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Commit | Line | Data |
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c73bd6d4 KT |
1 | /* |
2 | * security/tomoyo/realpath.c | |
3 | * | |
c3ef1500 | 4 | * Pathname calculation functions for TOMOYO. |
c73bd6d4 | 5 | * |
c3ef1500 | 6 | * Copyright (C) 2005-2010 NTT DATA CORPORATION |
c73bd6d4 KT |
7 | */ |
8 | ||
9 | #include <linux/types.h> | |
10 | #include <linux/mount.h> | |
11 | #include <linux/mnt_namespace.h> | |
5ad4e53b | 12 | #include <linux/fs_struct.h> |
67fa4880 | 13 | #include <linux/magic.h> |
5a0e3ad6 | 14 | #include <linux/slab.h> |
c8c57e84 | 15 | #include <net/sock.h> |
c73bd6d4 | 16 | #include "common.h" |
da502956 | 17 | #include "../../fs/internal.h" |
c73bd6d4 KT |
18 | |
19 | /** | |
20 | * tomoyo_encode: Convert binary string to ascii string. | |
21 | * | |
c8c57e84 | 22 | * @str: String in binary format. |
c73bd6d4 | 23 | * |
c8c57e84 TH |
24 | * Returns pointer to @str in ascii format on success, NULL otherwise. |
25 | * | |
26 | * This function uses kzalloc(), so caller must kfree() if this function | |
27 | * didn't return NULL. | |
c73bd6d4 | 28 | */ |
c8c57e84 | 29 | char *tomoyo_encode(const char *str) |
c73bd6d4 | 30 | { |
c8c57e84 TH |
31 | int len = 0; |
32 | const char *p = str; | |
33 | char *cp; | |
34 | char *cp0; | |
c73bd6d4 | 35 | |
c8c57e84 TH |
36 | if (!p) |
37 | return NULL; | |
38 | while (*p) { | |
39 | const unsigned char c = *p++; | |
40 | if (c == '\\') | |
41 | len += 2; | |
42 | else if (c > ' ' && c < 127) | |
43 | len++; | |
44 | else | |
45 | len += 4; | |
46 | } | |
47 | len++; | |
48 | /* Reserve space for appending "/". */ | |
49 | cp = kzalloc(len + 10, GFP_NOFS); | |
50 | if (!cp) | |
51 | return NULL; | |
52 | cp0 = cp; | |
53 | p = str; | |
54 | while (*p) { | |
55 | const unsigned char c = *p++; | |
56 | ||
57 | if (c == '\\') { | |
58 | *cp++ = '\\'; | |
59 | *cp++ = '\\'; | |
60 | } else if (c > ' ' && c < 127) { | |
61 | *cp++ = c; | |
62 | } else { | |
63 | *cp++ = '\\'; | |
64 | *cp++ = (c >> 6) + '0'; | |
65 | *cp++ = ((c >> 3) & 7) + '0'; | |
66 | *cp++ = (c & 7) + '0'; | |
c73bd6d4 | 67 | } |
c73bd6d4 | 68 | } |
c8c57e84 | 69 | return cp0; |
c73bd6d4 KT |
70 | } |
71 | ||
5625f2e3 TH |
72 | /** |
73 | * tomoyo_get_absolute_path - Get the path of a dentry but ignores chroot'ed root. | |
74 | * | |
75 | * @path: Pointer to "struct path". | |
76 | * @buffer: Pointer to buffer to return value in. | |
77 | * @buflen: Sizeof @buffer. | |
78 | * | |
79 | * Returns the buffer on success, an error code otherwise. | |
80 | * | |
81 | * If dentry is a directory, trailing '/' is appended. | |
82 | */ | |
83 | static char *tomoyo_get_absolute_path(struct path *path, char * const buffer, | |
84 | const int buflen) | |
85 | { | |
86 | char *pos = ERR_PTR(-ENOMEM); | |
87 | if (buflen >= 256) { | |
88 | struct path ns_root = { }; | |
89 | /* go to whatever namespace root we are under */ | |
90 | pos = __d_path(path, &ns_root, buffer, buflen - 1); | |
91 | if (!IS_ERR(pos) && *pos == '/' && pos[1]) { | |
92 | struct inode *inode = path->dentry->d_inode; | |
93 | if (inode && S_ISDIR(inode->i_mode)) { | |
94 | buffer[buflen - 2] = '/'; | |
95 | buffer[buflen - 1] = '\0'; | |
96 | } | |
97 | } | |
98 | } | |
99 | return pos; | |
100 | } | |
101 | ||
102 | /** | |
103 | * tomoyo_get_dentry_path - Get the path of a dentry. | |
104 | * | |
105 | * @dentry: Pointer to "struct dentry". | |
106 | * @buffer: Pointer to buffer to return value in. | |
107 | * @buflen: Sizeof @buffer. | |
108 | * | |
109 | * Returns the buffer on success, an error code otherwise. | |
110 | * | |
