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git.proxmox.com Git - mirror_ubuntu-eoan-kernel.git/blob - fs/attr.c
4 * Copyright (C) 1991, 1992 Linus Torvalds
5 * changes by Thomas Schoebel-Theuer
8 #include <linux/export.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>
16 #include <linux/evm.h>
17 #include <linux/ima.h>
20 * inode_change_ok - check if attribute changes to an inode are allowed
21 * @inode: inode to check
22 * @attr: attributes to change
24 * Check if we are allowed to change the attributes contained in @attr
25 * in the given inode. This includes the normal unix access permission
26 * checks, as well as checks for rlimits and others.
28 * Should be called as the first thing in ->setattr implementations,
29 * possibly after taking additional locks.
31 int inode_change_ok(const struct inode
*inode
, struct iattr
*attr
)
33 unsigned int ia_valid
= attr
->ia_valid
;
36 * First check size constraints. These can't be overriden using
39 if (ia_valid
& ATTR_SIZE
) {
40 int error
= inode_newsize_ok(inode
, attr
->ia_size
);
45 /* If force is set do it anyway. */
46 if (ia_valid
& ATTR_FORCE
)
49 /* Make sure a caller can chown. */
50 if ((ia_valid
& ATTR_UID
) &&
51 (!uid_eq(current_fsuid(), inode
->i_uid
) ||
52 !uid_eq(attr
->ia_uid
, inode
->i_uid
)) &&
53 !capable_wrt_inode_uidgid(inode
, CAP_CHOWN
))
56 /* Make sure caller can chgrp. */
57 if ((ia_valid
& ATTR_GID
) &&
58 (!uid_eq(current_fsuid(), inode
->i_uid
) ||
59 (!in_group_p(attr
->ia_gid
) && !gid_eq(attr
->ia_gid
, inode
->i_gid
))) &&
60 !capable_wrt_inode_uidgid(inode
, CAP_CHOWN
))
63 /* Make sure a caller can chmod. */
64 if (ia_valid
& ATTR_MODE
) {
65 if (!inode_owner_or_capable(inode
))
67 /* Also check the setgid bit! */
68 if (!in_group_p((ia_valid
& ATTR_GID
) ? attr
->ia_gid
:
70 !capable_wrt_inode_uidgid(inode
, CAP_FSETID
))
71 attr
->ia_mode
&= ~S_ISGID
;
74 /* Check for setting the inode time. */
75 if (ia_valid
& (ATTR_MTIME_SET
| ATTR_ATIME_SET
| ATTR_TIMES_SET
)) {
76 if (!inode_owner_or_capable(inode
))
82 EXPORT_SYMBOL(inode_change_ok
);
85 * inode_newsize_ok - may this inode be truncated to a given size
86 * @inode: the inode to be truncated
87 * @offset: the new size to assign to the inode
88 * @Returns: 0 on success, -ve errno on failure
90 * inode_newsize_ok must be called with i_mutex held.
92 * inode_newsize_ok will check filesystem limits and ulimits to check that the
93 * new inode size is within limits. inode_newsize_ok will also send SIGXFSZ
94 * when necessary. Caller must not proceed with inode size change if failure is
95 * returned. @inode must be a file (not directory), with appropriate
96 * permissions to allow truncate (inode_newsize_ok does NOT check these
99 int inode_newsize_ok(const struct inode
*inode
, loff_t offset
)
101 if (inode
->i_size
< offset
) {
104 limit
= rlimit(RLIMIT_FSIZE
);
105 if (limit
!= RLIM_INFINITY
&& offset
> limit
)
107 if (offset
> inode
->i_sb
->s_maxbytes
)
111 * truncation of in-use swapfiles is disallowed - it would
112 * cause subsequent swapout to scribble on the now-freed
115 if (IS_SWAPFILE(inode
))
121 send_sig(SIGXFSZ
, current
, 0);
125 EXPORT_SYMBOL(inode_newsize_ok
);
128 * setattr_copy - copy simple metadata updates into the generic inode
129 * @inode: the inode to be updated
130 * @attr: the new attributes
132 * setattr_copy must be called with i_mutex held.
134 * setattr_copy updates the inode's metadata with that specified
135 * in attr. Noticeably missing is inode size update, which is more complex
136 * as it requires pagecache updates.
138 * The inode is not marked as dirty after this operation. The rationale is
139 * that for "simple" filesystems, the struct inode is the inode storage.
140 * The caller is free to mark the inode dirty afterwards if needed.
