ima: read and use signature hash algorithm

All files on the filesystem, currently, are hashed using the same hash
algorithm.  In preparation for files from different packages being
signed using different hash algorithms, this patch adds support for
reading the signature hash algorithm from the 'security.ima' extended
attribute and calculates the appropriate file data hash based on it.

Changelog:
- fix scripts Lindent and checkpatch msgs - Mimi
- fix md5 support for older version, which occupied 20 bytes in the
  xattr, not the expected 16 bytes.  Fix the comparison to compare
  only the first 16 bytes.

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

1 files changed, 26 insertions, 3 deletions

diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
index eb86032..efcdef2 100644
--- a/security/integrity/ima/ima.h
+++ b/security/integrity/ima/ima.h
@@ -99,7 +99,9 @@ static inline unsigned long ima_hash_key(u8 *digest)
 int ima_get_action(struct inode *inode, int mask, int function);
 int ima_must_measure(struct inode *inode, int mask, int function);
 int ima_collect_measurement(struct integrity_iint_cache *iint,
-			    struct file *file);
+			    struct file *file,
+			    struct evm_ima_xattr_data **xattr_value,
+			    int *xattr_len);
 void ima_store_measurement(struct integrity_iint_cache *iint, struct file *file,
 			   const unsigned char *filename);
 void ima_audit_measurement(struct integrity_iint_cache *iint,
@@ -132,17 +134,25 @@ void ima_delete_rules(void);
 
 #ifdef CONFIG_IMA_APPRAISE
 int ima_appraise_measurement(int func, struct integrity_iint_cache *iint,
-			     struct file *file, const unsigned char *filename);
+			     struct file *file, const unsigned char *filename,
+			     struct evm_ima_xattr_data *xattr_value,
+			     int xattr_len);
 int ima_must_appraise(struct inode *inode, int mask, enum ima_hooks func);
 void ima_update_xattr(struct integrity_iint_cache *iint, struct file *file);
 enum integrity_status ima_get_cache_status(struct integrity_iint_cache *iint,
 					   int func);
+void ima_get_hash_algo(struct evm_ima_xattr_data *xattr_value, int xattr_len,
+		       struct ima_digest_data *hash);
+int ima_read_xattr(struct dentry *dentry,
+		   struct evm_ima_xattr_data **xattr_value);
 
 #else
 static inline int ima_appraise_measurement(int func,
 					   struct integrity_iint_cache *iint,
 					   struct file *file,
-					   const unsigned char *filename)
+					   const unsigned char *filename,
+					   struct evm_ima_xattr_data *xattr_value,
+					   int xattr_len)
 {
 	return INTEGRITY_UNKNOWN;
 }
@@ -163,6 +173,19 @@ static inline enum integrity_status ima_get_cache_status(struct integrity_iint_c
 {
 	return INTEGRITY_UNKNOWN;
 }
+
+static inline void ima_get_hash_algo(struct evm_ima_xattr_data *xattr_value,
+				     int xattr_len,
+				     struct ima_digest_data *hash)
+{
+}
+
+static inline int ima_read_xattr(struct dentry *dentry,
+				 struct evm_ima_xattr_data **xattr_value)
+{
+	return 0;
+}
+
 #endif
 
 /* LSM based policy rules require audit */