libcfs/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.gnu.org/licenses/gpl-2.0.html
  19  *
  20  * GPL HEADER END
  21  */
  22 /*
  23  * Copyright (c) 2008, 2010, Oracle and/or its affiliates. All rights reserved.
  24  * Use is subject to license terms.
  25  *
  26  * Copyright (c) 2012, 2015, Intel Corporation.
  27  */
  28 /*
  29  * This file is part of Lustre, http://www.lustre.org/
  30  * Lustre is a trademark of Sun Microsystems, Inc.
  31  *
  32  * libcfs/libcfs/linux/linux-curproc.c
  33  *
  34  * Lustre curproc API implementation for Linux kernel
  35  *
  36  * Author: Nikita Danilov <nikita@clusterfs.com>
  37  */
  38
  39 #include <linux/sched.h>
  40 #include <linux/fs_struct.h>
  41
  42 #include <linux/compat.h>
  43 #include <linux/thread_info.h>
  44
  45 #define DEBUG_SUBSYSTEM S_LNET
  46
  47 #include <libcfs/libcfs.h>
  48
  49 /*
  50  * Implementation of cfs_curproc API (see portals/include/libcfs/curproc.h)
  51  * for Linux kernel.
  52  */
  53
  54 /* Currently all the CFS_CAP_* defines match CAP_* ones. */
  55 #define cfs_cap_pack(cap) (cap)
  56 #define cfs_cap_unpack(cap) (cap)
  57
  58 void cfs_cap_raise(cfs_cap_t cap)
  59 {
  60         struct cred *cred;
  61         if ((cred = prepare_creds())) {
  62                 cap_raise(cred->cap_effective, cfs_cap_unpack(cap));
  63                 commit_creds(cred);
  64         }
  65 }
  66
  67 void cfs_cap_lower(cfs_cap_t cap)
  68 {
  69         struct cred *cred;
  70         if ((cred = prepare_creds())) {
  71                 cap_lower(cred->cap_effective, cfs_cap_unpack(cap));
  72                 commit_creds(cred);
  73         }
  74 }
  75
  76 int cfs_cap_raised(cfs_cap_t cap)
  77 {
  78         return cap_raised(current_cap(), cfs_cap_unpack(cap));
  79 }
  80
  81 static void cfs_kernel_cap_pack(kernel_cap_t kcap, cfs_cap_t *cap)
  82 {
  83 #if defined (_LINUX_CAPABILITY_VERSION) && _LINUX_CAPABILITY_VERSION == 0x19980330
  84         *cap = cfs_cap_pack(kcap);
  85 #elif defined (_LINUX_CAPABILITY_VERSION) && _LINUX_CAPABILITY_VERSION == 0x20071026
  86         *cap = cfs_cap_pack(kcap[0]);
  87 #elif defined(_KERNEL_CAPABILITY_VERSION) && _KERNEL_CAPABILITY_VERSION == 0x20080522
  88         /* XXX lost high byte */
  89         *cap = cfs_cap_pack(kcap.cap[0]);
  90 #else
  91         #error "need correct _KERNEL_CAPABILITY_VERSION "
  92 #endif
  93 }
  94
  95 static void cfs_kernel_cap_unpack(kernel_cap_t *kcap, cfs_cap_t cap)
  96 {
  97 #if defined (_LINUX_CAPABILITY_VERSION) && _LINUX_CAPABILITY_VERSION == 0x19980330
  98         *kcap = cfs_cap_unpack(cap);
  99 #elif defined (_LINUX_CAPABILITY_VERSION) && _LINUX_CAPABILITY_VERSION == 0x20071026
 100         (*kcap)[0] = cfs_cap_unpack(cap);
 101 #elif defined(_KERNEL_CAPABILITY_VERSION) && _KERNEL_CAPABILITY_VERSION == 0x20080522
 102         kcap->cap[0] = cfs_cap_unpack(cap);
 103 #else
 104         #error "need correct _KERNEL_CAPABILITY_VERSION "
 105 #endif
 106 }
 107
 108 cfs_cap_t cfs_curproc_cap_pack(void)
 109 {
 110         cfs_cap_t cap;
 111         cfs_kernel_cap_pack(current_cap(), &cap);
 112         return cap;
 113 }
 114
 115 void cfs_curproc_cap_unpack(cfs_cap_t cap)
 116 {
 117         struct cred *cred;
 118         if ((cred = prepare_creds())) {
 119                 cfs_kernel_cap_unpack(&cred->cap_effective, cap);
 120                 commit_creds(cred);
 121         }
 122 }
 123
 124 int cfs_capable(cfs_cap_t cap)
 125 {
 126         return capable(cfs_cap_unpack(cap));
 127 }
 128
 129 static int cfs_access_process_vm(struct task_struct *tsk,
 130                                  struct mm_struct *mm,
 131                                  unsigned long addr,
 132                                  void *buf, int len, int write)
 133 {
 134         /* Just copied from kernel for the kernels which doesn't
 135          * have access_process_vm() exported */
 136         struct vm_area_struct *vma;
 137         struct page *page;
 138         void *old_buf = buf;
 139
 140         /* Avoid deadlocks on mmap_sem if called from sys_mmap_pgoff(),
 141          * which is already holding mmap_sem for writes.  If some other
 142          * thread gets the write lock in the meantime, this thread will
 143          * block, but at least it won't deadlock on itself.  LU-1735 */
 144         if (down_read_trylock(&mm->mmap_sem) == 0)
 145                 return -EDEADLK;
 146
 147         /* ignore errors, just check how much was successfully transferred */
 148         while (len) {
 149                 int bytes, rc, offset;
 150                 void *maddr;
 151
 152 #if defined(HAVE_GET_USER_PAGES_GUP_FLAGS)
 153                 rc = get_user_pages(addr, 1, write ? FOLL_WRITE : 0, &page, &vma);
 154 #elif defined(HAVE_GET_USER_PAGES_6ARG)
 155                 rc = get_user_pages(addr, 1, write, 1, &page, &vma);
 156 #else
 157                 rc = get_user_pages(tsk, mm, addr, 1, write, 1, &page, &vma);
 158 #endif
 159                 if (rc <= 0)
 160                         break;
 161
 162                 bytes = len;
 163                 offset = addr & (PAGE_SIZE-1);
 164                 if (bytes > PAGE_SIZE-offset)
