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 static int __init ipc_ns_init(void)
 109 {
 110         shm_init_ns(&init_ipc_ns);
 111         return 0;
 112 }
 113
 114 pure_initcall(ipc_ns_init);
 115
 116 void __init shm_init (void)
 117 {
 118         ipc_init_proc_interface("sysvipc/shm",
 119 #if BITS_PER_LONG <= 32
 120                                 "       key      shmid perms       size  cpid  lpid nattch   uid   gid  cuid  cgid      atime      dtime      ctime        rss       swap\n",
 121 #else
 122                                 "       key      shmid perms                  size  cpid  lpid nattch   uid   gid  cuid  cgid      atime      dtime      ctime                   rss                  swap\n",
 123 #endif
 124                                 IPC_SHM_IDS, sysvipc_shm_proc_show);
 125 }
 126
 127 /*
 128  * shm_lock_(check_) routines are called in the paths where the rw_mutex
 129  * is not necessarily held.
 130  */
 131 static inline struct shmid_kernel *shm_lock(struct ipc_namespace *ns, int id)
 132 {
 133         struct kern_ipc_perm *ipcp = ipc_lock(&shm_ids(ns), id);
 134
 135         if (IS_ERR(ipcp))
 136                 return (struct shmid_kernel *)ipcp;
 137
 138         return container_of(ipcp, struct shmid_kernel, shm_perm);
 139 }
 140
 141 static inline void shm_lock_by_ptr(struct shmid_kernel *ipcp)
 142 {
 143         rcu_read_lock();
 144         spin_lock(&ipcp->shm_perm.lock);
 145 }
 146
 147 static inline struct shmid_kernel *shm_lock_check(struct ipc_namespace *ns,
 148                                                 int id)
 149 {
 150         struct kern_ipc_perm *ipcp = ipc_lock_check(&shm_ids(ns), id);
 151
 152         if (IS_ERR(ipcp))
 153                 return (struct shmid_kernel *)ipcp;
 154
 155         return container_of(ipcp, struct shmid_kernel, shm_perm);
 156 }
 157
 158 static inline void shm_rmid(struct ipc_namespace *ns, struct shmid_kernel *s)
 159 {
 160         ipc_rmid(&shm_ids(ns), &s->shm_perm);
 161 }
 162
 163
 164 /* This is called by fork, once for every shm attach. */
 165 static void shm_open(struct vm_area_struct *vma)
 166 {
 167         struct file *file = vma->vm_file;
 168         struct shm_file_data *sfd = shm_file_data(file);
 169         struct shmid_kernel *shp;
 170
 171         shp = shm_lock(sfd->ns, sfd->id);
 172         BUG_ON(IS_ERR(shp));
 173         shp->shm_atim = get_seconds();
 174         shp->shm_lprid = task_tgid_vnr(current);
 175         shp->shm_nattch++;
 176         shm_unlock(shp);
 177 }
 178
 179 /*
 180  * shm_destroy - free the struct shmid_kernel
 181  *
 182  * @ns: namespace
 183  * @shp: struct to free
 184  *
 185  * It has to be called with shp and shm_ids.rw_mutex (writer) locked,
 186  * but returns with shp unlocked and freed.
 187  */
 188 static void shm_destroy(struct ipc_namespace *ns, struct shmid_kernel *shp)
 189 {
 190         ns->shm_tot -= (shp->shm_segsz + PAGE_SIZE - 1) >> PAGE_SHIFT;
 191         shm_rmid(ns, shp);
 192         shm_unlock(shp);
 193         if (!is_file_hugepages(shp->shm_file))
 194                 shmem_lock(shp->shm_file, 0, shp->mlock_user);
 195         else if (shp->mlock_user)
 196                 user_shm_unlock(shp->shm_file->f_path.dentry->d_inode->i_size,
 197                                                 shp->mlock_user);
 198         fput (shp->shm_file);
 199         security_shm_free(shp);
 200         ipc_rcu_putref(shp);
 201 }
 202
 203 /*
 204  * shm_may_destroy - identifies whether shm segment should be destroyed now
 205  *
 206  * Returns true if and only if there are no active users of the segment and
 207  * one of the following is true:
 208  *
 209  * 1) shmctl(id, IPC_RMID, NULL) was called for this shp
 210  *
 211  * 2) sysctl kernel.shm_rmid_forced is set to 1.
 212  */
 213 static bool shm_may_destroy(struct ipc_namespace *ns, struct shmid_kernel *shp)
 214 {
 215         return (shp->shm_nattch == 0) &&
 216                (ns->shm_rmid_forced ||
 217                 (shp->shm_perm.mode & SHM_DEST));
 218 }
 219
 220 /*
 221  * remove the attach descriptor vma.
 222  * free memory for segment if it is marked destroyed.
 223  * The descriptor has already been removed from the current->mm->mmap list
 224  * and will later be kfree()d.
