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  */
  17
  18 #include <linux/config.h>
  19 #include <linux/slab.h>
  20 #include <linux/mm.h>
  21 #include <linux/hugetlb.h>
  22 #include <linux/shm.h>
  23 #include <linux/init.h>
  24 #include <linux/file.h>
  25 #include <linux/mman.h>
  26 #include <linux/proc_fs.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/ptrace.h>
  32
  33 #include <asm/uaccess.h>
  34
  35 #include "util.h"
  36
  37 #define shm_flags       shm_perm.mode
  38
  39 static struct file_operations shm_file_operations;
  40 static struct vm_operations_struct shm_vm_ops;
  41
  42 static struct ipc_ids shm_ids;
  43
  44 #define shm_lock(id)    ((struct shmid_kernel*)ipc_lock(&shm_ids,id))
  45 #define shm_unlock(shp) ipc_unlock(&(shp)->shm_perm)
  46 #define shm_get(id)     ((struct shmid_kernel*)ipc_get(&shm_ids,id))
  47 #define shm_buildid(id, seq) \
  48         ipc_buildid(&shm_ids, id, seq)
  49
  50 static int newseg (key_t key, int shmflg, size_t size);
  51 static void shm_open (struct vm_area_struct *shmd);
  52 static void shm_close (struct vm_area_struct *shmd);
  53 #ifdef CONFIG_PROC_FS
  54 static int sysvipc_shm_read_proc(char *buffer, char **start, off_t offset, int length, int *eof, void *data);
  55 #endif
  56
  57 size_t  shm_ctlmax = SHMMAX;
  58 size_t  shm_ctlall = SHMALL;
  59 int     shm_ctlmni = SHMMNI;
  60
  61 static int shm_tot; /* total number of shared memory pages */
  62
  63 void __init shm_init (void)
  64 {
  65         ipc_init_ids(&shm_ids, 1);
  66 #ifdef CONFIG_PROC_FS
  67         create_proc_read_entry("sysvipc/shm", 0, NULL, sysvipc_shm_read_proc, NULL);
  68 #endif
  69 }
  70
  71 static inline int shm_checkid(struct shmid_kernel *s, int id)
  72 {
  73         if (ipc_checkid(&shm_ids,&s->shm_perm,id))
  74                 return -EIDRM;
  75         return 0;
  76 }
  77
  78 static inline struct shmid_kernel *shm_rmid(int id)
  79 {
  80         return (struct shmid_kernel *)ipc_rmid(&shm_ids,id);
  81 }
  82
  83 static inline int shm_addid(struct shmid_kernel *shp)
  84 {
  85         return ipc_addid(&shm_ids, &shp->shm_perm, shm_ctlmni);
  86 }
  87
  88
  89
  90 static inline void shm_inc (int id) {
  91         struct shmid_kernel *shp;
  92
  93         if(!(shp = shm_lock(id)))
  94                 BUG();
  95         shp->shm_atim = get_seconds();
  96         shp->shm_lprid = current->tgid;
  97         shp->shm_nattch++;
  98         shm_unlock(shp);
  99 }
 100
 101 /* This is called by fork, once for every shm attach. */
 102 static void shm_open (struct vm_area_struct *shmd)
 103 {
 104         shm_inc (shmd->vm_file->f_dentry->d_inode->i_ino);
 105 }
 106
 107 /*
 108  * shm_destroy - free the struct shmid_kernel
 109  *
 110  * @shp: struct to free
 111  *
 112  * It has to be called with shp and shm_ids.sem locked,
 113  * but returns with shp unlocked and freed.
 114  */
 115 static void shm_destroy (struct shmid_kernel *shp)
 116 {
 117         shm_tot -= (shp->shm_segsz + PAGE_SIZE - 1) >> PAGE_SHIFT;
 118         shm_rmid (shp->id);
 119         shm_unlock(shp);
 120         if (!is_file_hugepages(shp->shm_file))
 121                 shmem_lock(shp->shm_file, 0, shp->mlock_user);
 122         else
 123                 user_shm_unlock(shp->shm_file->f_dentry->d_inode->i_size,
 124                                                 shp->mlock_user);
 125         fput (shp->shm_file);
 126         security_shm_free(shp);
 127         ipc_rcu_putref(shp);
 128 }
 129
 130 /*
 131  * remove the attach descriptor shmd.
