As an example of an end-to-end process for using verified boot in U-Boot, add a detailed description of the steps to be used for a Beaglebone Black. Signed-off-by: Simon Glass <sjg@chromium.org>master
Simon Glass
11 years ago
committed by
Tom Rini
parent
ce1400f694
commit
c7320ed52f
@ -0,0 +1,608 @@ |
||||
Verified Boot on the Beaglebone Black |
||||
===================================== |
||||
|
||||
Introduction |
||||
------------ |
||||
|
||||
Before reading this, please read verified-boot.txt and signature.txt. These |
||||
instructions are for mainline U-Boot from v2014.07 onwards. |
||||
|
||||
There is quite a bit of documentation in this directory describing how |
||||
verified boot works in U-Boot. There is also a test which runs through the |
||||
entire process of signing an image and running U-Boot (sandbox) to check it. |
||||
However, it might be useful to also have an example on a real board. |
||||
|
||||
Beaglebone Black is a fairly common board so seems to be a reasonable choice |
||||
for an example of how to enable verified boot using U-Boot. |
||||
|
||||
First a note that may to help avoid confusion. U-Boot and Linux both use |
||||
device tree. They may use the same device tree source, but it is seldom useful |
||||
for them to use the exact same binary from the same place. More typically, |
||||
U-Boot has its device tree packaged wtih it, and the kernel's device tree is |
||||
packaged with the kernel. In particular this is important with verified boot, |
||||
since U-Boot's device tree must be immutable. If it can be changed then the |
||||
public keys can be changed and verified boot is useless. An attacker can |
||||
simply generate a new key and put his public key into U-Boot so that |
||||
everything verifies. On the other hand the kernel's device tree typically |
||||
changes when the kernel changes, so it is useful to package an updated device |
||||
tree with the kernel binary. U-Boot supports the latter with its flexible FIT |
||||
format (Flat Image Tree). |
||||
|
||||
|
||||
Overview |
||||
-------- |
||||
|
||||
The steps are roughly as follows: |
||||
|
||||
1. Build U-Boot for the board, with the verified boot options enabled. |
||||
|
||||
2. Obtain a suitable Linux kernel |
||||
|
||||
3. Create a Image Tree Source file (ITS) file describing how you want the |
||||
kernel to be packaged, compressed and signed. |
||||
|
||||
4. Create a key pair |
||||
|
||||
5. Sign the kernel |
||||
|
||||
6. Put the public key into U-Boot's image |
||||
|
||||
7. Put U-Boot and the kernel onto the board |
||||
|
||||
8. Try it |
||||
|
||||
|
||||
Step 1: Build U-Boot |
||||
-------------------- |
||||
|
||||
a. Set up the environment variable to point to your toolchain. You will need |
||||
this for U-Boot and also for the kernel if you build it. For example if you |
||||
installed a Linaro version manually it might be something like: |
||||
|
||||
export CROSS_COMPILE=/opt/linaro/gcc-linaro-arm-linux-gnueabihf-4.8-2013.08_linux/bin/arm-linux-gnueabihf- |
||||
|
||||
or if you just installed gcc-arm-linux-gnueabi then it might be |
||||
|
||||
export CROSS_COMPILE=arm-linux-gnueabi- |
||||
|
||||
b. Configure and build U-Boot with verified boot enabled: |
||||
|
||||
export ARCH=arm |
||||
export UBOOT=/path/to/u-boot |
||||
cd $UBOOT |
||||
# You can add -j10 if you have 10 CPUs to make it faster |
||||
