ima: provide dedicated hash algo allocation function

This patch provides dedicated hash algo allocation and
deallocation function which can be used by different clients.

Signed-off-by: Dmitry Kasatkin <d.kasatkin@samsung.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>

1 files changed, 29 insertions, 14 deletions

diff --git a/security/integrity/ima/ima_crypto.c b/security/integrity/ima/ima_crypto.c
index 872c6698067c..e5d3ebf18436 100644
--- a/security/integrity/ima/ima_crypto.c
+++ b/security/integrity/ima/ima_crypto.c
@@ -39,6 +39,28 @@ int ima_init_crypto(void)
         return 0;
 }
 
+static struct crypto_shash *ima_alloc_tfm(enum hash_algo algo)
+{
+        struct crypto_shash *tfm = ima_shash_tfm;
+        int rc;
+
+        if (algo != ima_hash_algo && algo < HASH_ALGO__LAST) {
+                tfm = crypto_alloc_shash(hash_algo_name[algo], 0, 0);
+                if (IS_ERR(tfm)) {
+                        rc = PTR_ERR(tfm);
+                        pr_err("Can not allocate %s (reason: %d)\n",
+                               hash_algo_name[algo], rc);
+                }
+        }
+        return tfm;
+}
+
+static void ima_free_tfm(struct crypto_shash *tfm)
+{
+        if (tfm != ima_shash_tfm)
+                crypto_free_shash(tfm);
+}
+
 /*
  * Calculate the MD5/SHA1 file digest
  */
@@ -57,6 +79,8 @@ static int ima_calc_file_hash_tfm(struct file *file,
         desc.shash.tfm = tfm;
         desc.shash.flags = 0;
 
+        hash->length = crypto_shash_digestsize(tfm);
+
         rc = crypto_shash_init(&desc.shash);
         if (rc != 0)
                 return rc;
@@ -98,25 +122,16 @@ out:
 
 int ima_calc_file_hash(struct file *file, struct ima_digest_data *hash)
 {
-        struct crypto_shash *tfm = ima_shash_tfm;
+        struct crypto_shash *tfm;
         int rc;
 
-        if (hash->algo != ima_hash_algo && hash->algo < HASH_ALGO__LAST) {
-                tfm = crypto_alloc_shash(hash_algo_name[hash->algo], 0, 0);
-                if (IS_ERR(tfm)) {
-                        rc = PTR_ERR(tfm);
-                        pr_err("Can not allocate %s (reason: %d)\n",
-                               hash_algo_name[hash->algo], rc);
-                        return rc;
-                }
-        }
-
-        hash->length = crypto_shash_digestsize(tfm);
+        tfm = ima_alloc_tfm(hash->algo);
+        if (IS_ERR(tfm))
+                return PTR_ERR(tfm);
 
         rc = ima_calc_file_hash_tfm(file, hash, tfm);
 
-        if (tfm != ima_shash_tfm)
-                crypto_free_shash(tfm);
+        ima_free_tfm(tfm);
 
         return rc;
 }