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 * support for audit of ipc object properties and permission changes 17 * Dustin Kirkland <dustin.kirkland@us.ibm.com> 18 * 19 * namespaces support 20 * OpenVZ, SWsoft Inc. 21 * Pavel Emelianov <xemul@openvz.org> 22 */ 23 24 #include <linux/slab.h> 25 #include <linux/mm.h> 26 #include <linux/hugetlb.h> 27 #include <linux/shm.h> 28 #include <linux/init.h> 29 #include <linux/file.h> 30 #include <linux/mman.h> 31 #include <linux/shmem_fs.h> 32 #include <linux/security.h> 33 #include <linux/syscalls.h> 34 #include <linux/audit.h> 35 #include <linux/capability.h> 36 #include <linux/ptrace.h> 37 #include <linux/seq_file.h> 38 #include <linux/rwsem.h> 39 #include <linux/nsproxy.h> 40 #include <linux/mount.h> 41 #include <linux/ipc_namespace.h> 42 43 #include <asm/uaccess.h> 44 45 #include "util.h" 46 47 struct shm_file_data { 48 int id; 49 struct ipc_namespace *ns; 50 struct file *file; 51 const struct vm_operations_struct *vm_ops; 52 }; 53 54 #define shm_file_data(file) (*((struct shm_file_data **)&(file)->private_data)) 55 56 static const struct file_operations shm_file_operations; 57 static const struct vm_operations_struct shm_vm_ops; 58 59 #define shm_ids(ns) ((ns)->ids[IPC_SHM_IDS]) 60 61 #define shm_unlock(shp) \ 62 ipc_unlock(&(shp)->shm_perm) 63 64 static int newseg(struct ipc_namespace *, struct ipc_params *); 65 static void shm_open(struct vm_area_struct *vma); 66 static void shm_close(struct vm_area_struct *vma); 67 static void shm_destroy (struct ipc_namespace *ns, struct shmid_kernel *shp); 68 #ifdef CONFIG_PROC_FS 69 static int sysvipc_shm_proc_show(struct seq_file *s, void *it); 70 #endif 71 72 void shm_init_ns(struct ipc_namespace *ns) 73 { 74 ns->shm_ctlmax = SHMMAX; 75 ns->shm_ctlall = SHMALL; 76 ns->shm_ctlmni = SHMMNI; 77 ns->shm_tot = 0; 78 ipc_init_ids(&shm_ids(ns)); 79 } 80 81 /* 82 * Called with shm_ids.rw_mutex (writer) and the shp structure locked. 83 * Only shm_ids.rw_mutex remains locked on exit. 84 */ 85 static void do_shm_rmid(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp) 86 { 87 struct shmid_kernel *shp; 88 shp = container_of(ipcp, struct shmid_kernel, shm_perm); 89 90 if (shp->shm_nattch){ 91 shp->shm_perm.mode |= SHM_DEST; 92 /* Do not find it any more */ 93 shp->shm_perm.key = IPC_PRIVATE; 94 shm_unlock(shp); 95 } else 96 shm_destroy(ns, shp); 97 } 98 99 #ifdef CONFIG_IPC_NS 100 void shm_exit_ns(struct ipc_namespace *ns) 101 { 102 free_ipcs(ns, &shm_ids(ns), do_shm_rmid); 103 idr_destroy(&ns->ids[IPC_SHM_IDS].ipcs_idr); 104 } 105 #endif 106 107 void __init shm_init (void) 108 { 109 shm_init_ns(&init_ipc_ns); 110 ipc_init_proc_interface("sysvipc/shm", 111 " key shmid perms size cpid lpid nattch uid gid cuid cgid atime dtime ctime\n", 112 IPC_SHM_IDS, sysvipc_shm_proc_show); 113 } 114 115 /* 116 * shm_lock_(check_) routines are called in the paths where the rw_mutex 117 * is not necessarily held. 118 */ 119 static inline struct shmid_kernel *shm_lock(struct ipc_namespace *ns, int id) 120 { 121 struct kern_ipc_perm *ipcp = ipc_lock(&shm_ids(ns), id); 122 123 if (IS_ERR(ipcp)) 124 return (struct shmid_kernel *)ipcp; 125 126 return container_of(ipcp, struct shmid_kernel, shm_perm); 127 } 128 129 static inline struct shmid_kernel *shm_lock_check(struct ipc_namespace *ns, 130 int id) 131 { 132 struct kern_ipc_perm *ipcp = ipc_lock_check(&shm_ids(ns), id); 133 134 if (IS_ERR(ipcp)) 135 return (struct shmid_kernel *)ipcp; 136 137 return container_of(ipcp, struct shmid_kernel, shm_perm); 138 } 139 140 static inline void shm_rmid(struct ipc_namespace *ns, struct shmid_kernel *s) 141 { 142 ipc_rmid(&shm_ids(ns), &s->shm_perm); 143 } 144 145 146 /* This is called by fork, once for every shm attach. */ 147 static void shm_open(struct vm_area_struct *vma) 148 { 149 struct file *file = vma->vm_file; 150 struct shm_file_data *sfd = shm_file_data(file); 151 struct shmid_kernel *shp; 152 153 shp = shm_lock(sfd->ns, sfd->id); 154 BUG_ON(IS_ERR(shp)); 155 shp->shm_atim = get_seconds(); 156 shp->shm_lprid = task_tgid_vnr(current); 157 shp->shm_nattch++; 158 shm_unlock(shp); 159 } 160 161 /* 162 * shm_destroy - free the struct shmid_kernel 163 * 164 * @ns: namespace 165 * @shp: struct to free 166 * 167 * It has to be called with shp and shm_ids.rw_mutex (writer) locked, 168 * but returns with shp unlocked and freed. 169 */ 170 static void shm_destroy(struct ipc_namespace *ns, struct shmid_kernel *shp) 171 { 172 ns->shm_tot -= (shp->shm_segsz + PAGE_SIZE - 1) >> PAGE_SHIFT; 173 shm_rmid(ns, shp); 174 shm_unlock(shp); 175 if (!is_file_hugepages(shp->shm_file)) 176 shmem_lock(shp->shm_file, 0, shp->mlock_user); 177 else if (shp->mlock_user) 178 user_shm_unlock(shp->shm_file->f_path.dentry->d_inode->i_size, 179 shp->mlock_user); 180 fput (shp->shm_file); 181 security_shm_free(shp); 182 ipc_rcu_putref(shp); 183 } 184 185 /* 186 * remove the attach descriptor vma. 187 * free memory for segment if it is marked destroyed. 188 * The descriptor has already been removed from the current->mm->mmap list 189 * and will later be kfree()d. 190 */ 191 static void shm_close(struct vm_area_struct *vma) 192 { 193 struct file * file = vma->vm_file; 194 struct shm_file_data *sfd = shm_file_data(file); 195 struct shmid_kernel *shp; 196 struct ipc_namespace *ns = sfd->ns; 197 198 down_write(&shm_ids(ns).rw_mutex); 199 /* remove from the list of attaches of the shm segment */ 200 shp = shm_lock(ns, sfd->id); 201 BUG_ON(IS_ERR(shp)); 202 shp->shm_lprid = task_tgid_vnr(current); 203 shp->shm_dtim = get_seconds(); 204 shp->shm_nattch--; 205 if(shp->shm_nattch == 0 && 206 shp->shm_perm.mode & SHM_DEST) 207 shm_destroy(ns, shp); 208 else 209 shm_unlock(shp); 210 up_write(&shm_ids(ns).rw_mutex); 211 } 212 213 static int shm_fault(struct vm_area_struct *vma, struct vm_fault *vmf) 214 { 215 struct file *file = vma->vm_file; 216 struct shm_file_data *sfd = shm_file_data(file); 217 218 return sfd->vm_ops->fault(vma, vmf); 219 } 220 221 #ifdef CONFIG_NUMA 222 static int shm_set_policy(struct vm_area_struct *vma, struct mempolicy *new) 223 { 224 struct file *file = vma->vm_file; 225 struct shm_file_data *sfd = shm_file_data(file); 226 int err = 0; 227 if (sfd->vm_ops->set_policy) 228 err = sfd->vm_ops->set_policy(vma, new); 229 return err; 230 } 231 232 static struct mempolicy *shm_get_policy(struct vm_area_struct *vma, 233 unsigned long addr) 234 { 235 struct file *file = vma->vm_file; 236 struct shm_file_data *sfd = shm_file_data(file); 237 struct mempolicy *pol = NULL; 238 239 if (sfd->vm_ops->get_policy) 240 pol = sfd->vm_ops->get_policy(vma, addr); 241 else if (vma->vm_policy) 242 pol = vma->vm_policy; 243 244 return pol; 245 } 246 #endif 247 248 static int shm_mmap(struct file * file, struct vm_area_struct * vma) 249 { 250 struct shm_file_data *sfd = shm_file_data(file); 251 int ret; 252 253 ret = sfd->file->f_op->mmap(sfd->file, vma); 254 if (ret != 0) 255 return ret; 256 sfd->vm_ops = vma->vm_ops; 257 #ifdef CONFIG_MMU 258 BUG_ON(!sfd->vm_ops->fault); 259 #endif 260 vma->vm_ops = &shm_vm_ops; 261 shm_open(vma); 262 263 return ret; 264 } 265 266 static int shm_release(struct inode *ino, struct file *file) 