Hi Tim,
On Thu, 28 Mar 2024 at 19:01, Tim Harvey <thar...@gateworks.com> wrote:
>
> For pcr_read and pcr_extend commands allow the digest algorithm to be
> specified by an additional argument. If not specified it will default to
> SHA256 for backwards compatibility.
>
> A follow-on to this could be to extend all PCR banks with the detected
> algo when the <digest_algo> argument is 'auto'.
>
> Signed-off-by: Tim Harvey <thar...@gateworks.com>
> ---
> v2:
> - use tpm2_algorithm_to_len
> - use enum tpm2_algorithms
> - make function names and parameter names more consistent with existing
> tpm-v2 functions
> - fix various spelling errors
> ---
> cmd/tpm-v2.c | 49 ++++++++++++++++++++++++++++++++++--------------
> include/tpm-v2.h | 18 ++++++++++++++++++
> lib/tpm-v2.c | 34 +++++++++++++++++++++++++++++++++
> 3 files changed, 87 insertions(+), 14 deletions(-)
>
> diff --git a/cmd/tpm-v2.c b/cmd/tpm-v2.c
> index 7e479b9dfe36..2343b4d9cb9e 100644
> --- a/cmd/tpm-v2.c
> +++ b/cmd/tpm-v2.c
> @@ -99,11 +99,19 @@ static int do_tpm2_pcr_extend(struct cmd_tbl *cmdtp, int
> flag, int argc,
> struct tpm_chip_priv *priv;
> u32 index = simple_strtoul(argv[1], NULL, 0);
> void *digest = map_sysmem(simple_strtoul(argv[2], NULL, 0), 0);
> + int algo = TPM2_ALG_SHA256;
> + int algo_len;
> int ret;
> u32 rc;
>
> - if (argc != 3)
> + if (argc < 3 || argc > 4)
> return CMD_RET_USAGE;
> + if (argc == 4) {
> + algo = tpm2_name_to_algorithm(argv[3]);
> + if (algo < 0)
> + return CMD_RET_FAILURE;
> + }
> + algo_len = tpm2_algorithm_to_len(algo);
>
> ret = get_tpm(&dev);
> if (ret)
> @@ -116,8 +124,12 @@ static int do_tpm2_pcr_extend(struct cmd_tbl *cmdtp, int
> flag, int argc,
> if (index >= priv->pcr_count)
> return -EINVAL;
>
> - rc = tpm2_pcr_extend(dev, index, TPM2_ALG_SHA256, digest,
> - TPM2_DIGEST_LEN);
> + rc = tpm2_pcr_extend(dev, index, algo, digest, algo_len);
> + if (!rc) {
> + printf("PCR #%u extended with %d byte %s digest\n", index,
> + algo_len, tpm2_algorithm_name(algo));
> + print_byte_string(digest, algo_len);
> + }
>
> unmap_sysmem(digest);
>
> @@ -127,15 +139,23 @@ static int do_tpm2_pcr_extend(struct cmd_tbl *cmdtp,
> int flag, int argc,
> static int do_tpm_pcr_read(struct cmd_tbl *cmdtp, int flag, int argc,
> char *const argv[])
> {
> + enum tpm2_algorithms algo = TPM2_ALG_SHA256;
> struct udevice *dev;
> struct tpm_chip_priv *priv;
> u32 index, rc;
> + int algo_len;
> unsigned int updates;
> void *data;
> int ret;
>
> - if (argc != 3)
> + if (argc < 3 || argc > 4)
> return CMD_RET_USAGE;
> + if (argc == 4) {
> + algo = tpm2_name_to_algorithm(argv[3]);
> + if (algo < 0)
> + return CMD_RET_FAILURE;
> + }
> + algo_len = tpm2_algorithm_to_len(algo);
>
> ret = get_tpm(&dev);
> if (ret)
> @@ -151,11 +171,12 @@ static int do_tpm_pcr_read(struct cmd_tbl *cmdtp, int
> flag, int argc,
>
> data = map_sysmem(simple_strtoul(argv[2], NULL, 0), 0);
>
> - rc = tpm2_pcr_read(dev, index, priv->pcr_select_min, TPM2_ALG_SHA256,
> - data, TPM2_DIGEST_LEN, &updates);
> + rc = tpm2_pcr_read(dev, index, priv->pcr_select_min, algo,
> + data, algo_len, &updates);
> if (!rc) {
> - printf("PCR #%u content (%u known updates):\n", index,
> updates);
> - print_byte_string(data, TPM2_DIGEST_LEN);
> + printf("PCR #%u %s %d byte content (%u known updates):\n",
> index,
> + tpm2_algorithm_name(algo), algo_len, updates);
> + print_byte_string(data, algo_len);
> }
>
> unmap_sysmem(data);
> @@ -415,14 +436,14 @@ U_BOOT_CMD(tpm2, CONFIG_SYS_MAXARGS, 1, do_tpm, "Issue
> a TPMv2.x command",
> " <hierarchy> is one of:\n"
> " * TPM2_RH_LOCKOUT\n"
> " * TPM2_RH_PLATFORM\n"
> -"pcr_extend <pcr> <digest_addr>\n"
> -" Extend PCR #<pcr> with digest at <digest_addr>.\n"
> +"pcr_extend <pcr> <digest_addr> [<digest_algo>]\n"
> +" Extend PCR #<pcr> with digest at <digest_addr> with digest_algo.\n"
> " <pcr>: index of the PCR\n"
> -" <digest_addr>: address of a 32-byte SHA256 digest\n"
> -"pcr_read <pcr> <digest_addr>\n"
> -" Read PCR #<pcr> to memory address <digest_addr>.\n"
> +" <digest_addr>: address of digest of digest_algo type (defaults to
> SHA256)\n"
> +"pcr_read <pcr> <digest_addr> [<digest_algo>]\n"
