1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * proc_tty.c -- handles /proc/tty 4 * 5 * Copyright 1997, Theodore Ts'o 6 */ 7 8 #include <linux/uaccess.h> 9 #include <linux/module.h> 10 #include <linux/init.h> 11 #include <linux/errno.h> 12 #include <linux/time.h> 13 #include <linux/proc_fs.h> 14 #include <linux/stat.h> 15 #include <linux/tty.h> 16 #include <linux/seq_file.h> 17 #include <linux/bitops.h> 18 #include "internal.h" 19 20 /* 21 * The /proc/tty directory inodes... 22 */ 23 static struct proc_dir_entry *proc_tty_driver; 24 25 /* 26 * This is the handler for /proc/tty/drivers 27 */ 28 static void show_tty_range(struct seq_file *m, struct tty_driver *p, 29 dev_t from, int num) 30 { 31 seq_printf(m, "%-20s ", p->driver_name ? p->driver_name : "unknown"); 32 seq_printf(m, "/dev/%-8s ", p->name); 33 if (p->num > 1) { 34 seq_printf(m, "%3d %d-%d ", MAJOR(from), MINOR(from), 35 MINOR(from) + num - 1); 36 } else { 37 seq_printf(m, "%3d %7d ", MAJOR(from), MINOR(from)); 38 } 39 switch (p->type) { 40 case TTY_DRIVER_TYPE_SYSTEM: 41 seq_puts(m, "system"); 42 if (p->subtype == SYSTEM_TYPE_TTY) 43 seq_puts(m, ":/dev/tty"); 44 else if (p->subtype == SYSTEM_TYPE_SYSCONS) 45 seq_puts(m, ":console"); 46 else if (p->subtype == SYSTEM_TYPE_CONSOLE) 47 seq_puts(m, ":vtmaster"); 48 break; 49 case TTY_DRIVER_TYPE_CONSOLE: 50 seq_puts(m, "console"); 51 break; 52 case TTY_DRIVER_TYPE_SERIAL: 53 seq_puts(m, "serial"); 54 break; 55 case TTY_DRIVER_TYPE_PTY: 56 if (p->subtype == PTY_TYPE_MASTER) 57 seq_puts(m, "pty:master"); 58 else if (p->subtype == PTY_TYPE_SLAVE) 59 seq_puts(m, "pty:slave"); 60 else 61 seq_puts(m, "pty"); 62 break; 63 default: 64 seq_printf(m, "type:%d.%d", p->type, p->subtype); 65 } 66 seq_putc(m, '\n'); 67 } 68 69 static int show_tty_driver(struct seq_file *m, void *v) 70 { 71 struct tty_driver *p = list_entry(v, struct tty_driver, tty_drivers); 72 dev_t from = MKDEV(p->major, p->minor_start); 73 dev_t to = from + p->num; 74 75 if (&p->tty_drivers == tty_drivers.next) { 76 /* pseudo-drivers first */ 77 seq_printf(m, "%-20s /dev/%-8s ", "/dev/tty", "tty"); 78 seq_printf(m, "%3d %7d ", TTYAUX_MAJOR, 0); 79 seq_puts(m, "system:/dev/tty\n"); 80 seq_printf(m, "%-20s /dev/%-8s ", "/dev/console", "console"); 81 seq_printf(m, "%3d %7d ", TTYAUX_MAJOR, 1); 82 seq_puts(m, "system:console\n"); 83 #ifdef CONFIG_UNIX98_PTYS 84 seq_printf(m, "%-20s /dev/%-8s ", "/dev/ptmx", "ptmx"); 85 seq_printf(m, "%3d %7d ", TTYAUX_MAJOR, 2); 86 seq_puts(m, "system\n"); 87 #endif 88 #ifdef CONFIG_VT 89 seq_printf(m, "%-20s /dev/%-8s ", "/dev/vc/0", "vc/0"); 90 seq_printf(m, "%3d %7d ", TTY_MAJOR, 0); 91 seq_puts(m, "system:vtmaster\n"); 92 #endif 93 } 94 95 while (MAJOR(from) < MAJOR(to)) { 96 dev_t next = MKDEV(MAJOR(from)+1, 0); 97 show_tty_range(m, p, from, next - from); 98 from = next; 99 } 100 if (from != to) 101 show_tty_range(m, p, from, to - from); 102 return 0; 103 } 104 105 /* iterator */ 106 static void *t_start(struct seq_file *m, loff_t *pos) 107 { 108 mutex_lock(&tty_mutex); 109 return seq_list_start(&tty_drivers, *pos); 110 } 111 112 static void *t_next(struct seq_file *m, void *v, loff_t *pos) 113 { 114 return seq_list_next(v, &tty_drivers, pos); 115 } 116 117 static void t_stop(struct seq_file *m, void *v) 118 { 119 mutex_unlock(&tty_mutex); 120 } 121 122 static const struct seq_operations tty_drivers_op = { 123 .start = t_start, 124 .next = t_next, 125 .stop = t_stop, 126 .show = show_tty_driver 127 }; 128 129 static int tty_drivers_open(struct inode *inode, struct file *file) 130 { 131 return seq_open(file, &tty_drivers_op); 132 } 133 134 static const struct file_operations proc_tty_drivers_operations = { 135 .open = tty_drivers_open, 136 .read = seq_read, 137 .llseek = seq_lseek, 138 .release = seq_release, 139 }; 140 141 /* 142 * This function is called by tty_register_driver() to handle 143 * registering the driver's /proc handler into /proc/tty/driver/<foo> 144 */ 145 void proc_tty_register_driver(struct tty_driver *driver) 146 { 147 struct proc_dir_entry *ent; 148 149 if (!driver->driver_name || driver->proc_entry || 150 !driver->ops->proc_fops) 151 return; 152 153 ent = proc_create_data(driver->driver_name, 0, proc_tty_driver, 154 driver->ops->proc_fops, driver); 155 driver->proc_entry = ent; 156 } 157 158 /* 159 * This function is called by tty_unregister_driver() 160 */ 161 void proc_tty_unregister_driver(struct tty_driver *driver) 162 { 163 struct proc_dir_entry *ent; 164 165 ent = driver->proc_entry; 166 if (!ent) 167 return; 168 169 remove_proc_entry(ent->name, proc_tty_driver); 170 171 driver->proc_entry = NULL; 172 } 173 174 /* 175 * Called by proc_root_init() to initialize the /proc/tty subtree 176 */ 177 void __init proc_tty_init(void) 178 { 179 if (!proc_mkdir("tty", NULL)) 180 return; 181 proc_mkdir("tty/ldisc", NULL); /* Preserved: it's userspace visible */ 182 /* 183 * /proc/tty/driver/serial reveals the exact character counts for 184 * serial links which is just too easy to abuse for inferring 185 * password lengths and inter-keystroke timings during password 186 * entry. 187 */ 188 proc_tty_driver = proc_mkdir_mode("tty/driver", S_IRUSR|S_IXUSR, NULL); 189 proc_create("tty/ldiscs", 0, NULL, &tty_ldiscs_proc_fops); 190 proc_create("tty/drivers", 0, NULL, &proc_tty_drivers_operations); 191 } 192