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
  20 #include <linux/slab.h>
  21 #include <linux/mm.h>
  22 #include <linux/hugetlb.h>
  23 #include <linux/shm.h>
  24 #include <linux/init.h>
  25 #include <linux/file.h>
  26 #include <linux/mman.h>
  27 #include <linux/shmem_fs.h>
  28 #include <linux/security.h>
  29 #include <linux/syscalls.h>
  30 #include <linux/audit.h>
  31 #include <linux/capability.h>
  32 #include <linux/ptrace.h>
  33 #include <linux/seq_file.h>
  34 #include <linux/mutex.h>
  35
  36 #include <asm/uaccess.h>
  37
  38 #include "util.h"
  39
  40 static struct file_operations shm_file_operations;
  41 static struct vm_operations_struct shm_vm_ops;
  42
  43 static struct ipc_ids shm_ids;
  44
  45 #define shm_lock(id)    ((struct shmid_kernel*)ipc_lock(&shm_ids,id))
  46 #define shm_unlock(shp) ipc_unlock(&(shp)->shm_perm)
  47 #define shm_get(id)     ((struct shmid_kernel*)ipc_get(&shm_ids,id))
  48 #define shm_buildid(id, seq) \
  49         ipc_buildid(&shm_ids, id, seq)
  50
  51 static int newseg (key_t key, int shmflg, size_t size);
  52 static void shm_open (struct vm_area_struct *shmd);
  53 static void shm_close (struct vm_area_struct *shmd);
  54 #ifdef CONFIG_PROC_FS
  55 static int sysvipc_shm_proc_show(struct seq_file *s, void *it);
  56 #endif
  57
  58 size_t  shm_ctlmax = SHMMAX;
  59 size_t  shm_ctlall = SHMALL;
  60 int     shm_ctlmni = SHMMNI;
  61
  62 static int shm_tot; /* total number of shared memory pages */
  63
  64 void __init shm_init (void)
  65 {
  66         ipc_init_ids(&shm_ids, 1);
  67         ipc_init_proc_interface("sysvipc/shm",
  68                                 "       key      shmid perms       size  cpid  lpid nattch   uid   gid  cuid  cgid      atime      dtime      ctime\n",
  69                                 &shm_ids,
  70                                 sysvipc_shm_proc_show);
  71 }
  72
  73 static inline int shm_checkid(struct shmid_kernel *s, int id)
  74 {
  75         if (ipc_checkid(&shm_ids,&s->shm_perm,id))
  76                 return -EIDRM;
  77         return 0;
  78 }
  79
  80 static inline struct shmid_kernel *shm_rmid(int id)
  81 {
  82         return (struct shmid_kernel *)ipc_rmid(&shm_ids,id);
  83 }
  84
  85 static inline int shm_addid(struct shmid_kernel *shp)
  86 {
  87         return ipc_addid(&shm_ids, &shp->shm_perm, shm_ctlmni);
  88 }
  89
  90
  91
  92 static inline void shm_inc (int id) {
  93         struct shmid_kernel *shp;
  94
  95         shp = shm_lock(id);
  96         BUG_ON(!shp);
  97         shp->shm_atim = get_seconds();
  98         shp->shm_lprid = current->tgid;
  99         shp->shm_nattch++;
 100         shm_unlock(shp);
 101 }
 102
 103 /* This is called by fork, once for every shm attach. */
 104 static void shm_open (struct vm_area_struct *shmd)
 105 {
 106         shm_inc (shmd->vm_file->f_dentry->d_inode->i_ino);
 107 }
 108
 109 /*
 110  * shm_destroy - free the struct shmid_kernel
 111  *
 112  * @shp: struct to free
 113  *
 114  * It has to be called with shp and shm_ids.mutex locked,
 115  * but returns with shp unlocked and freed.
 116  */
 117 static void shm_destroy (struct shmid_kernel *shp)
 118 {
 119         shm_tot -= (shp->shm_segsz + PAGE_SIZE - 1) >> PAGE_SHIFT;
 120         shm_rmid (shp->id);
 121         shm_unlock(shp);
 122         if (!is_file_hugepages(shp->shm_file))
 123                 shmem_lock(shp->shm_file, 0, shp->mlock_user);
 124         else
 125                 user_shm_unlock(shp->shm_file->f_dentry->d_inode->i_size,
 126                                                 shp->mlock_user);
 127         fput (shp->shm_file);
 128         security_shm_free(shp);
 129         ipc_rcu_putref(shp);
 130 }
 131
 132 /*
 133  * remove the attach descriptor shmd.
