[PATCH 1/2] cmd: kaslrseed: add command to generate value from hwrng

[Kever Yang]

Reviewed-by: Kever Yang <kever.yang at rock-chips.com>


Thanks,
- Kever

Chris Morgan <macroalpha82 at gmail.com> 于2021年8月26日周四 上午12:23写道：
>
> From: Chris Morgan <macromorgan at hotmail.com>
>
> 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 ${dtb_loadaddr}
> fdt resize
> kaslrseed
>
> and the output can be seen here:
> fdt print /chosen
> chosen {
>         kaslr-seed = <0x6f61df74 0x6f7b996c>;
>         stdout-path = "serial2:115200n8";
> };
>
> Signed-off-by: Chris Morgan <macromorgan at hotmail.com>
> ---
>  cmd/Kconfig     |  7 +++++
>  cmd/Makefile    |  1 +
>  cmd/kaslrseed.c | 81 +++++++++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 89 insertions(+)
>  create mode 100644 cmd/kaslrseed.c
>
> diff --git a/cmd/Kconfig b/cmd/Kconfig
> index ffef3cc76c..e62adff939 100644
> --- a/cmd/Kconfig
> +++ b/cmd/Kconfig
> @@ -1790,6 +1790,13 @@ config CMD_RNG
>         help
>           Print bytes from the hardware random number generator.
>
> +config CMD_KASLRSEED
> +       bool "kaslrseed"
> +       depends on DM_RNG
> +       help
> +         Set the kaslr-seed in the chosen node with entropy provided by a
> +         hardware random number generator.
> +
>  config CMD_SLEEP
>         bool "sleep"
>         default y
> diff --git a/cmd/Makefile b/cmd/Makefile
> index ed3669411e..34cbda72f5 100644
> --- a/cmd/Makefile
> +++ b/cmd/Makefile
> @@ -131,6 +131,7 @@ obj-$(CONFIG_CMD_REGINFO) += reginfo.o
>  obj-$(CONFIG_CMD_REISER) += reiser.o
>  obj-$(CONFIG_CMD_REMOTEPROC) += remoteproc.o
>  obj-$(CONFIG_CMD_RNG) += rng.o
> +obj-$(CONFIG_CMD_KASLRSEED) += kaslrseed.o
>  obj-$(CONFIG_CMD_ROCKUSB) += rockusb.o
>  obj-$(CONFIG_CMD_RTC) += rtc.o
>  obj-$(CONFIG_SANDBOX) += host.o
> diff --git a/cmd/kaslrseed.c b/cmd/kaslrseed.c
> new file mode 100644
> index 0000000000..27c2648c91
> --- /dev/null
> +++ b/cmd/kaslrseed.c
> @@ -0,0 +1,81 @@
> +// 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 at 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
> +);
> --
> 2.25.1
>