Buildrootで小さなAPを作る(前編)
前回はRaspberry Pi OSを使用して4GBのSDカードでAPを作ってみましたが、今回は更に小さい2GBのSDカードに収まるAPを構築したいと思います。
今回使用するのは、Buildrootという組込み Linux システムの構築を自動化できるシステムです。
Build rootのインストール
まずは、作業ディレクトリを準備します。
$ mkdir rpi3bplus_hostapd
$ cd rpi3bplus_hostapd
次にBUildrootからbuildroot-2021.02.8.tar.bz2をダウンロードして展開します。
$ wget https://buildroot.org/downloads/buildroot-2021.02.8.tar.bz2
$ tar jxvf buildroot-2021.02.8.tar.bz2
$ cd buildroot-2021.02.8
今回はRaspberry Pi 3B+向けのコンフィグレーションを利用してビルドします。
$ make raspberrypi3_defconfig
$ make all
一度、ビルドが通るか確認したいと思います。
$ make raspberrypi3_defconfig
$ make all
このままだと、リモートログインで作業できないのでsshdを有効にします。
$ make menuconfig
Target packages --->
Networking applications --->
[*] openssh
[*] client (NEW)
[*] server (NEW)
[*] key utilities (NEW)
*** openswan needs a glibc or musl toolchain w/ headers >= 3.4 ***
MainメニューからTarget packagesを選択します。
次にNetworking applicationsを選択します。
そして、opensshを有効にします。
設定を終えたら、保存して終了します。
再度、ビルドを行います。
$ make
出来上がったイメージを書き込んでみましょう。
書き込み対象となるイメージは output/images/sdcard.img です。
$ ls -lh output/images/sdcard.img
-rw-r--r-- 1 developer developer 153M 1月 29 17:47 output/images/sdcard.img
153M と非常に小さいです。
これを、SDカードに書き込みます。
$ sudo dd bs=4M if=output/images/sdcard.img of=/dev/sdb status=progress conv=fsync
$ sync
Root filesystem overlay の設定
SDカードを起動し、SSHでログインを試みるとログインできません。
組み込まれている etc/ssh/sshd_config の中身を確認します。
$ nano output/target/etc/ssh/sshd_config
PermitRootLogin の設定を探すと下記のようになっています。
#PermitRootLogin prohibit-password
今回は、ユーザーアカウントを追加せずに root からログインできるように Yes に変更したいのですが、このファイルは直接編集しません。
buildroot の機能である Root filesystem overlay を使用します。
まず、環境の準備を行うために作業ルートに移動します。
$ cd rpi3bplus_hostapd
$ mkdir rootfs_overlay
$ nano setup.env
下記の内容を記述します。
export ENV_BASE_ROOT=$(pwd)
export ENV_ROOTFS_OVERLAY=${ENV_BASE_ROOT}/rootfs_overlay
続けて、setup.env を読み込みます。
$ source setup.env
これで下準備ができました。
SSHの導入
続けて、rootfs_overlay に環境を構築します。
$ mkdir -p ${ENV_ROOTFS_OVERLAY}/etc/ssh
$ cp buildroot-2021.02.8/output/target/etc/ssh/sshd_config ${ENV_ROOTFS_OVERLAY}/etc/ssh/
今回コピーした ${ENV_ROOTFS_OVERLAY}/etc/ssh/sshd_config を編集します。
$ nano ${ENV_ROOTFS_OVERLAY}/etc/ssh/sshd_config先ほど確認したPermitRootLogin の設定を修正します。
：
#PermitRootLogin prohibit-password
PermitRootLogin yes
：
buildroot に Root filesystem overlay を使用する設定を行います。
$ cd buildroot-2021.02.8
$ make menuconfig
System configuration --->
(${ENV_ROOTFS_OVERLAY}) Root filesystem overlay directories
MainメニューからSystem Configurationを選択します。
次に、Root filesystem overlay directories を指定します。
また、root にもパスワードを設定しておきます。
System configuration --->
[*] Enable root login with password
(rPi3pAss) Root password
設定を保存します。
さて、再度 make を行います。
$ make
無事にオーバーレイできているか確認しておきます。
$ nano output/target/etc/ssh/sshd_config
下記のようになっていれば成功です。
：
#PermitRootLogin prohibit-password
PermitRootLogin yes
：
間違いないようです。
SDイメージを書き込んで再起動してみます。
# dmesg
[ 0.000000] Booting Linux on physical CPU 0x0
