char: frandom: initial commit v1.1

    Based on my dd test:
      hw_random (msm_rng): 0.56 MB/s
      linux random/urandom: 4.4 MB/s
      frandom/erandom: 90 MB/s

2 files changed, 416 insertions, 1 deletions

diff --git a/drivers/char/Makefile b/drivers/char/Makefile
index e0047ed1e..85b2dfa6e 100644
--- a/drivers/char/Makefile
+++ b/drivers/char/Makefile
@@ -2,7 +2,7 @@
 # Makefile for the kernel character device drivers.
 #
 
-obj-y				+= mem.o random.o
+obj-y				+= mem.o random.o frandom.o
 obj-$(CONFIG_TTY_PRINTK)	+= ttyprintk.o
 obj-y				+= misc.o
 obj-$(CONFIG_ATARI_DSP56K)	+= dsp56k.o
diff --git a/drivers/char/frandom.c b/drivers/char/frandom.c
new file mode 100644
index 000000000..54b98c53e
--- /dev/null
+++ b/drivers/char/frandom.c
@@ -0,0 +1,415 @@
+/*
+** frandom.c
+**      Fast pseudo-random generator 
+**
+**      (c) Copyright 2003-2011 Eli Billauer
+**      http://www.billauer.co.il
+**
+** This program is free software; you can redistribute it and/or modify
+** it under the terms of the GNU General Public License as published by
+** the Free Software Foundation; either version 2 of the License, or
+** (at your option) any later version.
+**
+**
+*/
+
+#include <linux/version.h>
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/slab.h> 
+#include <linux/fs.h> 
+#include <linux/errno.h>
+#include <linux/types.h> 
+#include <linux/random.h>
+
+#include <asm/uaccess.h>
+#include <linux/cdev.h>
+#include <linux/err.h>
+#include <linux/device.h>
+
+#define INTERNAL_SEED 0
+#define EXTERNAL_SEED 1
+
+#define FRANDOM_MAJOR 235
+#define FRANDOM_MINOR 11 
+#define ERANDOM_MINOR 12 
+
+static struct file_operations frandom_fops; /* Values assigned below */
+
+static int erandom_seeded = 0; /* Internal flag */
+
+static int frandom_major = FRANDOM_MAJOR;
+static int frandom_minor = FRANDOM_MINOR;
+static int erandom_minor = ERANDOM_MINOR;
+static int frandom_bufsize = 256;
+static int frandom_chunklimit = 0; /* =0 means unlimited */
+
+static struct cdev frandom_cdev;
+static struct cdev erandom_cdev;
+static struct class *frandom_class;
+struct device *frandom_device;
+struct device *erandom_device;
+
+MODULE_DESCRIPTION("Fast pseudo-random number generator");
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Eli Billauer");
+module_param(frandom_major, int, 0);
+module_param(frandom_minor, int, 0);
+module_param(erandom_minor, int, 0);
+module_param(frandom_bufsize, int, 0);
+module_param(frandom_chunklimit, int, 0);
+
+MODULE_PARM_DESC(frandom_major,"Major number of /dev/frandom and /dev/erandom");
+MODULE_PARM_DESC(frandom_minor,"Minor number of /dev/frandom");
+MODULE_PARM_DESC(erandom_minor,"Minor number of /dev/erandom");
+MODULE_PARM_DESC(frandom_bufsize,"Internal buffer size in bytes. Default is 256. Must be >= 256");
+MODULE_PARM_DESC(frandom_chunklimit,"Limit for read() blocks size. 0 (default) is unlimited, otherwise must be >= 256");
+
+struct frandom_state
+{
+	struct semaphore sem; /* Semaphore on the state structure */
+
+	u8 S[256]; /* The state array */
+	u8 i;        
+	u8 j;
+
+	char *buf;
+};
+
+static struct frandom_state *erandom_state;
+
+static inline void swap_byte(u8 *a, u8 *b)
+{
+	u8 swapByte; 
+  
+	swapByte = *a; 
+	*a = *b;      
+	*b = swapByte;
+}
+
+static void init_rand_state(struct frandom_state *state, int seedflag);
+
+void erandom_get_random_bytes(char *buf, size_t count)
+{
+	struct frandom_state *state = erandom_state;
+	int k;
+
+	unsigned int i;
+	unsigned int j;
+	u8 *S;
+  
+	/* If we fail to get the semaphore, we revert to external random data.
+	   Since semaphore blocking is expected to be very rare, and interrupts
+	   during these rare and very short periods of time even less frequent,
+	   we take the better-safe-than-sorry approach, and fill the buffer
+	   some expensive random data, in case the caller wasn't aware of this
+	   possibility, and expects random data anyhow.
+	*/
+
+	if (down_interruptible(&state->sem)) {
+		get_random_bytes(buf, count);
+		return;
+	}
+
+	/* We seed erandom as late as possible, hoping that the kernel's main
+	   RNG is already restored in the boot sequence (not critical, but
+	   better.
