s390/ap/zcrypt: Rework AP message buffer allocation

Slight rework on the way how AP message buffers are allocated.
Instead of having multiple places with kmalloc() calls all
the AP message buffers are now allocated and freed on exactly
one place: ap_init_apmsg() allocates the current AP bus max
limit of ap_max_msg_size (defaults to 12KB). The AP message
buffer is then freed in ap_release_apmsg().

Signed-off-by: Harald Freudenberger <freude@linux.ibm.com>
Reviewed-by: Holger Dengler <dengler@linux.ibm.com>
Link: https://lore.kernel.org/r/20250424133619.16495-3-freude@linux.ibm.com
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

Author: hfreude

drivers/s390/crypto/ap_bus.c

@@ -547,6 +547,32 @@ static void ap_poll_thread_stop(void)
 #define is_card_dev(x) ((x)->parent == ap_root_device)
 #define is_queue_dev(x) ((x)->parent != ap_root_device)
 
+/*
+ * ap_init_apmsg() - Initialize ap_message.
+ */
+int ap_init_apmsg(struct ap_message *ap_msg)
+{
+	unsigned int maxmsgsize = atomic_read(&ap_max_msg_size);
+
+	memset(ap_msg, 0, sizeof(*ap_msg));
+	ap_msg->msg = kmalloc(maxmsgsize, GFP_KERNEL);
+	if (!ap_msg->msg)
+		return -ENOMEM;
+	ap_msg->bufsize = maxmsgsize;
+
+	return 0;
+}
+EXPORT_SYMBOL(ap_init_apmsg);
+
+/*
+ * ap_release_apmsg() - Release ap_message.
+ */
+void ap_release_apmsg(struct ap_message *ap_msg)
+{
+	kfree_sensitive(ap_msg->msg);
+}
+EXPORT_SYMBOL(ap_release_apmsg);
+
 /**
  * ap_bus_match()
  * @dev: Pointer to device

drivers/s390/crypto/ap_bus.h

@@ -237,25 +237,8 @@ struct ap_message {
 #define AP_MSG_FLAG_USAGE    0x0002	/* CCA, EP11: usage (no admin) msg */
 #define AP_MSG_FLAG_ADMIN    0x0004	/* CCA, EP11: admin (=control) msg */
 
-/**
- * ap_init_message() - Initialize ap_message.
- * Initialize a message before using. Otherwise this might result in
- * unexpected behaviour.
- */
-static inline void ap_init_message(struct ap_message *ap_msg)
-{
-	memset(ap_msg, 0, sizeof(*ap_msg));
-}
-
-/**
- * ap_release_message() - Release ap_message.
- * Releases all memory used internal within the ap_message struct
- * Currently this is the message and private field.
- */
-static inline void ap_release_message(struct ap_message *ap_msg)
-{
-	kfree_sensitive(ap_msg->msg);
-}
+int ap_init_apmsg(struct ap_message *ap_msg);
+void ap_release_apmsg(struct ap_message *ap_msg);
 
 enum ap_sm_wait ap_sm_event(struct ap_queue *aq, enum ap_sm_event event);
 enum ap_sm_wait ap_sm_event_loop(struct ap_queue *aq, enum ap_sm_event event);

drivers/s390/crypto/zcrypt_api.c

@@ -642,16 +642,17 @@ static long zcrypt_rsa_modexpo(struct ap_perms *perms,
 	struct zcrypt_queue *zq, *pref_zq;
 	struct ap_message ap_msg;
 	unsigned int wgt = 0, pref_wgt = 0;
-	unsigned int func_code;
-	int cpen, qpen, qid = 0, rc = -ENODEV;
+	unsigned int func_code = 0;
+	int cpen, qpen, qid = 0, rc;
 	struct module *mod;
 
 	trace_s390_zcrypt_req(mex, TP_ICARSAMODEXPO);
 
