Re: [PATCH 009 of 9] knfsd: Allow sockets to be passed to nfsd via 'portlist'

Andrew Morton
2006-07-26T06:53:20Z

On Tue, 25 Jul 2006 11:55:08 +1000
NeilBrown <neilb@suse.de> wrote:

>
> Userspace should create and bind a socket (but not connectted)
> and write the 'fd' to portlist. This will cause the nfs server
> to listen on that socket.
>
> To close a socket, the name of the socket - as read from 'portlist'
> can be written to 'portlist' with a preceding '-'.
>

ick. Is that the best API we can come up with?

It's a privileged operation, but heck. Do we perform validation on the fd
to make sure that it's refers to a socket and not to /dev/fb0?

> static ssize_t write_ports(struct file *file, char *buf, size_t size)
> {
> - /* for now, ignore what was written and just
> - * return known ports
> - * AF proto address port
> + if (size == 0) {
> + int len = 0;
> + lock_kernel();
> + if (nfsd_serv)
> + len = svc_sock_names(buf, nfsd_serv, NULL);
> + unlock_kernel();
> + return len;
> + }
> + /* Either a single 'fd' number is written, in which
> + * case it must be for a socket of a supported family/protocol,
> + * and we use it as an nfsd socket, or
> + * A '-' followed by the 'name' of a socket in which case
> + * we close the socket.
> */
> - int len = 0;
> - lock_kernel();
> - if (nfsd_serv)
> - len = svc_sock_names(buf, nfsd_serv);
> - unlock_kernel();
> - return len;
> + if (isdigit(buf[0])) {
> + char *mesg = buf;
> + int fd;
> + int err;
> + err = get_int(&mesg, &fd);
> + if (err)
> + return -EINVAL;
> + if (fd < 0)
> + return -EINVAL;
> + err = nfsd_create_serv();
> + if (!err) {
> + int proto = 0;
> + err = svc_addsock(nfsd_serv, fd, buf, &proto);
> + /* Decrease the count, but don't shutdown the
> + * the service
> + */
> + if (err >= 0)
> + lockd_up(proto);
> + nfsd_serv->sv_nrthreads--;
> + }
> + return err;
> + }
> + if (buf[0] == '-') {
> + char *toclose = kstrdup(buf+1, GFP_KERNEL);
> + int len = 0;
> + if (!toclose)
> + return -ENOMEM;
> + lock_kernel();
> + if (nfsd_serv)
> + len = svc_sock_names(buf, nfsd_serv, toclose);
> + unlock_kernel();
> + kfree(toclose);
> + return len;
> + }
> + return -EINVAL;
> }

<checks>

OK, simple_transaction_get() guarantees that *buf is null-terminated. It
might be worth a comment to stop code-reviewers from freaking out ;)