ipc/shm.c

   1 /*
   2  * linux/ipc/shm.c
   3  * Copyright (C) 1992, 1993 Krishna Balasubramanian
   4  *       Many improvements/fixes by Bruno Haible.
   5  * Replaced `struct shm_desc' by `struct vm_area_struct', July 1994.
   6  * Fixed the shm swap deallocation (shm_unuse()), August 1998 Andrea Arcangeli.
   7  *
   8  * /proc/sysvipc/shm support (c) 1999 Dragos Acostachioaie <dragos@iname.com>
   9  * BIGMEM support, Andrea Arcangeli <andrea@suse.de>
  10  * SMP thread shm, Jean-Luc Boyard <jean-luc.boyard@siemens.fr>
  11  * HIGHMEM support, Ingo Molnar <mingo@redhat.com>
  12  * Make shmmax, shmall, shmmni sysctl'able, Christoph Rohland <cr@sap.com>
  13  * Shared /dev/zero support, Kanoj Sarcar <kanoj@sgi.com>
  14  * Move the mm functionality over to mm/shmem.c, Christoph Rohland <cr@sap.com>
  15  *
  16  * support for audit of ipc object properties and permission changes
  17  * Dustin Kirkland <dustin.kirkland@us.ibm.com>
  18  *
  19  * namespaces support
  20  * OpenVZ, SWsoft Inc.
  21  * Pavel Emelianov <xemul@openvz.org>
  22  */
  23
  24 #include <linux/slab.h>
  25 #include <linux/mm.h>
  26 #include <linux/hugetlb.h>
  27 #include <linux/shm.h>
  28 #include <linux/init.h>
  29 #include <linux/file.h>
  30 #include <linux/mman.h>
  31 #include <linux/shmem_fs.h>
  32 #include <linux/security.h>
  33 #include <linux/syscalls.h>
  34 #include <linux/audit.h>
  35 #include <linux/capability.h>
  36 #include <linux/ptrace.h>
  37 #include <linux/seq_file.h>
  38 #include <linux/mutex.h>
  39 #include <linux/nsproxy.h>
  40
  41 #include <asm/uaccess.h>
  42
  43 #include "util.h"
  44
  45 static const struct file_operations shm_file_operations;
  46 static struct vm_operations_struct shm_vm_ops;
  47
  48 static struct ipc_ids init_shm_ids;
  49
  50 #define shm_ids(ns)     (*((ns)->ids[IPC_SHM_IDS]))
  51
  52 #define shm_lock(ns, id)                \
  53         ((struct shmid_kernel*)ipc_lock(&shm_ids(ns),id))
  54 #define shm_unlock(shp)                 \
  55         ipc_unlock(&(shp)->shm_perm)
  56 #define shm_get(ns, id)                 \
  57         ((struct shmid_kernel*)ipc_get(&shm_ids(ns),id))
  58 #define shm_buildid(ns, id, seq)        \
  59         ipc_buildid(&shm_ids(ns), id, seq)
  60
  61 static int newseg (struct ipc_namespace *ns, key_t key,
  62                 int shmflg, size_t size);
  63 static void shm_open (struct vm_area_struct *shmd);
  64 static void shm_close (struct vm_area_struct *shmd);
  65 static void shm_destroy (struct ipc_namespace *ns, struct shmid_kernel *shp);
  66 #ifdef CONFIG_PROC_FS
  67 static int sysvipc_shm_proc_show(struct seq_file *s, void *it);
  68 #endif
  69
  70 static void __ipc_init __shm_init_ns(struct ipc_namespace *ns, struct ipc_ids *ids)
  71 {
  72         ns->ids[IPC_SHM_IDS] = ids;
  73         ns->shm_ctlmax = SHMMAX;
  74         ns->shm_ctlall = SHMALL;
  75         ns->shm_ctlmni = SHMMNI;
  76         ns->shm_tot = 0;
  77         ipc_init_ids(ids, 1);
  78 }
  79
  80 static void do_shm_rmid(struct ipc_namespace *ns, struct shmid_kernel *shp)
  81 {
  82         if (shp->shm_nattch){
  83                 shp->shm_perm.mode |= SHM_DEST;
  84                 /* Do not find it any more */
  85                 shp->shm_perm.key = IPC_PRIVATE;
  86                 shm_unlock(shp);
  87         } else
  88                 shm_destroy(ns, shp);
  89 }
  90
  91 #ifdef CONFIG_IPC_NS
  92 int shm_init_ns(struct ipc_namespace *ns)
  93 {
  94         struct ipc_ids *ids;
  95
  96         ids = kmalloc(sizeof(struct ipc_ids), GFP_KERNEL);
