Compare commits

...

10 Commits

6 changed files with 51 additions and 44 deletions

View File

@ -6,12 +6,14 @@ all:
@printf "Nothing to make. Run make install.\n"
install:
install -D -m744 sbin/grub2-verify /usr/sbin/grub2-verify
install -D -m744 sbin/grub2-sign /usr/sbin/grub2-sign
install -D -m744 sbin/grub2-unsign /usr/sbin/grub2-unsign
install -D -m744 sbin/grub2-update-kernel-signature /usr/sbin/grub2-update-kernel-signature
@printf "Check for old scripts and remove them...\n"
rm -f /usr/sbin/grub2-{verify,sign,unsign,update-kernel-signature}
install -D -m744 sbin/grub-verify /usr/sbin/grub-verify
install -D -m744 sbin/grub-sign /usr/sbin/grub-sign
install -D -m744 sbin/grub-unsign /usr/sbin/grub-unsign
install -D -m744 sbin/grub-update-kernel-signature /usr/sbin/grub-update-kernel-signature
@printf "Done.\n"
uninstall:
rm /usr/sbin/grub2-{verify,sign,unsign,update-kernel-signature}
rm -f /usr/sbin/grub-{verify,sign,unsign,update-kernel-signature}
@printf "Done.\n"

View File

@ -21,13 +21,13 @@ You need
### From github
- Import [Bandie's GPG key](https://bandie.org/assets/bandie.pub.asc) through running `gpg --recv-keys E2D7876915312785DC086BFCC1E133BC65A822DD`.
- Download the [grub2-signing-extension](https://github.com/Bandie/grub2-signing-extension/releases/download/0.1/grub2-signing-extension-0.1.1.tar.gz) and it's [signature](https://github.com/Bandie/grub2-signing-extension/releases/download/0.1/grub2-signing-extension-0.1.1.tar.gz.asc).
- Download the [grub2-signing-extension](https://github.com/Bandie/grub2-signing-extension/releases/download/0.1.2/grub2-signing-extension-0.1.2.tar.gz) and it's [signature](https://github.com/Bandie/grub2-signing-extension/releases/download/0.1.2/grub2-signing-extension-0.1.2.tar.gz.asc).
- Run `gpg --verify grub2-signing-extension*.tar.gz.asc` to make sure that everything is alright.
- Unpack the tar archive. `tar xvf grub2-signing-extension*.tar.gz`
- Change into the grub2-signing-extension directory.
- Run `make install` as root.
You will now have `grub2-sign`, `grub2-unsign`, `grub2-verify` and `grub2-update-kernel-signature` as runable scripts.
You will now have `grub-sign`, `grub-unsign`, `grub-verify` and `grub-update-kernel-signature` as runable scripts.
## Enabling GRUB2 check\_signatures feature
@ -45,8 +45,8 @@ Before you can use the signing and verification feature you need to generate a k
```
- Export your public key through running `gpg --export -o ~/pubkey`.
- `mount /boot` (assuming your /boot partition is in your /etc/fstab)
- (Re)install GRUB2. The following command will install root's public key into the core and instruct to load the modules `gcry_sha256` `gcry_dsa` and `gcry_rsa` at start so that GRUB2 will be able to do verifications.
- `grub-install /dev/sda -k /root/pubkey --modules="gcry_sha256 gcry_dsa gcry_rsa"`
- (Re)install GRUB2. The following command will install root's public key into the core and instruct to load the modules `gcry_sha256`, `gcry_sha512` `gcry_dsa` and `gcry_rsa` at start so that GRUB2 will be able to do verifications. GRUB2 will take the right crypto for you then, depending on your system's configuration.
- `grub-install /dev/sda -k /root/pubkey --modules="gcry_sha256 gcry_sha512 gcry_dsa gcry_rsa"`
- Enable GRUB2's check\_signatures feature:
- Insert the following content at the end of the file of */etc/grub.d/00_header*
```
@ -55,16 +55,16 @@ Before you can use the signing and verification feature you need to generate a k
EOF
```
- Run`grub-mkconfig -o /boot/grub/grub.cfg` to make the new configuration valid.
- Sign your bootloader running `grub2-sign` and enter your GPG passphrase.
- Sign your bootloader running `grub-sign` and enter your GPG passphrase.
**It is also recommended to install a password in GRUB2! [See ADDENDUM]**
## How to update the signatures on changes
On every change at the GRUB2 core files you need to run `grub2-unsign` first before you make your changes. Please notice, if you reinstall GRUB2, you should do it as it is said above. Otherwise the signature check won't work.
On every change at the GRUB2 core files you need to run `grub-unsign` first before you make your changes. Please notice, if you reinstall GRUB2, you should do it as it is said above. Otherwise the signature check won't work.
If you do some changes or updates for the kernel or initramfs, you may want to use `grub2-update-kernel-signature` instead.
If you do some changes or updates for the kernel or initramfs, you may want to use `grub-update-kernel-signature` instead.
@ -73,15 +73,15 @@ If you do some changes or updates for the kernel or initramfs, you may want to u
If you didn't read the instruction above here is what the scripts does:
* `grub2-sign` is signing the bootloader files with root's keypair.
* `grub2-unsign` is removing the signatures of the bootloader files.
* `grub2-verify` is checking if your signatures are good. If not, you will see which signature is bad.