267 { 268 struct shm_file_data *sfd = shm_file_data(file); 269 270 put_ipc_ns(sfd->ns); 271 shm_file_data(file) = NULL; 272 kfree(sfd); 273 return 0; 274 } 275 276 static int shm_fsync(struct file *file, struct dentry *dentry, int datasync) 277 { 278 int (*fsync) (struct file *, struct dentry *, int datasync); 279 struct shm_file_data *sfd = shm_file_data(file); 280 int ret = -EINVAL; 281 282 fsync = sfd->file->f_op->fsync; 283 if (fsync) 284 ret = fsync(sfd->file, sfd->file->f_path.dentry, datasync); 285 return ret; 286 } 287 288 static unsigned long shm_get_unmapped_area(struct file *file, 289 unsigned long addr, unsigned long len, unsigned long pgoff, 290 unsigned long flags) 291 { 292 struct shm_file_data *sfd = shm_file_data(file); 293 return sfd->file->f_op->get_unmapped_area(sfd->file, addr, len, 294 pgoff, flags); 295 } 296 297 static const struct file_operations shm_file_operations = { 298 .mmap = shm_mmap, 299 .fsync = shm_fsync, 300 .release = shm_release, 301 #ifndef CONFIG_MMU 302 .get_unmapped_area = shm_get_unmapped_area, 303 #endif 304 }; 305 306 static const struct file_operations shm_file_operations_huge = { 307 .mmap = shm_mmap, 308 .fsync = shm_fsync, 309 .release = shm_release, 310 .get_unmapped_area = shm_get_unmapped_area, 311 }; 312 313 int is_file_shm_hugepages(struct file *file) 314 { 315 return file->f_op == &shm_file_operations_huge; 316 } 317 318 static const struct vm_operations_struct shm_vm_ops = { 319 .open = shm_open, /* callback for a new vm-area open */ 320 .close = shm_close, /* callback for when the vm-area is released */ 321 .fault = shm_fault, 322 #if defined(CONFIG_NUMA) 323 .set_policy = shm_set_policy, 324 .get_policy = shm_get_policy, 325 #endif 326 }; 327 328 /** 329 * newseg - Create a new shared memory segment 330 * @ns: namespace 331 * @params: ptr to the structure that contains key, size and shmflg 332 * 333 * Called with shm_ids.rw_mutex held as a writer. 334 */ 335 336 static int newseg(struct ipc_namespace *ns, struct ipc_params *params) 337 { 338 key_t key = params->key; 339 int shmflg = params->flg; 340 size_t size = params->u.size; 341 int error; 342 struct shmid_kernel *shp; 343 int numpages = (size + PAGE_SIZE -1) >> PAGE_SHIFT; 344 struct file * file; 345 char name[13]; 346 int id; 347 int acctflag = 0; 348 349 if (size < SHMMIN || size > ns->shm_ctlmax) 350 return -EINVAL; 351 352 if (ns->shm_tot + numpages > ns->shm_ctlall) 353 return -ENOSPC; 354 355 shp = ipc_rcu_alloc(sizeof(*shp)); 356 if (!shp) 357 return -ENOMEM; 358 359 shp->shm_perm.key = key; 360 shp->shm_perm.mode = (shmflg & S_IRWXUGO); 361 shp->mlock_user = NULL; 362 363 shp->shm_perm.security = NULL; 364 error = security_shm_alloc(shp); 365 if (error) { 366 ipc_rcu_putref(shp); 367 return error; 368 } 369 370 sprintf (name, "SYSV%08x", key); 371 if (shmflg & SHM_HUGETLB) { 372 /* hugetlb_file_setup applies strict accounting */ 373 if (shmflg & SHM_NORESERVE) 374 acctflag = VM_NORESERVE; 375 file = hugetlb_file_setup(name, size, acctflag, 376 &shp->mlock_user, HUGETLB_SHMFS_INODE); 377 } else { 378 /* 379 * Do not allow no accounting for OVERCOMMIT_NEVER, even 380 * if it's asked for. 381 */ 382 if ((shmflg & SHM_NORESERVE) && 383 sysctl_overcommit_memory != OVERCOMMIT_NEVER) 384 acctflag = VM_NORESERVE; 385 file = shmem_file_setup(name, size, acctflag); 386 } 387 error = PTR_ERR(file); 388 if (IS_ERR(file)) 389 goto no_file; 390 391 id = ipc_addid(&shm_ids(ns), &shp->shm_perm, ns->shm_ctlmni); 392 if (id < 0) { 393 error = id; 394 goto no_id; 395 } 396 397 shp->shm_cprid = task_tgid_vnr(current); 