  97         if (ids == NULL)
  98                 return -ENOMEM;
  99
 100         __shm_init_ns(ns, ids);
 101         return 0;
 102 }
 103
 104 void shm_exit_ns(struct ipc_namespace *ns)
 105 {
 106         int i;
 107         struct shmid_kernel *shp;
 108
 109         mutex_lock(&shm_ids(ns).mutex);
 110         for (i = 0; i <= shm_ids(ns).max_id; i++) {
 111                 shp = shm_lock(ns, i);
 112                 if (shp == NULL)
 113                         continue;
 114
 115                 do_shm_rmid(ns, shp);
 116         }
 117         mutex_unlock(&shm_ids(ns).mutex);
 118
 119         ipc_fini_ids(ns->ids[IPC_SHM_IDS]);
 120         kfree(ns->ids[IPC_SHM_IDS]);
 121         ns->ids[IPC_SHM_IDS] = NULL;
 122 }
 123 #endif
 124
 125 void __init shm_init (void)
 126 {
 127         __shm_init_ns(&init_ipc_ns, &init_shm_ids);
 128         ipc_init_proc_interface("sysvipc/shm",
 129                                 "       key      shmid perms       size  cpid  lpid nattch   uid   gid  cuid  cgid      atime      dtime      ctime\n",
 130                                 IPC_SHM_IDS, sysvipc_shm_proc_show);
 131 }
 132
 133 static inline int shm_checkid(struct ipc_namespace *ns,
 134                 struct shmid_kernel *s, int id)
 135 {
 136         if (ipc_checkid(&shm_ids(ns), &s->shm_perm, id))
 137                 return -EIDRM;
 138         return 0;
 139 }
 140
 141 static inline struct shmid_kernel *shm_rmid(struct ipc_namespace *ns, int id)
 142 {
 143         return (struct shmid_kernel *)ipc_rmid(&shm_ids(ns), id);
 144 }
 145
 146 static inline int shm_addid(struct ipc_namespace *ns, struct shmid_kernel *shp)
 147 {
 148         return ipc_addid(&shm_ids(ns), &shp->shm_perm, ns->shm_ctlmni);
 149 }
 150
 151
 152
 153 static inline void shm_inc(struct ipc_namespace *ns, int id)
 154 {
 155         struct shmid_kernel *shp;
 156
 157         shp = shm_lock(ns, id);
 158         BUG_ON(!shp);
 159         shp->shm_atim = get_seconds();
 160         shp->shm_lprid = current->tgid;
 161         shp->shm_nattch++;
 162         shm_unlock(shp);
 163 }
 164
 165 #define shm_file_ns(file) (*((struct ipc_namespace **)&(file)->private_data))
 166
 167 /* This is called by fork, once for every shm attach. */
 168 static void shm_open(struct vm_area_struct *shmd)
 169 {
 170         shm_inc(shm_file_ns(shmd->vm_file),
 171                         shmd->vm_file->f_path.dentry->d_inode->i_ino);
 172 }
 173
 174 /*
 175  * shm_destroy - free the struct shmid_kernel
 176  *
 177  * @shp: struct to free
 178  *
 179  * It has to be called with shp and shm_ids.mutex locked,
 180  * but returns with shp unlocked and freed.
 181  */
 182 static void shm_destroy(struct ipc_namespace *ns, struct shmid_kernel *shp)
 183 {
 184         ns->shm_tot -= (shp->shm_segsz + PAGE_SIZE - 1) >> PAGE_SHIFT;
 185         shm_rmid(ns, shp->id);
 186         shm_unlock(shp);
 187         if (!is_file_hugepages(shp->shm_file))
 188                 shmem_lock(shp->shm_file, 0, shp->mlock_user);
 189         else
 190                 user_shm_unlock(shp->shm_file->f_path.dentry->d_inode->i_size,
 191                                                 shp->mlock_user);
 192         fput (shp->shm_file);
 193         security_shm_free(shp);
 194         ipc_rcu_putref(shp);
 195 }
 196
 197 /*
 198  * remove the attach descriptor shmd.
 199  * free memory for segment if it is marked destroyed.
 200  * The descriptor has already been removed from the current->mm->mmap list
 201  * and will later be kfree()d.
