[SCTP] Do not allow unprivileged programs initiating new associations on

privileged ports.

Signed-off-by: Ivan Skytte Jorgensen <isj-sctp@i1.dk>
Signed-off-by: Sridhar Samudrala <sri@us.ibm.com>

1 files changed, 26 insertions, 0 deletions

diff --git a/net/sctp/socket.c b/net/sctp/socket.c
index 97b556c1c450..b529af5e6f2a 100644
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -1010,6 +1010,19 @@ static int __sctp_connect(struct sock* sk,
                                         err = -EAGAIN;
                                         goto out_free;
                                 }
+                        } else {
+                                /*
+                                 * If an unprivileged user inherits a 1-many 
+                                 * style socket with open associations on a 
+                                 * privileged port, it MAY be permitted to 
+                                 * accept new associations, but it SHOULD NOT 
+                                 * be permitted to open new associations.
+                                 */
+                                if (ep->base.bind_addr.port < PROT_SOCK &&
+                                    !capable(CAP_NET_BIND_SERVICE)) {
+                                        err = -EACCES;
+                                        goto out_free;
+                                }
                         }
 
                         scope = sctp_scope(&to);
@@ -1515,6 +1528,19 @@ SCTP_STATIC int sctp_sendmsg(struct kiocb *iocb, struct sock *sk,
                                 err = -EAGAIN;
                                 goto out_unlock;
                         }
+                } else {
+                        /*
+                         * If an unprivileged user inherits a one-to-many
+                         * style socket with open associations on a privileged
+                         * port, it MAY be permitted to accept new associations,
+                         * but it SHOULD NOT be permitted to open new
+                         * associations.
+                         */
+                        if (ep->base.bind_addr.port < PROT_SOCK &&
+                            !capable(CAP_NET_BIND_SERVICE)) {
+                                err = -EACCES;
+                                goto out_unlock;
+                        }
                 }
 
                 scope = sctp_scope(&to);