[PATCH v3 6/7] tpm: Implement state command for Cr50
Simon Glass
sjg at chromium.org
Mon Aug 22 18:39:00 CEST 2022
Hi Ilias,
On Mon, 22 Aug 2022 at 00:04, Ilias Apalodimas
<ilias.apalodimas at linaro.org> wrote:
>
> Hi Simon,
>
> This produces some build warnings e.g
> drivers/tpm/cr50_i2c.c: In function ‘cr50_i2c_report_state’:
> drivers/tpm/cr50_i2c.c:680:48: warning: passing argument 3 of
> ‘tpm2_cr50_report_state’ from incompatible pointer type
> [-Wincompatible-pointer-types]
> 680 | ret = tpm2_cr50_report_state(dev, buf, &buf_size);
> | ^~~~~~~~~
> | |
> | int *
>
> On Fri, 19 Aug 2022 at 16:47, Simon Glass <sjg at chromium.org> wrote:
> >
> > Add a vendor-specific TPM2 command for this and implement it for Cr50.
> > Note: This is not part of the TPM spec, but is a Cr50 extension.
> >
> > Signed-off-by: Simon Glass <sjg at chromium.org>
> > ---
> >
> > (no changes since v1)
> >
> > drivers/tpm/cr50_i2c.c | 117 +++++++++++++++++++++++++++++++++++++++++
> > include/tpm-v2.h | 54 +++++++++++++++++++
> > lib/tpm-v2.c | 24 +++++++++
> > 3 files changed, 195 insertions(+)
> >
> > diff --git a/drivers/tpm/cr50_i2c.c b/drivers/tpm/cr50_i2c.c
> > index f8c30878947..dabf617be0e 100644
> > --- a/drivers/tpm/cr50_i2c.c
> > +++ b/drivers/tpm/cr50_i2c.c
> > @@ -13,11 +13,13 @@
> > #include <irq.h>
> > #include <log.h>
> > #include <spl.h>
> > +#include <tpm-common.h>
> > #include <tpm-v2.h>
> > #include <acpi/acpigen.h>
> > #include <acpi/acpi_device.h>
> > #include <asm/gpio.h>
> > #include <asm/io.h>
> > +#include <asm/unaligned.h>
> > #include <linux/delay.h>
> > #include <dm/acpi.h>
> >
> > @@ -54,6 +56,41 @@ struct cr50_priv {
> > bool use_irq;
> > };
> >
> > +/*
> > + * The below structure represents the body of the response to the 'report tpm
> > + * state' vendor command.
> > + *
> > + * It is transferred over the wire, so it needs to be serialized/deserialized,
> > + * and it is likely to change, so its contents must be versioned.
> > + */
> > +#define TPM_STATE_VERSION 1
> > +struct tpm_vendor_state {
> > + u32 version;
> > + /*
> > + * The following three fields are set by the TPM in case of an assert.
> > + * There is no other processing than setting the source code line
> > + * number, error code and the first 4 characters of the function name.
> > + *
> > + * We don't expect this happening, but it is included in the report
> > + * just in case.
> > + */
> > + u32 fail_line; /* s_failLIne */
> > + u32 fail_code; /* s_failCode */
> > + char func_name[4]; /* s_failFunction, limited to 4 chars */
> > +
> > + /*
> > + * The following two fields are the current time filtered value of the
> > + * 'failed tries' TPM counter, and the maximum allowed value of the
> > + * counter.
> > + *
> > + * failed_tries == max_tries is the definition of the TPM lockout
> > + * condition.
