ipc/shm.c

   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_rmid_forced = 0;
  78         ns->shm_tot = 0;
  79         ipc_init_ids(&shm_ids(ns));
  80 }
  81
  82 /*
  83  * Called with shm_ids.rw_mutex (writer) and the shp structure locked.
  84  * Only shm_ids.rw_mutex remains locked on exit.
  85  */
  86 static void do_shm_rmid(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp)
  87 {
  88         struct shmid_kernel *shp;
  89         shp = container_of(ipcp, struct shmid_kernel, shm_perm);
  90
  91         if (shp->shm_nattch){
  92                 shp->shm_perm.mode |= SHM_DEST;
  93                 /* Do not find it any more */
  94                 shp->shm_perm.key = IPC_PRIVATE;
  95                 shm_unlock(shp);
  96         } else
  97                 shm_destroy(ns, shp);
  98 }
  99
 100 #ifdef CONFIG_IPC_NS
 101 void shm_exit_ns(struct ipc_namespace *ns)
 102 {
 103         free_ipcs(ns, &shm_ids(ns), do_shm_rmid);
 104         idr_destroy(&ns->ids[IPC_SHM_IDS].ipcs_idr);
 105 }
 106 #endif
 107
 108 void __init shm_init (void)
 109 {
 110         shm_init_ns(&init_ipc_ns);
 111         ipc_init_proc_interface("sysvipc/shm",
 112 #if BITS_PER_LONG <= 32
 113                                 "       key      shmid perms       size  cpid  lpid nattch   uid   gid  cuid  cgid      atime      dtime      ctime        rss       swap\n",
 114 #else
 115                                 "       key      shmid perms                  size  cpid  lpid nattch   uid   gid  cuid  cgid      atime      dtime      ctime                   rss                  swap\n",
 116 #endif
 117                                 IPC_SHM_IDS, sysvipc_shm_proc_show);
 118 }
 119
 120 /*
 121  * shm_lock_(check_) routines are called in the paths where the rw_mutex
 122  * is not necessarily held.
 123  */
 124 static inline struct shmid_kernel *shm_lock(struct ipc_namespace *ns, int id)
 125 {
 126         struct kern_ipc_perm *ipcp = ipc_lock(&shm_ids(ns), id);
 127
 128         if (IS_ERR(ipcp))
 129                 return (struct shmid_kernel *)ipcp;
 130
 131         return container_of(ipcp, struct shmid_kernel, shm_perm);
 132 }
 133
 134 static inline struct shmid_kernel *shm_lock_check(struct ipc_namespace *ns,
 135                                                 int id)
 136 {
 137         struct kern_ipc_perm *ipcp = ipc_lock_check(&shm_ids(ns), id);
 138
 139         if (IS_ERR(ipcp))
 140                 return (struct shmid_kernel *)ipcp;
 141
 142         return container_of(ipcp, struct shmid_kernel, shm_perm);
 143 }
 144
 145 static inline void shm_rmid(struct ipc_namespace *ns, struct shmid_kernel *s)
 146 {
 147         ipc_rmid(&shm_ids(ns), &s->shm_perm);
 148 }
 149
 150
 151 /* This is called by fork, once for every shm attach. */
 152 static void shm_open(struct vm_area_struct *vma)
 153 {
 154         struct file *file = vma->vm_file;
 155         struct shm_file_data *sfd = shm_file_data(file);
 156         struct shmid_kernel *shp;
 157
 158         shp = shm_lock(sfd->ns, sfd->id);
 159         BUG_ON(IS_ERR(shp));
 160         shp->shm_atim = get_seconds();
 161         shp->shm_lprid = task_tgid_vnr(current);
 162         shp->shm_nattch++;
 163         shm_unlock(shp);
 164 }
 165
 166 /*
 167  * shm_destroy - free the struct shmid_kernel
 168  *
 169  * @ns: namespace
 170  * @shp: struct to free
 171  *
 172  * It has to be called with shp and shm_ids.rw_mutex (writer) locked,
 173  * but returns with shp unlocked and freed.
 174  */
 175 static void shm_destroy(struct ipc_namespace *ns, struct shmid_kernel *shp)
 176 {
 177         ns->shm_tot -= (shp->shm_segsz + PAGE_SIZE - 1) >> PAGE_SHIFT;
 178         shm_rmid(ns, shp);
 179         shm_unlock(shp);
 180         if (!is_file_hugepages(shp->shm_file))
 181                 shmem_lock(shp->shm_file, 0, shp->mlock_user);
 182         else if (shp->mlock_user)
 183                 user_shm_unlock(shp->shm_file->f_path.dentry->d_inode->i_size,
 184                                                 shp->mlock_user);
 185         fput (shp->shm_file);
 186         security_shm_free(shp);
 187         ipc_rcu_putref(shp);
 188 }
 189
 190 /*
 191  * shm_may_destroy - identifies whether shm segment should be destroyed now
 192  *
 193  * Returns true if and only if there are no active users of the segment and
 194  * one of the following is true:
 195  *
 196  * 1) shmctl(id, IPC_RMID, NULL) was called for this shp
 197  *
 198  * 2) sysctl kernel.shm_rmid_forced is set to 1.
 199  */
 200 static bool shm_may_destroy(struct ipc_namespace *ns, struct shmid_kernel *shp)
 201 {
 202         return (shp->shm_nattch == 0) &&
 203                (ns->shm_rmid_forced ||
 204                 (shp->shm_perm.mode & SHM_DEST));
 205 }
 206
 207 /*
 208  * remove the attach descriptor vma.