398 shp->shm_lprid = 0; 399 shp->shm_atim = shp->shm_dtim = 0; 400 shp->shm_ctim = get_seconds(); 401 shp->shm_segsz = size; 402 shp->shm_nattch = 0; 403 shp->shm_file = file; 404 /* 405 * shmid gets reported as "inode#" in /proc/pid/maps. 406 * proc-ps tools use this. Changing this will break them. 407 */ 408 file->f_dentry->d_inode->i_ino = shp->shm_perm.id; 409 410 ns->shm_tot += numpages; 411 error = shp->shm_perm.id; 412 shm_unlock(shp); 413 return error; 414 415 no_id: 416 if (is_file_hugepages(file) && shp->mlock_user) 417 user_shm_unlock(size, shp->mlock_user); 418 fput(file); 419 no_file: 420 security_shm_free(shp); 421 ipc_rcu_putref(shp); 422 return error; 423 } 424 425 /* 426 * Called with shm_ids.rw_mutex and ipcp locked. 427 */ 428 static inline int shm_security(struct kern_ipc_perm *ipcp, int shmflg) 429 { 430 struct shmid_kernel *shp; 431 432 shp = container_of(ipcp, struct shmid_kernel, shm_perm); 433 return security_shm_associate(shp, shmflg); 434 } 435 436 /* 437 * Called with shm_ids.rw_mutex and ipcp locked. 438 */ 439 static inline int shm_more_checks(struct kern_ipc_perm *ipcp, 440 struct ipc_params *params) 441 { 442 struct shmid_kernel *shp; 443 444 shp = container_of(ipcp, struct shmid_kernel, shm_perm); 445 if (shp->shm_segsz < params->u.size) 446 return -EINVAL; 447 448 return 0; 449 } 450 451 SYSCALL_DEFINE3(shmget, key_t, key, size_t, size, int, shmflg) 452 { 453 struct ipc_namespace *ns; 454 struct ipc_ops shm_ops; 455 struct ipc_params shm_params; 456 457 ns = current->nsproxy->ipc_ns; 458 459 shm_ops.getnew = newseg; 460 shm_ops.associate = shm_security; 461 shm_ops.more_checks = shm_more_checks; 462 463 shm_params.key = key; 464 shm_params.flg = shmflg; 465 shm_params.u.size = size; 466 467 return ipcget(ns, &shm_ids(ns), &shm_ops, &shm_params); 468 } 469 470 static inline unsigned long copy_shmid_to_user(void __user *buf, struct shmid64_ds *in, int version) 471 { 472 switch(version) { 473 case IPC_64: 474 return copy_to_user(buf, in, sizeof(*in)); 475 case IPC_OLD: 476 { 477 struct shmid_ds out; 478 479 ipc64_perm_to_ipc_perm(&in->shm_perm, &out.shm_perm); 480 out.shm_segsz = in->shm_segsz; 481 out.shm_atime = in->shm_atime; 482 out.shm_dtime = in->shm_dtime; 483 out.shm_ctime = in->shm_ctime; 484 out.shm_cpid = in->shm_cpid; 485 out.shm_lpid = in->shm_lpid; 486 out.shm_nattch = in->shm_nattch; 487 488 return copy_to_user(buf, &out, sizeof(out)); 489 } 490 default: 491 return -EINVAL; 492 } 493 } 494 495 static inline unsigned long 496 copy_shmid_from_user(struct shmid64_ds *out, void __user *buf, int version) 497 { 498 switch(version) { 499 case IPC_64: 500 if (copy_from_user(out, buf, sizeof(*out))) 501 return -EFAULT; 502 return 0; 503 case IPC_OLD: 504 { 505 struct shmid_ds tbuf_old; 506 507 if (copy_from_user(&tbuf_old, buf, sizeof(tbuf_old))) 508 return -EFAULT; 509 510 out->shm_perm.uid = tbuf_old.shm_perm.uid; 511 out->shm_perm.gid = tbuf_old.shm_perm.gid; 512 out->shm_perm.mode = tbuf_old.shm_perm.mode; 513 514 return 0; 515 } 516 default: 517 return -EINVAL; 518 } 519 } 520 521 static inline unsigned long copy_shminfo_to_user(void __user *buf, struct shminfo64 *in, int version) 522 { 523 switch(version) { 524 case IPC_64: 525 return copy_to_user(buf, in, sizeof(*in)); 526 case IPC_OLD: 527 { 528 struct shminfo out; 529 530 if(in->shmmax > INT_MAX) 531 out.shmmax = INT_MAX; 532 else 533 out.shmmax = (int)in->shmmax; 534 535 out.shmmin = in->shmmin; 536 out.shmmni = in->shmmni; 537 out.shmseg = in->shmseg; 538 out.shmall = in->shmall; 539 540 return copy_to_user(buf, &out, sizeof(out)); 