From a07203fbfcf146b737781ee4658ed198956036ca Mon Sep 17 00:00:00 2001 From: Stephan Mueller Date: Tue, 14 Jun 2016 07:35:37 +0200 Subject: [PATCH] crypto: drbg - use full CTR AES for update The CTR DRBG update function performs a full CTR AES operation including the XOR with "plaintext" data. Hence, remove the XOR from the code and use the CTR mode to do the XOR. Signed-off-by: Stephan Mueller Signed-off-by: Herbert Xu --- crypto/drbg.c | 30 +++++++++++++----------------- 1 file changed, 13 insertions(+), 17 deletions(-) diff --git a/crypto/drbg.c b/crypto/drbg.c index 8ac3ea11d437..8ceb71699dea 100644 --- a/crypto/drbg.c +++ b/crypto/drbg.c @@ -258,7 +258,10 @@ static int drbg_kcapi_sym(struct drbg_state *drbg, unsigned char *outval, const struct drbg_string *in); static int drbg_init_sym_kernel(struct drbg_state *drbg); static int drbg_fini_sym_kernel(struct drbg_state *drbg); -static int drbg_kcapi_sym_ctr(struct drbg_state *drbg, u8 *outbuf, u32 outlen); +static int drbg_kcapi_sym_ctr(struct drbg_state *drbg, + u8 *inbuf, u32 inbuflen, + u8 *outbuf, u32 outlen); +#define DRBG_CTR_NULL_LEN 128 /* BCC function for CTR DRBG as defined in 10.4.3 */ static int drbg_ctr_bcc(struct drbg_state *drbg, @@ -481,8 +484,6 @@ static int drbg_ctr_update(struct drbg_state *drbg, struct list_head *seed, 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; if (3 > reseed) memset(df_data, 0, drbg_statelen(drbg)); @@ -510,18 +511,11 @@ static int drbg_ctr_update(struct drbg_state *drbg, struct list_head *seed, goto out; } - ret = drbg_kcapi_sym_ctr(drbg, temp, drbg_statelen(drbg)); + ret = drbg_kcapi_sym_ctr(drbg, df_data, drbg_statelen(drbg), + temp, drbg_statelen(drbg)); if (ret) return ret; - /* 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)); ret = crypto_skcipher_setkey(drbg->ctr_handle, drbg->C, @@ -561,7 +555,8 @@ static int drbg_ctr_generate(struct drbg_state *drbg, } /* 10.2.1.5.2 step 4.1 */ - ret = drbg_kcapi_sym_ctr(drbg, buf, len); + ret = drbg_kcapi_sym_ctr(drbg, drbg->ctr_null_value, DRBG_CTR_NULL_LEN, + buf, len); if (ret) return ret; @@ -1657,7 +1652,6 @@ static void drbg_skcipher_cb(struct crypto_async_request *req, int error) complete(&drbg->ctr_completion); } -#define DRBG_CTR_NULL_LEN 128 static int drbg_init_sym_kernel(struct drbg_state *drbg) { struct crypto_cipher *tfm; @@ -1733,14 +1727,16 @@ static int drbg_kcapi_sym(struct drbg_state *drbg, unsigned char *outval, return 0; } -static int drbg_kcapi_sym_ctr(struct drbg_state *drbg, u8 *outbuf, u32 outlen) +static int drbg_kcapi_sym_ctr(struct drbg_state *drbg, + u8 *inbuf, u32 inlen, + u8 *outbuf, u32 outlen) { struct scatterlist sg_in; - sg_init_one(&sg_in, drbg->ctr_null_value, DRBG_CTR_NULL_LEN); + sg_init_one(&sg_in, inbuf, inlen); while (outlen) { - u32 cryptlen = min_t(u32, outlen, DRBG_CTR_NULL_LEN); + u32 cryptlen = min_t(u32, inlen, outlen); struct scatterlist sg_out; int ret;