 202  */
 203 static void shm_close (struct vm_area_struct *shmd)
 204 {
 205         struct file * file = shmd->vm_file;
 206         int id = file->f_path.dentry->d_inode->i_ino;
 207         struct shmid_kernel *shp;
 208         struct ipc_namespace *ns;
 209
 210         ns = shm_file_ns(file);
 211
 212         mutex_lock(&shm_ids(ns).mutex);
 213         /* remove from the list of attaches of the shm segment */
 214         shp = shm_lock(ns, id);
 215         BUG_ON(!shp);
 216         shp->shm_lprid = current->tgid;
 217         shp->shm_dtim = get_seconds();
 218         shp->shm_nattch--;
 219         if(shp->shm_nattch == 0 &&
 220            shp->shm_perm.mode & SHM_DEST)
 221                 shm_destroy(ns, shp);
 222         else
 223                 shm_unlock(shp);
 224         mutex_unlock(&shm_ids(ns).mutex);
 225 }
 226
 227 static int shm_mmap(struct file * file, struct vm_area_struct * vma)
 228 {
 229         int ret;
 230
 231         ret = shmem_mmap(file, vma);
 232         if (ret == 0) {
 233                 vma->vm_ops = &shm_vm_ops;
 234                 if (!(vma->vm_flags & VM_WRITE))
 235                         vma->vm_flags &= ~VM_MAYWRITE;
 236                 shm_inc(shm_file_ns(file), file->f_path.dentry->d_inode->i_ino);
 237         }
 238
 239         return ret;
 240 }
 241
 242 static int shm_release(struct inode *ino, struct file *file)
 243 {
 244         struct ipc_namespace *ns;
 245
 246         ns = shm_file_ns(file);
 247         put_ipc_ns(ns);
 248         shm_file_ns(file) = NULL;
 249         return 0;
 250 }
 251
 252 static const struct file_operations shm_file_operations = {
 253         .mmap           = shm_mmap,
 254         .release        = shm_release,
 255 #ifndef CONFIG_MMU
 256         .get_unmapped_area = shmem_get_unmapped_area,
 257 #endif
 258 };
 259
 260 static struct vm_operations_struct shm_vm_ops = {
 261         .open   = shm_open,     /* callback for a new vm-area open */
 262         .close  = shm_close,    /* callback for when the vm-area is released */
 263         .nopage = shmem_nopage,
 264 #if defined(CONFIG_NUMA) && defined(CONFIG_SHMEM)
 265         .set_policy = shmem_set_policy,
 266         .get_policy = shmem_get_policy,
 267 #endif
 268 };
 269
 270 static int newseg (struct ipc_namespace *ns, key_t key, int shmflg, size_t size)
 271 {
 272         int error;
 273         struct shmid_kernel *shp;
 274         int numpages = (size + PAGE_SIZE -1) >> PAGE_SHIFT;
 275         struct file * file;
 276         char name[13];
 277         int id;
 278
 279         if (size < SHMMIN || size > ns->shm_ctlmax)
 280                 return -EINVAL;
 281
 282         if (ns->shm_tot + numpages > ns->shm_ctlall)
 283                 return -ENOSPC;
 284
 285         shp = ipc_rcu_alloc(sizeof(*shp));
 286         if (!shp)
 287                 return -ENOMEM;
 288
 289         shp->shm_perm.key = key;
 290         shp->shm_perm.mode = (shmflg & S_IRWXUGO);
 291         shp->mlock_user = NULL;
 292
 293         shp->shm_perm.security = NULL;
 294         error = security_shm_alloc(shp);
 295         if (error) {
 296                 ipc_rcu_putref(shp);
 297                 return error;
 298         }
 299
 300         if (shmflg & SHM_HUGETLB) {
 301                 /* hugetlb_zero_setup takes care of mlock user accounting */
 302                 file = hugetlb_zero_setup(size);
 303                 shp->mlock_user = current->user;
 304         } else {
 305                 int acctflag = VM_ACCOUNT;
 306                 /*
 307                  * Do not allow no accounting for OVERCOMMIT_NEVER, even
 308                  * if it's asked for.
 309                  */
 310                 if  ((shmflg & SHM_NORESERVE) &&
 311                                 sysctl_overcommit_memory != OVERCOMMIT_NEVER)
 312                         acctflag = 0;
 313                 sprintf (name, "SYSV%08x", key);
 314                 file = shmem_file_setup(name, size, acctflag);
 315         }
 316         error = PTR_ERR(file);
 317         if (IS_ERR(file))
 318                 goto no_file;
 319
 320         error = -ENOSPC;
 321         id = shm_addid(ns, shp);
 322         if(id == -1)
 323                 goto no_id;
 324
 325         shp->shm_cprid = current->tgid;
 326         shp->shm_lprid = 0;
 327         shp->shm_atim = shp->shm_dtim = 0;
 328         shp->shm_ctim = get_seconds();
 329         shp->shm_segsz = size;
 330         shp->shm_nattch = 0;
 331         shp->id = shm_buildid(ns, id, shp->shm_perm.seq);
 332         shp->shm_file = file;
 333         file->f_path.dentry->d_inode->i_ino = shp->id;
 334
 335         shm_file_ns(file) = get_ipc_ns(ns);
 336
 337         /* Hugetlb ops would have already been assigned. */
 338         if (!(shmflg & SHM_HUGETLB))
 339                 file->f_op = &shm_file_operations;
 340
 341         ns->shm_tot += numpages;
 342         shm_unlock(shp);
 343         return shp->id;
 344
 345 no_id:
 346         fput(file);
 347 no_file:
 348         security_shm_free(shp);
 349         ipc_rcu_putref(shp);
 350         return error;
 351 }
 352
 353 asmlinkage long sys_shmget (key_t key, size_t size, int shmflg)
 354 {
 355         struct shmid_kernel *shp;
 356         int err, id = 0;
