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 | static void show_tty_range(struct seq_file *m, struct tty_driver *p, |
27 | dev_t from, int num) |
28 | { |
29 | seq_printf(m, fmt: "%-20s " , p->driver_name ? p->driver_name : "unknown" ); |
30 | seq_printf(m, fmt: "/dev/%-8s " , p->name); |
31 | if (p->num > 1) { |
32 | seq_printf(m, fmt: "%3d %d-%d " , MAJOR(from), MINOR(from), |
33 | MINOR(from) + num - 1); |
34 | } else { |
35 | seq_printf(m, fmt: "%3d %7d " , MAJOR(from), MINOR(from)); |
36 | } |
37 | switch (p->type) { |
38 | case TTY_DRIVER_TYPE_SYSTEM: |
39 | seq_puts(m, s: "system" ); |
40 | if (p->subtype == SYSTEM_TYPE_TTY) |
41 | seq_puts(m, s: ":/dev/tty" ); |
42 | else if (p->subtype == SYSTEM_TYPE_SYSCONS) |
43 | seq_puts(m, s: ":console" ); |
44 | else if (p->subtype == SYSTEM_TYPE_CONSOLE) |
45 | seq_puts(m, s: ":vtmaster" ); |
46 | break; |
47 | case TTY_DRIVER_TYPE_CONSOLE: |
48 | seq_puts(m, s: "console" ); |
49 | break; |
50 | case TTY_DRIVER_TYPE_SERIAL: |
51 | seq_puts(m, s: "serial" ); |
52 | break; |
53 | case TTY_DRIVER_TYPE_PTY: |
54 | if (p->subtype == PTY_TYPE_MASTER) |
55 | seq_puts(m, s: "pty:master" ); |
56 | else if (p->subtype == PTY_TYPE_SLAVE) |
57 | seq_puts(m, s: "pty:slave" ); |
58 | else |
59 | seq_puts(m, s: "pty" ); |
60 | break; |
61 | default: |
62 | seq_printf(m, fmt: "type:%d.%d" , p->type, p->subtype); |
63 | } |
64 | seq_putc(m, c: '\n'); |
65 | } |
66 | |
67 | static int show_tty_driver(struct seq_file *m, void *v) |
68 | { |
69 | struct tty_driver *p = list_entry(v, struct tty_driver, tty_drivers); |
70 | dev_t from = MKDEV(p->major, p->minor_start); |
71 | dev_t to = from + p->num; |
72 | |
73 | if (&p->tty_drivers == tty_drivers.next) { |
74 | /* pseudo-drivers first */ |
75 | seq_printf(m, fmt: "%-20s /dev/%-8s " , "/dev/tty" , "tty" ); |
76 | seq_printf(m, fmt: "%3d %7d " , TTYAUX_MAJOR, 0); |
77 | seq_puts(m, s: "system:/dev/tty\n" ); |
78 | seq_printf(m, fmt: "%-20s /dev/%-8s " , "/dev/console" , "console" ); |
79 | seq_printf(m, fmt: "%3d %7d " , TTYAUX_MAJOR, 1); |
80 | seq_puts(m, s: "system:console\n" ); |
81 | #ifdef CONFIG_UNIX98_PTYS |
82 | seq_printf(m, fmt: "%-20s /dev/%-8s " , "/dev/ptmx" , "ptmx" ); |
83 | seq_printf(m, fmt: "%3d %7d " , TTYAUX_MAJOR, 2); |
84 | seq_puts(m, s: "system\n" ); |
85 | #endif |
86 | #ifdef CONFIG_VT |
87 | seq_printf(m, fmt: "%-20s /dev/%-8s " , "/dev/vc/0" , "vc/0" ); |
88 | seq_printf(m, fmt: "%3d %7d " , TTY_MAJOR, 0); |
89 | seq_puts(m, s: "system:vtmaster\n" ); |
90 | #endif |
91 | } |
92 | |
93 | while (MAJOR(from) < MAJOR(to)) { |
94 | dev_t next = MKDEV(MAJOR(from)+1, 0); |
95 | show_tty_range(m, p, from, num: next - from); |
96 | from = next; |
97 | } |
98 | if (from != to) |
99 | show_tty_range(m, p, from, num: to - from); |
100 | return 0; |
101 | } |
102 | |
103 | /* iterator */ |
104 | static void *t_start(struct seq_file *m, loff_t *pos) |
105 | { |
106 | mutex_lock(&tty_mutex); |
107 | return seq_list_start(head: &tty_drivers, pos: *pos); |
108 | } |
109 | |
110 | static void *t_next(struct seq_file *m, void *v, loff_t *pos) |
111 | { |
112 | return seq_list_next(v, head: &tty_drivers, ppos: pos); |
113 | } |
114 | |
115 | static void t_stop(struct seq_file *m, void *v) |
116 | { |
117 | mutex_unlock(lock: &tty_mutex); |
118 | } |
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 | void proc_tty_register_driver(struct tty_driver *driver) |
132 | { |
133 | struct proc_dir_entry *ent; |
134 | |
135 | if (!driver->driver_name || driver->proc_entry || |
136 | !driver->ops->proc_show) |
137 | return; |
138 | |
139 | ent = proc_create_single_data(name: driver->driver_name, mode: 0, parent: proc_tty_driver, |
140 | show: driver->ops->proc_show, data: driver); |
141 | driver->proc_entry = ent; |
142 | } |
143 | |
144 | /* |
145 | * This function is called by tty_unregister_driver() |
146 | */ |
147 | void proc_tty_unregister_driver(struct tty_driver *driver) |
148 | { |
149 | struct proc_dir_entry *ent; |
150 | |
151 | ent = driver->proc_entry; |
152 | if (!ent) |
153 | return; |
154 | |
155 | remove_proc_entry(ent->name, proc_tty_driver); |
156 | |
157 | driver->proc_entry = NULL; |
158 | } |
159 | |
160 | /* |
161 | * Called by proc_root_init() to initialize the /proc/tty subtree |
162 | */ |
163 | void __init proc_tty_init(void) |
164 | { |
165 | if (!proc_mkdir("tty" , NULL)) |
166 | return; |
167 | 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 | proc_tty_driver = proc_mkdir_mode("tty/driver" , S_IRUSR|S_IXUSR, NULL); |
175 | proc_create_seq("tty/ldiscs" , 0, NULL, &tty_ldiscs_seq_ops); |
176 | proc_create_seq("tty/drivers" , 0, NULL, &tty_drivers_op); |
177 | } |
178 | |