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 1.21 2008/01/06 16:55:51 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 <sys/mplock2.h>
  52
  53 #include <vm/vm.h>
  54 #include <vm/vm_param.h>
  55 #include <sys/lock.h>
  56 #include <vm/pmap.h>
  57 #include <vm/vm_object.h>
  58 #include <vm/vm_map.h>
  59 #include <vm/vm_page.h>
  60 #include <vm/vm_pager.h>
  61
  62 static MALLOC_DEFINE(M_SHM, "shm", "SVID compatible shared memory segments");
  63
  64 struct oshmctl_args;
  65 static int sys_oshmctl (struct proc *p, struct oshmctl_args *uap);
  66
  67 static int shmget_allocate_segment (struct proc *p, struct shmget_args *uap, int mode);
  68 static int shmget_existing (struct proc *p, struct shmget_args *uap, int mode, int segnum);
  69
  70 /* XXX casting to (sy_call_t *) is bogus, as usual. */
  71 static sy_call_t *shmcalls[] = {
  72         (sy_call_t *)sys_shmat, (sy_call_t *)sys_oshmctl,
  73         (sy_call_t *)sys_shmdt, (sy_call_t *)sys_shmget,
  74         (sy_call_t *)sys_shmctl
  75 };
  76
  77 #define SHMSEG_FREE             0x0200
  78 #define SHMSEG_REMOVED          0x0400
  79 #define SHMSEG_ALLOCATED        0x0800
  80 #define SHMSEG_WANTED           0x1000
  81
  82 static int shm_last_free, shm_nused, shm_committed, shmalloced;
  83 static struct shmid_ds  *shmsegs;
  84
  85 struct shm_handle {
  86         /* vm_offset_t kva; */
  87         vm_object_t shm_object;
  88 };
  89
  90 struct shmmap_state {
  91         vm_offset_t va;
  92         int shmid;
  93 };
  94
  95 static void shm_deallocate_segment (struct shmid_ds *);
  96 static int shm_find_segment_by_key (key_t);
  97 static struct shmid_ds *shm_find_segment_by_shmid (int);
  98 static int shm_delete_mapping (struct vmspace *vm, struct shmmap_state *);
  99 static void shmrealloc (void);
 100 static void shminit (void *);
 101
 102 /*
 103  * Tuneable values
 104  */
 105 #ifndef SHMMAXPGS
 106 #define SHMMAXPGS       8192    /* note: sysv shared memory is swap backed */
 107 #endif
 108 #ifndef SHMMAX
 109 #define SHMMAX  (SHMMAXPGS*PAGE_SIZE)
 110 #endif
 111 #ifndef SHMMIN
 112 #define SHMMIN  1
 113 #endif
 114 #ifndef SHMMNI
 115 #define SHMMNI  192
 116 #endif
 117 #ifndef SHMSEG
 118 #define SHMSEG  128
 119 #endif
 120 #ifndef SHMALL
 121 #define SHMALL  (SHMMAXPGS)
 122 #endif
 123
 124 struct  shminfo shminfo = {
 125         SHMMAX,
 126         SHMMIN,
 127         SHMMNI,
 128         SHMSEG,
 129         SHMALL
 130 };
 131
 132 static int shm_use_phys;
 133
 134 TUNABLE_INT("kern.ipc.shmmin", &shminfo.shmmin);
 135 TUNABLE_INT("kern.ipc.shmmni", &shminfo.shmmni);
 136 TUNABLE_INT("kern.ipc.shmseg", &shminfo.shmseg);
 137 TUNABLE_INT("kern.ipc.shmmaxpgs", &shminfo.shmall);
 138 TUNABLE_INT("kern.ipc.shm_use_phys", &shm_use_phys);
 139
 140 SYSCTL_INT(_kern_ipc, OID_AUTO, shmmax, CTLFLAG_RW, &shminfo.shmmax, 0, "");
 141 SYSCTL_INT(_kern_ipc, OID_AUTO, shmmin, CTLFLAG_RW, &shminfo.shmmin, 0, "");
 142 SYSCTL_INT(_kern_ipc, OID_AUTO, shmmni, CTLFLAG_RD, &shminfo.shmmni, 0, "");
 143 SYSCTL_INT(_kern_ipc, OID_AUTO, shmseg, CTLFLAG_RW, &shminfo.shmseg, 0, "");
 144 SYSCTL_INT(_kern_ipc, OID_AUTO, shmall, CTLFLAG_RW, &shminfo.shmall, 0, "");
