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