+	*/
+	
+	if (!erandom_seeded) {
+		erandom_seeded = 1;
+		init_rand_state(state, EXTERNAL_SEED);
+		printk(KERN_INFO "frandom: Seeded global generator now (used by erandom)\n");
+	}
+
+	i = state->i;     
+	j = state->j;
+	S = state->S;  
+
+	for (k=0; k<count; k++) {
+		i = (i + 1) & 0xff;
+		j = (j + S[i]) & 0xff;
+		swap_byte(&S[i], &S[j]);
+		*buf++ = S[(S[i] + S[j]) & 0xff];
+	}
+ 
+	state->i = i;     
+	state->j = j;
+
+	up(&state->sem);
+}
+
+static void init_rand_state(struct frandom_state *state, int seedflag)
+{
+	unsigned int i, j, k;
+	u8 *S;
+	u8 *seed = state->buf;
+
+	if (seedflag == INTERNAL_SEED)
+		erandom_get_random_bytes(seed, 256);
+	else
+		get_random_bytes(seed, 256);
+
+	S = state->S;
+	for (i=0; i<256; i++)
+		*S++=i;
+
+	j=0;
+	S = state->S;
+
+	for (i=0; i<256; i++) {
+		j = (j + S[i] + *seed++) & 0xff;
+		swap_byte(&S[i], &S[j]);
+	}
+
+	/* It's considered good practice to discard the first 256 bytes
+	   generated. So we do it:
+	*/
+
+	i=0; j=0;
+	for (k=0; k<256; k++) {
+		i = (i + 1) & 0xff;
+		j = (j + S[i]) & 0xff;
+		swap_byte(&S[i], &S[j]);
+	}
+
+	state->i = i; /* Save state */
+	state->j = j;
+}
+
+static int frandom_open(struct inode *inode, struct file *filp)
+{
+  
+	struct frandom_state *state;
+
+	int num = iminor(inode);
+
+	/* This should never happen, now when the minors are regsitered
+	 * explicitly
+	 */
+	if ((num != frandom_minor) && (num != erandom_minor)) return -ENODEV;
+  
+	state = kmalloc(sizeof(struct frandom_state), GFP_KERNEL);
+	if (!state)
+		return -ENOMEM;
+
+	state->buf = kmalloc(frandom_bufsize, GFP_KERNEL);
+	if (!state->buf) {
+		kfree(state);
+		return -ENOMEM;
+	}
+
+	sema_init(&state->sem, 1); /* Init semaphore as a mutex */
+
+	if (num == frandom_minor)
+		init_rand_state(state, EXTERNAL_SEED);
+	else
+		init_rand_state(state, INTERNAL_SEED);
+
+	filp->private_data = state;
+
+	return 0; /* Success */
+}
+
+static int frandom_release(struct inode *inode, struct file *filp)
+{
+
+	struct frandom_state *state = filp->private_data;
+
+	kfree(state->buf);
+	kfree(state);
+  
+	return 0;
+}
+
+static ssize_t frandom_read(struct file *filp, char *buf, size_t count,
+			    loff_t *f_pos)
+{
+	struct frandom_state *state = filp->private_data;
+	ssize_t ret;
+	int dobytes, k;
+	char *localbuf;
+
+	unsigned int i;
+	unsigned int j;
+	u8 *S;
+  
+	if (down_interruptible(&state->sem))
+		return -ERESTARTSYS;
+  
+	if ((frandom_chunklimit > 0) && (count > frandom_chunklimit))
+		count = frandom_chunklimit;
+
+	ret = count; /* It's either everything or an error... */
+  
+	i = state->i;     
+	j = state->j;
+	S = state->S;  
+
+	while (count) {
+		if (count > frandom_bufsize)
+			dobytes = frandom_bufsize;
+		else
+			dobytes = count;
+
+		localbuf = state->buf;
+
+		for (k=0; k<dobytes; k++) {
+			i = (i + 1) & 0xff;
+			j = (j + S[i]) & 0xff;
+			swap_byte(&S[i], &S[j]);
+			*localbuf++ = S[(S[i] + S[j]) & 0xff];
+		}
+ 
+		if (copy_to_user(buf, state->buf, dobytes)) {
+			ret = -EFAULT;
+			goto out;
+		}
+
+		buf += dobytes;
+		count -= dobytes;
+	}
+
+ out:
+	state->i = i;     
+	state->j = j;
+
+	up(&state->sem);
+	return ret;
+}
+
+static struct file_operations frandom_fops = {
+	read:       frandom_read,
+	open:       frandom_open,
+	release:    frandom_release,
+};
+
+static void frandom_cleanup_module(void) {
+	unregister_chrdev_region(MKDEV(frandom_major, erandom_minor), 1);
+	cdev_del(&erandom_cdev);
+	device_destroy(frandom_class, MKDEV(frandom_major, erandom_minor));
+
+	unregister_chrdev_region(MKDEV(frandom_major, frandom_minor), 1);
+	cdev_del(&frandom_cdev);
+	device_destroy(frandom_class, MKDEV(frandom_major, frandom_minor));
+	class_destroy(frandom_class);
+
+	kfree(erandom_state->buf);
+	kfree(erandom_state);
+}
+
+
+static int frandom_init_module(void)
+{
+	int result;
+
+	/* The buffer size MUST be at least 256 bytes, because we assume that
+	   minimal length in init_rand_state().