 357         struct ipc_namespace *ns;
 358
 359         ns = current->nsproxy->ipc_ns;
 360
 361         mutex_lock(&shm_ids(ns).mutex);
 362         if (key == IPC_PRIVATE) {
 363                 err = newseg(ns, key, shmflg, size);
 364         } else if ((id = ipc_findkey(&shm_ids(ns), key)) == -1) {
 365                 if (!(shmflg & IPC_CREAT))
 366                         err = -ENOENT;
 367                 else
 368                         err = newseg(ns, key, shmflg, size);
 369         } else if ((shmflg & IPC_CREAT) && (shmflg & IPC_EXCL)) {
 370                 err = -EEXIST;
 371         } else {
 372                 shp = shm_lock(ns, id);
 373                 BUG_ON(shp==NULL);
 374                 if (shp->shm_segsz < size)
 375                         err = -EINVAL;
 376                 else if (ipcperms(&shp->shm_perm, shmflg))
 377                         err = -EACCES;
 378                 else {
 379                         int shmid = shm_buildid(ns, id, shp->shm_perm.seq);
 380                         err = security_shm_associate(shp, shmflg);
 381                         if (!err)
 382                                 err = shmid;
 383                 }
 384                 shm_unlock(shp);
 385         }
 386         mutex_unlock(&shm_ids(ns).mutex);
 387
 388         return err;
 389 }
 390
 391 static inline unsigned long copy_shmid_to_user(void __user *buf, struct shmid64_ds *in, int version)
 392 {
 393         switch(version) {
 394         case IPC_64:
 395                 return copy_to_user(buf, in, sizeof(*in));
 396         case IPC_OLD:
 397             {
 398                 struct shmid_ds out;
 399
 400                 ipc64_perm_to_ipc_perm(&in->shm_perm, &out.shm_perm);
 401                 out.shm_segsz   = in->shm_segsz;
 402                 out.shm_atime   = in->shm_atime;
 403                 out.shm_dtime   = in->shm_dtime;
 404                 out.shm_ctime   = in->shm_ctime;
 405                 out.shm_cpid    = in->shm_cpid;
 406                 out.shm_lpid    = in->shm_lpid;
 407                 out.shm_nattch  = in->shm_nattch;
 408
 409                 return copy_to_user(buf, &out, sizeof(out));
 410             }
 411         default:
 412                 return -EINVAL;
 413         }
 414 }
 415
 416 struct shm_setbuf {
 417         uid_t   uid;
 418         gid_t   gid;
 419         mode_t  mode;
 420 };
 421
 422 static inline unsigned long copy_shmid_from_user(struct shm_setbuf *out, void __user *buf, int version)
 423 {
 424         switch(version) {
 425         case IPC_64:
 426             {
 427                 struct shmid64_ds tbuf;
 428
 429                 if (copy_from_user(&tbuf, buf, sizeof(tbuf)))
 430                         return -EFAULT;
 431
 432                 out->uid        = tbuf.shm_perm.uid;
 433                 out->gid        = tbuf.shm_perm.gid;
 434                 out->mode       = tbuf.shm_perm.mode;
 435
 436                 return 0;
 437             }
 438         case IPC_OLD:
 439             {
 440                 struct shmid_ds tbuf_old;
 441
 442                 if (copy_from_user(&tbuf_old, buf, sizeof(tbuf_old)))
 443                         return -EFAULT;
 444
 445                 out->uid        = tbuf_old.shm_perm.uid;
 446                 out->gid        = tbuf_old.shm_perm.gid;
 447                 out->mode       = tbuf_old.shm_perm.mode;
 448
 449                 return 0;
 450             }
 451         default:
 452                 return -EINVAL;
 453         }
 454 }
 455
 456 static inline unsigned long copy_shminfo_to_user(void __user *buf, struct shminfo64 *in, int version)
 457 {
 458         switch(version) {
 459         case IPC_64:
 460                 return copy_to_user(buf, in, sizeof(*in));
 461         case IPC_OLD:
 462             {
 463                 struct shminfo out;
 464
 465                 if(in->shmmax > INT_MAX)
 466                         out.shmmax = INT_MAX;
 467                 else
 468                         out.shmmax = (int)in->shmmax;
 469
 470                 out.shmmin      = in->shmmin;
 471                 out.shmmni      = in->shmmni;
 472                 out.shmseg      = in->shmseg;
 473                 out.shmall      = in->shmall;
 474
 475                 return copy_to_user(buf, &out, sizeof(out));
 476             }
 477         default:
 478                 return -EINVAL;
 479         }
 480 }
 481
 482 static void shm_get_stat(struct ipc_namespace *ns, unsigned long *rss,
 483                 unsigned long *swp)
 484 {
 485         int i;
 486
 487         *rss = 0;
 488         *swp = 0;
 489
 490         for (i = 0; i <= shm_ids(ns).max_id; i++) {
 491                 struct shmid_kernel *shp;
 492                 struct inode *inode;
 493
 494                 shp = shm_get(ns, i);
 495                 if(!shp)
 496                         continue;
 497
 498                 inode = shp->shm_file->f_path.dentry->d_inode;
 499
 500                 if (is_file_hugepages(shp->shm_file)) {
 501                         struct address_space *mapping = inode->i_mapping;
 502                         *rss += (HPAGE_SIZE/PAGE_SIZE)*mapping->nrpages;
 503                 } else {
 504                         struct shmem_inode_info *info = SHMEM_I(inode);