[ 0.000000] Linux version 5.10.1-v7 (developer@debian) (arm-buildroot-linux-uclibcgnueabihf-gcc.br_real (Buildroot 2021.02.8) 9.4.0, GNU ld (GNU Binutils) 2.35.2) #1 SMP Wed Jan 19 17:26:11 JST 2022
[ 0.000000] CPU: ARMv7 Processor [410fd034] revision 4 (ARMv7), cr=10c5383d
[ 0.000000] CPU: div instructions available: patching division code
[ 0.000000] CPU: PIPT / VIPT nonaliasing data cache, VIPT aliasing instruction cache
[ 0.000000] OF: fdt: Machine model: Raspberry Pi 3 Model B Plus Rev 1.3
[ 0.000000] Memory policy: Data cache writealloc
[ 0.000000] Reserved memory: created CMA memory pool at 0x35c00000, size 64 MiB
[ 0.000000] OF: reserved mem: initialized node linux,cma, compatible id shared-dma-pool
[ 0.000000] Zone ranges:
[ 0.000000] DMA [mem 0x0000000000000000-0x0000000039bfffff]
[ 0.000000] Normal empty
[ 0.000000] Movable zone start for each node
[ 0.000000] Early memory node ranges
[ 0.000000] node 0: [mem 0x0000000000000000-0x0000000039bfffff]
[ 0.000000] Initmem setup node 0 [mem 0x0000000000000000-0x0000000039bfffff]
[ 0.000000] On node 0 totalpages: 236544
[ 0.000000] DMA zone: 2079 pages used for memmap
[ 0.000000] DMA zone: 0 pages reserved
[ 0.000000] DMA zone: 236544 pages, LIFO batch:63
[ 0.000000] percpu: Embedded 20 pages/cpu s50572 r8192 d23156 u81920
[ 0.000000] pcpu-alloc: s50572 r8192 d23156 u81920 alloc=20*4096
[ 0.000000] pcpu-alloc: [0] 0 [0] 1 [0] 2 [0] 3
[ 0.000000] Built 1 zonelists, mobility grouping on. Total pages: 234465
[ 0.000000] Kernel command line: coherent_pool=1M 8250.nr_uarts=1 snd_bcm2835.enable_compat_alsa=0 snd_bcm2835.enable_hdmi=1 bcm2708_fb.fbwidth=720 bcm2708_fb.fbheight=480 bcm2708_fb.fbswap=1 vc_mem.mem_base=0x3ec00000 vc_mem.mem_size=0x40000000 root=/dev/mmcblk0p2 rootwait console=tty1 console=ttyAMA0,115200
[ 0.000000] Dentry cache hash table entries: 131072 (order: 7, 524288 bytes, linear)
[ 0.000000] Inode-cache hash table entries: 65536 (order: 6, 262144 bytes, linear)
[ 0.000000] mem auto-init: stack:off, heap alloc:off, heap free:off
[ 0.000000] Memory: 854448K/946176K available (10240K kernel code, 1310K rwdata, 2964K rodata, 1024K init, 860K bss, 26192K reserved, 65536K cma-reserved)
[ 0.000000] SLUB: HWalign=64, Order=0-3, MinObjects=0, CPUs=4, Nodes=1
[ 0.000000] ftrace: allocating 31783 entries in 63 pages
[ 0.000000] ftrace: allocated 63 pages with 6 groups
[ 0.000000] rcu: Hierarchical RCU implementation.
[ 0.000000] Rude variant of Tasks RCU enabled.
[ 0.000000] Tracing variant of Tasks RCU enabled.
[ 0.000000] rcu: RCU calculated value of scheduler-enlistment delay is 10 jiffies.
[ 0.000000] NR_IRQS: 16, nr_irqs: 16, preallocated irqs: 16
[ 0.000000] random: get_random_bytes called from start_kernel+0x3b0/0x598 with crng_init=0
[ 0.000000] arch_timer: cp15 timer(s) running at 19.20MHz (phys).