 132  * free memory for segment if it is marked destroyed.
 133  * The descriptor has already been removed from the current->mm->mmap list
 134  * and will later be kfree()d.
 135  */
 136 static void shm_close (struct vm_area_struct *shmd)
 137 {
 138         struct file * file = shmd->vm_file;
 139         int id = file->f_dentry->d_inode->i_ino;
 140         struct shmid_kernel *shp;
 141
 142         down (&shm_ids.sem);
 143         /* remove from the list of attaches of the shm segment */
 144         if(!(shp = shm_lock(id)))
 145                 BUG();
 146         shp->shm_lprid = current->tgid;
 147         shp->shm_dtim = get_seconds();
 148         shp->shm_nattch--;
 149         if(shp->shm_nattch == 0 &&
 150            shp->shm_flags & SHM_DEST)
 151                 shm_destroy (shp);
 152         else
 153                 shm_unlock(shp);
 154         up (&shm_ids.sem);
 155 }
 156
 157 static int shm_mmap(struct file * file, struct vm_area_struct * vma)
 158 {
 159         file_accessed(file);
 160         vma->vm_ops = &shm_vm_ops;
 161         shm_inc(file->f_dentry->d_inode->i_ino);
 162         return 0;
 163 }
 164
 165 static struct file_operations shm_file_operations = {
 166         .mmap   = shm_mmap
 167 };
 168
 169 static struct vm_operations_struct shm_vm_ops = {
 170         .open   = shm_open,     /* callback for a new vm-area open */
 171         .close  = shm_close,    /* callback for when the vm-area is released */
 172         .nopage = shmem_nopage,
 173 #if defined(CONFIG_NUMA) && defined(CONFIG_SHMEM)
 174         .set_policy = shmem_set_policy,
 175         .get_policy = shmem_get_policy,
 176 #endif
 177 };
 178
 179 static int newseg (key_t key, int shmflg, size_t size)
 180 {
 181         int error;
 182         struct shmid_kernel *shp;
 183         int numpages = (size + PAGE_SIZE -1) >> PAGE_SHIFT;
 184         struct file * file;
 185         char name[13];
 186         int id;
 187
 188         if (size < SHMMIN || size > shm_ctlmax)
 189                 return -EINVAL;
 190
 191         if (shm_tot + numpages >= shm_ctlall)
 192                 return -ENOSPC;
 193
 194         shp = ipc_rcu_alloc(sizeof(*shp));
 195         if (!shp)
 196                 return -ENOMEM;
 197
 198         shp->shm_perm.key = key;
 199         shp->shm_flags = (shmflg & S_IRWXUGO);
 200         shp->mlock_user = NULL;
 201
 202         shp->shm_perm.security = NULL;
 203         error = security_shm_alloc(shp);
 204         if (error) {
 205                 ipc_rcu_putref(shp);
 206                 return error;
 207         }
 208
 209         if (shmflg & SHM_HUGETLB) {
 210                 /* hugetlb_zero_setup takes care of mlock user accounting */
 211                 file = hugetlb_zero_setup(size);
 212                 shp->mlock_user = current->user;
 213         } else {
 214                 sprintf (name, "SYSV%08x", key);
 215                 file = shmem_file_setup(name, size, VM_ACCOUNT);
 216         }
 217         error = PTR_ERR(file);
 218         if (IS_ERR(file))
 219                 goto no_file;
 220
 221         error = -ENOSPC;
 222         id = shm_addid(shp);
 223         if(id == -1)
 224                 goto no_id;
 225
 226         shp->shm_cprid = current->tgid;
 227         shp->shm_lprid = 0;
 228         shp->shm_atim = shp->shm_dtim = 0;
 229         shp->shm_ctim = get_seconds();
 230         shp->shm_segsz = size;
 231         shp->shm_nattch = 0;
 232         shp->id = shm_buildid(id,shp->shm_perm.seq);
 233         shp->shm_file = file;
 234         file->f_dentry->d_inode->i_ino = shp->id;
 235         if (shmflg & SHM_HUGETLB)
 236                 set_file_hugepages(file);
 237         else
 238                 file->f_op = &shm_file_operations;
 239         shm_tot += numpages;
 240         shm_unlock(shp);
 241         return shp->id;
 242
 243 no_id:
 244         fput(file);
 245 no_file:
 246         security_shm_free(shp);
 247         ipc_rcu_putref(shp);
 248         return error;
 249 }
 250
 251 asmlinkage long sys_shmget (key_t key, size_t size, int shmflg)
