1 /*
2 * proc_tty.c -- handles /proc/tty
3 *
4 * Copyright 1997, Theodore Ts'o
5 */
6
7 #include <asm/uaccess.h>
8
9 #include <linux/init.h>
10 #include <linux/errno.h>
11 #include <linux/sched.h>
12 #include <linux/proc_fs.h>
13 #include <linux/stat.h>
14 #include <linux/tty.h>
15 #include <asm/bitops.h>
16
17 extern struct tty_driver *tty_drivers; /* linked list of tty drivers */
18
19 static int tty_drivers_read_proc(char *page, char **start, off_t off,
20 int count, int *eof, void *data);
21 static int tty_ldiscs_read_proc(char *page, char **start, off_t off,
22 int count, int *eof, void *data);
23
24 /*
25 * The /proc/tty directory inodes...
26 */
27 static struct proc_dir_entry *proc_tty_ldisc, *proc_tty_driver;
28
29 /*
30 * This is the handler for /proc/tty/drivers
31 */
tty_drivers_read_proc(char * page,char ** start,off_t off,int count,int * eof,void * data)32 static int tty_drivers_read_proc(char *page, char **start, off_t off,
33 int count, int *eof, void *data)
34 {
35 int len = 0;
36 off_t begin = 0;
37 struct tty_driver *p;
38 char range[20], deftype[20];
39 char *type;
40
41 for (p = tty_drivers; p; p = p->next) {
42 if (p->num > 1)
43 sprintf(range, "%d-%d", p->minor_start,
44 p->minor_start + p->num - 1);
45 else
46 sprintf(range, "%d", p->minor_start);
47 switch (p->type) {
48 case TTY_DRIVER_TYPE_SYSTEM:
49 if (p->subtype == SYSTEM_TYPE_TTY)
50 type = "system:/dev/tty";
51 else if (p->subtype == SYSTEM_TYPE_SYSCONS)
52 type = "system:console";
53 else if (p->subtype == SYSTEM_TYPE_CONSOLE)
54 type = "system:vtmaster";
55 else
56 type = "system";
57 break;
58 case TTY_DRIVER_TYPE_CONSOLE:
59 type = "console";
60 break;
61 case TTY_DRIVER_TYPE_SERIAL:
62 if (p->subtype == 2)
63 type = "serial:callout";
64 else
65 type = "serial";
66 break;
67 case TTY_DRIVER_TYPE_PTY:
68 if (p->subtype == PTY_TYPE_MASTER)
69 type = "pty:master";
70 else if (p->subtype == PTY_TYPE_SLAVE)
71 type = "pty:slave";
72 else
73 type = "pty";
74 break;
75 default:
76 sprintf(deftype, "type:%d.%d", p->type, p->subtype);
77 type = deftype;
78 break;
79 }
80 len += sprintf(page+len, "%-20s /dev/%-8s %3d %7s %s\n",
81 p->driver_name ? p->driver_name : "unknown",
82 p->name, p->major, range, type);
83 if (len+begin > off+count)
84 break;
85 if (len+begin < off) {
86 begin += len;
87 len = 0;
88 }
89 }
90 if (!p)
91 *eof = 1;
92 if (off >= len+begin)
93 return 0;
94 *start = page + (off-begin);
95 return ((count < begin+len-off) ? count : begin+len-off);
96 }
97
98 /*
99 * This is the handler for /proc/tty/ldiscs
100 */
tty_ldiscs_read_proc(char * page,char ** start,off_t off,int count,int * eof,void * data)101 static int tty_ldiscs_read_proc(char *page, char **start, off_t off,
102 int count, int *eof, void *data)
103 {
104 int i;
105 int len = 0;
106 off_t begin = 0;
107 struct tty_ldisc *ld;
108
109 for (i=0; i < NR_LDISCS; i++) {
110 ld = tty_ldisc_get(i);
111 if (ld == NULL)
112 continue;
113 len += sprintf(page+len, "%-10s %2d\n",
114 ld->name ? ld->name : "???", i);
115 tty_ldisc_put(i);
116 if (len+begin > off+count)
117 break;
118 if (len+begin < off) {
119 begin += len;
120 len = 0;
121 }
122 }
123 if (i >= NR_LDISCS)
124 *eof = 1;
125 if (off >= len+begin)
126 return 0;
127 *start = page + (off-begin);
128 return ((count < begin+len-off) ? count : begin+len-off);
129 }
130
131 /*
132 * This function is called by tty_register_driver() to handle
133 * registering the driver's /proc handler into /proc/tty/driver/<foo>
134 */
proc_tty_register_driver(struct tty_driver * driver)135 void proc_tty_register_driver(struct tty_driver *driver)
136 {
137 struct proc_dir_entry *ent;
138
139 if ((!driver->read_proc && !driver->write_proc) ||
140 !driver->driver_name ||
141 driver->proc_entry)
142 return;
143
144 ent = create_proc_entry(driver->driver_name, 0, proc_tty_driver);
145 if (!ent)
146 return;
147 ent->read_proc = driver->read_proc;
148 ent->write_proc = driver->write_proc;
149 ent->data = driver;
150
151 driver->proc_entry = ent;
152 }
153
154 /*
155 * This function is called by tty_unregister_driver()
156 */
proc_tty_unregister_driver(struct tty_driver * driver)157 void proc_tty_unregister_driver(struct tty_driver *driver)
158 {
159 struct proc_dir_entry *ent;
160
161 ent = driver->proc_entry;
162 if (!ent)
163 return;
164
165 remove_proc_entry(driver->driver_name, proc_tty_driver);
166
167 driver->proc_entry = 0;
168 }
169
170 /*
171 * Called by proc_root_init() to initialize the /proc/tty subtree
172 */
proc_tty_init(void)173 void __init proc_tty_init(void)
174 {
175 if (!proc_mkdir("tty", 0))
176 return;
177 proc_tty_ldisc = proc_mkdir("tty/ldisc", 0);
178 /*
179 * /proc/tty/driver/serial reveals the exact character counts for
180 * serial links which is just too easy to abuse for inferring
181 * password lengths and inter-keystroke timings during password
182 * entry.
183 */
184 proc_tty_driver = proc_mkdir_mode("tty/driver", S_IRUSR | S_IXUSR, 0);
185
186 create_proc_read_entry("tty/ldiscs", 0, 0, tty_ldiscs_read_proc,NULL);
187 create_proc_read_entry("tty/drivers", 0, 0, tty_drivers_read_proc,NULL);
188 }
189