Re: [PATCH v4 31/34] ima,evm: move initcalls to the LSM framework

[Mimi Zohar <zohar@linux.ibm.com>]

On Tue, 2025-09-30 at 16:11 -0400, Paul Moore wrote:
> On Tue, Sep 16, 2025 at 6:14 PM Paul Moore <paul@paul-moore.com> wrote:
> > 
> > From: Roberto Sassu <roberto.sassu@huawei.com>
> > 
> > This patch converts IMA and EVM to use the LSM frameworks's initcall
> > mechanism. It moved the integrity_fs_init() call to ima_fs_init() and
> > evm_init_secfs(), to work around the fact that there is no "integrity" LSM,
> > and introduced integrity_fs_fini() to remove the integrity directory, if
> > empty. Both integrity_fs_init() and integrity_fs_fini() support the
> > scenario of being called by both the IMA and EVM LSMs.
> > 
> > This patch does not touch any of the platform certificate code that
> > lives under the security/integrity/platform_certs directory as the
> > IMA/EVM developers would prefer to address that in a future patchset.
> > 
> > Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
> > [PM: adjust description as discussed over email]
> > Signed-off-by: Paul Moore <paul@paul-moore.com>
> > ---
> >  security/integrity/evm/evm_main.c  |  3 +--
> >  security/integrity/evm/evm_secfs.c | 11 +++++++++--
> >  security/integrity/iint.c          | 14 ++++++++++++--
> >  security/integrity/ima/ima_fs.c    | 11 +++++++++--
> >  security/integrity/ima/ima_main.c  |  4 ++--
> >  security/integrity/integrity.h     |  2 ++
> >  6 files changed, 35 insertions(+), 10 deletions(-)
> 
> I appreciate you reviewing most (all?) of the other patches in this
> patchset, but any chance you could review the IMA/EVM from Roberto?
> This is the only patch that really needs your review ...

Paul, I'm sorry for the long delay in reviewing and testing this patch set.  It
wasn't enough to just review this one patch, but it needed to be reviewed in
context.

The initcall ordering is extremely important for IMA. IMA-measurement needs to
be initialized after the TPM, otherwise IMA goes into TPM-bypass mode.  As
expected, the initcall ordering seems to be fine.  However this patch set
modifies the initcall debugging.

The kernel boot command line option "initcall_debug" outputs "entering initcall
level:" messages for each of the initcall levels, and "calling ...." and
"initcall ..." messages for the individual initcalls.

For example,
[ 0.896556] entering initcall level: arch
[ 0.896556] calling report_snp_info+0x0/0xd0 @ 1
[ 0.896556] initcall report_snp_info+0x0/0xd0 returned 0 after 0 usecs

With this patch set, the "calling ..." and "initcall ..." messages will not be
emitted for the LSMs. In lieu of these messages, the patch set defines a new
boot command line option "lsm.debug", which outputs "LSM: entering ....
initcall".

For example,
[ 2.225821] calling security_initcall_late+0x0/0xc0 @ 1
[ 2.225825] LSM: running ima late initcall

Regardless as to whether the performance information is actually necessary, the
initcall debugging change should probably be documented.  Maybe update
initcall_debug to reference lsm.debug in Documentation/admin-guide/kernel-
parameters.txt.

Mimi