From: Tyler Hicks <tyhicks@linux.microsoft.com>
To: Mimi Zohar <zohar@linux.ibm.com>,
Dmitry Kasatkin <dmitry.kasatkin@gmail.com>
Cc: James Morris <jmorris@namei.org>,
"Serge E . Hallyn" <serge@hallyn.com>,
Lakshmi Ramasubramanian <nramas@linux.microsoft.com>,
Prakhar Srivastava <prsriva02@gmail.com>,
linux-kernel@vger.kernel.org, linux-integrity@vger.kernel.org,
linux-security-module@vger.kernel.org
Subject: [PATCH v2 05/11] ima: Fail rule parsing when the KEXEC_CMDLINE hook is combined with an invalid cond
Date: Fri, 26 Jun 2020 17:38:54 -0500 [thread overview]
Message-ID: <20200626223900.253615-6-tyhicks@linux.microsoft.com> (raw)
In-Reply-To: <20200626223900.253615-1-tyhicks@linux.microsoft.com>
The KEXEC_CMDLINE hook function only supports the pcr conditional. Make
this clear at policy load so that IMA policy authors don't assume that
other conditionals are supported.
Since KEXEC_CMDLINE's inception, ima_match_rules() has always returned
true on any loaded KEXEC_CMDLINE rule without any consideration for
other conditionals present in the rule. Make it clear that pcr is the
only supported KEXEC_CMDLINE conditional by returning an error during
policy load.
An example of why this is a problem can be explained with the following
rule:
dont_measure func=KEXEC_CMDLINE obj_type=foo_t
An IMA policy author would have assumed that rule is valid because the
parser accepted it but the result was that measurements for all
KEXEC_CMDLINE operations would be disabled.
Fixes: b0935123a183 ("IMA: Define a new hook to measure the kexec boot command line arguments")
Signed-off-by: Tyler Hicks <tyhicks@linux.microsoft.com>
Reviewed-by: Mimi Zohar <zohar@linux.ibm.com>
---
* v2
- Added Mimi's Reviewed-by
security/integrity/ima/ima_policy.c | 21 +++++++++++++++++++++
1 file changed, 21 insertions(+)
diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
index 166124d67774..676d5557af1a 100644
--- a/security/integrity/ima/ima_policy.c
+++ b/security/integrity/ima/ima_policy.c
@@ -343,6 +343,17 @@ static int ima_lsm_update_rule(struct ima_rule_entry *entry)
return 0;
}
+static bool ima_rule_contains_lsm_cond(struct ima_rule_entry *entry)
+{
+ int i;
+
+ for (i = 0; i < MAX_LSM_RULES; i++)
+ if (entry->lsm[i].args_p)
+ return true;
+
+ return false;
+}
+
/*
* The LSM policy can be reloaded, leaving the IMA LSM based rules referring
* to the old, stale LSM policy. Update the IMA LSM based rules to reflect
@@ -993,6 +1004,16 @@ static bool ima_validate_rule(struct ima_rule_entry *entry)
case POLICY_CHECK:
break;
case KEXEC_CMDLINE:
+ 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;
case KEY_CHECK:
if (entry->action & ~(MEASURE | DONT_MEASURE))
return false;
--
2.25.1
next prev parent reply other threads:[~2020-06-26 22:40 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-26 22:38 [PATCH v2 00/11] ima: Fix rule parsing bugs and extend KEXEC_CMDLINE rule support Tyler Hicks
2020-06-26 22:38 ` [PATCH v2 01/11] ima: Have the LSM free its audit rule Tyler Hicks
2020-06-26 22:38 ` [PATCH v2 02/11] ima: Free the entire rule when deleting a list of rules Tyler Hicks
2020-06-26 22:38 ` [PATCH v2 03/11] ima: Free the entire rule if it fails to parse Tyler Hicks
2020-06-26 22:38 ` [PATCH v2 04/11] ima: Fail rule parsing when buffer hook functions have an invalid action Tyler Hicks
2020-06-26 22:38 ` Tyler Hicks [this message]
2020-06-27 23:40 ` [PATCH v2 05/11] ima: Fail rule parsing when the KEXEC_CMDLINE hook is combined with an invalid cond Lakshmi Ramasubramanian
2020-06-26 22:38 ` [PATCH v2 06/11] ima: Fail rule parsing when the KEY_CHECK " Tyler Hicks
2020-06-27 23:39 ` Lakshmi Ramasubramanian
2020-06-26 22:38 ` [PATCH v2 07/11] ima: Shallow copy the args_p member of ima_rule_entry.lsm elements Tyler Hicks
2020-06-26 22:38 ` [PATCH v2 08/11] ima: Use correct type for " Tyler Hicks
2020-06-26 22:38 ` [PATCH v2 09/11] ima: Move validation of the keyrings conditional into ima_validate_rule() Tyler Hicks
2020-06-27 23:49 ` Lakshmi Ramasubramanian
2020-06-29 14:16 ` Tyler Hicks
2020-06-30 23:07 ` Mimi Zohar
2020-07-02 22:16 ` Tyler Hicks
2020-07-03 14:15 ` Mimi Zohar
2020-07-06 13:18 ` Tyler Hicks
2020-07-07 3:18 ` Mimi Zohar
2020-06-26 22:38 ` [PATCH v2 10/11] ima: Use the common function to detect LSM conditionals in a rule Tyler Hicks
2020-06-26 22:39 ` [PATCH v2 11/11] ima: Support additional conditionals in the KEXEC_CMDLINE hook function Tyler Hicks
2020-06-28 0:03 ` Lakshmi Ramasubramanian
2020-07-01 8:04 ` Dave Young
2020-07-01 14:38 ` Tyler Hicks
2020-07-01 0:29 ` [PATCH v2 00/11] ima: Fix rule parsing bugs and extend KEXEC_CMDLINE rule support Mimi Zohar
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