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 /*
  * 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>
 #include <crypto/internal/cipher.h>
 #include <linux/kernel.h>
 #include <linux/jiffies.h>
 
 /***************************************************************
  * 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 */
         .blocklen_bytes = 16,
         .cra_name = "ctr_aes128",
         .backend_cra_name = "aes",
     }, {
         .flags = DRBG_CTR | DRBG_STRENGTH192,
         .statelen = 40, /* 320 bits as defined in 10.2.1 */
         .blocklen_bytes = 16,
         .cra_name = "ctr_aes192",
         .backend_cra_name = "aes",
     }, {
         .flags = DRBG_CTR | DRBG_STRENGTH256,
         .statelen = 48, /* 384 bits as defined in 10.2.1 */
         .blocklen_bytes = 16,
         .cra_name = "ctr_aes256",
         .backend_cra_name = "aes",
     },
 #endif /* CONFIG_CRYPTO_DRBG_CTR */
 #ifdef CONFIG_CRYPTO_DRBG_HASH
     {
         .flags = DRBG_HASH | DRBG_STRENGTH128,
         .statelen = 55, /* 440 bits */
         .blocklen_bytes = 20,
         .cra_name = "sha1",
         .backend_cra_name = "sha1",
     }, {
         .flags = DRBG_HASH | DRBG_STRENGTH256,
         .statelen = 111, /* 888 bits */
         .blocklen_bytes = 48,
         .cra_name = "sha384",
         .backend_cra_name = "sha384",
     }, {
         .flags = DRBG_HASH | DRBG_STRENGTH256,
         .statelen = 111, /* 888 bits */
         .blocklen_bytes = 64,
         .cra_name = "sha512",
         .backend_cra_name = "sha512",
     }, {
         .flags = DRBG_HASH | DRBG_STRENGTH256,
         .statelen = 55, /* 440 bits */
         .blocklen_bytes = 32,
         .cra_name = "sha256",
         .backend_cra_name = "sha256",
     },
 #endif /* CONFIG_CRYPTO_DRBG_HASH */
 #ifdef CONFIG_CRYPTO_DRBG_HMAC
     {
         .flags = DRBG_HMAC | DRBG_STRENGTH128,
         .statelen = 20, /* block length of cipher */
         .blocklen_bytes = 20,
         .cra_name = "hmac_sha1",
         .backend_cra_name = "hmac(sha1)",
     }, {
         .flags = DRBG_HMAC | DRBG_STRENGTH256,
         .statelen = 48, /* block length of cipher */
         .blocklen_bytes = 48,
         .cra_name = "hmac_sha384",
         .backend_cra_name = "hmac(sha384)",
     }, {
         .flags = DRBG_HMAC | DRBG_STRENGTH256,
         .statelen = 32, /* block length of cipher */
         .blocklen_bytes = 32,
         .cra_name = "hmac_sha256",
         .backend_cra_name = "hmac(sha256)",
     }, {
         .flags = DRBG_HMAC | DRBG_STRENGTH256,
         .statelen = 64, /* block length of cipher */
         .blocklen_bytes = 64,
         .cra_name = "hmac_sha512",
         .backend_cra_name = "hmac(sha512)",
     },
 #endif /* CONFIG_CRYPTO_DRBG_HMAC */
 };
 
 static int drbg_uninstantiate(struct drbg_state *drbg);
 
 /******************************************************************
  * 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 for the noise source
  * The test is performed on the noise source input data. Thus, the function
  * implicitly knows the size of the buffer to be equal to the security
  * strength.
  *
  * Note, this function disregards the nonce trailing the entropy data during
  * initial seeding.
  *
  * drbg->drbg_mutex must have been taken.
  *
  * @drbg DRBG handle
  * @entropy buffer of seed data to be checked
  *
  * return:
  *  0 on success
  *  -EAGAIN on when the CTRNG is not yet primed
  *  < 0 on error
  */
 static int drbg_fips_continuous_test(struct drbg_state *drbg,
                      const unsigned char *entropy)
 {
     unsigned short entropylen = drbg_sec_strength(drbg->core->flags);
     int ret = 0;
 
     if (!IS_ENABLED(CONFIG_CRYPTO_FIPS))
         return 0;
 
     /* skip test if we test the overall system */
     if (list_empty(&drbg->test_data.list))
         return 0;
     /* only perform test in FIPS mode */
     if (!fips_enabled)
         return 0;
 
     if (!drbg->fips_primed) {
         /* Priming of FIPS test */
         memcpy(drbg->prev, entropy, entropylen);
         drbg->fips_primed = true;
         /* priming: another round is needed */
         return -EAGAIN;
     }
     ret = memcmp(drbg->prev, entropy, entropylen);
     if (!ret)
         panic("DRBG continuous self test failed\n");
     memcpy(drbg->prev, entropy, entropylen);
 
     /* the test shall pass when the two values are not equal */
     return 0;
 }
 
 /*
  * Convert an integer into a byte representation of this integer.
  * The byte representation is big-endian
  *
  * @val value to be converted
  * @buf buffer holding the converted integer -- caller must ensure that
  *      buffer size is at least 32 bit
  */
 #if (defined(CONFIG_CRYPTO_DRBG_HASH) || defined(CONFIG_CRYPTO_DRBG_CTR))
 static inline void drbg_cpu_to_be32(__u32 val, unsigned char *buf)
 {
     struct s {
         __be32 conv;
     };
     struct s *conversion = (struct s *) buf;
 
     conversion->conv = cpu_to_be32(val);
 }
 #endif /* defined(CONFIG_CRYPTO_DRBG_HASH) || defined(CONFIG_CRYPTO_DRBG_CTR) */
 
 /******************************************************************
  * CTR DRBG callback functions
  ******************************************************************/
 