 505                         spin_lock(&info->lock);
 506                         *rss += inode->i_mapping->nrpages;
 507                         *swp += info->swapped;
 508                         spin_unlock(&info->lock);
 509                 }
 510         }
 511 }
 512
 513 asmlinkage long sys_shmctl (int shmid, int cmd, struct shmid_ds __user *buf)
 514 {
 515         struct shm_setbuf setbuf;
 516         struct shmid_kernel *shp;
 517         int err, version;
 518         struct ipc_namespace *ns;
 519
 520         if (cmd < 0 || shmid < 0) {
 521                 err = -EINVAL;
 522                 goto out;
 523         }
 524
 525         version = ipc_parse_version(&cmd);
 526         ns = current->nsproxy->ipc_ns;
 527
 528         switch (cmd) { /* replace with proc interface ? */
 529         case IPC_INFO:
 530         {
 531                 struct shminfo64 shminfo;
 532
 533                 err = security_shm_shmctl(NULL, cmd);
 534                 if (err)
 535                         return err;
 536
 537                 memset(&shminfo,0,sizeof(shminfo));
 538                 shminfo.shmmni = shminfo.shmseg = ns->shm_ctlmni;
 539                 shminfo.shmmax = ns->shm_ctlmax;
 540                 shminfo.shmall = ns->shm_ctlall;
 541
 542                 shminfo.shmmin = SHMMIN;
 543                 if(copy_shminfo_to_user (buf, &shminfo, version))
 544                         return -EFAULT;
 545                 /* reading a integer is always atomic */
 546                 err= shm_ids(ns).max_id;
 547                 if(err<0)
 548                         err = 0;
 549                 goto out;
 550         }
 551         case SHM_INFO:
 552         {
 553                 struct shm_info shm_info;
 554
 555                 err = security_shm_shmctl(NULL, cmd);
 556                 if (err)
 557                         return err;
 558
 559                 memset(&shm_info,0,sizeof(shm_info));
 560                 mutex_lock(&shm_ids(ns).mutex);
 561                 shm_info.used_ids = shm_ids(ns).in_use;
 562                 shm_get_stat (ns, &shm_info.shm_rss, &shm_info.shm_swp);
 563                 shm_info.shm_tot = ns->shm_tot;
 564                 shm_info.swap_attempts = 0;
 565                 shm_info.swap_successes = 0;
 566                 err = shm_ids(ns).max_id;
 567                 mutex_unlock(&shm_ids(ns).mutex);
 568                 if(copy_to_user (buf, &shm_info, sizeof(shm_info))) {
 569                         err = -EFAULT;
 570                         goto out;
 571                 }
 572
 573                 err = err < 0 ? 0 : err;
 574                 goto out;
 575         }
 576         case SHM_STAT:
 577         case IPC_STAT:
 578         {
 579                 struct shmid64_ds tbuf;
 580                 int result;
 581                 memset(&tbuf, 0, sizeof(tbuf));
 582                 shp = shm_lock(ns, shmid);
 583                 if(shp==NULL) {
 584                         err = -EINVAL;
 585                         goto out;
 586                 } else if(cmd==SHM_STAT) {
 587                         err = -EINVAL;
 588                         if (shmid > shm_ids(ns).max_id)
 589                                 goto out_unlock;
 590                         result = shm_buildid(ns, shmid, shp->shm_perm.seq);
 591                 } else {
 592                         err = shm_checkid(ns, shp,shmid);
 593                         if(err)
 594                                 goto out_unlock;
 595                         result = 0;
 596                 }
 597                 err=-EACCES;
 598                 if (ipcperms (&shp->shm_perm, S_IRUGO))
 599                         goto out_unlock;
 600                 err = security_shm_shmctl(shp, cmd);
 601                 if (err)
 602                         goto out_unlock;
 603                 kernel_to_ipc64_perm(&shp->shm_perm, &tbuf.shm_perm);
 604                 tbuf.shm_segsz  = shp->shm_segsz;
 605                 tbuf.shm_atime  = shp->shm_atim;
 606                 tbuf.shm_dtime  = shp->shm_dtim;
 607                 tbuf.shm_ctime  = shp->shm_ctim;
 608                 tbuf.shm_cpid   = shp->shm_cprid;
 609                 tbuf.shm_lpid   = shp->shm_lprid;
 610                 if (!is_file_hugepages(shp->shm_file))
 611                         tbuf.shm_nattch = shp->shm_nattch;
 612                 else
 613                         tbuf.shm_nattch = file_count(shp->shm_file) - 1;
 614                 shm_unlock(shp);
 615                 if(copy_shmid_to_user (buf, &tbuf, version))
 616                         err = -EFAULT;
 617                 else
 618                         err = result;
 619                 goto out;
 620         }
 621         case SHM_LOCK:
 622         case SHM_UNLOCK:
 623         {
 624                 shp = shm_lock(ns, shmid);
 625                 if(shp==NULL) {
 626                         err = -EINVAL;
 627                         goto out;
 628                 }
 629                 err = shm_checkid(ns, shp,shmid);
 630                 if(err)
 631                         goto out_unlock;
 632
 633                 err = audit_ipc_obj(&(shp->shm_perm));
 634                 if (err)
 635                         goto out_unlock;
 636
 637                 if (!capable(CAP_IPC_LOCK)) {
