LXR linux/drivers/s390/net/smsgiucv

   1/*
   2 * Deliver z/VM CP special messages (SMSG) as uevents.
   3 *
   4 * The driver registers for z/VM CP special messages with the
   5 * "APP" prefix. Incoming messages are delivered to user space
   6 * as uevents.
   7 *
   8 * Copyright IBM Corp. 2010
   9 * Author(s): Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
  10 *
  11 */
  12#define KMSG_COMPONENT          "smsgiucv_app"
  13#define pr_fmt(fmt)             KMSG_COMPONENT ": " fmt
  14
  15#include <linux/ctype.h>
  16#include <linux/err.h>
  17#include <linux/device.h>
  18#include <linux/list.h>
  19#include <linux/kobject.h>
  20#include <linux/module.h>
  21#include <linux/slab.h>
  22#include <linux/spinlock.h>
  23#include <linux/workqueue.h>
  24#include <net/iucv/iucv.h>
  25#include "smsgiucv.h"
  26
  27/* prefix used for SMSG registration */
  28#define SMSG_PREFIX             "APP"
  29
  30/* SMSG related uevent environment variables */
  31#define ENV_SENDER_STR          "SMSG_SENDER="
  32#define ENV_SENDER_LEN          (strlen(ENV_SENDER_STR) + 8 + 1)
  33#define ENV_PREFIX_STR          "SMSG_ID="
  34#define ENV_PREFIX_LEN          (strlen(ENV_PREFIX_STR) + \
  35                                 strlen(SMSG_PREFIX) + 1)
  36#define ENV_TEXT_STR            "SMSG_TEXT="
  37#define ENV_TEXT_LEN(msg)       (strlen(ENV_TEXT_STR) + strlen((msg)) + 1)
  38
  39/* z/VM user ID which is permitted to send SMSGs
  40 * If the value is undefined or empty (""), special messages are
  41 * accepted from any z/VM user ID. */
  42static char *sender;
  43module_param(sender, charp, 0400);
  44MODULE_PARM_DESC(sender, "z/VM user ID from which CP SMSGs are accepted");
  45
  46/* SMSG device representation */
  47static struct device *smsg_app_dev;
  48
  49/* list element for queuing received messages for delivery */
  50struct smsg_app_event {
  51        struct list_head list;
  52        char *buf;
  53        char *envp[4];
  54};
  55
  56/* queue for outgoing uevents */
  57static LIST_HEAD(smsg_event_queue);
  58static DEFINE_SPINLOCK(smsg_event_queue_lock);
  59
  60static void smsg_app_event_free(struct smsg_app_event *ev)
  61{
  62        kfree(ev->buf);
  63        kfree(ev);
  64}
  65
  66static struct smsg_app_event *smsg_app_event_alloc(const char *from,
  67                                                   const char *msg)
  68{
  69        struct smsg_app_event *ev;
  70
  71        ev = kzalloc(sizeof(*ev), GFP_ATOMIC);
  72        if (!ev)
  73                return NULL;
  74
  75        ev->buf = kzalloc(ENV_SENDER_LEN + ENV_PREFIX_LEN +
  76                          ENV_TEXT_LEN(msg), GFP_ATOMIC);
  77        if (!ev->buf) {
  78                kfree(ev);
  79                return NULL;
  80        }
  81
  82        /* setting up environment pointers into buf */
  83        ev->envp[0] = ev->buf;
  84        ev->envp[1] = ev->envp[0] + ENV_SENDER_LEN;
  85        ev->envp[2] = ev->envp[1] + ENV_PREFIX_LEN;
  86        ev->envp[3] = NULL;
  87
  88        /* setting up environment: sender, prefix name, and message text */
  89        snprintf(ev->envp[0], ENV_SENDER_LEN, ENV_SENDER_STR "%s", from);
  90        snprintf(ev->envp[1], ENV_PREFIX_LEN, ENV_PREFIX_STR "%s", SMSG_PREFIX);
  91        snprintf(ev->envp[2], ENV_TEXT_LEN(msg), ENV_TEXT_STR "%s", msg);
  92
  93        return ev;
  94}
  95
  96static void smsg_event_work_fn(struct work_struct *work)
  97{
  98        LIST_HEAD(event_queue);
  99        struct smsg_app_event *p, *n;
 100        struct device *dev;
 101
 102        dev = get_device(smsg_app_dev);
 103        if (!dev)
 104                return;
 105
 106        spin_lock_bh(&smsg_event_queue_lock);
