From: Lakshmi Ramasubramanian <nramas@linux.microsoft.com>
To: Tyler Hicks <tyhicks@linux.microsoft.com>
Cc: zohar@linux.ibm.com, stephen.smalley.work@gmail.com,
casey@schaufler-ca.com, sashal@kernel.org, jmorris@namei.org,
linux-integrity@vger.kernel.org, selinux@vger.kernel.org,
linux-security-module@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v5 1/4] IMA: Add func to measure LSM state and policy
Date: Thu, 30 Jul 2020 08:15:34 -0700 [thread overview]
Message-ID: <c2f0c4cc-67a9-d467-1b2c-7edaea47c9d6@linux.microsoft.com> (raw)
In-Reply-To: <20200730150228.GV4181@sequoia>
On 7/30/20 8:02 AM, Tyler Hicks wrote:
>> diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
>> index 07f033634b27..a0f5c39d9084 100644
>> --- a/security/integrity/ima/ima_policy.c
>> +++ b/security/integrity/ima/ima_policy.c
>> @@ -442,13 +442,20 @@ static bool ima_match_rules(struct ima_rule_entry *rule, struct inode *inode,
>> {
>> int i;
>>
>> - if (func == KEY_CHECK) {
>> - return (rule->flags & IMA_FUNC) && (rule->func == func) &&
>> - ima_match_keyring(rule, keyring, cred);
>> - }
>> if ((rule->flags & IMA_FUNC) &&
>> (rule->func != func && func != POST_SETATTR))
>> return false;
>> +
>> + switch (func) {
>> + case KEY_CHECK:
>> + return ima_match_keyring(rule, keyring, cred);
>> + case LSM_STATE:
>> + case LSM_POLICY:
>> + return true;
>> + default:
>> + break;
>> + }
>> +
>> if ((rule->flags & IMA_MASK) &&
>> (rule->mask != mask && func != POST_SETATTR))
>> return false;
>> @@ -1044,6 +1051,18 @@ static bool ima_validate_rule(struct ima_rule_entry *entry)
>> if (ima_rule_contains_lsm_cond(entry))
>> return false;
>>
>> + break;
>> + case LSM_STATE:
>> + case LSM_POLICY:
>> + if (entry->action & ~(MEASURE | DONT_MEASURE))
>> + return false;
>> +
>> + if (entry->flags & ~(IMA_FUNC | IMA_PCR))
>> + return false;
>> +
>> + if (ima_rule_contains_lsm_cond(entry))
>> + return false;
>> +
>> break;
>> default:
>> return false;
>> @@ -1176,6 +1195,10 @@ static int ima_parse_rule(char *rule, struct ima_rule_entry *entry)
>> entry->func = KEXEC_CMDLINE;
>> else if (strcmp(args[0].from, "KEY_CHECK") == 0)
>> entry->func = KEY_CHECK;
>> + else if (strcmp(args[0].from, "LSM_STATE") == 0)
>> + entry->func = LSM_STATE;
>> + else if (strcmp(args[0].from, "LSM_POLICY") == 0)
>> + entry->func = LSM_POLICY;
>
> This patch generally looks really good to me with the exception of one
> thing...
>
> We should only accept rules with these specified hook functions when an
> LSM that has measurement support is enabled. This messes up the ordering
> of your patch series but it could be as simple as doing this:
>
> else if (IS_ENABLED(CONFIG_SECURITY_SELINUX) &&
> strcmp(args[0].from, "LSM_STATE") == 0)
> entry->func = LSM_STATE;
>
> Or you could do something a little more complex, like what's done with
> CONFIG_IMA_LSM_RULES. You could create a CONFIG_IMA_MEASURE_LSM option
> that's default enabled but depends on CONFIG_SECURITY_SELINUX and then
> check for IS_ENABLED(CONFIG_IMA_MEASURE_LSM) in ima_parse_rule().
>
> I'd personally opt for just placing the
> IS_ENABLED(CONFIG_SECURITY_SELINUX) check directly into
> ima_parse_rule().
>
The LSM hook can be used by any security module (not just SELinux) to
measure their data.
I have implemented measurement in SELinux to illustrate the usage.
Maybe, I can add the check you have suggested for now and when more
security modules start using this IMA policy additional checks can be
added as appropriate.
thanks,
-lakshmi
next prev parent reply other threads:[~2020-07-30 15:15 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-30 3:47 [PATCH v5 0/4] LSM: Measure security module data Lakshmi Ramasubramanian
2020-07-30 3:47 ` [PATCH v5 1/4] IMA: Add func to measure LSM state and policy Lakshmi Ramasubramanian
2020-07-30 15:02 ` Tyler Hicks
2020-07-30 15:15 ` Lakshmi Ramasubramanian [this message]
2020-07-30 15:17 ` Tyler Hicks
2020-07-30 16:19 ` Casey Schaufler
2020-07-30 16:33 ` Lakshmi Ramasubramanian
2020-07-30 3:47 ` [PATCH v5 2/4] IMA: Define IMA hooks " Lakshmi Ramasubramanian
2020-07-30 15:04 ` Tyler Hicks
2020-07-30 3:47 ` [PATCH v5 3/4] LSM: Define SELinux function to measure " Lakshmi Ramasubramanian
2020-08-03 15:11 ` Stephen Smalley
2020-08-03 16:14 ` Lakshmi Ramasubramanian
2020-08-03 20:00 ` Stephen Smalley
2020-08-03 20:29 ` Stephen Smalley
2020-08-03 20:37 ` Lakshmi Ramasubramanian
2020-08-03 21:07 ` Stephen Smalley
2020-08-03 22:08 ` Lakshmi Ramasubramanian
2020-08-04 15:20 ` Stephen Smalley
2020-08-04 15:29 ` Stephen Smalley
2020-08-04 15:57 ` Lakshmi Ramasubramanian
2020-07-30 3:47 ` [PATCH v5 4/4] IMA: Handle early boot data measurement Lakshmi Ramasubramanian
2020-07-30 18:02 ` Lakshmi Ramasubramanian
2020-07-30 20:04 ` Tyler Hicks
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=c2f0c4cc-67a9-d467-1b2c-7edaea47c9d6@linux.microsoft.com \
--to=nramas@linux.microsoft.com \
--cc=casey@schaufler-ca.com \
--cc=jmorris@namei.org \
--cc=linux-integrity@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-security-module@vger.kernel.org \
--cc=sashal@kernel.org \
--cc=selinux@vger.kernel.org \
--cc=stephen.smalley.work@gmail.com \
--cc=tyhicks@linux.microsoft.com \
--cc=zohar@linux.ibm.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).