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);
170 int notify_change(struct dentry * dentry, struct iattr * attr)
172 struct inode *inode = dentry->d_inode;
173 umode_t mode = inode->i_mode;
176 unsigned int ia_valid = attr->ia_valid;
178 WARN_ON_ONCE(!mutex_is_locked(&inode->i_mutex));
180 if (ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID | ATTR_TIMES_SET)) {
181 if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
185 if ((ia_valid & ATTR_MODE)) {
186 umode_t amode = attr->ia_mode;
187 /* Flag setting protected by i_mutex */
189 inode->i_flags &= ~S_NOSEC;
192 now = current_fs_time(inode->i_sb);
194 attr->ia_ctime = now;
195 if (!(ia_valid & ATTR_ATIME_SET))
196 attr->ia_atime = now;
197 if (!(ia_valid & ATTR_MTIME_SET))
198 attr->ia_mtime = now;
199 if (ia_valid & ATTR_KILL_PRIV) {
200 attr->ia_valid &= ~ATTR_KILL_PRIV;
201 ia_valid &= ~ATTR_KILL_PRIV;
202 error = security_inode_need_killpriv(dentry);
204 error = security_inode_killpriv(dentry);
210 * We now pass ATTR_KILL_S*ID to the lower level setattr function so
211 * that the function has the ability to reinterpret a mode change
212 * that's due to these bits. This adds an implicit restriction that
213 * no function will ever call notify_change with both ATTR_MODE and
214 * ATTR_KILL_S*ID set.
216 if ((ia_valid & (ATTR_KILL_SUID|ATTR_KILL_SGID)) &&
217 (ia_valid & ATTR_MODE))
220 if (ia_valid & ATTR_KILL_SUID) {
221 if (mode & S_ISUID) {
222 ia_valid = attr->ia_valid |= ATTR_MODE;
223 attr->ia_mode = (inode->i_mode & ~S_ISUID);
226 if (ia_valid & ATTR_KILL_SGID) {
227 if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
228 if (!(ia_valid & ATTR_MODE)) {
229 ia_valid = attr->ia_valid |= ATTR_MODE;
230 attr->ia_mode = inode->i_mode;
232 attr->ia_mode &= ~S_ISGID;
235 if (!(attr->ia_valid & ~(ATTR_KILL_SUID | ATTR_KILL_SGID)))
238 error = security_inode_setattr(dentry, attr);
242 if (inode->i_op->setattr)
243 error = inode->i_op->setattr(dentry, attr);
245 error = simple_setattr(dentry, attr);
248 fsnotify_change(dentry, ia_valid);
249 ima_inode_post_setattr(dentry);
250 evm_inode_post_setattr(dentry, ia_valid);
255 EXPORT_SYMBOL(notify_change);