 252 {
 253         struct shmid_kernel *shp;
 254         int err, id = 0;
 255
 256         down(&shm_ids.sem);
 257         if (key == IPC_PRIVATE) {
 258                 err = newseg(key, shmflg, size);
 259         } else if ((id = ipc_findkey(&shm_ids, key)) == -1) {
 260                 if (!(shmflg & IPC_CREAT))
 261                         err = -ENOENT;
 262                 else
 263                         err = newseg(key, shmflg, size);
 264         } else if ((shmflg & IPC_CREAT) && (shmflg & IPC_EXCL)) {
 265                 err = -EEXIST;
 266         } else {
 267                 shp = shm_lock(id);
 268                 if(shp==NULL)
 269                         BUG();
 270                 if (shp->shm_segsz < size)
 271                         err = -EINVAL;
 272                 else if (ipcperms(&shp->shm_perm, shmflg))
 273                         err = -EACCES;
 274                 else {
 275                         int shmid = shm_buildid(id, shp->shm_perm.seq);
 276                         err = security_shm_associate(shp, shmflg);
 277                         if (!err)
 278                                 err = shmid;
 279                 }
 280                 shm_unlock(shp);
 281         }
 282         up(&shm_ids.sem);
 283
 284         return err;
 285 }
 286
 287 static inline unsigned long copy_shmid_to_user(void __user *buf, struct shmid64_ds *in, int version)
 288 {
 289         switch(version) {
 290         case IPC_64:
 291                 return copy_to_user(buf, in, sizeof(*in));
 292         case IPC_OLD:
 293             {
 294                 struct shmid_ds out;
 295
 296                 ipc64_perm_to_ipc_perm(&in->shm_perm, &out.shm_perm);
 297                 out.shm_segsz   = in->shm_segsz;
 298                 out.shm_atime   = in->shm_atime;
 299                 out.shm_dtime   = in->shm_dtime;
 300                 out.shm_ctime   = in->shm_ctime;
 301                 out.shm_cpid    = in->shm_cpid;
 302                 out.shm_lpid    = in->shm_lpid;
 303                 out.shm_nattch  = in->shm_nattch;
 304
 305                 return copy_to_user(buf, &out, sizeof(out));
 306             }
 307         default:
 308                 return -EINVAL;
 309         }
 310 }
 311
 312 struct shm_setbuf {
 313         uid_t   uid;
 314         gid_t   gid;
 315         mode_t  mode;
 316 };
 317
 318 static inline unsigned long copy_shmid_from_user(struct shm_setbuf *out, void __user *buf, int version)
 319 {
 320         switch(version) {
 321         case IPC_64:
 322             {
 323                 struct shmid64_ds tbuf;
 324
 325                 if (copy_from_user(&tbuf, buf, sizeof(tbuf)))
 326                         return -EFAULT;
 327
 328                 out->uid        = tbuf.shm_perm.uid;
 329                 out->gid        = tbuf.shm_perm.gid;
 330                 out->mode       = tbuf.shm_flags;
 331
 332                 return 0;
 333             }
 334         case IPC_OLD:
 335             {
 336                 struct shmid_ds tbuf_old;
 337
 338                 if (copy_from_user(&tbuf_old, buf, sizeof(tbuf_old)))
 339                         return -EFAULT;
 340
 341                 out->uid        = tbuf_old.shm_perm.uid;
 342                 out->gid        = tbuf_old.shm_perm.gid;
 343                 out->mode       = tbuf_old.shm_flags;
 344
 345                 return 0;
 346             }
 347         default:
 348                 return -EINVAL;
 349         }
 350 }
 351
 352 static inline unsigned long copy_shminfo_to_user(void __user *buf, struct shminfo64 *in, int version)
 353 {
 354         switch(version) {
 355         case IPC_64:
 356                 return copy_to_user(buf, in, sizeof(*in));
 357         case IPC_OLD:
 358             {
 359                 struct shminfo out;
 360
 361                 if(in->shmmax > INT_MAX)
 362                         out.shmmax = INT_MAX;
 363                 else
 364                         out.shmmax = (int)in->shmmax;
 365
 366                 out.shmmin      = in->shmmin;
 367                 out.shmmni      = in->shmmni;
