Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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sys/kern/sysv_shm.c
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1 /* $NetBSD: sysv_shm.c,v 1.23 1994/07/04 23:25:12 glass Exp $ */ 2 /*- 3 * Copyright (c) 1994 Adam Glass and Charles Hannum. All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 3. All advertising materials mentioning features or use of this software 14 * must display the following acknowledgement: 15 * This product includes software developed by Adam Glass and Charles 16 * Hannum. 17 * 4. The names of the authors may not be used to endorse or promote products 18 * derived from this software without specific prior written permission. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS OR 21 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 22 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 23 * IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY DIRECT, INDIRECT, 24 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 25 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 26 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 27 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 28 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 29 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 30 */ 31 32 #include <sys/cdefs.h> 33 __FBSDID("$FreeBSD: releng/5.4/sys/kern/sysv_shm.c 145335 2005-04-20 19:11:07Z cvs2svn $"); 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/kernel.h> 41 #include <sys/lock.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/module.h> 48 #include <sys/mutex.h> 49 #include <sys/resourcevar.h> 50 #include <sys/stat.h> 51 #include <sys/syscall.h> 52 #include <sys/syscallsubr.h> 53 #include <sys/sysent.h> 54 #include <sys/sysproto.h> 55 #include <sys/jail.h> 56 57 #include <vm/vm.h> 58 #include <vm/vm_param.h> 59 #include <vm/pmap.h> 60 #include <vm/vm_object.h> 61 #include <vm/vm_map.h> 62 #include <vm/vm_page.h> 63 #include <vm/vm_pager.h> 64 65 static MALLOC_DEFINE(M_SHM, "shm", "SVID compatible shared memory segments"); 66 67 struct oshmctl_args; 68 static int oshmctl(struct thread *td, struct oshmctl_args *uap); 69 70 static int shmget_allocate_segment(struct thread *td, 71 struct shmget_args *uap, int mode); 72 static int shmget_existing(struct thread *td, struct shmget_args *uap, 73 int mode, int segnum); 74 75 /* XXX casting to (sy_call_t *) is bogus, as usual. */ 76 static sy_call_t *shmcalls[] = { 77 (sy_call_t *)shmat, (sy_call_t *)oshmctl, 78 (sy_call_t *)shmdt, (sy_call_t *)shmget, 79 (sy_call_t *)shmctl 80 }; 81 82 #define SHMSEG_FREE 0x0200 83 #define SHMSEG_REMOVED 0x0400 84 #define SHMSEG_ALLOCATED 0x0800 85 #define SHMSEG_WANTED 0x1000 86 87 static int shm_last_free, shm_nused, shm_committed, shmalloced; 88 static struct shmid_ds *shmsegs; 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 struct shmid_ds *shm_find_segment_by_shmidx(int); 99 static int shm_delete_mapping(struct vmspace *vm, struct shmmap_state *); 100 static void shmrealloc(void); 101 static void shminit(void); 102 static int sysvshm_modload(struct module *, int, void *); 103 static int shmunload(void); 104 static void shmexit_myhook(struct vmspace *vm); 105 static void shmfork_myhook(struct proc *p1, struct proc *p2); 106 static int sysctl_shmsegs(SYSCTL_HANDLER_ARGS); 107 108 /* 109 * Tuneable values. 