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Message-ID: <20181108134651.GA8922@linux.intel.com>
Date: Thu, 8 Nov 2018 15:46:51 +0200
From: Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
To: Roberto Sassu <roberto.sassu@...wei.com>
Cc: zohar@...ux.ibm.com, linux-integrity@...r.kernel.org,
linux-security-module@...r.kernel.org,
linux-kernel@...r.kernel.org, silviu.vlasceanu@...wei.com
Subject: Re: [PATCH v4 1/6] tpm: dynamically allocate active_banks array
Orrayn Tue, Nov 06, 2018 at 04:01:54PM +0100, Roberto Sassu wrote:
> This patch removes the hard-coded limit of the active_banks array size.
> It stores in the tpm_chip structure the number of active PCR banks,
> determined in tpm2_get_pcr_allocation(), and replaces the static array
> with a pointer to a dynamically allocated array.
>
> As a consequence of the introduction of nr_active_banks, tpm_pcr_extend()
> does not check anymore if the algorithm stored in tpm_chip is equal to
> zero. The active_banks array always contains valid algorithms.
>
> Fixes: 1db15344f874 ("tpm: implement TPM 2.0 capability to get active
> PCR banks")
>
> Signed-off-by: Roberto Sassu <roberto.sassu@...wei.com>
> ---
> drivers/char/tpm/tpm-chip.c | 1 +
> drivers/char/tpm/tpm-interface.c | 19 ++++++++++++-------
> drivers/char/tpm/tpm.h | 3 ++-
> drivers/char/tpm/tpm2-cmd.c | 17 ++++++++---------
> 4 files changed, 23 insertions(+), 17 deletions(-)
>
> diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c
> index 46caadca916a..2a9e8b744436 100644
> --- a/drivers/char/tpm/tpm-chip.c
> +++ b/drivers/char/tpm/tpm-chip.c
> @@ -160,6 +160,7 @@ static void tpm_dev_release(struct device *dev)
> kfree(chip->log.bios_event_log);
> kfree(chip->work_space.context_buf);
> kfree(chip->work_space.session_buf);
> + kfree(chip->active_banks);
> kfree(chip);
> }
>
> diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c
> index 1a803b0cf980..ba7ca6b3e664 100644
> --- a/drivers/char/tpm/tpm-interface.c
> +++ b/drivers/char/tpm/tpm-interface.c
> @@ -1039,8 +1039,7 @@ static int tpm1_pcr_extend(struct tpm_chip *chip, int pcr_idx, const u8 *hash,
> int tpm_pcr_extend(struct tpm_chip *chip, int pcr_idx, const u8 *hash)
> {
> int rc;
> - struct tpm2_digest digest_list[ARRAY_SIZE(chip->active_banks)];
> - u32 count = 0;
> + struct tpm2_digest *digest_list;
> int i;
>
> chip = tpm_find_get_ops(chip);
> @@ -1048,16 +1047,22 @@ int tpm_pcr_extend(struct tpm_chip *chip, int pcr_idx, const u8 *hash)
> return -ENODEV;
Should take digest_list as input. Probably callers could re-use the
same digest_list array multiple times?
Move struct tpm_chip to include/linux/tpm.h so that the caller can query
nr_active_banks and active_banks and can create the digest array by
itself. Lets do this right at once now that this is being restructured.
>
> if (chip->flags & TPM_CHIP_FLAG_TPM2) {
> - memset(digest_list, 0, sizeof(digest_list));
> + digest_list = kmalloc_array(chip->nr_active_banks,
> + sizeof(*digest_list), GFP_KERNEL);
> + if (!digest_list)
> + return -ENOMEM;
>
> - for (i = 0; i < ARRAY_SIZE(chip->active_banks) &&
> - chip->active_banks[i] != TPM2_ALG_ERROR; i++) {
> + memset(digest_list, 0,
> + chip->nr_active_banks * sizeof(*digest_list));
You should use kcalloc() to allocate digest_list.
> +
> + for (i = 0; i < chip->nr_active_banks; i++) {
> digest_list[i].alg_id = chip->active_banks[i];
> memcpy(digest_list[i].digest, hash, TPM_DIGEST_SIZE);
> - count++;
> }
>
> - rc = tpm2_pcr_extend(chip, pcr_idx, count, digest_list);
> + rc = tpm2_pcr_extend(chip, pcr_idx, chip->nr_active_banks,
> + digest_list);
> + kfree(digest_list);
> tpm_put_ops(chip);
> return rc;
> }
> diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h
> index f3501d05264f..98368c3a6ff7 100644
> --- a/drivers/char/tpm/tpm.h
> +++ b/drivers/char/tpm/tpm.h
> @@ -248,7 +248,8 @@ struct tpm_chip {
> const struct attribute_group *groups[3];
> unsigned int groups_cnt;
>
> - u16 active_banks[7];
> + u32 nr_active_banks;
> + u16 *active_banks;
> #ifdef CONFIG_ACPI
> acpi_handle acpi_dev_handle;
> char ppi_version[TPM_PPI_VERSION_LEN + 1];
> diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c
> index c31b490bd41d..533089cede07 100644
> --- a/drivers/char/tpm/tpm2-cmd.c
> +++ b/drivers/char/tpm/tpm2-cmd.c
> @@ -242,7 +242,7 @@ int tpm2_pcr_extend(struct tpm_chip *chip, int pcr_idx, u32 count,
> int i;
> int j;
>
> - if (count > ARRAY_SIZE(chip->active_banks))
> + if (count > chip->nr_active_banks)
> return -EINVAL;
>
> rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_PCR_EXTEND);
> @@ -859,7 +859,6 @@ static ssize_t tpm2_get_pcr_allocation(struct tpm_chip *chip)
> void *marker;
> void *end;
> void *pcr_select_offset;
> - unsigned int count;
> u32 sizeof_pcr_selection;
> u32 rsp_len;
> int rc;
> @@ -878,11 +877,14 @@ static ssize_t tpm2_get_pcr_allocation(struct tpm_chip *chip)
> if (rc)
> goto out;
>
> - count = be32_to_cpup(
> + chip->nr_active_banks = be32_to_cpup(
> (__be32 *)&buf.data[TPM_HEADER_SIZE + 5]);
>
> - if (count > ARRAY_SIZE(chip->active_banks)) {
> - rc = -ENODEV;
> + chip->active_banks = kmalloc_array(chip->nr_active_banks,
> + sizeof(*chip->active_banks),
> + GFP_KERNEL);
> + if (!chip->active_banks) {
> + rc = -ENOMEM;
> goto out;
> }
>
> @@ -891,7 +893,7 @@ static ssize_t tpm2_get_pcr_allocation(struct tpm_chip *chip)
> rsp_len = be32_to_cpup((__be32 *)&buf.data[2]);
> end = &buf.data[rsp_len];
>
> - for (i = 0; i < count; i++) {
> + for (i = 0; i < chip->nr_active_banks; i++) {
> pcr_select_offset = marker +
> offsetof(struct tpm2_pcr_selection, size_of_select);
> if (pcr_select_offset >= end) {
> @@ -908,9 +910,6 @@ static ssize_t tpm2_get_pcr_allocation(struct tpm_chip *chip)
> }
>
> out:
> - if (i < ARRAY_SIZE(chip->active_banks))
> - chip->active_banks[i] = TPM2_ALG_ERROR;
> -
> tpm_buf_destroy(&buf);
>
> return rc;
> --
> 2.17.1
>
/Jarkko
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