Messages in this thread | | | Subject | Re: [PATCH v4 6/6] tpm: ensure that the output of PCR read contains the correct digest size | From | Roberto Sassu <> | Date | Thu, 8 Nov 2018 15:47:39 +0100 |
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On 11/8/2018 3:08 PM, Jarkko Sakkinen wrote: > On Tue, Nov 06, 2018 at 04:01:59PM +0100, Roberto Sassu wrote: >> This patch protects against data corruption that could happen in the bus, >> by checking that that the digest size returned by the TPM during a PCR read >> matches the size of the algorithm passed as argument to tpm2_pcr_read(). >> >> This check is performed after information about the PCR banks has been >> retrieved. >> >> Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com> >> --- >> drivers/char/tpm/tpm2-cmd.c | 16 +++++++++++++++- >> 1 file changed, 15 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c >> index e2d5b84286a7..3b0b5b032901 100644 >> --- a/drivers/char/tpm/tpm2-cmd.c >> +++ b/drivers/char/tpm/tpm2-cmd.c >> @@ -187,15 +187,28 @@ struct tpm2_pcr_read_out { >> int tpm2_pcr_read(struct tpm_chip *chip, int pcr_idx, >> struct tpm_digest *digest_struct, u16 *digest_size_ptr) >> { >> + int i; >> int rc; >> struct tpm_buf buf; >> struct tpm2_pcr_read_out *out; >> u8 pcr_select[TPM2_PCR_SELECT_MIN] = {0}; >> u16 digest_size; >> + u16 expected_digest_size = 0; >> >> if (pcr_idx >= TPM2_PLATFORM_PCR) >> return -EINVAL; >> >> + if (!digest_size_ptr) { >> + for (i = 0; i < chip->nr_active_banks && >> + chip->active_banks[i].alg_id != digest_struct->alg_id; i++) >> + ; > > Not sure if the semicolon should be in its own line.
scripts/Lindent suggests:
for (i = 0; i < chip->nr_active_banks && chip->active_banks[i].alg_id != digest_struct->alg_id; i++) ;
but this is not accepted by scripts/checkpatch.pl (there are no warnings/errors on the patch I sent).
>> + >> + if (i == chip->nr_active_banks) >> + return -EINVAL; >> + >> + expected_digest_size = chip->active_banks[i].digest_size; >> + } >> + >> rc = tpm_buf_init(&buf, TPM2_ST_NO_SESSIONS, TPM2_CC_PCR_READ); >> if (rc) >> return rc; >> @@ -215,7 +228,8 @@ int tpm2_pcr_read(struct tpm_chip *chip, int pcr_idx, >> >> out = (struct tpm2_pcr_read_out *)&buf.data[TPM_HEADER_SIZE]; >> digest_size = be16_to_cpu(out->digest_size); >> - if (digest_size > sizeof(digest_struct->digest)) { >> + if (digest_size > sizeof(digest_struct->digest) || >> + (!digest_size_ptr && digest_size != expected_digest_size)) { >> rc = -EINVAL; >> goto out; >> } >> -- >> 2.17.1 >> > > Please add > > Cc: stable@vger.kernel.org. > > /Jarkko >
-- HUAWEI TECHNOLOGIES Duesseldorf GmbH, HRB 56063 Managing Director: Bo PENG, Jian LI, Yanli SHI
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