-	ap_init_message(&ap_msg);
+	rc = ap_init_apmsg(&ap_msg);
+	if (rc)
+		goto out;
 
 	if (mex->outputdatalength < mex->inputdatalength) {
-		func_code = 0;
 		rc = -EINVAL;
 		goto out;
 	}
@@ -728,7 +729,7 @@ static long zcrypt_rsa_modexpo(struct ap_perms *perms,
 	spin_unlock(&zcrypt_list_lock);
 
 out:
-	ap_release_message(&ap_msg);
+	ap_release_apmsg(&ap_msg);
 	if (tr) {
 		tr->last_rc = rc;
 		tr->last_qid = qid;
@@ -746,16 +747,17 @@ static long zcrypt_rsa_crt(struct ap_perms *perms,
 	struct zcrypt_queue *zq, *pref_zq;
 	struct ap_message ap_msg;
 	unsigned int wgt = 0, pref_wgt = 0;
-	unsigned int func_code;
-	int cpen, qpen, qid = 0, rc = -ENODEV;
+	unsigned int func_code = 0;
+	int cpen, qpen, qid = 0, rc;
 	struct module *mod;
 
 	trace_s390_zcrypt_req(crt, TP_ICARSACRT);
 
-	ap_init_message(&ap_msg);
+	rc = ap_init_apmsg(&ap_msg);
+	if (rc)
+		goto out;
 
 	if (crt->outputdatalength < crt->inputdatalength) {
-		func_code = 0;
 		rc = -EINVAL;
 		goto out;
 	}
@@ -832,7 +834,7 @@ static long zcrypt_rsa_crt(struct ap_perms *perms,
 	spin_unlock(&zcrypt_list_lock);
 
 out:
-	ap_release_message(&ap_msg);
+	ap_release_apmsg(&ap_msg);
 	if (tr) {
 		tr->last_rc = rc;
 		tr->last_qid = qid;
@@ -850,15 +852,18 @@ static long _zcrypt_send_cprb(bool userspace, struct ap_perms *perms,
 	struct zcrypt_queue *zq, *pref_zq;
 	struct ap_message ap_msg;
 	unsigned int wgt = 0, pref_wgt = 0;
-	unsigned int func_code;
+	unsigned int func_code = 0;
 	unsigned short *domain, tdom;
-	int cpen, qpen, qid = 0, rc = -ENODEV;
+	int cpen, qpen, qid = 0, rc;
 	struct module *mod;
 
 	trace_s390_zcrypt_req(xcrb, TB_ZSECSENDCPRB);
 
 	xcrb->status = 0;
-	ap_init_message(&ap_msg);
+
+	rc = ap_init_apmsg(&ap_msg);
+	if (rc)
+		goto out;
 
 	rc = prep_cca_ap_msg(userspace, xcrb, &ap_msg, &func_code, &domain);
 	if (rc)
@@ -962,7 +967,7 @@ static long _zcrypt_send_cprb(bool userspace, struct ap_perms *perms,
 	spin_unlock(&zcrypt_list_lock);
 
 out:
-	ap_release_message(&ap_msg);
+	ap_release_apmsg(&ap_msg);
 	if (tr) {
 		tr->last_rc = rc;
 		tr->last_qid = qid;
@@ -1033,14 +1038,16 @@ static long _zcrypt_send_ep11_cprb(bool userspace, struct ap_perms *perms,
 	struct ep11_target_dev *targets;
 	unsigned short target_num;
 	unsigned int wgt = 0, pref_wgt = 0;
-	unsigned int func_code, domain;
+	unsigned int func_code = 0, domain;
 	struct ap_message ap_msg;
-	int cpen, qpen, qid = 0, rc = -ENODEV;
+	int cpen, qpen, qid = 0, rc;
 	struct module *mod;
 
 	trace_s390_zcrypt_req(xcrb, TP_ZSENDEP11CPRB);
 
-	ap_init_message(&ap_msg);
+	rc = ap_init_apmsg(&ap_msg);
+	if (rc)
+		goto out;
 
 	target_num = (unsigned short)xcrb->targets_num;
 
