CRED: Pass credentials through dentry_open()

Pass credentials through dentry_open() so that the COW creds patch can have
SELinux's flush_unauthorized_files() pass the appropriate creds back to itself
when it opens its null chardev.

The security_dentry_open() call also now takes a creds pointer, as does the
dentry_open hook in struct security_operations.

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: James Morris <jmorris@namei.org>
Signed-off-by: James Morris <jmorris@namei.org>

1 files changed, 11 insertions, 6 deletions

diff --git a/fs/open.c b/fs/open.c
index b1238e195e7e..f96eaab280a3 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -783,7 +783,8 @@ static inline int __get_file_write_access(struct inode *inode,
 
 static struct file *__dentry_open(struct dentry *dentry, struct vfsmount *mnt,
                                         int flags, struct file *f,
-                                        int (*open)(struct inode *, struct file *))
+                                        int (*open)(struct inode *, struct file *),
+                                        const struct cred *cred)
 {
         struct inode *inode;
         int error;
@@ -807,7 +808,7 @@ static struct file *__dentry_open(struct dentry *dentry, struct vfsmount *mnt,
         f->f_op = fops_get(inode->i_fop);
         file_move(f, &inode->i_sb->s_files);
 
-        error = security_dentry_open(f);
+        error = security_dentry_open(f, cred);
         if (error)
                 goto cleanup_all;
 
@@ -882,6 +883,8 @@ cleanup_file:
 struct file *lookup_instantiate_filp(struct nameidata *nd, struct dentry *dentry,
                 int (*open)(struct inode *, struct file *))
 {
+        const struct cred *cred = current_cred();
+
         if (IS_ERR(nd->intent.open.file))
                 goto out;
         if (IS_ERR(dentry))
@@ -889,7 +892,7 @@ struct file *lookup_instantiate_filp(struct nameidata *nd, struct dentry *dentry
         nd->intent.open.file = __dentry_open(dget(dentry), mntget(nd->path.mnt),
                                              nd->intent.open.flags - 1,
                                              nd->intent.open.file,
-                                             open);
+                                             open, cred);
 out:
         return nd->intent.open.file;
 out_err:
@@ -908,6 +911,7 @@ EXPORT_SYMBOL_GPL(lookup_instantiate_filp);
  */
 struct file *nameidata_to_filp(struct nameidata *nd, int flags)
 {
+        const struct cred *cred = current_cred();
         struct file *filp;
 
         /* Pick up the filp from the open intent */
@@ -915,7 +919,7 @@ struct file *nameidata_to_filp(struct nameidata *nd, int flags)
         /* Has the filesystem initialised the file for us? */
         if (filp->f_path.dentry == NULL)
                 filp = __dentry_open(nd->path.dentry, nd->path.mnt, flags, filp,
-                                     NULL);
+                                     NULL, cred);
         else
                 path_put(&nd->path);
         return filp;
@@ -925,7 +929,8 @@ struct file *nameidata_to_filp(struct nameidata *nd, int flags)
  * dentry_open() will have done dput(dentry) and mntput(mnt) if it returns an
  * error.
  */
-struct file *dentry_open(struct dentry *dentry, struct vfsmount *mnt, int flags)
+struct file *dentry_open(struct dentry *dentry, struct vfsmount *mnt, int flags,
+                         const struct cred *cred)
 {
         int error;
         struct file *f;
@@ -950,7 +955,7 @@ struct file *dentry_open(struct dentry *dentry, struct vfsmount *mnt, int flags)
                 return ERR_PTR(error);
         }
 
-        return __dentry_open(dentry, mnt, flags, f, NULL);
+        return __dentry_open(dentry, mnt, flags, f, NULL, cred);
 }
 EXPORT_SYMBOL(dentry_open);