From: Roberto Sassu <roberto.sassu@xxxxxxxxxx>
In preparation for moving IMA and EVM to the LSM infrastructure, introduce
the file_pre_free_security hook.
It is useful for IMA to calculate the digest of the file content, just
before a file descriptor is closed, and update the security.ima xattr with
the new value.
LSMs should use this hook instead of file_free_security, if they still need
to access the opened file, before it is closed. The new hook cannot return
an error and cannot cause the operation to be canceled.
Signed-off-by: Roberto Sassu <roberto.sassu@xxxxxxxxxx>