ipc/shm.c

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This source file includes following definitions.
shm_init_ns
do_shm_rmid
shm_exit_ns
ipc_ns_init
shm_init
shm_obtain_object
shm_obtain_object_check
shm_lock
shm_lock_by_ptr
shm_rcu_free
shm_rmid
__shm_open
shm_open
shm_destroy
shm_may_destroy
shm_close
shm_try_destroy_orphaned
shm_destroy_orphaned
exit_shm
shm_fault
shm_split
shm_pagesize
shm_set_policy
shm_get_policy
shm_mmap
shm_release
shm_fsync
shm_fallocate
shm_get_unmapped_area
is_file_shm_hugepages
newseg
shm_more_checks
ksys_shmget
SYSCALL_DEFINE3
copy_shmid_to_user
copy_shmid_from_user
copy_shminfo_to_user
shm_add_rss_swap
shm_get_stat
shmctl_down
shmctl_ipc_info
shmctl_shm_info
shmctl_stat
shmctl_do_lock
ksys_shmctl
SYSCALL_DEFINE3
ksys_old_shmctl
SYSCALL_DEFINE3
copy_compat_shminfo_to_user
put_compat_shm_info
copy_compat_shmid_to_user
copy_compat_shmid_from_user
compat_ksys_shmctl
COMPAT_SYSCALL_DEFINE3
compat_ksys_old_shmctl
COMPAT_SYSCALL_DEFINE3
do_shmat
SYSCALL_DEFINE3
COMPAT_SYSCALL_DEFINE3
ksys_shmdt
SYSCALL_DEFINE1
sysvipc_shm_proc_show
   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * linux/ipc/shm.c
   4  * Copyright (C) 1992, 1993 Krishna Balasubramanian
   5  *       Many improvements/fixes by Bruno Haible.
   6  * Replaced `struct shm_desc' by `struct vm_area_struct', July 1994.
   7  * Fixed the shm swap deallocation (shm_unuse()), August 1998 Andrea Arcangeli.
   8  *
   9  * /proc/sysvipc/shm support (c) 1999 Dragos Acostachioaie <dragos@iname.com>
  10  * BIGMEM support, Andrea Arcangeli <andrea@suse.de>
  11  * SMP thread shm, Jean-Luc Boyard <jean-luc.boyard@siemens.fr>
  12  * HIGHMEM support, Ingo Molnar <mingo@redhat.com>
  13  * Make shmmax, shmall, shmmni sysctl'able, Christoph Rohland <cr@sap.com>
  14  * Shared /dev/zero support, Kanoj Sarcar <kanoj@sgi.com>
  15  * Move the mm functionality over to mm/shmem.c, Christoph Rohland <cr@sap.com>
  16  *
  17  * support for audit of ipc object properties and permission changes
  18  * Dustin Kirkland <dustin.kirkland@us.ibm.com>
  19  *
  20  * namespaces support
  21  * OpenVZ, SWsoft Inc.
  22  * Pavel Emelianov <xemul@openvz.org>
  23  *
  24  * Better ipc lock (kern_ipc_perm.lock) handling
  25  * Davidlohr Bueso <davidlohr.bueso@hp.com>, June 2013.
  26  */
  27 
  28 #include <linux/slab.h>
  29 #include <linux/mm.h>
  30 #include <linux/hugetlb.h>
  31 #include <linux/shm.h>
  32 #include <linux/init.h>
  33 #include <linux/file.h>
  34 #include <linux/mman.h>
  35 #include <linux/shmem_fs.h>
  36 #include <linux/security.h>
  37 #include <linux/syscalls.h>
  38 #include <linux/audit.h>
  39 #include <linux/capability.h>
  40 #include <linux/ptrace.h>
  41 #include <linux/seq_file.h>
  42 #include <linux/rwsem.h>
  43 #include <linux/nsproxy.h>
  44 #include <linux/mount.h>
  45 #include <linux/ipc_namespace.h>
  46 #include <linux/rhashtable.h>
  47 
  48 #include <linux/uaccess.h>
  49 
  50 #include "util.h"
  51 
  52 struct shmid_kernel /* private to the kernel */
  53 {
  54         struct kern_ipc_perm    shm_perm;
  55         struct file             *shm_file;
  56         unsigned long           shm_nattch;
  57         unsigned long           shm_segsz;
  58         time64_t                shm_atim;
  59         time64_t                shm_dtim;
  60         time64_t                shm_ctim;
  61         struct pid              *shm_cprid;
  62         struct pid              *shm_lprid;
  63         struct user_struct      *mlock_user;
  64 
  65         /* The task created the shm object.  NULL if the task is dead. */
  66         struct task_struct      *shm_creator;
  67         struct list_head        shm_clist;      /* list by creator */
  68 } __randomize_layout;
  69 
  70 /* shm_mode upper byte flags */
  71 #define SHM_DEST        01000   /* segment will be destroyed on last detach */
  72 #define SHM_LOCKED      02000   /* segment will not be swapped */
  73 
  74 struct shm_file_data {
  75         int id;
  76         struct ipc_namespace *ns;
  77         struct file *file;
  78         const struct vm_operations_struct *vm_ops;
  79 };
  80 
  81 #define shm_file_data(file) (*((struct shm_file_data **)&(file)->private_data))
  82 
  83 static const struct file_operations shm_file_operations;
  84 static const struct vm_operations_struct shm_vm_ops;
  85 
  86 #define shm_ids(ns)     ((ns)->ids[IPC_SHM_IDS])
  87 
  88 #define shm_unlock(shp)                 \
  89         ipc_unlock(&(shp)->shm_perm)
  90 
  91 static int newseg(struct ipc_namespace *, struct ipc_params *);
  92 static void shm_open(struct vm_area_struct *vma);
  93 static void shm_close(struct vm_area_struct *vma);
  94 static void shm_destroy(struct ipc_namespace *ns, struct shmid_kernel *shp);
  95 #ifdef CONFIG_PROC_FS
  96 static int sysvipc_shm_proc_show(struct seq_file *s, void *it);
  97 #endif
  98 
  99 void shm_init_ns(struct ipc_namespace *ns)
 100 {
 101         ns->shm_ctlmax = SHMMAX;
 102         ns->shm_ctlall = SHMALL;
 103         ns->shm_ctlmni = SHMMNI;
 104         ns->shm_rmid_forced = 0;
 105         ns->shm_tot = 0;
 106         ipc_init_ids(&shm_ids(ns));
 107 }
 108 
 109 /*
 110  * Called with shm_ids.rwsem (writer) and the shp structure locked.
 111  * Only shm_ids.rwsem remains locked on exit.
 112  */
 113 static void do_shm_rmid(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp)
 114 {
 115         struct shmid_kernel *shp;
 116 
 117         shp = container_of(ipcp, struct shmid_kernel, shm_perm);
 118 
 119         if (shp->shm_nattch) {
 120                 shp->shm_perm.mode |= SHM_DEST;
 121                 /* Do not find it any more */
 122                 ipc_set_key_private(&shm_ids(ns), &shp->shm_perm);
 123                 shm_unlock(shp);
 124         } else
 125                 shm_destroy(ns, shp);
 126 }
 127 
 128 #ifdef CONFIG_IPC_NS
 129 void shm_exit_ns(struct ipc_namespace *ns)
 130 {
 131         free_ipcs(ns, &shm_ids(ns), do_shm_rmid);
 132         idr_destroy(&ns->ids[IPC_SHM_IDS].ipcs_idr);
 133         rhashtable_destroy(&ns->ids[IPC_SHM_IDS].key_ht);
 134 }
 135 #endif
 136 
 137 static int __init ipc_ns_init(void)
 138 {
 139         shm_init_ns(&init_ipc_ns);
 140         return 0;
 141 }
 142 
 143 pure_initcall(ipc_ns_init);
 144 
 145 void __init shm_init(void)
 146 {
 147         ipc_init_proc_interface("sysvipc/shm",
 148 #if BITS_PER_LONG <= 32
 149                                 "       key      shmid perms       size  cpid  lpid nattch   uid   gid  cuid  cgid      atime      dtime      ctime        rss       swap\n",
 150 #else
 151                                 "       key      shmid perms                  size  cpid  lpid nattch   uid   gid  cuid  cgid      atime      dtime      ctime                   rss                  swap\n",
 152 #endif
 153                                 IPC_SHM_IDS, sysvipc_shm_proc_show);
 154 }
 155 
 156 static inline struct shmid_kernel *shm_obtain_object(struct ipc_namespace *ns, int id)
 157 {
 158         struct kern_ipc_perm *ipcp = ipc_obtain_object_idr(&shm_ids(ns), id);
 159 
 160         if (IS_ERR(ipcp))
 161                 return ERR_CAST(ipcp);
 162 
 163         return container_of(ipcp, struct shmid_kernel, shm_perm);
 164 }
 165 
 166 static inline struct shmid_kernel *shm_obtain_object_check(struct ipc_namespace *ns, int id)
 167 {
 168         struct kern_ipc_perm *ipcp = ipc_obtain_object_check(&shm_ids(ns), id);
 169 
 170         if (IS_ERR(ipcp))
 171                 return ERR_CAST(ipcp);
 172 
 173         return container_of(ipcp, struct shmid_kernel, shm_perm);
 174 }
 175 
 176 /*
 177  * shm_lock_(check_) routines are called in the paths where the rwsem
 178  * is not necessarily held.