 225  */
 226 static void shm_close(struct vm_area_struct *vma)
 227 {
 228         struct file * file = vma->vm_file;
 229         struct shm_file_data *sfd = shm_file_data(file);
 230         struct shmid_kernel *shp;
 231         struct ipc_namespace *ns = sfd->ns;
 232
 233         down_write(&shm_ids(ns).rw_mutex);
 234         /* remove from the list of attaches of the shm segment */
 235         shp = shm_lock(ns, sfd->id);
 236         BUG_ON(IS_ERR(shp));
 237         shp->shm_lprid = task_tgid_vnr(current);
 238         shp->shm_dtim = get_seconds();
 239         shp->shm_nattch--;
 240         if (shm_may_destroy(ns, shp))
 241                 shm_destroy(ns, shp);
 242         else
 243                 shm_unlock(shp);
 244         up_write(&shm_ids(ns).rw_mutex);
 245 }
 246
 247 /* Called with ns->shm_ids(ns).rw_mutex locked */
 248 static int shm_try_destroy_current(int id, void *p, void *data)
 249 {
 250         struct ipc_namespace *ns = data;
 251         struct kern_ipc_perm *ipcp = p;
 252         struct shmid_kernel *shp = container_of(ipcp, struct shmid_kernel, shm_perm);
 253
 254         if (shp->shm_creator != current)
 255                 return 0;
 256
 257         /*
 258          * Mark it as orphaned to destroy the segment when
 259          * kernel.shm_rmid_forced is changed.
 260          * It is noop if the following shm_may_destroy() returns true.
 261          */
 262         shp->shm_creator = NULL;
 263
 264         /*
 265          * Don't even try to destroy it.  If shm_rmid_forced=0 and IPC_RMID
 266          * is not set, it shouldn't be deleted here.
 267          */
 268         if (!ns->shm_rmid_forced)
 269                 return 0;
 270
 271         if (shm_may_destroy(ns, shp)) {
 272                 shm_lock_by_ptr(shp);
 273                 shm_destroy(ns, shp);
 274         }
 275         return 0;
 276 }
 277
 278 /* Called with ns->shm_ids(ns).rw_mutex locked */
 279 static int shm_try_destroy_orphaned(int id, void *p, void *data)
 280 {
 281         struct ipc_namespace *ns = data;
 282         struct kern_ipc_perm *ipcp = p;
 283         struct shmid_kernel *shp = container_of(ipcp, struct shmid_kernel, shm_perm);
 284
 285         /*
 286          * We want to destroy segments without users and with already
 287          * exit'ed originating process.
 288          *
 289          * As shp->* are changed under rw_mutex, it's safe to skip shp locking.
 290          */
 291         if (shp->shm_creator != NULL)
 292                 return 0;
 293
 294         if (shm_may_destroy(ns, shp)) {
 295                 shm_lock_by_ptr(shp);
 296                 shm_destroy(ns, shp);
 297         }
 298         return 0;
 299 }
 300
 301 void shm_destroy_orphaned(struct ipc_namespace *ns)
 302 {
 303         down_write(&shm_ids(ns).rw_mutex);
 304         if (shm_ids(ns).in_use)
 305                 idr_for_each(&shm_ids(ns).ipcs_idr, &shm_try_destroy_orphaned, ns);
 306         up_write(&shm_ids(ns).rw_mutex);
 307 }
 308
 309
 310 void exit_shm(struct task_struct *task)
 311 {
 312         struct ipc_namespace *ns = task->nsproxy->ipc_ns;
 313
 314         if (shm_ids(ns).in_use == 0)
 315                 return;
 316
 317         /* Destroy all already created segments, but not mapped yet */
 318         down_write(&shm_ids(ns).rw_mutex);
 319         if (shm_ids(ns).in_use)
 320                 idr_for_each(&shm_ids(ns).ipcs_idr, &shm_try_destroy_current, ns);
 321         up_write(&shm_ids(ns).rw_mutex);
 322 }
 323
 324 static int shm_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
 325 {
 326         struct file *file = vma->vm_file;
 327         struct shm_file_data *sfd = shm_file_data(file);
 328
 329         return sfd->vm_ops->fault(vma, vmf);
 330 }
 331
 332 #ifdef CONFIG_NUMA
 333 static int shm_set_policy(struct vm_area_struct *vma, struct mempolicy *new)
 334 {
 335         struct file *file = vma->vm_file;
 336         struct shm_file_data *sfd = shm_file_data(file);
 337         int err = 0;
 338         if (sfd->vm_ops->set_policy)
 339                 err = sfd->vm_ops->set_policy(vma, new);
 340         return err;
 341 }
 342
 343 static struct mempolicy *shm_get_policy(struct vm_area_struct *vma,
 344                                         unsigned long addr)
 345 {
 346         struct file *file = vma->vm_file;
 347         struct shm_file_data *sfd = shm_file_data(file);
 348         struct mempolicy *pol = NULL;
 349
 350         if (sfd->vm_ops->get_policy)
 351                 pol = sfd->vm_ops->get_policy(vma, addr);
 352         else if (vma->vm_policy)
 353                 pol = vma->vm_policy;
 354
 355         return pol;
 356 }
 357 #endif
 358
 359 static int shm_mmap(struct file * file, struct vm_area_struct * vma)
 360 {
 361         struct shm_file_data *sfd = shm_file_data(file);
 362         int ret;
 363
 364         ret = sfd->file->f_op->mmap(sfd->file, vma);
 365         if (ret != 0)
 366                 return ret;
 367         sfd->vm_ops = vma->vm_ops;
 368 #ifdef CONFIG_MMU
 369         BUG_ON(!sfd->vm_ops->fault);
 370 #endif
 371         vma->vm_ops = &shm_vm_ops;
 372         shm_open(vma);
 373
 374         return ret;
 375 }
 376
 377 static int shm_release(struct inode *ino, struct file *file)
 378 {
 379         struct shm_file_data *sfd = shm_file_data(file);
 380
 381         put_ipc_ns(sfd->ns);
 382         shm_file_data(file) = NULL;
