Category Archives: Embedded

D-Link DAP-1520 hacking: Part 1

5 Replies

What do you do with a device you never would have bought for yourself, but received for free? Say welcome the D-Link DAP-1520, a “WiFi Extender” that was given to me by O2 as a bonus for signing up with them. Hopefully they aren’t expecting it back in one piece…

So, what is the DAP-1520? Executive summary:

  • Supports 2.4GHz at 300MBps and 5GHz at 433MBps (thanks to SmallNetBuilder for demystifying this)
  • Repeats the packets from your existing WiFi network for extending range
  • Will also turn a 2.4GHz network into 5GHz through the repeating process (or vice versa)
  • No Ethernet ports because Ethernet is so 2014

    • Right, now that we’ve got the useless D-Link page out of the way, let’s talk about what’s actually in the DAP-1520:

  • MediaTek MT7260A SoC running at 580MHz (includes 2.4GHz radio)
  • 64MB RAM (Winbond W9751G6KB-25 64471X600ZY2)
  • 8MB Flash (MXIC MX 25L640GE)
  • MediaTek MT7610EN (5GHz radio)
  • Skyworks 5GHz Frontend module (datasheet [PDF])

    • This all sounds great, but what do we actually have here? I will preface this post by saying that I started out wanting to port OpenWrt to this device, and I still do, but I got side tracked in my investigation and you’ll have to wait for a follow up post if I ever succeed to port OpenWrt.

    PCB front

    PCB front

    PCB Rear

    PCB Rear

    The UART runs at 57600 8N1.

    No pictures of the power supply because it’s just a boring 5V power source.

    Okay, so now that we know the UART pinout, what does the device say when it boots?

    Boot log:

    U-Boot 1.1.3 (Aug  8 2013 - 10:32:46)

Board: Ralink APSoC DRAM:  64 MB
relocate_code Pointer at: 83fb0000
enable ephy clock...done. rf reg 29 = 5
SSC disabled.
spi_wait_nsec: 29 
spi device id: c2 20 17 c2 20 (2017c220)
find flash: MX25L6405D
raspi_read: from:30000 len:1000 
*** Warning - bad CRC, using default environment

============================================ 
Ralink UBoot Version: 4.1.1.0
-------------------------------------------- 
ASIC 7620_MP (Port5None)
DRAM component: 512 Mbits DDR, width 16
DRAM bus: 16 bit
Total memory: 64 MBytes
Flash component: SPI Flash
Date:Aug  8 2013  Time:10:32:46
Cameo Version: v1.00 Build:01
Module Name: D-Link DAP-1520A1
============================================ 
icache: sets:512, ways:4, linesz:32 ,total:65536
dcache: sets:256, ways:4, linesz:32 ,total:32768 

 ##### The CPU freq = 580 MHZ #### 
 estimate memory size =64 Mbytes
raspi_read: from:50000 len:40 
raspi_read: from:4f0000 len:40 

=================================================
Check image validation:
Image1 Header Magic Number --> OK
Image2 Header Magic Number --> OK
Image1 Header Checksum --> OK
Image2 Header Checksum --> OK
Image1 Data Checksum --> raspi_read: from:50040 len:ddf98 
OK
Image2 Data Checksum --> raspi_read: from:4f0040 len:ca8f4 
OK
Image1 Stable Flag --> Not stable
Image1 Try Counter --> 0

Image1: OK Image2: OK
Both images are OK!!!

=================================================

Please choose the operation: 
   1: Load system code to SDRAM via TFTP. 
   2: Load system code then write to Flash via TFTP. 
   3: Boot system code via Flash (default).
   4: Entr boot command line interface.
   7: Load Boot Loader code then write to Flash via Serial. 
   9: Load Boot Loader code then write to Flash via TFTP. 
 1  0 
   
3: System Boot system code via Flash.
## Booting image at bc050000 ...
raspi_read: from:50000 len:40 
   Image Name:   Linux Kernel Image
   Image Type:   MIPS Linux Kernel Image (lzma compressed)
   Data Size:    909208 Bytes = 887.9 kB
   Load Address: 80000000
   Entry Point:  8000c310
raspi_read: from:50040 len:ddf98 
   Verifying Checksum ... OK
   Uncompressing Kernel Image ... OK
No initrd
## Transferring control to Linux (at address 8000c310) ...
## Giving linux memsize in MB, 64

Starting kernel ...


LINUX started...

 THIS IS ASIC
Linux version 2.6.36.x (root@ubuntu-10) (gcc version 3.4.2) #1 Fri Aug 22 16:26:27 CST 2014

 The CPU feqenuce set to 580 MHz

 MIPS CPU sleep mode enabled.
 PCIE: bypass PCIe DLL.
 PCIE: Elastic buffer control: Addr:0x68 -> 0xB4
 disable all power about PCIe
CPU revision is: 00019650 (MIPS 24Kc)
Determined physical RAM map:
 memory: 04000000 @ 00000000 (usable)
Zone PFN ranges:
  Normal   0x00000000 -> 0x00004000
Movable zone start PFN for each node
early_node_map[1] active PFN ranges
    0: 0x00000000 -> 0x00004000
Built 1 zonelists in Zone order, mobility grouping on.  Total pages: 16256
Kernel command line: console=ttyS1,57600n8 root=/dev/mtdblock5 console=ttyS0,57600 root=31:05 rootfstype=squashfs init=/sbin/init
PID hash table entries: 256 (order: -2, 1024 bytes)
Dentry cache hash table entries: 8192 (order: 3, 32768 bytes)
Inode-cache hash table entries: 4096 (order: 2, 16384 bytes)
Primary instruction cache 64kB, VIPT, 4-way, linesize 32 bytes.
Primary data cache 32kB, 4-way, PIPT, no aliases, linesize 32 bytes
Writing ErrCtl register=0007efde
Readback ErrCtl register=0007efde
Memory: 62028k/65536k available (2225k kernel code, 3508k reserved, 338k data, 168k init, 0k highmem)
NR_IRQS:128
MTK/Ralink System Tick Counter init... cd:80271d98, m:214748, s:32
console [ttyS1] enabled
Calibrating delay loop... 386.04 BogoMIPS (lpj=772096)
pid_max: default: 32768 minimum: 301
Mount-cache hash table entries: 512
NET: Registered protocol family 16
RALINK_GPIOMODE = 1a311d
RALINK_GPIOMODE = 18311d
PPLL_CFG1=0xe90000
MT7620 PPLL lock
PPLL_DRV =0x80080504
start PCIe register access
RALINK_PCI_PCICFG_ADDR = 1000f0

*************** MT7620 PCIe RC mode *************
bio: create slab  at 0
vgaarb: loaded
pci 0000:00:00.0: BAR 8: assigned [mem 0x20000000-0x201fffff]
pci 0000:00:00.0: BAR 1: assigned [mem 0x20200000-0x2020ffff]
pci 0000:00:00.0: BAR 1: set to [mem 0x20200000-0x2020ffff] (PCI address [0x20200000-0x2020ffff]
pci 0000:01:00.0: BAR 0: assigned [mem 0x20000000-0x200fffff]
pci 0000:01:00.0: BAR 0: set to [mem 0x20000000-0x200fffff] (PCI address [0x20000000-0x200fffff]
pci 0000:01:00.1: BAR 0: assigned [mem 0x20100000-0x201fffff]
pci 0000:01:00.1: BAR 0: set to [mem 0x20100000-0x201fffff] (PCI address [0x20100000-0x201fffff]
pci 0000:00:00.0: PCI bridge to [bus 01-01]
pci 0000:00:00.0:   bridge window [io  disabled]
pci 0000:00:00.0:   bridge window [mem 0x20000000-0x201fffff]
pci 0000:00:00.0:   bridge window [mem pref disabled]
BAR0 at slot 0 = 0
bus=0x0, slot = 0x0
res[0]->start = 0
res[0]->end = 0
res[1]->start = 20200000
res[1]->end = 2020ffff
res[2]->start = 0
res[2]->end = 0
res[3]->start = 0
res[3]->end = 0
res[4]->start = 0
res[4]->end = 0
res[5]->start = 0
res[5]->end = 0
bus=0x1, slot = 0x0
res[0]->start = 20000000
res[0]->end = 200fffff
res[1]->start = 0
res[1]->end = 0
res[2]->start = 0
res[2]->end = 0
res[3]->start = 0
res[3]->end = 0
res[4]->start = 0
res[4]->end = 0
res[5]->start = 0
res[5]->end = 0
bus=0x1, slot = 0x0
res[0]->start = 20100000
res[0]->end = 201fffff
res[1]->start = 0
res[1]->end = 0
res[2]->start = 0
res[2]->end = 0
res[3]->start = 0
res[3]->end = 0
res[4]->start = 0
res[4]->end = 0
res[5]->start = 0
res[5]->end = 0
Switching to clocksource Ralink external timer
NET: Registered protocol family 2
IP route cache hash table entries: 1024 (order: 0, 4096 bytes)
TCP established hash table entries: 2048 (order: 2, 16384 bytes)
TCP bind hash table entries: 2048 (order: 1, 8192 bytes)
TCP: Hash tables configured (established 2048 bind 2048)
TCP reno registered
UDP hash table entries: 256 (order: 0, 4096 bytes)
UDP-Lite hash table entries: 256 (order: 0, 4096 bytes)
NET: Registered protocol family 1
squashfs: version 4.0 (2009/01/31) Phillip Lougher
msgmni has been set to 121
Block layer SCSI generic (bsg) driver version 0.4 loaded (major 254)
io scheduler noop registered (default)
Ralink gpio driver initialized
Serial: 8250/16550 driver, 2 ports, IRQ sharing disabled
serial8250: ttyS0 at MMIO 0x10000500 (irq = 37) is a 16550A
serial8250: ttyS1 at MMIO 0x10000c00 (irq = 12) is a 16550A
brd: module loaded
deice id : c2 20 17 c2 20 (2017c220)
MX25L6405D(c2 2017c220) (8192 Kbytes)
mtd .name = raspi, .size = 0x00800000 (0M) .erasesize = 0x00000008 (0K) .numeraseregions = 65536
Creating 9 MTD partitions on "raspi":
0x000000000000-0x000000800000 : "ALL"
0x000000000000-0x000000030000 : "u-boot"
0x000000030000-0x000000040000 : "nvram"
0x000000040000-0x000000050000 : "Factory"
0x000000050000-0x000000140000 : "linux4"
0x000000140000-0x0000004e0000 : "rootfs"
0x0000004e0000-0x0000004f0000 : "LANG"
0x0000004f0000-0x0000005c0000 : "linux4b"
0x0000005c0000-0x000000800000 : "rootfsb"
rdm_major = 253
SMACCR1 -- : 0x0000000c
SMACCR0 -- : 0x43762077
Ralink APSoC Ethernet Driver Initilization. v3.0  256 rx/tx descriptors allocated, mtu = 1500!
SMACCR1 -- : 0x0000000c
SMACCR0 -- : 0x43762077
PROC INIT OK!
TCP cubic registered
NET: Registered protocol family 10
IPv6 over IPv4 tunneling driver
NET: Registered protocol family 17
VFS: Mounted root (squashfs filesystem) readonly on device 31:5.
Freeing unused kernel memory: 168k freed
init started:  BusyBox v1.01 (2014.08.22-08:26+0000) multi-call binary
Algorithmics/MIPS FPU Emulator v1.5
devpts: called with bogus options
init NVRAM_SPACE from mtdblock size
init nvram memory map size: 0x10000 order of pages: 0x4
nvram module init:
    /dev/nvram major number 225 glues to mtd: "nvram" size: 0x00010000
    nvram_space: 0x00010000 mapped via mmap(2)
openfile :/etc/sysinfo
openfile :/etc/nvram.default


