On Tue, 2022-04-26 at 12:08 +0000, Jonathan McDowell wrote: > 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@xxxxxx> > > > > 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? Thank you! With the change, as expected there are two "boot_aggregate" records in the measurement list. With a custom policy, the measurement list verifies. # grep boot_aggregate /sys/kernel/security/ima/ascii_runtime_measurements 10 fe0b821290b1bd229e0d34c5571f48eeff403119 ima-sig sha1:a87d47e560d148cd1f4c8da677a84ddbe27f12f8 boot_aggregate 10 fe0b821290b1bd229e0d34c5571f48eeff403119 ima-sig sha1:a87d47e560d148cd1f4c8da677a84ddbe27f12f8 boot_aggregate # cat /sys/kernel/security/ima/runtime_measurements_count 5597 # evmctl ima_measurement /sys/kernel/security/ima/binary_runtime_measurements Matched per TPM bank calculated digest(s). FYI, the builtin "ima_policy=tcb" results in measurement violations. Normally, the measurement list can still be verified using the evmctl "--ignore-violations" option. For some reason with the "tcb" policy, the measurement list doesn't verify even with the "--ignore-violations" option after kexec. I assume this is a result of additional measurements being added after the kexec load, which aren't being carried across kexec. thanks, Mimi > > 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 */
