fs/proc/proc_tty.c

   1 /*
   2  * proc_tty.c -- handles /proc/tty
   3  *
   4  * Copyright 1997, Theodore Ts'o
   5  */
   6
   7 #include <asm/uaccess.h>
   8 #include <linux/module.h>
   9 #include <linux/init.h>
  10 #include <linux/errno.h>
  11 #include <linux/time.h>
  12 #include <linux/proc_fs.h>
  13 #include <linux/stat.h>
  14 #include <linux/tty.h>
  15 #include <linux/tty_driver.h>
  16 #include <linux/console.h>
  17 #include <linux/seq_file.h>
  18 #include <linux/fdtable.h>
  19 #include <linux/bitops.h>
  20
  21 /*
  22  * The /proc/tty directory inodes...
  23  */
  24 static struct proc_dir_entry *proc_tty_ldisc, *proc_tty_driver;
  25
  26 /*
  27  * This is the handler for /proc/tty/drivers
  28  */
  29 static void show_tty_range(struct seq_file *m, struct tty_driver *p,
  30         dev_t from, int num)
  31 {
  32         seq_printf(m, "%-20s ", p->driver_name ? p->driver_name : "unknown");
  33         seq_printf(m, "/dev/%-8s ", p->name);
  34         if (p->num > 1) {
  35                 seq_printf(m, "%3d %d-%d ", MAJOR(from), MINOR(from),
  36                         MINOR(from) + num - 1);
  37         } else {
  38                 seq_printf(m, "%3d %7d ", MAJOR(from), MINOR(from));
  39         }
  40         switch (p->type) {
  41         case TTY_DRIVER_TYPE_SYSTEM:
  42                 seq_printf(m, "system");
  43                 if (p->subtype == SYSTEM_TYPE_TTY)
  44                         seq_printf(m, ":/dev/tty");
  45                 else if (p->subtype == SYSTEM_TYPE_SYSCONS)
  46                         seq_printf(m, ":console");
  47                 else if (p->subtype == SYSTEM_TYPE_CONSOLE)
  48                         seq_printf(m, ":vtmaster");
  49                 break;
  50         case TTY_DRIVER_TYPE_CONSOLE:
  51                 seq_printf(m, "console");
  52                 break;
  53         case TTY_DRIVER_TYPE_SERIAL:
  54                 seq_printf(m, "serial");
  55                 break;
  56         case TTY_DRIVER_TYPE_PTY:
  57                 if (p->subtype == PTY_TYPE_MASTER)
  58                         seq_printf(m, "pty:master");
  59                 else if (p->subtype == PTY_TYPE_SLAVE)
  60                         seq_printf(m, "pty:slave");
  61                 else
  62                         seq_printf(m, "pty");
  63                 break;
  64         default:
  65                 seq_printf(m, "type:%d.%d", p->type, p->subtype);
  66         }
  67         seq_putc(m, '\n');
  68 }
  69
  70 static int show_tty_driver(struct seq_file *m, void *v)
  71 {
  72         struct tty_driver *p = list_entry(v, struct tty_driver, tty_drivers);
  73         dev_t from = MKDEV(p->major, p->minor_start);
  74         dev_t to = from + p->num;
  75
  76         if (&p->tty_drivers == tty_drivers.next) {
  77                 /* pseudo-drivers first */
  78                 seq_printf(m, "%-20s /dev/%-8s ", "/dev/tty", "tty");
  79                 seq_printf(m, "%3d %7d ", TTYAUX_MAJOR, 0);
  80                 seq_printf(m, "system:/dev/tty\n");
  81                 seq_printf(m, "%-20s /dev/%-8s ", "/dev/console", "console");
  82                 seq_printf(m, "%3d %7d ", TTYAUX_MAJOR, 1);
  83                 seq_printf(m, "system:console\n");
  84 #ifdef CONFIG_UNIX98_PTYS
  85                 seq_printf(m, "%-20s /dev/%-8s ", "/dev/ptmx", "ptmx");
  86                 seq_printf(m, "%3d %7d ", TTYAUX_MAJOR, 2);
  87                 seq_printf(m, "system\n");
  88 #endif
  89 #ifdef CONFIG_VT
  90                 seq_printf(m, "%-20s /dev/%-8s ", "/dev/vc/0", "vc/0");
  91                 seq_printf(m, "%3d %7d ", TTY_MAJOR, 0);
  92                 seq_printf(m, "system:vtmaster\n");
  93 #endif
  94         }
  95
  96         while (MAJOR(from) < MAJOR(to)) {
  97                 dev_t next = MKDEV(MAJOR(from)+1, 0);
  98                 show_tty_range(m, p, from, next - from);
  99                 from = next;
 100         }
 101         if (from != to)
 102                 show_tty_range(m, p, from, to - from);
 103         return 0;
 104 }
 105
 106 /* iterator */
 107 static void *t_start(struct seq_file *m, loff_t *pos)
 108 {
 109         mutex_lock(&tty_mutex);
 110         return seq_list_start(&tty_drivers, *pos);
 111 }
 112
 113 static void *t_next(struct seq_file *m, void *v, loff_t *pos)
 114 {
 115         return seq_list_next(v, &tty_drivers, pos);
