wrapper/random.c

   1 /*
   2  * Copyright (C) 2011 Mathieu Desnoyers (mathieu.desnoyers@efficios.com)
   3  *
   4  * wrapper around bootid read. Using KALLSYMS to get its address when
   5  * available, else we need to have a kernel that exports this function to GPL
   6  * modules.
   7  *
   8  * Dual LGPL v2.1/GPL v2 license.
   9  */
  10
  11 /* boot_id depends on sysctl */
  12 #if defined(CONFIG_SYSCTL)
  13
  14 #include <linux/fs.h>
  15 #include <linux/file.h>
  16 #include <linux/sched.h>
  17 #include <linux/uaccess.h>
  18 #include "random.h"
  19
  20 /*
  21  * Returns string boot id.
  22  */
  23 int wrapper_get_bootid(char *bootid)
  24 {
  25         struct file *file;
  26         int ret;
  27         ssize_t len;
  28         mm_segment_t old_fs;
  29
  30         file = filp_open("/proc/sys/kernel/random/boot_id", O_RDONLY, 0);
  31         if (IS_ERR(file))
  32                 return PTR_ERR(file);
  33
  34         old_fs = get_fs();
  35         set_fs(KERNEL_DS);
  36
  37         if (!file->f_op || !file->f_op->read) {
  38                 ret = -EINVAL;
  39                 goto end;
  40         }
  41
  42         len = file->f_op->read(file, bootid, BOOT_ID_LEN - 1, &file->f_pos);
  43         if (len != BOOT_ID_LEN - 1) {
  44                 ret = -EINVAL;
  45                 goto end;
  46         }
  47
  48         bootid[BOOT_ID_LEN - 1] = '\0';
  49         ret = 0;
  50 end:
  51         set_fs(old_fs);
  52         filp_close(file, current->files);
  53         return ret;
  54 }
  55
  56 #else
  57
  58 int wrapper_get_bootid(char *bootid)
  59 {
  60         return -ENOSYS;
  61 }
  62
  63 #endif