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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
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>
Randy Dunlap16f7e0f2006-01-11 12:17:46 -080012#include <linux/capability.h>
Robert Love0eeca282005-07-12 17:06:03 -040013#include <linux/fsnotify.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070014#include <linux/fcntl.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070015#include <linux/security.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070016
17/* Taken over from the old code... */
18
19/* POSIX UID/GID verification for setting inode attributes. */
npiggin@suse.de25d9e2d2009-08-21 02:35:05 +100020int inode_change_ok(const struct inode *inode, struct iattr *attr)
Linus Torvalds1da177e2005-04-16 15:20:36 -070021{
22 int retval = -EPERM;
23 unsigned int ia_valid = attr->ia_valid;
24
25 /* If force is set do it anyway. */
26 if (ia_valid & ATTR_FORCE)
27 goto fine;
28
29 /* Make sure a caller can chown. */
30 if ((ia_valid & ATTR_UID) &&
David Howellsda9592e2008-11-14 10:39:05 +110031 (current_fsuid() != inode->i_uid ||
Linus Torvalds1da177e2005-04-16 15:20:36 -070032 attr->ia_uid != inode->i_uid) && !capable(CAP_CHOWN))
33 goto error;
34
35 /* Make sure caller can chgrp. */
36 if ((ia_valid & ATTR_GID) &&
David Howellsda9592e2008-11-14 10:39:05 +110037 (current_fsuid() != inode->i_uid ||
Linus Torvalds1da177e2005-04-16 15:20:36 -070038 (!in_group_p(attr->ia_gid) && attr->ia_gid != inode->i_gid)) &&
39 !capable(CAP_CHOWN))
40 goto error;
41
42 /* Make sure a caller can chmod. */
43 if (ia_valid & ATTR_MODE) {
Satyam Sharma3bd858a2007-07-17 15:00:08 +053044 if (!is_owner_or_cap(inode))
Linus Torvalds1da177e2005-04-16 15:20:36 -070045 goto error;
46 /* Also check the setgid bit! */
47 if (!in_group_p((ia_valid & ATTR_GID) ? attr->ia_gid :
48 inode->i_gid) && !capable(CAP_FSETID))
49 attr->ia_mode &= ~S_ISGID;
50 }
51
52 /* Check for setting the inode time. */
Miklos Szeredi9767d742008-07-01 15:01:26 +020053 if (ia_valid & (ATTR_MTIME_SET | ATTR_ATIME_SET | ATTR_TIMES_SET)) {
Satyam Sharma3bd858a2007-07-17 15:00:08 +053054 if (!is_owner_or_cap(inode))
Linus Torvalds1da177e2005-04-16 15:20:36 -070055 goto error;
56 }
57fine:
58 retval = 0;
59error:
60 return retval;
61}
Linus Torvalds1da177e2005-04-16 15:20:36 -070062EXPORT_SYMBOL(inode_change_ok);
63
npiggin@suse.de25d9e2d2009-08-21 02:35:05 +100064/**
65 * inode_newsize_ok - may this inode be truncated to a given size
66 * @inode: the inode to be truncated
67 * @offset: the new size to assign to the inode
68 * @Returns: 0 on success, -ve errno on failure
69 *
npiggin@suse.de7bb46a62010-05-27 01:05:33 +100070 * inode_newsize_ok must be called with i_mutex held.
71 *
npiggin@suse.de25d9e2d2009-08-21 02:35:05 +100072 * inode_newsize_ok will check filesystem limits and ulimits to check that the
73 * new inode size is within limits. inode_newsize_ok will also send SIGXFSZ
74 * when necessary. Caller must not proceed with inode size change if failure is
75 * returned. @inode must be a file (not directory), with appropriate
76 * permissions to allow truncate (inode_newsize_ok does NOT check these
77 * conditions).
