1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Copyright (C) 2001 - 2007 Jeff Dike (jdike@{linux.intel,addtoit}.com) 4 */ 5 6 #include <linux/completion.h> 7 #include <linux/interrupt.h> 8 #include <linux/list.h> 9 #include <linux/mutex.h> 10 #include <linux/slab.h> 11 #include <linux/workqueue.h> 12 #include <asm/atomic.h> 13 #include <init.h> 14 #include <irq_kern.h> 15 #include <os.h> 16 #include "port.h" 17 18 struct port_list { 19 struct list_head list; 20 atomic_t wait_count; 21 int has_connection; 22 struct completion done; 23 int port; 24 int fd; 25 spinlock_t lock; 26 struct list_head pending; 27 struct list_head connections; 28 }; 29 30 struct port_dev { 31 struct port_list *port; 32 int helper_pid; 33 int telnetd_pid; 34 }; 35 36 struct connection { 37 struct list_head list; 38 int fd; 39 int helper_pid; 40 int socket[2]; 41 int telnetd_pid; 42 struct port_list *port; 43 }; 44 45 static irqreturn_t pipe_interrupt(int irq, void *data) 46 { 47 struct connection *conn = data; 48 int fd; 49 50 fd = os_rcv_fd(conn->socket[0], &conn->helper_pid); 51 if (fd < 0) { 52 if (fd == -EAGAIN) 53 return IRQ_NONE; 54 55 printk(KERN_ERR "pipe_interrupt : os_rcv_fd returned %d\n", 56 -fd); 57 os_close_file(conn->fd); 58 } 59 60 list_del(&conn->list); 61 62 conn->fd = fd; 63 list_add(&conn->list, &conn->port->connections); 64 65 complete(&conn->port->done); 66 return IRQ_HANDLED; 67 } 68 69 #define NO_WAITER_MSG \ 70 "****\n" \ 71 "There are currently no UML consoles waiting for port connections.\n" \ 72 "Either disconnect from one to make it available or activate some more\n" \ 73 "by enabling more consoles in the UML /etc/inittab.\n" \ 74 "****\n" 75 76 static int port_accept(struct port_list *port) 77 { 78 struct connection *conn; 79 int fd, socket[2], pid; 80 81 fd = port_connection(port->fd, socket, &pid); 82 if (fd < 0) { 83 if (fd != -EAGAIN) 84 printk(KERN_ERR "port_accept : port_connection " 85 "returned %d\n", -fd); 86 goto out; 87 } 88 89 conn = kmalloc(sizeof(*conn), GFP_ATOMIC); 90 if (conn == NULL) { 91 printk(KERN_ERR "port_accept : failed to allocate " 92 "connection\n"); 93 goto out_close; 94 } 95 *conn = ((struct connection) 96 { .list = LIST_HEAD_INIT(conn->list), 97 .fd = fd, 98 .socket = { socket[0], socket[1] }, 99 .telnetd_pid = pid, 100 .port = port }); 101 102 if (um_request_irq(TELNETD_IRQ, socket[0], IRQ_READ, pipe_interrupt, 103 IRQF_SHARED, "telnetd", conn) < 0) { 104 printk(KERN_ERR "port_accept : failed to get IRQ for " 105 "telnetd\n"); 106 goto out_free; 107 } 108 109 if (atomic_read(&port->wait_count) == 0) { 110 os_write_file(fd, NO_WAITER_MSG, sizeof(NO_WAITER_MSG)); 111 printk(KERN_ERR "No one waiting for port\n"); 112 } 113 list_add(&conn->list, &port->pending); 114 return 1; 115 116 out_free: 117 kfree(conn); 118 out_close: 119 os_close_file(fd); 120 os_kill_process(pid, 1); 121 out: 122 return 0; 123 } 124 125 static DEFINE_MUTEX(ports_mutex); 126 static LIST_HEAD(ports); 127 128 static void port_work_proc(struct work_struct *unused) 129 { 130 struct port_list *port; 131 struct list_head *ele; 132 unsigned long flags; 133 134 local_irq_save(flags); 135 list_for_each(ele, &ports) { 136 port = list_entry(ele, struct port_list, list); 137 if (!port->has_connection) 138 continue; 139 140 while (port_accept(port)) 141 ; 142 port->has_connection = 0; 143 } 144 local_irq_restore(flags); 145 } 146 147 DECLARE_WORK(port_work, port_work_proc); 148 149 static irqreturn_t port_interrupt(int irq, void *data) 150 { 151 struct port_list *port = data; 152 153 port->has_connection = 1; 154 schedule_work(&port_work); 155 return