PCRSignature:initrd security fix

Reverted PCRSignature Phases=enter-initrd only with working systemd-tpm2-setup; small typo fixes

README.md

@@ -17,7 +17,7 @@ Alternatively, from an existing Arch Linux installation run:
 $ pacman-key -v archlinux-version-x86_64.iso.sig
 ```
 
-This guide assumes that your system supports UEFI amd you have a `Wired Ethernet` connection.
+This guide assumes that your system supports UEFI and you have a `Wired Ethernet` connection.
 If you want to use `Wi-Fi`, refer to the [Arch Wiki](https://wiki.archlinux.org/title/installation_guide#Connect_to_the_internet)
 
 ### 1. Disk Preparation
@@ -90,7 +90,8 @@ Now we, need to create the **LUKS2** encrypted container.
 
 **Optional**: Overwriting your disk with random data is an optional step that can help prevent any possible recovery of old data. This is typically done before setting up the LUKS2 container to ensure the disk is fully erased.
 
-Warning: This will erase all data on the disk. Ensure you have selected the correct device.
+> [!WARNING]
+> This will erase all data on the disk. Ensure you have selected the correct device.
 
 ```
 dd if=/dev/urandom of=/dev/nvme0n1p2 bs=1M status=progress
@@ -128,7 +129,8 @@ Create a volume group (in this example, it is named `MyVolGroup`, but it can be
 
 Create all your logical volumes on the volume group:
 
-**Tip**: If a logical volume will be formatted with ext4, leave at least 256 MiB free space in the volume group to allow using `e2scrub`. After creating the last volume with `-l 100%FREE`, this can be accomplished by reducing its size with `lvreduce -L -256M MyVolGroup/home`.
+> [!TIP]
+> If a logical volume will be formatted with ext4, leave at least 256 MiB free space in the volume group to allow using `e2scrub`. After creating the last volume with `-l 100%FREE`, this can be accomplished by reducing its size with `lvreduce -L -256M MyVolGroup/home`.
 
 ```
 # lvcreate -L 4G MyVolGroup -n swap
@@ -168,9 +170,10 @@ Mount the partition to `/mnt/efi`:
 
 ### 6. Installation
 
-**Note**: This section of the guide deals with installing the base system, setting up timezones, locale, hostname, hosts, creating new non-root user's, setting passwords for both `root` and `non-root` user accounts.
+> [!NOTE]
-This is generally user specific configuration, and you might have a different setup you might, want to follow.
+> This section of the guide deals with installing the base system, setting up timezones, locale, hostname, hosts, creating new non-root user's, setting passwords for both `root` and `non-root` user accounts.
-So it is recommended to refer to official [Arch Wiki Installation guide](https://wiki.archlinux.org/title/installation_guide#Installation), for this section. And you may come back here and follow from the next section, when it is time to [configure mkinitcpio](https://github.com/joelmathewthomas/archinstall-luks2-lvm2-secureboot-tpm2#7-configure-mkinitcpio).
+> This is generally user specific configuration, and you might have a different setup you might, want to follow.
+> So it is recommended to refer to official [Arch Wiki Installation guide](https://wiki.archlinux.org/title/installation_guide#Installation), for this section. And you may come back here and follow from the next section, when it is time to [configure mkinitcpio](https://github.com/joelmathewthomas/archinstall-luks2-lvm2-secureboot-tpm2#7-configure-mkinitcpio).
 
 But, if you want to follow through, how I do it, feel free to follow through this section.
 
@@ -286,7 +289,7 @@ Uncomment the following line:
 Add new user to wheel group:
 
