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         } else {
 500                 /*
 501                  * Do not allow no accounting for OVERCOMMIT_NEVER, even
 502                  * if it's asked for.
 503                  */
 504                 if  ((shmflg & SHM_NORESERVE) &&
 505                                 sysctl_overcommit_memory != OVERCOMMIT_NEVER)
 506                         acctflag = VM_NORESERVE;
 507                 file = shmem_file_setup(name, size, acctflag);
 508         }
 509         error = PTR_ERR(file);
 510         if (IS_ERR(file))
 511                 goto no_file;
 512
 513         id = ipc_addid(&shm_ids(ns), &shp->shm_perm, ns->shm_ctlmni);
 514         if (id < 0) {
 515                 error = id;
 516                 goto no_id;
 517         }
 518
 519         shp->shm_cprid = task_tgid_vnr(current);
 520         shp->shm_lprid = 0;
 521         shp->shm_atim = shp->shm_dtim = 0;
 522         shp->shm_ctim = get_seconds();
 523         shp->shm_segsz = size;
 524         shp->shm_nattch = 0;
 525         shp->shm_file = file;
 526         shp->shm_creator = current;
 527         /*
 528          * shmid gets reported as "inode#" in /proc/pid/maps.
 529          * proc-ps tools use this. Changing this will break them.
 530          */
 531         file->f_dentry->d_inode->i_ino = shp->shm_perm.id;
 532
 533         ns->shm_tot += numpages;
 534         error = shp->shm_perm.id;
 535         shm_unlock(shp);
 536         return error;
 537
 538 no_id:
 539         if (is_file_hugepages(file) && shp->mlock_user)
 540                 user_shm_unlock(size, shp->mlock_user);
 541         fput(file);
 542 no_file:
 543         security_shm_free(shp);
 544         ipc_rcu_putref(shp);
 545         return error;
 546 }
 547
 548 /*
 549  * Called with shm_ids.rw_mutex and ipcp locked.
 550  */
 551 static inline int shm_security(struct kern_ipc_perm *ipcp, int shmflg)
 552 {
 553         struct shmid_kernel *shp;
 554
 555         shp = container_of(ipcp, struct shmid_kernel, shm_perm);
 556         return security_shm_associate(shp, shmflg);
 557 }
 558
 559 /*
 560  * Called with shm_ids.rw_mutex and ipcp locked.
 561  */
 562 static inline int shm_more_checks(struct kern_ipc_perm *ipcp,
 563                                 struct ipc_params *params)
 564 {
 565         struct shmid_kernel *shp;
 566
 567         shp = container_of(ipcp, struct shmid_kernel, shm_perm);
 568         if (shp->shm_segsz < params->u.size)
 569                 return -EINVAL;
 570
 571         return 0;
 572 }
 573
 574 SYSCALL_DEFINE3(shmget, key_t, key, size_t, size, int, shmflg)
 575 {
 576         struct ipc_namespace *ns;
 577         struct ipc_ops shm_ops;
 578         struct ipc_params shm_params;
 579
 580         ns = current->nsproxy->ipc_ns;
 581
 582         shm_ops.getnew = newseg;
 583         shm_ops.associate = shm_security;
 584         shm_ops.more_checks = shm_more_checks;
 585
 586         shm_params.key = key;
 587         shm_params.flg = shmflg;
 588         shm_params.u.size = size;
 589
 590         return ipcget(ns, &shm_ids(ns), &shm_ops, &shm_params);
 591 }
 592
 593 static inline unsigned long copy_shmid_to_user(void __user *buf, struct shmid64_ds *in, int version)
 594 {
 595         switch(version) {
 596         case IPC_64:
 597                 return copy_to_user(buf, in, sizeof(*in));
 598         case IPC_OLD:
 599             {
 600                 struct shmid_ds out;
 601
 602                 memset(&out, 0, sizeof(out));
 603                 ipc64_perm_to_ipc_perm(&in->shm_perm, &out.shm_perm);
 604                 out.shm_segsz   = in->shm_segsz;
 605                 out.shm_atime   = in->shm_atime;
 606                 out.shm_dtime   = in->shm_dtime;
 607                 out.shm_ctime   = in->shm_ctime;
 608                 out.shm_cpid    = in->shm_cpid;
 609                 out.shm_lpid    = in->shm_lpid;
 610                 out.shm_nattch  = in->shm_nattch;
 611