BusyBox v1.01 (2014.08.22-08:26+0000) Built-in shell (ash)
Enter 'help' for a list of built-in commands.

/ # rm: cannot remove `/var/wizard_lang.js': No such file or directory
umount: cannot umount /tmp/lang_pack: No such file or directory
eth2: Cannot assign requested address
Raeth v3.0 (Tasklet,SkbRecycle)

phy_tx_ring = 0x03f4b000, tx_ring = 0xa3f4b000

phy_rx_ring0 = 0x03f4c000, rx_ring0 = 0xa3f4c000
SMACCR1 -- : 0x000054b8
SMACCR0 -- : 0x0a7d19a6
CDMA_CSG_CFG = 81000000
GDMA1_FWD_CFG = 20710000
umount: cannot umount /tmp/lang_pack: No such file or directory
mount: mounting /dev/mtdblock6 on /tmp/lang_pack failed
eth2: Cannot assign requested address
device eth2 entered promiscuous mode
TFTP main
standard_tftp_server launched on port 69.
killall: syslogd: no process killed
killall: klogd: no process killed
Sat Jan  1 00:00:00 UTC 2011
/tmp/password has been created
br0: port 1(eth2) entering forwarding state
br0: port 1(eth2) entering forwarding state
Set: phy[0].reg[0] = 3900
Set: phy[1].reg[0] = 3900
Set: phy[2].reg[0] = 3900
Set: phy[3].reg[0] = 3900
Set: phy[4].reg[0] = 3900
Set: phy[0].reg[0] = 3100
2011-01-01 00:00:00: (network.c.247) warning: please use server.use-ipv6 only for hostnames, not without server.bind / empty address; your config will break if the kernel default for IPV6_V6ONLY changes 
rt2860v2_ap: module license 'unspecified' taints kernel.
Disabling lock debugging due to kernel taint


=== pAd = c04cd000, size = 1278080 ===

<-- RTMPAllocTxRxRingMemory, Status=0
<-- RTMPAllocAdapterBlock, Status=0
AP Driver version-2.7.1.6_edcca_monitor_20131222


