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 <asm/bitops.h>
  17
  18 extern struct tty_ldisc ldiscs[];
  19
  20
  21 static int tty_ldiscs_read_proc(char *page, char **start, off_t off,
  22                                 int count, int *eof, void *data);
  23
  24 /*
  25  * The /proc/tty directory inodes...
  26  */
  27 static struct proc_dir_entry *proc_tty_ldisc, *proc_tty_driver;
  28
  29 /*
  30  * This is the handler for /proc/tty/drivers
  31  */
  32 static void show_tty_range(struct seq_file *m, struct tty_driver *p,
  33         dev_t from, int num)
  34 {
  35         seq_printf(m, "%-20s ", p->driver_name ? p->driver_name : "unknown");
  36         seq_printf(m, "/dev/%-8s ", p->name);
  37         if (p->num > 1) {
  38                 char    range[20];
  39                 sprintf(range, "%d-%d", MINOR(from),
  40                         MINOR(from) + num - 1);
  41                 seq_printf(m, "%3d %7s ", MAJOR(from), range);
  42         } else {
  43                 seq_printf(m, "%3d %7d ", MAJOR(from), MINOR(from));
  44         }
  45         switch (p->type) {
  46         case TTY_DRIVER_TYPE_SYSTEM:
  47                 seq_printf(m, "system");
  48                 if (p->subtype == SYSTEM_TYPE_TTY)
  49                         seq_printf(m, ":/dev/tty");
  50                 else if (p->subtype == SYSTEM_TYPE_SYSCONS)
  51                         seq_printf(m, ":console");
  52                 else if (p->subtype == SYSTEM_TYPE_CONSOLE)
  53                         seq_printf(m, ":vtmaster");
  54                 break;
  55         case TTY_DRIVER_TYPE_CONSOLE:
  56                 seq_printf(m, "console");
  57                 break;
  58         case TTY_DRIVER_TYPE_SERIAL:
  59                 seq_printf(m, "serial");
  60                 break;
  61         case TTY_DRIVER_TYPE_PTY:
  62                 if (p->subtype == PTY_TYPE_MASTER)
  63                         seq_printf(m, "pty:master");
  64                 else if (p->subtype == PTY_TYPE_SLAVE)
  65                         seq_printf(m, "pty:slave");
  66                 else
  67                         seq_printf(m, "pty");
  68                 break;
  69         default:
  70                 seq_printf(m, "type:%d.%d", p->type, p->subtype);
  71         }
  72         seq_putc(m, '\n');
  73 }
  74
  75 static int show_tty_driver(struct seq_file *m, void *v)
  76 {
  77         struct tty_driver *p = v;
  78         dev_t from = MKDEV(p->major, p->minor_start);
  79         dev_t to = from + p->num;
  80
  81         if (&p->tty_drivers == tty_drivers.next) {
  82                 /* pseudo-drivers first */
  83                 seq_printf(m, "%-20s /dev/%-8s ", "/dev/tty", "tty");
  84                 seq_printf(m, "%3d %7d ", TTYAUX_MAJOR, 0);
  85                 seq_printf(m, "system:/dev/tty\n");
  86                 seq_printf(m, "%-20s /dev/%-8s ", "/dev/console", "console");
  87                 seq_printf(m, "%3d %7d ", TTYAUX_MAJOR, 1);
  88                 seq_printf(m, "system:console\n");
  89 #ifdef CONFIG_UNIX98_PTYS
  90                 seq_printf(m, "%-20s /dev/%-8s ", "/dev/ptmx", "ptmx");
  91                 seq_printf(m, "%3d %7d ", TTYAUX_MAJOR, 2);
  92                 seq_printf(m, "system\n");
  93 #endif
  94 #ifdef CONFIG_VT
  95                 seq_printf(m, "%-20s /dev/%-8s ", "/dev/vc/0", "vc/0");
  96                 seq_printf(m, "%3d %7d ", TTY_MAJOR, 0);
  97                 seq_printf(m, "system:vtmaster\n");
  98 #endif
  99         }
 100
 101         while (MAJOR(from) < MAJOR(to)) {
 102                 dev_t next = MKDEV(MAJOR(from)+1, 0);
 103                 show_tty_range(m, p, from, next - from);
 104                 from = next;
 105         }
 106         if (from != to)
 107                 show_tty_range(m, p, from, to - from);
 108         return 0;
 109 }
 110
 111 /* iterator */
 112 static void *t_start(struct seq_file *m, loff_t *pos)
 113 {
 114         struct list_head *p;
 115         loff_t l = *pos;
 116         list_for_each(p, &tty_drivers)
 117                 if (!l--)
 118                         return list_entry(p, struct tty_driver, tty_drivers);
 119         return NULL;
 120 }
 121
