From b69a2afd5afce9bf6d56e349d6ab592c916e20f2 Mon Sep 17 00:00:00 2001 From: Jonathan McDowell Date: Thu, 30 Jun 2022 08:36:12 +0000 Subject: x86/kexec: Carry forward IMA measurement log on kexec On kexec file load, the 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 use the setup_data mechanism to pass the IMA buffer to the new kernel. Signed-off-by: Jonathan McDowell Signed-off-by: Borislav Petkov Reviewed-by: Mimi Zohar # IMA function definitions Link: https://lore.kernel.org/r/YmKyvlF3my1yWTvK@noodles-fedora-PC23Y6EG --- arch/x86/kernel/setup.c | 63 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 63 insertions(+) (limited to 'arch/x86/kernel/setup.c') diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c index bd6c6fd373ae..53f863f28b4c 100644 --- a/arch/x86/kernel/setup.c +++ b/arch/x86/kernel/setup.c @@ -11,6 +11,7 @@ #include #include #include +#include #include #include #include @@ -140,6 +141,11 @@ __visible unsigned long mmu_cr4_features __ro_after_init; __visible unsigned long mmu_cr4_features __ro_after_init = X86_CR4_PAE; #endif +#ifdef CONFIG_IMA +static phys_addr_t ima_kexec_buffer_phys; +static size_t ima_kexec_buffer_size; +#endif + /* Boot loader ID and version as integers, for the benefit of proc_dointvec */ int bootloader_type, bootloader_version; @@ -330,6 +336,60 @@ static void __init reserve_initrd(void) } #endif /* CONFIG_BLK_DEV_INITRD */ +static void __init add_early_ima_buffer(u64 phys_addr) +{ +#ifdef CONFIG_IMA + struct ima_setup_data *data; + + data = early_memremap(phys_addr + sizeof(struct setup_data), sizeof(*data)); + if (!data) { + pr_warn("setup: failed to memremap ima_setup_data entry\n"); + return; + } + + if (data->size) { + memblock_reserve(data->addr, data->size); + ima_kexec_buffer_phys = data->addr; + ima_kexec_buffer_size = data->size; + } + + early_memunmap(data, sizeof(*data)); +#else + pr_warn("Passed IMA kexec data, but CONFIG_IMA not set. Ignoring.\n"); +#endif +} + +#if defined(CONFIG_HAVE_IMA_KEXEC) && !defined(CONFIG_OF_FLATTREE) +int __init ima_free_kexec_buffer(void) +{ + int rc; + + if (!ima_kexec_buffer_size) + return -ENOENT; + + rc = memblock_phys_free(ima_kexec_buffer_phys, + ima_kexec_buffer_size); + if (rc) + return rc; + + ima_kexec_buffer_phys = 0; + ima_kexec_buffer_size = 0; + + return 0; +} + +int __init ima_get_kexec_buffer(void **addr, size_t *size) +{ + if (!ima_kexec_buffer_size) + return -ENOENT; + + *addr = __va(ima_kexec_buffer_phys); + *size = ima_kexec_buffer_size; + + return 0; +} +#endif + static void __init parse_setup_data(void) { struct setup_data *data; @@ -355,6 +415,9 @@ static void __init parse_setup_data(void) case SETUP_EFI: parse_efi_setup(pa_data, data_len); break; + case SETUP_IMA: + add_early_ima_buffer(pa_data); + break; default: break; } -- cgit v1.2.3