make O=b/am335x_boneblack_vboot am335x_boneblack_vboot_config all |
||||
export UOUT=$UBOOT/b/am335x_boneblack_vboot |
||||
|
||||
c. You will now have a U-Boot image: |
||||
|
||||
file b/am335x_boneblack_vboot/u-boot-dtb.img |
||||
b/am335x_boneblack_vboot/u-boot-dtb.img: u-boot legacy uImage, U-Boot 2014.07-rc2-00065-g2f69f8, Firmware/ARM, Firmware Image (Not compressed), 395375 bytes, Sat May 31 16:19:04 2014, Load Address: 0x80800000, Entry Point: 0x00000000, Header CRC: 0x0ABD6ACA, Data CRC: 0x36DEF7E4 |
||||
|
||||
|
||||
Step 2: Build Linux |
||||
-------------------- |
||||
|
||||
a. Find the kernel image ('Image') and device tree (.dtb) file you plan to |
||||
use. In our case it is am335x-boneblack.dtb and it is built with the kernel. |
||||
At the time of writing an SD Boot image can be obtained from here: |
||||
|
||||
http://www.elinux.org/Beagleboard:Updating_The_Software#Image_For_Booting_From_microSD |
||||
|
||||
You can write this to an SD card and then mount it to extract the kernel and |
||||
device tree files. |
||||
|
||||
You can also build a kernel. Instructions for this are are here: |
||||
|
||||
http://elinux.org/Building_BBB_Kernel |
||||
|
||||
or you can use your favourite search engine. Following these instructions |
||||
produces a kernel Image and device tree files. For the record the steps were: |
||||
|
||||
export KERNEL=/path/to/kernel |
||||
cd $KERNEL |
||||
git clone git://github.com/beagleboard/kernel.git . |
||||
git checkout v3.14 |
||||
./patch.sh |
||||
cp configs/beaglebone kernel/arch/arm/configs/beaglebone_defconfig |
||||
cd kernel |
||||
make beaglebone_defconfig |
||||
make uImage dtbs # -j10 if you have 10 CPUs |
||||
export OKERNEL=$KERNEL/kernel/arch/arm/boot |
||||
|
||||
c. You now have the 'Image' and 'am335x-boneblack.dtb' files needed to boot. |
||||
|
||||
|
||||
Step 3: Create the ITS |
||||
---------------------- |
||||
|
||||
Set up a directory for your work. |
||||
|
||||
export WORK=/path/to/dir |
||||
cd $WORK |
||||
|
||||
Put this into a file in that directory called sign.its: |
||||
|
||||
/dts-v1/; |
||||
|
||||
/ { |
||||
description = "Beaglebone black"; |
||||
#address-cells = <1>; |
||||
|
||||
images { |
||||
kernel@1 { |
||||
data = /incbin/("Image.lzo"); |
||||
type = "kernel"; |
||||
arch = "arm"; |
||||
os = "linux"; |
||||
compression = "lzo"; |
||||
load = <0x80008000>; |
||||
entry = <0x80008000>; |
||||
hash@1 { |
||||
algo = "sha1"; |
||||
}; |
||||
}; |
||||
fdt@1 { |
||||
description = "beaglebone-black"; |
||||
data = /incbin/("am335x-boneblack.dtb"); |
||||
type = "flat_dt"; |
||||
arch = "arm"; |
||||
compression = "none"; |
||||
hash@1 { |
||||
algo = "sha1"; |
||||
}; |
||||
}; |
||||
}; |
||||
configurations { |
||||
default = "conf@1"; |
||||
conf@1 { |
||||
kernel = "kernel@1"; |
||||
fdt = "fdt@1"; |
||||
signature@1 { |
||||
algo = "sha1,rsa2048"; |
||||
key-name-hint = "dev"; |
||||
sign-images = "fdt", "kernel"; |
||||
}; |
||||
}; |
||||
}; |
||||
}; |
||||
|
||||
|
||||
The explanation for this is all in the documentation you have already read. |
||||
But briefly it packages a kernel and device tree, and provides a single |
||||
configuration to be signed with a key named 'dev'. The kernel is compressed |
||||
with LZO to make it smaller. |
||||
|
||||
|
||||
Step 4: Create a key pair |
