1 /* 2 * linux/ipc/shm.c 3 * Copyright (C) 1992, 1993 Krishna Balasubramanian 4 * Many improvements/fixes by Bruno Haible. 5 * Replaced `struct shm_desc' by `struct vm_area_struct', July 1994. 6 * Fixed the shm swap deallocation (shm_unuse()), August 1998 Andrea Arcangeli. 7 * 8 * /proc/sysvipc/shm support (c) 1999 Dragos Acostachioaie <dragos@iname.com> 9 * BIGMEM support, Andrea Arcangeli <andrea@suse.de> 10 * SMP thread shm, Jean-Luc Boyard <jean-luc.boyard@siemens.fr> 11 * HIGHMEM support, Ingo Molnar <mingo@redhat.com> 12 * Make shmmax, shmall, shmmni sysctl'able, Christoph Rohland <cr@sap.com> 13 * Shared /dev/zero support, Kanoj Sarcar <kanoj@sgi.com> 14 * Move the mm functionality over to mm/shmem.c, Christoph Rohland <cr@sap.com> 15 * 16 */ 17 18 #include <linux/config.h> 19 #include <linux/slab.h> 20 #include <linux/mm.h> 21 #include <linux/hugetlb.h> 22 #include <linux/shm.h> 23 #include <linux/init.h> 24 #include <linux/file.h> 25 #include <linux/mman.h> 26 #include <linux/shmem_fs.h> 27 #include <linux/security.h> 28 #include <linux/syscalls.h> 29 #include <linux/audit.h> 30 #include <linux/capability.h> 31 #include <linux/ptrace.h> 32 #include <linux/seq_file.h> 33 34 #include <asm/uaccess.h> 35 36 #include "util.h" 37 38 static struct file_operations shm_file_operations; 39 static struct vm_operations_struct shm_vm_ops; 40 41 static struct ipc_ids shm_ids; 42 43 #define shm_lock(id) ((struct shmid_kernel*)ipc_lock(&shm_ids,id)) 44 #define shm_unlock(shp) ipc_unlock(&(shp)->shm_perm) 45 #define shm_get(id) ((struct shmid_kernel*)ipc_get(&shm_ids,id)) 46 #define shm_buildid(id, seq) \ 47 ipc_buildid(&shm_ids, id, seq) 48 49 static int newseg (key_t key, int shmflg, size_t size); 50 static void shm_open (struct vm_area_struct *shmd); 51 static void shm_close (struct vm_area_struct *shmd); 52 #ifdef CONFIG_PROC_FS 53 static int sysvipc_shm_proc_show(struct seq_file *s, void *it); 54 #endif 55 56 size_t shm_ctlmax = SHMMAX; 57 size_t shm_ctlall = SHMALL; 58 int shm_ctlmni = SHMMNI; 59 60 static int shm_tot; /* total number of shared memory pages */ 61 62 void __init shm_init (void) 63 { 64 ipc_init_ids(&shm_ids, 1); 65 ipc_init_proc_interface("sysvipc/shm", 66 " key shmid perms size cpid lpid nattch uid gid cuid cgid atime dtime ctime\n", 67 &shm_ids, 68 sysvipc_shm_proc_show); 69 } 70 71 static inline int shm_checkid(struct shmid_kernel *s, int id) 72 { 73 if (ipc_checkid(&shm_ids,&s->shm_perm,id)) 74 return -EIDRM; 75 return 0; 76 } 77 78 static inline struct shmid_kernel *shm_rmid(int id) 79 { 80 return (struct shmid_kernel *)ipc_rmid(&shm_ids,id); 81 } 82 83 static inline int shm_addid(struct shmid_kernel *shp) 84 { 85 return ipc_addid(&shm_ids, &shp->shm_perm, shm_ctlmni); 86 } 87 88 89 90 static inline void shm_inc (int id) { 91 struct shmid_kernel *shp; 92 93 if(!