Network Feature Example Failed

[buszk]

Hi all,

I want to explore the network feature of LKL and found the documentation not very helpful, so I wonder if I could get some help here.

I am using the provided sample conf.json and running command LKL_HIJACK_CONFIG_FILE="conf.json" bin/lkl-hijack.sh ip addr s

The result shows some errors and I'm very confused. They are 1) /dev/net/tun: failed to attach to: Operation not permitted, 2) no netdev available tap7, 3) Network is unreachable. The full output is as follows.

I would like some help with fixing the errors or pointing out why they exist.

LKL_HIJACK_CONFIG_FILE="conf.json" bin/lkl-hijack.sh ip addr s
/dev/net/tun: failed to attach to: Operation not permitted
/dev/net/tun: failed to attach to: Operation not permitted
LKL: Pin To CPU 0
[    0.000000] Linux version 5.3.0+ (buszk@debian) (gcc version 8.3.0 (Debian 8.3.0-6)) #1 Tue Mar 3 22:28:04 EST 2020
[    0.000000] memblock address range: 0x7f9ca4000000 - 0x7f9ca7fff000
[    0.000000] Built 1 zonelists, mobility grouping on.  Total pages: 16159
[    0.000000] Kernel command line: ip=dhcp
[    0.000000] Dentry cache hash table entries: 8192 (order: 4, 65536 bytes, linear)
[    0.000000] Inode-cache hash table entries: 4096 (order: 3, 32768 bytes, linear)
[    0.000000] mem auto-init: stack:off, heap alloc:off, heap free:off
[    0.000000] Memory available: 64500k/65532k RAM
[    0.000000] SLUB: HWalign=32, Order=0-3, MinObjects=0, CPUs=1, Nodes=1
[    0.000000] NR_IRQS: 4096
[    0.000000] lkl: irqs initialized
[    0.000000] clocksource: lkl: mask: 0xffffffffffffffff max_cycles: 0x1cd42e4dffb, max_idle_ns: 881590591483 ns
[    0.000000] lkl: time and timers initialized (irq1)
[    0.000003] pid_max: default: 4096 minimum: 301
[    0.000022] Mount-cache hash table entries: 512 (order: 0, 4096 bytes, linear)
[    0.000025] Mountpoint-cache hash table entries: 512 (order: 0, 4096 bytes, linear)
[    0.003137] random: get_random_bytes called from _etext+0xb531/0x13ec2 with crng_init=0
[    0.006085] printk: console [lkl_console0] enabled
[    0.006342] clocksource: jiffies: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 19112604462750000 ns
[    0.006478] xor: automatically using best checksumming function   8regs
[    0.006810] NET: Registered protocol family 16
[    0.326411] raid6: int64x8  gen()  9281 MB/s
[    0.633181] raid6: int64x8  xor()  5944 MB/s
[    0.964759] raid6: int64x4  gen()  9940 MB/s
[    1.316995] raid6: int64x4  xor()  7179 MB/s
[    1.631363] raid6: int64x2  gen() 12244 MB/s
[    1.967435] raid6: int64x2  xor()  7961 MB/s
[    2.306273] raid6: int64x1  gen() 11062 MB/s
[    2.648061] raid6: int64x1  xor()  6253 MB/s
[    2.648133] raid6: using algorithm int64x2 gen() 12244 MB/s
[    2.648162] raid6: .... xor() 7961 MB/s, rmw enabled
[    2.648526] raid6: using intx1 recovery algorithm
[    2.649190] clocksource: Switched to clocksource lkl
[    2.649746] NET: Registered protocol family 2
[    2.650290] tcp_listen_portaddr_hash hash table entries: 256 (order: 0, 4096 bytes, linear)
[    2.650346] TCP established hash table entries: 512 (order: 0, 4096 bytes, linear)
[    2.650468] TCP bind hash table entries: 512 (order: 0, 4096 bytes, linear)
[    2.650612] TCP: Hash tables configured (established 512 bind 512)
[    2.650954] UDP hash table entries: 128 (order: 0, 4096 bytes, linear)
[    2.651098] UDP-Lite hash table entries: 128 (order: 0, 4096 bytes, linear)
[    2.651604] workingset: timestamp_bits=62 max_order=15 bucket_order=0
[    2.652633] SGI XFS with ACLs, security attributes, no debug enabled
[    2.653078] io scheduler mq-deadline registered
[    2.653083] io scheduler kyber registered
[    2.655691] NET: Registered protocol family 10
[    2.656030] Segment Routing with IPv6
[    2.656190] sit: IPv6, IPv4 and MPLS over IPv4 tunneling driver
[    2.656619] Btrfs loaded, crc32c=crc32c-generic
[   15.139332] Warning: unable to open an initial console.
[   15.139353] This architecture does not have kernel memory protection.
[   15.139355] Run /init as init process
no netdev available tap7
RTNETLINK answers: Network is unreachable
failed to set IPv4 gateway: Network is unreachable
RTNETLINK answers: No route to host
failed to set IPv6 gateway: No route to host
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host
       valid_lft forever preferred_lft forever
2: sit0@NONE: <NOARP> mtu 1480 qdisc noop state DOWN group default qlen 1000
    link/sit 0.0.0.0 brd 0.0.0.0
[   15.141086] reboot: Restarting system

[buszk]

After some digging with strace I found that the user does not have permission to call ioctl on /dev/net/tun. After switching to root, the script can run. Now the problem is that it is actually very slow.