[PATCH 20/26] lib/digsig: Use SHA-1 library instead of crypto_shash

[Eric Biggers]

Use the SHA-1 library functions instead of crypto_shash.  This is
simpler and faster.

Signed-off-by: Eric Biggers <ebigg...@kernel.org>
---
 lib/Kconfig  |  3 +--
 lib/digsig.c | 46 ++++++----------------------------------------
 2 files changed, 7 insertions(+), 42 deletions(-)

diff --git a/lib/Kconfig b/lib/Kconfig
index 37db228f70a99..670c19800c26c 100644
--- a/lib/Kconfig
+++ b/lib/Kconfig
@@ -561,12 +561,11 @@ config MPILIB
          which is used by IMA/EVM digital signature extension.
 
 config SIGNATURE
        tristate
        depends on KEYS
-       select CRYPTO
-       select CRYPTO_SHA1
+       select CRYPTO_LIB_SHA1
        select MPILIB
        help
          Digital signature verification. Currently only RSA is supported.
          Implementation is done using GnuPG MPI library
 
diff --git a/lib/digsig.c b/lib/digsig.c
index 04b5e55ed95f5..5ddcc52f76863 100644
--- a/lib/digsig.c
+++ b/lib/digsig.c
@@ -16,19 +16,15 @@
 
 #include <linux/err.h>
 #include <linux/module.h>
 #include <linux/slab.h>
 #include <linux/key.h>
-#include <linux/crypto.h>
-#include <crypto/hash.h>
 #include <crypto/sha1.h>
 #include <keys/user-type.h>
 #include <linux/mpi.h>
 #include <linux/digsig.h>
 
-static struct crypto_shash *shash;
-
 static const char *pkcs_1_v1_5_decode_emsa(const unsigned char *msg,
                                                unsigned long  msglen,
                                                unsigned long  modulus_bitlen,
                                                unsigned long *outlen)
 {
@@ -197,16 +193,16 @@ static int digsig_verify_rsa(struct key *key,
  *
  */
 int digsig_verify(struct key *keyring, const char *sig, int siglen,
                                                const char *data, int datalen)
 {
-       int err = -ENOMEM;
        struct signature_hdr *sh = (struct signature_hdr *)sig;
-       struct shash_desc *desc = NULL;
+       struct sha1_ctx ctx;
        unsigned char hash[SHA1_DIGEST_SIZE];
        struct key *key;
        char name[20];
+       int err;
 
        if (siglen < sizeof(*sh) + 2)
                return -EINVAL;
 
        if (sh->algo != PUBKEY_ALGO_RSA)
@@ -229,51 +225,21 @@ int digsig_verify(struct key *keyring, const char *sig, 
int siglen,
        if (IS_ERR(key)) {
                pr_err("key not found, id: %s\n", name);
                return PTR_ERR(key);
        }
 
-       desc = kzalloc(sizeof(*desc) + crypto_shash_descsize(shash),
-                      GFP_KERNEL);
-       if (!desc)
-               goto err;
-
-       desc->tfm = shash;
-
-       crypto_shash_init(desc);
-       crypto_shash_update(desc, data, datalen);
-       crypto_shash_update(desc, sig, sizeof(*sh));
-       crypto_shash_final(desc, hash);
-
-       kfree(desc);
+       sha1_init(&ctx);
+       sha1_update(&ctx, data, datalen);
+       sha1_update(&ctx, sig, sizeof(*sh));
+       sha1_final(&ctx, hash);
 
        /* pass signature mpis address */
        err = digsig_verify_rsa(key, sig + sizeof(*sh), siglen - sizeof(*sh),
                             hash, sizeof(hash));
 
-err:
        key_put(key);
 
        return err ? -EINVAL : 0;
 }
 EXPORT_SYMBOL_GPL(digsig_verify);
 
-static int __init digsig_init(void)
-{
-       shash = crypto_alloc_shash("sha1", 0, 0);
-       if (IS_ERR(shash)) {
-               pr_err("shash allocation failed\n");
-               return  PTR_ERR(shash);
-       }
-
-       return 0;
-
-}
-
-static void __exit digsig_cleanup(void)
-{
-       crypto_free_shash(shash);
-}
-
-module_init(digsig_init);
-module_exit(digsig_cleanup);
-
 MODULE_LICENSE("GPL");
-- 
2.50.1