@@ -1164,7 +1171,7 @@ static long _zcrypt_send_ep11_cprb(bool userspace, struct ap_perms *perms,
 out_free:
 	kfree(targets);
 out:
-	ap_release_message(&ap_msg);
+	ap_release_apmsg(&ap_msg);
 	if (tr) {
 		tr->last_rc = rc;
 		tr->last_qid = qid;
@@ -1204,15 +1211,17 @@ static long zcrypt_rng(char *buffer)
 	struct zcrypt_card *zc, *pref_zc;
 	struct zcrypt_queue *zq, *pref_zq;
 	unsigned int wgt = 0, pref_wgt = 0;
-	unsigned int func_code;
+	unsigned int func_code = 0;
 	struct ap_message ap_msg;
 	unsigned int domain;
 	int qid = 0, rc = -ENODEV;
 	struct module *mod;
 
 	trace_s390_zcrypt_req(buffer, TP_HWRNGCPRB);
 
-	ap_init_message(&ap_msg);
+	rc = ap_init_apmsg(&ap_msg);
+	if (rc)
+		goto out;
 	rc = prep_rng_ap_msg(&ap_msg, &func_code, &domain);
 	if (rc)
 		goto out;
@@ -1258,7 +1267,7 @@ static long zcrypt_rng(char *buffer)
 	spin_unlock(&zcrypt_list_lock);
 
 out:
-	ap_release_message(&ap_msg);
+	ap_release_apmsg(&ap_msg);
 	trace_s390_zcrypt_rep(buffer, func_code, rc,
 			      AP_QID_CARD(qid), AP_QID_QUEUE(qid));
 	return rc;

drivers/s390/crypto/zcrypt_msgtype50.c

@@ -449,17 +449,19 @@ static atomic_t zcrypt_step = ATOMIC_INIT(0);
  * @zq: pointer to zcrypt_queue structure that identifies the
  *	CEXxA device to the request distributor
  * @mex: pointer to the modexpo request buffer
+ * This function assumes that ap_msg has been initialized with
+ * ap_init_apmsg() and thus a valid buffer with the size of
+ * ap_msg->bufsize is available within ap_msg. Also the caller has
+ * to make sure ap_release_apmsg() is always called even on failure.
  */
 static long zcrypt_msgtype50_modexpo(struct zcrypt_queue *zq,
 				     struct ica_rsa_modexpo *mex,
 				     struct ap_message *ap_msg)
 {
 	int rc;
 
-	ap_msg->bufsize = MSGTYPE50_CRB3_MAX_MSG_SIZE;
-	ap_msg->msg = kmalloc(ap_msg->bufsize, GFP_KERNEL);
-	if (!ap_msg->msg)
-		return -ENOMEM;
+	if (ap_msg->bufsize < MSGTYPE50_CRB3_MAX_MSG_SIZE)
+		return -EMSGSIZE;
 	ap_msg->receive = zcrypt_msgtype50_receive;
 	ap_msg->psmid = (((unsigned long)current->pid) << 32) +
 		atomic_inc_return(&zcrypt_step);
@@ -496,17 +498,19 @@ static long zcrypt_msgtype50_modexpo(struct zcrypt_queue *zq,
  * @zq: pointer to zcrypt_queue structure that identifies the
  *	CEXxA device to the request distributor
  * @crt: pointer to the modexpoc_crt request buffer
+ * This function assumes that ap_msg has been initialized with
+ * ap_init_apmsg() and thus a valid buffer with the size of
+ * ap_msg->bufsize is available within ap_msg. Also the caller has
+ * to make sure ap_release_apmsg() is always called even on failure.
  */
 static long zcrypt_msgtype50_modexpo_crt(struct zcrypt_queue *zq,
 					 struct ica_rsa_modexpo_crt *crt,
 					 struct ap_message *ap_msg)
 {
 	int rc;
 
-	ap_msg->bufsize = MSGTYPE50_CRB3_MAX_MSG_SIZE;
-	ap_msg->msg = kmalloc(ap_msg->bufsize, GFP_KERNEL);
-	if (!ap_msg->msg)
-		return -ENOMEM;
+	if (ap_msg->bufsize < MSGTYPE50_CRB3_MAX_MSG_SIZE)
+		return -EMSGSIZE;
 	ap_msg->receive = zcrypt_msgtype50_receive;
 	ap_msg->psmid = (((unsigned long)current->pid) << 32) +
 		atomic_inc_return(&zcrypt_step);

