For measured be boot we must avoid any volatile values in the device-tree. We already delete /chosen/kaslr-seed if we provide and EFI RNG protocol.
Additionally remove /chosen/rng-seed provided by QEMU or U-Boot. Signed-off-by: Heinrich Schuchardt <heinrich.schucha...@canonical.com> --- include/efi_loader.h | 2 +- lib/efi_loader/efi_dt_fixup.c | 15 ++++++++++----- lib/efi_loader/efi_helper.c | 2 +- 3 files changed, 12 insertions(+), 7 deletions(-) diff --git a/include/efi_loader.h b/include/efi_loader.h index f84852e384f..511281e150e 100644 --- a/include/efi_loader.h +++ b/include/efi_loader.h @@ -567,7 +567,7 @@ efi_status_t EFIAPI efi_convert_pointer(efi_uintn_t debug_disposition, /* Carve out DT reserved memory ranges */ void efi_carve_out_dt_rsv(void *fdt); /* Purge unused kaslr-seed */ -void efi_try_purge_kaslr_seed(void *fdt); +void efi_try_purge_rng_seed(void *fdt); /* Called by bootefi to make console interface available */ efi_status_t efi_console_register(void); /* Called by efi_init_obj_list() to proble all block devices */ diff --git a/lib/efi_loader/efi_dt_fixup.c b/lib/efi_loader/efi_dt_fixup.c index 9d017804eea..8f9e8dbd1ec 100644 --- a/lib/efi_loader/efi_dt_fixup.c +++ b/lib/efi_loader/efi_dt_fixup.c @@ -41,7 +41,7 @@ static void efi_reserve_memory(u64 addr, u64 size, bool nomap) } /** - * efi_try_purge_kaslr_seed() - Remove unused kaslr-seed + * efi_try_purge_rng_seed() - Remove unused kaslr-seed, rng-seed * * Kernel's EFI STUB only relies on EFI_RNG_PROTOCOL for randomization * and completely ignores the kaslr-seed for its own randomness needs @@ -51,8 +51,9 @@ static void efi_reserve_memory(u64 addr, u64 size, bool nomap) * * @fdt: Pointer to device tree */ -void efi_try_purge_kaslr_seed(void *fdt) +void efi_try_purge_rng_seed(void *fdt) { + const char * const prop[] = {"kaslr-seed", "rng-seed"}; const efi_guid_t efi_guid_rng_protocol = EFI_RNG_PROTOCOL_GUID; struct efi_handler *handler; efi_status_t ret; @@ -67,9 +68,13 @@ void efi_try_purge_kaslr_seed(void *fdt) if (nodeoff < 0) return; - err = fdt_delprop(fdt, nodeoff, "kaslr-seed"); - if (err < 0 && err != -FDT_ERR_NOTFOUND) - log_err("Error deleting kaslr-seed\n"); + for (const char * const *pos = prop; pos < &prop[ARRAY_SIZE(prop)]; + ++pos) { + err = fdt_delprop(fdt, nodeoff, *pos); + if (err < 0 && err != -FDT_ERR_NOTFOUND) + log_err("Error deleting %s\n", *pos); + log_debug("Deleted /chosen/%s\n", *pos); + } } /** diff --git a/lib/efi_loader/efi_helper.c b/lib/efi_loader/efi_helper.c index 96f847652ec..a481eb4b7e3 100644 --- a/lib/efi_loader/efi_helper.c +++ b/lib/efi_loader/efi_helper.c @@ -522,7 +522,7 @@ efi_status_t efi_install_fdt(void *fdt) /* Create memory reservations as indicated by the device tree */ efi_carve_out_dt_rsv(fdt); - efi_try_purge_kaslr_seed(fdt); + efi_try_purge_rng_seed(fdt); if (CONFIG_IS_ENABLED(EFI_TCG2_PROTOCOL_MEASURE_DTB)) { ret = efi_tcg2_measure_dtb(fdt); -- 2.45.2