On Fri, Oct 12, 2018 at 11:23 AM Dave Jiang <[email protected]> wrote:
>
> There are several issues WRT kernel key update when we are doing nvdimm
> security key update.
>
> 1. The kernel key created needs to have proper permission for update
> 2. We need to check key_update() return value and make sure it didn't fail
> 3. We need to not hold the key->sem when calling key_update() since it will
> call down_write() when doing modification to the key.
>
> Signed-off-by: Dave Jiang <[email protected]>
> ---
> drivers/nvdimm/security.c | 16 ++++++++++++----
> 1 file changed, 12 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/nvdimm/security.c b/drivers/nvdimm/security.c
> index 776c440a02ef..ef83bdf47c31 100644
> --- a/drivers/nvdimm/security.c
> +++ b/drivers/nvdimm/security.c
> @@ -27,7 +27,7 @@ static struct key *make_kernel_key(struct key *key)
>
> new_key = key_alloc(&key_type_logon, key->description,
> GLOBAL_ROOT_UID, GLOBAL_ROOT_GID, current_cred(),
> - KEY_POS_SEARCH, KEY_ALLOC_NOT_IN_QUOTA, NULL);
> + KEY_POS_ALL, KEY_ALLOC_NOT_IN_QUOTA, NULL);
Should that be (KEY_POS_ALL & ~KEY_POS_SETATTR)? I don't see a reason
why we would ever change key attributes.
> if (IS_ERR(new_key))
> return NULL;
>
> @@ -419,11 +419,19 @@ int nvdimm_security_change_key(struct nvdimm *nvdimm,
> dev_warn(dev, "key update failed: %d\n", rc);
>
> if (old_key) {
> + up_read(&old_key->sem);
> /* copy new payload to old payload */
Let's delete that comment and replace it with one that talks about the
locking rules. Namely that we are done with the old_key payload after
->change_key() returns and that key_update() will take the write lock
on the payload to update it.
> - if (rc == 0)
> - key_update(make_key_ref(old_key, 1), new_data,
> + if (rc == 0) {
> + rc = key_update(make_key_ref(old_key, 1), new_data,
> old_key->datalen);
> - up_read(&old_key->sem);
> + if (rc < 0) {
> + dev_warn(dev,
> + "kernel key update failed: %d\n", rc);
> + key_invalidate(old_key);
> + key_put(old_key);
I added a local 'key_destroy()' helper for that invalidate+put pattern.
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