||||
------------------------- |
||||
|
||||
See signature.txt for details on this step. |
||||
|
||||
cd $WORK |
||||
mkdir keys |
||||
openssl genrsa -F4 -out keys/dev.key 2048 |
||||
openssl req -batch -new -x509 -key keys/dev.key -out keys/dev.crt |
||||
|
||||
Note: keys/dev.key contains your private key and is very secret. If anyone |
||||
gets access to that file they can sign kernels with it. Keep it secure. |
||||
|
||||
|
||||
Step 5: Sign the kernel |
||||
----------------------- |
||||
|
||||
We need to use mkimage (which was built when you built U-Boot) to package the |
||||
Linux kernel into a FIT (Flat Image Tree, a flexible file format that U-Boot |
||||
can load) using the ITS file you just created. |
||||
|
||||
At the same time we must put the public key into U-Boot device tree, with the |
||||
'required' property, which tells U-Boot that this key must be verified for the |
||||
image to be valid. You will make this key available to U-Boot for booting in |
||||
step 6. |
||||
|
||||
ln -s $OKERNEL/dts/am335x-boneblack.dtb |
||||
ln -s $OKERNEL/Image |
||||
ln -s $UOUT/u-boot-dtb.img |
||||
cp $UOUT/arch/arm/dts/am335x-boneblack.dtb am335x-boneblack-pubkey.dtb |
||||
lzop Image |
||||
$UOUT/tools/mkimage -f sign.its -K am335x-boneblack-pubkey.dtb -k keys -r image.fit |
||||
|
||||
You should see something like this: |
||||
|
||||
FIT description: Beaglebone black |
||||
Created: Sun Jun 1 12:50:30 2014 |
||||
Image 0 (kernel@1) |
||||
Description: unavailable |
||||
Created: Sun Jun 1 12:50:30 2014 |
||||
Type: Kernel Image |
||||
Compression: lzo compressed |
||||
Data Size: 7790938 Bytes = 7608.34 kB = 7.43 MB |
||||
Architecture: ARM |
||||
OS: Linux |
||||
Load Address: 0x80008000 |
||||
Entry Point: 0x80008000 |
||||
Hash algo: sha1 |
||||
Hash value: c94364646427e10f423837e559898ef02c97b988 |
||||
Image 1 (fdt@1) |
||||
Description: beaglebone-black |
||||
Created: Sun Jun 1 12:50:30 2014 |
||||
Type: Flat Device Tree |
||||
Compression: uncompressed |
||||
Data Size: 31547 Bytes = 30.81 kB = 0.03 MB |
||||
Architecture: ARM |
||||
Hash algo: sha1 |
||||
Hash value: cb09202f889d824f23b8e4404b781be5ad38a68d |
||||
Default Configuration: 'conf@1' |
||||
Configuration 0 (conf@1) |
||||
Description: unavailable |
||||
Kernel: kernel@1 |
||||
FDT: fdt@1 |
||||
|
||||
|
||||
Now am335x-boneblack-pubkey.dtb contains the public key and image.fit contains |
||||
the signed kernel. Jump to step 6 if you like, or continue reading to increase |
||||
your understanding. |
||||
|
||||
You can also run fit_check_sign to check it: |
||||
|
||||
$UOUT/tools/fit_check_sign -f image.fit -k am335x-boneblack-pubkey.dtb |
||||
|
||||
which results in: |
||||
|
||||
Verifying Hash Integrity ... sha1,rsa2048:dev+ |
||||
## Loading kernel from FIT Image at 7fc6ee469000 ... |
||||
Using 'conf@1' configuration |
||||
Verifying Hash Integrity ... |
||||
sha1,rsa2048:dev+ |
||||
OK |
||||
|
||||
Trying 'kernel@1' kernel subimage |
||||
Description: unavailable |
||||
Created: Sun Jun 1 12:50:30 2014 |
||||
Type: Kernel Image |
||||
Compression: lzo compressed |
||||
Data Size: 7790938 Bytes = 7608.34 kB = 7.43 MB |
||||
Architecture: ARM |
||||
OS: Linux |
||||
Load Address: 0x80008000 |
||||
Entry Point: 0x80008000 |
||||
Hash algo: sha1 |
||||
Hash value: c94364646427e10f423837e559898ef02c97b988 |