 368                 out.shmseg      = in->shmseg;
 369                 out.shmall      = in->shmall;
 370
 371                 return copy_to_user(buf, &out, sizeof(out));
 372             }
 373         default:
 374                 return -EINVAL;
 375         }
 376 }
 377
 378 static void shm_get_stat(unsigned long *rss, unsigned long *swp)
 379 {
 380         int i;
 381
 382         *rss = 0;
 383         *swp = 0;
 384
 385         for (i = 0; i <= shm_ids.max_id; i++) {
 386                 struct shmid_kernel *shp;
 387                 struct inode *inode;
 388
 389                 shp = shm_get(i);
 390                 if(!shp)
 391                         continue;
 392
 393                 inode = shp->shm_file->f_dentry->d_inode;
 394
 395                 if (is_file_hugepages(shp->shm_file)) {
 396                         struct address_space *mapping = inode->i_mapping;
 397                         *rss += (HPAGE_SIZE/PAGE_SIZE)*mapping->nrpages;
 398                 } else {
 399                         struct shmem_inode_info *info = SHMEM_I(inode);
 400                         spin_lock(&info->lock);
 401                         *rss += inode->i_mapping->nrpages;
 402                         *swp += info->swapped;
 403                         spin_unlock(&info->lock);
 404                 }
 405         }
 406 }
 407
 408 asmlinkage long sys_shmctl (int shmid, int cmd, struct shmid_ds __user *buf)
 409 {
 410         struct shm_setbuf setbuf;
 411         struct shmid_kernel *shp;
 412         int err, version;
 413
 414         if (cmd < 0 || shmid < 0) {
 415                 err = -EINVAL;
 416                 goto out;
 417         }
 418
 419         version = ipc_parse_version(&cmd);
 420
 421         switch (cmd) { /* replace with proc interface ? */
 422         case IPC_INFO:
 423         {
 424                 struct shminfo64 shminfo;
 425
 426                 err = security_shm_shmctl(NULL, cmd);
 427                 if (err)
 428                         return err;
 429
 430                 memset(&shminfo,0,sizeof(shminfo));
 431                 shminfo.shmmni = shminfo.shmseg = shm_ctlmni;
 432                 shminfo.shmmax = shm_ctlmax;
 433                 shminfo.shmall = shm_ctlall;
 434
 435                 shminfo.shmmin = SHMMIN;
 436                 if(copy_shminfo_to_user (buf, &shminfo, version))
 437                         return -EFAULT;
 438                 /* reading a integer is always atomic */
 439                 err= shm_ids.max_id;
 440                 if(err<0)
 441                         err = 0;
 442                 goto out;
 443         }
 444         case SHM_INFO:
 445         {
 446                 struct shm_info shm_info;
 447
 448                 err = security_shm_shmctl(NULL, cmd);
 449                 if (err)
 450                         return err;
 451
 452                 memset(&shm_info,0,sizeof(shm_info));
 453                 down(&shm_ids.sem);
 454                 shm_info.used_ids = shm_ids.in_use;
 455                 shm_get_stat (&shm_info.shm_rss, &shm_info.shm_swp);
 456                 shm_info.shm_tot = shm_tot;
 457                 shm_info.swap_attempts = 0;
 458                 shm_info.swap_successes = 0;
 459                 err = shm_ids.max_id;
 460                 up(&shm_ids.sem);
 461                 if(copy_to_user (buf, &shm_info, sizeof(shm_info))) {
 462                         err = -EFAULT;
 463                         goto out;
 464                 }
 465
 466                 err = err < 0 ? 0 : err;
 467                 goto out;
 468         }
 469         case SHM_STAT:
 470         case IPC_STAT:
 471         {
 472                 struct shmid64_ds tbuf;
 473                 int result;
 474                 memset(&tbuf, 0, sizeof(tbuf));
 475                 shp = shm_lock(shmid);
 476                 if(shp==NULL) {
 477                         err = -EINVAL;
 478                         goto out;
 479                 } else if(cmd==SHM_STAT) {
 480                         err = -EINVAL;