 145 SYSCTL_INT(_kern_ipc, OID_AUTO, shm_use_phys, CTLFLAG_RW, &shm_use_phys, 0, "");
 146
 147 static int
 148 shm_find_segment_by_key(key_t key)
 149 {
 150         int i;
 151
 152         for (i = 0; i < shmalloced; i++)
 153                 if ((shmsegs[i].shm_perm.mode & SHMSEG_ALLOCATED) &&
 154                     shmsegs[i].shm_perm.key == key)
 155                         return i;
 156         return -1;
 157 }
 158
 159 static struct shmid_ds *
 160 shm_find_segment_by_shmid(int shmid)
 161 {
 162         int segnum;
 163         struct shmid_ds *shmseg;
 164
 165         segnum = IPCID_TO_IX(shmid);
 166         if (segnum < 0 || segnum >= shmalloced)
 167                 return NULL;
 168         shmseg = &shmsegs[segnum];
 169         if ((shmseg->shm_perm.mode & (SHMSEG_ALLOCATED | SHMSEG_REMOVED))
 170             != SHMSEG_ALLOCATED ||
 171             shmseg->shm_perm.seq != IPCID_TO_SEQ(shmid))
 172                 return NULL;
 173         return shmseg;
 174 }
 175
 176 static void
 177 shm_deallocate_segment(struct shmid_ds *shmseg)
 178 {
 179         struct shm_handle *shm_handle;
 180         size_t size;
 181
 182         shm_handle = shmseg->shm_internal;
 183         vm_object_deallocate(shm_handle->shm_object);
 184         kfree((caddr_t)shm_handle, M_SHM);
 185         shmseg->shm_internal = NULL;
 186         size = round_page(shmseg->shm_segsz);
 187         shm_committed -= btoc(size);
 188         shm_nused--;
 189         shmseg->shm_perm.mode = SHMSEG_FREE;
 190 }
 191
 192 static int
 193 shm_delete_mapping(struct vmspace *vm, struct shmmap_state *shmmap_s)
 194 {
 195         struct shmid_ds *shmseg;
 196         int segnum, result;
 197         size_t size;
 198
 199         segnum = IPCID_TO_IX(shmmap_s->shmid);
 200         shmseg = &shmsegs[segnum];
 201         size = round_page(shmseg->shm_segsz);
 202         result = vm_map_remove(&vm->vm_map, shmmap_s->va, shmmap_s->va + size);
 203         if (result != KERN_SUCCESS)
 204                 return EINVAL;
 205         shmmap_s->shmid = -1;
 206         shmseg->shm_dtime = time_second;
 207         if ((--shmseg->shm_nattch <= 0) &&
 208             (shmseg->shm_perm.mode & SHMSEG_REMOVED)) {
 209                 shm_deallocate_segment(shmseg);
 210                 shm_last_free = segnum;
 211         }
 212         return 0;
 213 }
 214
 215 /*
 216  * MPALMOSTSAFE
 217  */
 218 int
 219 sys_shmdt(struct shmdt_args *uap)
 220 {
 221         struct thread *td = curthread;
 222         struct proc *p = td->td_proc;
 223         struct shmmap_state *shmmap_s;
 224         int i;
 225         int error;
 226
 227         if (!jail_sysvipc_allowed && td->td_ucred->cr_prison != NULL)
 228                 return (ENOSYS);
 229
 230         get_mplock();
 231         shmmap_s = (struct shmmap_state *)p->p_vmspace->vm_shm;
 232         if (shmmap_s == NULL) {
 233                 error = EINVAL;
 234                 goto done;
 235         }
 236         for (i = 0; i < shminfo.shmseg; i++, shmmap_s++) {
 237                 if (shmmap_s->shmid != -1 &&
 238                     shmmap_s->va == (vm_offset_t)uap->shmaddr)
