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    SubjectRe: [PATCH] Carry forward IMA measurement log on kexec on x86_64
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    On Mon, Apr 25, 2022 at 12:29:17PM -0400, Mimi Zohar wrote:
    > Hi Jonathan,
    >
    > On Fri, 2022-04-22 at 13:50 +0000, Jonathan McDowell wrote:
    > > On kexec file load Integrity Measurement Architecture (IMA) subsystem
    > > may verify the IMA signature of the kernel and initramfs, and measure
    > > it. The command line parameters passed to the kernel in the kexec call
    > > may also be measured by IMA. A remote attestation service can verify
    > > a TPM quote based on the TPM event log, the IMA measurement list, and
    > > the TPM PCR data. This can be achieved only if the IMA measurement log
    > > is carried over from the current kernel to the next kernel across
    > > the kexec call.
    > >
    > > powerpc and ARM64 both achieve this using device tree with a
    > > "linux,ima-kexec-buffer" node. x86 platforms generally don't make use of
    > > device tree, so the IMA infrastructure is extended to allow non device
    > > tree platforms to provide a log buffer. x86 then passes the IMA buffer
    > > to the new kernel via the setup_data mechanism.
    > >
    > > Signed-off-by: Jonathan McDowell <noodles@fb.com>
    >
    > FYI, after applying, building, and booting a kernel with this patch,
    > "kexec -s -l /boot/vmlinuz-5.18.0-rc4+ --reuse-cmdline --
    > initrd=/boot/initramfs-5.18.0-rc4+.img" properly loads the kernel, but
    > "kexec -s -e" fails to reboot, at least on a test laptop even with only
    > the "boot_aggregate" measurement record.
    >
    > Without enabling CONFIG_IMA_KEXEC, kexec boots properly.

    Thanks for giving it a try. At a guess your laptop is booting with
    EFI, whereas for my testing I was using qemu with legacy BIOS. I've
    managed to reproduce the issue with qemu+OVMF and isolated the mistake
    in the setup data calculation I made when EFI is involved. If you have
    time can you try with the below on top of the original patch?

    diff --git a/arch/x86/kernel/kexec-bzimage64.c b/arch/x86/kernel/kexec-bzimage64.c
    index 07625da33075..cdc73e081585 100644
    --- a/arch/x86/kernel/kexec-bzimage64.c
    +++ b/arch/x86/kernel/kexec-bzimage64.c
    @@ -277,7 +277,9 @@ setup_boot_parameters(struct kimage *image, struct boot_params *params,
    #ifdef CONFIG_IMA_KEXEC
    /* Setup IMA log buffer state */
    setup_ima_state(image, params, params_load_addr,
    - efi_setup_data_offset + ALIGN(efi_map_sz, 16) + sizeof(struct setup_data));
    + efi_setup_data_offset +
    + sizeof(struct setup_data) +
    + sizeof(struct efi_setup_data));
    #endif

    /* Setup EDD info */
    \
     
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