541 } 542 default: 543 return -EINVAL; 544 } 545 } 546 547 /* 548 * Called with shm_ids.rw_mutex held as a reader 549 */ 550 static void shm_get_stat(struct ipc_namespace *ns, unsigned long *rss, 551 unsigned long *swp) 552 { 553 int next_id; 554 int total, in_use; 555 556 *rss = 0; 557 *swp = 0; 558 559 in_use = shm_ids(ns).in_use; 560 561 for (total = 0, next_id = 0; total < in_use; next_id++) { 562 struct kern_ipc_perm *ipc; 563 struct shmid_kernel *shp; 564 struct inode *inode; 565 566 ipc = idr_find(&shm_ids(ns).ipcs_idr, next_id); 567 if (ipc == NULL) 568 continue; 569 shp = container_of(ipc, struct shmid_kernel, shm_perm); 570 571 inode = shp->shm_file->f_path.dentry->d_inode; 572 573 if (is_file_hugepages(shp->shm_file)) { 574 struct address_space *mapping = inode->i_mapping; 575 struct hstate *h = hstate_file(shp->shm_file); 576 *rss += pages_per_huge_page(h) * mapping->nrpages; 577 } else { 578 #ifdef CONFIG_SHMEM 579 struct shmem_inode_info *info = SHMEM_I(inode); 580 spin_lock(&info->lock); 581 *rss += inode->i_mapping->nrpages; 582 *swp += info->swapped; 583 spin_unlock(&info->lock); 584 #else 585 *rss += inode->i_mapping->nrpages; 586 #endif 587 } 588 589 total++; 590 } 591 } 592 593 /* 594 * This function handles some shmctl commands which require the rw_mutex 595 * to be held in write mode. 596 * NOTE: no locks must be held, the rw_mutex is taken inside this function. 597 */ 598 static int shmctl_down(struct ipc_namespace *ns, int shmid, int cmd, 599 struct shmid_ds __user *buf, int version) 600 { 601 struct kern_ipc_perm *ipcp; 602 struct shmid64_ds shmid64; 603 struct shmid_kernel *shp; 604 int err; 605 606 if (cmd == IPC_SET) { 607 if (copy_shmid_from_user(&shmid64, buf, version)) 608 return -EFAULT; 609 } 610 611 ipcp = ipcctl_pre_down(&shm_ids(ns), shmid, cmd, &shmid64.shm_perm, 0); 612 if (IS_ERR(ipcp)) 613 return PTR_ERR(ipcp); 614 615 shp = container_of(ipcp, struct shmid_kernel, shm_perm); 616 617 err = security_shm_shmctl(shp, cmd); 618 if (err) 619 goto out_unlock; 620 switch (cmd) { 621 case IPC_RMID: 622 do_shm_rmid(ns, ipcp); 623 goto out_up; 624 case IPC_SET: 625 ipc_update_perm(&shmid64.shm_perm, ipcp); 626 shp->shm_ctim = get_seconds(); 627 break; 628 default: 629 err = -EINVAL; 630 } 631 out_unlock: 632 shm_unlock(shp); 633 out_up: 634 up_write(&shm_ids(ns).rw_mutex); 635 return err; 636 } 637 638 SYSCALL_DEFINE3(shmctl, int, shmid, int, cmd, struct shmid_ds __user *, buf) 639 { 640 struct shmid_kernel *shp; 641 int err, version; 642 struct ipc_namespace *ns; 643 644 if (cmd < 0 || shmid < 0) { 645 err = -EINVAL; 646 goto out; 647 } 648 649 version = ipc_parse_version(&cmd); 650 ns = current->nsproxy->ipc_ns; 651 652 switch (cmd) { /* replace with proc interface ? */ 653 case IPC_INFO: 654 { 655 struct shminfo64 shminfo; 656 657 err = security_shm_shmctl(NULL, cmd); 658 if (err) 659 return err; 660 661 memset(&shminfo, 0, sizeof(shminfo)); 662 shminfo.shmmni = shminfo.shmseg = ns->shm_ctlmni; 663 shminfo.shmmax = ns->shm_ctlmax; 664 shminfo.shmall = ns->shm_ctlall; 665 666 shminfo.shmmin = SHMMIN; 667 if(copy_shminfo_to_user (buf, &shminfo, version)) 668 return -EFAULT; 669 670 down_read(&shm_ids(ns).rw_mutex); 671 err = ipc_get_maxid(&shm_ids(ns)); 672 up_read(&shm_ids(ns).rw_mutex); 673 674 if(err<0) 675 err = 0; 676 goto out; 677 } 678 case SHM_INFO: 679 { 680 struct shm_info shm_info; 681 682 err = security_shm_shmctl(NULL, cmd); 683 if (err) 684 return err; 685 686 memset(&shm_info, 0, sizeof(shm_info)); 687 down_read(&shm_ids(ns).rw_mutex); 688 shm_info.used_ids = shm_ids(ns).in_use; 689 shm_get_stat (ns, &shm_info.shm_rss, &shm_info.shm_swp); 690 shm_info.shm_tot = ns->shm_tot; 691 shm_info.swap_attempts = 0; 692 shm_info.swap_successes = 0; 693 err = ipc_get_maxid(&shm_ids(ns)); 694 up_read(&shm_ids(ns).rw_mutex); 695 if (copy_to_user(buf, &shm_info, sizeof(shm_info))) { 696 err = -EFAULT; 697 goto out; 698 } 699 700 err = err < 0 ? 