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Message-Id: <1472000243-7088-1-git-send-email-jarkko.sakkinen@linux.intel.com>
Date: Tue, 23 Aug 2016 20:57:22 -0400
From: Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
To: Peter Huewe <peterhuewe@....de>
Cc: linux-security-module@...r.kernel.org,
Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>,
stable@...r.kernel.org, Marcel Selhorst <tpmdd@...horst.net>,
Jason Gunthorpe <jgunthorpe@...idianresearch.com>,
tpmdd-devel@...ts.sourceforge.net (moderated list:TPM DEVICE DRIVER),
linux-kernel@...r.kernel.org (open list)
Subject: [PATCH] tpm: fix a race condition tpm2_unseal_trusted()
Unseal and load operations should be done as an atomic operation. This
commit introduces unlocked tpm_transmit() so that tpm2_unseal_trusted()
can do the locking by itself.
v2: Introduced an unlocked unseal operation instead of changing locking
strategy in order to make less intrusive bug fix and thus more
backportable.
v3: Have also separate __tpm_transmit() that takes 'flags' in order to
better localize the bug fix and make it easier to backport.
v4: Cleaned up the control flow in tpm2_unseal_trusted. Added the
missing 'Fixes' line.
Fixes: 0fe5480303a1 ("keys, trusted: seal/unseal with TPM 2.0 chips")
CC: stable@...r.kernel.org
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
---
drivers/char/tpm/tpm-interface.c | 16 +++++++++-------
drivers/char/tpm/tpm.h | 25 +++++++++++++++++++++----
drivers/char/tpm/tpm2-cmd.c | 12 ++++++++----
3 files changed, 38 insertions(+), 15 deletions(-)
diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c
index 43ef0ef..80e702a 100644
--- a/drivers/char/tpm/tpm-interface.c
+++ b/drivers/char/tpm/tpm-interface.c
@@ -330,8 +330,8 @@ EXPORT_SYMBOL_GPL(tpm_calc_ordinal_duration);
/*
* Internal kernel interface to transmit TPM commands
*/
-ssize_t tpm_transmit(struct tpm_chip *chip, const char *buf,
- size_t bufsiz)
+ssize_t __tpm_transmit(struct tpm_chip *chip, const char *buf,
+ size_t bufsiz, unsigned int flags)
{
ssize_t rc;
u32 count, ordinal;
@@ -350,7 +350,8 @@ ssize_t tpm_transmit(struct tpm_chip *chip, const char *buf,
return -E2BIG;
}
- mutex_lock(&chip->tpm_mutex);
+ if (flags & TPM_TRANSMIT_LOCK)
+ mutex_lock(&chip->tpm_mutex);
rc = chip->ops->send(chip, (u8 *) buf, count);
if (rc < 0) {
@@ -393,20 +394,21 @@ out_recv:
dev_err(&chip->dev,
"tpm_transmit: tpm_recv: error %zd\n", rc);
out:
- mutex_unlock(&chip->tpm_mutex);
+ if (flags & TPM_TRANSMIT_LOCK)
+ mutex_unlock(&chip->tpm_mutex);
return rc;
}
#define TPM_DIGEST_SIZE 20
#define TPM_RET_CODE_IDX 6
-ssize_t tpm_transmit_cmd(struct tpm_chip *chip, void *cmd,
- int len, const char *desc)
+ssize_t __tpm_transmit_cmd(struct tpm_chip *chip, void *cmd,
+ int len, const char *desc, unsigned int flags)
{
struct tpm_output_header *header;
int err;
- len = tpm_transmit(chip, (u8 *) cmd, len);
+ len = __tpm_transmit(chip, cmd, len, flags);
if (len < 0)
return len;
else if (len < TPM_HEADER_SIZE)
diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h
index 6e002c4..0a4abf0 100644
--- a/drivers/char/tpm/tpm.h
+++ b/drivers/char/tpm/tpm.h
@@ -476,12 +476,29 @@ extern dev_t tpm_devt;
extern const struct file_operations tpm_fops;
extern struct idr dev_nums_idr;
+enum tpm_transmit_flags {
+ TPM_TRANSMIT_LOCK,
+};
+
+ssize_t __tpm_transmit(struct tpm_chip *chip, const char *buf,
+ size_t bufsiz, unsigned int flags);
+ssize_t __tpm_transmit_cmd(struct tpm_chip *chip, void *cmd, int len,
+ const char *desc, unsigned int flags);
+
+static inline ssize_t tpm_transmit(struct tpm_chip *chip, const char *buf,
+ size_t bufsiz)
+{
+ return __tpm_transmit(chip, buf, bufsiz, TPM_TRANSMIT_LOCK);
+}
+
+static inline ssize_t tpm_transmit_cmd(struct tpm_chip *chip, void *cmd,
+ int len, const char *desc)
+{
+ return __tpm_transmit_cmd(chip, cmd, len, desc, TPM_TRANSMIT_LOCK);
+}
+
ssize_t tpm_getcap(struct tpm_chip *chip, __be32 subcap_id, cap_t *cap,
const char *desc);
-ssize_t tpm_transmit(struct tpm_chip *chip, const char *buf,
- size_t bufsiz);
-ssize_t tpm_transmit_cmd(struct tpm_chip *chip, void *cmd, int len,
- const char *desc);
int tpm_get_timeouts(struct tpm_chip *chip);
int tpm1_auto_startup(struct tpm_chip *chip);
int tpm_do_selftest(struct tpm_chip *chip);
diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c
index 499f405..a2a0314 100644
--- a/drivers/char/tpm/tpm2-cmd.c
+++ b/drivers/char/tpm/tpm2-cmd.c
@@ -576,7 +576,7 @@ static int tpm2_load(struct tpm_chip *chip,
goto out;
}
- rc = tpm_transmit_cmd(chip, buf.data, PAGE_SIZE, "loading blob");
+ rc = __tpm_transmit_cmd(chip, buf.data, PAGE_SIZE, "loading blob", 0);
if (!rc)
*blob_handle = be32_to_cpup(
(__be32 *) &buf.data[TPM_HEADER_SIZE]);
@@ -604,7 +604,8 @@ static void tpm2_flush_context(struct tpm_chip *chip, u32 handle)
tpm_buf_append_u32(&buf, handle);
- rc = tpm_transmit_cmd(chip, buf.data, PAGE_SIZE, "flushing context");
+ rc = __tpm_transmit_cmd(chip, buf.data, PAGE_SIZE, "flushing context",
+ 0);
if (rc)
dev_warn(&chip->dev, "0x%08x was not flushed, rc=%d\n", handle,
rc);
@@ -635,7 +636,7 @@ static int tpm2_unseal(struct tpm_chip *chip,
options->blobauth /* hmac */,
TPM_DIGEST_SIZE);
- rc = tpm_transmit_cmd(chip, buf.data, PAGE_SIZE, "unsealing");
+ rc = __tpm_transmit_cmd(chip, buf.data, PAGE_SIZE, "unsealing", 0);
if (rc > 0)
rc = -EPERM;
@@ -668,14 +669,17 @@ int tpm2_unseal_trusted(struct tpm_chip *chip,
u32 blob_handle;
int rc;
+ mutex_lock(&chip->tpm_mutex);
rc = tpm2_load(chip, payload, options, &blob_handle);
if (rc)
- return rc;
+ goto out;
rc = tpm2_unseal(chip, payload, options, blob_handle);
tpm2_flush_context(chip, blob_handle);
+out:
+ mutex_unlock(&chip->tpm_mutex);
return rc;
}
--
2.7.4
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