 383         kfree(sfd);
 384         return 0;
 385 }
 386
 387 static int shm_fsync(struct file *file, loff_t start, loff_t end, int datasync)
 388 {
 389         struct shm_file_data *sfd = shm_file_data(file);
 390
 391         if (!sfd->file->f_op->fsync)
 392                 return -EINVAL;
 393         return sfd->file->f_op->fsync(sfd->file, start, end, datasync);
 394 }
 395
 396 static long shm_fallocate(struct file *file, int mode, loff_t offset,
 397                           loff_t len)
 398 {
 399         struct shm_file_data *sfd = shm_file_data(file);
 400
 401         if (!sfd->file->f_op->fallocate)
 402                 return -EOPNOTSUPP;
 403         return sfd->file->f_op->fallocate(file, mode, offset, len);
 404 }
 405
 406 static unsigned long shm_get_unmapped_area(struct file *file,
 407         unsigned long addr, unsigned long len, unsigned long pgoff,
 408         unsigned long flags)
 409 {
 410         struct shm_file_data *sfd = shm_file_data(file);
 411         return sfd->file->f_op->get_unmapped_area(sfd->file, addr, len,
 412                                                 pgoff, flags);
 413 }
 414
 415 static const struct file_operations shm_file_operations = {
 416         .mmap           = shm_mmap,
 417         .fsync          = shm_fsync,
 418         .release        = shm_release,
 419 #ifndef CONFIG_MMU
 420         .get_unmapped_area      = shm_get_unmapped_area,
 421 #endif
 422         .llseek         = noop_llseek,
 423         .fallocate      = shm_fallocate,
 424 };
 425
 426 static const struct file_operations shm_file_operations_huge = {
 427         .mmap           = shm_mmap,
 428         .fsync          = shm_fsync,
 429         .release        = shm_release,
 430         .get_unmapped_area      = shm_get_unmapped_area,
 431         .llseek         = noop_llseek,
 432         .fallocate      = shm_fallocate,
 433 };
 434
 435 int is_file_shm_hugepages(struct file *file)
 436 {
 437         return file->f_op == &shm_file_operations_huge;
 438 }
 439
 440 static const struct vm_operations_struct shm_vm_ops = {
 441         .open   = shm_open,     /* callback for a new vm-area open */
 442         .close  = shm_close,    /* callback for when the vm-area is released */
 443         .fault  = shm_fault,
 444 #if defined(CONFIG_NUMA)
 445         .set_policy = shm_set_policy,
 446         .get_policy = shm_get_policy,
 447 #endif
 448 };
 449
 450 /**
 451  * newseg - Create a new shared memory segment
 452  * @ns: namespace
 453  * @params: ptr to the structure that contains key, size and shmflg
 454  *
 455  * Called with shm_ids.rw_mutex held as a writer.
 456  */
 457
 458 static int newseg(struct ipc_namespace *ns, struct ipc_params *params)
 459 {
 460         key_t key = params->key;
 461         int shmflg = params->flg;
 462         size_t size = params->u.size;
 463         int error;
 464         struct shmid_kernel *shp;
 465         int numpages = (size + PAGE_SIZE -1) >> PAGE_SHIFT;
 466         struct file * file;
 467         char name[13];
 468         int id;
 469         vm_flags_t acctflag = 0;
 470
 471         if (size < SHMMIN || size > ns->shm_ctlmax)
 472                 return -EINVAL;
 473
 474         if (ns->shm_tot + numpages > ns->shm_ctlall)
 475                 return -ENOSPC;
 476
 477         shp = ipc_rcu_alloc(sizeof(*shp));
 478         if (!shp)
 479                 return -ENOMEM;
 480
 481         shp->shm_perm.key = key;
 482         shp->shm_perm.mode = (shmflg & S_IRWXUGO);
 483         shp->mlock_user = NULL;
 484
 485         shp->shm_perm.security = NULL;
 486         error = security_shm_alloc(shp);
 487         if (error) {
 488                 ipc_rcu_putref(shp);
 489                 return error;
 490         }
 491
 492         sprintf (name, "SYSV%08x", key);
 493         if (shmflg & SHM_HUGETLB) {
 494                 /* hugetlb_file_setup applies strict accounting */
 495                 if (shmflg & SHM_NORESERVE)
 496                         acctflag = VM_NORESERVE;
 497                 file = hugetlb_file_setup(name, 0, size, acctflag,
 498                                   &shp->mlock_user, HUGETLB_SHMFS_INODE,
 499                                 (shmflg >> SHM_HUGE_SHIFT) & SHM_HUGE_MASK);
 500         } else {
 501                 /*
 502                  * Do not allow no accounting for OVERCOMMIT_NEVER, even
 503                  * if it's asked for.
 504                  */
 505                 if  ((shmflg & SHM_NORESERVE) &&
 506                                 sysctl_overcommit_memory != OVERCOMMIT_NEVER)
 507                         acctflag = VM_NORESERVE;
 508                 file = shmem_file_setup(name, size, acctflag);
 509         }
 510         error = PTR_ERR(file);
 511         if (IS_ERR(file))
 512                 goto no_file;
 513
 514         id = ipc_addid(&shm_ids(ns), &shp->shm_perm, ns->shm_ctlmni);
 515         if (id < 0) {
 516                 error = id;
 517                 goto no_id;
 518         }
 519
 520         shp->shm_cprid = task_tgid_vnr(current);
 521         shp->shm_lprid = 0;
 522         shp->shm_atim = shp->shm_dtim = 0;
 523         shp->shm_ctim = get_seconds();
 524         shp->shm_segsz = size;
 525         shp->shm_nattch = 0;
 526         shp->shm_file = file;
 527         shp->shm_creator = current;
 528         /*
 529          * shmid gets reported as "inode#" in /proc/pid/maps.
