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net: fix installing orphaned programs

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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>
This commit is contained in:
Jakub Kicinski 2019-10-31 20:07:00 -07:00 committed by David S. Miller
parent 41aa29a58b
commit aefc3e723a
1 changed files with 2 additions and 1 deletions
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3
net/core/dev.c
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@ -8421,7 +8421,8 @@ int dev_change_xdp_fd(struct net_device *dev, struct netlink_ext_ack *extack,
return -EINVAL;
}
if (prog->aux->id == prog_id) {
/* prog->aux->id may be 0 for orphaned device-bound progs */
if (prog->aux->id && prog->aux->id == prog_id) {
bpf_prog_put(prog);
return 0;
}