wrapper/random.c

   1 /* SPDX-License-Identifier: (GPL-2.0-only or LGPL-2.1-only)
   2  *
   3  * wrapper/random.c
   4  *
   5  * wrapper around bootid read. Read the boot id through the /proc filesystem.
   6  *
   7  * Copyright (C) 2011-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   8  */
   9
  10 #include <linux/errno.h>
  11
  12 /* boot_id depends on sysctl */
  13 #if defined(CONFIG_SYSCTL)
  14
  15 #include <linux/fs.h>
  16 #include <linux/file.h>
  17 #include <linux/sched.h>
  18 #include <linux/uaccess.h>
  19 #include <wrapper/random.h>
  20
  21 /*
  22  * Returns string boot id.
  23  */
  24 int wrapper_get_bootid(char *bootid)
  25 {
  26         struct file *file;
  27         int ret;
  28         ssize_t len;
  29         mm_segment_t old_fs;
  30
  31         file = filp_open("/proc/sys/kernel/random/boot_id", O_RDONLY, 0);
  32         if (IS_ERR(file))
  33                 return PTR_ERR(file);
  34
  35         old_fs = get_fs();
  36         set_fs(KERNEL_DS);
  37
  38         if (!file->f_op || !file->f_op->read) {
  39                 ret = -EINVAL;
  40                 goto end;
  41         }
  42
  43         len = file->f_op->read(file, bootid, BOOT_ID_LEN - 1, &file->f_pos);
  44         if (len != BOOT_ID_LEN - 1) {
  45                 ret = -EINVAL;
  46                 goto end;
  47         }
  48
  49         bootid[BOOT_ID_LEN - 1] = '\0';
  50         ret = 0;
  51 end:
  52         set_fs(old_fs);
  53         filp_close(file, current->files);
  54         return ret;
  55 }
  56 EXPORT_SYMBOL_GPL(wrapper_get_bootid);
  57
  58 #else
  59
  60 int wrapper_get_bootid(char *bootid)
  61 {
  62         return -ENOSYS;
  63 }
  64 EXPORT_SYMBOL_GPL(wrapper_get_bootid);
  65
  66 #endif