 #ifdef CONFIG_CRYPTO_DRBG_CTR
 #define CRYPTO_DRBG_CTR_STRING "CTR "
 MODULE_ALIAS_CRYPTO("drbg_pr_ctr_aes256");
 MODULE_ALIAS_CRYPTO("drbg_nopr_ctr_aes256");
 MODULE_ALIAS_CRYPTO("drbg_pr_ctr_aes192");
 MODULE_ALIAS_CRYPTO("drbg_nopr_ctr_aes192");
 MODULE_ALIAS_CRYPTO("drbg_pr_ctr_aes128");
 MODULE_ALIAS_CRYPTO("drbg_nopr_ctr_aes128");
 
 static void drbg_kcapi_symsetkey(struct drbg_state *drbg,
                  const unsigned char *key);
 static int drbg_kcapi_sym(struct drbg_state *drbg, 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);
 static int drbg_kcapi_sym_ctr(struct drbg_state *drbg,
                   u8 *inbuf, u32 inbuflen,
                   u8 *outbuf, u32 outlen);
 #define DRBG_OUTSCRATCHLEN 256
 
 /* 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 list_head *in)
 {
     int ret = 0;
     struct drbg_string *curr = NULL;
     struct drbg_string data;
     short cnt = 0;
 
     drbg_string_fill(&data, out, drbg_blocklen(drbg));
 
     /* 10.4.3 step 2 / 4 */
     drbg_kcapi_symsetkey(drbg, key);
     list_for_each_entry(curr, in, list) {
         const unsigned char *pos = curr->buf;
         size_t len = curr->len;
         /* 10.4.3 step 4.1 */
         while (len) {
             /* 10.4.3 step 4.2 */
             if (drbg_blocklen(drbg) == cnt) {
                 cnt = 0;
                 ret = drbg_kcapi_sym(drbg, out, &data);
                 if (ret)
                     return ret;
             }
             out[cnt] ^= *pos;
             pos++;
             cnt++;
             len--;
         }
     }
     /* 10.4.3 step 4.2 for last block */
     if (cnt)
         ret = drbg_kcapi_sym(drbg, out, &data);
 
     return ret;
 }
 
 /*
  * 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_satelen(drbg) + drbg_blocklen(drbg)
  *          note: temp is the buffer that the BCC function operates
  *          on. BCC operates blockwise. drbg_statelen(drbg)
  *          is sufficient when the DRBG state length is a multiple
  *          of the block size. For AES192 (and maybe other ciphers)
  *          this is not correct and the length for temp is
  *          insufficient (yes, that also means for such ciphers,
  *          the final output of all BCC rounds are truncated).
  *          Therefore, add drbg_blocklen(drbg) to cover all
  *          possibilities.
  */
 
 /* 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 list_head *seedlist)
 {
     int ret = -EFAULT;
     unsigned char L_N[8];
     /* S3 is input */
     struct drbg_string S1, S2, S4, cipherin;
     LIST_HEAD(bcc_list);
     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;
     struct drbg_string *seed = NULL;
 
     memset(pad, 0, drbg_blocklen(drbg));
     memset(iv, 0, drbg_blocklen(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 */
     list_for_each_entry(seed, seedlist, list)
         inputlen += seed->len;
     drbg_cpu_to_be32(inputlen, &L_N[0]);
 
     /* 10.4.2 step 3 */
     drbg_cpu_to_be32(bytes_to_return, &L_N[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));
     list_add_tail(&S1.list, &bcc_list);
     drbg_string_fill(&S2, L_N, sizeof(L_N));
     list_add_tail(&S2.list, &bcc_list);
     list_splice_tail(seedlist, &bcc_list);
     drbg_string_fill(&S4, pad, padlen);
     list_add_tail(&S4.list, &bcc_list);
 
     /* 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_cpu_to_be32(i, iv);
         /* 10.4.2 step 9.2 -- BCC and concatenation with temp */
         ret = drbg_ctr_bcc(drbg, temp + templen, K, &bcc_list);
         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 */
     drbg_kcapi_symsetkey(drbg, temp);
     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, 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) + drbg_blocklen(drbg));
     memset(pad, 0, drbg_blocklen(drbg));
     return ret;
 }
 
 /*
  * update function of CTR DRBG as defined in 10.2.1.2
  *
  * The reseed variable has an enhanced meaning compared to the update
  * functions of the other DRBGs as follows:
  * 0 => initial seed from initialization
  * 1 => reseed via drbg_seed
  * 2 => first invocation from drbg_ctr_update when addtl is present. In
  *      this case, the df_data scratchpad is not deleted so that it is
  *      available for another calls to prevent calling the DF function
  *      again.
  * 3 => second invocation from drbg_ctr_update. When the update function
  *      was called with addtl, the df_data memory already contains the
  *      DFed addtl information and we do not need to call DF again.
  */
 static int drbg_ctr_update(struct drbg_state *drbg, struct list_head *seed,
                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);
 
     if (3 > reseed)
         memset(df_data, 0, drbg_statelen(drbg));
 
     if (!reseed) {
         /*
          * The DRBG uses the CTR mode of the underlying AES cipher. The
          * CTR mode increments the counter value after the AES operation
          * but SP800-90A requires that the counter is incremented before
          * the AES operation. Hence, we increment it at the time we set
          * it by one.
          */
         crypto_inc(drbg->V, drbg_blocklen(drbg));
 
         ret = crypto_skcipher_setkey(drbg->ctr_handle, drbg->C,
                          drbg_keylen(drbg));
         if (ret)
             goto out;
     }
 
     /* 10.2.1.3.2 step 2 and 10.2.1.4.2 step 2 */
     if (seed) {
         ret = drbg_ctr_df(drbg, df_data, drbg_statelen(drbg), seed);
         if (ret)
             goto out;
     }
 
     ret = drbg_kcapi_sym_ctr(drbg, df_data, drbg_statelen(drbg),
                  temp, drbg_statelen(drbg));
     if (ret)
         return ret;
 
