Flashing¶

There are several way to flash partitions (e.g. updating) manually:

• using /usr/sbin/ubiupdatevol:
  

  ubiupdatevol version 1.2 - a tool to write data to UBI volumes.
  
  Usage: ubiupdatevol <UBI volume node file name> [-t] [-s <size>] [-h] [-V] [--truncate]
              [--size=<size>] [--help] [--version] <image file>
  
  Example 1: ubiupdatevol /dev/ubi0_1 fs.img - write file "fs.img" to UBI volume /dev/ubi0_1
  Example 2: ubiupdatevol /dev/ubi0_1 -t - wipe out UBI volume /dev/ubi0_1
  
  -t, --truncate             truncate volume (wipe it out)
  -s, --size=<bytes>         bytes in input, if not reading from file
  -h, --help                 print help message
  -V, --version              print program version
  

• using /APP/dev_only/swupd.sh
  

  swupd.sh - update flash partitions on the target
  
  Easy mode:
     using NFS: swupd.sh -i<IP> -p<PATH>
     where:
     <IP>   = IP address of your VM (defaults to 192.168.16.18)
     <PATH> = path of NFS directory (defaults to /home/femto/ftpdata)
  
     using wget: swupd.sh -w<URL>
     where:
     <URL>  = URL to fetch images from (e.g. ftp://user:pass@host/path)
  
  Expert mode: (stay away from them!)
     -k update kernel
     -r update root fs
     -a update application partition
     -u update unitdata partition
     -c update caldata partition
     -x toggle banks
     -z don't reboot after successful update
  
     -o<str> Pass option string <str> to wget
  

/etc/init.d/flash_update takes care of flashing all partitions at once (also done during boot in /etc/init.d/rcS).

Lastly the operator can also flash images remotely through /APP/bin/oam_start.

Secure boot¶

System¶

The femtocell uses "secure boot" (see Bootlog).
You can check if it has been activated using cat /proc/prc6000/otp_data/boot/secured.

The partition signatures (kernel, rootfs, data) are stored in /dev/mtdblock2/bootdata.ini (the only file in the bootdata partition).
While bootdata is not signed itself, it only contains the signatures.
You can also see the content using /APP/dev_only/cat_bootdata.sh
The corresponding public key seems to be burned in the OTP section of the CPU, providing secure boot (this has not been verified).

bootdata.ini also defines which system will be booted (A or B).
The file is updated using /APP/dev_only/write_bootdata.sh

Operator¶

The unidata (mtd3) signature is checked in /etc/init.d/flash_update (called by /etc/init.d/rcS) using /boot/bc_cli -u${PARTNUM_UNITDATA} -q (with PARTNUM_UNITDATA=3):

• hash is sha1sum of 0x2000 (8192) first bytes
• signature is at 0x2000 (after the cramfs indicated size)
• public key is first 256 bytes of /caldata/unitkey.bin

It the signature check fails, unidata_backup is used.
If this signature check fails too, it enters recovery mode

caldata in mounted without check (in /etc/init.d/flash_update)