||||
Verifying Hash Integrity ... |
||||
sha1+ |
||||
OK |
||||
|
||||
Unimplemented compression type 4 |
||||
## Loading fdt from FIT Image at 7fc6ee469000 ... |
||||
Using 'conf@1' configuration |
||||
Trying 'fdt@1' fdt subimage |
||||
Description: beaglebone-black |
||||
Created: Sun Jun 1 12:50:30 2014 |
||||
Type: Flat Device Tree |
||||
Compression: uncompressed |
||||
Data Size: 31547 Bytes = 30.81 kB = 0.03 MB |
||||
Architecture: ARM |
||||
Hash algo: sha1 |
||||
Hash value: cb09202f889d824f23b8e4404b781be5ad38a68d |
||||
Verifying Hash Integrity ... |
||||
sha1+ |
||||
OK |
||||
|
||||
Loading Flat Device Tree ... OK |
||||
|
||||
## Loading ramdisk from FIT Image at 7fc6ee469000 ... |
||||
Using 'conf@1' configuration |
||||
Could not find subimage node |
||||
|
||||
Signature check OK |
||||
|
||||
|
||||
At the top, you see "sha1,rsa2048:dev+". This means that it checked an RSA key |
||||
of size 2048 bits using SHA1 as the hash algorithm. The key name checked was |
||||
'dev' and the '+' means that it verified. If it showed '-' that would be bad. |
||||
|
||||
Once the configuration is verified it is then possible to rely on the hashes |
||||
in each image referenced by that configuration. So fit_check_sign goes on to |
||||
load each of the images. We have a kernel and an FDT but no ramkdisk. In each |
||||
case fit_check_sign checks the hash and prints sha1+ meaning that the SHA1 |
||||
hash verified. This means that none of the images has been tampered with. |
||||
|
||||
There is a test in test/vboot which uses U-Boot's sandbox build to verify that |
||||
the above flow works. |
||||
|
||||
But it is fun to do this by hand, so you can load image.fit into a hex editor |
||||
like ghex, and change a byte in the kernel: |
||||
|
||||
$UOUT/tools/fit_info -f image.fit -n /images/kernel@1 -p data |
||||
NAME: kernel@1 |
||||
LEN: 7790938 |
||||
OFF: 168 |
||||
|
||||
This tells us that the kernel starts at byte offset 168 (decimal) in image.fit |
||||
and extends for about 7MB. Try changing a byte at 0x2000 (say) and run |
||||
fit_check_sign again. You should see something like: |
||||
|
||||
Verifying Hash Integrity ... sha1,rsa2048:dev+ |
||||
## Loading kernel from FIT Image at 7f5a39571000 ... |
||||
Using 'conf@1' configuration |
||||
Verifying Hash Integrity ... |
||||
sha1,rsa2048:dev+ |
||||
OK |
||||
|
||||
Trying 'kernel@1' kernel subimage |
||||
Description: unavailable |
||||
Created: Sun Jun 1 13:09:21 2014 |
||||
Type: Kernel Image |
||||
Compression: lzo compressed |
||||
Data Size: 7790938 Bytes = 7608.34 kB = 7.43 MB |
||||
Architecture: ARM |
||||
OS: Linux |
||||
Load Address: 0x80008000 |
||||
Entry Point: 0x80008000 |
||||
Hash algo: sha1 |
||||
Hash value: c94364646427e10f423837e559898ef02c97b988 |
||||
Verifying Hash Integrity ... |
||||
sha1 error |
||||
Bad hash value for 'hash@1' hash node in 'kernel@1' image node |
||||
Bad Data Hash |
||||
|
||||
## Loading fdt from FIT Image at 7f5a39571000 ... |
||||
Using 'conf@1' configuration |
||||
Trying 'fdt@1' fdt subimage |
||||
Description: beaglebone-black |
||||
Created: Sun Jun 1 13:09:21 2014 |
||||
Type: Flat Device Tree |
||||
Compression: uncompressed |
||||
Data Size: 31547 Bytes = 30.81 kB = 0.03 MB |
||||
Architecture: ARM |
||||
Hash algo: sha1 |
||||
Hash value: cb09202f889d824f23b8e4404b781be5ad38a68d |
||||
