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