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 /*
  19  * The /proc/tty directory inodes...
  20  */
  21 static struct proc_dir_entry *proc_tty_ldisc, *proc_tty_driver;
  22
  23 /*
  24  * This is the handler for /proc/tty/drivers
  25  */
  26 static void show_tty_range(struct seq_file *m, struct tty_driver *p,
  27         dev_t from, int num)
  28 {
  29         seq_printf(m, "%-20s ", p->driver_name ? p->driver_name : "unknown");
  30         seq_printf(m, "/dev/%-8s ", p->name);
  31         if (p->num > 1) {
  32                 seq_printf(m, "%3d %d-%d ", MAJOR(from), MINOR(from),
  33                         MINOR(from) + num - 1);
  34         } else {
  35                 seq_printf(m, "%3d %7d ", MAJOR(from), MINOR(from));
  36         }
  37         switch (p->type) {
  38         case TTY_DRIVER_TYPE_SYSTEM:
  39                 seq_printf(m, "system");
  40                 if (p->subtype == SYSTEM_TYPE_TTY)
  41                         seq_printf(m, ":/dev/tty");
  42                 else if (p->subtype == SYSTEM_TYPE_SYSCONS)
  43                         seq_printf(m, ":console");
  44                 else if (p->subtype == SYSTEM_TYPE_CONSOLE)
  45                         seq_printf(m, ":vtmaster");
  46                 break;
  47         case TTY_DRIVER_TYPE_CONSOLE:
  48                 seq_printf(m, "console");
  49                 break;
  50         case TTY_DRIVER_TYPE_SERIAL:
  51                 seq_printf(m, "serial");
  52                 break;
  53         case TTY_DRIVER_TYPE_PTY:
  54                 if (p->subtype == PTY_TYPE_MASTER)
  55                         seq_printf(m, "pty:master");
  56                 else if (p->subtype == PTY_TYPE_SLAVE)
  57                         seq_printf(m, "pty:slave");
  58                 else
  59                         seq_printf(m, "pty");
  60                 break;
  61         default:
  62                 seq_printf(m, "type:%d.%d", p->type, p->subtype);
  63         }
  64         seq_putc(m, '\n');
  65 }
  66
  67 static int show_tty_driver(struct seq_file *m, void *v)
  68 {
  69         struct tty_driver *p = list_entry(v, struct tty_driver, tty_drivers);
  70         dev_t from = MKDEV(p->major, p->minor_start);
  71         dev_t to = from + p->num;
  72
  73         if (&p->tty_drivers == tty_drivers.next) {
  74                 /* pseudo-drivers first */
  75                 seq_printf(m, "%-20s /dev/%-8s ", "/dev/tty", "tty");
  76                 seq_printf(m, "%3d %7d ", TTYAUX_MAJOR, 0);
  77                 seq_printf(m, "system:/dev/tty\n");
  78                 seq_printf(m, "%-20s /dev/%-8s ", "/dev/console", "console");
  79                 seq_printf(m, "%3d %7d ", TTYAUX_MAJOR, 1);
  80                 seq_printf(m, "system:console\n");
  81 #ifdef CONFIG_UNIX98_PTYS
  82                 seq_printf(m, "%-20s /dev/%-8s ", "/dev/ptmx", "ptmx");
  83                 seq_printf(m, "%3d %7d ", TTYAUX_MAJOR, 2);
  84                 seq_printf(m, "system\n");
  85 #endif
  86 #ifdef CONFIG_VT
  87                 seq_printf(m, "%-20s /dev/%-8s ", "/dev/vc/0", "vc/0");
  88                 seq_printf(m, "%3d %7d ", TTY_MAJOR, 0);
  89                 seq_printf(m, "system:vtmaster\n");
  90 #endif
  91         }
  92
  93         while (MAJOR(from) < MAJOR(to)) {
  94                 dev_t next = MKDEV(MAJOR(from)+1, 0);
  95                 show_tty_range(m, p, from, next - from);
  96                 from = next;
  97         }
  98         if (from != to)
  99                 show_tty_range(m, p, from, to - from);
 100         return 0;
 101 }
 102
 103 /* iterator */
 104 static void *t_start(struct seq_file *m, loff_t *pos)
 105 {
 106         mutex_lock(&tty_mutex);
 107         return seq_list_start(&tty_drivers, *pos);
 108 }
 109
 110 static void *t_next(struct seq_file *m, void *v, loff_t *pos)
 111 {
 112         return seq_list_next(v, &tty_drivers, pos);
 113 }
 114
 115 static void t_stop(struct seq_file *m, void *v)
 116 {