0 : err; 701 goto out; 702 } 703 case SHM_STAT: 704 case IPC_STAT: 705 { 706 struct shmid64_ds tbuf; 707 int result; 708 709 if (cmd == SHM_STAT) { 710 shp = shm_lock(ns, shmid); 711 if (IS_ERR(shp)) { 712 err = PTR_ERR(shp); 713 goto out; 714 } 715 result = shp->shm_perm.id; 716 } else { 717 shp = shm_lock_check(ns, shmid); 718 if (IS_ERR(shp)) { 719 err = PTR_ERR(shp); 720 goto out; 721 } 722 result = 0; 723 } 724 err = -EACCES; 725 if (ipcperms (&shp->shm_perm, S_IRUGO)) 726 goto out_unlock; 727 err = security_shm_shmctl(shp, cmd); 728 if (err) 729 goto out_unlock; 730 memset(&tbuf, 0, sizeof(tbuf)); 731 kernel_to_ipc64_perm(&shp->shm_perm, &tbuf.shm_perm); 732 tbuf.shm_segsz = shp->shm_segsz; 733 tbuf.shm_atime = shp->shm_atim; 734 tbuf.shm_dtime = shp->shm_dtim; 735 tbuf.shm_ctime = shp->shm_ctim; 736 tbuf.shm_cpid = shp->shm_cprid; 737 tbuf.shm_lpid = shp->shm_lprid; 738 tbuf.shm_nattch = shp->shm_nattch; 739 shm_unlock(shp); 740 if(copy_shmid_to_user (buf, &tbuf, version)) 741 err = -EFAULT; 742 else 743 err = result; 744 goto out; 745 } 746 case SHM_LOCK: 747 case SHM_UNLOCK: 748 { 749 struct file *uninitialized_var(shm_file); 750 751 lru_add_drain_all(); /* drain pagevecs to lru lists */ 752 753 shp = shm_lock_check(ns, shmid); 754 if (IS_ERR(shp)) { 755 err = PTR_ERR(shp); 756 goto out; 757 } 758 759 audit_ipc_obj(&(shp->shm_perm)); 760 761 if (!capable(CAP_IPC_LOCK)) { 762 uid_t euid = current_euid(); 763 err = -EPERM; 764 if (euid != shp->shm_perm.uid && 765 euid != shp->shm_perm.cuid) 766 goto out_unlock; 767 if (cmd == SHM_LOCK && 768 !current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur) 769 goto out_unlock; 770 } 771 772 err = security_shm_shmctl(shp, cmd); 773 if (err) 774 goto out_unlock; 775 776 if(cmd==SHM_LOCK) { 777 struct user_struct *user = current_user(); 778 if (!is_file_hugepages(shp->shm_file)) { 779 err = shmem_lock(shp->shm_file, 1, user); 780 if (!err && !(shp->shm_perm.mode & SHM_LOCKED)){ 781 shp->shm_perm.mode |= SHM_LOCKED; 782 shp->mlock_user = user; 783 } 784 } 785 } else if (!is_file_hugepages(shp->shm_file)) { 786 shmem_lock(shp->shm_file, 0, shp->mlock_user); 787 shp->shm_perm.mode &= ~SHM_LOCKED; 788 shp->mlock_user = NULL; 789 } 790 shm_unlock(shp); 791 goto out; 792 } 793 case IPC_RMID: 794 case IPC_SET: 795 err = shmctl_down(ns, shmid, cmd, buf, version); 796 return err; 797 default: 798 return -EINVAL; 799 } 800 801 out_unlock: 802 shm_unlock(shp); 803 out: 804 return err; 805 } 806 807 /* 808 * Fix shmaddr, allocate descriptor, map shm, add attach descriptor to lists. 809 * 810 * NOTE! Despite the name, this is NOT a direct system call entrypoint. The 811 * "raddr" thing points to kernel space, and there has to be a wrapper around 812 * this. 813 */ 814 long do_shmat(int shmid, char __user *shmaddr, int shmflg, ulong *raddr) 815 { 816 struct shmid_kernel *shp; 817 unsigned long addr; 818 unsigned long size; 819 struct file * file; 820 int err; 821 unsigned long flags; 822 unsigned long prot; 823 int acc_mode; 824 unsigned long user_addr; 825 struct ipc_namespace *ns; 826 struct shm_file_data *sfd; 827 struct path path; 828 fmode_t f_mode; 829 830 err = -EINVAL; 831 if (shmid < 0) 832 goto out; 833 else if ((addr = (ulong)shmaddr)) { 834 if (addr & (SHMLBA-1)) { 835 if (shmflg & SHM_RND) 836 addr &= ~(SHMLBA-1); /* round down */ 837 else 838 #ifndef __ARCH_FORCE_SHMLBA 839 if (addr & ~PAGE_MASK) 840 #endif 841 goto out; 842 } 843 flags = MAP_SHARED | MAP_FIXED; 844 } else { 845 if ((shmflg & SHM_REMAP)) 846 goto out; 847 848 flags = MAP_SHARED; 849 } 850 851 if (shmflg & SHM_RDONLY) { 852 prot = PROT_READ; 853 acc_mode = S_IRUGO; 854 f_mode = FMODE_READ; 855 } else { 856 prot = PROT_READ | PROT_WRITE; 857 acc_mode = S_IRUGO | S_IWUGO; 858 f_mode = FMODE_READ | FMODE_WRITE; 859 } 860 if (shmflg & SHM_EXEC) { 861 prot |= PROT_EXEC; 862 acc_mode |= S_IXUGO; 863 } 864 865 /* 866 * We cannot rely on the fs check since SYSV IPC does have an 867 * additional creator id... 868 */ 869 ns = current->nsproxy->ipc_ns; 870 shp = shm_lock_check(ns, shmid); 871 if (IS_ERR(shp)) { 872 err = PTR_ERR(shp); 873 goto out; 874 } 875 876 err = -EACCES; 877 if (ipcperms(&shp->shm_perm, acc_mode)) 878 goto out_unlock; 879 880 err = security_shm_shmat(shp, shmaddr, shmflg); 881 if (err) 882 goto out_unlock; 883 884 path = shp->shm_file->f_path; 885 path_get(&path); 886 shp->shm_nattch++; 887 size = i_size_read(path.dentry->d_inode); 888 shm_unlock(shp); 889 890 err = -ENOMEM; 891 sfd = kzalloc(sizeof(*sfd), GFP_KERNEL); 892 if (!sfd) 893 goto out_put_dentry; 894 895 file = alloc_file(&path, f_mode, 896 is_file_hugepages(shp->shm_file) ? 897 &shm_file_operations_huge : 898 &shm_file_operations); 899 if (!file) 900 goto out_free; 901 902 file->private_data = sfd; 903 file->f_mapping = shp->shm_file->f_mapping; 904 sfd->id = shp->shm_perm.id; 905 sfd->ns = get_ipc_ns(ns); 906 sfd->file = shp->shm_file; 907 sfd->vm_ops = NULL; 908 909 down_write(¤t->mm->mmap_sem); 910 if (addr && !(shmflg & SHM_REMAP)) { 911 err = -EINVAL; 912 if (find_vma_intersection(current->mm, addr, addr + size)) 913 goto invalid; 914 /* 915 * If shm segment goes below stack, make sure there is some 916 * space left for the stack to grow (at least 4 pages). 917 */ 918 if (addr < current->mm->start_stack && 919 addr > current->mm->start_stack - size - PAGE_SIZE * 5) 920 goto invalid; 921 } 922 923 user_addr = do_mmap (file, addr, size, prot, flags, 0); 924 *raddr = user_addr; 925 err = 0; 926 if (IS_ERR_VALUE(user_addr)) 927 err = (long)user_addr; 928 invalid: 929 up_write(¤t->mm->mmap_sem); 930 931 fput(file); 932 933 out_nattch: 934 down_write(&shm_ids(ns).rw_mutex); 935 shp = shm_lock(ns, shmid); 936 BUG_ON(IS_ERR(shp)); 937 shp->shm_nattch--; 938 if(shp->shm_nattch == 0 && 939 shp->shm_perm.mode & SHM_DEST) 940 shm_destroy(ns, shp); 941 else 942 shm_unlock(shp); 943 up_write(&shm_ids(ns).rw_mutex); 944 945 out: 946 return err; 947 948 out_unlock: 949 shm_unlock(shp); 950 goto out; 951 952 out_free: 953 kfree(sfd); 954 out_put_dentry: 955 path_put(&path); 956 goto out_nattch; 957 } 958 959 SYSCALL_DEFINE3(shmat, int, shmid, char __user *, shmaddr, int, shmflg) 960 { 961 unsigned long ret; 962 long err; 963 964 err = do_shmat(shmid, shmaddr, shmflg, &ret); 965 if (err) 966 return err; 967 force_successful_syscall_return(); 968 return (long)ret; 969 } 970 971 /* 972 * detach and kill segment if marked destroyed. 973 * The work is done in shm_close. 