> > + */
> > + u32 failed_tries; /* gp.failedTries */
> > + u32 max_tries; /* gp.maxTries */
> > + /* The below fields are present in version 2 and above */
> > +};
> > +
> > /* Wait for interrupt to indicate TPM is ready */
> > static int cr50_i2c_wait_tpm_ready(struct udevice *dev)
> > {
> > @@ -573,6 +610,85 @@ static int cr50_i2c_get_desc(struct udevice *dev, char *buf, int size)
> > return len;
> > }
> >
> > +static int stringify_state(char *buf, int len, char *str, size_t max_size)
> > +{
> > + struct tpm_vendor_state state;
> > + size_t text_size = 0;
> > +
> > + state.version = get_unaligned_be32(buf +
> > + offsetof(struct tpm_vendor_state, version));
> > + state.fail_line = get_unaligned_be32(buf +
> > + offsetof(struct tpm_vendor_state, fail_line));
> > + state.fail_code = get_unaligned_be32(buf +
> > + offsetof(struct tpm_vendor_state, fail_code));
> > + memcpy(state.func_name,
> > + buf + offsetof(struct tpm_vendor_state, func_name),
> > + sizeof(state.func_name));
> > + state.failed_tries = get_unaligned_be32(buf +
> > + offsetof(struct tpm_vendor_state, failed_tries));
> > + state.max_tries = get_unaligned_be32(buf +
> > + offsetof(struct tpm_vendor_state, max_tries));
> > +
> > + text_size += snprintf(str + text_size, max_size - text_size,
> > + "v=%d", state.version);
> > + if (text_size >= max_size)
> > + return -ENOSPC;
> > +
> > + if (state.version > TPM_STATE_VERSION)
> > + text_size += snprintf(str + text_size,
> > + max_size - text_size,
> > + " not fully supported\n");
> > + if (text_size >= max_size)
> > + return -ENOSPC;
> > +
> > + if (state.version == 0)
> > + return -EINVAL; /* This should never happen */
> > +
> > + text_size += snprintf(str + text_size,
> > + max_size - text_size,
> > + " failed_tries=%d max_tries=%d\n",
> > + state.failed_tries, state.max_tries);
> > + if (text_size >= max_size)
> > + return -ENOSPC;
> > +
> > + if (state.fail_line) {
> > + /* make sure function name is zero terminated. */
> > + char func_name[sizeof(state.func_name) + 1];
> > +
> > + memcpy(func_name, state.func_name, sizeof(state.func_name));
> > + func_name[sizeof(state.func_name)] = '\0';
> > +
> > + text_size += snprintf(str + text_size,
> > + max_size - text_size,
> > + "tpm failed: f %s line %d code %d",
> > + func_name,
> > + state.fail_line,
> > + state.fail_code);
> > + if (text_size >= max_size)
> > + return -ENOSPC;
> > + }
> > +
> > + return 0;
> > +}
> > +
> > +static int cr50_i2c_report_state(struct udevice *dev, char *str, int str_max)
> > +{
> > + char buf[50];
> > + int buf_size = sizeof(buf);
> > + int ret;
> > +
> > + ret = tpm2_cr50_report_state(dev, buf, &buf_size);
> > + if (ret)
> > + return ret;
> > +
> > + /* TPM responded as expected */
> > + ret = stringify_state(buf, buf_size, str, str_max);
> > + if (ret)
> > + return ret;
> > +
> > + return 0;
> > +}
> > +
> > static int cr50_i2c_open(struct udevice *dev)
> > {
> > char buf[80];
> > @@ -730,6 +846,7 @@ struct acpi_ops cr50_acpi_ops = {
> > static const struct tpm_ops cr50_i2c_ops = {
> > .open = cr50_i2c_open,
> > .get_desc = cr50_i2c_get_desc,
> > + .report_state = cr50_i2c_report_state,
> > .send = cr50_i2c_send,
> > .recv = cr50_i2c_recv,
> > .cleanup = cr50_i2c_cleanup,
> > diff --git a/include/tpm-v2.h b/include/tpm-v2.h
> > index e79c90b9395..8e90a616220 100644
> > --- a/include/tpm-v2.h
> > +++ b/include/tpm-v2.h
> > @@ -419,6 +419,50 @@ enum {
> > HR_NV_INDEX = TPM_HT_NV_INDEX << HR_SHIFT,
> > };
> >
> > +/*
> > + * Operations specific to the Cr50 TPM used on Chromium OS and Android devices
> > + *
> > + * FIXME: below is not enough to differentiate between vendors commands
> > + * of numerous devices. However, the current tpm2 APIs aren't very amenable
> > + * to extending generically because the marshaling code is assuming all
> > + * knowledge of all commands.
