+++ /dev/null
-/*
- * PRNG: Pseudo Random Number Generator
- * Based on NIST Recommended PRNG From ANSI X9.31 Appendix A.2.4 using
- * AES 128 cipher in RFC3686 ctr mode
- *
- * (C) Neil Horman <nhorman@tuxdriver.com>
- *
- * 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
- * any later version.
- *
- *
- */
-
-#include <linux/err.h>
-#include <linux/init.h>
-#include <linux/module.h>
-#include <linux/mm.h>
-#include <linux/slab.h>
-#include <linux/fs.h>
-#include <linux/scatterlist.h>
-#include <linux/string.h>
-#include <linux/crypto.h>
-#include <linux/highmem.h>
-#include <linux/moduleparam.h>
-#include <linux/jiffies.h>
-#include <linux/timex.h>
-#include <linux/interrupt.h>
-#include <linux/miscdevice.h>
-#include "prng.h"
-
-#define TEST_PRNG_ON_START 0
-
-#define DEFAULT_PRNG_KEY "0123456789abcdef1011"
-#define DEFAULT_PRNG_KSZ 20
-#define DEFAULT_PRNG_IV "defaultv"
-#define DEFAULT_PRNG_IVSZ 8
-#define DEFAULT_BLK_SZ 16
-#define DEFAULT_V_SEED "zaybxcwdveuftgsh"
-
-/*
- * Flags for the prng_context flags field
- */
-
-#define PRNG_FIXED_SIZE 0x1
-#define PRNG_NEED_RESET 0x2
-
-/*
- * Note: DT is our counter value
- * I is our intermediate value
- * V is our seed vector
- * See http://csrc.nist.gov/groups/STM/cavp/documents/rng/931rngext.pdf
- * for implementation details
- */
-
-
-struct prng_context {
- char *prng_key;
- char *prng_iv;
- spinlock_t prng_lock;
- unsigned char rand_data[DEFAULT_BLK_SZ];
- unsigned char last_rand_data[DEFAULT_BLK_SZ];
- unsigned char DT[DEFAULT_BLK_SZ];
- unsigned char I[DEFAULT_BLK_SZ];
- unsigned char V[DEFAULT_BLK_SZ];
- u32 rand_data_valid;
- struct crypto_blkcipher *tfm;
- u32 flags;
-};
-
-static int dbg;
-
-static void hexdump(char *note, unsigned char *buf, unsigned int len)
-{
- if (dbg) {
- printk(KERN_CRIT "%s", note);
- print_hex_dump(KERN_CONT, "", DUMP_PREFIX_OFFSET,
- 16, 1,
- buf, len, false);
- }
-}
-
-#define dbgprint(format, args...) do {if(dbg) printk(format, ##args);} while(0)
-
-static void xor_vectors(unsigned char *in1, unsigned char *in2,
- unsigned char *out, unsigned int size)
-{
- int i;
-
- for (i=0;i<size;i++)
- out[i] = in1[i] ^ in2[i];
-
-}
-/*
- * Returns DEFAULT_BLK_SZ bytes of random data per call
- * returns 0 if generation succeded, <0 if something went wrong
- */
-static int _get_more_prng_bytes(struct prng_context *ctx)
-{
- int i;
- struct blkcipher_desc desc;
- struct scatterlist sg_in, sg_out;
- int ret;
- unsigned char tmp[DEFAULT_BLK_SZ];
-
- desc.tfm = ctx->tfm;
- desc.flags = 0;
-
-
- dbgprint(KERN_CRIT "Calling _get_more_prng_bytes for context %p\n",ctx);
-
- hexdump("Input DT: ", ctx->DT, DEFAULT_BLK_SZ);
- hexdump("Input I: ", ctx->I, DEFAULT_BLK_SZ);
- hexdump("Input V: ", ctx->V, DEFAULT_BLK_SZ);
-
- /*
- * This algorithm is a 3 stage state machine
- */
- for (i=0;i<3;i++) {
-
- desc.tfm = ctx->tfm;
- desc.flags = 0;
- switch (i) {
- case 0:
- /*
- * Start by encrypting the counter value
- * This gives us an intermediate value I
- */
- memcpy(tmp, ctx->DT, DEFAULT_BLK_SZ);
- sg_init_one(&sg_out, &ctx->I[0], DEFAULT_BLK_SZ);
- hexdump("tmp stage 0: ", tmp, DEFAULT_BLK_SZ);
- break;
- case 1:
-
- /*
- * Next xor I with our secret vector V