drivers/s390/crypto/zcrypt_msgtype6.c

@@ -1050,20 +1050,17 @@ static long zcrypt_msgtype6_modexpo_crt(struct zcrypt_queue *zq,
  * Prepare a CCA AP msg: fetch the required data from userspace,
  * prepare the AP msg, fill some info into the ap_message struct,
  * extract some data from the CPRB and give back to the caller.
- * This function allocates memory and needs an ap_msg prepared
- * by the caller with ap_init_message(). Also the caller has to
- * make sure ap_release_message() is always called even on failure.
+ * This function assumes that ap_msg has been initialized with
+ * ap_init_apmsg() and thus a valid buffer with the size of
+ * ap_msg->bufsize is available within ap_msg. Also the caller has
+ * to make sure ap_release_apmsg() is always called even on failure.
  */
 int prep_cca_ap_msg(bool userspace, struct ica_xcRB *xcrb,
 		    struct ap_message *ap_msg,
 		    unsigned int *func_code, unsigned short **dom)
 {
 	struct ap_response_type *resp_type = &ap_msg->response;
 
-	ap_msg->bufsize = atomic_read(&ap_max_msg_size);
-	ap_msg->msg = kmalloc(ap_msg->bufsize, GFP_KERNEL);
-	if (!ap_msg->msg)
-		return -ENOMEM;
 	ap_msg->receive = zcrypt_msgtype6_receive;
 	ap_msg->psmid = (((unsigned long)current->pid) << 32) +
 				atomic_inc_return(&zcrypt_step);
@@ -1143,20 +1140,17 @@ static long zcrypt_msgtype6_send_cprb(bool userspace, struct zcrypt_queue *zq,
  * Prepare an EP11 AP msg: fetch the required data from userspace,
  * prepare the AP msg, fill some info into the ap_message struct,
  * extract some data from the CPRB and give back to the caller.
- * This function allocates memory and needs an ap_msg prepared
- * by the caller with ap_init_message(). Also the caller has to
- * make sure ap_release_message() is always called even on failure.
+ * This function assumes that ap_msg has been initialized with
+ * ap_init_apmsg() and thus a valid buffer with the size of
+ * ap_msg->bufsize is available within ap_msg. Also the caller has
+ * to make sure ap_release_apmsg() is always called even on failure.
  */
 int prep_ep11_ap_msg(bool userspace, struct ep11_urb *xcrb,
 		     struct ap_message *ap_msg,
 		     unsigned int *func_code, unsigned int *domain)
 {
 	struct ap_response_type *resp_type = &ap_msg->response;
 
-	ap_msg->bufsize = atomic_read(&ap_max_msg_size);
-	ap_msg->msg = kmalloc(ap_msg->bufsize, GFP_KERNEL);
-	if (!ap_msg->msg)
-		return -ENOMEM;
 	ap_msg->receive = zcrypt_msgtype6_receive_ep11;
 	ap_msg->psmid = (((unsigned long)current->pid) << 32) +
 				atomic_inc_return(&zcrypt_step);
@@ -1257,15 +1251,20 @@ static long zcrypt_msgtype6_send_ep11_cprb(bool userspace, struct zcrypt_queue *
 	return rc;
 }
 
+/*
+ * Prepare a CEXXC get random request ap message.
+ * This function assumes that ap_msg has been initialized with
+ * ap_init_apmsg() and thus a valid buffer with the size of
+ * ap_max_msg_size is available within ap_msg. Also the caller has
+ * to make sure ap_release_apmsg() is always called even on failure.
+ */
 int prep_rng_ap_msg(struct ap_message *ap_msg, int *func_code,
 		    unsigned int *domain)
 {
 	struct ap_response_type *resp_type = &ap_msg->response;
 
-	ap_msg->bufsize = AP_DEFAULT_MAX_MSG_SIZE;
-	ap_msg->msg = kmalloc(ap_msg->bufsize, GFP_KERNEL);
-	if (!ap_msg->msg)
-		return -ENOMEM;
+	if (ap_msg->bufsize < AP_DEFAULT_MAX_MSG_SIZE)
+		return -EMSGSIZE;
 	ap_msg->receive = zcrypt_msgtype6_receive;
 	ap_msg->psmid = (((unsigned long)current->pid) << 32) +
 				atomic_inc_return(&zcrypt_step);