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linux/crypto/drbg.c
Stephan Mueller 78f543a934 crypto: drbg - remove check for uninitialized DRBG handle 
The drbg_healthcheck() contained a test to call the DRBG with an
uninitialized DRBG cipher handle. As this is an inappropriate use of the
kernel crypto API to try to generate random numbers before
initialization, checks verifying for an initialized DRBG have been
removed in previous patches.

Now, the drbg_healthcheck test must also be removed.

Changes V2: Added patch marker to email subject line.

Signed-off-by: Stephan Mueller <smueller@chronox.de>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2014-09-05 15:56:43 +08:00

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/*
* DRBG: Deterministic Random Bits Generator
* Based on NIST Recommended DRBG from NIST SP800-90A with the following
* properties:
* * CTR DRBG with DF with AES-128, AES-192, AES-256 cores
* * Hash DRBG with DF with SHA-1, SHA-256, SHA-384, SHA-512 cores
* * HMAC DRBG with DF with SHA-1, SHA-256, SHA-384, SHA-512 cores
* * with and without prediction resistance
*
* Copyright Stephan Mueller <smueller@chronox.de>, 2014
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, and the entire permission notice in its entirety,
* including the disclaimer of warranties.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. The name of the author may not be used to endorse or promote
* products derived from this software without specific prior
* written permission.
*
* ALTERNATIVELY, this product may be distributed under the terms of
* the GNU General Public License, in which case the provisions of the GPL are
* required INSTEAD OF the above restrictions. (This clause is
* necessary due to a potential bad interaction between the GPL and
* the restrictions contained in a BSD-style copyright.)
*
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, ALL OF
* WHICH ARE HEREBY DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
* OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
* BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
* USE OF THIS SOFTWARE, EVEN IF NOT ADVISED OF THE POSSIBILITY OF SUCH
* DAMAGE.
*
* DRBG Usage
* ==========
* The SP 800-90A DRBG allows the user to specify a personalization string
* for initialization as well as an additional information string for each
* random number request. The following code fragments show how a caller
* uses the kernel crypto API to use the full functionality of the DRBG.
*
* Usage without any additional data
* ---------------------------------
* struct crypto_rng *drng;
* int err;
* char data[DATALEN];
*
* drng = crypto_alloc_rng(drng_name, 0, 0);
* err = crypto_rng_get_bytes(drng, &data, DATALEN);
* crypto_free_rng(drng);
*
*
* Usage with personalization string during initialization
* -------------------------------------------------------
* struct crypto_rng *drng;
* int err;
* char data[DATALEN];
* struct drbg_string pers;
* char personalization[11] = "some-string";
*
* drbg_string_fill(&pers, personalization, strlen(personalization));
* drng = crypto_alloc_rng(drng_name, 0, 0);
* // The reset completely re-initializes the DRBG with the provided
* // personalization string
* err = crypto_rng_reset(drng, &personalization, strlen(personalization));
* err = crypto_rng_get_bytes(drng, &data, DATALEN);
* crypto_free_rng(drng);
*
*
* Usage with additional information string during random number request
* ---------------------------------------------------------------------
* struct crypto_rng *drng;
* int err;
* char data[DATALEN];
* char addtl_string[11] = "some-string";
* string drbg_string addtl;
*
* drbg_string_fill(&addtl, addtl_string, strlen(addtl_string));
* drng = crypto_alloc_rng(drng_name, 0, 0);
* // The following call is a wrapper to crypto_rng_get_bytes() and returns
* // the same error codes.
* err = crypto_drbg_get_bytes_addtl(drng, &data, DATALEN, &addtl);
* crypto_free_rng(drng);
*
*
* Usage with personalization and additional information strings
* -------------------------------------------------------------
* Just mix both scenarios above.
*/
#include <crypto/drbg.h>
/***************************************************************
* Backend cipher definitions available to DRBG
***************************************************************/
/*
* The order of the DRBG definitions here matter: every DRBG is registered
* as stdrng. Each DRBG receives an increasing cra_priority values the later
* they are defined in this array (see drbg_fill_array).
*
* HMAC DRBGs are favored over Hash DRBGs over CTR DRBGs, and
* the SHA256 / AES 256 over other ciphers. Thus, the favored
* DRBGs are the latest entries in this array.
*/
static const struct drbg_core drbg_cores[] = {
#ifdef CONFIG_CRYPTO_DRBG_CTR
{
.flags = DRBG_CTR | DRBG_STRENGTH128,
.statelen = 32, /* 256 bits as defined in 10.2.1 */
.max_addtllen = 35,
.max_bits = 19,
.max_req = 48,
.blocklen_bytes = 16,
.cra_name = "ctr_aes128",
.backend_cra_name = "ecb(aes)",
}, {
.flags = DRBG_CTR | DRBG_STRENGTH192,
.statelen = 40, /* 320 bits as defined in 10.2.1 */
.max_addtllen = 35,
.max_bits = 19,
.max_req = 48,
.blocklen_bytes = 16,
.cra_name = "ctr_aes192",
.backend_cra_name = "ecb(aes)",
}, {
.flags = DRBG_CTR | DRBG_STRENGTH256,
.statelen = 48, /* 384 bits as defined in 10.2.1 */
.max_addtllen = 35,
.max_bits = 19,
.max_req = 48,
.blocklen_bytes = 16,
.cra_name = "ctr_aes256",
.backend_cra_name = "ecb(aes)",
},
#endif /* CONFIG_CRYPTO_DRBG_CTR */
#ifdef CONFIG_CRYPTO_DRBG_HASH
{
.flags = DRBG_HASH | DRBG_STRENGTH128,
.statelen = 55, /* 440 bits */
.max_addtllen = 35,
.max_bits = 19,
.max_req = 48,
.blocklen_bytes = 20,
.cra_name = "sha1",
.backend_cra_name = "sha1",
}, {
.flags = DRBG_HASH | DRBG_STRENGTH256,
.statelen = 111, /* 888 bits */
.max_addtllen = 35,
.max_bits = 19,
.max_req = 48,
.blocklen_bytes = 48,
.cra_name = "sha384",
.backend_cra_name = "sha384",
}, {
.flags = DRBG_HASH | DRBG_STRENGTH256,
.statelen = 111, /* 888 bits */
.max_addtllen = 35,
.max_bits = 19,
.max_req = 48,
.blocklen_bytes = 64,
.cra_name = "sha512",
.backend_cra_name = "sha512",
}, {
.flags = DRBG_HASH | DRBG_STRENGTH256,
.statelen = 55, /* 440 bits */
.max_addtllen = 35,
.max_bits = 19,
.max_req = 48,
.blocklen_bytes = 32,
.cra_name = "sha256",
.backend_cra_name = "sha256",
},
#endif /* CONFIG_CRYPTO_DRBG_HASH */
#ifdef CONFIG_CRYPTO_DRBG_HMAC
{
.flags = DRBG_HMAC | DRBG_STRENGTH128,
.statelen = 20, /* block length of cipher */
.max_addtllen = 35,
.max_bits = 19,
.max_req = 48,
.blocklen_bytes = 20,
.cra_name = "hmac_sha1",
.backend_cra_name = "hmac(sha1)",
}, {
.flags = DRBG_HMAC | DRBG_STRENGTH256,
.statelen = 48, /* block length of cipher */
.max_addtllen = 35,
.max_bits = 19,
.max_req = 48,
.blocklen_bytes = 48,
.cra_name = "hmac_sha384",
.backend_cra_name = "hmac(sha384)",
}, {
.flags = DRBG_HMAC | DRBG_STRENGTH256,
.statelen = 64, /* block length of cipher */
.max_addtllen = 35,
.max_bits = 19,
.max_req = 48,
.blocklen_bytes = 64,
.cra_name = "hmac_sha512",
.backend_cra_name = "hmac(sha512)",
}, {
.flags = DRBG_HMAC | DRBG_STRENGTH256,
.statelen = 32, /* block length of cipher */
.max_addtllen = 35,
.max_bits = 19,
.max_req = 48,
.blocklen_bytes = 32,
.cra_name = "hmac_sha256",
.backend_cra_name = "hmac(sha256)",
},
#endif /* CONFIG_CRYPTO_DRBG_HMAC */
};
/******************************************************************
* Generic helper functions
******************************************************************/
/*
* Return strength of DRBG according to SP800-90A section 8.4
*
* @flags DRBG flags reference
*
* Return: normalized strength in *bytes* value or 32 as default
* to counter programming errors
*/
static inline unsigned short drbg_sec_strength(drbg_flag_t flags)
{
switch (flags & DRBG_STRENGTH_MASK) {
case DRBG_STRENGTH128:
return 16;
case DRBG_STRENGTH192:
return 24;
case DRBG_STRENGTH256:
return 32;
default:
return 32;
}
}
/*
* FIPS 140-2 continuous self test
* The test is performed on the result of one round of the output
* function. Thus, the function implicitly knows the size of the
* buffer.