Verifying Hash Integrity ... |
||||
sha1+ |
||||
OK |
||||
|
||||
Loading Flat Device Tree ... OK |
||||
|
||||
## Loading ramdisk from FIT Image at 7f5a39571000 ... |
||||
Using 'conf@1' configuration |
||||
Could not find subimage node |
||||
|
||||
Signature check Bad (error 1) |
||||
|
||||
|
||||
It has detected the change in the kernel. |
||||
|
||||
You can also be sneaky and try to switch images, using the libfdt utilities |
||||
that come with dtc (package name is device-tree-compiler but you will need a |
||||
recent version like 1.4: |
||||
|
||||
dtc -v |
||||
Version: DTC 1.4.0 |
||||
|
||||
First we can check which nodes are actually hashed by the configuration: |
||||
|
||||
fdtget -l image.fit / |
||||
images |
||||
configurations |
||||
|
||||
fdtget -l image.fit /configurations |
||||
conf@1 |
||||
fdtget -l image.fit /configurations/conf@1 |
||||
signature@1 |
||||
|
||||
fdtget -p image.fit /configurations/conf@1/signature@1 |
||||
hashed-strings |
||||
hashed-nodes |
||||
timestamp |
||||
signer-version |
||||
signer-name |
||||
value |
||||
algo |
||||
key-name-hint |
||||
sign-images |
||||
|
||||
fdtget image.fit /configurations/conf@1/signature@1 hashed-nodes |
||||
/ /configurations/conf@1 /images/fdt@1 /images/fdt@1/hash@1 /images/kernel@1 /images/kernel@1/hash@1 |
||||
|
||||
This gives us a bit of a look into the signature that mkimage added. Note you |
||||
can also use fdtdump to list the entire device tree. |
||||
|
||||
Say we want to change the kernel that this configuration uses |
||||
(/images/kernel@1). We could just put a new kernel in the image, but we will |
||||
need to change the hash to match. Let's simulate that by changing a byte of |
||||
the hash: |
||||
|
||||
fdtget -tx image.fit /images/kernel@1/hash@1 value |
||||
c9436464 6427e10f 423837e5 59898ef0 2c97b988 |
||||
fdtput -tx image.fit /images/kernel@1/hash@1 value c9436464 6427e10f 423837e5 59898ef0 2c97b981 |
||||
|
||||
Now check it again: |
||||
|
||||
$UOUT/tools/fit_check_sign -f image.fit -k am335x-boneblack-pubkey.dtb |
||||
Verifying Hash Integrity ... sha1,rsa2048:devrsa_verify_with_keynode: RSA failed to verify: -13 |
||||
rsa_verify_with_keynode: RSA failed to verify: -13 |
||||
- |
||||
Failed to verify required signature 'key-dev' |
||||
Signature check Bad (error 1) |
||||
|
||||
This time we don't even get as far as checking the images, since the |
||||
configuration signature doesn't match. We can't change any hashes without the |
||||
signature check noticing. The configuration is essentially locked. U-Boot has |
||||
a public key for which it requires a match, and will not permit the use of any |
||||
configuration that does not match that public key. The only way the |
||||
configuration will match is if it was signed by the matching private key. |
||||
|
||||
It would also be possible to add a new signature node that does match your new |
||||
configuration. But that won't work since you are not allowed to change the |
||||
configuration in any way. Try it with a fresh (valid) image if you like by |
||||
running the mkimage link again. Then: |
||||
|
||||
fdtput -p image.fit /configurations/conf@1/signature@2 value fred |
||||
$UOUT/tools/fit_check_sign -f image.fit -k am335x-boneblack-pubkey.dtb |
||||
Verifying Hash Integrity ... - |
||||
sha1,rsa2048:devrsa_verify_with_keynode: RSA failed to verify: -13 |