 530          * proc-ps tools use this. Changing this will break them.
 531          */
 532         file->f_dentry->d_inode->i_ino = shp->shm_perm.id;
 533
 534         ns->shm_tot += numpages;
 535         error = shp->shm_perm.id;
 536         shm_unlock(shp);
 537         return error;
 538
 539 no_id:
 540         if (is_file_hugepages(file) && shp->mlock_user)
 541                 user_shm_unlock(size, shp->mlock_user);
 542         fput(file);
 543 no_file:
 544         security_shm_free(shp);
 545         ipc_rcu_putref(shp);
 546         return error;
 547 }
 548
 549 /*
 550  * Called with shm_ids.rw_mutex and ipcp locked.
 551  */
 552 static inline int shm_security(struct kern_ipc_perm *ipcp, int shmflg)
 553 {
 554         struct shmid_kernel *shp;
 555
 556         shp = container_of(ipcp, struct shmid_kernel, shm_perm);
 557         return security_shm_associate(shp, shmflg);
 558 }
 559
 560 /*
 561  * Called with shm_ids.rw_mutex and ipcp locked.
 562  */
 563 static inline int shm_more_checks(struct kern_ipc_perm *ipcp,
 564                                 struct ipc_params *params)
 565 {
 566         struct shmid_kernel *shp;
 567
 568         shp = container_of(ipcp, struct shmid_kernel, shm_perm);
 569         if (shp->shm_segsz < params->u.size)
 570                 return -EINVAL;
 571
 572         return 0;
 573 }
 574
 575 SYSCALL_DEFINE3(shmget, key_t, key, size_t, size, int, shmflg)
 576 {
 577         struct ipc_namespace *ns;
 578         struct ipc_ops shm_ops;
 579         struct ipc_params shm_params;
 580
 581         ns = current->nsproxy->ipc_ns;
 582
 583         shm_ops.getnew = newseg;
 584         shm_ops.associate = shm_security;
 585         shm_ops.more_checks = shm_more_checks;
 586
 587         shm_params.key = key;
 588         shm_params.flg = shmflg;
 589         shm_params.u.size = size;
 590
 591         return ipcget(ns, &shm_ids(ns), &shm_ops, &shm_params);
 592 }
 593
 594 static inline unsigned long copy_shmid_to_user(void __user *buf, struct shmid64_ds *in, int version)
 595 {
 596         switch(version) {
 597         case IPC_64:
 598                 return copy_to_user(buf, in, sizeof(*in));
 599         case IPC_OLD:
 600             {
 601                 struct shmid_ds out;
 602
 603                 memset(&out, 0, sizeof(out));
 604                 ipc64_perm_to_ipc_perm(&in->shm_perm, &out.shm_perm);
 605                 out.shm_segsz   = in->shm_segsz;
 606                 out.shm_atime   = in->shm_atime;
 607                 out.shm_dtime   = in->shm_dtime;
 608                 out.shm_ctime   = in->shm_ctime;
 609                 out.shm_cpid    = in->shm_cpid;
 610                 out.shm_lpid    = in->shm_lpid;
 611                 out.shm_nattch  = in->shm_nattch;
 612
 613                 return copy_to_user(buf, &out, sizeof(out));
 614             }
 615         default:
 616                 return -EINVAL;
 617         }
 618 }
 619
 620 static inline unsigned long
 621 copy_shmid_from_user(struct shmid64_ds *out, void __user *buf, int version)
 622 {
 623         switch(version) {
 624         case IPC_64:
 625                 if (copy_from_user(out, buf, sizeof(*out)))
 626                         return -EFAULT;
 627                 return 0;
 628         case IPC_OLD:
 629             {
 630                 struct shmid_ds tbuf_old;
 631
 632                 if (copy_from_user(&tbuf_old, buf, sizeof(tbuf_old)))
 633                         return -EFAULT;
 634
 635                 out->shm_perm.uid       = tbuf_old.shm_perm.uid;
 636                 out->shm_perm.gid       = tbuf_old.shm_perm.gid;
 637                 out->shm_perm.mode      = tbuf_old.shm_perm.mode;
 638
 639                 return 0;
 640             }
 641         default:
 642                 return -EINVAL;
 643         }
 644 }
 645
 646 static inline unsigned long copy_shminfo_to_user(void __user *buf, struct shminfo64 *in, int version)
 647 {
 648         switch(version) {
 649         case IPC_64:
 650                 return copy_to_user(buf, in, sizeof(*in));
 651         case IPC_OLD:
 652             {
 653                 struct shminfo out;
 654
 655                 if(in->shmmax > INT_MAX)
 656                         out.shmmax = INT_MAX;
 657                 else
 658                         out.shmmax = (int)in->shmmax;
 659
 660                 out.shmmin      = in->shmmin;
 661                 out.shmmni      = in->shmmni;
 662                 out.shmseg      = in->shmseg;
 663                 out.shmall      = in->shmall;
 664
 665                 return copy_to_user(buf, &out, sizeof(out));
 666             }
 667         default:
 668                 return -EINVAL;
 669         }
 670 }
 671
 672 /*
 673  * Calculate and add used RSS and swap pages of a shm.