*
* The FIPS test can be called in an endless loop until it returns
* true. Although the code looks like a potential for a deadlock, it
* is not the case, because returning a false cannot mathematically
* occur (except once when a reseed took place and the updated state
* would is now set up such that the generation of new value returns
* an identical one -- this is most unlikely and would happen only once).
* Thus, if this function repeatedly returns false and thus would cause
* a deadlock, the integrity of the entire kernel is lost.
*
* @drbg DRBG handle
* @buf output buffer of random data to be checked
*
* return:
* true on success
* false on error
*/
static bool drbg_fips_continuous_test(struct drbg_state *drbg,
const unsigned char *buf)
{
#ifdef CONFIG_CRYPTO_FIPS
int ret = 0;
/* skip test if we test the overall system */
if (drbg->test_data)
return true;
/* only perform test in FIPS mode */
if (0 == fips_enabled)
return true;
if (!drbg->fips_primed) {
/* Priming of FIPS test */
memcpy(drbg->prev, buf, drbg_blocklen(drbg));
drbg->fips_primed = true;
/* return false due to priming, i.e. another round is needed */
return false;
}
ret = memcmp(drbg->prev, buf, drbg_blocklen(drbg));
memcpy(drbg->prev, buf, drbg_blocklen(drbg));
/* the test shall pass when the two compared values are not equal */
return ret != 0;
#else
return true;
#endif /* CONFIG_CRYPTO_FIPS */
}
/*
* Convert an integer into a byte representation of this integer.
* The byte representation is big-endian
*
* @buf buffer holding the converted integer
* @val value to be converted
* @buflen length of buffer
*/
#if (defined(CONFIG_CRYPTO_DRBG_HASH) || defined(CONFIG_CRYPTO_DRBG_CTR))
static inline void drbg_int2byte(unsigned char *buf, uint64_t val,
size_t buflen)
{
unsigned char *byte;
uint64_t i;
byte = buf + (buflen - 1);
for (i = 0; i < buflen; i++)
*(byte--) = val >> (i * 8) & 0xff;
}
/*
* Increment buffer
*
* @dst buffer to increment
* @add value to add
*/
static inline void drbg_add_buf(unsigned char *dst, size_t dstlen,
const unsigned char *add, size_t addlen)
{
/* implied: dstlen > addlen */
unsigned char *dstptr;
const unsigned char *addptr;
unsigned int remainder = 0;
size_t len = addlen;
dstptr = dst + (dstlen-1);
addptr = add + (addlen-1);
while (len) {
remainder += *dstptr + *addptr;
*dstptr = remainder & 0xff;
remainder >>= 8;
len--; dstptr--; addptr--;
}
len = dstlen - addlen;
while (len && remainder > 0) {
remainder = *dstptr + 1;
*dstptr = remainder & 0xff;
remainder >>= 8;
len--; dstptr--;
}
}
#endif /* defined(CONFIG_CRYPTO_DRBG_HASH) || defined(CONFIG_CRYPTO_DRBG_CTR) */
/******************************************************************
* CTR DRBG callback functions
******************************************************************/
#ifdef CONFIG_CRYPTO_DRBG_CTR
#define CRYPTO_DRBG_CTR_STRING "CTR "
static int drbg_kcapi_sym(struct drbg_state *drbg, const unsigned char *key,
unsigned char *outval, const struct drbg_string *in);
static int drbg_init_sym_kernel(struct drbg_state *drbg);
static int drbg_fini_sym_kernel(struct drbg_state *drbg);
/* BCC function for CTR DRBG as defined in 10.4.3 */
static int drbg_ctr_bcc(struct drbg_state *drbg,
unsigned char *out, const unsigned char *key,
struct list_head *in)
{
int ret = 0;
struct drbg_string *curr = NULL;
struct drbg_string data;
short cnt = 0;
drbg_string_fill(&data, out, drbg_blocklen(drbg));
/* 10.4.3 step 1 */
memset(out, 0, drbg_blocklen(drbg));
/* 10.4.3 step 2 / 4 */
list_for_each_entry(curr, in, list) {
const unsigned char *pos = curr->buf;
size_t len = curr->len;
/* 10.4.3 step 4.1 */
while (len) {
/* 10.4.3 step 4.2 */
if (drbg_blocklen(drbg) == cnt) {
cnt = 0;
ret = drbg_kcapi_sym(drbg, key, out, &data);
if (ret)
return ret;
}
out[cnt] ^= *pos;
pos++;
cnt++;
len--;
}
}
/* 10.4.3 step 4.2 for last block */
if (cnt)
ret = drbg_kcapi_sym(drbg, key, out, &data);
return ret;
}
/*
* scratchpad usage: drbg_ctr_update is interlinked with drbg_ctr_df
* (and drbg_ctr_bcc, but this function does not need any temporary buffers),
* the scratchpad is used as follows:
* drbg_ctr_update:
* temp
* start: drbg->scratchpad
* length: drbg_statelen(drbg) + drbg_blocklen(drbg)
* note: the cipher writing into this variable works
* blocklen-wise. Now, when the statelen is not a multiple
* of blocklen, the generateion loop below "spills over"
* by at most blocklen. Thus, we need to give sufficient
* memory.
* df_data
* start: drbg->scratchpad +
* drbg_statelen(drbg) + drbg_blocklen(drbg)
* length: drbg_statelen(drbg)
*
* drbg_ctr_df:
* pad
* start: df_data + drbg_statelen(drbg)
* length: drbg_blocklen(drbg)
* iv
* start: pad + drbg_blocklen(drbg)
* length: drbg_blocklen(drbg)
* temp
* start: iv + drbg_blocklen(drbg)
* length: drbg_satelen(drbg) + drbg_blocklen(drbg)
* note: temp is the buffer that the BCC function operates
* on. BCC operates blockwise. drbg_statelen(drbg)
* is sufficient when the DRBG state length is a multiple
* of the block size. For AES192 (and maybe other ciphers)
* this is not correct and the length for temp is
* insufficient (yes, that also means for such ciphers,
* the final output of all BCC rounds are truncated).
* Therefore, add drbg_blocklen(drbg) to cover all
* possibilities.
*/
/* Derivation Function for CTR DRBG as defined in 10.4.2 */
static int drbg_ctr_df(struct drbg_state *drbg,
unsigned char *df_data, size_t bytes_to_return,
struct list_head *seedlist)
{
int ret = -EFAULT;
unsigned char L_N[8];
/* S3 is input */
struct drbg_string S1, S2, S4, cipherin;
LIST_HEAD(bcc_list);
unsigned char *pad = df_data + drbg_statelen(drbg);
unsigned char *iv = pad + drbg_blocklen(drbg);
unsigned char *temp = iv + drbg_blocklen(drbg);
size_t padlen = 0;
unsigned int templen = 0;
/* 10.4.2 step 7 */
unsigned int i = 0;
/* 10.4.2 step 8 */
const unsigned char *K = (unsigned char *)
"\x00\x01\x02\x03\x04\x05\x06\x07"
"\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f"
"\x10\x11\x12\x13\x14\x15\x16\x17"
"\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f";
unsigned char *X;
size_t generated_len = 0;
size_t inputlen = 0;
struct drbg_string *seed = NULL;
memset(pad, 0, drbg_blocklen(drbg));
memset(iv, 0, drbg_blocklen(drbg));
memset(temp, 0, drbg_statelen(drbg));
/* 10.4.2 step 1 is implicit as we work byte-wise */
/* 10.4.2 step 2 */
if ((512/8) < bytes_to_return)
return -EINVAL;
/* 10.4.2 step 2 -- calculate the entire length of all input data */
list_for_each_entry(seed, seedlist, list)
inputlen += seed->len;
drbg_int2byte(&L_N[0], inputlen, 4);
/* 10.4.2 step 3 */
drbg_int2byte(&L_N[4], bytes_to_return, 4);
/* 10.4.2 step 5: length is L_N, input_string, one byte, padding */
padlen = (inputlen + sizeof(L_N) + 1) % (drbg_blocklen(drbg));
/* wrap the padlen appropriately */
if (padlen)
padlen = drbg_blocklen(drbg) - padlen;
/*
* pad / padlen contains the 0x80 byte and the following zero bytes.
* As the calculated padlen value only covers the number of zero
* bytes, this value has to be incremented by one for the 0x80 byte.
