crypto: drbg - use crypto_inc

The DRBG internal buffer addition function is replaced with crypto_inc when
a buffer is to be incremented by one.

The function drbg_add_buf is moved to the CONFIG_CRYPTO_DRBG_HASH ifdef
area as it is now only needed for the Hash DRBG.

Signed-off-by: Stephan Mueller <smueller@chronox.de>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

1 files changed, 38 insertions, 41 deletions

diff --git a/crypto/drbg.c b/crypto/drbg.c
index 54cfd4820abc..8c0a742b60f6 100644
--- a/crypto/drbg.c
+++ b/crypto/drbg.c
@@ -283,38 +283,6 @@ static inline void drbg_cpu_to_be32(__u32 val, unsigned char *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) */
 
 /******************************************************************
@@ -554,7 +522,6 @@ static int drbg_ctr_update(struct drbg_state *drbg, struct list_head *seed,
         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)
@@ -574,7 +541,7 @@ static int drbg_ctr_update(struct drbg_state *drbg, struct list_head *seed,
          */
         while (len < (drbg_statelen(drbg))) {
                 /* 10.2.1.2 step 2.1 */
-                drbg_add_buf(drbg->V, drbg_blocklen(drbg), &prefix, 1);
+                crypto_inc(drbg->V, drbg_blocklen(drbg));
                 /*
                  * 10.2.1.2 step 2.2 */
                 ret = drbg_kcapi_sym(drbg, drbg->C, temp + len, &cipherin);
@@ -617,7 +584,6 @@ static int drbg_ctr_generate(struct drbg_state *drbg,
         int len = 0;
         int ret = 0;
         struct drbg_string data;
-        unsigned char prefix = DRBG_PREFIX1;
 
         memset(drbg->scratchpad, 0, drbg_blocklen(drbg));
 
@@ -629,7 +595,7 @@ static int drbg_ctr_generate(struct drbg_state *drbg,
         }
 
         /* 10.2.1.5.2 step 4.1 */
-        drbg_add_buf(drbg->V, drbg_blocklen(drbg), &prefix, 1);
+        crypto_inc(drbg->V, drbg_blocklen(drbg));
         drbg_string_fill(&data, drbg->V, drbg_blocklen(drbg));
         while (len < buflen) {
                 int outlen = 0;
@@ -643,7 +609,7 @@ static int drbg_ctr_generate(struct drbg_state *drbg,
                           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);
+                        crypto_inc(drbg->V, drbg_blocklen(drbg));
                         continue;
                 }
                 /* 10.2.1.5.2 step 4.3 */
@@ -651,7 +617,7 @@ static int drbg_ctr_generate(struct drbg_state *drbg,
                 len += outlen;
                 /* 10.2.1.5.2 step 6 */
                 if (len < buflen)
-                        drbg_add_buf(drbg->V, drbg_blocklen(drbg), &prefix, 1);
+                        crypto_inc(drbg->V, drbg_blocklen(drbg));
         }
 
         /* 10.2.1.5.2 step 6 */
@@ -797,6 +763,38 @@ static struct drbg_state_ops drbg_hmac_ops = {
 #ifdef CONFIG_CRYPTO_DRBG_HASH
 #define CRYPTO_DRBG_HASH_STRING "HASH "
 /*
+ * Increment buffer
+ *
+ * @dst buffer to increment
+ * @add value to add
+ */
+static inline void drbg_add_buf(unsigned char *dst, size_t dstlen,
+                                const unsigned char *add, size_t addlen)
+{
+        /* implied: dstlen > addlen */
+        unsigned char *dstptr;
+        const unsigned char *addptr;
+        unsigned int remainder = 0;
+        size_t len = addlen;
+
+        dstptr = dst + (dstlen-1);
+        addptr = add + (addlen-1);
+        while (len) {
+                remainder += *dstptr + *addptr;
+                *dstptr = remainder & 0xff;
+                remainder >>= 8;
+                len--; dstptr--; addptr--;
+        }
+        len = dstlen - addlen;
+        while (len && remainder > 0) {
+                remainder = *dstptr + 1;
+                *dstptr = remainder & 0xff;
+                remainder >>= 8;
+                len--; dstptr--;
+        }
+}
+
+/*
  * scratchpad usage: as drbg_hash_update and drbg_hash_df are used
  * interlinked, the scratchpad is used as follows:
  * drbg_hash_update
@@ -942,7 +940,6 @@ static int drbg_hash_hashgen(struct drbg_state *drbg,
         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));
@@ -963,7 +960,7 @@ static int drbg_hash_hashgen(struct drbg_state *drbg,
                 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);
+                        crypto_inc(src, drbg_statelen(drbg));
                         continue;
                 }
                 /* 10.1.1.4 step hashgen 4.2 */
@@ -971,7 +968,7 @@ static int drbg_hash_hashgen(struct drbg_state *drbg,
                 len += outlen;
                 /* 10.1.1.4 hashgen step 4.3 */
                 if (len < buflen)
-                        drbg_add_buf(src, drbg_statelen(drbg), &prefix, 1);
+                        crypto_inc(src, drbg_statelen(drbg));
         }
 
 out: