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 /* Check if task is running in 32-bit API mode, for the purpose of
 144  * userspace binary interfaces.  On 32-bit Linux this is (unfortunately)
 145  * always true, even if the application is using LARGEFILE64 and 64-bit
 146  * APIs, because Linux provides no way for the filesystem to know if it
 147  * is called via 32-bit or 64-bit APIs.  Other clients may vary.  On
 148  * 64-bit systems, this will only be true if the binary is calling a
 149  * 32-bit system call. */
 150 int current_is_32bit(void)
 151 {
 152         return is_compat_task();
 153 }
 154
 155 static int cfs_access_process_vm(struct task_struct *tsk, unsigned long addr,
 156                                  void *buf, int len, int write)
 157 {
 158         /* Just copied from kernel for the kernels which doesn't
 159          * have access_process_vm() exported */
 160         struct mm_struct *mm;
 161         struct vm_area_struct *vma;
 162         struct page *page;
 163         void *old_buf = buf;
 164
 165         mm = get_task_mm(tsk);
 166         if (!mm)
 167                 return 0;
 168
 169         down_read(&mm->mmap_sem);
 170         /* ignore errors, just check how much was sucessfully transfered */
 171         while (len) {
 172                 int bytes, rc, offset;
 173                 void *maddr;
 174
 175                 rc = get_user_pages(tsk, mm, addr, 1,
 176                                      write, 1, &page, &vma);
 177                 if (rc <= 0)
 178                         break;
 179
 180                 bytes = len;
 181                 offset = addr & (PAGE_SIZE-1);
 182                 if (bytes > PAGE_SIZE-offset)
 183                         bytes = PAGE_SIZE-offset;
 184
 185                 maddr = kmap(page);
 186                 if (write) {
 187                         copy_to_user_page(vma, page, addr,
 188                                           maddr + offset, buf, bytes);
 189                         set_page_dirty_lock(page);
 190                 } else {
 191                         copy_from_user_page(vma, page, addr,
 192                                             buf, maddr + offset, bytes);
 193                 }
 194                 kunmap(page);
 195                 page_cache_release(page);
 196                 len -= bytes;
 197                 buf += bytes;
 198                 addr += bytes;
 199         }
 200         up_read(&mm->mmap_sem);
 201         mmput(mm);
 202
 203         return buf - old_buf;
 204 }
 205
 206 /* Read the environment variable of current process specified by @key. */
 207 int cfs_get_environ(const char *key, char *value, int *val_len)
 208 {
 209         struct mm_struct *mm;
 210         char *buffer, *tmp_buf = NULL;
 211         int buf_len = PAGE_CACHE_SIZE;
 212         int key_len = strlen(key);
 213         unsigned long addr;
 214         int rc;
 215
 216         buffer = kmalloc(buf_len, GFP_USER);
 217         if (!buffer)
 218                 return -ENOMEM;
 219
 220         mm = get_task_mm(current);
 221         if (!mm) {
 222                 kfree(buffer);
 223                 return -EINVAL;
 224         }
 225
 226         /* Avoid deadlocks on mmap_sem if called from sys_mmap_pgoff(),
 227          * which is already holding mmap_sem for writes.  If some other
 228          * thread gets the write lock in the meantime, this thread will
 229          * block, but at least it won't deadlock on itself.  LU-1735 */
 230         if (down_read_trylock(&mm->mmap_sem) == 0)
 231                 return -EDEADLK;
 232         up_read(&mm->mmap_sem);
 233
 234         addr = mm->env_start;
 235         while (addr < mm->env_end) {
 236                 int this_len, retval, scan_len;
 237                 char *env_start, *env_end;
 238
 239                 memset(buffer, 0, buf_len);
 240
 241                 this_len = min_t(int, mm->env_end - addr, buf_len);
 242                 retval = cfs_access_process_vm(current, addr, buffer,
 243                                                this_len, 0);
 244                 if (retval != this_len)
 245                         break;
 246
 247                 addr += retval;
 248
 249                 /* Parse the buffer to find out the specified key/value pair.
 250                  * The "key=value" entries are separated by '\0'. */
 251                 env_start = buffer;
 252                 scan_len = this_len;
 253                 while (scan_len) {
 254                         char *entry;
 255                         int entry_len;
 256
 257                         env_end = memscan(env_start, '\0', scan_len);
 258                         LASSERT(env_end >= env_start &&
 259                                 env_end <= env_start + scan_len);
 260
 261                         /* The last entry of this buffer cross the buffer
 262                          * boundary, reread it in next cycle. */
 263                         if (unlikely(env_end - env_start == scan_len)) {
 264                                 /* This entry is too large to fit in buffer */
 265                                 if (unlikely(scan_len == this_len)) {
 266                                         CERROR("Too long env variable.\n");
 267                                         GOTO(out, rc = -EINVAL);
 268                                 }
 269                                 addr -= scan_len;
 270                                 break;
 271                         }
 272
 273                         entry = env_start;
 274                         entry_len = env_end - env_start;
 275
 276                         /* Key length + length of '=' */
 277                         if (entry_len > key_len + 1 &&
 278                             !memcmp(entry, key, key_len)) {
 279                                 entry += key_len + 1;
 280                                 entry_len -= key_len + 1;
 281                                 /* The 'value' buffer passed in is too small.*/
 282                                 if (entry_len >= *val_len)
 283                                         GOTO(out, rc = -EOVERFLOW);
 284
 285                                 memcpy(value, entry, entry_len);
 286                                 *val_len = entry_len;
 287                                 GOTO(out, rc = 0);
 288                         }
 289
 290                         scan_len -= (env_end - env_start + 1);
 291                         env_start = env_end + 1;
 292                 }
 293         }
 294         GOTO(out, rc = -ENOENT);
 295
 296 out:
 297         mmput(mm);
 298         kfree((void *)buffer);
 299         if (tmp_buf)
 300                 kfree((void *)tmp_buf);
 301         return rc;
 302 }
 303 EXPORT_SYMBOL(cfs_get_environ);
 304
 305 EXPORT_SYMBOL(cfs_curproc_groups_nr);
 306 EXPORT_SYMBOL(cfs_cap_raise);
 307 EXPORT_SYMBOL(cfs_cap_lower);
 308 EXPORT_SYMBOL(cfs_cap_raised);
 309 EXPORT_SYMBOL(cfs_curproc_cap_pack);
 310 EXPORT_SYMBOL(cfs_curproc_cap_unpack);
 311 EXPORT_SYMBOL(cfs_capable);
 312 EXPORT_SYMBOL(current_is_32bit);
 313
 314 /*
 315  * Local variables:
 316  * c-indentation-style: "K&R"
 317  * c-basic-offset: 8
 318  * tab-width: 8
 319  * fill-column: 80
 320  * scroll-step: 1
 321  * End:
 322  */