1
2
3
4
5
6
7
8#include <linux/module.h>
9#include <linux/time.h>
10#include <linux/mm.h>
11#include <linux/string.h>
12#include <linux/capability.h>
13#include <linux/fsnotify.h>
14#include <linux/fcntl.h>
15#include <linux/security.h>
16
17
18
19
20
21
22
23
24
25
26
27
28
29int inode_change_ok(const struct inode *inode, struct iattr *attr)
30{
31 unsigned int ia_valid = attr->ia_valid;
32
33
34
35
36
37 if (ia_valid & ATTR_SIZE) {
38 int error = inode_newsize_ok(inode, attr->ia_size);
39 if (error)
40 return error;
41 }
42
43
44 if (ia_valid & ATTR_FORCE)
45 return 0;
46
47
48 if ((ia_valid & ATTR_UID) &&
49 (current_fsuid() != inode->i_uid ||
50 attr->ia_uid != inode->i_uid) && !capable(CAP_CHOWN))
51 return -EPERM;
52
53
54 if ((ia_valid & ATTR_GID) &&
55 (current_fsuid() != inode->i_uid ||
56 (!in_group_p(attr->ia_gid) && attr->ia_gid != inode->i_gid)) &&
57 !capable(CAP_CHOWN))
58 return -EPERM;
59
60
61 if (ia_valid & ATTR_MODE) {
62 if (!is_owner_or_cap(inode))
63 return -EPERM;
64
65 if (!in_group_p((ia_valid & ATTR_GID) ? attr->ia_gid :
66 inode->i_gid) && !capable(CAP_FSETID))
67 attr->ia_mode &= ~S_ISGID;
68 }
69
70
71 if (ia_valid & (ATTR_MTIME_SET | ATTR_ATIME_SET | ATTR_TIMES_SET)) {
72 if (!is_owner_or_cap(inode))
73 return -EPERM;
74 }
75
76 return 0;
77}
78EXPORT_SYMBOL(inode_change_ok);
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95int inode_newsize_ok(const struct inode *inode, loff_t offset)
96{
97 if (inode->i_size < offset) {
98 unsigned long limit;
99
100 limit = rlimit(RLIMIT_FSIZE);
101 if (limit != RLIM_INFINITY && offset > limit)
102 goto out_sig;
103 if (offset > inode->i_sb->s_maxbytes)
104 goto out_big;
105 } else {
106
107
108
109
110
111 if (IS_SWAPFILE(inode))
112 return -ETXTBSY;
113 }
114
115 return 0;
116out_sig:
117 send_sig(SIGXFSZ, current, 0);
118out_big:
119 return -EFBIG;
120}
121EXPORT_SYMBOL(inode_newsize_ok);
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138void setattr_copy(struct inode *inode, const struct iattr *attr)
139{
140 unsigned int ia_valid = attr->ia_valid;
141
142 if (ia_valid & ATTR_UID)
143 inode->i_uid = attr->ia_uid;
144 if (ia_valid & ATTR_GID)
145 inode->i_gid = attr->ia_gid;
146 if (ia_valid & ATTR_ATIME)
147 inode->i_atime = timespec_trunc(attr->ia_atime,
148 inode->i_sb->s_time_gran);
149 if (ia_valid & ATTR_MTIME)
150 inode->i_mtime = timespec_trunc(attr->ia_mtime,
151 inode->i_sb->s_time_gran);
152 if (ia_valid & ATTR_CTIME)
153 inode->i_ctime = timespec_trunc(attr->ia_ctime,
154 inode->i_sb->s_time_gran);
155 if (ia_valid & ATTR_MODE) {
156 umode_t mode = attr->ia_mode;
157
158 if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID))
159 mode &= ~S_ISGID;
160 inode->i_mode = mode;
161 }
162}
163EXPORT_SYMBOL(setattr_copy);
164
165int notify_change(struct dentry * dentry, struct iattr * attr)
166{
167 struct inode *inode = dentry->d_inode;
168 mode_t mode = inode->i_mode;
169 int error;
170 struct timespec now;
171 unsigned int ia_valid = attr->ia_valid;
172
173 if (ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID | ATTR_TIMES_SET)) {
174 if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
175 return -EPERM;
176 }
177
178 now = current_fs_time(inode->i_sb);
179
180 attr->ia_ctime = now;
181 if (!(ia_valid & ATTR_ATIME_SET))
182 attr->ia_atime = now;
183 if (!(ia_valid & ATTR_MTIME_SET))
184 attr->ia_mtime = now;
185 if (ia_valid & ATTR_KILL_PRIV) {
186 attr->ia_valid &= ~ATTR_KILL_PRIV;
187 ia_valid &= ~ATTR_KILL_PRIV;
188 error = security_inode_need_killpriv(dentry);
189 if (error > 0)
190 error = security_inode_killpriv(dentry);
191 if (error)
192 return error;
193 }
194
195
196
197
198
199
200
201
202 if ((ia_valid & (ATTR_KILL_SUID|ATTR_KILL_SGID)) &&
203 (ia_valid & ATTR_MODE))
204 BUG();
205
206 if (ia_valid & ATTR_KILL_SUID) {
207 if (mode & S_ISUID) {
208 ia_valid = attr->ia_valid |= ATTR_MODE;
209 attr->ia_mode = (inode->i_mode & ~S_ISUID);
210 }
211 }
212 if (ia_valid & ATTR_KILL_SGID) {
213 if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
214 if (!(ia_valid & ATTR_MODE)) {
215 ia_valid = attr->ia_valid |= ATTR_MODE;
216 attr->ia_mode = inode->i_mode;
217 }
218 attr->ia_mode &= ~S_ISGID;
219 }
220 }
221 if (!(attr->ia_valid & ~(ATTR_KILL_SUID | ATTR_KILL_SGID)))
222 return 0;
223
224 error = security_inode_setattr(dentry, attr);
225 if (error)
226 return error;
227
228 if (ia_valid & ATTR_SIZE)
229 down_write(&dentry->d_inode->i_alloc_sem);
230
231 if (inode->i_op->setattr)
232 error = inode->i_op->setattr(dentry, attr);
233 else
234 error = simple_setattr(dentry, attr);
235
236 if (ia_valid & ATTR_SIZE)
237 up_write(&dentry->d_inode->i_alloc_sem);
238
239 if (!error)
240 fsnotify_change(dentry, ia_valid);
241
242 return error;
243}
244
245EXPORT_SYMBOL(notify_change);
246