110 */ 111 #ifndef SHMMAXPGS 112 #define SHMMAXPGS 8192 /* Note: sysv shared memory is swap backed. */ 113 #endif 114 #ifndef SHMMAX 115 #define SHMMAX (SHMMAXPGS*PAGE_SIZE) 116 #endif 117 #ifndef SHMMIN 118 #define SHMMIN 1 119 #endif 120 #ifndef SHMMNI 121 #define SHMMNI 192 122 #endif 123 #ifndef SHMSEG 124 #define SHMSEG 128 125 #endif 126 #ifndef SHMALL 127 #define SHMALL (SHMMAXPGS) 128 #endif 129 130 struct shminfo shminfo = { 131 SHMMAX, 132 SHMMIN, 133 SHMMNI, 134 SHMSEG, 135 SHMALL 136 }; 137 138 static int shm_use_phys; 139 static int shm_allow_removed; 140 141 SYSCTL_DECL(_kern_ipc); 142 SYSCTL_INT(_kern_ipc, OID_AUTO, shmmax, CTLFLAG_RW, &shminfo.shmmax, 0, 143 "Maximum shared memory segment size"); 144 SYSCTL_INT(_kern_ipc, OID_AUTO, shmmin, CTLFLAG_RW, &shminfo.shmmin, 0, 145 "Minimum shared memory segment size"); 146 SYSCTL_INT(_kern_ipc, OID_AUTO, shmmni, CTLFLAG_RDTUN, &shminfo.shmmni, 0, 147 "Number of shared memory identifiers"); 148 SYSCTL_INT(_kern_ipc, OID_AUTO, shmseg, CTLFLAG_RDTUN, &shminfo.shmseg, 0, 149 "Number of segments per process"); 150 SYSCTL_INT(_kern_ipc, OID_AUTO, shmall, CTLFLAG_RW, &shminfo.shmall, 0, 151 "Maximum number of pages available for shared memory"); 152 SYSCTL_INT(_kern_ipc, OID_AUTO, shm_use_phys, CTLFLAG_RW, 153 &shm_use_phys, 0, "Enable/Disable locking of shared memory pages in core"); 154 SYSCTL_INT(_kern_ipc, OID_AUTO, shm_allow_removed, CTLFLAG_RW, 155 &shm_allow_removed, 0, 156 "Enable/Disable attachment to attached segments marked for removal"); 157 SYSCTL_PROC(_kern_ipc, OID_AUTO, shmsegs, CTLFLAG_RD, 158 NULL, 0, sysctl_shmsegs, "", 159 "Current number of shared memory segments allocated"); 160 161 static int 162 shm_find_segment_by_key(key) 163 key_t key; 164 { 165 int i; 166 167 for (i = 0; i < shmalloced; i++) 168 if ((shmsegs[i].shm_perm.mode & SHMSEG_ALLOCATED) && 169 shmsegs[i].shm_perm.key == key) 170 return (i); 171 return (-1); 172 } 173 174 static struct shmid_ds * 175 shm_find_segment_by_shmid(int shmid) 176 { 177 int segnum; 178 struct shmid_ds *shmseg; 179 180 segnum = IPCID_TO_IX(shmid); 181 if (segnum < 0 || segnum >= shmalloced) 182 return (NULL); 183 shmseg = &shmsegs[segnum]; 184 if ((shmseg->shm_perm.mode & SHMSEG_ALLOCATED) == 0 || 185 (!shm_allow_removed && 186 (shmseg->shm_perm.mode & SHMSEG_REMOVED) != 0) || 187 shmseg->shm_perm.seq != IPCID_TO_SEQ(shmid)) 188 return (NULL); 189 return (shmseg); 190 } 191 192 static struct shmid_ds * 193 shm_find_segment_by_shmidx(int segnum) 194 { 195 struct shmid_ds *shmseg; 196 197 if (segnum < 0 || segnum >= shmalloced) 198 return (NULL); 199 shmseg = &shmsegs[segnum]; 200 if ((shmseg->shm_perm.mode & SHMSEG_ALLOCATED) == 0 || 201 (!shm_allow_removed && 202 (shmseg->shm_perm.mode & SHMSEG_REMOVED) != 0)) 203 return (NULL); 204 return (shmseg); 205 } 206 207 static void 208 shm_deallocate_segment(shmseg) 209 struct shmid_ds *shmseg; 210 { 211 size_t size; 212 213 GIANT_REQUIRED; 214 215 vm_object_deallocate(shmseg->shm_internal); 216 shmseg->shm_internal = NULL; 217 size = round_page(shmseg->shm_segsz); 218 shm_committed -= btoc(size); 219 shm_nused--; 220 shmseg->shm_perm.mode = SHMSEG_FREE; 221 } 222 223 static int 224 shm_delete_mapping(struct vmspace *vm, struct shmmap_state *shmmap_s) 225 { 226 struct shmid_ds *shmseg; 227 int segnum, result; 228 size_t size; 229 230 GIANT_REQUIRED; 231 232 segnum = IPCID_TO_IX(shmmap_s->shmid); 233 shmseg = &shmsegs[segnum]; 234 size = round_page(shmseg->shm_segsz); 235 result = vm_map_remove(&vm->vm_map, shmmap_s->va, shmmap_s->va + size); 236 if (result != KERN_SUCCESS) 237 return (EINVAL); 238 shmmap_s->shmid = -1; 239 shmseg->shm_dtime = time_second; 240 if ((--shmseg->shm_nattch <= 0) && 241 (shmseg->shm_perm.mode & SHMSEG_REMOVED)) { 242 shm_deallocate_segment(shmseg); 243 shm_last_free = segnum; 244 } 245 return (0); 246 } 247 248 #ifndef _SYS_SYSPROTO_H_ 249 struct shmdt_args { 250 const void *shmaddr; 251 }; 252 #endif 253 254 /* 255 * MPSAFE 256 */ 257 int 258 shmdt(td, uap) 259 struct thread *td; 260 struct shmdt_args *uap; 261 { 262 struct proc *p = td->td_proc; 263 struct shmmap_state *shmmap_s; 264 int i; 265 int error = 0; 266 267 if (!jail_sysvipc_allowed && jailed(td->td_ucred)) 268 return (ENOSYS); 269 mtx_lock(&Giant); 270 shmmap_s = p->p_vmspace->vm_shm; 271 if (shmmap_s == NULL) { 272 error = EINVAL; 273 goto done2; 274 } 275 for (i = 0; i < shminfo.shmseg; i++, shmmap_s++) { 276 if (shmmap_s->shmid != -1 && 277 shmmap_s->va == (vm_offset_t)uap->shmaddr) { 278 break; 279 } 280 } 281 if (i == shminfo.shmseg) { 282 error = EINVAL; 283 goto done2; 284 } 285 error = shm_delete_mapping(p->p_vmspace, shmmap_s); 286 done2: 287 mtx_unlock(&Giant); 288 return (error); 289 } 290 291 #ifndef _SYS_SYSPROTO_H_ 292 struct shmat_args { 293 int shmid; 294 const void *shmaddr; 295 int shmflg; 296 }; 297 #endif 298 299 /* 300 * MPSAFE 301 */ 302 int 303 kern_shmat(td, shmid, shmaddr, shmflg) 304 struct thread *td; 305 int shmid; 306 const void *shmaddr; 307 int shmflg; 308 { 309 struct proc *p = td->td_proc; 310 int i, flags; 311 struct shmid_ds *shmseg; 312 struct shmmap_state *shmmap_s = NULL; 313 vm_offset_t attach_va; 314 vm_prot_t prot; 315 vm_size_t size; 316 int rv; 317 int error = 0; 318 319 if (!jail_sysvipc_allowed && jailed(td->td_ucred)) 320 return (ENOSYS); 321 mtx_lock(&Giant); 322 shmmap_s = p->p_vmspace->vm_shm; 323 if (shmmap_s == NULL) { 324 size = shminfo.shmseg * sizeof(struct shmmap_state); 325 shmmap_s = malloc(size, M_SHM, M_WAITOK); 326 for (i = 0; i < shminfo.shmseg; i++) 327 shmmap_s[i].shmid = -1; 328 p->p_vmspace->vm_shm = shmmap_s; 329 } 330 shmseg = shm_find_segment_by_shmid(shmid); 331 if (shmseg == NULL) { 332 error = EINVAL; 333 goto done2; 334 } 335 error = ipcperm(td, &shmseg->shm_perm, 336 (shmflg & SHM_RDONLY) ? IPC_R : IPC_R|IPC_W); 337 if (error) 338 goto done2; 339 for (i = 0; i < shminfo.shmseg; i++) { 340 if (shmmap_s->shmid == -1) 341 break; 342 shmmap_s++; 343 } 344 if (i >= shminfo.shmseg) { 345 error = EMFILE; 346 goto done2; 347 } 348 size = round_page(shmseg->shm_segsz); 349 #ifdef VM_PROT_READ_IS_EXEC 350 prot = VM_PROT_READ | VM_PROT_EXECUTE; 351 #else 352 prot = VM_PROT_READ; 353 #endif 354 if ((shmflg & SHM_RDONLY) == 0) 355 prot |= VM_PROT_WRITE; 356 flags = MAP_ANON | MAP_SHARED; 357 if (shmaddr) { 358 flags |= MAP_FIXED; 359 if (shmflg & SHM_RND) { 360 attach_va = (vm_offset_t)shmaddr & ~(SHMLBA-1); 361 } else if (((vm_offset_t)shmaddr & (SHMLBA-1)) == 0) { 362 attach_va = (vm_offset_t)shmaddr; 363 } else { 364 error = EINVAL; 365 goto done2; 366 } 367 } else { 368 /* 369 * This is just a hint to vm_map_find() about where to 370 * put it. 371 */ 372 PROC_LOCK(p); 373 attach_va = round_page((vm_offset_t)p->p_vmspace->vm_daddr + 374 lim_max(p, RLIMIT_DATA)); 375 PROC_UNLOCK(p); 376 } 377 378 vm_object_reference(shmseg->shm_internal); 379 rv = vm_map_find(&p->p_vmspace->vm_map, shmseg->shm_internal, 380 0, &attach_va, size, (flags & MAP_FIXED)?0:1, prot, prot, 0); 381 if (rv != KERN_SUCCESS) { 382 vm_object_deallocate(shmseg->shm_internal); 383 error = ENOMEM; 384 goto done2; 385 } 386 vm_map_inherit(&p->p_vmspace->vm_map, 387 attach_va, attach_va + size, VM_INHERIT_SHARE); 388 389 shmmap_s->va = attach_va; 390 shmmap_s->shmid = shmid; 391 shmseg->shm_lpid = p->p_pid; 392 shmseg->shm_atime = time_second; 393 shmseg->shm_nattch++; 394 td->td_retval[0] = attach_va; 395 done2: 396 mtx_unlock(&Giant); 397 return (error); 398 } 399 400 int 401 shmat(td, uap) 402 struct thread *td; 403 struct shmat_args *uap; 404 { 405 return kern_shmat(td, uap->shmid, uap->shmaddr, uap->shmflg); 406 } 407 408 struct oshmid_ds { 409 struct ipc_perm shm_perm; /* operation perms */ 410 int shm_segsz; /* size of segment (bytes) */ 411 u_short shm_cpid; /* pid, creator */ 412 u_short shm_lpid; /* pid, last operation */ 413 short shm_nattch; /* no. of current attaches */ 414 time_t shm_atime; /* last attach time */ 415 time_t shm_dtime; /* last detach time */ 416 time_t shm_ctime; /* last change time */ 417 void *shm_handle; /* internal handle for shm segment */ 418 }; 419 420 struct oshmctl_args { 421 int shmid; 422 int cmd; 423 struct oshmid_ds *ubuf; 424 }; 425 426 /* 427 * MPSAFE 428 */ 429 static int 430 oshmctl(td, uap) 431 struct thread *td; 432 struct oshmctl_args *uap; 433 { 434 #ifdef COMPAT_43 435 int error = 0; 436 struct shmid_ds *shmseg; 437 struct oshmid_ds outbuf; 438 439 if (!jail_sysvipc_allowed && jailed(td->td_ucred)) 440 return (ENOSYS); 441 mtx_lock(&Giant); 442 shmseg = shm_find_segment_by_shmid(uap->shmid); 443 if (shmseg == NULL) { 444 error = EINVAL; 445 goto done2; 446 } 447 switch (uap->cmd) { 448 case IPC_STAT: 449 error = ipcperm(td, &shmseg->shm_perm, IPC_R); 450 if (error) 451 goto done2; 452 outbuf.shm_perm = shmseg->shm_perm; 453 outbuf.shm_segsz = shmseg->shm_segsz; 454 outbuf.shm_cpid = shmseg->shm_cpid; 455 outbuf.shm_lpid = shmseg->shm_lpid; 456 outbuf.shm_nattch = shmseg->shm_nattch; 457 