 638                         err = -EPERM;
 639                         if (current->euid != shp->shm_perm.uid &&
 640                             current->euid != shp->shm_perm.cuid)
 641                                 goto out_unlock;
 642                         if (cmd == SHM_LOCK &&
 643                             !current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur)
 644                                 goto out_unlock;
 645                 }
 646
 647                 err = security_shm_shmctl(shp, cmd);
 648                 if (err)
 649                         goto out_unlock;
 650
 651                 if(cmd==SHM_LOCK) {
 652                         struct user_struct * user = current->user;
 653                         if (!is_file_hugepages(shp->shm_file)) {
 654                                 err = shmem_lock(shp->shm_file, 1, user);
 655                                 if (!err) {
 656                                         shp->shm_perm.mode |= SHM_LOCKED;
 657                                         shp->mlock_user = user;
 658                                 }
 659                         }
 660                 } else if (!is_file_hugepages(shp->shm_file)) {
 661                         shmem_lock(shp->shm_file, 0, shp->mlock_user);
 662                         shp->shm_perm.mode &= ~SHM_LOCKED;
 663                         shp->mlock_user = NULL;
 664                 }
 665                 shm_unlock(shp);
 666                 goto out;
 667         }
 668         case IPC_RMID:
 669         {
 670                 /*
 671                  *      We cannot simply remove the file. The SVID states
 672                  *      that the block remains until the last person
 673                  *      detaches from it, then is deleted. A shmat() on
 674                  *      an RMID segment is legal in older Linux and if
 675                  *      we change it apps break...
 676                  *
 677                  *      Instead we set a destroyed flag, and then blow
 678                  *      the name away when the usage hits zero.
 679                  */
 680                 mutex_lock(&shm_ids(ns).mutex);
 681                 shp = shm_lock(ns, shmid);
 682                 err = -EINVAL;
 683                 if (shp == NULL)
 684                         goto out_up;
 685                 err = shm_checkid(ns, shp, shmid);
 686                 if(err)
 687                         goto out_unlock_up;
 688
 689                 err = audit_ipc_obj(&(shp->shm_perm));
 690                 if (err)
 691                         goto out_unlock_up;
 692
 693                 if (current->euid != shp->shm_perm.uid &&
 694                     current->euid != shp->shm_perm.cuid &&
 695                     !capable(CAP_SYS_ADMIN)) {
 696                         err=-EPERM;
 697                         goto out_unlock_up;
 698                 }
 699
 700                 err = security_shm_shmctl(shp, cmd);
 701                 if (err)
 702                         goto out_unlock_up;
 703
 704                 do_shm_rmid(ns, shp);
 705                 mutex_unlock(&shm_ids(ns).mutex);
 706                 goto out;
 707         }
 708
 709         case IPC_SET:
 710         {
 711                 if (copy_shmid_from_user (&setbuf, buf, version)) {
 712                         err = -EFAULT;
 713                         goto out;
 714                 }
 715                 mutex_lock(&shm_ids(ns).mutex);
 716                 shp = shm_lock(ns, shmid);
 717                 err=-EINVAL;
 718                 if(shp==NULL)
 719                         goto out_up;
 720                 err = shm_checkid(ns, shp,shmid);
 721                 if(err)
 722                         goto out_unlock_up;
 723                 err = audit_ipc_obj(&(shp->shm_perm));
 724                 if (err)
 725                         goto out_unlock_up;
 726                 err = audit_ipc_set_perm(0, setbuf.uid, setbuf.gid, setbuf.mode);
 727                 if (err)
 728                         goto out_unlock_up;
 729                 err=-EPERM;
 730                 if (current->euid != shp->shm_perm.uid &&
 731                     current->euid != shp->shm_perm.cuid &&
 732                     !capable(CAP_SYS_ADMIN)) {
 733                         goto out_unlock_up;
 734                 }
 735
 736                 err = security_shm_shmctl(shp, cmd);
 737                 if (err)
 738                         goto out_unlock_up;
 739
 740                 shp->shm_perm.uid = setbuf.uid;
 741                 shp->shm_perm.gid = setbuf.gid;
 742                 shp->shm_perm.mode = (shp->shm_perm.mode & ~S_IRWXUGO)
 743                         | (setbuf.mode & S_IRWXUGO);
 744                 shp->shm_ctim = get_seconds();
 745                 break;
 746         }
 747
 748         default:
 749                 err = -EINVAL;
 750                 goto out;
 751         }
 752
 753         err = 0;
 754 out_unlock_up:
 755         shm_unlock(shp);
 756 out_up:
 757         mutex_unlock(&shm_ids(ns).mutex);
 758         goto out;
 759 out_unlock:
 760         shm_unlock(shp);
 761 out:
 762         return err;
 763 }
 764
 765 /*
 766  * Fix shmaddr, allocate descriptor, map shm, add attach descriptor to lists.