 481                         if (shmid > shm_ids.max_id)
 482                                 goto out_unlock;
 483                         result = shm_buildid(shmid, shp->shm_perm.seq);
 484                 } else {
 485                         err = shm_checkid(shp,shmid);
 486                         if(err)
 487                                 goto out_unlock;
 488                         result = 0;
 489                 }
 490                 err=-EACCES;
 491                 if (ipcperms (&shp->shm_perm, S_IRUGO))
 492                         goto out_unlock;
 493                 err = security_shm_shmctl(shp, cmd);
 494                 if (err)
 495                         goto out_unlock;
 496                 kernel_to_ipc64_perm(&shp->shm_perm, &tbuf.shm_perm);
 497                 tbuf.shm_segsz  = shp->shm_segsz;
 498                 tbuf.shm_atime  = shp->shm_atim;
 499                 tbuf.shm_dtime  = shp->shm_dtim;
 500                 tbuf.shm_ctime  = shp->shm_ctim;
 501                 tbuf.shm_cpid   = shp->shm_cprid;
 502                 tbuf.shm_lpid   = shp->shm_lprid;
 503                 if (!is_file_hugepages(shp->shm_file))
 504                         tbuf.shm_nattch = shp->shm_nattch;
 505                 else
 506                         tbuf.shm_nattch = file_count(shp->shm_file) - 1;
 507                 shm_unlock(shp);
 508                 if(copy_shmid_to_user (buf, &tbuf, version))
 509                         err = -EFAULT;
 510                 else
 511                         err = result;
 512                 goto out;
 513         }
 514         case SHM_LOCK:
 515         case SHM_UNLOCK:
 516         {
 517                 shp = shm_lock(shmid);
 518                 if(shp==NULL) {
 519                         err = -EINVAL;
 520                         goto out;
 521                 }
 522                 err = shm_checkid(shp,shmid);
 523                 if(err)
 524                         goto out_unlock;
 525
 526                 if (!capable(CAP_IPC_LOCK)) {
 527                         err = -EPERM;
 528                         if (current->euid != shp->shm_perm.uid &&
 529                             current->euid != shp->shm_perm.cuid)
 530                                 goto out_unlock;
 531                         if (cmd == SHM_LOCK &&
 532                             !current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur)
 533                                 goto out_unlock;
 534                 }
 535
 536                 err = security_shm_shmctl(shp, cmd);
 537                 if (err)
 538                         goto out_unlock;
 539
 540                 if(cmd==SHM_LOCK) {
 541                         struct user_struct * user = current->user;
 542                         if (!is_file_hugepages(shp->shm_file)) {
 543                                 err = shmem_lock(shp->shm_file, 1, user);
 544                                 if (!err) {
 545                                         shp->shm_flags |= SHM_LOCKED;
 546                                         shp->mlock_user = user;
 547                                 }
 548                         }
 549                 } else if (!is_file_hugepages(shp->shm_file)) {
 550                         shmem_lock(shp->shm_file, 0, shp->mlock_user);
 551                         shp->shm_flags &= ~SHM_LOCKED;
 552                         shp->mlock_user = NULL;
 553                 }
 554                 shm_unlock(shp);
 555                 goto out;
 556         }
 557         case IPC_RMID:
 558         {
 559                 /*
 560                  *      We cannot simply remove the file. The SVID states
 561                  *      that the block remains until the last person
 562                  *      detaches from it, then is deleted. A shmat() on
 563                  *      an RMID segment is legal in older Linux and if
 564                  *      we change it apps break...
 565                  *
 566                  *      Instead we set a destroyed flag, and then blow
 567                  *      the name away when the usage hits zero.
