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, 2017, 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 #ifdef HAVE_SCHED_HEADERS
  41 #include <linux/sched/signal.h>
  42 #include <linux/sched/mm.h>
  43 #endif
  44 #include <linux/fs_struct.h>
  45 #include <linux/pagemap.h>
  46 #include <linux/compat.h>
  47 #include <linux/thread_info.h>
  48
  49 #define DEBUG_SUBSYSTEM S_LNET
  50
  51 #include <libcfs/libcfs.h>
  52
  53 /*
  54  * Implementation of cfs_curproc API (see portals/include/libcfs/curproc.h)
  55  * for Linux kernel.
  56  */
  57
  58 /* Currently all the CFS_CAP_* defines match CAP_* ones. */
  59 #define cfs_cap_pack(cap) (cap)
  60 #define cfs_cap_unpack(cap) (cap)
  61
  62 void cfs_cap_raise(cfs_cap_t cap)
  63 {
  64         struct cred *cred;
  65         if ((cred = prepare_creds())) {
  66                 cap_raise(cred->cap_effective, cfs_cap_unpack(cap));
  67                 commit_creds(cred);
  68         }
  69 }
  70
  71 void cfs_cap_lower(cfs_cap_t cap)
  72 {
  73         struct cred *cred;
  74         if ((cred = prepare_creds())) {
  75                 cap_lower(cred->cap_effective, cfs_cap_unpack(cap));
  76                 commit_creds(cred);
  77         }
  78 }
  79
  80 int cfs_cap_raised(cfs_cap_t cap)
  81 {
  82         return cap_raised(current_cap(), cfs_cap_unpack(cap));
  83 }
  84
  85 static void cfs_kernel_cap_pack(kernel_cap_t kcap, cfs_cap_t *cap)
  86 {
  87 #if defined (_LINUX_CAPABILITY_VERSION) && _LINUX_CAPABILITY_VERSION == 0x19980330
  88         *cap = cfs_cap_pack(kcap);
  89 #elif defined (_LINUX_CAPABILITY_VERSION) && _LINUX_CAPABILITY_VERSION == 0x20071026
  90         *cap = cfs_cap_pack(kcap[0]);
  91 #elif defined(_KERNEL_CAPABILITY_VERSION) && _KERNEL_CAPABILITY_VERSION == 0x20080522
  92         /* XXX lost high byte */
  93         *cap = cfs_cap_pack(kcap.cap[0]);
  94 #else
  95         #error "need correct _KERNEL_CAPABILITY_VERSION "
  96 #endif
  97 }
  98
  99 static void cfs_kernel_cap_unpack(kernel_cap_t *kcap, cfs_cap_t cap)
 100 {
 101 #if defined (_LINUX_CAPABILITY_VERSION) && _LINUX_CAPABILITY_VERSION == 0x19980330
 102         *kcap = cfs_cap_unpack(cap);
 103 #elif defined (_LINUX_CAPABILITY_VERSION) && _LINUX_CAPABILITY_VERSION == 0x20071026
 104         (*kcap)[0] = cfs_cap_unpack(cap);
 105 #elif defined(_KERNEL_CAPABILITY_VERSION) && _KERNEL_CAPABILITY_VERSION == 0x20080522
 106         kcap->cap[0] = cfs_cap_unpack(cap);
 107 #else
 108         #error "need correct _KERNEL_CAPABILITY_VERSION "
 109 #endif
 110 }
 111
 112 cfs_cap_t cfs_curproc_cap_pack(void)
 113 {
 114         cfs_cap_t cap;
 115         cfs_kernel_cap_pack(current_cap(), &cap);
 116         return cap;
 117 }
 118
 119 void cfs_curproc_cap_unpack(cfs_cap_t cap)
 120 {
 121         struct cred *cred;
 122         if ((cred = prepare_creds())) {
 123                 cfs_kernel_cap_unpack(&cred->cap_effective, cap);
 124                 commit_creds(cred);
 125         }
 126 }
 127
 128 int cfs_capable(cfs_cap_t cap)
 129 {
 130         return capable(cfs_cap_unpack(cap));
 131 }
 132
 133 static int cfs_access_process_vm(struct task_struct *tsk,
 134                                  struct mm_struct *mm,
 135                                  unsigned long addr,
 136                                  void *buf, int len, int write)
 137 {
 138         /* Just copied from kernel for the kernels which doesn't
 139          * have access_process_vm() exported */
 140         struct vm_area_struct *vma;
 141         struct page *page;
 142         void *old_buf = buf;
 143
 144         /* Avoid deadlocks on mmap_sem if called from sys_mmap_pgoff(),
 145          * which is already holding mmap_sem for writes.  If some other
 146          * thread gets the write lock in the meantime, this thread will
 147          * block, but at least it won't deadlock on itself.  LU-1735 */
 148         if (down_read_trylock(&mm->mmap_sem) == 0)
 149                 return -EDEADLK;
 150
 151         /* ignore errors, just check how much was successfully transferred */
 152         while (len) {
 153                 int bytes, rc, offset;
 154                 void *maddr;
 155
 156 #if defined(HAVE_GET_USER_PAGES_GUP_FLAGS)
 157                 rc = get_user_pages(addr, 1, write ? FOLL_WRITE : 0, &page, &vma);
 158 #elif defined(HAVE_GET_USER_PAGES_6ARG)
 159                 rc = get_user_pages(addr, 1, write, 1, &page, &vma);
 160 #else
 161                 rc = get_user_pages(tsk, mm, addr, 1, write, 1, &page, &vma);
 162 #endif
 163                 if (rc <= 0)
 164                         break;
 165
 166                 bytes = len;
 167                 offset = addr & (PAGE_SIZE-1);
 168                 if (bytes > PAGE_SIZE-offset)
 169                         bytes = PAGE_SIZE-offset;
 170
 171                 maddr = kmap(page);
 172                 if (write) {
 173                         copy_to_user_page(vma, page, addr,
