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