(shp = shm_lock(id))) 94 BUG(); 95 shp->shm_atim = get_seconds(); 96 shp->shm_lprid = current->tgid; 97 shp->shm_nattch++; 98 shm_unlock(shp); 99 } 100 101 /* This is called by fork, once for every shm attach. */ 102 static void shm_open (struct vm_area_struct *shmd) 103 { 104 shm_inc (shmd->vm_file->f_dentry->d_inode->i_ino); 105 } 106 107 /* 108 * shm_destroy - free the struct shmid_kernel 109 * 110 * @shp: struct to free 111 * 112 * It has to be called with shp and shm_ids.sem locked, 113 * but returns with shp unlocked and freed. 114 */ 115 static void shm_destroy (struct shmid_kernel *shp) 116 { 117 shm_tot -= (shp->shm_segsz + PAGE_SIZE - 1) >> PAGE_SHIFT; 118 shm_rmid (shp->id); 119 shm_unlock(shp); 120 if (!is_file_hugepages(shp->shm_file)) 121 shmem_lock(shp->shm_file, 0, shp->mlock_user); 122 else 123 user_shm_unlock(shp->shm_file->f_dentry->d_inode->i_size, 124 shp->mlock_user); 125 fput (shp->shm_file); 126 security_shm_free(shp); 127 ipc_rcu_putref(shp); 128 } 129 130 /* 131 * remove the attach descriptor shmd. 132 * free memory for segment if it is marked destroyed. 133 * The descriptor has already been removed from the current->mm->mmap list 134 * and will later be kfree()d. 135 */ 136 static void shm_close (struct vm_area_struct *shmd) 137 { 138 struct file * file = shmd->vm_file; 139 int id = file->f_dentry->d_inode->i_ino; 140 struct shmid_kernel *shp; 141 142 down (&shm_ids.sem); 143 /* remove from the list of attaches of the shm segment */ 144 if(!(shp = shm_lock(id))) 145 BUG(); 146 shp->shm_lprid = current->tgid; 147 shp->shm_dtim = get_seconds(); 148 shp->shm_nattch--; 149 if(shp->shm_nattch == 0 && 150 shp->shm_perm.mode & SHM_DEST) 151 shm_destroy (shp); 152 else 153 shm_unlock(shp); 154 up (&shm_ids.sem); 155 } 156 157 static int shm_mmap(struct file * file, struct vm_area_struct * vma) 158 { 159 int ret; 160 161 ret = shmem_mmap(file, vma); 162 if (ret == 0) { 163 vma->vm_ops = &shm_vm_ops; 164 shm_inc(file->f_dentry->d_inode->i_ino); 165 } 166 167 return ret; 168 } 169 170 static struct file_operations shm_file_operations = { 171 .mmap = shm_mmap, 172 #ifndef CONFIG_MMU 173 .get_unmapped_area = shmem_get_unmapped_area, 174 #endif 175 }; 176 177 static struct vm_operations_struct shm_vm_ops = { 178 .open = shm_open, /* callback for a new vm-area open */ 179 .close = shm_close, /* callback for when the vm-area is released */ 180 .nopage = shmem_nopage, 181 #if defined(CONFIG_NUMA) && defined(CONFIG_SHMEM) 182 .set_policy = shmem_set_policy, 183 .get_policy = shmem_get_policy, 184 #endif 185 }; 186 187 static int newseg (key_t key, int shmflg, size_t size) 188 { 189 int error; 190 struct shmid_kernel *shp; 191 int numpages = (size + PAGE_SIZE -1) >> PAGE_SHIFT; 192 struct file * file; 193 char name[13]; 194 int id; 195 196 if (size < SHMMIN || size > shm_ctlmax) 197 return -EINVAL; 198 199 if (shm_tot + numpages >= shm_ctlall) 200 return -ENOSPC; 201 202 shp = ipc_rcu_alloc(sizeof(*shp)); 203 if (!shp) 204 return -ENOMEM; 205 206 shp->shm_perm.key = key; 207 shp->shm_perm.mode = (shmflg & S_IRWXUGO); 208 