wrapper/random.c

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