 179  */
 180 static inline struct shmid_kernel *shm_lock(struct ipc_namespace *ns, int id)
 181 {
 182         struct kern_ipc_perm *ipcp;
 183 
 184         rcu_read_lock();
 185         ipcp = ipc_obtain_object_idr(&shm_ids(ns), id);
 186         if (IS_ERR(ipcp))
 187                 goto err;
 188 
 189         ipc_lock_object(ipcp);
 190         /*
 191          * ipc_rmid() may have already freed the ID while ipc_lock_object()
 192          * was spinning: here verify that the structure is still valid.
 193          * Upon races with RMID, return -EIDRM, thus indicating that
 194          * the ID points to a removed identifier.
 195          */
 196         if (ipc_valid_object(ipcp)) {
 197                 /* return a locked ipc object upon success */
 198                 return container_of(ipcp, struct shmid_kernel, shm_perm);
 199         }
 200 
 201         ipc_unlock_object(ipcp);
 202         ipcp = ERR_PTR(-EIDRM);
 203 err:
 204         rcu_read_unlock();
 205         /*
 206          * Callers of shm_lock() must validate the status of the returned ipc
 207          * object pointer and error out as appropriate.
 208          */
 209         return ERR_CAST(ipcp);
 210 }
 211 
 212 static inline void shm_lock_by_ptr(struct shmid_kernel *ipcp)
 213 {
 214         rcu_read_lock();
 215         ipc_lock_object(&ipcp->shm_perm);
 216 }
 217 
 218 static void shm_rcu_free(struct rcu_head *head)
 219 {
 220         struct kern_ipc_perm *ptr = container_of(head, struct kern_ipc_perm,
 221                                                         rcu);
 222         struct shmid_kernel *shp = container_of(ptr, struct shmid_kernel,
 223                                                         shm_perm);
 224         security_shm_free(&shp->shm_perm);
 225         kvfree(shp);
 226 }
 227 
 228 static inline void shm_rmid(struct ipc_namespace *ns, struct shmid_kernel *s)
 229 {
 230         list_del(&s->shm_clist);
 231         ipc_rmid(&shm_ids(ns), &s->shm_perm);
 232 }
 233 
 234 
 235 static int __shm_open(struct vm_area_struct *vma)
 236 {
 237         struct file *file = vma->vm_file;
 238         struct shm_file_data *sfd = shm_file_data(file);
 239         struct shmid_kernel *shp;
 240 
 241         shp = shm_lock(sfd->ns, sfd->id);
 242 
 243         if (IS_ERR(shp))
 244                 return PTR_ERR(shp);
 245 
 246         if (shp->shm_file != sfd->file) {
 247                 /* ID was reused */
 248                 shm_unlock(shp);
 249                 return -EINVAL;
 250         }
 251 
 252         shp->shm_atim = ktime_get_real_seconds();
 253         ipc_update_pid(&shp->shm_lprid, task_tgid(current));
 254         shp->shm_nattch++;
 255         shm_unlock(shp);
 256         return 0;
 257 }
 258 
 259 /* This is called by fork, once for every shm attach. */
 260 static void shm_open(struct vm_area_struct *vma)
 261 {
 262         int err = __shm_open(vma);
 263         /*
 264          * We raced in the idr lookup or with shm_destroy().
 265          * Either way, the ID is busted.
 266          */
 267         WARN_ON_ONCE(err);
 268 }
 269 
 270 /*
 271  * shm_destroy - free the struct shmid_kernel
 272  *
 273  * @ns: namespace
 274  * @shp: struct to free
 275  *
 276  * It has to be called with shp and shm_ids.rwsem (writer) locked,
 277  * but returns with shp unlocked and freed.
 278  */
 279 static void shm_destroy(struct ipc_namespace *ns, struct shmid_kernel *shp)
 280 {
 281         struct file *shm_file;
 282 
 283         shm_file = shp->shm_file;
 284         shp->shm_file = NULL;
 285         ns->shm_tot -= (shp->shm_segsz + PAGE_SIZE - 1) >> PAGE_SHIFT;
 286         shm_rmid(ns, shp);
 287         shm_unlock(shp);
 288         if (!is_file_hugepages(shm_file))
 289                 shmem_lock(shm_file, 0, shp->mlock_user);
 290         else if (shp->mlock_user)
 291                 user_shm_unlock(i_size_read(file_inode(shm_file)),
 292                                 shp->mlock_user);
 293         fput(shm_file);
 294         ipc_update_pid(&shp->shm_cprid, NULL);
 295         ipc_update_pid(&shp->shm_lprid, NULL);
 296         ipc_rcu_putref(&shp->shm_perm, shm_rcu_free);
 297 }
 298 
 299 /*
 300  * shm_may_destroy - identifies whether shm segment should be destroyed now
 301  *
 302  * Returns true if and only if there are no active users of the segment and
 303  * one of the following is true:
 304  *
 305  * 1) shmctl(id, IPC_RMID, NULL) was called for this shp
 306  *
 307  * 2) sysctl kernel.shm_rmid_forced is set to 1.
 308  */
 309 static bool shm_may_destroy(struct ipc_namespace *ns, struct shmid_kernel *shp)
 310 {
 311         return (shp->shm_nattch == 0) &&
 312                (ns->shm_rmid_forced ||
 313                 (shp->shm_perm.mode & SHM_DEST));
 314 }
 315 
 316 /*
 317  * remove the attach descriptor vma.
 318  * free memory for segment if it is marked destroyed.
 319  * The descriptor has already been removed from the current->mm->mmap list
 320  * and will later be kfree()d.
 321  */
 322 static void shm_close(struct vm_area_struct *vma)
 323 {
 324         struct file *file = vma->vm_file;
 325         struct shm_file_data *sfd = shm_file_data(file);
 326         struct shmid_kernel *shp;
 327         struct ipc_namespace *ns = sfd->ns;
 328 
 329         down_write(&shm_ids(ns).rwsem);
 330         /* remove from the list of attaches of the shm segment */
 331         shp = shm_lock(ns, sfd->id);
 332 
 333         /*
 334          * We raced in the idr lookup or with shm_destroy().
 335          * Either way, the ID is busted.
 336          */
 337         if (WARN_ON_ONCE(IS_ERR(shp)))
 338                 goto done; /* no-op */
 339 
 340         ipc_update_pid(&shp->shm_lprid, task_tgid(current));
 341         shp->shm_dtim = ktime_get_real_seconds();
 342         shp->shm_nattch--;
 343         if (shm_may_destroy(ns, shp))
 344                 shm_destroy(ns, shp);
 345         else
 346                 shm_unlock(shp);
 347 done:
 348         up_write(&shm_ids(ns).rwsem);
 349 }
 350 
 351 /* Called with ns->shm_ids(ns).rwsem locked */
 352 static int shm_try_destroy_orphaned(int id, void *p, void *data)
 353 {
 354         struct ipc_namespace *ns = data;
 355         struct kern_ipc_perm *ipcp = p;
 356         struct shmid_kernel *shp = container_of(ipcp, struct shmid_kernel, shm_perm);
 357 
 358         /*
 359          * We want to destroy segments without users and with already
 360          * exit'ed originating process.
 361          *
 362          * As shp->* are changed under rwsem, it's safe to skip shp locking.
 363          */
 364         if (shp->shm_creator != NULL)
 365                 return 0;
 366 
 367         if (shm_may_destroy(ns, shp)) {
 368                 shm_lock_by_ptr(shp);
 369                 shm_destroy(ns, shp);
 370         }
 371         return 0;
 372 }
 373 
 374 void shm_destroy_orphaned(struct ipc_namespace *ns)
 375 {
 376         down_write(&shm_ids(ns).rwsem);
 377         if (shm_ids(ns).in_use)
 378                 idr_for_each(&shm_ids(ns).ipcs_idr, &shm_try_destroy_orphaned, ns);
 379         up_write(&shm_ids(ns).rwsem);
 380 }
 381 
 382 /* Locking assumes this will only be called with task == current */
 383 void exit_shm(struct task_struct *task)
 384 {
 385         struct ipc_namespace *ns = task->nsproxy->ipc_ns;
 386         struct shmid_kernel *shp, *n;
 387 
 388         if (list_empty(&task->sysvshm.shm_clist))
 389                 return;
 390 
 391         /*
 392          * If kernel.shm_rmid_forced is not set then only keep track of
 393          * which shmids are orphaned, so that a later set of the sysctl
 394          * can clean them up.
