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Diffstat (limited to 'crypto/drbg.c')
| -rw-r--r-- | crypto/drbg.c | 2044 |
1 files changed, 2044 insertions, 0 deletions
diff --git a/crypto/drbg.c b/crypto/drbg.c new file mode 100644 index 0000000..7894db9 --- /dev/null +++ b/crypto/drbg.c @@ -0,0 +1,2044 @@ +/* + * 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> + +/*************************************************************** + * 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_STRENGTH128, + .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 +#define CRYPTO_DRBG_CTR_STRING "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 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 1 */ + memset(out, 0, drbg_blocklen(drbg)); + + /* 10.4.3 step 2 / 4 */ + 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, key, 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, key, 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)); + 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 */ + list_for_each_entry(seed, seedlist, list) + inputlen += seed->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)); + 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_int2byte(iv, i, 4); + /* 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 */ + 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 + * + * 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); + 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)); + if (3 > reseed) + memset(df_data, 0, drbg_statelen(drbg)); + + /* 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; + } + + 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)); + 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 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 && !list_empty(addtl)) { + ret = drbg_ctr_update(drbg, addtl, 2); + 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 */ + ret = drbg_ctr_update(drbg, NULL, 3); + 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 list_head *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 +#define CRYPTO_DRBG_HMAC_STRING "HMAC " +/* 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(drbg->C, 0, drbg_statelen(drbg)); + memset(drbg->V, 1, drbg_statelen(drbg)); + } + + 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, drbg->C, &seedlist); + if (ret) + return ret; + + /* 10.1.2.2 step 2 and 5 -- HMAC for V */ + ret = drbg_kcapi_hash(drbg, drbg->C, 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->C, drbg->V, &datalist); + 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 && !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 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 " +/* + * 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; + + 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(&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, NULL, 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; + + 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); + 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; + + /* this is value w as per documentation */ + memset(drbg->scratchpad, 0, drbg_blocklen(drbg)); + + /* 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, NULL, 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); + 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)); + 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, NULL, dst, &datalist); + 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 list_head *addtl) +{ + int len = 0; + int ret = 0; + unsigned char req[8]; + 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 */ + memset(drbg->scratchpad, 0, drbg_blocklen(drbg)); + /* 