||||
rsa_verify_with_keynode: RSA failed to verify: -13 |
||||
- |
||||
Failed to verify required signature 'key-dev' |
||||
Signature check Bad (error 1) |
||||
|
||||
|
||||
Of course it would be possible to add an entirely new configuration and boot |
||||
with that, but it still needs to be signed, so it won't help. |
||||
|
||||
|
||||
6. Put the public key into U-Boot's image |
||||
----------------------------------------- |
||||
|
||||
Having confirmed that the signature is doing its job, let's try it out in |
||||
U-Boot on the board. U-Boot needs access to the public key corresponding to |
||||
the private key that you signed with so that it can verify any kernels that |
||||
you sign. |
||||
|
||||
cd $UBOOT |
||||
make O=b/am335x_boneblack_vboot EXT_DTB=${WORK}/am335x-boneblack-pubkey.dtb |
||||
|
||||
Here we are overrriding the normal device tree file with our one, which |
||||
contains the public key. |
||||
|
||||
Now you have a special U-Boot image with the public key. It can verify can |
||||
kernel that you sign with the private key as in step 5. |
||||
|
||||
If you like you can take a look at the public key information that mkimage |
||||
added to U-Boot's device tree: |
||||
|
||||
fdtget -p am335x-boneblack-pubkey.dtb /signature/key-dev |
||||
required |
||||
algo |
||||
rsa,r-squared |
||||
rsa,modulus |
||||
rsa,n0-inverse |
||||
rsa,num-bits |
||||
key-name-hint |
||||
|
||||
This has information about the key and some pre-processed values which U-Boot |
||||
can use to verify against it. These values are obtained from the public key |
||||
certificate by mkimage, but require quite a bit of code to generate. To save |
||||
code space in U-Boot, the information is extracted and written in raw form for |
||||
U-Boot to easily use. The same mechanism is used in Google's Chrome OS. |
||||
|
||||
Notice the 'required' property. This marks the key as required - U-Boot will |
||||
not boot any image that does not verify against this key. |
||||
|
||||
|
||||
7. Put U-Boot and the kernel onto the board |
||||
------------------------------------------- |
||||
|
||||
The method here varies depending on how you are booting. For this example we |
||||
are booting from an micro-SD card with two partitions, one for U-Boot and one |
||||
for Linux. Put it into your machine and write U-Boot and the kernel to it. |
||||
Here the card is /dev/sde: |
||||
|
||||
cd $WORK |
||||
export UDEV=/dev/sde1 # Change thes two lines to the correct device |
||||
export KDEV=/dev/sde2 |
||||
sudo mount $UDEV /mnt/tmp && sudo cp $UOUT/u-boot-dtb.img /mnt/tmp/u-boot.img && sleep 1 && sudo umount $UDEV |
||||
sudo mount $KDEV /mnt/tmp && sudo cp $WORK/image.fit /mnt/tmp/boot/image.fit && sleep 1 && sudo umount $KDEV |
||||
|
||||
|
||||
8. Try it |
||||
--------- |
||||
|
||||
Boot the board using the commands below: |
||||
|
||||
setenv bootargs console=ttyO0,115200n8 quiet root=/dev/mmcblk0p2 ro rootfstype=ext4 rootwait |
||||
ext2load mmc 0:2 82000000 /boot/image.fit |
||||
bootm 82000000 |
||||
|
||||
You should then see something like this: |
||||
|
||||
U-Boot# setenv bootargs console=ttyO0,115200n8 quiet root=/dev/mmcblk0p2 ro rootfstype=ext4 rootwait |
||||
U-Boot# ext2load mmc 0:2 82000000 /boot/image.fit |
||||
7824930 bytes read in 589 ms (12.7 MiB/s) |
||||
U-Boot# bootm 82000000 |
