GNU Linux-libre 4.14.290-gnu1
[releases.git] / fs / proc / proc_tty.c
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 }