1 /*
2 * linux/fs/attr.c
3 *
4 * Copyright (C) 1991, 1992 Linus Torvalds
5 * changes by Thomas Schoebel-Theuer
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/quotaops.h>
16 #include <linux/security.h>
17
18 /* Taken over from the old code... */
19
20 /* POSIX UID/GID verification for setting inode attributes. */
21 int inode_change_ok(struct inode *inode, struct iattr *attr)
22 {
23 int retval = -EPERM;
24 unsigned int ia_valid = attr->ia_valid;
25
26 /* If force is set do it anyway. */
27 if (ia_valid & ATTR_FORCE)
28 goto fine;
29
30 /* Make sure a caller can chown. */
31 if ((ia_valid & ATTR_UID) &&
32 (current_fsuid() != inode->i_uid ||
33 attr->ia_uid != inode->i_uid) && !capable(CAP_CHOWN))
34 goto error;
35
36 /* Make sure caller can chgrp. */
37 if ((ia_valid & ATTR_GID) &&
38 (current_fsuid() != inode->i_uid ||
39 (!in_group_p(attr->ia_gid) && attr->ia_gid != inode->i_gid)) &&
40 !capable(CAP_CHOWN))
41 goto error;
42
43 /* Make sure a caller can chmod. */
44 if (ia_valid & ATTR_MODE) {
45 if (!is_owner_or_cap(inode))
46 goto error;
47 /* Also check the setgid bit! */
48 if (!in_group_p((ia_valid & ATTR_GID) ? attr->ia_gid :
49 inode->i_gid) && !capable(CAP_FSETID))
50 attr->ia_mode &= ~S_ISGID;
51 }
52
53 /* Check for setting the inode time. */
54 if (ia_valid & (ATTR_MTIME_SET | ATTR_ATIME_SET | ATTR_TIMES_SET)) {
55 if (!is_owner_or_cap(inode))
56 goto error;
57 }
58 fine:
59 retval = 0;
60 error:
61 return retval;
62 }
63
64 EXPORT_SYMBOL(inode_change_ok);
65
66 int inode_setattr(struct inode * inode, struct iattr * attr)
67 {
68 unsigned int ia_valid = attr->ia_valid;
69
70 if (ia_valid & ATTR_SIZE &&
71 attr->ia_size != i_size_read(inode)) {
72 int error = vmtruncate(inode, attr->ia_size);
73 if (error)
74 return error;
75 }
76
77 if (ia_valid & ATTR_UID)
78 inode->i_uid = attr->ia_uid;
79 if (ia_valid & ATTR_GID)
80 inode->i_gid = attr->ia_gid;
81 if (ia_valid & ATTR_ATIME)
82 inode->i_atime = timespec_trunc(attr->ia_atime,
83 inode->i_sb->s_time_gran);
84 if (ia_valid & ATTR_MTIME)
85 inode->i_mtime = timespec_trunc(attr->ia_mtime,
86 inode->i_sb->s_time_gran);
87 if (ia_valid & ATTR_CTIME)
88 inode->i_ctime = timespec_trunc(attr->ia_ctime,
89 inode->i_sb->s_time_gran);
90 if (ia_valid & ATTR_MODE) {
91 umode_t mode = attr->ia_mode;
92
93 if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID))
94 mode &= ~S_ISGID;
95 inode->i_mode = mode;
96 }
97 mark_inode_dirty(inode);
98
99 return 0;
100 }
101 EXPORT_SYMBOL(inode_setattr);
102
103 int notify_change(struct dentry * dentry, struct iattr * attr)
104 {
105 struct inode *inode = dentry->d_inode;
106 mode_t mode = inode->i_mode;
107 int error;
108 struct timespec now;
109 unsigned int ia_valid = attr->ia_valid;
110
111 if (ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID | ATTR_TIMES_SET)) {
112 if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
113 return -EPERM;
114 }
115
116 now = current_fs_time(inode->i_sb);
117
118 attr->ia_ctime = now;
119 if (!(ia_valid & ATTR_ATIME_SET))
120 attr->ia_atime = now;
121 if (!(ia_valid & ATTR_MTIME_SET))
122 attr->ia_mtime = now;
123 if (ia_valid & ATTR_KILL_PRIV) {
124 attr->ia_valid &= ~ATTR_KILL_PRIV;
125 ia_valid &= ~ATTR_KILL_PRIV;
126 error = security_inode_need_killpriv(dentry);
127 if (error > 0)
128 error = security_inode_killpriv(dentry);
129 if (error)
130 return error;
131 }
132
133 /*
134 * We now pass ATTR_KILL_S*ID to the lower level setattr function so
135 * that the function has the ability to reinterpret a mode change
136 * that's due to these bits. This adds an implicit restriction that
137 * no function will ever call notify_change with both ATTR_MODE and
138 * ATTR_KILL_S*ID set.
139 */
140 if ((ia_valid & (ATTR_KILL_SUID|ATTR_KILL_SGID)) &&
141 (ia_valid & ATTR_MODE))
142 BUG();
143
144 if (ia_valid & ATTR_KILL_SUID) {
145 if (mode & S_ISUID) {
146 ia_valid = attr->ia_valid |= ATTR_MODE;
147 attr->ia_mode = (inode->i_mode & ~S_ISUID);
148 }
149 }
150 if (ia_valid & ATTR_KILL_SGID) {
151 if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
152 if (!(ia_valid & ATTR_MODE)) {
153 ia_valid = attr->ia_valid |= ATTR_MODE;
154 attr->ia_mode = inode->i_mode;
155 }
156 attr->ia_mode &= ~S_ISGID;
157 }
158 }
159 if (!(attr->ia_valid & ~(ATTR_KILL_SUID | ATTR_KILL_SGID)))
160 return 0;
161
162 error = security_inode_setattr(dentry, attr);
163 if (error)
164 return error;
165
166 if (ia_valid & ATTR_SIZE)
167 down_write(&dentry->d_inode->i_alloc_sem);
168
169 if (inode->i_op && inode->i_op->setattr) {
170 error = inode->i_op->setattr(dentry, attr);
171 } else {
172 error = inode_change_ok(inode, attr);
173 if (!error) {
174 if ((ia_valid & ATTR_UID && attr->ia_uid != inode->i_uid) ||
175 (ia_valid & ATTR_GID && attr->ia_gid != inode->i_gid))
176 error = vfs_dq_transfer(inode, attr) ?
177 -EDQUOT : 0;
178 if (!error)
179 error = inode_setattr(inode, attr);
180 }
181 }
182
183 if (ia_valid & ATTR_SIZE)
184 up_write(&dentry->d_inode->i_alloc_sem);
185
186 if (!error)
187 fsnotify_change(dentry, ia_valid);
188
189 return error;
190 }
191
192 EXPORT_SYMBOL(notify_change);
193
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