syzkaller/docs/fuchsia

Fuchsia support

For information about checking out and building Fuchsia see Getting Started and Source Code.

Prerequisites

To run syzkaller with a fuchsia target, you will need:

• A fuchsia checkout.

The rest of the document will use the following environment variables:

• SOURCEDIR path of your fuchsia checkout.

Building Fuchsia

To build fuchsia run:

$ fx --dir "out/arm64" set core.arm64 \
  --with-base "//bundles:tools" \
  --with-base "//src/testing/fuzzing/syzkaller" \
  --args=syzkaller_dir='"/full/path/to/syzkaller"'
$ fx clean-build

And

$ fx --dir "out/x64" set core.x64 \
  --with-base "//bundles:tools" \
  --with-base "//src/testing/fuzzing/syzkaller" \
  --args=syzkaller_dir='"/full/path/to/syzkaller"'
$ fx clean-build

Building binaries for fuchsia

To build all the binaries required for running syzkaller in fuchsia, run:

$ make TARGETOS=fuchsia TARGETARCH=amd64 \
    SOURCEDIR=path/to/fuchsia/checkout

Running syz-manager

Running syz-manager requires you to have built fuchsia previously, and added the ssh keys to the fuchsia.zbi image:

$ ${SOURCEDIR}/out/x64.zircon/tools/zbi -o ${SOURCEDIR}/out/x64/fuchsia-ssh.zbi ${SOURCEDIR}/out/x64/fuchsia.zbi --entry "data/ssh/authorized_keys=${SOURCEDIR}/.ssh/authorized_keys"

Note: This needs to be repeated after each fx build.

Run syz-manager with a config along the lines of:

{
        "name": "fuchsia",
        "target": "fuchsia/amd64",
        "http": ":12345",
        "workdir": "/workdir.fuchsia",
        "kernel_obj": "/fuchsia/out/x64.zircon/kernel-x64-gcc",
        "syzkaller": "/syzkaller",
        "image": "/fuchsia/out/x64/obj/build/images/fvm.blk",
        "sshkey": "/fuchsia/.ssh/pkey",
        "reproduce": false,
        "cover": false,
        "procs": 8,
        "type": "qemu",
        "vm": {
                "count": 10,
                "cpu": 4,
                "mem": 2048,
                "kernel": "/fuchsia/out/x64.zircon/multiboot.bin",
                "initrd": "/fuchsia/out/x64/fuchsia-ssh.zbi"
        }
}

Update syscall and fidl definitions

Syscall descriptions live in the sys/fuchsia folder. To update a syscall, you need to modify the .txt file that contains it, make sure your new definition matches the one in zircon's syscalls.abigen file. If the syscall was used in executor/common_fuchsia.h, you need to update the usages there as well. FIDL definitions do not need manual updating because they are extracted automatically when you run make extract, but they require Fuchsia to be rebuilt for each architecture (see "Building Fuchsia" above).

Once you updated the syscalls definitions, everything can be regenerated by running:

make extract TARGETOS=fuchsia SOURCEDIR=/path/to/fuchsia/checkout
make generate

How to generate syscall description for FIDL

TODO: This section is out of date.

Syscall descriptions for FIDL are automatically generated as part of make extract as described above.

However, if you wish to manually generate syscall descriptions for a given .fidl file, do the following.

FIDL files should first be compiled into FIDL intermediate representation (JSON) files using fidlc:

$SOURCEDIR/out/x64/host_x64/fidlc --json /tmp/io.json --files $SOURCEDIR/zircon/system/fidl/fuchsia-io/io.fidl

Then run FIDL compiler backend fidlgen with syzkaller generator, which compiles a FIDL IR file into a syscall description file:

$SOURCEDIR/out/x64/host_x64/fidlgen -generators syzkaller -json /tmp/io.json -output-base fidl_io -include-base fidl_io

Running syz-ci locally

To run syz-ci locally for Fuchsia, you need:

• bootstrapped Fuchsia checkout (in /bootstrap/fuchsia dir in the example below)
• bootstrap syz-ci binary (in the current dir, build with make ci)
• syz-ci config similar to the one below (in ci.cfg file in the current dir)

{
	"name": "testci",
	"http": ":50000",
	"manager_port_start": 50001,
	"syzkaller_repo": "https://github.com/google/syzkaller.git",
	"managers": [
		{
			"name": "fuchsia",
			"repo": "https://fuchsia.googlesource.com",
			"manager_config": {
				"target": "fuchsia/amd64",
				"type": "qemu",
				"cover": false,
				"procs": 8,
				"vm": {
					"count": 4,
					"cpu": 4,
					"mem": 1024
				}
			}
		}
	]
}

Run syz-ci as:

SOURCEDIR=/bootstrap/fuchsia ./syz-ci -config ci.cfg

Troubleshooting

While running the make extract step, it's possible that the fidl definitions are not up to date. It could happen that they have been removed or renamed.

If this is the case, you would see an error mentioning that the fidl.json file could not be found:

go generate ./sys/fuchsia
cannot find /path-to-fuchsia/out/x64/fidling/gen/zircon/public/fidl/zircon-ethernet/zircon-ethernet.fidl.json
exit status 1

You can search for the string in the fuchsia repos or in the code-review tool to see what happened to it. If the fidl interface was renamed or removed, you should update sys/fuchsia/fidlgen/main.go to reflect this change, and remove the stale autogenerated files.