*/
padlen++;
pad[0] = 0x80;
/* 10.4.2 step 4 -- first fill the linked list and then order it */
drbg_string_fill(&S1, iv, drbg_blocklen(drbg));
list_add_tail(&S1.list, &bcc_list);
drbg_string_fill(&S2, L_N, sizeof(L_N));
list_add_tail(&S2.list, &bcc_list);
list_splice_tail(seedlist, &bcc_list);
drbg_string_fill(&S4, pad, padlen);
list_add_tail(&S4.list, &bcc_list);
/* 10.4.2 step 9 */
while (templen < (drbg_keylen(drbg) + (drbg_blocklen(drbg)))) {
/*
* 10.4.2 step 9.1 - the padding is implicit as the buffer
* holds zeros after allocation -- even the increment of i
* is irrelevant as the increment remains within length of i
*/
drbg_int2byte(iv, i, 4);
/* 10.4.2 step 9.2 -- BCC and concatenation with temp */
ret = drbg_ctr_bcc(drbg, temp + templen, K, &bcc_list);
if (ret)
goto out;
/* 10.4.2 step 9.3 */
i++;
templen += drbg_blocklen(drbg);
}
/* 10.4.2 step 11 */
X = temp + (drbg_keylen(drbg));
drbg_string_fill(&cipherin, X, drbg_blocklen(drbg));
/* 10.4.2 step 12: overwriting of outval is implemented in next step */
/* 10.4.2 step 13 */
while (generated_len < bytes_to_return) {
short blocklen = 0;
/*
* 10.4.2 step 13.1: the truncation of the key length is
* implicit as the key is only drbg_blocklen in size based on
* the implementation of the cipher function callback
*/
ret = drbg_kcapi_sym(drbg, temp, X, &cipherin);
if (ret)
goto out;
blocklen = (drbg_blocklen(drbg) <
(bytes_to_return - generated_len)) ?
drbg_blocklen(drbg) :
(bytes_to_return - generated_len);
/* 10.4.2 step 13.2 and 14 */
memcpy(df_data + generated_len, X, blocklen);
generated_len += blocklen;
}
ret = 0;
out:
memset(iv, 0, drbg_blocklen(drbg));
memset(temp, 0, drbg_statelen(drbg));
memset(pad, 0, drbg_blocklen(drbg));
return ret;
}
/*
* update function of CTR DRBG as defined in 10.2.1.2
*
* The reseed variable has an enhanced meaning compared to the update
* functions of the other DRBGs as follows:
* 0 => initial seed from initialization
* 1 => reseed via drbg_seed
* 2 => first invocation from drbg_ctr_update when addtl is present. In
* this case, the df_data scratchpad is not deleted so that it is
* available for another calls to prevent calling the DF function
* again.
* 3 => second invocation from drbg_ctr_update. When the update function
* was called with addtl, the df_data memory already contains the
* DFed addtl information and we do not need to call DF again.
*/
static int drbg_ctr_update(struct drbg_state *drbg, struct list_head *seed,
int reseed)
{
int ret = -EFAULT;
/* 10.2.1.2 step 1 */
unsigned char *temp = drbg->scratchpad;
unsigned char *df_data = drbg->scratchpad + drbg_statelen(drbg) +
drbg_blocklen(drbg);
unsigned char *temp_p, *df_data_p; /* pointer to iterate over buffers */
unsigned int len = 0;
struct drbg_string cipherin;
unsigned char prefix = DRBG_PREFIX1;
memset(temp, 0, drbg_statelen(drbg) + drbg_blocklen(drbg));
if (3 > reseed)
memset(df_data, 0, drbg_statelen(drbg));
/* 10.2.1.3.2 step 2 and 10.2.1.4.2 step 2 */
if (seed) {
ret = drbg_ctr_df(drbg, df_data, drbg_statelen(drbg), seed);
if (ret)
goto out;
}
drbg_string_fill(&cipherin, drbg->V, drbg_blocklen(drbg));
/*
* 10.2.1.3.2 steps 2 and 3 are already covered as the allocation
* zeroizes all memory during initialization
*/
while (len < (drbg_statelen(drbg))) {
/* 10.2.1.2 step 2.1 */
drbg_add_buf(drbg->V, drbg_blocklen(drbg), &prefix, 1);
/*
* 10.2.1.2 step 2.2 */
ret = drbg_kcapi_sym(drbg, drbg->C, temp + len, &cipherin);
if (ret)
goto out;
/* 10.2.1.2 step 2.3 and 3 */
len += drbg_blocklen(drbg);
}
/* 10.2.1.2 step 4 */
temp_p = temp;
df_data_p = df_data;
for (len = 0; len < drbg_statelen(drbg); len++) {
*temp_p ^= *df_data_p;
df_data_p++; temp_p++;
}
/* 10.2.1.2 step 5 */
memcpy(drbg->C, temp, drbg_keylen(drbg));
/* 10.2.1.2 step 6 */
memcpy(drbg->V, temp + drbg_keylen(drbg), drbg_blocklen(drbg));
ret = 0;
out:
memset(temp, 0, drbg_statelen(drbg) + drbg_blocklen(drbg));
if (2 != reseed)
memset(df_data, 0, drbg_statelen(drbg));
return ret;
}
/*
* scratchpad use: drbg_ctr_update is called independently from
* drbg_ctr_extract_bytes. Therefore, the scratchpad is reused
*/
/* Generate function of CTR DRBG as defined in 10.2.1.5.2 */
static int drbg_ctr_generate(struct drbg_state *drbg,
unsigned char *buf, unsigned int buflen,
struct list_head *addtl)
{
int len = 0;
int ret = 0;
struct drbg_string data;
unsigned char prefix = DRBG_PREFIX1;
memset(drbg->scratchpad, 0, drbg_blocklen(drbg));
/* 10.2.1.5.2 step 2 */
if (addtl && !list_empty(addtl)) {
ret = drbg_ctr_update(drbg, addtl, 2);
if (ret)
return 0;
}
/* 10.2.1.5.2 step 4.1 */
drbg_add_buf(drbg->V, drbg_blocklen(drbg), &prefix, 1);
drbg_string_fill(&data, drbg->V, drbg_blocklen(drbg));
while (len < buflen) {
int outlen = 0;
/* 10.2.1.5.2 step 4.2 */
ret = drbg_kcapi_sym(drbg, drbg->C, drbg->scratchpad, &data);
if (ret) {
len = ret;
goto out;
}
outlen = (drbg_blocklen(drbg) < (buflen - len)) ?
drbg_blocklen(drbg) : (buflen - len);
if (!drbg_fips_continuous_test(drbg, drbg->scratchpad)) {
/* 10.2.1.5.2 step 6 */
drbg_add_buf(drbg->V, drbg_blocklen(drbg), &prefix, 1);
continue;
}
/* 10.2.1.5.2 step 4.3 */
memcpy(buf + len, drbg->scratchpad, outlen);
len += outlen;
/* 10.2.1.5.2 step 6 */
if (len < buflen)
drbg_add_buf(drbg->V, drbg_blocklen(drbg), &prefix, 1);
}
/* 10.2.1.5.2 step 6 */
ret = drbg_ctr_update(drbg, NULL, 3);
if (ret)
len = ret;
out:
memset(drbg->scratchpad, 0, drbg_blocklen(drbg));
return len;
}
static struct drbg_state_ops drbg_ctr_ops = {
.update = drbg_ctr_update,
.generate = drbg_ctr_generate,
.crypto_init = drbg_init_sym_kernel,
.crypto_fini = drbg_fini_sym_kernel,
};
#endif /* CONFIG_CRYPTO_DRBG_CTR */
/******************************************************************
* HMAC DRBG callback functions
******************************************************************/
#if defined(CONFIG_CRYPTO_DRBG_HASH) || defined(CONFIG_CRYPTO_DRBG_HMAC)
static int drbg_kcapi_hash(struct drbg_state *drbg, const unsigned char *key,
unsigned char *outval, const struct list_head *in);
static int drbg_init_hash_kernel(struct drbg_state *drbg);
static int drbg_fini_hash_kernel(struct drbg_state *drbg);
#endif /* (CONFIG_CRYPTO_DRBG_HASH || CONFIG_CRYPTO_DRBG_HMAC) */
#ifdef CONFIG_CRYPTO_DRBG_HMAC
#define CRYPTO_DRBG_HMAC_STRING "HMAC "
/* update function of HMAC DRBG as defined in 10.1.2.2 */
static int drbg_hmac_update(struct drbg_state *drbg, struct list_head *seed,
int reseed)
{
int ret = -EFAULT;
int i = 0;
struct drbg_string seed1, seed2, vdata;
LIST_HEAD(seedlist);
LIST_HEAD(vdatalist);
if (!reseed) {
/* 10.1.2.3 step 2 */
memset(drbg->C, 0, drbg_statelen(drbg));
memset(drbg->V, 1, drbg_statelen(drbg));
}
drbg_string_fill(&seed1, drbg->V, drbg_statelen(drbg));
list_add_tail(&seed1.list, &seedlist);
/* buffer of seed2 will be filled in for loop below with one byte */
drbg_string_fill(&seed2, NULL, 1);
list_add_tail(&seed2.list, &seedlist);
/* input data of seed is allowed to be NULL at this point */
if (seed)
list_splice_tail(seed, &seedlist);
drbg_string_fill(&vdata, drbg->V, drbg_statelen(drbg));
list_add_tail(&vdata.list, &vdatalist);
for (i = 2; 0 < i; i--) {
/* first round uses 0x0, second 0x1 */
unsigned char prefix = DRBG_PREFIX0;
if (1 == i)
prefix = DRBG_PREFIX1;
/* 10.1.2.2 step 1 and 4 -- concatenation and HMAC for key */
seed2.buf = &prefix;
ret = drbg_kcapi_hash(drbg, drbg->C, drbg->C, &seedlist);
if (ret)
return ret;
/* 10.1.2.2 step 2 and 5 -- HMAC for V */
ret = drbg_kcapi_hash(drbg, drbg->C, drbg->V, &vdatalist);
if (ret)
return ret;
/* 10.1.2.2 step 3 */
if (!seed)
return ret;
}
return 0;
}
/* generate function of HMAC DRBG as defined in 10.1.2.5 */
static int drbg_hmac_generate(struct drbg_state *drbg,
unsigned char *buf,
unsigned int buflen,
struct list_head *addtl)
{
int len = 0;
int ret = 0;
struct drbg_string data;
LIST_HEAD(datalist);
/* 10.1.2.5 step 2 */
if (addtl && !list_empty(addtl)) {
ret = drbg_hmac_update(drbg, addtl, 1);
if (ret)
return ret;
}
drbg_string_fill(&data, drbg->V, drbg_statelen(drbg));
list_add_tail(&data.list, &datalist);
while (len < buflen) {
unsigned int outlen = 0;
/* 10.1.2.5 step 4.1 */
ret = drbg_kcapi_hash(drbg, drbg->C, drbg->V, &datalist);
if (ret)
return ret;
outlen = (drbg_blocklen(drbg) < (buflen - len)) ?