 209  * free memory for segment if it is marked destroyed.
 210  * The descriptor has already been removed from the current->mm->mmap list
 211  * and will later be kfree()d.
 212  */
 213 static void shm_close(struct vm_area_struct *vma)
 214 {
 215         struct file * file = vma->vm_file;
 216         struct shm_file_data *sfd = shm_file_data(file);
 217         struct shmid_kernel *shp;
 218         struct ipc_namespace *ns = sfd->ns;
 219
 220         down_write(&shm_ids(ns).rw_mutex);
 221         /* remove from the list of attaches of the shm segment */
 222         shp = shm_lock(ns, sfd->id);
 223         BUG_ON(IS_ERR(shp));
 224         shp->shm_lprid = task_tgid_vnr(current);
 225         shp->shm_dtim = get_seconds();
 226         shp->shm_nattch--;
 227         if (shm_may_destroy(ns, shp))
 228                 shm_destroy(ns, shp);
 229         else
 230                 shm_unlock(shp);
 231         up_write(&shm_ids(ns).rw_mutex);
 232 }
 233
 234 static int shm_try_destroy_current(int id, void *p, void *data)
 235 {
 236         struct ipc_namespace *ns = data;
 237         struct shmid_kernel *shp = shm_lock(ns, id);
 238
 239         if (IS_ERR(shp))
 240                 return 0;
 241
 242         if (shp->shm_creator != current) {
 243                 shm_unlock(shp);
 244                 return 0;
 245         }
 246
 247         /*
 248          * Mark it as orphaned to destroy the segment when
 249          * kernel.shm_rmid_forced is changed.
 250          * It is noop if the following shm_may_destroy() returns true.
 251          */
 252         shp->shm_creator = NULL;
 253
 254         /*
 255          * Don't even try to destroy it.  If shm_rmid_forced=0 and IPC_RMID
 256          * is not set, it shouldn't be deleted here.
 257          */
 258         if (!ns->shm_rmid_forced) {
 259                 shm_unlock(shp);
 260                 return 0;
 261         }
 262
 263         if (shm_may_destroy(ns, shp))
 264                 shm_destroy(ns, shp);
 265         else
 266                 shm_unlock(shp);
 267         return 0;
 268 }
 269
 270 static int shm_try_destroy_orphaned(int id, void *p, void *data)
 271 {
 272         struct ipc_namespace *ns = data;
 273         struct shmid_kernel *shp = shm_lock(ns, id);
 274
 275         if (IS_ERR(shp))
 276                 return 0;
 277
 278         /*
 279          * We want to destroy segments without users and with already
 280          * exit'ed originating process.
 281          */
 282         if (shp->shm_creator != NULL) {
 283                 shm_unlock(shp);
 284                 return 0;
 285         }
 286
 287         if (shm_may_destroy(ns, shp))
 288                 shm_destroy(ns, shp);
 289         else
 290                 shm_unlock(shp);
 291         return 0;
 292 }
 293
 294 void shm_destroy_orphaned(struct ipc_namespace *ns)
 295 {
 296         down_write(&shm_ids(ns).rw_mutex);
 297         idr_for_each(&shm_ids(ns).ipcs_idr, &shm_try_destroy_orphaned, ns);
 298         up_write(&shm_ids(ns).rw_mutex);
 299 }
 300
 301
 302 void exit_shm(struct task_struct *task)
 303 {
 304         struct nsproxy *nsp = task->nsproxy;
 305         struct ipc_namespace *ns;
 306
 307         if (!nsp)
 308                 return;
 309         ns = nsp->ipc_ns;
 310         if (!ns)
 311                 return;
 312
 313         /* Destroy all already created segments, but not mapped yet */
 314         down_write(&shm_ids(ns).rw_mutex);
 315         idr_for_each(&shm_ids(ns).ipcs_idr, &shm_try_destroy_current, ns);
 316         up_write(&shm_ids(ns).rw_mutex);
 317 }
 318
 319 static int shm_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
 320 {
 321         struct file *file = vma->vm_file;
 322         struct shm_file_data *sfd = shm_file_data(file);
 323
 324         return sfd->vm_ops->fault(vma, vmf);
 325 }
 326
 327 #ifdef CONFIG_NUMA
 328 static int shm_set_policy(struct vm_area_struct *vma, struct mempolicy *new)
 329 {
 330         struct file *file = vma->vm_file;
 331         struct shm_file_data *sfd = shm_file_data(file);
 332         int err = 0;
 333         if (sfd->vm_ops->set_policy)
 334                 err = sfd->vm_ops->set_policy(vma, new);
 335         return err;
 336 }
 337
 338 static struct mempolicy *shm_get_policy(struct vm_area_struct *vma,
 339                                         unsigned long addr)
 340 {
 341         struct file *file = vma->vm_file;
 342         struct shm_file_data *sfd = shm_file_data(file);
 343         struct mempolicy *pol = NULL;
 344
 345         if (sfd->vm_ops->get_policy)
 346                 pol = sfd->vm_ops->get_policy(vma, addr);
 347         else if (vma->vm_policy)
 348                 pol = vma->vm_policy;
 349
 350         return pol;
 351 }
 352 #endif
 353
 354 static int shm_mmap(struct file * file, struct vm_area_struct * vma)
 355 {
 356         struct shm_file_data *sfd = shm_file_data(file);
 357         int ret;
 358
 359         ret = sfd->file->f_op->mmap(sfd->file, vma);
 360         if (ret != 0)
 361                 return ret;
 362         sfd->vm_ops = vma->vm_ops;
 363 #ifdef CONFIG_MMU
 364         BUG_ON(!sfd->vm_ops->fault);
 365 #endif