outbuf.shm_atime = shmseg->shm_atime; 458 outbuf.shm_dtime = shmseg->shm_dtime; 459 outbuf.shm_ctime = shmseg->shm_ctime; 460 outbuf.shm_handle = shmseg->shm_internal; 461 error = copyout(&outbuf, uap->ubuf, sizeof(outbuf)); 462 if (error) 463 goto done2; 464 break; 465 default: 466 error = shmctl(td, (struct shmctl_args *)uap); 467 break; 468 } 469 done2: 470 mtx_unlock(&Giant); 471 return (error); 472 #else 473 return (EINVAL); 474 #endif 475 } 476 477 #ifndef _SYS_SYSPROTO_H_ 478 struct shmctl_args { 479 int shmid; 480 int cmd; 481 struct shmid_ds *buf; 482 }; 483 #endif 484 485 /* 486 * MPSAFE 487 */ 488 int 489 kern_shmctl(td, shmid, cmd, buf, bufsz) 490 struct thread *td; 491 int shmid; 492 int cmd; 493 void *buf; 494 size_t *bufsz; 495 { 496 int error = 0; 497 struct shmid_ds *shmseg; 498 499 if (!jail_sysvipc_allowed && jailed(td->td_ucred)) 500 return (ENOSYS); 501 502 mtx_lock(&Giant); 503 switch (cmd) { 504 case IPC_INFO: 505 memcpy(buf, &shminfo, sizeof(shminfo)); 506 if (bufsz) 507 *bufsz = sizeof(shminfo); 508 td->td_retval[0] = shmalloced; 509 goto done2; 510 case SHM_INFO: { 511 struct shm_info shm_info; 512 shm_info.used_ids = shm_nused; 513 shm_info.shm_rss = 0; /*XXX where to get from ? */ 514 shm_info.shm_tot = 0; /*XXX where to get from ? */ 515 shm_info.shm_swp = 0; /*XXX where to get from ? */ 516 shm_info.swap_attempts = 0; /*XXX where to get from ? */ 517 shm_info.swap_successes = 0; /*XXX where to get from ? */ 518 memcpy(buf, &shm_info, sizeof(shm_info)); 519 if (bufsz) 520 *bufsz = sizeof(shm_info); 521 td->td_retval[0] = shmalloced; 522 goto done2; 523 } 524 } 525 if (cmd == SHM_STAT) 526 shmseg = shm_find_segment_by_shmidx(shmid); 527 else 528 shmseg = shm_find_segment_by_shmid(shmid); 529 if (shmseg == NULL) { 530 error = EINVAL; 531 goto done2; 532 } 533 switch (cmd) { 534 case SHM_STAT: 535 case IPC_STAT: 536 error = ipcperm(td, &shmseg->shm_perm, IPC_R); 537 if (error) 538 goto done2; 539 memcpy(buf, shmseg, sizeof(struct shmid_ds)); 540 if (bufsz) 541 *bufsz = sizeof(struct shmid_ds); 542 if (cmd == SHM_STAT) 543 td->td_retval[0] = IXSEQ_TO_IPCID(shmid, shmseg->shm_perm); 544 break; 545 case IPC_SET: { 546 struct shmid_ds *shmid; 547 548 shmid = (struct shmid_ds *)buf; 549 error = ipcperm(td, &shmseg->shm_perm, IPC_M); 550 if (error) 551 goto done2; 552 shmseg->shm_perm.uid = shmid->shm_perm.uid; 553 shmseg->shm_perm.gid = shmid->shm_perm.gid; 554 shmseg->shm_perm.mode = 555 (shmseg->shm_perm.mode & ~ACCESSPERMS) | 556 (shmid->shm_perm.mode & ACCESSPERMS); 557 shmseg->shm_ctime = time_second; 558 break; 559 } 560 case IPC_RMID: 561 error = ipcperm(td, &shmseg->shm_perm, IPC_M); 562 if (error) 563 goto done2; 564 shmseg->shm_perm.key = IPC_PRIVATE; 565 shmseg->shm_perm.mode |= SHMSEG_REMOVED; 566 if (shmseg->shm_nattch <= 0) { 567 shm_deallocate_segment(shmseg); 568 shm_last_free = IPCID_TO_IX(shmid); 569 } 570 break; 571 #if 0 572 case SHM_LOCK: 573 case SHM_UNLOCK: 574 #endif 575 default: 576 error = EINVAL; 577 break; 578 } 579 done2: 580 mtx_unlock(&Giant); 581 return (error); 582 } 583 584 int 585 