> > + */
> > +#define TPM2_CC_VENDOR_BIT_MASK 0x20000000
> > +
> > +#define TPM2_CR50_VENDOR_COMMAND (TPM2_CC_VENDOR_BIT_MASK | 0)
> > +#define TPM2_CR50_SUB_CMD_IMMEDIATE_RESET 19
> > +#define TPM2_CR50_SUB_CMD_NVMEM_ENABLE_COMMITS 21
> > +#define TPM2_CR50_SUB_CMD_REPORT_TPM_STATE 23
> > +#define TPM2_CR50_SUB_CMD_TURN_UPDATE_ON 24
> > +#define TPM2_CR50_SUB_CMD_GET_REC_BTN 29
> > +#define TPM2_CR50_SUB_CMD_TPM_MODE 40
> > +#define TPM2_CR50_SUB_CMD_GET_BOOT_MODE 52
> > +#define TPM2_CR50_SUB_CMD_RESET_EC 53
> > +
> > +/* Cr50 vendor-specific error codes. */
> > +#define VENDOR_RC_ERR 0x00000500
> > +enum cr50_vendor_rc {
> > + VENDOR_RC_INTERNAL_ERROR = (VENDOR_RC_ERR | 6),
> > + VENDOR_RC_NO_SUCH_SUBCOMMAND = (VENDOR_RC_ERR | 8),
> > + VENDOR_RC_NO_SUCH_COMMAND = (VENDOR_RC_ERR | 127),
> > +};
> > +
> > +enum cr50_tpm_mode {
> > + /*
> > + * Default state: TPM is enabled, and may be set to either
> > + * TPM_MODE_ENABLED or TPM_MODE_DISABLED.
> > + */
> > + TPM_MODE_ENABLED_TENTATIVE = 0,
> > +
> > + /* TPM is enabled, and mode may not be changed. */
> > + TPM_MODE_ENABLED = 1,
> > +
> > + /* TPM is disabled, and mode may not be changed. */
> > + TPM_MODE_DISABLED = 2,
> > +
> > + TPM_MODE_INVALID,
> > +};
> > +
> > /**
> > * Issue a TPM2_Startup command.
> > *
> > @@ -658,4 +702,14 @@ u32 tpm2_disable_platform_hierarchy(struct udevice *dev);
> > u32 tpm2_submit_command(struct udevice *dev, const u8 *sendbuf,
> > u8 *recvbuf, size_t *recv_size);
> >
> > +/**
> > + * tpm_cr50_report_state() - Report the Cr50 internal state
> > + *
> > + * @dev: TPM device
> > + * @recvbuf: Buffer to save the response to
> > + * @recv_size: Pointer to the size of the response buffer
> > + * Return: result of the operation
> > + */
> > +u32 tpm2_cr50_report_state(struct udevice *dev, u8 *recvbuf, size_t *recv_size);
> > +
> > #endif /* __TPM_V2_H */
> > diff --git a/lib/tpm-v2.c b/lib/tpm-v2.c
> > index 3e240bb4c67..3de4841974a 100644
> > --- a/lib/tpm-v2.c
> > +++ b/lib/tpm-v2.c
> > @@ -679,3 +679,27 @@ u32 tpm2_submit_command(struct udevice *dev, const u8 *sendbuf,
> > {
> > return tpm_sendrecv_command(dev, sendbuf, recvbuf, recv_size);
> > }
> > +
> > +u32 tpm2_cr50_report_state(struct udevice *dev, u8 *recvbuf, size_t *recv_size)
> > +{
> > + u8 command_v2[COMMAND_BUFFER_SIZE] = {
> > + /* header 10 bytes */
> > + tpm_u16(TPM2_ST_NO_SESSIONS), /* TAG */
> > + tpm_u32(10 + 2), /* Length */
> > + tpm_u32(TPM2_CR50_VENDOR_COMMAND), /* Command code */
> > +
> > + tpm_u16(TPM2_CR50_SUB_CMD_REPORT_TPM_STATE),
> > + };
> > + int ret;
> > +
> > + ret = tpm_sendrecv_command(dev, command_v2, recvbuf, recv_size);
> > + log_debug("ret=%s, %x\n", dev->name, ret);
> > + if (ret)
> > + return ret;
> > + if (*recv_size < 12)
> > + return -ENODATA;
> > + *recv_size -= 12;
> > + memcpy(recvbuf, recvbuf + 12, *recv_size);
> > +
> > + return 0;
> > +}
>
> From the previous patchset, I still don't understand why it makes
> sense to add hardware specific functions in the generic API.
> It doesn't seem too much work to move this into drivers/tpm/cr50_i2c.c
We are not allowed to directly call into drivers without going through
the uclass interface, except perhaps in extremis e.g. SPL for
code-size reasons.
Regards,
Simon
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