 612                 return copy_to_user(buf, &out, sizeof(out));
 613             }
 614         default:
 615                 return -EINVAL;
 616         }
 617 }
 618
 619 static inline unsigned long
 620 copy_shmid_from_user(struct shmid64_ds *out, void __user *buf, int version)
 621 {
 622         switch(version) {
 623         case IPC_64:
 624                 if (copy_from_user(out, buf, sizeof(*out)))
 625                         return -EFAULT;
 626                 return 0;
 627         case IPC_OLD:
 628             {
 629                 struct shmid_ds tbuf_old;
 630
 631                 if (copy_from_user(&tbuf_old, buf, sizeof(tbuf_old)))
 632                         return -EFAULT;
 633
 634                 out->shm_perm.uid       = tbuf_old.shm_perm.uid;
 635                 out->shm_perm.gid       = tbuf_old.shm_perm.gid;
 636                 out->shm_perm.mode      = tbuf_old.shm_perm.mode;
 637
 638                 return 0;
 639             }
 640         default:
 641                 return -EINVAL;
 642         }
 643 }
 644
 645 static inline unsigned long copy_shminfo_to_user(void __user *buf, struct shminfo64 *in, int version)
 646 {
 647         switch(version) {
 648         case IPC_64:
 649                 return copy_to_user(buf, in, sizeof(*in));
 650         case IPC_OLD:
 651             {
 652                 struct shminfo out;
 653
 654                 if(in->shmmax > INT_MAX)
 655                         out.shmmax = INT_MAX;
 656                 else
 657                         out.shmmax = (int)in->shmmax;
 658
 659                 out.shmmin      = in->shmmin;
 660                 out.shmmni      = in->shmmni;
 661                 out.shmseg      = in->shmseg;
 662                 out.shmall      = in->shmall;
 663
 664                 return copy_to_user(buf, &out, sizeof(out));
 665             }
 666         default:
 667                 return -EINVAL;
 668         }
 669 }
 670
 671 /*
 672  * Calculate and add used RSS and swap pages of a shm.
 673  * Called with shm_ids.rw_mutex held as a reader
 674  */
 675 static void shm_add_rss_swap(struct shmid_kernel *shp,
 676         unsigned long *rss_add, unsigned long *swp_add)
 677 {
 678         struct inode *inode;
 679
 680         inode = shp->shm_file->f_path.dentry->d_inode;
 681
 682         if (is_file_hugepages(shp->shm_file)) {
 683                 struct address_space *mapping = inode->i_mapping;
 684                 struct hstate *h = hstate_file(shp->shm_file);
 685                 *rss_add += pages_per_huge_page(h) * mapping->nrpages;
 686         } else {
 687 #ifdef CONFIG_SHMEM
 688                 struct shmem_inode_info *info = SHMEM_I(inode);
 689                 spin_lock(&info->lock);
 690                 *rss_add += inode->i_mapping->nrpages;
 691                 *swp_add += info->swapped;
 692                 spin_unlock(&info->lock);
 693 #else
 694                 *rss_add += inode->i_mapping->nrpages;
 695 #endif
 696         }
 697 }
 698
 699 /*
 700  * Called with shm_ids.rw_mutex held as a reader
 701  */
 702 static void shm_get_stat(struct ipc_namespace *ns, unsigned long *rss,
 703                 unsigned long *swp)
 704 {
 705         int next_id;
 706         int total, in_use;
 707
 708         *rss = 0;
 709         *swp = 0;
 710
 711         in_use = shm_ids(ns).in_use;
 712
 713         for (total = 0, next_id = 0; total < in_use; next_id++) {
 714                 struct kern_ipc_perm *ipc;
 715                 struct shmid_kernel *shp;
 716
 717                 ipc = idr_find(&shm_ids(ns).ipcs_idr, next_id);
 718                 if (ipc == NULL)
 719                         continue;
 720                 shp = container_of(ipc, struct shmid_kernel, shm_perm);
 721
 722                 shm_add_rss_swap(shp, rss, swp);
 723
 724                 total++;
 725         }
 726 }
 727
 728 /*
 729  * This function handles some shmctl commands which require the rw_mutex
 730  * to be held in write mode.
