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 /*      $NetBSD: sysv_shm.c,v 1.23 1994/07/04 23:25:12 glass Exp $      */
   3
   4 /*
   5  * Copyright (c) 1994 Adam Glass and Charles Hannum.  All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice, this list of conditions and the following disclaimer in the
  14  *    documentation and/or other materials provided with the distribution.
  15  * 3. All advertising materials mentioning features or use of this software
  16  *    must display the following acknowledgement:
  17  *      This product includes software developed by Adam Glass and Charles
  18  *      Hannum.
  19  * 4. The names of the authors may not be used to endorse or promote products
  20  *    derived from this software without specific prior written permission.
  21  *
  22  * THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS OR
  23  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  24  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  25  * IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY DIRECT, INDIRECT,
  26  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  27  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  28  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  29  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  30  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  31  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  32  */
  33
  34 #include "opt_compat.h"
  35 #include "opt_sysvipc.h"
  36
  37 #include <sys/param.h>
  38 #include <sys/systm.h>
  39 #include <sys/sysproto.h>
  40 #include <sys/kernel.h>
  41 #include <sys/sysctl.h>
  42 #include <sys/shm.h>
  43 #include <sys/proc.h>
  44 #include <sys/malloc.h>
  45 #include <sys/mman.h>
  46 #include <sys/stat.h>
  47 #include <sys/sysent.h>
  48 #include <sys/jail.h>
  49
  50 #include <sys/mplock2.h>
  51
  52 #include <vm/vm.h>
  53 #include <vm/vm_param.h>
  54 #include <sys/lock.h>
  55 #include <vm/pmap.h>
  56 #include <vm/vm_object.h>
  57 #include <vm/vm_map.h>
  58 #include <vm/vm_page.h>
  59 #include <vm/vm_pager.h>
  60
  61 static MALLOC_DEFINE(M_SHM, "shm", "SVID compatible shared memory segments");
  62
  63 struct oshmctl_args;
  64 static int sys_oshmctl (struct proc *p, struct oshmctl_args *uap);
  65
  66 static int shmget_allocate_segment (struct proc *p, struct shmget_args *uap, int mode);
  67 static int shmget_existing (struct proc *p, struct shmget_args *uap, int mode, int segnum);
  68
  69 /* XXX casting to (sy_call_t *) is bogus, as usual. */
  70 static sy_call_t *shmcalls[] = {
  71         (sy_call_t *)sys_shmat, (sy_call_t *)sys_oshmctl,
  72         (sy_call_t *)sys_shmdt, (sy_call_t *)sys_shmget,
  73         (sy_call_t *)sys_shmctl
  74 };
  75
  76 #define SHMSEG_FREE             0x0200
  77 #define SHMSEG_REMOVED          0x0400
  78 #define SHMSEG_ALLOCATED        0x0800
  79 #define SHMSEG_WANTED           0x1000
  80
  81 static int shm_last_free, shm_committed, shmalloced;
  82 int shm_nused;
  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 SHMMIN
 106 #define SHMMIN  1
 107 #endif
 108 #ifndef SHMMNI
 109 #define SHMMNI  512
 110 #endif
 111 #ifndef SHMSEG
 112 #define SHMSEG  1024
 113 #endif
 114
 115 struct  shminfo shminfo = {
 116         0,
 117         SHMMIN,
 118         SHMMNI,
 119         SHMSEG,
 120         0
 121 };
 122
 123 static int shm_use_phys;
 124
 125 TUNABLE_LONG("kern.ipc.shmmin", &shminfo.shmmin);
 126 TUNABLE_LONG("kern.ipc.shmmni", &shminfo.shmmni);
 127 TUNABLE_LONG("kern.ipc.shmseg", &shminfo.shmseg);
 128 TUNABLE_LONG("kern.ipc.shmmaxpgs", &shminfo.shmall);
 129 TUNABLE_INT("kern.ipc.shm_use_phys", &shm_use_phys);
 130
 131 SYSCTL_LONG(_kern_ipc, OID_AUTO, shmmax, CTLFLAG_RW, &shminfo.shmmax, 0,
 132     "Max shared memory segment size");
 133 SYSCTL_LONG(_kern_ipc, OID_AUTO, shmmin, CTLFLAG_RW, &shminfo.shmmin, 0,
 134     "Min shared memory segment size");
 135 SYSCTL_LONG(_kern_ipc, OID_AUTO, shmmni, CTLFLAG_RD, &shminfo.shmmni, 0,
 136     "Max number of shared memory identifiers");
 137 SYSCTL_LONG(_kern_ipc, OID_AUTO, shmseg, CTLFLAG_RW, &shminfo.shmseg, 0,
