1 // SPDX-License-Identifier: GPL-2.0 <<
2 /* 1 /*
3 * linux/fs/filesystems.c 2 * linux/fs/filesystems.c
4 * 3 *
5 * Copyright (C) 1991, 1992 Linus Torvalds 4 * Copyright (C) 1991, 1992 Linus Torvalds
6 * 5 *
7 * table of configured filesystems 6 * table of configured filesystems
8 */ 7 */
9 8
10 #include <linux/syscalls.h> 9 #include <linux/syscalls.h>
11 #include <linux/fs.h> 10 #include <linux/fs.h>
12 #include <linux/proc_fs.h> 11 #include <linux/proc_fs.h>
13 #include <linux/seq_file.h> 12 #include <linux/seq_file.h>
>> 13 #include <linux/slab.h>
14 #include <linux/kmod.h> 14 #include <linux/kmod.h>
15 #include <linux/init.h> 15 #include <linux/init.h>
16 #include <linux/module.h> 16 #include <linux/module.h>
17 #include <linux/slab.h> !! 17 #include <asm/uaccess.h>
18 #include <linux/uaccess.h> <<
19 #include <linux/fs_parser.h> <<
20 18
21 /* 19 /*
22 * Handling of filesystem drivers list. 20 * Handling of filesystem drivers list.
23 * Rules: 21 * Rules:
24 * Inclusion to/removals from/scanning of 22 * Inclusion to/removals from/scanning of list are protected by spinlock.
25 * During the unload module must call unr 23 * During the unload module must call unregister_filesystem().
26 * We can access the fields of list eleme 24 * We can access the fields of list element if:
27 * 1) spinlock is held or 25 * 1) spinlock is held or
28 * 2) we hold the reference to th 26 * 2) we hold the reference to the module.
29 * The latter can be guaranteed by call o 27 * The latter can be guaranteed by call of try_module_get(); if it
30 * returned 0 we must skip the element, o 28 * returned 0 we must skip the element, otherwise we got the reference.
31 * Once the reference is obtained we can 29 * Once the reference is obtained we can drop the spinlock.
32 */ 30 */
33 31
34 static struct file_system_type *file_systems; 32 static struct file_system_type *file_systems;
35 static DEFINE_RWLOCK(file_systems_lock); 33 static DEFINE_RWLOCK(file_systems_lock);
36 34
37 /* WARNING: This can be used only if we _alrea 35 /* WARNING: This can be used only if we _already_ own a reference */
38 struct file_system_type *get_filesystem(struct !! 36 void get_filesystem(struct file_system_type *fs)
39 { 37 {
40 __module_get(fs->owner); 38 __module_get(fs->owner);
41 return fs; <<
42 } 39 }
43 40
44 void put_filesystem(struct file_system_type *f 41 void put_filesystem(struct file_system_type *fs)
45 { 42 {
46 module_put(fs->owner); 43 module_put(fs->owner);
47 } 44 }
48 45
49 static struct file_system_type **find_filesyst 46 static struct file_system_type **find_filesystem(const char *name, unsigned len)
50 { 47 {
51 struct file_system_type **p; 48 struct file_system_type **p;
52 for (p = &file_systems; *p; p = &(*p)- !! 49 for (p=&file_systems; *p; p=&(*p)->next)
53 if (strncmp((*p)->name, name, !! 50 if (strlen((*p)->name) == len &&
54 !(*p)->name[len]) !! 51 strncmp((*p)->name, name, len) == 0)
55 break; 52 break;
56 return p; 53 return p;
57 } 54 }
58 55
59 /** 56 /**
60 * register_filesystem - register a new f 57 * register_filesystem - register a new filesystem
61 * @fs: the file system structure 58 * @fs: the file system structure
62 * 59 *
63 * Adds the file system passed to the lis 60 * Adds the file system passed to the list of file systems the kernel
64 * is aware of for mount and other syscal 61 * is aware of for mount and other syscalls. Returns 0 on success,
65 * or a negative errno code on an error. 62 * or a negative errno code on an error.
66 * 63 *
67 * The &struct file_system_type that is p 64 * The &struct file_system_type that is passed is linked into the kernel
68 * structures and must not be freed until 65 * structures and must not be freed until the file system has been
69 * unregistered. 66 * unregistered.