 731  * NOTE: no locks must be held, the rw_mutex is taken inside this function.
 732  */
 733 static int shmctl_down(struct ipc_namespace *ns, int shmid, int cmd,
 734                        struct shmid_ds __user *buf, int version)
 735 {
 736         struct kern_ipc_perm *ipcp;
 737         struct shmid64_ds shmid64;
 738         struct shmid_kernel *shp;
 739         int err;
 740
 741         if (cmd == IPC_SET) {
 742                 if (copy_shmid_from_user(&shmid64, buf, version))
 743                         return -EFAULT;
 744         }
 745
 746         ipcp = ipcctl_pre_down(ns, &shm_ids(ns), shmid, cmd,
 747                                &shmid64.shm_perm, 0);
 748         if (IS_ERR(ipcp))
 749                 return PTR_ERR(ipcp);
 750
 751         shp = container_of(ipcp, struct shmid_kernel, shm_perm);
 752
 753         err = security_shm_shmctl(shp, cmd);
 754         if (err)
 755                 goto out_unlock;
 756         switch (cmd) {
 757         case IPC_RMID:
 758                 do_shm_rmid(ns, ipcp);
 759                 goto out_up;
 760         case IPC_SET:
 761                 ipc_update_perm(&shmid64.shm_perm, ipcp);
 762                 shp->shm_ctim = get_seconds();
 763                 break;
 764         default:
 765                 err = -EINVAL;
 766         }
 767 out_unlock:
 768         shm_unlock(shp);
 769 out_up:
 770         up_write(&shm_ids(ns).rw_mutex);
 771         return err;
 772 }
 773
 774 SYSCALL_DEFINE3(shmctl, int, shmid, int, cmd, struct shmid_ds __user *, buf)
 775 {
 776         struct shmid_kernel *shp;
 777         int err, version;
 778         struct ipc_namespace *ns;
 779
 780         if (cmd < 0 || shmid < 0) {
 781                 err = -EINVAL;
 782                 goto out;
 783         }
 784
 785         version = ipc_parse_version(&cmd);
 786         ns = current->nsproxy->ipc_ns;
 787
 788         switch (cmd) { /* replace with proc interface ? */
 789         case IPC_INFO:
 790         {
 791                 struct shminfo64 shminfo;
 792
 793                 err = security_shm_shmctl(NULL, cmd);
 794                 if (err)
 795                         return err;
 796
 797                 memset(&shminfo, 0, sizeof(shminfo));
 798                 shminfo.shmmni = shminfo.shmseg = ns->shm_ctlmni;
 799                 shminfo.shmmax = ns->shm_ctlmax;
 800                 shminfo.shmall = ns->shm_ctlall;
 801
 802                 shminfo.shmmin = SHMMIN;
 803                 if(copy_shminfo_to_user (buf, &shminfo, version))
 804                         return -EFAULT;
 805
 806                 down_read(&shm_ids(ns).rw_mutex);
 807                 err = ipc_get_maxid(&shm_ids(ns));
 808                 up_read(&shm_ids(ns).rw_mutex);
 809
 810                 if(err<0)
 811                         err = 0;
 812                 goto out;
 813         }
 814         case SHM_INFO:
 815         {
 816                 struct shm_info shm_info;
 817
 818                 err = security_shm_shmctl(NULL, cmd);
 819                 if (err)
 820                         return err;
 821
 822                 memset(&shm_info, 0, sizeof(shm_info));
 823                 down_read(&shm_ids(ns).rw_mutex);
 824                 shm_info.used_ids = shm_ids(ns).in_use;
 825                 shm_get_stat (ns, &shm_info.shm_rss, &shm_info.shm_swp);
 826                 shm_info.shm_tot = ns->shm_tot;
 827                 shm_info.swap_attempts = 0;
 828                 shm_info.swap_successes = 0;
 829                 err = ipc_get_maxid(&shm_ids(ns));
 830                 up_read(&shm_ids(ns).rw_mutex);
 831                 if (copy_to_user(buf, &shm_info, sizeof(shm_info))) {
 832                         err = -EFAULT;
 833                         goto out;
 834                 }
 835
 836                 err = err < 0 ? 0 : err;
 837                 goto out;
 838         }
 839         case SHM_STAT:
 840         case IPC_STAT:
 841         {
 842                 struct shmid64_ds tbuf;
 843                 int result;
 844
 845                 if (cmd == SHM_STAT) {
 846                         shp = shm_lock(ns, shmid);
 847                         if (IS_ERR(shp)) {
