crypto: rng - Mark crypto_rng_reset seed as const

There is no reason why crypto_rng_reset should modify the seed
so this patch marks it as const.  Since our algorithms don't
export a const seed function yet we have to go through some
contortions for now.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

2 files changed, 28 insertions, 8 deletions

diff --git a/crypto/rng.c b/crypto/rng.c
index 4514d3755f79..f1d64948f6fc 100644
--- a/crypto/rng.c
+++ b/crypto/rng.c
@@ -42,7 +42,29 @@ static int generate(struct crypto_rng *tfm, const u8 *src, unsigned int slen,
         return crypto_rng_alg(tfm)->rng_make_random(tfm, dst, dlen);
 }
 
-static int rngapi_reset(struct crypto_rng *tfm, u8 *seed, unsigned int slen)
+static int rngapi_reset(struct crypto_rng *tfm, const u8 *seed,
+                        unsigned int slen)
+{
+        u8 *buf = NULL;
+        u8 *src = (u8 *)seed;
+        int err;
+
+        if (slen) {
+                buf = kmalloc(slen, GFP_KERNEL);
+                if (!buf)
+                        return -ENOMEM;
+
+                memcpy(buf, seed, slen);
+                src = buf;
+        }
+
+        err = crypto_rng_alg(tfm)->rng_reset(tfm, src, slen);
+
+        kzfree(buf);
+        return err;
+}
+
+int crypto_rng_reset(struct crypto_rng *tfm, const u8 *seed, unsigned int slen)
 {
         u8 *buf = NULL;
         int err;
@@ -56,11 +78,12 @@ static int rngapi_reset(struct crypto_rng *tfm, u8 *seed, unsigned int slen)
                 seed = buf;
         }
 
-        err = crypto_rng_alg(tfm)->rng_reset(tfm, seed, slen);
+        err = tfm->seed(tfm, seed, slen);
 
         kfree(buf);
         return err;
 }
+EXPORT_SYMBOL_GPL(crypto_rng_reset);
 
 static int crypto_rng_init_tfm(struct crypto_tfm *tfm)
 {
diff --git a/include/crypto/rng.h b/include/crypto/rng.h
index f20f068154bc..7fca37144b59 100644
--- a/include/crypto/rng.h
+++ b/include/crypto/rng.h
@@ -19,7 +19,7 @@ struct crypto_rng {
         int (*generate)(struct crypto_rng *tfm,
                         const u8 *src, unsigned int slen,
                         u8 *dst, unsigned int dlen);
-        int (*seed)(struct crypto_rng *tfm, u8 *seed, unsigned int slen);
+        int (*seed)(struct crypto_rng *tfm, const u8 *seed, unsigned int slen);
         struct crypto_tfm base;
 };
 
@@ -139,11 +139,8 @@ static inline int crypto_rng_get_bytes(struct crypto_rng *tfm,
  *
  * Return: 0 if the setting of the key was successful; < 0 if an error occurred
  */
-static inline int crypto_rng_reset(struct crypto_rng *tfm,
-                                   u8 *seed, unsigned int slen)
-{
-        return tfm->seed(tfm, seed, slen);
-}
+int crypto_rng_reset(struct crypto_rng *tfm, const u8 *seed,
+                     unsigned int slen);
 
 /**
  * crypto_rng_seedsize() - obtain seed size of RNG