1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Deliver z/VM CP special messages (SMSG) as uevents.
4 *
5 * The driver registers for z/VM CP special messages with the
6 * "APP" prefix. Incoming messages are delivered to user space
7 * as uevents.
8 *
9 * Copyright IBM Corp. 2010
10 * Author(s): Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
11 *
12 */
13 #define KMSG_COMPONENT "smsgiucv_app"
14 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
15
16 #include <linux/ctype.h>
17 #include <linux/err.h>
18 #include <linux/device.h>
19 #include <linux/list.h>
20 #include <linux/kobject.h>
21 #include <linux/module.h>
22 #include <linux/slab.h>
23 #include <linux/spinlock.h>
24 #include <linux/workqueue.h>
25 #include <net/iucv/iucv.h>
26 #include "smsgiucv.h"
27
28 /* prefix used for SMSG registration */
29 #define SMSG_PREFIX "APP"
30
31 /* SMSG related uevent environment variables */
32 #define ENV_SENDER_STR "SMSG_SENDER="
33 #define ENV_SENDER_LEN (strlen(ENV_SENDER_STR) + 8 + 1)
34 #define ENV_PREFIX_STR "SMSG_ID="
35 #define ENV_PREFIX_LEN (strlen(ENV_PREFIX_STR) + \
36 strlen(SMSG_PREFIX) + 1)
37 #define ENV_TEXT_STR "SMSG_TEXT="
38 #define ENV_TEXT_LEN(msg) (strlen(ENV_TEXT_STR) + strlen((msg)) + 1)
39
40 /* z/VM user ID which is permitted to send SMSGs
41 * If the value is undefined or empty (""), special messages are
42 * accepted from any z/VM user ID. */
43 static char *sender;
44 module_param(sender, charp, 0400);
45 MODULE_PARM_DESC(sender, "z/VM user ID from which CP SMSGs are accepted");
46
47 /* SMSG device representation */
48 static struct device *smsg_app_dev;
49
50 /* list element for queuing received messages for delivery */
51 struct smsg_app_event {
52 struct list_head list;
53 char *buf;
54 char *envp[4];
55 };
56
57 /* queue for outgoing uevents */
58 static LIST_HEAD(smsg_event_queue);
59 static DEFINE_SPINLOCK(smsg_event_queue_lock);
60
smsg_app_event_free(struct smsg_app_event * ev)61 static void smsg_app_event_free(struct smsg_app_event *ev)
62 {
63 kfree(ev->buf);
64 kfree(ev);
65 }
66
smsg_app_event_alloc(const char * from,const char * msg)67 static struct smsg_app_event *smsg_app_event_alloc(const char *from,
68 const char *msg)
69 {
70 struct smsg_app_event *ev;
71
72 ev = kzalloc(sizeof(*ev), GFP_ATOMIC);
73 if (!ev)
74 return NULL;
75
76 ev->buf = kzalloc(ENV_SENDER_LEN + ENV_PREFIX_LEN +
77 ENV_TEXT_LEN(msg), GFP_ATOMIC);
78 if (!ev->buf) {
79 kfree(ev);
80 return NULL;
81 }
82
83 /* setting up environment pointers into buf */
84 ev->envp[0] = ev->buf;
85 ev->envp[1] = ev->envp[0] + ENV_SENDER_LEN;
86 ev->envp[2] = ev->envp[1] + ENV_PREFIX_LEN;
87 ev->envp[3] = NULL;
88
89 /* setting up environment: sender, prefix name, and message text */
90 snprintf(ev->envp[0], ENV_SENDER_LEN, ENV_SENDER_STR "%s", from);
91 snprintf(ev->envp[1], ENV_PREFIX_LEN, ENV_PREFIX_STR "%s", SMSG_PREFIX);
92 snprintf(ev->envp[2], ENV_TEXT_LEN(msg), ENV_TEXT_STR "%s", msg);
93
94 return ev;
95 }
96
smsg_event_work_fn(struct work_struct * work)97 static void smsg_event_work_fn(struct work_struct *work)
98 {
99 LIST_HEAD(event_queue);
100 struct smsg_app_event *p, *n;
101 struct device *dev;
102
