[PATCH 4.8 35/37] ima: use file_dentry()

From: Greg Kroah-Hartman
Date: Fri Oct 14 2016 - 08:33:19 EST


4.8-stable review patch. If anyone has any objections, please let me know.

------------------

From: Miklos Szeredi <mszeredi@xxxxxxxxxx>

commit e71b9dff0634edb127f449e076e883ef24a8c76c upstream.

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: Mimi Zohar <zohar@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
security/integrity/ima/ima_appraise.c | 4 ++--
security/integrity/ima/ima_main.c | 2 +-
2 files changed, 3 insertions(+), 3 deletions(-)

--- a/security/integrity/ima/ima_appraise.c
+++ b/security/integrity/ima/ima_appraise.c
@@ -190,7 +190,7 @@ int ima_appraise_measurement(enum ima_ho
{
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 */
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -228,7 +228,7 @@ static int process_measurement(struct fi
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);