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1# FreeBSD
2
3## How to run syzkaller on FreeBSD using qemu
4
5So far the process is tested only on linux/amd64 host. To build Go binaries do:
6```
7make manager fuzzer execprog TARGETOS=freebsd
8```
9To build C `syz-executor` binary, copy `executor/*` files to a FreeBSD machine and build there with:
10```
11c++ executor/executor_freebsd.cc -o syz-executor -O1 -lpthread -DGOOS=\"freebsd\" -DGIT_REVISION=\"CURRENT_GIT_REVISION\"
12```
13Then, copy out the binary back to host into `bin/freebsd_amd64` dir.
14
15Building/running on a FreeBSD host should work as well, but currently our `Makefile` does not work there, so you will need to do its work manually.
16
17Then, you need a FreeBSD image with root ssh access with a key. General instructions can be found here [qemu instructions](https://wiki.qemu.org/Hosts/BSD). I used `FreeBSD-11.0-RELEASE-amd64.qcow2` image, and it required a freashly built `qemu-system-x86_64` (networking did not work in the system-provided one). After booting add the following to `/boot/loader.conf`:
18```
19autoboot_delay="-1"
20console="comconsole"
21```
22and the following to `/etc/rc.conf`:
23```
24sshd_enable="YES"
25ifconfig_em0="inet 10.0.0.1 netmask 255.255.255.0"
26```
27Here is `/etc/ssh/sshd_config` that I used:
28```
29Port 22
30AddressFamily any
31ListenAddress 0.0.0.0
32ListenAddress ::
33Protocol 2
34HostKey /etc/ssh/ssh_host_rsa_key
35SyslogFacility AUTH
36LogLevel INFO
37AuthenticationMethods publickey password
38PermitRootLogin yes
39PubkeyAuthentication yes
40AuthorizedKeysFile .ssh/authorized_keys .ssh/authorized_keys2
41PasswordAuthentication yes
42PermitEmptyPasswords yes
43Subsystem sftp /usr/libexec/sftp-server
44```
45
46Check that you can run the VM with:
47```
48qemu-system-x86_64 -m 2048 -hda FreeBSD-11.0-RELEASE-amd64.qcow2 -enable-kvm -netdev user,id=mynet0,host=10.0.2.10,hostfwd=tcp::10022-:22 -device e1000,netdev=mynet0 -nographic
49```
50and ssh into it with a key.
51
52If all of the above worked, create `freebsd.cfg` config file with the following contents (alter paths as necessary):
53```
54{
55	"name": "freebsd",
56	"target": "freebsd/amd64",
57	"http": ":10000",
58	"workdir": "/workdir",
59	"syzkaller": "/gopath/src/github.com/google/syzkaller",
60	"image": "/FreeBSD-11.1-RELEASE-amd64.qcow2",
61	"sshkey": "/freebsd_id_rsa",
62	"sandbox": "none",
63	"procs": 8,
64	"type": "qemu",
65	"vm": {
66		"qemu": "/qemu/build/x86_64-softmmu/qemu-system-x86_64",
67		"count": 10,
68		"cpu": 4,
69		"mem": 2048
70	}
71}
72```
73
74Then, start `syz-manager` with:
75```
76bin/syz-manager -config freebsd.cfg
77```
78It should start printing output along the lines of:
79```
80booting test machines...
81wait for the connection from test machine...
82machine check: 253 calls enabled, kcov=true, kleakcheck=false, faultinjection=false, comps=false
83executed 3622, cover 1219, crashes 0, repro 0
84executed 7921, cover 1239, crashes 0, repro 0
85executed 32807, cover 1244, crashes 0, repro 0
86executed 35803, cover 1248, crashes 0, repro 0
87```
88If something does not work, add `-debug` flag to `syz-manager`.
89
90## Missing things
91
92- Coverage. `executor/executor_freebsd.cc` uses a very primitive fallback for coverage. We need KCOV for FreeBSD. It will also help to assess what's covered and what's missing.
93- System call descriptions. `sys/freebsd/*.txt` is a dirty copy from `sys/linux/*.txt` with everything that does not compile dropped. We need to go through syscalls and verify/fix/extend them, including devices/ioctls/etc.
94- Currently only `amd64` arch is supported. Supporting `386` would be useful, because it should cover compat paths. Also, we could do testing of the linux-compatibility subsystem.
95- `pkg/csource` needs to be taught how to generate/build C reproducers.
96- `pkg/host` needs to be taught how to detect supported syscalls/devices.
97- `pkg/report`/`pkg/symbolizer` need to be taught how to extract/symbolize kernel crash reports.
98- We need to learn how to build/use debug version of kernel.
99- KASAN for FreeBSD would be useful.
100- On Linux we have emission of exernal networking/USB traffic into kernel using tun/gadgetfs. Implementing these for FreeBSD could uncover a number of high-profile bugs.
101- Last but not least, we need to support FreeBSD in `syz-ci` command (including building kernel/image continuously from git).
102