 116 }
 117
 118 static void t_stop(struct seq_file *m, void *v)
 119 {
 120         mutex_unlock(&tty_mutex);
 121 }
 122
 123 static const struct seq_operations tty_drivers_op = {
 124         .start  = t_start,
 125         .next   = t_next,
 126         .stop   = t_stop,
 127         .show   = show_tty_driver
 128 };
 129
 130 static int tty_drivers_open(struct inode *inode, struct file *file)
 131 {
 132         return seq_open(file, &tty_drivers_op);
 133 }
 134
 135 static const struct file_operations proc_tty_drivers_operations = {
 136         .open           = tty_drivers_open,
 137         .read           = seq_read,
 138         .llseek         = seq_lseek,
 139         .release        = seq_release,
 140 };
 141
 142 /*
 143  * The device ID of file descriptor 0 of the current reading
 144  * task if a character device...
 145  */
 146 static dev_t current_dev;
 147
 148 /*
 149  * This is the handler for /proc/tty/consoles
 150  */
 151 static int show_console_dev(struct seq_file *m, void *v)
 152 {
 153         const struct tty_driver *driver;
 154         struct console *con;
 155         int index, len;
 156         char flags[10];
 157         dev_t dev;
 158
 159         if (v == SEQ_START_TOKEN)
 160                 return 0;
 161         con = (struct console *)v;
 162         if (!con)
 163                 return 0;
 164         driver = con->device(con, &index);
 165         if (!driver)
 166                 return 0;
 167         dev = MKDEV(driver->major, driver->minor_start) + index;
 168
 169         index = 0;
 170         if (con->flags & CON_ENABLED)
 171                 flags[index++] = 'E';
 172         if (con->flags & CON_CONSDEV)
 173                 flags[index++] = 'C';
 174         if (con->flags & CON_BOOT)
 175                 flags[index++] = 'B';
 176         if (con->flags & CON_PRINTBUFFER)
 177                 flags[index++] = 'p';
 178         if (con->flags & CON_BRL)
 179                 flags[index++] = 'b';
 180         if (con->flags & CON_ANYTIME)
 181                 flags[index++] = 'a';
 182         if (current_dev == dev)
 183                 flags[index++] = '*';
 184         flags[index] = 0;
 185
 186         seq_printf(m, "%s%d%n", con->name, con->index, &len);
 187         len = 21 - len;
 188         if (len < 1)
 189                 len = 1;
 190         seq_printf(m, "%*c", len, ' ');
 191         seq_printf(m, "%c%c%c (%s)%n", con->read ? 'R' : '-',
 192                         con->write ? 'W' : '-', con->unblank ? 'U' : '-',
 193                         flags, &len);
 194         len = 13 - len;
 195         if (len < 1)
 196                 len = 1;
 197         seq_printf(m, "%*c%4d:%d\n", len, ' ', MAJOR(dev), MINOR(dev));
 198
 199         return 0;
 200 }
 201
 202 /* iterator for consoles */
 203 static void *c_start(struct seq_file *m, loff_t *pos)
 204 {
 205         struct console *con;
 206         loff_t off = 0;
 207
 208         if (*pos == 0)
 209                 return SEQ_START_TOKEN;
 210
 211         acquire_console_sem();
 212         for (con = console_drivers; con; con = con->next) {
 213                 if (!con->device)
 214                         continue;
 215                 if (++off == *pos)
 216                         break;
 217         }
 218         release_console_sem();
 219
 220         return con;
 221 }
 222
 223 static void *c_next(struct seq_file *m, void *v, loff_t *pos)
 224 {
 225         struct console *con;
 226
 227         acquire_console_sem();
 228         if (v == SEQ_START_TOKEN)
 229                 con = console_drivers;
 230         else
 231                 con = ((struct console *)v)->next;
 232         for (; con; con = con->next) {
 233                 if (!con->device)
 234                         continue;
 235                 ++*pos;
 236                 break;
 237         }
 238         release_console_sem();
 239
 240         return con;
 241 }
 242
 243 static void c_stop(struct seq_file *m, void *v)
 244 {
 245 }
 246
 247 static const struct seq_operations tty_consoles_op = {
 248         .start  = c_start,
 249         .next   = c_next,
 250         .stop   = c_stop,
 251         .show   = show_console_dev
 252 };
 253
 254 /*
 255  * Used for open /proc/tty/consoles. Before this detect
 256  * the device ID of file descriptor 0 of the current
 257  * reading task if a character device...
