From: Mimi Zohar <zohar@linux.ibm.com>
To: Casey Schaufler <casey@schaufler-ca.com>,
casey.schaufler@intel.com, jmorris@namei.org,
linux-security-module@vger.kernel.org, selinux@vger.kernel.org
Cc: linux-audit@redhat.com, keescook@chromium.org,
john.johansen@canonical.com, penguin-kernel@i-love.sakura.ne.jp,
paul@paul-moore.com, sds@tycho.nsa.gov,
linux-kernel@vger.kernel.org, bpf@vger.kernel.org
Subject: Re: [PATCH v23 02/23] LSM: Create and manage the lsmblob data structure.
Date: Tue, 29 Dec 2020 14:16:41 -0500 [thread overview]
Message-ID: <ed9e0dbb48b712a371d3ca4ea5dfa5121d2f98df.camel@linux.ibm.com> (raw)
In-Reply-To: <10442dd5-f16e-3ca4-c233-7394a11cbbad@schaufler-ca.com>
On Tue, 2020-12-29 at 10:46 -0800, Casey Schaufler wrote:
> >>>>>> -int security_audit_rule_match(u32 secid, u32 field, u32 op, void *lsmrule)
> >>>>>> +int security_audit_rule_match(u32 secid, u32 field, u32 op, void **lsmrule)
> >>>>>> {
> >>>>>> - return call_int_hook(audit_rule_match, 0, secid, field, op, lsmrule);
> >>>>>> + struct security_hook_list *hp;
> >>>>>> + int rc;
> >>>>>> +
> >>>>>> + hlist_for_each_entry(hp, &security_hook_heads.audit_rule_match, list) {
> >>>>>> + if (WARN_ON(hp->lsmid->slot < 0 || hp->lsmid->slot >= lsm_slot))
> >>>>>> + continue;
> >>>>>> + rc = hp->hook.audit_rule_match(secid, field, op,
> >>>>>> + &lsmrule[hp->lsmid->slot]);
> >>>>>> + if (rc)
> >>>>>> + return rc;
> >>>>> Suppose that there is an IMA dont_measure or dont_appraise rule, if one
> >>>>> LSM matches, then this returns true, causing any measurement or
> >>>>> integrity verification to be skipped.
> >>>> Yes, that is correct. Like the audit system, you're doing a string based
> >>>> lookup, which pretty well has to work this way. I have proposed compound
> >>>> label specifications in the past, but even if we accepted something like
> >>>> "apparmor=dates,selinux=figs" we'd still have to be compatible with the
> >>>> old style inputs.
> >>>>
> >>>>> Sample policy rules:
> >>>>> dont_measure obj_type=foo_log
> >>>>> dont_appraise obj_type=foo_log
> >>> IMA could extend the existing policy rules like "lsm=[selinux] |
> >>> [smack] | [apparmor]", but that assumes that the underlying
> >>> infrastructure supports it.
> >> Yes, but you would still need rational behavior in the
> >> case where someone has old IMA policy rules.
> > From an IMA perspective, allowing multiple LSMs to define the same
> > policy label is worse than requiring the label be constrained to a
> > particular LSM.
>
> Just to be sure we're talking about the same thing,
> the case I'm referring to is something like a file with
> two extended attributes:
>
> security.apparmor MacAndCheese
> security.SMACK64 MacAndCheese
>
> and an IMA rule that says
>
> dont_measure obj_type=MacAndCheese
>
> In this case the dont_measure will be applied to both.
> On the other hand,
>
> security.apparmor MacAndCheese
> security.SMACK64 FranksAndBeans
>
> would also apply the rule to both, which is not
> what you want. Unfortunately, there is no way to
> differentiate which LSM hit the rule.
>
> So now I'm a little confused. The case where both LSMs
> use the same label looks like it works right, where the
> case where they're different doesn't.
I'm more concerned about multiple LSMs using the same label. The
label's meaning is LSM specific.
>
> I'm beginning to think that identifying which LSMs matched
> a rule (it may be none, either or both) is the right solution.
> I don't think that audit is as sensitive to this.