 134  * free memory for segment if it is marked destroyed.
 135  * The descriptor has already been removed from the current->mm->mmap list
 136  * and will later be kfree()d.
 137  */
 138 static void shm_close (struct vm_area_struct *shmd)
 139 {
 140         struct file * file = shmd->vm_file;
 141         int id = file->f_dentry->d_inode->i_ino;
 142         struct shmid_kernel *shp;
 143
 144         mutex_lock(&shm_ids.mutex);
 145         /* remove from the list of attaches of the shm segment */
 146         shp = shm_lock(id);
 147         BUG_ON(!shp);
 148         shp->shm_lprid = current->tgid;
 149         shp->shm_dtim = get_seconds();
 150         shp->shm_nattch--;
 151         if(shp->shm_nattch == 0 &&
 152            shp->shm_perm.mode & SHM_DEST)
 153                 shm_destroy (shp);
 154         else
 155                 shm_unlock(shp);
 156         mutex_unlock(&shm_ids.mutex);
 157 }
 158
 159 static int shm_mmap(struct file * file, struct vm_area_struct * vma)
 160 {
 161         int ret;
 162
 163         ret = shmem_mmap(file, vma);
 164         if (ret == 0) {
 165                 vma->vm_ops = &shm_vm_ops;
 166                 if (!(vma->vm_flags & VM_WRITE))
 167                         vma->vm_flags &= ~VM_MAYWRITE;
 168                 shm_inc(file->f_dentry->d_inode->i_ino);
 169         }
 170
 171         return ret;
 172 }
 173
 174 static struct file_operations shm_file_operations = {
 175         .mmap   = shm_mmap,
 176 #ifndef CONFIG_MMU
 177         .get_unmapped_area = shmem_get_unmapped_area,
 178 #endif
 179 };
 180
 181 static struct vm_operations_struct shm_vm_ops = {
 182         .open   = shm_open,     /* callback for a new vm-area open */
 183         .close  = shm_close,    /* callback for when the vm-area is released */
 184         .nopage = shmem_nopage,
 185 #if defined(CONFIG_NUMA) && defined(CONFIG_SHMEM)
 186         .set_policy = shmem_set_policy,
 187         .get_policy = shmem_get_policy,
 188 #endif
 189 };
 190
 191 static int newseg (key_t key, int shmflg, size_t size)
 192 {
 193         int error;
 194         struct shmid_kernel *shp;
 195         int numpages = (size + PAGE_SIZE -1) >> PAGE_SHIFT;
 196         struct file * file;
 197         char name[13];
 198         int id;
 199
 200         if (size < SHMMIN || size > shm_ctlmax)
 201                 return -EINVAL;
 202
 203         if (shm_tot + numpages >= shm_ctlall)
 204                 return -ENOSPC;
 205
 206         shp = ipc_rcu_alloc(sizeof(*shp));
 207         if (!shp)
 208                 return -ENOMEM;
 209
 210         shp->shm_perm.key = key;
 211         shp->shm_perm.mode = (shmflg & S_IRWXUGO);
 212         shp->mlock_user = NULL;
 213
 214         shp->shm_perm.security = NULL;
 215         error = security_shm_alloc(shp);
 216         if (error) {
 217                 ipc_rcu_putref(shp);
 218                 return error;
 219         }
 220
 221         if (shmflg & SHM_HUGETLB) {
 222                 /* hugetlb_zero_setup takes care of mlock user accounting */
 223                 file = hugetlb_zero_setup(size);
 224                 shp->mlock_user = current->user;
 225         } else {
 226                 int acctflag = VM_ACCOUNT;
 227                 /*
 228                  * Do not allow no accounting for OVERCOMMIT_NEVER, even
 229                  * if it's asked for.