 239                         break;
 240         }
 241         if (i == shminfo.shmseg)
 242                 error = EINVAL;
 243         else
 244                 error = shm_delete_mapping(p->p_vmspace, shmmap_s);
 245 done:
 246         rel_mplock();
 247         return (error);
 248 }
 249
 250 /*
 251  * MPALMOSTSAFE
 252  */
 253 int
 254 sys_shmat(struct shmat_args *uap)
 255 {
 256         struct thread *td = curthread;
 257         struct proc *p = td->td_proc;
 258         int error, i, flags;
 259         struct shmid_ds *shmseg;
 260         struct shmmap_state *shmmap_s = NULL;
 261         struct shm_handle *shm_handle;
 262         vm_offset_t attach_va;
 263         vm_prot_t prot;
 264         vm_size_t size;
 265         int rv;
 266
 267         if (!jail_sysvipc_allowed && td->td_ucred->cr_prison != NULL)
 268                 return (ENOSYS);
 269
 270         get_mplock();
 271 again:
 272         shmmap_s = (struct shmmap_state *)p->p_vmspace->vm_shm;
 273         if (shmmap_s == NULL) {
 274                 size = shminfo.shmseg * sizeof(struct shmmap_state);
 275                 shmmap_s = kmalloc(size, M_SHM, M_WAITOK);
 276                 for (i = 0; i < shminfo.shmseg; i++)
 277                         shmmap_s[i].shmid = -1;
 278                 if (p->p_vmspace->vm_shm != NULL) {
 279                         kfree(shmmap_s, M_SHM);
 280                         goto again;
 281                 }
 282                 p->p_vmspace->vm_shm = (caddr_t)shmmap_s;
 283         }
 284         shmseg = shm_find_segment_by_shmid(uap->shmid);
 285         if (shmseg == NULL) {
 286                 error = EINVAL;
 287                 goto done;
 288         }
 289         error = ipcperm(p, &shmseg->shm_perm,
 290                         (uap->shmflg & SHM_RDONLY) ? IPC_R : IPC_R|IPC_W);
 291         if (error)
 292                 goto done;
 293         for (i = 0; i < shminfo.shmseg; i++) {
 294                 if (shmmap_s->shmid == -1)
 295                         break;
 296                 shmmap_s++;
 297         }
 298         if (i >= shminfo.shmseg) {
 299                 error = EMFILE;
 300                 goto done;
 301         }
 302         size = round_page(shmseg->shm_segsz);
 303 #ifdef VM_PROT_READ_IS_EXEC
 304         prot = VM_PROT_READ | VM_PROT_EXECUTE;
 305 #else
 306         prot = VM_PROT_READ;
 307 #endif
 308         if ((uap->shmflg & SHM_RDONLY) == 0)
 309                 prot |= VM_PROT_WRITE;
 310         flags = MAP_ANON | MAP_SHARED;
 311         if (uap->shmaddr) {
 312                 flags |= MAP_FIXED;
 313                 if (uap->shmflg & SHM_RND) {
 314                         attach_va = (vm_offset_t)uap->shmaddr & ~(SHMLBA-1);
 315                 } else if (((vm_offset_t)uap->shmaddr & (SHMLBA-1)) == 0) {
 316                         attach_va = (vm_offset_t)uap->shmaddr;
 317                 } else {
 318                         error = EINVAL;
 319                         goto done;
 320                 }
 321         } else {
 322                 /*
 323                  * This is just a hint to vm_map_find() about where to put it.