 395          */
 396         if (!ns->shm_rmid_forced) {
 397                 down_read(&shm_ids(ns).rwsem);
 398                 list_for_each_entry(shp, &task->sysvshm.shm_clist, shm_clist)
 399                         shp->shm_creator = NULL;
 400                 /*
 401                  * Only under read lock but we are only called on current
 402                  * so no entry on the list will be shared.
 403                  */
 404                 list_del(&task->sysvshm.shm_clist);
 405                 up_read(&shm_ids(ns).rwsem);
 406                 return;
 407         }
 408 
 409         /*
 410          * Destroy all already created segments, that were not yet mapped,
 411          * and mark any mapped as orphan to cover the sysctl toggling.
 412          * Destroy is skipped if shm_may_destroy() returns false.
 413          */
 414         down_write(&shm_ids(ns).rwsem);
 415         list_for_each_entry_safe(shp, n, &task->sysvshm.shm_clist, shm_clist) {
 416                 shp->shm_creator = NULL;
 417 
 418                 if (shm_may_destroy(ns, shp)) {
 419                         shm_lock_by_ptr(shp);
 420                         shm_destroy(ns, shp);
 421                 }
 422         }
 423 
 424         /* Remove the list head from any segments still attached. */
 425         list_del(&task->sysvshm.shm_clist);
 426         up_write(&shm_ids(ns).rwsem);
 427 }
 428 
 429 static vm_fault_t shm_fault(struct vm_fault *vmf)
 430 {
 431         struct file *file = vmf->vma->vm_file;
 432         struct shm_file_data *sfd = shm_file_data(file);
 433 
 434         return sfd->vm_ops->fault(vmf);
 435 }
 436 
 437 static int shm_split(struct vm_area_struct *vma, unsigned long addr)
 438 {
 439         struct file *file = vma->vm_file;
 440         struct shm_file_data *sfd = shm_file_data(file);
 441 
 442         if (sfd->vm_ops->split)
 443                 return sfd->vm_ops->split(vma, addr);
 444 
 445         return 0;
 446 }
 447 
 448 static unsigned long shm_pagesize(struct vm_area_struct *vma)
 449 {
 450         struct file *file = vma->vm_file;
 451         struct shm_file_data *sfd = shm_file_data(file);
 452 
 453         if (sfd->vm_ops->pagesize)
 454                 return sfd->vm_ops->pagesize(vma);
 455 
 456         return PAGE_SIZE;
 457 }
 458 
 459 #ifdef CONFIG_NUMA
 460 static int shm_set_policy(struct vm_area_struct *vma, struct mempolicy *new)
 461 {
 462         struct file *file = vma->vm_file;
 463         struct shm_file_data *sfd = shm_file_data(file);
 464         int err = 0;
 465 
 466         if (sfd->vm_ops->set_policy)
 467                 err = sfd->vm_ops->set_policy(vma, new);
 468         return err;
 469 }
 470 
 471 static struct mempolicy *shm_get_policy(struct vm_area_struct *vma,
 472                                         unsigned long addr)
 473 {
 474         struct file *file = vma->vm_file;
 475         struct shm_file_data *sfd = shm_file_data(file);
 476         struct mempolicy *pol = NULL;
 477 
 478         if (sfd->vm_ops->get_policy)
 479                 pol = sfd->vm_ops->get_policy(vma, addr);
 480         else if (vma->vm_policy)
 481                 pol = vma->vm_policy;
 482 
 483         return pol;
 484 }
 485 #endif
 486 
 487 static int shm_mmap(struct file *file, struct vm_area_struct *vma)
 488 {
 489         struct shm_file_data *sfd = shm_file_data(file);
 490         int ret;
 491 
 492         /*
 493          * In case of remap_file_pages() emulation, the file can represent an
 494          * IPC ID that was removed, and possibly even reused by another shm
 495          * segment already.  Propagate this case as an error to caller.
 496          */
 497         ret = __shm_open(vma);
 498         if (ret)
 499                 return ret;
 500 
 501         ret = call_mmap(sfd->file, vma);
 502         if (ret) {
 503                 shm_close(vma);
 504                 return ret;
 505         }
 506         sfd->vm_ops = vma->vm_ops;
 507 #ifdef CONFIG_MMU
 508         WARN_ON(!sfd->vm_ops->fault);
 509 #endif
 510         vma->vm_ops = &shm_vm_ops;
 511         return 0;
 512 }
 513 
 514 static int shm_release(struct inode *ino, struct file *file)
 515 {
 516         struct shm_file_data *sfd = shm_file_data(file);
 517 
 518         put_ipc_ns(sfd->ns);
 519         fput(sfd->file);
 520         shm_file_data(file) = NULL;
 521         kfree(sfd);
 522         return 0;
 523 }
 524 
 525 static int shm_fsync(struct file *file, loff_t start, loff_t end, int datasync)
 526 {
 527         struct shm_file_data *sfd = shm_file_data(file);
 528 
 529         if (!sfd->file->f_op->fsync)
 530                 return -EINVAL;
 531         return sfd->file->f_op->fsync(sfd->file, start, end, datasync);
 532 }
 533 
 534 static long shm_fallocate(struct file *file, int mode, loff_t offset,
 535                           loff_t len)
 536 {
 537         struct shm_file_data *sfd = shm_file_data(file);
 538 
 539         if (!sfd->file->f_op->fallocate)
 540                 return -EOPNOTSUPP;
 541         return sfd->file->f_op->fallocate(file, mode, offset, len);
 542 }
 543 
 544 static unsigned long shm_get_unmapped_area(struct file *file,
 545         unsigned long addr, unsigned long len, unsigned long pgoff,
 546         unsigned long flags)
 547 {
 548         struct shm_file_data *sfd = shm_file_data(file);
 549 
 550         return sfd->file->f_op->get_unmapped_area(sfd->file, addr, len,
 551                                                 pgoff, flags);
 552 }
 553 
 554 static const struct file_operations shm_file_operations = {
 555         .mmap           = shm_mmap,
 556         .fsync          = shm_fsync,
 557         .release        = shm_release,
 558         .get_unmapped_area      = shm_get_unmapped_area,
 559         .llseek         = noop_llseek,
 560         .fallocate      = shm_fallocate,
 561 };
 562 
 563 /*
 564  * shm_file_operations_huge is now identical to shm_file_operations,
 565  * but we keep it distinct for the sake of is_file_shm_hugepages().
 566  */
 567 static const struct file_operations shm_file_operations_huge = {
 568         .mmap           = shm_mmap,
 569         .fsync          = shm_fsync,
 570         .release        = shm_release,
 571         .get_unmapped_area      = shm_get_unmapped_area,
 572         .llseek         = noop_llseek,
 573         .fallocate      = shm_fallocate,
 574 };
 575 
 576 bool is_file_shm_hugepages(struct file *file)
 577 {
 578         return file->f_op == &shm_file_operations_huge;
 579 }
 580 
 581 static const struct vm_operations_struct shm_vm_ops = {
 582         .open   = shm_open,     /* callback for a new vm-area open */
 583         .close  = shm_close,    /* callback for when the vm-area is released */
 584         .fault  = shm_fault,
 585         .split  = shm_split,
 586         .pagesize = shm_pagesize,
 587 #if defined(CONFIG_NUMA)
 588         .set_policy = shm_set_policy,
 589         .get_policy = shm_get_policy,
 590 #endif
 591 };
 592 
 593 /**
 594  * newseg - Create a new shared memory segment
 595  * @ns: namespace
 596  * @params: ptr to the structure that contains key, size and shmflg
 597  *
 598  * Called with shm_ids.rwsem held as a writer.
 599  */
 600 static int newseg(struct ipc_namespace *ns, struct ipc_params *params)
 601 {
 602         key_t key = params->key;
 603         int shmflg = params->flg;
 604         size_t size = params->u.size;
 605         int error;
 606         struct shmid_kernel *shp;
 607         size_t numpages = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
 608         struct file *file;
 609         char name[13];
 610         vm_flags_t acctflag = 0;
 611 
 612         if (size < SHMMIN || size > ns->shm_ctlmax)
 613                 return -EINVAL;
 614 
 615         if (numpages << PAGE_SHIFT < size)
 616                 return -ENOSPC;
 617 
 618         if (ns->shm_tot + numpages < ns->shm_tot ||
 619                         ns->shm_tot + numpages > ns->shm_ctlall)
 620                 return -ENOSPC;
 621 
 622         shp = kvmalloc(sizeof(*shp), GFP_KERNEL);
 623         if (unlikely(!shp))
 624                 return -ENOMEM;
 625 
 626         shp->shm_perm.key = key;
 627         shp->shm_perm.mode = (shmflg & S_IRWXUGO);
 628         shp->mlock_user = NULL;
 629 
 630         shp->shm_perm.security = NULL;
 631         error = security_shm_alloc(&shp->shm_perm);
 632         if (error) {
 633                 kvfree(shp);
 634                 return error;
 635         }
 636 
 637         sprintf(name, "SYSV%08x", key);
 638         if (shmflg & SHM_HUGETLB) {
 639                 struct hstate *hs;
 640                 size_t hugesize;
 641 
 642                 hs = hstate_sizelog((shmflg >> SHM_HUGE_SHIFT) & SHM_HUGE_MASK);
 643                 if (!hs) {
 644                         error = -EINVAL;
 645                         goto no_file;
 646                 }
 647                 hugesize = ALIGN(size, huge_page_size(hs));
 648 
 649                 /* hugetlb_file_setup applies strict accounting */
 650                 if (shmflg & SHM_NORESERVE)
 651                         acctflag = VM_NORESERVE;
 652                 file = hugetlb_file_setup(name, hugesize, acctflag,
 653                                   &shp->mlock_user, HUGETLB_SHMFS_INODE,
 654                                 (shmflg >> SHM_HUGE_SHIFT) & SHM_HUGE_MASK);
 655         } else {
 656                 /*
 657                  * Do not allow no accounting for OVERCOMMIT_NEVER, even
 658                  * if it's asked for.
