From 7aee9c52d7ac90e19705bf3b429caa51f105174a Mon Sep 17 00:00:00 2001 From: Tomas Winkler Date: Fri, 19 Oct 2018 21:23:02 +0300 Subject: [PATCH] tpm: tpm1: rewrite tpm1_get_random() using tpm_buf structure 1. Use tpm_buf in tpm1_get_random() 2. Fix comment in tpm_get_random() so it is clear that the function is expected to return number of random bytes. Signed-off-by: Tomas Winkler Reviewed-by: Jarkko Sakkinen Tested-by: Jarkko Sakkinen Signed-off-by: Jarkko Sakkinen --- drivers/char/tpm/tpm-interface.c | 2 +- drivers/char/tpm/tpm.h | 11 ----- drivers/char/tpm/tpm1-cmd.c | 84 ++++++++++++++++++-------------- 3 files changed, 49 insertions(+), 48 deletions(-) diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c index e6ece49e18a8..a6c5d40e30b0 100644 --- a/drivers/char/tpm/tpm-interface.c +++ b/drivers/char/tpm/tpm-interface.c @@ -600,7 +600,7 @@ EXPORT_SYMBOL_GPL(tpm_pm_resume); * @out: destination buffer for the random bytes * @max: the max number of bytes to write to @out * - * Return: same as with tpm_transmit_cmd() + * Return: number of random bytes read or a negative error value. */ int tpm_get_random(struct tpm_chip *chip, u8 *out, size_t max) { diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h index daca1d0190b1..6895f183396b 100644 --- a/drivers/char/tpm/tpm.h +++ b/drivers/char/tpm/tpm.h @@ -396,20 +396,9 @@ struct tpm_pcrread_in { * compiler warnings about stack frame size. */ #define TPM_MAX_RNG_DATA 128 -struct tpm_getrandom_out { - __be32 rng_data_len; - u8 rng_data[TPM_MAX_RNG_DATA]; -} __packed; - -struct tpm_getrandom_in { - __be32 num_bytes; -} __packed; - typedef union { struct tpm_pcrread_in pcrread_in; struct tpm_pcrread_out pcrread_out; - struct tpm_getrandom_in getrandom_in; - struct tpm_getrandom_out getrandom_out; } tpm_cmd_params; struct tpm_cmd_t { diff --git a/drivers/char/tpm/tpm1-cmd.c b/drivers/char/tpm/tpm1-cmd.c index 8a84db315676..b5c4fa158c30 100644 --- a/drivers/char/tpm/tpm1-cmd.c +++ b/drivers/char/tpm/tpm1-cmd.c @@ -505,58 +505,70 @@ ssize_t tpm1_getcap(struct tpm_chip *chip, u32 subcap_id, cap_t *cap, EXPORT_SYMBOL_GPL(tpm1_getcap); #define TPM_ORD_GET_RANDOM 70 -#define TPM_GETRANDOM_RESULT_SIZE 18 -static const struct tpm_input_header tpm_getrandom_header = { - .tag = cpu_to_be16(TPM_TAG_RQU_COMMAND), - .length = cpu_to_be32(14), - .ordinal = cpu_to_be32(TPM_ORD_GET_RANDOM) -}; +struct tpm1_get_random_out { + __be32 rng_data_len; + u8 rng_data[TPM_MAX_RNG_DATA]; +} __packed; -int tpm1_get_random(struct tpm_chip *chip, u8 *out, size_t max) +/** + * tpm1_get_random() - get random bytes from the TPM's RNG + * @chip: a &struct tpm_chip instance + * @dest: destination buffer for the random bytes + * @max: the maximum number of bytes to write to @dest + * + * Return: + * * number of bytes read + * * -errno or a TPM return code otherwise + */ +int tpm1_get_random(struct tpm_chip *chip, u8 *dest, size_t max) { - struct tpm_cmd_t tpm_cmd; + struct tpm1_get_random_out *out; + u32 num_bytes = min_t(u32, max, TPM_MAX_RNG_DATA); + struct tpm_buf buf; + u32 total = 0; + int retries = 5; u32 recd; - u32 num_bytes = min_t(u32, max, TPM_MAX_RNG_DATA); - u32 rlength; - int err, total = 0, retries = 5; - u8 *dest = out; + int rc; - if (!out || !num_bytes || max > TPM_MAX_RNG_DATA) - return -EINVAL; + rc = tpm_buf_init(&buf, TPM_TAG_RQU_COMMAND, TPM_ORD_GET_RANDOM); + if (rc) + return rc; do { - tpm_cmd.header.in = tpm_getrandom_header; - tpm_cmd.params.getrandom_in.num_bytes = cpu_to_be32(num_bytes); - - err = tpm_transmit_cmd(chip, NULL, &tpm_cmd, - TPM_GETRANDOM_RESULT_SIZE + num_bytes, - offsetof(struct tpm_getrandom_out, - rng_data), - 0, "attempting get random"); - if (err) - break; + tpm_buf_append_u32(&buf, num_bytes); + + rc = tpm_transmit_cmd(chip, NULL, buf.data, PAGE_SIZE, + sizeof(out->rng_data_len), 0, + "attempting get random"); + if (rc) + goto out; - recd = be32_to_cpu(tpm_cmd.params.getrandom_out.rng_data_len); + out = (struct tpm1_get_random_out *)&buf.data[TPM_HEADER_SIZE]; + + recd = be32_to_cpu(out->rng_data_len); if (recd > num_bytes) { - total = -EFAULT; - break; + rc = -EFAULT; + goto out; } - rlength = be32_to_cpu(tpm_cmd.header.out.length); - if (rlength < TPM_HEADER_SIZE + - offsetof(struct tpm_getrandom_out, rng_data) + - recd) { - total = -EFAULT; - break; + if (tpm_buf_length(&buf) < TPM_HEADER_SIZE + + sizeof(out->rng_data_len) + recd) { + rc = -EFAULT; + goto out; } - memcpy(dest, tpm_cmd.params.getrandom_out.rng_data, recd); + memcpy(dest, out->rng_data, recd); dest += recd; total += recd; num_bytes -= recd; - } while (retries-- && (size_t)total < max); - return total ? total : -EIO; + tpm_buf_reset(&buf, TPM_TAG_RQU_COMMAND, TPM_ORD_GET_RANDOM); + } while (retries-- && total < max); + + rc = total ? (int)total : -EIO; +out: + tpm_buf_destroy(&buf); + return rc; } #define TPM_ORDINAL_PCRREAD 21 -- 2.25.1