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// SPDX-License-Identifier: GPL-2.0
/*
* Deliver z/VM CP special messages (SMSG) as uevents.
*
* The driver registers for z/VM CP special messages with the
* "APP" prefix. Incoming messages are delivered to user space
* as uevents.
*
* Copyright IBM Corp. 2010
* Author(s): Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
*
*/
#define KMSG_COMPONENT "smsgiucv_app"
#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
#include <linux/ctype.h>
#include <linux/err.h>
#include <linux/device.h>
#include <linux/list.h>
#include <linux/kobject.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/workqueue.h>
#include <net/iucv/iucv.h>
#include "smsgiucv.h"
/* prefix used for SMSG registration */
#define SMSG_PREFIX "APP"
/* SMSG related uevent environment variables */
#define ENV_SENDER_STR "SMSG_SENDER="
#define ENV_SENDER_LEN (strlen(ENV_SENDER_STR) + 8 + 1)
#define ENV_PREFIX_STR "SMSG_ID="
#define ENV_PREFIX_LEN (strlen(ENV_PREFIX_STR) + \
strlen(SMSG_PREFIX) + 1)
#define ENV_TEXT_STR "SMSG_TEXT="
#define ENV_TEXT_LEN(msg) (strlen(ENV_TEXT_STR) + strlen((msg)) + 1)
/* z/VM user ID which is permitted to send SMSGs
* If the value is undefined or empty (""), special messages are
* accepted from any z/VM user ID. */
static char *sender;
module_param(sender, charp, 0400);
MODULE_PARM_DESC(sender, "z/VM user ID from which CP SMSGs are accepted");
/* SMSG device representation */
static struct device *smsg_app_dev;
/* list element for queuing received messages for delivery */
struct smsg_app_event {
struct list_head list;
char *buf;
char *envp[4];
};
/* queue for outgoing uevents */
static LIST_HEAD(smsg_event_queue);
static DEFINE_SPINLOCK(smsg_event_queue_lock);
static void smsg_app_event_free(struct smsg_app_event *ev)
{
kfree(ev->buf);
kfree(ev);
}
static struct smsg_app_event *smsg_app_event_alloc(const char *from,
const char *msg)
{
struct smsg_app_event *ev;
ev = kzalloc(sizeof(*ev), GFP_ATOMIC);
if (!ev)
return NULL;
ev->buf = kzalloc(ENV_SENDER_LEN + ENV_PREFIX_LEN +
ENV_TEXT_LEN(msg), GFP_ATOMIC);
if (!ev->buf) {
kfree(ev);
return NULL;
}
/* setting up environment pointers into buf */
ev->envp[0] = ev->buf;
ev->envp[1] = ev->envp[0] + ENV_SENDER_LEN;
ev->envp[2] = ev->envp[1] + ENV_PREFIX_LEN;
ev->envp[3] = NULL;
/* setting up environment: sender, prefix name, and message text */
snprintf(ev->envp[0], ENV_SENDER_LEN, ENV_SENDER_STR "%s", from);
snprintf(ev->envp[1], ENV_PREFIX_LEN, ENV_PREFIX_STR "%s", SMSG_PREFIX);
snprintf(ev->envp[2], ENV_TEXT_LEN(msg), ENV_TEXT_STR "%s", msg);
return ev;
}
static void smsg_event_work_fn(struct work_struct *work)
{
LIST_HEAD(event_queue);
struct smsg_app_event *p, *n;
struct device *dev;
dev = get_device(smsg_app_dev);
if (!dev)
return;
spin_lock_bh(&smsg_event_queue_lock);
list_splice_init(&smsg_event_queue, &event_queue);
spin_unlock_bh(&smsg_event_queue_lock);
list_for_each_entry_safe(p, n, &event_queue, list) {
list_del(&p->list);
kobject_uevent_env(&dev->kobj, KOBJ_CHANGE, p->envp);
smsg_app_event_free(p);
}
put_device(dev);
}
static DECLARE_WORK(smsg_event_work, smsg_event_work_fn);
static void smsg_app_callback(const char *from, char *msg)
{
struct smsg_app_event *se;
/* check if the originating z/VM user ID matches
* the configured sender. */
if (sender && strlen(sender) > 0 && strcmp(from, sender) != 0)
return;
/* get start of message text (skip prefix and leading blanks) */
msg += strlen(SMSG_PREFIX);
while (*msg && isspace(*msg))
msg++;
if (*msg == '\0')
return;
/* allocate event list element and its environment */
se = smsg_app_event_alloc(from, msg);
if (!se)
return;
/* queue event and schedule work function */
spin_lock(&smsg_event_queue_lock);
list_add_tail(&se->list, &smsg_event_queue);
spin_unlock(&smsg_event_queue_lock);
schedule_work(&smsg_event_work);
return;
}
static int __init smsgiucv_app_init(void)
{
struct device_driver *smsgiucv_drv;
int rc;
if (!MACHINE_IS_VM)
return -ENODEV;
smsg_app_dev = kzalloc(sizeof(*smsg_app_dev), GFP_KERNEL);
if (!smsg_app_dev)
return -ENOMEM;
smsgiucv_drv = driver_find(SMSGIUCV_DRV_NAME, &iucv_bus);
if (!smsgiucv_drv) {
kfree(smsg_app_dev);
return -ENODEV;
}
rc = dev_set_name(smsg_app_dev, KMSG_COMPONENT);
if (rc) {
kfree(smsg_app_dev);
goto fail;
}
smsg_app_dev->bus = &iucv_bus;
smsg_app_dev->parent = iucv_root;
smsg_app_dev->release = (void (*)(struct device *)) kfree;
smsg_app_dev->driver = smsgiucv_drv;
rc = device_register(smsg_app_dev);
if (rc) {
put_device(smsg_app_dev);
goto fail;
}
/* convert sender to uppercase characters */
if (sender) {
int len = strlen(sender);
while (len--)
sender[len] = toupper(sender[len]);
}
/* register with the smsgiucv device driver */
rc = smsg_register_callback(SMSG_PREFIX, smsg_app_callback);
if (rc) {
device_unregister(smsg_app_dev);
goto fail;
}
rc = 0;
fail:
return rc;
}
module_init(smsgiucv_app_init);
static void __exit smsgiucv_app_exit(void)
{
/* unregister callback */
smsg_unregister_callback(SMSG_PREFIX, smsg_app_callback);
/* cancel pending work and flush any queued event work */
cancel_work_sync(&smsg_event_work);
smsg_event_work_fn(&smsg_event_work);
device_unregister(smsg_app_dev);
}
module_exit(smsgiucv_app_exit);
MODULE_LICENSE("GPL v2");
MODULE_DESCRIPTION("Deliver z/VM CP SMSG as uevents");
MODULE_AUTHOR("Hendrik Brueckner <brueckner@linux.vnet.ibm.com>");
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