70 */ 67 */
71 68
72 int register_filesystem(struct file_system_typ 69 int register_filesystem(struct file_system_type * fs)
73 { 70 {
74 int res = 0; 71 int res = 0;
75 struct file_system_type ** p; 72 struct file_system_type ** p;
76 73
77 if (fs->parameters && <<
78 !fs_validate_description(fs->name, <<
79 return -EINVAL; <<
80 <<
81 BUG_ON(strchr(fs->name, '.')); 74 BUG_ON(strchr(fs->name, '.'));
82 if (fs->next) 75 if (fs->next)
83 return -EBUSY; 76 return -EBUSY;
>> 77 INIT_LIST_HEAD(&fs->fs_supers);
84 write_lock(&file_systems_lock); 78 write_lock(&file_systems_lock);
85 p = find_filesystem(fs->name, strlen(f 79 p = find_filesystem(fs->name, strlen(fs->name));
86 if (*p) 80 if (*p)
87 res = -EBUSY; 81 res = -EBUSY;
88 else 82 else
89 *p = fs; 83 *p = fs;
90 write_unlock(&file_systems_lock); 84 write_unlock(&file_systems_lock);
91 return res; 85 return res;
92 } 86 }
93 87
94 EXPORT_SYMBOL(register_filesystem); 88 EXPORT_SYMBOL(register_filesystem);
95 89
96 /** 90 /**
97 * unregister_filesystem - unregister a f 91 * unregister_filesystem - unregister a file system
98 * @fs: filesystem to unregister 92 * @fs: filesystem to unregister
99 * 93 *
100 * Remove a file system that was previous 94 * Remove a file system that was previously successfully registered
101 * with the kernel. An error is returned 95 * with the kernel. An error is returned if the file system is not found.
102 * Zero is returned on a success. 96 * Zero is returned on a success.
103 * 97 *
104 * Once this function has returned the &s 98 * Once this function has returned the &struct file_system_type structure
105 * may be freed or reused. 99 * may be freed or reused.
106 */ 100 */
107 101
108 int unregister_filesystem(struct file_system_t 102 int unregister_filesystem(struct file_system_type * fs)
109 { 103 {
110 struct file_system_type ** tmp; 104 struct file_system_type ** tmp;
111 105
112 write_lock(&file_systems_lock); 106 write_lock(&file_systems_lock);
113 tmp = &file_systems; 107 tmp = &file_systems;
114 while (*tmp) { 108 while (*tmp) {
115 if (fs == *tmp) { 109 if (fs == *tmp) {
116 *tmp = fs->next; 110 *tmp = fs->next;
117 fs->next = NULL; 111 fs->next = NULL;
118 write_unlock(&file_sys 112 write_unlock(&file_systems_lock);
119 synchronize_rcu(); <<
120 return 0; 113 return 0;
121 } 114 }
122 tmp = &(*tmp)->next; 115 tmp = &(*tmp)->next;
123 } 116 }
124 write_unlock(&file_systems_lock); 117 write_unlock(&file_systems_lock);
125 <<
126 return -EINVAL; 118 return -EINVAL;
127 } 119 }
128 120
129 EXPORT_SYMBOL(unregister_filesystem); 121 EXPORT_SYMBOL(unregister_filesystem);
130 122
131 #ifdef CONFIG_SYSFS_SYSCALL <<
132 static int fs_index(const char __user * __name 123 static int fs_index(const char __user * __name)
133 { 124 {
134 struct file_system_type * tmp; 125 struct file_system_type * tmp;
135 struct filename *name; !! 126 char * name;
136 int err, index; 127 int err, index;
137 128
138 name = getname(__name); 129 name = getname(__name);
139 err = PTR_ERR(name); 130 err = PTR_ERR(name);
140 if (IS_ERR(name)) 131 if (IS_ERR(name))
141 return err; 132 return err;
142 133
143 err = -EINVAL; 134 err = -EINVAL;
144 read_lock(&file_systems_lock); 135 read_lock(&file_systems_lock);
145 for (tmp=file_systems, index=0 ; tmp ; 136 for (tmp=file_systems, index=0 ; tmp ; tmp=tmp->next, index++) {
146 if (strcmp(tmp->name, name->na !! 137 if (strcmp(tmp->name,name) == 0) {