 674  * Called with shm_ids.rw_mutex held as a reader
 675  */
 676 static void shm_add_rss_swap(struct shmid_kernel *shp,
 677         unsigned long *rss_add, unsigned long *swp_add)
 678 {
 679         struct inode *inode;
 680
 681         inode = shp->shm_file->f_path.dentry->d_inode;
 682
 683         if (is_file_hugepages(shp->shm_file)) {
 684                 struct address_space *mapping = inode->i_mapping;
 685                 struct hstate *h = hstate_file(shp->shm_file);
 686                 *rss_add += pages_per_huge_page(h) * mapping->nrpages;
 687         } else {
 688 #ifdef CONFIG_SHMEM
 689                 struct shmem_inode_info *info = SHMEM_I(inode);
 690                 spin_lock(&info->lock);
 691                 *rss_add += inode->i_mapping->nrpages;
 692                 *swp_add += info->swapped;
 693                 spin_unlock(&info->lock);
 694 #else
 695                 *rss_add += inode->i_mapping->nrpages;
 696 #endif
 697         }
 698 }
 699
 700 /*
 701  * Called with shm_ids.rw_mutex held as a reader
 702  */
 703 static void shm_get_stat(struct ipc_namespace *ns, unsigned long *rss,
 704                 unsigned long *swp)
 705 {
 706         int next_id;
 707         int total, in_use;
 708
 709         *rss = 0;
 710         *swp = 0;
 711
 712         in_use = shm_ids(ns).in_use;
 713
 714         for (total = 0, next_id = 0; total < in_use; next_id++) {
 715                 struct kern_ipc_perm *ipc;
 716                 struct shmid_kernel *shp;
 717
 718                 ipc = idr_find(&shm_ids(ns).ipcs_idr, next_id);
 719                 if (ipc == NULL)
 720                         continue;
 721                 shp = container_of(ipc, struct shmid_kernel, shm_perm);
 722
 723                 shm_add_rss_swap(shp, rss, swp);
 724
 725                 total++;
 726         }
 727 }
 728
 729 /*
 730  * This function handles some shmctl commands which require the rw_mutex
 731  * to be held in write mode.
 732  * NOTE: no locks must be held, the rw_mutex is taken inside this function.
 733  */
 734 static int shmctl_down(struct ipc_namespace *ns, int shmid, int cmd,
 735                        struct shmid_ds __user *buf, int version)
 736 {
 737         struct kern_ipc_perm *ipcp;
 738         struct shmid64_ds shmid64;
 739         struct shmid_kernel *shp;
 740         int err;
 741
 742         if (cmd == IPC_SET) {
 743                 if (copy_shmid_from_user(&shmid64, buf, version))
 744                         return -EFAULT;
 745         }
 746
 747         ipcp = ipcctl_pre_down(ns, &shm_ids(ns), shmid, cmd,
 748                                &shmid64.shm_perm, 0);
 749         if (IS_ERR(ipcp))
 750                 return PTR_ERR(ipcp);
 751
 752         shp = container_of(ipcp, struct shmid_kernel, shm_perm);
 753
 754         err = security_shm_shmctl(shp, cmd);
 755         if (err)
 756                 goto out_unlock;
 757         switch (cmd) {
 758         case IPC_RMID:
 759                 do_shm_rmid(ns, ipcp);
 760                 goto out_up;
 761         case IPC_SET:
 762                 err = ipc_update_perm(&shmid64.shm_perm, ipcp);
 763                 if (err)
 764                         goto out_unlock;
 765                 shp->shm_ctim = get_seconds();
 766                 break;
 767         default:
 768                 err = -EINVAL;
 769         }
 770 out_unlock:
 771         shm_unlock(shp);
 772 out_up:
 773         up_write(&shm_ids(ns).rw_mutex);
 774         return err;
 775 }
 776
 777 SYSCALL_DEFINE3(shmctl, int, shmid, int, cmd, struct shmid_ds __user *, buf)
 778 {
 779         struct shmid_kernel *shp;
 780         int err, version;
 781         struct ipc_namespace *ns;
 782
 783         if (cmd < 0 || shmid < 0) {
 784                 err = -EINVAL;
 785                 goto out;
 786         }
 787
 788         version = ipc_parse_version(&cmd);
 789         ns = current->nsproxy->ipc_ns;
 790
 791         switch (cmd) { /* replace with proc interface ? */
 792         case IPC_INFO:
 793         {
 794                 struct shminfo64 shminfo;
 795
 796                 err = security_shm_shmctl(NULL, cmd);
 797                 if (err)
 798                         return err;
 799
 800                 memset(&shminfo, 0, sizeof(shminfo));
 801                 shminfo.shmmni = shminfo.shmseg = ns->shm_ctlmni;
 802                 shminfo.shmmax = ns->shm_ctlmax;
 803                 shminfo.shmall = ns->shm_ctlall;
 804
 805                 shminfo.shmmin = SHMMIN;
 806                 if(copy_shminfo_to_user (buf, &shminfo, version))
 807                         return -EFAULT;
 808
 809                 down_read(&shm_ids(ns).rw_mutex);
 810                 err = ipc_get_maxid(&shm_ids(ns));
 811                 up_read(&shm_ids(ns).rw_mutex);
 812
 813                 if(err<0)
 814                         err = 0;
 815                 goto out;
 816         }
 817         case SHM_INFO:
 818         {
 819                 struct shm_info shm_info;
 820
 821                 err = security_shm_shmctl(NULL, cmd);
 822                 if (err)
 823                         return err;
 824
 825                 memset(&shm_info, 0, sizeof(shm_info));
 826                 down_read(&shm_ids(ns).rw_mutex);
 827                 shm_info.used_ids = shm_ids(ns).in_use;
