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