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