crypto: drbg - SP800-90A Deterministic Random Bit Generator

This is a clean-room implementation of the DRBG defined in SP800-90A.
All three viable DRBGs defined in the standard are implemented:

 * HMAC: This is the leanest DRBG and compiled per default
 * Hash: The more complex DRBG can be enabled at compile time
 * CTR: The most complex DRBG can also be enabled at compile time

The DRBG implementation offers the following:

 * All three DRBG types are implemented with a derivation function.
 * All DRBG types are available with and without prediction resistance.
 * All SHA types of SHA-1, SHA-256, SHA-384, SHA-512 are available for
   the HMAC and Hash DRBGs.
 * All AES types of AES-128, AES-192 and AES-256 are available for the
   CTR DRBG.
 * A self test is implemented with drbg_healthcheck().
 * The FIPS 140-2 continuous self test is implemented.

Signed-off-by: Stephan Mueller <smueller@chronox.de>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

1 files changed, 2007 insertions, 0 deletions

diff --git a/crypto/drbg.c b/crypto/drbg.c
new file mode 100644
index 000000000000..faaa2cefeeed
--- /dev/null
+++ b/crypto/drbg.c
@@ -0,0 +1,2007 @@
+/*
+ * DRBG: Deterministic Random Bits Generator
+ *       Based on NIST Recommended DRBG from NIST SP800-90A with the following
+ *       properties:
+ *              * CTR DRBG with DF with AES-128, AES-192, AES-256 cores
+ *              * Hash DRBG with DF with SHA-1, SHA-256, SHA-384, SHA-512 cores
+ *              * HMAC DRBG with DF with SHA-1, SHA-256, SHA-384, SHA-512 cores
+ *              * with and without prediction resistance
+ *
+ * Copyright Stephan Mueller <smueller@chronox.de>, 2014
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, and the entire permission notice in its entirety,
+ *    including the disclaimer of warranties.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. The name of the author may not be used to endorse or promote
+ *    products derived from this software without specific prior
+ *    written permission.
+ *
+ * ALTERNATIVELY, this product may be distributed under the terms of
+ * the GNU General Public License, in which case the provisions of the GPL are
+ * required INSTEAD OF the above restrictions.  (This clause is
+ * necessary due to a potential bad interaction between the GPL and
+ * the restrictions contained in a BSD-style copyright.)
+ *
+ * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
+ * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, ALL OF
+ * WHICH ARE HEREBY DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
+ * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
+ * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
+ * USE OF THIS SOFTWARE, EVEN IF NOT ADVISED OF THE POSSIBILITY OF SUCH
+ * DAMAGE.
+ *
+ * DRBG Usage
+ * ==========
+ * The SP 800-90A DRBG allows the user to specify a personalization string
+ * for initialization as well as an additional information string for each
+ * random number request. The following code fragments show how a caller
+ * uses the kernel crypto API to use the full functionality of the DRBG.
+ *
+ * Usage without any additional data
+ * ---------------------------------
+ * struct crypto_rng *drng;
+ * int err;
+ * char data[DATALEN];
+ *
+ * drng = crypto_alloc_rng(drng_name, 0, 0);
+ * err = crypto_rng_get_bytes(drng, &data, DATALEN);
+ * crypto_free_rng(drng);
+ *
+ *
+ * Usage with personalization string during initialization
+ * -------------------------------------------------------
+ * struct crypto_rng *drng;
+ * int err;
+ * char data[DATALEN];
+ * struct drbg_string pers;
+ * char personalization[11] = "some-string";
+ *
+ * drbg_string_fill(&pers, personalization, strlen(personalization));
+ * drng = crypto_alloc_rng(drng_name, 0, 0);
+ * // The reset completely re-initializes the DRBG with the provided
+ * // personalization string
+ * err = crypto_rng_reset(drng, &personalization, strlen(personalization));
+ * err = crypto_rng_get_bytes(drng, &data, DATALEN);
+ * crypto_free_rng(drng);
+ *
+ *
+ * Usage with additional information string during random number request
+ * ---------------------------------------------------------------------
+ * struct crypto_rng *drng;
+ * int err;
+ * char data[DATALEN];
+ * char addtl_string[11] = "some-string";
+ * string drbg_string addtl;
+ *
+ * drbg_string_fill(&addtl, addtl_string, strlen(addtl_string));
+ * drng = crypto_alloc_rng(drng_name, 0, 0);
+ * // The following call is a wrapper to crypto_rng_get_bytes() and returns
+ * // the same error codes.
+ * err = crypto_drbg_get_bytes_addtl(drng, &data, DATALEN, &addtl);
+ * crypto_free_rng(drng);
+ *
+ *
+ * Usage with personalization and additional information strings
+ * -------------------------------------------------------------
+ * Just mix both scenarios above.
+ */
+
+#include <crypto/drbg.h>
+
+#if !defined(CONFIG_CRYPTO_DRBG_HASH) && \
+        !defined(CONFIG_CRYPTO_DRBG_HMAC) && \
+        !defined(CONFIG_CRYPTO_DRBG_CTR)
+#warning "The DRBG code is useless without compiling at least one DRBG type"
+#endif
+
+/***************************************************************
+ * Backend cipher definitions available to DRBG
+ ***************************************************************/
+
+/*
+ * The order of the DRBG definitions here matter: every DRBG is registered
+ * as stdrng. Each DRBG receives an increasing cra_priority values the later
+ * they are defined in this array (see drbg_fill_array).
+ *
+ * HMAC DRBGs are favored over Hash DRBGs over CTR DRBGs, and
+ * the SHA256 / AES 256 over other ciphers. Thus, the favored
+ * DRBGs are the latest entries in this array.
+ */
+static const struct drbg_core drbg_cores[] = {
+#ifdef CONFIG_CRYPTO_DRBG_CTR
+        {
+                .flags = DRBG_CTR | DRBG_STRENGTH128,
+                .statelen = 32, /* 256 bits as defined in 10.2.1 */
+                .max_addtllen = 35,
+                .max_bits = 19,
+                .max_req = 48,
+                .blocklen_bytes = 16,
+                .cra_name = "ctr_aes128",
+                .backend_cra_name = "ecb(aes)",
+        }, {
+                .flags = DRBG_CTR | DRBG_STRENGTH192,
+                .statelen = 40, /* 320 bits as defined in 10.2.1 */
+                .max_addtllen = 35,
+                .max_bits = 19,
+                .max_req = 48,
+                .blocklen_bytes = 16,
+                .cra_name = "ctr_aes192",
+                .backend_cra_name = "ecb(aes)",
+        }, {
+                .flags = DRBG_CTR | DRBG_STRENGTH256,
+                .statelen = 48, /* 384 bits as defined in 10.2.1 */
+                .max_addtllen = 35,
+                .max_bits = 19,
+                .max_req = 48,
+                .blocklen_bytes = 16,
+                .cra_name = "ctr_aes256",
+                .backend_cra_name = "ecb(aes)",
+        },
+#endif /* CONFIG_CRYPTO_DRBG_CTR */
+#ifdef CONFIG_CRYPTO_DRBG_HASH
+        {
+                .flags = DRBG_HASH | DRBG_STRENGTH128,
+                .statelen = 55, /* 440 bits */
+                .max_addtllen = 35,
+                .max_bits = 19,
+                .max_req = 48,
+                .blocklen_bytes = 20,
+                .cra_name = "sha1",
+                .backend_cra_name = "sha1",
+        }, {
+                .flags = DRBG_HASH | DRBG_STRENGTH256,
+                .statelen = 111, /* 888 bits */
+                .max_addtllen = 35,
+                .max_bits = 19,
+                .max_req = 48,
+                .blocklen_bytes = 48,
+                .cra_name = "sha384",
+                .backend_cra_name = "sha384",
+        }, {
+                .flags = DRBG_HASH | DRBG_STRENGTH256,
+                .statelen = 111, /* 888 bits */
+                .max_addtllen = 35,
+                .max_bits = 19,
+                .max_req = 48,
+                .blocklen_bytes = 64,
+                .cra_name = "sha512",
+                .backend_cra_name = "sha512",
+        }, {
+                .flags = DRBG_HASH | DRBG_STRENGTH256,
+                .statelen = 55, /* 440 bits */
+                .max_addtllen = 35,
+                .max_bits = 19,
+                .max_req = 48,
+                .blocklen_bytes = 32,
+                .cra_name = "sha256",
+                .backend_cra_name = "sha256",
+        },
+#endif /* CONFIG_CRYPTO_DRBG_HASH */
+#ifdef CONFIG_CRYPTO_DRBG_HMAC
+        {
+                .flags = DRBG_HMAC | DRBG_STRENGTH256,
+                .statelen = 20, /* block length of cipher */
+                .max_addtllen = 35,
+                .max_bits = 19,
+                .max_req = 48,
+                .blocklen_bytes = 20,
+                .cra_name = "hmac_sha1",
+                .backend_cra_name = "hmac(sha1)",
+        }, {
+                .flags = DRBG_HMAC | DRBG_STRENGTH256,
+                .statelen = 48, /* block length of cipher */
+                .max_addtllen = 35,
+                .max_bits = 19,
+                .max_req = 48,
+                .blocklen_bytes = 48,
+                .cra_name = "hmac_sha384",
+                .backend_cra_name = "hmac(sha384)",
+        }, {
+                .flags = DRBG_HMAC | DRBG_STRENGTH256,
+                .statelen = 64, /* block length of cipher */
+                .max_addtllen = 35,
+                .max_bits = 19,
+                .max_req = 48,
+                .blocklen_bytes = 64,
+                .cra_name = "hmac_sha512",
+                .backend_cra_name = "hmac(sha512)",
+        }, {
+                .flags = DRBG_HMAC | DRBG_STRENGTH256,
+                .statelen = 32, /* block length of cipher */
+                .max_addtllen = 35,
+                .max_bits = 19,
+                .max_req = 48,
+                .blocklen_bytes = 32,
+                .cra_name = "hmac_sha256",
+                .backend_cra_name = "hmac(sha256)",
+        },
+#endif /* CONFIG_CRYPTO_DRBG_HMAC */
+};
+
+/******************************************************************
+ * Generic helper functions
+ ******************************************************************/
+
+/*
+ * Return strength of DRBG according to SP800-90A section 8.4
+ *
+ * @flags DRBG flags reference
+ *
+ * Return: normalized strength in *bytes* value or 32 as default
+ *         to counter programming errors
+ */
+static inline unsigned short drbg_sec_strength(drbg_flag_t flags)
+{
+        switch (flags & DRBG_STRENGTH_MASK) {
+        case DRBG_STRENGTH128:
+                return 16;
+        case DRBG_STRENGTH192:
+                return 24;
+        case DRBG_STRENGTH256:
+                return 32;
+        default:
+                return 32;
+        }
+}
+
+/*
+ * FIPS 140-2 continuous self test
+ * The test is performed on the result of one round of the output
+ * function. Thus, the function implicitly knows the size of the
+ * buffer.
