RE: [PATCH v4 1/3] ima: Introduce ima_get_current_hash_algo()
From: Roberto Sassu
Date: Fri Jul 23 2021 - 08:51:28 EST
> From: Mimi Zohar [mailto:zohar@xxxxxxxxxxxxx]
> Sent: Friday, July 23, 2021 2:49 PM
> On Fri, 2021-07-23 at 10:53 +0200, Roberto Sassu wrote:
> > Buffer measurements, unlike file measurements, are not accessible after the
> > measurement is done, as buffers are not suitable for use with the
> > integrity_iint_cache structure (there is no index, for files it is the
> > inode number). In the subsequent patches, the measurement (digest) will be
> > returned directly by the functions that perform the buffer measurement,
> > ima_measure_critical_data() and process_buffer_measurement().
> > A caller of those functions also needs to know the algorithm used to
> > calculate the digest. Instead of adding the algorithm as a new parameter to
> > the functions, this patch provides it separately with the new function
> > ima_get_current_hash_algo().
> > Since the hash algorithm does not change after the IMA setup phase, there
> > is no risk of races (obtaining a digest calculated with a different
> > algorithm than the one returned).
> Perfect explaination for annotating ima_hash_algo like:
> int __ro_after_init ima_hash_algo = HASH_ALGO_SHA1;
> Assuming you don't object, I'll include this change in this patch.
HUAWEI TECHNOLOGIES Duesseldorf GmbH, HRB 56063
Managing Director: Li Peng, Li Jian, Shi Yanli
> > Signed-off-by: Roberto Sassu <roberto.sassu@xxxxxxxxxx>
> > Reviewed-by: Lakshmi Ramasubramanian <nramas@xxxxxxxxxxxxxxxxxxx>