/* * 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 /*************************************************************** * Backend cipher definitions available to DRBG ***************************************************************/ /* * The order of the DRBG definitions here matter: every DRBG is registered * as stdrng. Each DRBG receives an increasing cra_priority values the later * they are defined in this array (see drbg_fill_array). * * HMAC DRBGs are favored over Hash DRBGs over CTR DRBGs, and * the SHA256 / AES 256 over other ciphers. Thus, the favored * DRBGs are the latest entries in this array. */ static const struct drbg_core drbg_cores[] = { #ifdef CONFIG_CRYPTO_DRBG_CTR { .flags = DRBG_CTR | DRBG_STRENGTH128, .statelen = 32, /* 256 bits as defined in 10.2.1 */ .blocklen_bytes = 16, .cra_name = "ctr_aes128", .backend_cra_name = "ecb(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 = "ecb(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 = "ecb(aes)", }, #endif /* CONFIG_CRYPTO_DRBG_CTR */ #ifdef CONFIG_CRYPTO_DRBG_HASH { .flags = DRBG_HASH | DRBG_STRENGTH128, .statelen = 55, /* 440 bits */ .blocklen_bytes = 20, .cra_name = "sha1", .backend_cra_name = "sha1", }, { .flags = DRBG_HASH | DRBG_STRENGTH256, .statelen = 111, /* 888 bits */ .blocklen_bytes = 48, .cra_name = "sha384", .backend_cra_name = "sha384", }, { .flags = DRBG_HASH | DRBG_STRENGTH256, .statelen = 111, /* 888 bits */ .blocklen_bytes = 64, .cra_name = "sha512", .backend_cra_name = "sha512", }, { .flags = DRBG_HASH | DRBG_STRENGTH256, .statelen = 55, /* 440 bits */ .blocklen_bytes = 32, .cra_name = "sha256", .backend_cra_name = "sha256", }, #endif /* CONFIG_CRYPTO_DRBG_HASH */ #ifdef CONFIG_CRYPTO_DRBG_HMAC { .flags = DRBG_HMAC | DRBG_STRENGTH128, .statelen = 20, /* block length of cipher */ .blocklen_bytes = 20, .cra_name = "hmac_sha1", .backend_cra_name = "hmac(sha1)", }, { .flags = DRBG_HMAC | DRBG_STRENGTH256, .statelen = 48, /* block length of cipher */ .blocklen_bytes = 48, .cra_name = "hmac_sha384", .backend_cra_name = "hmac(sha384)", }, { .flags = DRBG_HMAC | DRBG_STRENGTH256, .statelen = 64, /* block length of cipher */ .blocklen_bytes = 64, .cra_name = "hmac_sha512", .backend_cra_name = "hmac(sha512)", }, { .flags = DRBG_HMAC | DRBG_STRENGTH256, .statelen = 32, /* block length of cipher */ .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 * * @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); } /* * 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_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 */ 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(0) of C is implicit with kzalloc */ 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_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, 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; 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 */ 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)); 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 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"); } if (!reseed) { memset(drbg->V, 0, drbg_statelen(drbg)); memset(drbg->C, 0, drbg_statelen(drbg)); } 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: 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; kzfree(drbg->V); drbg->V = NULL; kzfree(drbg->C); drbg->C = NULL; kzfree(drbg->scratchpad); drbg->scratchpad = NULL; drbg->reseed_ctr = 0; #ifdef CONFIG_CRYPTO_FIPS 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; drbg->V = kmalloc(drbg_statelen(drbg), GFP_KERNEL); if (!drbg->V) goto err; drbg->C = kmalloc(drbg_statelen(drbg), GFP_KERNEL); if (!drbg->C) goto err; #ifdef CONFIG_CRYPTO_FIPS drbg->prev = kmalloc(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; 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: 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 */ 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: 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)) goto err; ret = drbg_seed(drbg, pers, false); 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); /* 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 "); 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);