If the label's meaning is LSM specific, then the rule needs to be LSM
specific.
next prev parent reply other threads:[~2020-12-29 19:17 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20201120201507.11993-1-casey.ref@schaufler-ca.com>
2020-11-20 20:14 ` [PATCH v22 00/23] LSM: Module stacking for AppArmor Casey Schaufler
2020-11-20 20:14 ` [PATCH v23 01/23] LSM: Infrastructure management of the sock security Casey Schaufler
2020-11-20 20:14 ` [PATCH v23 02/23] LSM: Create and manage the lsmblob data structure Casey Schaufler
2020-12-28 17:54 ` Mimi Zohar
2020-12-28 19:22 ` Casey Schaufler
2020-12-28 19:43 ` Mimi Zohar
2020-12-28 19:24 ` Mimi Zohar
2020-12-28 20:06 ` Casey Schaufler
2020-12-28 22:14 ` Mimi Zohar
2020-12-28 23:20 ` Casey Schaufler
2020-12-29 1:53 ` Mimi Zohar
2020-12-29 13:53 ` Mimi Zohar
2020-12-29 18:46 ` Casey Schaufler
2020-12-29 19:16 ` Mimi Zohar [this message]
2020-11-20 20:14 ` [PATCH v23 03/23] LSM: Use lsmblob in security_audit_rule_match Casey Schaufler
2020-11-20 20:14 ` [PATCH v23 04/23] LSM: Use lsmblob in security_kernel_act_as Casey Schaufler
2020-11-20 20:14 ` [PATCH v23 05/23] LSM: Use lsmblob in security_secctx_to_secid Casey Schaufler
2020-11-20 20:14 ` [PATCH v23 06/23] LSM: Use lsmblob in security_secid_to_secctx Casey Schaufler
2020-11-20 20:14 ` [PATCH v23 07/23] LSM: Use lsmblob in security_ipc_getsecid Casey Schaufler
2020-11-20 20:14 ` [PATCH v23 08/23] LSM: Use lsmblob in security_task_getsecid Casey Schaufler
2020-11-20 20:14 ` [PATCH v23 09/23] LSM: Use lsmblob in security_inode_getsecid Casey Schaufler
2020-11-20 20:14 ` [PATCH v23 10/23] LSM: Use lsmblob in security_cred_getsecid Casey Schaufler
2020-11-20 20:14 ` [PATCH v23 11/23] IMA: Change internal interfaces to use lsmblobs Casey Schaufler
2020-11-20 20:14 ` [PATCH v23 12/23] LSM: Specify which LSM to display Casey Schaufler
2020-11-20 20:14 ` [PATCH v23 13/23] LSM: Ensure the correct LSM context releaser Casey Schaufler
2020-11-20 20:14 ` [PATCH v23 14/23] LSM: Use lsmcontext in security_secid_to_secctx Casey Schaufler
2020-11-20 20:14 ` [PATCH v23 15/23] LSM: Use lsmcontext in security_inode_getsecctx Casey Schaufler
2020-11-20 20:15 ` [PATCH v23 16/23] LSM: security_secid_to_secctx in netlink netfilter Casey Schaufler
2020-11-20 20:15 ` [PATCH v23 17/23] NET: Store LSM netlabel data in a lsmblob Casey Schaufler
2020-11-20 20:15 ` [PATCH v23 18/23] LSM: Verify LSM display sanity in binder Casey Schaufler
2020-11-20 20:15 ` [PATCH v23 19/23] audit: add support for non-syscall auxiliary records Casey Schaufler
2020-11-20 20:15 ` [PATCH v23 20/23] Audit: Add new record for multiple process LSM attributes Casey Schaufler
2020-11-20 20:15 ` [PATCH v23 21/23] Audit: Add a new record for multiple object " Casey Schaufler
2020-11-20 20:15 ` [PATCH v23 22/23] LSM: Add /proc attr entry for full LSM context Casey Schaufler
2020-11-20 20:15 ` [PATCH v23 23/23] AppArmor: Remove the exclusive flag Casey Schaufler
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