On 3/8/2017 20:08, Chao Yu wrote:
> In commit d9cdc9033181 ("ext4 crypto: enforce context consistency") we
> declared that:
>
> 2) All files or directories in a directory must be protected using the
> same key as their containing directory.
>
> But in f2fs_cross_rename there is a vulnerability that allow to cross
> rename unencrypted file into encrypted directory, it needs to be refused.
fscrypt_has_permitted_context has do the checking as this patch,
168 /* no restrictions if the parent directory is not encrypted */
169 if (!parent->i_sb->s_cop->is_encrypted(parent))
170 return 1;
171 /* if the child directory is not encrypted, this is always a
problem */
172 if (!parent->i_sb->s_cop->is_encrypted(child))
173 return 0;
So, the cross rename unencrypted file into encrypted directory is permitted
right now.
I have a encrypted directory "ncry", "new" is unencrypted file.
[root@nfstestnic f2fs]# renameat2 -x encry/hello new
Operation not permitted
[root@nfstestnic f2fs]# renameat2 -x encry/hello new
Operation not permitted
How do you test it?
thanks,
Kinglong Mee
>
> Signed-off-by: Chao Yu <[email protected]>
> ---
> fs/f2fs/namei.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/fs/f2fs/namei.c b/fs/f2fs/namei.c
> index 25c073f6c7d4..8de684b84cb9 100644
> --- a/fs/f2fs/namei.c
> +++ b/fs/f2fs/namei.c
> @@ -855,6 +855,10 @@ static int f2fs_cross_rename(struct inode *old_dir,
> struct dentry *old_dentry,
> !fscrypt_has_encryption_key(new_dir)))
> return -ENOKEY;
>
> + if (f2fs_encrypted_inode(old_dir) && !f2fs_encrypted_inode(new_inode) ||
> + f2fs_encrypted_inode(new_dir) &&
> !f2fs_encrypted_inode(old_inode))
> + return -EPERM;
> +
> if ((f2fs_encrypted_inode(old_dir) || f2fs_encrypted_inode(new_dir)) &&
> (old_dir != new_dir) &&
> (!fscrypt_has_permitted_context(new_dir, old_inode) ||
>
