drivers/staging/lustre/lustre/libcfs/linux/linux-curproc.c

   1 /*
   2  * GPL HEADER START
   3  *
   4  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 only,
   8  * as published by the Free Software Foundation.
   9  *
  10  * This program is distributed in the hope that it will be useful, but
  11  * WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13  * General Public License version 2 for more details (a copy is included
  14  * in the LICENSE file that accompanied this code).
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * version 2 along with this program; If not, see
  18  * http://www.sun.com/software/products/lustre/docs/GPLv2.pdf
  19  *
  20  * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
  21  * CA 95054 USA or visit www.sun.com if you need additional information or
  22  * have any questions.
  23  *
  24  * GPL HEADER END
  25  */
  26 /*
  27  * Copyright (c) 2008, 2010, Oracle and/or its affiliates. All rights reserved.
  28  * Use is subject to license terms.
  29  *
  30  * Copyright (c) 2011, 2012, Intel Corporation.
  31  */
  32 /*
  33  * This file is part of Lustre, http://www.lustre.org/
  34  * Lustre is a trademark of Sun Microsystems, Inc.
  35  *
  36  * libcfs/libcfs/linux/linux-curproc.c
  37  *
  38  * Lustre curproc API implementation for Linux kernel
  39  *
  40  * Author: Nikita Danilov <nikita@clusterfs.com>
  41  */
  42
  43 #include <linux/sched.h>
  44 #include <linux/fs_struct.h>
  45
  46 #include <linux/compat.h>
  47 #include <linux/thread_info.h>
  48
  49 #define DEBUG_SUBSYSTEM S_LNET
  50
  51 #include <linux/libcfs/libcfs.h>
  52
  53 /*
  54  * Implementation of cfs_curproc API (see portals/include/libcfs/curproc.h)
  55  * for Linux kernel.
  56  */
  57
  58 int    cfs_curproc_groups_nr(void)
  59 {
  60         int nr;
  61
  62         task_lock(current);
  63         nr = current_cred()->group_info->ngroups;
  64         task_unlock(current);
  65         return nr;
  66 }
  67
  68 /* Currently all the CFS_CAP_* defines match CAP_* ones. */
  69 #define cfs_cap_pack(cap) (cap)
  70 #define cfs_cap_unpack(cap) (cap)
  71
  72 void cfs_cap_raise(cfs_cap_t cap)
  73 {
  74         struct cred *cred;
  75         if ((cred = prepare_creds())) {
  76                 cap_raise(cred->cap_effective, cfs_cap_unpack(cap));
  77                 commit_creds(cred);
  78         }
  79 }
  80
  81 void cfs_cap_lower(cfs_cap_t cap)
  82 {
  83         struct cred *cred;
  84         if ((cred = prepare_creds())) {
  85                 cap_lower(cred->cap_effective, cfs_cap_unpack(cap));
  86                 commit_creds(cred);
  87         }
  88 }
  89
  90 int cfs_cap_raised(cfs_cap_t cap)
  91 {
  92         return cap_raised(current_cap(), cfs_cap_unpack(cap));
  93 }
  94
  95 void cfs_kernel_cap_pack(kernel_cap_t kcap, cfs_cap_t *cap)
  96 {
  97 #if defined (_LINUX_CAPABILITY_VERSION) && _LINUX_CAPABILITY_VERSION == 0x19980330
  98         *cap = cfs_cap_pack(kcap);
  99 #elif defined (_LINUX_CAPABILITY_VERSION) && _LINUX_CAPABILITY_VERSION == 0x20071026
 100         *cap = cfs_cap_pack(kcap[0]);
 101 #elif defined(_KERNEL_CAPABILITY_VERSION) && _KERNEL_CAPABILITY_VERSION == 0x20080522
 102         /* XXX lost high byte */
 103         *cap = cfs_cap_pack(kcap.cap[0]);
 104 #else
 105         #error "need correct _KERNEL_CAPABILITY_VERSION "
 106 #endif
 107 }
 108
 109 void cfs_kernel_cap_unpack(kernel_cap_t *kcap, cfs_cap_t cap)
 110 {
 111 #if defined (_LINUX_CAPABILITY_VERSION) && _LINUX_CAPABILITY_VERSION == 0x19980330
 112         *kcap = cfs_cap_unpack(cap);
 113 #elif defined (_LINUX_CAPABILITY_VERSION) && _LINUX_CAPABILITY_VERSION == 0x20071026
 114         (*kcap)[0] = cfs_cap_unpack(cap);
 115 #elif defined(_KERNEL_CAPABILITY_VERSION) && _KERNEL_CAPABILITY_VERSION == 0x20080522
 116         kcap->cap[0] = cfs_cap_unpack(cap);
 117 #else
 118         #error "need correct _KERNEL_CAPABILITY_VERSION "
 119 #endif
 120 }
 121
 122 cfs_cap_t cfs_curproc_cap_pack(void)
 123 {
 124         cfs_cap_t cap;
 125         cfs_kernel_cap_pack(current_cap(), &cap);
 126         return cap;