 828                 shm_get_stat (ns, &shm_info.shm_rss, &shm_info.shm_swp);
 829                 shm_info.shm_tot = ns->shm_tot;
 830                 shm_info.swap_attempts = 0;
 831                 shm_info.swap_successes = 0;
 832                 err = ipc_get_maxid(&shm_ids(ns));
 833                 up_read(&shm_ids(ns).rw_mutex);
 834                 if (copy_to_user(buf, &shm_info, sizeof(shm_info))) {
 835                         err = -EFAULT;
 836                         goto out;
 837                 }
 838
 839                 err = err < 0 ? 0 : err;
 840                 goto out;
 841         }
 842         case SHM_STAT:
 843         case IPC_STAT:
 844         {
 845                 struct shmid64_ds tbuf;
 846                 int result;
 847
 848                 if (cmd == SHM_STAT) {
 849                         shp = shm_lock(ns, shmid);
 850                         if (IS_ERR(shp)) {
 851                                 err = PTR_ERR(shp);
 852                                 goto out;
 853                         }
 854                         result = shp->shm_perm.id;
 855                 } else {
 856                         shp = shm_lock_check(ns, shmid);
 857                         if (IS_ERR(shp)) {
 858                                 err = PTR_ERR(shp);
 859                                 goto out;
 860                         }
 861                         result = 0;
 862                 }
 863                 err = -EACCES;
 864                 if (ipcperms(ns, &shp->shm_perm, S_IRUGO))
 865                         goto out_unlock;
 866                 err = security_shm_shmctl(shp, cmd);
 867                 if (err)
 868                         goto out_unlock;
 869                 memset(&tbuf, 0, sizeof(tbuf));
 870                 kernel_to_ipc64_perm(&shp->shm_perm, &tbuf.shm_perm);
 871                 tbuf.shm_segsz  = shp->shm_segsz;
 872                 tbuf.shm_atime  = shp->shm_atim;
 873                 tbuf.shm_dtime  = shp->shm_dtim;
 874                 tbuf.shm_ctime  = shp->shm_ctim;
 875                 tbuf.shm_cpid   = shp->shm_cprid;
 876                 tbuf.shm_lpid   = shp->shm_lprid;
 877                 tbuf.shm_nattch = shp->shm_nattch;
 878                 shm_unlock(shp);
 879                 if(copy_shmid_to_user (buf, &tbuf, version))
 880                         err = -EFAULT;
 881                 else
 882                         err = result;
 883                 goto out;
 884         }
 885         case SHM_LOCK:
 886         case SHM_UNLOCK:
 887         {
 888                 struct file *shm_file;
 889
 890                 shp = shm_lock_check(ns, shmid);
 891                 if (IS_ERR(shp)) {
 892                         err = PTR_ERR(shp);
 893                         goto out;
 894                 }
 895
 896                 audit_ipc_obj(&(shp->shm_perm));
 897
 898                 if (!ns_capable(ns->user_ns, CAP_IPC_LOCK)) {
 899                         kuid_t euid = current_euid();
 900                         err = -EPERM;
 901                         if (!uid_eq(euid, shp->shm_perm.uid) &&
 902                             !uid_eq(euid, shp->shm_perm.cuid))
 903                                 goto out_unlock;
 904                         if (cmd == SHM_LOCK && !rlimit(RLIMIT_MEMLOCK))
 905                                 goto out_unlock;
 906                 }
 907
 908                 err = security_shm_shmctl(shp, cmd);
 909                 if (err)
 910                         goto out_unlock;
 911
 912                 shm_file = shp->shm_file;
 913                 if (is_file_hugepages(shm_file))
 914                         goto out_unlock;
 915
 916                 if (cmd == SHM_LOCK) {
 917                         struct user_struct *user = current_user();
 918                         err = shmem_lock(shm_file, 1, user);
 919                         if (!err && !(shp->shm_perm.mode & SHM_LOCKED)) {
 920                                 shp->shm_perm.mode |= SHM_LOCKED;
 921                                 shp->mlock_user = user;
 922                         }
 923                         goto out_unlock;
 924                 }
 925
 926                 /* SHM_UNLOCK */
 927                 if (!(shp->shm_perm.mode & SHM_LOCKED))
 928                         goto out_unlock;
 929                 shmem_lock(shm_file, 0, shp->mlock_user);
 930                 shp->shm_perm.mode &= ~SHM_LOCKED;
 931                 shp->mlock_user = NULL;
 932                 get_file(shm_file);
 933                 shm_unlock(shp);
 934                 shmem_unlock_mapping(shm_file->f_mapping);
 935                 fput(shm_file);
 936                 goto out;
 937         }
 938         case IPC_RMID:
 939         case IPC_SET:
 940                 err = shmctl_down(ns, shmid, cmd, buf, version);
 941                 return err;
 942         default:
 943                 return -EINVAL;
 944         }
 945
 946 out_unlock:
 947         shm_unlock(shp);
 948 out:
 949         return err;
 950 }
 951
 952 /*
 953  * Fix shmaddr, allocate descriptor, map shm, add attach descriptor to lists.
 954  *
 955  * NOTE! Despite the name, this is NOT a direct system call entrypoint. The
 956  * "raddr" thing points to kernel space, and there has to be a wrapper around
 957  * this.
