net: fix installing orphaned programs
authorJakub Kicinski <jakub.kicinski@netronome.com>
Fri, 1 Nov 2019 03:07:00 +0000 (20:07 -0700)
committerDavid S. Miller <davem@davemloft.net>
Fri, 1 Nov 2019 22:16:01 +0000 (15:16 -0700)
commitaefc3e723a78c2e429a64dadd7815ef2a4aecd44
treeb063451b5cf5c6ab727b3dfdf36f7763d4574f03
parent41aa29a58b5f7f7be43f35372ef411f304a87a0d
net: fix installing orphaned programs

When netdevice with offloaded BPF programs is destroyed
the programs are orphaned and removed from the program
IDA - their IDs get released (the programs may remain
accessible via existing open file descriptors and pinned
files). After IDs are released they are set to 0.

This confuses dev_change_xdp_fd() because it compares
the __dev_xdp_query() result where 0 means no program
with prog->aux->id where 0 means orphaned.

dev_change_xdp_fd() would have incorrectly returned success
even though it had not installed the program.

Since drivers already catch this case via bpf_offload_dev_match()
let them handle this case. The error message drivers produce in
this case ("program loaded for a different device") is in fact
correct as the orphaned program must had to be loaded for a
different device.

Fixes: c14a9f633d9e ("net: Don't call XDP_SETUP_PROG when nothing is changed")
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
net/core/dev.c