u-boot/cmd/kaslrseed.c
Chris Morgan fe3dde3e7b cmd: kaslrseed: add command to generate value from hwrng
Allow the kaslr-seed value in the chosen node to be set from a hardware
rng source.

Tested on a Rockchip PX30 (Odroid Go Advance), you must have loaded
the devicetree first and prepared it for editing. On my device the
workflow goes as follows:

setenv dtb_loadaddr "0x01f00000"
load mmc 0:1 ${dtb_loadaddr} rk3326-odroid-go2.dtb
fdt addr ${dtb_loadaddr}
fdt resize
kaslrseed

and the output can be seen here:
fdt print /chosen
chosen {
        kaslr-seed = <0x6f61df74 0x6f7b996c>;
        stdout-path = "serial2:115200n8";
};

Signed-off-by: Chris Morgan <macromorgan@hotmail.com>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
2021-12-24 10:54:56 +08:00

81 lines
1.8 KiB
C

// SPDX-License-Identifier: GPL-2.0+
/*
* The 'kaslrseed' command takes bytes from the hardware random number
* generator and uses them to set the kaslr-seed value in the chosen node.
*
* Copyright (c) 2021, Chris Morgan <macromorgan@hotmail.com>
*/
#include <common.h>
#include <command.h>
#include <dm.h>
#include <hexdump.h>
#include <malloc.h>
#include <rng.h>
#include <fdt_support.h>
static int do_kaslr_seed(struct cmd_tbl *cmdtp, int flag, int argc, char *const argv[])
{
size_t n = 0x8;
struct udevice *dev;
u64 *buf;
int nodeoffset;
int ret = CMD_RET_SUCCESS;
if (uclass_get_device(UCLASS_RNG, 0, &dev) || !dev) {
printf("No RNG device\n");
return CMD_RET_FAILURE;
}
buf = malloc(n);
if (!buf) {
printf("Out of memory\n");
return CMD_RET_FAILURE;
}
if (dm_rng_read(dev, buf, n)) {
printf("Reading RNG failed\n");
return CMD_RET_FAILURE;
}
if (!working_fdt) {
printf("No FDT memory address configured. Please configure\n"
"the FDT address via \"fdt addr <address>\" command.\n"
"Aborting!\n");
return CMD_RET_FAILURE;
}
ret = fdt_check_header(working_fdt);
if (ret < 0) {
printf("fdt_chosen: %s\n", fdt_strerror(ret));
return CMD_RET_FAILURE;
}
nodeoffset = fdt_find_or_add_subnode(working_fdt, 0, "chosen");
if (nodeoffset < 0) {
printf("Reading chosen node failed\n");
return CMD_RET_FAILURE;
}
ret = fdt_setprop(working_fdt, nodeoffset, "kaslr-seed", buf, sizeof(buf));
if (ret < 0) {
printf("Unable to set kaslr-seed on chosen node: %s\n", fdt_strerror(ret));
return CMD_RET_FAILURE;
}
free(buf);
return ret;
}
#ifdef CONFIG_SYS_LONGHELP
static char kaslrseed_help_text[] =
"[n]\n"
" - append random bytes to chosen kaslr-seed node\n";
#endif
U_BOOT_CMD(
kaslrseed, 1, 0, do_kaslr_seed,
"feed bytes from the hardware random number generator to the kaslr-seed",
kaslrseed_help_text
);