- * encrypt that result to obtain our
- * pseudo random data which we output
- */
- xor_vectors(ctx->I, ctx->V, tmp, DEFAULT_BLK_SZ);
- sg_init_one(&sg_out, &ctx->rand_data[0], DEFAULT_BLK_SZ);
- hexdump("tmp stage 1: ", tmp, DEFAULT_BLK_SZ);
- break;
- case 2:
- /*
- * First check that we didn't produce the same random data
- * that we did last time around through this
- */
- if (!memcmp(ctx->rand_data, ctx->last_rand_data, DEFAULT_BLK_SZ)) {
- printk(KERN_ERR "ctx %p Failed repetition check!\n",
- ctx);
- ctx->flags |= PRNG_NEED_RESET;
- return -1;
- }
- memcpy(ctx->last_rand_data, ctx->rand_data, DEFAULT_BLK_SZ);
-
- /*
- * Lastly xor the random data with I
- * and encrypt that to obtain a new secret vector V
- */
- xor_vectors(ctx->rand_data, ctx->I, tmp, DEFAULT_BLK_SZ);
- sg_init_one(&sg_out, &ctx->V[0], DEFAULT_BLK_SZ);
- hexdump("tmp stage 2: ", tmp, DEFAULT_BLK_SZ);
- break;
- }
-
- /* Initialize our input buffer */
- sg_init_one(&sg_in, &tmp[0], DEFAULT_BLK_SZ);
-
- /* do the encryption */
- ret = crypto_blkcipher_encrypt(&desc, &sg_out, &sg_in, DEFAULT_BLK_SZ);
-
- /* And check the result */
- if (ret) {
- dbgprint(KERN_CRIT "Encryption of new block failed for context %p\n",ctx);
- ctx->rand_data_valid = DEFAULT_BLK_SZ;
- return -1;
- }
-
- }
-
- /*
- * Now update our DT value
- */
- for (i=DEFAULT_BLK_SZ-1;i>0;i--) {
- ctx->DT[i] = ctx->DT[i-1];
- }
- ctx->DT[0] += 1;
-
- dbgprint("Returning new block for context %p\n",ctx);
- ctx->rand_data_valid = 0;
-
- hexdump("Output DT: ", ctx->DT, DEFAULT_BLK_SZ);
- hexdump("Output I: ", ctx->I, DEFAULT_BLK_SZ);
- hexdump("Output V: ", ctx->V, DEFAULT_BLK_SZ);
- hexdump("New Random Data: ", ctx->rand_data, DEFAULT_BLK_SZ);
-
- return 0;
-}
-
-/* Our exported functions */
-int get_prng_bytes(char *buf, int nbytes, struct prng_context *ctx)
-{
- unsigned long flags;
- unsigned char *ptr = buf;
- unsigned int byte_count = (unsigned int)nbytes;
- int err;
-
-
- if (nbytes < 0)
- return -EINVAL;
-
- spin_lock_irqsave(&ctx->prng_lock, flags);
-
- err = -EFAULT;
- if (ctx->flags & PRNG_NEED_RESET)
- goto done;
-
- /*
- * If the FIXED_SIZE flag is on, only return whole blocks of
- * pseudo random data
- */
- err = -EINVAL;
- if (ctx->flags & PRNG_FIXED_SIZE) {
- if (nbytes < DEFAULT_BLK_SZ)
- goto done;
- byte_count = DEFAULT_BLK_SZ;
- }
-
- err = byte_count;
-
- dbgprint(KERN_CRIT "getting %d random bytes for context %p\n",byte_count, ctx);
-
-
-remainder:
- if (ctx->rand_data_valid == DEFAULT_BLK_SZ) {
- if (_get_more_prng_bytes(ctx) < 0) {
- memset(buf, 0, nbytes);
- err = -EFAULT;
- goto done;
- }
- }
-
- /*
- * Copy up to the next whole block size
- */
- if (byte_count < DEFAULT_BLK_SZ) {
- for (;ctx->rand_data_valid < DEFAULT_BLK_SZ; ctx->rand_data_valid++) {
- *ptr = ctx->rand_data[ctx->rand_data_valid];
- ptr++;
- byte_count--;
- if (byte_count == 0)
- goto done;
- }
- }
-
- /*
- * Now copy whole blocks
- */
- for(;byte_count >= DEFAULT_BLK_SZ; byte_count -= DEFAULT_BLK_SZ) {
- if (_get_more_prng_bytes(ctx) < 0) {
- memset(buf, 0, nbytes);
- err = -1;
- goto done;
- }
- memcpy(ptr, ctx->rand_data, DEFAULT_BLK_SZ);
- ctx->rand_data_valid += DEFAULT_BLK_SZ;