147 err = index; 138 err = index;
148 break; 139 break;
149 } 140 }
150 } 141 }
151 read_unlock(&file_systems_lock); 142 read_unlock(&file_systems_lock);
152 putname(name); 143 putname(name);
153 return err; 144 return err;
154 } 145 }
155 146
156 static int fs_name(unsigned int index, char __ 147 static int fs_name(unsigned int index, char __user * buf)
157 { 148 {
158 struct file_system_type * tmp; 149 struct file_system_type * tmp;
159 int len, res; 150 int len, res;
160 151
161 read_lock(&file_systems_lock); 152 read_lock(&file_systems_lock);
162 for (tmp = file_systems; tmp; tmp = tm 153 for (tmp = file_systems; tmp; tmp = tmp->next, index--)
163 if (index <= 0 && try_module_g 154 if (index <= 0 && try_module_get(tmp->owner))
164 break; 155 break;
165 read_unlock(&file_systems_lock); 156 read_unlock(&file_systems_lock);
166 if (!tmp) 157 if (!tmp)
167 return -EINVAL; 158 return -EINVAL;
168 159
169 /* OK, we got the reference, so we can 160 /* OK, we got the reference, so we can safely block */
170 len = strlen(tmp->name) + 1; 161 len = strlen(tmp->name) + 1;
171 res = copy_to_user(buf, tmp->name, len 162 res = copy_to_user(buf, tmp->name, len) ? -EFAULT : 0;
172 put_filesystem(tmp); 163 put_filesystem(tmp);
173 return res; 164 return res;
174 } 165 }
175 166
176 static int fs_maxindex(void) 167 static int fs_maxindex(void)
177 { 168 {
178 struct file_system_type * tmp; 169 struct file_system_type * tmp;
179 int index; 170 int index;
180 171
181 read_lock(&file_systems_lock); 172 read_lock(&file_systems_lock);
182 for (tmp = file_systems, index = 0 ; t 173 for (tmp = file_systems, index = 0 ; tmp ; tmp = tmp->next, index++)
183 ; 174 ;
184 read_unlock(&file_systems_lock); 175 read_unlock(&file_systems_lock);
185 return index; 176 return index;
186 } 177 }
187 178
188 /* 179 /*
189 * Whee.. Weird sysv syscall. 180 * Whee.. Weird sysv syscall.
190 */ 181 */
191 SYSCALL_DEFINE3(sysfs, int, option, unsigned l 182 SYSCALL_DEFINE3(sysfs, int, option, unsigned long, arg1, unsigned long, arg2)
192 { 183 {
193 int retval = -EINVAL; 184 int retval = -EINVAL;
194 185
195 switch (option) { 186 switch (option) {
196 case 1: 187 case 1:
197 retval = fs_index((con 188 retval = fs_index((const char __user *) arg1);
198 break; 189 break;
199 190
200 case 2: 191 case 2:
201 retval = fs_name(arg1, 192 retval = fs_name(arg1, (char __user *) arg2);
202 break; 193 break;
203 194
204 case 3: 195 case 3:
205 retval = fs_maxindex() 196 retval = fs_maxindex();
206 break; 197 break;
207 } 198 }
208 return retval; 199 return retval;
209 } 200 }
210 #endif <<
211 201
212 int __init list_bdev_fs_names(char *buf, size_ !! 202 int __init get_filesystem_list(char *buf)
213 { 203 {
214 struct file_system_type *p; !! 204 int len = 0;
215 size_t len; !! 205 struct file_system_type * tmp;
216 int count = 0; <<
217 206
218 read_lock(&file_systems_lock); 207 read_lock(&file_systems_lock);
219 for (p = file_systems; p; p = p->next) !! 208 tmp = file_systems;
220 if (!(p->fs_flags & FS_REQUIRE !! 209 while (tmp && len < PAGE_SIZE - 80) {
221 continue; !! 210 len += sprintf(buf+len, "%s\t%s\n",
222 len = strlen(p->name) + 1; !! 211 (tmp->fs_flags & FS_REQUIRES_DEV) ? "" : "nodev",
223 if (len > size) { !! 212 tmp->name);
224 pr_warn("%s: truncatin !! 213 tmp = tmp->next;
225 break; <<
226 } <<
227 memcpy(buf, p->name, len); <<