 138     "Max shared memory segments per process");
 139 SYSCTL_LONG(_kern_ipc, OID_AUTO, shmall, CTLFLAG_RW, &shminfo.shmall, 0,
 140     "Max pages of shared memory");
 141 SYSCTL_INT(_kern_ipc, OID_AUTO, shm_use_phys, CTLFLAG_RW, &shm_use_phys, 0,
 142     "Use phys pager allocation instead of swap pager allocation");
 143
 144 static int
 145 shm_find_segment_by_key(key_t key)
 146 {
 147         int i;
 148
 149         for (i = 0; i < shmalloced; i++) {
 150                 if ((shmsegs[i].shm_perm.mode & SHMSEG_ALLOCATED) &&
 151                     shmsegs[i].shm_perm.key == key)
 152                         return i;
 153         }
 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         }
 172         return shmseg;
 173 }
 174
 175 static void
 176 shm_deallocate_segment(struct shmid_ds *shmseg)
 177 {
 178         struct shm_handle *shm_handle;
 179         size_t size;
 180
 181         shm_handle = shmseg->shm_internal;
 182         vm_object_deallocate(shm_handle->shm_object);
 183         kfree((caddr_t)shm_handle, M_SHM);
 184         shmseg->shm_internal = NULL;
 185         size = round_page(shmseg->shm_segsz);
 186         shm_committed -= btoc(size);
 187         shm_nused--;
 188         shmseg->shm_perm.mode = SHMSEG_FREE;
 189 }
 190
 191 static int
 192 shm_delete_mapping(struct vmspace *vm, struct shmmap_state *shmmap_s)
 193 {
 194         struct shmid_ds *shmseg;
 195         int segnum, result;
 196         size_t size;
 197
 198         segnum = IPCID_TO_IX(shmmap_s->shmid);
 199         shmseg = &shmsegs[segnum];
 200         size = round_page(shmseg->shm_segsz);
 201         result = vm_map_remove(&vm->vm_map, shmmap_s->va, shmmap_s->va + size);
 202         if (result != KERN_SUCCESS)
 203                 return EINVAL;
 204         shmmap_s->shmid = -1;
 205         shmseg->shm_dtime = time_second;
 206         if ((--shmseg->shm_nattch <= 0) &&
 207             (shmseg->shm_perm.mode & SHMSEG_REMOVED)) {
 208                 shm_deallocate_segment(shmseg);
 209                 shm_last_free = segnum;
 210         }
 211         return 0;
 212 }
 213
 214 /*
 215  * MPALMOSTSAFE
 216  */
 217 int
 218 sys_shmdt(struct shmdt_args *uap)
 219 {
 220         struct thread *td = curthread;
 221         struct proc *p = td->td_proc;
 222         struct shmmap_state *shmmap_s;
 223         long i;
 224         int error;
 225
 226         if (!jail_sysvipc_allowed && td->td_ucred->cr_prison != NULL)
 227                 return (ENOSYS);
 228
 229         get_mplock();
 230         shmmap_s = (struct shmmap_state *)p->p_vmspace->vm_shm;
 231         if (shmmap_s == NULL) {
 232                 error = EINVAL;
 233                 goto done;
 234         }
 235         for (i = 0; i < shminfo.shmseg; i++, shmmap_s++) {
 236                 if (shmmap_s->shmid != -1 &&
 237                     shmmap_s->va == (vm_offset_t)uap->shmaddr)
 238                         break;
 239         }
 240         if (i == shminfo.shmseg)
 241                 error = EINVAL;
 242         else
 243                 error = shm_delete_mapping(p->p_vmspace, shmmap_s);
 244 done:
 245         rel_mplock();
 246         return (error);
 247 }
 248
 249 /*
 250  * MPALMOSTSAFE
 251  */
 252 int
 253 sys_shmat(struct shmat_args *uap)
 254 {
 255         struct thread *td = curthread;
 256         struct proc *p = td->td_proc;
 257         int error, flags;
 258         long i;
 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_hold(shm_handle->shm_object);
 330         vm_object_reference_locked(shm_handle->shm_object);
 331         rv = vm_map_find(&p->p_vmspace->vm_map,
 332                          shm_handle->shm_object, 0,
 333                          &attach_va,
 334                          size, PAGE_SIZE,
 335                          ((flags & MAP_FIXED) ? 0 : 1),
 336                          VM_MAPTYPE_NORMAL,
 337                          prot, prot,
 338                          0);
 339         vm_object_drop(shm_handle->shm_object);
 340         if (rv != KERN_SUCCESS) {
 341                 vm_object_deallocate(shm_handle->shm_object);