 568                  */
 569                 down(&shm_ids.sem);
 570                 shp = shm_lock(shmid);
 571                 err = -EINVAL;
 572                 if (shp == NULL)
 573                         goto out_up;
 574                 err = shm_checkid(shp, shmid);
 575                 if(err)
 576                         goto out_unlock_up;
 577
 578                 if (current->euid != shp->shm_perm.uid &&
 579                     current->euid != shp->shm_perm.cuid &&
 580                     !capable(CAP_SYS_ADMIN)) {
 581                         err=-EPERM;
 582                         goto out_unlock_up;
 583                 }
 584
 585                 err = security_shm_shmctl(shp, cmd);
 586                 if (err)
 587                         goto out_unlock_up;
 588
 589                 if (shp->shm_nattch){
 590                         shp->shm_flags |= SHM_DEST;
 591                         /* Do not find it any more */
 592                         shp->shm_perm.key = IPC_PRIVATE;
 593                         shm_unlock(shp);
 594                 } else
 595                         shm_destroy (shp);
 596                 up(&shm_ids.sem);
 597                 goto out;
 598         }
 599
 600         case IPC_SET:
 601         {
 602                 if (copy_shmid_from_user (&setbuf, buf, version)) {
 603                         err = -EFAULT;
 604                         goto out;
 605                 }
 606                 if ((err = audit_ipc_perms(0, setbuf.uid, setbuf.gid, setbuf.mode)))
 607                         return err;
 608                 down(&shm_ids.sem);
 609                 shp = shm_lock(shmid);
 610                 err=-EINVAL;
 611                 if(shp==NULL)
 612                         goto out_up;
 613                 err = shm_checkid(shp,shmid);
 614                 if(err)
 615                         goto out_unlock_up;
 616                 err=-EPERM;
 617                 if (current->euid != shp->shm_perm.uid &&
 618                     current->euid != shp->shm_perm.cuid &&
 619                     !capable(CAP_SYS_ADMIN)) {
 620                         goto out_unlock_up;
 621                 }
 622
 623                 err = security_shm_shmctl(shp, cmd);
 624                 if (err)
 625                         goto out_unlock_up;
 626
 627                 shp->shm_perm.uid = setbuf.uid;
 628                 shp->shm_perm.gid = setbuf.gid;
 629                 shp->shm_flags = (shp->shm_flags & ~S_IRWXUGO)
 630                         | (setbuf.mode & S_IRWXUGO);
 631                 shp->shm_ctim = get_seconds();
 632                 break;
 633         }
 634
 635         default:
 636                 err = -EINVAL;
 637                 goto out;
 638         }
 639
 640         err = 0;
 641 out_unlock_up:
 642         shm_unlock(shp);
 643 out_up:
 644         up(&shm_ids.sem);
 645         goto out;
 646 out_unlock:
 647         shm_unlock(shp);
 648 out:
 649         return err;
 650 }
 651
 652 /*
 653  * Fix shmaddr, allocate descriptor, map shm, add attach descriptor to lists.
 654  *
 655  * NOTE! Despite the name, this is NOT a direct system call entrypoint. The
 656  * "raddr" thing points to kernel space, and there has to be a wrapper around
 657  * this.
 658  */
 659 long do_shmat(int shmid, char __user *shmaddr, int shmflg, ulong *raddr)
 660 {
 661         struct shmid_kernel *shp;
 662         unsigned long addr;
 663         unsigned long size;
 664         struct file * file;
 665         int    err;
 666         unsigned long flags;
 667         unsigned long prot;
 668         unsigned long o_flags;
 669         int acc_mode;
 670         void *user_addr;
 671
 672         if (shmid < 0) {
 673                 err = -EINVAL;
 674                 goto out;
 675         } else if ((addr = (ulong)shmaddr)) {
 676                 if (addr & (SHMLBA-1)) {
 677                         if (shmflg & SHM_RND)
 678                                 addr &= ~(SHMLBA-1);       /* round down */
 679                         else
 680 #ifndef __ARCH_FORCE_SHMLBA
 681                                 if (addr & ~PAGE_MASK)
 682 #endif
 683                                         return -EINVAL;
 684                 }
 685                 flags = MAP_SHARED | MAP_FIXED;
 686         } else {
 687                 if ((shmflg & SHM_REMAP))
 688                         return -EINVAL;
 689
 690                 flags = MAP_SHARED;
 691         }
 692
 693         if (shmflg & SHM_RDONLY) {
 694                 prot = PROT_READ;
 695                 o_flags = O_RDONLY;
 696                 acc_mode = S_IRUGO;
 697         } else {
 698                 prot = PROT_READ | PROT_WRITE;
 699                 o_flags = O_RDWR;
 700                 acc_mode = S_IRUGO | S_IWUGO;
 701         }
 702         if (shmflg & SHM_EXEC) {
 703                 prot |= PROT_EXEC;
 704                 acc_mode |= S_IXUGO;
 705         }
 706
 707         /*
 708          * We cannot rely on the fs check since SYSV IPC does have an
 709          * additional creator id...