+ *
+ * The FIPS test can be called in an endless loop until it returns
+ * true. Although the code looks like a potential for a deadlock, it
+ * is not the case, because returning a false cannot mathematically
+ * occur (except once when a reseed took place and the updated state
+ * would is now set up such that the generation of new value returns
+ * an identical one -- this is most unlikely and would happen only once).
+ * Thus, if this function repeatedly returns false and thus would cause
+ * a deadlock, the integrity of the entire kernel is lost.
+ *
+ * @drbg DRBG handle
+ * @buf output buffer of random data to be checked
+ *
+ * return:
+ *      true on success
+ *      false on error
+ */
+static bool drbg_fips_continuous_test(struct drbg_state *drbg,
+                                      const unsigned char *buf)
+{
+#ifdef CONFIG_CRYPTO_FIPS
+        int ret = 0;
+        /* skip test if we test the overall system */
+        if (drbg->test_data)
+                return true;
+        /* only perform test in FIPS mode */
+        if (0 == fips_enabled)
+                return true;
+        if (!drbg->fips_primed) {
+                /* Priming of FIPS test */
+                memcpy(drbg->prev, buf, drbg_blocklen(drbg));
+                drbg->fips_primed = true;
+                /* return false due to priming, i.e. another round is needed */
+                return false;
+        }
+        ret = memcmp(drbg->prev, buf, drbg_blocklen(drbg));
+        memcpy(drbg->prev, buf, drbg_blocklen(drbg));
+        /* the test shall pass when the two compared values are not equal */
+        return ret != 0;
+#else
+        return true;
+#endif /* CONFIG_CRYPTO_FIPS */
+}
+
+/*
+ * Convert an integer into a byte representation of this integer.
+ * The byte representation is big-endian
+ *
+ * @buf buffer holding the converted integer
+ * @val value to be converted
+ * @buflen length of buffer
+ */
+#if (defined(CONFIG_CRYPTO_DRBG_HASH) || defined(CONFIG_CRYPTO_DRBG_CTR))
+static inline void drbg_int2byte(unsigned char *buf, uint64_t val,
+                                 size_t buflen)
+{
+        unsigned char *byte;
+        uint64_t i;
+
+        byte = buf + (buflen - 1);
+        for (i = 0; i < buflen; i++)
+                *(byte--) = val >> (i * 8) & 0xff;
+}
+
+/*
+ * Increment buffer
+ *
+ * @dst buffer to increment
+ * @add value to add
+ */
+static inline void drbg_add_buf(unsigned char *dst, size_t dstlen,
+                                const unsigned char *add, size_t addlen)
+{
+        /* implied: dstlen > addlen */
+        unsigned char *dstptr;
+        const unsigned char *addptr;
+        unsigned int remainder = 0;
+        size_t len = addlen;
+
+        dstptr = dst + (dstlen-1);
+        addptr = add + (addlen-1);
+        while (len) {
+                remainder += *dstptr + *addptr;
+                *dstptr = remainder & 0xff;
+                remainder >>= 8;
+                len--; dstptr--; addptr--;
+        }
+        len = dstlen - addlen;
+        while (len && remainder > 0) {
+                remainder = *dstptr + 1;
+                *dstptr = remainder & 0xff;
+                remainder >>= 8;
+                len--; dstptr--;
+        }
+}
+#endif /* defined(CONFIG_CRYPTO_DRBG_HASH) || defined(CONFIG_CRYPTO_DRBG_CTR) */
+
+/******************************************************************
+ * CTR DRBG callback functions
+ ******************************************************************/
+
+#ifdef CONFIG_CRYPTO_DRBG_CTR
+static int drbg_kcapi_sym(struct drbg_state *drbg, const unsigned char *key,
+                          unsigned char *outval, const struct drbg_string *in);
+static int drbg_init_sym_kernel(struct drbg_state *drbg);
+static int drbg_fini_sym_kernel(struct drbg_state *drbg);
+
+/* BCC function for CTR DRBG as defined in 10.4.3 */
+static int drbg_ctr_bcc(struct drbg_state *drbg,
+                        unsigned char *out, const unsigned char *key,
+                        struct drbg_string *in)
+{
+        int ret = -EFAULT;
+        struct drbg_string *curr = in;
+        size_t inpos = curr->len;
+        const unsigned char *pos = curr->buf;
+        struct drbg_string data;
+
+        drbg_string_fill(&data, out, drbg_blocklen(drbg));
+
+        /* 10.4.3 step 1 */
+        memset(out, 0, drbg_blocklen(drbg));
+
+        /* 10.4.3 step 2 / 4 */
+        while (inpos) {
+                short cnt = 0;
+                /* 10.4.3 step 4.1 */
+                for (cnt = 0; cnt < drbg_blocklen(drbg); cnt++) {
+                        out[cnt] ^= *pos;
+                        pos++; inpos--;
+                        /*
+                         * The following branch implements the linked list
+                         * iteration of drbg_string *in. If we are at the
+                         * end of the current list member, we have to start
+                         * using the next member if available. The inpos
+                         * value always points to the current byte and will
+                         * be zero if we have processed the last byte of
+                         * the last linked list member.
+                         */
+                        if (0 == inpos) {
+                                curr = curr->next;
+                                if (NULL != curr) {
+                                        pos = curr->buf;
+                                        inpos = curr->len;
+                                } else {
+                                        inpos = 0;
+                                        break;
+                                }
+                        }
+                }
+                /* 10.4.3 step 4.2 */
+                ret = drbg_kcapi_sym(drbg, key, out, &data);
+                if (ret)
+                        return ret;
+                /* 10.4.3 step 2 */
+        }
+        return 0;
+}
+
+/*
+ * scratchpad usage: drbg_ctr_update is interlinked with drbg_ctr_df
+ * (and drbg_ctr_bcc, but this function does not need any temporary buffers),
+ * the scratchpad is used as follows:
+ * drbg_ctr_update:
+ *      temp
+ *              start: drbg->scratchpad
+ *              length: drbg_statelen(drbg) + drbg_blocklen(drbg)
+ *                      note: the cipher writing into this variable works
+ *                      blocklen-wise. Now, when the statelen is not a multiple
+ *                      of blocklen, the generateion loop below "spills over"
+ *                      by at most blocklen. Thus, we need to give sufficient
+ *                      memory.
+ *      df_data
+ *              start: drbg->scratchpad +
+ *                              drbg_statelen(drbg) + drbg_blocklen(drbg)
+ *              length: drbg_statelen(drbg)
+ *
+ * drbg_ctr_df:
+ *      pad
+ *              start: df_data + drbg_statelen(drbg)
+ *              length: drbg_blocklen(drbg)
+ *      iv
+ *              start: pad + drbg_blocklen(drbg)
+ *              length: drbg_blocklen(drbg)
+ *      temp
+ *              start: iv + drbg_blocklen(drbg)
+ *              length: (drbg_keylen(drbg) + drbg_blocklen(drbg) ==
+ *                              drbg_statelen(drbg))
+ */
+
+/* Derivation Function for CTR DRBG as defined in 10.4.2 */
+static int drbg_ctr_df(struct drbg_state *drbg,
+                       unsigned char *df_data, size_t bytes_to_return,
+                       struct drbg_string *addtl)
+{
+        int ret = -EFAULT;
+        unsigned char L_N[8];
+        /* S3 is input */
+        struct drbg_string S1, S2, S4, cipherin;
+        struct drbg_string *tempstr = addtl;
+        unsigned char *pad = df_data + drbg_statelen(drbg);
+        unsigned char *iv = pad + drbg_blocklen(drbg);
+        unsigned char *temp = iv + drbg_blocklen(drbg);
+        size_t padlen = 0;
+        unsigned int templen = 0;
+        /* 10.4.2 step 7 */
+        unsigned int i = 0;
+        /* 10.4.2 step 8 */
+        const unsigned char *K = (unsigned char *)
+                           "\x00\x01\x02\x03\x04\x05\x06\x07"
+                           "\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f"
+                           "\x10\x11\x12\x13\x14\x15\x16\x17"
+                           "\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f";
+        unsigned char *X;
+        size_t generated_len = 0;
+        size_t inputlen = 0;
+
+        memset(pad, 0, drbg_blocklen(drbg));
+        memset(iv, 0, drbg_blocklen(drbg));
+        memset(temp, 0, drbg_statelen(drbg));
+
+        /* 10.4.2 step 1 is implicit as we work byte-wise */
+
+        /* 10.4.2 step 2 */
+        if ((512/8) < bytes_to_return)
+                return -EINVAL;
+
+        /* 10.4.2 step 2 -- calculate the entire length of all input data */
+        for (; NULL != tempstr; tempstr = tempstr->next)
+                inputlen += tempstr->len;
+        drbg_int2byte(&L_N[0], inputlen, 4);
+
+        /* 10.4.2 step 3 */
+        drbg_int2byte(&L_N[4], bytes_to_return, 4);
+
+        /* 10.4.2 step 5: length is L_N, input_string, one byte, padding */
+        padlen = (inputlen + sizeof(L_N) + 1) % (drbg_blocklen(drbg));
+        /* wrap the padlen appropriately */
+        if (padlen)
+                padlen = drbg_blocklen(drbg) - padlen;
+        /*
+         * pad / padlen contains the 0x80 byte and the following zero bytes.
