drivers/s390/net/smsgiucv_app.c

   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. */
  42 static char *sender;
  43 module_param(sender, charp, 0400);
  44 MODULE_PARM_DESC(sender, "z/VM user ID from which CP SMSGs are accepted");
  45
  46 /* SMSG device representation */
  47 static struct device *smsg_app_dev;
  48
  49 /* list element for queuing received messages for delivery */
  50 struct smsg_app_event {
  51         struct list_head list;
  52         char *buf;
  53         char *envp[4];
  54 };
  55
  56 /* queue for outgoing uevents */
  57 static LIST_HEAD(smsg_event_queue);
  58 static DEFINE_SPINLOCK(smsg_event_queue_lock);
  59
  60 static void smsg_app_event_free(struct smsg_app_event *ev)
  61 {
  62         kfree(ev->buf);
  63         kfree(ev);
  64 }
  65
  66 static 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
  96 static 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 }
 118 static DECLARE_WORK(smsg_event_work, smsg_event_work_fn);
 119
 120 static 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
 150 static 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_put_driver;
 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_put_driver;
 181         }
 182
 183         /* register with the smsgiucv device driver */
 184         rc = smsg_register_callback(SMSG_PREFIX, smsg_app_callback);
 185         if (rc) {
 186                 device_unregister(smsg_app_dev);
 187                 goto fail_put_driver;
 188         }
 189
 190         rc = 0;
 191 fail_put_driver:
 192         put_driver(smsgiucv_drv);
 193         return rc;
 194 }
 195 module_init(smsgiucv_app_init);
 196
 197 static void __exit smsgiucv_app_exit(void)
 198 {
 199         /* unregister callback */
 200         smsg_unregister_callback(SMSG_PREFIX, smsg_app_callback);
 201
 202         /* cancel pending work and flush any queued event work */
 203         cancel_work_sync(&smsg_event_work);
 204         smsg_event_work_fn(&smsg_event_work);
 205
 206         device_unregister(smsg_app_dev);
 207 }
 208 module_exit(smsgiucv_app_exit);
 209
 210 MODULE_LICENSE("GPL v2");
 211 MODULE_DESCRIPTION("Deliver z/VM CP SMSG as uevents");
 212 MODULE_AUTHOR("Hendrik Brueckner <brueckner@linux.vnet.ibm.com>");