 366         vma->vm_ops = &shm_vm_ops;
 367         shm_open(vma);
 368
 369         return ret;
 370 }
 371
 372 static int shm_release(struct inode *ino, struct file *file)
 373 {
 374         struct shm_file_data *sfd = shm_file_data(file);
 375
 376         put_ipc_ns(sfd->ns);
 377         shm_file_data(file) = NULL;
 378         kfree(sfd);
 379         return 0;
 380 }
 381
 382 static int shm_fsync(struct file *file, loff_t start, loff_t end, int datasync)
 383 {
 384         struct shm_file_data *sfd = shm_file_data(file);
 385
 386         if (!sfd->file->f_op->fsync)
 387                 return -EINVAL;
 388         return sfd->file->f_op->fsync(sfd->file, start, end, datasync);
 389 }
 390
 391 static unsigned long shm_get_unmapped_area(struct file *file,
 392         unsigned long addr, unsigned long len, unsigned long pgoff,
 393         unsigned long flags)
 394 {
 395         struct shm_file_data *sfd = shm_file_data(file);
 396         return sfd->file->f_op->get_unmapped_area(sfd->file, addr, len,
 397                                                 pgoff, flags);
 398 }
 399
 400 static const struct file_operations shm_file_operations = {
 401         .mmap           = shm_mmap,
 402         .fsync          = shm_fsync,
 403         .release        = shm_release,
 404 #ifndef CONFIG_MMU
 405         .get_unmapped_area      = shm_get_unmapped_area,
 406 #endif
 407         .llseek         = noop_llseek,
 408 };
 409
 410 static const struct file_operations shm_file_operations_huge = {
 411         .mmap           = shm_mmap,
 412         .fsync          = shm_fsync,
 413         .release        = shm_release,
 414         .get_unmapped_area      = shm_get_unmapped_area,
 415         .llseek         = noop_llseek,
 416 };
 417
 418 int is_file_shm_hugepages(struct file *file)
 419 {
 420         return file->f_op == &shm_file_operations_huge;
 421 }
 422
 423 static const struct vm_operations_struct shm_vm_ops = {
 424         .open   = shm_open,     /* callback for a new vm-area open */
 425         .close  = shm_close,    /* callback for when the vm-area is released */
 426         .fault  = shm_fault,
 427 #if defined(CONFIG_NUMA)
 428         .set_policy = shm_set_policy,
 429         .get_policy = shm_get_policy,
 430 #endif
 431 };
 432
 433 /**
 434  * newseg - Create a new shared memory segment
 435  * @ns: namespace
 436  * @params: ptr to the structure that contains key, size and shmflg
 437  *
 438  * Called with shm_ids.rw_mutex held as a writer.
 439  */
 440
 441 static int newseg(struct ipc_namespace *ns, struct ipc_params *params)
 442 {
 443         key_t key = params->key;
 444         int shmflg = params->flg;
 445         size_t size = params->u.size;
 446         int error;
 447         struct shmid_kernel *shp;
 448         int numpages = (size + PAGE_SIZE -1) >> PAGE_SHIFT;
 449         struct file * file;
 450         char name[13];
 451         int id;
 452         vm_flags_t acctflag = 0;
 453
 454         if (size < SHMMIN || size > ns->shm_ctlmax)
 455                 return -EINVAL;
 456
 457         if (ns->shm_tot + numpages > ns->shm_ctlall)
 458                 return -ENOSPC;
 459
 460         shp = ipc_rcu_alloc(sizeof(*shp));
 461         if (!shp)
 462                 return -ENOMEM;
 463
 464         shp->shm_perm.key = key;
 465         shp->shm_perm.mode = (shmflg & S_IRWXUGO);
 466         shp->mlock_user = NULL;
 467
 468         shp->shm_perm.security = NULL;
 469         error = security_shm_alloc(shp);
 470         if (error) {
 471                 ipc_rcu_putref(shp);
 472                 return error;
 473         }
 474
 475         sprintf (name, "SYSV%08x", key);
 476         if (shmflg & SHM_HUGETLB) {
 477                 /* hugetlb_file_setup applies strict accounting */
 478                 if (shmflg & SHM_NORESERVE)
 479                         acctflag = VM_NORESERVE;
 480                 file = hugetlb_file_setup(name, size, acctflag,
 481                                         &shp->mlock_user, HUGETLB_SHMFS_INODE);
 482         } else {
 483                 /*
 484                  * Do not allow no accounting for OVERCOMMIT_NEVER, even
 485                  * if it's asked for.
 486                  */
 487                 if  ((shmflg & SHM_NORESERVE) &&
 488                                 sysctl_overcommit_memory != OVERCOMMIT_NEVER)
 489                         acctflag = VM_NORESERVE;
 490                 file = shmem_file_setup(name, size, acctflag);
 491         }
 492         error = PTR_ERR(file);
 493         if (IS_ERR(file))
 494                 goto no_file;
 495
 496         id = ipc_addid(&shm_ids(ns), &shp->shm_perm, ns->shm_ctlmni);
 497         if (id < 0) {
 498                 error = id;
 499                 goto no_id;
 500         }
 501
 502         shp->shm_cprid = task_tgid_vnr(current);
 503         shp->shm_lprid = 0;
 504         shp->shm_atim = shp->shm_dtim = 0;
 505         shp->shm_ctim = get_seconds();
 506         shp->shm_segsz = size;
 507         shp->shm_nattch = 0;
 508         shp->shm_file = file;
 509         shp->shm_creator = current;
 510         /*
 511          * shmid gets reported as "inode#" in /proc/pid/maps.
