fscrypt: constify struct fscrypt_hkdf parameter to fscrypt_hkdf_expand()

Constify the struct fscrypt_hkdf parameter to fscrypt_hkdf_expand().
This makes it clearer that struct fscrypt_hkdf contains the key only,
not any per-request state.

Link: https://lore.kernel.org/r/20191209204054.227736-1-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>

diff --git a/fs/crypto/fscrypt_private.h b/fs/crypto/fscrypt_private.h
index 130b50e5a0115d9959e2cef9d606027fb48e79d5..23cef4d3793a5b1d967afd4c455176350627e72b 100644 (file)
--- a/fs/crypto/fscrypt_private.h
+++ b/fs/crypto/fscrypt_private.h
@@ -287,7 +287,7 @@ extern int fscrypt_init_hkdf(struct fscrypt_hkdf *hkdf, const u8 *master_key,
 #define HKDF_CONTEXT_DIRECT_KEY                3
 #define HKDF_CONTEXT_IV_INO_LBLK_64_KEY        4
 
-extern int fscrypt_hkdf_expand(struct fscrypt_hkdf *hkdf, u8 context,
+extern int fscrypt_hkdf_expand(const struct fscrypt_hkdf *hkdf, u8 context,
                               const u8 *info, unsigned int infolen,
                               u8 *okm, unsigned int okmlen);
 

diff --git a/fs/crypto/hkdf.c b/fs/crypto/hkdf.c
index f21873e1b46749547cd32808f29b26ad6212b036..efb95bd19a8948f1fd7042a5f4a2e9ba2a967c2d 100644 (file)
--- a/fs/crypto/hkdf.c
+++ b/fs/crypto/hkdf.c
@@ -112,7 +112,7 @@ out:
  * adds to its application-specific info strings to guarantee that it doesn't
  * accidentally repeat an info string when using HKDF for different purposes.)
  */
-int fscrypt_hkdf_expand(struct fscrypt_hkdf *hkdf, u8 context,
+int fscrypt_hkdf_expand(const struct fscrypt_hkdf *hkdf, u8 context,
                        const u8 *info, unsigned int infolen,
                        u8 *okm, unsigned int okmlen)
 {