drbg_blocklen(drbg) : (buflen - len);
if (!drbg_fips_continuous_test(drbg, drbg->V))
continue;
/* 10.1.2.5 step 4.2 */
memcpy(buf + len, drbg->V, outlen);
len += outlen;
}
/* 10.1.2.5 step 6 */
if (addtl && !list_empty(addtl))
ret = drbg_hmac_update(drbg, addtl, 1);
else
ret = drbg_hmac_update(drbg, NULL, 1);
if (ret)
return ret;
return len;
}
static struct drbg_state_ops drbg_hmac_ops = {
.update = drbg_hmac_update,
.generate = drbg_hmac_generate,
.crypto_init = drbg_init_hash_kernel,
.crypto_fini = drbg_fini_hash_kernel,
};
#endif /* CONFIG_CRYPTO_DRBG_HMAC */
/******************************************************************
* Hash DRBG callback functions
******************************************************************/
#ifdef CONFIG_CRYPTO_DRBG_HASH
#define CRYPTO_DRBG_HASH_STRING "HASH "
/*
* scratchpad usage: as drbg_hash_update and drbg_hash_df are used
* interlinked, the scratchpad is used as follows:
* drbg_hash_update
* start: drbg->scratchpad
* length: drbg_statelen(drbg)
* drbg_hash_df:
* start: drbg->scratchpad + drbg_statelen(drbg)
* length: drbg_blocklen(drbg)
*
* drbg_hash_process_addtl uses the scratchpad, but fully completes
* before either of the functions mentioned before are invoked. Therefore,
* drbg_hash_process_addtl does not need to be specifically considered.
*/
/* Derivation Function for Hash DRBG as defined in 10.4.1 */
static int drbg_hash_df(struct drbg_state *drbg,
unsigned char *outval, size_t outlen,
struct list_head *entropylist)
{
int ret = 0;
size_t len = 0;
unsigned char input[5];
unsigned char *tmp = drbg->scratchpad + drbg_statelen(drbg);
struct drbg_string data;
memset(tmp, 0, drbg_blocklen(drbg));
/* 10.4.1 step 3 */
input[0] = 1;
drbg_int2byte(&input[1], (outlen * 8), 4);
/* 10.4.1 step 4.1 -- concatenation of data for input into hash */
drbg_string_fill(&data, input, 5);
list_add(&data.list, entropylist);
/* 10.4.1 step 4 */
while (len < outlen) {
short blocklen = 0;
/* 10.4.1 step 4.1 */
ret = drbg_kcapi_hash(drbg, NULL, tmp, entropylist);
if (ret)
goto out;
/* 10.4.1 step 4.2 */
input[0]++;
blocklen = (drbg_blocklen(drbg) < (outlen - len)) ?
drbg_blocklen(drbg) : (outlen - len);
memcpy(outval + len, tmp, blocklen);
len += blocklen;
}
out:
memset(tmp, 0, drbg_blocklen(drbg));
return ret;
}
/* update function for Hash DRBG as defined in 10.1.1.2 / 10.1.1.3 */
static int drbg_hash_update(struct drbg_state *drbg, struct list_head *seed,
int reseed)
{
int ret = 0;
struct drbg_string data1, data2;
LIST_HEAD(datalist);
LIST_HEAD(datalist2);
unsigned char *V = drbg->scratchpad;
unsigned char prefix = DRBG_PREFIX1;
memset(drbg->scratchpad, 0, drbg_statelen(drbg));
if (!seed)
return -EINVAL;
if (reseed) {
/* 10.1.1.3 step 1 */
memcpy(V, drbg->V, drbg_statelen(drbg));
drbg_string_fill(&data1, &prefix, 1);
list_add_tail(&data1.list, &datalist);
drbg_string_fill(&data2, V, drbg_statelen(drbg));
list_add_tail(&data2.list, &datalist);
}
list_splice_tail(seed, &datalist);
/* 10.1.1.2 / 10.1.1.3 step 2 and 3 */
ret = drbg_hash_df(drbg, drbg->V, drbg_statelen(drbg), &datalist);
if (ret)
goto out;
/* 10.1.1.2 / 10.1.1.3 step 4 */
prefix = DRBG_PREFIX0;
drbg_string_fill(&data1, &prefix, 1);
list_add_tail(&data1.list, &datalist2);
drbg_string_fill(&data2, drbg->V, drbg_statelen(drbg));
list_add_tail(&data2.list, &datalist2);
/* 10.1.1.2 / 10.1.1.3 step 4 */
ret = drbg_hash_df(drbg, drbg->C, drbg_statelen(drbg), &datalist2);
out:
memset(drbg->scratchpad, 0, drbg_statelen(drbg));
return ret;
}
/* processing of additional information string for Hash DRBG */
static int drbg_hash_process_addtl(struct drbg_state *drbg,
struct list_head *addtl)
{
int ret = 0;
struct drbg_string data1, data2;
LIST_HEAD(datalist);
unsigned char prefix = DRBG_PREFIX2;
/* this is value w as per documentation */
memset(drbg->scratchpad, 0, drbg_blocklen(drbg));
/* 10.1.1.4 step 2 */
if (!addtl || list_empty(addtl))
return 0;
/* 10.1.1.4 step 2a */
drbg_string_fill(&data1, &prefix, 1);
drbg_string_fill(&data2, drbg->V, drbg_statelen(drbg));
list_add_tail(&data1.list, &datalist);
list_add_tail(&data2.list, &datalist);
list_splice_tail(addtl, &datalist);
ret = drbg_kcapi_hash(drbg, NULL, drbg->scratchpad, &datalist);
if (ret)
goto out;
/* 10.1.1.4 step 2b */
drbg_add_buf(drbg->V, drbg_statelen(drbg),
drbg->scratchpad, drbg_blocklen(drbg));
out:
memset(drbg->scratchpad, 0, drbg_blocklen(drbg));
return ret;
}
/* Hashgen defined in 10.1.1.4 */
static int drbg_hash_hashgen(struct drbg_state *drbg,
unsigned char *buf,
unsigned int buflen)
{
int len = 0;
int ret = 0;
unsigned char *src = drbg->scratchpad;
unsigned char *dst = drbg->scratchpad + drbg_statelen(drbg);
struct drbg_string data;
LIST_HEAD(datalist);
unsigned char prefix = DRBG_PREFIX1;
memset(src, 0, drbg_statelen(drbg));
memset(dst, 0, drbg_blocklen(drbg));
/* 10.1.1.4 step hashgen 2 */
memcpy(src, drbg->V, drbg_statelen(drbg));
drbg_string_fill(&data, src, drbg_statelen(drbg));
list_add_tail(&data.list, &datalist);
while (len < buflen) {
unsigned int outlen = 0;
/* 10.1.1.4 step hashgen 4.1 */
ret = drbg_kcapi_hash(drbg, NULL, dst, &datalist);
if (ret) {
len = ret;
goto out;
}
outlen = (drbg_blocklen(drbg) < (buflen - len)) ?
