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   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/config.h>
  21 #include <linux/slab.h>
  22 #include <linux/mm.h>
  23 #include <linux/hugetlb.h>
  24 #include <linux/shm.h>
  25 #include <linux/init.h>
  26 #include <linux/file.h>
  27 #include <linux/mman.h>
  28 #include <linux/shmem_fs.h>
  29 #include <linux/security.h>
  30 #include <linux/syscalls.h>
  31 #include <linux/audit.h>
  32 #include <linux/capability.h>
  33 #include <linux/ptrace.h>
  34 #include <linux/seq_file.h>
  35 #include <linux/mutex.h>
  36
  37 #include <asm/uaccess.h>
  38
  39 #include "util.h"
  40
  41 static struct file_operations shm_file_operations;
  42 static struct vm_operations_struct shm_vm_ops;
  43
  44 static struct ipc_ids shm_ids;
  45
  46 #define shm_lock(id)    ((struct shmid_kernel*)ipc_lock(&shm_ids,id))
  47 #define shm_unlock(shp) ipc_unlock(&(shp)->shm_perm)
  48 #define shm_get(id)     ((struct shmid_kernel*)ipc_get(&shm_ids,id))
  49 #define shm_buildid(id, seq) \
  50         ipc_buildid(&shm_ids, id, seq)
  51
  52 static int newseg (key_t key, int shmflg, size_t size);
  53 static void shm_open (struct vm_area_struct *shmd);
  54 static void shm_close (struct vm_area_struct *shmd);
  55 #ifdef CONFIG_PROC_FS
  56 static int sysvipc_shm_proc_show(struct seq_file *s, void *it);
  57 #endif
  58
  59 size_t  shm_ctlmax = SHMMAX;
  60 size_t  shm_ctlall = SHMALL;
  61 int     shm_ctlmni = SHMMNI;
  62
  63 static int shm_tot; /* total number of shared memory pages */
  64
  65 void __init shm_init (void)
  66 {
  67         ipc_init_ids(&shm_ids, 1);
  68         ipc_init_proc_interface("sysvipc/shm",
  69                                 "       key      shmid perms       size  cpid  lpid nattch   uid   gid  cuid  cgid      atime      dtime      ctime\n",
  70                                 &shm_ids,
  71                                 sysvipc_shm_proc_show);
  72 }
  73
  74 static inline int shm_checkid(struct shmid_kernel *s, int id)
  75 {
  76         if (ipc_checkid(&shm_ids,&s->shm_perm,id))
  77                 return -EIDRM;
  78         return 0;
  79 }
  80
  81 static inline struct shmid_kernel *shm_rmid(int id)
  82 {
  83         return (struct shmid_kernel *)ipc_rmid(&shm_ids,id);
  84 }
  85
  86 static inline int shm_addid(struct shmid_kernel *shp)
  87 {
  88         return ipc_addid(&shm_ids, &shp->shm_perm, shm_ctlmni);
  89 }
  90
  91
  92
  93 static inline void shm_inc (int id) {
  94         struct shmid_kernel *shp;
  95
  96         shp = shm_lock(id);
  97         BUG_ON(!shp);
  98         shp->shm_atim = get_seconds();
  99         shp->shm_lprid = current->tgid;
 100         shp->shm_nattch++;
 101         shm_unlock(shp);
 102 }
 103
 104 /* This is called by fork, once for every shm attach. */
 105 static void shm_open (struct vm_area_struct *shmd)
 106 {
 107         shm_inc (shmd->vm_file->f_dentry->d_inode->i_ino);
 108 }
 109
 110 /*
 111  * shm_destroy - free the struct shmid_kernel
 112  *
 113  * @shp: struct to free
 114  *
 115  * It has to be called with shp and shm_ids.mutex locked,
 116  * but returns with shp unlocked and freed.
 117  */
 118 static void shm_destroy (struct shmid_kernel *shp)
 119 {
 120         shm_tot -= (shp->shm_segsz + PAGE_SIZE - 1) >> PAGE_SHIFT;
 121         shm_rmid (shp->id);
 122         shm_unlock(shp);
 123         if (!is_file_hugepages(shp->shm_file))
 124                 shmem_lock(shp->shm_file, 0, shp->mlock_user);
 125         else
 126                 user_shm_unlock(shp->shm_file->f_dentry->d_inode->i_size,
 127                                                 shp->mlock_user);
 128         fput (shp->shm_file);
 129         security_shm_free(shp);
 130         ipc_rcu_putref(shp);
 131 }
 132
 133 /*
 134  * remove the attach descriptor shmd.