 512          * proc-ps tools use this. Changing this will break them.
 513          */
 514         file->f_dentry->d_inode->i_ino = shp->shm_perm.id;
 515
 516         ns->shm_tot += numpages;
 517         error = shp->shm_perm.id;
 518         shm_unlock(shp);
 519         return error;
 520
 521 no_id:
 522         if (is_file_hugepages(file) && shp->mlock_user)
 523                 user_shm_unlock(size, shp->mlock_user);
 524         fput(file);
 525 no_file:
 526         security_shm_free(shp);
 527         ipc_rcu_putref(shp);
 528         return error;
 529 }
 530
 531 /*
 532  * Called with shm_ids.rw_mutex and ipcp locked.
 533  */
 534 static inline int shm_security(struct kern_ipc_perm *ipcp, int shmflg)
 535 {
 536         struct shmid_kernel *shp;
 537
 538         shp = container_of(ipcp, struct shmid_kernel, shm_perm);
 539         return security_shm_associate(shp, shmflg);
 540 }
 541
 542 /*
 543  * Called with shm_ids.rw_mutex and ipcp locked.
 544  */
 545 static inline int shm_more_checks(struct kern_ipc_perm *ipcp,
 546                                 struct ipc_params *params)
 547 {
 548         struct shmid_kernel *shp;
 549
 550         shp = container_of(ipcp, struct shmid_kernel, shm_perm);
 551         if (shp->shm_segsz < params->u.size)
 552                 return -EINVAL;
 553
 554         return 0;
 555 }
 556
 557 SYSCALL_DEFINE3(shmget, key_t, key, size_t, size, int, shmflg)
 558 {
 559         struct ipc_namespace *ns;
 560         struct ipc_ops shm_ops;
 561         struct ipc_params shm_params;
 562
 563         ns = current->nsproxy->ipc_ns;
 564
 565         shm_ops.getnew = newseg;
 566         shm_ops.associate = shm_security;
 567         shm_ops.more_checks = shm_more_checks;
 568
 569         shm_params.key = key;
 570         shm_params.flg = shmflg;
 571         shm_params.u.size = size;
 572
 573         return ipcget(ns, &shm_ids(ns), &shm_ops, &shm_params);
 574 }
 575
 576 static inline unsigned long copy_shmid_to_user(void __user *buf, struct shmid64_ds *in, int version)
 577 {
 578         switch(version) {
 579         case IPC_64:
 580                 return copy_to_user(buf, in, sizeof(*in));
 581         case IPC_OLD:
 582             {
 583                 struct shmid_ds out;
 584
 585                 memset(&out, 0, sizeof(out));
 586                 ipc64_perm_to_ipc_perm(&in->shm_perm, &out.shm_perm);
 587                 out.shm_segsz   = in->shm_segsz;
 588                 out.shm_atime   = in->shm_atime;
 589                 out.shm_dtime   = in->shm_dtime;
 590                 out.shm_ctime   = in->shm_ctime;
 591                 out.shm_cpid    = in->shm_cpid;
 592                 out.shm_lpid    = in->shm_lpid;
 593                 out.shm_nattch  = in->shm_nattch;
 594
 595                 return copy_to_user(buf, &out, sizeof(out));
 596             }
 597         default:
 598                 return -EINVAL;
 599         }
 600 }
 601
 602 static inline unsigned long
 603 copy_shmid_from_user(struct shmid64_ds *out, void __user *buf, int version)
 604 {
 605         switch(version) {
 606         case IPC_64:
 607                 if (copy_from_user(out, buf, sizeof(*out)))
 608                         return -EFAULT;
 609                 return 0;
 610         case IPC_OLD:
 611             {
 612                 struct shmid_ds tbuf_old;
 613
 614                 if (copy_from_user(&tbuf_old, buf, sizeof(tbuf_old)))
 615                         return -EFAULT;
 616
 617                 out->shm_perm.uid       = tbuf_old.shm_perm.uid;
 618                 out->shm_perm.gid       = tbuf_old.shm_perm.gid;
 619                 out->shm_perm.mode      = tbuf_old.shm_perm.mode;
 620
 621                 return 0;
 622             }
 623         default:
 624                 return -EINVAL;
 625         }
 626 }
 627
 628 static inline unsigned long copy_shminfo_to_user(void __user *buf, struct shminfo64 *in, int version)
 629 {
 630         switch(version) {
 631         case IPC_64:
 632                 return copy_to_user(buf, in, sizeof(*in));
 633         case IPC_OLD:
 634             {
 635                 struct shminfo out;
 636
 637                 if(in->shmmax > INT_MAX)
 638                         out.shmmax = INT_MAX;
 639                 else
 640                         out.shmmax = (int)in->shmmax;
 641
 642                 out.shmmin      = in->shmmin;
 643                 out.shmmni      = in->shmmni;
 644                 out.shmseg      = in->shmseg;
 645                 out.shmall      = in->shmall;
 646
 647                 return copy_to_user(buf, &out, sizeof(out));
 648             }
 649         default:
 650                 return -EINVAL;
 651         }
 652 }
 653
 654 /*
 655  * Calculate and add used RSS and swap pages of a shm.