=== pAd = c0b02000, size = 2010752 ===

<-- RTMPAllocTxRxRingMemory, Status=0
MT76x0_WLAN_ChipOnOff(): OnOff:1, pAd->WlanFunCtrl:0x0, Reg-WlanFunCtrl=0xff000002
MACVersion = 0x76502000
RX DESC a3672000  size = 2048
RTMP_TimerListAdd: add timer obj c05a1e20!
RTMP_TimerListAdd: add timer obj c053b694!
RTMP_TimerListAdd: add timer obj c053f78c!
RTMP_TimerListAdd: add timer obj c053f84c!
RTMP_TimerListAdd: add timer obj c053f90c!
RTMP_TimerListAdd: add timer obj c053f9cc!
RTMP_TimerListAdd: add timer obj c053fa8c!
RTMP_TimerListAdd: add timer obj c053fb4c!
RTMP_TimerListAdd: add timer obj c053fc0c!
RTMP_TimerListAdd: add timer obj c053fccc!
RTMP_TimerListAdd: add timer obj c053fd8c!
RTMP_TimerListAdd: add timer obj c053fe4c!
RTMP_TimerListAdd: add timer obj c053ff0c!
RTMP_TimerListAdd: add timer obj c053ffcc!
RTMP_TimerListAdd: add timer obj c054008c!
RTMP_TimerListAdd: add timer obj c054014c!
RTMP_TimerListAdd: add timer obj c054020c!
RTMP_TimerListAdd: add timer obj c05402cc!
RTMP_TimerListAdd: add timer obj c0569e9c!
RTMP_TimerListAdd: add timer obj c056df94!
RTMP_TimerListAdd: add timer obj c056e054!
RTMP_TimerListAdd: add timer obj c056e114!
RTMP_TimerListAdd: add timer obj c056e1d4!
RTMP_TimerListAdd: add timer obj c056e294!
RTMP_TimerListAdd: add timer obj c056e354!
RTMP_TimerListAdd: add timer obj c056e414!
RTMP_TimerListAdd: add timer obj c056e4d4!
RTMP_TimerListAdd: add timer obj c056e594!
RTMP_TimerListAdd: add timer obj c056e654!
RTMP_TimerListAdd: add timer obj c056e714!
RTMP_TimerListAdd: add timer obj c056e7d4!
RTMP_TimerListAdd: add timer obj c056e894!
RTMP_TimerListAdd: add timer obj c056e954!
RTMP_TimerListAdd: add timer obj c056ea14!
RTMP_TimerListAdd: add timer obj c056ead4!
RTMP_TimerListAdd: add timer obj c053b668!
RTMP_TimerListAdd: add timer obj c053b6c0!
RTMP_TimerListAdd: add timer obj c053f760!
RTMP_TimerListAdd: add timer obj c053f820!
RTMP_TimerListAdd: add timer obj c053f8e0!
RTMP_TimerListAdd: add timer obj c053f9a0!
RTMP_TimerListAdd: add timer obj c053fa60!
RTMP_TimerListAdd: add timer obj c053fb20!
RTMP_TimerListAdd: add timer obj c053fbe0!
RTMP_TimerListAdd: add timer obj c053fca0!
RTMP_TimerListAdd: add timer obj c053fd60!
RTMP_TimerListAdd: add timer obj c053fe20!
RTMP_TimerListAdd: add timer obj c053fee0!
RTMP_TimerListAdd: add timer obj c053ffa0!
RTMP_TimerListAdd: add timer obj c0540060!
RTMP_TimerListAdd: add timer obj c0540120!
RTMP_TimerListAdd: add timer obj c05401e0!
RTMP_TimerListAdd: add timer obj c05402a0!
RTMP_TimerListAdd: add timer obj c0569e70!
RTMP_TimerListAdd: add timer obj c0569ec8!
RTMP_TimerListAdd: add timer obj c056df68!
RTMP_TimerListAdd: add timer obj c056e028!
RTMP_TimerListAdd: add timer obj c056e0e8!
RTMP_TimerListAdd: add timer obj c056e1a8!
RTMP_TimerListAdd: add timer obj c056e268!
RTMP_TimerListAdd: add timer obj c056e328!
RTMP_TimerListAdd: add timer obj c056e3e8!
RTMP_TimerListAdd: add timer obj c056e4a8!
RTMP_TimerListAdd: add timer obj c056e568!
RTMP_TimerListAdd: add timer obj c056e628!
RTMP_TimerListAdd: add timer obj c056e6e8!
RTMP_TimerListAdd: add timer obj c056e7a8!
RTMP_TimerListAdd: add timer obj c056e868!
RTMP_TimerListAdd: add timer obj c056e928!
RTMP_TimerListAdd: add timer obj c056e9e8!
RTMP_TimerListAdd: add timer obj c056eaa8!
RTMP_TimerListAdd: add timer obj c053b63c!
RTMP_TimerListAdd: add timer obj c0569e44!
RTMP_TimerListAdd: add timer obj c053f7b8!
RTMP_TimerListAdd: add timer obj c053f878!
RTMP_TimerListAdd: add timer obj c053f938!
RTMP_TimerListAdd: add timer obj c053f9f8!
RTMP_TimerListAdd: add timer obj c053fab8!
RTMP_TimerListAdd: add timer obj c053fb78!
RTMP_TimerListAdd: add timer obj c053fc38!
RTMP_TimerListAdd: add timer obj c053fcf8!
RTMP_TimerListAdd: add timer obj c053fdb8!
RTMP_TimerListAdd: add timer obj c053fe78!
RTMP_TimerListAdd: add timer obj c053ff38!
RTMP_TimerListAdd: add timer obj c053fff8!
RTMP_TimerListAdd: add timer obj c05400b8!
RTMP_TimerListAdd: add timer obj c0540178!
RTMP_TimerListAdd: add timer obj c0540238!
RTMP_TimerListAdd: add timer obj c05402f8!
RTMP_TimerListAdd: add timer obj c053b710!
RTMP_TimerListAdd: add timer obj c053b73c!
RTMP_TimerListAdd: add timer obj c053b768!
RTMP_TimerListAdd: add timer obj c056dfc0!
RTMP_TimerListAdd: add timer obj c056e080!
RTMP_TimerListAdd: add timer obj c056e140!
RTMP_TimerListAdd: add timer obj c056e200!
RTMP_TimerListAdd: add timer obj c056e2c0!
RTMP_TimerListAdd: add timer obj c056e380!
RTMP_TimerListAdd: add timer obj c056e440!
RTMP_TimerListAdd: add timer obj c056e500!
RTMP_TimerListAdd: add timer obj c056e5c0!
RTMP_TimerListAdd: add timer obj c056e680!
RTMP_TimerListAdd: add timer obj c056e740!
RTMP_TimerListAdd: add timer obj c056e800!
RTMP_TimerListAdd: add timer obj c056e8c0!
RTMP_TimerListAdd: add timer obj c056e980!
RTMP_TimerListAdd: add timer obj c056ea40!
RTMP_TimerListAdd: add timer obj c056eb00!
RTMP_TimerListAdd: add timer obj c0569f18!
RTMP_TimerListAdd: add timer obj c0569f44!
RTMP_TimerListAdd: add timer obj c0569f70!
RTMP_TimerListAdd: add timer obj c04d5014!
RTMP_TimerListAdd: add timer obj c04d4bf8!
RTMP_TimerListAdd: add timer obj c04d4fe4!
RTMP_TimerListAdd: add timer obj c04d5320!
RTMP_TimerListAdd: add timer obj c04d5260!
RTMP_TimerListAdd: add timer obj c04d5290!
RTMP_TimerListAdd: add timer obj c04d8fbc!
RTMP_TimerListAdd: add timer obj c04d8ba0!
RTMP_TimerListAdd: add timer obj c04d8f8c!
RTMP_TimerListAdd: add timer obj c04d92c8!
RTMP_TimerListAdd: add timer obj c04d9208!
RTMP_TimerListAdd: add timer obj c04d9238!
RTMP_TimerListAdd: add timer obj c04dcf64!
RTMP_TimerListAdd: add timer obj c04dcb48!
RTMP_TimerListAdd: add timer obj c04dcf34!
RTMP_TimerListAdd: add timer obj c04dd270!
RTMP_TimerListAdd: add timer obj c04dd1b0!
RTMP_TimerListAdd: add timer obj c04dd1e0!
RTMP_TimerListAdd: add timer obj c04e0f0c!
RTMP_TimerListAdd: add timer obj c04e0af0!
RTMP_TimerListAdd: add timer obj c04e0edc!
RTMP_TimerListAdd: add timer obj c04e1218!
RTMP_TimerListAdd: add timer obj c04e1158!
RTMP_TimerListAdd: add timer obj c04e1188!
RTMP_TimerListAdd: add timer obj c04e4eb4!
RTMP_TimerListAdd: add timer obj c04e4a98!
RTMP_TimerListAdd: add timer obj c04e4e84!
RTMP_TimerListAdd: add timer obj c04e51c0!
RTMP_TimerListAdd: add timer obj c04e5100!
RTMP_TimerListAdd: add timer obj c04e5130!
RTMP_TimerListAdd: add timer obj c04e8e5c!
RTMP_TimerListAdd: add timer obj c04e8a40!
RTMP_TimerListAdd: add timer obj c04e8e2c!
RTMP_TimerListAdd: add timer obj c04e9168!
RTMP_TimerListAdd: add timer obj c04e90a8!
RTMP_TimerListAdd: add timer obj c04e90d8!
RTMP_TimerListAdd: add timer obj c04ece04!
RTMP_TimerListAdd: add timer obj c04ec9e8!
RTMP_TimerListAdd: add timer obj c04ecdd4!
RTMP_TimerListAdd: add timer obj c04ed110!
RTMP_TimerListAdd: add timer obj c04ed050!
RTMP_TimerListAdd: add timer obj c04ed080!
RTMP_TimerListAdd: add timer obj c04f0dac!
RTMP_TimerListAdd: add timer obj c04f0990!
RTMP_TimerListAdd: add timer obj c04f0d7c!
RTMP_TimerListAdd: add timer obj c04f10b8!
RTMP_TimerListAdd: add timer obj c04f0ff8!
RTMP_TimerListAdd: add timer obj c04f1028!
RTMP_TimerListAdd: add timer obj c053e5ec!
RTMP_TimerListAdd: add timer obj c053e1d0!
RTMP_TimerListAdd: add timer obj c053e5bc!
RTMP_TimerListAdd: add timer obj c053e8f8!
RTMP_TimerListAdd: add timer obj c053e61c!
RTMP_TimerListAdd: add timer obj c053e64c!
RTMP_TimerListAdd: add timer obj c053e67c!
RTMP_TimerListAdd: add timer obj c056cdf4!
RTMP_TimerListAdd: add timer obj c056c9d8!
RTMP_TimerListAdd: add timer obj c056cdc4!
RTMP_TimerListAdd: add timer obj c056d100!
RTMP_TimerListAdd: add timer obj c056ce24!
RTMP_TimerListAdd: add timer obj c056ce54!
RTMP_TimerListAdd: add timer obj c056ce84!
RTMP_TimerListAdd: add timer obj c057878c!
RTMP_TimerListAdd: add timer obj c05788a8!
RTMP_TimerListAdd: add timer obj c05787b8!
RTMP_TimerListAdd: add timer obj c056fcc4!
RTMP_TimerListAdd: add timer obj c04d24c4!
RTMP_TimerListAdd: add timer obj c04d646c!
RTMP_TimerListAdd: add timer obj c04da414!
RTMP_TimerListAdd: add timer obj c04de3bc!
RTMP_TimerListAdd: add timer obj c04e2364!
RTMP_TimerListAdd: add timer obj c04e630c!
RTMP_TimerListAdd: add timer obj c04ea2b4!
RTMP_TimerListAdd: add timer obj c04ee25c!
RTMP_TimerListAdd: add timer obj c056f9d0!
APSDCapable[0]=0
APSDCapable[1]=0
APSDCapable[2]=0
APSDCapable[3]=0
APSDCapable[4]=0
APSDCapable[5]=0
APSDCapable[6]=0
APSDCapable[7]=0
APSDCapable[8]=0
APSDCapable[9]=0
APSDCapable[10]=0
APSDCapable[11]=0
APSDCapable[12]=0
APSDCapable[13]=0
APSDCapable[14]=0
APSDCapable[15]=0
default ApCliAPSDCapable[0]=0
default ApCliAPSDCapable[1]=0
start ch = 1, ch->num = 2
30 30 30 30 
30 30 30 30 30 30 30 30 
26 26 26 26 26 26 26 26 26 26 26 26 26 26 26 26 
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 
start ch = 3, ch->num = 9
30 30 30 30 
30 30 30 30 30 30 30 30 
26 26 26 26 26 26 26 26 26 26 26 26 26 26 26 26 
26 26 26 26 26 26 26 26 26 26 26 26 26 26 26 26 
start ch = 12, ch->num = 2
30 30 30 30 
30 30 30 30 30 30 30 30 
26 26 26 26 26 26 26 26 26 26 26 26 26 26 26 26 
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 
start ch = 14, ch->num = 1
30 30 30 30 
0 0 0 0 0 0 0 0 
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 
1. Phy Mode = 9
2. Phy Mode = 9
E2PROM: D0 target power=0xff20 
E2PROM: 40 MW Power Delta= 0 
3. Phy Mode = 9
AntCfgInit: primary/secondary ant 0/1
Initialize RF Central Registers for E2 !!!
Initialize RF Central Registers for E3 !!!
Initialize RF Channel Registers for E2 !!!
Initialize RF Channel Registers for E3 !!!
Initialize RF DCCal Registers for E2 !!!
Initialize RF DCCal Registers for E3 !!!
D1 = -1, D2 = 16, CalCode = 40 !!!
RT6352_Temperature_Init : BBPR49 = 0xffffffff
RT6352_Temperature_Init : TemperatureRef25C = 0xfffffff5
Current Temperature from BBP_R49=0xffffffec
RT6352_TemperatureCalibration:: CurrentTemper 
@@@ ed_monitor_init : <===
Main bssid = 54:b8:0a:7d:19:a6

