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@@ -1,410 +0,0 @@
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-/*
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- * PRNG: Pseudo Random Number Generator
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- * Based on NIST Recommended PRNG From ANSI X9.31 Appendix A.2.4 using
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- * AES 128 cipher in RFC3686 ctr mode
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- *
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- * (C) Neil Horman <nhorman@tuxdriver.com>
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- *
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- * This program is free software; you can redistribute it and/or modify it
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- * under the terms of the GNU General Public License as published by the
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- * Free Software Foundation; either version 2 of the License, or (at your
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- * any later version.
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- *
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- *
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- */
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-
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-#include <linux/err.h>
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-#include <linux/init.h>
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-#include <linux/module.h>
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-#include <linux/mm.h>
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-#include <linux/slab.h>
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-#include <linux/fs.h>
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-#include <linux/scatterlist.h>
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-#include <linux/string.h>
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-#include <linux/crypto.h>
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-#include <linux/highmem.h>
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-#include <linux/moduleparam.h>
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-#include <linux/jiffies.h>
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-#include <linux/timex.h>
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-#include <linux/interrupt.h>
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-#include <linux/miscdevice.h>
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-#include "prng.h"
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-
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-#define TEST_PRNG_ON_START 0
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-
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-#define DEFAULT_PRNG_KEY "0123456789abcdef1011"
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-#define DEFAULT_PRNG_KSZ 20
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-#define DEFAULT_PRNG_IV "defaultv"
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-#define DEFAULT_PRNG_IVSZ 8
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-#define DEFAULT_BLK_SZ 16
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-#define DEFAULT_V_SEED "zaybxcwdveuftgsh"
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-
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-/*
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- * Flags for the prng_context flags field
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- */
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-
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-#define PRNG_FIXED_SIZE 0x1
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-#define PRNG_NEED_RESET 0x2
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-
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-/*
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- * Note: DT is our counter value
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- * I is our intermediate value
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- * V is our seed vector
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- * See http://csrc.nist.gov/groups/STM/cavp/documents/rng/931rngext.pdf
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- * for implementation details
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- */
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-
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-
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-struct prng_context {
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- char *prng_key;
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- char *prng_iv;
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- spinlock_t prng_lock;
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- unsigned char rand_data[DEFAULT_BLK_SZ];
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- unsigned char last_rand_data[DEFAULT_BLK_SZ];
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- unsigned char DT[DEFAULT_BLK_SZ];
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- unsigned char I[DEFAULT_BLK_SZ];
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- unsigned char V[DEFAULT_BLK_SZ];
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- u32 rand_data_valid;
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- struct crypto_blkcipher *tfm;
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- u32 flags;
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-};
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-
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-static int dbg;
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-
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-static void hexdump(char *note, unsigned char *buf, unsigned int len)
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-{
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- if (dbg) {
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- printk(KERN_CRIT "%s", note);
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- print_hex_dump(KERN_CONT, "", DUMP_PREFIX_OFFSET,
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- 16, 1,
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- buf, len, false);
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- }
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-}
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-
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-#define dbgprint(format, args...) do {if(dbg) printk(format, ##args);} while(0)
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-
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-static void xor_vectors(unsigned char *in1, unsigned char *in2,
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- unsigned char *out, unsigned int size)
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-{
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- int i;
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-
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- for (i=0;i<size;i++)
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- out[i] = in1[i] ^ in2[i];
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-
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-}
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-/*
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- * Returns DEFAULT_BLK_SZ bytes of random data per call
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- * returns 0 if generation succeded, <0 if something went wrong
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- */
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-static int _get_more_prng_bytes(struct prng_context *ctx)
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-{
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- int i;
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- struct blkcipher_desc desc;
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- struct scatterlist sg_in, sg_out;
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- int ret;
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- unsigned char tmp[DEFAULT_BLK_SZ];
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-
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- desc.tfm = ctx->tfm;
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- desc.flags = 0;
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-
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-
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- dbgprint(KERN_CRIT "Calling _get_more_prng_bytes for context %p\n",ctx);
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-
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- hexdump("Input DT: ", ctx->DT, DEFAULT_BLK_SZ);
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- hexdump("Input I: ", ctx->I, DEFAULT_BLK_SZ);
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- hexdump("Input V: ", ctx->V, DEFAULT_BLK_SZ);
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-
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- /*
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- * This algorithm is a 3 stage state machine
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- */
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- for (i=0;i<3;i++) {
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-
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- desc.tfm = ctx->tfm;
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- desc.flags = 0;
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- switch (i) {
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- case 0:
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- /*
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- * Start by encrypting the counter value
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- * This gives us an intermediate value I
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- */
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- memcpy(tmp, ctx->DT, DEFAULT_BLK_SZ);
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- sg_init_one(&sg_out, &ctx->I[0], DEFAULT_BLK_SZ);
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- hexdump("tmp stage 0: ", tmp, DEFAULT_BLK_SZ);
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- break;
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- case 1:
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-
