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