On Tue, Jun 20, 2017 at 03:00:46PM -0400, Neil Horman wrote:
> On Tue, Jun 20, 2017 at 12:41:47PM -0300, Marcelo Ricardo Leitner wrote:
...
> > Maybe by extending sctp_peeloff_arg_t to have a flags attribute in
> > there, we can allow the application to specify it and feed into
> > get_unused_fd_flags() call in sctp_getsockopt_peeloff() instead, or even
> > just overload the sd, which is currently an output-only value, to
> > contain flags as the patch below. (We probably should add some sanity
> > checking in there, though)
> >
> Thinking about this some more, I'm a bit hesitant to change the
> sctp_peeloff_arg_t, since thats exposed to user space. Instead, what if we use
+1
> the sd value in the peeloff arg to fetch the close_on_exec flag in the new fd?
> Something like this (untested) patch:
Yes. :-) That's similar to what I proposed, though you used peeloff.sd
to find the old fd and copy the flag from it and I used it as a pure
'flags' field instead.
I'm still not comfortable on hardwiring this copy. What if the
application doesn't want to inherit the flag?
accept() calls accept4(... , flags=0)
dup2() calls dup3(... , flags=0)
I don't see this direct inheritance anywhere else.
Marcelo
>
>
> diff --git a/net/sctp/socket.c b/net/sctp/socket.c
> index f16c8d9..6386ac4 100644
> --- a/net/sctp/socket.c
> +++ b/net/sctp/socket.c
> @@ -4939,6 +4939,8 @@ static int sctp_getsockopt_peeloff(struct sock *sk, int len, char __user *optval
> sctp_peeloff_arg_t peeloff;
> struct socket *newsock;
> struct file *newfile;
> + struct file *oldfile
> + unsigned flags = 0;
> int retval = 0;
>
> if (len < sizeof(sctp_peeloff_arg_t))
> @@ -4951,8 +4953,17 @@ static int sctp_getsockopt_peeloff(struct sock *sk, int len, char __user *optval
> if (retval < 0)
> goto out;
>
> + if (get_close_on_exec(peeloff.sd))
> + flags |= O_CLOEXEC;
> +
> + oldfile = fget(peelof.sd);
> + if (oldfile) {
> + flags |= oldfile->f_flags & O_NONBLOCK;
> + fput(oldfile);
> + }
> +
> /* Map the socket to an unused fd that can be returned to the user. */
> - retval = get_unused_fd_flags(0);
> + retval = get_unused_fd_flags(flags);
> if (retval < 0) {
> sock_release(newsock);
> goto out;
> --
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