+         * As the calculated padlen value only covers the number of zero
+         * bytes, this value has to be incremented by one for the 0x80 byte.
+         */
+        padlen++;
+        pad[0] = 0x80;
+
+        /* 10.4.2 step 4 -- first fill the linked list and then order it */
+        drbg_string_fill(&S1, iv, drbg_blocklen(drbg));
+        drbg_string_fill(&S2, L_N, sizeof(L_N));
+        drbg_string_fill(&S4, pad, padlen);
+        S1.next = &S2;
+        S2.next = addtl;
+
+        /*
+         * splice in addtl between S2 and S4 -- we place S4 at the end of the
+         * input data chain
+         */
+        tempstr = addtl;
+        for (; NULL != tempstr; tempstr = tempstr->next)
+                if (NULL == tempstr->next)
+                        break;
+        tempstr->next = &S4;
+
+        /* 10.4.2 step 9 */
+        while (templen < (drbg_keylen(drbg) + (drbg_blocklen(drbg)))) {
+                /*
+                 * 10.4.2 step 9.1 - the padding is implicit as the buffer
+                 * holds zeros after allocation -- even the increment of i
+                 * is irrelevant as the increment remains within length of i
+                 */
+                drbg_int2byte(iv, i, 4);
+                /* 10.4.2 step 9.2 -- BCC and concatenation with temp */
+                ret = drbg_ctr_bcc(drbg, temp + templen, K, &S1);
+                if (ret)
+                        goto out;
+                /* 10.4.2 step 9.3 */
+                i++;
+                templen += drbg_blocklen(drbg);
+        }
+
+        /* 10.4.2 step 11 */
+        X = temp + (drbg_keylen(drbg));
+        drbg_string_fill(&cipherin, X, drbg_blocklen(drbg));
+
+        /* 10.4.2 step 12: overwriting of outval is implemented in next step */
+
+        /* 10.4.2 step 13 */
+        while (generated_len < bytes_to_return) {
+                short blocklen = 0;
+                /*
+                 * 10.4.2 step 13.1: the truncation of the key length is
+                 * implicit as the key is only drbg_blocklen in size based on
+                 * the implementation of the cipher function callback
+                 */
+                ret = drbg_kcapi_sym(drbg, temp, X, &cipherin);
+                if (ret)
+                        goto out;
+                blocklen = (drbg_blocklen(drbg) <
+                                (bytes_to_return - generated_len)) ?
+                            drbg_blocklen(drbg) :
+                                (bytes_to_return - generated_len);
+                /* 10.4.2 step 13.2 and 14 */
+                memcpy(df_data + generated_len, X, blocklen);
+                generated_len += blocklen;
+        }
+
+        ret = 0;
+
+out:
+        memset(iv, 0, drbg_blocklen(drbg));
+        memset(temp, 0, drbg_statelen(drbg));
+        memset(pad, 0, drbg_blocklen(drbg));
+        return ret;
+}
+
+/* update function of CTR DRBG as defined in 10.2.1.2 */
+static int drbg_ctr_update(struct drbg_state *drbg,
+                           struct drbg_string *addtl, int reseed)
+{
+        int ret = -EFAULT;
+        /* 10.2.1.2 step 1 */
+        unsigned char *temp = drbg->scratchpad;
+        unsigned char *df_data = drbg->scratchpad + drbg_statelen(drbg) +
+                                 drbg_blocklen(drbg);
+        unsigned char *temp_p, *df_data_p; /* pointer to iterate over buffers */
+        unsigned int len = 0;
+        struct drbg_string cipherin;
+        unsigned char prefix = DRBG_PREFIX1;
+
+        memset(temp, 0, drbg_statelen(drbg) + drbg_blocklen(drbg));
+        memset(df_data, 0, drbg_statelen(drbg));
+
+        /* 10.2.1.3.2 step 2 and 10.2.1.4.2 step 2 */
+        if (addtl && 0 < addtl->len) {
+                ret = drbg_ctr_df(drbg, df_data, drbg_statelen(drbg),
+                                  addtl);
+                if (ret)
+                        goto out;
+        }
+
+        drbg_string_fill(&cipherin, drbg->V, drbg_blocklen(drbg));
+        /*
+         * 10.2.1.3.2 steps 2 and 3 are already covered as the allocation
+         * zeroizes all memory during initialization
+         */
+        while (len < (drbg_statelen(drbg))) {
+                /* 10.2.1.2 step 2.1 */
+                drbg_add_buf(drbg->V, drbg_blocklen(drbg), &prefix, 1);
+                /*
+                 * 10.2.1.2 step 2.2 */
+                ret = drbg_kcapi_sym(drbg, drbg->C, temp + len, &cipherin);
+                if (ret)
+                        goto out;
+                /* 10.2.1.2 step 2.3 and 3 */
+                len += drbg_blocklen(drbg);
+        }
+
+        /* 10.2.1.2 step 4 */
+        temp_p = temp;
+        df_data_p = df_data;
+        for (len = 0; len < drbg_statelen(drbg); len++) {
+                *temp_p ^= *df_data_p;
+                df_data_p++; temp_p++;
+        }
+
+        /* 10.2.1.2 step 5 */
+        memcpy(drbg->C, temp, drbg_keylen(drbg));
+        /* 10.2.1.2 step 6 */
+        memcpy(drbg->V, temp + drbg_keylen(drbg), drbg_blocklen(drbg));
+        ret = 0;
+
+out:
+        memset(temp, 0, drbg_statelen(drbg) + drbg_blocklen(drbg));
+        memset(df_data, 0, drbg_statelen(drbg));
+        return ret;
+}
+
+/*
+ * scratchpad use: drbg_ctr_update is called independently from
+ * drbg_ctr_extract_bytes. Therefore, the scratchpad is reused
+ */
+/* Generate function of CTR DRBG as defined in 10.2.1.5.2 */
+static int drbg_ctr_generate(struct drbg_state *drbg,
+                             unsigned char *buf, unsigned int buflen,
+                             struct drbg_string *addtl)
+{
+        int len = 0;
+        int ret = 0;
+        struct drbg_string data;
+        unsigned char prefix = DRBG_PREFIX1;
+
+        memset(drbg->scratchpad, 0, drbg_blocklen(drbg));
+
+        /* 10.2.1.5.2 step 2 */
+        if (addtl && 0 < addtl->len) {
+                addtl->next = NULL;
+                ret = drbg_ctr_update(drbg, addtl, 1);
+                if (ret)
+                        return 0;
+        }
+
+        /* 10.2.1.5.2 step 4.1 */
+        drbg_add_buf(drbg->V, drbg_blocklen(drbg), &prefix, 1);
+        drbg_string_fill(&data, drbg->V, drbg_blocklen(drbg));
+        while (len < buflen) {
+                int outlen = 0;
+                /* 10.2.1.5.2 step 4.2 */
+                ret = drbg_kcapi_sym(drbg, drbg->C, drbg->scratchpad, &data);
+                if (ret) {
+                        len = ret;
+                        goto out;
+                }
+                outlen = (drbg_blocklen(drbg) < (buflen - len)) ?
+                          drbg_blocklen(drbg) : (buflen - len);
+                if (!drbg_fips_continuous_test(drbg, drbg->scratchpad)) {
+                        /* 10.2.1.5.2 step 6 */
+                        drbg_add_buf(drbg->V, drbg_blocklen(drbg), &prefix, 1);
+                        continue;
+                }
+                /* 10.2.1.5.2 step 4.3 */
+                memcpy(buf + len, drbg->scratchpad, outlen);
+                len += outlen;
+                /* 10.2.1.5.2 step 6 */
+                if (len < buflen)
+                        drbg_add_buf(drbg->V, drbg_blocklen(drbg), &prefix, 1);
+        }
+
+        /* 10.2.1.5.2 step 6 */
+        if (addtl)
+                addtl->next = NULL;
+        /*
+         * The following call invokes the DF function again which could be
+         * optimized. In step 2, the "additional_input" after step 2 is the
+         * output of the DF function. If this result would be saved, the DF
+         * function would not need to be invoked again at this point.
