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 v3 05/12] ima: Fail rule parsing when the KEXEC_CMDLINE hook is combined with an invalid cond
Date: Thu, 9 Jul 2020 01:19:04 -0500 [thread overview]
Message-ID: <20200709061911.954326-6-tyhicks@linux.microsoft.com> (raw)
In-Reply-To: <20200709061911.954326-1-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>
Reviewed-by: Lakshmi Ramasubramanian <nramas@linux.microsoft.com>
---
* v3
- Adjust for the indentation change introduced in patch #4
- Added Lakshmi's Reviewed-by
* 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 40c28f1a6a5a..1c64bd6f1728 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
@@ -998,6 +1009,16 @@ static bool ima_validate_rule(struct ima_rule_entry *entry)
/* Validation of these hook functions is in ima_parse_rule() */
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:[~2020-07-09 6:20 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-09 6:18 [PATCH v3 00/12] ima: Fix rule parsing bugs and extend KEXEC_CMDLINE rule support Tyler Hicks
2020-07-09 6:19 ` [PATCH v3 01/12] ima: Have the LSM free its audit rule Tyler Hicks
2020-07-17 19:20 ` Nayna
2020-07-17 19:24 ` Tyler Hicks
2020-07-19 11:02 ` Mimi Zohar
2020-07-09 6:19 ` [PATCH v3 02/12] ima: Free the entire rule when deleting a list of rules Tyler Hicks
2020-07-09 6:19 ` [PATCH v3 03/12] ima: Free the entire rule if it fails to parse Tyler Hicks
2020-07-09 6:19 ` [PATCH v3 04/12] ima: Fail rule parsing when buffer hook functions have an invalid action Tyler Hicks
2020-07-09 6:19 ` Tyler Hicks [this message]
2020-07-09 6:19 ` [PATCH v3 06/12] ima: Fail rule parsing when the KEY_CHECK hook is combined with an invalid cond Tyler Hicks
2020-07-17 18:56 ` Nayna
2020-07-17 19:18 ` Tyler Hicks
2020-07-17 23:39 ` Tyler Hicks
2020-07-09 6:19 ` [PATCH v3 07/12] ima: Fail rule parsing when appraise_flag=blacklist is unsupportable Tyler Hicks
2020-07-16 18:14 ` Mimi Zohar
2020-07-16 18:20 ` Tyler Hicks
[not found] ` <76d2b27b-3b59-1852-046a-b1718c62b167@linux.vnet.ibm.com>
2020-07-17 18:11 ` Tyler Hicks
2020-07-20 17:02 ` Nayna
2020-07-09 6:19 ` [PATCH v3 08/12] ima: Shallow copy the args_p member of ima_rule_entry.lsm elements Tyler Hicks
2020-07-17 15:35 ` Konsta Karsisto
2020-07-17 16:51 ` Tyler Hicks
2020-07-09 6:19 ` [PATCH v3 09/12] ima: Use correct type for " Tyler Hicks
2020-07-09 6:19 ` [PATCH v3 10/12] ima: Move comprehensive rule validation checks out of the token parser Tyler Hicks
2020-07-09 6:19 ` [PATCH v3 11/12] ima: Use the common function to detect LSM conditionals in a rule Tyler Hicks
2020-07-09 6:19 ` [PATCH v3 12/12] ima: Support additional conditionals in the KEXEC_CMDLINE hook function Tyler Hicks
2020-07-17 4:31 ` [PATCH v3 00/12] ima: Fix rule parsing bugs and extend KEXEC_CMDLINE rule support Mimi Zohar
2020-07-17 4:34 ` Tyler Hicks
2020-07-20 21:38 ` Mimi Zohar
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