Hi Roberto, On Fri, 2022-02-11 at 11:48 +0100, Roberto Sassu wrote: > __ima_inode_hash() checks if a digest has been already calculated by > looking for the integrity_iint_cache structure associated to the passed > inode. > > Users of ima_file_hash() and ima_inode_hash() (e.g. eBPF) might be > interested in obtaining the information without having to setup an IMA > policy so that the digest is always available at the time they call one of > those functions. > > Open a new file descriptor in __ima_inode_hash(), so that this function > could invoke ima_collect_measurement() to calculate the digest if it is not > available. Still return -EOPNOTSUPP if the calculation failed. > > Instead of opening a new file descriptor, the one from ima_file_hash() > could have been used. However, since ima_inode_hash() was created to obtain > the digest when the file descriptor is not available, it could benefit from > this change too. Also, the opened file descriptor might be not suitable for > use (file descriptor opened not for reading). > > This change does not cause memory usage increase, due to using a temporary > integrity_iint_cache structure for the digest calculation, and due to > freeing the ima_digest_data structure inside integrity_iint_cache before > exiting from __ima_inode_hash(). > > Finally, update the test by removing ima_setup.sh (it is not necessary > anymore to set an IMA policy) and by directly executing /bin/true. > > Signed-off-by: Roberto Sassu <roberto.sassu@xxxxxxxxxx> Although this patch doesn't directly modify either ima_file_hash() or ima_inode_hash(), this change affects both functions. ima_file_hash() was introduced to be used with eBPF. Based on Florent's post, changing the ima_file_hash() behavor seems fine. Since I have no idea whether anyone is still using ima_inode_hash(), perhaps it would be safer to limit this behavior change to just ima_file_hash(). Please update the ima_file_hash() doc. While touching this area, I'd appreciate your fixing the first doc line in both ima_file_hash() and ima_inode_hash() cases, which wraps spanning two lines. Please split the IMA from the eBPF changes. -- thanks, Mimi