shp->mlock_user = NULL; 209 210 shp->shm_perm.security = NULL; 211 error = security_shm_alloc(shp); 212 if (error) { 213 ipc_rcu_putref(shp); 214 return error; 215 } 216 217 if (shmflg & SHM_HUGETLB) { 218 /* hugetlb_zero_setup takes care of mlock user accounting */ 219 file = hugetlb_zero_setup(size); 220 shp->mlock_user = current->user; 221 } else { 222 int acctflag = VM_ACCOUNT; 223 /* 224 * Do not allow no accounting for OVERCOMMIT_NEVER, even 225 * if it's asked for. 226 */ 227 if ((shmflg & SHM_NORESERVE) && 228 sysctl_overcommit_memory != OVERCOMMIT_NEVER) 229 acctflag = 0; 230 sprintf (name, "SYSV%08x", key); 231 file = shmem_file_setup(name, size, acctflag); 232 } 233 error = PTR_ERR(file); 234 if (IS_ERR(file)) 235 goto no_file; 236 237 error = -ENOSPC; 238 id = shm_addid(shp); 239 if(id == -1) 240 goto no_id; 241 242 shp->shm_cprid = current->tgid; 243 shp->shm_lprid = 0; 244 shp->shm_atim = shp->shm_dtim = 0; 245 shp->shm_ctim = get_seconds(); 246 shp->shm_segsz = size; 247 shp->shm_nattch = 0; 248 shp->id = shm_buildid(id,shp->shm_perm.seq); 249 shp->shm_file = file; 250 file->f_dentry->d_inode->i_ino = shp->id; 251 252 /* Hugetlb ops would have already been assigned. */ 253 if (!(shmflg & SHM_HUGETLB)) 254 file->f_op = &shm_file_operations; 255 256 shm_tot += numpages; 257 shm_unlock(shp); 258 return shp->id; 259 260 no_id: 261 fput(file); 262 no_file: 263 security_shm_free(shp); 264 ipc_rcu_putref(shp); 265 return error; 266 } 267 268 asmlinkage long sys_shmget (key_t key, size_t size, int shmflg) 269 { 270 struct shmid_kernel *shp; 271 int err, id = 0; 272 273 down(&shm_ids.sem); 274 if (key == IPC_PRIVATE) { 275 err = newseg(key, shmflg, size); 276 } else if ((id = ipc_findkey(&shm_ids, key)) == -1) { 277 if (!(shmflg & IPC_CREAT)) 278 err = -ENOENT; 279 else 280 err = newseg(key, shmflg, size); 281 } else if ((shmflg & IPC_CREAT) && (shmflg & IPC_EXCL)) { 282 err = -EEXIST; 283 } else { 284 shp = shm_lock(id); 285 if(shp==NULL) 286 BUG(); 287 if (shp->shm_segsz < size) 288 err = -EINVAL; 289 else if (ipcperms(&shp->shm_perm, shmflg)) 290 err = -EACCES; 291 else { 292 int shmid = shm_buildid(id, shp->shm_perm.seq); 293 err = security_shm_associate(shp, shmflg); 294 if (!err) 295 err = shmid; 296 } 297 shm_unlock(shp); 298 } 299 up(&shm_ids.sem); 300 301 return err; 302 } 303 304 static inline unsigned long copy_shmid_to_user(void __user *buf, struct shmid64_ds *in, int version) 305 { 306 switch(version) { 307 case IPC_64: 308 return copy_to_user(buf, in, sizeof(*in)); 309 case IPC_OLD: 310 { 311 struct shmid_ds out; 312 313 ipc64_perm_to_ipc_perm(&in->shm_perm, &out.shm_perm); 314 out.shm_segsz = in->shm_segsz; 315 out.shm_atime = in->shm_atime; 316 out.shm_dtime = in->shm_dtime; 317 out.shm_ctime = in->shm_ctime; 318 out.shm_cpid = in->shm_cpid; 319 out.shm_lpid = in->shm_lpid; 320 out.shm_nattch = in->shm_nattch; 321 322 return copy_to_user(buf, &out, sizeof(out)); 323 } 324 default: 325 return -EINVAL; 326 } 327 } 328 329 struct shm_setbuf { 330 uid_t uid; 331 gid_t gid; 332 mode_t mode; 333 }; 334 335 static inline unsigned long copy_shmid_from_user(struct shm_setbuf *out, void __user *buf, int version) 336 { 337 switch(version) { 338 case IPC_64: 339 { 340 struct shmid64_ds tbuf; 341 342 if (copy_from_user(&tbuf, buf, sizeof(tbuf))) 343 return -EFAULT; 344 345 out->uid = tbuf.shm_perm.uid; 346 out->gid = tbuf.shm_perm.gid; 347 out->mode = tbuf.shm_perm.mode; 348 349 return 0; 350 } 351 case IPC_OLD: 352 { 353 struct shmid_ds tbuf_old; 354 355 if (copy_from_user(&tbuf_old, buf, sizeof(tbuf_old))) 356 return -EFAULT; 357 358 out->uid = tbuf_old.shm_perm.uid; 359 out->gid = tbuf_old.shm_perm.gid; 360 out->mode = tbuf_old.shm_perm.mode; 361 362 return 0; 363 } 364 default: 365 return -EINVAL; 366 } 367 } 368 369 static inline unsigned long copy_shminfo_to_user(void __user *buf, struct shminfo64 *in, int version) 370 { 371 switch(version) { 372 case IPC_64: 373 return copy_to_user(buf, in, sizeof(*in)); 374 case IPC_OLD: 375 { 376 struct shminfo out; 377 378 if(in->shmmax > INT_MAX) 379 out.shmmax = INT_MAX; 380 else 381 out.shmmax = (int)in->shmmax; 382 383 out.shmmin = in->shmmin; 384 out.shmmni = in->shmmni; 385 out.shmseg = in->shmseg; 386 out.shmall = in->shmall; 387 388 return copy_to_user(buf, &out, sizeof(out)); 389 } 390 default: 391 return -EINVAL; 392 } 393 } 394 395 static void shm_get_stat(unsigned long *rss, unsigned long *swp) 396 { 397 int i; 398 399 *rss = 0; 400 *swp = 0; 401 402 for (i = 0; i <= shm_ids.max_id; i++) { 403 struct shmid_kernel *shp; 404 struct inode *inode; 405 406 shp = shm_get(i); 407 if(!shp) 408 continue; 409 410 inode = shp->shm_file->f_dentry->d_inode; 411 412 if (is_file_hugepages(shp->shm_file)) { 413 struct address_space *mapping = inode->i_mapping; 414 *rss += (HPAGE_SIZE/PAGE_SIZE)*mapping->nrpages; 415 } else { 416 struct shmem_inode_info *info = SHMEM_I(inode); 417 spin_lock(&info->lock); 418 *rss += inode->i_mapping->nrpages; 419 *swp += info->swapped; 420 spin_unlock(&info->lock); 421 } 422 } 423 } 424 425 asmlinkage long sys_shmctl (int shmid, int cmd, struct shmid_ds __user *buf) 426 { 427 struct shm_setbuf setbuf; 428 struct shmid_kernel *shp; 429 int err, version; 430 431 if (cmd < 0 || shmid < 0) { 432 err = -EINVAL; 433 goto out; 434 } 435 436 version = ipc_parse_version(&cmd); 437 438 switch (cmd) { /* replace with proc interface ? */ 439 case IPC_INFO: 440 { 441 struct shminfo64 shminfo; 442 443 err = security_shm_shmctl(NULL, cmd); 444 if (err) 445 return err; 446 447 memset(&shminfo,0,sizeof(shminfo)); 448 shminfo.shmmni = shminfo.shmseg = shm_ctlmni; 449 shminfo.shmmax = shm_ctlmax; 450 shminfo.shmall = shm_ctlall; 451 452 shminfo.shmmin = SHMMIN; 453 if(copy_shminfo_to_user (buf, &shminfo, version)) 454 return -EFAULT; 455 /* reading a integer is always atomic */ 456 err= shm_ids.max_id; 457 if(err<0) 458 err = 0; 459 goto out; 460 } 461 