linux-kernel - [PATCH] TPM: chip disabled state erronously being reported as error

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-ID: <20120424205717.GA3755@localhost>
Date:	Tue, 24 Apr 2012 17:57:17 -0300
From:	Rajiv Andrade <srajiv@...ux.vnet.ibm.com>
To:	Paul Bolle <pebolle@...cali.nl>
Cc:	linux-kernel@...r.kernel.org, tpmdd-devel@...ts.sourceforge.net
Subject: [PATCH] TPM: chip disabled state erronously being reported as error

Hi Paul,

Can you test it?

Thanks,
Rajiv

---
tpm_do_selftest() attempts to read a PCR in order to
decide if one can rely on the TPM being used or not.
The function that's used by __tpm_pcr_read() does not
expect the TPM to be disabled or deactivated, and if so,
reports an error.

It's fine if the TPM returns this error when trying to
use it for the first time after a power cycle, but it's
definitely not if it already returned success for a
previous attempt to read one of its PCRs.

The tpm_do_selftest() was modified so that the driver only
reports this return code as an error when it really is.

Reported-by: Paul Bolle <pebolle@...cali.nl>
Signed-off-by: Rajiv Andrade <srajiv@...ux.vnet.ibm.com>
---
 drivers/char/tpm/tpm.c |   13 +++++++++++--
 1 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/drivers/char/tpm/tpm.c b/drivers/char/tpm/tpm.c
index ad7c732..9511abd 100644
--- a/drivers/char/tpm/tpm.c
+++ b/drivers/char/tpm/tpm.c
@@ -827,10 +827,10 @@ EXPORT_SYMBOL_GPL(tpm_pcr_extend);
 int tpm_do_selftest(struct tpm_chip *chip)
 {
 	int rc;
-	u8 digest[TPM_DIGEST_SIZE];
 	unsigned int loops;
 	unsigned int delay_msec = 1000;
 	unsigned long duration;
+	struct tpm_cmd_t cmd;
 
 	duration = tpm_calc_ordinal_duration(chip,
 	                                     TPM_ORD_CONTINUE_SELFTEST);
@@ -845,7 +845,16 @@ int tpm_do_selftest(struct tpm_chip *chip)
 		return rc;
 
 	do {
-		rc = __tpm_pcr_read(chip, 0, digest);
+		/* Attempt to read a PCR value */
+		cmd.header.in = pcrread_header;
+		cmd.params.pcrread_in.pcr_idx = cpu_to_be32(0);
+		rc = tpm_transmit(chip, (u8 *) &cmd, READ_PCR_RESULT_SIZE);
+
+		if (rc < TPM_HEADER_SIZE)
+			return -EFAULT;
+		else
+			rc = be32_to_cpu(cmd.header.out.return_code);
+
 		if (rc == TPM_ERR_DISABLED || rc == TPM_ERR_DEACTIVATED) {
 			dev_info(chip->dev,
 				 "TPM is disabled/deactivated (0x%X)\n", rc);
-- 
1.7.3.4

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/