linux-kernel - [PATCH 6.1 2/3] s390/pkey: Wipe copies of clear-key structures on failure

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Message-ID: <20241128153337.19666-3-n.zhandarovich@fintech.ru>
Date: Thu, 28 Nov 2024 07:33:36 -0800
From: Nikita Zhandarovich <n.zhandarovich@...tech.ru>
To: Greg Kroah-Hartman <gregkh@...uxfoundation.org>, Sasha Levin
	<sashal@...nel.org>, <stable@...r.kernel.org>
CC: Nikita Zhandarovich <n.zhandarovich@...tech.ru>, Harald Freudenberger
	<freude@...ux.ibm.com>, Heiko Carstens <hca@...ux.ibm.com>, Vasily Gorbik
	<gor@...ux.ibm.com>, Christian Borntraeger <borntraeger@...ibm.com>, "Holger
 Dengler" <dengler@...ux.ibm.com>, Alexander Gordeev <agordeev@...ux.ibm.com>,
	<linux-s390@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<lvc-project@...uxtesting.org>
Subject: [PATCH 6.1 2/3] s390/pkey: Wipe copies of clear-key structures on failure

From: Holger Dengler <dengler@...ux.ibm.com>

commit d65d76a44ffe74c73298ada25b0f578680576073 upstream.

Wipe all sensitive data from stack for all IOCTLs, which convert a
clear-key into a protected- or secure-key.

Reviewed-by: Harald Freudenberger <freude@...ux.ibm.com>
Reviewed-by: Ingo Franzki <ifranzki@...ux.ibm.com>
Acked-by: Heiko Carstens <hca@...ux.ibm.com>
Signed-off-by: Holger Dengler <dengler@...ux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@...ux.ibm.com>
[Nikita: small changes were made during cherry-picking due to
different debug macro use and similar discrepancies between branches]
Signed-off-by: Nikita Zhandarovich <n.zhandarovich@...tech.ru>
---
P.S. As no Fixes: tag was present, I decided against adding it myself
and leaving commit body intact.

 drivers/s390/crypto/pkey_api.c | 16 +++++++++-------
 1 file changed, 9 insertions(+), 7 deletions(-)

diff --git a/drivers/s390/crypto/pkey_api.c b/drivers/s390/crypto/pkey_api.c
index d1429622036f..0aaa8686a0b2 100644
--- a/drivers/s390/crypto/pkey_api.c
+++ b/drivers/s390/crypto/pkey_api.c
@@ -1188,9 +1188,7 @@ static long pkey_unlocked_ioctl(struct file *filp, unsigned int cmd,
 		rc = cca_clr2seckey(kcs.cardnr, kcs.domain, kcs.keytype,
 				    kcs.clrkey.clrkey, kcs.seckey.seckey);
 		DEBUG_DBG("%s cca_clr2seckey()=%d\n", __func__, rc);
-		if (rc)
-			break;
-		if (copy_to_user(ucs, &kcs, sizeof(kcs)))
+		if (!rc && copy_to_user(ucs, &kcs, sizeof(kcs)))
 			rc = -EFAULT;
 		memzero_explicit(&kcs, sizeof(kcs));
 		break;
@@ -1220,9 +1218,7 @@ static long pkey_unlocked_ioctl(struct file *filp, unsigned int cmd,
 		rc = pkey_clr2protkey(kcp.keytype,
 				      &kcp.clrkey, &kcp.protkey);
 		DEBUG_DBG("%s pkey_clr2protkey()=%d\n", __func__, rc);
-		if (rc)
-			break;
-		if (copy_to_user(ucp, &kcp, sizeof(kcp)))
+		if (!rc && copy_to_user(ucp, &kcp, sizeof(kcp)))
 			rc = -EFAULT;
 		memzero_explicit(&kcp, sizeof(kcp));
 		break;
@@ -1366,11 +1362,14 @@ static long pkey_unlocked_ioctl(struct file *filp, unsigned int cmd,
 		if (copy_from_user(&kcs, ucs, sizeof(kcs)))
 			return -EFAULT;
 		apqns = _copy_apqns_from_user(kcs.apqns, kcs.apqn_entries);
-		if (IS_ERR(apqns))
+		if (IS_ERR(apqns)) {
+			memzero_explicit(&kcs, sizeof(kcs));
 			return PTR_ERR(apqns);
+		}
 		kkey = kzalloc(klen, GFP_KERNEL);
 		if (!kkey) {
 			kfree(apqns);
+			memzero_explicit(&kcs, sizeof(kcs));
 			return -ENOMEM;
 		}
 		rc = pkey_clr2seckey2(apqns, kcs.apqn_entries,
@@ -1380,15 +1379,18 @@ static long pkey_unlocked_ioctl(struct file *filp, unsigned int cmd,
 		kfree(apqns);
 		if (rc) {
 			kfree(kkey);
+			memzero_explicit(&kcs, sizeof(kcs));
 			break;
 		}
 		if (kcs.key) {
 			if (kcs.keylen < klen) {
 				kfree(kkey);
+				memzero_explicit(&kcs, sizeof(kcs));
 				return -EINVAL;
 			}
 			if (copy_to_user(kcs.key, kkey, klen)) {
 				kfree(kkey);
+				memzero_explicit(&kcs, sizeof(kcs));
 				return -EFAULT;
 			}
 		}
-- 
2.25.1