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, NULL, 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)); + 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; + LIST_HEAD(seedlist); + + /* 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 (drbg->test_data && drbg->test_data->testentropy) { + drbg_string_fill(&data1, drbg->test_data->testentropy->buf, + drbg->test_data->testentropy->len); + pr_devel("DRBG: using test entropy\n"); + } else { + /* + * Gather entropy equal to the security strength of the DRBG. + * With a derivation function, a nonce is required in addition + * to the entropy. A nonce must be at least 1/2 of the security + * strength of the DRBG in size. Thus, entropy * nonce is 3/2 + * of the strength. The consideration of a nonce is only + * applicable during initial seeding. + */ + entropylen = drbg_sec_strength(drbg->core->flags); + if (!entropylen) + return -EFAULT; + if (!reseed) + entropylen = ((entropylen + 1) / 2) * 3; + pr_devel("DRBG: (re)seeding with %zu bytes of entropy\n", + entropylen); + entropy = kzalloc(entropylen, GFP_KERNEL); + if (!entropy) + return -ENOMEM; + get_random_bytes(entropy, entropylen); + drbg_string_fill(&data1, entropy, entropylen); + } + 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"); + } + + ret = drbg->d_ops->update(drbg, &seedlist, reseed); + if (ret) + goto out; + + drbg->seeded = true; + /* 10.1.1.2 / 10.1.1.3 step 5 */ + drbg->reseed_ctr = 1; + +out: + if (entropy) + kzfree(entropy); + return ret; +} + +/* Free all substructures in a DRBG state without the DRBG state structure */ +static inline void drbg_dealloc_state(struct drbg_state *drbg) +{ + if (!drbg) + return; + if (drbg->V) + kzfree(drbg->V); + drbg->V = NULL; + if (drbg->C) + kzfree(drbg->C); + drbg->C = NULL; + if (drbg->scratchpad) + kzfree(drbg->scratchpad); + drbg->scratchpad = NULL; + drbg->reseed_ctr = 0; +#ifdef CONFIG_CRYPTO_FIPS + if (drbg->prev) + kzfree(drbg->prev); + drbg->prev = NULL; + drbg->fips_primed = false; +#endif +} + +/* + * Allocate all sub-structures for a DRBG state. + * The DRBG state structure must already be allocated. + */ +static inline int drbg_alloc_state(struct drbg_state *drbg) +{ + int ret = -ENOMEM; + unsigned int sb_size = 0; + + if (!drbg) + return -EINVAL; + + drbg->V = kzalloc(drbg_statelen(drbg), GFP_KERNEL); + if (!drbg->V) + goto err; + drbg->C = kzalloc(drbg_statelen(drbg), GFP_KERNEL); + if (!drbg->C) + goto err; +#ifdef CONFIG_CRYPTO_FIPS + drbg->prev = kzalloc(drbg_blocklen(drbg), GFP_KERNEL); + if (!drbg->prev) + goto err; + drbg->fips_primed = false; +#endif + /* scratchpad is only generated for CTR and Hash */ + if (drbg->core->flags & DRBG_HMAC) + sb_size = 0; + else if (drbg->core->flags & DRBG_CTR) + sb_size = drbg_statelen(drbg) + drbg_blocklen(drbg) + /* temp */ + drbg_statelen(drbg) + /* df_data */ + drbg_blocklen(drbg) + /* pad */ + drbg_blocklen(drbg) + /* iv */ + drbg_statelen(drbg) + drbg_blocklen(drbg); /* temp */ + else + sb_size = drbg_statelen(drbg) + drbg_blocklen(drbg); + + if (0 < sb_size) { + drbg->scratchpad = kzalloc(sb_size, GFP_KERNEL); + if (!drbg->scratchpad) + goto err; + } + spin_lock_init(&drbg->drbg_lock); + return 0; + +err: + drbg_dealloc_state(drbg); + return ret; +} + +/* + * Strategy to avoid holding long term locks: generate a shadow copy of DRBG + * and perform all operations on this shadow copy. After finishing, restore + * the updated state of the shadow copy into original drbg state. This way, + * only the read and write operations of the original drbg state must be + * locked + */ +static inline void drbg_copy_drbg(struct drbg_state *src, + struct drbg_state *dst) +{ + if (!src || !dst) + return; + memcpy(dst->V, src->V, drbg_statelen(src)); + memcpy(dst->C, src->C, drbg_statelen(src)); + dst->reseed_ctr = src->reseed_ctr; + dst->seeded = src->seeded; + dst->pr = src->pr; +#ifdef CONFIG_CRYPTO_FIPS + dst->fips_primed = src->fips_primed; + memcpy(dst->prev, src->prev, drbg_blocklen(src)); +#endif + /* + * Not copied: + * scratchpad is initialized drbg_alloc_state; + * priv_data is initialized with call to crypto_init; + * d_ops and core are set outside, as these parameters are const; + * test_data is set outside to prevent it being copied back. + */ +} + +static int drbg_make_shadow(struct drbg_state *drbg, struct drbg_state **shadow) +{ + int ret = -ENOMEM; + struct drbg_state *tmp = NULL; + + if (!drbg || !drbg->core || !drbg->V || !drbg->C) { + pr_devel("DRBG: attempt to generate shadow copy for " + "uninitialized DRBG state rejected\n"); + return -EINVAL; + } + /* HMAC does not have a scratchpad */ + if (!(drbg->core->flags & DRBG_HMAC) && NULL == drbg->scratchpad) + return -EINVAL; + + tmp = kzalloc(sizeof(struct drbg_state), GFP_KERNEL); + if (!tmp) + return -ENOMEM; + + /* read-only data as they are defined as const, no lock needed */ + tmp->core = drbg->core; + tmp->d_ops = drbg->d_ops; + + ret = drbg_alloc_state(tmp); + if (ret) + goto err; + + spin_lock_bh(&drbg->drbg_lock); + drbg_copy_drbg(drbg, tmp); + /* only make a link to the test buffer, as we only read that data */ + tmp->test_data = drbg->test_data; + spin_unlock_bh(&drbg->drbg_lock); + *shadow = tmp; + return 0; + +err: + if (tmp) + kzfree(tmp); + return ret; +} + +static void drbg_restore_shadow(struct drbg_state *drbg, + struct drbg_state **shadow) +{ + struct drbg_state *tmp = *shadow; + + spin_lock_bh(&drbg->drbg_lock); + drbg_copy_drbg(tmp, drbg); + spin_unlock_bh(&drbg->drbg_lock); + drbg_dealloc_state(tmp); + kzfree(tmp); + *shadow = NULL; +} + +/************************************************************************* + * DRBG interface functions + *************************************************************************/ + +/* + * DRBG generate function as required by SP800-90A - this function + * generates random numbers + * + * @drbg DRBG state handle + * @buf Buffer where to store the random numbers -- the buffer must already + * be pre-allocated by caller + * @buflen Length of output buffer - this value defines the number of random + * bytes pulled from DRBG + * @addtl Additional input that is mixed into state, may be NULL -- note + * the entropy is pulled by the DRBG internally unconditionally + * as defined in SP800-90A. The additional input is mixed into + * the state in addition to the pulled entropy. + * + * return: generated number of bytes + */ +static int drbg_generate(struct drbg_state *drbg, + unsigned char *buf, unsigned int buflen, + struct drbg_string *addtl) +{ + int len = 0; + struct drbg_state *shadow = NULL; + LIST_HEAD(addtllist); + struct drbg_string timestamp; + union { + cycles_t cycles; + unsigned char char_cycles[sizeof(cycles_t)]; + } now; + + if (0 == buflen || !buf) { + pr_devel("DRBG: no output buffer provided\n"); + return -EINVAL; + } + if (addtl && NULL == addtl->buf && 0 < addtl->len) { + pr_devel("DRBG: wrong format of additional information\n"); + return -EINVAL; + } + + len = drbg_make_shadow(drbg, &shadow); + if (len) { + pr_devel("DRBG: shadow copy cannot be generated\n"); + return len; + } + + /* 9.3.1 step 2 */ + len = -EINVAL; + if (buflen > (drbg_max_request_bytes(shadow))) { + pr_devel("DRBG: requested random numbers too large %u\n", + buflen); + goto err; + } + + /* 9.3.1 step 3 is implicit with the chosen DRBG */ + + /* 9.3.1 step 4 */ + if (addtl && addtl->len > (drbg_max_addtl(shadow))) { + pr_devel("DRBG: additional information string too long %zu\n", + addtl->len); + goto err; + } + /* 9.3.1 step 5 is implicit with the chosen DRBG */ + + /* + * 9.3.1 step 6 and 9 supplemented by 9.3.2 step c is implemented + * here. The spec is a bit convoluted here, we make it simpler. + */ + if ((drbg_max_requests(shadow)) < shadow->reseed_ctr) + shadow->seeded = false; + + /* allocate cipher handle */ + if (shadow->d_ops->crypto_init) { + len = shadow->d_ops->crypto_init(shadow); + if (len) + goto err; + } + + if (shadow->pr || !shadow->seeded) { + pr_devel("DRBG: reseeding before generation (prediction " + "resistance: %s, state %s)\n", + drbg->pr ? "true" : "false", + drbg->seeded ? "seeded" : "unseeded"); + /* 9.3.1 steps 7.1 through 7.3 */ + len = drbg_seed(shadow, addtl, true); + if (len) + goto err; + /* 9.3.1 step 7.4 */ + addtl = NULL; + } + + /* + * Mix the time stamp into the DRBG state if the DRBG is not in + * test mode. If there are two callers invoking the DRBG at the same + * time, i.e. before the first caller merges its shadow state back, + * both callers would obtain the same random number stream without + * changing the state here. + */ + if (!drbg->test_data) { + now.cycles = random_get_entropy(); + drbg_string_fill(×tamp, now.char_cycles, sizeof(cycles_t)); + list_add_tail(×tamp.list, &addtllist); + } + if (addtl && 0 < addtl->len) + list_add_tail(&addtl->list, &addtllist); + /* 9.3.1 step 8 and 10 */ + len = shadow->d_ops->generate(shadow, buf, buflen, &addtllist); + + /* 10.1.1.4 step 6, 10.1.2.5 step 7, 10.2.1.5.2 step 7 */ + shadow->reseed_ctr++; + if (0 >= len) + goto err; + + /* + * Section 11.3.3 requires to re-perform self tests after some + * generated random numbers. The chosen value after which self + * test is performed is arbitrary, but it should be reasonable. + * However, we do not perform the self tests because of the following + * reasons: it is mathematically impossible that the initial self tests + * were successfully and the following are not. If the initial would + * pass and the following would not, the kernel integrity is violated. + * In this case, the entire kernel operation is questionable and it + * is unlikely that the integrity violation only affects the + * correct operation of the DRBG. + * + * Albeit the following code is commented out, it is provided in + * case somebody has a need to implement the test of 11.3.3. + */ +#if 0 + if (shadow->reseed_ctr && !(shadow->reseed_ctr % 4096)) { + int err = 0; + pr_devel("DRBG: start to perform self test\n"); + if (drbg->core->flags & DRBG_HMAC) + err = alg_test("drbg_pr_hmac_sha256", + "drbg_pr_hmac_sha256", 0, 0); + else if (drbg->core->flags & DRBG_CTR) + err = alg_test("drbg_pr_ctr_aes128", + "drbg_pr_ctr_aes128", 0, 0); + else + err = alg_test("drbg_pr_sha256", + "drbg_pr_sha256", 0, 0); + if (err) { + pr_err("DRBG: periodical self test failed\n"); + /* + * uninstantiate implies that from now on, only errors + * are returned when reusing this DRBG cipher handle + */ + drbg_uninstantiate(drbg); + drbg_dealloc_state(shadow); + kzfree(shadow); + return 0; + } else { + pr_devel("DRBG: self test successful\n"); + } + } +#endif + +err: + if (shadow->d_ops->crypto_fini) + shadow->d_ops->crypto_fini(shadow); + drbg_restore_shadow(drbg, &shadow); + return len; +} + +/* + * Wrapper around drbg_generate which can pull arbitrary long strings + * from the DRBG without hitting the maximum request limitation. + * + * Parameters: see drbg_generate + * Return codes: see drbg_generate -- if one drbg_generate request fails, + * the entire drbg_generate_long request