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// 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 <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;
}
U_BOOT_LONGHELP(kaslrseed,
"[n]\n"
" - append random bytes to chosen kaslr-seed node\n");
U_BOOT_CMD(
kaslrseed, 1, 0, do_kaslr_seed,
"feed bytes from the hardware random number generator to the kaslr-seed",
kaslrseed_help_text
);
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