shmctl(td, uap) 586 struct thread *td; 587 struct shmctl_args *uap; 588 { 589 int error = 0; 590 struct shmid_ds buf; 591 size_t bufsz; 592 593 /* IPC_SET needs to copyin the buffer before calling kern_shmctl */ 594 if (uap->cmd == IPC_SET) { 595 if ((error = copyin(uap->buf, &buf, sizeof(struct shmid_ds)))) 596 goto done; 597 } 598 599 error = kern_shmctl(td, uap->shmid, uap->cmd, (void *)&buf, &bufsz); 600 if (error) 601 goto done; 602 603 /* Cases in which we need to copyout */ 604 switch (uap->cmd) { 605 case IPC_INFO: 606 case SHM_INFO: 607 case SHM_STAT: 608 case IPC_STAT: 609 error = copyout(&buf, uap->buf, bufsz); 610 break; 611 } 612 613 done: 614 if (error) { 615 /* Invalidate the return value */ 616 td->td_retval[0] = -1; 617 } 618 return (error); 619 } 620 621 622 #ifndef _SYS_SYSPROTO_H_ 623 struct shmget_args { 624 key_t key; 625 size_t size; 626 int shmflg; 627 }; 628 #endif 629 630 static int 631 shmget_existing(td, uap, mode, segnum) 632 struct thread *td; 633 struct shmget_args *uap; 634 int mode; 635 int segnum; 636 { 637 struct shmid_ds *shmseg; 638 int error; 639 640 shmseg = &shmsegs[segnum]; 641 if (shmseg->shm_perm.mode & SHMSEG_REMOVED) { 642 /* 643 * This segment is in the process of being allocated. Wait 644 * until it's done, and look the key up again (in case the 645 * allocation failed or it was freed). 646 */ 647 shmseg->shm_perm.mode |= SHMSEG_WANTED; 648 error = tsleep(shmseg, PLOCK | PCATCH, "shmget", 0); 649 if (error) 650 return (error); 651 return (EAGAIN); 652 } 653 if ((uap->shmflg & (IPC_CREAT | IPC_EXCL)) == (IPC_CREAT | IPC_EXCL)) 654 return (EEXIST); 655 error = ipcperm(td, &shmseg->shm_perm, mode); 656 if (error) 657 return (error); 658 if (uap->size && uap->size > shmseg->shm_segsz) 659 return (EINVAL); 660 td->td_retval[0] = IXSEQ_TO_IPCID(segnum, shmseg->shm_perm); 661 return (0); 662 } 663 664 static int 665 shmget_allocate_segment(td, uap, mode) 666 struct thread *td; 667 struct shmget_args *uap; 668 int mode; 669 { 670 int i, segnum, shmid, size; 671 struct ucred *cred = td->td_ucred; 672 struct shmid_ds *shmseg; 673 vm_object_t shm_object; 674 675 GIANT_REQUIRED; 676 677 if (uap->size < shminfo.shmmin || uap->size > shminfo.shmmax) 678 return (EINVAL); 679 if (shm_nused >= shminfo.shmmni) /* Any shmids left? */ 680 return (ENOSPC); 681 size = round_page(uap->size); 682 if (shm_committed + btoc(size) > shminfo.shmall) 683 return (ENOMEM); 684 if (shm_last_free < 0) { 685 shmrealloc(); /* Maybe expand the shmsegs[] array. */ 686 for (i = 0; i < shmalloced; i++) 687 if (shmsegs[i].shm_perm.mode & SHMSEG_FREE) 688 break; 689 if (i == shmalloced) 690 return (ENOSPC); 691 segnum = i; 692 } else { 693 segnum = shm_last_free; 694 shm_last_free = -1; 695 } 696 shmseg = &shmsegs[segnum]; 697 /* 698 * In case we sleep in malloc(), mark the segment present but deleted 699 * so that noone else tries to create the same key. 700 */ 701 shmseg->shm_perm.mode = SHMSEG_ALLOCATED | SHMSEG_REMOVED; 702 shmseg->shm_perm.key = uap->key; 703 shmseg->shm_perm.seq = (shmseg->shm_perm.seq + 1) & 0x7fff; 704 shmid = IXSEQ_TO_IPCID(segnum, shmseg->shm_perm); 705 706 /* 707 * We make sure that we have allocated a pager before we need 708 * to. 709 */ 710 if (shm_use_phys) { 711 shm_object = 712 vm_pager_allocate(OBJT_PHYS, 0, size, VM_PROT_DEFAULT, 0); 713 } else { 714 shm_object = 715 vm_pager_allocate(OBJT_SWAP, 0, size, VM_PROT_DEFAULT, 0); 716 } 717 VM_OBJECT_LOCK(shm_object); 718 vm_object_clear_flag(shm_object, OBJ_ONEMAPPING); 719 vm_object_set_flag(shm_object, OBJ_NOSPLIT); 720 VM_OBJECT_UNLOCK(shm_object); 721 722 shmseg->shm_internal = shm_object; 723 shmseg->shm_perm.cuid = shmseg->shm_perm.uid = cred->cr_uid; 724 shmseg->shm_perm.cgid = shmseg->shm_perm.gid = cred->cr_gid; 725 shmseg->shm_perm.mode = (shmseg->shm_perm.mode & SHMSEG_WANTED) | 726 (mode & ACCESSPERMS) | SHMSEG_ALLOCATED; 727 shmseg->shm_segsz = uap->size; 728 shmseg->shm_cpid = td->td_proc->p_pid; 729 shmseg->shm_lpid = shmseg->shm_nattch = 0; 730 shmseg->shm_atime = shmseg->shm_dtime = 0; 731 shmseg->shm_ctime = time_second; 732 shm_committed += btoc(size); 733 shm_nused++; 734 if (shmseg->shm_perm.mode & SHMSEG_WANTED) { 735 /* 736 * Somebody else wanted this key while we were asleep. Wake 737 * them up now. 738 */ 739 shmseg->shm_perm.mode &= ~SHMSEG_WANTED; 740 wakeup(shmseg); 741 } 742 td->td_retval[0] = shmid; 743 return (0); 744 } 745 746 /* 747 * MPSAFE 748 */ 749 int 750 shmget(td, uap) 751 struct thread *td; 752 struct shmget_args *uap; 753 { 754 int segnum, mode; 755 int error; 756 757 if (!jail_sysvipc_allowed && jailed(td->td_ucred)) 758 return (ENOSYS); 759 mtx_lock(&Giant); 760 mode = uap->shmflg & ACCESSPERMS; 761 if (uap->key != IPC_PRIVATE) { 762 again: 763 segnum = shm_find_segment_by_key(uap->key); 764 if (segnum >= 0) { 765 error = shmget_existing(td, uap, mode, segnum); 766 if (error == EAGAIN) 767 goto again; 768 goto done2; 769 } 770 if ((uap->shmflg & IPC_CREAT) == 0) { 771 error = ENOENT; 772 goto done2; 773 } 774 } 775 error = shmget_allocate_segment(td, uap, mode); 776 done2: 777 mtx_unlock(&Giant); 778 return (error); 779 } 780 781 /* 782 * MPSAFE 783 */ 784 int 785 shmsys(td, uap) 786 struct thread *td; 787 /* XXX actually varargs. */ 788 struct shmsys_args /* { 789 int which; 790 int a2; 791 int a3; 792 int a4; 793 } */ *uap; 794 { 795 int error; 796 797 if (!jail_sysvipc_allowed && jailed(td->td_ucred)) 798 return (ENOSYS); 799 if (uap->which < 0 || 800 uap->which >= sizeof(shmcalls)/sizeof(shmcalls[0])) 801 return (EINVAL); 802 mtx_lock(&Giant); 803 error = (*shmcalls[uap->which])(td, &uap->a2); 804 mtx_unlock(&Giant); 805 return (error); 806 } 807 808 static void 809 shmfork_myhook(p1, p2) 810 struct proc *p1, *p2; 811 { 812 struct shmmap_state *shmmap_s; 813 size_t size; 814 int i; 815 816 mtx_lock(&Giant); 817 size = shminfo.shmseg * sizeof(struct shmmap_state); 818 shmmap_s = malloc(size, M_SHM, M_WAITOK); 819 bcopy(p1->p_vmspace->vm_shm, shmmap_s, size); 820 p2->p_vmspace->vm_shm = shmmap_s; 821 for (i = 0; i < shminfo.shmseg; i++, shmmap_s++) 822 if (shmmap_s->shmid != -1) 823 shmsegs[IPCID_TO_IX(shmmap_s->shmid)].shm_nattch++; 824 