[ 0.000000] clocksource: arch_sys_counter: mask: 0xffffffffffffff max_cycles: 0x46d987e47, max_idle_ns: 440795202767 ns
[ 0.000008] sched_clock: 56 bits at 19MHz, resolution 52ns, wraps every 4398046511078ns
[ 0.000024] Switching to timer-based delay loop, resolution 52ns
[ 0.000309] Console: colour dummy device 80x30
[ 0.001101] printk: console [tty1] enabled
[ 0.001172] Calibrating delay loop (skipped), value calculated using timer frequency.. 38.40 BogoMIPS (lpj=192000)
[ 0.001230] pid_max: default: 32768 minimum: 301
[ 0.001453] LSM: Security Framework initializing
[ 0.001711] Mount-cache hash table entries: 2048 (order: 1, 8192 bytes, linear)
[ 0.001762] Mountpoint-cache hash table entries: 2048 (order: 1, 8192 bytes, linear)
[ 0.003320] Disabling memory control group subsystem
[ 0.003458] CPU: Testing write buffer coherency: ok
[ 0.003959] CPU0: thread -1, cpu 0, socket 0, mpidr 80000000
[ 0.004951] Setting up static identity map for 0x100000 - 0x10003c
[ 0.005178] rcu: Hierarchical SRCU implementation.
[ 0.006101] smp: Bringing up secondary CPUs ...
[ 0.007270] CPU1: thread -1, cpu 1, socket 0, mpidr 80000001
[ 0.008556] CPU2: thread -1, cpu 2, socket 0, mpidr 80000002
[ 0.009765] CPU3: thread -1, cpu 3, socket 0, mpidr 80000003
[ 0.010009] smp: Brought up 1 node, 4 CPUs
[ 0.010042] SMP: Total of 4 processors activated (153.60 BogoMIPS).
[ 0.010073] CPU: All CPU(s) started in HYP mode.
[ 0.010101] CPU: Virtualization extensions available.
[ 0.011072] devtmpfs: initialized
[ 0.028439] VFP support v0.3: implementor 41 architecture 3 part 40 variant 3 rev 4
[ 0.029064] clocksource: jiffies: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 19112604462750000 ns
[ 0.029125] futex hash table entries: 1024 (order: 4, 65536 bytes, linear)
[ 0.032371] pinctrl core: initialized pinctrl subsystem
[ 0.033578] NET: Registered protocol family 16
[ 0.037611] DMA: preallocated 1024 KiB pool for atomic coherent allocations
[ 0.043410] audit: initializing netlink subsys (disabled)
[ 0.043751] audit: type=2000 audit(0.040:1): state=initialized audit_enabled=0 res=1
[ 0.044335] thermal_sys: Registered thermal governor 'step_wise'
[ 0.045229] hw-breakpoint: found 5 (+1 reserved) breakpoint and 4 watchpoint registers.
[ 0.045291] hw-breakpoint: maximum watchpoint size is 8 bytes.
[ 0.045583] Serial: AMBA PL011 UART driver
[ 0.064384] bcm2835-mbox 3f00b880.mailbox: mailbox enabled
[ 0.080159] raspberrypi-firmware soc:firmware: Attached to firmware from 2020-12-15T18:34:30, variant start
[ 0.090171] raspberrypi-firmware soc:firmware: Firmware hash is 4b4aff21f72c5b9ba39d83c7b0f8fa910a6ef99b
[ 0.139465] bcm2835-dma 3f007000.dma: DMA legacy API manager, dmachans=0x1
[ 0.142038] SCSI subsystem initialized
[ 0.142310] usbcore: registered new interface driver usbfs
[ 0.142409] usbcore: registered new interface driver hub
[ 0.142556] usbcore: registered new device driver usb
[ 0.144438] clocksource: Switched to clocksource arch_sys_counter
[ 1.753184] VFS: Disk quotas dquot_6.6.0
[ 1.753326] VFS: Dquot-cache hash table entries: 1024 (order 0, 4096 bytes)
[ 1.753559] FS-Cache: Loaded
[ 1.753844] CacheFiles: Loaded
[ 1.765040] NET: Registered protocol family 2
[ 1.765989] tcp_listen_portaddr_hash hash table entries: 512 (order: 0, 6144 bytes, linear)
[ 1.766076] TCP established hash table entries: 8192 (order: 3, 32768 bytes, linear)
[ 1.766227] TCP bind hash table entries: 8192 (order: 4, 65536 bytes, linear)
[ 1.766441] TCP: Hash tables configured (established 8192 bind 8192)
[ 1.766627] UDP hash table entries: 512 (order: 2, 16384 bytes, linear)
[ 1.766705] UDP-Lite hash table entries: 512 (order: 2, 16384 bytes, linear)
[ 1.767170] NET: Registered protocol family 1
[ 1.768030] RPC: Registered named UNIX socket transport module.