case SHM_INFO: 462 { 463 struct shm_info shm_info; 464 465 err = security_shm_shmctl(NULL, cmd); 466 if (err) 467 return err; 468 469 memset(&shm_info,0,sizeof(shm_info)); 470 down(&shm_ids.sem); 471 shm_info.used_ids = shm_ids.in_use; 472 shm_get_stat (&shm_info.shm_rss, &shm_info.shm_swp); 473 shm_info.shm_tot = shm_tot; 474 shm_info.swap_attempts = 0; 475 shm_info.swap_successes = 0; 476 err = shm_ids.max_id; 477 up(&shm_ids.sem); 478 if(copy_to_user (buf, &shm_info, sizeof(shm_info))) { 479 err = -EFAULT; 480 goto out; 481 } 482 483 err = err < 0 ? 0 : err; 484 goto out; 485 } 486 case SHM_STAT: 487 case IPC_STAT: 488 { 489 struct shmid64_ds tbuf; 490 int result; 491 memset(&tbuf, 0, sizeof(tbuf)); 492 shp = shm_lock(shmid); 493 if(shp==NULL) { 494 err = -EINVAL; 495 goto out; 496 } else if(cmd==SHM_STAT) { 497 err = -EINVAL; 498 if (shmid > shm_ids.max_id) 499 goto out_unlock; 500 result = shm_buildid(shmid, shp->shm_perm.seq); 501 } else { 502 err = shm_checkid(shp,shmid); 503 if(err) 504 goto out_unlock; 505 result = 0; 506 } 507 err=-EACCES; 508 if (ipcperms (&shp->shm_perm, S_IRUGO)) 509 goto out_unlock; 510 err = security_shm_shmctl(shp, cmd); 511 if (err) 512 goto out_unlock; 513 kernel_to_ipc64_perm(&shp->shm_perm, &tbuf.shm_perm); 514 tbuf.shm_segsz = shp->shm_segsz; 515 tbuf.shm_atime = shp->shm_atim; 516 tbuf.shm_dtime = shp->shm_dtim; 517 tbuf.shm_ctime = shp->shm_ctim; 518 tbuf.shm_cpid = shp->shm_cprid; 519 tbuf.shm_lpid = shp->shm_lprid; 520 if (!is_file_hugepages(shp->shm_file)) 521 tbuf.shm_nattch = shp->shm_nattch; 522 else 523 tbuf.shm_nattch = file_count(shp->shm_file) - 1; 524 shm_unlock(shp); 525 if(copy_shmid_to_user (buf, &tbuf, version)) 526 err = -EFAULT; 527 else 528 err = result; 529 goto out; 530 } 531 case SHM_LOCK: 532 case SHM_UNLOCK: 533 { 534 shp = shm_lock(shmid); 535 if(shp==NULL) { 536 err = -EINVAL; 537 goto out; 538 } 539 err = shm_checkid(shp,shmid); 540 if(err) 541 goto out_unlock; 542 543 if (!capable(CAP_IPC_LOCK)) { 544 err = -EPERM; 545 if (current->euid != shp->shm_perm.uid && 546 current->euid != shp->shm_perm.cuid) 547 goto out_unlock; 548 if (cmd == SHM_LOCK && 549 !current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur) 550 goto out_unlock; 551 } 552 553 err = security_shm_shmctl(shp, cmd); 554 if (err) 555 goto out_unlock; 556 557 if(cmd==SHM_LOCK) { 558 struct user_struct * user = current->user; 559 if (!is_file_hugepages(shp->shm_file)) { 560 err = shmem_lock(shp->shm_file, 1, user); 561 if (!err) { 562 shp->shm_perm.mode |= SHM_LOCKED; 563 shp->mlock_user = user; 564 } 565 } 566 } else if (!is_file_hugepages(shp->shm_file)) { 567 shmem_lock(shp->shm_file, 0, shp->mlock_user); 568 shp->shm_perm.mode &= ~SHM_LOCKED; 569 shp->mlock_user = NULL; 570 } 571 shm_unlock(shp); 572 goto out; 573 } 574 case IPC_RMID: 575 { 576 /* 577 * We cannot simply remove the file. The SVID states 578 * that the block remains until the last person 579 * detaches from it, then is deleted. A shmat() on 580 * an RMID segment is legal in older Linux and if 581 * we change it apps break... 