u-boot-brain/include/tpm.h
mario.six@gdsys.cc 0f4b2ba176 tpm: Add function to load keys via their parent's SHA1 hash
If we want to load a key into a TPM, we need to know the designated parent
key's handle, so that the TPM is able to insert the key at the correct place in
the key hierarchy.

However, if we want to load a key whose designated parent key we also
previously loaded ourselves, we first need to memorize this parent key's handle
(since the handles for the key are chosen at random when they are inserted into
the TPM). If we are, however, unable to do so, for example if the parent key is
loaded into the TPM during production, and its child key during the actual
boot, we must find a different mechanism to identify the parent key.

To solve this problem, we add a function that allows U-Boot to load a key into
the TPM using their designated parent key's SHA1 hash, and the corresponding
auth data.

Signed-off-by: Mario Six <mario.six@gdsys.cc>
Reviewed-by: Simon Glass <sjg@chromium.org>
2017-03-26 13:22:58 -06:00

655 lines
19 KiB
C

/*
* Copyright (c) 2013 The Chromium OS Authors.
* Coypright (c) 2013 Guntermann & Drunck GmbH
*
* SPDX-License-Identifier: GPL-2.0+
*/
#ifndef __TPM_H
#define __TPM_H
/*
* Here is a partial implementation of TPM commands. Please consult TCG Main
* Specification for definitions of TPM commands.
*/
#define TPM_HEADER_SIZE 10
enum tpm_duration {
TPM_SHORT = 0,
TPM_MEDIUM = 1,
TPM_LONG = 2,
TPM_UNDEFINED,
TPM_DURATION_COUNT,
};
enum tpm_startup_type {
TPM_ST_CLEAR = 0x0001,
TPM_ST_STATE = 0x0002,
TPM_ST_DEACTIVATED = 0x0003,
};
enum tpm_physical_presence {
TPM_PHYSICAL_PRESENCE_HW_DISABLE = 0x0200,
TPM_PHYSICAL_PRESENCE_CMD_DISABLE = 0x0100,
TPM_PHYSICAL_PRESENCE_LIFETIME_LOCK = 0x0080,
TPM_PHYSICAL_PRESENCE_HW_ENABLE = 0x0040,
TPM_PHYSICAL_PRESENCE_CMD_ENABLE = 0x0020,
TPM_PHYSICAL_PRESENCE_NOTPRESENT = 0x0010,
TPM_PHYSICAL_PRESENCE_PRESENT = 0x0008,
TPM_PHYSICAL_PRESENCE_LOCK = 0x0004,
};
enum tpm_nv_index {
TPM_NV_INDEX_LOCK = 0xffffffff,
TPM_NV_INDEX_0 = 0x00000000,
TPM_NV_INDEX_DIR = 0x10000001,
};
enum tpm_resource_type {
TPM_RT_KEY = 0x00000001,
TPM_RT_AUTH = 0x00000002,
TPM_RT_HASH = 0x00000003,
TPM_RT_TRANS = 0x00000004,
TPM_RT_CONTEXT = 0x00000005,
TPM_RT_COUNTER = 0x00000006,
TPM_RT_DELEGATE = 0x00000007,
TPM_RT_DAA_TPM = 0x00000008,
TPM_RT_DAA_V0 = 0x00000009,
TPM_RT_DAA_V1 = 0x0000000A,
};
enum tpm_capability_areas {
TPM_CAP_ORD = 0x00000001,
TPM_CAP_ALG = 0x00000002,
TPM_CAP_PID = 0x00000003,
TPM_CAP_FLAG = 0x00000004,
TPM_CAP_PROPERTY = 0x00000005,
TPM_CAP_VERSION = 0x00000006,
TPM_CAP_KEY_HANDLE = 0x00000007,
TPM_CAP_CHECK_LOADED = 0x00000008,