fails + */ +static int drbg_generate_long(struct drbg_state *drbg, + unsigned char *buf, unsigned int buflen, + struct drbg_string *addtl) +{ + int len = 0; + unsigned int slice = 0; + do { + int tmplen = 0; + unsigned int chunk = 0; + slice = ((buflen - len) / drbg_max_request_bytes(drbg)); + chunk = slice ? drbg_max_request_bytes(drbg) : (buflen - len); + tmplen = drbg_generate(drbg, buf + len, chunk, addtl); + if (0 >= tmplen) + return tmplen; + len += tmplen; + } while (slice > 0 && (len < buflen)); + return len; +} + +/* + * DRBG instantiation function as required by SP800-90A - this function + * sets up the DRBG handle, performs the initial seeding and all sanity + * checks required by SP800-90A + * + * @drbg memory of state -- if NULL, new memory is allocated + * @pers Personalization string that is mixed into state, may be NULL -- note + * the entropy is pulled by the DRBG internally unconditionally + * as defined in SP800-90A. The additional input is mixed into + * the state in addition to the pulled entropy. + * @coreref reference to core + * @pr prediction resistance enabled + * + * return + * 0 on success + * error value otherwise + */ +static int drbg_instantiate(struct drbg_state *drbg, struct drbg_string *pers, + int coreref, bool pr) +{ + int ret = -ENOMEM; + + pr_devel("DRBG: Initializing DRBG core %d with prediction resistance " + "%s\n", coreref, pr ? "enabled" : "disabled"); + drbg->core = &drbg_cores[coreref]; + drbg->pr = pr; + drbg->seeded = false; + switch (drbg->core->flags & DRBG_TYPE_MASK) { +#ifdef CONFIG_CRYPTO_DRBG_HMAC + case DRBG_HMAC: + drbg->d_ops = &drbg_hmac_ops; + break; +#endif /* CONFIG_CRYPTO_DRBG_HMAC */ +#ifdef CONFIG_CRYPTO_DRBG_HASH + case DRBG_HASH: + drbg->d_ops = &drbg_hash_ops; + break; +#endif /* CONFIG_CRYPTO_DRBG_HASH */ +#ifdef CONFIG_CRYPTO_DRBG_CTR + case DRBG_CTR: + drbg->d_ops = &drbg_ctr_ops; + break; +#endif /* CONFIG_CRYPTO_DRBG_CTR */ + default: + return -EOPNOTSUPP; + } + + /* 9.1 step 1 is implicit with the selected DRBG type */ + + /* + * 9.1 step 2 is implicit as caller can select prediction resistance + * and the flag is copied into drbg->flags -- + * all DRBG types support prediction resistance + */ + + /* 9.1 step 4 is implicit in drbg_sec_strength */ + + ret = drbg_alloc_state(drbg); + if (ret) + return ret; + + ret = -EFAULT; + if (drbg->d_ops->crypto_init && drbg->d_ops->crypto_init(drbg)) + goto err; + ret = drbg_seed(drbg, pers, false); + if (drbg->d_ops->crypto_fini) + drbg->d_ops->crypto_fini(drbg); + if (ret) + goto err; + + return 0; + +err: + drbg_dealloc_state(drbg); + return ret; +} + +/* + * DRBG uninstantiate function as required by SP800-90A - this function + * frees all buffers and the DRBG handle + * + * @drbg DRBG state handle + * + * return + * 0 on success + */ +static int drbg_uninstantiate(struct drbg_state *drbg) +{ + spin_lock_bh(&drbg->drbg_lock); + drbg_dealloc_state(drbg); + /* no scrubbing of test_data -- this shall survive an uninstantiate */ + spin_unlock_bh(&drbg->drbg_lock); + return 0; +} + +/* + * Helper function for setting the test data in the DRBG + * + * @drbg DRBG state handle + * @test_data test data to sets + */ +static inline void drbg_set_testdata(struct drbg_state *drbg, + struct drbg_test_data *test_data) +{ + if (!test_data || !test_data->testentropy) + return; + spin_lock_bh(&drbg->drbg_lock); + drbg->test_data = test_data; + spin_unlock_bh(&drbg->drbg_lock); +} + +/*************************************************************** + * Kernel crypto API cipher invocations requested by DRBG + ***************************************************************/ + +#if