 767  *
 768  * NOTE! Despite the name, this is NOT a direct system call entrypoint. The
 769  * "raddr" thing points to kernel space, and there has to be a wrapper around
 770  * this.
 771  */
 772 long do_shmat(int shmid, char __user *shmaddr, int shmflg, ulong *raddr)
 773 {
 774         struct shmid_kernel *shp;
 775         unsigned long addr;
 776         unsigned long size;
 777         struct file * file;
 778         int    err;
 779         unsigned long flags;
 780         unsigned long prot;
 781         int acc_mode;
 782         void *user_addr;
 783         struct ipc_namespace *ns;
 784
 785         if (shmid < 0) {
 786                 err = -EINVAL;
 787                 goto out;
 788         } else if ((addr = (ulong)shmaddr)) {
 789                 if (addr & (SHMLBA-1)) {
 790                         if (shmflg & SHM_RND)
 791                                 addr &= ~(SHMLBA-1);       /* round down */
 792                         else
 793 #ifndef __ARCH_FORCE_SHMLBA
 794                                 if (addr & ~PAGE_MASK)
 795 #endif
 796                                         return -EINVAL;
 797                 }
 798                 flags = MAP_SHARED | MAP_FIXED;
 799         } else {
 800                 if ((shmflg & SHM_REMAP))
 801                         return -EINVAL;
 802
 803                 flags = MAP_SHARED;
 804         }
 805
 806         if (shmflg & SHM_RDONLY) {
 807                 prot = PROT_READ;
 808                 acc_mode = S_IRUGO;
 809         } else {
 810                 prot = PROT_READ | PROT_WRITE;
 811                 acc_mode = S_IRUGO | S_IWUGO;
 812         }
 813         if (shmflg & SHM_EXEC) {
 814                 prot |= PROT_EXEC;
 815                 acc_mode |= S_IXUGO;
 816         }
 817
 818         /*
 819          * We cannot rely on the fs check since SYSV IPC does have an
 820          * additional creator id...
 821          */
 822         ns = current->nsproxy->ipc_ns;
 823         shp = shm_lock(ns, shmid);
 824         if(shp == NULL) {
 825                 err = -EINVAL;
 826                 goto out;
 827         }
 828         err = shm_checkid(ns, shp,shmid);
 829         if (err) {
 830                 shm_unlock(shp);
 831                 goto out;
 832         }
 833         if (ipcperms(&shp->shm_perm, acc_mode)) {
 834                 shm_unlock(shp);
 835                 err = -EACCES;
 836                 goto out;
 837         }
 838
 839         err = security_shm_shmat(shp, shmaddr, shmflg);
 840         if (err) {
 841                 shm_unlock(shp);
 842                 return err;
 843         }
 844
 845         file = shp->shm_file;
 846         size = i_size_read(file->f_path.dentry->d_inode);
 847         shp->shm_nattch++;
 848         shm_unlock(shp);
 849
 850         down_write(&current->mm->mmap_sem);
 851         if (addr && !(shmflg & SHM_REMAP)) {
 852                 user_addr = ERR_PTR(-EINVAL);
 853                 if (find_vma_intersection(current->mm, addr, addr + size))
 854                         goto invalid;
 855                 /*
 856                  * If shm segment goes below stack, make sure there is some
 857                  * space left for the stack to grow (at least 4 pages).
 858                  */
 859                 if (addr < current->mm->start_stack &&
 860                     addr > current->mm->start_stack - size - PAGE_SIZE * 5)
 861                         goto invalid;
 862         }
 863
 864         user_addr = (void*) do_mmap (file, addr, size, prot, flags, 0);
 865
 866 invalid:
 867         up_write(&current->mm->mmap_sem);
 868
 869         mutex_lock(&shm_ids(ns).mutex);
 870         shp = shm_lock(ns, shmid);
 871         BUG_ON(!shp);
 872         shp->shm_nattch--;
 873         if(shp->shm_nattch == 0 &&
 874            shp->shm_perm.mode & SHM_DEST)
 875                 shm_destroy(ns, shp);
 876         else
 877                 shm_unlock(shp);
 878         mutex_unlock(&shm_ids(ns).mutex);
 879
 880         *raddr = (unsigned long) user_addr;
 881         err = 0;
 882         if (IS_ERR(user_addr))
 883                 err = PTR_ERR(user_addr);
 884 out:
 885         return err;
 886 }
 887
 888 asmlinkage long sys_shmat(int shmid, char __user *shmaddr, int shmflg)
 889 {
 890         unsigned long ret;
 891         long err;
 892
 893         err = do_shmat(shmid, shmaddr, shmflg, &ret);
 894         if (err)
 895                 return err;
 896         force_successful_syscall_return();
 897         return (long)ret;
 898 }
 899
 900 /*
 901  * detach and kill segment if marked destroyed.