 659                  */
 660                 if  ((shmflg & SHM_NORESERVE) &&
 661                                 sysctl_overcommit_memory != OVERCOMMIT_NEVER)
 662                         acctflag = VM_NORESERVE;
 663                 file = shmem_kernel_file_setup(name, size, acctflag);
 664         }
 665         error = PTR_ERR(file);
 666         if (IS_ERR(file))
 667                 goto no_file;
 668 
 669         shp->shm_cprid = get_pid(task_tgid(current));
 670         shp->shm_lprid = NULL;
 671         shp->shm_atim = shp->shm_dtim = 0;
 672         shp->shm_ctim = ktime_get_real_seconds();
 673         shp->shm_segsz = size;
 674         shp->shm_nattch = 0;
 675         shp->shm_file = file;
 676         shp->shm_creator = current;
 677 
 678         /* ipc_addid() locks shp upon success. */
 679         error = ipc_addid(&shm_ids(ns), &shp->shm_perm, ns->shm_ctlmni);
 680         if (error < 0)
 681                 goto no_id;
 682 
 683         list_add(&shp->shm_clist, &current->sysvshm.shm_clist);
 684 
 685         /*
 686          * shmid gets reported as "inode#" in /proc/pid/maps.
 687          * proc-ps tools use this. Changing this will break them.
 688          */
 689         file_inode(file)->i_ino = shp->shm_perm.id;
 690 
 691         ns->shm_tot += numpages;
 692         error = shp->shm_perm.id;
 693 
 694         ipc_unlock_object(&shp->shm_perm);
 695         rcu_read_unlock();
 696         return error;
 697 
 698 no_id:
 699         ipc_update_pid(&shp->shm_cprid, NULL);
 700         ipc_update_pid(&shp->shm_lprid, NULL);
 701         if (is_file_hugepages(file) && shp->mlock_user)
 702                 user_shm_unlock(size, shp->mlock_user);
 703         fput(file);
 704         ipc_rcu_putref(&shp->shm_perm, shm_rcu_free);
 705         return error;
 706 no_file:
 707         call_rcu(&shp->shm_perm.rcu, shm_rcu_free);
 708         return error;
 709 }
 710 
 711 /*
 712  * Called with shm_ids.rwsem and ipcp locked.
 713  */
 714 static inline int shm_more_checks(struct kern_ipc_perm *ipcp,
 715                                 struct ipc_params *params)
 716 {
 717         struct shmid_kernel *shp;
 718 
 719         shp = container_of(ipcp, struct shmid_kernel, shm_perm);
 720         if (shp->shm_segsz < params->u.size)
 721                 return -EINVAL;
 722 
 723         return 0;
 724 }
 725 
 726 long ksys_shmget(key_t key, size_t size, int shmflg)
 727 {
 728         struct ipc_namespace *ns;
 729         static const struct ipc_ops shm_ops = {
 730                 .getnew = newseg,
 731                 .associate = security_shm_associate,
 732                 .more_checks = shm_more_checks,
 733         };
 734         struct ipc_params shm_params;
 735 
 736         ns = current->nsproxy->ipc_ns;
 737 
 738         shm_params.key = key;
 739         shm_params.flg = shmflg;
 740         shm_params.u.size = size;
 741 
 742         return ipcget(ns, &shm_ids(ns), &shm_ops, &shm_params);
 743 }
 744 
 745 SYSCALL_DEFINE3(shmget, key_t, key, size_t, size, int, shmflg)
 746 {
 747         return ksys_shmget(key, size, shmflg);
 748 }
 749 
 750 static inline unsigned long copy_shmid_to_user(void __user *buf, struct shmid64_ds *in, int version)
 751 {
 752         switch (version) {
 753         case IPC_64:
 754                 return copy_to_user(buf, in, sizeof(*in));
 755         case IPC_OLD:
 756             {
 757                 struct shmid_ds out;
 758 
 759                 memset(&out, 0, sizeof(out));
 760                 ipc64_perm_to_ipc_perm(&in->shm_perm, &out.shm_perm);
 761                 out.shm_segsz   = in->shm_segsz;
 762                 out.shm_atime   = in->shm_atime;
 763                 out.shm_dtime   = in->shm_dtime;
 764                 out.shm_ctime   = in->shm_ctime;
 765                 out.shm_cpid    = in->shm_cpid;
 766                 out.shm_lpid    = in->shm_lpid;
 767                 out.shm_nattch  = in->shm_nattch;
 768 
 769                 return copy_to_user(buf, &out, sizeof(out));
 770             }
 771         default:
 772                 return -EINVAL;
 773         }
 774 }
 775 
 776 static inline unsigned long
 777 copy_shmid_from_user(struct shmid64_ds *out, void __user *buf, int version)
 778 {
 779         switch (version) {
 780         case IPC_64:
 781                 if (copy_from_user(out, buf, sizeof(*out)))
 782                         return -EFAULT;
 783                 return 0;
 784         case IPC_OLD:
 785             {
 786                 struct shmid_ds tbuf_old;
 787 
 788                 if (copy_from_user(&tbuf_old, buf, sizeof(tbuf_old)))
 789                         return -EFAULT;
 790 
 791                 out->shm_perm.uid       = tbuf_old.shm_perm.uid;
 792                 out->shm_perm.gid       = tbuf_old.shm_perm.gid;
 793                 out->shm_perm.mode      = tbuf_old.shm_perm.mode;
 794 
 795                 return 0;
 796             }
 797         default:
 798                 return -EINVAL;
 799         }
 800 }
 801 
 802 static inline unsigned long copy_shminfo_to_user(void __user *buf, struct shminfo64 *in, int version)
 803 {
 804         switch (version) {
 805         case IPC_64:
 806                 return copy_to_user(buf, in, sizeof(*in));
 807         case IPC_OLD:
 808             {
 809                 struct shminfo out;
 810 
 811                 if (in->shmmax > INT_MAX)
 812                         out.shmmax = INT_MAX;
 813                 else
 814                         out.shmmax = (int)in->shmmax;
 815 
 816                 out.shmmin      = in->shmmin;
 817                 out.shmmni      = in->shmmni;
 818                 out.shmseg      = in->shmseg;
 819                 out.shmall      = in->shmall;
 820 
 821                 return copy_to_user(buf, &out, sizeof(out));
 822             }
 823         default:
 824                 return -EINVAL;
 825         }
 826 }
 827 
 828 /*
 829  * Calculate and add used RSS and swap pages of a shm.
 830  * Called with shm_ids.rwsem held as a reader
 831  */
 832 static void shm_add_rss_swap(struct shmid_kernel *shp,
 833         unsigned long *rss_add, unsigned long *swp_add)
 834 {
 835         struct inode *inode;
 836 
 837         inode = file_inode(shp->shm_file);
 838 
 839         if (is_file_hugepages(shp->shm_file)) {
 840                 struct address_space *mapping = inode->i_mapping;
 841                 struct hstate *h = hstate_file(shp->shm_file);
 842                 *rss_add += pages_per_huge_page(h) * mapping->nrpages;
 843         } else {
 844 #ifdef CONFIG_SHMEM
 845                 struct shmem_inode_info *info = SHMEM_I(inode);
 846 
 847                 spin_lock_irq(&info->lock);
 848                 *rss_add += inode->i_mapping->nrpages;
 849                 *swp_add += info->swapped;
 850                 spin_unlock_irq(&info->lock);
 851 #else
 852                 *rss_add += inode->i_mapping->nrpages;
 853 #endif
 854         }
 855 }
 856 
 857 /*
 858  * Called with shm_ids.rwsem held as a reader
 859  */
 860 static void shm_get_stat(struct ipc_namespace *ns, unsigned long *rss,
 861                 unsigned long *swp)
 862 {
 863         int next_id;
 864         int total, in_use;
 865 
 866         *rss = 0;
 867         *swp = 0;
 868 
 869         in_use = shm_ids(ns).in_use;
 870 
 871         for (total = 0, next_id = 0; total < in_use; next_id++) {
 872                 struct kern_ipc_perm *ipc;
 873                 struct shmid_kernel *shp;
 874 
 875                 ipc = idr_find(&shm_ids(ns).ipcs_idr, next_id);
 876                 if (ipc == NULL)
 877                         continue;
 878                 shp = container_of(ipc, struct shmid_kernel, shm_perm);
 879 
 880                 shm_add_rss_swap(shp, rss, swp);
 881 
 882                 total++;
 883         }
 884 }
 885 
 886 /*
 887  * This function handles some shmctl commands which require the rwsem
 888  * to be held in write mode.