drbg_blocklen(drbg) : (buflen - len);
if (!drbg_fips_continuous_test(drbg, dst)) {
drbg_add_buf(src, drbg_statelen(drbg), &prefix, 1);
continue;
}
/* 10.1.1.4 step hashgen 4.2 */
memcpy(buf + len, dst, outlen);
len += outlen;
/* 10.1.1.4 hashgen step 4.3 */
if (len < buflen)
drbg_add_buf(src, drbg_statelen(drbg), &prefix, 1);
}
out:
memset(drbg->scratchpad, 0,
(drbg_statelen(drbg) + drbg_blocklen(drbg)));
return len;
}
/* generate function for Hash DRBG as defined in 10.1.1.4 */
static int drbg_hash_generate(struct drbg_state *drbg,
unsigned char *buf, unsigned int buflen,
struct list_head *addtl)
{
int len = 0;
int ret = 0;
unsigned char req[8];
unsigned char prefix = DRBG_PREFIX3;
struct drbg_string data1, data2;
LIST_HEAD(datalist);
/* 10.1.1.4 step 2 */
ret = drbg_hash_process_addtl(drbg, addtl);
if (ret)
return ret;
/* 10.1.1.4 step 3 */
len = drbg_hash_hashgen(drbg, buf, buflen);
/* this is the value H as documented in 10.1.1.4 */
memset(drbg->scratchpad, 0, drbg_blocklen(drbg));
/* 10.1.1.4 step 4 */
drbg_string_fill(&data1, &prefix, 1);
list_add_tail(&data1.list, &datalist);
drbg_string_fill(&data2, drbg->V, drbg_statelen(drbg));
list_add_tail(&data2.list, &datalist);
ret = drbg_kcapi_hash(drbg, NULL, drbg->scratchpad, &datalist);
if (ret) {
len = ret;
goto out;
}
/* 10.1.1.4 step 5 */
drbg_add_buf(drbg->V, drbg_statelen(drbg),
drbg->scratchpad, drbg_blocklen(drbg));
drbg_add_buf(drbg->V, drbg_statelen(drbg),
drbg->C, drbg_statelen(drbg));
drbg_int2byte(req, drbg->reseed_ctr, sizeof(req));
drbg_add_buf(drbg->V, drbg_statelen(drbg), req, 8);
out:
memset(drbg->scratchpad, 0, drbg_blocklen(drbg));
return len;
}
/*
* scratchpad usage: as update and generate are used isolated, both
* can use the scratchpad
*/
static struct drbg_state_ops drbg_hash_ops = {
.update = drbg_hash_update,
.generate = drbg_hash_generate,
.crypto_init = drbg_init_hash_kernel,
.crypto_fini = drbg_fini_hash_kernel,
};
#endif /* CONFIG_CRYPTO_DRBG_HASH */
/******************************************************************
* Functions common for DRBG implementations
******************************************************************/
/*
* Seeding or reseeding of the DRBG
*
* @drbg: DRBG state struct
* @pers: personalization / additional information buffer
* @reseed: 0 for initial seed process, 1 for reseeding
*
* return:
* 0 on success
* error value otherwise
*/
static int drbg_seed(struct drbg_state *drbg, struct drbg_string *pers,
bool reseed)
{
int ret = 0;
unsigned char *entropy = NULL;
size_t entropylen = 0;
struct drbg_string data1;
LIST_HEAD(seedlist);
/* 9.1 / 9.2 / 9.3.1 step 3 */
if (pers && pers->len > (drbg_max_addtl(drbg))) {
pr_devel("DRBG: personalization string too long %zu\n",
pers->len);
return -EINVAL;
}
if (drbg->test_data && drbg->test_data->testentropy) {
drbg_string_fill(&data1, drbg->test_data->testentropy->buf,
drbg->test_data->testentropy->len);
pr_devel("DRBG: using test entropy\n");
} else {
/*
* Gather entropy equal to the security strength of the DRBG.
* With a derivation function, a nonce is required in addition
* to the entropy. A nonce must be at least 1/2 of the security
* strength of the DRBG in size. Thus, entropy * nonce is 3/2
* of the strength. The consideration of a nonce is only
* applicable during initial seeding.
*/
entropylen = drbg_sec_strength(drbg->core->flags);
if (!entropylen)
return -EFAULT;
if (!reseed)
entropylen = ((entropylen + 1) / 2) * 3;
pr_devel("DRBG: (re)seeding with %zu bytes of entropy\n",
entropylen);
entropy = kzalloc(entropylen, GFP_KERNEL);
if (!entropy)
return -ENOMEM;
get_random_bytes(entropy, entropylen);
drbg_string_fill(&data1, entropy, entropylen);
}
list_add_tail(&data1.list, &seedlist);
/*
* concatenation of entropy with personalization str / addtl input)
* the variable pers is directly handed in by the caller, so check its
* contents whether it is appropriate
*/
if (pers && pers->buf && 0 < pers->len) {
list_add_tail(&pers->list, &seedlist);
pr_devel("DRBG: using personalization string\n");
}
ret = drbg->d_ops->update(drbg, &seedlist, reseed);
if (ret)
goto out;
drbg->seeded = true;
/* 10.1.1.2 / 10.1.1.3 step 5 */
drbg->reseed_ctr = 1;
out:
if (entropy)
kzfree(entropy);
return ret;
}
/* Free all substructures in a DRBG state without the DRBG state structure */
static inline void drbg_dealloc_state(struct drbg_state *drbg)
{
if (!drbg)
return;
if (drbg->V)
kzfree(drbg->V);
drbg->V = NULL;
if (drbg->C)
kzfree(drbg->C);
drbg->C = NULL;
if (drbg->scratchpad)
kzfree(drbg->scratchpad);
drbg->scratchpad = NULL;
drbg->reseed_ctr = 0;
#ifdef CONFIG_CRYPTO_FIPS
if (drbg->prev)
kzfree(drbg->prev);
drbg->prev = NULL;
drbg->fips_primed = false;
#endif
}
/*
* Allocate all sub-structures for a DRBG state.
* The DRBG state structure must already be allocated.
*/
static inline int drbg_alloc_state(struct drbg_state *drbg)
{
int ret = -ENOMEM;
unsigned int sb_size = 0;
if (!drbg)
return -EINVAL;
drbg->V = kzalloc(drbg_statelen(drbg), GFP_KERNEL);
if (!drbg->V)
goto err;
drbg->C = kzalloc(drbg_statelen(drbg), GFP_KERNEL);
if (!drbg->C)
goto err;
#ifdef CONFIG_CRYPTO_FIPS
drbg->prev = kzalloc(drbg_blocklen(drbg), GFP_KERNEL);
if (!drbg->prev)
goto err;
drbg->fips_primed = false;
#endif
/* scratchpad is only generated for CTR and Hash */
if (drbg->core->flags & DRBG_HMAC)
sb_size = 0;
else if (drbg->core->flags & DRBG_CTR)
sb_size = drbg_statelen(drbg) + drbg_blocklen(drbg) + /* temp */
drbg_statelen(drbg) + /* df_data */
drbg_blocklen(drbg) + /* pad */
drbg_blocklen(drbg) + /* iv */
drbg_statelen(drbg) + drbg_blocklen(drbg); /* temp */
else
sb_size = drbg_statelen(drbg) + drbg_blocklen(drbg);
if (0 < sb_size) {
drbg->scratchpad = kzalloc(sb_size, GFP_KERNEL);
if (!drbg->scratchpad)
goto err;
}
spin_lock_init(&drbg->drbg_lock);
return 0;
err:
drbg_dealloc_state(drbg);
return ret;
}
/*
* Strategy to avoid holding long term locks: generate a shadow copy of DRBG
* and perform all operations on this shadow copy. After finishing, restore
* the updated state of the shadow copy into original drbg state. This way,
* only the read and write operations of the original drbg state must be
* locked
*/
static inline void drbg_copy_drbg(struct drbg_state *src,
struct drbg_state *dst)
{
if (!src || !dst)
return;
memcpy(dst->V, src->V, drbg_statelen(src));
memcpy(dst->C, src->C, drbg_statelen(src));
dst->reseed_ctr = src->reseed_ctr;
dst->seeded = src->seeded;
dst->pr = src->pr;
#ifdef CONFIG_CRYPTO_FIPS
dst->fips_primed = src->fips_primed;
memcpy(dst->prev, src->prev, drbg_blocklen(src));
#endif
/*
* Not copied:
* scratchpad is initialized drbg_alloc_state;
* priv_data is initialized with call to crypto_init;
* d_ops and core are set outside, as these parameters are const;
* test_data is set outside to prevent it being copied back.