 902  * The work is done in shm_close.
 903  */
 904 asmlinkage long sys_shmdt(char __user *shmaddr)
 905 {
 906         struct mm_struct *mm = current->mm;
 907         struct vm_area_struct *vma, *next;
 908         unsigned long addr = (unsigned long)shmaddr;
 909         loff_t size = 0;
 910         int retval = -EINVAL;
 911
 912         if (addr & ~PAGE_MASK)
 913                 return retval;
 914
 915         down_write(&mm->mmap_sem);
 916
 917         /*
 918          * This function tries to be smart and unmap shm segments that
 919          * were modified by partial mlock or munmap calls:
 920          * - It first determines the size of the shm segment that should be
 921          *   unmapped: It searches for a vma that is backed by shm and that
 922          *   started at address shmaddr. It records it's size and then unmaps
 923          *   it.
 924          * - Then it unmaps all shm vmas that started at shmaddr and that
 925          *   are within the initially determined size.
 926          * Errors from do_munmap are ignored: the function only fails if
 927          * it's called with invalid parameters or if it's called to unmap
 928          * a part of a vma. Both calls in this function are for full vmas,
 929          * the parameters are directly copied from the vma itself and always
 930          * valid - therefore do_munmap cannot fail. (famous last words?)
 931          */
 932         /*
 933          * If it had been mremap()'d, the starting address would not
 934          * match the usual checks anyway. So assume all vma's are
 935          * above the starting address given.
 936          */
 937         vma = find_vma(mm, addr);
 938
 939         while (vma) {
 940                 next = vma->vm_next;
 941
 942                 /*
 943                  * Check if the starting address would match, i.e. it's
 944                  * a fragment created by mprotect() and/or munmap(), or it
 945                  * otherwise it starts at this address with no hassles.
 946                  */
 947                 if ((vma->vm_ops == &shm_vm_ops || is_vm_hugetlb_page(vma)) &&
 948                         (vma->vm_start - addr)/PAGE_SIZE == vma->vm_pgoff) {
 949
 950
 951                         size = vma->vm_file->f_path.dentry->d_inode->i_size;
 952                         do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start);
 953                         /*
 954                          * We discovered the size of the shm segment, so
 955                          * break out of here and fall through to the next
 956                          * loop that uses the size information to stop
 957                          * searching for matching vma's.
 958                          */
 959                         retval = 0;
 960                         vma = next;
 961                         break;
 962                 }
 963                 vma = next;
 964         }
 965
 966         /*
 967          * We need look no further than the maximum address a fragment
 968          * could possibly have landed at. Also cast things to loff_t to
 969          * prevent overflows and make comparisions vs. equal-width types.
 970          */
 971         size = PAGE_ALIGN(size);
 972         while (vma && (loff_t)(vma->vm_end - addr) <= size) {
 973                 next = vma->vm_next;
 974
 975                 /* finding a matching vma now does not alter retval */
 976                 if ((vma->vm_ops == &shm_vm_ops || is_vm_hugetlb_page(vma)) &&
 977                         (vma->vm_start - addr)/PAGE_SIZE == vma->vm_pgoff)
 978
 979                         do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start);
 980                 vma = next;
 981         }
 982
 983         up_write(&mm->mmap_sem);
 984         return retval;
 985 }
 986
 987 #ifdef CONFIG_PROC_FS
 988 static int sysvipc_shm_proc_show(struct seq_file *s, void *it)
 989 {
 990         struct shmid_kernel *shp = it;
 991         char *format;
 992
 993 #define SMALL_STRING "%10d %10d  %4o %10u %5u %5u  %5d %5u %5u %5u %5u %10lu %10lu %10lu\n"
 994 #define BIG_STRING   "%10d %10d  %4o %21u %5u %5u  %5d %5u %5u %5u %5u %10lu %10lu %10lu\n"
 995
 996         if (sizeof(size_t) <= sizeof(int))
 997                 format = SMALL_STRING;
 998         else
 999                 format = BIG_STRING;
1000         return seq_printf(s, format,
1001                           shp->shm_perm.key,
1002                           shp->id,
1003                           shp->shm_perm.mode,
1004                           shp->shm_segsz,
1005                           shp->shm_cprid,
1006                           shp->shm_lprid,
1007                           is_file_hugepages(shp->shm_file) ? (file_count(shp->shm_file) - 1) : shp->shm_nattch,
1008                           shp->shm_perm.uid,
1009                           shp->shm_perm.gid,
1010                           shp->shm_perm.cuid,
1011                           shp->shm_perm.cgid,
1012                           shp->shm_atim,
1013                           shp->shm_dtim,
1014                           shp->shm_ctim);
1015 }
1016 #endif