+         */
+        ret = drbg_ctr_update(drbg, addtl, 1);
+        if (ret)
+                len = ret;
+
+out:
+        memset(drbg->scratchpad, 0, drbg_blocklen(drbg));
+        return len;
+}
+
+static struct drbg_state_ops drbg_ctr_ops = {
+        .update         = drbg_ctr_update,
+        .generate       = drbg_ctr_generate,
+        .crypto_init    = drbg_init_sym_kernel,
+        .crypto_fini    = drbg_fini_sym_kernel,
+};
+#endif /* CONFIG_CRYPTO_DRBG_CTR */
+
+/******************************************************************
+ * HMAC DRBG callback functions
+ ******************************************************************/
+
+#if defined(CONFIG_CRYPTO_DRBG_HASH) || defined(CONFIG_CRYPTO_DRBG_HMAC)
+static int drbg_kcapi_hash(struct drbg_state *drbg, const unsigned char *key,
+                           unsigned char *outval, const struct drbg_string *in);
+static int drbg_init_hash_kernel(struct drbg_state *drbg);
+static int drbg_fini_hash_kernel(struct drbg_state *drbg);
+#endif /* (CONFIG_CRYPTO_DRBG_HASH || CONFIG_CRYPTO_DRBG_HMAC) */
+
+#ifdef CONFIG_CRYPTO_DRBG_HMAC
+/* update function of HMAC DRBG as defined in 10.1.2.2 */
+static int drbg_hmac_update(struct drbg_state *drbg,
+                            struct drbg_string *seed, int reseed)
+{
+        int ret = -EFAULT;
+        int i = 0;
+        struct drbg_string seed1, seed2, cipherin;
+
+        if (!reseed) {
+                /* 10.1.2.3 step 2 */
+                memset(drbg->C, 0, drbg_statelen(drbg));
+                memset(drbg->V, 1, drbg_statelen(drbg));
+        }
+
+        drbg_string_fill(&seed1, drbg->V, drbg_statelen(drbg));
+        /* buffer of seed2 will be filled in for loop below with one byte */
+        drbg_string_fill(&seed2, NULL, 1);
+        seed1.next = &seed2;
+        /* input data of seed is allowed to be NULL at this point */
+        seed2.next = seed;
+
+        drbg_string_fill(&cipherin, drbg->V, drbg_statelen(drbg));
+        for (i = 2; 0 < i; i--) {
+                /* first round uses 0x0, second 0x1 */
+                unsigned char prefix = DRBG_PREFIX0;
+                if (1 == i)
+                        prefix = DRBG_PREFIX1;
+                /* 10.1.2.2 step 1 and 4 -- concatenation and HMAC for key */
+                seed2.buf = &prefix;
+                ret = drbg_kcapi_hash(drbg, drbg->C, drbg->C, &seed1);
+                if (ret)
+                        return ret;
+
+                /* 10.1.2.2 step 2 and 5 -- HMAC for V */
+                ret = drbg_kcapi_hash(drbg, drbg->C, drbg->V, &cipherin);
+                if (ret)
+                        return ret;
+
+                /* 10.1.2.2 step 3 */
+                if (!seed || 0 == seed->len)
+                        return ret;
+        }
+
+        return 0;
+}
+
+/* generate function of HMAC DRBG as defined in 10.1.2.5 */
+static int drbg_hmac_generate(struct drbg_state *drbg,
+                              unsigned char *buf,
+                              unsigned int buflen,
+                              struct drbg_string *addtl)
+{
+        int len = 0;
+        int ret = 0;
+        struct drbg_string data;
+
+        /* 10.1.2.5 step 2 */
+        if (addtl && 0 < addtl->len) {
+                addtl->next = NULL;
+                ret = drbg_hmac_update(drbg, addtl, 1);
+                if (ret)
+                        return ret;
+        }
+
+        drbg_string_fill(&data, drbg->V, drbg_statelen(drbg));
+        while (len < buflen) {
+                unsigned int outlen = 0;
+                /* 10.1.2.5 step 4.1 */
+                ret = drbg_kcapi_hash(drbg, drbg->C, drbg->V, &data);
+                if (ret)
+                        return ret;
+                outlen = (drbg_blocklen(drbg) < (buflen - len)) ?
+                          drbg_blocklen(drbg) : (buflen - len);
+                if (!drbg_fips_continuous_test(drbg, drbg->V))
+                        continue;
+
+                /* 10.1.2.5 step 4.2 */
+                memcpy(buf + len, drbg->V, outlen);
+                len += outlen;
+        }
+
+        /* 10.1.2.5 step 6 */
+        if (addtl)
+                addtl->next = NULL;
+        ret = drbg_hmac_update(drbg, addtl, 1);
+        if (ret)
+                return ret;
+
+        return len;
+}
+
+static struct drbg_state_ops drbg_hmac_ops = {
+        .update         = drbg_hmac_update,
+        .generate       = drbg_hmac_generate,
+        .crypto_init    = drbg_init_hash_kernel,
+        .crypto_fini    = drbg_fini_hash_kernel,
+
+};
+#endif /* CONFIG_CRYPTO_DRBG_HMAC */
+
+/******************************************************************
+ * Hash DRBG callback functions
+ ******************************************************************/
+
+#ifdef CONFIG_CRYPTO_DRBG_HASH
+/*
+ * scratchpad usage: as drbg_hash_update and drbg_hash_df are used
+ * interlinked, the scratchpad is used as follows:
+ * drbg_hash_update
+ *      start: drbg->scratchpad
+ *      length: drbg_statelen(drbg)
+ * drbg_hash_df:
+ *      start: drbg->scratchpad + drbg_statelen(drbg)
+ *      length: drbg_blocklen(drbg)
+ *
+ * drbg_hash_process_addtl uses the scratchpad, but fully completes
+ * before either of the functions mentioned before are invoked. Therefore,
+ * drbg_hash_process_addtl does not need to be specifically considered.
+ */
+
+/* Derivation Function for Hash DRBG as defined in 10.4.1 */
+static int drbg_hash_df(struct drbg_state *drbg,
+                        unsigned char *outval, size_t outlen,
+                        struct drbg_string *entropy)
+{
+        int ret = 0;
+        size_t len = 0;
+        unsigned char input[5];
+        unsigned char *tmp = drbg->scratchpad + drbg_statelen(drbg);
+        struct drbg_string data1;
+
+        memset(tmp, 0, drbg_blocklen(drbg));
+
+        /* 10.4.1 step 3 */
+        input[0] = 1;
+        drbg_int2byte(&input[1], (outlen * 8), 4);
+
+        /* 10.4.1 step 4.1 -- concatenation of data for input into hash */
+        drbg_string_fill(&data1, input, 5);
+        data1.next = entropy;
+
+        /* 10.4.1 step 4 */
+        while (len < outlen) {
+                short blocklen = 0;
+                /* 10.4.1 step 4.1 */
+                ret = drbg_kcapi_hash(drbg, NULL, tmp, &data1);
+                if (ret)
+                        goto out;
+                /* 10.4.1 step 4.2 */
+                input[0]++;
+                blocklen = (drbg_blocklen(drbg) < (outlen - len)) ?
+                            drbg_blocklen(drbg) : (outlen - len);
+                memcpy(outval + len, tmp, blocklen);
+                len += blocklen;
+        }
+
+out:
+        memset(tmp, 0, drbg_blocklen(drbg));
+        return ret;
+}
+
+/* update function for Hash DRBG as defined in 10.1.1.2 / 10.1.1.3 */
+static int drbg_hash_update(struct drbg_state *drbg, struct drbg_string *seed,
+                            int reseed)
+{
+        int ret = 0;
+        struct drbg_string data1, data2;
+        unsigned char *V = drbg->scratchpad;
+        unsigned char prefix = DRBG_PREFIX1;
+
+        memset(drbg->scratchpad, 0, drbg_statelen(drbg));
+        if (!seed)
+                return -EINVAL;
+
+        if (reseed) {
+                /* 10.1.1.3 step 1 */
+                memcpy(V, drbg->V, drbg_statelen(drbg));
+                drbg_string_fill(&data1, &prefix, 1);
+                drbg_string_fill(&data2, V, drbg_statelen(drbg));
+                data1.next = &data2;
+                data2.next = seed;
+        } else {
+                drbg_string_fill(&data1, seed->buf, seed->len);
+                data1.next = seed->next;
+        }
+
+        /* 10.1.1.2 / 10.1.1.3 step 2 and 3 */
+        ret = drbg_hash_df(drbg, drbg->V, drbg_statelen(drbg), &data1);
+        if (ret)
+                goto out;
+
+        /* 10.1.1.2 / 10.1.1.3 step 4  */
+        prefix = DRBG_PREFIX0;
+        drbg_string_fill(&data1, &prefix, 1);
+        drbg_string_fill(&data2, drbg->V, drbg_statelen(drbg));
+        data1.next = &data2;
+        /* 10.1.1.2 / 10.1.1.3 step 4 */
+        ret = drbg_hash_df(drbg, drbg->C, drbg_statelen(drbg), &data1);
+
+out:
+        memset(drbg->scratchpad, 0, drbg_statelen(drbg));
+        return ret;
+}
+
+/* processing of additional information string for Hash DRBG */
+static int drbg_hash_process_addtl(struct drbg_state *drbg,
+                                   struct drbg_string *addtl)
+{
+        int ret = 0;
+        struct drbg_string data1, data2;
+        struct drbg_string *data3;
+        unsigned char prefix = DRBG_PREFIX2;
+
+        /* this is value w as per documentation */
+        memset(drbg->scratchpad, 0, drbg_blocklen(drbg));
+
+        /* 10.1.1.4 step 2 */
+        if (!addtl || 0 == addtl->len)
+                return 0;
+
+        /* 10.1.1.4 step 2a */
+        drbg_string_fill(&data1, &prefix, 1);
+        drbg_string_fill(&data2, drbg->V, drbg_statelen(drbg));
+        data3 = addtl;
+        data1.next = &data2;
+        data2.next = data3;
+        data3->next = NULL;
+        ret = drbg_kcapi_hash(drbg, NULL, drbg->scratchpad, &data1);
+        if (ret)
+                goto out;
+
+        /* 10.1.1.4 step 2b */
+        drbg_add_buf(drbg->V, drbg_statelen(drbg),
+                     drbg->scratchpad, drbg_blocklen(drbg));
+
+out:
+        memset(drbg->scratchpad, 0, drbg_blocklen(drbg));
+        return ret;
+}
+
+/* Hashgen defined in 10.1.1.4 */
+static int drbg_hash_hashgen(struct drbg_state *drbg,
+                             unsigned char *buf,
+                             unsigned int buflen)
+{
+        int len = 0;
+        int ret = 0;
+        unsigned char *src = drbg->scratchpad;
+        unsigned char *dst = drbg->scratchpad + drbg_statelen(drbg);
+        struct drbg_string data;
+        unsigned char prefix = DRBG_PREFIX1;
+
+        memset(src, 0, drbg_statelen(drbg));
+        memset(dst, 0, drbg_blocklen(drbg));
+
+        /* 10.1.1.4 step hashgen 2 */
+        memcpy(src, drbg->V, drbg_statelen(drbg));
+
+        drbg_string_fill(&data, src, drbg_statelen(drbg));
+        while (len < buflen) {
+                unsigned int outlen = 0;
+                /* 10.1.1.4 step hashgen 4.1 */
+                ret = drbg_kcapi_hash(drbg, NULL, dst, &data);
+                if (ret) {
+                        len = ret;
+                        goto out;
+                }
+                outlen = (drbg_blocklen(drbg) < (buflen - len)) ?