     /* 10.2.1.2 step 5 */
     ret = crypto_skcipher_setkey(drbg->ctr_handle, temp,
                      drbg_keylen(drbg));
     if (ret)
         goto out;
     /* 10.2.1.2 step 6 */
     memcpy(drbg->V, temp + drbg_keylen(drbg), drbg_blocklen(drbg));
     /* See above: increment counter by one to compensate timing of CTR op */
     crypto_inc(drbg->V, drbg_blocklen(drbg));
     ret = 0;
 
 out:
     memset(temp, 0, drbg_statelen(drbg) + drbg_blocklen(drbg));
     if (2 != reseed)
         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 list_head *addtl)
 {
     int ret;
     int len = min_t(int, buflen, INT_MAX);
 
     /* 10.2.1.5.2 step 2 */
     if (addtl && !list_empty(addtl)) {
         ret = drbg_ctr_update(drbg, addtl, 2);
         if (ret)
             return 0;
     }
 
     /* 10.2.1.5.2 step 4.1 */
     ret = drbg_kcapi_sym_ctr(drbg, NULL, 0, buf, len);
     if (ret)
         return ret;
 
     /* 10.2.1.5.2 step 6 */
     ret = drbg_ctr_update(drbg, NULL, 3);
     if (ret)
         len = ret;
 
     return len;
 }
 
 static const 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, unsigned char *outval,
                const struct list_head *in);
 static void drbg_kcapi_hmacsetkey(struct drbg_state *drbg,
                   const unsigned char *key);
 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
 #define CRYPTO_DRBG_HMAC_STRING "HMAC "
 MODULE_ALIAS_CRYPTO("drbg_pr_hmac_sha512");
 MODULE_ALIAS_CRYPTO("drbg_nopr_hmac_sha512");
 MODULE_ALIAS_CRYPTO("drbg_pr_hmac_sha384");
 MODULE_ALIAS_CRYPTO("drbg_nopr_hmac_sha384");
 MODULE_ALIAS_CRYPTO("drbg_pr_hmac_sha256");
 MODULE_ALIAS_CRYPTO("drbg_nopr_hmac_sha256");
 MODULE_ALIAS_CRYPTO("drbg_pr_hmac_sha1");
 MODULE_ALIAS_CRYPTO("drbg_nopr_hmac_sha1");
 
 /* update function of HMAC DRBG as defined in 10.1.2.2 */
 static int drbg_hmac_update(struct drbg_state *drbg, struct list_head *seed,
                 int reseed)
 {
     int ret = -EFAULT;
     int i = 0;
     struct drbg_string seed1, seed2, vdata;
     LIST_HEAD(seedlist);
     LIST_HEAD(vdatalist);
 
     if (!reseed) {
         /* 10.1.2.3 step 2 -- memset(0) of C is implicit with kzalloc */
         memset(drbg->V, 1, drbg_statelen(drbg));
         drbg_kcapi_hmacsetkey(drbg, drbg->C);
     }
 
     drbg_string_fill(&seed1, drbg->V, drbg_statelen(drbg));
     list_add_tail(&seed1.list, &seedlist);
     /* buffer of seed2 will be filled in for loop below with one byte */
     drbg_string_fill(&seed2, NULL, 1);
     list_add_tail(&seed2.list, &seedlist);
     /* input data of seed is allowed to be NULL at this point */
     if (seed)
         list_splice_tail(seed, &seedlist);
 
     drbg_string_fill(&vdata, drbg->V, drbg_statelen(drbg));
     list_add_tail(&vdata.list, &vdatalist);
     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, &seedlist);
         if (ret)
             return ret;
         drbg_kcapi_hmacsetkey(drbg, drbg->C);
 
         /* 10.1.2.2 step 2 and 5 -- HMAC for V */
         ret = drbg_kcapi_hash(drbg, drbg->V, &vdatalist);
         if (ret)
             return ret;
 
         /* 10.1.2.2 step 3 */
         if (!seed)
             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 list_head *addtl)
 {
     int len = 0;
     int ret = 0;
     struct drbg_string data;
     LIST_HEAD(datalist);
 
     /* 10.1.2.5 step 2 */
     if (addtl && !list_empty(addtl)) {
         ret = drbg_hmac_update(drbg, addtl, 1);
         if (ret)
             return ret;
     }
 
     drbg_string_fill(&data, drbg->V, drbg_statelen(drbg));
     list_add_tail(&data.list, &datalist);
     while (len < buflen) {
         unsigned int outlen = 0;
         /* 10.1.2.5 step 4.1 */
         ret = drbg_kcapi_hash(drbg, drbg->V, &datalist);
         if (ret)
             return ret;
         outlen = (drbg_blocklen(drbg) < (buflen - len)) ?
               drbg_blocklen(drbg) : (buflen - len);
 
         /* 10.1.2.5 step 4.2 */
         memcpy(buf + len, drbg->V, outlen);
         len += outlen;
     }
 
     /* 10.1.2.5 step 6 */
     if (addtl && !list_empty(addtl))
         ret = drbg_hmac_update(drbg, addtl, 1);
     else
         ret = drbg_hmac_update(drbg, NULL, 1);
     if (ret)
         return ret;
 
     return len;
 }
 
 static const 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
 #define CRYPTO_DRBG_HASH_STRING "HASH "
 MODULE_ALIAS_CRYPTO("drbg_pr_sha512");
 MODULE_ALIAS_CRYPTO("drbg_nopr_sha512");
 MODULE_ALIAS_CRYPTO("drbg_pr_sha384");
 MODULE_ALIAS_CRYPTO("drbg_nopr_sha384");
 MODULE_ALIAS_CRYPTO("drbg_pr_sha256");
 MODULE_ALIAS_CRYPTO("drbg_nopr_sha256");
 MODULE_ALIAS_CRYPTO("drbg_pr_sha1");
 MODULE_ALIAS_CRYPTO("drbg_nopr_sha1");
 
 /*
  * 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--;
     }
 }
 
 /*
  * 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 list_head *entropylist)
 {
     int ret = 0;
     size_t len = 0;
     unsigned char input[5];
     unsigned char *tmp = drbg->scratchpad + drbg_statelen(drbg);
     struct drbg_string data;
 
