linux-kernel - [PATCH v6 25/26] integrity/powerpc: Improve error handling & reporting when loading certs

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Message-Id: <20230210080401.345462-26-ajd@linux.ibm.com>
Date:   Fri, 10 Feb 2023 19:04:00 +1100
From:   Andrew Donnellan <ajd@...ux.ibm.com>
To:     linuxppc-dev@...ts.ozlabs.org, linux-integrity@...r.kernel.org
Cc:     ruscur@...sell.cc, bgray@...ux.ibm.com, nayna@...ux.ibm.com,
        gcwilson@...ux.ibm.com, gjoyce@...ux.ibm.com, brking@...ux.ibm.com,
        stefanb@...ux.ibm.com, sudhakar@...ux.ibm.com,
        erichte@...ux.ibm.com, gregkh@...uxfoundation.org,
        linux-kernel@...r.kernel.org, zohar@...ux.ibm.com, joel@....id.au,
        npiggin@...il.com
Subject: [PATCH v6 25/26] integrity/powerpc: Improve error handling & reporting when loading certs

From: Russell Currey <ruscur@...sell.cc>

A few improvements to load_powerpc.c:

 - include integrity.h for the pr_fmt()
 - move all error reporting out of get_cert_list()
 - use ERR_PTR() to better preserve error detail
 - don't use pr_err() for missing keys

Reviewed-by: Mimi Zohar <zohar@...ux.ibm.com>
Signed-off-by: Russell Currey <ruscur@...sell.cc>
Signed-off-by: Andrew Donnellan <ajd@...ux.ibm.com>

---

v3: New patch
---
 .../integrity/platform_certs/load_powerpc.c   | 26 ++++++++++++++-----
 1 file changed, 20 insertions(+), 6 deletions(-)

diff --git a/security/integrity/platform_certs/load_powerpc.c b/security/integrity/platform_certs/load_powerpc.c
index 1e4f80a4e71c..dee51606d5f4 100644
--- a/security/integrity/platform_certs/load_powerpc.c
+++ b/security/integrity/platform_certs/load_powerpc.c
@@ -14,9 +14,15 @@
 #include <asm/secure_boot.h>
 #include <asm/secvar.h>
 #include "keyring_handler.h"
+#include "../integrity.h"
 
 /*
  * Get a certificate list blob from the named secure variable.
+ *
+ * Returns:
+ *  - a pointer to a kmalloc'd buffer containing the cert list on success
+ *  - NULL if the key does not exist
+ *  - an ERR_PTR on error
  */
 static __init void *get_cert_list(u8 *key, unsigned long keylen, u64 *size)
 {
@@ -25,19 +31,19 @@ static __init void *get_cert_list(u8 *key, unsigned long keylen, u64 *size)
 
 	rc = secvar_ops->get(key, keylen, NULL, size);
 	if (rc) {
-		pr_err("Couldn't get size: %d\n", rc);
-		return NULL;
+		if (rc == -ENOENT)
+			return NULL;
+		return ERR_PTR(rc);
 	}
 
 	db = kmalloc(*size, GFP_KERNEL);
 	if (!db)
-		return NULL;
+		return ERR_PTR(-ENOMEM);
 
 	rc = secvar_ops->get(key, keylen, db, size);
 	if (rc) {
 		kfree(db);
-		pr_err("Error reading %s var: %d\n", key, rc);
-		return NULL;
+		return ERR_PTR(rc);
 	}
 
 	return db;
@@ -69,7 +75,11 @@ static int __init load_powerpc_certs(void)
 	 */
 	db = get_cert_list("db", 3, &dbsize);
 	if (!db) {
-		pr_err("Couldn't get db list from firmware\n");
+		pr_info("Couldn't get db list from firmware\n");
+	} else if (IS_ERR(db)) {
+		rc = PTR_ERR(db);
+		pr_err("Error reading db from firmware: %d\n", rc);
+		return rc;
 	} else {
 		rc = parse_efi_signature_list("powerpc:db", db, dbsize,
 					      get_handler_for_db);
@@ -81,6 +91,10 @@ static int __init load_powerpc_certs(void)
 	dbx = get_cert_list("dbx", 4,  &dbxsize);
 	if (!dbx) {
 		pr_info("Couldn't get dbx list from firmware\n");
+	} else if (IS_ERR(dbx)) {
+		rc = PTR_ERR(dbx);
+		pr_err("Error reading dbx from firmware: %d\n", rc);
+		return rc;
 	} else {
 		rc = parse_efi_signature_list("powerpc:dbx", dbx, dbxsize,
 					      get_handler_for_dbx);
-- 
2.39.1