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- /*
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- * Next xor I with our secret vector V
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- * encrypt that result to obtain our
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- * pseudo random data which we output
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- */
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- xor_vectors(ctx->I, ctx->V, tmp, DEFAULT_BLK_SZ);
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- sg_init_one(&sg_out, &ctx->rand_data[0], DEFAULT_BLK_SZ);
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- hexdump("tmp stage 1: ", tmp, DEFAULT_BLK_SZ);
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- break;
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- case 2:
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- /*
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- * First check that we didn't produce the same random data
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- * that we did last time around through this
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- */
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- if (!memcmp(ctx->rand_data, ctx->last_rand_data, DEFAULT_BLK_SZ)) {
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- printk(KERN_ERR "ctx %p Failed repetition check!\n",
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- ctx);
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- ctx->flags |= PRNG_NEED_RESET;
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- return -1;
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- }
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- memcpy(ctx->last_rand_data, ctx->rand_data, DEFAULT_BLK_SZ);
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-
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- /*
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- * Lastly xor the random data with I
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- * and encrypt that to obtain a new secret vector V
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- */
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- xor_vectors(ctx->rand_data, ctx->I, tmp, DEFAULT_BLK_SZ);
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- sg_init_one(&sg_out, &ctx->V[0], DEFAULT_BLK_SZ);
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- hexdump("tmp stage 2: ", tmp, DEFAULT_BLK_SZ);
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- break;
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- }
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-
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- /* Initialize our input buffer */
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- sg_init_one(&sg_in, &tmp[0], DEFAULT_BLK_SZ);
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-
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- /* do the encryption */
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- ret = crypto_blkcipher_encrypt(&desc, &sg_out, &sg_in, DEFAULT_BLK_SZ);
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-
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- /* And check the result */
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- if (ret) {
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- dbgprint(KERN_CRIT "Encryption of new block failed for context %p\n",ctx);
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- ctx->rand_data_valid = DEFAULT_BLK_SZ;
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- return -1;
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- }
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-
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- }
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-
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- /*
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- * Now update our DT value
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- */
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- for (i=DEFAULT_BLK_SZ-1;i>0;i--) {
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- ctx->DT[i] = ctx->DT[i-1];
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- }
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- ctx->DT[0] += 1;
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-
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- dbgprint("Returning new block for context %p\n",ctx);
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- ctx->rand_data_valid = 0;
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-
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- hexdump("Output DT: ", ctx->DT, DEFAULT_BLK_SZ);
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- hexdump("Output I: ", ctx->I, DEFAULT_BLK_SZ);
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- hexdump("Output V: ", ctx->V, DEFAULT_BLK_SZ);
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- hexdump("New Random Data: ", ctx->rand_data, DEFAULT_BLK_SZ);
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-
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- return 0;
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-}
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-
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-/* Our exported functions */
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-int get_prng_bytes(char *buf, int nbytes, struct prng_context *ctx)
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-{
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- unsigned long flags;
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- unsigned char *ptr = buf;
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- unsigned int byte_count = (unsigned int)nbytes;
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- int err;
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-
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-
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- if (nbytes < 0)
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- return -EINVAL;
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-
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- spin_lock_irqsave(&ctx->prng_lock, flags);
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-
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- err = -EFAULT;
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- if (ctx->flags & PRNG_NEED_RESET)
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- goto done;
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-
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- /*
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- * If the FIXED_SIZE flag is on, only return whole blocks of
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- * pseudo random data
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- */
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- err = -EINVAL;
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- if (ctx->flags & PRNG_FIXED_SIZE) {
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- if (nbytes < DEFAULT_BLK_SZ)
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- goto done;
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- byte_count = DEFAULT_BLK_SZ;
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- }
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-
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- err = byte_count;
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-
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- dbgprint(KERN_CRIT "getting %d random bytes for context %p\n",byte_count, ctx);
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-
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-
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-remainder:
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- if (ctx->rand_data_valid == DEFAULT_BLK_SZ) {
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- if (_get_more_prng_bytes(ctx) < 0) {
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- memset(buf, 0, nbytes);
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- err = -EFAULT;
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- goto done;
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- }
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- }
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-
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- /*
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- * Copy up to the next whole block size
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- */
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- if (byte_count < DEFAULT_BLK_SZ) {
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- for (;ctx->rand_data_valid < DEFAULT_BLK_SZ; ctx->rand_data_valid++) {
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- *ptr = ctx->rand_data[ctx->rand_data_valid];
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- ptr++;
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- byte_count--;
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- if (byte_count == 0)
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- goto done;
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- }
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- }
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-
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- /*
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- * Now copy whole blocks
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- */
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- for(;byte_count >= DEFAULT_BLK_SZ; byte_count -= DEFAULT_BLK_SZ) {
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- if (_get_more_prng_bytes(ctx) < 0) {
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- memset(buf, 0, nbytes);
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- err = -1;
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- goto done;
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- }
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- memcpy(ptr, ctx->rand_data, DEFAULT_BLK_SZ);
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- ctx->rand_data_valid += DEFAULT_BLK_SZ;
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- ptr += DEFAULT_BLK_SZ;
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- }
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-