*/
}
static int drbg_make_shadow(struct drbg_state *drbg, struct drbg_state **shadow)
{
int ret = -ENOMEM;
struct drbg_state *tmp = NULL;
if (!drbg || !drbg->core || !drbg->V || !drbg->C) {
pr_devel("DRBG: attempt to generate shadow copy for "
"uninitialized DRBG state rejected\n");
return -EINVAL;
}
/* HMAC does not have a scratchpad */
if (!(drbg->core->flags & DRBG_HMAC) && NULL == drbg->scratchpad)
return -EINVAL;
tmp = kzalloc(sizeof(struct drbg_state), GFP_KERNEL);
if (!tmp)
return -ENOMEM;
/* read-only data as they are defined as const, no lock needed */
tmp->core = drbg->core;
tmp->d_ops = drbg->d_ops;
ret = drbg_alloc_state(tmp);
if (ret)
goto err;
spin_lock_bh(&drbg->drbg_lock);
drbg_copy_drbg(drbg, tmp);
/* only make a link to the test buffer, as we only read that data */
tmp->test_data = drbg->test_data;
spin_unlock_bh(&drbg->drbg_lock);
*shadow = tmp;
return 0;
err:
if (tmp)
kzfree(tmp);
return ret;
}
static void drbg_restore_shadow(struct drbg_state *drbg,
struct drbg_state **shadow)
{
struct drbg_state *tmp = *shadow;
spin_lock_bh(&drbg->drbg_lock);
drbg_copy_drbg(tmp, drbg);
spin_unlock_bh(&drbg->drbg_lock);
drbg_dealloc_state(tmp);
kzfree(tmp);
*shadow = NULL;
}
/*************************************************************************
* DRBG interface functions
*************************************************************************/
/*
* DRBG generate function as required by SP800-90A - this function
* generates random numbers
*
* @drbg DRBG state handle
* @buf Buffer where to store the random numbers -- the buffer must already
* be pre-allocated by caller
* @buflen Length of output buffer - this value defines the number of random
* bytes pulled from DRBG
* @addtl Additional input that is mixed into state, may be NULL -- note
* the entropy is pulled by the DRBG internally unconditionally
* as defined in SP800-90A. The additional input is mixed into
* the state in addition to the pulled entropy.
*
* return: generated number of bytes
*/
static int drbg_generate(struct drbg_state *drbg,
unsigned char *buf, unsigned int buflen,
struct drbg_string *addtl)
{
int len = 0;
struct drbg_state *shadow = NULL;
LIST_HEAD(addtllist);
struct drbg_string timestamp;
union {
cycles_t cycles;
unsigned char char_cycles[sizeof(cycles_t)];
} now;
if (0 == buflen || !buf) {
pr_devel("DRBG: no output buffer provided\n");
return -EINVAL;
}
if (addtl && NULL == addtl->buf && 0 < addtl->len) {
pr_devel("DRBG: wrong format of additional information\n");
return -EINVAL;
}
len = drbg_make_shadow(drbg, &shadow);
if (len) {
pr_devel("DRBG: shadow copy cannot be generated\n");
return len;
}
/* 9.3.1 step 2 */
len = -EINVAL;
if (buflen > (drbg_max_request_bytes(shadow))) {
pr_devel("DRBG: requested random numbers too large %u\n",
buflen);
goto err;
}
/* 9.3.1 step 3 is implicit with the chosen DRBG */
/* 9.3.1 step 4 */
if (addtl && addtl->len > (drbg_max_addtl(shadow))) {
pr_devel("DRBG: additional information string too long %zu\n",
addtl->len);
goto err;
}
/* 9.3.1 step 5 is implicit with the chosen DRBG */
/*
* 9.3.1 step 6 and 9 supplemented by 9.3.2 step c is implemented
* here. The spec is a bit convoluted here, we make it simpler.
*/
if ((drbg_max_requests(shadow)) < shadow->reseed_ctr)
shadow->seeded = false;
/* allocate cipher handle */
if (shadow->d_ops->crypto_init) {
len = shadow->d_ops->crypto_init(shadow);
if (len)
goto err;
}
if (shadow->pr || !shadow->seeded) {
pr_devel("DRBG: reseeding before generation (prediction "
"resistance: %s, state %s)\n",
drbg->pr ? "true" : "false",
drbg->seeded ? "seeded" : "unseeded");
/* 9.3.1 steps 7.1 through 7.3 */
len = drbg_seed(shadow, addtl, true);
if (len)
goto err;
/* 9.3.1 step 7.4 */
addtl = NULL;
}
/*
* Mix the time stamp into the DRBG state if the DRBG is not in
* test mode. If there are two callers invoking the DRBG at the same
* time, i.e. before the first caller merges its shadow state back,
* both callers would obtain the same random number stream without
* changing the state here.
*/
if (!drbg->test_data) {
now.cycles = random_get_entropy();
drbg_string_fill(&timestamp, now.char_cycles, sizeof(cycles_t));
list_add_tail(&timestamp.list, &addtllist);
}
if (addtl && 0 < addtl->len)
list_add_tail(&addtl->list, &addtllist);
/* 9.3.1 step 8 and 10 */
len = shadow->d_ops->generate(shadow, buf, buflen, &addtllist);
/* 10.1.1.4 step 6, 10.1.2.5 step 7, 10.2.1.5.2 step 7 */
shadow->reseed_ctr++;
if (0 >= len)
goto err;
/*
* Section 11.3.3 requires to re-perform self tests after some
* generated random numbers. The chosen value after which self
* test is performed is arbitrary, but it should be reasonable.
* However, we do not perform the self tests because of the following
* reasons: it is mathematically impossible that the initial self tests
* were successfully and the following are not. If the initial would
* pass and the following would not, the kernel integrity is violated.
* In this case, the entire kernel operation is questionable and it
* is unlikely that the integrity violation only affects the
* correct operation of the DRBG.
*
* Albeit the following code is commented out, it is provided in
* case somebody has a need to implement the test of 11.3.3.
*/
#if 0
if (shadow->reseed_ctr && !(shadow->reseed_ctr % 4096)) {
int err = 0;
pr_devel("DRBG: start to perform self test\n");
if (drbg->core->flags & DRBG_HMAC)
err = alg_test("drbg_pr_hmac_sha256",
"drbg_pr_hmac_sha256", 0, 0);
else if (drbg->core->flags & DRBG_CTR)
err = alg_test("drbg_pr_ctr_aes128",
"drbg_pr_ctr_aes128", 0, 0);
else
err = alg_test("drbg_pr_sha256",
"drbg_pr_sha256", 0, 0);
if (err) {
pr_err("DRBG: periodical self test failed\n");
/*
* uninstantiate implies that from now on, only errors
* are returned when reusing this DRBG cipher handle
*/
drbg_uninstantiate(drbg);
drbg_dealloc_state(shadow);
kzfree(shadow);
return 0;
} else {
pr_devel("DRBG: self test successful\n");
}
}
#endif
err:
if (shadow->d_ops->crypto_fini)
shadow->d_ops->crypto_fini(shadow);
drbg_restore_shadow(drbg, &shadow);
return len;
}
/*
* Wrapper around drbg_generate which can pull arbitrary long strings
* from the DRBG without hitting the maximum request limitation.
*
* Parameters: see drbg_generate
* Return codes: see drbg_generate -- if one drbg_generate request fails,
* the entire drbg_generate_long request fails
*/
static int drbg_generate_long(struct drbg_state *drbg,
unsigned char *buf, unsigned int buflen,
struct drbg_string *addtl)
{
int len = 0;
unsigned int slice = 0;
do {
int tmplen = 0;
unsigned int chunk = 0;
slice = ((buflen - len) / drbg_max_request_bytes(drbg));
chunk = slice ? drbg_max_request_bytes(drbg) : (buflen - len);
tmplen = drbg_generate(drbg, buf + len, chunk, addtl);
if (0 >= tmplen)
return tmplen;
len += tmplen;
} while (slice > 0 && (len < buflen));
return len;
}
/*
* DRBG instantiation function as required by SP800-90A - this function
* sets up the DRBG handle, performs the initial seeding and all sanity
* checks required by SP800-90A
*
* @drbg memory of state -- if NULL, new memory is allocated
* @pers Personalization string that is mixed into state, may be NULL -- note
* the entropy is pulled by the DRBG internally unconditionally
* as defined in SP800-90A. The additional input is mixed into
* the state in addition to the pulled entropy.