 174                                           maddr + offset, buf, bytes);
 175                         set_page_dirty_lock(page);
 176                 } else {
 177                         copy_from_user_page(vma, page, addr,
 178                                             buf, maddr + offset, bytes);
 179                 }
 180                 kunmap(page);
 181                 put_page(page);
 182                 len -= bytes;
 183                 buf += bytes;
 184                 addr += bytes;
 185         }
 186         up_read(&mm->mmap_sem);
 187
 188         return buf - old_buf;
 189 }
 190
 191 /* Read the environment variable of current process specified by @key. */
 192 int cfs_get_environ(const char *key, char *value, int *val_len)
 193 {
 194         struct mm_struct *mm;
 195         char *buffer;
 196         int buf_len = PAGE_SIZE;
 197         int key_len = strlen(key);
 198         unsigned long addr;
 199         int rc;
 200         bool skip = false;
 201         ENTRY;
 202
 203         buffer = kmalloc(buf_len, GFP_USER);
 204         if (!buffer)
 205                 RETURN(-ENOMEM);
 206
 207         mm = get_task_mm(current);
 208         if (!mm) {
 209                 kfree(buffer);
 210                 RETURN(-EINVAL);
 211         }
 212
 213         addr = mm->env_start;
 214         while (addr < mm->env_end) {
 215                 int this_len, retval, scan_len;
 216                 char *env_start, *env_end;
 217
 218                 memset(buffer, 0, buf_len);
 219
 220                 this_len = min_t(int, mm->env_end - addr, buf_len);
 221                 retval = cfs_access_process_vm(current, mm, addr, buffer,
 222                                                this_len, 0);
 223                 if (retval < 0)
 224                         GOTO(out, rc = retval);
 225                 else if (retval != this_len)
 226                         break;
 227
 228                 addr += retval;
 229
 230                 /* Parse the buffer to find out the specified key/value pair.
 231                  * The "key=value" entries are separated by '\0'. */
 232                 env_start = buffer;
 233                 scan_len = this_len;
 234                 while (scan_len) {
 235                         char *entry;
 236                         int entry_len;
 237
 238                         env_end = memscan(env_start, '\0', scan_len);
 239                         LASSERT(env_end >= env_start &&
 240                                 env_end <= env_start + scan_len);
 241
 242                         /* The last entry of this buffer cross the buffer
 243                          * boundary, reread it in next cycle. */
 244                         if (unlikely(env_end - env_start == scan_len)) {
 245                                 /* Just skip the entry larger than page size,
 246                                  * it can't be jobID env variable. */
 247                                 if (unlikely(scan_len == this_len))
 248                                         skip = true;
 249                                 else
 250                                         addr -= scan_len;
 251                                 break;
 252                         } else if (unlikely(skip)) {
 253                                 skip = false;
 254                                 goto skip;
 255                         }
 256
 257                         entry = env_start;
 258                         entry_len = env_end - env_start;
 259
 260                         /* Key length + length of '=' */
 261                         if (entry_len > key_len + 1 &&
 262                             !memcmp(entry, key, key_len)) {
 263                                 entry += key_len + 1;
 264                                 entry_len -= key_len + 1;
 265                                 /* The 'value' buffer passed in is too small.*/
 266                                 if (entry_len >= *val_len)
 267                                         GOTO(out, rc = -EOVERFLOW);
 268
 269                                 memcpy(value, entry, entry_len);
 270                                 *val_len = entry_len;
 271                                 GOTO(out, rc = 0);
 272                         }
 273 skip:
 274                         scan_len -= (env_end - env_start + 1);
 275                         env_start = env_end + 1;
 276                 }
 277         }
 278         GOTO(out, rc = -ENOENT);
 279
 280 out:
 281         mmput(mm);
 282         kfree((void *)buffer);
 283         return rc;
 284 }
 285 EXPORT_SYMBOL(cfs_get_environ);
 286
 287 EXPORT_SYMBOL(cfs_cap_raise);
 288 EXPORT_SYMBOL(cfs_cap_lower);
 289 EXPORT_SYMBOL(cfs_cap_raised);
 290 EXPORT_SYMBOL(cfs_curproc_cap_pack);
 291 EXPORT_SYMBOL(cfs_capable);
 292
 293 /*
 294  * Local variables:
 295  * c-indentation-style: "K&R"
 296  * c-basic-offset: 8
 297  * tab-width: 8
 298  * fill-column: 80
 299  * scroll-step: 1
 300  * End:
 301  */