 342                 error = ENOMEM;
 343                 goto done;
 344         }
 345         vm_map_inherit(&p->p_vmspace->vm_map,
 346                        attach_va, attach_va + size, VM_INHERIT_SHARE);
 347
 348         KKASSERT(shmmap_s->shmid == -1);
 349         shmmap_s->va = attach_va;
 350         shmmap_s->shmid = uap->shmid;
 351         shmseg->shm_lpid = p->p_pid;
 352         shmseg->shm_atime = time_second;
 353         shmseg->shm_nattch++;
 354         uap->sysmsg_resultp = (void *)attach_va;
 355         error = 0;
 356 done:
 357         rel_mplock();
 358         return error;
 359 }
 360
 361 struct oshmid_ds {
 362         struct  ipc_perm shm_perm;      /* operation perms */
 363         int     shm_segsz;              /* size of segment (bytes) */
 364         ushort  shm_cpid;               /* pid, creator */
 365         ushort  shm_lpid;               /* pid, last operation */
 366         short   shm_nattch;             /* no. of current attaches */
 367         time_t  shm_atime;              /* last attach time */
 368         time_t  shm_dtime;              /* last detach time */
 369         time_t  shm_ctime;              /* last change time */
 370         void    *shm_handle;            /* internal handle for shm segment */
 371 };
 372
 373 struct oshmctl_args {
 374         struct sysmsg sysmsg;
 375         int shmid;
 376         int cmd;
 377         struct oshmid_ds *ubuf;
 378 };
 379
 380 /*
 381  * MPALMOSTSAFE
 382  */
 383 static int
 384 sys_oshmctl(struct proc *p, struct oshmctl_args *uap)
 385 {
 386 #ifdef COMPAT_43
 387         struct thread *td = curthread;
 388         struct shmid_ds *shmseg;
 389         struct oshmid_ds outbuf;
 390         int error;
 391
 392         if (!jail_sysvipc_allowed && td->td_ucred->cr_prison != NULL)
 393                 return (ENOSYS);
 394
 395         get_mplock();
 396         shmseg = shm_find_segment_by_shmid(uap->shmid);
 397         if (shmseg == NULL) {
 398                 error = EINVAL;
 399                 goto done;
 400         }
 401
 402         switch (uap->cmd) {
 403         case IPC_STAT:
 404                 error = ipcperm(p, &shmseg->shm_perm, IPC_R);
 405                 if (error)
 406                         break;
 407                 outbuf.shm_perm = shmseg->shm_perm;
 408                 outbuf.shm_segsz = shmseg->shm_segsz;
 409                 outbuf.shm_cpid = shmseg->shm_cpid;
 410                 outbuf.shm_lpid = shmseg->shm_lpid;
 411                 outbuf.shm_nattch = shmseg->shm_nattch;
 412                 outbuf.shm_atime = shmseg->shm_atime;
 413                 outbuf.shm_dtime = shmseg->shm_dtime;
 414                 outbuf.shm_ctime = shmseg->shm_ctime;
 415                 outbuf.shm_handle = shmseg->shm_internal;
 416                 error = copyout((caddr_t)&outbuf, uap->ubuf, sizeof(outbuf));
 417                 break;
 418         default:
 419                 /* XXX casting to (sy_call_t *) is bogus, as usual. */
 420                 error = sys_shmctl((struct shmctl_args *)uap);
 421         }
 422 done:
 423         rel_mplock();
 424         return error;
 425 #else
 426         return EINVAL;
 427 #endif
 428 }
 429
 430 /*
 431  * MPALMOSTSAFE
 432  */
 433 int
 434 sys_shmctl(struct shmctl_args *uap)
 435 {
 436         struct thread *td = curthread;
 437         struct proc *p = td->td_proc;
 438         int error;
 439         struct shmid_ds inbuf;
 440         struct shmid_ds *shmseg;
 441
 442         if (!jail_sysvipc_allowed && td->td_ucred->cr_prison != NULL)
 443                 return (ENOSYS);
 444
 445         get_mplock();
 446         shmseg = shm_find_segment_by_shmid(uap->shmid);
 447         if (shmseg == NULL) {
 448                 error = EINVAL;
 449                 goto done;
 450         }
 451
 452         switch (uap->cmd) {
 453         case IPC_STAT:
 454                 error = ipcperm(p, &shmseg->shm_perm, IPC_R);
 455                 if (error == 0)
 456                         error = copyout(shmseg, uap->buf, sizeof(inbuf));
 457                 break;
 458         case IPC_SET:
 459                 error = ipcperm(p, &shmseg->shm_perm, IPC_M);
 460                 if (error == 0)
 461                         error = copyin(uap->buf, &inbuf, sizeof(inbuf));
 462                 if (error == 0) {
 463                         shmseg->shm_perm.uid = inbuf.shm_perm.uid;
 464                         shmseg->shm_perm.gid = inbuf.shm_perm.gid;
 465                         shmseg->shm_perm.mode =
 466                             (shmseg->shm_perm.mode & ~ACCESSPERMS) |
 467                             (inbuf.shm_perm.mode & ACCESSPERMS);
 468                         shmseg->shm_ctime = time_second;
 469                 }
 470                 break;
 471         case IPC_RMID:
 472                 error = ipcperm(p, &shmseg->shm_perm, IPC_M);
 473                 if (error == 0) {
 474                         shmseg->shm_perm.key = IPC_PRIVATE;
 475                         shmseg->shm_perm.mode |= SHMSEG_REMOVED;
 476                         if (shmseg->shm_nattch <= 0) {
 477                                 shm_deallocate_segment(shmseg);
 478                                 shm_last_free = IPCID_TO_IX(uap->shmid);
 479                         }
 480                 }
 481                 break;
 482 #if 0
 483         case SHM_LOCK:
 484         case SHM_UNLOCK:
 485 #endif
 486         default:
 487                 error = EINVAL;
 488                 break;
 489         }
 490 done:
 491         rel_mplock();
 492         return error;
 493 }
 494
 495 static int
 496 shmget_existing(struct proc *p, struct shmget_args *uap, int mode, int segnum)
 497 {
 498         struct shmid_ds *shmseg;
 499         int error;
 500
 501         shmseg = &shmsegs[segnum];
 502         if (shmseg->shm_perm.mode & SHMSEG_REMOVED) {
 503                 /*
 504                  * This segment is in the process of being allocated.  Wait
 505                  * until it's done, and look the key up again (in case the
 506                  * allocation failed or it was freed).
 507                  */
 508                 shmseg->shm_perm.mode |= SHMSEG_WANTED;
 509                 error = tsleep((caddr_t)shmseg, PCATCH, "shmget", 0);
 510                 if (error)
 511                         return error;
 512                 return EAGAIN;
 513         }
 514         if ((uap->shmflg & (IPC_CREAT | IPC_EXCL)) == (IPC_CREAT | IPC_EXCL))
 515                 return EEXIST;
 516         error = ipcperm(p, &shmseg->shm_perm, mode);
 517         if (error)
 518                 return error;
 519         if (uap->size && uap->size > shmseg->shm_segsz)
 520                 return EINVAL;
 521         uap->sysmsg_result = IXSEQ_TO_IPCID(segnum, shmseg->shm_perm);
 522         return 0;
 523 }
 524
 525 static int
 526 shmget_allocate_segment(struct proc *p, struct shmget_args *uap, int mode)
 527 {
 528         int i, segnum, shmid;
 529         size_t size;
 530         struct ucred *cred = p->p_ucred;
 531         struct shmid_ds *shmseg;
 532         struct shm_handle *shm_handle;
 533
 534         if (uap->size < shminfo.shmmin || uap->size > shminfo.shmmax)
 535                 return EINVAL;
 536         if (shm_nused >= shminfo.shmmni) /* any shmids left? */
 537                 return ENOSPC;
 538         size = round_page(uap->size);
 539         if (shm_committed + btoc(size) > shminfo.shmall)
 540                 return ENOMEM;
 541         if (shm_last_free < 0) {
 542                 shmrealloc();   /* maybe expand the shmsegs[] array */
 543                 for (i = 0; i < shmalloced; i++) {
 544                         if (shmsegs[i].shm_perm.mode & SHMSEG_FREE)
 545                                 break;
 546                 }
 547                 if (i == shmalloced)
 548                         return ENOSPC;
 549                 segnum = i;
 550         } else  {
 551                 segnum = shm_last_free;
 552                 shm_last_free = -1;
 553         }
 554         shmseg = &shmsegs[segnum];
 555         /*
 556          * In case we sleep in malloc(), mark the segment present but deleted
 557          * so that noone else tries to create the same key.