     /* 10.4.1 step 3 */
     input[0] = 1;
     drbg_cpu_to_be32((outlen * 8), &input[1]);
 
     /* 10.4.1 step 4.1 -- concatenation of data for input into hash */
     drbg_string_fill(&data, input, 5);
     list_add(&data.list, entropylist);
 
     /* 10.4.1 step 4 */
     while (len < outlen) {
         short blocklen = 0;
         /* 10.4.1 step 4.1 */
         ret = drbg_kcapi_hash(drbg, tmp, entropylist);
         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 list_head *seed,
                 int reseed)
 {
     int ret = 0;
     struct drbg_string data1, data2;
     LIST_HEAD(datalist);
     LIST_HEAD(datalist2);
     unsigned char *V = drbg->scratchpad;
     unsigned char prefix = DRBG_PREFIX1;
 
     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);
         list_add_tail(&data1.list, &datalist);
         drbg_string_fill(&data2, V, drbg_statelen(drbg));
         list_add_tail(&data2.list, &datalist);
     }
     list_splice_tail(seed, &datalist);
 
     /* 10.1.1.2 / 10.1.1.3 step 2 and 3 */
     ret = drbg_hash_df(drbg, drbg->V, drbg_statelen(drbg), &datalist);
     if (ret)
         goto out;
 
     /* 10.1.1.2 / 10.1.1.3 step 4  */
     prefix = DRBG_PREFIX0;
     drbg_string_fill(&data1, &prefix, 1);
     list_add_tail(&data1.list, &datalist2);
     drbg_string_fill(&data2, drbg->V, drbg_statelen(drbg));
     list_add_tail(&data2.list, &datalist2);
     /* 10.1.1.2 / 10.1.1.3 step 4 */
     ret = drbg_hash_df(drbg, drbg->C, drbg_statelen(drbg), &datalist2);
 
 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 list_head *addtl)
 {
     int ret = 0;
     struct drbg_string data1, data2;
     LIST_HEAD(datalist);
     unsigned char prefix = DRBG_PREFIX2;
 
     /* 10.1.1.4 step 2 */
     if (!addtl || list_empty(addtl))
         return 0;
 
     /* 10.1.1.4 step 2a */
     drbg_string_fill(&data1, &prefix, 1);
     drbg_string_fill(&data2, drbg->V, drbg_statelen(drbg));
     list_add_tail(&data1.list, &datalist);
     list_add_tail(&data2.list, &datalist);
     list_splice_tail(addtl, &datalist);
     ret = drbg_kcapi_hash(drbg, drbg->scratchpad, &datalist);
     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;
     LIST_HEAD(datalist);
 
     /* 10.1.1.4 step hashgen 2 */
     memcpy(src, drbg->V, drbg_statelen(drbg));
 
     drbg_string_fill(&data, src, drbg_statelen(drbg));
     list_add_tail(&data.list, &datalist);
     while (len < buflen) {
         unsigned int outlen = 0;
         /* 10.1.1.4 step hashgen 4.1 */
         ret = drbg_kcapi_hash(drbg, dst, &datalist);
         if (ret) {
             len = ret;
             goto out;
         }
         outlen = (drbg_blocklen(drbg) < (buflen - len)) ?
               drbg_blocklen(drbg) : (buflen - len);
         /* 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)
             crypto_inc(src, drbg_statelen(drbg));
     }
 
 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 list_head *addtl)
 {
     int len = 0;
     int ret = 0;
     union {
         unsigned char req[8];
         __be64 req_int;
     } u;
     unsigned char prefix = DRBG_PREFIX3;
     struct drbg_string data1, data2;
     LIST_HEAD(datalist);
 
     /* 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 */
     /* 10.1.1.4 step 4 */
     drbg_string_fill(&data1, &prefix, 1);
     list_add_tail(&data1.list, &datalist);
     drbg_string_fill(&data2, drbg->V, drbg_statelen(drbg));
     list_add_tail(&data2.list, &datalist);
     ret = drbg_kcapi_hash(drbg, drbg->scratchpad, &datalist);
     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));
     u.req_int = cpu_to_be64(drbg->reseed_ctr);
     drbg_add_buf(drbg->V, drbg_statelen(drbg), u.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 const 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
  ******************************************************************/
 
 static inline int __drbg_seed(struct drbg_state *drbg, struct list_head *seed,
                   int reseed, enum drbg_seed_state new_seed_state)
 {
     int ret = drbg->d_ops->update(drbg, seed, reseed);
 
     if (ret)
         return ret;
 
     drbg->seeded = new_seed_state;
     drbg->last_seed_time = jiffies;
     /* 10.1.1.2 / 10.1.1.3 step 5 */
     drbg->reseed_ctr = 1;
 
     switch (drbg->seeded) {
     case DRBG_SEED_STATE_UNSEEDED:
         /* Impossible, but handle it to silence compiler warnings. */
         fallthrough;
     case DRBG_SEED_STATE_PARTIAL:
         /*
          * Require frequent reseeds until the seed source is
          * fully initialized.
          */
         drbg->reseed_threshold = 50;
         break;
 
     case DRBG_SEED_STATE_FULL:
         /*
          * Seed source has become fully initialized, frequent
          * reseeds no longer required.
          */
         drbg->reseed_threshold = drbg_max_requests(drbg);
         break;
     }
 
     return ret;
 }
 
 static inline int drbg_get_random_bytes(struct drbg_state *drbg,
                     unsigned char *entropy,
                     unsigned int entropylen)
 {
     int ret;
 
     do {
         get_random_bytes(entropy, entropylen);
         ret = drbg_fips_continuous_test(drbg, entropy);
         if (ret && ret != -EAGAIN)
             return ret;
     } while (ret);
 
     return 0;
 }
 
 static int drbg_seed_from_random(struct drbg_state *drbg)
 {
     struct drbg_string data;
     LIST_HEAD(seedlist);
     unsigned int entropylen = drbg_sec_strength(drbg->core->flags);
     unsigned char entropy[32];
     int ret;
 
