From: "Theodore Ts'o" <tytso@mit.edu>
To: Chao Yu <chao@kernel.org>
Cc: jaegeuk@kernel.org, linux-f2fs-devel@lists.sourceforge.net,
linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org,
Chao Yu <yuchao0@huawei.com>
Subject: Re: [PATCH] fscrypto: fix to null-terminate encrypted filename in fname_encrypt
Date: Sun, 28 Aug 2016 01:13:30 -0400 [thread overview]
Message-ID: <20160828051330.7kyhhvvxitghshi7@thunk.org> (raw)
In-Reply-To: <1472346808-3213-1-git-send-email-chao@kernel.org>
On Sun, Aug 28, 2016 at 09:13:28AM +0800, Chao Yu wrote:
> From: Chao Yu <yuchao0@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
next prev parent reply other threads:[~2016-08-28 5:44 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-08-28 1:13 [PATCH] fscrypto: fix to null-terminate encrypted filename in fname_encrypt Chao Yu
2016-08-28 5:13 ` Theodore Ts'o [this message]
2016-08-28 6:16 ` Chao Yu
2016-08-29 14:55 ` [f2fs-dev] " Chao Yu
2016-08-29 17:51 ` Jaegeuk Kim
2016-08-29 19:08 ` Theodore Ts'o
2016-08-30 16:10 ` Chao Yu
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