 558          */
 559         shmseg->shm_perm.mode = SHMSEG_ALLOCATED | SHMSEG_REMOVED;
 560         shmseg->shm_perm.key = uap->key;
 561         shmseg->shm_perm.seq = (shmseg->shm_perm.seq + 1) & 0x7fff;
 562         shm_handle = kmalloc(sizeof(struct shm_handle), M_SHM, M_WAITOK);
 563         shmid = IXSEQ_TO_IPCID(segnum, shmseg->shm_perm);
 564
 565         /*
 566          * We make sure that we have allocated a pager before we need
 567          * to.
 568          */
 569         if (shm_use_phys) {
 570                 shm_handle->shm_object =
 571                    phys_pager_alloc(NULL, size, VM_PROT_DEFAULT, 0);
 572         } else {
 573                 shm_handle->shm_object =
 574                    swap_pager_alloc(NULL, size, VM_PROT_DEFAULT, 0);
 575         }
 576         vm_object_clear_flag(shm_handle->shm_object, OBJ_ONEMAPPING);
 577         vm_object_set_flag(shm_handle->shm_object, OBJ_NOSPLIT);
 578
 579         shmseg->shm_internal = shm_handle;
 580         shmseg->shm_perm.cuid = shmseg->shm_perm.uid = cred->cr_uid;
 581         shmseg->shm_perm.cgid = shmseg->shm_perm.gid = cred->cr_gid;
 582         shmseg->shm_perm.mode = (shmseg->shm_perm.mode & SHMSEG_WANTED) |
 583             (mode & ACCESSPERMS) | SHMSEG_ALLOCATED;
 584         shmseg->shm_segsz = uap->size;
 585         shmseg->shm_cpid = p->p_pid;
 586         shmseg->shm_lpid = shmseg->shm_nattch = 0;
 587         shmseg->shm_atime = shmseg->shm_dtime = 0;
 588         shmseg->shm_ctime = time_second;
 589         shm_committed += btoc(size);
 590         shm_nused++;
 591         if (shmseg->shm_perm.mode & SHMSEG_WANTED) {
 592                 /*
 593                  * Somebody else wanted this key while we were asleep.  Wake
 594                  * them up now.
 595                  */
 596                 shmseg->shm_perm.mode &= ~SHMSEG_WANTED;
 597                 wakeup((caddr_t)shmseg);
 598         }
 599         uap->sysmsg_result = shmid;
 600         return 0;
 601 }
 602
 603 /*
 604  * MPALMOSTSAFE
 605  */
 606 int
 607 sys_shmget(struct shmget_args *uap)
 608 {
 609         struct thread *td = curthread;
 610         struct proc *p = td->td_proc;
 611         int segnum, mode, error;
 612
 613         if (!jail_sysvipc_allowed && td->td_ucred->cr_prison != NULL)
 614                 return (ENOSYS);
 615
 616         mode = uap->shmflg & ACCESSPERMS;
 617         get_mplock();
 618
 619         if (uap->key != IPC_PRIVATE) {
 620         again:
 621                 segnum = shm_find_segment_by_key(uap->key);
 622                 if (segnum >= 0) {
 623                         error = shmget_existing(p, uap, mode, segnum);
 624                         if (error == EAGAIN)
 625                                 goto again;
 626                         goto done;
 627                 }
 628                 if ((uap->shmflg & IPC_CREAT) == 0) {
 629                         error = ENOENT;
 630                         goto done;
 631                 }
 632         }
 633         error = shmget_allocate_segment(p, uap, mode);
 634 done:
 635         rel_mplock();
 636         return (error);
 637 }
 638
 639 /*
 640  * shmsys_args(int which, int a2, ...) (VARARGS)
 641  *
 642  * MPALMOSTSAFE
 643  */
 644 int
 645 sys_shmsys(struct shmsys_args *uap)
