Check out autosec.org and read the (refereed academic) papers there about how the alleged firewalling between CAN subnets is largely unimplemented. In my own vehicle using the scantool.net STN1110 OBDLink MX, I can listen to ECUs on several subnets. CAN (actually controller area network) has very little security, and GENIVI has a Networking Expert Group and a Security Team that are laboring to create new standards to address the situation.
As someone who has participated in GENIVI, I am excited about the new AGL and look forward to learning more. I am delighted that the previously quiet Toyota is stepping up to provide leadership alongside Samsung and Intel with Tizen. Linux is winning big in automotive, which will be an increasingly vital arena as autonomous vehicles become inevitable. California has made self-driving cars legal within the week, so we shouldn't squabble, but roll up our sleeves and get to the work.
The article is yet more great coverage of Linux IVI by Nate Willis and Michael Kerrisk. Thank you LWN!