TPM_CAP_SYM_MODE = 0x00000009,
TPM_CAP_KEY_STATUS = 0x0000000C,
TPM_CAP_NV_LIST = 0x0000000D,
TPM_CAP_MFR = 0x00000010,
TPM_CAP_NV_INDEX = 0x00000011,
TPM_CAP_TRANS_ALG = 0x00000012,
TPM_CAP_HANDLE = 0x00000014,
TPM_CAP_TRANS_ES = 0x00000015,
TPM_CAP_AUTH_ENCRYPT = 0x00000017,
TPM_CAP_SELECT_SIZE = 0x00000018,
TPM_CAP_DA_LOGIC = 0x00000019,
TPM_CAP_VERSION_VAL = 0x0000001A,
};
#define TPM_NV_PER_GLOBALLOCK (1U << 15)
#define TPM_NV_PER_PPWRITE (1U << 0)
#define TPM_NV_PER_READ_STCLEAR (1U << 31)
#define TPM_NV_PER_WRITE_STCLEAR (1U << 14)
enum {
TPM_PUBEK_SIZE = 256,
};
/**
* TPM return codes as defined in the TCG Main specification
* (TPM Main Part 2 Structures; Specification version 1.2)
*/
enum tpm_return_code {
TPM_BASE = 0x00000000,
TPM_NON_FATAL = 0x00000800,
TPM_SUCCESS = TPM_BASE,
/* TPM-defined fatal error codes */
TPM_AUTHFAIL = TPM_BASE + 1,
TPM_BADINDEX = TPM_BASE + 2,
TPM_BAD_PARAMETER = TPM_BASE + 3,
TPM_AUDITFAILURE = TPM_BASE + 4,
TPM_CLEAR_DISABLED = TPM_BASE + 5,
TPM_DEACTIVATED = TPM_BASE + 6,
TPM_DISABLED = TPM_BASE + 7,
TPM_DISABLED_CMD = TPM_BASE + 8,
TPM_FAIL = TPM_BASE + 9,
TPM_BAD_ORDINAL = TPM_BASE + 10,
TPM_INSTALL_DISABLED = TPM_BASE + 11,
TPM_INVALID_KEYHANDLE = TPM_BASE + 12,
TPM_KEYNOTFOUND = TPM_BASE + 13,
TPM_INAPPROPRIATE_ENC = TPM_BASE + 14,
TPM_MIGRATE_FAIL = TPM_BASE + 15,
TPM_INVALID_PCR_INFO = TPM_BASE + 16,
TPM_NOSPACE = TPM_BASE + 17,
TPM_NOSRK = TPM_BASE + 18,
TPM_NOTSEALED_BLOB = TPM_BASE + 19,
TPM_OWNER_SET = TPM_BASE + 20,
TPM_RESOURCES = TPM_BASE + 21,
TPM_SHORTRANDOM = TPM_BASE + 22,
TPM_SIZE = TPM_BASE + 23,
TPM_WRONGPCRVAL = TPM_BASE + 24,
TPM_BAD_PARAM_SIZE = TPM_BASE + 25,
TPM_SHA_THREAD = TPM_BASE + 26,
TPM_SHA_ERROR = TPM_BASE + 27,
TPM_FAILEDSELFTEST = TPM_BASE + 28,
TPM_AUTH2FAIL = TPM_BASE + 29,
TPM_BADTAG = TPM_BASE + 30,
TPM_IOERROR = TPM_BASE + 31,
TPM_ENCRYPT_ERROR = TPM_BASE + 32,
TPM_DECRYPT_ERROR = TPM_BASE + 33,
TPM_INVALID_AUTHHANDLE = TPM_BASE + 34,
TPM_NO_ENDORSEMENT = TPM_BASE + 35,
TPM_INVALID_KEYUSAGE = TPM_BASE + 36,
TPM_WRONG_ENTITYTYPE = TPM_BASE + 37,
TPM_INVALID_POSTINIT = TPM_BASE + 38,
TPM_INAPPROPRIATE_SIG = TPM_BASE + 39,
TPM_BAD_KEY_PROPERTY = TPM_BASE + 40,
TPM_BAD_MIGRATION = TPM_BASE + 41,
TPM_BAD_SCHEME = TPM_BASE + 42,
TPM_BAD_DATASIZE = TPM_BASE + 43,
TPM_BAD_MODE = TPM_BASE + 44,
TPM_BAD_PRESENCE = TPM_BASE + 45,
TPM_BAD_VERSION = TPM_BASE + 46,
TPM_NO_WRAP_TRANSPORT = TPM_BASE + 47,
TPM_AUDITFAIL_UNSUCCESSFUL = TPM_BASE + 48,
TPM_AUDITFAIL_SUCCESSFUL = TPM_BASE + 49,
TPM_NOTRESETABLE = TPM_BASE + 50,
TPM_NOTLOCAL = TPM_BASE + 51,
TPM_BAD_TYPE = TPM_BASE + 52,
TPM_INVALID_RESOURCE = TPM_BASE + 53,