 324                  */
 325                 attach_va = round_page((vm_offset_t)p->p_vmspace->vm_taddr + maxtsiz + maxdsiz);
 326         }
 327
 328         shm_handle = shmseg->shm_internal;
 329         vm_object_reference(shm_handle->shm_object);
 330         rv = vm_map_find(&p->p_vmspace->vm_map,
 331                          shm_handle->shm_object, 0,
 332                          &attach_va, size,
 333                          ((flags & MAP_FIXED) ? 0 : 1),
 334                          VM_MAPTYPE_NORMAL,
 335                          prot, prot,
 336                          0);
 337         if (rv != KERN_SUCCESS) {
 338                 vm_object_deallocate(shm_handle->shm_object);
 339                 error = ENOMEM;
 340                 goto done;
 341         }
 342         vm_map_inherit(&p->p_vmspace->vm_map,
 343                        attach_va, attach_va + size, VM_INHERIT_SHARE);
 344
 345         KKASSERT(shmmap_s->shmid == -1);
 346         shmmap_s->va = attach_va;
 347         shmmap_s->shmid = uap->shmid;
 348         shmseg->shm_lpid = p->p_pid;
 349         shmseg->shm_atime = time_second;
 350         shmseg->shm_nattch++;
 351         uap->sysmsg_result = attach_va;
 352         error = 0;
 353 done:
 354         rel_mplock();
 355         return error;
 356 }
 357
 358 struct oshmid_ds {
 359         struct  ipc_perm shm_perm;      /* operation perms */
 360         int     shm_segsz;              /* size of segment (bytes) */
 361         ushort  shm_cpid;               /* pid, creator */
 362         ushort  shm_lpid;               /* pid, last operation */
 363         short   shm_nattch;             /* no. of current attaches */
 364         time_t  shm_atime;              /* last attach time */
 365         time_t  shm_dtime;              /* last detach time */
 366         time_t  shm_ctime;              /* last change time */
 367         void    *shm_handle;            /* internal handle for shm segment */
 368 };
 369
 370 struct oshmctl_args {
 371         struct sysmsg sysmsg;
 372         int shmid;
 373         int cmd;
 374         struct oshmid_ds *ubuf;
 375 };
 376
 377 /*
 378  * MPALMOSTSAFE
 379  */
 380 static int
 381 sys_oshmctl(struct proc *p, struct oshmctl_args *uap)
 382 {
 383 #ifdef COMPAT_43
 384         struct thread *td = curthread;
 385         struct shmid_ds *shmseg;
 386         struct oshmid_ds outbuf;
 387         int error;
 388
 389         if (!jail_sysvipc_allowed && td->td_ucred->cr_prison != NULL)
 390                 return (ENOSYS);
 391
 392         get_mplock();
 393         shmseg = shm_find_segment_by_shmid(uap->shmid);
 394         if (shmseg == NULL) {
 395                 error = EINVAL;
 396                 goto done;
 397         }
 398
 399         switch (uap->cmd) {
 400         case IPC_STAT:
 401                 error = ipcperm(p, &shmseg->shm_perm, IPC_R);
 402                 if (error)
 403                         break;
 404                 outbuf.shm_perm = shmseg->shm_perm;
 405                 outbuf.shm_segsz = shmseg->shm_segsz;
 406                 outbuf.shm_cpid = shmseg->shm_cpid;
 407                 outbuf.shm_lpid = shmseg->shm_lpid;
 408                 outbuf.shm_nattch = shmseg->shm_nattch;
 409                 outbuf.shm_atime = shmseg->shm_atime;
 410                 outbuf.shm_dtime = shmseg->shm_dtime;
 411                 outbuf.shm_ctime = shmseg->shm_ctime;
 412                 outbuf.shm_handle = shmseg->shm_internal;
 413                 error = copyout((caddr_t)&outbuf, uap->ubuf, sizeof(outbuf));
 414                 break;
 415         default:
 416                 /* XXX casting to (sy_call_t *) is bogus, as usual. */
 417                 error = sys_shmctl((struct shmctl_args *)uap);
 418         }
 419 done:
 420         rel_mplock();
 421         return error;
 422 #else
 423         return EINVAL;
 424 #endif
 425 }
 426
 427 /*
 428  * MPALMOSTSAFE
 429  */
 430 int
 431 sys_shmctl(struct shmctl_args *uap)
 432 {
 433         struct thread *td = curthread;
 434         struct proc *p = td->td_proc;
 435         int error;
 436         struct shmid_ds inbuf;
 437         struct shmid_ds *shmseg;
 438
 439         if (!jail_sysvipc_allowed && td->td_ucred->cr_prison != NULL)
 440                 return (ENOSYS);
 441
 442         get_mplock();
 443         shmseg = shm_find_segment_by_shmid(uap->shmid);
 444         if (shmseg == NULL) {
 445                 error = EINVAL;