+                          drbg_blocklen(drbg) : (buflen - len);
+                if (!drbg_fips_continuous_test(drbg, dst)) {
+                        drbg_add_buf(src, drbg_statelen(drbg), &prefix, 1);
+                        continue;
+                }
+                /* 10.1.1.4 step hashgen 4.2 */
+                memcpy(buf + len, dst, outlen);
+                len += outlen;
+                /* 10.1.1.4 hashgen step 4.3 */
+                if (len < buflen)
+                        drbg_add_buf(src, drbg_statelen(drbg), &prefix, 1);
+        }
+
+out:
+        memset(drbg->scratchpad, 0,
+               (drbg_statelen(drbg) + drbg_blocklen(drbg)));
+        return len;
+}
+
+/* generate function for Hash DRBG as defined in  10.1.1.4 */
+static int drbg_hash_generate(struct drbg_state *drbg,
+                              unsigned char *buf, unsigned int buflen,
+                              struct drbg_string *addtl)
+{
+        int len = 0;
+        int ret = 0;
+        unsigned char req[8];
+        unsigned char prefix = DRBG_PREFIX3;
+        struct drbg_string data1, data2;
+
+        /* 10.1.1.4 step 2 */
+        ret = drbg_hash_process_addtl(drbg, addtl);
+        if (ret)
+                return ret;
+        /* 10.1.1.4 step 3 */
+        len = drbg_hash_hashgen(drbg, buf, buflen);
+
+        /* this is the value H as documented in 10.1.1.4 */
+        memset(drbg->scratchpad, 0, drbg_blocklen(drbg));
+        /* 10.1.1.4 step 4 */
+        drbg_string_fill(&data1, &prefix, 1);
+        drbg_string_fill(&data2, drbg->V, drbg_statelen(drbg));
+        data1.next = &data2;
+        ret = drbg_kcapi_hash(drbg, NULL, drbg->scratchpad, &data1);
+        if (ret) {
+                len = ret;
+                goto out;
+        }
+
+        /* 10.1.1.4 step 5 */
+        drbg_add_buf(drbg->V, drbg_statelen(drbg),
+                     drbg->scratchpad, drbg_blocklen(drbg));
+        drbg_add_buf(drbg->V, drbg_statelen(drbg),
+                     drbg->C, drbg_statelen(drbg));
+        drbg_int2byte(req, drbg->reseed_ctr, sizeof(req));
+        drbg_add_buf(drbg->V, drbg_statelen(drbg), req, 8);
+
+out:
+        memset(drbg->scratchpad, 0, drbg_blocklen(drbg));
+        return len;
+}
+
+/*
+ * scratchpad usage: as update and generate are used isolated, both
+ * can use the scratchpad
+ */
+static struct drbg_state_ops drbg_hash_ops = {
+        .update         = drbg_hash_update,
+        .generate       = drbg_hash_generate,
+        .crypto_init    = drbg_init_hash_kernel,
+        .crypto_fini    = drbg_fini_hash_kernel,
+};
+#endif /* CONFIG_CRYPTO_DRBG_HASH */
+
+/******************************************************************
+ * Functions common for DRBG implementations
+ ******************************************************************/
+
+/*
+ * Seeding or reseeding of the DRBG
+ *
+ * @drbg: DRBG state struct
+ * @pers: personalization / additional information buffer
+ * @reseed: 0 for initial seed process, 1 for reseeding
+ *
+ * return:
+ *      0 on success
+ *      error value otherwise
+ */
+static int drbg_seed(struct drbg_state *drbg, struct drbg_string *pers,
+                     bool reseed)
+{
+        int ret = 0;
+        unsigned char *entropy = NULL;
+        size_t entropylen = 0;
+        struct drbg_string data1;
+
+        /* 9.1 / 9.2 / 9.3.1 step 3 */
+        if (pers && pers->len > (drbg_max_addtl(drbg))) {
+                pr_devel("DRBG: personalization string too long %lu\n",
+                         pers->len);
+                return -EINVAL;
+        }
+
+        if (drbg->test_data && drbg->test_data->testentropy) {
+                drbg_string_fill(&data1, drbg->test_data->testentropy->buf,
+                                 drbg->test_data->testentropy->len);
+                pr_devel("DRBG: using test entropy\n");
+        } else {
+                /*
+                 * Gather entropy equal to the security strength of the DRBG.
+                 * With a derivation function, a nonce is required in addition
+                 * to the entropy. A nonce must be at least 1/2 of the security
+                 * strength of the DRBG in size. Thus, entropy * nonce is 3/2
+                 * of the strength. The consideration of a nonce is only
+                 * applicable during initial seeding.
+                 */
+                entropylen = drbg_sec_strength(drbg->core->flags);
+                if (!entropylen)
+                        return -EFAULT;
+                if (!reseed)
+                        entropylen = ((entropylen + 1) / 2) * 3;
+                pr_devel("DRBG: (re)seeding with %zu bytes of entropy\n",
+                         entropylen);
+                entropy = kzalloc(entropylen, GFP_KERNEL);
+                if (!entropy)
+                        return -ENOMEM;
+                get_random_bytes(entropy, entropylen);
+                drbg_string_fill(&data1, entropy, entropylen);
+        }
+
+        /*
+         * concatenation of entropy with personalization str / addtl input)
+         * the variable pers is directly handed in by the caller, so check its
+         * contents whether it is appropriate
+         */
+        if (pers && pers->buf && 0 < pers->len && NULL == pers->next) {
+                data1.next = pers;
+                pr_devel("DRBG: using personalization string\n");
+        }
+
+        ret = drbg->d_ops->update(drbg, &data1, reseed);
+        if (ret)
+                goto out;
+
+        drbg->seeded = true;
+        /* 10.1.1.2 / 10.1.1.3 step 5 */
+        drbg->reseed_ctr = 1;
+
+out:
+        if (entropy)
+                kzfree(entropy);
+        return ret;
+}
+
+/* Free all substructures in a DRBG state without the DRBG state structure */
+static inline void drbg_dealloc_state(struct drbg_state *drbg)
+{
+        if (!drbg)
+                return;
+        if (drbg->V)
+                kzfree(drbg->V);
+        drbg->V = NULL;
+        if (drbg->C)
+                kzfree(drbg->C);
+        drbg->C = NULL;
+        if (drbg->scratchpad)
+                kzfree(drbg->scratchpad);
+        drbg->scratchpad = NULL;
+        drbg->reseed_ctr = 0;
+#ifdef CONFIG_CRYPTO_FIPS
+        if (drbg->prev)
+                kzfree(drbg->prev);
+        drbg->prev = NULL;
+        drbg->fips_primed = false;
+#endif
+}
+
+/*
+ * Allocate all sub-structures for a DRBG state.
+ * The DRBG state structure must already be allocated.
+ */
+static inline int drbg_alloc_state(struct drbg_state *drbg)
+{
+        int ret = -ENOMEM;
+        unsigned int sb_size = 0;
+
+        if (!drbg)
+                return -EINVAL;
+
+        drbg->V = kzalloc(drbg_statelen(drbg), GFP_KERNEL);
+        if (!drbg->V)
+                goto err;
+        drbg->C = kzalloc(drbg_statelen(drbg), GFP_KERNEL);
+        if (!drbg->C)
+                goto err;
+#ifdef CONFIG_CRYPTO_FIPS
+        drbg->prev = kzalloc(drbg_blocklen(drbg), GFP_KERNEL);
+        if (!drbg->prev)
+                goto err;
+        drbg->fips_primed = false;
+#endif
+        /* scratchpad is only generated for CTR and Hash */
+        if (drbg->core->flags & DRBG_HMAC)
+                sb_size = 0;
+        else if (drbg->core->flags & DRBG_CTR)
+                sb_size = drbg_statelen(drbg) + drbg_blocklen(drbg) + /* temp */
+                          drbg_statelen(drbg) + /* df_data */
+                          drbg_blocklen(drbg) + /* pad */
+                          drbg_blocklen(drbg) + /* iv */
+                          drbg_statelen(drbg);  /* temp */
+        else
+                sb_size = drbg_statelen(drbg) + drbg_blocklen(drbg);
+
+        if (0 < sb_size) {
+                drbg->scratchpad = kzalloc(sb_size, GFP_KERNEL);
+                if (!drbg->scratchpad)
+                        goto err;
+        }
+        spin_lock_init(&drbg->drbg_lock);
+        return 0;
+
+err:
+        drbg_dealloc_state(drbg);
+        return ret;
+}
+
+/*
+ * Strategy to avoid holding long term locks: generate a shadow copy of DRBG
+ * and perform all operations on this shadow copy. After finishing, restore
+ * the updated state of the shadow copy into original drbg state. This way,
+ * only the read and write operations of the original drbg state must be
+ * locked
+ */
+static inline void drbg_copy_drbg(struct drbg_state *src,
+                                  struct drbg_state *dst)
+{
+        if (!src || !dst)
+                return;
+        memcpy(dst->V, src->V, drbg_statelen(src));
+        memcpy(dst->C, src->C, drbg_statelen(src));
+        dst->reseed_ctr = src->reseed_ctr;
+        dst->seeded = src->seeded;
+        dst->pr = src->pr;
+#ifdef CONFIG_CRYPTO_FIPS
+        dst->fips_primed = src->fips_primed;
+        memcpy(dst->prev, src->prev, drbg_blocklen(src));
+#endif
+        /*
+         * Not copied:
+         * scratchpad is initialized drbg_alloc_state;
+         * priv_data is initialized with call to crypto_init;
+         * d_ops and core are set outside, as these parameters are const;
+         * test_data is set outside to prevent it being copied back.