 117         mutex_unlock(&tty_mutex);
 118 }
 119
 120 static const struct seq_operations tty_drivers_op = {
 121         .start  = t_start,
 122         .next   = t_next,
 123         .stop   = t_stop,
 124         .show   = show_tty_driver
 125 };
 126
 127 static int tty_drivers_open(struct inode *inode, struct file *file)
 128 {
 129         return seq_open(file, &tty_drivers_op);
 130 }
 131
 132 static const struct file_operations proc_tty_drivers_operations = {
 133         .open           = tty_drivers_open,
 134         .read           = seq_read,
 135         .llseek         = seq_lseek,
 136         .release        = seq_release,
 137 };
 138
 139 /*
 140  * This is the handler for /proc/tty/ldiscs
 141  */
 142 static int tty_ldiscs_read_proc(char *page, char **start, off_t off,
 143                                 int count, int *eof, void *data)
 144 {
 145         int     i;
 146         int     len = 0;
 147         off_t   begin = 0;
 148         struct tty_ldisc *ld;
 149
 150         for (i=0; i < NR_LDISCS; i++) {
 151                 ld = tty_ldisc_get(i);
 152                 if (ld == NULL)
 153                         continue;
 154                 len += sprintf(page+len, "%-10s %2d\n",
 155                                ld->name ? ld->name : "???", i);
 156                 tty_ldisc_put(i);
 157                 if (len+begin > off+count)
 158                         break;
 159                 if (len+begin < off) {
 160                         begin += len;
 161                         len = 0;
 162                 }
 163         }
 164         if (i >= NR_LDISCS)
 165                 *eof = 1;
 166         if (off >= len+begin)
 167                 return 0;
 168         *start = page + (off-begin);
 169         return ((count < begin+len-off) ? count : begin+len-off);
 170 }
 171
 172 /*
 173  * This function is called by tty_register_driver() to handle
 174  * registering the driver's /proc handler into /proc/tty/driver/<foo>
 175  */
 176 void proc_tty_register_driver(struct tty_driver *driver)
 177 {
 178         struct proc_dir_entry *ent;
 179
 180         if ((!driver->read_proc && !driver->write_proc) ||
 181             !driver->driver_name ||
 182             driver->proc_entry)
 183                 return;
 184
 185         ent = create_proc_entry(driver->driver_name, 0, proc_tty_driver);
 186         if (!ent)
 187                 return;
 188         ent->read_proc = driver->read_proc;
 189         ent->write_proc = driver->write_proc;
 190         ent->owner = driver->owner;
 191         ent->data = driver;
 192
 193         driver->proc_entry = ent;
 194 }
 195
 196 /*
 197  * This function is called by tty_unregister_driver()
 198  */
 199 void proc_tty_unregister_driver(struct tty_driver *driver)
 200 {
 201         struct proc_dir_entry *ent;
 202
 203         ent = driver->proc_entry;
 204         if (!ent)
 205                 return;
 206
 207         remove_proc_entry(driver->driver_name, proc_tty_driver);
 208
 209         driver->proc_entry = NULL;
 210 }
 211
 212 /*
 213  * Called by proc_root_init() to initialize the /proc/tty subtree
 214  */
 215 void __init proc_tty_init(void)
 216 {
 217         struct proc_dir_entry *entry;
 218         if (!proc_mkdir("tty", NULL))
 219                 return;
 220         proc_tty_ldisc = proc_mkdir("tty/ldisc", NULL);
 221         /*
 222          * /proc/tty/driver/serial reveals the exact character counts for
 223          * serial links which is just too easy to abuse for inferring
 224          * password lengths and inter-keystroke timings during password
 225          * entry.
 226          */
 227         proc_tty_driver = proc_mkdir_mode("tty/driver", S_IRUSR | S_IXUSR, NULL);
 228
 229         create_proc_read_entry("tty/ldiscs", 0, NULL, tty_ldiscs_read_proc, NULL);
 230         entry = create_proc_entry("tty/drivers", 0, NULL);
 231         if (entry)
 232                 entry->proc_fops = &proc_tty_drivers_operations;
 233 }