 656  * Called with shm_ids.rw_mutex held as a reader
 657  */
 658 static void shm_add_rss_swap(struct shmid_kernel *shp,
 659         unsigned long *rss_add, unsigned long *swp_add)
 660 {
 661         struct inode *inode;
 662
 663         inode = shp->shm_file->f_path.dentry->d_inode;
 664
 665         if (is_file_hugepages(shp->shm_file)) {
 666                 struct address_space *mapping = inode->i_mapping;
 667                 struct hstate *h = hstate_file(shp->shm_file);
 668                 *rss_add += pages_per_huge_page(h) * mapping->nrpages;
 669         } else {
 670 #ifdef CONFIG_SHMEM
 671                 struct shmem_inode_info *info = SHMEM_I(inode);
 672                 spin_lock(&info->lock);
 673                 *rss_add += inode->i_mapping->nrpages;
 674                 *swp_add += info->swapped;
 675                 spin_unlock(&info->lock);
 676 #else
 677                 *rss_add += inode->i_mapping->nrpages;
 678 #endif
 679         }
 680 }
 681
 682 /*
 683  * Called with shm_ids.rw_mutex held as a reader
 684  */
 685 static void shm_get_stat(struct ipc_namespace *ns, unsigned long *rss,
 686                 unsigned long *swp)
 687 {
 688         int next_id;
 689         int total, in_use;
 690
 691         *rss = 0;
 692         *swp = 0;
 693
 694         in_use = shm_ids(ns).in_use;
 695
 696         for (total = 0, next_id = 0; total < in_use; next_id++) {
 697                 struct kern_ipc_perm *ipc;
 698                 struct shmid_kernel *shp;
 699
 700                 ipc = idr_find(&shm_ids(ns).ipcs_idr, next_id);
 701                 if (ipc == NULL)
 702                         continue;
 703                 shp = container_of(ipc, struct shmid_kernel, shm_perm);
 704
 705                 shm_add_rss_swap(shp, rss, swp);
 706
 707                 total++;
 708         }
 709 }
 710
 711 /*
 712  * This function handles some shmctl commands which require the rw_mutex
 713  * to be held in write mode.
 714  * NOTE: no locks must be held, the rw_mutex is taken inside this function.
 715  */
 716 static int shmctl_down(struct ipc_namespace *ns, int shmid, int cmd,
 717                        struct shmid_ds __user *buf, int version)
 718 {
 719         struct kern_ipc_perm *ipcp;
 720         struct shmid64_ds shmid64;
 721         struct shmid_kernel *shp;
 722         int err;
 723
 724         if (cmd == IPC_SET) {
 725                 if (copy_shmid_from_user(&shmid64, buf, version))
 726                         return -EFAULT;
 727         }
 728
 729         ipcp = ipcctl_pre_down(ns, &shm_ids(ns), shmid, cmd,
 730                                &shmid64.shm_perm, 0);
 731         if (IS_ERR(ipcp))
 732                 return PTR_ERR(ipcp);
 733
 734         shp = container_of(ipcp, struct shmid_kernel, shm_perm);
 735
 736         err = security_shm_shmctl(shp, cmd);
 737         if (err)
 738                 goto out_unlock;
 739         switch (cmd) {
 740         case IPC_RMID:
 741                 do_shm_rmid(ns, ipcp);
 742                 goto out_up;
 743         case IPC_SET:
 744                 ipc_update_perm(&shmid64.shm_perm, ipcp);
 745                 shp->shm_ctim = get_seconds();
 746                 break;
 747         default:
 748                 err = -EINVAL;
 749         }
 750 out_unlock:
 751         shm_unlock(shp);
 752 out_up:
 753         up_write(&shm_ids(ns).rw_mutex);
 754         return err;
 755 }
 756
 757 SYSCALL_DEFINE3(shmctl, int, shmid, int, cmd, struct shmid_ds __user *, buf)
 758 {
 759         struct shmid_kernel *shp;
 760         int err, version;
 761         struct ipc_namespace *ns;
 762
 763         if (cmd < 0 || shmid < 0) {
 764                 err = -EINVAL;
 765                 goto out;
 766         }
 767
 768         version = ipc_parse_version(&cmd);
 769         ns = current->nsproxy->ipc_ns;
 770
 771         switch (cmd) { /* replace with proc interface ? */
 772         case IPC_INFO:
 773         {
 774                 struct shminfo64 shminfo;
 775
 776                 err = security_shm_shmctl(NULL, cmd);
 777                 if (err)
 778                         return err;
 779
 780                 memset(&shminfo, 0, sizeof(shminfo));
 781                 shminfo.shmmni = shminfo.shmseg = ns->shm_ctlmni;
 782                 shminfo.shmmax = ns->shm_ctlmax;
 783                 shminfo.shmall = ns->shm_ctlall;
 784
 785                 shminfo.shmmin = SHMMIN;
 786                 if(copy_shminfo_to_user (buf, &shminfo, version))
 787                         return -EFAULT;
 788
 789                 down_read(&shm_ids(ns).rw_mutex);
 790                 err = ipc_get_maxid(&shm_ids(ns));
 791                 up_read(&shm_ids(ns).rw_mutex);
 792
 793                 if(err<0)
 794                         err = 0;
 795                 goto out;
 796         }
 797         case SHM_INFO:
 798         {
 799                 struct shm_info shm_info;
 800
 801                 err = security_shm_shmctl(NULL, cmd);
 802                 if (err)
 803                         return err;
 804
 805                 memset(&shm_info, 0, sizeof(shm_info));