 230                  */
 231                 if  ((shmflg & SHM_NORESERVE) &&
 232                                 sysctl_overcommit_memory != OVERCOMMIT_NEVER)
 233                         acctflag = 0;
 234                 sprintf (name, "SYSV%08x", key);
 235                 file = shmem_file_setup(name, size, acctflag);
 236         }
 237         error = PTR_ERR(file);
 238         if (IS_ERR(file))
 239                 goto no_file;
 240
 241         error = -ENOSPC;
 242         id = shm_addid(shp);
 243         if(id == -1)
 244                 goto no_id;
 245
 246         shp->shm_cprid = current->tgid;
 247         shp->shm_lprid = 0;
 248         shp->shm_atim = shp->shm_dtim = 0;
 249         shp->shm_ctim = get_seconds();
 250         shp->shm_segsz = size;
 251         shp->shm_nattch = 0;
 252         shp->id = shm_buildid(id,shp->shm_perm.seq);
 253         shp->shm_file = file;
 254         file->f_dentry->d_inode->i_ino = shp->id;
 255
 256         /* Hugetlb ops would have already been assigned. */
 257         if (!(shmflg & SHM_HUGETLB))
 258                 file->f_op = &shm_file_operations;
 259
 260         shm_tot += numpages;
 261         shm_unlock(shp);
 262         return shp->id;
 263
 264 no_id:
 265         fput(file);
 266 no_file:
 267         security_shm_free(shp);
 268         ipc_rcu_putref(shp);
 269         return error;
 270 }
 271
 272 asmlinkage long sys_shmget (key_t key, size_t size, int shmflg)
 273 {
 274         struct shmid_kernel *shp;
 275         int err, id = 0;
 276
 277         mutex_lock(&shm_ids.mutex);
 278         if (key == IPC_PRIVATE) {
 279                 err = newseg(key, shmflg, size);
 280         } else if ((id = ipc_findkey(&shm_ids, key)) == -1) {
 281                 if (!(shmflg & IPC_CREAT))
 282                         err = -ENOENT;
 283                 else
 284                         err = newseg(key, shmflg, size);
 285         } else if ((shmflg & IPC_CREAT) && (shmflg & IPC_EXCL)) {
 286                 err = -EEXIST;
 287         } else {
 288                 shp = shm_lock(id);
 289                 BUG_ON(shp==NULL);
 290                 if (shp->shm_segsz < size)
 291                         err = -EINVAL;
 292                 else if (ipcperms(&shp->shm_perm, shmflg))
 293                         err = -EACCES;
 294                 else {
 295                         int shmid = shm_buildid(id, shp->shm_perm.seq);
 296                         err = security_shm_associate(shp, shmflg);
 297                         if (!err)
 298                                 err = shmid;
 299                 }
 300                 shm_unlock(shp);
 301         }
 302         mutex_unlock(&shm_ids.mutex);
 303
 304         return err;
 305 }
 306
 307 static inline unsigned long copy_shmid_to_user(void __user *buf, struct shmid64_ds *in, int version)
 308 {
 309         switch(version) {
 310         case IPC_64:
 311                 return copy_to_user(buf, in, sizeof(*in));
 312         case IPC_OLD:
 313             {
 314                 struct shmid_ds out;
 315
 316                 ipc64_perm_to_ipc_perm(&in->shm_perm, &out.shm_perm);
 317                 out.shm_segsz   = in->shm_segsz;
 318                 out.shm_atime   = in->shm_atime;
 319                 out.shm_dtime   = in->shm_dtime;
 320                 out.shm_ctime   = in->shm_ctime;
 321                 out.shm_cpid    = in->shm_cpid;
 322                 out.shm_lpid    = in->shm_lpid;
 323                 out.shm_nattch  = in->shm_nattch;
 324
 325                 return copy_to_user(buf, &out, sizeof(out));
 326             }
 327         default:
 328                 return -EINVAL;
 329         }
 330 }
 331
 332 struct shm_setbuf {
 333         uid_t   uid;
 334         gid_t   gid;
 335         mode_t  mode;
 336 };
 337
 338 static inline unsigned long copy_shmid_from_user(struct shm_setbuf *out, void __user *buf, int version)
 339 {
 340         switch(version) {
 341         case IPC_64:
 342             {
 343                 struct shmid64_ds tbuf;
 344
 345                 if (copy_from_user(&tbuf, buf, sizeof(tbuf)))
 346                         return -EFAULT;
 347
 348                 out->uid        = tbuf.shm_perm.uid;
 349                 out->gid        = tbuf.shm_perm.gid;
 350                 out->mode       = tbuf.shm_perm.mode;
 351
 352                 return 0;
 353             }
 354         case IPC_OLD:
 355             {
 356                 struct shmid_ds tbuf_old;
 357
 358                 if (copy_from_user(&tbuf_old, buf, sizeof(tbuf_old)))