 135  * free memory for segment if it is marked destroyed.
 136  * The descriptor has already been removed from the current->mm->mmap list
 137  * and will later be kfree()d.
 138  */
 139 static void shm_close (struct vm_area_struct *shmd)
 140 {
 141         struct file * file = shmd->vm_file;
 142         int id = file->f_dentry->d_inode->i_ino;
 143         struct shmid_kernel *shp;
 144
 145         mutex_lock(&shm_ids.mutex);
 146         /* remove from the list of attaches of the shm segment */
 147         shp = shm_lock(id);
 148         BUG_ON(!shp);
 149         shp->shm_lprid = current->tgid;
 150         shp->shm_dtim = get_seconds();
 151         shp->shm_nattch--;
 152         if(shp->shm_nattch == 0 &&
 153            shp->shm_perm.mode & SHM_DEST)
 154                 shm_destroy (shp);
 155         else
 156                 shm_unlock(shp);
 157         mutex_unlock(&shm_ids.mutex);
 158 }
 159
 160 static int shm_mmap(struct file * file, struct vm_area_struct * vma)
 161 {
 162         int ret;
 163
 164         ret = shmem_mmap(file, vma);
 165         if (ret == 0) {
 166                 vma->vm_ops = &shm_vm_ops;
 167                 if (!(vma->vm_flags & VM_WRITE))
 168                         vma->vm_flags &= ~VM_MAYWRITE;
 169                 shm_inc(file->f_dentry->d_inode->i_ino);
 170         }
 171
 172         return ret;
 173 }
 174
 175 static struct file_operations shm_file_operations = {
 176         .mmap   = shm_mmap,
 177 #ifndef CONFIG_MMU
 178         .get_unmapped_area = shmem_get_unmapped_area,
 179 #endif
 180 };
 181
 182 static struct vm_operations_struct shm_vm_ops = {
 183         .open   = shm_open,     /* callback for a new vm-area open */
 184         .close  = shm_close,    /* callback for when the vm-area is released */
 185         .nopage = shmem_nopage,
 186 #if defined(CONFIG_NUMA) && defined(CONFIG_SHMEM)
 187         .set_policy = shmem_set_policy,
 188         .get_policy = shmem_get_policy,
 189 #endif
 190 };
 191
 192 static int newseg (key_t key, int shmflg, size_t size)
 193 {
 194         int error;
 195         struct shmid_kernel *shp;
 196         int numpages = (size + PAGE_SIZE -1) >> PAGE_SHIFT;
 197         struct file * file;
 198         char name[13];
 199         int id;
 200
 201         if (size < SHMMIN || size > shm_ctlmax)
 202                 return -EINVAL;
 203
 204         if (shm_tot + numpages >= shm_ctlall)
 205                 return -ENOSPC;
 206
 207         shp = ipc_rcu_alloc(sizeof(*shp));
 208         if (!shp)
 209                 return -ENOMEM;
 210
 211         shp->shm_perm.key = key;
 212         shp->shm_perm.mode = (shmflg & S_IRWXUGO);
 213         shp->mlock_user = NULL;
 214
 215         shp->shm_perm.security = NULL;
 216         error = security_shm_alloc(shp);
 217         if (error) {
 218                 ipc_rcu_putref(shp);
 219                 return error;
 220         }
 221
 222         if (shmflg & SHM_HUGETLB) {
 223                 /* hugetlb_zero_setup takes care of mlock user accounting */
 224                 file = hugetlb_zero_setup(size);
 225                 shp->mlock_user = current->user;
 226         } else {
 227                 int acctflag = VM_ACCOUNT;
 228                 /*
 229                  * Do not allow no accounting for OVERCOMMIT_NEVER, even
 230                  * if it's asked for.