582 * 583 * Instead we set a destroyed flag, and then blow 584 * the name away when the usage hits zero. 585 */ 586 down(&shm_ids.sem); 587 shp = shm_lock(shmid); 588 err = -EINVAL; 589 if (shp == NULL) 590 goto out_up; 591 err = shm_checkid(shp, shmid); 592 if(err) 593 goto out_unlock_up; 594 595 if (current->euid != shp->shm_perm.uid && 596 current->euid != shp->shm_perm.cuid && 597 !capable(CAP_SYS_ADMIN)) { 598 err=-EPERM; 599 goto out_unlock_up; 600 } 601 602 err = security_shm_shmctl(shp, cmd); 603 if (err) 604 goto out_unlock_up; 605 606 if (shp->shm_nattch){ 607 shp->shm_perm.mode |= SHM_DEST; 608 /* Do not find it any more */ 609 shp->shm_perm.key = IPC_PRIVATE; 610 shm_unlock(shp); 611 } else 612 shm_destroy (shp); 613 up(&shm_ids.sem); 614 goto out; 615 } 616 617 case IPC_SET: 618 { 619 if (copy_shmid_from_user (&setbuf, buf, version)) { 620 err = -EFAULT; 621 goto out; 622 } 623 if ((err = audit_ipc_perms(0, setbuf.uid, setbuf.gid, setbuf.mode))) 624 return err; 625 down(&shm_ids.sem); 626 shp = shm_lock(shmid); 627 err=-EINVAL; 628 if(shp==NULL) 629 goto out_up; 630 err = shm_checkid(shp,shmid); 631 if(err) 632 goto out_unlock_up; 633 err=-EPERM; 634 if (current->euid != shp->shm_perm.uid && 635 current->euid != shp->shm_perm.cuid && 636 !capable(CAP_SYS_ADMIN)) { 637 goto out_unlock_up; 638 } 639 640 err = security_shm_shmctl(shp, cmd); 641 if (err) 642 goto out_unlock_up; 643 644 shp->shm_perm.uid = setbuf.uid; 645 shp->shm_perm.gid = setbuf.gid; 646 shp->shm_perm.mode = (shp->shm_perm.mode & ~S_IRWXUGO) 647 | (setbuf.mode & S_IRWXUGO); 648 shp->shm_ctim = get_seconds(); 649 break; 650 } 651 652 default: 653 err = -EINVAL; 654 goto out; 655 } 656 657 err = 0; 658 out_unlock_up: 659 shm_unlock(shp); 660 out_up: 661 up(&shm_ids.sem); 662 goto out; 663 out_unlock: 664 shm_unlock(shp); 665 out: 666 return err; 667 } 668 669 /* 670 * Fix shmaddr, allocate descriptor, map shm, add attach descriptor to lists. 671 * 672 * NOTE! Despite the name, this is NOT a direct system call entrypoint. The 673 * "raddr" thing points to kernel space, and there has to be a wrapper around 674 * this. 675 */ 676 long do_shmat(int shmid, char __user *shmaddr, int shmflg, ulong *raddr) 677 { 678 struct shmid_kernel *shp; 679 unsigned long addr; 680 unsigned long size; 681 struct file * file; 682 int err; 683 unsigned long flags; 684 unsigned long prot; 685 unsigned long o_flags; 686 int acc_mode; 687 void *user_addr; 688 689 if (shmid < 0) { 690 err = -EINVAL; 691 goto out; 692 } else if ((addr = (ulong)shmaddr)) { 693 if (addr & (SHMLBA-1)) { 694 if (shmflg & SHM_RND) 695 addr &= ~(SHMLBA-1); /* round down */ 696 else 697 #ifndef __ARCH_FORCE_SHMLBA 698 if (addr & ~PAGE_MASK) 699 #endif 700 return -EINVAL; 701 } 702 flags = MAP_SHARED | MAP_FIXED; 703 } else { 704 if ((shmflg & SHM_REMAP)) 705 return -EINVAL; 706 707 flags = MAP_SHARED; 708 } 709 710 if (shmflg & SHM_RDONLY) { 711 prot = PROT_READ; 712 o_flags = O_RDONLY; 713 acc_mode = S_IRUGO; 714 } else { 715 prot = PROT_READ | PROT_WRITE; 716 o_flags = O_RDWR; 717 acc_mode = S_IRUGO | S_IWUGO; 718 } 719 if (shmflg & SHM_EXEC) { 720 prot |= PROT_EXEC; 721 acc_mode |= S_IXUGO; 722 } 723 724 /* 725 * We cannot rely on the fs check since SYSV IPC does have an 726 * additional creator id... 727 */ 728 shp = shm_lock(shmid); 729 if(shp == NULL) { 730 err = -EINVAL; 731 goto out; 732 } 733 err = shm_checkid(shp,shmid); 734 if (err) { 735 shm_unlock(shp); 736 goto out; 737 } 738 if (ipcperms(&shp->shm_perm, acc_mode)) { 739 shm_unlock(shp); 740 err = -EACCES; 741 goto out; 742 } 743 744 err = security_shm_shmat(shp, shmaddr, shmflg); 745 if (err) { 746 shm_unlock(shp); 747 return err; 748 } 749 750 file = shp->shm_file; 751 size = i_size_read(file->f_dentry->d_inode); 752 shp->shm_nattch++; 753 shm_unlock(shp); 754 755 down_write(¤t->mm->mmap_sem); 756 if (addr && !(shmflg & SHM_REMAP)) { 757 user_addr = ERR_PTR(-EINVAL); 758 if (find_vma_intersection(current->mm, addr, addr + size)) 759 goto invalid; 760 /* 761 * If shm segment goes below stack, make sure there is some 762 * space left for the stack to grow (at least 4 pages). 763 */ 764 if (addr < current->mm->start_stack && 765 addr > current->mm->start_stack - size - PAGE_SIZE * 5) 766 goto invalid; 767 } 768 769 user_addr = (void*) do_mmap (file, addr, size, prot, flags, 0); 770 771 invalid: 772 up_write(¤t->mm->mmap_sem); 773 774 down (&shm_ids.sem); 775 if(!(shp = shm_lock(shmid))) 776 BUG(); 777 shp->shm_nattch--; 778 if(shp->shm_nattch == 0 && 779 shp->shm_perm.mode & SHM_DEST) 780 shm_destroy (shp); 781 else 782 shm_unlock(shp); 783 up (&shm_ids.sem); 784 785 *raddr = (unsigned long) user_addr; 786 err = 0; 787 if (IS_ERR(user_addr)) 788 err = PTR_ERR(user_addr); 789 out: 790 return err; 791 } 792 793 asmlinkage long sys_shmat(int shmid, char __user *shmaddr, int shmflg) 794 { 795 unsigned long ret; 796 long err; 797 798 err = do_shmat(shmid, shmaddr, shmflg, &ret); 799 if (err) 800 return err; 801 force_successful_syscall_return(); 802 return (long)ret; 803 } 804 805 /* 806 * detach and kill segment if marked destroyed. 807 * The work is done in shm_close. 808 */ 809 asmlinkage long sys_shmdt(char __user *shmaddr) 810 { 811 struct mm_struct *mm = current->mm; 812 struct vm_area_struct *vma, *next; 813 unsigned long addr = (unsigned long)shmaddr; 814 loff_t size = 0; 815 int retval = -EINVAL; 816 817 down_write(&mm->mmap_sem); 818 819 /* 820 * This function tries to be smart and unmap shm segments that 821 * were modified by partial mlock or munmap calls: 822 * - It first determines the size of the shm segment that should be 823 * unmapped: It searches for a vma that is backed by shm and that 824 * started at address shmaddr. It records it's size and then unmaps 825 * it. 826 * - Then it unmaps all shm vmas that started at shmaddr and that 827 * are within the initially determined size. 828 * Errors from do_munmap are ignored: the function only fails if 829 * it's called with invalid parameters or if it's called to unmap 830 * a part of a vma. Both calls in this function are for full vmas, 831 * the parameters are directly copied from the vma itself and always 832 * valid - therefore do_munmap cannot fail. (famous last words?) 