 446                 goto done;
 447         }
 448
 449         switch (uap->cmd) {
 450         case IPC_STAT:
 451                 error = ipcperm(p, &shmseg->shm_perm, IPC_R);
 452                 if (error == 0)
 453                         error = copyout(shmseg, uap->buf, sizeof(inbuf));
 454                 break;
 455         case IPC_SET:
 456                 error = ipcperm(p, &shmseg->shm_perm, IPC_M);
 457                 if (error == 0)
 458                         error = copyin(uap->buf, &inbuf, sizeof(inbuf));
 459                 if (error == 0) {
 460                         shmseg->shm_perm.uid = inbuf.shm_perm.uid;
 461                         shmseg->shm_perm.gid = inbuf.shm_perm.gid;
 462                         shmseg->shm_perm.mode =
 463                             (shmseg->shm_perm.mode & ~ACCESSPERMS) |
 464                             (inbuf.shm_perm.mode & ACCESSPERMS);
 465                         shmseg->shm_ctime = time_second;
 466                 }
 467                 break;
 468         case IPC_RMID:
 469                 error = ipcperm(p, &shmseg->shm_perm, IPC_M);
 470                 if (error == 0) {
 471                         shmseg->shm_perm.key = IPC_PRIVATE;
 472                         shmseg->shm_perm.mode |= SHMSEG_REMOVED;
 473                         if (shmseg->shm_nattch <= 0) {
 474                                 shm_deallocate_segment(shmseg);
 475                                 shm_last_free = IPCID_TO_IX(uap->shmid);
 476                         }
 477                 }
 478                 break;
 479 #if 0
 480         case SHM_LOCK:
 481         case SHM_UNLOCK:
 482 #endif
 483         default:
 484                 error = EINVAL;
 485                 break;
 486         }
 487 done:
 488         rel_mplock();
 489         return error;
 490 }
 491
 492 static int
 493 shmget_existing(struct proc *p, struct shmget_args *uap, int mode, int segnum)
 494 {
 495         struct shmid_ds *shmseg;
 496         int error;
 497
 498         shmseg = &shmsegs[segnum];
 499         if (shmseg->shm_perm.mode & SHMSEG_REMOVED) {
 500                 /*
 501                  * This segment is in the process of being allocated.  Wait
 502                  * until it's done, and look the key up again (in case the
 503                  * allocation failed or it was freed).
 504                  */
 505                 shmseg->shm_perm.mode |= SHMSEG_WANTED;
 506                 error = tsleep((caddr_t)shmseg, PCATCH, "shmget", 0);
 507                 if (error)
 508                         return error;
 509                 return EAGAIN;
 510         }
 511         if ((uap->shmflg & (IPC_CREAT | IPC_EXCL)) == (IPC_CREAT | IPC_EXCL))
 512                 return EEXIST;
 513         error = ipcperm(p, &shmseg->shm_perm, mode);
 514         if (error)
 515                 return error;
 516         if (uap->size && uap->size > shmseg->shm_segsz)
 517                 return EINVAL;
 518         uap->sysmsg_result = IXSEQ_TO_IPCID(segnum, shmseg->shm_perm);
 519         return 0;
 520 }
 521
 522 static int
 523 shmget_allocate_segment(struct proc *p, struct shmget_args *uap, int mode)
 524 {
 525         int i, segnum, shmid, size;
 526         struct ucred *cred = p->p_ucred;
 527         struct shmid_ds *shmseg;
 528         struct shm_handle *shm_handle;
 529
 530         if (uap->size < shminfo.shmmin || uap->size > shminfo.shmmax)
 531                 return EINVAL;
 532         if (shm_nused >= shminfo.shmmni) /* any shmids left? */
 533                 return ENOSPC;
 534         size = round_page(uap->size);
 535         if (shm_committed + btoc(size) > shminfo.shmall)
 536                 return ENOMEM;
 537         if (shm_last_free < 0) {
 538                 shmrealloc();   /* maybe expand the shmsegs[] array */
 539                 for (i = 0; i < shmalloced; i++)
 540                         if (shmsegs[i].shm_perm.mode & SHMSEG_FREE)
 541                                 break;
 542                 if (i == shmalloced)
 543                         return ENOSPC;
 544                 segnum = i;
 545         } else  {
 546                 segnum = shm_last_free;
 547                 shm_last_free = -1;
 548         }
 549         shmseg = &shmsegs[segnum];
 550         /*
 551          * In case we sleep in malloc(), mark the segment present but deleted
 552          * so that noone else tries to create the same key.