 231                  */
 232                 if  ((shmflg & SHM_NORESERVE) &&
 233                                 sysctl_overcommit_memory != OVERCOMMIT_NEVER)
 234                         acctflag = 0;
 235                 sprintf (name, "SYSV%08x", key);
 236                 file = shmem_file_setup(name, size, acctflag);
 237         }
 238         error = PTR_ERR(file);
 239         if (IS_ERR(file))
 240                 goto no_file;
 241
 242         error = -ENOSPC;
 243         id = shm_addid(shp);
 244         if(id == -1)
 245                 goto no_id;
 246
 247         shp->shm_cprid = current->tgid;
 248         shp->shm_lprid = 0;
 249         shp->shm_atim = shp->shm_dtim = 0;
 250         shp->shm_ctim = get_seconds();
 251         shp->shm_segsz = size;
 252         shp->shm_nattch = 0;
 253         shp->id = shm_buildid(id,shp->shm_perm.seq);
 254         shp->shm_file = file;
 255         file->f_dentry->d_inode->i_ino = shp->id;
 256
 257         /* Hugetlb ops would have already been assigned. */
 258         if (!(shmflg & SHM_HUGETLB))
 259                 file->f_op = &shm_file_operations;
 260
 261         shm_tot += numpages;
 262         shm_unlock(shp);
 263         return shp->id;
 264
 265 no_id:
 266         fput(file);
 267 no_file:
 268         security_shm_free(shp);
 269         ipc_rcu_putref(shp);
 270         return error;
 271 }
 272
 273 asmlinkage long sys_shmget (key_t key, size_t size, int shmflg)
 274 {
 275         struct shmid_kernel *shp;
 276         int err, id = 0;
 277
 278         mutex_lock(&shm_ids.mutex);
 279         if (key == IPC_PRIVATE) {
 280                 err = newseg(key, shmflg, size);
 281         } else if ((id = ipc_findkey(&shm_ids, key)) == -1) {
 282                 if (!(shmflg & IPC_CREAT))
 283                         err = -ENOENT;
 284                 else
 285                         err = newseg(key, shmflg, size);
 286         } else if ((shmflg & IPC_CREAT) && (shmflg & IPC_EXCL)) {
 287                 err = -EEXIST;
 288         } else {
 289                 shp = shm_lock(id);
 290                 BUG_ON(shp==NULL);
 291                 if (shp->shm_segsz < size)
 292                         err = -EINVAL;
 293                 else if (ipcperms(&shp->shm_perm, shmflg))
 294                         err = -EACCES;
 295                 else {
 296                         int shmid = shm_buildid(id, shp->shm_perm.seq);
 297                         err = security_shm_associate(shp, shmflg);
 298                         if (!err)
 299                                 err = shmid;
 300                 }
 301                 shm_unlock(shp);
 302         }
 303         mutex_unlock(&shm_ids.mutex);
 304
 305         return err;
 306 }
 307
 308 static inline unsigned long copy_shmid_to_user(void __user *buf, struct shmid64_ds *in, int version)
 309 {
 310         switch(version) {
 311         case IPC_64:
 312                 return copy_to_user(buf, in, sizeof(*in));
 313         case IPC_OLD:
 314             {
 315                 struct shmid_ds out;
 316
 317                 ipc64_perm_to_ipc_perm(&in->shm_perm, &out.shm_perm);
 318                 out.shm_segsz   = in->shm_segsz;
 319                 out.shm_atime   = in->shm_atime;
 320                 out.shm_dtime   = in->shm_dtime;
 321                 out.shm_ctime   = in->shm_ctime;
 322                 out.shm_cpid    = in->shm_cpid;
 323                 out.shm_lpid    = in->shm_lpid;
 324                 out.shm_nattch  = in->shm_nattch;
 325
 326                 return copy_to_user(buf, &out, sizeof(out));
 327             }
 328         default:
 329                 return -EINVAL;
 330         }
 331 }
 332
 333 struct shm_setbuf {
 334         uid_t   uid;
 335         gid_t   gid;
 336         mode_t  mode;
 337 };
 338
 339 static inline unsigned long copy_shmid_from_user(struct shm_setbuf *out, void __user *buf, int version)
 340 {
 341         switch(version) {
 342         case IPC_64:
 343             {
 344                 struct shmid64_ds tbuf;
 345
 346                 if (copy_from_user(&tbuf, buf, sizeof(tbuf)))
 347                         return -EFAULT;
 348
 349                 out->uid        = tbuf.shm_perm.uid;
 350                 out->gid        = tbuf.shm_perm.gid;
 351                 out->mode       = tbuf.shm_perm.mode;
 352
 353                 return 0;
 354             }
 355         case IPC_OLD:
 356             {
 357                 struct shmid_ds tbuf_old;
 358
 359                 if (copy_from_user(&tbuf_old, buf, sizeof(tbuf_old)))