 ```
-# usermod -G wheel newuser
+# usermod -aG wheel newuser
 ```
 
 ### 7. Configure `mkinitcpio`
@@ -361,6 +364,10 @@ The calculated policy will be included in the .pcrsig section.
 
 When `.pcrsig` and/or `.pcrpkey` sections are present in a unified kernel image their contents are passed to the booted kernel in an synthetic initrd cpio archive that places them in the `/.extra/tpm2-pcr-signature.json` and `/.extra/tpm2-pcr-public-key.pem` files. Typically, a tmpfiles.d line then ensures they are copied into `/run/systemd/tpm2-pcr-signature.json` and `/run/systemd/tpm2-pcr-public-key.pem` where they remain accessible even after the system transitions out of the initrd environment into the host file system. Tools such as `systemd-cryptsetup@.service`, `systemd-cryptenroll` and `systemd-creds` will automatically use files present under these paths to unlock protected resources (encrypted storage or credentials) or bind encryption to booted kernels.
 
+The `[PCRSignature:initrd]` section covers only the enter-initrd phase. This is the policy used by systemd-cryptenroll to unseal the LUKS key from the TPM. Once the boot progresses past this phase, PCR 11 gets extended and the initrd signature no longer matches, so the TPM will refuse to release the key
+
+The `[PCRSignature:system]` section is separate and covers all four boot phases: enter-initrd, leave-initrd, sysinit, and ready. This is not used for LUKS unlock. It exists for systemd-tpm2-setup-early.service and systemd-tpm2-setup.service, which provision Storage Root Key (SRK) and NvPCR required by systemd-creds.
+
 Create `uki.conf`
 
 ```
@@ -374,6 +381,11 @@ PCRBanks=sha256
 Phases=enter-initrd
 PCRPrivateKey=/etc/kernel/pcr-initrd.key.pem
 PCRPublicKey=/etc/kernel/pcr-initrd.pub.pem
+
+[PCRSignature:system]
+Phases=enter-initrd leave-initrd sysinit ready
+PCRPrivateKey=/etc/kernel/pcr-system.key.pem
+PCRPublicKey=/etc/kernel/pcr-system.pub.pem
 ```
 
 Generate the key for the PCR policy
@@ -409,12 +421,20 @@ fallback_uki="/efi/EFI/Linux/arch-linux-fallback.efi"
 fallback_options="-S autodetect"
 ```
 
+> [!TIP]
+> Regarding the situation where other kernels (such as `extra/linux-zen`) are installed, the corresponding `/etc/mkinitcpio.d/linux-zen.preset` file should be edited.
+
 Finally, to build the **UKI**, make sure that the directory for the UKIs exist.
 For example, for the linux preset:
 ```
 # mkdir -p /efi/EFI/Linux
 ```
 
+> [!TIP]
+> All kernel UKI efi files are located in this directory, including `extra/linux-zen`.
+>
+> That is to say, regardless of which kernel you use, you only need to create this one directory.
+
 Now install the `lvm2` package:
 
 ```
@@ -427,6 +447,11 @@ Now, regenerate `initramfs`:
 # mkinitcpio -p linux
 ```
 
+> [!TIP]
+> Use the command `mkinitcpio -P` to generate all initramfs at once for multiple kernels.
+>
+> Or use `mkinitcpio -p linux-zen` for `extra/linux-zen`.
+
 ### 12. Configuring the boot loader
 
 Install `systemd-boot` with:
@@ -465,7 +490,8 @@ Now to configure secure boot , first install the `sbctl` utility:
 $ pacman -S sbctl
 ```
 
-**Note**: It might say completed installation with some errors, that's fine because sbctl can't find the key database, because there never was one.
+> [!NOTE]
+> It might say completed installation with some errors, that's fine because sbctl can't find the key database, because there never was one.
 
 Now run ```sbctl status``` and ensure setup mode is enabled.
 
@@ -502,7 +528,9 @@ delimitered string.
 Default: "db,KEK"
 ```
 
-**Warnings:** If using the flag `--tpm-eventlog`, results in a warning or error, just ignore it. It means that operation is not supported on your specific device. Trying to force it can soft brick your device.
+> [!WARNING]
+> If using the flag `--tpm-eventlog`, results in a warning or error, just ignore it.
+> It means that operation is not supported on your specific device. Trying to force it can soft brick your device.
 
 Some firmware is signed and verified with Microsoft's keys when secure boot is enabled. Not validating devices could brick them. To enroll your keys without enrolling Microsoft's, run: `sbctl enroll-keys`. Only do this if you know what you are doing.
 