 127 }
 128
 129 void cfs_curproc_cap_unpack(cfs_cap_t cap)
 130 {
 131         struct cred *cred;
 132         if ((cred = prepare_creds())) {
 133                 cfs_kernel_cap_unpack(&cred->cap_effective, cap);
 134                 commit_creds(cred);
 135         }
 136 }
 137
 138 int cfs_capable(cfs_cap_t cap)
 139 {
 140         return capable(cfs_cap_unpack(cap));
 141 }
 142
 143 static int cfs_access_process_vm(struct task_struct *tsk, unsigned long addr,
 144                                  void *buf, int len, int write)
 145 {
 146         /* Just copied from kernel for the kernels which doesn't
 147          * have access_process_vm() exported */
 148         struct mm_struct *mm;
 149         struct vm_area_struct *vma;
 150         struct page *page;
 151         void *old_buf = buf;
 152
 153         mm = get_task_mm(tsk);
 154         if (!mm)
 155                 return 0;
 156
 157         down_read(&mm->mmap_sem);
 158         /* ignore errors, just check how much was successfully transferred */
 159         while (len) {
 160                 int bytes, rc, offset;
 161                 void *maddr;
 162
 163                 rc = get_user_pages(tsk, mm, addr, 1,
 164                                      write, 1, &page, &vma);
 165                 if (rc <= 0)
 166                         break;
 167
 168                 bytes = len;
 169                 offset = addr & (PAGE_SIZE-1);
 170                 if (bytes > PAGE_SIZE-offset)
 171                         bytes = PAGE_SIZE-offset;
 172
 173                 maddr = kmap(page);
 174                 if (write) {
 175                         copy_to_user_page(vma, page, addr,
 176                                           maddr + offset, buf, bytes);
 177                         set_page_dirty_lock(page);
 178                 } else {
 179                         copy_from_user_page(vma, page, addr,
 180                                             buf, maddr + offset, bytes);
 181                 }
 182                 kunmap(page);
 183                 page_cache_release(page);
 184                 len -= bytes;
 185                 buf += bytes;
 186                 addr += bytes;
 187         }
 188         up_read(&mm->mmap_sem);
 189         mmput(mm);
 190
 191         return buf - old_buf;
 192 }
 193
 194 /* Read the environment variable of current process specified by @key. */
 195 int cfs_get_environ(const char *key, char *value, int *val_len)
 196 {
 197         struct mm_struct *mm;
 198         char *buffer, *tmp_buf = NULL;
 199         int buf_len = PAGE_CACHE_SIZE;
 200         int key_len = strlen(key);
 201         unsigned long addr;
 202         int rc;
 203
 204         buffer = kmalloc(buf_len, GFP_USER);
 205         if (!buffer)
 206                 return -ENOMEM;
 207
 208         mm = get_task_mm(current);
 209         if (!mm) {
 210                 kfree(buffer);
 211                 return -EINVAL;
 212         }
 213
 214         /* Avoid deadlocks on mmap_sem if called from sys_mmap_pgoff(),
 215          * which is already holding mmap_sem for writes.  If some other
 216          * thread gets the write lock in the meantime, this thread will
 217          * block, but at least it won't deadlock on itself.  LU-1735 */
 218         if (down_read_trylock(&mm->mmap_sem) == 0) {
 219                 kfree(buffer);
 220                 return -EDEADLK;
 221         }
 222         up_read(&mm->mmap_sem);
 223
 224         addr = mm->env_start;
 225         while (addr < mm->env_end) {
 226                 int this_len, retval, scan_len;
 227                 char *env_start, *env_end;
 228
 229                 memset(buffer, 0, buf_len);
 230
 231                 this_len = min_t(int, mm->env_end - addr, buf_len);
 232                 retval = cfs_access_process_vm(current, addr, buffer,
 233                                                this_len, 0);
 234                 if (retval != this_len)
 235                         break;
 236
 237                 addr += retval;
 238
 239                 /* Parse the buffer to find out the specified key/value pair.
