On Wed, Mar 24, 2021 at 12:21 PM Tetsuo Handa
[off-list ref] wrote:

On 2021/03/24 20:10, Mimi Zohar wrote:

quoted

On Wed, 2021-03-24 at 19:10 +0900, Tetsuo Handa wrote:

quoted

On 2021/03/24 1:13, Mimi Zohar wrote:

quoted

On Wed, 2021-03-24 at 00:14 +0900, Tetsuo Handa wrote:

quoted

On 2021/03/23 23:47, Mimi Zohar wrote:

quoted

Initially I also questioned making "integrity" an LSM.  Perhaps it's
time to reconsider.   For now, it makes sense to just fix the NULL
pointer dereferencing.

Do we think calling panic() as "fix the NULL pointer dereferencing" ?

Not supplying "integrity" as an "lsm=" option is a user error.  There
are only two options - allow or deny the caller to proceed.   If the
user is expecting the integrity subsystem to be properly working,
returning a NULL and allowing the system to boot (RFC patch version)
does not make sense.   Better to fail early.

What does the "user" mean? Those who load the vmlinux?
Only the "root" user (so called administrators)?
Any users including other than "root" user?

If the user means those who load the vmlinux, that user is explicitly asking
for disabling "integrity" for some reason. In that case, it is a bug if
booting with "integrity" disabled is impossible.

If the user means something other than those who load the vmlinux,
is there a possibility that that user (especially non "root" users) is
allowed to try to use "integrity" ? If processes other than global init
process can try to use "integrity", wouldn't it be a DoS attack vector?
Please explain in the descripotion why calling panic() does not cause
DoS attack vector.

User in this case, is anyone rebooting the system and is intentionally
changing the default values, dropping the "integrity" option on the
boot command line.

OK. Then, I expect that the system boots instead of calling panic().
That user is explicitly asking for disabling "integrity" for some reason.

That was actually my intention. The prebuilt kernel that I use for
things has all LSMs enabled, but then I needed to try some workload
with only 1 specific LSM, so I gave a different lsm= argument.