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