From: Chao Yu <chao@kernel.org>
To: "Theodore Ts'o" <tytso@mit.edu>,
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 14:16:03 +0800 [thread overview]
Message-ID: <4a1a7233-a8f5-873a-2895-a259dc0cf717@kernel.org> (raw)
In-Reply-To: <20160828051330.7kyhhvvxitghshi7@thunk.org>
Hi Ted,
On 2016/8/28 13:13, Theodore Ts'o wrote:
> 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.
You're right, I missed this mistake. So actually, this is a bug of f2fs.
Let me figure out the fixing patch.
Thanks for your review! :)
Thanks,
>
> - Ted
>
next prev parent reply other threads:[~2016-08-28 6:16 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
2016-08-28 6:16 ` Chao Yu [this message]
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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