Hello, On Fri, Dec 25, 2009 at 05:09:40PM +0800, Da Zheng wrote: > > Sergiu Ivanov wrote: > > - master_device = file_name_lookup (arg, 0, 0); > > + master_device = file_name_lookup (arg, O_READ | O_WRITE, 0); > > What happens if .MASTER file is read-only? Certainly, > file_name_lookup in devnode fails. But the questions is: can .MASTER > node be read-only?
That's a good point. Consider the following situation: user A sets up eth-multiplexer on ~A/veth/ and allows only themselves to write into ~A/veth/ . If user B tries to use ~A/veth/.MASTER via a devnode, B will get a ``Permission denied'' error. (I've just checked it: A was root and B was me). The question is, however, how critical this restriction is. If, for example, root sets up a multiplexer for public use, they may also allow read-write access to its virtual devices. (I've just allowed 777 access to ~root/veth and my normal user could setup devnode instances working with .MASTER.) Also, I wonder whether read-only network devices make sense. (Here I may be lacking information, which makes me have such an opinion.) Regards, Sergiu