npiggin@suse.de25d9e2d2009-08-21 02:35:05 +100078 */
79int inode_newsize_ok(const struct inode *inode, loff_t offset)
80{
81 if (inode->i_size < offset) {
82 unsigned long limit;
83
Jiri Slabyd554ed892010-03-05 13:42:42 -080084 limit = rlimit(RLIMIT_FSIZE);
npiggin@suse.de25d9e2d2009-08-21 02:35:05 +100085 if (limit != RLIM_INFINITY && offset > limit)
86 goto out_sig;
87 if (offset > inode->i_sb->s_maxbytes)
88 goto out_big;
89 } else {
90 /*
91 * truncation of in-use swapfiles is disallowed - it would
92 * cause subsequent swapout to scribble on the now-freed
93 * blocks.
94 */
95 if (IS_SWAPFILE(inode))
96 return -ETXTBSY;
97 }
98
99 return 0;
100out_sig:
101 send_sig(SIGXFSZ, current, 0);
102out_big:
103 return -EFBIG;
104}
105EXPORT_SYMBOL(inode_newsize_ok);
106
npiggin@suse.de7bb46a62010-05-27 01:05:33 +1000107/**
108 * generic_setattr - copy simple metadata updates into the generic inode
109 * @inode: the inode to be updated
110 * @attr: the new attributes
111 *
112 * generic_setattr must be called with i_mutex held.
113 *
114 * generic_setattr updates the inode's metadata with that specified
115 * in attr. Noticably missing is inode size update, which is more complex
116 * as it requires pagecache updates. See simple_setsize.
117 *
118 * The inode is not marked as dirty after this operation. The rationale is
119 * that for "simple" filesystems, the struct inode is the inode storage.
120 * The caller is free to mark the inode dirty afterwards if needed.
121 */
122void generic_setattr(struct inode *inode, const struct iattr *attr)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700123{
124 unsigned int ia_valid = attr->ia_valid;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700125
Linus Torvalds1da177e2005-04-16 15:20:36 -0700126 if (ia_valid & ATTR_UID)
127 inode->i_uid = attr->ia_uid;
128 if (ia_valid & ATTR_GID)
129 inode->i_gid = attr->ia_gid;
130 if (ia_valid & ATTR_ATIME)
131 inode->i_atime = timespec_trunc(attr->ia_atime,
132 inode->i_sb->s_time_gran);
133 if (ia_valid & ATTR_MTIME)
134 inode->i_mtime = timespec_trunc(attr->ia_mtime,
135 inode->i_sb->s_time_gran);
136 if (ia_valid & ATTR_CTIME)
137 inode->i_ctime = timespec_trunc(attr->ia_ctime,
138 inode->i_sb->s_time_gran);
139 if (ia_valid & ATTR_MODE) {
140 umode_t mode = attr->ia_mode;
141
142 if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID))
143 mode &= ~S_ISGID;
144 inode->i_mode = mode;
145 }
npiggin@suse.de7bb46a62010-05-27 01:05:33 +1000146}
147EXPORT_SYMBOL(generic_setattr);
148
149/*
150 * note this function is deprecated, the new truncate sequence should be
151 * used instead -- see eg. simple_setsize, generic_setattr.