IRQ_HANDLED; 156 } 157 158 void *port_data(int port_num) 159 { 160 struct list_head *ele; 161 struct port_list *port; 162 struct port_dev *dev = NULL; 163 int fd; 164 165 mutex_lock(&ports_mutex); 166 list_for_each(ele, &ports) { 167 port = list_entry(ele, struct port_list, list); 168 if (port->port == port_num) 169 goto found; 170 } 171 port = kmalloc(sizeof(struct port_list), GFP_KERNEL); 172 if (port == NULL) { 173 printk(KERN_ERR "Allocation of port list failed\n"); 174 goto out; 175 } 176 177 fd = port_listen_fd(port_num); 178 if (fd < 0) { 179 printk(KERN_ERR "binding to port %d failed, errno = %d\n", 180 port_num, -fd); 181 goto out_free; 182 } 183 184 if (um_request_irq(ACCEPT_IRQ, fd, IRQ_READ, port_interrupt, 185 IRQF_SHARED, "port", port) < 0) { 186 printk(KERN_ERR "Failed to get IRQ for port %d\n", port_num); 187 goto out_close; 188 } 189 190 *port = ((struct port_list) 191 { .list = LIST_HEAD_INIT(port->list), 192 .wait_count = ATOMIC_INIT(0), 193 .has_connection = 0, 194 .port = port_num, 195 .fd = fd, 196 .pending = LIST_HEAD_INIT(port->pending), 197 .connections = LIST_HEAD_INIT(port->connections) }); 198 spin_lock_init(&port->lock); 199 init_completion(&port->done); 200 list_add(&port->list, &ports); 201 202 found: 203 dev = kmalloc(sizeof(struct port_dev), GFP_KERNEL); 204 if (dev == NULL) { 205 printk(KERN_ERR "Allocation of port device entry failed\n"); 206 goto out; 207 } 208 209 *dev = ((struct port_dev) { .port = port, 210 .helper_pid = -1, 211 .telnetd_pid = -1 }); 212 goto out; 213 214 out_close: 215 os_close_file(fd); 216 out_free: 217 kfree(port); 218 out: 219 mutex_unlock(&ports_mutex); 220 return dev; 221 } 222 223 int port_wait(void *data) 224 { 225 struct port_dev *dev = data; 226 struct connection *conn; 227 struct port_list *port = dev->port; 228 int fd; 229 230 atomic_inc(&port->wait_count); 231 while (1) { 232 fd = -ERESTARTSYS; 233 if (wait_for_completion_interruptible(&port->done)) 234 goto out; 235 236 spin_lock(&port->lock); 237 238 conn = list_entry(port->connections.next, struct connection, 239 list); 240 list_del(&conn->list); 241 spin_unlock(&port->lock); 242 243 os_shutdown_socket(conn->socket[0], 1, 1); 244 os_close_file(conn->socket[0]); 245 os_shutdown_socket(conn->socket[1], 1, 1); 246 os_close_file(conn->socket[1]); 247 248 /* This is done here because freeing an IRQ can't be done 249 * within the IRQ handler. So, pipe_interrupt always ups 250 * the semaphore regardless of whether it got a successful 251 * connection. Then we loop here throwing out failed 252 * connections until a good one is found. 253 */ 254 um_free_irq(TELNETD_IRQ, conn); 255 256 if (conn->fd >= 0) 257 break; 258 os_close_file(conn->fd); 259 kfree(conn); 260 } 261 262 fd = conn->fd; 263 dev->helper_pid = conn->helper_pid; 264 dev->telnetd_pid = conn->telnetd_pid; 265 kfree(conn); 266 out: 267 atomic_dec(&port->wait_count); 268 return fd; 269 } 270 271 void port_remove_dev(void *d) 272 { 273 struct port_dev *dev = d; 274 275 if (dev->helper_pid != -1) 276 os_kill_process(dev->helper_pid, 0); 277 if (dev->telnetd_pid != -1) 278 os_kill_process(dev->telnetd_pid, 1); 279 dev->helper_pid = -1; 280 dev->telnetd_pid = -1; 281 } 282 283 void port_kern_free(void *d) 284 { 285 struct port_dev *dev = d; 286 287 port_remove_dev(dev); 288 kfree(dev); 289 } 290 291 static void free_port(void) 292 { 293 struct list_head *ele; 294 struct port_list *port; 295 296 list_for_each(ele, &ports) { 297 port = list_entry(ele, struct port_list, list); 298 free_irq_by_fd(port->fd); 299 os_close_file(port->fd); 300 } 301 } 302 303 __uml_exitcall(free_port); 304