arch/um/drivers/port_kern.c

   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)) {
 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)) {
 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);