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
   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/seq_file.h>
  16 #include <linux/bitops.h>
  17
  18 static int tty_ldiscs_read_proc(char *page, char **start, off_t off,
  19                                 int count, int *eof, void *data);
  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 = v;
  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         struct list_head *p;
 110         loff_t l = *pos;
 111
 112         mutex_lock(&tty_mutex);
 113         list_for_each(p, &tty_drivers)
 114                 if (!l--)
 115                         return list_entry(p, struct tty_driver, tty_drivers);
 116         return NULL;
 117 }
 118
 119 static void *t_next(struct seq_file *m, void *v, loff_t *pos)
 120 {
 121         struct list_head *p = ((struct tty_driver *)v)->tty_drivers.next;
 122         (*pos)++;
 123         return p==&tty_drivers ? NULL :
 124                         list_entry(p, struct tty_driver, tty_drivers);
 125 }
 126
 127 static void t_stop(struct seq_file *m, void *v)
 128 {
 129         mutex_unlock(&tty_mutex);
 130 }
 131
 132 static struct seq_operations tty_drivers_op = {
 133         .start  = t_start,
 134         .next   = t_next,
 135         .stop   = t_stop,
 136         .show   = show_tty_driver
 137 };
 138
 139 static int tty_drivers_open(struct inode *inode, struct file *file)
 140 {
 141         return seq_open(file, &tty_drivers_op);
 142 }
 143
 144 static const struct file_operations proc_tty_drivers_operations = {
 145         .open           = tty_drivers_open,
 146         .read           = seq_read,
 147         .llseek         = seq_lseek,
 148         .release        = seq_release,
 149 };
 150
 151 /*
 152  * This is the handler for /proc/tty/ldiscs
 153  */
 154 static int tty_ldiscs_read_proc(char *page, char **start, off_t off,
 155                                 int count, int *eof, void *data)
 156 {
 157         int     i;
 158         int     len = 0;
 159         off_t   begin = 0;
 160         struct tty_ldisc *ld;
 161
 162         for (i=0; i < NR_LDISCS; i++) {
 163                 ld = tty_ldisc_get(i);
 164                 if (ld == NULL)
 165                         continue;
 166                 len += sprintf(page+len, "%-10s %2d\n",
 167                                ld->name ? ld->name : "???", i);
 168                 tty_ldisc_put(i);
 169                 if (len+begin > off+count)
 170                         break;
 171                 if (len+begin < off) {
 172                         begin += len;
 173                         len = 0;
 174                 }
 175         }
 176         if (i >= NR_LDISCS)
 177                 *eof = 1;
 178         if (off >= len+begin)
 179                 return 0;
 180         *start = page + (off-begin);
 181         return ((count < begin+len-off) ? count : begin+len-off);
 182 }
 183
 184 /*
 185  * This function is called by tty_register_driver() to handle
 186  * registering the driver's /proc handler into /proc/tty/driver/<foo>
 187  */
 188 void proc_tty_register_driver(struct tty_driver *driver)
 189 {
 190         struct proc_dir_entry *ent;
 191
 192         if ((!driver->read_proc && !driver->write_proc) ||
 193             !driver->driver_name ||
 194             driver->proc_entry)
 195                 return;
 196
 197         ent = create_proc_entry(driver->driver_name, 0, proc_tty_driver);
 198         if (!ent)
 199                 return;
 200         ent->read_proc = driver->read_proc;
 201         ent->write_proc = driver->write_proc;
 202         ent->owner = driver->owner;
 203         ent->data = driver;
 204
 205         driver->proc_entry = ent;
 206 }
 207
 208 /*
 209  * This function is called by tty_unregister_driver()
 210  */
 211 void proc_tty_unregister_driver(struct tty_driver *driver)
 212 {
 213         struct proc_dir_entry *ent;
 214
 215         ent = driver->proc_entry;
 216         if (!ent)
 217                 return;
 218
 219         remove_proc_entry(driver->driver_name, proc_tty_driver);
 220
 221         driver->proc_entry = NULL;
 222 }
 223
 224 /*
 225  * Called by proc_root_init() to initialize the /proc/tty subtree
 226  */
 227 void __init proc_tty_init(void)
 228 {
 229         struct proc_dir_entry *entry;
 230         if (!proc_mkdir("tty", NULL))
 231                 return;
 232         proc_tty_ldisc = proc_mkdir("tty/ldisc", NULL);
 233         /*
 234          * /proc/tty/driver/serial reveals the exact character counts for
 235          * serial links which is just too easy to abuse for inferring
 236          * password lengths and inter-keystroke timings during password
 237          * entry.
 238          */
 239         proc_tty_driver = proc_mkdir_mode("tty/driver", S_IRUSR | S_IXUSR, NULL);
 240
 241         create_proc_read_entry("tty/ldiscs", 0, NULL, tty_ldiscs_read_proc, NULL);
 242         entry = create_proc_entry("tty/drivers", 0, NULL);
 243         if (entry)
 244                 entry->proc_fops = &proc_tty_drivers_operations;
 245 }