@@@ ed_monitor_init : num = 1
0 0 0 0 
38 38 38 38 36 36 32 32 
38 38 38 38 36 36 32 32 38 38 38 38 36 36 32 32 
38 38 38 38 36 36 32 32 38 38 38 38 36 36 32 32 
32 32 32 32 32 32 32 32 26 26 
start ch = 38, ch->num = 1
0 0 0 0 
38 38 38 38 36 36 32 32 
38 38 38 38 36 36 32 32 38 38 38 38 36 36 32 32 
38 38 38 38 36 36 32 32 38 38 38 38 36 36 32 32 
32 32 32 32 32 32 32 32 26 26 
start ch = 40, ch->num = 1
0 0 0 0 
38 38 38 38 36 36 32 32 
38 38 38 38 36 36 32 32 38 38 38 38 36 36 32 32 
38 38 38 38 36 36 32 32 38 38 38 38 36 36 32 32 
32 32 32 32 32 32 32 32 26 26 
start ch = 42, ch->num = 1
0 0 0 0 
38 38 38 38 36 36 32 32 
38 38 38 38 36 36 32 32 38 38 38 38 36 36 32 32 
38 38 38 38 36 36 32 32 38 38 38 38 36 36 32 32 
32 32 32 32 32 32 32 32 26 26 
start ch = 44, ch->num = 1
0 0 0 0 
38 38 38 38 36 36 32 32 
38 38 38 38 36 36 32 32 38 38 38 38 36 36 32 32 
38 38 38 38 36 36 32 32 38 38 38 38 36 36 32 32 
32 32 32 32 32 32 32 32 26 26 
start ch = 46, ch->num = 1
0 0 0 0 
38 38 38 38 36 36 32 32 
38 38 38 38 36 36 32 32 38 38 38 38 36 36 32 32 
38 38 38 38 36 36 32 32 38 38 38 38 36 36 32 32 
32 32 32 32 32 32 32 32 26 26 
start ch = 48, ch->num = 1
0 0 0 0 
38 38 38 38 36 36 32 32 
38 38 38 38 36 36 32 32 38 38 38 38 36 36 32 32 
38 38 38 38 36 36 32 32 38 38 38 38 36 36 32 32 
32 32 32 32 32 32 32 32 26 26 
start ch = 52, ch->num = 1
0 0 0 0 
38 38 38 38 36 36 32 32 
38 38 38 38 36 36 32 32 38 38 38 38 36 36 32 32 
38 38 38 38 36 36 32 32 38 38 38 38 36 36 32 32 
32 32 32 32 32 32 32 32 26 26 
start ch = 54, ch->num = 1
0 0 0 0 
38 38 38 38 36 36 32 32 
38 38 38 38 36 36 32 32 38 38 38 38 36 36 32 32 
38 38 38 38 36 36 32 32 38 38 38 38 36 36 32 32 
32 32 32 32 32 32 32 32 26 26 
start ch = 56, ch->num = 1
0 0 0 0 
38 38 38 38 36 36 32 32 
38 38 38 38 36 36 32 32 38 38 38 38 36 36 32 32 
38 38 38 38 36 36 32 32 38 38 38 38 36 36 32 32 
32 32 32 32 32 32 32 32 26 26 
start ch = 58, ch->num = 1
0 0 0 0 
38 38 38 38 36 36 32 32 
38 38 38 38 36 36 32 32 38 38 38 38 36 36 32 32 
38 38 38 38 36 36 32 32 38 38 38 38 36 36 32 32 
32 32 32 32 32 32 32 32 26 26 
start ch = 60, ch->num = 1
0 0 0 0 
38 38 38 38 36 36 32 32 
38 38 38 38 36 36 32 32 38 38 38 38 36 36 32 32 
38 38 38 38 36 36 32 32 38 38 38 38 36 36 32 32 
32 32 32 32 32 32 32 32 26 26 
start ch = 62, ch->num = 1
0 0 0 0 
38 38 38 38 36 36 32 32 
38 38 38 38 36 36 32 32 38 38 38 38 36 36 32 32 
38 38 38 38 36 36 32 32 38 38 38 38 36 36 32 32 
32 32 32 32 32 32 32 32 26 26 
start ch = 64, ch->num = 1
0 0 0 0 
38 38 38 38 36 36 32 32 
38 38 38 38 36 36 32 32 38 38 38 38 36 36 32 32 
38 38 38 38 36 36 32 32 38 38 38 38 36 36 32 32 
32 32 32 32 32 32 32 32 26 26 
start ch = 100, ch->num = 1
0 0 0 0 
38 38 38 38 36 36 32 32 
38 38 38 38 36 36 32 32 38 38 38 38 36 36 32 32 
38 38 38 38 36 36 32 32 38 38 38 38 36 36 32 32 
32 32 32 32 32 32 32 32 26 26 
start ch = 102, ch->num = 1
0 0 0 0 
38 38 38 38 36 36 32 32 
38 38 38 38 36 36 32 32 38 38 38 38 36 36 32 32 
38 38 38 38 36 36 32 32 38 38 38 38 36 36 32 32 
32 32 32 32 32 32 32 32 26 26 
start ch = 104, ch->num = 1
0 0 0 0 
38 38 38 38 36 36 32 32 
38 38 38 38 36 36 32 32 38 38 38 38 36 36 32 32 
38 38 38 38 36 36 32 32 38 38 38 38 36 36 32 32 
32 32 32 32 32 32 32 32 26 26 
start ch = 106, ch->num = 1
0 0 0 0 
38 38 38 38 36 36 32 32 
38 38 38 38 36 36 32 32 38 38 38 38 36 36 32 32 
38 38 38 38 36 36 32 32 38 38 38 38 36 36 32 32 
32 32 32 32 32 32 32 32 26 26 
start ch = 108, ch->num = 1
0 0 0 0 
38 38 38 38 36 36 32 32 
38 38 38 38 36 36 32 32 38 38 38 38 36 36 32 32 
38 38 38 38 36 36 32 32 38 38 38 38 36 36 32 32 
32 32 32 32 32 32 32 32 26 26 
start ch = 110, ch->num = 1
0 0 0 0 
38 38 38 38 36 36 32 32 
38 38 38 38 36 36 32 32 38 38 38 38 36 36 32 32 
38 38 38 38 36 36 32 32 38 38 38 38 36 36 32 32 
32 32 32 32 32 32 32 32 26 26 
start ch = 112, ch->num = 1
0 0 0 0 
38 38 38 38 36 36 32 32 
38 38 38 38 36 36 32 32 38 38 38 38 36 36 32 32 
38 38 38 38 36 36 32 32 38 38 38 38 36 36 32 32 
32 32 32 32 32 32 32 32 26 26 
start ch = 116, ch->num = 1
0 0 0 0 
38 38 38 38 36 36 32 32 
38 38 38 38 36 36 32 32 38 38 38 38 36 36 32 32 
38 38 38 38 36 36 32 32 38 38 38 38 36 36 32 32 
32 32 32 32 32 32 32 32 26 26 
start ch = 118, ch->num = 1
0 0 0 0 
38 38 38 38 36 36 32 32 
38 38 38 38 36 36 32 32 38 38 38 38 36 36 32 32 
38 38 38 38 36 36 32 32 38 38 38 38 36 36 32 32 
32 32 32 32 32 32 32 32 26 26 
start ch = 120, ch->num = 1
0 0 0 0 
38 38 38 38 36 36 32 32 
38 38 38 38 36 36 32 32 38 38 38 38 36 36 32 32 
38 38 38 38 36 36 32 32 38 38 38 38 36 36 32 32 
32 32 32 32 32 32 32 32 26 26 
start ch = 122, ch->num = 1
0 0 0 0 
38 38 38 38 36 36 32 32 
38 38 38 38 36 36 32 32 38 38 38 38 36 36 32 32 
38 38 38 38 36 36 32 32 38 38 38 38 36 36 32 32 
32 32 32 32 32 32 32 32 26 26 
start ch = 124, ch->num = 1
0 0 0 0 
38 38 38 38 36 36 32 32 
38 38 38 38 36 36 32 32 38 38 38 38 36 36 32 32 
38 38 38 38 36 36 32 32 38 38 38 38 36 36 32 32 
32 32 32 32 32 32 32 32 26 26 
start ch = 126, ch->num = 1
0 0 0 0 
38 38 38 38 36 36 32 32 
38 38 38 38 36 36 32 32 38 38 38 38 36 36 32 32 
38 38 38 38 36 36 32 32 38 38 38 38 36 36 32 32 
32 32 32 32 32 32 32 32 26 26 
start ch = 128, ch->num = 1
0 0 0 0 
38 38 38 38 36 36 32 32 
38 38 38 38 36 36 32 32 38 38 38 38 36 36 32 32 
38 38 38 38 36 36 32 32 38 38 38 38 36 36 32 32 
32 32 32 32 32 32 32 32 26 26 
start ch = 132, ch->num = 1
0 0 0 0 
38 38 38 38 36 36 32 32 
38 38 38 38 36 36 32 32 38 38 38 38 36 36 32 32 
38 38 38 38 36 36 32 32 38 38 38 38 36 36 32 32 
32 32 32 32 32 32 32 32 26 26 
start ch = 134, ch->num = 1
0 0 0 0 
38 38 38 38 36 36 32 32 
38 38 38 38 36 36 32 32 38 38 38 38 36 36 32 32 
38 38 38 38 36 36 32 32 38 38 38 38 36 36 32 32 
32 32 32 32 32 32 32 32 26 26 
start ch = 136, ch->num = 1
0 0 0 0 
38 38 38 38 36 36 32 32 
38 38 38 38 36 36 32 32 38 38 38 38 36 36 32 32 
38 38 38 38 36 36 32 32 38 38 38 38 36 36 32 32 
32 32 32 32 32 32 32 32 26 26 
start ch = 140, ch->num = 1
0 0 0 0 
38 38 38 38 36 36 32 32 
38 38 38 38 36 36 32 32 38 38 38 38 36 36 32 32 
38 38 38 38 36 36 32 32 38 38 38 38 36 36 32 32 
32 32 32 32 32 32 32 32 26 26 
start ch = 149, ch->num = 1
0 0 0 0 
38 38 38 38 36 36 32 32 
38 38 38 38 36 36 32 32 38 38 38 38 36 36 32 32 
38 38 38 38 36 36 32 32 38 38 38 38 36 36 32 32 
32 32 32 32 32 32 32 32 26 26 
start ch = 151, ch->num = 1
0 0 0 0 
38 38 38 38 36 36 32 32 
38 38 38 38 36 36 32 32 38 38 38 38 36 36 32 32 
38 38 38 38 36 36 32 32 38 38 38 38 36 36 32 32 
32 32 32 32 32 32 32 32 26 26 
start ch = 153, ch->num = 1
0 0 0 0 
38 38 38 38 36 36 32 32 
38 38 38 38 36 36 32 32 38 38 38 38 36 36 32 32 
38 38 38 38 36 36 32 32 38 38 38 38 36 36 32 32 
32 32 32 32 32 32 32 32 26 26 
start ch = 155, ch->num = 1
0 0 0 0 
38 38 38 38 36 36 32 32 
38 38 38 38 36 36 32 32 38 38 38 38 36 36 32 32 
38 38 38 38 36 36 32 32 38 38 38 38 36 36 32 32 
32 32 32 32 32 32 32 32 26 26 
start ch = 157, ch->num = 1
0 0 0 0 
38 38 38 38 36 36 32 32 
38 38 38 38 36 36 32 32 38 38 38 38 36 36 32 32 
38 38 38 38 36 36 32 32 38 38 38 38 36 36 32 32 
32 32 32 32 32 32 32 32 26 26 
start ch = 159, ch->num = 1
0 0 0 0 
38 38 38 38 36 36 32 32 
38 38 38 38 36 36 32 32 38 38 38 38 36 36 32 32 
38 38 38 38 36 36 32 32 38 38 38 38 36 36 32 32 
32 32 32 32 32 32 32 32 26 26 
start ch = 161, ch->num = 1
0 0 0 0 
38 38 38 38 36 36 32 32 
38 38 38 38 36 36 32 32 38 38 38 38 36 36 32 32 
38 38 38 38 36 36 32 32 38 38 38 38 36 36 32 32 
32 32 32 32 32 32 32 32 26 26 
start ch = 165, ch->num = 1
0 0 0 0 
38 38 38 38 36 36 32 32 
38 38 38 38 36 36 32 32 38 38 38 38 36 36 32 32 
38 38 38 38 36 36 32 32 38 38 38 38 36 36 32 32 
32 32 32 32 32 32 32 32 26 26 
start ch = 169, ch->num = 1
0 0 0 0 
38 38 38 38 36 36 32 32 
38 38 38 38 36 36 32 32 38 38 38 38 36 36 32 32 
38 38 38 38 36 36 32 32 38 38 38 38 36 36 32 32 
32 32 32 32 32 32 32 32 26 26 
start ch = 173, ch->num = 1
0 0 0 0 
38 38 38 38 36 36 32 32 
38 38 38 38 36 36 32 32 38 38 38 38 36 36 32 32 
38 38 38 38 36 36 32 32 38 38 38 38 36 36 32 32 
32 32 32 32 32 32 32 32 26 26 
1. Phy Mode = 49
2. Phy Mode = 49
ext_pa_current_setting = 1
3. Phy Mode = 49
AntCfgInit: primary/secondary ant 0/1
ChipStructAssign(): RALINK6590 hook !
MCS Set = ff 00 00 00 01
MT76x0_ChipBBPAdjust():rf_bw=2, ext_ch=1, PrimCh=36, HT-CentCh=38, VHT-CentCh=42
MT76x0_ChipSwitchChannel: DefaultTargetPwr = 30
APStartUp(): AP Set CentralFreq at 42(Prim=36, HT-CentCh=38, VHT-CentCh=42, BBP_BW=2)
Main bssid = 54:b8:0a:7d:19:a8
<==== rt28xx_init, Status=0
MT76x0_ChipSwitchChannel: DefaultTargetPwr = 30
MT76x0_ChipSwitchChannel: DefaultTargetPwr = 30
MT76x0_ChipSwitchChannel: DefaultTargetPwr = 30
MT76x0_ChipSwitchChannel: DefaultTargetPwr = 30
MT76x0_ChipSwitchChannel: DefaultTargetPwr = 30
MT76x0_ChipSwitchChannel: DefaultTargetPwr = 30
MT76x0_ChipSwitchChannel: DefaultTargetPwr = 30
MT76x0_ChipSwitchChannel: DefaultTargetPwr = 30
MT76x0_ChipSwitchChannel: DefaultTargetPwr = 30
MT76x0_ChipSwitchChannel: DefaultTargetPwr = 30
MT76x0_ChipSwitchChannel: DefaultTargetPwr = 30
MT76x0_ChipSwitchChannel: DefaultTargetPwr = 30
MT76x0_ChipSwitchChannel: DefaultTargetPwr = 30
RT6352_TemperatureCalibration:: CurrentTemper < 20 
MT76x0_ChipSwitchChannel: DefaultTargetPwr = 30
MT76x0_ChipSwitchChannel: DefaultTargetPwr = 30
MT76x0_ChipSwitchChannel: DefaultTargetPwr = 30
MT76x0_ChipSwitchChannel: DefaultTargetPwr = 30
MT76x0_ChipSwitchChannel: DefaultTargetPwr = 30
MT76x0_ChipSwitchChannel: DefaultTargetPwr = 30
MT76x0_ChipSwitchChannel: DefaultTargetPwr = 30
MT76x0_ChipSwitchChannel: DefaultTargetPwr = 30
MT76x0_ChipSwitchChannel: DefaultTargetPwr = 30
MT76x0_ChipSwitchChannel: DefaultTargetPwr = 30
MT76x0_ChipBBPAdjust():rf_bw=2, ext_ch=1, PrimCh=44, HT-CentCh=46, VHT-CentCh=42
MT76x0_ChipSwitchChannel: DefaultTargetPwr = 30
APStartUp(): AP Set CentralFreq at 42(Prim=44, HT-CentCh=46, VHT-CentCh=42, BBP_BW=2)
0x1300 = 00064380
RTMPDrvOpen(1):Check if PDMA is idle!
RTMPDrvOpen(2):Check if PDMA is idle!
device rai0 entered promiscuous mode
br0: port 4(rai0) entering forwarding state
br0: port 4(rai0) entering forwarding state
device apclii0 entered promiscuous mode
br0: port 5(apclii0) entering forwarding state
br0: port 5(apclii0) entering forwarding state
Interface doesn't accept private ioctl...
set (8BE2): Invalid argument
killall: udhcpc: no process killed
SIOCSIFFLAGS: Cannot assign requested address
rm: cannot remove `/var/tmp/previous_dn': No such file or directory
rm: cannot remove `/var/tmp/previous_dns': No such file or directory
rm: cannot remove `/var/tmp/m_flag': No such file or directory
rm: cannot remove `/var/tmp/o_flag': No such file or directory
RTNETLINK answers: No such file or directory
cat: /var/etc/resolv.conf: No such file or directory
sh: cannot create /proc/sys/net/ipv6/conf/br0/disable_ipv6: Directory nonexistent
Start IPv6 dhclient
Sat Jan  1 00:00:00 UTC 2011
rdnssd is already active !
RT6352_TemperatureCalibration:: CurrentTemper < 20 
Start IPv6 dhclient
DHCP server start.
device_lan_ip=192.168.0.50 , device_lan_subnet_mask=255.255.255.0
max_leases value (254) not sane, setting to 20 instead
Unable to open /var/misc/udhcpd.leases for reading
llmnr: have no available linklocal address. wait count=0
/tmp/password has been created
2011-01-01 00:00:00: (network.c.247) warning: please use server.use-ipv6 only for hostnames, not without server.bind / empty address; your config will break if the kernel default for IPV6_V6ONLY changes 
Failed to kill daemon: No such file or directory
Daemon already running on PID 315
RT6352_TemperatureCalibration:: CurrentTemper < 20 
RT6352_TemperatureCalibration:: CurrentTemper < 20 
RT6352_TemperatureCalibration:: CurrentTemper < 20