103 dev = get_device(smsg_app_dev);
104 if (!dev)
105 return;
106
107 spin_lock_bh(&smsg_event_queue_lock);
108 list_splice_init(&smsg_event_queue, &event_queue);
109 spin_unlock_bh(&smsg_event_queue_lock);
110
111 list_for_each_entry_safe(p, n, &event_queue, list) {
112 list_del(&p->list);
113 kobject_uevent_env(&dev->kobj, KOBJ_CHANGE, p->envp);
114 smsg_app_event_free(p);
115 }
116
117 put_device(dev);
118 }
119 static DECLARE_WORK(smsg_event_work, smsg_event_work_fn);
120
smsg_app_callback(const char * from,char * msg)121 static void smsg_app_callback(const char *from, char *msg)
122 {
123 struct smsg_app_event *se;
124
125 /* check if the originating z/VM user ID matches
126 * the configured sender. */
127 if (sender && strlen(sender) > 0 && strcmp(from, sender) != 0)
128 return;
129
130 /* get start of message text (skip prefix and leading blanks) */
131 msg += strlen(SMSG_PREFIX);
132 while (*msg && isspace(*msg))
133 msg++;
134 if (*msg == '\0')
135 return;
136
137 /* allocate event list element and its environment */
138 se = smsg_app_event_alloc(from, msg);
139 if (!se)
140 return;
141
142 /* queue event and schedule work function */
143 spin_lock(&smsg_event_queue_lock);
144 list_add_tail(&se->list, &smsg_event_queue);
145 spin_unlock(&smsg_event_queue_lock);
146
147 schedule_work(&smsg_event_work);
148 return;
149 }
150
smsgiucv_app_init(void)151 static int __init smsgiucv_app_init(void)
152 {
153 struct device_driver *smsgiucv_drv;
154 int rc;
155
156 if (!MACHINE_IS_VM)
157 return -ENODEV;
158
159 smsg_app_dev = kzalloc(sizeof(*smsg_app_dev), GFP_KERNEL);
160 if (!smsg_app_dev)
161 return -ENOMEM;
162
163 smsgiucv_drv = driver_find(SMSGIUCV_DRV_NAME, &iucv_bus);
164 if (!smsgiucv_drv) {
165 kfree(smsg_app_dev);
166 return -ENODEV;
167 }
168
169 rc = dev_set_name(smsg_app_dev, KMSG_COMPONENT);
170 if (rc) {
171 kfree(smsg_app_dev);
172 goto fail;
173 }
174 smsg_app_dev->bus = &iucv_bus;
175 smsg_app_dev->parent = iucv_root;
176 smsg_app_dev->release = (void (*)(struct device *)) kfree;
177 smsg_app_dev->driver = smsgiucv_drv;
178 rc = device_register(smsg_app_dev);
179 if (rc) {
180 put_device(smsg_app_dev);
181 goto fail;
182 }
183
184 /* convert sender to uppercase characters */
185 if (sender) {
186 int len = strlen(sender);
187 while (len--)
188 sender[len] = toupper(sender[len]);
189 }
190
191 /* register with the smsgiucv device driver */
192 rc = smsg_register_callback(SMSG_PREFIX, smsg_app_callback);
193 if (rc) {
194 device_unregister(smsg_app_dev);
195 goto fail;
196 }
197
198 rc = 0;
199 fail:
200 return rc;
201 }
202 module_init(smsgiucv_app_init);
203
smsgiucv_app_exit(void)204 static void __exit smsgiucv_app_exit(void)
205 {
206 /* unregister callback */
207 smsg_unregister_callback(SMSG_PREFIX, smsg_app_callback);
208
209 /* cancel pending work and flush any queued event work */
210 cancel_work_sync(&smsg_event_work);
211 smsg_event_work_fn(&smsg_event_work);
212
213 device_unregister(smsg_app_dev);
214 }
215 module_exit(smsgiucv_app_exit);
216
217 MODULE_LICENSE("GPL v2");
218 MODULE_DESCRIPTION("Deliver z/VM CP SMSG as uevents");
219 MODULE_AUTHOR("Hendrik Brueckner <brueckner@linux.vnet.ibm.com>");
220