On Wed, Sep 14, 2011 at 18:48 +0400, Vasiliy Kulikov wrote:
> > So, there is no *new* hole.
>
> Actually now I see the difference between having something mapped and
> having an _fd_ of this something.
>
> Relevant code:
>
> +static struct dentry *
> +proc_map_files_instantiate(struct inode *dir, struct dentry *dentry,
> + struct task_struct *task, const void *ptr)
> +{
> ...
> + inode->i_mode = S_IFLNK;
> +
> + if (file->f_mode & FMODE_READ)
> + inode->i_mode |= S_IRUSR | S_IXUSR;
> + if (file->f_mode & FMODE_WRITE)
> + inode->i_mode |= S_IWUSR | S_IXUSR;
>
>
> If you have a write mmap area, but no fd, you may not trunc a file; with
> map_files/ you may get an fd and ftrunc it.
Also it unconditionally adds +x, but I don't think it breaks any
security assumption as (1) there is no +s and (2) fd is not a directory.
Thanks,
--
Vasiliy Kulikov
http://www.openwall.com - bringing security into open computing environments
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