111 | * If dentry is a directory, trailing '/' is appended. | |
112 | */ | |
113 | static char *tomoyo_get_dentry_path(struct dentry *dentry, char * const buffer, | |
114 | const int buflen) | |
115 | { | |
116 | char *pos = ERR_PTR(-ENOMEM); | |
117 | if (buflen >= 256) { | |
118 | pos = dentry_path_raw(dentry, buffer, buflen - 1); | |
119 | if (!IS_ERR(pos) && *pos == '/' && pos[1]) { | |
120 | struct inode *inode = dentry->d_inode; | |
121 | if (inode && S_ISDIR(inode->i_mode)) { | |
122 | buffer[buflen - 2] = '/'; | |
123 | buffer[buflen - 1] = '\0'; | |
124 | } | |
125 | } | |
126 | } | |
127 | return pos; | |
128 | } | |
129 | ||
130 | /** | |
131 | * tomoyo_get_local_path - Get the path of a dentry. | |
132 | * | |
133 | * @dentry: Pointer to "struct dentry". | |
134 | * @buffer: Pointer to buffer to return value in. | |
135 | * @buflen: Sizeof @buffer. | |
136 | * | |
137 | * Returns the buffer on success, an error code otherwise. | |
138 | */ | |
139 | static char *tomoyo_get_local_path(struct dentry *dentry, char * const buffer, | |
140 | const int buflen) | |
141 | { | |
142 | struct super_block *sb = dentry->d_sb; | |
143 | char *pos = tomoyo_get_dentry_path(dentry, buffer, buflen); | |
144 | if (IS_ERR(pos)) | |
145 | return pos; | |
146 | /* Convert from $PID to self if $PID is current thread. */ | |
147 | if (sb->s_magic == PROC_SUPER_MAGIC && *pos == '/') { | |
148 | char *ep; | |
149 | const pid_t pid = (pid_t) simple_strtoul(pos + 1, &ep, 10); | |
150 | if (*ep == '/' && pid && pid == | |
151 | task_tgid_nr_ns(current, sb->s_fs_info)) { | |
152 | pos = ep - 5; | |
153 | if (pos < buffer) | |
154 | goto out; | |
155 | memmove(pos, "/self", 5); | |
156 | } | |
157 | goto prepend_filesystem_name; | |
158 | } | |
159 | /* Use filesystem name for unnamed devices. */ | |
160 | if (!MAJOR(sb->s_dev)) | |
161 | goto prepend_filesystem_name; | |
162 | { | |
163 | struct inode *inode = sb->s_root->d_inode; | |
164 | /* | |
165 | * Use filesystem name if filesystem does not support rename() | |
166 | * operation. | |
167 | */ | |
168 | if (inode->i_op && !inode->i_op->rename) | |
169 | goto prepend_filesystem_name; | |
170 | } | |
171 | /* Prepend device name. */ | |
172 | { | |
173 | char name[64]; | |
174 | int name_len; | |
175 | const dev_t dev = sb->s_dev; | |
176 | name[sizeof(name) - 1] = '\0'; | |
177 | snprintf(name, sizeof(name) - 1, "dev(%u,%u):", MAJOR(dev), | |
178 | MINOR(dev)); | |
179 | name_len = strlen(name); | |
180 | pos -= name_len; | |
181 | if (pos < buffer) | |
182 | goto out; | |
183 | memmove(pos, name, name_len); | |
184 | return pos; | |
185 | } | |
186 | /* Prepend filesystem name. */ | |
187 | prepend_filesystem_name: | |
188 | { | |
189 | const char *name = sb->s_type->name; | |
190 | const int name_len = strlen(name); | |
191 | pos -= name_len + 1; | |
192 | if (pos < buffer) | |
193 | goto out; | |
194 | memmove(pos, name, name_len); | |
195 | pos[name_len] = ':'; | |
196 | } | |
197 | return pos; | |
198 | out: | |
199 | return ERR_PTR(-ENOMEM); | |
200 | } | |
201 | ||
202 | /** | |
203 | * tomoyo_get_socket_name - Get the name of a socket. | |
204 | * | |
205 | * @path: Pointer to "struct path". | |
206 | * @buffer: Pointer to buffer to return value in. | |
207 | * @buflen: Sizeof @buffer. | |
208 | * | |
209 | * Returns the buffer. | |
210 | */ | |
211 | static char *tomoyo_get_socket_name(struct path *path, char * const buffer, | |
212 | const int buflen) | |
213 | { | |
214 | struct inode *inode = path->dentry->d_inode; | |
215 | struct socket *sock = inode ? SOCKET_I(inode) : NULL; | |
216 | struct sock *sk = sock ? sock->sk : NULL; | |
