CONFIG_CRASH_DM_CRYPT has been introduced to support LUKS-encrypted device dump target by addressing two challenges [1], - Kdump kernel may not be able to decrypt the LUKS partition. For some machines, a system administrator may not have a chance to enter the password to decrypt the device in kdump initramfs after the 1st kernel crashes
- LUKS2 by default use the memory-hard Argon2 key derivation function which is quite memory-consuming compared to the limited memory reserved for kdump. To also enable this feature for ARM64 and PowerPC, the missing piece is to let the kdump kernel know where to find the dm-crypt keys which are randomly stored in memory reserved for kdump. Introduce a new device tree property dmcryptkeys [2] as similar to elfcorehdr to pass the memory address of the stored info of dm-crypt keys to the kdump kernel. Since this property is only needed by the kdump kernel, it won't be exposed to user space. [1] https://lore.kernel.org/all/[email protected]/ [2] https://github.com/devicetree-org/dt-schema/pull/181 Cc: Arnaud Lefebvre <[email protected]> Cc: Baoquan he <[email protected]> Cc: Dave Young <[email protected]> Cc: Kairui Song <[email protected]> Cc: Pingfan Liu <[email protected]> Cc: Andrew Morton <[email protected]> Cc: Krzysztof Kozlowski <[email protected]> Cc: Rob Herring <[email protected]> Cc: Thomas Staudt <[email protected]> Cc: Sourabh Jain <[email protected]> Cc: Will Deacon <[email protected]> Cc: Christophe Leroy (CS GROUP) <[email protected]> Signed-off-by: Coiby Xu <[email protected]> --- arch/arm64/kernel/machine_kexec_file.c | 4 ++++ arch/powerpc/kexec/elf_64.c | 4 ++++ drivers/of/fdt.c | 21 +++++++++++++++++++++ drivers/of/kexec.c | 19 +++++++++++++++++++ 4 files changed, 48 insertions(+) diff --git a/arch/arm64/kernel/machine_kexec_file.c b/arch/arm64/kernel/machine_kexec_file.c index fba260ad87a9..e31fabed378a 100644 --- a/arch/arm64/kernel/machine_kexec_file.c +++ b/arch/arm64/kernel/machine_kexec_file.c @@ -134,6 +134,10 @@ int load_other_segments(struct kimage *image, kexec_dprintk("Loaded elf core header at 0x%lx bufsz=0x%lx memsz=0x%lx\n", image->elf_load_addr, kbuf.bufsz, kbuf.memsz); + + ret = crash_load_dm_crypt_keys(image); + if (ret) + goto out_err; } #endif diff --git a/arch/powerpc/kexec/elf_64.c b/arch/powerpc/kexec/elf_64.c index 5d6d616404cf..ea50a072debf 100644 --- a/arch/powerpc/kexec/elf_64.c +++ b/arch/powerpc/kexec/elf_64.c @@ -79,6 +79,10 @@ static void *elf64_load(struct kimage *image, char *kernel_buf, goto out; } + ret = crash_load_dm_crypt_keys(image); + if (ret) + goto out; + /* Setup cmdline for kdump kernel case */ modified_cmdline = setup_kdump_cmdline(image, cmdline, cmdline_len); diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c index 331646d667b9..2967e4aff807 100644 --- a/drivers/of/fdt.c +++ b/drivers/of/fdt.c @@ -866,6 +866,26 @@ static void __init early_init_dt_check_for_elfcorehdr(unsigned long node) elfcorehdr_addr, elfcorehdr_size); } +static void __init early_init_dt_check_for_dmcryptkeys(unsigned long node) +{ + const char *prop_name = "linux,dmcryptkeys"; + const __be32 *prop; + + if (!IS_ENABLED(CONFIG_CRASH_DM_CRYPT)) + return; + + pr_debug("Looking for dmcryptkeys property... "); + + prop = of_get_flat_dt_prop(node, prop_name, NULL); + if (!prop) + return; + + dm_crypt_keys_addr = dt_mem_next_cell(dt_root_addr_cells, &prop); + + /* Property only accessible to crash dump kernel */ + fdt_delprop(initial_boot_params, node, prop_name); +} + static unsigned long chosen_node_offset = -FDT_ERR_NOTFOUND; /* @@ -1097,6 +1117,7 @@ int __init early_init_dt_scan_chosen(char *cmdline) early_init_dt_check_for_initrd(node); early_init_dt_check_for_elfcorehdr(node); + early_init_dt_check_for_dmcryptkeys(node); rng_seed = of_get_flat_dt_prop(node, "rng-seed", &l); if (rng_seed && l > 0) { diff --git a/drivers/of/kexec.c b/drivers/of/kexec.c index c4cf3552c018..fbd253f0d3c5 100644 --- a/drivers/of/kexec.c +++ b/drivers/of/kexec.c @@ -423,6 +423,25 @@ void *of_kexec_alloc_and_setup_fdt(const struct kimage *image, if (ret) goto out; + if (image->dm_crypt_keys_addr != 0) { + ret = fdt_appendprop_addrrange(fdt, 0, chosen_node, + "linux,dmcryptkeys", + image->dm_crypt_keys_addr, + image->dm_crypt_keys_sz); + + if (ret) + goto out; + + /* + * Avoid dmcryptkeys from being stomped on in kdump kernel by + * setting up memory reserve map. + */ + ret = fdt_add_mem_rsv(fdt, image->dm_crypt_keys_addr, + image->dm_crypt_keys_sz); + if (ret) + goto out; + } + #ifdef CONFIG_CRASH_DUMP /* add linux,usable-memory-range */ ret = fdt_appendprop_addrrange(fdt, 0, chosen_node, -- 2.53.0