 806                 down_read(&shm_ids(ns).rw_mutex);
 807                 shm_info.used_ids = shm_ids(ns).in_use;
 808                 shm_get_stat (ns, &shm_info.shm_rss, &shm_info.shm_swp);
 809                 shm_info.shm_tot = ns->shm_tot;
 810                 shm_info.swap_attempts = 0;
 811                 shm_info.swap_successes = 0;
 812                 err = ipc_get_maxid(&shm_ids(ns));
 813                 up_read(&shm_ids(ns).rw_mutex);
 814                 if (copy_to_user(buf, &shm_info, sizeof(shm_info))) {
 815                         err = -EFAULT;
 816                         goto out;
 817                 }
 818
 819                 err = err < 0 ? 0 : err;
 820                 goto out;
 821         }
 822         case SHM_STAT:
 823         case IPC_STAT:
 824         {
 825                 struct shmid64_ds tbuf;
 826                 int result;
 827
 828                 if (cmd == SHM_STAT) {
 829                         shp = shm_lock(ns, shmid);
 830                         if (IS_ERR(shp)) {
 831                                 err = PTR_ERR(shp);
 832                                 goto out;
 833                         }
 834                         result = shp->shm_perm.id;
 835                 } else {
 836                         shp = shm_lock_check(ns, shmid);
 837                         if (IS_ERR(shp)) {
 838                                 err = PTR_ERR(shp);
 839                                 goto out;
 840                         }
 841                         result = 0;
 842                 }
 843                 err = -EACCES;
 844                 if (ipcperms(ns, &shp->shm_perm, S_IRUGO))
 845                         goto out_unlock;
 846                 err = security_shm_shmctl(shp, cmd);
 847                 if (err)
 848                         goto out_unlock;
 849                 memset(&tbuf, 0, sizeof(tbuf));
 850                 kernel_to_ipc64_perm(&shp->shm_perm, &tbuf.shm_perm);
 851                 tbuf.shm_segsz  = shp->shm_segsz;
 852                 tbuf.shm_atime  = shp->shm_atim;
 853                 tbuf.shm_dtime  = shp->shm_dtim;
 854                 tbuf.shm_ctime  = shp->shm_ctim;
 855                 tbuf.shm_cpid   = shp->shm_cprid;
 856                 tbuf.shm_lpid   = shp->shm_lprid;
 857                 tbuf.shm_nattch = shp->shm_nattch;
 858                 shm_unlock(shp);
 859                 if(copy_shmid_to_user (buf, &tbuf, version))
 860                         err = -EFAULT;
 861                 else
 862                         err = result;
 863                 goto out;
 864         }
 865         case SHM_LOCK:
 866         case SHM_UNLOCK:
 867         {
 868                 struct file *uninitialized_var(shm_file);
 869
 870                 lru_add_drain_all();  /* drain pagevecs to lru lists */
 871
 872                 shp = shm_lock_check(ns, shmid);
 873                 if (IS_ERR(shp)) {
 874                         err = PTR_ERR(shp);
 875                         goto out;
 876                 }
 877
 878                 audit_ipc_obj(&(shp->shm_perm));
 879
 880                 if (!ns_capable(ns->user_ns, CAP_IPC_LOCK)) {
 881                         uid_t euid = current_euid();
 882                         err = -EPERM;
 883                         if (euid != shp->shm_perm.uid &&
 884                             euid != shp->shm_perm.cuid)
 885                                 goto out_unlock;
 886                         if (cmd == SHM_LOCK && !rlimit(RLIMIT_MEMLOCK))
 887                                 goto out_unlock;
 888                 }
 889
 890                 err = security_shm_shmctl(shp, cmd);
 891                 if (err)
 892                         goto out_unlock;
 893
 894                 if(cmd==SHM_LOCK) {
 895                         struct user_struct *user = current_user();
 896                         if (!is_file_hugepages(shp->shm_file)) {
 897                                 err = shmem_lock(shp->shm_file, 1, user);
 898                                 if (!err && !(shp->shm_perm.mode & SHM_LOCKED)){
 899                                         shp->shm_perm.mode |= SHM_LOCKED;
 900                                         shp->mlock_user = user;
 901                                 }
 902                         }
 903                 } else if (!is_file_hugepages(shp->shm_file)) {
 904                         shmem_lock(shp->shm_file, 0, shp->mlock_user);
 905                         shp->shm_perm.mode &= ~SHM_LOCKED;
 906                         shp->mlock_user = NULL;
 907                 }
 908                 shm_unlock(shp);
 909                 goto out;
 910         }
 911         case IPC_RMID:
 912         case IPC_SET:
 913                 err = shmctl_down(ns, shmid, cmd, buf, version);
 914                 return err;
 915         default:
 916                 return -EINVAL;
 917         }
 918
 919 out_unlock:
 920         shm_unlock(shp);
 921 out:
 922         return err;
 923 }
 924
 925 /*
 926  * Fix shmaddr, allocate descriptor, map shm, add attach descriptor to lists.
