diff options
| -rw-r--r-- | drivers/char/tpm/tpm2-sessions.c | 129 | ||||
| -rw-r--r-- | include/linux/tpm.h | 26 |
2 files changed, 155 insertions, 0 deletions
diff --git a/drivers/char/tpm/tpm2-sessions.c b/drivers/char/tpm/tpm2-sessions.c index 1c8d50a501d7..203a3b3cee67 100644 --- a/drivers/char/tpm/tpm2-sessions.c +++ b/drivers/char/tpm/tpm2-sessions.c @@ -49,6 +49,11 @@ * Under normal operation this function is done by * tpm_buf_check_hmac_response(), so this is only to be used on * error legs where the latter is not executed. + * tpm_buf_append_name() to add a handle to the buffer. This must be + * used in place of the usual tpm_buf_append_u32() for adding + * handles because handles have to be processed specially when + * calculating the HMAC. In particular, for NV, volatile and + * permanent objects you now need to provide the name. */ #include "tpm.h" @@ -60,6 +65,9 @@ #include <crypto/hash.h> #include <crypto/hmac.h> +/* maximum number of names the TPM must remember for authorization */ +#define AUTH_MAX_NAMES 3 + /* * This is the structure that carries all the auth information (like * session handle, nonces, session key and auth) from use to use it is @@ -96,9 +104,32 @@ struct tpm2_auth { u8 scratch[AES_KEY_BYTES + AES_BLOCK_SIZE]; }; u8 session_key[SHA256_DIGEST_SIZE]; + + /* + * memory for three authorization handles. We know them by + * handle, but they are part of the session by name, which + * we must compute and remember + */ + u32 name_h[AUTH_MAX_NAMES]; + u8 name[AUTH_MAX_NAMES][2 + SHA512_DIGEST_SIZE]; }; /* + * Name Size based on TPM algorithm (assumes no hash bigger than 255) + */ +static u8 name_size(const u8 *name) +{ + static u8 size_map[] = { + [TPM_ALG_SHA1] = SHA1_DIGEST_SIZE, + [TPM_ALG_SHA256] = SHA256_DIGEST_SIZE, + [TPM_ALG_SHA384] = SHA384_DIGEST_SIZE, + [TPM_ALG_SHA512] = SHA512_DIGEST_SIZE, + }; + u16 alg = get_unaligned_be16(name); + return size_map[alg] + 2; +} + +/* * It turns out the crypto hmac(sha256) is hard for us to consume * because it assumes a fixed key and the TPM seems to change the key * on every operation, so we weld the hmac init and final functions in @@ -277,6 +308,104 @@ static void tpm_buf_append_salt(struct tpm_buf *buf, struct tpm_chip *chip) out: crypto_free_kpp(kpp); } + +static int tpm2_parse_read_public(char *name, struct tpm_buf *buf) +{ + struct tpm_header *head = (struct tpm_header *)buf->data; + off_t offset = TPM_HEADER_SIZE; + u32 tot_len = be32_to_cpu(head->length); + u32 val; + + /* we're starting after the header so adjust the length */ + tot_len -= TPM_HEADER_SIZE; + + /* skip public */ + val = tpm_buf_read_u16(buf, &offset); + if (val > tot_len) + return -EINVAL; + offset += val; + /* name */ + val = tpm_buf_read_u16(buf, &offset); + if (val != name_size(&buf->data[offset])) + return -EINVAL; + memcpy(name, &buf->data[offset], val); + /* forget the rest */ + return 0; +} + +static int tpm2_read_public(struct tpm_chip *chip, u32 handle, char *name) +{ + struct tpm_buf buf; + int rc; + + rc = tpm_buf_init(&buf, TPM2_ST_NO_SESSIONS, TPM2_CC_READ_PUBLIC); + if (rc) + return rc; + + tpm_buf_append_u32(&buf, handle); + rc = tpm_transmit_cmd(chip, &buf, 0, "read public"); + if (rc == TPM2_RC_SUCCESS) + rc = tpm2_parse_read_public(name, &buf); + + tpm_buf_destroy(&buf); + + return rc; +} + +/** + * tpm_buf_append_name() - add a handle area to the buffer + * @chip: the TPM chip structure + * @buf: The buffer to be appended + * @handle: The handle to be appended + * @name: The name of the handle (may be