 359                         return -EFAULT;
 360
 361                 out->uid        = tbuf_old.shm_perm.uid;
 362                 out->gid        = tbuf_old.shm_perm.gid;
 363                 out->mode       = tbuf_old.shm_perm.mode;
 364
 365                 return 0;
 366             }
 367         default:
 368                 return -EINVAL;
 369         }
 370 }
 371
 372 static inline unsigned long copy_shminfo_to_user(void __user *buf, struct shminfo64 *in, int version)
 373 {
 374         switch(version) {
 375         case IPC_64:
 376                 return copy_to_user(buf, in, sizeof(*in));
 377         case IPC_OLD:
 378             {
 379                 struct shminfo out;
 380
 381                 if(in->shmmax > INT_MAX)
 382                         out.shmmax = INT_MAX;
 383                 else
 384                         out.shmmax = (int)in->shmmax;
 385
 386                 out.shmmin      = in->shmmin;
 387                 out.shmmni      = in->shmmni;
 388                 out.shmseg      = in->shmseg;
 389                 out.shmall      = in->shmall;
 390
 391                 return copy_to_user(buf, &out, sizeof(out));
 392             }
 393         default:
 394                 return -EINVAL;
 395         }
 396 }
 397
 398 static void shm_get_stat(unsigned long *rss, unsigned long *swp)
 399 {
 400         int i;
 401
 402         *rss = 0;
 403         *swp = 0;
 404
 405         for (i = 0; i <= shm_ids.max_id; i++) {
 406                 struct shmid_kernel *shp;
 407                 struct inode *inode;
 408
 409                 shp = shm_get(i);
 410                 if(!shp)
 411                         continue;
 412
 413                 inode = shp->shm_file->f_dentry->d_inode;
 414
 415                 if (is_file_hugepages(shp->shm_file)) {
 416                         struct address_space *mapping = inode->i_mapping;
 417                         *rss += (HPAGE_SIZE/PAGE_SIZE)*mapping->nrpages;
 418                 } else {
 419                         struct shmem_inode_info *info = SHMEM_I(inode);
 420                         spin_lock(&info->lock);
 421                         *rss += inode->i_mapping->nrpages;
 422                         *swp += info->swapped;
 423                         spin_unlock(&info->lock);
 424                 }
 425         }
 426 }
 427
 428 asmlinkage long sys_shmctl (int shmid, int cmd, struct shmid_ds __user *buf)
 429 {
 430         struct shm_setbuf setbuf;
 431         struct shmid_kernel *shp;
 432         int err, version;
 433
 434         if (cmd < 0 || shmid < 0) {
 435                 err = -EINVAL;
 436                 goto out;
 437         }
 438
 439         version = ipc_parse_version(&cmd);
 440
 441         switch (cmd) { /* replace with proc interface ? */
 442         case IPC_INFO:
 443         {
 444                 struct shminfo64 shminfo;
 445
 446                 err = security_shm_shmctl(NULL, cmd);
 447                 if (err)
 448                         return err;
 449
 450                 memset(&shminfo,0,sizeof(shminfo));
 451                 shminfo.shmmni = shminfo.shmseg = shm_ctlmni;
 452                 shminfo.shmmax = shm_ctlmax;
 453                 shminfo.shmall = shm_ctlall;
 454
 455                 shminfo.shmmin = SHMMIN;
 456                 if(copy_shminfo_to_user (buf, &shminfo, version))
 457                         return -EFAULT;
 458                 /* reading a integer is always atomic */
 459                 err= shm_ids.max_id;
 460                 if(err<0)
 461                         err = 0;
 462                 goto out;
 463         }
 464         case SHM_INFO:
 465         {
 466                 struct shm_info shm_info;
 467
 468                 err = security_shm_shmctl(NULL, cmd);
 469                 if (err)
 470                         return err;
 471
 472                 memset(&shm_info,0,sizeof(shm_info));
 473                 mutex_lock(&shm_ids.mutex);
 474                 shm_info.used_ids = shm_ids.in_use;
 475                 shm_get_stat (&shm_info.shm_rss, &shm_info.shm_swp);
 476                 shm_info.shm_tot = shm_tot;
 477                 shm_info.swap_attempts = 0;
 478                 shm_info.swap_successes = 0;
 479                 err = shm_ids.max_id;
 480                 mutex_unlock(&shm_ids.mutex);
 481                 if(copy_to_user (buf, &shm_info, sizeof(shm_info))) {
 482                         err = -EFAULT;
 483                         goto out;
 484                 }
 485
 486                 err = err < 0 ? 0 : err;
 487                 goto out;
