Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
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 08/12] ima: Shallow copy the args_p member of ima_rule_entry.lsm elements
Date:   Thu,  9 Jul 2020 01:19:07 -0500
Message-Id: <20200709061911.954326-9-tyhicks@linux.microsoft.com>
In-Reply-To: <20200709061911.954326-1-tyhicks@linux.microsoft.com>
References: <20200709061911.954326-1-tyhicks@linux.microsoft.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

The args_p member is a simple string that is allocated by
ima_rule_init(). Shallow copy it like other non-LSM references in
ima_rule_entry structs.

There are no longer any necessary error path cleanups to do in
ima_lsm_copy_rule().

Signed-off-by: Tyler Hicks <tyhicks@linux.microsoft.com>
---

* v3
  - No change
* v2
  - Adjusted context to account for ima_lsm_copy_rule() directly calling
    ima_lsm_free_rule() and the lack of explicit reference ownership
    transfers
  - Added comment to ima_lsm_copy_rule() to document the args_p
    reference ownership transfer

 security/integrity/ima/ima_policy.c | 16 +++++++---------
 1 file changed, 7 insertions(+), 9 deletions(-)

diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
index 9842e2e0bc6d..b02e1ffd10c9 100644
--- a/security/integrity/ima/ima_policy.c
+++ b/security/integrity/ima/ima_policy.c
@@ -300,10 +300,13 @@ static struct ima_rule_entry *ima_lsm_copy_rule(struct ima_rule_entry *entry)
 			continue;
 
 		nentry->lsm[i].type = entry->lsm[i].type;
-		nentry->lsm[i].args_p = kstrdup(entry->lsm[i].args_p,
-						GFP_KERNEL);
-		if (!nentry->lsm[i].args_p)
-			goto out_err;
+		nentry->lsm[i].args_p = entry->lsm[i].args_p;
+		/*
+		 * Remove the reference from entry so that the associated
+		 * memory will not be freed during a later call to
+		 * ima_lsm_free_rule(entry).
+		 */
+		entry->lsm[i].args_p = NULL;
 
 		security_filter_rule_init(nentry->lsm[i].type,
 					  Audit_equal,
@@ -314,11 +317,6 @@ static struct ima_rule_entry *ima_lsm_copy_rule(struct ima_rule_entry *entry)
 				(char *)entry->lsm[i].args_p);
 	}
 	return nentry;
-
-out_err:
-	ima_lsm_free_rule(nentry);
-	kfree(nentry);
-	return NULL;
 }
 
 static int ima_lsm_update_rule(struct ima_rule_entry *entry)
-- 
2.25.1