+         */
+}
+
+static int drbg_make_shadow(struct drbg_state *drbg, struct drbg_state **shadow)
+{
+        int ret = -ENOMEM;
+        struct drbg_state *tmp = NULL;
+
+        if (!drbg || !drbg->core || !drbg->V || !drbg->C) {
+                pr_devel("DRBG: attempt to generate shadow copy for "
+                         "uninitialized DRBG state rejected\n");
+                return -EINVAL;
+        }
+        /* HMAC does not have a scratchpad */
+        if (!(drbg->core->flags & DRBG_HMAC) && NULL == drbg->scratchpad)
+                return -EINVAL;
+
+        tmp = kzalloc(sizeof(struct drbg_state), GFP_KERNEL);
+        if (!tmp)
+                return -ENOMEM;
+
+        /* read-only data as they are defined as const, no lock needed */
+        tmp->core = drbg->core;
+        tmp->d_ops = drbg->d_ops;
+
+        ret = drbg_alloc_state(tmp);
+        if (ret)
+                goto err;
+
+        spin_lock_bh(&drbg->drbg_lock);
+        drbg_copy_drbg(drbg, tmp);
+        /* only make a link to the test buffer, as we only read that data */
+        tmp->test_data = drbg->test_data;
+        spin_unlock_bh(&drbg->drbg_lock);
+        *shadow = tmp;
+        return 0;
+
+err:
+        if (tmp)
+                kzfree(tmp);
+        return ret;
+}
+
+static void drbg_restore_shadow(struct drbg_state *drbg,
+                                struct drbg_state **shadow)
+{
+        struct drbg_state *tmp = *shadow;
+
+        spin_lock_bh(&drbg->drbg_lock);
+        drbg_copy_drbg(tmp, drbg);
+        spin_unlock_bh(&drbg->drbg_lock);
+        drbg_dealloc_state(tmp);
+        kzfree(tmp);
+        *shadow = NULL;
+}
+
+/*************************************************************************
+ * DRBG interface functions
+ *************************************************************************/
+
+/*
+ * DRBG generate function as required by SP800-90A - this function
+ * generates random numbers
+ *
+ * @drbg DRBG state handle
+ * @buf Buffer where to store the random numbers -- the buffer must already
+ *      be pre-allocated by caller
+ * @buflen Length of output buffer - this value defines the number of random
+ *         bytes pulled from DRBG
+ * @addtl Additional input that is mixed into state, may be NULL -- note
+ *        the entropy is pulled by the DRBG internally unconditionally
+ *        as defined in SP800-90A. The additional input is mixed into
+ *        the state in addition to the pulled entropy.
+ *
+ * return: generated number of bytes
+ */
+static int drbg_generate(struct drbg_state *drbg,
+                         unsigned char *buf, unsigned int buflen,
+                         struct drbg_string *addtl)
+{
+        int len = 0;
+        struct drbg_state *shadow = NULL;
+
+        if (0 == buflen || !buf) {
+                pr_devel("DRBG: no output buffer provided\n");
+                return -EINVAL;
+        }
+        if (addtl && NULL == addtl->buf && 0 < addtl->len) {
+                pr_devel("DRBG: wrong format of additional information\n");
+                return -EINVAL;
+        }
+
+        len = drbg_make_shadow(drbg, &shadow);
+        if (len) {
+                pr_devel("DRBG: shadow copy cannot be generated\n");
+                return len;
+        }
+
+        /* 9.3.1 step 2 */
+        len = -EINVAL;
+        if (buflen > (drbg_max_request_bytes(shadow))) {
+                pr_devel("DRBG: requested random numbers too large %u\n",
+                         buflen);
+                goto err;
+        }
+
+        /* 9.3.1 step 3 is implicit with the chosen DRBG */
+
+        /* 9.3.1 step 4 */
+        if (addtl && addtl->len > (drbg_max_addtl(shadow))) {
+                pr_devel("DRBG: additional information string too long %zu\n",
+                         addtl->len);
+                goto err;
+        }
+        /* 9.3.1 step 5 is implicit with the chosen DRBG */
+
+        /*
+         * 9.3.1 step 6 and 9 supplemented by 9.3.2 step c is implemented
+         * here. The spec is a bit convoluted here, we make it simpler.
+         */
+        if ((drbg_max_requests(shadow)) < shadow->reseed_ctr)
+                shadow->seeded = false;
+
+        /* allocate cipher handle */
+        if (shadow->d_ops->crypto_init) {
+                len = shadow->d_ops->crypto_init(shadow);
+                if (len)
+                        goto err;
+        }
+
+        if (shadow->pr || !shadow->seeded) {
+                pr_devel("DRBG: reseeding before generation (prediction "
+                         "resistance: %s, state %s)\n",
+                         drbg->pr ? "true" : "false",
+                         drbg->seeded ? "seeded" : "unseeded");
+                /* 9.3.1 steps 7.1 through 7.3 */
+                len = drbg_seed(shadow, addtl, true);
+                if (len)
+                        goto err;
+                /* 9.3.1 step 7.4 */
+                addtl = NULL;
+        }
+        /* 9.3.1 step 8 and 10 */
+        len = shadow->d_ops->generate(shadow, buf, buflen, addtl);
+
+        /* 10.1.1.4 step 6, 10.1.2.5 step 7, 10.2.1.5.2 step 7 */
+        shadow->reseed_ctr++;
+        if (0 >= len)
+                goto err;
+
+        /*
+         * Section 11.3.3 requires to re-perform self tests after some
+         * generated random numbers. The chosen value after which self
+         * test is performed is arbitrary, but it should be reasonable.
+         * However, we do not perform the self tests because of the following
+         * reasons: it is mathematically impossible that the initial self tests
+         * were successfully and the following are not. If the initial would
+         * pass and the following would not, the kernel integrity is violated.
+         * In this case, the entire kernel operation is questionable and it
+         * is unlikely that the integrity violation only affects the
+         * correct operation of the DRBG.
+         *
+         * Albeit the following code is commented out, it is provided in
+         * case somebody has a need to implement the test of 11.3.3.
+         */
+#if 0
+        if (shadow->reseed_ctr && !(shadow->reseed_ctr % 4096)) {
+                int err = 0;
+                pr_devel("DRBG: start to perform self test\n");
+                if (drbg->core->flags & DRBG_HMAC)
+                        err = alg_test("drbg_pr_hmac_sha256",
+                                       "drbg_pr_hmac_sha256", 0, 0);
+                else if (drbg->core->flags & DRBG_CTR)
+                        err = alg_test("drbg_pr_ctr_aes128",
+                                       "drbg_pr_ctr_aes128", 0, 0);
+                else
+                        err = alg_test("drbg_pr_sha256",
+                                       "drbg_pr_sha256", 0, 0);
+                if (err) {
+                        pr_err("DRBG: periodical self test failed\n");
+                        /*
+                         * uninstantiate implies that from now on, only errors
+                         * are returned when reusing this DRBG cipher handle
+                         */
+                        drbg_uninstantiate(drbg);
+                        drbg_dealloc_state(shadow);
+                        kzfree(shadow);
+                        return 0;
+                } else {
+                        pr_devel("DRBG: self test successful\n");
+                }
+        }
+#endif
+
+err:
+        if (shadow->d_ops->crypto_fini)
+                shadow->d_ops->crypto_fini(shadow);
+        drbg_restore_shadow(drbg, &shadow);
+        return len;
+}
+
+/*
+ * Wrapper around drbg_generate which can pull arbitrary long strings
+ * from the DRBG without hitting the maximum request limitation.
+ *
+ * Parameters: see drbg_generate
+ * Return codes: see drbg_generate -- if one drbg_generate request fails,
+ *               the entire drbg_generate_long request fails
+ */
+static int drbg_generate_long(struct drbg_state *drbg,
+                              unsigned char *buf, unsigned int buflen,
+                              struct drbg_string *addtl)
+{
+        int len = 0;
+        unsigned int slice = 0;
+        do {
+                int tmplen = 0;
+                unsigned int chunk = 0;
+                slice = ((buflen - len) / drbg_max_request_bytes(drbg));
+                chunk = slice ? drbg_max_request_bytes(drbg) : (buflen - len);
+                tmplen = drbg_generate(drbg, buf + len, chunk, addtl);
+                if (0 >= tmplen)
+                        return tmplen;
+                len += tmplen;
+        } while (slice > 0);
+        return len;
+}
+
+/*
+ * DRBG instantiation function as required by SP800-90A - this function
+ * sets up the DRBG handle, performs the initial seeding and all sanity
+ * checks required by SP800-90A
+ *
+ * @drbg memory of state -- if NULL, new memory is allocated
+ * @pers Personalization string that is mixed into state, may be NULL -- note
+ *       the entropy is pulled by the DRBG internally unconditionally
+ *       as defined in SP800-90A. The additional input is mixed into
+ *       the state in addition to the pulled entropy.
