diff options
Diffstat (limited to 'crypto/dh_helper.c')
| -rw-r--r-- | crypto/dh_helper.c | 122 |
1 files changed, 122 insertions, 0 deletions
diff --git a/crypto/dh_helper.c b/crypto/dh_helper.c new file mode 100644 index 000000000..edacda5f6 --- /dev/null +++ b/crypto/dh_helper.c @@ -0,0 +1,122 @@ +/* + * Copyright (c) 2016, Intel Corporation + * Authors: Salvatore Benedetto <salvatore.benedetto@intel.com> + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation; either version + * 2 of the License, or (at your option) any later version. + */ +#include <linux/kernel.h> +#include <linux/export.h> +#include <linux/err.h> +#include <linux/string.h> +#include <crypto/dh.h> +#include <crypto/kpp.h> + +#define DH_KPP_SECRET_MIN_SIZE (sizeof(struct kpp_secret) + 4 * sizeof(int)) + +static inline u8 *dh_pack_data(u8 *dst, u8 *end, const void *src, size_t size) +{ + if (!dst || size > end - dst) + return NULL; + memcpy(dst, src, size); + return dst + size; +} + +static inline const u8 *dh_unpack_data(void *dst, const void *src, size_t size) +{ + memcpy(dst, src, size); + return src + size; +} + +static inline unsigned int dh_data_size(const struct dh *p) +{ + return p->key_size + p->p_size + p->q_size + p->g_size; +} + +unsigned int crypto_dh_key_len(const struct dh *p) +{ + return DH_KPP_SECRET_MIN_SIZE + dh_data_size(p); +} +EXPORT_SYMBOL_GPL(crypto_dh_key_len); + +int crypto_dh_encode_key(char *buf, unsigned int len, const struct dh *params) +{ + u8 *ptr = buf; + u8 * const end = ptr + len; + struct kpp_secret secret = { + .type = CRYPTO_KPP_SECRET_TYPE_DH, + .len = len + }; + + if (unlikely(!len)) + return -EINVAL; + + ptr = dh_pack_data(ptr, end, &secret, sizeof(secret)); + ptr = dh_pack_data(ptr, end, ¶ms->key_size, + sizeof(params->key_size)); + ptr = dh_pack_data(ptr, end, ¶ms->p_size, sizeof(params->p_size)); + ptr = dh_pack_data(ptr, end, ¶ms->q_size, sizeof(params->q_size)); + ptr = dh_pack_data(ptr, end, ¶ms->g_size, sizeof(params->g_size)); + ptr = dh_pack_data(ptr, end, params->key, params->key_size); + ptr = dh_pack_data(ptr, end, params->p, params->p_size); + ptr = dh_pack_data(ptr, end, params->q, params->q_size); + ptr = dh_pack_data(ptr, end, params->g, params->g_size); + if (ptr != end) + return -EINVAL; + return 0; +} +EXPORT_SYMBOL_GPL(crypto_dh_encode_key); + +int crypto_dh_decode_key(const char *buf, unsigned int len, struct dh *params) +{ + const u8 *ptr = buf; + struct kpp_secret secret; + + if (unlikely(!buf || len < DH_KPP_SECRET_MIN_SIZE)) + return -EINVAL; + + ptr = dh_unpack_data(&secret, ptr, sizeof(secret)); + if (secret.type != CRYPTO_KPP_SECRET_TYPE_DH) + return -EINVAL; + + ptr = dh_unpack_data(¶ms->key_size, ptr, sizeof(params->key_size)); + ptr = dh_unpack_data(¶ms->p_size, ptr, sizeof(params->p_size)); + ptr = dh_unpack_data(¶ms->q_size, ptr, sizeof(params->q_size)); + ptr = dh_unpack_data(¶ms->g_size, ptr, sizeof(params->g_size)); + if (secret.len != crypto_dh_key_len(params)) + return -EINVAL; + + /* + * Don't permit the buffer for 'key' or 'g' to be larger than 'p', since + * some drivers assume otherwise. + */ + if (params->key_size > params->p_size || + params->g_size > params->p_size || params->q_size > params->p_size) + return -EINVAL; + + /* Don't allocate memory. Set pointers to data within + * the given buffer + */ + params->key = (void *)ptr; + params->p = (void *)(ptr + params->key_size); + params->q = (void *)(ptr + params->key_size + params->p_size); + params->g = (void *)(ptr + params->key_size + params->p_size + + params->q_size); + + /* + * Don't permit 'p' to be 0. It's not a prime number, and it's subject + * to corner cases such as 'mod 0' being undefined or + * crypto_kpp_maxsize() returning 0. + */ + if (memchr_inv(params->p, 0, params->p_size) == NULL) + return -EINVAL; + + /* It is permissible to not provide Q. */ + if (params->q_size == 0) + params->q = NULL; + + return 0; +} +EXPORT_SYMBOL_GPL(crypto_dh_decode_key); |