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c2176f0098
Otherwise, we might be seeding the RNG using bad randomness, which is dangerous. The one use of this function from within the kernel -- not from userspace -- is being removed (keys/big_key), so that call site isn't relevant in assessing this. Cc: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
235 lines
4.9 KiB
C
235 lines
4.9 KiB
C
/*
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* Cryptographic API.
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*
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* RNG operations.
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*
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* Copyright (c) 2008 Neil Horman <nhorman@tuxdriver.com>
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* Copyright (c) 2015 Herbert Xu <herbert@gondor.apana.org.au>
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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 Free
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* Software Foundation; either version 2 of the License, or (at your option)
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* any later version.
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*
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*/
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#include <linux/atomic.h>
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#include <crypto/internal/rng.h>
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#include <linux/err.h>
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#include <linux/module.h>
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#include <linux/mutex.h>
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#include <linux/random.h>
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#include <linux/seq_file.h>
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#include <linux/slab.h>
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#include <linux/string.h>
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#include <linux/cryptouser.h>
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#include <linux/compiler.h>
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#include <net/netlink.h>
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#include "internal.h"
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static DEFINE_MUTEX(crypto_default_rng_lock);
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struct crypto_rng *crypto_default_rng;
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EXPORT_SYMBOL_GPL(crypto_default_rng);
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static int crypto_default_rng_refcnt;
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int crypto_rng_reset(struct crypto_rng *tfm, const u8 *seed, unsigned int slen)
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{
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u8 *buf = NULL;
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int err;
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if (!seed && slen) {
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buf = kmalloc(slen, GFP_KERNEL);
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if (!buf)
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return -ENOMEM;
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err = get_random_bytes_wait(buf, slen);
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if (err)
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goto out;
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seed = buf;
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}
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err = crypto_rng_alg(tfm)->seed(tfm, seed, slen);
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out:
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kzfree(buf);
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return err;
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}
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EXPORT_SYMBOL_GPL(crypto_rng_reset);
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static int crypto_rng_init_tfm(struct crypto_tfm *tfm)
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{
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return 0;
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}
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static unsigned int seedsize(struct crypto_alg *alg)
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{
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struct rng_alg *ralg = container_of(alg, struct rng_alg, base);
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return ralg->seedsize;
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}
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#ifdef CONFIG_NET
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static int crypto_rng_report(struct sk_buff *skb, struct crypto_alg *alg)
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{
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struct crypto_report_rng rrng;
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strncpy(rrng.type, "rng", sizeof(rrng.type));
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rrng.seedsize = seedsize(alg);
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if (nla_put(skb, CRYPTOCFGA_REPORT_RNG,
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sizeof(struct crypto_report_rng), &rrng))
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goto nla_put_failure;
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return 0;
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nla_put_failure:
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return -EMSGSIZE;
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}
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#else
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static int crypto_rng_report(struct sk_buff *skb, struct crypto_alg *alg)
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{
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return -ENOSYS;
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}
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#endif
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static void crypto_rng_show(struct seq_file *m, struct crypto_alg *alg)
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__maybe_unused;
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static void crypto_rng_show(struct seq_file *m, struct crypto_alg *alg)
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{
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seq_printf(m, "type : rng\n");
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seq_printf(m, "seedsize : %u\n", seedsize(alg));
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}
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static const struct crypto_type crypto_rng_type = {
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.extsize = crypto_alg_extsize,
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.init_tfm = crypto_rng_init_tfm,
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#ifdef CONFIG_PROC_FS
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.show = crypto_rng_show,
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#endif
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.report = crypto_rng_report,
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.maskclear = ~CRYPTO_ALG_TYPE_MASK,
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.maskset = CRYPTO_ALG_TYPE_MASK,
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.type = CRYPTO_ALG_TYPE_RNG,
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.tfmsize = offsetof(struct crypto_rng, base),
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};
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struct crypto_rng *crypto_alloc_rng(const char *alg_name, u32 type, u32 mask)
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{
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return crypto_alloc_tfm(alg_name, &crypto_rng_type, type, mask);
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}
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EXPORT_SYMBOL_GPL(crypto_alloc_rng);
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int crypto_get_default_rng(void)
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{
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struct crypto_rng *rng;
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int err;
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mutex_lock(&crypto_default_rng_lock);
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if (!crypto_default_rng) {
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rng = crypto_alloc_rng("stdrng", 0, 0);
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err = PTR_ERR(rng);
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if (IS_ERR(rng))
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goto unlock;
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err = crypto_rng_reset(rng, NULL, crypto_rng_seedsize(rng));
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if (err) {
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crypto_free_rng(rng);
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goto unlock;
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}
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crypto_default_rng = rng;
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}
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crypto_default_rng_refcnt++;
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err = 0;
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unlock:
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mutex_unlock(&crypto_default_rng_lock);
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return err;
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}
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EXPORT_SYMBOL_GPL(crypto_get_default_rng);
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void crypto_put_default_rng(void)
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{
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mutex_lock(&crypto_default_rng_lock);
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crypto_default_rng_refcnt--;
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mutex_unlock(&crypto_default_rng_lock);
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}
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EXPORT_SYMBOL_GPL(crypto_put_default_rng);
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#if defined(CONFIG_CRYPTO_RNG) || defined(CONFIG_CRYPTO_RNG_MODULE)
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int crypto_del_default_rng(void)
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{
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int err = -EBUSY;
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mutex_lock(&crypto_default_rng_lock);
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if (crypto_default_rng_refcnt)
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goto out;
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crypto_free_rng(crypto_default_rng);
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crypto_default_rng = NULL;
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err = 0;
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out:
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mutex_unlock(&crypto_default_rng_lock);
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return err;
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}
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EXPORT_SYMBOL_GPL(crypto_del_default_rng);
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#endif
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int crypto_register_rng(struct rng_alg *alg)
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{
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struct crypto_alg *base = &alg->base;
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if (alg->seedsize > PAGE_SIZE / 8)
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return -EINVAL;
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base->cra_type = &crypto_rng_type;
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base->cra_flags &= ~CRYPTO_ALG_TYPE_MASK;
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base->cra_flags |= CRYPTO_ALG_TYPE_RNG;
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return crypto_register_alg(base);
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}
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EXPORT_SYMBOL_GPL(crypto_register_rng);
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void crypto_unregister_rng(struct rng_alg *alg)
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{
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crypto_unregister_alg(&alg->base);
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}
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EXPORT_SYMBOL_GPL(crypto_unregister_rng);
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int crypto_register_rngs(struct rng_alg *algs, int count)
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{
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int i, ret;
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for (i = 0; i < count; i++) {
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ret = crypto_register_rng(algs + i);
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if (ret)
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goto err;
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}
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return 0;
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err:
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for (--i; i >= 0; --i)
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crypto_unregister_rng(algs + i);
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return ret;
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}
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EXPORT_SYMBOL_GPL(crypto_register_rngs);
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void crypto_unregister_rngs(struct rng_alg *algs, int count)
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{
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int i;
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for (i = count - 1; i >= 0; --i)
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crypto_unregister_rng(algs + i);
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}
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EXPORT_SYMBOL_GPL(crypto_unregister_rngs);
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MODULE_LICENSE("GPL");
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MODULE_DESCRIPTION("Random Number Generator");
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