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
do_kaslr_seed(struct cmd_tbl * cmdtp,int flag,int argc,char * const argv[])17 static 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
71 #ifdef CONFIG_SYS_LONGHELP
72 static char kaslrseed_help_text[] =
73 "[n]\n"
74 " - append random bytes to chosen kaslr-seed node\n";
75 #endif
76
77 U_BOOT_CMD(
78 kaslrseed, 1, 0, do_kaslr_seed,
79 "feed bytes from the hardware random number generator to the kaslr-seed",
80 kaslrseed_help_text
81 );
82