 488         }
 489         case SHM_STAT:
 490         case IPC_STAT:
 491         {
 492                 struct shmid64_ds tbuf;
 493                 int result;
 494                 memset(&tbuf, 0, sizeof(tbuf));
 495                 shp = shm_lock(shmid);
 496                 if(shp==NULL) {
 497                         err = -EINVAL;
 498                         goto out;
 499                 } else if(cmd==SHM_STAT) {
 500                         err = -EINVAL;
 501                         if (shmid > shm_ids.max_id)
 502                                 goto out_unlock;
 503                         result = shm_buildid(shmid, shp->shm_perm.seq);
 504                 } else {
 505                         err = shm_checkid(shp,shmid);
 506                         if(err)
 507                                 goto out_unlock;
 508                         result = 0;
 509                 }
 510                 err=-EACCES;
 511                 if (ipcperms (&shp->shm_perm, S_IRUGO))
 512                         goto out_unlock;
 513                 err = security_shm_shmctl(shp, cmd);
 514                 if (err)
 515                         goto out_unlock;
 516                 kernel_to_ipc64_perm(&shp->shm_perm, &tbuf.shm_perm);
 517                 tbuf.shm_segsz  = shp->shm_segsz;
 518                 tbuf.shm_atime  = shp->shm_atim;
 519                 tbuf.shm_dtime  = shp->shm_dtim;
 520                 tbuf.shm_ctime  = shp->shm_ctim;
 521                 tbuf.shm_cpid   = shp->shm_cprid;
 522                 tbuf.shm_lpid   = shp->shm_lprid;
 523                 if (!is_file_hugepages(shp->shm_file))
 524                         tbuf.shm_nattch = shp->shm_nattch;
 525                 else
 526                         tbuf.shm_nattch = file_count(shp->shm_file) - 1;
 527                 shm_unlock(shp);
 528                 if(copy_shmid_to_user (buf, &tbuf, version))
 529                         err = -EFAULT;
 530                 else
 531                         err = result;
 532                 goto out;
 533         }
 534         case SHM_LOCK:
 535         case SHM_UNLOCK:
 536         {
 537                 shp = shm_lock(shmid);
 538                 if(shp==NULL) {
 539                         err = -EINVAL;
 540                         goto out;
 541                 }
 542                 err = shm_checkid(shp,shmid);
 543                 if(err)
 544                         goto out_unlock;
 545
 546                 err = audit_ipc_obj(&(shp->shm_perm));
 547                 if (err)
 548                         goto out_unlock;
 549
 550                 if (!capable(CAP_IPC_LOCK)) {
 551                         err = -EPERM;
 552                         if (current->euid != shp->shm_perm.uid &&
 553                             current->euid != shp->shm_perm.cuid)
 554                                 goto out_unlock;
 555                         if (cmd == SHM_LOCK &&
 556                             !current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur)
 557                                 goto out_unlock;
 558                 }
 559
 560                 err = security_shm_shmctl(shp, cmd);
 561                 if (err)
 562                         goto out_unlock;
 563
 564                 if(cmd==SHM_LOCK) {
 565                         struct user_struct * user = current->user;
 566                         if (!is_file_hugepages(shp->shm_file)) {
 567                                 err = shmem_lock(shp->shm_file, 1, user);
 568                                 if (!err) {
 569                                         shp->shm_perm.mode |= SHM_LOCKED;
 570                                         shp->mlock_user = user;
 571                                 }
 572                         }
 573                 } else if (!is_file_hugepages(shp->shm_file)) {
 574                         shmem_lock(shp->shm_file, 0, shp->mlock_user);
 575                         shp->shm_perm.mode &= ~SHM_LOCKED;
 576                         shp->mlock_user = NULL;
 577                 }
 578                 shm_unlock(shp);
 579                 goto out;
 580         }
 581         case IPC_RMID:
 582         {
 583                 /*
 584                  *      We cannot simply remove the file. The SVID states
 585                  *      that the block remains until the last person
 586                  *      detaches from it, then is deleted. A shmat() on
 587                  *      an RMID segment is legal in older Linux and if
 588                  *      we change it apps break...
