thunderbolt: Allow clearing the key
PATCH 3/3 thunderbolt: Allow clearing the key
If secure authentication of a devices fails, either because the device already has another key uploaded, or there is some other error sending challenge to the device, and the user only wants to approve the device just once (without a new key being uploaded to the device) the current implementation does not allow this because the key cannot be cleared once set even if we allow it to be changed.
Make this scenario possible and allow clearing the key by writing empty string to the key sysfs file.
--- Documentation/ABI/testing/sysfs-bus-thunderbolt | 2 ++ drivers/thunderbolt/switch.c | 15 +++++++++++---- 2 files changed, 13 insertions(+), 4 deletions(-)
Documentation/ABI/testing/sysfs-bus-thunderbolt +2 -0
@@ -45,6 +45,8 @@ Contact: [email protected] Description: When a devices supports Thunderbolt secure connect it will have this attribute. Writing 32 byte hex string changes authorization to use the secure connection method instead. + Writing an empty string clears the key and regular connection + method can be used again. What: /sys/bus/thunderbolt/devices/.../device Date: Sep 2017
drivers/thunderbolt/switch.c +11 -4
@@ -807,8 +807,11 @@ static ssize_t key_store(struct device *dev, struct device_attribute *attr,struct tb_switch *sw =tb_to_switch (dev);u8 key[TB_SWITCH_KEY_SIZE ];ssize_t ret = count; +bool clear = false; -if (hex2bin (key, buf,sizeof (key))) +if (!strcmp (buf,"\n" )) + clear = true; +else if (hex2bin (key, buf,sizeof (key)))return -EINVAL ;if (mutex_lock_interruptible (&switch_lock))
@@ -818,9 +821,13 @@ static ssize_t key_store(struct device *dev, struct device_attribute *attr, ret = -EBUSY ; }else {kfree (sw->key); - sw->key =kmemdup (key,sizeof (key),GFP_KERNEL ); -if (!sw->key) - ret = -ENOMEM ; +if (clear) { + sw->key =NULL ; + }else { + sw->key =kmemdup (key,sizeof (key),GFP_KERNEL ); +if (!sw->key) + ret = -ENOMEM ; + } }mutex_unlock (&switch_lock);
Signature · 1 line
2.7.4
Quoted 11 lines · Yehezkel
If secure authentication of a devices fails, either because the device already has another key uploaded, or there is some other error sending challenge to the device, and the user only wants to approve the device just once (without a new key being uploaded to the device) the current implementation does not allow this because the key cannot be cleared once set even if we allow it to be changed.
Make this scenario possible and allow clearing the key by writing empty string to the key sysfs file.
Signed-off-by Yehezkel Bernat <[email protected]>