 360                         return -EFAULT;
 361
 362                 out->uid        = tbuf_old.shm_perm.uid;
 363                 out->gid        = tbuf_old.shm_perm.gid;
 364                 out->mode       = tbuf_old.shm_perm.mode;
 365
 366                 return 0;
 367             }
 368         default:
 369                 return -EINVAL;
 370         }
 371 }
 372
 373 static inline unsigned long copy_shminfo_to_user(void __user *buf, struct shminfo64 *in, int version)
 374 {
 375         switch(version) {
 376         case IPC_64:
 377                 return copy_to_user(buf, in, sizeof(*in));
 378         case IPC_OLD:
 379             {
 380                 struct shminfo out;
 381
 382                 if(in->shmmax > INT_MAX)
 383                         out.shmmax = INT_MAX;
 384                 else
 385                         out.shmmax = (int)in->shmmax;
 386
 387                 out.shmmin      = in->shmmin;
 388                 out.shmmni      = in->shmmni;
 389                 out.shmseg      = in->shmseg;
 390                 out.shmall      = in->shmall;
 391
 392                 return copy_to_user(buf, &out, sizeof(out));
 393             }
 394         default:
 395                 return -EINVAL;
 396         }
 397 }
 398
 399 static void shm_get_stat(unsigned long *rss, unsigned long *swp)
 400 {
 401         int i;
 402
 403         *rss = 0;
 404         *swp = 0;
 405
 406         for (i = 0; i <= shm_ids.max_id; i++) {
 407                 struct shmid_kernel *shp;
 408                 struct inode *inode;
 409
 410                 shp = shm_get(i);
 411                 if(!shp)
 412                         continue;
 413
 414                 inode = shp->shm_file->f_dentry->d_inode;
 415
 416                 if (is_file_hugepages(shp->shm_file)) {
 417                         struct address_space *mapping = inode->i_mapping;
 418                         *rss += (HPAGE_SIZE/PAGE_SIZE)*mapping->nrpages;
 419                 } else {
 420                         struct shmem_inode_info *info = SHMEM_I(inode);
 421                         spin_lock(&info->lock);
 422                         *rss += inode->i_mapping->nrpages;
 423                         *swp += info->swapped;
 424                         spin_unlock(&info->lock);
 425                 }
 426         }
 427 }
 428
 429 asmlinkage long sys_shmctl (int shmid, int cmd, struct shmid_ds __user *buf)
 430 {
 431         struct shm_setbuf setbuf;
 432         struct shmid_kernel *shp;
 433         int err, version;
 434
 435         if (cmd < 0 || shmid < 0) {
 436                 err = -EINVAL;
 437                 goto out;
 438         }
 439
 440         version = ipc_parse_version(&cmd);
 441
 442         switch (cmd) { /* replace with proc interface ? */
 443         case IPC_INFO:
 444         {
 445                 struct shminfo64 shminfo;
 446
 447                 err = security_shm_shmctl(NULL, cmd);
 448                 if (err)
 449                         return err;
 450
 451                 memset(&shminfo,0,sizeof(shminfo));
 452                 shminfo.shmmni = shminfo.shmseg = shm_ctlmni;
 453                 shminfo.shmmax = shm_ctlmax;
 454                 shminfo.shmall = shm_ctlall;
 455
 456                 shminfo.shmmin = SHMMIN;
 457                 if(copy_shminfo_to_user (buf, &shminfo, version))
 458                         return -EFAULT;
 459                 /* reading a integer is always atomic */
 460                 err= shm_ids.max_id;
 461                 if(err<0)
 462                         err = 0;
 463                 goto out;
 464         }
 465         case SHM_INFO:
 466         {
 467                 struct shm_info shm_info;
 468
 469                 err = security_shm_shmctl(NULL, cmd);
 470                 if (err)
 471                         return err;
 472
 473                 memset(&shm_info,0,sizeof(shm_info));
 474                 mutex_lock(&shm_ids.mutex);
 475                 shm_info.used_ids = shm_ids.in_use;
 476                 shm_get_stat (&shm_info.shm_rss, &shm_info.shm_swp);
 477                 shm_info.shm_tot = shm_tot;
 478                 shm_info.swap_attempts = 0;
 479                 shm_info.swap_successes = 0;
 480                 err = shm_ids.max_id;
 481                 mutex_unlock(&shm_ids.mutex);
 482                 if(copy_to_user (buf, &shm_info, sizeof(shm_info))) {
 483                         err = -EFAULT;
 484                         goto out;
 485                 }
 486
 487                 err = err < 0 ? 0 : err;
 488                 goto out;