 710          */
 711         shp = shm_lock(shmid);
 712         if(shp == NULL) {
 713                 err = -EINVAL;
 714                 goto out;
 715         }
 716         err = shm_checkid(shp,shmid);
 717         if (err) {
 718                 shm_unlock(shp);
 719                 goto out;
 720         }
 721         if (ipcperms(&shp->shm_perm, acc_mode)) {
 722                 shm_unlock(shp);
 723                 err = -EACCES;
 724                 goto out;
 725         }
 726
 727         err = security_shm_shmat(shp, shmaddr, shmflg);
 728         if (err) {
 729                 shm_unlock(shp);
 730                 return err;
 731         }
 732
 733         file = shp->shm_file;
 734         size = i_size_read(file->f_dentry->d_inode);
 735         shp->shm_nattch++;
 736         shm_unlock(shp);
 737
 738         down_write(&current->mm->mmap_sem);
 739         if (addr && !(shmflg & SHM_REMAP)) {
 740                 user_addr = ERR_PTR(-EINVAL);
 741                 if (find_vma_intersection(current->mm, addr, addr + size))
 742                         goto invalid;
 743                 /*
 744                  * If shm segment goes below stack, make sure there is some
 745                  * space left for the stack to grow (at least 4 pages).
 746                  */
 747                 if (addr < current->mm->start_stack &&
 748                     addr > current->mm->start_stack - size - PAGE_SIZE * 5)
 749                         goto invalid;
 750         }
 751
 752         user_addr = (void*) do_mmap (file, addr, size, prot, flags, 0);
 753
 754 invalid:
 755         up_write(&current->mm->mmap_sem);
 756
 757         down (&shm_ids.sem);
 758         if(!(shp = shm_lock(shmid)))
 759                 BUG();
 760         shp->shm_nattch--;
 761         if(shp->shm_nattch == 0 &&
 762            shp->shm_flags & SHM_DEST)
 763                 shm_destroy (shp);
 764         else
 765                 shm_unlock(shp);
 766         up (&shm_ids.sem);
 767
 768         *raddr = (unsigned long) user_addr;
 769         err = 0;
 770         if (IS_ERR(user_addr))
 771                 err = PTR_ERR(user_addr);
 772 out:
 773         return err;
 774 }
 775
 776 asmlinkage long sys_shmat(int shmid, char __user *shmaddr, int shmflg)
 777 {
 778         unsigned long ret;
 779         long err;
 780
 781         err = do_shmat(shmid, shmaddr, shmflg, &ret);
 782         if (err)
 783                 return err;
 784         force_successful_syscall_return();
 785         return (long)ret;
 786 }
 787
 788 /*
 789  * detach and kill segment if marked destroyed.
 790  * The work is done in shm_close.
 791  */
 792 asmlinkage long sys_shmdt(char __user *shmaddr)
 793 {
 794         struct mm_struct *mm = current->mm;
 795         struct vm_area_struct *vma, *next;
 796         unsigned long addr = (unsigned long)shmaddr;
 797         loff_t size = 0;
 798         int retval = -EINVAL;
 799
 800         down_write(&mm->mmap_sem);
 801
 802         /*
 803          * This function tries to be smart and unmap shm segments that
 804          * were modified by partial mlock or munmap calls:
 805          * - It first determines the size of the shm segment that should be
 806          *   unmapped: It searches for a vma that is backed by shm and that
 807          *   started at address shmaddr. It records it's size and then unmaps
 808          *   it.
 809          * - Then it unmaps all shm vmas that started at shmaddr and that
 810          *   are within the initially determined size.
 811          * Errors from do_munmap are ignored: the function only fails if
 812          * it's called with invalid parameters or if it's called to unmap
 813          * a part of a vma. Both calls in this function are for full vmas,
 814          * the parameters are directly copied from the vma itself and always
 815          * valid - therefore do_munmap cannot fail. (famous last words?)
 816          */
 817         /*
 818          * If it had been mremap()'d, the starting address would not
 819          * match the usual checks anyway. So assume all vma's are
 820          * above the starting address given.
