tmm1
commented
1 year ago Okay so I found arm64 widevinecdm.so in two places:
gs://chromeos-localmirror has squashfs archives containing arm64 chrome which are part of Lacros
According to https://chromium.googlesource.com/chromiumos/docs/+/HEAD/archive_mirrors.md#public-mirrors, this bucket is used by google developers to "manually copy files for mirroring purposes". However it seems there is some automated process uploading builds there, because there are many months worth of chrome builds going back to chrome v99
A full list is available on this url: https://gsdview.appspot.com/chromeos-localmirror/distfiles/?marker=distfiles%2Fchromeos-lacros-amd64-squash-zstd-106.0.5249.42
These can be extracted using unsquashfs as follows:
$ wget https://gsdview.appspot.com/chromeos-localmirror/distfiles/chromeos-lacros-arm64-squash-zstd-112.0.5579.0
$ unsquashfs chromeos-lacros-arm64-squash-zstd-112.0.5579.0
$ file squashfs-root/WidevineCdm/_platform_specific/cros_arm64/libwidevinecdm.so
ELF 64-bit LSB shared object, ARM aarch64, version 1 (SYSV), dynamically linked, BuildID[sha1]=b71fd3342a03fdb140e1f7a757960df219d63625, strippedbeta update images for certain Acer chromebooks (trogdor / lazor) use arm64 userland
According to https://www.chromium.org/chromium-os/developer-information-for-chrome-os-devices/, the existing ARM chromebooks all currently using aarch64 kernel combined with arm userland.
However according to this thread, someone reported that beta on their chromebook was using arm64 userland.
Unfortunately the https://dl.google.com/dl/edgedl/chromeos/recovery/recovery.json endpoint only lists STABLE builds. On https://chromiumdash.appspot.com/serving-builds?deviceCategory=ChromeOS you can see the latest beta and canary builds, but there is no way to download them.
This was confirmed according to this reddit post that there are no recovery images available for beta and canary builds builds. There is a feature request active for beta recovery images, but has not seen any traction.
Looking for a way to download beta update images, I found this reddit post which talks about how to find the urls on an actual device inside /var/log/update_engine.log. The url format used is also provided.
Based on that information, I found this blog post which explains how google's "omaha" update service serves up beta updates. The post includes some python code to make an update request yourself, which is available in this repo: https://github.com/ajorg/cros-updates
I cloned that repo, and after some searching I was able to find the relevant variables for the trogdor device, which are typically available on the device as follows:
With those vars, I made the following change to cros-updates:
--- a/lambda_function.py
+++ b/lambda_function.py
@@ -53,10 +53,10 @@ CHROMEBOOKS_JSON = (
environ.get("CHROMEBOOKS_JSON")
or """[
{
- "appid": "{92A7272A-834A-47A3-9112-E8FD55831660}",
- "track": "stable-channel",
- "board": "kevin-signed-mpkeys",
- "hardware_class": "KEVIN D25-A3E-B2A-O8Y"
+ "appid": "{9023C063-08D6-4A4F-908C-BCF97DE8BA69}",
+ "track": "beta-channel",
+ "board": "trogdor-signed-mpkeys",
+ "hardware_class": "LAZOR-FHYR D5B-B2A-F4G-R2W-B5X"
}
]"""
)Then running python3 lambda_function.py produces the URL to the latest beta image for that device:
$ python3 lambda_function.py
{"Request": "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n<request protocol=\"3.0\" ismachine=\"1\">\n <app appid=\"{9023C063-08D6-4A4F-908C-BCF97DE8BA69}\" track=\"beta-channel\" board=\"trogdor-signed-mpkeys\" hardware_class=\"LAZOR-FHYR D5B-B2A-F4G-R2W-B5X\" delta_okay=\"false\">\n <updatecheck/>\n </app>\n</request>"}