228 buf += len; <<
229 size -= len; <<
230 count++; <<
231 } 214 }
232 read_unlock(&file_systems_lock); 215 read_unlock(&file_systems_lock);
233 return count; !! 216 return len;
234 } 217 }
235 218
236 #ifdef CONFIG_PROC_FS 219 #ifdef CONFIG_PROC_FS
237 static int filesystems_proc_show(struct seq_fi 220 static int filesystems_proc_show(struct seq_file *m, void *v)
238 { 221 {
239 struct file_system_type * tmp; 222 struct file_system_type * tmp;
240 223
241 read_lock(&file_systems_lock); 224 read_lock(&file_systems_lock);
242 tmp = file_systems; 225 tmp = file_systems;
243 while (tmp) { 226 while (tmp) {
244 seq_printf(m, "%s\t%s\n", 227 seq_printf(m, "%s\t%s\n",
245 (tmp->fs_flags & FS_RE 228 (tmp->fs_flags & FS_REQUIRES_DEV) ? "" : "nodev",
246 tmp->name); 229 tmp->name);
247 tmp = tmp->next; 230 tmp = tmp->next;
248 } 231 }
249 read_unlock(&file_systems_lock); 232 read_unlock(&file_systems_lock);
250 return 0; 233 return 0;
251 } 234 }
252 235
>> 236 static int filesystems_proc_open(struct inode *inode, struct file *file)
>> 237 {
>> 238 return single_open(file, filesystems_proc_show, NULL);
>> 239 }
>> 240
>> 241 static const struct file_operations filesystems_proc_fops = {
>> 242 .open = filesystems_proc_open,
>> 243 .read = seq_read,
>> 244 .llseek = seq_lseek,
>> 245 .release = single_release,
>> 246 };
>> 247
253 static int __init proc_filesystems_init(void) 248 static int __init proc_filesystems_init(void)
254 { 249 {
255 proc_create_single("filesystems", 0, N !! 250 proc_create("filesystems", 0, NULL, &filesystems_proc_fops);
256 return 0; 251 return 0;
257 } 252 }
258 module_init(proc_filesystems_init); 253 module_init(proc_filesystems_init);
259 #endif 254 #endif
260 255
261 static struct file_system_type *__get_fs_type( 256 static struct file_system_type *__get_fs_type(const char *name, int len)
262 { 257 {
263 struct file_system_type *fs; 258 struct file_system_type *fs;
264 259
265 read_lock(&file_systems_lock); 260 read_lock(&file_systems_lock);
266 fs = *(find_filesystem(name, len)); 261 fs = *(find_filesystem(name, len));
267 if (fs && !try_module_get(fs->owner)) 262 if (fs && !try_module_get(fs->owner))
268 fs = NULL; 263 fs = NULL;
269 read_unlock(&file_systems_lock); 264 read_unlock(&file_systems_lock);
270 return fs; 265 return fs;
271 } 266 }
272 267
273 struct file_system_type *get_fs_type(const cha 268 struct file_system_type *get_fs_type(const char *name)
274 { 269 {
275 struct file_system_type *fs; 270 struct file_system_type *fs;
276 const char *dot = strchr(name, '.'); 271 const char *dot = strchr(name, '.');
277 int len = dot ? dot - name : strlen(na 272 int len = dot ? dot - name : strlen(name);
278 273
279 fs = __get_fs_type(name, len); 274 fs = __get_fs_type(name, len);
280 if (!fs && (request_module("fs-%.*s", !! 275 if (!fs && (request_module("%.*s", len, name) == 0))
281 fs = __get_fs_type(name, len); 276 fs = __get_fs_type(name, len);
282 if (!fs) <<
283 pr_warn_once("request_ <<
284 len, name <<
285 } <<
286 277
287 if (dot && fs && !(fs->fs_flags & FS_H 278 if (dot && fs && !(fs->fs_flags & FS_HAS_SUBTYPE)) {
288 put_filesystem(fs); 279 put_filesystem(fs);
289 fs = NULL; 280 fs = NULL;
290 } 281 }
291 return fs; 282 return fs;
292 } 283 }
293 284
294 EXPORT_SYMBOL(get_fs_type); 285 EXPORT_SYMBOL(get_fs_type);
295 286
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