[PATCH v7 3/4] use fdt_kaslrseed function to de-duplicate code
Michal Simek
michal.simek at amd.com
Thu Jun 20 10:54:54 CEST 2024
On 6/18/24 23:06, Tim Harvey wrote:
> Use the fdt_kaslrseed function to deduplicate code doing the same thing.
>
> Note that the kalsrseed command (CMD_KASLRSEED) is likely pointless now
> but left in place in case boot scripts exist that rely on this command
> existing and returning success. An informational message is printed to
> alert users of this command that it is likely no longer needed.
>
> Note that the Kernel's EFI STUB only relies on EFI_RNG_PROTOCOL for
> randomization and completely ignores the kaslr-seed for its own
> randomness needs (i.e the randomization of the physical placement of
> the kernel). It gets weeded out from the DTB that gets handed over via
> efi_install_fdt() as it would also mess up the measured boot DTB TPM
> measurements as well.
>
> Signed-off-by: Tim Harvey <tharvey at gateworks.com>
> Reviewed-by: Simon Glass <sjg at chromium.org>
> Cc: Michal Simek <michal.simek at amd.com>
> Cc: Andy Yan <andy.yan at rock-chips.com>
> Cc: Akash Gajjar <gajjar04akash at gmail.com>
> Cc: Ilias Apalodimas <ilias.apalodimas at linaro.org>
> Cc: Simon Glass <sjg at chromium.org>
> Cc: Patrick Delaunay <patrick.delaunay at foss.st.com>
> Cc: Patrice Chotard <patrice.chotard at foss.st.com>
> Cc: Devarsh Thakkar <devarsht at ti.com>
> Cc: Heinrich Schuchardt <xypron.glpk at gmx.de>
> Cc: Hugo Villeneuve <hvilleneuve at dimonoff.com>
> Cc: Marek Vasut <marex at denx.de>
> Cc: Tom Rini <trini at konsulko.com>
> Cc: Chris Morgan <macromorgan at hotmail.com>
> ---
> v6:
> - collected tags
> v5:
> - fixed typo in commit message s/it's/its/
> - use cmd_process_error per Michal's suggestion
> v4:
> - add missing /n to notice in kaslrseed cmd
> - combine ints in declaration
> - remove unused vars from board/xilinx/common/board.c ft_board_setup
> v3:
> - skip if CONFIG_MEASURED_BOOT
> - fix skip for CONFIG_ARMV8_SEC_FIRMWARE_SUPPORT
> - pass in rng index and bool to specify overwrite
> - remove duplicate error strings printed outside of fdt_kaslrseed
> - added note to commit log about how EFI STUB weeds out kalsr-seed
> v2:
> - fix typo in commit msg
> - use stack for seed to avoid unecessary malloc/free
> - move to a library function and deduplicate code by using it
> elsewhere
> ---
> board/xilinx/common/board.c | 40 ------------------------------
> boot/pxe_utils.c | 34 +------------------------
> cmd/kaslrseed.c | 49 ++++++-------------------------------
> 3 files changed, 8 insertions(+), 115 deletions(-)
>
> diff --git a/board/xilinx/common/board.c b/board/xilinx/common/board.c
> index b47d2d23f913..098738017bab 100644
> --- a/board/xilinx/common/board.c
> +++ b/board/xilinx/common/board.c
> @@ -702,11 +702,6 @@ phys_addr_t board_get_usable_ram_top(phys_size_t total_size)
> #define MAX_RAND_SIZE 8
> int ft_board_setup(void *blob, struct bd_info *bd)
> {
> - size_t n = MAX_RAND_SIZE;
> - struct udevice *dev;
> - u8 buf[MAX_RAND_SIZE];
> - int nodeoffset, ret;
> -
> static const struct node_info nodes[] = {
> { "arm,pl353-nand-r2p1", MTD_DEV_TYPE_NAND, },
> };
> @@ -714,41 +709,6 @@ int ft_board_setup(void *blob, struct bd_info *bd)
