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 pr_fmt(fmt) "smsgiucv_app: " 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 <asm/machine.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 61 static void smsg_app_event_free(struct smsg_app_event *ev) 62 { 63 kfree(ev->buf); 64 kfree(ev); 65 } 66 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 scnprintf(ev->envp[0], ENV_SENDER_LEN, ENV_SENDER_STR "%s", from); 91 scnprintf(ev->envp[1], ENV_PREFIX_LEN, ENV_PREFIX_STR "%s", 92 SMSG_PREFIX); 93 scnprintf(ev->envp[2], ENV_TEXT_LEN(msg), ENV_TEXT_STR "%s", msg); 94 95 return ev; 96 } 97 98 static void smsg_event_work_fn(struct work_struct *work) 99 { 100 LIST_HEAD(event_queue); 101 struct smsg_app_event *p, *n; 102 struct device *dev; 103 104 dev = get_device(smsg_app_dev); 105 if (!dev) 106 return; 107 108 spin_lock_bh(&smsg_event_queue_lock); 109 list_splice_init(&smsg_event_queue, &event_queue); 110 spin_unlock_bh(&smsg_event_queue_lock); 111 112 list_for_each_entry_safe(p, n, &event_queue, list) { 113 list_del(&p->list); 114 kobject_uevent_env(&dev->kobj, KOBJ_CHANGE, p->envp); 115 smsg_app_event_free(p); 116 } 117 118 put_device(dev); 119 } 120 static DECLARE_WORK(smsg_event_work, smsg_event_work_fn); 121 122 static void smsg_app_callback(const char *from, char *msg) 123 { 124 struct smsg_app_event *se; 125 126 /* check if the originating z/VM user ID matches 127 * the configured sender. */ 128 if (sender && strlen(sender) > 0 && strcmp(from, sender) != 0) 129 return; 130 131 /* get start of message text (skip prefix and leading blanks) */ 132 msg += strlen(SMSG_PREFIX); 133 while (*msg && isspace(*msg)) 134 msg++; 135 if (*msg == '\0') 136 return; 137 138 /* allocate event list element and its environment */ 139 se = smsg_app_event_alloc(from, msg); 140 if (!se) 141 return; 142 143 /* queue event and schedule work function */ 144 spin_lock(&smsg_event_queue_lock); 145 list_add_tail(&se->list, &smsg_event_queue); 146 spin_unlock(&smsg_event_queue_lock); 147 148 schedule_work(&smsg_event_work); 149 return; 150 } 151 152 static int __init smsgiucv_app_init(void) 153 { 154 struct device_driver *smsgiucv_drv; 155 int rc; 156 157 if (!machine_is_vm()) 158 return -ENODEV; 159 160 smsgiucv_drv = driver_find(SMSGIUCV_DRV_NAME, &iucv_bus); 161 if (!smsgiucv_drv) 162 return -ENODEV; 163 164 smsg_app_dev = iucv_alloc_device(NULL, smsgiucv_drv, NULL, "smsgiucv_app"); 165 if (!smsg_app_dev) 166 return -ENOMEM; 167 168 rc = device_register(smsg_app_dev); 169 if (rc) { 170 put_device(smsg_app_dev); 171 goto fail; 172 } 173 174 /* convert sender to uppercase characters */ 175 if (sender) { 176 int len = strlen(sender); 177 while (len--) 178 sender[len] = toupper(sender[len]); 179 } 180 181 /* register with the smsgiucv device driver */ 182 rc = smsg_register_callback(SMSG_PREFIX, smsg_app_callback); 183 if (rc) { 184 device_unregister(smsg_app_dev); 185 goto fail; 186 } 187 188 rc = 0; 189 fail: 190 return rc; 191 } 192 module_init(smsgiucv_app_init); 193 194 static void __exit smsgiucv_app_exit(void) 195 { 196 /* unregister callback */ 197 smsg_unregister_callback(SMSG_PREFIX, smsg_app_callback); 198 199 /* cancel pending work and flush any queued event work */ 200 cancel_work_sync(&smsg_event_work); 201 smsg_event_work_fn(&smsg_event_work); 202 203 device_unregister(smsg_app_dev); 204 } 205 module_exit(smsgiucv_app_exit); 206 207 MODULE_LICENSE("GPL v2"); 208 MODULE_DESCRIPTION("Deliver z/VM CP SMSG as uevents"); 209 MODULE_AUTHOR("Hendrik Brueckner <brueckner@linux.vnet.ibm.com>"); 210