+ * @coreref reference to core
+ * @pr prediction resistance enabled
+ *
+ * return
+ *      0 on success
+ *      error value otherwise
+ */
+static int drbg_instantiate(struct drbg_state *drbg, struct drbg_string *pers,
+                            int coreref, bool pr)
+{
+        int ret = -ENOMEM;
+
+        pr_devel("DRBG: Initializing DRBG core %d with prediction resistance "
+                 "%s\n", coreref, pr ? "enabled" : "disabled");
+        drbg->core = &drbg_cores[coreref];
+        drbg->pr = pr;
+        drbg->seeded = false;
+        switch (drbg->core->flags & DRBG_TYPE_MASK) {
+#ifdef CONFIG_CRYPTO_DRBG_HMAC
+        case DRBG_HMAC:
+                drbg->d_ops = &drbg_hmac_ops;
+                break;
+#endif /* CONFIG_CRYPTO_DRBG_HMAC */
+#ifdef CONFIG_CRYPTO_DRBG_HASH
+        case DRBG_HASH:
+                drbg->d_ops = &drbg_hash_ops;
+                break;
+#endif /* CONFIG_CRYPTO_DRBG_HASH */
+#ifdef CONFIG_CRYPTO_DRBG_CTR
+        case DRBG_CTR:
+                drbg->d_ops = &drbg_ctr_ops;
+                break;
+#endif /* CONFIG_CRYPTO_DRBG_CTR */
+        default:
+                return -EOPNOTSUPP;
+        }
+
+        /* 9.1 step 1 is implicit with the selected DRBG type */
+
+        /*
+         * 9.1 step 2 is implicit as caller can select prediction resistance
+         * and the flag is copied into drbg->flags --
+         * all DRBG types support prediction resistance
+         */
+
+        /* 9.1 step 4 is implicit in  drbg_sec_strength */
+
+        ret = drbg_alloc_state(drbg);
+        if (ret)
+                return ret;
+
+        ret = -EFAULT;
+        if (drbg->d_ops->crypto_init && drbg->d_ops->crypto_init(drbg))
+                goto err;
+        ret = drbg_seed(drbg, pers, false);
+        if (drbg->d_ops->crypto_fini)
+                drbg->d_ops->crypto_fini(drbg);
+        if (ret)
+                goto err;
+
+        return 0;
+
+err:
+        drbg_dealloc_state(drbg);
+        return ret;
+}
+
+/*
+ * DRBG uninstantiate function as required by SP800-90A - this function
+ * frees all buffers and the DRBG handle
+ *
+ * @drbg DRBG state handle
+ *
+ * return
+ *      0 on success
+ */
+static int drbg_uninstantiate(struct drbg_state *drbg)
+{
+        spin_lock_bh(&drbg->drbg_lock);
+        drbg_dealloc_state(drbg);
+        /* no scrubbing of test_data -- this shall survive an uninstantiate */
+        spin_unlock_bh(&drbg->drbg_lock);
+        return 0;
+}
+
+/*
+ * Helper function for setting the test data in the DRBG
+ *
+ * @drbg DRBG state handle
+ * @test_data test data to sets
+ */
+static inline void drbg_set_testdata(struct drbg_state *drbg,
+                                     struct drbg_test_data *test_data)
+{
+        if (!test_data || !test_data->testentropy)
+                return;
+        spin_lock_bh(&drbg->drbg_lock);
+        drbg->test_data = test_data;
+        spin_unlock_bh(&drbg->drbg_lock);
+}
+
+/***************************************************************
+ * Kernel crypto API cipher invocations requested by DRBG
+ ***************************************************************/
+
+#if defined(CONFIG_CRYPTO_DRBG_HASH) || defined(CONFIG_CRYPTO_DRBG_HMAC)
+struct sdesc {
+        struct shash_desc shash;
+        char ctx[];
+};
+
+static int drbg_init_hash_kernel(struct drbg_state *drbg)
+{
+        struct sdesc *sdesc;
+        struct crypto_shash *tfm;
+
+        tfm = crypto_alloc_shash(drbg->core->backend_cra_name, 0, 0);
+        if (IS_ERR(tfm)) {
+                pr_info("DRBG: could not allocate digest TFM handle\n");
+                return PTR_ERR(tfm);
+        }
+        BUG_ON(drbg_blocklen(drbg) != crypto_shash_digestsize(tfm));
+        sdesc = kzalloc(sizeof(struct shash_desc) + crypto_shash_descsize(tfm),
+                        GFP_KERNEL);
+        if (!sdesc) {
+                crypto_free_shash(tfm);
+                return -ENOMEM;
+        }
+
+        sdesc->shash.tfm = tfm;
+        sdesc->shash.flags = 0;
+        drbg->priv_data = sdesc;
+        return 0;
+}
+
+static int drbg_fini_hash_kernel(struct drbg_state *drbg)
+{
+        struct sdesc *sdesc = (struct sdesc *)drbg->priv_data;
+        if (sdesc) {
+                crypto_free_shash(sdesc->shash.tfm);
+                kzfree(sdesc);
+        }
+        drbg->priv_data = NULL;
+        return 0;
+}
+
+static int drbg_kcapi_hash(struct drbg_state *drbg, const unsigned char *key,
+                           unsigned char *outval, const struct drbg_string *in)
+{
+        struct sdesc *sdesc = (struct sdesc *)drbg->priv_data;
+
+        if (key)
+                crypto_shash_setkey(sdesc->shash.tfm, key, drbg_statelen(drbg));
+        crypto_shash_init(&sdesc->shash);
+        for (; NULL != in; in = in->next)
+                crypto_shash_update(&sdesc->shash, in->buf, in->len);
+        return crypto_shash_final(&sdesc->shash, outval);
+}
+#endif /* (CONFIG_CRYPTO_DRBG_HASH || CONFIG_CRYPTO_DRBG_HMAC) */
+
+#ifdef CONFIG_CRYPTO_DRBG_CTR
+static int drbg_init_sym_kernel(struct drbg_state *drbg)
+{
+        int ret = 0;
+        struct crypto_blkcipher *tfm;
+
+        tfm = crypto_alloc_blkcipher(drbg->core->backend_cra_name, 0, 0);
+        if (IS_ERR(tfm)) {
+                pr_info("DRBG: could not allocate cipher TFM handle\n");
+                return PTR_ERR(tfm);
+        }
+        BUG_ON(drbg_blocklen(drbg) != crypto_blkcipher_blocksize(tfm));
+        drbg->priv_data = tfm;
+        return ret;
+}
+
+static int drbg_fini_sym_kernel(struct drbg_state *drbg)
+{
+        struct crypto_blkcipher *tfm =
+                (struct crypto_blkcipher *)drbg->priv_data;
+        if (tfm)
+                crypto_free_blkcipher(tfm);
+        drbg->priv_data = NULL;
+        return 0;
+}
+
+static int drbg_kcapi_sym(struct drbg_state *drbg, const unsigned char *key,
+                          unsigned char *outval, const struct drbg_string *in)
+{
+        int ret = 0;
+        struct scatterlist sg_in, sg_out;
+        struct blkcipher_desc desc;
+        struct crypto_blkcipher *tfm =
+                (struct crypto_blkcipher *)drbg->priv_data;
+
+        desc.tfm = tfm;
+        desc.flags = 0;
+        crypto_blkcipher_setkey(tfm, key, (drbg_keylen(drbg)));
+        /* there is only component in *in */
+        sg_init_one(&sg_in, in->buf, in->len);
+        sg_init_one(&sg_out, outval, drbg_blocklen(drbg));
+        ret = crypto_blkcipher_encrypt(&desc, &sg_out, &sg_in, in->len);
+
+        return ret;
+}
+#endif /* CONFIG_CRYPTO_DRBG_CTR */
+
+/***************************************************************
+ * Kernel crypto API interface to register DRBG
+ ***************************************************************/
+
+/*
+ * Look up the DRBG flags by given kernel crypto API cra_name
+ * The code uses the drbg_cores definition to do this
+ *
+ * @cra_name kernel crypto API cra_name
+ * @coreref reference to integer which is filled with the pointer to
+ *  the applicable core
+ * @pr reference for setting prediction resistance
+ *
+ * return: flags
+ */
+static inline void drbg_convert_tfm_core(const char *cra_driver_name,
+                                         int *coreref, bool *pr)
+{
+        int i = 0;
+        size_t start = 0;
+        int len = 0;
+
+        *pr = true;
+        /* disassemble the names */
+        if (!memcmp(cra_driver_name, "drbg_nopr_", 10)) {
+                start = 10;
+                *pr = false;
+        } else if (!memcmp(cra_driver_name, "drbg_pr_", 8)) {
+                start = 8;
+        } else {
+                return;
+        }
+
+        /* remove the first part */
+        len = strlen(cra_driver_name) - start;
+        for (i = 0; ARRAY_SIZE(drbg_cores) > i; i++) {
+                if (!memcmp(cra_driver_name + start, drbg_cores[i].cra_name,
+                            len)) {
+                        *coreref = i;
+                        return;
+                }
+        }
+}
+
+static int drbg_kcapi_init(struct crypto_tfm *tfm)
+{
+        struct drbg_state *drbg = crypto_tfm_ctx(tfm);
+        bool pr = false;
+        int coreref = 0;
+
+        drbg_convert_tfm_core(crypto_tfm_alg_name(tfm), &coreref, &pr);
+        /*
+         * when personalization string is needed, the caller must call reset
+         * and provide the personalization string as seed information
+         */
+        return drbg_instantiate(drbg, NULL, coreref, pr);
+}
+
+static void drbg_kcapi_cleanup(struct crypto_tfm *tfm)
+{
+        drbg_uninstantiate(crypto_tfm_ctx(tfm));
+}
+
+/*
+ * Generate random numbers invoked by the kernel crypto API:
+ * The API of the kernel crypto API is extended as follows:
+ *
+ * If dlen is larger than zero, rdata is interpreted as the output buffer
+ * where random data is to be stored.