     BUG_ON(!entropylen);
     BUG_ON(entropylen > sizeof(entropy));
 
     drbg_string_fill(&data, entropy, entropylen);
     list_add_tail(&data.list, &seedlist);
 
     ret = drbg_get_random_bytes(drbg, entropy, entropylen);
     if (ret)
         goto out;
 
     ret = __drbg_seed(drbg, &seedlist, true, DRBG_SEED_STATE_FULL);
 
 out:
     memzero_explicit(entropy, entropylen);
     return ret;
 }
 
 static bool drbg_nopr_reseed_interval_elapsed(struct drbg_state *drbg)
 {
     unsigned long next_reseed;
 
     /* Don't ever reseed from get_random_bytes() in test mode. */
     if (list_empty(&drbg->test_data.list))
         return false;
 
     /*
      * Obtain fresh entropy for the nopr DRBGs after 300s have
      * elapsed in order to still achieve sort of partial
      * prediction resistance over the time domain at least. Note
      * that the period of 300s has been chosen to match the
      * CRNG_RESEED_INTERVAL of the get_random_bytes()' chacha
      * rngs.
      */
     next_reseed = drbg->last_seed_time + 300 * HZ;
     return time_after(jiffies, next_reseed);
 }
 
 /*
  * 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;
     unsigned char entropy[((32 + 16) * 2)];
     unsigned int entropylen = drbg_sec_strength(drbg->core->flags);
     struct drbg_string data1;
     LIST_HEAD(seedlist);
     enum drbg_seed_state new_seed_state = DRBG_SEED_STATE_FULL;
 
     /* 9.1 / 9.2 / 9.3.1 step 3 */
     if (pers && pers->len > (drbg_max_addtl(drbg))) {
         pr_devel("DRBG: personalization string too long %zu\n",
              pers->len);
         return -EINVAL;
     }
 
     if (list_empty(&drbg->test_data.list)) {
         drbg_string_fill(&data1, drbg->test_data.buf,
                  drbg->test_data.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.
          */
         BUG_ON(!entropylen);
         if (!reseed)
             entropylen = ((entropylen + 1) / 2) * 3;
         BUG_ON((entropylen * 2) > sizeof(entropy));
 
         /* Get seed from in-kernel /dev/urandom */
         if (!rng_is_initialized())
             new_seed_state = DRBG_SEED_STATE_PARTIAL;
 
         ret = drbg_get_random_bytes(drbg, entropy, entropylen);
         if (ret)
             goto out;
 
         if (!drbg->jent) {
             drbg_string_fill(&data1, entropy, entropylen);
             pr_devel("DRBG: (re)seeding with %u bytes of entropy\n",
                  entropylen);
         } else {
             /*
              * Get seed from Jitter RNG, failures are
              * fatal only in FIPS mode.
              */
             ret = crypto_rng_get_bytes(drbg->jent,
                            entropy + entropylen,
                            entropylen);
             if (fips_enabled && ret) {
                 pr_devel("DRBG: jent failed with %d\n", ret);
 
                 /*
                  * Do not treat the transient failure of the
                  * Jitter RNG as an error that needs to be
                  * reported. The combined number of the
                  * maximum reseed threshold times the maximum
                  * number of Jitter RNG transient errors is
                  * less than the reseed threshold required by
                  * SP800-90A allowing us to treat the
                  * transient errors as such.
                  *
                  * However, we mandate that at least the first
                  * seeding operation must succeed with the
                  * Jitter RNG.
                  */
                 if (!reseed || ret != -EAGAIN)
                     goto out;
             }
 
             drbg_string_fill(&data1, entropy, entropylen * 2);
             pr_devel("DRBG: (re)seeding with %u bytes of entropy\n",
                  entropylen * 2);
         }
     }
     list_add_tail(&data1.list, &seedlist);
 
     /*
      * 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) {
         list_add_tail(&pers->list, &seedlist);
         pr_devel("DRBG: using personalization string\n");
     }
 
     if (!reseed) {
         memset(drbg->V, 0, drbg_statelen(drbg));
         memset(drbg->C, 0, drbg_statelen(drbg));
     }
 
     ret = __drbg_seed(drbg, &seedlist, reseed, new_seed_state);
 
 out:
     memzero_explicit(entropy, entropylen * 2);
 
     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;
     kfree_sensitive(drbg->Vbuf);
     drbg->Vbuf = NULL;
     drbg->V = NULL;
     kfree_sensitive(drbg->Cbuf);
     drbg->Cbuf = NULL;
     drbg->C = NULL;
     kfree_sensitive(drbg->scratchpadbuf);
     drbg->scratchpadbuf = NULL;
     drbg->reseed_ctr = 0;
     drbg->d_ops = NULL;
     drbg->core = NULL;
     if (IS_ENABLED(CONFIG_CRYPTO_FIPS)) {
         kfree_sensitive(drbg->prev);
         drbg->prev = NULL;
         drbg->fips_primed = false;
     }
 }
 
 /*
  * 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;
 
     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:
         ret = -EOPNOTSUPP;
         goto err;
     }
 
     ret = drbg->d_ops->crypto_init(drbg);
     if (ret < 0)
         goto err;
 
     drbg->Vbuf = kmalloc(drbg_statelen(drbg) + ret, GFP_KERNEL);
     if (!drbg->Vbuf) {
         ret = -ENOMEM;
         goto fini;
     }
     drbg->V = PTR_ALIGN(drbg->Vbuf, ret + 1);
     drbg->Cbuf = kmalloc(drbg_statelen(drbg) + ret, GFP_KERNEL);
     if (!drbg->Cbuf) {
         ret = -ENOMEM;
         goto fini;
     }
     drbg->C = PTR_ALIGN(drbg->Cbuf, ret + 1);
     /* 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) + drbg_blocklen(drbg); /* temp */
     else
         sb_size = drbg_statelen(drbg) + drbg_blocklen(drbg);
 
     if (0 < sb_size) {
         drbg->scratchpadbuf = kzalloc(sb_size + ret, GFP_KERNEL);
         if (!drbg->scratchpadbuf) {
             ret = -ENOMEM;
             goto fini;
         }
         drbg->scratchpad = PTR_ALIGN(drbg->scratchpadbuf, ret + 1);
     }
 
     if (IS_ENABLED(CONFIG_CRYPTO_FIPS)) {
         drbg->prev = kzalloc(drbg_sec_strength(drbg->core->flags),
                      GFP_KERNEL);
         if (!drbg->prev) {
             ret = -ENOMEM;
             goto fini;
         }
         drbg->fips_primed = false;
     }
 
     return 0;
 
 fini:
     drbg->d_ops->crypto_fini(drbg);
 err:
     drbg_dealloc_state(drbg);
     return ret;
 }
 