 165                         bytes = PAGE_SIZE-offset;
 166
 167                 maddr = kmap(page);
 168                 if (write) {
 169                         copy_to_user_page(vma, page, addr,
 170                                           maddr + offset, buf, bytes);
 171                         set_page_dirty_lock(page);
 172                 } else {
 173                         copy_from_user_page(vma, page, addr,
 174                                             buf, maddr + offset, bytes);
 175                 }
 176                 kunmap(page);
 177                 put_page(page);
 178                 len -= bytes;
 179                 buf += bytes;
 180                 addr += bytes;
 181         }
 182         up_read(&mm->mmap_sem);
 183
 184         return buf - old_buf;
 185 }
 186
 187 /* Read the environment variable of current process specified by @key. */
 188 int cfs_get_environ(const char *key, char *value, int *val_len)
 189 {
 190         struct mm_struct *mm;
 191         char *buffer;
 192         int buf_len = PAGE_SIZE;
 193         int key_len = strlen(key);
 194         unsigned long addr;
 195         int rc;
 196         bool skip = false;
 197         ENTRY;
 198
 199         buffer = kmalloc(buf_len, GFP_USER);
 200         if (!buffer)
 201                 RETURN(-ENOMEM);
 202
 203         mm = get_task_mm(current);
 204         if (!mm) {
 205                 kfree(buffer);
 206                 RETURN(-EINVAL);
 207         }
 208
 209         addr = mm->env_start;
 210         while (addr < mm->env_end) {
 211                 int this_len, retval, scan_len;
 212                 char *env_start, *env_end;
 213
 214                 memset(buffer, 0, buf_len);
 215
 216                 this_len = min_t(int, mm->env_end - addr, buf_len);
 217                 retval = cfs_access_process_vm(current, mm, addr, buffer,
 218                                                this_len, 0);
 219                 if (retval < 0)
 220                         GOTO(out, rc = retval);
 221                 else if (retval != this_len)
 222                         break;
 223
 224                 addr += retval;
 225
 226                 /* Parse the buffer to find out the specified key/value pair.
 227                  * The "key=value" entries are separated by '\0'. */
 228                 env_start = buffer;
 229                 scan_len = this_len;
 230                 while (scan_len) {
 231                         char *entry;
 232                         int entry_len;
 233
 234                         env_end = memscan(env_start, '\0', scan_len);
 235                         LASSERT(env_end >= env_start &&
 236                                 env_end <= env_start + scan_len);
 237
 238                         /* The last entry of this buffer cross the buffer
 239                          * boundary, reread it in next cycle. */
 240                         if (unlikely(env_end - env_start == scan_len)) {
 241                                 /* Just skip the entry larger than page size,
 242                                  * it can't be jobID env variable. */
 243                                 if (unlikely(scan_len == this_len))
 244                                         skip = true;
 245                                 else
 246                                         addr -= scan_len;
 247                                 break;
 248                         } else if (unlikely(skip)) {
 249                                 skip = false;
 250                                 goto skip;
 251                         }
 252
 253                         entry = env_start;
 254                         entry_len = env_end - env_start;
 255
 256                         /* Key length + length of '=' */
 257                         if (entry_len > key_len + 1 &&
 258                             !memcmp(entry, key, key_len)) {
 259                                 entry += key_len + 1;
 260                                 entry_len -= key_len + 1;
 261                                 /* The 'value' buffer passed in is too small.*/
 262                                 if (entry_len >= *val_len)
 263                                         GOTO(out, rc = -EOVERFLOW);
 264
 265                                 memcpy(value, entry, entry_len);
 266                                 *val_len = entry_len;
 267                                 GOTO(out, rc = 0);
 268                         }
 269 skip:
 270                         scan_len -= (env_end - env_start + 1);
 271                         env_start = env_end + 1;
 272                 }
 273         }
 274         GOTO(out, rc = -ENOENT);
 275
 276 out:
 277         mmput(mm);
 278         kfree((void *)buffer);
 279         return rc;
 280 }
 281 EXPORT_SYMBOL(cfs_get_environ);
 282
 283 EXPORT_SYMBOL(cfs_cap_raise);
 284 EXPORT_SYMBOL(cfs_cap_lower);
 285 EXPORT_SYMBOL(cfs_cap_raised);
 286 EXPORT_SYMBOL(cfs_curproc_cap_pack);
 287 EXPORT_SYMBOL(cfs_capable);
 288
 289 /*
 290  * Local variables:
 291  * c-indentation-style: "K&R"
 292  * c-basic-offset: 8
 293  * tab-width: 8
 294  * fill-column: 80
 295  * scroll-step: 1
 296  * End:
 297  */