About kernel-headers

[skandbug]

Hi，Thank you for giving us your help!

The bpf source code is not given in bpfroid, in

https://github.com/libbpf/libbpf/tree/d1fd50d475779f64805fdc28f912547b9e3dee8a

can be obtained successfully.
But KERN_HEADERS is not easy to get, as you mentioned

KERN_HEADERS := /home/yaniv/src/thesis/pixel3a/android-kernel/headers/kernel-headers

I got it through

https://github.com/Backup-Gits/android11-5.4

Use make headers_install to mention it, there are always some files missing, such as: generated/autoconf, uapi/linux/ptrace.h

It is possible to give a complete kernel-headers that you use when compiling, thank you.

[yanivagman]

Kernel headers are specific to the kernel you are using.
Even if I will provide the specific headers I used, they are useless if you are not running Android on a pixel 3a device.
So you will need to find a way to get all the headers for the kernel you are compiling to.

[skandbug]

Following the idea you provided, I generated the container in the host with your code. The version of my host is:

5.15.0-46-generic.

I ran your program source code BPFroid in the container.

[skandbug]

I generated the headers with make headers_install, but it always suggests that some files are missing.

[skandbug]

I want to run the compiled BPFroid on Android, but I don't have the binary of BPFroid, so I need to compile it.
Does the compiled binary depend on the Android system version?

[yanivagman]

The headers that you need are of the target device, not of your host.
If your target is Android emulator - you can get the kernel headers from google site.
If your target is an Android device - you will need to get the headers from the device manufacturer.
Precompiled binary won't help you here - the code is compiled to specific kernel structs, and thus need to be compiled against the matching kernel headers

[JacquesJurado]

First I tried to build it for an goldfish kernel for later usage in an emulator. But this methodology didnt work cause of the same problems like @skandbug. Then i followed your advice for compiling it for a pixel 3A in the aarch64 docker container. But then there occured the compilation errors shown in the screenshot.

[yanivagman]

If you are using pixel 3a xl you can simply take the image included in the repository (the kernel headers are also there):
https://github.com/yanivagman/BPFroid/tree/main/pixel%203a

[skandbug]

Thanks, I'll try that later.

[skandbug]

The address you gave is a link, which shows all the source files of Android.

If it is based on the header file of Android11-5.4 (the Android kernel version is fixed), is it convenient for you to provide the header file or have you compiled an executable two-process program? We will be very grateful.

I seem to have encountered this problem too. @JacquesJurado

[yanivagman]

This link is only relevant for pixel 3a xl devices. I provided it since @JacquesJurado wrote that he is trying to compile for a pixel 3a device, for which it should work. To make BPFroid work on any other device/emulator you will have to provide the full kernel headers matching your platform (most probably you can download them from google).

Sorry that I can't help more with that, but this was a side project of mine and Android is not the main focus of my work these days...

[yanivagman]

Unfortunately, I don't remember having these errors

[yanivagman]

One thing I can't understand from your attached image - if you are compiling to an Android emulator, then why do you use the pixel3a folder? You should have your own kernel headers downloaded from google matching your emulator kernel version

[skandbug]

It's not compiling the emulator.
It is compiling bpfroid, the compilation process needs the kernel header files, I downloaded these files from GOOGLE, but during the compilation process there is a problem like the above picture.

[yanivagman]

Do you run the command as described in the readme?
KERN_HEADERS=/path/to/android-goldfish-kernel make
You should change the headers path to point to the sources you downloaded

[skandbug]

What I did was:

1. I downloaded the corresponding version of the header file here(https://android.googlesource.com/platform/bionic/+/master/libc/kernel/), but it prompted me that kconfig.h was missing when I compiled it.
2. I again in https://android.googlesource.com/kernel/common/+/refs/heads/android11-5.4
   I extracted the source file and put it in the same level directory.
3. I modified the address of KERN_HEADERS in your source code to point to the downloaded header file directory.
   After compiling, the error in the figure appears.