/* * 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 , 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 #include #include #include #include /*************************************************************** * 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 * HMAC-SHA512 / SHA256 / AES 256 over other ciphers. Thus, the * favored DRBGs are the latest entries in this array. */ static const struct drbg_core drbg_cores[] = { #ifdef CONFIG_CRYPTO_DRBG_CTR { .flags = DRBG_CTR | DRBG_STRENGTH128, .statelen = 32, /* 256 bits as defined in 10.2.1 */ .blocklen_bytes = 16, .cra_name = "ctr_aes128", .backend_cra_name = "aes", }, { .flags = DRBG_CTR | DRBG_STRENGTH192, .statelen = 40, /* 320 bits as defined in 10.2.1 */ .blocklen_bytes = 16, .cra_name = "ctr_aes192", .backend_cra_name = "aes", }, { .flags = DRBG_CTR | DRBG_STRENGTH256, .statelen = 48, /* 384 bits as defined in 10.2.1 */ .blocklen_bytes = 16, .cra_name = "ctr_aes256", .backend_cra_name = "aes", }, #endif /* CONFIG_CRYPTO_DRBG_CTR */ #ifdef CONFIG_CRYPTO_DRBG_HASH { .flags = DRBG_HASH | DRBG_STRENGTH256, .statelen = 111, /* 888 bits */ .blocklen_bytes = 48, .cra_name = "sha384", .backend_cra_name = "sha384", }, { .flags = DRBG_HASH | DRBG_STRENGTH256, .statelen = 111, /* 888 bits */ .blocklen_bytes = 64, .cra_name = "sha512", .backend_cra_name = "sha512", }, { .flags = DRBG_HASH | DRBG_STRENGTH256, .statelen = 55, /* 440 bits */ .blocklen_bytes = 32, .cra_name = "sha256", .backend_cra_name = "sha256", }, #endif /* CONFIG_CRYPTO_DRBG_HASH */ #ifdef CONFIG_CRYPTO_DRBG_HMAC { .flags = DRBG_HMAC | DRBG_STRENGTH256, .statelen = 48, /* block length of cipher */ .blocklen_bytes = 48, .cra_name = "hmac_sha384", .backend_cra_name = "hmac(sha384)", }, { .flags = DRBG_HMAC | DRBG_STRENGTH256, .statelen = 32, /* block length of cipher */ .blocklen_bytes = 32, .cra_name = "hmac_sha256", .backend_cra_name = "hmac(sha256)", }, { .flags = DRBG_HMAC | DRBG_STRENGTH256, .statelen = 64, /* block length of cipher */ .blocklen_bytes = 64, .cra_name = "hmac_sha512", .backend_cra_name = "hmac(sha512)", }, #endif /* CONFIG_CRYPTO_DRBG_HMAC */ }; static int drbg_uninstantiate(struct drbg_state *drbg); /****************************************************************** * Generic helper functions ******************************************************************/ /* * Return strength of DRBG according to SP800-90A section 8.4 * * @flags DRBG flags reference * * Return: normalized strength in *bytes* value or 32 as default * to counter programming errors */ static inline unsigned short drbg_sec_strength(drbg_flag_t flags) { switch (flags & DRBG_STRENGTH_MASK) { case DRBG_STRENGTH128: return 16; case DRBG_STRENGTH192: return 24; case DRBG_STRENGTH256: return 32; default: return 32; } } /* * FIPS 140-2 continuous self test for the noise source * The test is performed on the noise source input data. Thus, the function * implicitly knows the size of the buffer to be equal to the security * strength. * * Note, this function disregards the nonce trailing the entropy data during * initial seeding. * * drbg->drbg_mutex must have been taken. * * @drbg DRBG handle * @entropy buffer of seed data to be checked * * return: * 0 on success * -EAGAIN on when the CTRNG is not yet primed * < 0 on error */ static int drbg_fips_continuous_test(struct drbg_state *drbg, const unsigned char *entropy) { unsigned short entropylen = drbg_sec_strength(drbg->core->flags); int ret = 0; if (!IS_ENABLED(CONFIG_CRYPTO_FIPS)) return 0; /* skip test if we test the overall system */ if (list_empty(&drbg->test_data.list)) return 0; /* only perform test in FIPS mode */ if (!fips_enabled) return 0; if (!drbg->fips_primed) { /* Priming of FIPS test */ memcpy(drbg->prev, entropy, entropylen); drbg->fips_primed = true; /* priming: another round is needed */ return -EAGAIN; } ret = memcmp(drbg->prev, entropy, entropylen); if (!ret) panic("DRBG continuous self test failed\n"); memcpy(drbg->prev, entropy, entropylen); /* the test shall pass when the two values are not equal */ return 0; } /* * Convert an integer into a byte representation of this integer. * The byte representation is big-endian * * @val value to be converted * @buf buffer holding the converted integer -- caller must ensure that * buffer size is at least 32 bit */ #if (defined(CONFIG_CRYPTO_DRBG_HASH) || defined(CONFIG_CRYPTO_DRBG_CTR)) static inline void drbg_cpu_to_be32(__u32 val, unsigned char *buf) { struct s { __be32 conv; }; struct s *conversion = (struct s *) buf; conversion->conv = cpu_to_be32(val); } #endif /* defined(CONFIG_CRYPTO_DRBG_HASH) || defined(CONFIG_CRYPTO_DRBG_CTR) */ /****************************************************************** * CTR DRBG callback functions ******************************************************************/ #ifdef CONFIG_CRYPTO_DRBG_CTR #define CRYPTO_DRBG_CTR_STRING "CTR " MODULE_ALIAS_CRYPTO("drbg_pr_ctr_aes256"); MODULE_ALIAS_CRYPTO("drbg_nopr_ctr_aes256"); MODULE_ALIAS_CRYPTO("drbg_pr_ctr_aes192"); MODULE_ALIAS_CRYPTO("drbg_nopr_ctr_aes192"); MODULE_ALIAS_CRYPTO("drbg_pr_ctr_aes128"); MODULE_ALIAS_CRYPTO("drbg_nopr_ctr_aes128"); static void drbg_kcapi_symsetkey(struct drbg_state *drbg, const unsigned char *key); static int drbg_kcapi_sym(struct drbg_state *drbg, unsigned char *outval, const struct drbg_string *in); static int drbg_init_sym_kernel(struct drbg_state *drbg); static int drbg_fini_sym_kernel(struct drbg_state *drbg); static int drbg_kcapi_sym_ctr(struct drbg_state *drbg, u8 *inbuf, u32 inbuflen, u8 *outbuf, u32 outlen); #define DRBG_OUTSCRATCHLEN 256 /* BCC function for CTR DRBG as defined in 10.4.3 */ static int drbg_ctr_bcc(struct drbg_state *drbg, unsigned char *out, const unsigned char *key, struct list_head *in) { int ret = 0; struct drbg_string *curr = NULL; struct drbg_string data; short cnt = 0; drbg_string_fill(&data, out, drbg_blocklen(drbg)); /* 10.4.3 step 2 / 4 */ drbg_kcapi_symsetkey(drbg, key); list_for_each_entry(curr, in, list) { const unsigned char *pos = curr->buf; size_t len = curr->len; /* 10.4.3 step 4.1 */ while (len) { /* 10.4.3 step 4.2 */ if (drbg_blocklen(drbg) == cnt) { cnt = 0; ret = drbg_kcapi_sym(drbg, out, &data); if (ret) return ret; } out[cnt] ^= *pos; pos++; cnt++; len--; } } /* 10.4.3 step 4.2 for last block */ if (cnt) ret = drbg_kcapi_sym(drbg, out, &data); return ret; } /* * scratchpad usage: drbg_ctr_update is interlinked with drbg_ctr_df * (and drbg_ctr_bcc, but this function does not need any temporary buffers), * the scratchpad is used as follows: * drbg_ctr_update: * temp * start: drbg->scratchpad * length: drbg_statelen(drbg) + drbg_blocklen(drbg) * note: the cipher writing into this variable works * blocklen-wise. Now, when the statelen is not a multiple * of blocklen, the generateion loop below "spills over" * by at most blocklen. Thus, we need to give sufficient * memory. * df_data * start: drbg->scratchpad + * drbg_statelen(drbg) + drbg_blocklen(drbg) * length: drbg_statelen(drbg) * * drbg_ctr_df: * pad * start: df_data + drbg_statelen(drbg) * length: drbg_blocklen(drbg) * iv * start: pad + drbg_blocklen(drbg) * length: drbg_blocklen(drbg) * temp * start: iv + drbg_blocklen(drbg) * length: drbg_satelen(drbg) + drbg_blocklen(drbg) * note: temp is the buffer that the BCC function operates * on. BCC operates blockwise. drbg_statelen(drbg) * is sufficient when the DRBG state length is a multiple * of the block size. For AES192 (and maybe other ciphers) * this is not correct and the length for temp is * insufficient (yes, that also means for such ciphers, * the final output of all BCC rounds are truncated). * Therefore, add drbg_blocklen(drbg) to cover all * possibilities. */ /* Derivation Function for CTR DRBG as defined in 10.4.2 */ static int drbg_ctr_df(struct drbg_state *drbg, unsigned char *df_data, size_t bytes_to_return, struct list_head *seedlist) { int ret = -EFAULT; unsigned char L_N[8]; /* S3 is input */ struct drbg_string S1, S2, S4, cipherin; LIST_HEAD(bcc_list); unsigned char *pad = df_data + drbg_statelen(drbg); unsigned char *iv = pad + drbg_blocklen(drbg); unsigned char *temp = iv + drbg_blocklen(drbg); size_t padlen = 0; unsigned int templen = 0; /* 10.4.2 step 7 */ unsigned int i = 0; /* 10.4.2 step 8 */ const unsigned char *K = (unsigned char *) "\x00\x01\x02\x03\x04\x05\x06\x07" "\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f" "\x10\x11\x12\x13\x14\x15\x16\x17" "\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f"; unsigned char *X; size_t generated_len = 0; size_t inputlen = 0; struct drbg_string *seed = NULL; memset(pad, 0, drbg_blocklen(drbg)); memset(iv, 0, drbg_blocklen(drbg)); /* 10.4.2 step 1 is implicit as we work byte-wise */ /* 10.4.2 step 2 */ if ((512/8) < bytes_to_return) return -EINVAL; /* 10.4.2 step 2 -- calculate the entire length of all input data */ list_for_each_entry(seed, seedlist, list) inputlen += seed->len; drbg_cpu_to_be32(inputlen, &L_N[0]); /* 10.4.2 step 3 */ drbg_cpu_to_be32(bytes_to_return, &L_N[4]); /* 10.4.2 step 5: length is L_N, input_string, one byte, padding */ padlen = (inputlen + sizeof(L_N) + 1) % (drbg_blocklen(drbg)); /* wrap the padlen appropriately */ if (padlen) padlen = drbg_blocklen(drbg) - padlen; /* * pad / padlen contains the 0x80 byte and the following zero bytes. * As the calculated padlen value only covers the number of zero * bytes, this value has to be incremented by one for the 0x80 byte. */ padlen++; pad[0] = 0x80; /* 10.4.2 step 4 -- first fill the linked list and then order it */ drbg_string_fill(&S1, iv, drbg_blocklen(drbg)); list_add_tail(&S1.list, &bcc_list); drbg_string_fill(&S2, L_N, sizeof(L_N)); list_add_tail(&S2.list, &bcc_list); list_splice_tail(seedlist, &bcc_list); drbg_string_fill(&S4, pad, padlen); list_add_tail(&S4.list, &bcc_list); /* 10.4.2 step 9 */ while (templen < (drbg_keylen(drbg) + (drbg_blocklen(drbg)))) { /* * 10.4.2 step 9.1 - the padding is implicit as the buffer * holds zeros after allocation -- even the increment of i * is irrelevant as the increment remains within length of i */ drbg_cpu_to_be32(i, iv); /* 10.4.2 step 9.2 -- BCC and concatenation with temp */ ret = drbg_ctr_bcc(drbg, temp + templen, K, &bcc_list); if (ret) goto out; /* 10.4.2 step 9.3 */ i++; templen += drbg_blocklen(drbg); } /* 10.4.2 step 11 */ X = temp + (drbg_keylen(drbg)); drbg_string_fill(&cipherin, X, drbg_blocklen(drbg)); /* 10.4.2 step 12: overwriting of outval is implemented in next step */ /* 10.4.2 step 13 */ drbg_kcapi_symsetkey(drbg, temp); while (generated_len < bytes_to_return) { short blocklen = 0; /* * 10.4.2 step 13.1: the truncation of the key length is * implicit as the key is only drbg_blocklen in size based on * the implementation of the cipher function callback */ ret = drbg_kcapi_sym(drbg, X, &cipherin); if (ret) goto out; blocklen = (drbg_blocklen(drbg) < (bytes_to_return - generated_len)) ? drbg_blocklen(drbg) : (bytes_to_return - generated_len); /* 10.4.2 step 13.2 and 14 */ memcpy(df_data + generated_len, X, blocklen); generated_len += blocklen; } ret = 0; out: memset(iv, 0, drbg_blocklen(drbg)); memset(temp, 0, drbg_statelen(drbg) + drbg_blocklen(drbg)); memset(pad, 0, drbg_blocklen(drbg)); return ret; } /* * update function of CTR DRBG as defined in 10.2.1.2 * * The reseed variable has an enhanced meaning compared to the update * functions of the other DRBGs as follows: * 0 => initial seed from initialization * 1 => reseed via drbg_seed * 2 => first invocation from drbg_ctr_update when addtl is present. In * this case, the df_data scratchpad is not deleted so that it is * available for another calls to prevent calling the DF function * again. * 3 => second invocation from drbg_ctr_update. When the update function * was called with addtl, the df_data memory already contains the * DFed addtl information and we do not need to call DF again. */ static int drbg_ctr_update(struct drbg_state *drbg, struct list_head *seed, int reseed) { int ret = -EFAULT; /* 10.2.1.2 step 1 */ unsigned char *temp = drbg->scratchpad; unsigned char *df_data = drbg->scratchpad + drbg_statelen(drbg) + drbg_blocklen(drbg); if (3 > reseed) memset(df_data, 0, drbg_statelen(drbg)); if (!reseed) { /* * The DRBG uses the CTR mode of the underlying AES cipher. The * CTR mode increments the counter value after the AES operation * but SP800-90A requires that the counter is incremented before * the AES operation. Hence, we increment it at the time we set * it by one. */ crypto_inc(drbg->V, drbg_blocklen(drbg)); ret = crypto_skcipher_setkey(drbg->ctr_handle, drbg->C, drbg_keylen(drbg)); if (ret) goto out; } /* 10.2.1.3.2 step 2 and 10.2.1.4.2 step 2 */ if (seed) { ret = drbg_ctr_df(drbg, df_data, drbg_statelen(drbg), seed); if (ret) goto out; } ret = drbg_kcapi_sym_ctr(drbg, df_data, drbg_statelen(drbg), temp, drbg_statelen(drbg)); if (ret) return ret; /* 10.2.1.2 step 5 */ ret = crypto_skcipher_setkey(drbg->ctr_handle, temp, drbg_keylen(drbg)); if (ret) goto out; /* 10.2.1.2 step 6 */ memcpy(drbg->V, temp + drbg_keylen(drbg), drbg_blocklen(drbg)); /* See above: increment counter by one to compensate timing of CTR op */ crypto_inc(drbg->V, drbg_blocklen(drbg)); ret = 0; out: memset(temp, 0, drbg_statelen(drbg) + drbg_blocklen(drbg)); if (2 != reseed) memset(df_data, 0, drbg_statelen(drbg)); return ret; } /* * scratchpad use: drbg_ctr_update is called independently from * drbg_ctr_extract_bytes. Therefore, the scratchpad is reused */ /* Generate function of CTR DRBG as defined in 10.2.1.5.2 */ static int drbg_ctr_generate(struct drbg_state *drbg, unsigned char *buf, unsigned int buflen, struct list_head *addtl) { int ret; int len = min_t(int, buflen, INT_MAX); /* 10.2.1.5.2 step 2 */ if (addtl && !list_empty(addtl)) { ret = drbg_ctr_update(drbg, addtl, 2); if (ret) return 0; } /* 10.2.1.5.2 step 4.1 */ ret = drbg_kcapi_sym_ctr(drbg, NULL, 0, buf, len); if (ret) return ret; /* 10.2.1.5.2 step 6 */ ret = drbg_ctr_update(drbg, NULL, 3); if (ret) len = ret; return len; } static const struct drbg_state_ops drbg_ctr_ops = { .update = drbg_ctr_update, .generate = drbg_ctr_generate, .crypto_init = drbg_init_sym_kernel, .crypto_fini = drbg_fini_sym_kernel, }; #endif /* CONFIG_CRYPTO_DRBG_CTR */ /****************************************************************** * HMAC DRBG callback functions ******************************************************************/ #if defined(CONFIG_CRYPTO_DRBG_HASH) || defined(CONFIG_CRYPTO_DRBG_HMAC) static int drbg_kcapi_hash(struct drbg_state *drbg, unsigned char *outval, const struct list_head *in); static void drbg_kcapi_hmacsetkey(struct drbg_state *drbg, const unsigned char *key); static int drbg_init_hash_kernel(struct drbg_state *drbg); static int drbg_fini_hash_kernel(struct drbg_state *drbg); #endif /* (CONFIG_CRYPTO_DRBG_HASH || CONFIG_CRYPTO_DRBG_HMAC) */ #ifdef CONFIG_CRYPTO_DRBG_HMAC #define CRYPTO_DRBG_HMAC_STRING "HMAC " MODULE_ALIAS_CRYPTO("drbg_pr_hmac_sha512"); MODULE_ALIAS_CRYPTO("drbg_nopr_hmac_sha512"); MODULE_ALIAS_CRYPTO("drbg_pr_hmac_sha384"); MODULE_ALIAS_CRYPTO("drbg_nopr_hmac_sha384"); MODULE_ALIAS_CRYPTO("drbg_pr_hmac_sha256"); MODULE_ALIAS_CRYPTO("drbg_nopr_hmac_sha256"); /* update function of HMAC DRBG as defined in 10.1.2.2 */ static int drbg_hmac_update(struct drbg_state *drbg, struct list_head *seed, int reseed) { int ret = -EFAULT; int i = 0; struct drbg_string seed1, seed2, vdata; LIST_HEAD(seedlist); LIST_HEAD(vdatalist); if (!reseed) { /* 10.1.2.3 step 2 -- memset(0) of C is implicit with kzalloc */ memset(drbg->V, 1, drbg_statelen(drbg)); drbg_kcapi_hmacsetkey(drbg, drbg->C); } drbg_string_fill(&seed1, drbg->V, drbg_statelen(drbg)); list_add_tail(&seed1.list, &seedlist); /* buffer of seed2 will be filled in for loop below with one byte */ drbg_string_fill(&seed2, NULL, 1); list_add_tail(&seed2.list, &seedlist); /* input data of seed is allowed to be NULL at this point */ if (seed) list_splice_tail(seed, &seedlist); drbg_string_fill(&vdata, drbg->V, drbg_statelen(drbg)); list_add_tail(&vdata.list, &vdatalist); for (i = 2; 0 < i; i--) { /* first round uses 0x0, second 0x1 */ unsigned char prefix = DRBG_PREFIX0; if (1 == i) prefix = DRBG_PREFIX1; /* 10.1.2.2 step 1 and 4 -- concatenation and HMAC for key */ seed2.buf = &prefix; ret = drbg_kcapi_hash(drbg, drbg->C, &seedlist); if (ret) return ret; drbg_kcapi_hmacsetkey(drbg, drbg->C); /* 10.1.2.2 step 2 and 5 -- HMAC for V */ ret = drbg_kcapi_hash(drbg, drbg->V, &vdatalist); if (ret) return ret; /* 10.1.2.2 step 3 */ if (!seed) return ret; } return 0; } /* generate function of HMAC DRBG as defined in 10.1.2.5 */ static int drbg_hmac_generate(struct drbg_state *drbg, unsigned char *buf, unsigned int buflen, struct list_head *addtl) { int len = 0; int ret = 0; struct drbg_string data; LIST_HEAD(datalist); /* 10.1.2.5 step 2 */ if (addtl && !list_empty(addtl)) { ret = drbg_hmac_update(drbg, addtl, 1); if (ret) return ret; } drbg_string_fill(&data, drbg->V, drbg_statelen(drbg)); list_add_tail(&data.list, &datalist); while (len < buflen) { unsigned int outlen = 0; /* 10.1.2.5 step 4.1 */ ret = drbg_kcapi_hash(drbg, drbg->V, &datalist); if (ret) return ret; outlen = (drbg_blocklen(drbg) < (buflen - len)) ? drbg_blocklen(drbg) : (buflen - len); /* 10.1.2.5 step 4.2 */ memcpy(buf + len, drbg->V, outlen); len += outlen; } /* 10.1.2.5 step 6 */ if (addtl && !list_empty(addtl)) ret = drbg_hmac_update(drbg, addtl, 1); else ret = drbg_hmac_update(drbg, NULL, 1); if (ret) return ret; return len; } static const struct drbg_state_ops drbg_hmac_ops = { .update = drbg_hmac_update, .generate = drbg_hmac_generate, .crypto_init = drbg_init_hash_kernel, .crypto_fini = drbg_fini_hash_kernel, }; #endif /* CONFIG_CRYPTO_DRBG_HMAC */ /****************************************************************** * Hash DRBG callback functions ******************************************************************/ #ifdef CONFIG_CRYPTO_DRBG_HASH #define CRYPTO_DRBG_HASH_STRING "HASH " MODULE_ALIAS_CRYPTO("drbg_pr_sha512"); MODULE_ALIAS_CRYPTO("drbg_nopr_sha512"); MODULE_ALIAS_CRYPTO("drbg_pr_sha384"); MODULE_ALIAS_CRYPTO("drbg_nopr_sha384"); MODULE_ALIAS_CRYPTO("drbg_pr_sha256"); MODULE_ALIAS_CRYPTO("drbg_nopr_sha256"); /* * Increment buffer * * @dst buffer to increment * @add value to add */ static inline void drbg_add_buf(unsigned char *dst, size_t dstlen, const unsigned char *add, size_t addlen) { /* implied: dstlen > addlen */ unsigned char *dstptr; const unsigned char *addptr; unsigned int remainder = 0; size_t len = addlen; dstptr = dst + (dstlen-1); addptr = add + (addlen-1); while (len) { remainder += *dstptr + *addptr; *dstptr = remainder & 0xff; remainder >>= 8; len--; dstptr--; addptr--; } len = dstlen - addlen; while (len && remainder > 0) { remainder = *dstptr + 1; *dstptr = remainder & 0xff; remainder >>= 8; len--; dstptr--; } } /* * scratchpad usage: as drbg_hash_update and drbg_hash_df are used * interlinked, the scratchpad is used as follows: * drbg_hash_update * start: drbg->scratchpad * length: drbg_statelen(drbg) * drbg_hash_df: * start: drbg->scratchpad + drbg_statelen(drbg) * length: drbg_blocklen(drbg) * * drbg_hash_process_addtl uses the scratchpad, but fully completes * before either of the functions mentioned before are invoked. Therefore, * drbg_hash_process_addtl does not need to be specifically considered. */ /* Derivation Function for Hash DRBG as defined in 10.4.1 */ static int drbg_hash_df(struct drbg_state *drbg, unsigned char *outval, size_t outlen, struct list_head *entropylist) { int ret = 0; size_t len = 0; unsigned char input[5]; unsigned char *tmp = drbg->scratchpad + drbg_statelen(drbg); struct drbg_string data; /* 10.4.1 step 3 */ input[0] = 1; drbg_cpu_to_be32((outlen * 8), &input[1]); /* 10.4.1 step 4.1 -- concatenation of data for input into hash */ drbg_string_fill(&data, input, 5); list_add(&data.list, entropylist); /* 10.4.1 step 4 */ while (len < outlen) { short blocklen = 0; /* 10.4.1 step 4.1 */ ret = drbg_kcapi_hash(drbg, tmp, entropylist); if (ret) goto out; /* 10.4.1 step 4.2 */ input[0]++; blocklen = (drbg_blocklen(drbg) < (outlen - len)) ? drbg_blocklen(drbg) : (outlen - len); memcpy(outval + len, tmp, blocklen); len += blocklen; } out: memset(tmp, 0, drbg_blocklen(drbg)); return ret; } /* update function for Hash DRBG as defined in 10.1.1.2 / 10.1.1.3 */ static int drbg_hash_update(struct drbg_state *drbg, struct list_head *seed, int reseed) { int ret = 0; struct drbg_string data1, data2; LIST_HEAD(datalist); LIST_HEAD(datalist2); unsigned char *V = drbg->scratchpad; unsigned char prefix = DRBG_PREFIX1; if (!seed) return -EINVAL; if (reseed) { /* 10.1.1.3 step 1 */ memcpy(V, drbg->V, drbg_statelen(drbg)); drbg_string_fill(&data1, &prefix, 1); list_add_tail(&data1.list, &datalist); drbg_string_fill(&data2, V, drbg_statelen(drbg)); list_add_tail(&data2.list, &datalist); } list_splice_tail(seed, &datalist); /* 10.1.1.2 / 10.1.1.3 step 2 and 3 */ ret = drbg_hash_df(drbg, drbg->V, drbg_statelen(drbg), &datalist); if (ret) goto out; /* 10.1.1.2 / 10.1.1.3 step 4 */ prefix = DRBG_PREFIX0; drbg_string_fill(&data1, &prefix, 1); list_add_tail(&data1.list, &datalist2); drbg_string_fill(&data2, drbg->V, drbg_statelen(drbg)); list_add_tail(&data2.list, &datalist2); /* 10.1.1.2 / 10.1.1.3 step 4 */ ret = drbg_hash_df(drbg, drbg->C, drbg_statelen(drbg), &datalist2); out: memset(drbg->scratchpad, 0, drbg_statelen(drbg)); return ret; } /* processing of additional information string for Hash DRBG */ static int drbg_hash_process_addtl(struct drbg_state *drbg, struct list_head *addtl) { int ret = 0; struct drbg_string data1, data2; LIST_HEAD(datalist); unsigned char prefix = DRBG_PREFIX2; /* 10.1.1.4 step 2 */ if (!addtl || list_empty(addtl)) return 0; /* 10.1.1.4 step 2a */ drbg_string_fill(&data1, &prefix, 1); drbg_string_fill(&data2, drbg->V, drbg_statelen(drbg)); list_add_tail(&data1.list, &datalist); list_add_tail(&data2.list, &datalist); list_splice_tail(addtl, &datalist); ret = drbg_kcapi_hash(drbg, drbg->scratchpad, &datalist); if (ret) goto out; /* 10.1.1.4 step 2b */ drbg_add_buf(drbg->V, drbg_statelen(drbg), drbg->scratchpad, drbg_blocklen(drbg)); out: memset(drbg->scratchpad, 0, drbg_blocklen(drbg)); return ret; } /* Hashgen defined in 10.1.1.4 */ static int drbg_hash_hashgen(struct drbg_state *drbg, unsigned char *buf, unsigned int buflen) { int len = 0; int ret = 0; unsigned char *src = drbg->scratchpad; unsigned char *dst = drbg->scratchpad + drbg_statelen(drbg); struct drbg_string data; LIST_HEAD(datalist); /* 10.1.1.4 step hashgen 2 */ memcpy(src, drbg->V, drbg_statelen(drbg)); drbg_string_fill(&data, src, drbg_statelen(drbg)); list_add_tail(&data.list, &datalist); while (len < buflen) { unsigned int outlen = 0; /* 10.1.1.4 step hashgen 4.1 */ ret = drbg_kcapi_hash(drbg, dst, &datalist); if (ret) { len = ret; goto out; } outlen = (drbg_blocklen(drbg) < (buflen - len)) ? drbg_blocklen(drbg) : (buflen - len); /* 10.1.1.4 step hashgen 4.2 */ memcpy(buf + len, dst, outlen); len += outlen; /* 10.1.1.4 hashgen step 4.3 */ if (len < buflen) crypto_inc(src, drbg_statelen(drbg)); } out: memset(drbg->scratchpad, 0, (drbg_statelen(drbg) + drbg_blocklen(drbg))); return len; } /* generate function for Hash DRBG as defined in 10.1.1.4 */ static int drbg_hash_generate(struct drbg_state *drbg, unsigned char *buf, unsigned int buflen, struct list_head *addtl) { int len = 0; int ret = 0; union { unsigned char req[8]; __be64 req_int; } u; unsigned char prefix = DRBG_PREFIX3; struct drbg_string data1, data2; LIST_HEAD(datalist); /* 10.1.1.4 step 2 */ ret = drbg_hash_process_addtl(drbg, addtl); if (ret) return ret; /* 10.1.1.4 step 3 */ len = drbg_hash_hashgen(drbg, buf, buflen); /* this is the value H as documented in 10.1.1.4 */ /* 10.1.1.4 step 4 */ drbg_string_fill(&data1, &prefix, 1); list_add_tail(&data1.list, &datalist); drbg_string_fill(&data2, drbg->V, drbg_statelen(drbg)); list_add_tail(&data2.list, &datalist); ret = drbg_kcapi_hash(drbg, drbg->scratchpad, &datalist); if (ret) { len = ret; goto out; } /* 10.1.1.4 step 5 */ drbg_add_buf(drbg->V, drbg_statelen(drbg), drbg->scratchpad, drbg_blocklen(drbg)); drbg_add_buf(drbg->V, drbg_statelen(drbg), drbg->C, drbg_statelen(drbg)); u.req_int = cpu_to_be64(drbg->reseed_ctr); drbg_add_buf(drbg->V, drbg_statelen(drbg), u.req, 8); out: memset(drbg->scratchpad, 0, drbg_blocklen(drbg)); return len; } /* * scratchpad usage: as update and generate are used isolated, both * can use the scratchpad */ static const struct drbg_state_ops drbg_hash_ops = { .update = drbg_hash_update, .generate = drbg_hash_generate, .crypto_init = drbg_init_hash_kernel, .crypto_fini = drbg_fini_hash_kernel, }; #endif /* CONFIG_CRYPTO_DRBG_HASH */ /****************************************************************** * Functions common for DRBG implementations ******************************************************************/ static inline int __drbg_seed(struct drbg_state *drbg, struct list_head *seed, int reseed, enum drbg_seed_state new_seed_state) { int ret = drbg->d_ops->update(drbg, seed, reseed); if (ret) return ret; drbg->seeded = new_seed_state; drbg->last_seed_time = jiffies; /* 10.1.1.2 / 10.1.1.3 step 5 */ drbg->reseed_ctr = 1; switch (drbg->seeded) { case DRBG_SEED_STATE_UNSEEDED: /* Impossible, but handle it to silence compiler warnings. */ fallthrough; case DRBG_SEED_STATE_PARTIAL: /* * Require frequent reseeds until the seed source is * fully initialized. */ drbg->reseed_threshold = 50; break; case DRBG_SEED_STATE_FULL: /* * Seed source has become fully initialized, frequent * reseeds no longer required. */ drbg->reseed_threshold = drbg_max_requests(drbg); break; } return ret; } static inline int drbg_get_random_bytes(struct drbg_state *drbg, unsigned char *entropy, unsigned int entropylen) { int ret; do { get_random_bytes(entropy, entropylen); ret = drbg_fips_continuous_test(drbg, entropy); if (ret && ret != -EAGAIN) return ret; } while (ret); return 0; } static int drbg_seed_from_random(struct drbg_state *drbg) { struct drbg_string data; LIST_HEAD(seedlist); unsigned int entropylen = drbg_sec_strength(drbg->core->flags); unsigned char entropy[32]; int ret; BUG_ON(!entropylen); BUG_ON(entropylen > sizeof(entropy)); drbg_string_fill(&data, entropy, entropylen); list_add_tail(&data.list, &seedlist); ret = drbg_get_random_bytes(drbg, entropy, entropylen); if (ret) goto out; ret = __drbg_seed(drbg, &seedlist, true, DRBG_SEED_STATE_FULL); out: memzero_explicit(entropy, entropylen); return ret; } static bool drbg_nopr_reseed_interval_elapsed(struct drbg_state *drbg) { unsigned long next_reseed; /* Don't ever reseed from get_random_bytes() in test mode. */ if (list_empty(&drbg->test_data.list)) return false; /* * Obtain fresh entropy for the nopr DRBGs after 300s have * elapsed in order to