 927  *
 928  * NOTE! Despite the name, this is NOT a direct system call entrypoint. The
 929  * "raddr" thing points to kernel space, and there has to be a wrapper around
 930  * this.
 931  */
 932 long do_shmat(int shmid, char __user *shmaddr, int shmflg, ulong *raddr)
 933 {
 934         struct shmid_kernel *shp;
 935         unsigned long addr;
 936         unsigned long size;
 937         struct file * file;
 938         int    err;
 939         unsigned long flags;
 940         unsigned long prot;
 941         int acc_mode;
 942         unsigned long user_addr;
 943         struct ipc_namespace *ns;
 944         struct shm_file_data *sfd;
 945         struct path path;
 946         fmode_t f_mode;
 947
 948         err = -EINVAL;
 949         if (shmid < 0)
 950                 goto out;
 951         else if ((addr = (ulong)shmaddr)) {
 952                 if (addr & (SHMLBA-1)) {
 953                         if (shmflg & SHM_RND)
 954                                 addr &= ~(SHMLBA-1);       /* round down */
 955                         else
 956 #ifndef __ARCH_FORCE_SHMLBA
 957                                 if (addr & ~PAGE_MASK)
 958 #endif
 959                                         goto out;
 960                 }
 961                 flags = MAP_SHARED | MAP_FIXED;
 962         } else {
 963                 if ((shmflg & SHM_REMAP))
 964                         goto out;
 965
 966                 flags = MAP_SHARED;
 967         }
 968
 969         if (shmflg & SHM_RDONLY) {
 970                 prot = PROT_READ;
 971                 acc_mode = S_IRUGO;
 972                 f_mode = FMODE_READ;
 973         } else {
 974                 prot = PROT_READ | PROT_WRITE;
 975                 acc_mode = S_IRUGO | S_IWUGO;
 976                 f_mode = FMODE_READ | FMODE_WRITE;
 977         }
 978         if (shmflg & SHM_EXEC) {
 979                 prot |= PROT_EXEC;
 980                 acc_mode |= S_IXUGO;
 981         }
 982
 983         /*
 984          * We cannot rely on the fs check since SYSV IPC does have an
 985          * additional creator id...
 986          */
 987         ns = current->nsproxy->ipc_ns;
 988         shp = shm_lock_check(ns, shmid);
 989         if (IS_ERR(shp)) {
 990                 err = PTR_ERR(shp);
 991                 goto out;
 992         }
 993
 994         err = -EACCES;
 995         if (ipcperms(ns, &shp->shm_perm, acc_mode))
 996                 goto out_unlock;
 997
 998         err = security_shm_shmat(shp, shmaddr, shmflg);
 999         if (err)
1000                 goto out_unlock;
1001
1002         path = shp->shm_file->f_path;
1003         path_get(&path);
1004         shp->shm_nattch++;
1005         size = i_size_read(path.dentry->d_inode);
1006         shm_unlock(shp);
1007
1008         err = -ENOMEM;
1009         sfd = kzalloc(sizeof(*sfd), GFP_KERNEL);
1010         if (!sfd)
1011                 goto out_put_dentry;
1012
1013         file = alloc_file(&path, f_mode,
1014                           is_file_hugepages(shp->shm_file) ?
1015                                 &shm_file_operations_huge :
1016                                 &shm_file_operations);
1017         if (!file)
1018                 goto out_free;
1019
1020         file->private_data = sfd;
1021         file->f_mapping = shp->shm_file->f_mapping;
1022         sfd->id = shp->shm_perm.id;
1023         sfd->ns = get_ipc_ns(ns);
1024         sfd->file = shp->shm_file;
1025         sfd->vm_ops = NULL;
1026
1027         down_write(&current->mm->mmap_sem);
1028         if (addr && !(shmflg & SHM_REMAP)) {
1029                 err = -EINVAL;
1030                 if (find_vma_intersection(current->mm, addr, addr + size))
1031                         goto invalid;
1032                 /*
1033                  * If shm segment goes below stack, make sure there is some
1034                  * space left for the stack to grow (at least 4 pages).
1035                  */
1036                 if (addr < current->mm->start_stack &&
1037                     addr > current->mm->start_stack - size - PAGE_SIZE * 5)
1038                         goto invalid;
1039         }
1040
1041         user_addr = do_mmap (file, addr, size, prot, flags, 0);
1042         *raddr = user_addr;
1043         err = 0;
1044         if (IS_ERR_VALUE(user_addr))
1045                 err = (long)user_addr;
1046 invalid:
1047         up_write(&current->mm->mmap_sem);
1048
1049         fput(file);
1050
1051 out_nattch:
1052         down_write(&shm_ids(ns).rw_mutex);
1053         shp = shm_lock(ns, shmid);
1054         BUG_ON(IS_ERR(shp));
1055         shp->shm_nattch--;
1056         if (shm_may_destroy(ns, shp))
1057                 shm_destroy(ns, shp);
1058         else
1059                 shm_unlock(shp);
1060         up_write(&shm_ids(ns).rw_mutex);
1061
1062 out:
1063         return err;
1064
1065 out_unlock:
1066         shm_unlock(shp);
1067         goto out;
1068
1069 out_free:
1070         kfree(sfd);
1071 out_put_dentry:
1072         path_put(&path);
1073         goto out_nattch;
1074 }
1075
1076 SYSCALL_DEFINE3(shmat, int, shmid, char __user *, shmaddr, int, shmflg)
1077 {
1078         unsigned long ret;
1079         long err;
1080
1081         err = do_shmat(shmid, shmaddr, shmflg, &ret);
1082         if (err)
1083                 return err;
1084         force_successful_syscall_return();
1085         return (long)ret;
1086 }
1087
1088 /*
1089  * detach and kill segment if marked destroyed.