> +" Read PCR #<pcr> to memory address <digest_addr> with <digest_algo>.\n"
> " <pcr>: index of the PCR\n"
> -" <digest_addr>: address to store the a 32-byte SHA256 digest\n"
> +" <digest_addr>: address of digest of digest_algo type (defaults to
> SHA256)\n"
> "get_capability <capability> <property> <addr> <count>\n"
> " Read and display <count> entries indexed by <capability>/<property>.\n"
> " Values are 4 bytes long and are written at <addr>.\n"
> diff --git a/include/tpm-v2.h b/include/tpm-v2.h
> index 33dd103767c4..933882fcbf97 100644
> --- a/include/tpm-v2.h
> +++ b/include/tpm-v2.h
> @@ -965,4 +965,22 @@ u32 tpm2_enable_nvcommits(struct udevice *dev, uint
> vendor_cmd,
> */
> u32 tpm2_auto_start(struct udevice *dev);
>
> +/**
> + * tpm2_name_to_algorithm() - Return an algorithm id given a supported
> + * algorithm name
> + *
> + * @name: algorithm name
> + * Return: enum tpm2_algorithms or -EINVAL
> + */
> +enum tpm2_algorithms tpm2_name_to_algorithm(const char *name);
> +
> +/**
> + * tpm2_algorithm_name() - Return an algorithm name string for a
> + * supported algorithm id
> + *
> + * @algorithm_id: algorithm defined in enum tpm2_algorithms
> + * Return: algorithm name string or ""
> + */
> +const char *tpm2_algorithm_name(enum tpm2_algorithms);
> +
> #endif /* __TPM_V2_H */
> diff --git a/lib/tpm-v2.c b/lib/tpm-v2.c
> index 68eaaa639f89..19b2535682e1 100644
> --- a/lib/tpm-v2.c
> +++ b/lib/tpm-v2.c
> @@ -29,6 +29,13 @@ const enum tpm2_algorithms tpm2_supported_algorithms[4] = {
> TPM2_ALG_SHA512,
> };
>
> +const char *tpm2_supported_algorithm_names[4] = {
> + "sha1",
> + "sha256",
> + "sha384",
> + "sha512",
> +};
> +
Overall this looks correct(but we don't need the [4] in the definition
tbh). However, keeping the info in 2 different places is not ideal.
We used to have a nice struct array that had all the info tightly together [0].
The struct looked like
struct digest_info {
u16 hash_alg;
u32 hash_mask;
u16 hash_len;
};
static const struct digest_info hash_algo_list[] = {
{
TPM2_ALG_SHA1,
EFI_TCG2_BOOT_HASH_ALG_SHA1,
TPM2_SHA1_DIGEST_SIZE,
},
{
TPM2_ALG_SHA256,
EFI_TCG2_BOOT_HASH_ALG_SHA256,
TPM2_SHA256_DIGEST_SIZE,
},
{
TPM2_ALG_SHA384,
EFI_TCG2_BOOT_HASH_ALG_SHA384,
TPM2_SHA384_DIGEST_SIZE,
},
{
TPM2_ALG_SHA512,
EFI_TCG2_BOOT_HASH_ALG_SHA512,
TPM2_SHA512_DIGEST_SIZE,
},
};
In short, we need to
- define the algorithm registry as defined by the TCG spec
/* Algorithm Registry */
#define EFI_TCG2_BOOT_HASH_ALG_SHA1 0x00000001
#define EFI_TCG2_BOOT_HASH_ALG_SHA256 0x00000002
#define EFI_TCG2_BOOT_HASH_ALG_SHA384 0x00000004
#define EFI_TCG2_BOOT_HASH_ALG_SHA512 0x00000008
#define EFI_TCG2_BOOT_HASH_ALG_SM3_256 0x00000010
- Bring back the functions that exist in that branch. Pre 2023.07 all
measured boot code lived in lib/efi_loader/efi_tcg.c, so we just need
to copy them over
- Add a new struct member with the name and a new function to retrieve it.
[0]
https://source.denx.de/u-boot/custodians/u-boot-tpm/-/blob/v2022.01-rc3/lib/efi_loader/efi_tcg2.c?ref_type=tags#L75
I understand that's more than what your patch tries to achieve here. I
am fine pulling this as-is and you/I can fix it up later unless you
don't mind doing it in a v3.
Thanks
/Ilias
> int tcg2_get_active_pcr_banks(struct udevice *dev, u32 *active_pcr_banks)
> {
> u32 supported = 0;
> @@ -1555,3 +1562,30 @@ u32 tpm2_enable_nvcommits(struct udevice *dev, uint
> vendor_cmd,
>
> return 0;
> }
> +
> +enum tpm2_algorithms tpm2_name_to_algorithm(const char *name)
> +{
> + enum tpm2_algorithms algo;
> + size_t i;
> +
> + for (i = 0; i < ARRAY_SIZE(tpm2_supported_algorithms); ++i) {
> + algo = tpm2_supported_algorithms[i];
> + if (!strcasecmp(name, tpm2_supported_algorithm_names[i]))
> + return algo;
> + }
> + printf("%s: unsupported algorithm %s\n", __func__, name);
> +
> + return -EINVAL;
> +}
> +
> +const char *tpm2_algorithm_name(enum tpm2_algorithms algo)
> +{
> + size_t i;
> +
> + for (i = 0; i < ARRAY_SIZE(tpm2_supported_algorithms); ++i) {
> + if (tpm2_supported_algorithms[i] == algo)
> + return tpm2_supported_algorithm_names[i];
> + }
> +
> + return "";
> +}
> --
> 2.25.1
>