still achieve sort of partial * prediction resistance over the time domain at least. Note * that the period of 300s has been chosen to match the * CRNG_RESEED_INTERVAL of the get_random_bytes()' chacha * rngs. */ next_reseed = drbg->last_seed_time + 300 * HZ; return time_after(jiffies, next_reseed); } /* * Seeding or reseeding of the DRBG * * @drbg: DRBG state struct * @pers: personalization / additional information buffer * @reseed: 0 for initial seed process, 1 for reseeding * * return: * 0 on success * error value otherwise */ static int drbg_seed(struct drbg_state *drbg, struct drbg_string *pers, bool reseed) { int ret; unsigned char entropy[((32 + 16) * 2)]; unsigned int entropylen = drbg_sec_strength(drbg->core->flags); struct drbg_string data1; LIST_HEAD(seedlist); enum drbg_seed_state new_seed_state = DRBG_SEED_STATE_FULL; /* 9.1 / 9.2 / 9.3.1 step 3 */ if (pers && pers->len > (drbg_max_addtl(drbg))) { pr_devel("DRBG: personalization string too long %zu\n", pers->len); return -EINVAL; } if (list_empty(&drbg->test_data.list)) { drbg_string_fill(&data1, drbg->test_data.buf, drbg->test_data.len); pr_devel("DRBG: using test entropy\n"); } else { /* * Gather entropy equal to the security strength of the DRBG. * With a derivation function, a nonce is required in addition * to the entropy. A nonce must be at least 1/2 of the security * strength of the DRBG in size. Thus, entropy + nonce is 3/2 * of the strength. The consideration of a nonce is only * applicable during initial seeding. */ BUG_ON(!entropylen); if (!reseed) entropylen = ((entropylen + 1) / 2) * 3; BUG_ON((entropylen * 2) > sizeof(entropy)); /* Get seed from in-kernel /dev/urandom */ if (!rng_is_initialized()) new_seed_state = DRBG_SEED_STATE_PARTIAL; ret = drbg_get_random_bytes(drbg, entropy, entropylen); if (ret) goto out; if (!drbg->jent) { drbg_string_fill(&data1, entropy, entropylen); pr_devel("DRBG: (re)seeding with %u bytes of entropy\n", entropylen); } else { /* * Get seed from Jitter RNG, failures are * fatal only in FIPS mode. */ ret = crypto_rng_get_bytes(drbg->jent, entropy + entropylen, entropylen); if (fips_enabled && ret) { pr_devel("DRBG: jent failed with %d\n", ret); /* * Do not treat the transient failure of the * Jitter RNG as an error that needs to be * reported. The combined number of the * maximum reseed threshold times the maximum * number of Jitter RNG transient errors is * less than the reseed threshold required by * SP800-90A allowing us to treat the * transient errors as such. * * However, we mandate that at least the first * seeding operation must succeed with the * Jitter RNG. */ if (!reseed || ret != -EAGAIN) goto out; } drbg_string_fill(&data1, entropy, entropylen * 2); pr_devel("DRBG: (re)seeding with %u bytes of entropy\n", entropylen * 2); } } list_add_tail(&data1.list, &seedlist); /* * concatenation of entropy with personalization str / addtl input) * the variable pers is directly handed in by the caller, so check its * contents whether it is appropriate */ if (pers && pers->buf && 0 < pers->len) { list_add_tail(&pers->list, &seedlist); pr_devel("DRBG: using personalization string\n"); } if (!reseed) { memset(drbg->V, 0, drbg_statelen(drbg)); memset(drbg->C, 0, drbg_statelen(drbg)); } ret = __drbg_seed(drbg, &seedlist, reseed, new_seed_state); out: memzero_explicit(entropy, entropylen * 2); return ret; } /* Free all substructures in a DRBG state without the DRBG state structure */ static inline void drbg_dealloc_state(struct drbg_state *drbg) { if (!drbg) return; kfree_sensitive(drbg->Vbuf); drbg->Vbuf = NULL; drbg->V = NULL; kfree_sensitive(drbg->Cbuf); drbg->Cbuf = NULL; drbg->C = NULL; kfree_sensitive(drbg->scratchpadbuf); drbg->scratchpadbuf = NULL; drbg->reseed_ctr = 0; drbg->d_ops = NULL; drbg->core = NULL; if (IS_ENABLED(CONFIG_CRYPTO_FIPS)) { kfree_sensitive(drbg->prev); drbg->prev = NULL; drbg->fips_primed = false; } } /* * Allocate all sub-structures for a DRBG state. * The DRBG state structure must already be allocated. */ static inline int drbg_alloc_state(struct drbg_state *drbg) { int ret = -ENOMEM; unsigned int sb_size = 0; switch (drbg->core->flags & DRBG_TYPE_MASK) { #ifdef CONFIG_CRYPTO_DRBG_HMAC case DRBG_HMAC: drbg->d_ops = &drbg_hmac_ops; break; #endif /* CONFIG_CRYPTO_DRBG_HMAC */ #ifdef CONFIG_CRYPTO_DRBG_HASH case DRBG_HASH: drbg->d_ops = &drbg_hash_ops; break; #endif /* CONFIG_CRYPTO_DRBG_HASH */ #ifdef CONFIG_CRYPTO_DRBG_CTR case DRBG_CTR: drbg->d_ops = &drbg_ctr_ops; break; #endif /* CONFIG_CRYPTO_DRBG_CTR */ default: ret = -EOPNOTSUPP; goto err; } ret = drbg->d_ops->crypto_init(drbg); if (ret < 0) goto err; drbg->Vbuf = kmalloc(drbg_statelen(drbg) + ret, GFP_KERNEL); if (!drbg->Vbuf) { ret = -ENOMEM; goto fini; } drbg->V = PTR_ALIGN(drbg->Vbuf, ret + 1); drbg->Cbuf = kmalloc(drbg_statelen(drbg) + ret, GFP_KERNEL); if (!drbg->Cbuf) { ret = -ENOMEM; goto fini; } drbg->C = PTR_ALIGN(drbg->Cbuf, ret + 1); /* scratchpad is only generated for CTR and Hash */ if (drbg->core->flags & DRBG_HMAC) sb_size = 0; else if (drbg->core->flags & DRBG_CTR) sb_size = drbg_statelen(drbg) + drbg_blocklen(drbg) + /* temp */ drbg_statelen(drbg) + /* df_data */ drbg_blocklen(drbg) + /* pad */ drbg_blocklen(drbg) + /* iv */ drbg_statelen(drbg) + drbg_blocklen(drbg); /* temp */ else sb_size = drbg_statelen(drbg) + drbg_blocklen(drbg); if (0 < sb_size) { drbg->scratchpadbuf = kzalloc(sb_size + ret, GFP_KERNEL); if (!drbg->scratchpadbuf) { ret = -ENOMEM; goto fini; } drbg->scratchpad = PTR_ALIGN(drbg->scratchpadbuf, ret + 1); } if (IS_ENABLED(CONFIG_CRYPTO_FIPS)) { drbg->prev = kzalloc(drbg_sec_strength(drbg->core->flags), GFP_KERNEL); if (!drbg->prev) { ret = -ENOMEM; goto fini; } drbg->fips_primed = false; } return 0; fini: drbg->d_ops->crypto_fini(drbg); err: drbg_dealloc_state(drbg); return ret; } /************************************************************************* * DRBG interface functions *************************************************************************/ /* * DRBG generate function as required by SP800-90A - this function * generates random numbers * * @drbg DRBG state handle * @buf Buffer where to store the random numbers -- the buffer must already * be pre-allocated by caller * @buflen Length of output buffer - this value defines the number of random * bytes pulled from DRBG * @addtl Additional input that is mixed into state, may be NULL -- note * the entropy is pulled by the DRBG internally unconditionally * as defined in SP800-90A. The additional input is mixed into * the state in addition to the pulled entropy. * * return: 0 when all bytes are generated; < 0 in case of an error */ static int drbg_generate(struct drbg_state *drbg, unsigned char *buf, unsigned int buflen, struct drbg_string *addtl) { int len = 0; LIST_HEAD(addtllist); if (!drbg->core) { pr_devel("DRBG: not yet seeded\n"); return -EINVAL; } if (0 == buflen || !buf) { pr_devel("DRBG: no output buffer provided\n"); return -EINVAL; } if (addtl && NULL == addtl->buf && 0 < addtl->len) { pr_devel("DRBG: wrong format of additional information\n"); return -EINVAL; } /* 9.3.1 step 2 */ len = -EINVAL; if (buflen > (drbg_max_request_bytes(drbg))) { pr_devel("DRBG: requested random numbers too large %u\n", buflen); goto err; } /* 9.3.1 step 3 is implicit with the chosen DRBG */ /* 9.3.1 step 4 */ if (addtl && addtl->len > (drbg_max_addtl(drbg))) { pr_devel("DRBG: additional information string too long %zu\n", addtl->len); goto err; } /* 9.3.1 step 5 is implicit with the chosen DRBG */ /* * 9.3.1 step 6 and 9 supplemented by 9.3.2 step c is implemented * here. The spec is a bit convoluted here, we make it simpler. */ if (drbg->reseed_threshold < drbg->reseed_ctr) drbg->seeded = DRBG_SEED_STATE_UNSEEDED; if (drbg->pr || drbg->seeded == DRBG_SEED_STATE_UNSEEDED) { pr_devel("DRBG: reseeding before generation (prediction " "resistance: %s, state %s)\n", str_true_false(drbg->pr), (drbg->seeded == DRBG_SEED_STATE_FULL ? "seeded" : "unseeded")); /* 9.3.1 steps 7.1 through 7.3 */ len = drbg_seed(drbg, addtl, true); if (len) goto err; /* 9.3.1 step 7.4 */ addtl = NULL; } else if (rng_is_initialized() && (drbg->seeded == DRBG_SEED_STATE_PARTIAL || drbg_nopr_reseed_interval_elapsed(drbg))) { len = drbg_seed_from_random(drbg); if (len) goto err; } if (addtl && 0 < addtl->len) list_add_tail(&addtl->list, &addtllist); /* 9.3.1 step 8 and 10 */ len = drbg->d_ops->generate(drbg, buf, buflen, &addtllist); /* 10.1.1.4 step 6, 10.1.2.5 step 7, 10.2.1.5.2 step 7 */ drbg->reseed_ctr++; if (0 >= len) goto err; /* * Section 11.3.3 requires to re-perform self tests after some * generated random numbers. The chosen value after which self * test is performed is arbitrary, but it should be reasonable. * However, we do not perform the self tests because of the following * reasons: it is mathematically impossible that the initial self tests * were successfully and the following are not. If the initial would * pass and the following would not, the kernel integrity is violated. * In this case, the entire kernel operation is questionable and it * is unlikely that the integrity violation only affects the * correct operation of the DRBG. * * Albeit the following code is commented out, it is provided in * case somebody has a need to implement the test of 11.3.3. */ #if 0 if (drbg->reseed_ctr && !(drbg->reseed_ctr % 4096)) { int err = 0; pr_devel("DRBG: start to perform self test\n"); if (drbg->core->flags & DRBG_HMAC) err = alg_test("drbg_pr_hmac_sha512", "drbg_pr_hmac_sha512", 0, 0); else if (drbg->core->flags & DRBG_CTR) err = alg_test("drbg_pr_ctr_aes256", "drbg_pr_ctr_aes256", 0, 0); else err = alg_test("drbg_pr_sha256", "drbg_pr_sha256", 0, 0); if (err) { pr_err("DRBG: periodical self test failed\n"); /* * uninstantiate implies that from now on, only errors * are returned when reusing this DRBG cipher handle */ drbg_uninstantiate(drbg); return 0; } else { pr_devel("DRBG: self test successful\n"); } } #endif /* * All operations were successful, return 0 as mandated by * the kernel crypto API interface. */ len = 0; err: return len; } /* * Wrapper around drbg_generate which can pull arbitrary long strings * from the DRBG without hitting the maximum request limitation. * * Parameters: see drbg_generate * Return codes: see drbg_generate -- if one drbg_generate request fails, * the entire drbg_generate_long request fails */ static int drbg_generate_long(struct drbg_state *drbg, unsigned char *buf, unsigned int buflen, struct drbg_string *addtl) { unsigned int len = 0; unsigned int slice = 0; do { int err = 0; unsigned int chunk = 0; slice = ((buflen - len) / drbg_max_request_bytes(drbg)); chunk = slice ? drbg_max_request_bytes(drbg) : (buflen - len); mutex_lock(&drbg->drbg_mutex); err = drbg_generate(drbg, buf + len, chunk, addtl); mutex_unlock(&drbg->drbg_mutex); if (0 > err) return err; len += chunk; } while (slice > 0 && (len < buflen)); return 0; } static int drbg_prepare_hrng(struct drbg_state *drbg) { /* We do not need an HRNG in test mode. */ if (list_empty(&drbg->test_data.list)) return 0; drbg->jent = crypto_alloc_rng("jitterentropy_rng", 0, 0); if (IS_ERR(drbg->jent)) { const int err = PTR_ERR(drbg->jent); drbg->jent = NULL; if (fips_enabled) return err; pr_info("DRBG: Continuing without Jitter RNG\n"); } return 0; } /* * DRBG instantiation function as required by SP800-90A - this function * sets up the DRBG handle, performs the initial seeding and all sanity * checks required by SP800-90A * * @drbg memory of state -- if NULL, new memory is allocated * @pers Personalization string that is mixed into state, may be NULL -- note * the entropy is pulled by the DRBG internally unconditionally * as defined in SP800-90A. The additional input is mixed into * the state in addition to the pulled entropy. * @coreref reference to core * @pr prediction resistance enabled * * return * 0 on success * error value otherwise */ static int drbg_instantiate(struct drbg_state *drbg, struct drbg_string *pers, int coreref, bool pr) { int ret; bool reseed = true; pr_devel("DRBG: Initializing DRBG core %d with prediction resistance " "%s\n", coreref, str_enabled_disabled(pr)); mutex_lock(&drbg->drbg_mutex); /* 9.1 step 1 is implicit with the selected DRBG type */ /* * 9.1 step 2 is implicit as caller can select prediction resistance * and the flag is copied into drbg->flags -- * all DRBG types support prediction resistance */ /* 9.1 step 4 is implicit in drbg_sec_strength */ if (!drbg->core) { drbg->core = &drbg_cores[coreref]; drbg->pr = pr; drbg->seeded = DRBG_SEED_STATE_UNSEEDED; drbg->last_seed_time = 0; drbg->reseed_threshold = drbg_max_requests(drbg); ret = drbg_alloc_state(drbg); if (ret) goto unlock; ret = drbg_prepare_hrng(drbg); if (ret) goto free_everything; reseed = false; } ret = drbg_seed(drbg, pers, reseed); if (ret && !reseed) goto free_everything; mutex_unlock(&drbg->drbg_mutex); return ret; unlock: mutex_unlock(&drbg->drbg_mutex); return ret; free_everything: mutex_unlock(&drbg->drbg_mutex); drbg_uninstantiate(drbg); return ret; } /* * DRBG uninstantiate function as required by SP800-90A - this function * frees all buffers and the DRBG handle * * @drbg DRBG state handle * * return * 0 on success */ static int drbg_uninstantiate(struct drbg_state *drbg) { if (!IS_ERR_OR_NULL(drbg->jent)) crypto_free_rng(drbg->jent); drbg->jent = NULL; if (drbg->d_ops) drbg->d_ops->crypto_fini(drbg); drbg_dealloc_state(drbg); /* no