 848                                 err = PTR_ERR(shp);
 849                                 goto out;
 850                         }
 851                         result = shp->shm_perm.id;
 852                 } else {
 853                         shp = shm_lock_check(ns, shmid);
 854                         if (IS_ERR(shp)) {
 855                                 err = PTR_ERR(shp);
 856                                 goto out;
 857                         }
 858                         result = 0;
 859                 }
 860                 err = -EACCES;
 861                 if (ipcperms(ns, &shp->shm_perm, S_IRUGO))
 862                         goto out_unlock;
 863                 err = security_shm_shmctl(shp, cmd);
 864                 if (err)
 865                         goto out_unlock;
 866                 memset(&tbuf, 0, sizeof(tbuf));
 867                 kernel_to_ipc64_perm(&shp->shm_perm, &tbuf.shm_perm);
 868                 tbuf.shm_segsz  = shp->shm_segsz;
 869                 tbuf.shm_atime  = shp->shm_atim;
 870                 tbuf.shm_dtime  = shp->shm_dtim;
 871                 tbuf.shm_ctime  = shp->shm_ctim;
 872                 tbuf.shm_cpid   = shp->shm_cprid;
 873                 tbuf.shm_lpid   = shp->shm_lprid;
 874                 tbuf.shm_nattch = shp->shm_nattch;
 875                 shm_unlock(shp);
 876                 if(copy_shmid_to_user (buf, &tbuf, version))
 877                         err = -EFAULT;
 878                 else
 879                         err = result;
 880                 goto out;
 881         }
 882         case SHM_LOCK:
 883         case SHM_UNLOCK:
 884         {
 885                 struct file *shm_file;
 886
 887                 shp = shm_lock_check(ns, shmid);
 888                 if (IS_ERR(shp)) {
 889                         err = PTR_ERR(shp);
 890                         goto out;
 891                 }
 892
 893                 audit_ipc_obj(&(shp->shm_perm));
 894
 895                 if (!ns_capable(ns->user_ns, CAP_IPC_LOCK)) {
 896                         uid_t euid = current_euid();
 897                         err = -EPERM;
 898                         if (euid != shp->shm_perm.uid &&
 899                             euid != shp->shm_perm.cuid)
 900                                 goto out_unlock;
 901                         if (cmd == SHM_LOCK && !rlimit(RLIMIT_MEMLOCK))
 902                                 goto out_unlock;
 903                 }
 904
 905                 err = security_shm_shmctl(shp, cmd);
 906                 if (err)
 907                         goto out_unlock;
 908
 909                 shm_file = shp->shm_file;
 910                 if (is_file_hugepages(shm_file))
 911                         goto out_unlock;
 912
 913                 if (cmd == SHM_LOCK) {
 914                         struct user_struct *user = current_user();
 915                         err = shmem_lock(shm_file, 1, user);
 916                         if (!err && !(shp->shm_perm.mode & SHM_LOCKED)) {
 917                                 shp->shm_perm.mode |= SHM_LOCKED;
 918                                 shp->mlock_user = user;
 919                         }
 920                         goto out_unlock;
 921                 }
 922
 923                 /* SHM_UNLOCK */
 924                 if (!(shp->shm_perm.mode & SHM_LOCKED))
 925                         goto out_unlock;
 926                 shmem_lock(shm_file, 0, shp->mlock_user);
 927                 shp->shm_perm.mode &= ~SHM_LOCKED;
 928                 shp->mlock_user = NULL;
 929                 get_file(shm_file);
 930                 shm_unlock(shp);
 931                 shmem_unlock_mapping(shm_file->f_mapping);
 932                 fput(shm_file);
 933                 goto out;
 934         }
 935         case IPC_RMID:
 936         case IPC_SET:
 937                 err = shmctl_down(ns, shmid, cmd, buf, version);
 938                 return err;
 939         default:
 940                 return -EINVAL;
 941         }
 942
 943 out_unlock:
 944         shm_unlock(shp);
 945 out:
 946         return err;
 947 }
 948
 949 /*
 950  * Fix shmaddr, allocate descriptor, map shm, add attach descriptor to lists.
