * In case we sleep in malloc(), mark the segment present but deleted
 499          * so that noone else tries to create the same key.
 500          */
 501         shmseg->shm_perm.mode = SHMSEG_ALLOCATED | SHMSEG_REMOVED;
 502         shmseg->shm_perm.key = uap->key;
 503         shmseg->shm_perm.seq = (shmseg->shm_perm.seq + 1) & 0x7fff;
 504         shm_handle = kmalloc(sizeof(struct shm_handle), M_SHM, M_WAITOK);
 505         shmid = IXSEQ_TO_IPCID(segnum, shmseg->shm_perm);
 506
 507         /*
 508          * We make sure that we have allocated a pager before we need
 509          * to.
 510          */
 511         if (shm_use_phys) {
 512                 shm_handle->shm_object =
 513                     vm_pager_allocate(OBJT_PHYS, 0, size, VM_PROT_DEFAULT, 0);
 514         } else {
 515                 shm_handle->shm_object =
 516                     vm_pager_allocate(OBJT_SWAP, 0, size, VM_PROT_DEFAULT, 0);
 517         }
 518         vm_object_clear_flag(shm_handle->shm_object, OBJ_ONEMAPPING);
 519         vm_object_set_flag(shm_handle->shm_object, OBJ_NOSPLIT);
 520
 521         shmseg->shm_internal = shm_handle;
 522         shmseg->shm_perm.cuid = shmseg->shm_perm.uid = cred->cr_uid;
 523         shmseg->shm_perm.cgid = shmseg->shm_perm.gid = cred->cr_gid;
 524         shmseg->shm_perm.mode = (shmseg->shm_perm.mode & SHMSEG_WANTED) |
 525             (mode & ACCESSPERMS) | SHMSEG_ALLOCATED;
 526         shmseg->shm_segsz = uap->size;
 527         shmseg->shm_cpid = p->p_pid;
 528         shmseg->shm_lpid = shmseg->shm_nattch = 0;
 529         shmseg->shm_atime = shmseg->shm_dtime = 0;
 530         shmseg->shm_ctime = time_second;
 531         shm_committed += btoc(size);
 532         shm_nused++;
 533         if (shmseg->shm_perm.mode & SHMSEG_WANTED) {
 534                 /*
 535                  * Somebody else wanted this key while we were asleep.  Wake
 536                  * them up now.
 537                  */
 538                 shmseg->shm_perm.mode &= ~SHMSEG_WANTED;
 539                 wakeup((caddr_t)shmseg);
 540         }
 541         uap->sysmsg_result = shmid;
 542         return 0;
 543 }
 544
 545 int
 546 sys_shmget(struct shmget_args *uap)
 547 {
 548         struct proc *p = curproc;
 549         int segnum, mode, error;
 550
 551         if (!jail_sysvipc_allowed && p->p_ucred->cr_prison != NULL)
 552                 return (ENOSYS);
 553
 554         mode = uap->shmflg & ACCESSPERMS;
 555         if (uap->key != IPC_PRIVATE) {
 556         again:
 557                 segnum = shm_find_segment_by_key(uap->key);
 558                 if (segnum >= 0) {
 559                         error = shmget_existing(p, uap, mode, segnum);
 560                         if (error == EAGAIN)
 561                                 goto again;
 562                         return error;
 563                 }
 564                 if ((uap->shmflg & IPC_CREAT) == 0)
 565                         return ENOENT;
 566         }
 567         return shmget_allocate_segment(p, uap, mode);
 568 }
 569
 570 /*
 571  *  shmsys_args(int which, int a2, ...) (VARARGS)
 572  */
 573 int
 574 sys_shmsys(struct shmsys_args *uap)
 575 {
 576         struct proc *p = curproc;
 577         unsigned int which = (unsigned int)uap->which;
 578         int error;
 579
 580         if (!jail_sysvipc_allowed && p->p_ucred->cr_prison != NULL)
 581                 return (ENOSYS);
 582
 583         if (which >= sizeof(shmcalls)/sizeof(shmcalls[0]))
 584                 return EINVAL;
 585         bcopy(&uap->a2, &uap->which,
 586                 sizeof(struct shmsys_args) - offsetof(struct shmsys_args, a2));
 587         error = ((*shmcalls[which])(uap));
 588         return(error);
 589 }
 590
 591 void
 592 shmfork(struct proc *p1, struct proc *p2)
 593 {
 594         struct shmmap_state *shmmap_s;
 595         size_t size;
 596         int i;
 597
 598         size = shminfo.shmseg * sizeof(struct shmmap_state);
 599         shmmap_s = kmalloc(size, M_SHM, M_WAITOK);
 600         bcopy((caddr_t)p1->p_vmspace->vm_shm, (caddr_t)shmmap_s, size);
 601         p2->p_vmspace->vm_shm = (caddr_t)shmmap_s;
 602         for (i = 0; i < shminfo.shmseg; i++, shmmap_s++)
 603                 if (shmmap_s->shmid != -1)
 604                         shmsegs[IPCID_TO_IX(shmmap_s->shmid)].shm_nattch++;
 605 }
 606
 607 void
 608 shmexit(struct vmspace *vm)
 609 {
 610         struct shmmap_state *base, *shm;
 611         int i;
 612
 613         if ((base = (struct shmmap_state *)vm->vm_shm) != NULL) {
 614                 vm->vm_shm = NULL;
 615                 for (i = 0, shm = base; i < shminfo.shmseg; i++, shm++) {
 616                         if (shm->shmid != -1)
 617                                 shm_delete_mapping(vm, shm);
 618                 }
 619                 kfree(base, M_SHM);
 620         }
 621 }
 622
 623 static void
 624 shmrealloc(void)
 625 {
 626         int i;
 627         struct shmid_ds *newsegs;
 628
 629         if (shmalloced >= shminfo.shmmni)
 630                 return;
 631
 632         newsegs = kmalloc(shminfo.shmmni * sizeof(*newsegs), M_SHM, M_WAITOK);
 633         if (newsegs == NULL)
 634                 return;
 635         for (i = 0; i < shmalloced; i++)
 636                 bcopy(&shmsegs[i], &newsegs[i], sizeof(newsegs[0]));
 637         for (; i < shminfo.shmmni; i++) {
 638                 shmsegs[i].shm_perm.mode = SHMSEG_FREE;
 639                 shmsegs[i].shm_perm.seq = 0;
 640         }
 641         kfree(shmsegs, M_SHM);
 642         shmsegs = newsegs;
 643         shmalloced = shminfo.shmmni;
 644 }
 645
 646 static void
 647 shminit(void *dummy)
 648 {
 649         int i;
 650
 651         shminfo.shmmax = shminfo.shmall * PAGE_SIZE;
 652         shmalloced = shminfo.shmmni;
 653         shmsegs = kmalloc(shmalloced * sizeof(shmsegs[0]), M_SHM, M_WAITOK);
 654         if (shmsegs == NULL)
 655                 panic("cannot allocate initial memory for sysvshm");
 656         for (i = 0; i < shmalloced; i++) {
 657                 shmsegs[i].shm_perm.mode = SHMSEG_FREE;
 658                 shmsegs[i].shm_perm.seq = 0;
 659         }
 660         shm_last_free = 0;
 661         shm_nused = 0;
 662         shm_committed = 0;
 663 }
 664 SYSINIT(sysv_shm, SI_SUB_SYSV_SHM, SI_ORDER_FIRST, shminit, NULL);