[ 1.768065] RPC: Registered udp transport module.
[ 1.768095] RPC: Registered tcp transport module.
[ 1.768124] RPC: Registered tcp NFSv4.1 backchannel transport module.
[ 1.769701] hw perfevents: enabled with armv7_cortex_a7 PMU driver, 7 counters available
[ 1.773493] Initialise system trusted keyrings
[ 1.773777] workingset: timestamp_bits=14 max_order=18 bucket_order=4
[ 1.783499] zbud: loaded
[ 1.785640] FS-Cache: Netfs 'nfs' registered for caching
[ 1.786556] NFS: Registering the id_resolver key type
[ 1.786638] Key type id_resolver registered
[ 1.786669] Key type id_legacy registered
[ 1.786844] nfs4filelayout_init: NFSv4 File Layout Driver Registering...
[ 1.788025] Key type asymmetric registered
[ 1.788059] Asymmetric key parser 'x509' registered
[ 1.788133] Block layer SCSI generic (bsg) driver version 0.4 loaded (major 249)
[ 1.788174] io scheduler mq-deadline registered
[ 1.788205] io scheduler kyber registered
[ 1.791634] bcm2708_fb soc:fb: FB found 1 display(s)
[ 1.805262] Console: switching to colour frame buffer device 90x30
[ 1.813846] bcm2708_fb soc:fb: Registered framebuffer for display 0, size 720x480
[ 1.820340] Serial: 8250/16550 driver, 1 ports, IRQ sharing enabled
[ 1.826134] bcm2835-rng 3f104000.rng: hwrng registered
[ 1.829483] vc-mem: phys_addr:0x00000000 mem_base=0x3ec00000 mem_size:0x40000000(1024 MiB)
[ 1.836463] gpiomem-bcm2835 3f200000.gpiomem: Initialised: Registers at 0x3f200000
[ 1.853062] brd: module loaded
[ 1.868399] loop: module loaded
[ 1.873061] Loading iSCSI transport class v2.0-870.
[ 1.877923] libphy: Fixed MDIO Bus: probed
[ 1.881299] usbcore: registered new interface driver lan78xx
[ 1.884601] usbcore: registered new interface driver smsc95xx
[ 1.887639] dwc_otg: version 3.00a 10-AUG-2012 (platform bus)
[ 2.618920] Core Release: 2.80a
[ 2.621928] Setting default values for core params
[ 2.625046] Finished setting default values for core params
[ 2.828497] Using Buffer DMA mode
[ 2.831493] Periodic Transfer Interrupt Enhancement - disabled
[ 2.834590] Multiprocessor Interrupt Enhancement - disabled
[ 2.837641] OTG VER PARAM: 0, OTG VER FLAG: 0
[ 2.840626] Dedicated Tx FIFOs mode
[ 2.844154]
[ 2.844176] WARN::dwc_otg_hcd_init:1072: FIQ DMA bounce buffers: virt = b5d14000 dma = 0xf5d14000 len=9024
[ 2.853161] FIQ FSM acceleration enabled for :
[ 2.853161] Non-periodic Split Transactions
[ 2.853161] Periodic Split Transactions
[ 2.853161] High-Speed Isochronous Endpoints
[ 2.853161] Interrupt/Control Split Transaction hack enabled
[ 2.867419] dwc_otg: Microframe scheduler enabled
[ 2.867490]
[ 2.867500] WARN::hcd_init_fiq:457: FIQ on core 1
[ 2.872636]
[ 2.872646] WARN::hcd_init_fiq:458: FIQ ASM at 807cb66c length 36
[ 2.877828]
[ 2.877837] WARN::hcd_init_fiq:496: MPHI regs_base at ba010000
[ 2.883114] dwc_otg 3f980000.usb: DWC OTG Controller
[ 2.885917] dwc_otg 3f980000.usb: new USB bus registered, assigned bus number 1