 889  * NOTE: no locks must be held, the rwsem is taken inside this function.
 890  */
 891 static int shmctl_down(struct ipc_namespace *ns, int shmid, int cmd,
 892                        struct shmid64_ds *shmid64)
 893 {
 894         struct kern_ipc_perm *ipcp;
 895         struct shmid_kernel *shp;
 896         int err;
 897 
 898         down_write(&shm_ids(ns).rwsem);
 899         rcu_read_lock();
 900 
 901         ipcp = ipcctl_obtain_check(ns, &shm_ids(ns), shmid, cmd,
 902                                       &shmid64->shm_perm, 0);
 903         if (IS_ERR(ipcp)) {
 904                 err = PTR_ERR(ipcp);
 905                 goto out_unlock1;
 906         }
 907 
 908         shp = container_of(ipcp, struct shmid_kernel, shm_perm);
 909 
 910         err = security_shm_shmctl(&shp->shm_perm, cmd);
 911         if (err)
 912                 goto out_unlock1;
 913 
 914         switch (cmd) {
 915         case IPC_RMID:
 916                 ipc_lock_object(&shp->shm_perm);
 917                 /* do_shm_rmid unlocks the ipc object and rcu */
 918                 do_shm_rmid(ns, ipcp);
 919                 goto out_up;
 920         case IPC_SET:
 921                 ipc_lock_object(&shp->shm_perm);
 922                 err = ipc_update_perm(&shmid64->shm_perm, ipcp);
 923                 if (err)
 924                         goto out_unlock0;
 925                 shp->shm_ctim = ktime_get_real_seconds();
 926                 break;
 927         default:
 928                 err = -EINVAL;
 929                 goto out_unlock1;
 930         }
 931 
 932 out_unlock0:
 933         ipc_unlock_object(&shp->shm_perm);
 934 out_unlock1:
 935         rcu_read_unlock();
 936 out_up:
 937         up_write(&shm_ids(ns).rwsem);
 938         return err;
 939 }
 940 
 941 static int shmctl_ipc_info(struct ipc_namespace *ns,
 942                            struct shminfo64 *shminfo)
 943 {
 944         int err = security_shm_shmctl(NULL, IPC_INFO);
 945         if (!err) {
 946                 memset(shminfo, 0, sizeof(*shminfo));
 947                 shminfo->shmmni = shminfo->shmseg = ns->shm_ctlmni;
 948                 shminfo->shmmax = ns->shm_ctlmax;
 949                 shminfo->shmall = ns->shm_ctlall;
 950                 shminfo->shmmin = SHMMIN;
 951                 down_read(&shm_ids(ns).rwsem);
 952                 err = ipc_get_maxidx(&shm_ids(ns));
 953                 up_read(&shm_ids(ns).rwsem);
 954                 if (err < 0)
 955                         err = 0;
 956         }
 957         return err;
 958 }
 959 
 960 static int shmctl_shm_info(struct ipc_namespace *ns,
 961                            struct shm_info *shm_info)
 962 {
 963         int err = security_shm_shmctl(NULL, SHM_INFO);
 964         if (!err) {
 965                 memset(shm_info, 0, sizeof(*shm_info));
 966                 down_read(&shm_ids(ns).rwsem);
 967                 shm_info->used_ids = shm_ids(ns).in_use;
 968                 shm_get_stat(ns, &shm_info->shm_rss, &shm_info->shm_swp);
 969                 shm_info->shm_tot = ns->shm_tot;
 970                 shm_info->swap_attempts = 0;
 971                 shm_info->swap_successes = 0;
 972                 err = ipc_get_maxidx(&shm_ids(ns));
 973                 up_read(&shm_ids(ns).rwsem);
 974                 if (err < 0)
 975                         err = 0;
 976         }
 977         return err;
 978 }
 979 
 980 static int shmctl_stat(struct ipc_namespace *ns, int shmid,
 981                         int cmd, struct shmid64_ds *tbuf)
 982 {
 983         struct shmid_kernel *shp;
 984         int err;
 985 
 986         memset(tbuf, 0, sizeof(*tbuf));
 987 
 988         rcu_read_lock();
 989         if (cmd == SHM_STAT || cmd == SHM_STAT_ANY) {
 990                 shp = shm_obtain_object(ns, shmid);
 991                 if (IS_ERR(shp)) {
 992                         err = PTR_ERR(shp);
 993                         goto out_unlock;
 994                 }
 995         } else { /* IPC_STAT */
 996                 shp = shm_obtain_object_check(ns, shmid);
 997                 if (IS_ERR(shp)) {
 998                         err = PTR_ERR(shp);
 999                         goto out_unlock;
1000                 }
1001         }
1002 
1003         /*
1004          * Semantically SHM_STAT_ANY ought to be identical to
1005          * that functionality provided by the /proc/sysvipc/
1006          * interface. As such, only audit these calls and
1007          * do not do traditional S_IRUGO permission checks on
1008          * the ipc object.
1009          */
1010         if (cmd == SHM_STAT_ANY)
1011                 audit_ipc_obj(&shp->shm_perm);
1012         else {
1013                 err = -EACCES;
1014                 if (ipcperms(ns, &shp->shm_perm, S_IRUGO))
1015                         goto out_unlock;
1016         }
1017 
1018         err = security_shm_shmctl(&shp->shm_perm, cmd);
1019         if (err)
1020                 goto out_unlock;
1021 
1022         ipc_lock_object(&shp->shm_perm);
1023 
1024         if (!ipc_valid_object(&shp->shm_perm)) {
1025                 ipc_unlock_object(&shp->shm_perm);
1026                 err = -EIDRM;
1027                 goto out_unlock;
1028         }
1029 
1030         kernel_to_ipc64_perm(&shp->shm_perm, &tbuf->shm_perm);
1031         tbuf->shm_segsz = shp->shm_segsz;
1032         tbuf->shm_atime = shp->shm_atim;
1033         tbuf->shm_dtime = shp->shm_dtim;
1034         tbuf->shm_ctime = shp->shm_ctim;
1035 #ifndef CONFIG_64BIT
1036         tbuf->shm_atime_high = shp->shm_atim >> 32;
1037         tbuf->shm_dtime_high = shp->shm_dtim >> 32;
1038         tbuf->shm_ctime_high = shp->shm_ctim >> 32;
1039 #endif
1040         tbuf->shm_cpid  = pid_vnr(shp->shm_cprid);
1041         tbuf->shm_lpid  = pid_vnr(shp->shm_lprid);
1042         tbuf->shm_nattch = shp->shm_nattch;
1043 
1044         if (cmd == IPC_STAT) {
1045                 /*
1046                  * As defined in SUS:
1047                  * Return 0 on success
1048                  */
1049                 err = 0;
1050         } else {
1051                 /*
1052                  * SHM_STAT and SHM_STAT_ANY (both Linux specific)
1053                  * Return the full id, including the sequence number
1054                  */
1055                 err = shp->shm_perm.id;
1056         }
1057 
1058         ipc_unlock_object(&shp->shm_perm);
1059 out_unlock:
1060         rcu_read_unlock();
1061         return err;
1062 }
1063 
1064 static int shmctl_do_lock(struct ipc_namespace *ns, int shmid, int cmd)
1065 {
1066         struct shmid_kernel *shp;
1067         struct file *shm_file;
1068         int err;
1069 
1070         rcu_read_lock();
1071         shp = shm_obtain_object_check(ns, shmid);
1072         if (IS_ERR(shp)) {
1073                 err = PTR_ERR(shp);
1074                 goto out_unlock1;
1075         }
1076 
1077         audit_ipc_obj(&(shp->shm_perm));
1078         err = security_shm_shmctl(&shp->shm_perm, cmd);
1079         if (err)
1080                 goto out_unlock1;
1081 
1082         ipc_lock_object(&shp->shm_perm);
1083 
1084         /* check if shm_destroy() is tearing down shp */
1085         if (!ipc_valid_object(&shp->shm_perm)) {
1086                 err = -EIDRM;
1087                 goto out_unlock0;
1088         }
1089 
1090         if (!ns_capable(ns->user_ns, CAP_IPC_LOCK)) {
1091                 kuid_t euid = current_euid();
1092 
1093                 if (!uid_eq(euid, shp->shm_perm.uid) &&
1094                     !uid_eq(euid, shp->shm_perm.cuid)) {
1095                         err = -EPERM;
1096                         goto out_unlock0;
1097                 }
1098                 if (cmd == SHM_LOCK && !rlimit(RLIMIT_MEMLOCK)) {
1099                         err = -EPERM;
1100                         goto out_unlock0;
1101                 }
1102         }
1103 
1104         shm_file = shp->shm_file;
1105         if (is_file_hugepages(shm_file))