||||
## Loading kernel from FIT Image at 82000000 ... |
||||
Using 'conf@1' configuration |
||||
Verifying Hash Integrity ... sha1,rsa2048:dev+ OK |
||||
Trying 'kernel@1' kernel subimage |
||||
Description: unavailable |
||||
Created: 2014-06-01 19:32:54 UTC |
||||
Type: Kernel Image |
||||
Compression: lzo compressed |
||||
Data Start: 0x820000a8 |
||||
Data Size: 7790938 Bytes = 7.4 MiB |
||||
Architecture: ARM |
||||
OS: Linux |
||||
Load Address: 0x80008000 |
||||
Entry Point: 0x80008000 |
||||
Hash algo: sha1 |
||||
Hash value: c94364646427e10f423837e559898ef02c97b988 |
||||
Verifying Hash Integrity ... sha1+ OK |
||||
## Loading fdt from FIT Image at 82000000 ... |
||||
Using 'conf@1' configuration |
||||
Trying 'fdt@1' fdt subimage |
||||
Description: beaglebone-black |
||||
Created: 2014-06-01 19:32:54 UTC |
||||
Type: Flat Device Tree |
||||
Compression: uncompressed |
||||
Data Start: 0x8276e2ec |
||||
Data Size: 31547 Bytes = 30.8 KiB |
||||
Architecture: ARM |
||||
Hash algo: sha1 |
||||
Hash value: cb09202f889d824f23b8e4404b781be5ad38a68d |
||||
Verifying Hash Integrity ... sha1+ OK |
||||
Booting using the fdt blob at 0x8276e2ec |
||||
Uncompressing Kernel Image ... OK |
||||
Loading Device Tree to 8fff5000, end 8ffffb3a ... OK |
||||
|
||||
Starting kernel ... |
||||
|
||||
[ 0.582377] omap_init_mbox: hwmod doesn't have valid attrs |
||||
[ 2.589651] musb-hdrc musb-hdrc.0.auto: Failed to request rx1. |
||||
[ 2.595830] musb-hdrc musb-hdrc.0.auto: musb_init_controller failed with status -517 |
||||
[ 2.606470] musb-hdrc musb-hdrc.1.auto: Failed to request rx1. |
||||
[ 2.612723] musb-hdrc musb-hdrc.1.auto: musb_init_controller failed with status -517 |
||||
[ 2.940808] drivers/rtc/hctosys.c: unable to open rtc device (rtc0) |
||||
[ 7.248889] libphy: PHY 4a101000.mdio:01 not found |
||||
[ 7.253995] net eth0: phy 4a101000.mdio:01 not found on slave 1 |
||||
systemd-fsck[83]: Angstrom: clean, 50607/218160 files, 306348/872448 blocks |
||||
|
||||
.---O---. |
||||
| | .-. o o |
||||
| | |-----.-----.-----.| | .----..-----.-----. |
||||
| | | __ | ---'| '--.| .-'| | | |
||||
| | | | | |--- || --'| | | ' | | | | |
||||
'---'---'--'--'--. |-----''----''--' '-----'-'-'-' |
||||
-' | |
||||
'---' |
||||
|
||||
The Angstrom Distribution beaglebone ttyO0 |
||||
|
||||
Angstrom v2012.12 - Kernel 3.14.1+ |
||||
|
||||
beaglebone login: |
||||
|
||||
At this point your kernel has been verified and you can be sure that it is one |
||||
that you signed. As an exercise, try changing image.fit as in step 5 and see |
||||
what happens. |
||||
|
||||
|
||||
Further Improvements |
||||
-------------------- |
||||
|
||||
Several of the steps here can be easily automated. In particular it would be |
||||
capital if signing and packaging a kernel were easy, perhaps a simple make |
||||
target in the kernel. |
||||
|
||||
Some mention of how to use multiple .dtb files in a FIT might be useful. |
||||
|
||||
U-Boot's verified boot mechanism has not had a robust and independent security |
||||
review. Such a review should look at the implementation and its resistance to |
||||
attacks. |
||||
|
||||
Perhaps the verified boot feature could could be integrated into the Amstrom |
||||
distribution. |
||||
|
||||
|
||||
Simon Glass |
||||
sjg@chromium.org |
||||
2-June-14 |
||||
Loading…
Reference in new issue