 951  *
 952  * NOTE! Despite the name, this is NOT a direct system call entrypoint. The
 953  * "raddr" thing points to kernel space, and there has to be a wrapper around
 954  * this.
 955  */
 956 long do_shmat(int shmid, char __user *shmaddr, int shmflg, ulong *raddr)
 957 {
 958         struct shmid_kernel *shp;
 959         unsigned long addr;
 960         unsigned long size;
 961         struct file * file;
 962         int    err;
 963         unsigned long flags;
 964         unsigned long prot;
 965         int acc_mode;
 966         unsigned long user_addr;
 967         struct ipc_namespace *ns;
 968         struct shm_file_data *sfd;
 969         struct path path;
 970         fmode_t f_mode;
 971
 972         err = -EINVAL;
 973         if (shmid < 0)
 974                 goto out;
 975         else if ((addr = (ulong)shmaddr)) {
 976                 if (addr & (SHMLBA-1)) {
 977                         if (shmflg & SHM_RND)
 978                                 addr &= ~(SHMLBA-1);       /* round down */
 979                         else
 980 #ifndef __ARCH_FORCE_SHMLBA
 981                                 if (addr & ~PAGE_MASK)
 982 #endif
 983                                         goto out;
 984                 }
 985                 flags = MAP_SHARED | MAP_FIXED;
 986         } else {
 987                 if ((shmflg & SHM_REMAP))
 988                         goto out;
 989
 990                 flags = MAP_SHARED;
 991         }
 992
 993         if (shmflg & SHM_RDONLY) {
 994                 prot = PROT_READ;
 995                 acc_mode = S_IRUGO;
 996                 f_mode = FMODE_READ;
 997         } else {
 998                 prot = PROT_READ | PROT_WRITE;
 999                 acc_mode = S_IRUGO | S_IWUGO;
1000                 f_mode = FMODE_READ | FMODE_WRITE;
1001         }
1002         if (shmflg & SHM_EXEC) {
1003                 prot |= PROT_EXEC;
1004                 acc_mode |= S_IXUGO;
1005         }
1006
1007         /*
1008          * We cannot rely on the fs check since SYSV IPC does have an
1009          * additional creator id...
1010          */
1011         ns = current->nsproxy->ipc_ns;
1012         shp = shm_lock_check(ns, shmid);
1013         if (IS_ERR(shp)) {
1014                 err = PTR_ERR(shp);
1015                 goto out;
1016         }
1017
1018         err = -EACCES;
1019         if (ipcperms(ns, &shp->shm_perm, acc_mode))
1020                 goto out_unlock;
1021
1022         err = security_shm_shmat(shp, shmaddr, shmflg);
1023         if (err)
1024                 goto out_unlock;
1025
1026         path = shp->shm_file->f_path;
1027         path_get(&path);
1028         shp->shm_nattch++;
1029         size = i_size_read(path.dentry->d_inode);
1030         shm_unlock(shp);
1031
1032         err = -ENOMEM;
1033         sfd = kzalloc(sizeof(*sfd), GFP_KERNEL);
1034         if (!sfd)
1035                 goto out_put_dentry;
1036
1037         file = alloc_file(&path, f_mode,
1038                           is_file_hugepages(shp->shm_file) ?
