When the system reboots, the rng-seed that the FDT has should be
re-randomized, so that the new boot gets a new seed. Since the FDT is in
the ROM region at this point, we add a hook right after the ROM has been
added, so that we have a pointer to that copy of the FDT. When the
reboot happens, we then look for RNG seeds and replace their contents
with new random data.
Cc: Peter Maydell <peter.mayd...@linaro.org>
Signed-off-by: Jason A. Donenfeld <ja...@zx2c4.com>
---
hw/arm/boot.c | 22 ++++++++++++++++++++++
1 file changed, 22 insertions(+)
diff --git a/hw/arm/boot.c b/hw/arm/boot.c
index ada2717f76..2836db4abb 100644
--- a/hw/arm/boot.c
+++ b/hw/arm/boot.c
@@ -25,6 +25,7 @@
#include "qemu/config-file.h"
#include "qemu/option.h"
#include "qemu/units.h"
+#include "qemu/guest-random.h"
/* Kernel boot protocol is specified in the kernel docs
* Documentation/arm/Booting and Documentation/arm64/booting.txt
@@ -529,6 +530,26 @@ static void fdt_add_psci_node(void *fdt)
qemu_fdt_setprop_cell(fdt, "/psci", "migrate", migrate_fn);
}
+static void rerandomize_fdt_seeds(void *fdt)
+{
+ int noffset, poffset, len;
+ const char *name;
+ uint8_t *data;
+
+ for (noffset = fdt_next_node(fdt, 0, NULL);
+ noffset >= 0;
+ noffset = fdt_next_node(fdt, noffset, NULL)) {
+ for (poffset = fdt_first_property_offset(fdt, noffset);
+ poffset >= 0;
+ poffset = fdt_next_property_offset(fdt, poffset)) {
+ data = (uint8_t *)fdt_getprop_by_offset(fdt, poffset, &name, &len);
+ if (!data || strcmp(name, "rng-seed"))
+ continue;
+ qemu_guest_getrandom_nofail(data, len);
+ }
+ }
+}
+
int arm_load_dtb(hwaddr addr, const struct arm_boot_info *binfo,
hwaddr addr_limit, AddressSpace *as, MachineState *ms)
{
@@ -683,6 +704,7 @@ int arm_load_dtb(hwaddr addr, const struct arm_boot_info
*binfo,
* the DTB is copied again upon reset, even if addr points into RAM.
*/
rom_add_blob_fixed_as("dtb", fdt, size, addr, as);
+ qemu_register_reset(rerandomize_fdt_seeds, rom_ptr_for_as(as, addr, size));
g_free(fdt);
--
2.37.3
