google / alioth / 43396930315

44%

Build Type

push

github

Committed by Lencerf

Commit Message

fix(net): validate TAP MTU and make VIRTIO_NET_F_MTU optional

Net::new() unconditionally offered VIRTIO_NET_F_MTU with
TapNetSpec::mtu as config.mtu. When mtu was set below 68, the device
advertised VIRTIO_NET_F_MTU with an invalid config.mtu, violating
VirtIO 1.4 Sec 5.1.4.1 ("The device MUST set mtu to between 68 and
65535 inclusive, if it offers VIRTIO_NET_F_MTU"). Linux tolerates it
by not accepting VIRTIO_NET_F_MTU if config.mtu is below 68.

Make TapNetSpec::mtu optional on the command line, defaulting to 0.
When it is 0, set config.mtu to 0 and omit NetFeature::MTU from the
device features. Otherwise validate mtu >= 68 before opening the TAP
device and return Error::InvalidMtu if it is smaller.

Signed-off-by: Changyuan Lyu <changyuanl@google.com>

Coverage Stats

1004 of 1788 branches covered (56.15%)

Branch coverage included in aggregate %.

28 of 35 new or added lines in 1 file covered. (80.0%)

1 existing line in 1 file now uncovered.

7139 of 16578 relevant lines covered (43.06%)

900.27 hits per line