1039                                 &shm_file_operations_huge :
1040                                 &shm_file_operations);
1041         if (!file)
1042                 goto out_free;
1043
1044         file->private_data = sfd;
1045         file->f_mapping = shp->shm_file->f_mapping;
1046         sfd->id = shp->shm_perm.id;
1047         sfd->ns = get_ipc_ns(ns);
1048         sfd->file = shp->shm_file;
1049         sfd->vm_ops = NULL;
1050
1051         err = security_mmap_file(file, prot, flags);
1052         if (err)
1053                 goto out_fput;
1054
1055         down_write(&current->mm->mmap_sem);
1056         if (addr && !(shmflg & SHM_REMAP)) {
1057                 err = -EINVAL;
1058                 if (find_vma_intersection(current->mm, addr, addr + size))
1059                         goto invalid;
1060                 /*
1061                  * If shm segment goes below stack, make sure there is some
1062                  * space left for the stack to grow (at least 4 pages).
1063                  */
1064                 if (addr < current->mm->start_stack &&
1065                     addr > current->mm->start_stack - size - PAGE_SIZE * 5)
1066                         goto invalid;
1067         }
1068
1069         user_addr = do_mmap_pgoff(file, addr, size, prot, flags, 0);
1070         *raddr = user_addr;
1071         err = 0;
1072         if (IS_ERR_VALUE(user_addr))
1073                 err = (long)user_addr;
1074 invalid:
1075         up_write(&current->mm->mmap_sem);
1076
1077 out_fput:
1078         fput(file);
1079
1080 out_nattch:
1081         down_write(&shm_ids(ns).rw_mutex);
1082         shp = shm_lock(ns, shmid);
1083         BUG_ON(IS_ERR(shp));
1084         shp->shm_nattch--;
1085         if (shm_may_destroy(ns, shp))
1086                 shm_destroy(ns, shp);
1087         else
1088                 shm_unlock(shp);
1089         up_write(&shm_ids(ns).rw_mutex);
1090
1091 out:
1092         return err;
1093
1094 out_unlock:
1095         shm_unlock(shp);
1096         goto out;
1097
1098 out_free:
1099         kfree(sfd);
1100 out_put_dentry:
1101         path_put(&path);
1102         goto out_nattch;
1103 }
1104
1105 SYSCALL_DEFINE3(shmat, int, shmid, char __user *, shmaddr, int, shmflg)
1106 {
1107         unsigned long ret;
1108         long err;
1109
1110         err = do_shmat(shmid, shmaddr, shmflg, &ret);
1111         if (err)
1112                 return err;
1113         force_successful_syscall_return();
1114         return (long)ret;
1115 }
1116
1117 /*
1118  * detach and kill segment if marked destroyed.
1119  * The work is done in shm_close.
1120  */
1121 SYSCALL_DEFINE1(shmdt, char __user *, shmaddr)
1122 {
1123         struct mm_struct *mm = current->mm;
1124         struct vm_area_struct *vma;
1125         unsigned long addr = (unsigned long)shmaddr;
1126         int retval = -EINVAL;
1127 #ifdef CONFIG_MMU
1128         loff_t size = 0;
1129         struct vm_area_struct *next;
1130 #endif
1131
1132         if (addr & ~PAGE_MASK)
1133                 return retval;
1134
1135         down_write(&mm->mmap_sem);
1136
1137         /*
1138          * This function tries to be smart and unmap shm segments that
1139          * were modified by partial mlock or munmap calls:
1140          * - It first determines the size of the shm segment that should be
1141          *   unmapped: It searches for a vma that is backed by shm and that
1142          *   started at address shmaddr. It records it's size and then unmaps
1143          *   it.
1144          * - Then it unmaps all shm vmas that started at shmaddr and that
1145          *   are within the initially determined size.