 489         }
 490         case SHM_STAT:
 491         case IPC_STAT:
 492         {
 493                 struct shmid64_ds tbuf;
 494                 int result;
 495                 memset(&tbuf, 0, sizeof(tbuf));
 496                 shp = shm_lock(shmid);
 497                 if(shp==NULL) {
 498                         err = -EINVAL;
 499                         goto out;
 500                 } else if(cmd==SHM_STAT) {
 501                         err = -EINVAL;
 502                         if (shmid > shm_ids.max_id)
 503                                 goto out_unlock;
 504                         result = shm_buildid(shmid, shp->shm_perm.seq);
 505                 } else {
 506                         err = shm_checkid(shp,shmid);
 507                         if(err)
 508                                 goto out_unlock;
 509                         result = 0;
 510                 }
 511                 err=-EACCES;
 512                 if (ipcperms (&shp->shm_perm, S_IRUGO))
 513                         goto out_unlock;
 514                 err = security_shm_shmctl(shp, cmd);
 515                 if (err)
 516                         goto out_unlock;
 517                 kernel_to_ipc64_perm(&shp->shm_perm, &tbuf.shm_perm);
 518                 tbuf.shm_segsz  = shp->shm_segsz;
 519                 tbuf.shm_atime  = shp->shm_atim;
 520                 tbuf.shm_dtime  = shp->shm_dtim;
 521                 tbuf.shm_ctime  = shp->shm_ctim;
 522                 tbuf.shm_cpid   = shp->shm_cprid;
 523                 tbuf.shm_lpid   = shp->shm_lprid;
 524                 if (!is_file_hugepages(shp->shm_file))
 525                         tbuf.shm_nattch = shp->shm_nattch;
 526                 else
 527                         tbuf.shm_nattch = file_count(shp->shm_file) - 1;
 528                 shm_unlock(shp);
 529                 if(copy_shmid_to_user (buf, &tbuf, version))
 530                         err = -EFAULT;
 531                 else
 532                         err = result;
 533                 goto out;
 534         }
 535         case SHM_LOCK:
 536         case SHM_UNLOCK:
 537         {
 538                 shp = shm_lock(shmid);
 539                 if(shp==NULL) {
 540                         err = -EINVAL;
 541                         goto out;
 542                 }
 543                 err = shm_checkid(shp,shmid);
 544                 if(err)
 545                         goto out_unlock;
 546
 547                 err = audit_ipc_obj(&(shp->shm_perm));
 548                 if (err)
 549                         goto out_unlock;
 550
 551                 if (!capable(CAP_IPC_LOCK)) {
 552                         err = -EPERM;
 553                         if (current->euid != shp->shm_perm.uid &&
 554                             current->euid != shp->shm_perm.cuid)
 555                                 goto out_unlock;
 556                         if (cmd == SHM_LOCK &&
 557                             !current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur)
 558                                 goto out_unlock;
 559                 }
 560
 561                 err = security_shm_shmctl(shp, cmd);
 562                 if (err)
 563                         goto out_unlock;
 564
 565                 if(cmd==SHM_LOCK) {
 566                         struct user_struct * user = current->user;
 567                         if (!is_file_hugepages(shp->shm_file)) {
 568                                 err = shmem_lock(shp->shm_file, 1, user);
 569                                 if (!err) {
 570                                         shp->shm_perm.mode |= SHM_LOCKED;
 571                                         shp->mlock_user = user;
 572                                 }
 573                         }
 574                 } else if (!is_file_hugepages(shp->shm_file)) {
 575                         shmem_lock(shp->shm_file, 0, shp->mlock_user);
 576                         shp->shm_perm.mode &= ~SHM_LOCKED;
 577                         shp->mlock_user = NULL;
 578                 }
 579                 shm_unlock(shp);
 580                 goto out;
 581         }
 582         case IPC_RMID:
 583         {
 584                 /*
 585                  *      We cannot simply remove the file. The SVID states
 586                  *      that the block remains until the last person
 587                  *      detaches from it, then is deleted. A shmat() on
 588                  *      an RMID segment is legal in older Linux and if
 589                  *      we change it apps break...
