4 * Copyright (C) 1991, 1992 Linus Torvalds
5 * changes by Thomas Schoebel-Theuer
8 #include <linux/module.h>
9 #include <linux/time.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>
18 * inode_change_ok - check if attribute changes to an inode are allowed
19 * @inode: inode to check
20 * @attr: attributes to change
22 * Check if we are allowed to change the attributes contained in @attr
23 * in the given inode. This includes the normal unix access permission
24 * checks, as well as checks for rlimits and others.
26 * Should be called as the first thing in ->setattr implementations,
27 * possibly after taking additional locks.
29 int inode_change_ok(const struct inode
*inode
, struct iattr
*attr
)
31 unsigned int ia_valid
= attr
->ia_valid
;
34 * First check size constraints. These can't be overriden using
37 if (ia_valid
& ATTR_SIZE
) {
38 int error
= inode_newsize_ok(inode
, attr
->ia_size
);
43 /* If force is set do it anyway. */
44 if (ia_valid
& ATTR_FORCE
)
47 /* Make sure a caller can chown. */
48 if ((ia_valid
& ATTR_UID
) &&
49 (current_fsuid() != inode
->i_uid
||
50 attr
->ia_uid
!= inode
->i_uid
) && !capable(CAP_CHOWN
))
53 /* Make sure caller can chgrp. */
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
)) &&
60 /* Make sure a caller can chmod. */
61 if (ia_valid
& ATTR_MODE
) {
62 if (!is_owner_or_cap(inode
))
64 /* Also check the setgid bit! */
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
;
70 /* Check for setting the inode time. */
71 if (ia_valid
& (ATTR_MTIME_SET
| ATTR_ATIME_SET
| ATTR_TIMES_SET
)) {
72 if (!is_owner_or_cap(inode
))
78 EXPORT_SYMBOL(inode_change_ok
);
81 * inode_newsize_ok - may this inode be truncated to a given size
82 * @inode: the inode to be truncated
83 * @offset: the new size to assign to the inode
84 * @Returns: 0 on success, -ve errno on failure
86 * inode_newsize_ok must be called with i_mutex held.
88 * inode_newsize_ok will check filesystem limits and ulimits to check that the
89 * new inode size is within limits. inode_newsize_ok will also send SIGXFSZ
90 * when necessary. Caller must not proceed with inode size change if failure is
91 * returned. @inode must be a file (not directory), with appropriate
92 * permissions to allow truncate (inode_newsize_ok does NOT check these
95 int inode_newsize_ok(const struct inode
*inode
, loff_t offset
)
97 if (inode
->i_size
< offset
) {
100 limit
= rlimit(RLIMIT_FSIZE
);
101 if (limit
!= RLIM_INFINITY
&& offset
> limit
)
103 if (offset
> inode
->i_sb
->s_maxbytes
)
107 * truncation of in-use swapfiles is disallowed - it would
108 * cause subsequent swapout to scribble on the now-freed
111 if (IS_SWAPFILE(inode
))
117 send_sig(SIGXFSZ
, current
, 0);
121 EXPORT_SYMBOL(inode_newsize_ok
);
124 * setattr_copy - copy simple metadata updates into the generic inode
125 * @inode: the inode to be updated
126 * @attr: the new attributes
128 * setattr_copy must be called with i_mutex held.
130 * setattr_copy updates the inode's metadata with that specified
131 * in attr. Noticably missing is inode size update, which is more complex
132 * as it requires pagecache updates.
134 * The inode is not marked as dirty after this operation. The rationale is
135 * that for "simple" filesystems, the struct inode is the inode storage.
136 * The caller is free to mark the inode dirty afterwards if needed.
138 void setattr_copy(struct inode
*inode
, const struct iattr
*attr
)
140 unsigned int ia_valid
= attr
->ia_valid
;
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
;
158 if (!in_group_p(inode
->i_gid
) && !capable(CAP_FSETID
))
160 inode
->i_mode
= mode
;
163 EXPORT_SYMBOL(setattr_copy
);
165 int notify_change(struct dentry
* dentry
, struct iattr
* attr
)
167 struct inode
*inode
= dentry
->d_inode
;
168 mode_t mode
= inode
->i_mode
;
171 unsigned int ia_valid
= attr
->ia_valid
;
173 if (ia_valid
& (ATTR_MODE
| ATTR_UID
| ATTR_GID
| ATTR_TIMES_SET
)) {
174 if (IS_IMMUTABLE(inode
) || IS_APPEND(inode
))
178 now
= current_fs_time(inode
->i_sb
);
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
);
190 error
= security_inode_killpriv(dentry
);
196 * We now pass ATTR_KILL_S*ID to the lower level setattr function so
197 * that the function has the ability to reinterpret a mode change
198 * that's due to these bits. This adds an implicit restriction that
199 * no function will ever call notify_change with both ATTR_MODE and
200 * ATTR_KILL_S*ID set.
202 if ((ia_valid
& (ATTR_KILL_SUID
|ATTR_KILL_SGID
)) &&
203 (ia_valid
& ATTR_MODE
))
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
);
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
;
218 attr
->ia_mode
&= ~S_ISGID
;
221 if (!(attr
->ia_valid
& ~(ATTR_KILL_SUID
| ATTR_KILL_SGID
)))
224 error
= security_inode_setattr(dentry
, attr
);
228 if (ia_valid
& ATTR_SIZE
)
229 down_write(&dentry
->d_inode
->i_alloc_sem
);
231 if (inode
->i_op
->setattr
)
232 error
= inode
->i_op
->setattr(dentry
, attr
);
234 error
= simple_setattr(dentry
, attr
);
236 if (ia_valid
& ATTR_SIZE
)
237 up_write(&dentry
->d_inode
->i_alloc_sem
);
240 fsnotify_change(dentry
, ia_valid
);
245 EXPORT_SYMBOL(notify_change
);
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