 589                  *
 590                  *      Instead we set a destroyed flag, and then blow
 591                  *      the name away when the usage hits zero.
 592                  */
 593                 mutex_lock(&shm_ids.mutex);
 594                 shp = shm_lock(shmid);
 595                 err = -EINVAL;
 596                 if (shp == NULL)
 597                         goto out_up;
 598                 err = shm_checkid(shp, shmid);
 599                 if(err)
 600                         goto out_unlock_up;
 601
 602                 err = audit_ipc_obj(&(shp->shm_perm));
 603                 if (err)
 604                         goto out_unlock_up;
 605
 606                 if (current->euid != shp->shm_perm.uid &&
 607                     current->euid != shp->shm_perm.cuid &&
 608                     !capable(CAP_SYS_ADMIN)) {
 609                         err=-EPERM;
 610                         goto out_unlock_up;
 611                 }
 612
 613                 err = security_shm_shmctl(shp, cmd);
 614                 if (err)
 615                         goto out_unlock_up;
 616
 617                 if (shp->shm_nattch){
 618                         shp->shm_perm.mode |= SHM_DEST;
 619                         /* Do not find it any more */
 620                         shp->shm_perm.key = IPC_PRIVATE;
 621                         shm_unlock(shp);
 622                 } else
 623                         shm_destroy (shp);
 624                 mutex_unlock(&shm_ids.mutex);
 625                 goto out;
 626         }
 627
 628         case IPC_SET:
 629         {
 630                 if (copy_shmid_from_user (&setbuf, buf, version)) {
 631                         err = -EFAULT;
 632                         goto out;
 633                 }
 634                 mutex_lock(&shm_ids.mutex);
 635                 shp = shm_lock(shmid);
 636                 err=-EINVAL;
 637                 if(shp==NULL)
 638                         goto out_up;
 639                 err = shm_checkid(shp,shmid);
 640                 if(err)
 641                         goto out_unlock_up;
 642                 err = audit_ipc_obj(&(shp->shm_perm));
 643                 if (err)
 644                         goto out_unlock_up;
 645                 err = audit_ipc_set_perm(0, setbuf.uid, setbuf.gid, setbuf.mode);
 646                 if (err)
 647                         goto out_unlock_up;
 648                 err=-EPERM;
 649                 if (current->euid != shp->shm_perm.uid &&
 650                     current->euid != shp->shm_perm.cuid &&
 651                     !capable(CAP_SYS_ADMIN)) {
 652                         goto out_unlock_up;
 653                 }
 654
 655                 err = security_shm_shmctl(shp, cmd);
 656                 if (err)
 657                         goto out_unlock_up;
 658
 659                 shp->shm_perm.uid = setbuf.uid;
 660                 shp->shm_perm.gid = setbuf.gid;
 661                 shp->shm_perm.mode = (shp->shm_perm.mode & ~S_IRWXUGO)
 662                         | (setbuf.mode & S_IRWXUGO);
 663                 shp->shm_ctim = get_seconds();
 664                 break;
 665         }
 666
 667         default:
 668                 err = -EINVAL;
 669                 goto out;
 670         }
 671
 672         err = 0;
 673 out_unlock_up:
 674         shm_unlock(shp);
 675 out_up:
 676         mutex_unlock(&shm_ids.mutex);
 677         goto out;
 678 out_unlock:
 679         shm_unlock(shp);
 680 out:
 681         return err;
 682 }
 683
 684 /*
 685  * Fix shmaddr, allocate descriptor, map shm, add attach descriptor to lists.
 686  *
 687  * NOTE! Despite the name, this is NOT a direct system call entrypoint. The
 688  * "raddr" thing points to kernel space, and there has to be a wrapper around
 689  * this.