    Warning: Do not attempt to modify the firmware of this device if you do not have hardware to rewrite the firmware to the SPI flash. Before I even powered up the device the first time, I took a dump of the SPI flash in case I ended up “bricking” the device (which I did, many times).

    You can build your own SPI flash reader/writer with a Teensy and a chip clip. I am using the work of Trammell Hudson who gave an awesome talk at 31C3 on manipulating UEFI on MacBook Pros for fun and profit.

    You can find a copy of the SPI dump of my device (firmware 1.05) here. You cannot flash this image without hardware tools as described above. If you flash this dump, your device will have the same MAC address as mine. This dump should be used only as an option of last resort.

    Poking around the D-Link firmware for vulnerabilities

    I would love to say that I’m an infosec god, and that I can hack anything that moves. Really though, I’m not. I tried to find exploits for D-Link, and it doesn’t seem that there is any shortage of HNAP exploits and other nasty things, but I was unable to get the device to do any interesting things for me, like start a telnet server.

    Disassembling the firmware to learn more about installed software

    Since my Google-fu is weak, I couldn’t find the firmware images for this device on D-Link’s website at first, so I just disassembled the firmware I dumped from the MXIC.

    $ binwalk dlink-dap1520.bin 

DECIMAL       HEXADECIMAL     DESCRIPTION
--------------------------------------------------------------------------------
99968         0x18680         U-Boot version string, "U-Boot 1.1.3 (Aug  8 2013 - 10:32:46)"
100732        0x1897C         HTML document header
101832        0x18DC8         HTML document footer
101954        0x18E42         HTML document header
102754        0x19162         HTML document footer
102878        0x191DE         HTML document header
105248        0x19B20         HTML document footer
105367        0x19B97         HTML document header
106050        0x19E42         HTML document footer
106174        0x19EBE         HTML document header
106255        0x19F0F         HTML document footer
196962        0x30162         Unix path: /01/01/00/00/00
327680        0x50000         uImage header, header size: 64 bytes, header CRC: 0xC9616E23, created: 2014-08-22 08:41:24, image size: 909208 bytes, Data Address: 0x80000000, Entry Point: 0x8000C310, data CRC: 0x895D3AE, OS: Linux, CPU: MIPS, image type: OS Kernel Image, compression type: lzma, image name: "Linux Kernel Image"
327744        0x50040         LZMA compressed data, properties: 0x5D, dictionary size: 33554432 bytes, uncompressed size: 2798288 bytes
1310720       0x140000        Squashfs filesystem, little endian, version 4.0, compression:xz, size: 3459080 bytes, 649 inodes, blocksize: 65536 bytes, created: 2014-08-22 08:41:35
5177344       0x4F0000        uImage header, header size: 64 bytes, header CRC: 0x225D8E97, created: 2013-09-26 08:58:51, image size: 829684 bytes, Data Address: 0x80000000, Entry Point: 0x8000C310, data CRC: 0xA98529B2, OS: Linux, CPU: MIPS, image type: OS Kernel Image, compression type: lzma, image name: "Linux Kernel Image"
5177408       0x4F0040        LZMA compressed data, properties: 0x5D, dictionary size: 33554432 bytes, uncompressed size: 2544052 bytes
6029312       0x5C0000        Squashfs filesystem, little endian, version 4.0, compression:xz, size: 2192260 bytes, 345 inodes, blocksize: 65536 bytes, created: 2013-09-26 08:59:04

    Something interesting, there are two Squashfs filesystems on this device. This makes some sense, given what we saw earlier in the uboot logs:

    Check image validation:
Image1 Header Magic Number --> OK
Image2 Header Magic Number --> OK
Image1 Header Checksum --> OK
Image2 Header Checksum --> OK
Image1 Data Checksum --> raspi_read: from:50040 len:ddf98 
OK
Image2 Data Checksum --> raspi_read: from:4f0040 len:ca8f4 
OK
Image1 Stable Flag --> Not stable
Image1 Try Counter --> 0

Image1: OK Image2: OK
Both images are OK!!!