 553          */
 554         shmseg->shm_perm.mode = SHMSEG_ALLOCATED | SHMSEG_REMOVED;
 555         shmseg->shm_perm.key = uap->key;
 556         shmseg->shm_perm.seq = (shmseg->shm_perm.seq + 1) & 0x7fff;
 557         shm_handle = kmalloc(sizeof(struct shm_handle), M_SHM, M_WAITOK);
 558         shmid = IXSEQ_TO_IPCID(segnum, shmseg->shm_perm);
 559
 560         /*
 561          * We make sure that we have allocated a pager before we need
 562          * to.
 563          */
 564         if (shm_use_phys) {
 565                 shm_handle->shm_object =
 566                    vm_pager_allocate(OBJT_PHYS, NULL, size, VM_PROT_DEFAULT, 0);
 567         } else {
 568                 shm_handle->shm_object =
 569                    vm_pager_allocate(OBJT_SWAP, NULL, size, VM_PROT_DEFAULT, 0);
 570         }
 571         vm_object_clear_flag(shm_handle->shm_object, OBJ_ONEMAPPING);
 572         vm_object_set_flag(shm_handle->shm_object, OBJ_NOSPLIT);
 573
 574         shmseg->shm_internal = shm_handle;
 575         shmseg->shm_perm.cuid = shmseg->shm_perm.uid = cred->cr_uid;
 576         shmseg->shm_perm.cgid = shmseg->shm_perm.gid = cred->cr_gid;
 577         shmseg->shm_perm.mode = (shmseg->shm_perm.mode & SHMSEG_WANTED) |
 578             (mode & ACCESSPERMS) | SHMSEG_ALLOCATED;
 579         shmseg->shm_segsz = uap->size;
 580         shmseg->shm_cpid = p->p_pid;
 581         shmseg->shm_lpid = shmseg->shm_nattch = 0;
 582         shmseg->shm_atime = shmseg->shm_dtime = 0;
 583         shmseg->shm_ctime = time_second;
 584         shm_committed += btoc(size);
 585         shm_nused++;
 586         if (shmseg->shm_perm.mode & SHMSEG_WANTED) {
 587                 /*
 588                  * Somebody else wanted this key while we were asleep.  Wake
 589                  * them up now.
 590                  */
 591                 shmseg->shm_perm.mode &= ~SHMSEG_WANTED;
 592                 wakeup((caddr_t)shmseg);
 593         }
 594         uap->sysmsg_result = shmid;
 595         return 0;
 596 }
 597
 598 /*
 599  * MPALMOSTSAFE
 600  */
 601 int
 602 sys_shmget(struct shmget_args *uap)
 603 {
 604         struct thread *td = curthread;
 605         struct proc *p = td->td_proc;
 606         int segnum, mode, error;
 607
 608         if (!jail_sysvipc_allowed && td->td_ucred->cr_prison != NULL)
 609                 return (ENOSYS);
 610
 611         mode = uap->shmflg & ACCESSPERMS;
 612         get_mplock();
 613
 614         if (uap->key != IPC_PRIVATE) {
 615         again:
 616                 segnum = shm_find_segment_by_key(uap->key);
 617                 if (segnum >= 0) {
 618                         error = shmget_existing(p, uap, mode, segnum);
 619                         if (error == EAGAIN)
 620                                 goto again;
 621                         goto done;
 622                 }
 623                 if ((uap->shmflg & IPC_CREAT) == 0) {
 624                         error = ENOENT;
 625                         goto done;
 626                 }
 627         }
 628         error = shmget_allocate_segment(p, uap, mode);
 629 done:
 630         rel_mplock();
 631         return (error);
 632 }
 633
 634 /*
