evm: add evm_inode_setattr to prevent updating an invalid security.evm

Permit changing of security.evm only when valid, unless in fixmode.

Reported-by: Roberto Sassu <roberto.sassu@polito.it>
Signed-off-by: Mimi Zohar <zohar@us.ibm.com>

1 files changed, 6 insertions, 0 deletions

diff --git a/include/linux/evm.h b/include/linux/evm.h
index 6d4e89b020c5..db5556dcdd27 100644
--- a/include/linux/evm.h
+++ b/include/linux/evm.h
@@ -19,6 +19,7 @@ extern enum integrity_status evm_verifyxattr(struct dentry *dentry,
                                              void *xattr_value,
                                              size_t xattr_value_len,
                                              struct integrity_iint_cache *iint);
+extern int evm_inode_setattr(struct dentry *dentry, struct iattr *attr);
 extern void evm_inode_post_setattr(struct dentry *dentry, int ia_valid);
 extern int evm_inode_setxattr(struct dentry *dentry, const char *name,
                               const void *value, size_t size);
@@ -44,6 +45,11 @@ static inline enum integrity_status evm_verifyxattr(struct dentry *dentry,
 }
 #endif
 
+static int evm_inode_setattr(struct dentry *dentry, struct iattr *attr)
+{
+        return 0;
+}
+
 static inline void evm_inode_post_setattr(struct dentry *dentry, int ia_valid)
 {
         return;