    Using dd, we can extract both Squashfs images from the firmware file. I used my dump, but actually I would recommend you just head over to D-Link's website and download the 1.06 firmware image [ZIP] and dump that instead. However, D-Link's firmware is missing the second Squashfs filesystem.

    Squashfs #1

    $ dd if=dlink-dap1520.bin of=squashfs1.bin bs=1 skip=1310720

    Squashfs #2

    $ dd if=dlink-dap1520.bin of=squashfs2.bin bs=1 skip=6029312

    Run the 'ol unsquashfs on squashfs1.bin and squashfs2.bin, and you'll have the extracted filesystems of the squashfs images in my dump the firmware. Remember to rename the directory squashfs-root between runs, or specify unsquashfs -d with a different directory name to decompress the images into respective directories.

    If you're using the D-Link firmware from their website, the dd command is a bit different due to offsets and all:

    $ binwalk DAP1520A1_FW106B04.bin

DECIMAL       HEXADECIMAL     DESCRIPTION
--------------------------------------------------------------------------------
0             0x0             uImage header, header size: 64 bytes, header CRC: 0xBA3B64BA, created: 2015-01-22 03:48:48, image size: 909200 bytes, Data Address: 0x80000000, Entry Point: 0x8000C310, data CRC: 0x310BA125, OS: Linux, CPU: MIPS, image type: OS Kernel Image, compression type: lzma, image name: "Linux Kernel Image"
64            0x40            LZMA compressed data, properties: 0x5D, dictionary size: 33554432 bytes, uncompressed size: 2798288 bytes
983040        0xF0000         Squashfs filesystem, little endian, version 4.0, compression:xz, size: 3460300 bytes, 649 inodes, blocksize: 65536 bytes, created: 2015-01-22 03:48:54
    $ dd if=DAP1520A1_FW106B04.bin of=dlink106.bin bs=1 skip=983040

    Now unsquashfs that, and you'll have firmware 1.06 from D-Link.

    I'm going to leave investigation of the individual files in the firmware to the reader, but I'd like to state some facts I learned while investigating the firmware:

  • There are two copies of busybox on the firmware, versions 1.01 and 1.6.1. Some programs in /bin are linked to 1.01 and others to 1.6.1. I have no idea why D-Link would do this.
  • Pretty much everything on the device is run from /bin/cli and /bin/ssi. Other people on the web have analyzed these binaries and can tell you what they do (and how insecure they are).

    • The second squashfs image is the D-Link recovery OS. This OS will boot if the first kernel fails the integrity check performed in uboot. Hilariously, it won't boot into the recovery environment if you flash a bad kernel to the device in Image 1 as I found out.

    You might have noticed the flash layout from the binwalk of the firmware dump I made, but here is the actual firmware layout as reported by Linux:

    0x000000000000-0x000000800000 : "ALL"
0x000000000000-0x000000030000 : "u-boot"
0x000000030000-0x000000040000 : "nvram"
0x000000040000-0x000000050000 : "Factory"
0x000000050000-0x000000140000 : "linux4"
0x000000140000-0x0000004e0000 : "rootfs"
0x0000004e0000-0x0000004f0000 : "LANG"
0x0000004f0000-0x0000005c0000 : "linux4b"
0x0000005c0000-0x000000800000 : "rootfsb"

    To summarize:
    ALL: This spans from 0x000000 to 0x800000 which is the entire 8MB of the MXIC chip
    u-boot: u-boot loader
    nvram: Storage space for configuration variables. More on this in part 2
    Factory: No idea.
    linux4: This is the primary kernel on the device, and the one that will boot if your device has a valid Image 1. This is the firmware that you download from D-Link's website. Despite the label, it is not Linux 4.x, but 2.6.36.
    rootfs: Squashfs compressed filesystem of the primary OS (Image 1)
    LANG: No idea.
    linux4b: Recovery kernel. This kernel will be booted if Image 1 kernel fails verification.
    rootfsb: Squashfs compressed recovery filesystem. This, along with linux4b boot if Image 1 is corrupt and allow you to flash a firmware through the web interface to restore the device.

    I must say that the inclusion of a recovery OS is an interesting move on D-Link's part. Since I don't buy their products normally, I'm not sure if other D-Link devices also have this recovery OS on them. It seems like a good idea to include on this device, since if a firmware update fails, since there are no Ethernet ports on the device it's not possible to recover via TFTP, as it would be on a normal router. The firmware update from D-Link's website only updates Image 1 squashfs and kernel. Image 2 on my device is firmware version 1.00, and the squashfs filesystem is smaller than the Image 1 OS.

    If you do some maths on the mtd blocks, you will see that with the stock D-Link layout, the Image 1 kernel can only be 983040 bytes (0xF0000) large. Any larger, and the kernel will not fit in flash. The recovery kernel has to be even smaller, maximum 851968 bytes (0xD0000).

    Since this device lacks Ethernet ports, it doesn't include some of the features one would consider necessary on a home router, such as port forwarding, firewall configuration, and the like. I suspect that not needing to include these features gave D-Link the space on flash to store a recovery OS. As you can see though, they did have to make some compromises in the allocation of flash to fit the main and recovery OS within 8MB. The device does not function as a WiFi repeater in the recovery OS, only allowing you to reflash a firmware.

    As much as I would love to cram all of what I did into one post, this is getting long already.

    Stay tuned for part 2 where I compile the D-Link GPL firmware from source and backdoor the device to allow shell access without a login (infosec is hard). If you've heard horror stories about GPL firmwares before, they're all true...

    Come back soon!

    Build and package your own software for OpenWRT

    8 Replies

    Today I am going to discuss how to build and package your own software for OpenWRT.

    When I say “your own software” in this case I am referring to a C program which you want to cross-compile for the target SoC and install using the opkg package manager included in OpenWRT.

    The program I wrote is a little more complicated than your standard “Hello World” application. Here’s what I wanted to do:
    1) use libconfig to read a configuration file in /etc/config/ and then perform actions based on the configuration described in this file
    2) use sqlite3 to create a database
    3) write some meaningful data to the database

    Here’s the program flow:
    1) Open /etc/config/example-sqlite and read the values into variables
    2) Open (or create) a new SQLite3 database file at the location defined in the above configuration file
    3) Determine if the SQLite file is initialized with the target table we want to write to, and if not, create the table
    4) Write the system load average to the database
    5) Quit

    To recap, this program is different from “Hello World” in the following ways:
    1) It must read and understand a configuration file in libconfig syntax; this requires linking against the libconfig library, which we must tell opkg is a dependency
    2) It must create or open an SQLite 3 database; this requires linking against the sqlite3 library, which we must tell opkg is a depenedency
    3) It must perform some useful operations on this SQLite file

    Let’s start with compiling the C file on your native architecture. Sure, you can just use cc/gcc from bash, but this isn’t any good to OpenWRT SDK, which expects that each package will have a makefile which can be used to compile the software.

    load2sqlite.c

    #include <sys/types.h>
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <sqlite3.h>
#include <libconfig.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <errno.h>

int main(int argc, char *argv[]) {
// ...

    Most importantly above, we are including sqlite3.h for SQLite support, libconfig.h, and sys/stat.h, fcntl.h,errno.h to check if the SQLite3 database file exists or not.

    You can compile this by hand quite easily, just by doing:
    cc load2sqlite.c -lsqlite3 -lconfig -o load2sqlite

    Okay, but how do we make this ready for OpenWRT SDK? By writing a makefile!

    makefile

    PROFILE = -O2 -s
CFLAGS = $(PROFILE)
LDFLAGS = -lsqlite3 -lconfig

all: main

# build it
main:
	$(CC) $(CFLAGS) load2sqlite.c $(LDFLAGS) -o load2sqlite

# clean it
clean:
	rm load2sqlite

    Okay, so now if you type make in the directory, magically you will end up with an executable called load2sqlite!

    But, this is a native binary, and it’s somewhat unlikely that your OpenWRT device is on the same architecture.

    load2sqlite: ELF 64-bit LSB executable, x86-64, version 1 (SYSV), dynamically linked, interpreter /lib64/ld-linux-x86-64.so.2, for GNU/Linux 2.6.32, BuildID[sha1]=9661b88e92b553d0556cbeeafccf04d2526c770f, stripped

    If you run it, you’ll see that it looks for the sqlite database file, can’t find it, and so initalizes a new one with the “readings” table.

