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grub2-signing-extension
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@ -14,58 +14,53 @@ You need
## Preparation ## Installation
### Arch Linux (AUR)
- Import [Bandie's GPG key](https://bandie.org/assets/bandie.pub.asc) through running `gpg --recv-keys E2D7876915312785DC086BFCC1E133BC65A822DD`.
- Use your favourite AUR helper to install [grub2-signing-extension](https://aur.archlinux.org/packages/grub2-signing-extension/).
Before you can use the signing and verification feature you need to generate a keypair as root. Please use a secure passphrase. ### 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.tar.gz) and it's [signature](https://github.com/Bandie/grub2-signing-extension/releases/download/0.1/grub2-signing-extension-0.1.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.
`# gpg --gen-key` You will now have `grub2-sign`, `grub2-unsign`, `grub2-verify` and `grub2-update-kernel-signature` as runable scripts.
To make gpg able to sign and verify files in a `su` environment we need to activate the gpg-agent for root. ## Enabling GRUB2 check\_signatures feature
Edit the file _/root/.gnupg/gpg.conf_ and add the line `use-agent`. Before you can use the signing and verification feature you need to generate a keypair as root.
Save the file and create _/root/.gnupg/gpg-agent.conf_ with the following content - Run `gpg --gen-key` as root. Please use a secure passphrase.
- Activate the `gpg-agent` for root so that you are able to sign and verify files in a `su` environment. To do that:
- Edit the file _/root/.gnupg/gpg.conf_ and add the line `use-agent`. Save the file.
- Create _/root/.gnupg/gpg-agent.conf_ with the following content
```
pinentry-program /usr/bin/pinentry-curses
no-grab
default-cache-ttl 1800
```
- 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"`
- Enable GRUB2's check\_signatures feature:
- Insert the following content at the end of the file of */etc/grub.d/00_header*
```
cat << EOF
set check_signatures=enforce
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.
pinentry-program /usr/bin/pinentry-curses **It is also recommended to install a password in GRUB2! [See ADDENDUM]**
no-grab
default-cache-ttl 1800
## How to update the signatures on changes
## How to install the GRUB2 check\_signatures feature and using the grub2-signing-extension
First, export your public key.
`# gpg --export -o ~/pubkey`
Next step, `mount /boot` and (re)install GRUB2. You need to install the public key into the core and instruct to load the modules `gcry_sha256` `gcry_dsa` and `gcry_rsa` at start. So you need the following arguments to install it this way
`grub-install /dev/sda -k /root/pubkey --modules="gcry_sha256 gcry_dsa gcry_rsa"`
Now download the grub2-signing-extension and run `make install` as root. You will now have `grub2-sign`, `grub2-unsign`, `grub2-verify` and `grub2-update-kernel-signature` as runable scripts.
To _enable_ GRUB2's check\_signatures feature insert the following content at the end of the file of */etc/grub.d/00_header*
cat << EOF
set check_signatures=enforce
EOF
Run `grub-mkconfig -o /boot/grub/grub.cfg` to make the new configuration valid.
Now the time is come to sign your GRUB2 bootloader. Just run `grub2-sign`, enter your passphrase and that's it.
**It's also recommended to install a password in GRUB2! [See ADDENDUM]**
## How to update the signatures on change
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 `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.
@ -146,35 +141,33 @@ Check your system thoroughly. Check it about malicious software. Check it about
## How to install a GRUB2 password ## How to install a GRUB2 password
Run `grub-mkpasswd-pbkdf2` and type a password. Please take care because in the GRUB2 standard installation the keyboard layout is set to en\_US. - Generate a GRUB2 password string through running `grub-mkpasswd-pbkdf2`. Please take care because in the GRUB2 standard installation the keyboard layout is set to en\_US.
Copy the content of *grub.pbkdf2.[...]* to your clipboard. Open the file */etc/grub.d/00_header* and insert this at the end of the file - Copy the generated *grub.pbkdf2.[...]* string to your clipboard.
- Open the file */etc/grub.d/00_header* and insert this at the end of the file
```
cat << EOF cat << EOF
set superusers="yourUsername" set superusers="yourUsername"
export superusers export superusers
password_pbkdf2 yourUsername grub.pbkdf2.[...this string from the clipboard...] password_pbkdf2 yourUsername [...this grub.pbkdf2.* string from the clipboard...]
EOF EOF
```
To boot GNU/Linux automatically and without authentication open */etc/grub.d/10_linux* and change the following lines like this - To boot GNU/Linux automatically and without authentication open */etc/grub.d/10_linux* and change the following lines from
```
echo "menuentry '$(echo "$title" | grub_quote)' ${CLASS} \$menuentry_id_option 'gnulinux-$version-$type-$boot_device_id' {" | sed "s/^/$submenu_indentation/" echo "menuentry '$(echo "$title" | grub_quote)' ${CLASS} \$menuentry_id_option 'gnulinux-$version-$type-$boot_device_id' {" | sed "s/^/$submenu_indentation/"
else else
echo "menuentry '$(echo "$os" | grub_quote)' ${CLASS} \$menuentry_id_option 'gnulinux-simple-$boot_device_id' {" | sed "s/^/$submenu_indentation/" echo "menuentry '$(echo "$os" | grub_quote)' ${CLASS} \$menuentry_id_option 'gnulinux-simple-$boot_device_id' {" | sed "s/^/$submenu_indentation/"
fi fi
```
to
to ```
echo "menuentry '$(echo "$title" | grub_quote)' --unrestricted ${CLASS} \$menuentry_id_option 'gnulinux-$version-$type-$boot_device_id' {" | sed "s/^/$submenu_indentation/"
echo "menuentry '$(echo "$title" | grub_quote)' --unrestricted ${CLASS} \$menuentry_id_option 'gnulinux-$version-$type-$boot_device_id' {" | sed "s/^/$submenu_indentation/"
else else
echo "menuentry '$(echo "$os" | grub_quote)' --unrestricted ${CLASS} \$menuentry_id_option 'gnulinux-simple-$boot_device_id' {" | sed "s/^/$submenu_indentation/" echo "menuentry '$(echo "$os" | grub_quote)' --unrestricted ${CLASS} \$menuentry_id_option 'gnulinux-simple-$boot_device_id' {" | sed "s/^/$submenu_indentation/"
fi fi
```
The important changing is the flag *--unrestricted*. The important changing is the flag *--unrestricted*.
- Run `grub2-unsign` to unsign the bootloader.
Run `grub2-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.
Then run `grub-mkconfig -o /boot/grub/grub.cfg` to write the new config.
After this run `grub2-sign` again to sign the new changings.