diff options
| author | James Bottomley <James.Bottomley@HansenPartnership.com> | 2024-04-29 23:28:06 +0300 |
|---|---|---|
| committer | Jarkko Sakkinen <jarkko@kernel.org> | 2024-05-09 22:30:51 +0300 |
| commit | 6519fea6fd372b2247a48d72dcb23e14de70b4ea (patch) | |
| tree | 68f3d8b6e0bf56ea09cba6fc4b749c50d51a0038 /drivers | |
| parent | 1085b8276bb4239daa7008f0dcd5c973e4bd690f (diff) | |
| download | linux-6519fea6fd372b2247a48d72dcb23e14de70b4ea.tar.xz | |
tpm: add hmac checks to tpm2_pcr_extend()
tpm2_pcr_extend() is used by trusted keys to extend a PCR to prevent a
key from being re-loaded until the next reboot. To use this
functionality securely, that extend must be protected by a session
hmac. This patch adds HMAC protection so tampering with the
tpm2_pcr_extend() command in flight is detected.
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Tested-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/char/tpm/tpm2-cmd.c | 27 |
1 files changed, 10 insertions, 17 deletions
diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c index b0e72fb563d9..a53a843294ed 100644 --- a/drivers/char/tpm/tpm2-cmd.c +++ b/drivers/char/tpm/tpm2-cmd.c @@ -216,13 +216,6 @@ out: return rc; } -struct tpm2_null_auth_area { - __be32 handle; - __be16 nonce_size; - u8 attributes; - __be16 auth_size; -} __packed; - /** * tpm2_pcr_extend() - extend a PCR value * @@ -236,24 +229,22 @@ int tpm2_pcr_extend(struct tpm_chip *chip, u32 pcr_idx, struct tpm_digest *digests) { struct tpm_buf buf; - struct tpm2_null_auth_area auth_area; int rc; int i; - rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_PCR_EXTEND); + rc = tpm2_start_auth_session(chip); if (rc) return rc; - tpm_buf_append_u32(&buf, pcr_idx); + rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_PCR_EXTEND); + if (rc) { + tpm2_end_auth_session(chip); + return rc; + } - auth_area.handle = cpu_to_be32(TPM2_RS_PW); - auth_area.nonce_size = 0; - auth_area.attributes = 0; - auth_area.auth_size = 0; + tpm_buf_append_name(chip, &buf, pcr_idx, NULL); + tpm_buf_append_hmac_session(chip, &buf, 0, NULL, 0); - tpm_buf_append_u32(&buf, sizeof(struct tpm2_null_auth_area)); - tpm_buf_append(&buf, (const unsigned char *)&auth_area, - sizeof(auth_area)); tpm_buf_append_u32(&buf, chip->nr_allocated_banks); for (i = 0; i < chip->nr_allocated_banks; i++) { @@ -262,7 +253,9 @@ int tpm2_pcr_extend(struct tpm_chip *chip, u32 pcr_idx, chip->allocated_banks[i].digest_size); } + tpm_buf_fill_hmac_session(chip, &buf); rc = tpm_transmit_cmd(chip, &buf, 0, "attempting extend a PCR value"); + rc = tpm_buf_check_hmac_response(chip, &buf, rc); tpm_buf_destroy(&buf); |