[PATCH 1/3] fdt: common API to populate kaslr seed
Sean Edmond
seanedmond at linux.microsoft.com
Thu Aug 10 00:35:30 CEST 2023
On 2023-08-08 7:03 p.m., Simon Glass wrote:
> Hi,
>
> On Fri, 4 Aug 2023 at 17:34, <seanedmond at linux.microsoft.com> wrote:
>> From: Dhananjay Phadke <dphadke at linux.microsoft.com>
>>
>> fdt_fixup_kaslr_seed() will update given FDT with random seed value.
>> Source for random seed can be TPM or RNG driver in u-boot or sec
>> firmware (ARM).
>>
>> Signed-off-by: Dhananjay Phadke <dphadke at linux.microsoft.com>
>> ---
>> arch/arm/cpu/armv8/sec_firmware.c | 32 +++++++------------------------
>> common/fdt_support.c | 31 ++++++++++++++++++++++++++++++
>> include/fdt_support.h | 3 +++
>> 3 files changed, 41 insertions(+), 25 deletions(-)
> We need to find a way to use the ofnode API here.
>
>> diff --git a/arch/arm/cpu/armv8/sec_firmware.c b/arch/arm/cpu/armv8/sec_firmware.c
>> index c0e8726346..84ba49924e 100644
>> --- a/arch/arm/cpu/armv8/sec_firmware.c
>> +++ b/arch/arm/cpu/armv8/sec_firmware.c
>> @@ -411,46 +411,28 @@ int sec_firmware_init(const void *sec_firmware_img,
>> /*
>> * fdt_fix_kaslr - Add kalsr-seed node in Device tree
>> * @fdt: Device tree
>> - * @eret: 0 in case of error, 1 for success
>> + * @eret: 0 for success
>> */
>> int fdt_fixup_kaslr(void *fdt)
> You could pass an oftree to this function, e.g. obtained with:
>
> oftree_from_fdt(fdt)
The common API I added is fdt_fixup_kaslr_seed(), which was added to
"common/fdt_support.c".
There are 3 callers:
sec_firmware_init()->fdt_fixup_kaslr_seed()
do_kaslr_seed()->fdt_fixup_kaslr_seed()
image_setup_libfdt()->fdt_tpm_kaslr_seed->fdt_fixup_kaslr_seed()
I think the ask is to create a common API that uses the ofnode API. So,
instead of fdt_fixup_kaslr_seed() I can create
ofnode_fixup_kaslr_seed()? Where should it live? Are you also wanting
the callers (eg. fdt_tpm_kaslr_seed, fdt_fixup_kaslr) to take oftree as
input too?
>
>> {
>> - int nodeoffset;
>> - int err, ret = 0;
>> - u8 rand[8];
>> + int ret = 0;
>>
>> #if defined(CONFIG_ARMV8_SEC_FIRMWARE_SUPPORT)
>> + u8 rand[8];
>> +
>> /* Check if random seed generation is supported */
>> if (sec_firmware_support_hwrng() == false) {
>> printf("WARNING: SEC firmware not running, no kaslr-seed\n");
>> - return 0;
>> + return -EOPNOTSUPP;
>> }
>>
>> err = sec_firmware_get_random(rand, 8);
>> if (err < 0) {
>> printf("WARNING: No random number to set kaslr-seed\n");
>> - return 0;
>> - }
>> -
>> - err = fdt_check_header(fdt);
>> - if (err < 0) {
>> - printf("fdt_chosen: %s\n", fdt_strerror(err));
>> - return 0;
>> + return ret;
>> }
>>
>> - /* find or create "/chosen" node. */
>> - nodeoffset = fdt_find_or_add_subnode(fdt, 0, "chosen");
>> - if (nodeoffset < 0)
>> - return 0;
>> -
>> - err = fdt_setprop(fdt, nodeoffset, "kaslr-seed", rand,
>> - sizeof(rand));
>> - if (err < 0) {
>> - printf("WARNING: can't set kaslr-seed %s.\n",
>> - fdt_strerror(err));
>> - return 0;
>> - }
>> - ret = 1;
>> + ret = fdt_fixup_kaslr_seed(fdt, rand, sizeof(rand));
>> #endif
>>
>> return ret;
>> diff --git a/common/fdt_support.c b/common/fdt_support.c
>> index 5e49078f8c..35d4f26dbd 100644
>> --- a/common/fdt_support.c
>> +++ b/common/fdt_support.c
>> @@ -631,6 +631,37 @@ void fdt_fixup_ethernet(void *fdt)
>> }
>> }
>>
>> +/*
>> + * fdt_fix_kaslr_seed - Add kalsr-seed node in Device tree
>> + * @fdt: Device tree
>> + * @eret: 0 for success
>> + */
>> +int fdt_fixup_kaslr_seed(void *fdt, const u8 *seed, int len)
>> +{
>> + int nodeoffset;
>> + int err;
>> +
>> + err = fdt_check_header(fdt);
>> + if (err < 0) {
>> + printf("fdt_chosen: %s\n", fdt_strerror(err));
>> + return err;
>> + }
>> +
>> + /* find or create "/chosen" node. */
>> + nodeoffset = fdt_find_or_add_subnode(fdt, 0, "chosen");
>> + if (nodeoffset < 0)
>> + return -ENOENT;
>> +
>> + err = fdt_setprop(fdt, nodeoffset, "kaslr-seed", seed, len);
>> + if (err < 0) {
>> + printf("WARNING: can't set kaslr-seed %s.\n",
>> + fdt_strerror(err));
>> + return err;
>> + }
>> +
>> + return 0;
>> +}
>> +
>> int fdt_record_loadable(void *blob, u32 index, const char *name,
>> uintptr_t load_addr, u32 size, uintptr_t entry_point,
>> const char *type, const char *os, const char *arch)
>> diff --git a/include/fdt_support.h b/include/fdt_support.h
>> index 2cd8366898..d74ef4e0a7 100644
>> --- a/include/fdt_support.h
>> +++ b/include/fdt_support.h
>> @@ -121,6 +121,9 @@ static inline int fdt_fixup_memory_banks(void *blob, u64 start[], u64 size[],
>> #endif
>>
>> void fdt_fixup_ethernet(void *fdt);
>> +
>> +int fdt_fixup_kaslr_seed(void *fdt, const u8 *seed, int len);
> Please get in the habit of adding full comments to exported functions.
>
>> +
>> int fdt_find_and_setprop(void *fdt, const char *node, const char *prop,
>> const void *val, int len, int create);
>> void fdt_fixup_qe_firmware(void *fdt);
>> --
>> 2.40.0
>>
> Regards,
> Simon
>
>
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