 590                  *
 591                  *      Instead we set a destroyed flag, and then blow
 592                  *      the name away when the usage hits zero.
 593                  */
 594                 mutex_lock(&shm_ids.mutex);
 595                 shp = shm_lock(shmid);
 596                 err = -EINVAL;
 597                 if (shp == NULL)
 598                         goto out_up;
 599                 err = shm_checkid(shp, shmid);
 600                 if(err)
 601                         goto out_unlock_up;
 602
 603                 err = audit_ipc_obj(&(shp->shm_perm));
 604                 if (err)
 605                         goto out_unlock_up;
 606
 607                 if (current->euid != shp->shm_perm.uid &&
 608                     current->euid != shp->shm_perm.cuid &&
 609                     !capable(CAP_SYS_ADMIN)) {
 610                         err=-EPERM;
 611                         goto out_unlock_up;
 612                 }
 613
 614                 err = security_shm_shmctl(shp, cmd);
 615                 if (err)
 616                         goto out_unlock_up;
 617
 618                 if (shp->shm_nattch){
 619                         shp->shm_perm.mode |= SHM_DEST;
 620                         /* Do not find it any more */
 621                         shp->shm_perm.key = IPC_PRIVATE;
 622                         shm_unlock(shp);
 623                 } else
 624                         shm_destroy (shp);
 625                 mutex_unlock(&shm_ids.mutex);
 626                 goto out;
 627         }
 628
 629         case IPC_SET:
 630         {
 631                 if (copy_shmid_from_user (&setbuf, buf, version)) {
 632                         err = -EFAULT;
 633                         goto out;
 634                 }
 635                 mutex_lock(&shm_ids.mutex);
 636                 shp = shm_lock(shmid);
 637                 err=-EINVAL;
 638                 if(shp==NULL)
 639                         goto out_up;
 640                 err = shm_checkid(shp,shmid);
 641                 if(err)
 642                         goto out_unlock_up;
 643                 err = audit_ipc_obj(&(shp->shm_perm));
 644                 if (err)
 645                         goto out_unlock_up;
 646                 err = audit_ipc_set_perm(0, setbuf.uid, setbuf.gid, setbuf.mode, &(shp->shm_perm));
 647                 if (err)
 648                         goto out_unlock_up;
 649                 err=-EPERM;
 650                 if (current->euid != shp->shm_perm.uid &&
 651                     current->euid != shp->shm_perm.cuid &&
 652                     !capable(CAP_SYS_ADMIN)) {
 653                         goto out_unlock_up;
 654                 }
 655
 656                 err = security_shm_shmctl(shp, cmd);
 657                 if (err)
 658                         goto out_unlock_up;
 659
 660                 shp->shm_perm.uid = setbuf.uid;
 661                 shp->shm_perm.gid = setbuf.gid;
 662                 shp->shm_perm.mode = (shp->shm_perm.mode & ~S_IRWXUGO)
 663                         | (setbuf.mode & S_IRWXUGO);
 664                 shp->shm_ctim = get_seconds();
 665                 break;
 666         }
 667
 668         default:
 669                 err = -EINVAL;
 670                 goto out;
 671         }
 672
 673         err = 0;
 674 out_unlock_up:
 675         shm_unlock(shp);
 676 out_up:
 677         mutex_unlock(&shm_ids.mutex);
 678         goto out;
 679 out_unlock:
 680         shm_unlock(shp);
 681 out:
 682         return err;
 683 }
 684
 685 /*
 686  * Fix shmaddr, allocate descriptor, map shm, add attach descriptor to lists.
 687  *
 688  * NOTE! Despite the name, this is NOT a direct system call entrypoint. The
 689  * "raddr" thing points to kernel space, and there has to be a wrapper around
 690  * this.
