1// SPDX-License-Identifier: GPL-2.0+
2/*
3 * The 'kaslrseed' command takes bytes from the hardware random number
4 * generator and uses them to set the kaslr-seed value in the chosen node.
5 *
6 * Copyright (c) 2021, Chris Morgan <macromorgan@hotmail.com>
7 */
8
9#include <common.h>
10#include <command.h>
11#include <dm.h>
12#include <hexdump.h>
13#include <malloc.h>
14#include <rng.h>
15#include <fdt_support.h>
16
17static int do_kaslr_seed(struct cmd_tbl *cmdtp, int flag, int argc, char *const argv[])
18{
19	size_t n = 0x8;
20	struct udevice *dev;
21	u64 *buf;
22	int nodeoffset;
23	int ret = CMD_RET_SUCCESS;
24
25	if (uclass_get_device(UCLASS_RNG, 0, &dev) || !dev) {
26		printf("No RNG device\n");
27		return CMD_RET_FAILURE;
28	}
29
30	buf = malloc(n);
31	if (!buf) {
32		printf("Out of memory\n");
33		return CMD_RET_FAILURE;
34	}
35
36	if (dm_rng_read(dev, buf, n)) {
37		printf("Reading RNG failed\n");
38		return CMD_RET_FAILURE;
39	}
40
41	if (!working_fdt) {
42		printf("No FDT memory address configured. Please configure\n"
43		       "the FDT address via \"fdt addr <address>\" command.\n"
44		       "Aborting!\n");
45		return CMD_RET_FAILURE;
46	}
47
48	ret = fdt_check_header(working_fdt);
49	if (ret < 0) {
50		printf("fdt_chosen: %s\n", fdt_strerror(ret));
51		return CMD_RET_FAILURE;
52	}
53
54	nodeoffset = fdt_find_or_add_subnode(working_fdt, 0, "chosen");
55	if (nodeoffset < 0) {
56		printf("Reading chosen node failed\n");
57		return CMD_RET_FAILURE;
58	}
59
60	ret = fdt_setprop(working_fdt, nodeoffset, "kaslr-seed", buf, sizeof(buf));
61	if (ret < 0) {
62		printf("Unable to set kaslr-seed on chosen node: %s\n", fdt_strerror(ret));
63		return CMD_RET_FAILURE;
64	}
65
66	free(buf);
67
68	return ret;
69}
70
71U_BOOT_LONGHELP(kaslrseed,
72	"[n]\n"
73	"  - append random bytes to chosen kaslr-seed node\n");
74
75U_BOOT_CMD(
76	kaslrseed, 1, 0, do_kaslr_seed,
77	"feed bytes from the hardware random number generator to the kaslr-seed",
78	kaslrseed_help_text
79);
80