142 void setattr_copy(struct inode
*inode
, const struct iattr
*attr
)
144 unsigned int ia_valid
= attr
->ia_valid
;
146 if (ia_valid
& ATTR_UID
)
147 inode
->i_uid
= attr
->ia_uid
;
148 if (ia_valid
& ATTR_GID
)
149 inode
->i_gid
= attr
->ia_gid
;
150 if (ia_valid
& ATTR_ATIME
)
151 inode
->i_atime
= timespec_trunc(attr
->ia_atime
,
152 inode
->i_sb
->s_time_gran
);
153 if (ia_valid
& ATTR_MTIME
)
154 inode
->i_mtime
= timespec_trunc(attr
->ia_mtime
,
155 inode
->i_sb
->s_time_gran
);
156 if (ia_valid
& ATTR_CTIME
)
157 inode
->i_ctime
= timespec_trunc(attr
->ia_ctime
,
158 inode
->i_sb
->s_time_gran
);
159 if (ia_valid
& ATTR_MODE
) {
160 umode_t mode
= attr
->ia_mode
;
162 if (!in_group_p(inode
->i_gid
) &&
163 !capable_wrt_inode_uidgid(inode
, CAP_FSETID
))
165 inode
->i_mode
= mode
;
168 EXPORT_SYMBOL(setattr_copy
);
171 * notify_change - modify attributes of a filesytem object
172 * @dentry: object affected
173 * @iattr: new attributes
174 * @delegated_inode: returns inode, if the inode is delegated
176 * The caller must hold the i_mutex on the affected object.
178 * If notify_change discovers a delegation in need of breaking,
179 * it will return -EWOULDBLOCK and return a reference to the inode in
180 * delegated_inode. The caller should then break the delegation and
181 * retry. Because breaking a delegation may take a long time, the
182 * caller should drop the i_mutex before doing so.
184 * Alternatively, a caller may pass NULL for delegated_inode. This may
185 * be appropriate for callers that expect the underlying filesystem not
186 * to be NFS exported. Also, passing NULL is fine for callers holding
187 * the file open for write, as there can be no conflicting delegation in
190 int notify_change(struct dentry
* dentry
, struct iattr
* attr
, struct inode
**delegated_inode
)
192 struct inode
*inode
= dentry
->d_inode
;
193 umode_t mode
= inode
->i_mode
;
196 unsigned int ia_valid
= attr
->ia_valid
;
198 WARN_ON_ONCE(!mutex_is_locked(&inode
->i_mutex
));
200 if (ia_valid
& (ATTR_MODE
| ATTR_UID
| ATTR_GID
| ATTR_TIMES_SET
)) {
201 if (IS_IMMUTABLE(inode
) || IS_APPEND(inode
))
205 if ((ia_valid
& ATTR_MODE
)) {
206 umode_t amode
= attr
->ia_mode
;
207 /* Flag setting protected by i_mutex */
209 inode
->i_flags
&= ~S_NOSEC
;
212 now
= current_fs_time(inode
->i_sb
);
214 attr
->ia_ctime
= now
;
215 if (!(ia_valid
& ATTR_ATIME_SET
))
216 attr
->ia_atime
= now
;
217 if (!(ia_valid
& ATTR_MTIME_SET
))
218 attr
->ia_mtime
= now
;
219 if (ia_valid
& ATTR_KILL_PRIV
) {
220 attr
->ia_valid
&= ~ATTR_KILL_PRIV
;
221 ia_valid
&= ~ATTR_KILL_PRIV
;
222 error
= security_inode_need_killpriv(dentry
);
224 error
= security_inode_killpriv(dentry
);
230 * We now pass ATTR_KILL_S*ID to the lower level setattr function so
231 * that the function has the ability to reinterpret a mode change
232 * that's due to these bits. This adds an implicit restriction that
233 * no function will ever call notify_change with both ATTR_MODE and
234 * ATTR_KILL_S*ID set.
236 if ((ia_valid
& (ATTR_KILL_SUID
|ATTR_KILL_SGID
)) &&
237 (ia_valid
& ATTR_MODE
))
240 if (ia_valid
& ATTR_KILL_SUID
) {
241 if (mode
& S_ISUID
) {
242 ia_valid
= attr
->ia_valid
|= ATTR_MODE
;
243 attr
->ia_mode
= (inode
->i_mode
& ~S_ISUID
);
246 if (ia_valid
& ATTR_KILL_SGID
) {
247 if ((mode
& (S_ISGID
| S_IXGRP
)) == (S_ISGID
| S_IXGRP
)) {
248 if (!(ia_valid
& ATTR_MODE
)) {
249 ia_valid
= attr
->ia_valid
|= ATTR_MODE
;
250 attr
->ia_mode
= inode
->i_mode
;
252 attr
->ia_mode
&= ~S_ISGID
;
255 if (!(attr
->ia_valid
& ~(ATTR_KILL_SUID
| ATTR_KILL_SGID
)))
258 error
= security_inode_setattr(dentry
, attr
);
261 error
= try_break_deleg(inode
, delegated_inode
);
265 if (inode
->i_op
->setattr
)
266 error
= inode
->i_op
->setattr(dentry
, attr
);
268 error
= simple_setattr(dentry
, attr
);
271 fsnotify_change(dentry
, ia_valid
);
272 ima_inode_post_setattr(dentry
);
273 evm_inode_post_setattr(dentry
, ia_valid
);
278 EXPORT_SYMBOL(notify_change
);