scrubbing of test_data -- this shall survive an uninstantiate */ return 0; } /* * Helper function for setting the test data in the DRBG * * @drbg DRBG state handle * @data test data * @len test data length */ static void drbg_kcapi_set_entropy(struct crypto_rng *tfm, const u8 *data, unsigned int len) { struct drbg_state *drbg = crypto_rng_ctx(tfm); mutex_lock(&drbg->drbg_mutex); drbg_string_fill(&drbg->test_data, data, len); mutex_unlock(&drbg->drbg_mutex); } /*************************************************************** * Kernel crypto API cipher invocations requested by DRBG ***************************************************************/ #if defined(CONFIG_CRYPTO_DRBG_HASH) || defined(CONFIG_CRYPTO_DRBG_HMAC) struct sdesc { struct shash_desc shash; char ctx[]; }; static int drbg_init_hash_kernel(struct drbg_state *drbg) { struct sdesc *sdesc; struct crypto_shash *tfm; tfm = crypto_alloc_shash(drbg->core->backend_cra_name, 0, 0); if (IS_ERR(tfm)) { pr_info("DRBG: could not allocate digest TFM handle: %s\n", drbg->core->backend_cra_name); return PTR_ERR(tfm); } BUG_ON(drbg_blocklen(drbg) != crypto_shash_digestsize(tfm)); sdesc = kzalloc(sizeof(struct shash_desc) + crypto_shash_descsize(tfm), GFP_KERNEL); if (!sdesc) { crypto_free_shash(tfm); return -ENOMEM; } sdesc->shash.tfm = tfm; drbg->priv_data = sdesc; return 0; } static int drbg_fini_hash_kernel(struct drbg_state *drbg) { struct sdesc *sdesc = drbg->priv_data; if (sdesc) { crypto_free_shash(sdesc->shash.tfm); kfree_sensitive(sdesc); } drbg->priv_data = NULL; return 0; } static void drbg_kcapi_hmacsetkey(struct drbg_state *drbg, const unsigned char *key) { struct sdesc *sdesc = drbg->priv_data; crypto_shash_setkey(sdesc->shash.tfm, key, drbg_statelen(drbg)); } static int drbg_kcapi_hash(struct drbg_state *drbg, unsigned char *outval, const struct list_head *in) { struct sdesc *sdesc = drbg->priv_data; struct drbg_string *input = NULL; crypto_shash_init(&sdesc->shash); list_for_each_entry(input, in, list) crypto_shash_update(&sdesc->shash, input->buf, input->len); return crypto_shash_final(&sdesc->shash, outval); } #endif /* (CONFIG_CRYPTO_DRBG_HASH || CONFIG_CRYPTO_DRBG_HMAC) */ #ifdef CONFIG_CRYPTO_DRBG_CTR static int drbg_fini_sym_kernel(struct drbg_state *drbg) { struct crypto_cipher *tfm = (struct crypto_cipher *)drbg->priv_data; if (tfm) crypto_free_cipher(tfm); drbg->priv_data = NULL; if (drbg->ctr_handle) crypto_free_skcipher(drbg->ctr_handle); drbg->ctr_handle = NULL; if (drbg->ctr_req) skcipher_request_free(drbg->ctr_req); drbg->ctr_req = NULL; kfree(drbg->outscratchpadbuf); drbg->outscratchpadbuf = NULL; return 0; } static int drbg_init_sym_kernel(struct drbg_state *drbg) { struct crypto_cipher *tfm; struct crypto_skcipher *sk_tfm; struct skcipher_request *req; unsigned int alignmask; char ctr_name[CRYPTO_MAX_ALG_NAME]; tfm = crypto_alloc_cipher(drbg->core->backend_cra_name, 0, 0); if (IS_ERR(tfm)) { pr_info("DRBG: could not allocate cipher TFM handle: %s\n", drbg->core->backend_cra_name); return PTR_ERR(tfm); } BUG_ON(drbg_blocklen(drbg) != crypto_cipher_blocksize(tfm)); drbg->priv_data = tfm; if (snprintf(ctr_name, CRYPTO_MAX_ALG_NAME, "ctr(%s)", drbg->core->backend_cra_name) >= CRYPTO_MAX_ALG_NAME) { drbg_fini_sym_kernel(drbg); return -EINVAL; } sk_tfm = crypto_alloc_skcipher(ctr_name, 0, 0); if (IS_ERR(sk_tfm)) { pr_info("DRBG: could not allocate CTR cipher TFM handle: %s\n", ctr_name); drbg_fini_sym_kernel(drbg); return PTR_ERR(sk_tfm); } drbg->ctr_handle = sk_tfm; crypto_init_wait(&drbg->ctr_wait); req = skcipher_request_alloc(sk_tfm, GFP_KERNEL); if (!req) { pr_info("DRBG: could not allocate request queue\n"); drbg_fini_sym_kernel(drbg); return -ENOMEM; } drbg->ctr_req = req; skcipher_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP, crypto_req_done, &drbg->ctr_wait); alignmask = crypto_skcipher_alignmask(sk_tfm); drbg->outscratchpadbuf = kmalloc(DRBG_OUTSCRATCHLEN + alignmask, GFP_KERNEL); if (!drbg->outscratchpadbuf) { drbg_fini_sym_kernel(drbg); return -ENOMEM; } drbg->outscratchpad = (u8 *)PTR_ALIGN(drbg->outscratchpadbuf, alignmask + 1); sg_init_table(&drbg->sg_in, 1); sg_init_one(&drbg->sg_out, drbg->outscratchpad, DRBG_OUTSCRATCHLEN); return alignmask; } static void drbg_kcapi_symsetkey(struct drbg_state *drbg, const unsigned char *key) { struct crypto_cipher *tfm = drbg->priv_data; crypto_cipher_setkey(tfm, key, (drbg_keylen(drbg))); } static int drbg_kcapi_sym(struct drbg_state *drbg, unsigned char *outval, const struct drbg_string *in) { struct crypto_cipher *tfm = drbg->priv_data; /* there is only component in *in */ BUG_ON(in->len < drbg_blocklen(drbg)); crypto_cipher_encrypt_one(tfm, outval, in->buf); return 0; } static int drbg_kcapi_sym_ctr(struct drbg_state *drbg, u8 *inbuf, u32 inlen, u8 *outbuf, u32 outlen) { struct scatterlist *sg_in = &drbg->sg_in, *sg_out = &drbg->sg_out; u32 scratchpad_use = min_t(u32, outlen, DRBG_OUTSCRATCHLEN); int ret; if (inbuf) { /* Use caller-provided input buffer */ sg_set_buf(sg_in, inbuf, inlen); } else { /* Use scratchpad for in-place operation */ inlen = scratchpad_use; memset(drbg->outscratchpad, 0, scratchpad_use); sg_set_buf(sg_in, drbg->outscratchpad, scratchpad_use); } while (outlen) { u32 cryptlen = min3(inlen, outlen, (u32)DRBG_OUTSCRATCHLEN); /* Output buffer may not be valid for SGL, use scratchpad */ skcipher_request_set_crypt(drbg->ctr_req, sg_in, sg_out, cryptlen, drbg->V); ret = crypto_wait_req(crypto_skcipher_encrypt(drbg->ctr_req), &drbg->ctr_wait); if (ret) goto out; crypto_init_wait(&drbg->ctr_wait); memcpy(outbuf, drbg->outscratchpad, cryptlen); memzero_explicit(drbg->outscratchpad, cryptlen); outlen -= cryptlen; outbuf += cryptlen; } ret = 0; out: return ret; } #endif /* CONFIG_CRYPTO_DRBG_CTR */ /*************************************************************** * Kernel crypto API interface to register DRBG ***************************************************************/ /* * Look up the DRBG flags by given kernel crypto API cra_name * The code uses the drbg_cores definition to do this * * @cra_name kernel crypto API cra_name * @coreref reference to integer which is filled with the pointer to * the applicable core * @pr reference for setting prediction resistance * * return: flags */ static inline void drbg_convert_tfm_core(const char *cra_driver_name, int *coreref, bool *pr) { int i = 0; size_t start = 0; int len = 0; *pr = true; /* disassemble the names */ if (!memcmp(cra_driver_name, "drbg_nopr_", 10)) { start = 10; *pr = false; } else if (!memcmp(cra_driver_name, "drbg_pr_", 8)) { start = 8; } else { return; } /* remove the first part */ len = strlen(cra_driver_name) - start; for (i = 