* `grub2-update-kernel-signature` is renewing the signatures in /boot/. (without subdirs) regardless if grub2-verify fails.
* `grub-sign` is signing the bootloader files with root's keypair.
* `grub-unsign` is removing the signatures of the bootloader files.
* `grub-verify` is checking if your signatures are good. If not, you will see which signature is bad.
* `grub-update-kernel-signature` is renewing the signatures in /boot/ (without subdirs) and grub.cfg, regardless if grub-verify fails.
## Exit codes
You might be interested in the exit codes of `grub2-verify` to use it in your monitoring tools:
You might be interested in the exit codes of `grub-verify` to use it in your monitoring tools:
```
0 - Everything is okay
@ -107,8 +107,8 @@ chown root:root $(tty)
### I forgot to run grub2-unsign before I made changes. What now?
Run `grub2-verify` to see, which signature is bad. Remove the signature and run `grub2-unsign`, after this `grub2-sign`.
Alternatively, if you just updated your kernel/initramfs, run `grub2-update-kernel-signatures`.
Run `grub-verify` to see, which signature is bad. Remove the signature and run `grub-unsign`, after this `grub-sign`.
Alternatively, if you just updated your kernel/initramfs/grub.cfg, run `grub-update-kernel-signatures`.
### How can I switch off GRUB2's check\_signature feature?
@ -119,7 +119,7 @@ Open */etc/grub.d/00_header* and remove the part
set check_signatures=enforce
EOF
Run `grub2-unsign` and `grub-mkconfig -o /boot/grub/grub.cfg`.
Run `grub-unsign` and `grub-mkconfig -o /boot/grub/grub.cfg`.
Also you should reinstall grub2, using something like `grub-install /dev/sda`.
@ -127,8 +127,8 @@ Also you should reinstall grub2, using something like `grub-install /dev/sda`.
### Suddenly I can't boot! This is YOUR FAULT!
No. An important signature is bad. So GRUB2 didn't run this part of code/configuration/kernel/whatever.
You could do a chroot using an USB dongle with a GNU/Linux distribution on it. If you're chrooted to your system run `grub2-verify`.
If you think this happened through an update shortly done by you, you may want to run `gpg-agent --daemon ; grub2-update-kernel-signatures`.
You could do a chroot using an USB dongle with a GNU/Linux distribution on it. If you're chrooted to your system run `grub-verify`.
If you think this happened through an update shortly done by you, you may want to run `gpg-agent --daemon ; grub-update-kernel-signatures`.
### Okay, I really got some bad signatures not caused by me. What do I do now?
@ -168,6 +168,6 @@ Check your system thoroughly. Check it about malicious software. Check it about
```
The important changing is the flag *--unrestricted*.
- Run `grub2-unsign` to unsign the bootloader.
- Run `grub-unsign` to unsign the bootloader.
- Run `grub-mkconfig -o /boot/grub/grub.cfg` to write the new config.
- Run `grub2-sign` to sign the new changings.
- Run `grub-sign` to sign the new changings.

View File

@ -5,7 +5,7 @@
# Licence: GNU-GPLv3
function sign(){
for f in `find /boot -type f`
for f in $(find /boot -iname "efi" -prune -o -type f -print)
do
if gpg --detach-sign $f
then
@ -20,7 +20,7 @@ function sign(){
# Running grub2-verify first to prevent bad people and double signing
echo "Running grub2-verify to check if everything is unsigned..." >&2
grub2-verify
grub-verify
if (( $? < 2 )); then
echo "Run grub2-unsign first." >&2
exit 1

View File

@ -5,30 +5,28 @@
# Licence: GNU-GPLv3
# Check if something is wrong
grub2-verify
grub-verify
stat=$?
if (( $stat == 1 ))
then
case "$stat" in
1)
printf '%s\n' "grub2-verify has detected a one or more bad signatures." "Please check for malicious software before you're unsigning everything!" >&2
exit 1
elif (( $stat == 2 ))
then
;;
2)
printf 'Everything is unsigned already.\n'
exit 0
elif (( $stat == 3 ))
then
;;
3)
printf 'Ignoring missing signatures...\n'
elif (( $stat == 0 ))
then
;&
0|3)
# Then remove the signatures.
find /boot -name '*.sig' -exec rm {} +
find /boot -iname "efi" -prune -o -name '*.sig' -exec shred --remove=unlink {} +
echo "GRUB2 unsigned. WARNING: If you want to deactivate GRUB2's signature feature, change the check_signatures variable in the headers file!"
exit 0
else
;;
*)
printf 'Something unknown happened!\n'
exit 99
fi
esac

View File

@ -14,11 +14,18 @@ function sign(){
return 1
fi
done
if gpg --detach-sign "/boot/grub/grub.cfg"
then
echo /boot/grub/grub.cfg signed.
else
return 1
fi
return 0
}
rm /boot/*.sig
shred --remove=unlink /boot/*.sig
shred --remove=unlink /boot/grub/grub.cfg.sig
if ! sign
then

View File

@ -22,7 +22,7 @@ do
error_files+=( "$i" )
fi
all_files+=( "$i" )
done < <(find /boot -type f -name "*.sig" -print0)
done < <(find /boot -iname "efi" -prune -o -type f -name "*.sig" -print0)
echo "Checking missing signatures in /boot..." >&2
while IFS= read -r -d '' i
@ -31,7 +31,7 @@ do
then
missing_files+=( "$i" )
fi
done < <(find /boot -type f -not -name "*.sig" -print0)
done < <(find /boot -iname "efi" -prune -o -type f -not -name "*.sig" -print0)
# Nothing to verify? Exit 2.
if (( ${#all_files[@]} == 0 ))