 258  */
 259 static int tty_consoles_open(struct inode *inode, struct file *file)
 260 {
 261         struct files_struct *curfiles;
 262
 263         current_dev = 0;
 264         curfiles = get_files_struct(current);
 265         if (curfiles) {
 266                 const struct file *curfp;
 267                 spin_lock(&curfiles->file_lock);
 268                 curfp = fcheck_files(curfiles, 0);
 269                 if (curfp && curfp->private_data) {
 270                         const struct inode *inode;
 271                         dget(curfp->f_dentry);
 272                         inode = curfp->f_dentry->d_inode;
 273                         if (S_ISCHR(inode->i_mode)) {
 274                                 struct tty_struct *tty;
 275                                 tty = (struct tty_struct *)curfp->private_data;
 276                                 if (tty && tty->magic == TTY_MAGIC) {
 277                                         tty = tty_pair_get_tty(tty);
 278                                         current_dev = tty_devnum(tty);
 279                                 }
 280                         }
 281                         dput(curfp->f_dentry);
 282                 }
 283                 spin_unlock(&curfiles->file_lock);
 284                 put_files_struct(curfiles);
 285         }
 286         return seq_open(file, &tty_consoles_op);
 287 }
 288
 289 static const struct file_operations proc_tty_consoles_operations = {
 290         .open           = tty_consoles_open,
 291         .read           = seq_read,
 292         .llseek         = seq_lseek,
 293         .release        = seq_release,
 294 };
 295
 296 /*
 297  * This function is called by tty_register_driver() to handle
 298  * registering the driver's /proc handler into /proc/tty/driver/<foo>
 299  */
 300 void proc_tty_register_driver(struct tty_driver *driver)
 301 {
 302         struct proc_dir_entry *ent;
 303
 304         if (!driver->driver_name || driver->proc_entry ||
 305             !driver->ops->proc_fops)
 306                 return;
 307
 308         ent = proc_create_data(driver->driver_name, 0, proc_tty_driver,
 309                                driver->ops->proc_fops, driver);
 310         driver->proc_entry = ent;
 311 }
 312
 313 /*
 314  * This function is called by tty_unregister_driver()
 315  */
 316 void proc_tty_unregister_driver(struct tty_driver *driver)
 317 {
 318         struct proc_dir_entry *ent;
 319
 320         ent = driver->proc_entry;
 321         if (!ent)
 322                 return;
 323
 324         remove_proc_entry(driver->driver_name, proc_tty_driver);
 325
 326         driver->proc_entry = NULL;
 327 }
 328
 329 /*
 330  * Called by proc_root_init() to initialize the /proc/tty subtree
 331  */
 332 void __init proc_tty_init(void)
 333 {
 334         if (!proc_mkdir("tty", NULL))
 335                 return;
 336         proc_tty_ldisc = proc_mkdir("tty/ldisc", NULL);
 337         /*
 338          * /proc/tty/driver/serial reveals the exact character counts for
 339          * serial links which is just too easy to abuse for inferring
 340          * password lengths and inter-keystroke timings during password
 341          * entry.
 342          */
 343         proc_tty_driver = proc_mkdir_mode("tty/driver", S_IRUSR|S_IXUSR, NULL);
 344         proc_create("tty/ldiscs", 0, NULL, &tty_ldiscs_proc_fops);
 345         proc_create("tty/drivers", 0, NULL, &proc_tty_drivers_operations);
 346         proc_create("tty/consoles", 0, NULL, &proc_tty_consoles_operations);
 347 }