* @coreref reference to core
* @pr prediction resistance enabled
*
* return
* 0 on success
* error value otherwise
*/
static int drbg_instantiate(struct drbg_state *drbg, struct drbg_string *pers,
int coreref, bool pr)
{
int ret = -ENOMEM;
pr_devel("DRBG: Initializing DRBG core %d with prediction resistance "
"%s\n", coreref, pr ? "enabled" : "disabled");
drbg->core = &drbg_cores[coreref];
drbg->pr = pr;
drbg->seeded = false;
switch (drbg->core->flags & DRBG_TYPE_MASK) {
#ifdef CONFIG_CRYPTO_DRBG_HMAC
case DRBG_HMAC:
drbg->d_ops = &drbg_hmac_ops;
break;
#endif /* CONFIG_CRYPTO_DRBG_HMAC */
#ifdef CONFIG_CRYPTO_DRBG_HASH
case DRBG_HASH:
drbg->d_ops = &drbg_hash_ops;
break;
#endif /* CONFIG_CRYPTO_DRBG_HASH */
#ifdef CONFIG_CRYPTO_DRBG_CTR
case DRBG_CTR:
drbg->d_ops = &drbg_ctr_ops;
break;
#endif /* CONFIG_CRYPTO_DRBG_CTR */
default:
return -EOPNOTSUPP;
}
/* 9.1 step 1 is implicit with the selected DRBG type */
/*
* 9.1 step 2 is implicit as caller can select prediction resistance
* and the flag is copied into drbg->flags --
* all DRBG types support prediction resistance
*/
/* 9.1 step 4 is implicit in drbg_sec_strength */
ret = drbg_alloc_state(drbg);
if (ret)
return ret;
ret = -EFAULT;
if (drbg->d_ops->crypto_init && drbg->d_ops->crypto_init(drbg))
goto err;
ret = drbg_seed(drbg, pers, false);
if (drbg->d_ops->crypto_fini)
drbg->d_ops->crypto_fini(drbg);
if (ret)
goto err;
return 0;
err:
drbg_dealloc_state(drbg);
return ret;
}
/*
* DRBG uninstantiate function as required by SP800-90A - this function
* frees all buffers and the DRBG handle
*
* @drbg DRBG state handle
*
* return
* 0 on success
*/
static int drbg_uninstantiate(struct drbg_state *drbg)
{
spin_lock_bh(&drbg->drbg_lock);
drbg_dealloc_state(drbg);
/* no scrubbing of test_data -- this shall survive an uninstantiate */
spin_unlock_bh(&drbg->drbg_lock);
return 0;
}
/*
* Helper function for setting the test data in the DRBG
*
* @drbg DRBG state handle
* @test_data test data to sets
*/
static inline void drbg_set_testdata(struct drbg_state *drbg,
struct drbg_test_data *test_data)
{
if (!test_data || !test_data->testentropy)
return;
spin_lock_bh(&drbg->drbg_lock);
drbg->test_data = test_data;
spin_unlock_bh(&drbg->drbg_lock);
}
/***************************************************************
* Kernel crypto API cipher invocations requested by DRBG
***************************************************************/
#if defined(CONFIG_CRYPTO_DRBG_HASH) || defined(CONFIG_CRYPTO_DRBG_HMAC)
struct sdesc {
struct shash_desc shash;
char ctx[];
};
static int drbg_init_hash_kernel(struct drbg_state *drbg)
{
struct sdesc *sdesc;
struct crypto_shash *tfm;
tfm = crypto_alloc_shash(drbg->core->backend_cra_name, 0, 0);
if (IS_ERR(tfm)) {
pr_info("DRBG: could not allocate digest TFM handle\n");
return PTR_ERR(tfm);
}
BUG_ON(drbg_blocklen(drbg) != crypto_shash_digestsize(tfm));
sdesc = kzalloc(sizeof(struct shash_desc) + crypto_shash_descsize(tfm),
GFP_KERNEL);
if (!sdesc) {
crypto_free_shash(tfm);
return -ENOMEM;
}
sdesc->shash.tfm = tfm;
sdesc->shash.flags = 0;
drbg->priv_data = sdesc;
return 0;
}
static int drbg_fini_hash_kernel(struct drbg_state *drbg)
{
struct sdesc *sdesc = (struct sdesc *)drbg->priv_data;
if (sdesc) {
crypto_free_shash(sdesc->shash.tfm);
kzfree(sdesc);
}
drbg->priv_data = NULL;
return 0;
}
static int drbg_kcapi_hash(struct drbg_state *drbg, const unsigned char *key,
unsigned char *outval, const struct list_head *in)
{
struct sdesc *sdesc = (struct sdesc *)drbg->priv_data;
struct drbg_string *input = NULL;
if (key)
crypto_shash_setkey(sdesc->shash.tfm, key, drbg_statelen(drbg));
crypto_shash_init(&sdesc->shash);
list_for_each_entry(input, in, list)
crypto_shash_update(&sdesc->shash, input->buf, input->len);
return crypto_shash_final(&sdesc->shash, outval);
}
#endif /* (CONFIG_CRYPTO_DRBG_HASH || CONFIG_CRYPTO_DRBG_HMAC) */
#ifdef CONFIG_CRYPTO_DRBG_CTR
static int drbg_init_sym_kernel(struct drbg_state *drbg)
{
int ret = 0;
struct crypto_blkcipher *tfm;
tfm = crypto_alloc_blkcipher(drbg->core->backend_cra_name, 0, 0);
if (IS_ERR(tfm)) {
pr_info("DRBG: could not allocate cipher TFM handle\n");
return PTR_ERR(tfm);
}
BUG_ON(drbg_blocklen(drbg) != crypto_blkcipher_blocksize(tfm));
drbg->priv_data = tfm;
return ret;
}
static int drbg_fini_sym_kernel(struct drbg_state *drbg)
{
struct crypto_blkcipher *tfm =
(struct crypto_blkcipher *)drbg->priv_data;
if (tfm)
crypto_free_blkcipher(tfm);
drbg->priv_data = NULL;
return 0;
}
static int drbg_kcapi_sym(struct drbg_state *drbg, const unsigned char *key,
unsigned char *outval, const struct drbg_string *in)
{
int ret = 0;
struct scatterlist sg_in, sg_out;
struct blkcipher_desc desc;
struct crypto_blkcipher *tfm =
(struct crypto_blkcipher *)drbg->priv_data;
desc.tfm = tfm;
desc.flags = 0;
crypto_blkcipher_setkey(tfm, key, (drbg_keylen(drbg)));
/* there is only component in *in */
sg_init_one(&sg_in, in->buf, in->len);
sg_init_one(&sg_out, outval, drbg_blocklen(drbg));
ret = crypto_blkcipher_encrypt(&desc, &sg_out, &sg_in, in->len);
return ret;
}
#endif /* CONFIG_CRYPTO_DRBG_CTR */
/***************************************************************
* Kernel crypto API interface to register DRBG
***************************************************************/
/*
* Look up the DRBG flags by given kernel crypto API cra_name
* The code uses the drbg_cores definition to do this
*
* @cra_name kernel crypto API cra_name
* @coreref reference to integer which is filled with the pointer to
* the applicable core
* @pr reference for setting prediction resistance
*
* return: flags
*/
static inline void drbg_convert_tfm_core(const char *cra_driver_name,
int *coreref, bool *pr)
{
int i = 0;
size_t start = 0;
int len = 0;
*pr = true;
/* disassemble the names */
if (!memcmp(cra_driver_name, "drbg_nopr_", 10)) {
start = 10;
*pr = false;
} else if (!memcmp(cra_driver_name, "drbg_pr_", 8)) {
start = 8;
} else {
return;
}
/* remove the first part */
len = strlen(cra_driver_name) - start;
for (i = 0; ARRAY_SIZE(drbg_cores) > i; i++) {
if (!memcmp(cra_driver_name + start, drbg_cores[i].cra_name,
len)) {
*coreref = i;
return;
}
}
}
static int drbg_kcapi_init(struct crypto_tfm *tfm)
{
struct drbg_state *drbg = crypto_tfm_ctx(tfm);
bool pr = false;
int coreref = 0;
drbg_convert_tfm_core(crypto_tfm_alg_driver_name(tfm), &coreref, &pr);
/*
* when personalization string is needed, the caller must call reset
* and provide the personalization string as seed information
*/
return drbg_instantiate(drbg, NULL, coreref, pr);
}
static void drbg_kcapi_cleanup(struct crypto_tfm *tfm)
{
drbg_uninstantiate(crypto_tfm_ctx(tfm));
}
/*
* Generate random numbers invoked by the kernel crypto API:
* The API of the kernel crypto API is extended as follows:
*
* If dlen is larger than zero, rdata is interpreted as the output buffer
* where random data is to be stored.
*
* If dlen is zero, rdata is interpreted as a pointer to a struct drbg_gen
* which holds the additional information string that is used for the
* DRBG generation process. The output buffer that is to be used to store
* data is also pointed to by struct drbg_gen.