> if (IS_ENABLED(CONFIG_FDT_FIXUP_PARTITIONS) && IS_ENABLED(CONFIG_NAND_ZYNQ))
> fdt_fixup_mtdparts(blob, nodes, ARRAY_SIZE(nodes));
>
> - if (uclass_get_device(UCLASS_RNG, 0, &dev) || !dev) {
> - debug("No RNG device\n");
> - return 0;
> - }
> -
> - if (dm_rng_read(dev, buf, n)) {
> - debug("Reading RNG failed\n");
> - return 0;
> - }
> -
> - if (!blob) {
> - debug("No FDT memory address configured. Please configure\n"
> - "the FDT address via \"fdt addr <address>\" command.\n"
> - "Aborting!\n");
> - return 0;
> - }
> -
> - ret = fdt_check_header(blob);
> - if (ret < 0) {
> - debug("fdt_chosen: %s\n", fdt_strerror(ret));
> - return ret;
> - }
> -
> - nodeoffset = fdt_find_or_add_subnode(blob, 0, "chosen");
> - if (nodeoffset < 0) {
> - debug("Reading chosen node failed\n");
> - return nodeoffset;
> - }
> -
> - ret = fdt_setprop(blob, nodeoffset, "kaslr-seed", buf, sizeof(buf));
> - if (ret < 0) {
> - debug("Unable to set kaslr-seed on chosen node: %s\n", fdt_strerror(ret));
> - return ret;
> - }
> -
> return 0;
> }
> #endif
> diff --git a/boot/pxe_utils.c b/boot/pxe_utils.c
> index 5c1c962ff4c1..38ca9b81a42d 100644
> --- a/boot/pxe_utils.c
> +++ b/boot/pxe_utils.c
> @@ -324,10 +324,6 @@ static void label_boot_kaslrseed(void)
> #if CONFIG_IS_ENABLED(DM_RNG)
> ulong fdt_addr;
> struct fdt_header *working_fdt;
> - size_t n = 0x8;
> - struct udevice *dev;
> - u64 *buf;
> - int nodeoffset;
> int err;
>
> /* Get the main fdt and map it */
> @@ -343,35 +339,7 @@ static void label_boot_kaslrseed(void)
> if (err <= 0)
> return;
>
> - if (uclass_get_device(UCLASS_RNG, 0, &dev) || !dev) {
> - printf("No RNG device\n");
> - return;
> - }
> -
> - nodeoffset = fdt_find_or_add_subnode(working_fdt, 0, "chosen");
> - if (nodeoffset < 0) {
> - printf("Reading chosen node failed\n");
> - return;
> - }
> -
> - buf = malloc(n);
> - if (!buf) {
> - printf("Out of memory\n");
> - return;
> - }
> -
> - if (dm_rng_read(dev, buf, n)) {
> - printf("Reading RNG failed\n");
> - goto err;
> - }
> -
> - err = fdt_setprop(working_fdt, nodeoffset, "kaslr-seed", buf, sizeof(buf));
> - if (err < 0) {
> - printf("Unable to set kaslr-seed on chosen node: %s\n", fdt_strerror(err));
> - goto err;
> - }
> -err:
> - free(buf);
> + fdt_kaslrseed(working_fdt, true);
> #endif
> return;
> }
> diff --git a/cmd/kaslrseed.c b/cmd/kaslrseed.c
> index 9acb8e163863..645cab2e74fd 100644
> --- a/cmd/kaslrseed.c
> +++ b/cmd/kaslrseed.c
> @@ -16,56 +16,21 @@
>
> 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;
> + int err = 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;
> - }
> + printf("Notice: a /chosen/kaslr-seed is automatically added to the device-tree when booted via booti/bootm/bootz therefore using this command is likely no longer needed\n");
>
> 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;
> + err = CMD_RET_FAILURE;
> + } else {
> + if (fdt_kaslrseed(working_fdt, true) < 0)
> + err = 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;
> + return cmd_process_error(cmdtp, err);
> }
>
> U_BOOT_LONGHELP(kaslrseed,
Acked-by: Michal Simek <michal.simek at amd.com>
Thanks,
Michal
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