 122 static void *t_next(struct seq_file *m, void *v, loff_t *pos)
 123 {
 124         struct list_head *p = ((struct tty_driver *)v)->tty_drivers.next;
 125         (*pos)++;
 126         return p==&tty_drivers ? NULL :
 127                         list_entry(p, struct tty_driver, tty_drivers);
 128 }
 129
 130 static void t_stop(struct seq_file *m, void *v)
 131 {
 132 }
 133
 134 static struct seq_operations tty_drivers_op = {
 135         .start  = t_start,
 136         .next   = t_next,
 137         .stop   = t_stop,
 138         .show   = show_tty_driver
 139 };
 140
 141 static int tty_drivers_open(struct inode *inode, struct file *file)
 142 {
 143         return seq_open(file, &tty_drivers_op);
 144 }
 145
 146 static struct file_operations proc_tty_drivers_operations = {
 147         .open           = tty_drivers_open,
 148         .read           = seq_read,
 149         .llseek         = seq_lseek,
 150         .release        = seq_release,
 151 };
 152
 153 /*
 154  * This is the handler for /proc/tty/ldiscs
 155  */
 156 static int tty_ldiscs_read_proc(char *page, char **start, off_t off,
 157                                 int count, int *eof, void *data)
 158 {
 159         int     i;
 160         int     len = 0;
 161         off_t   begin = 0;
 162
 163         for (i=0; i < NR_LDISCS; i++) {
 164                 if (!(ldiscs[i].flags & LDISC_FLAG_DEFINED))
 165                         continue;
 166                 len += sprintf(page+len, "%-10s %2d\n",
 167                                ldiscs[i].name ? ldiscs[i].name : "???", i);
 168                 if (len+begin > off+count)
 169                         break;
 170                 if (len+begin < off) {
 171                         begin += len;
 172                         len = 0;
 173                 }
 174         }
 175         if (i >= NR_LDISCS)
 176                 *eof = 1;
 177         if (off >= len+begin)
 178                 return 0;
 179         *start = page + (off-begin);
 180         return ((count < begin+len-off) ? count : begin+len-off);
 181 }
 182
 183 /*
 184  * This function is called by tty_register_driver() to handle
 185  * registering the driver's /proc handler into /proc/tty/driver/<foo>
 186  */
 187 void proc_tty_register_driver(struct tty_driver *driver)
 188 {
 189         struct proc_dir_entry *ent;
 190
 191         if ((!driver->read_proc && !driver->write_proc) ||
 192             !driver->driver_name ||
 193             driver->proc_entry)
 194                 return;
 195
 196         ent = create_proc_entry(driver->driver_name, 0, proc_tty_driver);
 197         if (!ent)
 198                 return;
 199         ent->read_proc = driver->read_proc;
 200         ent->write_proc = driver->write_proc;
 201         ent->owner = driver->owner;
 202         ent->data = driver;
 203
 204         driver->proc_entry = ent;
 205 }
 206
 207 /*
 208  * This function is called by tty_unregister_driver()
 209  */
 210 void proc_tty_unregister_driver(struct tty_driver *driver)
 211 {
 212         struct proc_dir_entry *ent;
 213
 214         ent = driver->proc_entry;
 215         if (!ent)
 216                 return;
 217
 218         remove_proc_entry(driver->driver_name, proc_tty_driver);
 219
 220         driver->proc_entry = 0;
 221 }
 222
 223 /*
 224  * Called by proc_root_init() to initialize the /proc/tty subtree
 225  */
 226 void __init proc_tty_init(void)
 227 {
 228         struct proc_dir_entry *entry;
 229         if (!proc_mkdir("tty", 0))
 230                 return;
 231         proc_tty_ldisc = proc_mkdir("tty/ldisc", 0);
 232         /*
 233          * /proc/tty/driver/serial reveals the exact character counts for
 234          * serial links which is just too easy to abuse for inferring
 235          * password lengths and inter-keystroke timings during password
 236          * entry.
 237          */
 238         proc_tty_driver = proc_mkdir_mode("tty/driver", S_IRUSR | S_IXUSR, 0);
 239
 240         create_proc_read_entry("tty/ldiscs", 0, 0, tty_ldiscs_read_proc,NULL);
 241         entry = create_proc_entry("tty/drivers", 0, NULL);
 242         if (entry)
 243                 entry->proc_fops = &proc_tty_drivers_operations;
 244 }