diff options
author | Stephan Mueller <smueller@chronox.de> | 2014-05-31 15:44:17 +0200 |
---|---|---|
committer | Herbert Xu <herbert@gondor.apana.org.au> | 2014-06-20 21:26:08 +0800 |
commit | 541af946fe1360ec1b45730964e87d7f93c50781 (patch) | |
tree | ad89cf0a13a361db5d80a204329e2c0539454322 /crypto | |
parent | 13269ec647050fd7652abd0eb05673ffe90c3e92 (diff) |
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>
Diffstat (limited to 'crypto')
-rw-r--r-- | crypto/drbg.c | 2007 |
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 & |