 240                  * The "key=value" entries are separated by '\0'. */
 241                 env_start = buffer;
 242                 scan_len = this_len;
 243                 while (scan_len) {
 244                         char *entry;
 245                         int entry_len;
 246
 247                         env_end = memscan(env_start, '\0', scan_len);
 248                         LASSERT(env_end >= env_start &&
 249                                 env_end <= env_start + scan_len);
 250
 251                         /* The last entry of this buffer cross the buffer
 252                          * boundary, reread it in next cycle. */
 253                         if (unlikely(env_end - env_start == scan_len)) {
 254                                 /* This entry is too large to fit in buffer */
 255                                 if (unlikely(scan_len == this_len)) {
 256                                         CERROR("Too long env variable.\n");
 257                                         GOTO(out, rc = -EINVAL);
 258                                 }
 259                                 addr -= scan_len;
 260                                 break;
 261                         }
 262
 263                         entry = env_start;
 264                         entry_len = env_end - env_start;
 265
 266                         /* Key length + length of '=' */
 267                         if (entry_len > key_len + 1 &&
 268                             !memcmp(entry, key, key_len)) {
 269                                 entry += key_len + 1;
 270                                 entry_len -= key_len + 1;
 271                                 /* The 'value' buffer passed in is too small.*/
 272                                 if (entry_len >= *val_len)
 273                                         GOTO(out, rc = -EOVERFLOW);
 274
 275                                 memcpy(value, entry, entry_len);
 276                                 *val_len = entry_len;
 277                                 GOTO(out, rc = 0);
 278                         }
 279
 280                         scan_len -= (env_end - env_start + 1);
 281                         env_start = env_end + 1;
 282                 }
 283         }
 284         GOTO(out, rc = -ENOENT);
 285
 286 out:
 287         mmput(mm);
 288         kfree((void *)buffer);
 289         if (tmp_buf)
 290                 kfree((void *)tmp_buf);
 291         return rc;
 292 }
 293 EXPORT_SYMBOL(cfs_get_environ);
 294
 295 EXPORT_SYMBOL(cfs_curproc_groups_nr);
 296 EXPORT_SYMBOL(cfs_cap_raise);
 297 EXPORT_SYMBOL(cfs_cap_lower);
 298 EXPORT_SYMBOL(cfs_cap_raised);
 299 EXPORT_SYMBOL(cfs_curproc_cap_pack);
 300 EXPORT_SYMBOL(cfs_curproc_cap_unpack);
 301 EXPORT_SYMBOL(cfs_capable);
 302
 303 /*
 304  * Local variables:
 305  * c-indentation-style: "K&R"
 306  * c-basic-offset: 8
 307  * tab-width: 8
 308  * fill-column: 80
 309  * scroll-step: 1
 310  * End:
 311  */