    [hmartin@localhost src]$ ./load2sqlite 
Database file /tmp/sqlite3.db does not exist
Initialized database with readings table
[hmartin@localhost src]$ echo "select * from readings;" | sqlite3 /tmp/sqlite3.db 
2015-10-28 22:48:42|0.57|0.56|0.57

    And if you run it again, without removing the SQLite3 file that was created, you’ll see this output:

    [hmartin@localhost src]$ ./load2sqlite
SQLite database opened
Found readings table
[hmartin@localhost src]$ echo "select * from readings;" | sqlite3 /tmp/sqlite3.db 
2015-10-28 22:48:42|0.57|0.56|0.57
2015-10-28 22:49:00|0.47|0.54|0.57

    Before we proceed further, I want to show you the directory structure so you have an idea of where we just were when we did this compilation. We are currently in the the src directory.

    load2sqlite/
|-- Makefile
|-- README
`-- src
    |-- load2sqlite.c
    |-- load2sqlite.conf
    `-- makefile

    Now let’s move up to the load2sqlite directory and work on the OpenWRT Makefile (seen above).

    Here is the complete file, and then we will discuss it section by section:
    Makefile

    #
# Copyright (C) 2006-2015 OpenWrt.org
#
# This is free software, licensed under the GNU General Public License v2.
# See /LICENSE for more information.
#

include $(TOPDIR)/rules.mk

PKG_NAME:=load2sqlite
PKG_VERSION:=1.0.1
PKG_RELEASE:=5
PKG_MAINTAINER:=Hal Martin 
PKG_LICENSE:=GPL-2
PKG_CONFIG_DEPENDS:=libsqlite3 libconfig

include $(INCLUDE_DIR)/package.mk

PKG_BUILD_DIR := $(BUILD_DIR)/$(PKG_NAME)-$(PKG_VERSION)

TARGET_LDFLAGS+= \
  -Wl,-rpath-link=$(STAGING_DIR)/usr/lib \
  -Wl,-rpath-link=$(STAGING_DIR)/usr/lib/libconfig/lib \
  -Wl,-rpath-link=$(STAGING_DIR)/usr/lib/sqlite/lib

define Package/load2sqlite
  SECTION:=utils
  CATEGORY:=Utilities
  DEPENDS:=+libsqlite3 +libconfig
  TITLE:=SQLite example program, creates or opens a user defined SQLite database
  URL:=https://github.com/halmartin/load2sqlite
  MENU:=1
endef

define Package/load2sqlite/description
 Example SQLite is a sample program built using libsqlite3 and libconfig
 which creates or opens a user-defined SQLite3 database and performs some
 simple verification checks on the file to ensure that the target table (readings)
 exists, and if not creates the table, then inserts a row with the current system
 time, and the load (1 minute, 5 minute, 15 minute).
endef

define Build/Prepare
	mkdir -p $(PKG_BUILD_DIR)
	$(CP) ./src/* $(PKG_BUILD_DIR)/
endef

define Build/Configure
endef

define Build/Compile
	$(MAKE) -C $(PKG_BUILD_DIR) $(TARGET_CONFIGURE_OPTS)
endef

define Package/load2sqlite/install
	$(INSTALL_DIR) $(1)/bin
	$(INSTALL_BIN) $(PKG_BUILD_DIR)/load2sqlite $(1)/bin/
	$(INSTALL_DIR) $(1)/etc/config
	$(INSTALL_CONF) $(PKG_BUILD_DIR)/load2sqlite.conf $(1)/etc/config/load2sqlite
endef

$(eval $(call BuildPackage,load2sqlite))

    If you clone the OpenWRT source and take a look at basically any package, you’ll see a Makefile that looks similar to the one above.

    Let’s look at the package information:

    PKG_NAME:=load2sqlite
PKG_VERSION:=1.0.1
PKG_RELEASE:=5
PKG_MAINTAINER:=Hal Martin 
PKG_LICENSE:=GPL-2

    Here is where we define core details of our package, such as the name (e.g. what opkg will know it as), the version (useful for upgrading later), maintainer, and license.

    TARGET_LDFLAGS+= \
  -Wl,-rpath-link=$(STAGING_DIR)/usr/lib \
  -Wl,-rpath-link=$(STAGING_DIR)/usr/lib/libconfig/lib \
  -Wl,-rpath-link=$(STAGING_DIR)/usr/lib/sqlite/lib

    Since we want to build a program which links against external libraries, we must also tell the compiler where to find the header files for these libraries, so that the linking process does not fail during compilation. Above you can see that we are linking to libconfig and sqlite libraries.

    define Package/load2sqlite
  SECTION:=utils
  CATEGORY:=Utilities
  DEPENDS:=+libsqlite3 +libconfig
  TITLE:=SQLite example program, creates or opens a user defined SQLite database
  URL:=https://github.com/halmartin/load2sqlite
  MENU:=1
endef

    This is where you define the package for the OpenWRT build system and declare things like dependencies, and the description that will be present when you run menuconfig (which is how you will select your package to be built as part of an image).

    Without declaring dependencies, you may find that you can build, package, and install your software, but it won’t run! So, by declaring the dependencies (packages which provide the libraries we link against) we ensure that when we type opkg install load2sqlite and libconfig and libsqlite3 are not installed, opkg knows to go and install them before installing our program. Now we can safely run the program because all the required libraries are installed on the device! 

    define Build/Prepare
	mkdir -p $(PKG_BUILD_DIR)
	$(CP) ./src/* $(PKG_BUILD_DIR)/
endef

define Build/Configure
endef

    Since our utility is quite simple, as *NIX software goes, the preparation steps are to create the build directory and copy the source from the source directory to the build directory. Since there is nothing to configure in our sample program, the configure step is empty (otherwise the OpenWRT build system will attempt to configure the package and fail because we haven’t bothered to implement this).

    define Build/Compile
	$(MAKE) -C $(PKG_BUILD_DIR) $(TARGET_CONFIGURE_OPTS)
endef

define Package/load2sqlite/install
	$(INSTALL_DIR) $(1)/bin
	$(INSTALL_BIN) $(PKG_BUILD_DIR)/load2sqlite $(1)/bin/
	$(INSTALL_DIR) $(1)/etc/config
	$(INSTALL_CONF) $(PKG_BUILD_DIR)/load2sqlite.conf $(1)/etc/config/load2sqlite
endef

    Finally, compile and install the software. As you can see above, I didn’t include an install directive in the makefile of the application, it is instead done manually within the OpenWRT Makefile. This is your choice, since I was designing this program specifically to run on OpenWRT, I saw no need to incorporate the installation steps in the makefile of the program.

    And, finally:

    $(eval $(call BuildPackage,load2sqlite))

    This line is required for OpenWRT to build the package. Forget this line, and you will sit there wondering why your package is not being built!

    Okay, now we have prepared our software to be built for OpenWRT. It would be stupid of me to get this far and not tell you how to compile it using the OpenWRT toolchain!

    Following the excellent OpenWRT documentation, we need to set up a buildroot.

    Install the dependencies (instructions for Debian/Ubuntu):

    sudo apt-get install git-core build-essential libssl-dev libncurses5-dev unzip subversion mercurial

    Clone the OpenWRT Chaos Calmer release:

    git clone git://git.openwrt.org/15.05/openwrt.git

    I find that the stock OpenWRT repository is a bit light on some of the software I like to have on my routers, so I take step 3 and install the additional feeds:

    cd openwrt
./scripts/feeds update -a
./scripts/feeds install -a

    Follow step 4 to ensure you have all the required dependencies installed on your host system!

    make defconfig
make prereq
# don't forget to copy load2sqlite to package/utils/ before running this step, or the package won't appear in the menu!
make menuconfig

    If everything has gone well thus far (e.g. no errors in the OpenWRT Makefile, and you put load2sqlite in package/utils/ then you should see the following in your menuconfig:

    menuconfig_load2sqlite

    menuconfig_load2sqlite_desc

    Now I already have an official OpenWRT build installed on my router, so I don’t need to build an entire image, just the package I want to install. To do this, we must first build the cross compilation toolchain required to compile for a different CPU architecture.

    Warning: the OpenWRT buildroot is around 6GB on disk, so ensure you have the necessary space before starting!

    make tools/install
# this will take a while the first time
make toolchain/install
# this will also take a while the first time

    When we have the tools and toolchain compiled, we can compile our package:

    make package/load2sqlite/compile

    This will create an ipkg file in bin/ramips/packages/base/load2sqlite_1.0.1-5_ramips_24kec.ipk which we need to copy to our router to install:

    scp bin/ramips/packages/base/load2sqlite_1.0.1-5_ramips_24kec.ipk [email protected]:/tmp/
# scp completes
ssh [email protected]
[email protected]'s password:

BusyBox v1.23.2 (2015-07-25 03:03:02 CEST) built-in shell (ash)

  _______                     ________        __
 |       |.-----.-----.-----.|  |  |  |.----.|  |_
 |   -   ||  _  |  -__|     ||  |  |  ||   _||   _|
 |_______||   __|_____|__|__||________||__|  |____|
          |__| W I R E L E S S   F R E E D O M
 -----------------------------------------------------
 CHAOS CALMER (15.05, r46767)
 -----------------------------------------------------
  * 1 1/2 oz Gin            Shake with a glassful
  * 1/4 oz Triple Sec       of broken ice and pour
  * 3/4 oz Lime Juice       unstrained into a goblet.
  * 1 1/2 oz Orange Juice
  * 1 tsp. Grenadine Syrup
 -----------------------------------------------------
root@OpenWrt:~# opkg install /tmp/load2sqlite_1.0.1-5_ramips_24kec.ipk 
Installing load2sqlite (1.0.1-4) to root...
Installing libsqlite3 (3081101-1) to root...
Downloading http://downloads.openwrt.org/chaos_calmer/15.05/ramips/mt7620/packages/packages/libsqlite3_3081101-1_ramips_24kec.ipk.
Installing libpthread (0.9.33.2-1) to root...
Downloading http://downloads.openwrt.org/chaos_calmer/15.05/ramips/mt7620/packages/base/libpthread_0.9.33.2-1_ramips_24kec.ipk.
Installing libconfig (1.4.9-1) to root...
Downloading http://downloads.openwrt.org/chaos_calmer/15.05/ramips/mt7620/packages/base/libconfig_1.4.9-1_ramips_24kec.ipk.
Configuring libpthread.
Configuring libconfig.
Configuring libsqlite3.
Configuring load2sqlite.