 646 {
 647         struct thread *td = curthread;
 648         unsigned int which = (unsigned int)uap->which;
 649         int error;
 650
 651         if (!jail_sysvipc_allowed && td->td_ucred->cr_prison != NULL)
 652                 return (ENOSYS);
 653
 654         if (which >= NELEM(shmcalls))
 655                 return EINVAL;
 656         get_mplock();
 657         bcopy(&uap->a2, &uap->which,
 658                 sizeof(struct shmsys_args) - offsetof(struct shmsys_args, a2));
 659         error = ((*shmcalls[which])(uap));
 660         rel_mplock();
 661
 662         return(error);
 663 }
 664
 665 void
 666 shmfork(struct proc *p1, struct proc *p2)
 667 {
 668         struct shmmap_state *shmmap_s;
 669         size_t size;
 670         int i;
 671
 672         size = shminfo.shmseg * sizeof(struct shmmap_state);
 673         shmmap_s = kmalloc(size, M_SHM, M_WAITOK);
 674         bcopy((caddr_t)p1->p_vmspace->vm_shm, (caddr_t)shmmap_s, size);
 675         p2->p_vmspace->vm_shm = (caddr_t)shmmap_s;
 676         for (i = 0; i < shminfo.shmseg; i++, shmmap_s++)
 677                 if (shmmap_s->shmid != -1)
 678                         shmsegs[IPCID_TO_IX(shmmap_s->shmid)].shm_nattch++;
 679 }
 680
 681 void
 682 shmexit(struct vmspace *vm)
 683 {
 684         struct shmmap_state *base, *shm;
 685         int i;
 686
 687         if ((base = (struct shmmap_state *)vm->vm_shm) != NULL) {
 688                 vm->vm_shm = NULL;
 689                 for (i = 0, shm = base; i < shminfo.shmseg; i++, shm++) {
 690                         if (shm->shmid != -1)
 691                                 shm_delete_mapping(vm, shm);
 692                 }
 693                 kfree(base, M_SHM);
 694         }
 695 }
 696
 697 static void
 698 shmrealloc(void)
 699 {
 700         int i;
 701         struct shmid_ds *newsegs;
 702
 703         if (shmalloced >= shminfo.shmmni)
 704                 return;
 705
 706         newsegs = kmalloc(shminfo.shmmni * sizeof(*newsegs), M_SHM, M_WAITOK);
 707         for (i = 0; i < shmalloced; i++)
 708                 bcopy(&shmsegs[i], &newsegs[i], sizeof(newsegs[0]));
 709         for (; i < shminfo.shmmni; i++) {
 710                 shmsegs[i].shm_perm.mode = SHMSEG_FREE;
 711                 shmsegs[i].shm_perm.seq = 0;
 712         }
 713         kfree(shmsegs, M_SHM);
 714         shmsegs = newsegs;
 715         shmalloced = shminfo.shmmni;
 716 }
 717
 718 static void
 719 shminit(void *dummy)
 720 {
 721         int i;
 722
 723         /*
 724          * If not overridden by a tunable set the maximum shm to
 725          * 2/3 of main memory.
 726          */
 727         if (shminfo.shmall == 0)
 728                 shminfo.shmall = (size_t)vmstats.v_page_count * 2 / 3;
 729
 730         shminfo.shmmax = shminfo.shmall * PAGE_SIZE;
 731         shmalloced = shminfo.shmmni;
 732         shmsegs = kmalloc(shmalloced * sizeof(shmsegs[0]), M_SHM, M_WAITOK);
 733         for (i = 0; i < shmalloced; i++) {
 734                 shmsegs[i].shm_perm.mode = SHMSEG_FREE;
 735                 shmsegs[i].shm_perm.seq = 0;
 736         }
 737         shm_last_free = 0;
 738         shm_nused = 0;
 739         shm_committed = 0;
 740 }
 741 SYSINIT(sysv_shm, SI_SUB_SYSV_SHM, SI_ORDER_FIRST, shminit, NULL);