{"Response": "<?xml version=\"1.0\" encoding=\"UTF-8\"?><response protocol=\"3.0\" server=\"prod\"><daystart elapsed_days=\"5882\" elapsed_seconds=\"40272\"/><app appid=\"{9023C063-08D6-4A4F-908C-BCF97DE8BA69}\" cohort=\"1:6:\" cohortname=\"trogdor_lazor_beta\" status=\"ok\"><updatecheck _eol_date=\"22067\" _firmware_version=\"1.1\" _firmware_version_0=\"1.1\" _firmware_version_1=\"1.1\" _firmware_version_2=\"1.1\" _firmware_version_3=\"1.1\" _firmware_version_4=\"1.1\" _kernel_version=\"1.1\" _kernel_version_0=\"1.1\" _kernel_version_1=\"1.1\" _kernel_version_2=\"1.1\" _kernel_version_3=\"1.1\" _kernel_version_4=\"1.1\" status=\"ok\"><urls><url codebase=\"http://edgedl.me.gvt1.com/edgedl/chromeos/trogdor/15278.51.0/beta-channel/\"/><url codebase=\"http://dl.google.com/chromeos/trogdor/15278.51.0/beta-channel/\"/><url codebase=\"https://edgedl.me.gvt1.com/edgedl/chromeos/trogdor/15278.51.0/beta-channel/\"/><url codebase=\"https://dl.google.com/chromeos/trogdor/15278.51.0/beta-channel/\"/></urls><manifest version=\"15278.51.0\"><actions><action event=\"install\" run=\"chromeos_15278.51.0_trogdor_beta-channel_full_mp-v7.bin-gyzwiyrwmezgn7gx74jxtm47d4vece3i.signed\"/><action ChromeOSVersion=\"15278.51.0\" ChromeVersion=\"110.0.5481.82\" IsDeltaPayload=\"false\" MaxDaysToScatter=\"14\" MetadataSignatureRsa=\"HBo/h/FnoHniouS7gmZOVk60LDhhiNBxYG7qFErgp8GqWj5W4+1Jkm8fvK7mUGlqZ5B2lO3Q3CDgJdHgVUjSWzcO7oiqRWeGXjqgabovTPvAMANYhmMo2xyX+1hQGX8smScVxqqB6I5+PVOClEWkxsc5Sb+6uer/6FoNrJPmIAuZ/qxHe3z1kvnnUULUUvwdwXMOc3x6N+qMTlYF4Vu7H3IZ572nSbRf4LP+2WR4aWtwvj0Hvvu9G4jc1QGgrojlw4PKgTpUOFOLwe9V9MSqEOtYmTZbIyFRytbOItczTbwn3773bZfgApm4cNcUFxLN5i8+w41aURdhutsr9pVKPw==\" MetadataSize=\"66182\" event=\"postinstall\" sha256=\"7p45aYKjOGD9gtdGQeZ1/pu36MM/9iRfI8lagq0lwAw=\"/></actions><packages><package fp=\"3.ee9e396982a33860fd82d74641e675fe9bb7e8c33ff6245f23c95a82ad25c00c\" hash_sha256=\"ee9e396982a33860fd82d74641e675fe9bb7e8c33ff6245f23c95a82ad25c00c\" name=\"chromeos_15278.51.0_trogdor_beta-channel_full_mp-v7.bin-gyzwiyrwmezgn7gx74jxtm47d4vece3i.signed\" required=\"true\" size=\"1251102522\"/></packages></manifest></updatecheck></app></response>", "Status": 200}
Acer Chromebook Spin 513, CP513-1H/1HL, R841T/LT updated to 110.0.5481.82The URL constructed out of the json/xml response is:
Looking at this file, you'll notice the first four bytes are CrAU. Searching for that, I discovered this project to extract these files: https://github.com/sebanc/chromeos-ota-extract/blob/master/extract_android_ota_payload.py
Running that produces:
$ python3 extract_android_ota_payload.py chromeos_15278.51.0_trogdor_beta-channel_full_mp-v7.bin-gyzwiyrwmezgn7gx74jxtm47d4vece3i.signed
Extracting 'root.img'
Extracting 'kernel.img'where root.img is an ext2 filesystem:
$ file root.img
root.img: Linux rev 1.0 ext2 filesystem data, UUID=00000000-0000-0000-0000-000000000000, volume name "ROOT-A" (large files)I was able to loopback mount this, and inside I found the same widevinecdm.so:
$ file /mnt/ROOT-A/opt/google/chrome/WidevineCdm/_platform_specific/cros_arm64/libwidevinecdm.so
ELF 64-bit LSB shared object, ARM aarch64, version 1 (SYSV), dynamically linked, BuildID[sha1]=b71fd3342a03fdb140e1f7a757960df219d63625, stripped
matthuisman
jollySleeper
And removed the arm64 check in 
lameventanas
CastagnaIT
horstle
slavid
64bit ARM Linux Widevine CDM now out in the wild :slightly_smiling_face: @tmm1 found it. looks like was just released last month in a new 64bit beta chrome os
" seems new development https://groups.google.com/a/chromium.org/g/chromium-os-dev/c/GdZ0mebutXw inside https://gsdview.appspot.com/chromeos-localmirror/distfiles/chromeos-lacros-arm64-squash-zstd-112.0.5579.0 "
i managed to open the above squash-zstd file in windows using an extended version of 7zip: https://github.com/mcmilk/7-Zip-zstd
tmm1 said its not working in the arm64 build of LibreELEC due to "libwidevinecdm.so: undefined symbol: __aarch64_ldadd4_acq_rel" but the LibreELEC guys are looking into it
inputstream helper will need to add support for this. Not sure if there is any recovery image that contains it yet. Unless there is a Beta channel recovery. Looking for Acer Chromebook Spin 13 (CP713-1WN) on Chrome version 112 Current "Stable" seems to be chrome 109
UPDATE: "LE folks got aarch64 widevine working! Might require some glibc patches, will see how it shakes out"