217 | if (sk) { | |
218 | snprintf(buffer, buflen, "socket:[family=%u:type=%u:" | |
219 | "protocol=%u]", sk->sk_family, sk->sk_type, | |
220 | sk->sk_protocol); | |
221 | } else { | |
222 | snprintf(buffer, buflen, "socket:[unknown]"); | |
223 | } | |
224 | return buffer; | |
225 | } | |
226 | ||
c73bd6d4 | 227 | /** |
c8c57e84 | 228 | * tomoyo_realpath_from_path - Returns realpath(3) of the given pathname but ignores chroot'ed root. |
c73bd6d4 | 229 | * |
c8c57e84 | 230 | * @path: Pointer to "struct path". |
c73bd6d4 | 231 | * |
c8c57e84 | 232 | * Returns the realpath of the given @path on success, NULL otherwise. |
c73bd6d4 KT |
233 | * |
234 | * If dentry is a directory, trailing '/' is appended. | |
235 | * Characters out of 0x20 < c < 0x7F range are converted to | |
236 | * \ooo style octal string. | |
237 | * Character \ is converted to \\ string. | |
c8c57e84 TH |
238 | * |
239 | * These functions use kzalloc(), so the caller must call kfree() | |
240 | * if these functions didn't return NULL. | |
c73bd6d4 | 241 | */ |
c8c57e84 | 242 | char *tomoyo_realpath_from_path(struct path *path) |
c73bd6d4 | 243 | { |
c8c57e84 TH |
244 | char *buf = NULL; |
245 | char *name = NULL; | |
246 | unsigned int buf_len = PAGE_SIZE / 2; | |
c73bd6d4 | 247 | struct dentry *dentry = path->dentry; |
5625f2e3 | 248 | struct super_block *sb; |
c8c57e84 TH |
249 | if (!dentry) |
250 | return NULL; | |
5625f2e3 | 251 | sb = dentry->d_sb; |
c8c57e84 | 252 | while (1) { |
c8c57e84 | 253 | char *pos; |
5625f2e3 | 254 | struct inode *inode; |
c8c57e84 TH |
255 | buf_len <<= 1; |
256 | kfree(buf); | |
257 | buf = kmalloc(buf_len, GFP_NOFS); | |
258 | if (!buf) | |
259 | break; | |
5625f2e3 TH |
260 | /* To make sure that pos is '\0' terminated. */ |
261 | buf[buf_len - 1] = '\0'; | |
c8c57e84 | 262 | /* Get better name for socket. */ |
5625f2e3 TH |
263 | if (sb->s_magic == SOCKFS_MAGIC) { |
264 | pos = tomoyo_get_socket_name(path, buf, buf_len - 1); | |
265 | goto encode; | |
c8c57e84 | 266 | } |
5625f2e3 | 267 | /* For "pipe:[\$]". */ |
c8c57e84 TH |
268 | if (dentry->d_op && dentry->d_op->d_dname) { |
269 | pos = dentry->d_op->d_dname(dentry, buf, buf_len - 1); | |
5625f2e3 | 270 | goto encode; |
c73bd6d4 | 271 | } |
5625f2e3 TH |
272 | inode = sb->s_root->d_inode; |
273 | /* | |
274 | * Get local name for filesystems without rename() operation | |
275 | * or dentry without vfsmount. | |
276 | */ | |
277 | if (!path->mnt || (inode->i_op && !inode->i_op->rename)) | |
278 | pos = tomoyo_get_local_path(path->dentry, buf, | |
279 | buf_len - 1); | |
280 | /* Get absolute name for the rest. */ | |
281 | else | |
282 | pos = tomoyo_get_absolute_path(path, buf, buf_len - 1); | |
283 | encode: | |
c8c57e84 TH |
284 | if (IS_ERR(pos)) |
285 | continue; | |
286 | name = tomoyo_encode(pos); | |
287 | break; | |
c73bd6d4 | 288 | } |
8e2d39a1 | 289 | kfree(buf); |
c8c57e84 TH |
290 | if (!name) |
291 | tomoyo_warn_oom(__func__); | |
c8c57e84 | 292 | return name; |
c73bd6d4 KT |
293 | } |
294 | ||
c73bd6d4 KT |
295 | /** |
296 | * tomoyo_realpath_nofollow - Get realpath of a pathname. | |
297 | * | |
298 | * @pathname: The pathname to solve. | |
299 | * | |
300 | * Returns the realpath of @pathname on success, NULL otherwise. | |
301 | */ | |
302 | char *tomoyo_realpath_nofollow(const char *pathname) | |
303 | { | |
e24977d4 | 304 | struct path path; |
c73bd6d4 | 305 | |
e24977d4 AV |
306 | if (pathname && kern_path(pathname, 0, &path) == 0) { |
307 | char *buf = tomoyo_realpath_from_path(&path); | |
308 | path_put(&path); | |
c73bd6d4 KT |
309 | return buf; |
310 | } | |
311 | return NULL; | |
312 | } |