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- /*
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- * Now copy any extra partial data
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- */
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- if (byte_count)
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- goto remainder;
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-
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-done:
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- spin_unlock_irqrestore(&ctx->prng_lock, flags);
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- dbgprint(KERN_CRIT "returning %d from get_prng_bytes in context %p\n",err, ctx);
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- return err;
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-}
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-EXPORT_SYMBOL_GPL(get_prng_bytes);
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-
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-struct prng_context *alloc_prng_context(void)
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-{
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- struct prng_context *ctx=kzalloc(sizeof(struct prng_context), GFP_KERNEL);
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-
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- spin_lock_init(&ctx->prng_lock);
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-
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- if (reset_prng_context(ctx, NULL, NULL, NULL, NULL)) {
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- kfree(ctx);
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- ctx = NULL;
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- }
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-
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- dbgprint(KERN_CRIT "returning context %p\n",ctx);
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- return ctx;
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-}
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-
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-EXPORT_SYMBOL_GPL(alloc_prng_context);
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-
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-void free_prng_context(struct prng_context *ctx)
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-{
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- crypto_free_blkcipher(ctx->tfm);
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- kfree(ctx);
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-}
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-EXPORT_SYMBOL_GPL(free_prng_context);
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-
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-int reset_prng_context(struct prng_context *ctx,
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- unsigned char *key, unsigned char *iv,
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- unsigned char *V, unsigned char *DT)
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-{
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- int ret;
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- int iv_len;
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- int rc = -EFAULT;
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-
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- spin_lock(&ctx->prng_lock);
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- ctx->flags |= PRNG_NEED_RESET;
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-
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- if (key)
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- memcpy(ctx->prng_key,key,strlen(ctx->prng_key));
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- else
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- ctx->prng_key = DEFAULT_PRNG_KEY;
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-
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- if (iv)
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- memcpy(ctx->prng_iv,iv, strlen(ctx->prng_iv));
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- else
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- ctx->prng_iv = DEFAULT_PRNG_IV;
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-
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- if (V)
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- memcpy(ctx->V,V,DEFAULT_BLK_SZ);
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- else
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- memcpy(ctx->V,DEFAULT_V_SEED,DEFAULT_BLK_SZ);
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-
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- if (DT)
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- memcpy(ctx->DT, DT, DEFAULT_BLK_SZ);
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- else
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- memset(ctx->DT, 0, DEFAULT_BLK_SZ);
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-
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- memset(ctx->rand_data,0,DEFAULT_BLK_SZ);
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- memset(ctx->last_rand_data,0,DEFAULT_BLK_SZ);
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-
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- if (ctx->tfm)
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- crypto_free_blkcipher(ctx->tfm);
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-
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- ctx->tfm = crypto_alloc_blkcipher("rfc3686(ctr(aes))",0,0);
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- if (!ctx->tfm) {
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- dbgprint(KERN_CRIT "Failed to alloc crypto tfm for context %p\n",ctx->tfm);
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- goto out;
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- }
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-
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- ctx->rand_data_valid = DEFAULT_BLK_SZ;
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-
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- ret = crypto_blkcipher_setkey(ctx->tfm, ctx->prng_key, strlen(ctx->prng_key));
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- if (ret) {
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- dbgprint(KERN_CRIT "PRNG: setkey() failed flags=%x\n",
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- crypto_blkcipher_get_flags(ctx->tfm));
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- crypto_free_blkcipher(ctx->tfm);
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- goto out;
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- }
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-
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- iv_len = crypto_blkcipher_ivsize(ctx->tfm);
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- if (iv_len) {
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- crypto_blkcipher_set_iv(ctx->tfm, ctx->prng_iv, iv_len);
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- }
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- rc = 0;
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- ctx->flags &= ~PRNG_NEED_RESET;
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-out:
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- spin_unlock(&ctx->prng_lock);
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-
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- return rc;
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-
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-}
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-EXPORT_SYMBOL_GPL(reset_prng_context);
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-
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-/* Module initalization */
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-static int __init prng_mod_init(void)
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-{
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-
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-#ifdef TEST_PRNG_ON_START
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- int i;
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- unsigned char tmpbuf[DEFAULT_BLK_SZ];
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-
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- struct prng_context *ctx = alloc_prng_context();
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- if (ctx == NULL)
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- return -EFAULT;
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- for (i=0;i<16;i++) {
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- if (get_prng_bytes(tmpbuf, DEFAULT_BLK_SZ, ctx) < 0) {
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- free_prng_context(ctx);
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- return -EFAULT;
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- }
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- }
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- free_prng_context(ctx);
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-#endif
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-
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- return 0;
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-}
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-
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-static void __exit prng_mod_fini(void)
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-{
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- return;
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-}
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-
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-MODULE_LICENSE("GPL");
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-MODULE_DESCRIPTION("Software Pseudo Random Number Generator");
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-MODULE_AUTHOR("Neil Horman <nhorman@tuxdriver.com>");
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-module_param(dbg, int, 0);
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-MODULE_PARM_DESC(dbg, "Boolean to enable debugging (0/1 == off/on)");
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-module_init(prng_mod_init);
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-module_exit(prng_mod_fini);
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