 107        list_splice_init(&smsg_event_queue, &event_queue);
 108        spin_unlock_bh(&smsg_event_queue_lock);
 109
 110        list_for_each_entry_safe(p, n, &event_queue, list) {
 111                list_del(&p->list);
 112                kobject_uevent_env(&dev->kobj, KOBJ_CHANGE, p->envp);
 113                smsg_app_event_free(p);
 114        }
 115
 116        put_device(dev);
 117}
 118static DECLARE_WORK(smsg_event_work, smsg_event_work_fn);
 119
 120static void smsg_app_callback(const char *from, char *msg)
 121{
 122        struct smsg_app_event *se;
 123
 124        /* check if the originating z/VM user ID matches
 125         * the configured sender. */
 126        if (sender && strlen(sender) > 0 && strcmp(from, sender) != 0)
 127                return;
 128
 129        /* get start of message text (skip prefix and leading blanks) */
 130        msg += strlen(SMSG_PREFIX);
 131        while (*msg && isspace(*msg))
 132                msg++;
 133        if (*msg == '\0')
 134                return;
 135
 136        /* allocate event list element and its environment */
 137        se = smsg_app_event_alloc(from, msg);
 138        if (!se)
 139                return;
 140
 141        /* queue event and schedule work function */
 142        spin_lock(&smsg_event_queue_lock);
 143        list_add_tail(&se->list, &smsg_event_queue);
 144        spin_unlock(&smsg_event_queue_lock);
 145
 146        schedule_work(&smsg_event_work);
 147        return;
 148}
 149
 150static int __init smsgiucv_app_init(void)
 151{
 152        struct device_driver *smsgiucv_drv;
 153        int rc;
 154
 155        if (!MACHINE_IS_VM)
 156                return -ENODEV;
 157
 158        smsg_app_dev = kzalloc(sizeof(*smsg_app_dev), GFP_KERNEL);
 159        if (!smsg_app_dev)
 160                return -ENOMEM;
 161
 162        smsgiucv_drv = driver_find(SMSGIUCV_DRV_NAME, &iucv_bus);
 163        if (!smsgiucv_drv) {
 164                kfree(smsg_app_dev);
 165                return -ENODEV;
 166        }
 167
 168        rc = dev_set_name(smsg_app_dev, KMSG_COMPONENT);
 169        if (rc) {
 170                kfree(smsg_app_dev);
 171                goto fail;
 172        }
 173        smsg_app_dev->bus = &iucv_bus;
 174        smsg_app_dev->parent = iucv_root;
 175        smsg_app_dev->release = (void (*)(struct device *)) kfree;
 176        smsg_app_dev->driver = smsgiucv_drv;
 177        rc = device_register(smsg_app_dev);
 178        if (rc) {
 179                put_device(smsg_app_dev);
 180                goto fail;
 181        }
 182
 183        /* convert sender to uppercase characters */
 184        if (sender) {
 185                int len = strlen(sender);
 186                while (len--)
 187                        sender[len] = toupper(sender[len]);
 188        }
 189
 190        /* register with the smsgiucv device driver */
 191        rc = smsg_register_callback(SMSG_PREFIX, smsg_app_callback);
 192        if (rc) {
 193                device_unregister(smsg_app_dev);
 194                goto fail;
 195        }
 196
 197        rc = 0;
 198fail:
 199        return rc;
 200}
 201module_init(smsgiucv_app_init);
 202
 203static void __exit smsgiucv_app_exit(void)
 204{
 205        /* unregister callback */
 206        smsg_unregister_callback(SMSG_PREFIX, smsg_app_callback);
 207
 208        /* cancel pending work and flush any queued event work */
 209        cancel_work_sync(&smsg_event_work);
 210        smsg_event_work_fn(&smsg_event_work);
 211
 212        device_unregister(smsg_app_dev);
 213}
 214module_exit(smsgiucv_app_exit);
 215
 216MODULE_LICENSE("GPL v2");
 217MODULE_DESCRIPTION("Deliver z/VM CP SMSG as uevents");
 218MODULE_AUTHOR("Hendrik Brueckner <brueckner@linux.vnet.ibm.com>");
 219