1106                 goto out_unlock0;
1107 
1108         if (cmd == SHM_LOCK) {
1109                 struct user_struct *user = current_user();
1110 
1111                 err = shmem_lock(shm_file, 1, user);
1112                 if (!err && !(shp->shm_perm.mode & SHM_LOCKED)) {
1113                         shp->shm_perm.mode |= SHM_LOCKED;
1114                         shp->mlock_user = user;
1115                 }
1116                 goto out_unlock0;
1117         }
1118 
1119         /* SHM_UNLOCK */
1120         if (!(shp->shm_perm.mode & SHM_LOCKED))
1121                 goto out_unlock0;
1122         shmem_lock(shm_file, 0, shp->mlock_user);
1123         shp->shm_perm.mode &= ~SHM_LOCKED;
1124         shp->mlock_user = NULL;
1125         get_file(shm_file);
1126         ipc_unlock_object(&shp->shm_perm);
1127         rcu_read_unlock();
1128         shmem_unlock_mapping(shm_file->f_mapping);
1129 
1130         fput(shm_file);
1131         return err;
1132 
1133 out_unlock0:
1134         ipc_unlock_object(&shp->shm_perm);
1135 out_unlock1:
1136         rcu_read_unlock();
1137         return err;
1138 }
1139 
1140 static long ksys_shmctl(int shmid, int cmd, struct shmid_ds __user *buf, int version)
1141 {
1142         int err;
1143         struct ipc_namespace *ns;
1144         struct shmid64_ds sem64;
1145 
1146         if (cmd < 0 || shmid < 0)
1147                 return -EINVAL;
1148 
1149         ns = current->nsproxy->ipc_ns;
1150 
1151         switch (cmd) {
1152         case IPC_INFO: {
1153                 struct shminfo64 shminfo;
1154                 err = shmctl_ipc_info(ns, &shminfo);
1155                 if (err < 0)
1156                         return err;
1157                 if (copy_shminfo_to_user(buf, &shminfo, version))
1158                         err = -EFAULT;
1159                 return err;
1160         }
1161         case SHM_INFO: {
1162                 struct shm_info shm_info;
1163                 err = shmctl_shm_info(ns, &shm_info);
1164                 if (err < 0)
1165                         return err;
1166                 if (copy_to_user(buf, &shm_info, sizeof(shm_info)))
1167                         err = -EFAULT;
1168                 return err;
1169         }
1170         case SHM_STAT:
1171         case SHM_STAT_ANY:
1172         case IPC_STAT: {
1173                 err = shmctl_stat(ns, shmid, cmd, &sem64);
1174                 if (err < 0)
1175                         return err;
1176                 if (copy_shmid_to_user(buf, &sem64, version))
1177                         err = -EFAULT;
1178                 return err;
1179         }
1180         case IPC_SET:
1181                 if (copy_shmid_from_user(&sem64, buf, version))
1182                         return -EFAULT;
1183                 /* fallthru */
1184         case IPC_RMID:
1185                 return shmctl_down(ns, shmid, cmd, &sem64);
1186         case SHM_LOCK:
1187         case SHM_UNLOCK:
1188                 return shmctl_do_lock(ns, shmid, cmd);
1189         default:
1190                 return -EINVAL;
1191         }
1192 }
1193 
1194 SYSCALL_DEFINE3(shmctl, int, shmid, int, cmd, struct shmid_ds __user *, buf)
1195 {
1196         return ksys_shmctl(shmid, cmd, buf, IPC_64);
1197 }
1198 
1199 #ifdef CONFIG_ARCH_WANT_IPC_PARSE_VERSION
1200 long ksys_old_shmctl(int shmid, int cmd, struct shmid_ds __user *buf)
1201 {
1202         int version = ipc_parse_version(&cmd);
1203 
1204         return ksys_shmctl(shmid, cmd, buf, version);
1205 }
1206 
1207 SYSCALL_DEFINE3(old_shmctl, int, shmid, int, cmd, struct shmid_ds __user *, buf)
1208 {
1209         return ksys_old_shmctl(shmid, cmd, buf);
1210 }
1211 #endif
1212 
1213 #ifdef CONFIG_COMPAT
1214 
1215 struct compat_shmid_ds {
1216         struct compat_ipc_perm shm_perm;
1217         int shm_segsz;
1218         old_time32_t shm_atime;
1219         old_time32_t shm_dtime;
1220         old_time32_t shm_ctime;
1221         compat_ipc_pid_t shm_cpid;
1222         compat_ipc_pid_t shm_lpid;
1223         unsigned short shm_nattch;
1224         unsigned short shm_unused;
1225         compat_uptr_t shm_unused2;
1226         compat_uptr_t shm_unused3;
1227 };
1228 
1229 struct compat_shminfo64 {
1230         compat_ulong_t shmmax;
1231         compat_ulong_t shmmin;
1232         compat_ulong_t shmmni;
1233         compat_ulong_t shmseg;
1234         compat_ulong_t shmall;
1235         compat_ulong_t __unused1;
1236         compat_ulong_t __unused2;
1237         compat_ulong_t __unused3;
1238         compat_ulong_t __unused4;
1239 };
1240 
1241 struct compat_shm_info {
1242         compat_int_t used_ids;
1243         compat_ulong_t shm_tot, shm_rss, shm_swp;
1244         compat_ulong_t swap_attempts, swap_successes;
1245 };
1246 
1247 static int copy_compat_shminfo_to_user(void __user *buf, struct shminfo64 *in,
1248                                         int version)
1249 {
1250         if (in->shmmax > INT_MAX)
1251                 in->shmmax = INT_MAX;
1252         if (version == IPC_64) {
1253                 struct compat_shminfo64 info;
1254                 memset(&info, 0, sizeof(info));
1255                 info.shmmax = in->shmmax;
1256                 info.shmmin = in->shmmin;
1257                 info.shmmni = in->shmmni;
1258                 info.shmseg = in->shmseg;
1259                 info.shmall = in->shmall;
1260                 return copy_to_user(buf, &info, sizeof(info));
1261         } else {
1262                 struct shminfo info;
1263                 memset(&info, 0, sizeof(info));
1264                 info.shmmax = in->shmmax;
1265                 info.shmmin = in->shmmin;
1266                 info.shmmni = in->shmmni;
1267                 info.shmseg = in->shmseg;
1268                 info.shmall = in->shmall;
1269                 return copy_to_user(buf, &info, sizeof(info));
1270         }
1271 }
1272 
1273 static int put_compat_shm_info(struct shm_info *ip,
1274                                 struct compat_shm_info __user *uip)
1275 {
1276         struct compat_shm_info info;
1277 
1278         memset(&info, 0, sizeof(info));
1279         info.used_ids = ip->used_ids;
1280         info.shm_tot = ip->shm_tot;
1281         info.shm_rss = ip->shm_rss;
1282         info.shm_swp = ip->shm_swp;
1283         info.swap_attempts = ip->swap_attempts;
1284         info.swap_successes = ip->swap_successes;
1285         return copy_to_user(uip, &info, sizeof(info));
1286 }
1287 
1288 static int copy_compat_shmid_to_user(void __user *buf, struct shmid64_ds *in,
1289                                         int version)
1290 {
1291         if (version == IPC_64) {
1292                 struct compat_shmid64_ds v;
1293                 memset(&v, 0, sizeof(v));
1294                 to_compat_ipc64_perm(&v.shm_perm, &in->shm_perm);
1295                 v.shm_atime      = lower_32_bits(in->shm_atime);
1296                 v.shm_atime_high = upper_32_bits(in->shm_atime);
1297                 v.shm_dtime      = lower_32_bits(in->shm_dtime);
1298                 v.shm_dtime_high = upper_32_bits(in->shm_dtime);
1299                 v.shm_ctime      = lower_32_bits(in->shm_ctime);
1300                 v.shm_ctime_high = upper_32_bits(in->shm_ctime);
1301                 v.shm_segsz = in->shm_segsz;
1302                 v.shm_nattch = in->shm_nattch;
1303                 v.shm_cpid = in->shm_cpid;
1304                 v.shm_lpid = in->shm_lpid;
1305                 return copy_to_user(buf, &v, sizeof(v));
1306         } else {
1307                 struct compat_shmid_ds v;
1308                 memset(&v, 0, sizeof(v));
1309                 to_compat_ipc_perm(&v.shm_perm, &in->shm_perm);
1310                 v.shm_perm.key = in->shm_perm.key;
1311                 v.shm_atime = in->shm_atime;
1312                 v.shm_dtime = in->shm_dtime;
1313                 v.shm_ctime = in->shm_ctime;
1314                 v.shm_segsz = in->shm_segsz;