1146          * Errors from do_munmap are ignored: the function only fails if
1147          * it's called with invalid parameters or if it's called to unmap
1148          * a part of a vma. Both calls in this function are for full vmas,
1149          * the parameters are directly copied from the vma itself and always
1150          * valid - therefore do_munmap cannot fail. (famous last words?)
1151          */
1152         /*
1153          * If it had been mremap()'d, the starting address would not
1154          * match the usual checks anyway. So assume all vma's are
1155          * above the starting address given.
1156          */
1157         vma = find_vma(mm, addr);
1158
1159 #ifdef CONFIG_MMU
1160         while (vma) {
1161                 next = vma->vm_next;
1162
1163                 /*
1164                  * Check if the starting address would match, i.e. it's
1165                  * a fragment created by mprotect() and/or munmap(), or it
1166                  * otherwise it starts at this address with no hassles.
1167                  */
1168                 if ((vma->vm_ops == &shm_vm_ops) &&
1169                         (vma->vm_start - addr)/PAGE_SIZE == vma->vm_pgoff) {
1170
1171
1172                         size = vma->vm_file->f_path.dentry->d_inode->i_size;
1173                         do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start);
1174                         /*
1175                          * We discovered the size of the shm segment, so
1176                          * break out of here and fall through to the next
1177                          * loop that uses the size information to stop
1178                          * searching for matching vma's.
1179                          */
1180                         retval = 0;
1181                         vma = next;
1182                         break;
1183                 }
1184                 vma = next;
1185         }
1186
1187         /*
1188          * We need look no further than the maximum address a fragment
1189          * could possibly have landed at. Also cast things to loff_t to
1190          * prevent overflows and make comparisons vs. equal-width types.
1191          */
1192         size = PAGE_ALIGN(size);
1193         while (vma && (loff_t)(vma->vm_end - addr) <= size) {
1194                 next = vma->vm_next;
1195
1196                 /* finding a matching vma now does not alter retval */
1197                 if ((vma->vm_ops == &shm_vm_ops) &&
1198                         (vma->vm_start - addr)/PAGE_SIZE == vma->vm_pgoff)
1199
1200                         do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start);
1201                 vma = next;
1202         }
1203
1204 #else /* CONFIG_MMU */
1205         /* under NOMMU conditions, the exact address to be destroyed must be
1206          * given */
1207         retval = -EINVAL;
1208         if (vma->vm_start == addr && vma->vm_ops == &shm_vm_ops) {
1209                 do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start);
1210                 retval = 0;
1211         }
1212
1213 #endif
1214
1215         up_write(&mm->mmap_sem);
1216         return retval;
1217 }
1218
1219 #ifdef CONFIG_PROC_FS
1220 static int sysvipc_shm_proc_show(struct seq_file *s, void *it)
1221 {
1222         struct shmid_kernel *shp = it;
1223         unsigned long rss = 0, swp = 0;
1224
1225         shm_add_rss_swap(shp, &rss, &swp);
1226
1227 #if BITS_PER_LONG <= 32
1228 #define SIZE_SPEC "%10lu"
1229 #else
1230 #define SIZE_SPEC "%21lu"
1231 #endif
1232
1233         return seq_printf(s,
1234                           "%10d %10d  %4o " SIZE_SPEC " %5u %5u  "
1235                           "%5lu %5u %5u %5u %5u %10lu %10lu %10lu "
1236                           SIZE_SPEC " " SIZE_SPEC "\n",
1237                           shp->shm_perm.key,
1238                           shp->shm_perm.id,
1239                           shp->shm_perm.mode,
1240                           shp->shm_segsz,
1241                           shp->shm_cprid,
1242                           shp->shm_lprid,
1243                           shp->shm_nattch,
1244                           shp->shm_perm.uid,
1245                           shp->shm_perm.gid,
1246                           shp->shm_perm.cuid,
1247                           shp->shm_perm.cgid,
1248                           shp->shm_atim,
1249                           shp->shm_dtim,
1250                           shp->shm_ctim,
1251                           rss * PAGE_SIZE,
1252                           swp * PAGE_SIZE);
1253 }
1254 #endif