1090  * The work is done in shm_close.
1091  */
1092 SYSCALL_DEFINE1(shmdt, char __user *, shmaddr)
1093 {
1094         struct mm_struct *mm = current->mm;
1095         struct vm_area_struct *vma;
1096         unsigned long addr = (unsigned long)shmaddr;
1097         int retval = -EINVAL;
1098 #ifdef CONFIG_MMU
1099         loff_t size = 0;
1100         struct vm_area_struct *next;
1101 #endif
1102
1103         if (addr & ~PAGE_MASK)
1104                 return retval;
1105
1106         down_write(&mm->mmap_sem);
1107
1108         /*
1109          * This function tries to be smart and unmap shm segments that
1110          * were modified by partial mlock or munmap calls:
1111          * - It first determines the size of the shm segment that should be
1112          *   unmapped: It searches for a vma that is backed by shm and that
1113          *   started at address shmaddr. It records it's size and then unmaps
1114          *   it.
1115          * - Then it unmaps all shm vmas that started at shmaddr and that
1116          *   are within the initially determined size.
1117          * Errors from do_munmap are ignored: the function only fails if
1118          * it's called with invalid parameters or if it's called to unmap
1119          * a part of a vma. Both calls in this function are for full vmas,
1120          * the parameters are directly copied from the vma itself and always
1121          * valid - therefore do_munmap cannot fail. (famous last words?)
1122          */
1123         /*
1124          * If it had been mremap()'d, the starting address would not
1125          * match the usual checks anyway. So assume all vma's are
1126          * above the starting address given.
1127          */
1128         vma = find_vma(mm, addr);
1129
1130 #ifdef CONFIG_MMU
1131         while (vma) {
1132                 next = vma->vm_next;
1133
1134                 /*
1135                  * Check if the starting address would match, i.e. it's
1136                  * a fragment created by mprotect() and/or munmap(), or it
1137                  * otherwise it starts at this address with no hassles.
1138                  */
1139                 if ((vma->vm_ops == &shm_vm_ops) &&
1140                         (vma->vm_start - addr)/PAGE_SIZE == vma->vm_pgoff) {
1141
1142
1143                         size = vma->vm_file->f_path.dentry->d_inode->i_size;
1144                         do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start);
1145                         /*
1146                          * We discovered the size of the shm segment, so
1147                          * break out of here and fall through to the next
1148                          * loop that uses the size information to stop
1149                          * searching for matching vma's.
1150                          */
1151                         retval = 0;
1152                         vma = next;
1153                         break;
1154                 }
1155                 vma = next;
1156         }
1157
1158         /*
1159          * We need look no further than the maximum address a fragment
1160          * could possibly have landed at. Also cast things to loff_t to
1161          * prevent overflows and make comparisons vs. equal-width types.
1162          */
1163         size = PAGE_ALIGN(size);
1164         while (vma && (loff_t)(vma->vm_end - addr) <= size) {
1165                 next = vma->vm_next;
1166
1167                 /* finding a matching vma now does not alter retval */
1168                 if ((vma->vm_ops == &shm_vm_ops) &&
1169                         (vma->vm_start - addr)/PAGE_SIZE == vma->vm_pgoff)
1170
1171                         do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start);
1172                 vma = next;
1173         }
1174
1175 #else /* CONFIG_MMU */
1176         /* under NOMMU conditions, the exact address to be destroyed must be
1177          * given */
1178         retval = -EINVAL;
1179         if (vma->vm_start == addr && vma->vm_ops == &shm_vm_ops) {
1180                 do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start);
1181                 retval = 0;
1182         }
1183
1184 #endif
1185
1186         up_write(&mm->mmap_sem);
1187         return retval;
1188 }
1189
1190 #ifdef CONFIG_PROC_FS
1191 static int sysvipc_shm_proc_show(struct seq_file *s, void *it)
1192 {
1193         struct shmid_kernel *shp = it;
1194         unsigned long rss = 0, swp = 0;
1195
1196         shm_add_rss_swap(shp, &rss, &swp);
1197
1198 #if BITS_PER_LONG <= 32
1199 #define SIZE_SPEC "%10lu"
1200 #else
1201 #define SIZE_SPEC "%21lu"
1202 #endif
1203
1204         return seq_printf(s,
1205                           "%10d %10d  %4o " SIZE_SPEC " %5u %5u  "
1206                           "%5lu %5u %5u %5u %5u %10lu %10lu %10lu "
1207                           SIZE_SPEC " " SIZE_SPEC "\n",
1208                           shp->shm_perm.key,
1209                           shp->shm_perm.id,
1210                           shp->shm_perm.mode,
1211                           shp->shm_segsz,
1212                           shp->shm_cprid,
1213                           shp->shm_lprid,
1214                           shp->shm_nattch,
1215                           shp->shm_perm.uid,
1216                           shp->shm_perm.gid,
1217                           shp->shm_perm.cuid,
1218                           shp->shm_perm.cgid,
1219                           shp->shm_atim,
1220                           shp->shm_dtim,
1221                           shp->shm_ctim,
1222                           rss * PAGE_SIZE,
1223                           swp * PAGE_SIZE);
1224 }
1225 #endif