1315                 v.shm_nattch = in->shm_nattch;
1316                 v.shm_cpid = in->shm_cpid;
1317                 v.shm_lpid = in->shm_lpid;
1318                 return copy_to_user(buf, &v, sizeof(v));
1319         }
1320 }
1321 
1322 static int copy_compat_shmid_from_user(struct shmid64_ds *out, void __user *buf,
1323                                         int version)
1324 {
1325         memset(out, 0, sizeof(*out));
1326         if (version == IPC_64) {
1327                 struct compat_shmid64_ds __user *p = buf;
1328                 return get_compat_ipc64_perm(&out->shm_perm, &p->shm_perm);
1329         } else {
1330                 struct compat_shmid_ds __user *p = buf;
1331                 return get_compat_ipc_perm(&out->shm_perm, &p->shm_perm);
1332         }
1333 }
1334 
1335 long compat_ksys_shmctl(int shmid, int cmd, void __user *uptr, int version)
1336 {
1337         struct ipc_namespace *ns;
1338         struct shmid64_ds sem64;
1339         int err;
1340 
1341         ns = current->nsproxy->ipc_ns;
1342 
1343         if (cmd < 0 || shmid < 0)
1344                 return -EINVAL;
1345 
1346         switch (cmd) {
1347         case IPC_INFO: {
1348                 struct shminfo64 shminfo;
1349                 err = shmctl_ipc_info(ns, &shminfo);
1350                 if (err < 0)
1351                         return err;
1352                 if (copy_compat_shminfo_to_user(uptr, &shminfo, version))
1353                         err = -EFAULT;
1354                 return err;
1355         }
1356         case SHM_INFO: {
1357                 struct shm_info shm_info;
1358                 err = shmctl_shm_info(ns, &shm_info);
1359                 if (err < 0)
1360                         return err;
1361                 if (put_compat_shm_info(&shm_info, uptr))
1362                         err = -EFAULT;
1363                 return err;
1364         }
1365         case IPC_STAT:
1366         case SHM_STAT_ANY:
1367         case SHM_STAT:
1368                 err = shmctl_stat(ns, shmid, cmd, &sem64);
1369                 if (err < 0)
1370                         return err;
1371                 if (copy_compat_shmid_to_user(uptr, &sem64, version))
1372                         err = -EFAULT;
1373                 return err;
1374 
1375         case IPC_SET:
1376                 if (copy_compat_shmid_from_user(&sem64, uptr, version))
1377                         return -EFAULT;
1378                 /* fallthru */
1379         case IPC_RMID:
1380                 return shmctl_down(ns, shmid, cmd, &sem64);
1381         case SHM_LOCK:
1382         case SHM_UNLOCK:
1383                 return shmctl_do_lock(ns, shmid, cmd);
1384                 break;
1385         default:
1386                 return -EINVAL;
1387         }
1388         return err;
1389 }
1390 
1391 COMPAT_SYSCALL_DEFINE3(shmctl, int, shmid, int, cmd, void __user *, uptr)
1392 {
1393         return compat_ksys_shmctl(shmid, cmd, uptr, IPC_64);
1394 }
1395 
1396 #ifdef CONFIG_ARCH_WANT_COMPAT_IPC_PARSE_VERSION
1397 long compat_ksys_old_shmctl(int shmid, int cmd, void __user *uptr)
1398 {
1399         int version = compat_ipc_parse_version(&cmd);
1400 
1401         return compat_ksys_shmctl(shmid, cmd, uptr, version);
1402 }
1403 
1404 COMPAT_SYSCALL_DEFINE3(old_shmctl, int, shmid, int, cmd, void __user *, uptr)
1405 {
1406         return compat_ksys_old_shmctl(shmid, cmd, uptr);
1407 }
1408 #endif
1409 #endif
1410 
1411 /*
1412  * Fix shmaddr, allocate descriptor, map shm, add attach descriptor to lists.
1413  *
1414  * NOTE! Despite the name, this is NOT a direct system call entrypoint. The
1415  * "raddr" thing points to kernel space, and there has to be a wrapper around
1416  * this.
1417  */
1418 long do_shmat(int shmid, char __user *shmaddr, int shmflg,
1419               ulong *raddr, unsigned long shmlba)
1420 {
1421         struct shmid_kernel *shp;
1422         unsigned long addr = (unsigned long)shmaddr;
1423         unsigned long size;
1424         struct file *file, *base;
1425         int    err;
1426         unsigned long flags = MAP_SHARED;
1427         unsigned long prot;
1428         int acc_mode;
1429         struct ipc_namespace *ns;
1430         struct shm_file_data *sfd;
1431         int f_flags;
1432         unsigned long populate = 0;
1433 
1434         err = -EINVAL;
1435         if (shmid < 0)
1436                 goto out;
1437 
1438         if (addr) {
1439                 if (addr & (shmlba - 1)) {
1440                         if (shmflg & SHM_RND) {
1441                                 addr &= ~(shmlba - 1);  /* round down */
1442 
1443                                 /*
1444                                  * Ensure that the round-down is non-nil
1445                                  * when remapping. This can happen for
1446                                  * cases when addr < shmlba.
1447                                  */
1448                                 if (!addr && (shmflg & SHM_REMAP))
1449                                         goto out;
1450                         } else
1451 #ifndef __ARCH_FORCE_SHMLBA
1452                                 if (addr & ~PAGE_MASK)
1453 #endif
1454                                         goto out;
1455                 }
1456 
1457                 flags |= MAP_FIXED;
1458         } else if ((shmflg & SHM_REMAP))
1459                 goto out;
1460 
1461         if (shmflg & SHM_RDONLY) {
1462                 prot = PROT_READ;
1463                 acc_mode = S_IRUGO;
1464                 f_flags = O_RDONLY;
1465         } else {
1466                 prot = PROT_READ | PROT_WRITE;
1467                 acc_mode = S_IRUGO | S_IWUGO;
1468                 f_flags = O_RDWR;
1469         }
1470         if (shmflg & SHM_EXEC) {
1471                 prot |= PROT_EXEC;
1472                 acc_mode |= S_IXUGO;
1473         }
1474 
1475         /*
1476          * We cannot rely on the fs check since SYSV IPC does have an
1477          * additional creator id...
1478          */
1479         ns = current->nsproxy->ipc_ns;
1480         rcu_read_lock();
1481         shp = shm_obtain_object_check(ns, shmid);
1482         if (IS_ERR(shp)) {
1483                 err = PTR_ERR(shp);
1484                 goto out_unlock;
1485         }
1486 
1487         err = -EACCES;
1488         if (ipcperms(ns, &shp->shm_perm, acc_mode))
1489                 goto out_unlock;
1490 
1491         err = security_shm_shmat(&shp->shm_perm, shmaddr, shmflg);
1492         if (err)
1493                 goto out_unlock;
1494 
1495         ipc_lock_object(&shp->shm_perm);
1496 
1497         /* check if shm_destroy() is tearing down shp */
1498         if (!ipc_valid_object(&shp->shm_perm)) {
1499                 ipc_unlock_object(&shp->shm_perm);
1500                 err = -EIDRM;
1501                 goto out_unlock;
1502         }
1503 
1504         /*
1505          * We need to take a reference to the real shm file to prevent the
1506          * pointer from becoming stale in cases where the lifetime of the outer
1507          * file extends beyond that of the shm segment.  It's not usually
1508          * possible, but it can happen during remap_file_pages() emulation as
1509          * that unmaps the memory, then does ->mmap() via file reference only.
1510          * We'll deny the ->mmap() if the shm segment was since removed, but to
1511          * detect shm ID reuse we need to compare the file pointers.
1512          */
1513         base = get_file(shp->shm_file);
1514         shp->shm_nattch++;
1515         size = i_size_read(file_inode(base));
1516         ipc_unlock_object(&shp->shm_perm);
1517         rcu_read_unlock();
1518 
1519         err = -ENOMEM;
1520         sfd = kzalloc(sizeof(*sfd), GFP_KERNEL);
1521         if (!sfd) {
1522                 fput(base);
1523                 goto out_nattch;
1524         }
1525 
1526         file = alloc_file_clone(base, f_flags,
1527                           is_file_hugepages(base) ?