+ *
+ * If dlen is zero, rdata is interpreted as a pointer to a struct drbg_gen
+ * which holds the additional information string that is used for the
+ * DRBG generation process. The output buffer that is to be used to store
+ * data is also pointed to by struct drbg_gen.
+ */
+static int drbg_kcapi_random(struct crypto_rng *tfm, u8 *rdata,
+                             unsigned int dlen)
+{
+        struct drbg_state *drbg = crypto_rng_ctx(tfm);
+        if (0 < dlen) {
+                return drbg_generate_long(drbg, rdata, dlen, NULL);
+        } else {
+                struct drbg_gen *data = (struct drbg_gen *)rdata;
+                /* catch NULL pointer */
+                if (!data)
+                        return 0;
+                drbg_set_testdata(drbg, data->test_data);
+                return drbg_generate_long(drbg, data->outbuf, data->outlen,
+                                          data->addtl);
+        }
+}
+
+/*
+ * Reset the DRBG invoked by the kernel crypto API
+ * The reset implies a full re-initialization of the DRBG. Similar to the
+ * generate function of drbg_kcapi_random, this function extends the
+ * kernel crypto API interface with struct drbg_gen
+ */
+static int drbg_kcapi_reset(struct crypto_rng *tfm, u8 *seed, unsigned int slen)
+{
+        struct drbg_state *drbg = crypto_rng_ctx(tfm);
+        struct crypto_tfm *tfm_base = crypto_rng_tfm(tfm);
+        bool pr = false;
+        struct drbg_string seed_string;
+        int coreref = 0;
+
+        drbg_uninstantiate(drbg);
+        drbg_convert_tfm_core(crypto_tfm_alg_driver_name(tfm_base), &coreref,
+                              &pr);
+        if (0 < slen) {
+                drbg_string_fill(&seed_string, seed, slen);
+                return drbg_instantiate(drbg, &seed_string, coreref, pr);
+        } else {
+                struct drbg_gen *data = (struct drbg_gen *)seed;
+                /* allow invocation of API call with NULL, 0 */
+                if (!data)
+                        return drbg_instantiate(drbg, NULL, coreref, pr);
+                drbg_set_testdata(drbg, data->test_data);
+                return drbg_instantiate(drbg, data->addtl, coreref, pr);
+        }
+}
+
+/***************************************************************
+ * Kernel module: code to load the module
+ ***************************************************************/
+
+/*
+ * Tests as defined in 11.3.2 in addition to the cipher tests: testing
+ * of the error handling.
+ *
+ * Note: testing of failing seed source as defined in 11.3.2 is not applicable
+ * as seed source of get_random_bytes does not fail.
+ *
+ * Note 2: There is no sensible way of testing the reseed counter
+ * enforcement, so skip it.
+ */
+static inline int __init drbg_healthcheck_sanity(void)
+{
+#ifdef CONFIG_CRYPTO_FIPS
+        int len = 0;
+#define OUTBUFLEN 16
+        unsigned char buf[OUTBUFLEN];
+        struct drbg_state *drbg = NULL;
+        int ret = -EFAULT;
+        int rc = -EFAULT;
+        bool pr = false;
+        int coreref = 0;
+        struct drbg_string addtl;
+        size_t max_addtllen, max_request_bytes;
+
+        /* only perform test in FIPS mode */
+        if (!fips_enabled)
+                return 0;
+
+#ifdef CONFIG_CRYPTO_DRBG_CTR
+        drbg_convert_tfm_core("drbg_nopr_ctr_aes128", &coreref, &pr);
+#elif CONFIG_CRYPTO_DRBG_HASH
+        drbg_convert_tfm_core("drbg_nopr_sha256", &coreref, &pr);
+#else
+        drbg_convert_tfm_core("drbg_nopr_hmac_sha256", &coreref, &pr);
+#endif
+
+        drbg = kzalloc(sizeof(struct drbg_state), GFP_KERNEL);
+        if (!drbg)
+                return -ENOMEM;
+
+        /*
+         * if the following tests fail, it is likely that there is a buffer
+         * overflow as buf is much smaller than the requested or provided
+         * string lengths -- in case the error handling does not succeed
+         * we may get an OOPS. And we want to get an OOPS as this is a
+         * grave bug.
+         */
+
+        /* get a valid instance of DRBG for following tests */
+        ret = drbg_instantiate(drbg, NULL, coreref, pr);
+        if (ret) {
+                rc = ret;
+                goto outbuf;
+        }
+        max_addtllen = drbg_max_addtl(drbg);
+        max_request_bytes = drbg_max_request_bytes(drbg);
+        drbg_string_fill(&addtl, buf, max_addtllen + 1);
+        /* overflow addtllen with additonal info string */
+        len = drbg_generate(drbg, buf, OUTBUFLEN, &addtl);
+        BUG_ON(0 < len);
+        /* overflow max_bits */
+        len = drbg_generate(drbg, buf, (max_request_bytes + 1), NULL);
+        BUG_ON(0 < len);
+        drbg_uninstantiate(drbg);
+
+        /* overflow max addtllen with personalization string */
+        ret = drbg_instantiate(drbg, &addtl, coreref, pr);
+        BUG_ON(0 == ret);
+        /* test uninstantated DRBG */
+        len = drbg_generate(drbg, buf, (max_request_bytes + 1), NULL);
+        BUG_ON(0 < len);
+        /* all tests passed */
+        rc = 0;
+
+        pr_devel("DRBG: Sanity tests for failure code paths successfully "
+                 "completed\n");
+
+        drbg_uninstantiate(drbg);
+outbuf:
+        kzfree(drbg);
+        return rc;
+#else /* CONFIG_CRYPTO_FIPS */
+        return 0;
+#endif /* CONFIG_CRYPTO_FIPS */
+}
+
+static struct crypto_alg drbg_algs[22];
+
+/*
+ * Fill the array drbg_algs used to register the different DRBGs
+ * with the kernel crypto API. To fill the array, the information
+ * from drbg_cores[] is used.
+ */
+static inline void __init drbg_fill_array(struct crypto_alg *alg,
+                                          const struct drbg_core *core, int pr)
+{
+        int pos = 0;
+        static int priority = 100;
+
+        memset(alg, 0, sizeof(struct crypto_alg));
+        memcpy(alg->cra_name, "stdrng", 6);
+        if (pr) {
+                memcpy(alg->cra_driver_name, "drbg_pr_", 8);
+                pos = 8;
+        } else {
+                memcpy(alg->cra_driver_name, "drbg_nopr_", 10);
+                pos = 10;
+        }
+        memcpy(alg->cra_driver_name + pos, core->cra_name,
+               strlen(core->cra_name));
+
+        alg->cra_priority = priority;
+        priority++;
+        /*
+         * If FIPS mode enabled, the selected DRBG shall have the
+         * highest cra_priority over other stdrng instances to ensure
+         * it is selected.
+         */
+        if (fips_enabled)
+                alg->cra_priority += 200;
+
+        alg->cra_flags          = CRYPTO_ALG_TYPE_RNG;
+        alg->cra_ctxsize        = sizeof(struct drbg_state);
+        alg->cra_type           = &crypto_rng_type;
+        alg->cra_module         = THIS_MODULE;
+        alg->cra_init           = drbg_kcapi_init;
+        alg->cra_exit           = drbg_kcapi_cleanup;
+        alg->cra_u.rng.rng_make_random  = drbg_kcapi_random;
+        alg->cra_u.rng.rng_reset        = drbg_kcapi_reset;
+        alg->cra_u.rng.seedsize = 0;
+}
+
+static int __init drbg_init(void)
+{
+        unsigned int i = 0; /* pointer to drbg_algs */
+        unsigned int j = 0; /* pointer to drbg_cores */
+        int ret = -EFAULT;
+
+        ret = drbg_healthcheck_sanity();
+        if (ret)
+                return ret;
+
+        if (ARRAY_SIZE(drbg_cores) * 2 > ARRAY_SIZE(drbg_algs)) {
+                pr_info("DRBG: Cannot register all DRBG types"
+                        "(slots needed: %lu, slots available: %lu)\n",
+                        ARRAY_SIZE(drbg_cores) * 2, ARRAY_SIZE(drbg_algs));
+                return ret;
+        }
+
+        /*
+         * each DRBG definition can be used with PR and without PR, thus
+         * we instantiate each DRBG in drbg_cores[] twice.
+         *
+         * As the order of placing them into the drbg_algs array matters
+         * (the later DRBGs receive a higher cra_priority) we register the
+         * prediction resistance DRBGs first as the should not be too
+         * interesting.
+         */
+        for (j = 0; ARRAY_SIZE(drbg_cores) > j; j++, i++)
+                drbg_fill_array(&drbg_algs[i], &drbg_cores[j], 1);
+        for (j = 0; ARRAY_SIZE(drbg_cores) > j; j++, i++)
+                drbg_fill_array(&drbg_algs[i], &drbg_cores[j], 0);
+        return crypto_register_algs(drbg_algs, (ARRAY_SIZE(drbg_cores) * 2));
+}
+
+void __exit drbg_exit(void)
+{
+        crypto_unregister_algs(drbg_algs, (ARRAY_SIZE(drbg_cores) * 2));
+}
+
+module_init(drbg_init);
+module_exit(drbg_exit);
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Stephan Mueller <smueller@chronox.de>");
+MODULE_DESCRIPTION("NIST SP800-90A Deterministic Random Bit Generator (DRBG) using following cores:"
+#ifdef CONFIG_CRYPTO_DRBG_HMAC
+"HMAC "
+#endif
+#ifdef CONFIG_CRYPTO_DRBG_HASH
+"Hash "
+#endif
+#ifdef CONFIG_CRYPTO_DRBG_CTR
+"CTR"
+#endif
+);