On Sun, Aug 28, 2016 at 09:13:28AM +0800, Chao Yu wrote:
> From: Chao Yu <yuch...@huawei.com>
>
> This patch fixes to add null character at the end of encrypted filename
> in fname_encrypt, in order to avoid incorrectly traversing random data
> located after target filename. The call stack is as below:
>
> - f2fs_add_link
> - __f2fs_add_link
> - fscrypt_setup_filename
> - fscrypt_fname_alloc_buffer allocate buffer for @fname
> - fname_encrypt didn't set null character for @fname
> - f2fs_add_regular_entry init qstr with @fname
> - init_inode_metadata
> - f2fs_init_security
> - security_inode_init_security
> - selinux_inode_init_security
> - selinux_determine_inode_label
> - security_transition_sid
> - security_compute_sid
> - filename_compute_type
> - hashtab_search
> - filenametr_hash traverse @fname as one which has null
> character
The problem is not in fname_encrypt(), but rather that
security_inode_init_security() should be given the _unencrypted_
filename.
In ext4 security_inode_init_security() is called with the qstr from
the dentry, not the encrypted qstr --- in fact we call
security_inode_init_security before we call fname_encrypt.
SELinux needs the unencrypted filename in order to decide which
SELinux rules / labels should apply.
- Ted