 /*************************************************************************
  * 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: 0 when all bytes are generated; < 0 in case of an error
  */
 static int drbg_generate(struct drbg_state *drbg,
              unsigned char *buf, unsigned int buflen,
              struct drbg_string *addtl)
 {
     int len = 0;
     LIST_HEAD(addtllist);
 
     if (!drbg->core) {
         pr_devel("DRBG: not yet seeded\n");
         return -EINVAL;
     }
     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;
     }
 
     /* 9.3.1 step 2 */
     len = -EINVAL;
     if (buflen > (drbg_max_request_bytes(drbg))) {
         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(drbg))) {
         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->reseed_threshold < drbg->reseed_ctr)
         drbg->seeded = DRBG_SEED_STATE_UNSEEDED;
 
     if (drbg->pr || drbg->seeded == DRBG_SEED_STATE_UNSEEDED) {
         pr_devel("DRBG: reseeding before generation (prediction "
              "resistance: %s, state %s)\n",
              drbg->pr ? "true" : "false",
              (drbg->seeded ==  DRBG_SEED_STATE_FULL ?
               "seeded" : "unseeded"));
         /* 9.3.1 steps 7.1 through 7.3 */
         len = drbg_seed(drbg, addtl, true);
         if (len)
             goto err;
         /* 9.3.1 step 7.4 */
         addtl = NULL;
     } else if (rng_is_initialized() &&
            (drbg->seeded == DRBG_SEED_STATE_PARTIAL ||
             drbg_nopr_reseed_interval_elapsed(drbg))) {
         len = drbg_seed_from_random(drbg);
         if (len)
             goto err;
     }
 
     if (addtl && 0 < addtl->len)
         list_add_tail(&addtl->list, &addtllist);
     /* 9.3.1 step 8 and 10 */
     len = drbg->d_ops->generate(drbg, buf, buflen, &addtllist);
 
     /* 10.1.1.4 step 6, 10.1.2.5 step 7, 10.2.1.5.2 step 7 */
     drbg->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 (drbg->reseed_ctr && !(drbg->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);
             return 0;
         } else {
             pr_devel("DRBG: self test successful\n");
         }
     }
 #endif
 
     /*
      * All operations were successful, return 0 as mandated by
      * the kernel crypto API interface.
      */
     len = 0;
 err:
     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)
 {
     unsigned int len = 0;
     unsigned int slice = 0;
     do {
         int err = 0;
         unsigned int chunk = 0;
         slice = ((buflen - len) / drbg_max_request_bytes(drbg));
         chunk = slice ? drbg_max_request_bytes(drbg) : (buflen - len);
         mutex_lock(&drbg->drbg_mutex);
         err = drbg_generate(drbg, buf + len, chunk, addtl);
         mutex_unlock(&drbg->drbg_mutex);
         if (0 > err)
             return err;
         len += chunk;
     } while (slice > 0 && (len < buflen));
     return 0;
 }
 
 static int drbg_prepare_hrng(struct drbg_state *drbg)
 {
     /* We do not need an HRNG in test mode. */
     if (list_empty(&drbg->test_data.list))
         return 0;
 
     drbg->jent = crypto_alloc_rng("jitterentropy_rng", 0, 0);
     if (IS_ERR(drbg->jent)) {
         const int err = PTR_ERR(drbg->jent);
 
         drbg->jent = NULL;
         if (fips_enabled || err != -ENOENT)
             return err;
         pr_info("DRBG: Continuing without Jitter RNG\n");
     }
 
     return 0;
 }
 
 /*
  * 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;
     bool reseed = true;
 
     pr_devel("DRBG: Initializing DRBG core %d with prediction resistance "
          "%s\n", coreref, pr ? "enabled" : "disabled");
     mutex_lock(&drbg->drbg_mutex);
 
     /* 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 */
 
     if (!drbg->core) {
         drbg->core = &drbg_cores[coreref];
         drbg->pr = pr;
         drbg->seeded = DRBG_SEED_STATE_UNSEEDED;
         drbg->last_seed_time = 0;
         drbg->reseed_threshold = drbg_max_requests(drbg);
 
         ret = drbg_alloc_state(drbg);
         if (ret)
             goto unlock;
 
         ret = drbg_prepare_hrng(drbg);
         if (ret)
             goto free_everything;
 
         reseed = false;
     }
 
     ret = drbg_seed(drbg, pers, reseed);
 
     if (ret && !reseed)
         goto free_everything;
 
     mutex_unlock(&drbg->drbg_mutex);
     return ret;
 
 unlock:
     mutex_unlock(&drbg->drbg_mutex);
     return ret;
 
 free_everything:
     mutex_unlock(&drbg->drbg_mutex);
     drbg_uninstantiate(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)
 {
     if (!IS_ERR_OR_NULL(drbg->jent))
         crypto_free_rng(drbg->jent);
     drbg->jent = NULL;
 
     if (drbg->d_ops)
         drbg->d_ops->crypto_fini(drbg);
     drbg_dealloc_state(drbg);
     /* no scrubbing of test_data -- this shall survive an uninstantiate */
     return 0;
 }
 