 821          */
 822         vma = find_vma(mm, addr);
 823
 824         while (vma) {
 825                 next = vma->vm_next;
 826
 827                 /*
 828                  * Check if the starting address would match, i.e. it's
 829                  * a fragment created by mprotect() and/or munmap(), or it
 830                  * otherwise it starts at this address with no hassles.
 831                  */
 832                 if ((vma->vm_ops == &shm_vm_ops || is_vm_hugetlb_page(vma)) &&
 833                         (vma->vm_start - addr)/PAGE_SIZE == vma->vm_pgoff) {
 834
 835
 836                         size = vma->vm_file->f_dentry->d_inode->i_size;
 837                         do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start);
 838                         /*
 839                          * We discovered the size of the shm segment, so
 840                          * break out of here and fall through to the next
 841                          * loop that uses the size information to stop
 842                          * searching for matching vma's.
 843                          */
 844                         retval = 0;
 845                         vma = next;
 846                         break;
 847                 }
 848                 vma = next;
 849         }
 850
 851         /*
 852          * We need look no further than the maximum address a fragment
 853          * could possibly have landed at. Also cast things to loff_t to
 854          * prevent overflows and make comparisions vs. equal-width types.
 855          */
 856         while (vma && (loff_t)(vma->vm_end - addr) <= size) {
 857                 next = vma->vm_next;
 858
 859                 /* finding a matching vma now does not alter retval */
 860                 if ((vma->vm_ops == &shm_vm_ops || is_vm_hugetlb_page(vma)) &&
 861                         (vma->vm_start - addr)/PAGE_SIZE == vma->vm_pgoff)
 862
 863                         do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start);
 864                 vma = next;
 865         }
 866
 867         up_write(&mm->mmap_sem);
 868         return retval;
 869 }
 870
 871 #ifdef CONFIG_PROC_FS
 872 static int sysvipc_shm_read_proc(char *buffer, char **start, off_t offset, int length, int *eof, void *data)
 873 {
 874         off_t pos = 0;
 875         off_t begin = 0;
 876         int i, len = 0;
 877
 878         down(&shm_ids.sem);
 879         len += sprintf(buffer, "       key      shmid perms       size  cpid  lpid nattch   uid   gid  cuid  cgid      atime      dtime      ctime\n");
 880
 881         for(i = 0; i <= shm_ids.max_id; i++) {
 882                 struct shmid_kernel* shp;
 883
 884                 shp = shm_lock(i);
 885                 if(shp!=NULL) {
 886 #define SMALL_STRING "%10d %10d  %4o %10u %5u %5u  %5d %5u %5u %5u %5u %10lu %10lu %10lu\n"
 887 #define BIG_STRING   "%10d %10d  %4o %21u %5u %5u  %5d %5u %5u %5u %5u %10lu %10lu %10lu\n"
 888                         char *format;
 889
 890                         if (sizeof(size_t) <= sizeof(int))
 891                                 format = SMALL_STRING;
 892                         else
 893                                 format = BIG_STRING;
 894                         len += sprintf(buffer + len, format,
 895                                 shp->shm_perm.key,
 896                                 shm_buildid(i, shp->shm_perm.seq),
 897                                 shp->shm_flags,
 898                                 shp->shm_segsz,
 899                                 shp->shm_cprid,
 900                                 shp->shm_lprid,
 901                                 is_file_hugepages(shp->shm_file) ? (file_count(shp->shm_file) - 1) : shp->shm_nattch,
 902                                 shp->shm_perm.uid,
 903                                 shp->shm_perm.gid,
 904                                 shp->shm_perm.cuid,
 905                                 shp->shm_perm.cgid,
 906                                 shp->shm_atim,
 907                                 shp->shm_dtim,
 908                                 shp->shm_ctim);
 909                         shm_unlock(shp);
 910
 911                         pos += len;
 912                         if(pos < offset) {
 913                                 len = 0;
 914                                 begin = pos;
 915                         }
 916                         if(pos > offset + length)
 917                                 goto done;
 918                 }
 919         }
 920         *eof = 1;
 921 done:
 922         up(&shm_ids.sem);
 923         *start = buffer + (offset - begin);
 924         len -= (offset - begin);
 925         if(len > length)
 926                 len = length;
 927         if(len < 0)
 928                 len = 0;
 929         return len;
 930 }
 931 #endif