[PATCH 01/12] ima: use file_dentry()

[Miklos Szeredi]

Ima tries to call ->setxattr() on overlayfs dentry after having locked
underlying inode, which results in a deadlock.

Reported-by: Krisztian Litkey <kli@xxxxxx>
Fixes: 4bacc9c9234c ("overlayfs: Make f_path always point to the overlay and f_inode to the underlay")
Signed-off-by: Miklos Szeredi <mszeredi@xxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx> # v4.2
Cc: Mimi Zohar <zohar@xxxxxxxxxxxxxxxxxx>
---
 security/integrity/ima/ima_appraise.c | 4 ++--
 security/integrity/ima/ima_main.c     | 2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/security/integrity/ima/ima_appraise.c b/security/integrity/ima/ima_appraise.c
index 4b9b4a4e1b89..ef1e4e701780 100644
--- a/security/integrity/ima/ima_appraise.c
+++ b/security/integrity/ima/ima_appraise.c
@@ -190,7 +190,7 @@ int ima_appraise_measurement(enum ima_hooks func,
 {
 	static const char op[] = "appraise_data";
 	char *cause = "unknown";
-	struct dentry *dentry = file->f_path.dentry;
+	struct dentry *dentry = file_dentry(file);
 	struct inode *inode = d_backing_inode(dentry);
 	enum integrity_status status = INTEGRITY_UNKNOWN;
 	int rc = xattr_len, hash_start = 0;
@@ -295,7 +295,7 @@ out:
  */
 void ima_update_xattr(struct integrity_iint_cache *iint, struct file *file)
 {
-	struct dentry *dentry = file->f_path.dentry;
+	struct dentry *dentry = file_dentry(file);
 	int rc = 0;
 
 	/* do not collect and update hash for digital signatures */
diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
index 596ef616ac21..423d111b3b94 100644
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -228,7 +228,7 @@ static int process_measurement(struct file *file, char *buf, loff_t size,
 	if ((action & IMA_APPRAISE_SUBMASK) ||
 		    strcmp(template_desc->name, IMA_TEMPLATE_IMA_NAME) != 0)
 		/* read 'security.ima' */
-		xattr_len = ima_read_xattr(file->f_path.dentry, &xattr_value);
+		xattr_len = ima_read_xattr(file_dentry(file), &xattr_value);
 
 	hash_algo = ima_get_hash_algo(xattr_value, xattr_len);
 
-- 
2.5.5