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

[Heinrich Schuchardt]

Am 15. Oktober 2021 14:54:03 MESZ schrieb Kever Yang <kever.yang at rock-chips.com>:
>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

This seems overly complicated. Why don't you add the seed in the board fixup routines in dependence on a Kconfig symbol.

Best regards

Heinrich


>>
>> 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
>>