ima: define ima_post_create_tmpfile() hook and add missing call

If tmpfiles can be made persistent, then newly created tmpfiles need to
be treated like any other new files in policy.

This patch indicates which newly created tmpfiles are in policy, causing
the file hash to be calculated on __fput().

Reported-by: Ignaz Forster <ignaz.forster@gmx.de>
[rgoldwyn@suse.com: Call ima_post_create_tmpfile() in vfs_tmpfile() as
opposed to do_tmpfile(). This will help the case for overlayfs where
copy_up is denied while overwriting a file.]
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>

1 files changed, 33 insertions, 2 deletions

diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
index 4ffac4f5c647..357edd140c09 100644
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -397,6 +397,33 @@ int ima_file_check(struct file *file, int mask)
 EXPORT_SYMBOL_GPL(ima_file_check);
 
 /**
+ * ima_post_create_tmpfile - mark newly created tmpfile as new
+ * @file : newly created tmpfile
+ *
+ * No measuring, appraising or auditing of newly created tmpfiles is needed.
+ * Skip calling process_measurement(), but indicate which newly, created
+ * tmpfiles are in policy.
+ */
+void ima_post_create_tmpfile(struct inode *inode)
+{
+	struct integrity_iint_cache *iint;
+	int must_appraise;
+
+	must_appraise = ima_must_appraise(inode, MAY_ACCESS, FILE_CHECK);
+	if (!must_appraise)
+		return;
+
+	/* Nothing to do if we can't allocate memory */
+	iint = integrity_inode_get(inode);
+	if (!iint)
+		return;
+
+	/* needed for writing the security xattrs */
+	set_bit(IMA_UPDATE_XATTR, &iint->atomic_flags);
+	iint->ima_file_status = INTEGRITY_PASS;
+}
+
+/**
  * ima_post_path_mknod - mark as a new inode
  * @dentry: newly created dentry
  *
@@ -413,9 +440,13 @@ void ima_post_path_mknod(struct dentry *dentry)
 	if (!must_appraise)
 		return;
 
+	/* Nothing to do if we can't allocate memory */
 	iint = integrity_inode_get(inode);
-	if (iint)
-		iint->flags |= IMA_NEW_FILE;
+	if (!iint)
+		return;
+
+	/* needed for re-opening empty files */
+	iint->flags |= IMA_NEW_FILE;
 }
 
 /**