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