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Wed, 18 Jan 2023 06:11:12 +0000 (GMT) Received: from jarvis-ozlabs-ibm-com.ozlabs.ibm.com (haven.au.ibm.com [9.192.254.114]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ozlabs.au.ibm.com (Postfix) with ESMTPSA id 516EF6060A; Wed, 18 Jan 2023 17:11:08 +1100 (AEDT) From: Andrew Donnellan To: linuxppc-dev@lists.ozlabs.org, linux-integrity@vger.kernel.org Subject: [PATCH v3 09/24] powerpc/secvar: Warn when PAGE_SIZE is smaller than max object size Date: Wed, 18 Jan 2023 17:10:34 +1100 Message-Id: <20230118061049.1006141-10-ajd@linux.ibm.com> X-Mailer: git-send-email 2.39.0 In-Reply-To: <20230118061049.1006141-1-ajd@linux.ibm.com> References: <20230118061049.1006141-1-ajd@linux.ibm.com> MIME-Version: 1.0 X-TM-AS-GCONF: 00 X-Proofpoint-GUID: fVyGledytYs5sCx6nVUetw8ke1ngkkir X-Proofpoint-ORIG-GUID: fVyGledytYs5sCx6nVUetw8ke1ngkkir X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.219,Aquarius:18.0.923,Hydra:6.0.562,FMLib:17.11.122.1 definitions=2023-01-18_01,2023-01-17_01,2022-06-22_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 impostorscore=0 malwarescore=0 spamscore=0 mlxscore=0 bulkscore=0 phishscore=0 adultscore=0 mlxlogscore=999 priorityscore=1501 clxscore=1015 suspectscore=0 lowpriorityscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2212070000 definitions=main-2301180051 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: sudhakar@linux.ibm.com, bgray@linux.ibm.com, erichte@linux.ibm.com, gregkh@linuxfoundation.org, nayna@linux.ibm.com, linux-kernel@vger.kernel.org, zohar@linux.ibm.com, gjoyce@linux.ibm.com, gcwilson@linux.ibm.com Errors-To: linuxppc-dev-bounces+incoming=patchwork.ozlabs.org@lists.ozlabs.org Sender: "Linuxppc-dev" Due to sysfs constraints, when writing to a variable, we can only handle writes of up to PAGE_SIZE. It's possible that the maximum object size is larger than PAGE_SIZE, in which case, print a warning on boot so that the user is aware. Signed-off-by: Andrew Donnellan Signed-off-by: Russell Currey --- v3: New patch (ajd) --- arch/powerpc/kernel/secvar-sysfs.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/arch/powerpc/kernel/secvar-sysfs.c b/arch/powerpc/kernel/secvar-sysfs.c index d9352d4be87b..68fb0b857442 100644 --- a/arch/powerpc/kernel/secvar-sysfs.c +++ b/arch/powerpc/kernel/secvar-sysfs.c @@ -217,6 +217,7 @@ static int secvar_sysfs_load_static(void) static int secvar_sysfs_init(void) { + u64 max_size; int rc; if (!secvar_ops) { @@ -266,6 +267,14 @@ static int secvar_sysfs_init(void) goto err; } + // Due to sysfs limitations, we will only ever get a write buffer of + // up to 1 page in size. Print a warning if this is potentially going + // to cause problems, so that the user is aware. + secvar_ops->max_size(&max_size); + if (max_size > PAGE_SIZE) + pr_warn_ratelimited("PAGE_SIZE (%lu) is smaller than maximum object size (%llu), writes are limited to PAGE_SIZE\n", + PAGE_SIZE, max_size); + return 0; err: kobject_put(secvar_kobj);