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