tpm: fix Atmel TPM crash caused by too frequent queries

BugLink: https://bugs.launchpad.net/bugs/1951822
[ Upstream commit 79ca6f74dae067681a779fd573c2eb59649989bc ]

The Atmel TPM 1.2 chips crash with error
`tpm_try_transmit: send(): error -62` since kernel 4.14.
It is observed from the kernel log after running `tpm_sealdata -z`.
The error thrown from the command is as follows
```
$ tpm_sealdata -z
Tspi_Key_LoadKey failed: 0x00001087 - layer=tddl,
code=0087 (135), I/O error
```

The issue was reproduced with the following Atmel TPM chip:
```
$ tpm_version
T0  TPM 1.2 Version Info:
  Chip Version:        1.2.66.1
  Spec Level:          2
  Errata Revision:     3
  TPM Vendor ID:       ATML
  TPM Version:         01010000
  Manufacturer Info:   41544d4c
```

The root cause of the issue is due to the TPM calls to msleep()
were replaced with usleep_range() [1], which reduces
the actual timeout. Via experiments, it is observed that
the original msleep(5) actually sleeps for 15ms.
Because of a known timeout issue in Atmel TPM 1.2 chip,
the shorter timeout than 15ms can cause the error described above.

A few further changes in kernel 4.16 [2] and 4.18 [3, 4] further
reduced the timeout to less than 1ms. With experiments,
the problematic timeout in the latest kernel is the one
for `wait_for_tpm_stat`.

To fix it, the patch reverts the timeout of `wait_for_tpm_stat`
to 15ms for all Atmel TPM 1.2 chips, but leave it untouched
for Ateml TPM 2.0 chip, and chips from other vendors.
As explained above, the chosen 15ms timeout is
the actual timeout before this issue introduced,
thus the old value is used here.
Particularly, TPM_ATML_TIMEOUT_WAIT_STAT_MIN is set to 14700us,
TPM_ATML_TIMEOUT_WAIT_STAT_MIN is set to 15000us according to
the existing TPM_TIMEOUT_RANGE_US (300us).
The fixed has been tested in the system with the affected Atmel chip
with no issues observed after boot up.

References:
[1] 9f3fc7bcddcb tpm: replace msleep() with usleep_range() in TPM
1.2/2.0 generic drivers
[2] cf151a9a44d5 tpm: reduce tpm polling delay in tpm_tis_core
[3] 59f5a6b07f64 tpm: reduce poll sleep time in tpm_transmit()
[4] 424eaf910c32 tpm: reduce polling time to usecs for even finer
granularity

Fixes: 9f3fc7bcddcb ("tpm: replace msleep() with usleep_range() in TPM 1.2/2.0 generic drivers")
Link: https://patchwork.kernel.org/project/linux-integrity/patch/20200926223150.109645-1-hao.wu@rubrik.com/
Signed-off-by: Hao Wu <hao.wu@rubrik.com>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Paolo Pisati <paolo.pisati@canonical.com>

diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c
index 69579efb247b3b7508df00d5796cb9d429db3889..b2659a4c401687342f2ce21bfa80ceea3e238842 100644 (file)
--- a/drivers/char/tpm/tpm_tis_core.c
+++ b/drivers/char/tpm/tpm_tis_core.c
@@ -48,6 +48,7 @@ static int wait_for_tpm_stat(struct tpm_chip *chip, u8 mask,
                unsigned long timeout, wait_queue_head_t *queue,
                bool check_cancel)
 {
+       struct tpm_tis_data *priv = dev_get_drvdata(&chip->dev);
        unsigned long stop;
        long rc;
        u8 status;
@@ -80,8 +81,8 @@ again:
                }
        } else {
                do {
-                       usleep_range(TPM_TIMEOUT_USECS_MIN,
-                                    TPM_TIMEOUT_USECS_MAX);
+                       usleep_range(priv->timeout_min,
+                                    priv->timeout_max);
                        status = chip->ops->status(chip);
                        if ((status & mask) == mask)
                                return 0;
@@ -945,7 +946,22 @@ int tpm_tis_core_init(struct device *dev, struct tpm_tis_data *priv, int irq,
        chip->timeout_b = msecs_to_jiffies(TIS_TIMEOUT_B_MAX);
        chip->timeout_c = msecs_to_jiffies(TIS_TIMEOUT_C_MAX);
        chip->timeout_d = msecs_to_jiffies(TIS_TIMEOUT_D_MAX);
+       priv->timeout_min = TPM_TIMEOUT_USECS_MIN;
+       priv->timeout_max = TPM_TIMEOUT_USECS_MAX;
        priv->phy_ops = phy_ops;
+
+       rc = tpm_tis_read32(priv, TPM_DID_VID(0), &vendor);
+       if (rc < 0)
+               goto out_err;
+
+       priv->manufacturer_id = vendor;
+
+       if (priv->manufacturer_id == TPM_VID_ATML &&
+               !(chip->flags & TPM_CHIP_FLAG_TPM2)) {
+               priv->timeout_min = TIS_TIMEOUT_MIN_ATML;
+               priv->timeout_max = TIS_TIMEOUT_MAX_ATML;
+       }
+
        dev_set_drvdata(&chip->dev, priv);
 
        if (is_bsw()) {
@@ -988,12 +1004,6 @@ int tpm_tis_core_init(struct device *dev, struct tpm_tis_data *priv, int irq,
        if (rc)
                goto out_err;
 
-       rc = tpm_tis_read32(priv, TPM_DID_VID(0), &vendor);
-       if (rc < 0)
-               goto out_err;
-
-       priv->manufacturer_id = vendor;
-
        rc = tpm_tis_read8(priv, TPM_RID(0), &rid);
        if (rc < 0)
                goto out_err;

diff --git a/drivers/char/tpm/tpm_tis_core.h b/drivers/char/tpm/tpm_tis_core.h
index b2a3c6c72882d48feada725f9e3bcda3ca53010e..3be24f221e32af812e276acac08f88c29e60eb15 100644 (file)
--- a/drivers/char/tpm/tpm_tis_core.h
+++ b/drivers/char/tpm/tpm_tis_core.h
@@ -54,6 +54,8 @@ enum tis_defaults {
        TIS_MEM_LEN = 0x5000,
        TIS_SHORT_TIMEOUT = 750,        /* ms */
        TIS_LONG_TIMEOUT = 2000,        /* 2 sec */
+       TIS_TIMEOUT_MIN_ATML = 14700,   /* usecs */
+       TIS_TIMEOUT_MAX_ATML = 15000,   /* usecs */
 };
 
 /* Some timeout values are needed before it is known whether the chip is
@@ -98,6 +100,8 @@ struct tpm_tis_data {
        wait_queue_head_t read_queue;
        const struct tpm_tis_phy_ops *phy_ops;
        unsigned short rng_quality;
+       unsigned int timeout_min; /* usecs */
+       unsigned int timeout_max; /* usecs */
 };
 
 struct tpm_tis_phy_ops {

diff --git a/include/linux/tpm.h b/include/linux/tpm.h
index aa11fe323c56b5d86a7d66095a826cf0e4cf1c57..12d827734686dd9f8bcc846c311384ed5c070980 100644 (file)
--- a/include/linux/tpm.h
+++ b/include/linux/tpm.h
@@ -269,6 +269,7 @@ enum tpm2_cc_attrs {
 #define TPM_VID_INTEL    0x8086
 #define TPM_VID_WINBOND  0x1050
 #define TPM_VID_STM      0x104A
+#define TPM_VID_ATML     0x1114
 
 enum tpm_chip_flags {
        TPM_CHIP_FLAG_TPM2              = BIT(1),