defined(CONFIG_CRYPTO_DRBG_HASH) || defined(CONFIG_CRYPTO_DRBG_HMAC) +struct sdesc { + struct shash_desc shash; + char ctx[]; +}; + +static int drbg_init_hash_kernel(struct drbg_state *drbg) +{ + struct sdesc *sdesc; + struct crypto_shash *tfm; + + tfm = crypto_alloc_shash(drbg->core->backend_cra_name, 0, 0); + if (IS_ERR(tfm)) { + pr_info("DRBG: could not allocate digest TFM handle\n"); + return PTR_ERR(tfm); + } + BUG_ON(drbg_blocklen(drbg) != crypto_shash_digestsize(tfm)); + sdesc = kzalloc(sizeof(struct shash_desc) + crypto_shash_descsize(tfm), + GFP_KERNEL); + if (!sdesc) { + crypto_free_shash(tfm); + return -ENOMEM; + } + + sdesc->shash.tfm = tfm; + sdesc->shash.flags = 0; + drbg->priv_data = sdesc; + return 0; +} + +static int drbg_fini_hash_kernel(struct drbg_state *drbg) +{ + struct sdesc *sdesc = (struct sdesc *)drbg->priv_data; + if (sdesc) { + crypto_free_shash(sdesc->shash.tfm); + kzfree(sdesc); + } + drbg->priv_data = NULL; + return 0; +} + +static int drbg_kcapi_hash(struct drbg_state *drbg, const unsigned char *key, + unsigned char *outval, const struct list_head *in) +{ + struct sdesc *sdesc = (struct sdesc *)drbg->priv_data; + struct drbg_string *input = NULL; + + if (key) + crypto_shash_setkey(sdesc->shash.tfm, key, drbg_statelen(drbg)); + 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_init_sym_kernel(struct drbg_state *drbg) +{ + int ret = 0; + struct crypto_blkcipher *tfm; + + tfm = crypto_alloc_blkcipher(drbg->core->backend_cra_name, 0, 0); + if (IS_ERR(tfm)) { + pr_info("DRBG: could not allocate cipher TFM handle\n"); + return PTR_ERR(tfm); + } + BUG_ON(drbg_blocklen(drbg) != crypto_blkcipher_blocksize(tfm)); + drbg->priv_data = tfm; + return ret; +} + +static int drbg_fini_sym_kernel(struct drbg_state *drbg) +{ + struct crypto_blkcipher *tfm = + (struct crypto_blkcipher *)drbg->priv_data; + if (tfm) + crypto_free_blkcipher(tfm); + drbg->priv_data = NULL; + return 0; +} + +static int drbg_kcapi_sym(struct drbg_state *drbg, const unsigned char *key, + unsigned char *outval, const struct drbg_string *in) +{ + int ret = 0; + struct scatterlist sg_in, sg_out; + struct blkcipher_desc desc; + struct crypto_blkcipher *tfm = + (struct crypto_blkcipher *)drbg->priv_data; + + desc.tfm = tfm; + desc.flags = 0; + crypto_blkcipher_setkey(tfm, key, (drbg_keylen(drbg))); + /* there is only component in *in */ + sg_init_one(&sg_in, in->buf, in->len); + sg_init_one(&sg_out, outval, drbg_blocklen(drbg)); + ret = crypto_blkcipher_encrypt(&desc, &sg_out, &sg_in, in->len); + + return ret; +} +#endif /* CONFIG_CRYPTO_DRBG_CTR */ + +/*************************************************************** + * Kernel crypto API interface to register DRBG + ***************************************************************/ + +/* + * Look up the DRBG flags by given kernel crypto API cra_name + * The code uses the drbg_cores definition to do this + * + * @cra_name kernel crypto API cra_name + * @coreref reference to integer which is filled with the pointer to + * the applicable core + * @pr reference for setting prediction resistance + * + * return: flags + */ +static inline void drbg_convert_tfm_core(const char *cra_driver_name, + int *coreref, bool *pr) +{ + int i = 0; + size_t start = 0; + int len = 0; + + *pr = true; + /* disassemble the names */ + if (!memcmp(cra_driver_name, "drbg_nopr_", 10)) { + start = 10; + *pr = false; + } else if (!memcmp(cra_driver_name, "drbg_pr_", 8)) { + start = 8; + } else { + return; + } + + /* remove the first part */ + len = strlen(cra_driver_name) - start; + for (i = 0; ARRAY_SIZE(drbg_cores) > i; i++) { + if (!memcmp(cra_driver_name + start, drbg_cores[i].cra_name, + len)) { + *coreref = i; + return; + } + } +} + +static int drbg_kcapi_init(struct crypto_tfm *tfm) +{ + struct drbg_state *drbg = crypto_tfm_ctx(tfm); + bool pr = false; + int coreref = 0; + + drbg_convert_tfm_core(crypto_tfm_alg_driver_name(tfm), &coreref, &pr); + /* + * when personalization string is needed, the caller must call reset + * and provide the personalization string as seed information + */ + return drbg_instantiate(drbg, NULL, coreref, pr); +} + +static void drbg_kcapi_cleanup(struct crypto_tfm *tfm) +{ + drbg_uninstantiate(crypto_tfm_ctx(tfm)); +} + +/* + * Generate random numbers invoked by the kernel crypto API: + * The API of the kernel crypto API is extended as follows: + * + * If dlen is larger than zero, rdata is interpreted as the output buffer + * where random data is to be stored. + * + * If dlen is zero, rdata is interpreted as a pointer to a struct drbg_gen + * which holds the additional information string that is used for the + * DRBG generation process. The output buffer that is to be used to store + * data is also pointed to by struct drbg_gen. + */ +static int drbg_kcapi_random(struct crypto_rng *tfm, u8 *rdata, + unsigned int dlen) +{ + struct drbg_state *drbg = crypto_rng_ctx(tfm); + if (0 < dlen) { + return drbg_generate_long(drbg, rdata, dlen, NULL); + } else { + struct drbg_gen *data = (struct drbg_gen *)rdata; + struct drbg_string addtl; + /* catch NULL pointer */ + if (!data) + return 0; + drbg_set_testdata(drbg, data->test_data); + /* linked list variable is now local to allow modification */ + drbg_string_fill(&addtl, data->addtl->buf, data->addtl->len); + return drbg_generate_long(drbg, data->outbuf, data->outlen, + &addtl); + } +} + +/* + * Reset the DRBG invoked by the kernel crypto API + * The reset implies a full re-initialization of the DRBG. Similar to the + * generate function of drbg_kcapi_random, this function extends the + * kernel crypto API interface with struct drbg_gen + */ +static int drbg_kcapi_reset(struct crypto_rng *tfm, u8 *seed, unsigned int slen) +{ + struct drbg_state *drbg = crypto_rng_ctx(tfm); + struct crypto_tfm *tfm_base = crypto_rng_tfm(tfm); + bool pr = false; + struct drbg_string seed_string; + int coreref = 0; + + drbg_uninstantiate(drbg); + drbg_convert_tfm_core(crypto_tfm_alg_driver_name(tfm_base), &coreref, + &pr); + if (0 < slen) { + drbg_string_fill(&seed_string, seed, slen); + return drbg_instantiate(drbg, &seed_string, coreref, pr); + } else { + struct drbg_gen *data = (struct drbg_gen *)seed; + /* allow invocation of API call with NULL, 0 */ + if (!data) + return drbg_instantiate(drbg, NULL, coreref, pr); + drbg_set_testdata(drbg, data->test_data); + /* linked list variable is now local to allow modification */ + drbg_string_fill(&seed_string, data->addtl->buf, + data->addtl->len); + 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) +{ +#ifdef CONFIG_CRYPTO_FIPS + int len = 0; +#define OUTBUFLEN 16 + unsigned char buf[OUTBUFLEN]; + struct drbg_state *drbg = NULL; + int ret = -EFAULT; + int rc = -EFAULT; + bool pr = false; + int coreref = 0; + struct drbg_string addtl; + size_t max_addtllen, max_request_bytes; + + /* only perform test in FIPS mode */ + if (!fips_enabled) + return 0; + +#ifdef CONFIG_CRYPTO_DRBG_CTR + drbg_convert_tfm_core("drbg_nopr_ctr_aes128", &coreref, &pr); +#elif 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; + + /* + * if the following tests fail, it is likely that there is a buffer + * overflow as buf is much smaller than the requested or provided + * string lengths -- in case the error handling does not succeed + * we may get an OOPS. And we want to get an OOPS as this is a + * grave