+	*/       
+	if (frandom_bufsize < 256) {
+		printk(KERN_ERR "frandom: Refused to load because frandom_bufsize=%d < 256\n",frandom_bufsize);
+		return -EINVAL;
+	}
+	if ((frandom_chunklimit != 0) && (frandom_chunklimit < 256)) {
+		printk(KERN_ERR "frandom: Refused to load because frandom_chunklimit=%d < 256 and != 0\n",frandom_chunklimit);
+		return -EINVAL;
+	}
+
+	erandom_state = kmalloc(sizeof(struct frandom_state), GFP_KERNEL);
+	if (!erandom_state)
+		return -ENOMEM;
+
+	/* This specific buffer is only used for seeding, so we need
+	   256 bytes exactly */
+	erandom_state->buf = kmalloc(256, GFP_KERNEL);
+	if (!erandom_state->buf) {
+		kfree(erandom_state);
+		return -ENOMEM;
+	}
+
+	sema_init(&erandom_state->sem, 1); /* Init semaphore as a mutex */
+
+	erandom_seeded = 0;
+
+	frandom_class = class_create(THIS_MODULE, "fastrng");
+	if (IS_ERR(frandom_class)) {
+		result = PTR_ERR(frandom_class);
+		printk(KERN_WARNING "frandom: Failed to register class fastrng\n");
+		goto error0;
+	}
+	
+	/*
+	 * Register your major, and accept a dynamic number. This is the
+	 * first thing to do, in order to avoid releasing other module's
+	 * fops in frandom_cleanup_module()
+	 */
+
+	cdev_init(&frandom_cdev, &frandom_fops);
+	frandom_cdev.owner = THIS_MODULE;
+	result = cdev_add(&frandom_cdev, MKDEV(frandom_major, frandom_minor), 1);
+	if (result) {
+	  printk(KERN_WARNING "frandom: Failed to add cdev for /dev/frandom\n");
+	  goto error1;
+	}
+
+	result = register_chrdev_region(MKDEV(frandom_major, frandom_minor), 1, "/dev/frandom");
+	if (result < 0) {
+		printk(KERN_WARNING "frandom: can't get major/minor %d/%d\n", frandom_major, frandom_minor);
+	  goto error2;
+	}
+
+	frandom_device = device_create(frandom_class, NULL, MKDEV(frandom_major, frandom_minor), NULL, "frandom");
+
+	if (IS_ERR(frandom_device)) {
+		printk(KERN_WARNING "frandom: Failed to create frandom device\n");
+		goto error3;
+	}
+
+	cdev_init(&erandom_cdev, &frandom_fops);
+	erandom_cdev.owner = THIS_MODULE;
+	result = cdev_add(&erandom_cdev, MKDEV(frandom_major, erandom_minor), 1);
+	if (result) {
+	  printk(KERN_WARNING "frandom: Failed to add cdev for /dev/erandom\n");
+	  goto error4;
+	}
+
+	result = register_chrdev_region(MKDEV(frandom_major, erandom_minor), 1, "/dev/erandom");
+	if (result < 0) {
+		printk(KERN_WARNING "frandom: can't get major/minor %d/%d\n", frandom_major, erandom_minor);
+		goto error5;
+	}
+
+	erandom_device = device_create(frandom_class, NULL, MKDEV(frandom_major, erandom_minor), NULL, "erandom");
+
+	if (IS_ERR(erandom_device)) {
+		printk(KERN_WARNING "frandom: Failed to create erandom device\n");
+		goto error6;
+	}
+	return 0; /* succeed */
+
+ error6:
+	unregister_chrdev_region(MKDEV(frandom_major, erandom_minor), 1);
+ error5:
+	cdev_del(&erandom_cdev);
+ error4:
+	device_destroy(frandom_class, MKDEV(frandom_major, frandom_minor));
+ error3:
+	unregister_chrdev_region(MKDEV(frandom_major, frandom_minor), 1);
+ error2:
+	cdev_del(&frandom_cdev);
+ error1:
+	class_destroy(frandom_class);
+ error0:
+	kfree(erandom_state->buf);
+	kfree(erandom_state);
+
+	return result;	
+}
+
+module_init(frandom_init_module);
+module_exit(frandom_cleanup_module);
+
+EXPORT_SYMBOL(erandom_get_random_bytes);