TPM_NOTFIPS = TPM_BASE + 54,
TPM_INVALID_FAMILY = TPM_BASE + 55,
TPM_NO_NV_PERMISSION = TPM_BASE + 56,
TPM_REQUIRES_SIGN = TPM_BASE + 57,
TPM_KEY_NOTSUPPORTED = TPM_BASE + 58,
TPM_AUTH_CONFLICT = TPM_BASE + 59,
TPM_AREA_LOCKED = TPM_BASE + 60,
TPM_BAD_LOCALITY = TPM_BASE + 61,
TPM_READ_ONLY = TPM_BASE + 62,
TPM_PER_NOWRITE = TPM_BASE + 63,
TPM_FAMILY_COUNT = TPM_BASE + 64,
TPM_WRITE_LOCKED = TPM_BASE + 65,
TPM_BAD_ATTRIBUTES = TPM_BASE + 66,
TPM_INVALID_STRUCTURE = TPM_BASE + 67,
TPM_KEY_OWNER_CONTROL = TPM_BASE + 68,
TPM_BAD_COUNTER = TPM_BASE + 69,
TPM_NOT_FULLWRITE = TPM_BASE + 70,
TPM_CONTEXT_GAP = TPM_BASE + 71,
TPM_MAXNVWRITES = TPM_BASE + 72,
TPM_NOOPERATOR = TPM_BASE + 73,
TPM_RESOURCEMISSING = TPM_BASE + 74,
TPM_DELEGATE_LOCK = TPM_BASE + 75,
TPM_DELEGATE_FAMILY = TPM_BASE + 76,
TPM_DELEGATE_ADMIN = TPM_BASE + 77,
TPM_TRANSPORT_NOTEXCLUSIVE = TPM_BASE + 78,
TPM_OWNER_CONTROL = TPM_BASE + 79,
TPM_DAA_RESOURCES = TPM_BASE + 80,
TPM_DAA_INPUT_DATA0 = TPM_BASE + 81,
TPM_DAA_INPUT_DATA1 = TPM_BASE + 82,
TPM_DAA_ISSUER_SETTINGS = TPM_BASE + 83,
TPM_DAA_TPM_SETTINGS = TPM_BASE + 84,
TPM_DAA_STAGE = TPM_BASE + 85,
TPM_DAA_ISSUER_VALIDITY = TPM_BASE + 86,
TPM_DAA_WRONG_W = TPM_BASE + 87,
TPM_BAD_HANDLE = TPM_BASE + 88,
TPM_BAD_DELEGATE = TPM_BASE + 89,
TPM_BADCONTEXT = TPM_BASE + 90,
TPM_TOOMANYCONTEXTS = TPM_BASE + 91,
TPM_MA_TICKET_SIGNATURE = TPM_BASE + 92,
TPM_MA_DESTINATION = TPM_BASE + 93,
TPM_MA_SOURCE = TPM_BASE + 94,
TPM_MA_AUTHORITY = TPM_BASE + 95,
TPM_PERMANENTEK = TPM_BASE + 97,
TPM_BAD_SIGNATURE = TPM_BASE + 98,
TPM_NOCONTEXTSPACE = TPM_BASE + 99,
/* TPM-defined non-fatal errors */
TPM_RETRY = TPM_BASE + TPM_NON_FATAL,
TPM_NEEDS_SELFTEST = TPM_BASE + TPM_NON_FATAL + 1,
TPM_DOING_SELFTEST = TPM_BASE + TPM_NON_FATAL + 2,
TPM_DEFEND_LOCK_RUNNING = TPM_BASE + TPM_NON_FATAL + 3,
};
struct tpm_permanent_flags {
__be16 tag;
u8 disable;
u8 ownership;
u8 deactivated;
u8 read_pubek;
u8 disable_owner_clear;
u8 allow_maintenance;
u8 physical_presence_lifetime_lock;
u8 physical_presence_hw_enable;
u8 physical_presence_cmd_enable;
u8 cekp_used;
u8 tpm_post;
u8 tpm_post_lock;
u8 fips;
u8 operator;
u8 enable_revoke_ek;
u8 nv_locked;
u8 read_srk_pub;
u8 tpm_established;
u8 maintenance_done;
u8 disable_full_da_logic_info;
} __packed;
/* Max buffer size supported by our tpm */
#define TPM_DEV_BUFSIZE 1260
/**
* struct tpm_chip_priv - Information about a TPM, stored by the uclass
*
* These values must be set up by the device's probe() method before
* communcation is attempted. If the device has an xfer() method, this is
* not needed. There is no need to set up @buf.
