On Tue, Jun 20, 2017 at 12:41:47PM -0300, Marcelo Ricardo Leitner wrote: > Hi, > > On Tue, Jun 20, 2017 at 10:39:51AM -0400, Neil Horman wrote: > > On Tue, Jun 20, 2017 at 03:24:13PM +0200, Andreas Steinmetz wrote: > > > [please CC me, I'm not subscribed] > > > > > > It seems that if one does a getsockopt(SCTP_SOCKOPT_PEELOFF) a.k.a. > > > sctp_peeloff(), even if the socket descriptor from which the > > > association is to be peeled off has SOCK_CLOEXEC/SOCK_NONBLOCK set, > > > the peeled off socket descriptor doesn't have so. > > > > > > It would be advisable to either clone these flags or add an atomic > > > version of SCTP_SOCKOPT_PEELOFF (accept4() style). > > > > > > The missing SOCK_CLOEXEC requires unintentional additional locking > > > which typically is prone to errors and can slow down processing. > > > -- > > > Andreas Steinmetz SPAMmers use robotrap@xxxxxxxx > > > -- > > > To unsubscribe from this list: send the line "unsubscribe linux-sctp" in > > > the body of a message to majordomo@xxxxxxxxxxxxxxx > > > More majordomo info at http://vger.kernel.org/majordomo-info.html > > > > > > > > > Try this patch, and confirm that it fixes the problem please? > > > > Thanks! > > Neil > > > > > > diff --git a/net/sctp/socket.c b/net/sctp/socket.c > > index f16c8d9..a95e3d6 100644 > > --- a/net/sctp/socket.c > > +++ b/net/sctp/socket.c > > @@ -4912,7 +4912,7 @@ int sctp_do_peeloff(struct sock *sk, sctp_assoc_t id, struct socket **sockp) > > return -EINVAL; > > > > /* Create a new socket. */ > > - err = sock_create(sk->sk_family, SOCK_SEQPACKET, IPPROTO_SCTP, &sock); > > + err = sock_create(sk->sk_family, sk->sk_type, IPPROTO_SCTP, &sock); > > I don't think this will work. Syscall socket() filters out these > flags and handle them separetly after calling sock_create() with just > the type, so I don't think this information is preserved in there. > Shoot, you're right, they get masked as assigned to the fdflags, and aren't preserved in the socket flags. We would have to find another way to go. > Interesting to note that according to man page dup() syscall also > doesn't duplicate these flags. One has to use dup3() instead in order to > be able to specify them. > Yeah. Actually in the case of dup3, it won't even let you specify O_CLOEXEC at all, it returns an error if its set in the flags field. > 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) > I wonder if theres something in the sock_map_fd function set that might let us clone an fd with all its flags to a new socket? Neil > Thanks, > Marcelo > > ---8<--- > > diff --git a/net/sctp/socket.c b/net/sctp/socket.c > index e1fabf67d4ad..50021a925b16 100644 > --- a/net/sctp/socket.c > +++ b/net/sctp/socket.c > @@ -4950,8 +4950,10 @@ static int sctp_getsockopt_peeloff(struct sock *sk, int len, char __user *optval > if (retval < 0) > goto out; > > - /* Map the socket to an unused fd that can be returned to the user. */ > - retval = get_unused_fd_flags(0); > + /* Map the socket to an unused fd that can be returned to the user. > + * peeloff.sd[in] is used to transport flags > + */ > + retval = get_unused_fd_flags(peeloff.sd); > if (retval < 0) { > sock_release(newsock); > goto out; > -- > To unsubscribe from this list: send the line "unsubscribe linux-sctp" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- To unsubscribe from this list: send the line "unsubscribe linux-sctp" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
