[PATCH v3 14/24] powerpc/pseries: Fix alignment of PLPKS structures and buffers

From: Andrew Donnellan <ajd@linux.ibm.com>
To: linuxppc-dev@lists.ozlabs.org, linux-integrity@vger.kernel.org
Cc: gregkh@linuxfoundation.org, gcwilson@linux.ibm.com,
	linux-kernel@vger.kernel.org, nayna@linux.ibm.com,
	ruscur@russell.cc, zohar@linux.ibm.com, mpe@ellerman.id.au,
	gjoyce@linux.ibm.com, sudhakar@linux.ibm.com,
	bgray@linux.ibm.com, erichte@linux.ibm.com
Subject: [PATCH v3 14/24] powerpc/pseries: Fix alignment of PLPKS structures and buffers
Date: Wed, 18 Jan 2023 17:10:39 +1100	[thread overview]
Message-ID: <20230118061049.1006141-15-ajd@linux.ibm.com> (raw)
In-Reply-To: <20230118061049.1006141-1-ajd@linux.ibm.com>

A number of structures and buffers passed to PKS hcalls have alignment
requirements, which could on occasion cause problems:

- Authorisation structures must be 16-byte aligned and must not cross a
  page boundary

- Label structures must not cross page coundaries

- Password output buffers must not cross page boundaries

Round up the allocations of these structures/buffers to the next power of
2 to make sure this happens.

Reported-by: Benjamin Gray <bgray@linux.ibm.com>
Fixes: 2454a7af0f2a ("powerpc/pseries: define driver for Platform KeyStore")
Signed-off-by: Andrew Donnellan <ajd@linux.ibm.com>
Reviewed-by: Russell Currey <ruscur@russell.cc>
Signed-off-by: Russell Currey <ruscur@russell.cc>

---

v3: Merge plpks fixes and signed update series with secvar series
---
 arch/powerpc/platforms/pseries/plpks.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/platforms/pseries/plpks.c b/arch/powerpc/platforms/pseries/plpks.c
index 6d1303e4862d..91f3f623a2c7 100644
--- a/arch/powerpc/platforms/pseries/plpks.c
+++ b/arch/powerpc/platforms/pseries/plpks.c
@@ -112,7 +112,8 @@ static int plpks_gen_password(void)
 	u8 *password, consumer = PLPKS_OS_OWNER;
 	int rc;
 
-	password = kzalloc(maxpwsize, GFP_KERNEL);
+	// The password must not cross a page boundary, so we align to the next power of 2
+	password = kzalloc(roundup_pow_of_two(maxpwsize), GFP_KERNEL);
 	if (!password)
 		return -ENOMEM;
 
@@ -148,7 +149,9 @@ static struct plpks_auth *construct_auth(u8 consumer)
 	if (consumer > PLPKS_OS_OWNER)
 		return ERR_PTR(-EINVAL);
 
-	auth = kzalloc(struct_size(auth, password, maxpwsize), GFP_KERNEL);
+	// The auth structure must not cross a page boundary and must be
+	// 16 byte aligned. We align to the next largest power of 2
+	auth = kzalloc(roundup_pow_of_two(struct_size(auth, password, maxpwsize)), GFP_KERNEL);
 	if (!auth)
 		return ERR_PTR(-ENOMEM);
 
@@ -182,7 +185,8 @@ static struct label *construct_label(char *component, u8 varos, u8 *name,
 	if (component && slen > sizeof(label->attr.prefix))
 		return ERR_PTR(-EINVAL);
 
-	label = kzalloc(sizeof(*label), GFP_KERNEL);
+	// The label structure must not cross a page boundary, so we align to the next power of 2
+	label = kzalloc(roundup_pow_of_two(sizeof(*label)), GFP_KERNEL);
 	if (!label)
 		return ERR_PTR(-ENOMEM);
 
-- 
2.39.0