[ 2.888760] dwc_otg 3f980000.usb: irq 89, io mem 0x00000000
[ 2.891544] Init: Port Power? op_state=1
[ 2.894266] Init: Power Port (0)
[ 2.897302] usb usb1: New USB device found, idVendor=1d6b, idProduct=0002, bcdDevice= 5.10
[ 2.902811] usb usb1: New USB device strings: Mfr=3, Product=2, SerialNumber=1
[ 2.905756] usb usb1: Product: DWC OTG Controller
[ 2.908636] usb usb1: Manufacturer: Linux 5.10.1-v7 dwc_otg_hcd
[ 2.911559] usb usb1: SerialNumber: 3f980000.usb
[ 2.915263] hub 1-0:1.0: USB hub found
[ 2.918166] hub 1-0:1.0: 1 port detected
[ 2.921911] dwc_otg: FIQ enabled
[ 2.921924] dwc_otg: NAK holdoff enabled
[ 2.921936] dwc_otg: FIQ split-transaction FSM enabled
[ 2.921954] Module dwc_common_port init
[ 2.922334] usbcore: registered new interface driver usb-storage
[ 2.925364] mousedev: PS/2 mouse device common for all mice
[ 2.929359] bcm2835-wdt bcm2835-wdt: Broadcom BCM2835 watchdog timer
[ 2.935229] sdhci: Secure Digital Host Controller Interface driver
[ 2.938172] sdhci: Copyright(c) Pierre Ossman
[ 2.941678] mmc-bcm2835 3f300000.mmcnr: could not get clk, deferring probe
[ 2.945397] sdhost-bcm2835 3f202000.mmc: could not get clk, deferring probe
[ 2.948668] sdhci-pltfm: SDHCI platform and OF driver helper
[ 2.953474] ledtrig-cpu: registered to indicate activity on CPUs
[ 2.957051] hid: raw HID events driver (C) Jiri Kosina
[ 2.960271] usbcore: registered new interface driver usbhid
[ 2.963328] usbhid: USB HID core driver
[ 2.970842] Initializing XFRM netlink socket
[ 2.973896] NET: Registered protocol family 17
[ 2.977056] Key type dns_resolver registered
[ 2.980516] Registering SWP/SWPB emulation handler
[ 2.983643] registered taskstats version 1
[ 2.986565] Loading compiled-in X.509 certificates
[ 2.990251] Key type ._fscrypt registered
[ 2.992980] Key type .fscrypt registered
[ 2.995658] Key type fscrypt-provisioning registered
[ 3.009397] uart-pl011 3f201000.serial: there is not valid maps for state default
[ 3.012412] uart-pl011 3f201000.serial: cts_event_workaround enabled
[ 3.015330] 3f201000.serial: ttyAMA0 at MMIO 0x3f201000 (irq = 114, base_baud = 0) is a PL011 rev2
[ 4.058104] printk: console [ttyAMA0] enabled
[ 4.068521] 3f215040.serial: ttyS0 at MMIO 0x3f215040 (irq = 86, base_baud = 50000000) is a 16550
[ 4.084298] bcm2835-power bcm2835-power: Broadcom BCM2835 power domains driver
[ 4.096386] mmc-bcm2835 3f300000.mmcnr: mmc_debug:0 mmc_debug2:0
[ 4.105503] mmc-bcm2835 3f300000.mmcnr: DMA channel allocated
[ 4.141008] sdhost: log_buf @ (ptrval) (f5d13000)
[ 4.186449] mmc1: queuing unknown CIS tuple 0x80 (2 bytes)
[ 4.194974] mmc0: sdhost-bcm2835 loaded - DMA enabled (>1)
[ 4.206454] of_cfs_init
[ 4.211927] of_cfs_init: OK
[ 4.218615] uart-pl011 3f201000.serial: no DMA platform data
[ 4.224605] Indeed it is in host mode hprt0 = 00021501
[ 4.232720] Waiting for root device /dev/mmcblk0p2...