 691  */
 692 long do_shmat(int shmid, char __user *shmaddr, int shmflg, ulong *raddr)
 693 {
 694         struct shmid_kernel *shp;
 695         unsigned long addr;
 696         unsigned long size;
 697         struct file * file;
 698         int    err;
 699         unsigned long flags;
 700         unsigned long prot;
 701         unsigned long o_flags;
 702         int acc_mode;
 703         void *user_addr;
 704
 705         if (shmid < 0) {
 706                 err = -EINVAL;
 707                 goto out;
 708         } else if ((addr = (ulong)shmaddr)) {
 709                 if (addr & (SHMLBA-1)) {
 710                         if (shmflg & SHM_RND)
 711                                 addr &= ~(SHMLBA-1);       /* round down */
 712                         else
 713 #ifndef __ARCH_FORCE_SHMLBA
 714                                 if (addr & ~PAGE_MASK)
 715 #endif
 716                                         return -EINVAL;
 717                 }
 718                 flags = MAP_SHARED | MAP_FIXED;
 719         } else {
 720                 if ((shmflg & SHM_REMAP))
 721                         return -EINVAL;
 722
 723                 flags = MAP_SHARED;
 724         }
 725
 726         if (shmflg & SHM_RDONLY) {
 727                 prot = PROT_READ;
 728                 o_flags = O_RDONLY;
 729                 acc_mode = S_IRUGO;
 730         } else {
 731                 prot = PROT_READ | PROT_WRITE;
 732                 o_flags = O_RDWR;
 733                 acc_mode = S_IRUGO | S_IWUGO;
 734         }
 735         if (shmflg & SHM_EXEC) {
 736                 prot |= PROT_EXEC;
 737                 acc_mode |= S_IXUGO;
 738         }
 739
 740         /*
 741          * We cannot rely on the fs check since SYSV IPC does have an
 742          * additional creator id...
 743          */
 744         shp = shm_lock(shmid);
 745         if(shp == NULL) {
 746                 err = -EINVAL;
 747                 goto out;
 748         }
 749         err = shm_checkid(shp,shmid);
 750         if (err) {
 751                 shm_unlock(shp);
 752                 goto out;
 753         }
 754         if (ipcperms(&shp->shm_perm, acc_mode)) {
 755                 shm_unlock(shp);
 756                 err = -EACCES;
 757                 goto out;
 758         }
 759
 760         err = security_shm_shmat(shp, shmaddr, shmflg);
 761         if (err) {
 762                 shm_unlock(shp);
 763                 return err;
 764         }
 765
 766         file = shp->shm_file;
 767         size = i_size_read(file->f_dentry->d_inode);
 768         shp->shm_nattch++;
 769         shm_unlock(shp);
 770
 771         down_write(&current->mm->mmap_sem);
 772         if (addr && !(shmflg & SHM_REMAP)) {
 773                 user_addr = ERR_PTR(-EINVAL);
 774                 if (find_vma_intersection(current->mm, addr, addr + size))
 775                         goto invalid;
 776                 /*
 777                  * If shm segment goes below stack, make sure there is some
 778                  * space left for the stack to grow (at least 4 pages).
 779                  */
 780                 if (addr < current->mm->start_stack &&
 781                     addr > current->mm->start_stack - size - PAGE_SIZE * 5)
 782                         goto invalid;
 783         }
 784
 785         user_addr = (void*) do_mmap (file, addr, size, prot, flags, 0);
 786
 787 invalid:
 788         up_write(&current->mm->mmap_sem);
 789
 790         mutex_lock(&shm_ids.mutex);
 791         shp = shm_lock(shmid);
 792         BUG_ON(!shp);
 793         shp->shm_nattch--;
 794         if(shp->shm_nattch == 0 &&
 795            shp->shm_perm.mode & SHM_DEST)
 796                 shm_destroy (shp);
 797         else
 798                 shm_unlock(shp);
 799         mutex_unlock(&shm_ids.mutex);
 800
 801         *raddr = (unsigned long) user_addr;
 802         err = 0;
 803         if (IS_ERR(user_addr))
 804                 err = PTR_ERR(user_addr);
 805 out:
 806         return err;
 807 }
 808
 809 asmlinkage long sys_shmat(int shmid, char __user *shmaddr, int shmflg)
 810 {
 811         unsigned long ret;
 812         long err;
 813
 814         err = do_shmat(shmid, shmaddr, shmflg, &ret);
 815         if (err)
 816                 return err;
 817         force_successful_syscall_return();
 818         return (long)ret;
 819 }
 820
 821 /*
 822  * detach and kill segment if marked destroyed.
 823  * The work is done in shm_close.
