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Wed, 9 Apr 2025 16:19:36 +0000 (GMT) Message-ID: Date: Wed, 9 Apr 2025 18:19:35 +0200 Precedence: bulk X-Mailing-List: linux-s390@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 04/24] s390/zcrypt: Avoid alloc and copy of ep11 targets if kernelspace cprb To: Harald Freudenberger , ifranzki@linux.ibm.com, fcallies@linux.ibm.com, hca@linux.ibm.com, gor@linux.ibm.com, agordeev@linux.ibm.com, seiden@linux.ibm.com, borntraeger@linux.ibm.com, frankja@linux.ibm.com, imbrenda@linux.ibm.com Cc: linux-s390@vger.kernel.org, herbert@gondor.apana.org.au References: <20250409140305.58900-1-freude@linux.ibm.com> <20250409140305.58900-5-freude@linux.ibm.com> Content-Language: de-DE, en-US From: Holger Dengler In-Reply-To: <20250409140305.58900-5-freude@linux.ibm.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: 7B83RVnUKXhRJCSFlkVWK-BChMMVjR-k X-Proofpoint-GUID: 7B83RVnUKXhRJCSFlkVWK-BChMMVjR-k X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1095,Hydra:6.0.680,FMLib:17.12.68.34 definitions=2025-04-09_05,2025-04-08_04,2024-11-22_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 mlxscore=0 suspectscore=0 priorityscore=1501 impostorscore=0 malwarescore=0 bulkscore=0 clxscore=1015 lowpriorityscore=0 spamscore=0 adultscore=0 phishscore=0 mlxlogscore=999 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.19.0-2502280000 definitions=main-2504090102 On 09/04/2025 16:02, Harald Freudenberger wrote: > If there is a target list of APQNs given when an CPRB is > to be send via zcrypt_send_ep11_cprb() there is always a > kmalloc() done and the targets are copied via z_copy_from_user. > > As there are callers from kernel space (zcrypt_ep11misc.c) > which signal this via the userspace parameter improve this > code to directly use the given target list in case of > kernelspace thus removing the unnecessary memory alloc > and mem copy. > > Signed-off-by: Harald Freudenberger I have a few comments below. The rest looks good to me. > --- > drivers/s390/crypto/zcrypt_api.c | 41 ++++++++++++++++---------------- > 1 file changed, 20 insertions(+), 21 deletions(-) > > diff --git a/drivers/s390/crypto/zcrypt_api.c b/drivers/s390/crypto/zcrypt_api.c > index ad09c5306e28..f96f596e578f 100644 > --- a/drivers/s390/crypto/zcrypt_api.c > +++ b/drivers/s390/crypto/zcrypt_api.c [...] > @@ -1052,29 +1052,28 @@ static long _zcrypt_send_ep11_cprb(bool userspace, struct ap_perms *perms, > target_num = (unsigned short)xcrb->targets_num; > > /* empty list indicates autoselect (all available targets) */ > - targets = NULL; > + rc = -ENOMEM; I would prefer to set rc in the kmalloc error handling. See below. > if (target_num != 0) { > struct ep11_target_dev __user *uptr; *uptr is no longer required, as the userspace case is ensured by code. > > - targets = kcalloc(target_num, sizeof(*targets), GFP_KERNEL); > - if (!targets) { > - func_code = 0; > - rc = -ENOMEM; > - goto out; > - } > - > - uptr = (struct ep11_target_dev __force __user *)xcrb->targets; > - if (z_copy_from_user(userspace, targets, uptr, > - target_num * sizeof(*targets))) { > - func_code = 0; > - rc = -EFAULT; > - goto out_free; > + if (userspace) { > + targets = kcalloc(target_num, sizeof(*targets), GFP_KERNEL); > + if (!targets) > + goto out; Please set rc here. It makes it easier to read as it correlates with the other error case for copy_from_user(). if (!targets) { rc = -ENOMEM; goto out; } > + uptr = (struct ep11_target_dev __force __user *)xcrb->targets; > + if (copy_from_user(targets, uptr, > + target_num * sizeof(*targets))) { The cast can be dropped and you can copy directly from the userspace pointer in xcrb. if (copy_from_user(targets, xcrb->targets, target_num * sizeof(*targets))) { > + rc = -EFAULT; > + goto out; > + } > + } else { > + targets = (struct ep11_target_dev __force __kernel *)xcrb->targets; > } > } > > rc = prep_ep11_ap_msg(userspace, xcrb, &ap_msg, &func_code, &domain); > if (rc) > - goto out_free; > + goto out; > print_hex_dump_debug("ep11req: ", DUMP_PREFIX_ADDRESS, 16, 1, > ap_msg.msg, ap_msg.len, false); > [...] -- Mit freundlichen Grüßen / Kind regards Holger Dengler -- IBM Systems, Linux on IBM Z Development dengler@linux.ibm.com