NULL) + * + * In order to compute session HMACs, we need to know the names of the + * objects pointed to by the handles. For most objects, this is simply + * the actual 4 byte handle or an empty buf (in these cases @name + * should be NULL) but for volatile objects, permanent objects and NV + * areas, the name is defined as the hash (according to the name + * algorithm which should be set to sha256) of the public area to + * which the two byte algorithm id has been appended. For these + * objects, the @name pointer should point to this. If a name is + * required but @name is NULL, then TPM2_ReadPublic() will be called + * on the handle to obtain the name. + * + * As with most tpm_buf operations, success is assumed because failure + * will be caused by an incorrect programming model and indicated by a + * kernel message. + */ +void tpm_buf_append_name(struct tpm_chip *chip, struct tpm_buf *buf, + u32 handle, u8 *name) +{ + enum tpm2_mso_type mso = tpm2_handle_mso(handle); + struct tpm2_auth *auth = chip->auth; + int slot; + + slot = (tpm_buf_length(buf) - TPM_HEADER_SIZE)/4; + if (slot >= AUTH_MAX_NAMES) { + dev_err(&chip->dev, "TPM: too many handles\n"); + return; + } + WARN(auth->session != tpm_buf_length(buf), + "name added in wrong place\n"); + tpm_buf_append_u32(buf, handle); + auth->session += 4; + + if (mso == TPM2_MSO_PERSISTENT || + mso == TPM2_MSO_VOLATILE || + mso == TPM2_MSO_NVRAM) { + if (!name) + tpm2_read_public(chip, handle, auth->name[slot]); + } else { + if (name) + dev_err(&chip->dev, "TPM: Handle does not require name but one is specified\n"); + } + + auth->name_h[slot] = handle; + if (name) + memcpy(auth->name[slot], name, name_size(name)); +} +EXPORT_SYMBOL(tpm_buf_append_name); /** * tpm2_end_auth_session() - kill the allocated auth session * @chip: the TPM chip structure diff --git a/include/linux/tpm.h b/include/linux/tpm.h index 81b5a70ff80d..31c2065fcd35 100644 --- a/include/linux/tpm.h +++ b/include/linux/tpm.h @@ -275,6 +275,7 @@ enum tpm2_command_codes { TPM2_CC_CONTEXT_LOAD = 0x0161, TPM2_CC_CONTEXT_SAVE = 0x0162, TPM2_CC_FLUSH_CONTEXT = 0x0165, + TPM2_CC_READ_PUBLIC = 0x0173, TPM2_CC_START_AUTH_SESS = 0x0176, TPM2_CC_VERIFY_SIGNATURE = 0x0177, TPM2_CC_GET_CAPABILITY = 0x017A, @@ -292,6 +293,21 @@ enum tpm2_permanent_handles { TPM2_RS_PW = 0x40000009, }; +/* Most Significant Octet for key types */ +enum tpm2_mso_type { + TPM2_MSO_NVRAM = 0x01, + TPM2_MSO_SESSION = 0x02, + TPM2_MSO_POLICY = 0x03, + TPM2_MSO_PERMANENT = 0x40, + TPM2_MSO_VOLATILE = 0x80, + TPM2_MSO_PERSISTENT = 0x81, +}; + +static inline enum tpm2_mso_type tpm2_handle_mso(u32 handle) +{ + return handle >> 24; +} + enum tpm2_capabilities { TPM2_CAP_HANDLES = 1, TPM2_CAP_COMMANDS = 2, @@ -492,6 +508,8 @@ static inline void tpm_buf_append_empty_auth(struct tpm_buf *buf, u32 handle) #ifdef CONFIG_TCG_TPM2_HMAC int tpm2_start_auth_session(struct tpm_chip *chip); +void tpm_buf_append_name(struct tpm_chip *chip, struct tpm_buf *buf, + u32 handle, u8 *name); void tpm2_end_auth_session(struct tpm_chip *chip); #else static inline int tpm2_start_auth_session(struct tpm_chip *chip) @@ -501,6 +519,14 @@ static inline int tpm2_start_auth_session(struct tpm_chip *chip) static inline void tpm2_end_auth_session(struct tpm_chip *chip) { } +static inline void tpm_buf_append_name(struct tpm_chip *chip, + struct tpm_buf *buf, + u32 handle, u8 *name) +{ + tpm_buf_append_u32(buf, handle); + /* count the number of handles in the upper bits of flags */ + buf->handles++; +} #endif /* CONFIG_TCG_TPM2_HMAC */ #endif |