ima: fix hash algorithm initialization

BugLink: http://bugs.launchpad.net/bugs/1745046

[ Upstream commit ebe7c0a7 ]

The hash_setup function always sets the hash_setup_done flag, even
when the hash algorithm is invalid.  This prevents the default hash
algorithm defined as CONFIG_IMA_DEFAULT_HASH from being used.

This patch sets hash_setup_done flag only for valid hash algorithms.

Fixes: e7a2ad7e "ima: enable support for larger default filedata hash algorithms"
Signed-off-by: Boshi Wang <wangboshi@huawei.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

security/integrity/ima/ima_main.c

@@ -52,6 +52,8 @@ static int __init hash_setup(char *str)
 			ima_hash_algo = HASH_ALGO_SHA1;
 		else if (strncmp(str, "md5", 3) == 0)
 			ima_hash_algo = HASH_ALGO_MD5;
+		else
+			return 1;
 		goto out;
 	}
 
@@ -61,6 +63,8 @@ static int __init hash_setup(char *str)
 			break;
 		}
 	}
+	if (i == HASH_ALGO__LAST)
+		return 1;
 out:
 	hash_setup_done = 1;
 	return 1;