0; ARRAY_SIZE(drbg_cores) > i; i++) { if (!memcmp(cra_driver_name + start, drbg_cores[i].cra_name, len)) { *coreref = i; return; } } } static int drbg_kcapi_init(struct crypto_tfm *tfm) { struct drbg_state *drbg = crypto_tfm_ctx(tfm); mutex_init(&drbg->drbg_mutex); return 0; } static void drbg_kcapi_cleanup(struct crypto_tfm *tfm) { drbg_uninstantiate(crypto_tfm_ctx(tfm)); } /* * Generate random numbers invoked by the kernel crypto API: * The API of the kernel crypto API is extended as follows: * * src is additional input supplied to the RNG. * slen is the length of src. * dst is the output buffer where random data is to be stored. * dlen is the length of dst. */ static int drbg_kcapi_random(struct crypto_rng *tfm, const u8 *src, unsigned int slen, u8 *dst, unsigned int dlen) { struct drbg_state *drbg = crypto_rng_ctx(tfm); struct drbg_string *addtl = NULL; struct drbg_string string; if (slen) { /* linked list variable is now local to allow modification */ drbg_string_fill(&string, src, slen); addtl = &string; } return drbg_generate_long(drbg, dst, dlen, addtl); } /* * Seed the DRBG invoked by the kernel crypto API */ static int drbg_kcapi_seed(struct crypto_rng *tfm, const u8 *seed, unsigned int slen) { struct drbg_state *drbg = crypto_rng_ctx(tfm); struct crypto_tfm *tfm_base = crypto_rng_tfm(tfm); bool pr = false; struct drbg_string string; struct drbg_string *seed_string = NULL; int coreref = 0; drbg_convert_tfm_core(crypto_tfm_alg_driver_name(tfm_base), &coreref, &pr); if (0 < slen) { drbg_string_fill(&string, seed, slen); seed_string = &string; } return drbg_instantiate(drbg, seed_string, coreref, pr); } /*************************************************************** * Kernel module: code to load the module ***************************************************************/ /* * Tests as defined in 11.3.2 in addition to the cipher tests: testing * of the error handling. * * Note: testing of failing seed source as defined in 11.3.2 is not applicable * as seed source of get_random_bytes does not fail. * * Note 2: There is no sensible way of testing the reseed counter * enforcement, so skip it. */ static inline int __init drbg_healthcheck_sanity(void) { int len = 0; #define OUTBUFLEN 16 unsigned char buf[OUTBUFLEN]; struct drbg_state *drbg = NULL; int ret; int rc = -EFAULT; bool pr = false; int coreref = 0; struct drbg_string addtl; size_t max_addtllen, max_request_bytes; /* only perform test in FIPS mode */ if (!fips_enabled) return 0; #ifdef CONFIG_CRYPTO_DRBG_CTR drbg_convert_tfm_core("drbg_nopr_ctr_aes256", &coreref, &pr); #endif #ifdef CONFIG_CRYPTO_DRBG_HASH drbg_convert_tfm_core("drbg_nopr_sha256", &coreref, &pr); #endif #ifdef CONFIG_CRYPTO_DRBG_HMAC drbg_convert_tfm_core("drbg_nopr_hmac_sha512", &coreref, &pr); #endif drbg = kzalloc(sizeof(struct drbg_state), GFP_KERNEL); if (!drbg) return -ENOMEM; mutex_init(&drbg->drbg_mutex); drbg->core = &drbg_cores[coreref]; drbg->reseed_threshold = drbg_max_requests(drbg); /* * if the following tests fail, it is likely that there is a buffer * overflow as buf is much smaller than the requested or provided * string lengths -- in case the error handling does not succeed * we may get an OOPS. And we want to get an OOPS as this is a * grave bug. */ max_addtllen = drbg_max_addtl(drbg); max_request_bytes = drbg_max_request_bytes(drbg); drbg_string_fill(&addtl, buf, max_addtllen + 1); /* overflow addtllen with additonal info string */ len = drbg_generate(drbg, buf, OUTBUFLEN, &addtl); BUG_ON(0 < len); /* overflow max_bits */ len = drbg_generate(drbg, buf, (max_request_bytes + 1), NULL); BUG_ON(0 < len); /* overflow max addtllen with personalization string */ ret = drbg_seed(drbg, &addtl, false); BUG_ON(0 == ret); /* all tests passed */ rc = 0; pr_devel("DRBG: Sanity tests for failure code paths successfully " "completed\n"); kfree(drbg); return rc; } static struct rng_alg drbg_algs[22]; /* * Fill the array drbg_algs used to register the different DRBGs * with the kernel crypto API. To fill the array, the information * from drbg_cores[] is used. */ static inline void __init drbg_fill_array(struct rng_alg *alg, const struct drbg_core *core, int pr) { int pos = 0; static int priority = 200; memcpy(alg->base.cra_name, "stdrng", 6); if (pr) { memcpy(alg->base.cra_driver_name, "drbg_pr_", 8); pos = 8; } else { memcpy(alg->base.cra_driver_name, "drbg_nopr_", 10); pos = 10; } memcpy(alg->base.cra_driver_name + pos, core->cra_name, strlen(core->cra_name)); alg->base.cra_priority = priority; priority++; /* * If FIPS mode enabled, the selected DRBG shall have the * highest cra_priority over other stdrng instances to ensure * it is selected. */ if (fips_enabled) alg->base.cra_priority += 200; alg->base.cra_ctxsize = sizeof(struct drbg_state); alg->base.cra_module = THIS_MODULE; alg->base.cra_init = drbg_kcapi_init; alg->base.cra_exit = drbg_kcapi_cleanup; alg->generate = drbg_kcapi_random; alg->seed = drbg_kcapi_seed; alg->set_ent = drbg_kcapi_set_entropy; alg->seedsize = 0; } static int __init drbg_init(void) { unsigned int i = 0; /* pointer to drbg_algs */ unsigned int j = 0; /* pointer to drbg_cores */ int ret; ret = drbg_healthcheck_sanity(); if (ret) return ret; if (ARRAY_SIZE(drbg_cores) * 2 > ARRAY_SIZE(drbg_algs)) { pr_info("DRBG: Cannot register all DRBG types" "(slots needed: %zu, slots available: %zu)\n", ARRAY_SIZE(drbg_cores) * 2, ARRAY_SIZE(drbg_algs)); return -EFAULT; } /* * each DRBG definition can be used with PR and without PR, thus * we instantiate each DRBG in drbg_cores[] twice. * * As the order of placing them into the drbg_algs array matters * (the later DRBGs receive a higher cra_priority) we register the * prediction resistance DRBGs first as the should not be too * interesting. */ for (j = 0; ARRAY_SIZE(drbg_cores) > j; j++, i++) drbg_fill_array(&drbg_algs[i], &drbg_cores[j], 1); for (j = 0; ARRAY_SIZE(drbg_cores) > j; j++, i++) drbg_fill_array(&drbg_algs[i], &drbg_cores[j], 0); return crypto_register_rngs(drbg_algs, (ARRAY_SIZE(drbg_cores) * 2)); } static void __exit drbg_exit(void) { crypto_unregister_rngs(drbg_algs, (ARRAY_SIZE(drbg_cores) * 2)); } subsys_initcall(drbg_init); module_exit(drbg_exit); #ifndef CRYPTO_DRBG_HASH_STRING #define CRYPTO_DRBG_HASH_STRING "" #endif #ifndef CRYPTO_DRBG_HMAC_STRING #define CRYPTO_DRBG_HMAC_STRING "" #endif #ifndef CRYPTO_DRBG_CTR_STRING #define CRYPTO_DRBG_CTR_STRING "" #endif MODULE_LICENSE("GPL"); MODULE_AUTHOR("Stephan Mueller "); MODULE_DESCRIPTION("NIST SP800-90A Deterministic Random Bit Generator (DRBG) " "using following cores: " CRYPTO_DRBG_HASH_STRING CRYPTO_DRBG_HMAC_STRING CRYPTO_DRBG_CTR_STRING); MODULE_ALIAS_CRYPTO("stdrng"); MODULE_IMPORT_NS("CRYPTO_INTERNAL");