 958  */
 959 long do_shmat(int shmid, char __user *shmaddr, int shmflg, ulong *raddr,
 960               unsigned long shmlba)
 961 {
 962         struct shmid_kernel *shp;
 963         unsigned long addr;
 964         unsigned long size;
 965         struct file * file;
 966         int    err;
 967         unsigned long flags;
 968         unsigned long prot;
 969         int acc_mode;
 970         struct ipc_namespace *ns;
 971         struct shm_file_data *sfd;
 972         struct path path;
 973         fmode_t f_mode;
 974         unsigned long populate = 0;
 975
 976         err = -EINVAL;
 977         if (shmid < 0)
 978                 goto out;
 979         else if ((addr = (ulong)shmaddr)) {
 980                 if (addr & (shmlba - 1)) {
 981                         if (shmflg & SHM_RND)
 982                                 addr &= ~(shmlba - 1);     /* round down */
 983                         else
 984 #ifndef __ARCH_FORCE_SHMLBA
 985                                 if (addr & ~PAGE_MASK)
 986 #endif
 987                                         goto out;
 988                 }
 989                 flags = MAP_SHARED | MAP_FIXED;
 990         } else {
 991                 if ((shmflg & SHM_REMAP))
 992                         goto out;
 993
 994                 flags = MAP_SHARED;
 995         }
 996
 997         if (shmflg & SHM_RDONLY) {
 998                 prot = PROT_READ;
 999                 acc_mode = S_IRUGO;
1000                 f_mode = FMODE_READ;
1001         } else {
1002                 prot = PROT_READ | PROT_WRITE;
1003                 acc_mode = S_IRUGO | S_IWUGO;
1004                 f_mode = FMODE_READ | FMODE_WRITE;
1005         }
1006         if (shmflg & SHM_EXEC) {
1007                 prot |= PROT_EXEC;
1008                 acc_mode |= S_IXUGO;
1009         }
1010
1011         /*
1012          * We cannot rely on the fs check since SYSV IPC does have an
1013          * additional creator id...
1014          */
1015         ns = current->nsproxy->ipc_ns;
1016         shp = shm_lock_check(ns, shmid);
1017         if (IS_ERR(shp)) {
1018                 err = PTR_ERR(shp);
1019                 goto out;
1020         }
1021
1022         err = -EACCES;
1023         if (ipcperms(ns, &shp->shm_perm, acc_mode))
1024                 goto out_unlock;
1025
1026         err = security_shm_shmat(shp, shmaddr, shmflg);
1027         if (err)
1028                 goto out_unlock;
1029
1030         path = shp->shm_file->f_path;
1031         path_get(&path);
1032         shp->shm_nattch++;
1033         size = i_size_read(path.dentry->d_inode);
1034         shm_unlock(shp);
1035
1036         err = -ENOMEM;
1037         sfd = kzalloc(sizeof(*sfd), GFP_KERNEL);
1038         if (!sfd)
1039                 goto out_put_dentry;
1040
1041         file = alloc_file(&path, f_mode,
1042                           is_file_hugepages(shp->shm_file) ?
1043                                 &shm_file_operations_huge :
1044                                 &shm_file_operations);
1045         if (!file)
1046                 goto out_free;
1047
1048         file->private_data = sfd;
1049         file->f_mapping = shp->shm_file->f_mapping;
1050         sfd->id = shp->shm_perm.id;
1051         sfd->ns = get_ipc_ns(ns);
1052         sfd->file = shp->shm_file;
1053         sfd->vm_ops = NULL;
1054
1055         err = security_mmap_file(file, prot, flags);
1056         if (err)
1057                 goto out_fput;
1058
1059         down_write(&current->mm->mmap_sem);
1060         if (addr && !(shmflg & SHM_REMAP)) {
1061                 err = -EINVAL;
1062                 if (find_vma_intersection(current->mm, addr, addr + size))
1063                         goto invalid;
1064                 /*
1065                  * If shm segment goes below stack, make sure there is some
1066                  * space left for the stack to grow (at least 4 pages).
1067                  */
1068                 if (addr < current->mm->start_stack &&
1069                     addr > current->mm->start_stack - size - PAGE_SIZE * 5)
1070                         goto invalid;
1071         }
1072
1073         addr = do_mmap_pgoff(file, addr, size, prot, flags, 0, &populate);
1074         *raddr = addr;
1075         err = 0;
1076         if (IS_ERR_VALUE(addr))
1077                 err = (long)addr;
1078 invalid:
1079         up_write(&current->mm->mmap_sem);
1080         if (populate)
1081                 mm_populate(addr, populate);
1082
1083 out_fput:
1084         fput(file);
1085
1086 out_nattch:
1087         down_write(&shm_ids(ns).rw_mutex);
1088         shp = shm_lock(ns, shmid);
1089         BUG_ON(IS_ERR(shp));
1090         shp->shm_nattch--;
1091         if (shm_may_destroy(ns, shp))
1092                 shm_destroy(ns, shp);
1093         else
1094                 shm_unlock(shp);
1095         up_write(&shm_ids(ns).rw_mutex);
1096
1097 out:
1098         return err;
1099
1100 out_unlock:
1101         shm_unlock(shp);
1102         goto out;
1103
1104 out_free:
1105         kfree(sfd);
1106 out_put_dentry:
1107         path_put(&path);
1108         goto out_nattch;
1109 }
1110
1111 SYSCALL_DEFINE3(shmat, int, shmid, char __user *, shmaddr, int, shmflg)
1112 {
1113         unsigned long ret;
1114         long err;
1115
1116         err = do_shmat(shmid, shmaddr, shmflg, &ret, SHMLBA);
1117         if (err)
1118                 return err;
1119         force_successful_syscall_return();
1120         return (long)ret;
1121 }
1122
1123 /*
1124  * detach and kill segment if marked destroyed.
