Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
tjh.dev
kernel
os
linux
1/* Copyright (C) 2005 Jeff Dike <jdike@addtoit.com> */
2/* Much of this ripped from drivers/char/hw_random.c, see there for other
3 * copyright.
4 *
5 * This software may be used and distributed according to the terms
6 * of the GNU General Public License, incorporated herein by reference.
7 */
8#include <linux/sched.h>
9#include <linux/module.h>
10#include <linux/fs.h>
11#include <linux/miscdevice.h>
12#include <linux/delay.h>
13#include <asm/uaccess.h>
14#include "os.h"
15
16/*
17 * core module and version information
18 */
19#define RNG_VERSION "1.0.0"
20#define RNG_MODULE_NAME "random"
21
22#define RNG_MISCDEV_MINOR 183 /* official */
23
24/* Changed at init time, in the non-modular case, and at module load
25 * time, in the module case. Presumably, the module subsystem
26 * protects against a module being loaded twice at the same time.
27 */
28static int random_fd = -1;
29
30static int rng_dev_open (struct inode *inode, struct file *filp)
31{
32 /* enforce read-only access to this chrdev */
33 if ((filp->f_mode & FMODE_READ) == 0)
34 return -EINVAL;
35 if (filp->f_mode & FMODE_WRITE)
36 return -EINVAL;
37
38 return 0;
39}
40
41static ssize_t rng_dev_read (struct file *filp, char __user *buf, size_t size,
42 loff_t * offp)
43{
44 u32 data;
45 int n, ret = 0, have_data;
46
47 while(size){
48 n = os_read_file(random_fd, &data, sizeof(data));
49 if(n > 0){
50 have_data = n;
51 while (have_data && size) {
52 if (put_user((u8)data, buf++)) {
53 ret = ret ? : -EFAULT;
54 break;
55 }
56 size--;
57 ret++;
58 have_data--;
59 data>>=8;
60 }
61 }
62 else if(n == -EAGAIN){
63 if (filp->f_flags & O_NONBLOCK)
64 return ret ? : -EAGAIN;
65
66 if(need_resched())
67 schedule_timeout_interruptible(1);
68 }
69 else return n;
70 if (signal_pending (current))
71 return ret ? : -ERESTARTSYS;
72 }
73 return ret;
74}
75
76static const struct file_operations rng_chrdev_ops = {
77 .owner = THIS_MODULE,
78 .open = rng_dev_open,
79 .read = rng_dev_read,
80};
81
82/* rng_init shouldn't be called more than once at boot time */
83static struct miscdevice rng_miscdev = {
84 RNG_MISCDEV_MINOR,
85 RNG_MODULE_NAME,
86 &rng_chrdev_ops,
87};
88
89/*
90 * rng_init - initialize RNG module
91 */
92static int __init rng_init (void)
93{
94 int err;
95
96 err = os_open_file("/dev/random", of_read(OPENFLAGS()), 0);
97 if(err < 0)
98 goto out;
99
100 random_fd = err;
101
102 err = os_set_fd_block(random_fd, 0);
103 if(err)
104 goto err_out_cleanup_hw;
105
106 err = misc_register (&rng_miscdev);
107 if (err) {
108 printk (KERN_ERR RNG_MODULE_NAME ": misc device register failed\n");
109 goto err_out_cleanup_hw;
110 }
111
112 out:
113 return err;
114
115 err_out_cleanup_hw:
116 random_fd = -1;
117 goto out;
118}
119
120/*
121 * rng_cleanup - shutdown RNG module
122 */
123static void __exit rng_cleanup (void)
124{
125 misc_deregister (&rng_miscdev);
126}
127
128module_init (rng_init);
129module_exit (rng_cleanup);
130
131MODULE_DESCRIPTION("UML Host Random Number Generator (RNG) driver");
132MODULE_LICENSE("GPL");