833 */ 834 /* 835 * If it had been mremap()'d, the starting address would not 836 * match the usual checks anyway. So assume all vma's are 837 * above the starting address given. 838 */ 839 vma = find_vma(mm, addr); 840 841 while (vma) { 842 next = vma->vm_next; 843 844 /* 845 * Check if the starting address would match, i.e. it's 846 * a fragment created by mprotect() and/or munmap(), or it 847 * otherwise it starts at this address with no hassles. 848 */ 849 if ((vma->vm_ops == &shm_vm_ops || is_vm_hugetlb_page(vma)) && 850 (vma->vm_start - addr)/PAGE_SIZE == vma->vm_pgoff) { 851 852 853 size = vma->vm_file->f_dentry->d_inode->i_size; 854 do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start); 855 /* 856 * We discovered the size of the shm segment, so 857 * break out of here and fall through to the next 858 * loop that uses the size information to stop 859 * searching for matching vma's. 860 */ 861 retval = 0; 862 vma = next; 863 break; 864 } 865 vma = next; 866 } 867 868 /* 869 * We need look no further than the maximum address a fragment 870 * could possibly have landed at. Also cast things to loff_t to 871 * prevent overflows and make comparisions vs. equal-width types. 872 */ 873 size = PAGE_ALIGN(size); 874 while (vma && (loff_t)(vma->vm_end - addr) <= size) { 875 next = vma->vm_next; 876 877 /* finding a matching vma now does not alter retval */ 878 if ((vma->vm_ops == &shm_vm_ops || is_vm_hugetlb_page(vma)) && 879 (vma->vm_start - addr)/PAGE_SIZE == vma->vm_pgoff) 880 881 do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start); 882 vma = next; 883 } 884 885 up_write(&mm->mmap_sem); 886 return retval; 887 } 888 889 #ifdef CONFIG_PROC_FS 890 static int sysvipc_shm_proc_show(struct seq_file *s, void *it) 891 { 892 struct shmid_kernel *shp = it; 893 char *format; 894 895 #define SMALL_STRING "%10d %10d %4o %10u %5u %5u %5d %5u %5u %5u %5u %10lu %10lu %10lu\n" 896 #define BIG_STRING "%10d %10d %4o %21u %5u %5u %5d %5u %5u %5u %5u %10lu %10lu %10lu\n" 897 898 if (sizeof(size_t) <= sizeof(int)) 899 format = SMALL_STRING; 900 else 901 format = BIG_STRING; 902 return seq_printf(s, format, 903 shp->shm_perm.key, 904 shp->id, 905 shp->shm_perm.mode, 906 shp->shm_segsz, 907 shp->shm_cprid, 908 shp->shm_lprid, 909 is_file_hugepages(shp->shm_file) ? (file_count(shp->shm_file) - 1) : shp->shm_nattch, 910 shp->shm_perm.uid, 911 shp->shm_perm.gid, 912 shp->shm_perm.cuid, 913 shp->shm_perm.cgid, 914 shp->shm_atim, 915 shp->shm_dtim, 916 shp->shm_ctim); 917 } 918 #endif 919