 690  */
 691 long do_shmat(int shmid, char __user *shmaddr, int shmflg, ulong *raddr)
 692 {
 693         struct shmid_kernel *shp;
 694         unsigned long addr;
 695         unsigned long size;
 696         struct file * file;
 697         int    err;
 698         unsigned long flags;
 699         unsigned long prot;
 700         int acc_mode;
 701         void *user_addr;
 702
 703         if (shmid < 0) {
 704                 err = -EINVAL;
 705                 goto out;
 706         } else if ((addr = (ulong)shmaddr)) {
 707                 if (addr & (SHMLBA-1)) {
 708                         if (shmflg & SHM_RND)
 709                                 addr &= ~(SHMLBA-1);       /* round down */
 710                         else
 711 #ifndef __ARCH_FORCE_SHMLBA
 712                                 if (addr & ~PAGE_MASK)
 713 #endif
 714                                         return -EINVAL;
 715                 }
 716                 flags = MAP_SHARED | MAP_FIXED;
 717         } else {
 718                 if ((shmflg & SHM_REMAP))
 719                         return -EINVAL;
 720
 721                 flags = MAP_SHARED;
 722         }
 723
 724         if (shmflg & SHM_RDONLY) {
 725                 prot = PROT_READ;
 726                 acc_mode = S_IRUGO;
 727         } else {
 728                 prot = PROT_READ | PROT_WRITE;
 729                 acc_mode = S_IRUGO | S_IWUGO;
 730         }
 731         if (shmflg & SHM_EXEC) {
 732                 prot |= PROT_EXEC;
 733                 acc_mode |= S_IXUGO;
 734         }
 735
 736         /*
 737          * We cannot rely on the fs check since SYSV IPC does have an
 738          * additional creator id...
 739          */
 740         shp = shm_lock(shmid);
 741         if(shp == NULL) {
 742                 err = -EINVAL;
 743                 goto out;
 744         }
 745         err = shm_checkid(shp,shmid);
 746         if (err) {
 747                 shm_unlock(shp);
 748                 goto out;
 749         }
 750         if (ipcperms(&shp->shm_perm, acc_mode)) {
 751                 shm_unlock(shp);
 752                 err = -EACCES;
 753                 goto out;
 754         }
 755
 756         err = security_shm_shmat(shp, shmaddr, shmflg);
 757         if (err) {
 758                 shm_unlock(shp);
 759                 return err;
 760         }
 761
 762         file = shp->shm_file;
 763         size = i_size_read(file->f_dentry->d_inode);
 764         shp->shm_nattch++;
 765         shm_unlock(shp);
 766
 767         down_write(&current->mm->mmap_sem);
 768         if (addr && !(shmflg & SHM_REMAP)) {
 769                 user_addr = ERR_PTR(-EINVAL);
 770                 if (find_vma_intersection(current->mm, addr, addr + size))
 771                         goto invalid;
 772                 /*
 773                  * If shm segment goes below stack, make sure there is some
 774                  * space left for the stack to grow (at least 4 pages).
 775                  */
 776                 if (addr < current->mm->start_stack &&
 777                     addr > current->mm->start_stack - size - PAGE_SIZE * 5)
 778                         goto invalid;
 779         }
 780
 781         user_addr = (void*) do_mmap (file, addr, size, prot, flags, 0);
 782
 783 invalid:
 784         up_write(&current->mm->mmap_sem);
 785
 786         mutex_lock(&shm_ids.mutex);
 787         shp = shm_lock(shmid);
 788         BUG_ON(!shp);
 789         shp->shm_nattch--;
 790         if(shp->shm_nattch == 0 &&
 791            shp->shm_perm.mode & SHM_DEST)
 792                 shm_destroy (shp);
 793         else
 794                 shm_unlock(shp);
 795         mutex_unlock(&shm_ids.mutex);
 796
 797         *raddr = (unsigned long) user_addr;
 798         err = 0;
 799         if (IS_ERR(user_addr))
 800                 err = PTR_ERR(user_addr);
 801 out:
 802         return err;
 803 }
 804
 805 asmlinkage long sys_shmat(int shmid, char __user *shmaddr, int shmflg)
 806 {
 807         unsigned long ret;
 808         long err;
 809
 810         err = do_shmat(shmid, shmaddr, shmflg, &ret);
 811         if (err)
 812                 return err;
 813         force_successful_syscall_return();
 814         return (long)ret;
 815 }
 816
 817 /*
 818  * detach and kill segment if marked destroyed.
 819  * The work is done in shm_close.