*
* @duration_ms: Length of each duration type in milliseconds
* @retry_time_ms: Time to wait before retrying receive
*/
struct tpm_chip_priv {
uint duration_ms[TPM_DURATION_COUNT];
uint retry_time_ms;
u8 buf[TPM_DEV_BUFSIZE + sizeof(u8)]; /* Max buffer size + addr */
};
/**
* struct tpm_ops - low-level TPM operations
*
* These are designed to avoid loops and delays in the driver itself. These
* should be handled in the uclass.
*
* In gneral you should implement everything except xfer(). Where you need
* complete control of the transfer, then xfer() can be provided and will
* override the other methods.
*
* This interface is for low-level TPM access. It does not understand the
* concept of localities or the various TPM messages. That interface is
* defined in the functions later on in this file, but they all translate
* to bytes which are sent and received.
*/
struct tpm_ops {
/**
* open() - Request access to locality 0 for the caller
*
* After all commands have been completed the caller should call
* close().
*
* @dev: Device to close
* @return 0 ok OK, -ve on error
*/
int (*open)(struct udevice *dev);
/**
* close() - Close the current session
*
* Releasing the locked locality. Returns 0 on success, -ve 1 on
* failure (in case lock removal did not succeed).
*
* @dev: Device to close
* @return 0 ok OK, -ve on error
*/
int (*close)(struct udevice *dev);
/**
* get_desc() - Get a text description of the TPM
*
* @dev: Device to check
* @buf: Buffer to put the string
* @size: Maximum size of buffer
* @return length of string, or -ENOSPC it no space
*/
int (*get_desc)(struct udevice *dev, char *buf, int size);
/**
* send() - send data to the TPM
*
* @dev: Device to talk to
* @sendbuf: Buffer of the data to send
* @send_size: Size of the data to send
*
* Returns 0 on success or -ve on failure.
*/
int (*send)(struct udevice *dev, const uint8_t *sendbuf,
size_t send_size);
/**
* recv() - receive a response from the TPM
*
* @dev: Device to talk to
* @recvbuf: Buffer to save the response to
* @max_size: Maximum number of bytes to receive
*
* Returns number of bytes received on success, -EAGAIN if the TPM
* response is not ready, -EINTR if cancelled, or other -ve value on
* failure.
*/
int (*recv)(struct udevice *dev, uint8_t *recvbuf, size_t max_size);
/**
* cleanup() - clean up after an operation in progress
*
* This is called if receiving times out. The TPM may need to abort
* the current transaction if it did not complete, and make itself
* ready for another.
*
* @dev: Device to talk to
*/
int (*cleanup)(struct udevice *dev);
/**
* xfer() - send data to the TPM and get response
*
* This method is optional. If it exists it is used in preference
* to send(), recv() and cleanup(). It should handle all aspects of
* TPM communication for a single transfer.
*
* @dev: Device to talk to
* @sendbuf: Buffer of the data to send
* @send_size: Size of the data to send
* @recvbuf: Buffer to save the response to
* @recv_size: Pointer to the size of the response buffer
*
* Returns 0 on success (and places the number of response bytes at
* recv_size) or -ve on failure.
*/
int (*xfer)(struct udevice *dev, const uint8_t *sendbuf,
size_t send_size, uint8_t *recvbuf, size_t *recv_size);
};
#define tpm_get_ops(dev) ((struct tpm_ops *)device_get_ops(dev))
/**
* tpm_open() - Request access to locality 0 for the caller
*
* After all commands have been completed the caller is supposed to
* call tpm_close().
*
* Returns 0 on success, -ve on failure.
*/
int tpm_open(struct udevice *dev);
/**
* tpm_close() - Close the current session
*
* Releasing the locked locality. Returns 0 on success, -ve 1 on
* failure (in case lock removal did not succeed).
