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Date: Tue, 16 Aug 2016 22:38:22 +0300
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.
CC: stable@...r.kernel.org
Fixes: 954650efb79f ("tpm: seal/unseal for TPM 2.0")
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
---
drivers/char/tpm/tpm-dev.c | 2 +-
drivers/char/tpm/tpm-interface.c | 14 ++++++++------
drivers/char/tpm/tpm.h | 18 ++++++++++++++----
drivers/char/tpm/tpm2-cmd.c | 13 +++++++++----
4 files changed, 32 insertions(+), 15 deletions(-)
diff --git a/drivers/char/tpm/tpm-dev.c b/drivers/char/tpm/tpm-dev.c
index f5d4521..8df8846 100644
--- a/drivers/char/tpm/tpm-dev.c
+++ b/drivers/char/tpm/tpm-dev.c
@@ -145,7 +145,7 @@ static ssize_t tpm_write(struct file *file, const char __user *buf,
return -EPIPE;
}
out_size = tpm_transmit(priv->chip, priv->data_buffer,
- sizeof(priv->data_buffer));
+ sizeof(priv->data_buffer), TPM_TRANSMIT_LOCK);
tpm_put_ops(priv->chip);
if (out_size < 0) {
diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c
index 43ef0ef..627daa7 100644
--- a/drivers/char/tpm/tpm-interface.c
+++ b/drivers/char/tpm/tpm-interface.c
@@ -331,7 +331,7 @@ 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)
+ 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..b9383fd 100644
--- a/drivers/char/tpm/tpm.h
+++ b/drivers/char/tpm/tpm.h
@@ -476,12 +476,22 @@ 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_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..99007d8 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;
@@ -668,13 +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)
+ if (rc) {
+ mutex_unlock(&chip->tpm_mutex);
return rc;
+ }
rc = tpm2_unseal(chip, payload, options, blob_handle);
tpm2_flush_context(chip, blob_handle);
+ mutex_unlock(&chip->tpm_mutex);
return rc;
}
--
2.7.4
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