mtx_unlock(&Giant); 825 } 826 827 static void 828 shmexit_myhook(struct vmspace *vm) 829 { 830 struct shmmap_state *base, *shm; 831 int i; 832 833 if ((base = vm->vm_shm) != NULL) { 834 vm->vm_shm = NULL; 835 mtx_lock(&Giant); 836 for (i = 0, shm = base; i < shminfo.shmseg; i++, shm++) { 837 if (shm->shmid != -1) 838 shm_delete_mapping(vm, shm); 839 } 840 mtx_unlock(&Giant); 841 free(base, M_SHM); 842 } 843 } 844 845 static void 846 shmrealloc(void) 847 { 848 int i; 849 struct shmid_ds *newsegs; 850 851 if (shmalloced >= shminfo.shmmni) 852 return; 853 854 newsegs = malloc(shminfo.shmmni * sizeof(*newsegs), M_SHM, M_WAITOK); 855 if (newsegs == NULL) 856 return; 857 for (i = 0; i < shmalloced; i++) 858 bcopy(&shmsegs[i], &newsegs[i], sizeof(newsegs[0])); 859 for (; i < shminfo.shmmni; i++) { 860 shmsegs[i].shm_perm.mode = SHMSEG_FREE; 861 shmsegs[i].shm_perm.seq = 0; 862 } 863 free(shmsegs, M_SHM); 864 shmsegs = newsegs; 865 shmalloced = shminfo.shmmni; 866 } 867 868 static void 869 shminit() 870 { 871 int i; 872 873 TUNABLE_INT_FETCH("kern.ipc.shmmaxpgs", &shminfo.shmall); 874 for (i = PAGE_SIZE; i > 0; i--) { 875 shminfo.shmmax = shminfo.shmall * PAGE_SIZE; 876 if (shminfo.shmmax >= shminfo.shmall) 877 break; 878 } 879 TUNABLE_INT_FETCH("kern.ipc.shmmin", &shminfo.shmmin); 880 TUNABLE_INT_FETCH("kern.ipc.shmmni", &shminfo.shmmni); 881 TUNABLE_INT_FETCH("kern.ipc.shmseg", &shminfo.shmseg); 882 TUNABLE_INT_FETCH("kern.ipc.shm_use_phys", &shm_use_phys); 883 884 shmalloced = shminfo.shmmni; 885 shmsegs = malloc(shmalloced * sizeof(shmsegs[0]), M_SHM, M_WAITOK); 886 if (shmsegs == NULL) 887 panic("cannot allocate initial memory for sysvshm"); 888 for (i = 0; i < shmalloced; i++) { 889 shmsegs[i].shm_perm.mode = SHMSEG_FREE; 890 shmsegs[i].shm_perm.seq = 0; 891 } 892 shm_last_free = 0; 893 shm_nused = 0; 894 shm_committed = 0; 895 shmexit_hook = &shmexit_myhook; 896 shmfork_hook = &shmfork_myhook; 897 } 898 899 static int 900 shmunload() 901 { 902 903 if (shm_nused > 0) 904 return (EBUSY); 905 906 free(shmsegs, M_SHM); 907 shmexit_hook = NULL; 908 shmfork_hook = NULL; 909 return (0); 910 } 911 912 static int 913 sysctl_shmsegs(SYSCTL_HANDLER_ARGS) 914 { 915 916 return (SYSCTL_OUT(req, shmsegs, shmalloced * sizeof(shmsegs[0]))); 917 } 918 919 static int 920 sysvshm_modload(struct module *module, int cmd, void *arg) 921 { 922 int error = 0; 923 924 switch (cmd) { 925 case MOD_LOAD: 926 shminit(); 927 break; 928 case MOD_UNLOAD: 929 error = shmunload(); 930 break; 931 case MOD_SHUTDOWN: 932 break; 933 default: 934 error = EINVAL; 935 break; 936 } 937 return (error); 938 } 939 940 static moduledata_t sysvshm_mod = { 941 "sysvshm", 942 &sysvshm_modload, 943 NULL 944 }; 945 946 SYSCALL_MODULE_HELPER(shmsys); 947 SYSCALL_MODULE_HELPER(shmat); 948 SYSCALL_MODULE_HELPER(shmctl); 949 SYSCALL_MODULE_HELPER(shmdt); 950 SYSCALL_MODULE_HELPER(shmget); 951 952 DECLARE_MODULE(sysvshm, sysvshm_mod, 953 SI_SUB_SYSV_SHM, SI_ORDER_FIRST); 954 MODULE_VERSION(sysvshm, 1);
Cache object: cfede77c63a20161d8496a0d8fcc474a
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