*/
int tpm_close(struct udevice *dev);
/**
* tpm_get_desc() - Get a text description of the TPM
*
* @dev: Device to check
* @buf: Buffer to put the string
* @size: Maximum size of buffer
* @return length of string, or -ENOSPC it no space
*/
int tpm_get_desc(struct udevice *dev, char *buf, int size);
/**
* tpm_xfer() - send data to the TPM and get response
*
* This first uses the device's send() method to send the bytes. Then it calls
* recv() to get the reply. If recv() returns -EAGAIN then it will delay a
* short time and then call recv() again.
*
* Regardless of whether recv() completes successfully, it will then call
* cleanup() to finish the transaction.
*
* Note that the outgoing data is inspected to determine command type
* (ordinal) and a timeout is used for that command type.
*
* @sendbuf - buffer of the data to send
* @send_size size of the data to send
* @recvbuf - memory to save the response to
* @recv_len - pointer to the size of the response buffer
*
* Returns 0 on success (and places the number of response bytes at
* recv_len) or -ve on failure.
*/
int tpm_xfer(struct udevice *dev, const uint8_t *sendbuf, size_t send_size,
uint8_t *recvbuf, size_t *recv_size);
/**
* Initialize TPM device. It must be called before any TPM commands.
*
* @return 0 on success, non-0 on error.
*/
int tpm_init(void);
/**
* Issue a TPM_Startup command.
*
* @param mode TPM startup mode
* @return return code of the operation
*/
uint32_t tpm_startup(enum tpm_startup_type mode);
/**
* Issue a TPM_SelfTestFull command.
*
* @return return code of the operation
*/
uint32_t tpm_self_test_full(void);
/**
* Issue a TPM_ContinueSelfTest command.
*
* @return return code of the operation
*/
uint32_t tpm_continue_self_test(void);
/**
* Issue a TPM_NV_DefineSpace command. The implementation is limited
* to specify TPM_NV_ATTRIBUTES and size of the area. The area index
* could be one of the special value listed in enum tpm_nv_index.
*
* @param index index of the area
* @param perm TPM_NV_ATTRIBUTES of the area
* @param size size of the area
* @return return code of the operation
*/
uint32_t tpm_nv_define_space(uint32_t index, uint32_t perm, uint32_t size);
/**
* Issue a TPM_NV_ReadValue command. This implementation is limited
* to read the area from offset 0. The area index could be one of
* the special value listed in enum tpm_nv_index.
*
* @param index index of the area
* @param data output buffer of the area contents
* @param count size of output buffer
* @return return code of the operation
*/
uint32_t tpm_nv_read_value(uint32_t index, void *data, uint32_t count);
/**
* Issue a TPM_NV_WriteValue command. This implementation is limited
* to write the area from offset 0. The area index could be one of
* the special value listed in enum tpm_nv_index.
*
* @param index index of the area
* @param data input buffer to be wrote to the area
* @param length length of data bytes of input buffer
* @return return code of the operation
*/
uint32_t tpm_nv_write_value(uint32_t index, const void *data, uint32_t length);
/**
* Issue a TPM_Extend command.
*
* @param index index of the PCR
* @param in_digest 160-bit value representing the event to be
* recorded
* @param out_digest 160-bit PCR value after execution of the
* command
* @return return code of the operation
*/
uint32_t tpm_extend(uint32_t index, const void *in_digest, void *out_digest);
/**
* Issue a TPM_PCRRead command.
*
* @param index index of the PCR
* @param data output buffer for contents of the named PCR
* @param count size of output buffer
* @return return code of the operation
*/
uint32_t tpm_pcr_read(uint32_t index, void *data, size_t count);
/**
* Issue a TSC_PhysicalPresence command. TPM physical presence flag
* is bit-wise OR'ed of flags listed in enum tpm_physical_presence.
*
* @param presence TPM physical presence flag
* @return return code of the operation
*/
uint32_t tpm_tsc_physical_presence(uint16_t presence);
/**
* Issue a TPM_ReadPubek command.
*
* @param data output buffer for the public endorsement key
* @param count size of ouput buffer
* @return return code of the operation
*/
uint32_t tpm_read_pubek(void *data, size_t count);
/**
* Issue a TPM_ForceClear command.
