ima: use file_dentry()

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

Reported-by: Krisztian Litkey <kli@iki.fi>
Fixes: 4bacc9c9234c ("overlayfs: Make f_path always point to the overlay and f_inode to the underlay")
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Cc: <stable@vger.kernel.org> # v4.2
Cc: Mimi Zohar <zohar@linux.vnet.ibm.com>

diff --git a/security/integrity/ima/ima_appraise.c b/security/integrity/ima/ima_appraise.c
index 4b9b4a4..ef1e4e7 100644 (file)
--- 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 596ef61..423d111 100644 (file)
--- 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);