net: netprio: fd passed in SCM_RIGHTS datagram not set correctly

A socket fd passed in a SCM_RIGHTS datagram was not getting
updated with the new tasks cgrp prioidx. This leaves IO on
the socket tagged with the old tasks priority.

To fix this add a check in the scm recvmsg path to update the
sock cgrp prioidx with the new tasks value.

Thanks to Al Viro for catching this.

CC: Neil Horman <nhorman@tuxdriver.com>
Reported-by: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: John Fastabend <john.r.fastabend@intel.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 4 insertions, 0 deletions

diff --git a/net/core/scm.c b/net/core/scm.c
index 8f6ccfd68ef4..040cebeed45b 100644
--- a/net/core/scm.c
+++ b/net/core/scm.c
@@ -265,6 +265,7 @@ void scm_detach_fds(struct msghdr *msg, struct scm_cookie *scm)
         for (i=0, cmfptr=(__force int __user *)CMSG_DATA(cm); i<fdmax;
              i++, cmfptr++)
         {
+                struct socket *sock;
                 int new_fd;
                 err = security_file_receive(fp[i]);
                 if (err)
@@ -281,6 +282,9 @@ void scm_detach_fds(struct msghdr *msg, struct scm_cookie *scm)
                 }
                 /* Bump the usage count and install the file. */
                 get_file(fp[i]);
+                sock = sock_from_file(fp[i], &err);
+                if (sock)
+                        sock_update_netprioidx(sock->sk, current);
                 fd_install(new_fd, fp[i]);
         }