@@ -588,9 +616,14 @@ We'll now enroll our system firmware and secure boot state.
 This would allow our TPM to unlock our encrypted drive, as long as the state hasn't changed.
 
 ```
-$ sudo systemd-cryptenroll --tpm2-device=auto --tpm2-pcrs=0+7 --tpm2-public-key /etc/kernel/pcr-initrd.pub.pem /dev/nvme0n1p2
+$ sudo systemd-cryptenroll --tpm2-device=auto --tpm2-pcrs=0+7 --tpm2-public-key /etc/kernel/pcr-initrd.pub.pem --tpm2-with-pin=yes /dev/nvme0n1p2
 ```
 
+> [!WARNING]
+> It is recommended to use a pin to unlock the TPM, instead of allowing it to unlock automatically, for more security.
+> Use `--tpm2-with-pin=no` **only** if you are comfortable with TPM unlocking without user interaction (this is the default behavior).
+> Do not use `--tpm2-pcrs=11` here. This option seals the LUKS key to the current raw PCR value and will break after kernel or initramfs updates.
+
 ```
 Additional Flags
 
@@ -599,7 +632,12 @@ When enrolling a TPM2 device, controls whether to require the user to enter a PI
 Note that incorrect PIN entry when unlocking increments the TPM dictionary attack lockout mechanism, and may lock out users for a prolonged time, depending on its configuration. The lockout mechanism is a global property of the TPM, systemd-cryptenroll does not control or configure the lockout mechanism. You may use tpm2-tss tools to inspect or configure the dictionary attack lockout, with tpm2_getcap(1) and tpm2_dictionarylockout(1) commands, respectively.
 ```
 
-**Note**: Including PCR0 in the PCRs can cause the entry to become invalid after every firmware update. This happens because PCR0 reflects measurements of the firmware, and any update to the firmware will change these measurements, invalidating the TPM2 entry. If you prefer to avoid this issue, you might exclude PCR0 and use only PCR7 or other suitable PCRs.
+> [!NOTE]
+> Including PCR0 in the PCRs can cause the entry to become invalid after every firmware update.
+> This happens because PCR0 reflects measurements of the firmware, and any update to the firmware will change these measurements, invalidating the TPM2 entry.
+> If you prefer to avoid this issue, you might exclude PCR0 and use only PCR7 or other suitable PCRs.
+>
+> For reference see discussion: [PCR_0_should_be_avoided](https://wiki.archlinux.org/title/Talk:Trusted_Platform_Module#PCR_0_should_be_avoided)
 
 Info on all additional PCRs can be found [here](https://wiki.archlinux.org/title/Trusted_Platform_Module#Accessing_PCR_registers).
 
@@ -612,7 +650,7 @@ Now if at some point later in time, our secure boot state has changed, the TPM w
 This can be done in a very short step and is less prone to error by running the following command:
 
 ```
-systemd-cryptenroll --wipe-slot=tpm2 /dev/<device> --tpm2-pcrs=0+7
+systemd-cryptenroll --wipe-slot=tpm2 /dev/<device> --tpm2-pcrs=0+7 --tpm2-public-key /etc/kernel/pcr-initrd.pub.pem --tpm2-with-pin=<yes/no>
 ```
 
 Or, if you prefer to do it manually, do the following:
@@ -653,7 +691,7 @@ $ sudo cryptsetup token remove --token-id 1 /dev/nvme0n1p2
 ```
 Here we specify `token-id` as `1` based on the previous output of `luksDump`. Specify it correspondingy depending on what the token number is on your output of `luksDump`.
 
-Now repeat the steps from [TPM enrollment](https://github.com/joelmathewthomas/archinstall-luks2-lvm2-secureboot-tpm2?tab=readme-ov-file#13-enrolling-the-tpm) to renroll to the TPM.
+Now repeat the steps from [TPM enrollment](https://github.com/joelmathewthomas/archinstall-luks2-lvm2-secureboot-tpm2?tab=readme-ov-file#16-enrolling-the-tpm) to renroll to the TPM.
 
 
 With this, the guide has mostly covered on how to install Arch Linux, Encrypt disk with LUKS2 , use logical volumes with LVM2, how to setup Secure Boot, and how to enroll the TPM.