 635  * shmsys_args(int which, int a2, ...) (VARARGS)
 636  *
 637  * MPALMOSTSAFE
 638  */
 639 int
 640 sys_shmsys(struct shmsys_args *uap)
 641 {
 642         struct thread *td = curthread;
 643         unsigned int which = (unsigned int)uap->which;
 644         int error;
 645
 646         if (!jail_sysvipc_allowed && td->td_ucred->cr_prison != NULL)
 647                 return (ENOSYS);
 648
 649         if (which >= sizeof(shmcalls)/sizeof(shmcalls[0]))
 650                 return EINVAL;
 651         get_mplock();
 652         bcopy(&uap->a2, &uap->which,
 653                 sizeof(struct shmsys_args) - offsetof(struct shmsys_args, a2));
 654         error = ((*shmcalls[which])(uap));
 655         rel_mplock();
 656
 657         return(error);
 658 }
 659
 660 void
 661 shmfork(struct proc *p1, struct proc *p2)
 662 {
 663         struct shmmap_state *shmmap_s;
 664         size_t size;
 665         int i;
 666
 667         size = shminfo.shmseg * sizeof(struct shmmap_state);
 668         shmmap_s = kmalloc(size, M_SHM, M_WAITOK);
 669         bcopy((caddr_t)p1->p_vmspace->vm_shm, (caddr_t)shmmap_s, size);
 670         p2->p_vmspace->vm_shm = (caddr_t)shmmap_s;
 671         for (i = 0; i < shminfo.shmseg; i++, shmmap_s++)
 672                 if (shmmap_s->shmid != -1)
 673                         shmsegs[IPCID_TO_IX(shmmap_s->shmid)].shm_nattch++;
 674 }
 675
 676 void
 677 shmexit(struct vmspace *vm)
 678 {
 679         struct shmmap_state *base, *shm;
 680         int i;
 681
 682         if ((base = (struct shmmap_state *)vm->vm_shm) != NULL) {
 683                 vm->vm_shm = NULL;
 684                 for (i = 0, shm = base; i < shminfo.shmseg; i++, shm++) {
 685                         if (shm->shmid != -1)
 686                                 shm_delete_mapping(vm, shm);
 687                 }
 688                 kfree(base, M_SHM);
 689         }
 690 }
 691
 692 static void
 693 shmrealloc(void)
 694 {
 695         int i;
 696         struct shmid_ds *newsegs;
 697
 698         if (shmalloced >= shminfo.shmmni)
 699                 return;
 700
 701         newsegs = kmalloc(shminfo.shmmni * sizeof(*newsegs), M_SHM, M_WAITOK);
 702         for (i = 0; i < shmalloced; i++)
 703                 bcopy(&shmsegs[i], &newsegs[i], sizeof(newsegs[0]));
 704         for (; i < shminfo.shmmni; i++) {
 705                 shmsegs[i].shm_perm.mode = SHMSEG_FREE;
 706                 shmsegs[i].shm_perm.seq = 0;
 707         }
 708         kfree(shmsegs, M_SHM);
 709         shmsegs = newsegs;
 710         shmalloced = shminfo.shmmni;
 711 }
 712
 713 static void
 714 shminit(void *dummy)
 715 {
 716         int i;
 717
 718         shminfo.shmmax = shminfo.shmall * PAGE_SIZE;
 719         shmalloced = shminfo.shmmni;
 720         shmsegs = kmalloc(shmalloced * sizeof(shmsegs[0]), M_SHM, M_WAITOK);
 721         for (i = 0; i < shmalloced; i++) {
 722                 shmsegs[i].shm_perm.mode = SHMSEG_FREE;
 723                 shmsegs[i].shm_perm.seq = 0;
 724         }
 725         shm_last_free = 0;
 726         shm_nused = 0;
 727         shm_committed = 0;
 728 }
 729 SYSINIT(sysv_shm, SI_SUB_SYSV_SHM, SI_ORDER_FIRST, shminit, NULL);