- ptr += DEFAULT_BLK_SZ;
- }
-
- /*
- * Now copy any extra partial data
- */
- if (byte_count)
- goto remainder;
-
-done:
- spin_unlock_irqrestore(&ctx->prng_lock, flags);
- dbgprint(KERN_CRIT "returning %d from get_prng_bytes in context %p\n",err, ctx);
- return err;
-}
-EXPORT_SYMBOL_GPL(get_prng_bytes);
-
-struct prng_context *alloc_prng_context(void)
-{
- struct prng_context *ctx=kzalloc(sizeof(struct prng_context), GFP_KERNEL);
-
- spin_lock_init(&ctx->prng_lock);
-
- if (reset_prng_context(ctx, NULL, NULL, NULL, NULL)) {
- kfree(ctx);
- ctx = NULL;
- }
-
- dbgprint(KERN_CRIT "returning context %p\n",ctx);
- return ctx;
-}
-
-EXPORT_SYMBOL_GPL(alloc_prng_context);
-
-void free_prng_context(struct prng_context *ctx)
-{
- crypto_free_blkcipher(ctx->tfm);
- kfree(ctx);
-}
-EXPORT_SYMBOL_GPL(free_prng_context);
-
-int reset_prng_context(struct prng_context *ctx,
- unsigned char *key, unsigned char *iv,
- unsigned char *V, unsigned char *DT)
-{
- int ret;
- int iv_len;
- int rc = -EFAULT;
-
- spin_lock(&ctx->prng_lock);
- ctx->flags |= PRNG_NEED_RESET;
-
- if (key)
- memcpy(ctx->prng_key,key,strlen(ctx->prng_key));
- else
- ctx->prng_key = DEFAULT_PRNG_KEY;
-
- if (iv)
- memcpy(ctx->prng_iv,iv, strlen(ctx->prng_iv));
- else
- ctx->prng_iv = DEFAULT_PRNG_IV;
-
- if (V)
- memcpy(ctx->V,V,DEFAULT_BLK_SZ);
- else
- memcpy(ctx->V,DEFAULT_V_SEED,DEFAULT_BLK_SZ);
-
- if (DT)
- memcpy(ctx->DT, DT, DEFAULT_BLK_SZ);
- else
- memset(ctx->DT, 0, DEFAULT_BLK_SZ);
-
- memset(ctx->rand_data,0,DEFAULT_BLK_SZ);
- memset(ctx->last_rand_data,0,DEFAULT_BLK_SZ);
-
- if (ctx->tfm)
- crypto_free_blkcipher(ctx->tfm);
-
- ctx->tfm = crypto_alloc_blkcipher("rfc3686(ctr(aes))",0,0);
- if (!ctx->tfm) {
- dbgprint(KERN_CRIT "Failed to alloc crypto tfm for context %p\n",ctx->tfm);
- goto out;
- }
-
- ctx->rand_data_valid = DEFAULT_BLK_SZ;
-
- ret = crypto_blkcipher_setkey(ctx->tfm, ctx->prng_key, strlen(ctx->prng_key));
- if (ret) {
- dbgprint(KERN_CRIT "PRNG: setkey() failed flags=%x\n",
- crypto_blkcipher_get_flags(ctx->tfm));
- crypto_free_blkcipher(ctx->tfm);
- goto out;
- }
-
- iv_len = crypto_blkcipher_ivsize(ctx->tfm);
- if (iv_len) {
- crypto_blkcipher_set_iv(ctx->tfm, ctx->prng_iv, iv_len);
- }
- rc = 0;
- ctx->flags &= ~PRNG_NEED_RESET;
-out:
- spin_unlock(&ctx->prng_lock);
-
- return rc;
-
-}
-EXPORT_SYMBOL_GPL(reset_prng_context);
-
-/* Module initalization */
-static int __init prng_mod_init(void)
-{
-
-#ifdef TEST_PRNG_ON_START
- int i;
- unsigned char tmpbuf[DEFAULT_BLK_SZ];
-
- struct prng_context *ctx = alloc_prng_context();
- if (ctx == NULL)
- return -EFAULT;
- for (i=0;i<16;i++) {
- if (get_prng_bytes(tmpbuf, DEFAULT_BLK_SZ, ctx) < 0) {
- free_prng_context(ctx);
- return -EFAULT;
- }
- }
- free_prng_context(ctx);
-#endif
-
- return 0;
-}
-
-static void __exit prng_mod_fini(void)
-{
- return;
-}
-
-MODULE_LICENSE("GPL");
-MODULE_DESCRIPTION("Software Pseudo Random Number Generator");
-MODULE_AUTHOR("Neil Horman <nhorman@tuxdriver.com>");
-module_param(dbg, int, 0);
-MODULE_PARM_DESC(dbg, "Boolean to enable debugging (0/1 == off/on)");
-module_init(prng_mod_init);
-module_exit(prng_mod_fini);
git.openpandora.org / pandora-kernel.git / commitdiff