*/
static int drbg_kcapi_random(struct crypto_rng *tfm, u8 *rdata,
unsigned int dlen)
{
struct drbg_state *drbg = crypto_rng_ctx(tfm);
if (0 < dlen) {
return drbg_generate_long(drbg, rdata, dlen, NULL);
} else {
struct drbg_gen *data = (struct drbg_gen *)rdata;
struct drbg_string addtl;
/* catch NULL pointer */
if (!data)
return 0;
drbg_set_testdata(drbg, data->test_data);
/* linked list variable is now local to allow modification */
drbg_string_fill(&addtl, data->addtl->buf, data->addtl->len);
return drbg_generate_long(drbg, data->outbuf, data->outlen,
&addtl);
}
}
/*
* Reset the DRBG invoked by the kernel crypto API
* The reset implies a full re-initialization of the DRBG. Similar to the
* generate function of drbg_kcapi_random, this function extends the
* kernel crypto API interface with struct drbg_gen
*/
static int drbg_kcapi_reset(struct crypto_rng *tfm, u8 *seed, unsigned int slen)
{
struct drbg_state *drbg = crypto_rng_ctx(tfm);
struct crypto_tfm *tfm_base = crypto_rng_tfm(tfm);
bool pr = false;
struct drbg_string seed_string;
int coreref = 0;
drbg_uninstantiate(drbg);
drbg_convert_tfm_core(crypto_tfm_alg_driver_name(tfm_base), &coreref,
&pr);
if (0 < slen) {
drbg_string_fill(&seed_string, seed, slen);
return drbg_instantiate(drbg, &seed_string, coreref, pr);
} else {
struct drbg_gen *data = (struct drbg_gen *)seed;
/* allow invocation of API call with NULL, 0 */
if (!data)
return drbg_instantiate(drbg, NULL, coreref, pr);
drbg_set_testdata(drbg, data->test_data);
/* linked list variable is now local to allow modification */
drbg_string_fill(&seed_string, data->addtl->buf,
data->addtl->len);
return drbg_instantiate(drbg, &seed_string, coreref, pr);
}
}
/***************************************************************
* Kernel module: code to load the module
***************************************************************/
/*
* Tests as defined in 11.3.2 in addition to the cipher tests: testing
* of the error handling.
*
* Note: testing of failing seed source as defined in 11.3.2 is not applicable
* as seed source of get_random_bytes does not fail.
*
* Note 2: There is no sensible way of testing the reseed counter
* enforcement, so skip it.
*/
static inline int __init drbg_healthcheck_sanity(void)
{
#ifdef CONFIG_CRYPTO_FIPS
int len = 0;
#define OUTBUFLEN 16
unsigned char buf[OUTBUFLEN];
struct drbg_state *drbg = NULL;
int ret = -EFAULT;
int rc = -EFAULT;
bool pr = false;
int coreref = 0;
struct drbg_string addtl;
size_t max_addtllen, max_request_bytes;
/* only perform test in FIPS mode */
if (!fips_enabled)
return 0;
#ifdef CONFIG_CRYPTO_DRBG_CTR
drbg_convert_tfm_core("drbg_nopr_ctr_aes128", &coreref, &pr);
#elif defined CONFIG_CRYPTO_DRBG_HASH
drbg_convert_tfm_core("drbg_nopr_sha256", &coreref, &pr);
#else
drbg_convert_tfm_core("drbg_nopr_hmac_sha256", &coreref, &pr);
#endif
drbg = kzalloc(sizeof(struct drbg_state), GFP_KERNEL);
if (!drbg)
return -ENOMEM;
/*
* if the following tests fail, it is likely that there is a buffer
* overflow as buf is much smaller than the requested or provided
* string lengths -- in case the error handling does not succeed
* we may get an OOPS. And we want to get an OOPS as this is a
* grave bug.
*/
/* get a valid instance of DRBG for following tests */
ret = drbg_instantiate(drbg, NULL, coreref, pr);
if (ret) {
rc = ret;
goto outbuf;
}
max_addtllen = drbg_max_addtl(drbg);
max_request_bytes = drbg_max_request_bytes(drbg);
drbg_string_fill(&addtl, buf, max_addtllen + 1);
/* overflow addtllen with additonal info string */
len = drbg_generate(drbg, buf, OUTBUFLEN, &addtl);
BUG_ON(0 < len);
/* overflow max_bits */
len = drbg_generate(drbg, buf, (max_request_bytes + 1), NULL);
BUG_ON(0 < len);
drbg_uninstantiate(drbg);
/* overflow max addtllen with personalization string */
ret = drbg_instantiate(drbg, &addtl, coreref, pr);
BUG_ON(0 == ret);
/* all tests passed */
rc = 0;
pr_devel("DRBG: Sanity tests for failure code paths successfully "
"completed\n");
drbg_uninstantiate(drbg);
outbuf:
kzfree(drbg);
return rc;
#else /* CONFIG_CRYPTO_FIPS */
return 0;
#endif /* CONFIG_CRYPTO_FIPS */
}
static struct crypto_alg drbg_algs[22];
/*
* Fill the array drbg_algs used to register the different DRBGs
* with the kernel crypto API. To fill the array, the information
* from drbg_cores[] is used.
*/
static inline void __init drbg_fill_array(struct crypto_alg *alg,
const struct drbg_core *core, int pr)
{
int pos = 0;
static int priority = 100;
memset(alg, 0, sizeof(struct crypto_alg));
memcpy(alg->cra_name, "stdrng", 6);
if (pr) {
memcpy(alg->cra_driver_name, "drbg_pr_", 8);
pos = 8;
} else {
memcpy(alg->cra_driver_name, "drbg_nopr_", 10);
pos = 10;
}
memcpy(alg->cra_driver_name + pos, core->cra_name,
strlen(core->cra_name));
alg->cra_priority = priority;
priority++;
/*
* If FIPS mode enabled, the selected DRBG shall have the
* highest cra_priority over other stdrng instances to ensure
* it is selected.
*/
if (fips_enabled)
alg->cra_priority += 200;
alg->cra_flags = CRYPTO_ALG_TYPE_RNG;
alg->cra_ctxsize = sizeof(struct drbg_state);
alg->cra_type = &crypto_rng_type;
alg->cra_module = THIS_MODULE;
alg->cra_init = drbg_kcapi_init;
alg->cra_exit = drbg_kcapi_cleanup;
alg->cra_u.rng.rng_make_random = drbg_kcapi_random;
alg->cra_u.rng.rng_reset = drbg_kcapi_reset;
alg->cra_u.rng.seedsize = 0;
}
static int __init drbg_init(void)
{
unsigned int i = 0; /* pointer to drbg_algs */
unsigned int j = 0; /* pointer to drbg_cores */
int ret = -EFAULT;
ret = drbg_healthcheck_sanity();
if (ret)
return ret;
if (ARRAY_SIZE(drbg_cores) * 2 > ARRAY_SIZE(drbg_algs)) {
pr_info("DRBG: Cannot register all DRBG types"
"(slots needed: %zu, slots available: %zu)\n",
ARRAY_SIZE(drbg_cores) * 2, ARRAY_SIZE(drbg_algs));
return ret;
}
/*
* each DRBG definition can be used with PR and without PR, thus
* we instantiate each DRBG in drbg_cores[] twice.
*
* As the order of placing them into the drbg_algs array matters
* (the later DRBGs receive a higher cra_priority) we register the
* prediction resistance DRBGs first as the should not be too
* interesting.
*/
for (j = 0; ARRAY_SIZE(drbg_cores) > j; j++, i++)
drbg_fill_array(&drbg_algs[i], &drbg_cores[j], 1);
for (j = 0; ARRAY_SIZE(drbg_cores) > j; j++, i++)
drbg_fill_array(&drbg_algs[i], &drbg_cores[j], 0);
return crypto_register_algs(drbg_algs, (ARRAY_SIZE(drbg_cores) * 2));
}
static void __exit drbg_exit(void)
{
crypto_unregister_algs(drbg_algs, (ARRAY_SIZE(drbg_cores) * 2));
}
module_init(drbg_init);
module_exit(drbg_exit);
#ifndef CRYPTO_DRBG_HASH_STRING
#define CRYPTO_DRBG_HASH_STRING ""
#endif
#ifndef CRYPTO_DRBG_HMAC_STRING
#define CRYPTO_DRBG_HMAC_STRING ""
#endif
#ifndef CRYPTO_DRBG_CTR_STRING
#define CRYPTO_DRBG_CTR_STRING ""
#endif
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Stephan Mueller <smueller@chronox.de>");
MODULE_DESCRIPTION("NIST SP800-90A Deterministic Random Bit Generator (DRBG) "
"using following cores: "
CRYPTO_DRBG_HASH_STRING
CRYPTO_DRBG_HMAC_STRING
CRYPTO_DRBG_CTR_STRING);
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