152 */
153int inode_setattr(struct inode *inode, const struct iattr *attr)
154{
155 unsigned int ia_valid = attr->ia_valid;
156
157 if (ia_valid & ATTR_SIZE &&
158 attr->ia_size != i_size_read(inode)) {
159 int error;
160
161 error = vmtruncate(inode, attr->ia_size);
162 if (error)
163 return error;
164 }
165
166 generic_setattr(inode, attr);
167
Linus Torvalds1da177e2005-04-16 15:20:36 -0700168 mark_inode_dirty(inode);
NeilBrown4a301312006-01-08 01:02:39 -0800169
170 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700171}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700172EXPORT_SYMBOL(inode_setattr);
173
Linus Torvalds1da177e2005-04-16 15:20:36 -0700174int notify_change(struct dentry * dentry, struct iattr * attr)
175{
176 struct inode *inode = dentry->d_inode;
Jeff Layton6de0ec02007-10-18 03:05:20 -0700177 mode_t mode = inode->i_mode;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700178 int error;
179 struct timespec now;
180 unsigned int ia_valid = attr->ia_valid;
181
Miklos Szeredibeb29e02008-07-01 15:01:29 +0200182 if (ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID | ATTR_TIMES_SET)) {
183 if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
184 return -EPERM;
185 }
186
Linus Torvalds1da177e2005-04-16 15:20:36 -0700187 now = current_fs_time(inode->i_sb);
188
189 attr->ia_ctime = now;
190 if (!(ia_valid & ATTR_ATIME_SET))
191 attr->ia_atime = now;
192 if (!(ia_valid & ATTR_MTIME_SET))
193 attr->ia_mtime = now;
Serge E. Hallynb5376772007-10-16 23:31:36 -0700194 if (ia_valid & ATTR_KILL_PRIV) {
195 attr->ia_valid &= ~ATTR_KILL_PRIV;
196 ia_valid &= ~ATTR_KILL_PRIV;
197 error = security_inode_need_killpriv(dentry);
198 if (error > 0)
199 error = security_inode_killpriv(dentry);
200 if (error)
201 return error;
202 }
Jeff Layton6de0ec02007-10-18 03:05:20 -0700203
204 /*
205 * We now pass ATTR_KILL_S*ID to the lower level setattr function so
206 * that the function has the ability to reinterpret a mode change
207 * that's due to these bits. This adds an implicit restriction that
208 * no function will ever call notify_change with both ATTR_MODE and
209 * ATTR_KILL_S*ID set.
210 */
211 if ((ia_valid & (ATTR_KILL_SUID|ATTR_KILL_SGID)) &&
212 (ia_valid & ATTR_MODE))
213 BUG();
214
Linus Torvalds1da177e2005-04-16 15:20:36 -0700215 if (ia_valid & ATTR_KILL_SUID) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700216 if (mode & S_ISUID) {
Jeff Layton6de0ec02007-10-18 03:05:20 -0700217 ia_valid = attr->ia_valid |= ATTR_MODE;
218 attr->ia_mode = (inode->i_mode & ~S_ISUID);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700219 }
220 }
221 if (ia_valid & ATTR_KILL_SGID) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700222 if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
223 if (!(ia_valid & ATTR_MODE)) {
224 ia_valid = attr->ia_valid |= ATTR_MODE;
225 attr->ia_mode = inode->i_mode;
226 }
227 attr->ia_mode &= ~S_ISGID;
228 }
229 }
Jeff Layton6de0ec02007-10-18 03:05:20 -0700230 if (!(attr->ia_valid & ~(ATTR_KILL_SUID | ATTR_KILL_SGID)))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700231 return 0;
232
Miklos Szeredia77b72d2008-07-30 14:06:22 +0200233 error = security_inode_setattr(dentry, attr);
234 if (error)
235 return error;
236
Linus Torvalds1da177e2005-04-16 15:20:36 -0700237 if (ia_valid & ATTR_SIZE)
238 down_write(&dentry->d_inode->i_alloc_sem);
239
240 if (inode->i_op && inode->i_op->setattr) {
Miklos Szeredia77b72d2008-07-30 14:06:22 +0200241 error = inode->i_op->setattr(dentry, attr);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700242 } else {
243 error = inode_change_ok(inode, attr);
Christoph Hellwig759bfee2010-03-03 09:05:02 -0500244 if (!error)
245 error = inode_setattr(inode, attr);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700246 }
247
248 if (ia_valid & ATTR_SIZE)
249 up_write(&dentry->d_inode->i_alloc_sem);
250
Robert Love0eeca282005-07-12 17:06:03 -0400251 if (!error)
252 fsnotify_change(dentry, ia_valid);
253
Linus Torvalds1da177e2005-04-16 15:20:36 -0700254 return error;
255}
256
257EXPORT_SYMBOL(notify_change);