vold: remove session keyring workaround for old kernels
The android-4.14-stable and later kernels support the
FS_IOC_ADD_ENCRYPTION_KEY and FS_IOC_REMOVE_ENCRYPTION_KEY ioctls. This
has superseded the old way of adding fscrypt keys to the kernel, which
was to use the add_key() syscall to add keys to the "session" keyring.
On kernels that support the ioctls, Android doesn't use the obsolete
way. Since upgrading even just to Android 14 requires at minimum a
android-4.14-stable kernel (according to
https://source.android.com/docs/core/architecture/kernel/android-common#compatibility-matrix),
there is no need to support the obsolete way anymore.
Therefore, this commit removes the code that added and removed keys
to/from the session keyring. Now the ioctls are used unconditionally.
Flag: N/A for the following reasons:
- Removing obsolete code, which is fairly safe
- Very early code, so runtime flag cannot be used
- This topic also removes code from init, which cannot use aconfig
libraries because they do not support recovery_available
Bug: 311736104
Test: Build and boot Cuttlefish
Change-Id: I0d9abbda77b1ac838ea6f014dbe22ab032c0e5ae
4 files changed