    Now that our package is installed, we can test it!

    root@OpenWrt:~# /bin/load2sqlite 
Database file /tmp/sqlite3.db does not exist
Initialized database with readings table

    If you install sqlite3-cli we can inspect the row added to the file:

    root@OpenWrt:~# opkg install sqlite3-cli
root@OpenWrt:~# echo "select * from readings;" | sqlite3 /tmp/sqlite3.db 
2015-10-31 20:47:33|0.76|0.4|0.25

    Since this is just an example program, it is one-shot (e.g. not a daemon). If you really do want to track the load of our OpenWRT router, just add /bin/load2sqlite to crontab (e.g. every hour) and you’ll have this tracking info in the SQLite database.

    If you run it multiple times, you get another row added to the file each time the program is run:

    root@OpenWrt:~# /bin/load2sqlite 
SQLite database opened
Found readings table
root@OpenWrt:~# echo "select * from readings;" | sqlite3 /tmp/sqlite3.db 
2015-10-31 20:47:33|0.76|0.4|0.25
2015-10-31 20:53:43|0.02|0.2|0.22
2015-10-31 21:23:19|0.08|0.04|0.05

    Note that by default the file is saved to /tmp/, which on OpenWRT is a ramdisk. This means that the file will be lost when you reboot, or if you leave it running unattended for too long, the file size will grow to the point where the ramdisk will consume all available memory and the router will crash. For this reason, I suggest you modify the configuration file /etc/config/load2sqlite to point to non-volatile storage (such as a USB stick).

    Source code: https://github.com/halmartin/load2sqlite

    Why write another OpenWRT software guide?

    Well, while I was looking for resources on how to build and package software for OpenWRT, I ran into a lot of posts about people compiling simple “Hello World” programs for OpenWRT, but for my particular use case, I wanted to utilize multiple libraries in my program, and I couldn’t find any good instructions on how to compile a program with linked libraries for OpenWRT.

    Disclaimer: I’m not a C expert, so maybe there are some headers there which are not strictly necessary, but it works for me and the executable size is quite small.

    If you wish to further reduce the size of your executable, you can tell the compiler to strip it of the symbol table and relocation information. Do this by appending -s to the PROFILE line in the makefile. When I did this on my laptop, the output went from 9.9KB to 7.0KB, or a savings of 30%

    I have tested this on Chaos Calmer (15.05), and I expect the instructions would also work on Barrier Breaker (14.07) however I didn’t try this, so I cannot say certainly that it will work.

    Building Linux 4.1 for the Banana Pi

    2 Replies

    This post is a follow up to my original post Building BananaPi LeMaker Kernel.

    If you’re just looking for a vanilla Debian or Ubuntu image for your Banana Pi that utilizes a Linux kernel newer than 3.4.xxx, then stop reading and go to this page maintained by Igor Pečovnik. He provides pre-built Debian and Ubuntu images for a variety of Banana Pi boards.

    If you want to manually build an image, he has put the build scripts he uses up on his GitHub repository. While I tried to do everything manually starting from my last post, I ended up building a kernel that would not boot. So I shamelessly stole the kernel configuration from Igor, and the resulting kernel boots.

    The GMAC driver which required so much patching for the 3.4 kernel was mainlined in 3.17. As such, these instructions should work for any kernel newer than 3.17. I am building 4.1.3 in my script.

    Here is the Jenkins/bash script to build the kernel, modules, and boot goodness you need (a direct link to the .sh file is at the end of the post):

    if [ ! -d "linux-4.1.3" ]; then
wget https://www.kernel.org/pub/linux/kernel/v4.x/linux-4.1.3.tar.xz
tar -Jxvf linux-4.1.3.tar.xz
fi
cd linux-4.1.3
wget https://watchmysys.com/blog/wp-content/uploads/2015/07/banana-pi-linux-4.1.3-config.txt -O .config
make ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf- clean
make -j4 ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf- LOADADDR=0x40008000 zImage dtbs
make ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf- INSTALL_MOD_PATH=output modules
make ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf- INSTALL_MOD_PATH=output modules_install
mkdir -p output/boot/
cp arch/arm/boot/zImage output/boot/
cp arch/arm/boot/dts/sun7i-a20-bananapi.dtb output/boot/
cat > output/boot/boot.cmd < output/boot/uEnv.txt << EOF
fatload mmc 0 0x46000000 zImage
fatload mmc 0 0x49000000 sun7i-a20-bananapi.dtb
setenv bootargs console=ttyS0,115200 [earlyprintk] root=/dev/mmcblk0p2 rootwait panic=10 rootfstype=ext4 rw ${extra}
bootz 0x46000000 - 0x49000000
EOF
mkimage -C none -A arm -T script -d output/boot/boot.cmd output/boot/boot.scr
cd ..
if [ ! -d "u-boot-2015.04" ]; then
wget ftp://ftp.denx.de/pub/u-boot/u-boot-2015.04.tar.bz2
tar -jxvf u-boot-2015.04.tar.bz2
fi
cd u-boot-2015.04
make -s CROSS_COMPILE=arm-linux-gnueabihf- clean
make ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf- Bananapi_defconfig
make -j4 ARCH=arm CROSS_COMPILE=arm-linux-gnueabihf-
cp u-boot-sunxi-with-spl.bin ../linux-4.1.3/output/boot/
cd ../linux-4.1.3/
cat > output/boot/uEnv.txt << EOF
fatload mmc 0 0x46000000 zImage
fatload mmc 0 0x49000000 sun7i-a20-bananapi.dtb
setenv bootargs console=ttyS0,115200 [earlyprintk] root=/dev/mmcblk0p2 rootwait panic=10 rootfstype=ext4 rw ${extra}
bootz 0x46000000 - 0x49000000
EOF
tar -C output -cjvf ../linux-bananapi-4.1.3.tar.bz2 boot/ lib/

    Here is what the partition layout of my SDHC card:

    root@bpi:~# fdisk -l /dev/mmcblk0

Disk /dev/mmcblk0: 7948 MB, 7948206080 bytes
4 heads, 16 sectors/track, 242560 cylinders, total 15523840 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000

        Device Boot      Start         End      Blocks   Id  System
/dev/mmcblk0p1   *        2048      133119       65536    c  W95 FAT32 (LBA)
/dev/mmcblk0p2          133120    15523839     7695360   83  Linux

    Here is the contents of the boot partition (mmcblk0p1, vfat):

    root@bpi:~# ls /boot
boot.cmd  boot.scr  sun7i-a20-bananapi.dtb  uEnv.txt  zImage

    boot.cmd

    fatload mmc 0 0x46000000 zImage
fatload mmc 0 0x49000000 sun7i-a20-bananapi.dtb
setenv bootargs console=ttyS0,115200 earlyprintk root=/dev/mmcblk0p2 rw rootwait panic=10 
bootm 0x46000000 - 0x49000000

    uEnv.txt

    fatload mmc 0 0x46000000 zImage
fatload mmc 0 0x49000000 sun7i-a20-bananapi.dtb
setenv bootargs console=ttyS0,115200 [earlyprintk] root=/dev/mmcblk0p2 rootwait panic=10 rootfstype=ext4 rw ${extra}
bootz 0x46000000 - 0x49000000

    You will need to update u-boot on the SD card to v2015.04. If you use the script I provide above, this file is in boot/u-boot-sunxi-with-spl.bin. You need to write it to the SD card using dd:

    dd if=boot/u-boot-sunxi-with-spl.bin of=/dev/mmcblk0 bs=1024 seek=8

    More notes:
    I was unable to build this kernel running Debian 7 (Wheezy) because binutils is too old. Unfortunately the official repositories do not have a newer version available for Wheezy (slash) I was too lazy to look for a repository that might have a newer version. As such, I upgraded by Jenkins build box to Debian 8 (Jessie) to build this kernel.

    Additionally, I had to upgrade from a 1GB SD Card in my Banana Pi to an 8GB SDHC Card because the new u-boot does not seem to like small (non-SDHC) cards.

    Banana Pi info:

    root@bpi:~# free -m
             total       used       free     shared    buffers     cached
Mem:           996         72        923          0          4         19
-/+ buffers/cache:         48        948
Swap:            0          0          0
root@bpi:~# uname -a
Linux bpi 4.1.3-bananapi #2 SMP Sun Jul 26 15:41:54 CEST 2015 armv7l GNU/Linux
root@bpi:~# lsmod
Module                  Size  Used by
root@bpi:~#

    Speed test of the network interface:

    # Laptop with Gigabit wired connection, saving to /tmp/ ramdisk
[derp@laptop ~]$ nc -lp 5000 | dd of=/tmp/zerofile
# Banana Pi
root@bpi:~# dd if=/dev/zero bs=1M count=2000 | nc laptop 5000
2000+0 records in
2000+0 records out
2097152000 bytes (2.1 GB) copied, 73.5536 s, 28.5 MB/s

    Yes, it is a Gigabit link, but not the fastest. It does seem to be quite stable, and since I am not using my Banana Pi for a bandwidth intensive purpose, this speed is fine for me.

    The build script does everything with relative paths, and can be run as a normal user. The output is a tar.bz2 archive containing u-boot binary, boot folder, and kernel modules. You will need sudo/root to install the u-boot bin file with dd as described above.

    Download kernel .config: here
    Download build script: here
    Download u-boot 2015.04: here (SHA1SUM: 8bf4f738ba8aa18ab5d45fca324587f0749f7c10)
    Download tar archive with u-boot, kernel, and modules: here (SHA1SUM: d94a8da66ce6d77a1ceb4569740cadf2c8c67e72)