bug. + */ + + /* get a valid instance of DRBG for following tests */ + ret = drbg_instantiate(drbg, NULL, coreref, pr); + if (ret) { + rc = ret; + goto outbuf; + } + max_addtllen = drbg_max_addtl(drbg); + max_request_bytes = drbg_max_request_bytes(drbg); + drbg_string_fill(&addtl, buf, max_addtllen + 1); + /* overflow addtllen with additonal info string */ + len = drbg_generate(drbg, buf, OUTBUFLEN, &addtl); + BUG_ON(0 < len); + /* overflow max_bits */ + len = drbg_generate(drbg, buf, (max_request_bytes + 1), NULL); + BUG_ON(0 < len); + drbg_uninstantiate(drbg); + + /* overflow max addtllen with personalization string */ + ret = drbg_instantiate(drbg, &addtl, coreref, pr); + BUG_ON(0 == ret); + /* test uninstantated DRBG */ + len = drbg_generate(drbg, buf, (max_request_bytes + 1), NULL); + BUG_ON(0 < len); + /* all tests passed */ + rc = 0; + + pr_devel("DRBG: Sanity tests for failure code paths successfully " + "completed\n"); + + drbg_uninstantiate(drbg); +outbuf: + kzfree(drbg); + return rc; +#else /* CONFIG_CRYPTO_FIPS */ + return 0; +#endif /* CONFIG_CRYPTO_FIPS */ +} + +static struct crypto_alg drbg_algs[22]; + +/* + * Fill the array drbg_algs used to register the different DRBGs + * with the kernel crypto API. To fill the array, the information + * from drbg_cores[] is used. + */ +static inline void __init drbg_fill_array(struct crypto_alg *alg, + const struct drbg_core *core, int pr) +{ + int pos = 0; + static int priority = 100; + + memset(alg, 0, sizeof(struct crypto_alg)); + memcpy(alg->cra_name, "stdrng", 6); + if (pr) { + memcpy(alg->cra_driver_name, "drbg_pr_", 8); + pos = 8; + } else { + memcpy(alg->cra_driver_name, "drbg_nopr_", 10); + pos = 10; + } + memcpy(alg->cra_driver_name + pos, core->cra_name, + strlen(core->cra_name)); + + alg->cra_priority = priority; + priority++; + /* + * If FIPS mode enabled, the selected DRBG shall have the + * highest cra_priority over other stdrng instances to ensure + * it is selected. + */ + if (fips_enabled) + alg->cra_priority += 200; + + alg->cra_flags = CRYPTO_ALG_TYPE_RNG; + alg->cra_ctxsize = sizeof(struct drbg_state); + alg->cra_type = &crypto_rng_type; + alg->cra_module = THIS_MODULE; + alg->cra_init = drbg_kcapi_init; + alg->cra_exit = drbg_kcapi_cleanup; + alg->cra_u.rng.rng_make_random = drbg_kcapi_random; + alg->cra_u.rng.rng_reset = drbg_kcapi_reset; + alg->cra_u.rng.seedsize = 0; +} + +static int __init drbg_init(void) +{ + unsigned int i = 0; /* pointer to drbg_algs */ + unsigned int j = 0; /* pointer to drbg_cores */ + int ret = -EFAULT; + + ret = drbg_healthcheck_sanity(); + if (ret) + return ret; + + if (ARRAY_SIZE(drbg_cores) * 2 > ARRAY_SIZE(drbg_algs)) { + pr_info("DRBG: Cannot register all DRBG types" + "(slots needed: %zu, slots available: %zu)\n", + ARRAY_SIZE(drbg_cores) * 2, ARRAY_SIZE(drbg_algs)); + return ret; + } + + /* + * each DRBG definition can be used with PR and without PR, thus + * we instantiate each DRBG in drbg_cores[] twice. + * + * As the order of placing them into the drbg_algs array matters + * (the later DRBGs receive a higher cra_priority) we register the + * prediction resistance DRBGs first as the should not be too + * interesting. + */ + for (j = 0; ARRAY_SIZE(drbg_cores) > j; j++, i++) + drbg_fill_array(&drbg_algs[i], &drbg_cores[j], 1); + for (j = 0; ARRAY_SIZE(drbg_cores) > j; j++, i++) + drbg_fill_array(&drbg_algs[i], &drbg_cores[j], 0); + return crypto_register_algs(drbg_algs, (ARRAY_SIZE(drbg_cores) * 2)); +} + +static void __exit drbg_exit(void) +{ + crypto_unregister_algs(drbg_algs, (ARRAY_SIZE(drbg_cores) * 2)); +} + +module_init(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); |
