Technically minded Weblog

If you want to know how it began and what this is all about, do read part 1 of the post.
If you just want the instructions on how to root WebOS and add Samba support, read part 4.

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I knew that my smart TV had Linux under the hood. At first, I needed to figure out how to get some kind of shell access to the TV. It turns out, LG does have an app called Developer Mode which offers shell access via SSH. I did try the app out and it did work but the shell access it offered was very limited.
All I had was access to an OpenSSH instance running as unprivileged user in a chroot-like jail.
To add Samba support, I needed root access to the TV’s OS. Since LG’s app did not offer any way of getting root, the only way was to try some kind of exploit, just like you do when rooting Android without custom recovery.
My first thought was to exploit CVE-2016-5195 (aka. the Dirty Cow bug) since it had source code available. So I’ve build the exploit and it out. And… it didn’t work. It turned out that my TVs firmware (version 05.30.01, released on October 31st, 2017) had a patched kernel which wasn’t vulnerable. Since I could not find any other public root exploits, I wasn’t able to root the TV with the firmware it had. The only thing I could think of is downgrading the TVs firmware to an earlier version (with a vulnerable kernel). Which isn’t straightforward, since WebOS normally only supports installing newer firmware versions, not older ones.
Fortunately, with the help of my skills and a tutorial available here: http://webos-forums.ru/post23624.html (in Russian, Google Translate link) I was able to downgrade the firmware to version 04.31.00.
I’ve also found a pre-packed exploit (based on the same Dirty Cow bug which I’ve tried to exploit before) for rooting WebOS with instructions here: http://webos-forums.ru/topic4650.html (again in Russian, Google Translate link). With it, I was able gain root access to WebOS.

That’s when the fun began. Read on to part 3.

I’ve always treated my TVs simply as monitors with some additional functionality, like a built-in tuner or a simple media player. I never treated them as real computers.
Even when my family bought our first smart TV back in 2014, I still treated it as a monitor, even though I did know that it had a real Unix-like OS under the hood.
That has changed when I got (well, inherited) my own Smart TV, an 2016 model LG 43UH603V-ZE running WebOS 3.3.1. I previously had an old LG feature TV and used a separate device (a Raspberry Pi 3 with Kodi) to play all my media.
But since I now had a smart TV, I wanted to play everything directly on it, without using a separate device. My main sources of media are IPTV and my home server (which also acts as a NAS). IPTV viewing wasn’t a problem as WebOS had several apps for that. Connecting my server to the TV was a different story. It turned out that WebOS does not have any kind of support for NAS devices at all. No Samba, no FTP and no way of streaming HTTP links. Nothing.
At first, I tried to resort to using Emby media server via TVs built-in browser (tried Emby’s app as well), but it was too cumbersome to use with a remote. Not to mention the flaws, like really long loading times, buggy resuming and totally unnecessary transcoding of media that my TV could play directly. For example, I could not play a 4K H265 BDRip without Emby trying to transcode it to H264 resulting in choppy video and overloaded server.

This got me thinking: is there any way to mod the TV to retrofit Samba support in a way which would play nice with WebOS ?
And I did find a way. Now on to part 2.

P.S.: Happy 2018, the year of the Yellow Dog ! (sadly the Linux distro with the same name died long ago…)