*
* @return return code of the operation
*/
uint32_t tpm_force_clear(void);
/**
* Issue a TPM_PhysicalEnable command.
*
* @return return code of the operation
*/
uint32_t tpm_physical_enable(void);
/**
* Issue a TPM_PhysicalDisable command.
*
* @return return code of the operation
*/
uint32_t tpm_physical_disable(void);
/**
* Issue a TPM_PhysicalSetDeactivated command.
*
* @param state boolean state of the deactivated flag
* @return return code of the operation
*/
uint32_t tpm_physical_set_deactivated(uint8_t state);
/**
* Issue a TPM_GetCapability command. This implementation is limited
* to query sub_cap index that is 4-byte wide.
*
* @param cap_area partition of capabilities
* @param sub_cap further definition of capability, which is
* limited to be 4-byte wide
* @param cap output buffer for capability information
* @param count size of ouput buffer
* @return return code of the operation
*/
uint32_t tpm_get_capability(uint32_t cap_area, uint32_t sub_cap,
void *cap, size_t count);
/**
* Issue a TPM_FlushSpecific command for a AUTH ressource.
*
* @param auth_handle handle of the auth session
* @return return code of the operation
*/
uint32_t tpm_terminate_auth_session(uint32_t auth_handle);
/**
* Issue a TPM_OIAP command to setup an object independant authorization
* session.
* Information about the session is stored internally.
* If there was already an OIAP session active it is terminated and a new
* session is set up.
*
* @param auth_handle pointer to the (new) auth handle or NULL.
* @return return code of the operation
*/
uint32_t tpm_oiap(uint32_t *auth_handle);
/**
* Ends an active OIAP session.
*
* @return return code of the operation
*/
uint32_t tpm_end_oiap(void);
/**
* Issue a TPM_LoadKey2 (Auth1) command using an OIAP session for authenticating
* the usage of the parent key.
*
* @param parent_handle handle of the parent key.
* @param key pointer to the key structure (TPM_KEY or TPM_KEY12).
* @param key_length size of the key structure
* @param parent_key_usage_auth usage auth for the parent key
* @param key_handle pointer to the key handle
* @return return code of the operation
*/
uint32_t tpm_load_key2_oiap(uint32_t parent_handle,
const void *key, size_t key_length,
const void *parent_key_usage_auth,
uint32_t *key_handle);
/**
* Issue a TPM_GetPubKey (Auth1) command using an OIAP session for
* authenticating the usage of the key.
*
* @param key_handle handle of the key
* @param usage_auth usage auth for the key
* @param pubkey pointer to the pub key buffer; may be NULL if the pubkey
* should not be stored.
* @param pubkey_len pointer to the pub key buffer len. On entry: the size of
* the provided pubkey buffer. On successful exit: the size
* of the stored TPM_PUBKEY structure (iff pubkey != NULL).
* @return return code of the operation
*/
uint32_t tpm_get_pub_key_oiap(uint32_t key_handle, const void *usage_auth,
void *pubkey, size_t *pubkey_len);
/**
* Get the TPM permanent flags value
*
* @param pflags Place to put permanent flags
* @return return code of the operation
*/
uint32_t tpm_get_permanent_flags(struct tpm_permanent_flags *pflags);
/**
* Get the TPM permissions
*
* @param perm Returns permissions value
* @return return code of the operation
*/
uint32_t tpm_get_permissions(uint32_t index, uint32_t *perm);
/**
* Flush a resource with a given handle and type from the TPM
*
* @param key_handle handle of the resource
* @param resource_type type of the resource
* @return return code of the operation
*/
uint32_t tpm_flush_specific(uint32_t key_handle, uint32_t resource_type);
#ifdef CONFIG_TPM_LOAD_KEY_BY_SHA1
/**
* Search for a key by usage AuthData and the hash of the parent's pub key.
*
* @param auth Usage auth of the key to search for
* @param pubkey_digest SHA1 hash of the pub key structure of the key
* @param[out] handle The handle of the key (Non-null iff found)
* @return 0 if key was found in TPM; != 0 if not.
*/
uint32_t tpm_find_key_sha1(const uint8_t auth[20], const uint8_t
pubkey_digest[20], uint32_t *handle);
#endif /* CONFIG_TPM_LOAD_KEY_BY_SHA1 */
#endif /* __TPM_H */