From e1e618b9a0f9c23e9caa5933fa30ee3d33e00bfe Mon Sep 17 00:00:00 2001 From: "Jason A. Donenfeld" Date: Tue, 25 Oct 2022 02:43:18 +0200 Subject: [PATCH] device-tree: add re-randomization helper function When the system reboots, the rng-seed that the FDT has should be re-randomized, so that the new boot gets a new seed. Several architectures require this functionality, so export a function for injecting a new seed into the given FDT. Cc: Alistair Francis Cc: David Gibson Signed-off-by: Jason A. Donenfeld Reviewed-by: Alistair Francis Message-id: 20221025004327.568476-3-Jason@zx2c4.com Signed-off-by: Peter Maydell --- include/sysemu/device_tree.h | 9 +++++++++ softmmu/device_tree.c | 21 +++++++++++++++++++++ 2 files changed, 30 insertions(+) diff --git a/include/sysemu/device_tree.h b/include/sysemu/device_tree.h index e7c5441f56..ca5339beae 100644 --- a/include/sysemu/device_tree.h +++ b/include/sysemu/device_tree.h @@ -197,6 +197,15 @@ int qemu_fdt_setprop_sized_cells_from_array(void *fdt, qdt_tmp); \ }) + +/** + * qemu_fdt_randomize_seeds: + * @fdt: device tree blob + * + * Re-randomize all "rng-seed" properties with new seeds. + */ +void qemu_fdt_randomize_seeds(void *fdt); + #define FDT_PCI_RANGE_RELOCATABLE 0x80000000 #define FDT_PCI_RANGE_PREFETCHABLE 0x40000000 #define FDT_PCI_RANGE_ALIASED 0x20000000 diff --git a/softmmu/device_tree.c b/softmmu/device_tree.c index ce74f3d48d..30aa3aea9f 100644 --- a/softmmu/device_tree.c +++ b/softmmu/device_tree.c @@ -22,6 +22,7 @@ #include "qemu/option.h" #include "qemu/bswap.h" #include "qemu/cutils.h" +#include "qemu/guest-random.h" #include "sysemu/device_tree.h" #include "hw/loader.h" #include "hw/boards.h" @@ -680,3 +681,23 @@ void hmp_dumpdtb(Monitor *mon, const QDict *qdict) info_report("dtb dumped to %s", filename); } + +void qemu_fdt_randomize_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); + } + } +}