 820  */
 821 asmlinkage long sys_shmdt(char __user *shmaddr)
 822 {
 823         struct mm_struct *mm = current->mm;
 824         struct vm_area_struct *vma, *next;
 825         unsigned long addr = (unsigned long)shmaddr;
 826         loff_t size = 0;
 827         int retval = -EINVAL;
 828
 829         if (addr & ~PAGE_MASK)
 830                 return retval;
 831
 832         down_write(&mm->mmap_sem);
 833
 834         /*
 835          * This function tries to be smart and unmap shm segments that
 836          * were modified by partial mlock or munmap calls:
 837          * - It first determines the size of the shm segment that should be
 838          *   unmapped: It searches for a vma that is backed by shm and that
 839          *   started at address shmaddr. It records it's size and then unmaps
 840          *   it.
 841          * - Then it unmaps all shm vmas that started at shmaddr and that
 842          *   are within the initially determined size.
 843          * Errors from do_munmap are ignored: the function only fails if
 844          * it's called with invalid parameters or if it's called to unmap
 845          * a part of a vma. Both calls in this function are for full vmas,
 846          * the parameters are directly copied from the vma itself and always
 847          * valid - therefore do_munmap cannot fail. (famous last words?)
 848          */
 849         /*
 850          * If it had been mremap()'d, the starting address would not
 851          * match the usual checks anyway. So assume all vma's are
 852          * above the starting address given.
 853          */
 854         vma = find_vma(mm, addr);
 855
 856         while (vma) {
 857                 next = vma->vm_next;
 858
 859                 /*
 860                  * Check if the starting address would match, i.e. it's
 861                  * a fragment created by mprotect() and/or munmap(), or it
 862                  * otherwise it starts at this address with no hassles.
 863                  */
 864                 if ((vma->vm_ops == &shm_vm_ops || is_vm_hugetlb_page(vma)) &&
 865                         (vma->vm_start - addr)/PAGE_SIZE == vma->vm_pgoff) {
 866
 867
 868                         size = vma->vm_file->f_dentry->d_inode->i_size;
 869                         do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start);
 870                         /*
 871                          * We discovered the size of the shm segment, so
 872                          * break out of here and fall through to the next
 873                          * loop that uses the size information to stop
 874                          * searching for matching vma's.
 875                          */
 876                         retval = 0;
 877                         vma = next;
 878                         break;
 879                 }
 880                 vma = next;
 881         }
 882
 883         /*
 884          * We need look no further than the maximum address a fragment
 885          * could possibly have landed at. Also cast things to loff_t to
 886          * prevent overflows and make comparisions vs. equal-width types.
 887          */
 888         size = PAGE_ALIGN(size);
 889         while (vma && (loff_t)(vma->vm_end - addr) <= size) {
 890                 next = vma->vm_next;
 891
 892                 /* finding a matching vma now does not alter retval */
 893                 if ((vma->vm_ops == &shm_vm_ops || is_vm_hugetlb_page(vma)) &&
 894                         (vma->vm_start - addr)/PAGE_SIZE == vma->vm_pgoff)
 895
 896                         do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start);
 897                 vma = next;
 898         }
 899
 900         up_write(&mm->mmap_sem);
 901         return retval;
 902 }
 903
 904 #ifdef CONFIG_PROC_FS
 905 static int sysvipc_shm_proc_show(struct seq_file *s, void *it)
 906 {
 907         struct shmid_kernel *shp = it;
 908         char *format;
 909
 910 #define SMALL_STRING "%10d %10d  %4o %10u %5u %5u  %5d %5u %5u %5u %5u %10lu %10lu %10lu\n"
 911 #define BIG_STRING   "%10d %10d  %4o %21u %5u %5u  %5d %5u %5u %5u %5u %10lu %10lu %10lu\n"
 912
 913         if (sizeof(size_t) <= sizeof(int))
 914                 format = SMALL_STRING;
 915         else
 916                 format = BIG_STRING;
 917         return seq_printf(s, format,
 918                           shp->shm_perm.key,
 919                           shp->id,
 920                           shp->shm_perm.mode,
 921                           shp->shm_segsz,
 922                           shp->shm_cprid,
 923                           shp->shm_lprid,
 924                           is_file_hugepages(shp->shm_file) ? (file_count(shp->shm_file) - 1) : shp->shm_nattch,
 925                           shp->shm_perm.uid,
 926                           shp->shm_perm.gid,
 927                           shp->shm_perm.cuid,
 928                           shp->shm_perm.cgid,
 929                           shp->shm_atim,
 930                           shp->shm_dtim,
 931                           shp->shm_ctim);
 932 }
 933 #endif