1528                                 &shm_file_operations_huge :
1529                                 &shm_file_operations);
1530         err = PTR_ERR(file);
1531         if (IS_ERR(file)) {
1532                 kfree(sfd);
1533                 fput(base);
1534                 goto out_nattch;
1535         }
1536 
1537         sfd->id = shp->shm_perm.id;
1538         sfd->ns = get_ipc_ns(ns);
1539         sfd->file = base;
1540         sfd->vm_ops = NULL;
1541         file->private_data = sfd;
1542 
1543         err = security_mmap_file(file, prot, flags);
1544         if (err)
1545                 goto out_fput;
1546 
1547         if (down_write_killable(&current->mm->mmap_sem)) {
1548                 err = -EINTR;
1549                 goto out_fput;
1550         }
1551 
1552         if (addr && !(shmflg & SHM_REMAP)) {
1553                 err = -EINVAL;
1554                 if (addr + size < addr)
1555                         goto invalid;
1556 
1557                 if (find_vma_intersection(current->mm, addr, addr + size))
1558                         goto invalid;
1559         }
1560 
1561         addr = do_mmap_pgoff(file, addr, size, prot, flags, 0, &populate, NULL);
1562         *raddr = addr;
1563         err = 0;
1564         if (IS_ERR_VALUE(addr))
1565                 err = (long)addr;
1566 invalid:
1567         up_write(&current->mm->mmap_sem);
1568         if (populate)
1569                 mm_populate(addr, populate);
1570 
1571 out_fput:
1572         fput(file);
1573 
1574 out_nattch:
1575         down_write(&shm_ids(ns).rwsem);
1576         shp = shm_lock(ns, shmid);
1577         shp->shm_nattch--;
1578         if (shm_may_destroy(ns, shp))
1579                 shm_destroy(ns, shp);
1580         else
1581                 shm_unlock(shp);
1582         up_write(&shm_ids(ns).rwsem);
1583         return err;
1584 
1585 out_unlock:
1586         rcu_read_unlock();
1587 out:
1588         return err;
1589 }
1590 
1591 SYSCALL_DEFINE3(shmat, int, shmid, char __user *, shmaddr, int, shmflg)
1592 {
1593         unsigned long ret;
1594         long err;
1595 
1596         err = do_shmat(shmid, shmaddr, shmflg, &ret, SHMLBA);
1597         if (err)
1598                 return err;
1599         force_successful_syscall_return();
1600         return (long)ret;
1601 }
1602 
1603 #ifdef CONFIG_COMPAT
1604 
1605 #ifndef COMPAT_SHMLBA
1606 #define COMPAT_SHMLBA   SHMLBA
1607 #endif
1608 
1609 COMPAT_SYSCALL_DEFINE3(shmat, int, shmid, compat_uptr_t, shmaddr, int, shmflg)
1610 {
1611         unsigned long ret;
1612         long err;
1613 
1614         err = do_shmat(shmid, compat_ptr(shmaddr), shmflg, &ret, COMPAT_SHMLBA);
1615         if (err)
1616                 return err;
1617         force_successful_syscall_return();
1618         return (long)ret;
1619 }
1620 #endif
1621 
1622 /*
1623  * detach and kill segment if marked destroyed.
1624  * The work is done in shm_close.
1625  */
1626 long ksys_shmdt(char __user *shmaddr)
1627 {
1628         struct mm_struct *mm = current->mm;
1629         struct vm_area_struct *vma;
1630         unsigned long addr = (unsigned long)shmaddr;
1631         int retval = -EINVAL;
1632 #ifdef CONFIG_MMU
1633         loff_t size = 0;
1634         struct file *file;
1635         struct vm_area_struct *next;
1636 #endif
1637 
1638         if (addr & ~PAGE_MASK)
1639                 return retval;
1640 
1641         if (down_write_killable(&mm->mmap_sem))
1642                 return -EINTR;
1643 
1644         /*
1645          * This function tries to be smart and unmap shm segments that
1646          * were modified by partial mlock or munmap calls:
1647          * - It first determines the size of the shm segment that should be
1648          *   unmapped: It searches for a vma that is backed by shm and that
1649          *   started at address shmaddr. It records it's size and then unmaps
1650          *   it.
1651          * - Then it unmaps all shm vmas that started at shmaddr and that
1652          *   are within the initially determined size and that are from the
1653          *   same shm segment from which we determined the size.
1654          * Errors from do_munmap are ignored: the function only fails if
1655          * it's called with invalid parameters or if it's called to unmap
1656          * a part of a vma. Both calls in this function are for full vmas,
1657          * the parameters are directly copied from the vma itself and always
1658          * valid - therefore do_munmap cannot fail. (famous last words?)
1659          */
1660         /*
1661          * If it had been mremap()'d, the starting address would not
1662          * match the usual checks anyway. So assume all vma's are
1663          * above the starting address given.
1664          */
1665         vma = find_vma(mm, addr);
1666 
1667 #ifdef CONFIG_MMU
1668         while (vma) {
1669                 next = vma->vm_next;
1670 
1671                 /*
1672                  * Check if the starting address would match, i.e. it's
1673                  * a fragment created by mprotect() and/or munmap(), or it
1674                  * otherwise it starts at this address with no hassles.
1675                  */
1676                 if ((vma->vm_ops == &shm_vm_ops) &&
1677                         (vma->vm_start - addr)/PAGE_SIZE == vma->vm_pgoff) {
1678 
1679                         /*
1680                          * Record the file of the shm segment being
1681                          * unmapped.  With mremap(), someone could place
1682                          * page from another segment but with equal offsets
1683                          * in the range we are unmapping.
1684                          */
1685                         file = vma->vm_file;
1686                         size = i_size_read(file_inode(vma->vm_file));
1687                         do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start, NULL);
1688                         /*
1689                          * We discovered the size of the shm segment, so
1690                          * break out of here and fall through to the next
1691                          * loop that uses the size information to stop
1692                          * searching for matching vma's.
1693                          */
1694                         retval = 0;
1695                         vma = next;
1696                         break;
1697                 }
1698                 vma = next;
1699         }
1700 
1701         /*
1702          * We need look no further than the maximum address a fragment
1703          * could possibly have landed at. Also cast things to loff_t to
1704          * prevent overflows and make comparisons vs. equal-width types.
1705          */
1706         size = PAGE_ALIGN(size);
1707         while (vma && (loff_t)(vma->vm_end - addr) <= size) {
1708                 next = vma->vm_next;
1709 
1710                 /* finding a matching vma now does not alter retval */
1711                 if ((vma->vm_ops == &shm_vm_ops) &&
1712                     ((vma->vm_start - addr)/PAGE_SIZE == vma->vm_pgoff) &&
1713                     (vma->vm_file == file))
1714                         do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start, NULL);
1715                 vma = next;
1716         }
1717 
1718 #else   /* CONFIG_MMU */
1719         /* under NOMMU conditions, the exact address to be destroyed must be
1720          * given
1721          */
1722         if (vma && vma->vm_start == addr && vma->vm_ops == &shm_vm_ops) {
1723                 do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start, NULL);
1724                 retval = 0;
1725         }
1726 
1727 #endif
1728 
1729         up_write(&mm->mmap_sem);
1730         return retval;
1731 }
1732 
1733 SYSCALL_DEFINE1(shmdt, char __user *, shmaddr)
1734 {
1735         return ksys_shmdt(shmaddr);
1736 }
1737 
1738 #ifdef CONFIG_PROC_FS
1739 static int sysvipc_shm_proc_show(struct seq_file *s, void *it)
1740 {
1741         struct pid_namespace *pid_ns = ipc_seq_pid_ns(s);
1742         struct user_namespace *user_ns = seq_user_ns(s);
1743         struct kern_ipc_perm *ipcp = it;
1744         struct shmid_kernel *shp;
1745         unsigned long rss = 0, swp = 0;
1746 
1747         shp = container_of(ipcp, struct shmid_kernel, shm_perm);
1748         shm_add_rss_swap(shp, &rss, &swp);
1749 
1750 #if BITS_PER_LONG <= 32
1751 #define SIZE_SPEC "%10lu"
1752 #else
1753 #define SIZE_SPEC "%21lu"
1754 #endif
1755 
1756         seq_printf(s,
1757                    "%10d %10d  %4o " SIZE_SPEC " %5u %5u  "
1758                    "%5lu %5u %5u %5u %5u %10llu %10llu %10llu "
1759                    SIZE_SPEC " " SIZE_SPEC "\n",
1760                    shp->shm_perm.key,
1761                    shp->shm_perm.id,
1762                    shp->shm_perm.mode,
1763                    shp->shm_segsz,
1764                    pid_nr_ns(shp->shm_cprid, pid_ns),
1765                    pid_nr_ns(shp->shm_lprid, pid_ns),
1766                    shp->shm_nattch,
1767                    from_kuid_munged(user_ns, shp->shm_perm.uid),
1768                    from_kgid_munged(user_ns, shp->shm_perm.gid),
1769                    from_kuid_munged(user_ns, shp->shm_perm.cuid),
1770                    from_kgid_munged(user_ns, shp->shm_perm.cgid),
1771                    shp->shm_atim,
1772                    shp->shm_dtim,
1773                    shp->shm_ctim,
1774                    rss * PAGE_SIZE,
1775                    swp * PAGE_SIZE);
1776 
1777         return 0;
1778 }
1779 #endif
/* [<][>][^][v][top][bottom][index][help] */
root/ipc/shm.c

DEFINITIONS