 824  */
 825 asmlinkage long sys_shmdt(char __user *shmaddr)
 826 {
 827         struct mm_struct *mm = current->mm;
 828         struct vm_area_struct *vma, *next;
 829         unsigned long addr = (unsigned long)shmaddr;
 830         loff_t size = 0;
 831         int retval = -EINVAL;
 832
 833         if (addr & ~PAGE_MASK)
 834                 return retval;
 835
 836         down_write(&mm->mmap_sem);
 837
 838         /*
 839          * This function tries to be smart and unmap shm segments that
 840          * were modified by partial mlock or munmap calls:
 841          * - It first determines the size of the shm segment that should be
 842          *   unmapped: It searches for a vma that is backed by shm and that
 843          *   started at address shmaddr. It records it's size and then unmaps
 844          *   it.
 845          * - Then it unmaps all shm vmas that started at shmaddr and that
 846          *   are within the initially determined size.
 847          * Errors from do_munmap are ignored: the function only fails if
 848          * it's called with invalid parameters or if it's called to unmap
 849          * a part of a vma. Both calls in this function are for full vmas,
 850          * the parameters are directly copied from the vma itself and always
 851          * valid - therefore do_munmap cannot fail. (famous last words?)
 852          */
 853         /*
 854          * If it had been mremap()'d, the starting address would not
 855          * match the usual checks anyway. So assume all vma's are
 856          * above the starting address given.
 857          */
 858         vma = find_vma(mm, addr);
 859
 860         while (vma) {
 861                 next = vma->vm_next;
 862
 863                 /*
 864                  * Check if the starting address would match, i.e. it's
 865                  * a fragment created by mprotect() and/or munmap(), or it
 866                  * otherwise it starts at this address with no hassles.
 867                  */
 868                 if ((vma->vm_ops == &shm_vm_ops || is_vm_hugetlb_page(vma)) &&
 869                         (vma->vm_start - addr)/PAGE_SIZE == vma->vm_pgoff) {
 870
 871
 872                         size = vma->vm_file->f_dentry->d_inode->i_size;
 873                         do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start);
 874                         /*
 875                          * We discovered the size of the shm segment, so
 876                          * break out of here and fall through to the next
 877                          * loop that uses the size information to stop
 878                          * searching for matching vma's.
 879                          */
 880                         retval = 0;
 881                         vma = next;
 882                         break;
 883                 }
 884                 vma = next;
 885         }
 886
 887         /*
 888          * We need look no further than the maximum address a fragment
 889          * could possibly have landed at. Also cast things to loff_t to
 890          * prevent overflows and make comparisions vs. equal-width types.
 891          */
 892         size = PAGE_ALIGN(size);
 893         while (vma && (loff_t)(vma->vm_end - addr) <= size) {
 894                 next = vma->vm_next;
 895
 896                 /* finding a matching vma now does not alter retval */
 897                 if ((vma->vm_ops == &shm_vm_ops || is_vm_hugetlb_page(vma)) &&
 898                         (vma->vm_start - addr)/PAGE_SIZE == vma->vm_pgoff)
 899
 900                         do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start);
 901                 vma = next;
 902         }
 903
 904         up_write(&mm->mmap_sem);
 905         return retval;
 906 }
 907
 908 #ifdef CONFIG_PROC_FS
 909 static int sysvipc_shm_proc_show(struct seq_file *s, void *it)
 910 {
 911         struct shmid_kernel *shp = it;
 912         char *format;
 913
 914 #define SMALL_STRING "%10d %10d  %4o %10u %5u %5u  %5d %5u %5u %5u %5u %10lu %10lu %10lu\n"
 915 #define BIG_STRING   "%10d %10d  %4o %21u %5u %5u  %5d %5u %5u %5u %5u %10lu %10lu %10lu\n"
 916
 917         if (sizeof(size_t) <= sizeof(int))
 918                 format = SMALL_STRING;
 919         else
 920                 format = BIG_STRING;
 921         return seq_printf(s, format,
 922                           shp->shm_perm.key,
 923                           shp->id,
 924                           shp->shm_perm.mode,
 925                           shp->shm_segsz,
 926                           shp->shm_cprid,
 927                           shp->shm_lprid,
 928                           is_file_hugepages(shp->shm_file) ? (file_count(shp->shm_file) - 1) : shp->shm_nattch,
 929                           shp->shm_perm.uid,
 930                           shp->shm_perm.gid,
 931                           shp->shm_perm.cuid,
 932                           shp->shm_perm.cgid,
 933                           shp->shm_atim,
 934                           shp->shm_dtim,
 935                           shp->shm_ctim);
 936 }
 937 #endif