 /*
  * Helper function for setting the test data in the DRBG
  *
  * @drbg DRBG state handle
  * @data test data
  * @len test data length
  */
 static void drbg_kcapi_set_entropy(struct crypto_rng *tfm,
                    const u8 *data, unsigned int len)
 {
     struct drbg_state *drbg = crypto_rng_ctx(tfm);
 
     mutex_lock(&drbg->drbg_mutex);
     drbg_string_fill(&drbg->test_data, data, len);
     mutex_unlock(&drbg->drbg_mutex);
 }
 
 /***************************************************************
  * 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: %s\n",
                 drbg->core->backend_cra_name);
         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;
     drbg->priv_data = sdesc;
 
     return crypto_shash_alignmask(tfm);
 }
 
 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);
         kfree_sensitive(sdesc);
     }
     drbg->priv_data = NULL;
     return 0;
 }
 
 static void drbg_kcapi_hmacsetkey(struct drbg_state *drbg,
                   const unsigned char *key)
 {
     struct sdesc *sdesc = (struct sdesc *)drbg->priv_data;
 
     crypto_shash_setkey(sdesc->shash.tfm, key, drbg_statelen(drbg));
 }
 
 static int drbg_kcapi_hash(struct drbg_state *drbg, unsigned char *outval,
                const struct list_head *in)
 {
     struct sdesc *sdesc = (struct sdesc *)drbg->priv_data;
     struct drbg_string *input = NULL;
 
     crypto_shash_init(&sdesc->shash);
     list_for_each_entry(input, in, list)
         crypto_shash_update(&sdesc->shash, input->buf, input->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_fini_sym_kernel(struct drbg_state *drbg)
 {
     struct crypto_cipher *tfm =
         (struct crypto_cipher *)drbg->priv_data;
     if (tfm)
         crypto_free_cipher(tfm);
     drbg->priv_data = NULL;
 
     if (drbg->ctr_handle)
         crypto_free_skcipher(drbg->ctr_handle);
     drbg->ctr_handle = NULL;
 
     if (drbg->ctr_req)
         skcipher_request_free(drbg->ctr_req);
     drbg->ctr_req = NULL;
 
     kfree(drbg->outscratchpadbuf);
     drbg->outscratchpadbuf = NULL;
 
     return 0;
 }
 
 static int drbg_init_sym_kernel(struct drbg_state *drbg)
 {
     struct crypto_cipher *tfm;
     struct crypto_skcipher *sk_tfm;
     struct skcipher_request *req;
     unsigned int alignmask;
     char ctr_name[CRYPTO_MAX_ALG_NAME];
 
     tfm = crypto_alloc_cipher(drbg->core->backend_cra_name, 0, 0);
     if (IS_ERR(tfm)) {
         pr_info("DRBG: could not allocate cipher TFM handle: %s\n",
                 drbg->core->backend_cra_name);
         return PTR_ERR(tfm);
     }
     BUG_ON(drbg_blocklen(drbg) != crypto_cipher_blocksize(tfm));
     drbg->priv_data = tfm;
 
     if (snprintf(ctr_name, CRYPTO_MAX_ALG_NAME, "ctr(%s)",
         drbg->core->backend_cra_name) >= CRYPTO_MAX_ALG_NAME) {
         drbg_fini_sym_kernel(drbg);
         return -EINVAL;
     }
     sk_tfm = crypto_alloc_skcipher(ctr_name, 0, 0);
     if (IS_ERR(sk_tfm)) {
         pr_info("DRBG: could not allocate CTR cipher TFM handle: %s\n",
                 ctr_name);
         drbg_fini_sym_kernel(drbg);
         return PTR_ERR(sk_tfm);
     }
     drbg->ctr_handle = sk_tfm;
     crypto_init_wait(&drbg->ctr_wait);
 
     req = skcipher_request_alloc(sk_tfm, GFP_KERNEL);
     if (!req) {
         pr_info("DRBG: could not allocate request queue\n");
         drbg_fini_sym_kernel(drbg);
         return -ENOMEM;
     }
     drbg->ctr_req = req;
     skcipher_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG |
                         CRYPTO_TFM_REQ_MAY_SLEEP,
                     crypto_req_done, &drbg->ctr_wait);
 
     alignmask = crypto_skcipher_alignmask(sk_tfm);
     drbg->outscratchpadbuf = kmalloc(DRBG_OUTSCRATCHLEN + alignmask,
                      GFP_KERNEL);
     if (!drbg->outscratchpadbuf) {
         drbg_fini_sym_kernel(drbg);
         return -ENOMEM;
     }
     drbg->outscratchpad = (u8 *)PTR_ALIGN(drbg->outscratchpadbuf,
                           alignmask + 1);
 
     sg_init_table(&drbg->sg_in, 1);
     sg_init_one(&drbg->sg_out, drbg->outscratchpad, DRBG_OUTSCRATCHLEN);
 
     return alignmask;
 }
 
 static void drbg_kcapi_symsetkey(struct drbg_state *drbg,
                  const unsigned char *key)
 {
     struct crypto_cipher *tfm =
         (struct crypto_cipher *)drbg->priv_data;
 
     crypto_cipher_setkey(tfm, key, (drbg_keylen(drbg)));
 }
 
 static int drbg_kcapi_sym(struct drbg_state *drbg, unsigned char *outval,
               const struct drbg_string *in)
 {
     struct crypto_cipher *tfm =
         (struct crypto_cipher *)drbg->priv_data;
 
     /* there is only component in *in */
     BUG_ON(in->len < drbg_blocklen(drbg));
     crypto_cipher_encrypt_one(tfm, outval, in->buf);
     return 0;
 }
 
 static int drbg_kcapi_sym_ctr(struct drbg_state *drbg,
                   u8 *inbuf, u32 inlen,
                   u8 *outbuf, u32 outlen)
 {
     struct scatterlist *sg_in = &drbg->sg_in, *sg_out = &drbg->sg_out;
     u32 scratchpad_use = min_t(u32, outlen, DRBG_OUTSCRATCHLEN);
     int ret;
 
     if (inbuf) {
         /* Use caller-provided input buffer */
         sg_set_buf(sg_in, inbuf, inlen);
     } else {
         /* Use scratchpad for in-place operation */
         inlen = scratchpad_use;
         memset(drbg->outscratchpad, 0, scratchpad_use);
         sg_set_buf(sg_in, drbg->outscratchpad, scratchpad_use);
     }
 
     while (outlen) {
         u32 cryptlen = min3(inlen, outlen, (u32)DRBG_OUTSCRATCHLEN);
 