1125  * The work is done in shm_close.
1126  */
1127 SYSCALL_DEFINE1(shmdt, char __user *, shmaddr)
1128 {
1129         struct mm_struct *mm = current->mm;
1130         struct vm_area_struct *vma;
1131         unsigned long addr = (unsigned long)shmaddr;
1132         int retval = -EINVAL;
1133 #ifdef CONFIG_MMU
1134         loff_t size = 0;
1135         struct vm_area_struct *next;
1136 #endif
1137
1138         if (addr & ~PAGE_MASK)
1139                 return retval;
1140
1141         down_write(&mm->mmap_sem);
1142
1143         /*
1144          * This function tries to be smart and unmap shm segments that
1145          * were modified by partial mlock or munmap calls:
1146          * - It first determines the size of the shm segment that should be
1147          *   unmapped: It searches for a vma that is backed by shm and that
1148          *   started at address shmaddr. It records it's size and then unmaps
1149          *   it.
1150          * - Then it unmaps all shm vmas that started at shmaddr and that
1151          *   are within the initially determined size.
1152          * Errors from do_munmap are ignored: the function only fails if
1153          * it's called with invalid parameters or if it's called to unmap
1154          * a part of a vma. Both calls in this function are for full vmas,
1155          * the parameters are directly copied from the vma itself and always
1156          * valid - therefore do_munmap cannot fail. (famous last words?)
1157          */
1158         /*
1159          * If it had been mremap()'d, the starting address would not
1160          * match the usual checks anyway. So assume all vma's are
1161          * above the starting address given.
1162          */
1163         vma = find_vma(mm, addr);
1164
1165 #ifdef CONFIG_MMU
1166         while (vma) {
1167                 next = vma->vm_next;
1168
1169                 /*
1170                  * Check if the starting address would match, i.e. it's
1171                  * a fragment created by mprotect() and/or munmap(), or it
1172                  * otherwise it starts at this address with no hassles.
1173                  */
1174                 if ((vma->vm_ops == &shm_vm_ops) &&
1175                         (vma->vm_start - addr)/PAGE_SIZE == vma->vm_pgoff) {
1176
1177
1178                         size = vma->vm_file->f_path.dentry->d_inode->i_size;
1179                         do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start);
1180                         /*
1181                          * We discovered the size of the shm segment, so
1182                          * break out of here and fall through to the next
1183                          * loop that uses the size information to stop
1184                          * searching for matching vma's.
1185                          */
1186                         retval = 0;
1187                         vma = next;
1188                         break;
1189                 }
1190                 vma = next;
1191         }
1192
1193         /*
1194          * We need look no further than the maximum address a fragment
1195          * could possibly have landed at. Also cast things to loff_t to
1196          * prevent overflows and make comparisons vs. equal-width types.
1197          */
1198         size = PAGE_ALIGN(size);
1199         while (vma && (loff_t)(vma->vm_end - addr) <= size) {
1200                 next = vma->vm_next;
1201
1202                 /* finding a matching vma now does not alter retval */
1203                 if ((vma->vm_ops == &shm_vm_ops) &&
1204                         (vma->vm_start - addr)/PAGE_SIZE == vma->vm_pgoff)
1205
1206                         do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start);
1207                 vma = next;
1208         }
1209
1210 #else /* CONFIG_MMU */
1211         /* under NOMMU conditions, the exact address to be destroyed must be
1212          * given */
1213         retval = -EINVAL;
1214         if (vma->vm_start == addr && vma->vm_ops == &shm_vm_ops) {
1215                 do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start);
1216                 retval = 0;
1217         }
1218
1219 #endif
1220
1221         up_write(&mm->mmap_sem);
1222         return retval;
1223 }
1224
1225 #ifdef CONFIG_PROC_FS
1226 static int sysvipc_shm_proc_show(struct seq_file *s, void *it)
1227 {
1228         struct user_namespace *user_ns = seq_user_ns(s);
1229         struct shmid_kernel *shp = it;
1230         unsigned long rss = 0, swp = 0;
1231
1232         shm_add_rss_swap(shp, &rss, &swp);
1233
1234 #if BITS_PER_LONG <= 32
1235 #define SIZE_SPEC "%10lu"
1236 #else
1237 #define SIZE_SPEC "%21lu"
1238 #endif
1239
1240         return seq_printf(s,
1241                           "%10d %10d  %4o " SIZE_SPEC " %5u %5u  "
1242                           "%5lu %5u %5u %5u %5u %10lu %10lu %10lu "
1243                           SIZE_SPEC " " SIZE_SPEC "\n",
1244                           shp->shm_perm.key,
1245                           shp->shm_perm.id,
1246                           shp->shm_perm.mode,
1247                           shp->shm_segsz,
1248                           shp->shm_cprid,
1249                           shp->shm_lprid,
1250                           shp->shm_nattch,
1251                           from_kuid_munged(user_ns, shp->shm_perm.uid),
1252                           from_kgid_munged(user_ns, shp->shm_perm.gid),
1253                           from_kuid_munged(user_ns, shp->shm_perm.cuid),
1254                           from_kgid_munged(user_ns, shp->shm_perm.cgid),
1255                           shp->shm_atim,
1256                           shp->shm_dtim,
1257                           shp->shm_ctim,
1258                           rss * PAGE_SIZE,
1259                           swp * PAGE_SIZE);
1260 }
1261 #endif