[ 4.295263] mmc1: queuing unknown CIS tuple 0x80 (3 bytes)
[ 4.305395] mmc1: queuing unknown CIS tuple 0x80 (3 bytes)
[ 4.314021] random: fast init done
[ 4.324936] mmc1: queuing unknown CIS tuple 0x80 (7 bytes)
[ 4.355634] mmc0: host does not support reading read-only switch, assuming write-enable
[ 4.370165] mmc0: new high speed SD card at address 0002
[ 4.379742] mmcblk0: mmc0:0002 S02GF 1.84 GiB
[ 4.390668] mmcblk0: p1 p2
[ 4.436531] EXT4-fs (mmcblk0p2): mounted filesystem with ordered data mode. Opts: (null)
[ 4.437726] mmc1: new high speed SDIO card at address 0001
[ 4.450717] VFS: Mounted root (ext4 filesystem) readonly on device 179:2.
[ 4.459287] usb 1-1: new high-speed USB device number 2 using dwc_otg
[ 4.470536] devtmpfs: mounted
[ 4.479373] Indeed it is in host mode hprt0 = 00001101
[ 4.554580] Freeing unused kernel memory: 1024K
[ 4.562477] Run /sbin/init as init process
[ 4.569440] with arguments:
[ 4.569452] /sbin/init
[ 4.569463] with environment:
[ 4.569474] HOME=/
[ 4.569485] TERM=linux
[ 4.688194] EXT4-fs (mmcblk0p2): re-mounted. Opts: (null)
[ 4.724969] usb 1-1: New USB device found, idVendor=0424, idProduct=2514, bcdDevice= b.b3
[ 4.739428] usb 1-1: New USB device strings: Mfr=0, Product=0, SerialNumber=0
[ 4.751015] hub 1-1:1.0: USB hub found
[ 4.758373] hub 1-1:1.0: 4 ports detected
[ 4.825341] random: dd: uninitialized urandom read (512 bytes read)
[ 5.084570] usb 1-1.1: new high-speed USB device number 3 using dwc_otg
[ 5.093732] NET: Registered protocol family 10
[ 5.103694] Segment Routing with IPv6
[ 5.244864] usb 1-1.1: New USB device found, idVendor=0424, idProduct=2514, bcdDevice= b.b3
[ 5.259966] usb 1-1.1: New USB device strings: Mfr=0, Product=0, SerialNumber=0
[ 5.272028] hub 1-1.1:1.0: USB hub found
[ 5.279495] hub 1-1.1:1.0: 3 ports detected
[ 5.640217] dwc_otg_handle_wakeup_detected_intr lxstate = 2
[ 6.074480] usb 1-1.1.1: new high-speed USB device number 4 using dwc_otg
[ 6.225013] usb 1-1.1.1: New USB device found, idVendor=0424, idProduct=7800, bcdDevice= 3.00
[ 6.240222] usb 1-1.1.1: New USB device strings: Mfr=0, Product=0, SerialNumber=0
[ 6.517574] lan78xx 1-1.1.1:1.0 (unnamed net_device) (uninitialized): No External EEPROM. Setting MAC Speed
[ 6.536172] libphy: lan78xx-mdiobus: probed
[ 6.652730] lan78xx 1-1.1.1:1.0 (unnamed net_device) (uninitialized): int urb period 64
[ 7.218754] random: mktemp: uninitialized urandom read (6 bytes read)
[ 9.230156] IPv6: ADDRCONF(NETDEV_CHANGE): eth0: link becomes ready
[ 10.839168] random: mktemp: uninitialized urandom read (6 bytes read)
[ 12.514498] random: crng init done
#
無事にroot でログインできました。
次回は、hostapd の設定を行います。
ちなみに電源を切るときは
# poweroff
です。