         /* Output buffer may not be valid for SGL, use scratchpad */
         skcipher_request_set_crypt(drbg->ctr_req, sg_in, sg_out,
                        cryptlen, drbg->V);
         ret = crypto_wait_req(crypto_skcipher_encrypt(drbg->ctr_req),
                     &drbg->ctr_wait);
         if (ret)
             goto out;
 
         crypto_init_wait(&drbg->ctr_wait);
 
         memcpy(outbuf, drbg->outscratchpad, cryptlen);
         memzero_explicit(drbg->outscratchpad, cryptlen);
 
         outlen -= cryptlen;
         outbuf += cryptlen;
     }
     ret = 0;
 
 out:
     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);
 
     mutex_init(&drbg->drbg_mutex);
 
     return 0;
 }
 
 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:
  *
  * src is additional input supplied to the RNG.
  * slen is the length of src.
  * dst is the output buffer where random data is to be stored.
  * dlen is the length of dst.
  */
 static int drbg_kcapi_random(struct crypto_rng *tfm,
                  const u8 *src, unsigned int slen,
                  u8 *dst, unsigned int dlen)
 {
     struct drbg_state *drbg = crypto_rng_ctx(tfm);
     struct drbg_string *addtl = NULL;
     struct drbg_string string;
 
     if (slen) {
         /* linked list variable is now local to allow modification */
         drbg_string_fill(&string, src, slen);
         addtl = &string;
     }
 
     return drbg_generate_long(drbg, dst, dlen, addtl);
 }
 
 /*
  * Seed the DRBG invoked by the kernel crypto API
  */
 static int drbg_kcapi_seed(struct crypto_rng *tfm,
                const 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 string;
     struct drbg_string *seed_string = NULL;
     int coreref = 0;
 
     drbg_convert_tfm_core(crypto_tfm_alg_driver_name(tfm_base), &coreref,
                   &pr);
     if (0 < slen) {
         drbg_string_fill(&string, seed, slen);
         seed_string = &string;
     }
 
     return drbg_instantiate(drbg, seed_string, 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)
 {
     int len = 0;
 #define OUTBUFLEN 16
     unsigned char buf[OUTBUFLEN];
     struct drbg_state *drbg = NULL;
     int ret;
     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 defined 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;
 
     mutex_init(&drbg->drbg_mutex);
     drbg->core = &drbg_cores[coreref];
     drbg->reseed_threshold = drbg_max_requests(drbg);
 
     /*
      * 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.
      */
 
     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);
 
     /* overflow max addtllen with personalization string */
     ret = drbg_seed(drbg, &addtl, false);
     BUG_ON(0 == ret);
     /* all tests passed */
     rc = 0;
 
     pr_devel("DRBG: Sanity tests for failure code paths successfully "
          "completed\n");
 
     kfree(drbg);
     return rc;
 }
 
 static struct rng_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 rng_alg *alg,
                       const struct drbg_core *core, int pr)
 {
     int pos = 0;
     static int priority = 200;
 
     memcpy(alg->base.cra_name, "stdrng", 6);
     if (pr) {
         memcpy(alg->base.cra_driver_name, "drbg_pr_", 8);
         pos = 8;
     } else {
         memcpy(alg->base.cra_driver_name, "drbg_nopr_", 10);
         pos = 10;
     }
     memcpy(alg->base.cra_driver_name + pos, core->cra_name,
            strlen(core->cra_name));
 
     alg->base.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->base.cra_priority += 200;
 
     alg->base.cra_ctxsize   = sizeof(struct drbg_state);
     alg->base.cra_module    = THIS_MODULE;
     alg->base.cra_init  = drbg_kcapi_init;
     alg->base.cra_exit  = drbg_kcapi_cleanup;
     alg->generate       = drbg_kcapi_random;
     alg->seed       = drbg_kcapi_seed;
     alg->set_ent        = drbg_kcapi_set_entropy;
     alg->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;
 
     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: %zu, slots available: %zu)\n",
             ARRAY_SIZE(drbg_cores) * 2, ARRAY_SIZE(drbg_algs));
         return -EFAULT;
     }
 
     /*
      * 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_rngs(drbg_algs, (ARRAY_SIZE(drbg_cores) * 2));
 }
 
 static void __exit drbg_exit(void)
 {
     crypto_unregister_rngs(drbg_algs, (ARRAY_SIZE(drbg_cores) * 2));
 }
 
 subsys_initcall(drbg_init);
 module_exit(drbg_exit);
 #ifndef CRYPTO_DRBG_HASH_STRING
 #define CRYPTO_DRBG_HASH_STRING ""
 #endif
 #ifndef CRYPTO_DRBG_HMAC_STRING
 #define CRYPTO_DRBG_HMAC_STRING ""
 #endif
 #ifndef CRYPTO_DRBG_CTR_STRING
 #define CRYPTO_DRBG_CTR_STRING ""
 #endif
 MODULE_LICENSE("GPL");
 MODULE_AUTHOR("Stephan Mueller <smueller@chronox.de>");
 MODULE_DESCRIPTION("NIST SP800-90A Deterministic Random Bit Generator (DRBG) "
            "using following cores: "
            CRYPTO_DRBG_HASH_STRING
            CRYPTO_DRBG_HMAC_STRING
            CRYPTO_DRBG_CTR_STRING);
 MODULE_ALIAS_CRYPTO("stdrng");
 MODULE_IMPORT_NS(CRYPTO_INTERNAL);

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