From: Dhananjay Phadke dphadke@linux.microsoft.com
Add support for KASLR seed from the RNG device. Invokes dm_rng_read() API to read 8-bytes of random bytes. Performs the FDT fixup using event spy. To enable use CONFIG_KASLR_RNG_SEED
Signed-off-by: Dhananjay Phadke dphadke@linux.microsoft.com Signed-off-by: Drew Kluemke ankluemk@microsoft.com Signed-off-by: Sean Edmond seanedmond@microsoft.com --- common/fdt_support.c | 36 ++++++++++++++++++++++++++++++++++++ lib/Kconfig | 7 +++++++ 2 files changed, 43 insertions(+)
diff --git a/common/fdt_support.c b/common/fdt_support.c index 52be4375b4..09ce582865 100644 --- a/common/fdt_support.c +++ b/common/fdt_support.c @@ -12,7 +12,10 @@ #include <log.h> #include <mapmem.h> #include <net.h> +#include <rng.h> #include <stdio_dev.h> +#include <dm/device.h> +#include <dm/uclass.h> #include <dm/ofnode.h> #include <linux/ctype.h> #include <linux/types.h> @@ -650,6 +653,39 @@ int fdt_fixup_kaslr_seed(ofnode node, const u8 *seed, int len) return 0; }
+int fdt_rng_kaslr_seed(void *ctx, struct event *event) +{ + u8 rand[8] = {0}; + struct udevice *dev; + int ret; + oftree tree = event->data.ft_fixup.tree; + ofnode root_node = oftree_root(tree); + + ret = uclass_first_device_err(UCLASS_RNG, &dev); + if (ret) { + printf("ERROR: Failed to find RNG device\n"); + return ret; + } + + ret = dm_rng_read(dev, rand, sizeof(rand)); + if (ret) { + printf("ERROR: RNG read failed, ret=%d\n", ret); + return ret; + } + + ret = fdt_fixup_kaslr_seed(root_node, rand, sizeof(rand)); + if (ret) { + printf("ERROR: failed to add kaslr-seed to fdt\n"); + return ret; + } + + return 0; +} + +#if defined(CONFIG_KASLR_RNG_SEED) +EVENT_SPY(EVT_FT_FIXUP, fdt_rng_kaslr_seed); +#endif + int fdt_record_loadable(void *blob, u32 index, const char *name, uintptr_t load_addr, u32 size, uintptr_t entry_point, const char *type, const char *os, const char *arch) diff --git a/lib/Kconfig b/lib/Kconfig index 3926652db6..545a14343e 100644 --- a/lib/Kconfig +++ b/lib/Kconfig @@ -465,6 +465,13 @@ config VPL_TPM for the low-level TPM interface, but only one TPM is supported at a time by the TPM library.
+config KASLR_RNG_SEED + bool "Use RNG driver for KASLR random seed" + depends on DM_RNG + help + This enables support for using the RNG driver as entropy source for + KASLR seed populated in kernel's device tree. + endmenu
menu "Android Verified Boot"