974 */ 975 SYSCALL_DEFINE1(shmdt, char __user *, shmaddr) 976 { 977 struct mm_struct *mm = current->mm; 978 struct vm_area_struct *vma; 979 unsigned long addr = (unsigned long)shmaddr; 980 int retval = -EINVAL; 981 #ifdef CONFIG_MMU 982 loff_t size = 0; 983 struct vm_area_struct *next; 984 #endif 985 986 if (addr & ~PAGE_MASK) 987 return retval; 988 989 down_write(&mm->mmap_sem); 990 991 /* 992 * This function tries to be smart and unmap shm segments that 993 * were modified by partial mlock or munmap calls: 994 * - It first determines the size of the shm segment that should be 995 * unmapped: It searches for a vma that is backed by shm and that 996 * started at address shmaddr. It records it's size and then unmaps 997 * it. 998 * - Then it unmaps all shm vmas that started at shmaddr and that 999 * are within the initially determined size. 1000 * Errors from do_munmap are ignored: the function only fails if 1001 * it's called with invalid parameters or if it's called to unmap 1002 * a part of a vma. Both calls in this function are for full vmas, 1003 * the parameters are directly copied from the vma itself and always 1004 * valid - therefore do_munmap cannot fail. (famous last words?) 1005 */ 1006 /* 1007 * If it had been mremap()'d, the starting address would not 1008 * match the usual checks anyway. So assume all vma's are 1009 * above the starting address given. 1010 */ 1011 vma = find_vma(mm, addr); 1012 1013 #ifdef CONFIG_MMU 1014 while (vma) { 1015 next = vma->vm_next; 1016 1017 /* 1018 * Check if the starting address would match, i.e. it's 1019 * a fragment created by mprotect() and/or munmap(), or it 1020 * otherwise it starts at this address with no hassles. 1021 */ 1022 if ((vma->vm_ops == &shm_vm_ops) && 1023 (vma->vm_start - addr)/PAGE_SIZE == vma->vm_pgoff) { 1024 1025 1026 size = vma->vm_file->f_path.dentry->d_inode->i_size; 1027 do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start); 1028 /* 1029 * We discovered the size of the shm segment, so 1030 * break out of here and fall through to the next 1031 * loop that uses the size information to stop 1032 * searching for matching vma's. 1033 */ 1034 retval = 0; 1035 vma = next; 1036 break; 1037 } 1038 vma = next; 1039 } 1040 1041 /* 1042 * We need look no further than the maximum address a fragment 1043 * could possibly have landed at. Also cast things to loff_t to 1044 * prevent overflows and make comparisions vs. equal-width types. 1045 */ 1046 size = PAGE_ALIGN(size); 1047 while (vma && (loff_t)(vma->vm_end - addr) <= size) { 1048 next = vma->vm_next; 1049 1050 /* finding a matching vma now does not alter retval */ 1051 if ((vma->vm_ops == &shm_vm_ops) && 1052 (vma->vm_start - addr)/PAGE_SIZE == vma->vm_pgoff) 1053 1054 do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start); 1055 vma = next; 1056 } 1057 1058 #else /* CONFIG_MMU */ 1059 /* under NOMMU conditions, the exact address to be destroyed must be 1060 * given */ 1061 retval = -EINVAL; 1062 if (vma->vm_start == addr && vma->vm_ops == &shm_vm_ops) { 1063 do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start); 1064 retval = 0; 1065 } 1066 1067 #endif 1068 1069 up_write(&mm->mmap_sem); 1070 return retval; 1071 } 1072 1073 #ifdef CONFIG_PROC_FS 1074 static int sysvipc_shm_proc_show(struct seq_file *s, void *it) 1075 { 1076 struct shmid_kernel *shp = it; 1077 1078 #if BITS_PER_LONG <= 32 1079 #define SIZE_SPEC "%10lu" 1080 #else 1081 #define SIZE_SPEC "%21lu" 1082 #endif 1083 1084 return seq_printf(s, 1085 "%10d %10d %4o " SIZE_SPEC " %5u %5u " 1086 "%5lu %5u %5u %5u %5u %10lu %10lu %10lu\n", 1087 shp->shm_perm.key, 1088 shp->shm_perm.id, 1089 shp->shm_perm.mode, 1090 shp->shm_segsz, 1091 shp->shm_cprid, 1092 shp->shm_lprid, 1093 shp->shm_nattch, 1094 shp->shm_perm.uid, 1095 shp->shm_perm.gid, 1096 shp->shm_perm.cuid, 1097 shp->shm_perm.cgid, 1098 shp->shm_atim, 1099 shp->shm_dtim, 1100 shp->shm_ctim); 1101 } 1102 #endif 1103