blob: 1007ed6163146e5de5c5e0695ab6f40a6ad8c390 [file] [log] [blame]
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
Christoph Hellwig2c27c652010-06-04 11:30:04 +020017/**
18 * inode_change_ok - check if attribute changes to an inode are allowed
19 * @inode: inode to check
20 * @attr: attributes to change
21 *
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.
25 *
26 * Should be called as the first thing in ->setattr implementations,
27 * possibly after taking additional locks.
28 */
npiggin@suse.de25d9e2d2009-08-21 02:35:05 +100029int inode_change_ok(const struct inode *inode, struct iattr *attr)
Linus Torvalds1da177e2005-04-16 15:20:36 -070030{
Linus Torvalds1da177e2005-04-16 15:20:36 -070031 unsigned int ia_valid = attr->ia_valid;
32
Christoph Hellwig2c27c652010-06-04 11:30:04 +020033 /*
34 * First check size constraints. These can't be overriden using
35 * ATTR_FORCE.
36 */
37 if (ia_valid & ATTR_SIZE) {
38 int error = inode_newsize_ok(inode, attr->ia_size);
39 if (error)
40 return error;
41 }
42
Linus Torvalds1da177e2005-04-16 15:20:36 -070043 /* If force is set do it anyway. */
44 if (ia_valid & ATTR_FORCE)
Christoph Hellwig2c27c652010-06-04 11:30:04 +020045 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -070046
47 /* Make sure a caller can chown. */
48 if ((ia_valid & ATTR_UID) &&
David Howellsda9592e2008-11-14 10:39:05 +110049 (current_fsuid() != inode->i_uid ||
Linus Torvalds1da177e2005-04-16 15:20:36 -070050 attr->ia_uid != inode->i_uid) && !capable(CAP_CHOWN))
Christoph Hellwig2c27c652010-06-04 11:30:04 +020051 return -EPERM;
Linus Torvalds1da177e2005-04-16 15:20:36 -070052
53 /* Make sure caller can chgrp. */
54 if ((ia_valid & ATTR_GID) &&
David Howellsda9592e2008-11-14 10:39:05 +110055 (current_fsuid() != inode->i_uid ||
Linus Torvalds1da177e2005-04-16 15:20:36 -070056 (!in_group_p(attr->ia_gid) && attr->ia_gid != inode->i_gid)) &&
57 !capable(CAP_CHOWN))
Christoph Hellwig2c27c652010-06-04 11:30:04 +020058 return -EPERM;
Linus Torvalds1da177e2005-04-16 15:20:36 -070059
60 /* Make sure a caller can chmod. */
61 if (ia_valid & ATTR_MODE) {
Serge E. Hallyn2e149672011-03-23 16:43:26 -070062 if (!inode_owner_or_capable(inode))
Christoph Hellwig2c27c652010-06-04 11:30:04 +020063 return -EPERM;
Linus Torvalds1da177e2005-04-16 15:20:36 -070064 /* 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;
68 }
69
70 /* Check for setting the inode time. */
Miklos Szeredi9767d742008-07-01 15:01:26 +020071 if (ia_valid & (ATTR_MTIME_SET | ATTR_ATIME_SET | ATTR_TIMES_SET)) {
Serge E. Hallyn2e149672011-03-23 16:43:26 -070072 if (!inode_owner_or_capable(inode))
Christoph Hellwig2c27c652010-06-04 11:30:04 +020073 return -EPERM;
Linus Torvalds1da177e2005-04-16 15:20:36 -070074 }
Christoph Hellwig2c27c652010-06-04 11:30:04 +020075
76 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -070077}
Linus Torvalds1da177e2005-04-16 15:20:36 -070078EXPORT_SYMBOL(inode_change_ok);
79
npiggin@suse.de25d9e2d2009-08-21 02:35:05 +100080/**
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
85 *
npiggin@suse.de7bb46a62010-05-27 01:05:33 +100086 * inode_newsize_ok must be called with i_mutex held.
87 *
npiggin@suse.de25d9e2d2009-08-21 02:35:05 +100088 * 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
93 * conditions).
npiggin@suse.de25d9e2d2009-08-21 02:35:05 +100094 */
95int inode_newsize_ok(const struct inode *inode, loff_t offset)
96{
97 if (inode->i_size < offset) {
98 unsigned long limit;
99
Jiri Slabyd554ed892010-03-05 13:42:42 -0800100 limit = rlimit(RLIMIT_FSIZE);
npiggin@suse.de25d9e2d2009-08-21 02:35:05 +1000101 if (limit != RLIM_INFINITY && offset > limit)
102 goto out_sig;
103 if (offset > inode->i_sb->s_maxbytes)
104 goto out_big;
105 } else {
106 /*
107 * truncation of in-use swapfiles is disallowed - it would
108 * cause subsequent swapout to scribble on the now-freed
109 * blocks.
110 */
111 if (IS_SWAPFILE(inode))
112 return -ETXTBSY;
113 }
114
115 return 0;
116out_sig:
117 send_sig(SIGXFSZ, current, 0);
118out_big:
119 return -EFBIG;
120}
121EXPORT_SYMBOL(inode_newsize_ok);
122
npiggin@suse.de7bb46a62010-05-27 01:05:33 +1000123/**
Christoph Hellwig6a1a90a2010-06-04 11:30:00 +0200124 * setattr_copy - copy simple metadata updates into the generic inode
npiggin@suse.de7bb46a62010-05-27 01:05:33 +1000125 * @inode: the inode to be updated
126 * @attr: the new attributes
127 *
Christoph Hellwig6a1a90a2010-06-04 11:30:00 +0200128 * setattr_copy must be called with i_mutex held.
npiggin@suse.de7bb46a62010-05-27 01:05:33 +1000129 *
Christoph Hellwig6a1a90a2010-06-04 11:30:00 +0200130 * setattr_copy updates the inode's metadata with that specified
npiggin@suse.de7bb46a62010-05-27 01:05:33 +1000131 * in attr. Noticably missing is inode size update, which is more complex
Christoph Hellwig2c27c652010-06-04 11:30:04 +0200132 * as it requires pagecache updates.
npiggin@suse.de7bb46a62010-05-27 01:05:33 +1000133 *
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.
137 */
Christoph Hellwig6a1a90a2010-06-04 11:30:00 +0200138void setattr_copy(struct inode *inode, const struct iattr *attr)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700139{
140 unsigned int ia_valid = attr->ia_valid;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700141
Linus Torvalds1da177e2005-04-16 15:20:36 -0700142 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;
157
158 if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID))
159 mode &= ~S_ISGID;
160 inode->i_mode = mode;
161 }
npiggin@suse.de7bb46a62010-05-27 01:05:33 +1000162}
Christoph Hellwig6a1a90a2010-06-04 11:30:00 +0200163EXPORT_SYMBOL(setattr_copy);
npiggin@suse.de7bb46a62010-05-27 01:05:33 +1000164
Linus Torvalds1da177e2005-04-16 15:20:36 -0700165int notify_change(struct dentry * dentry, struct iattr * attr)
166{
167 struct inode *inode = dentry->d_inode;
Jeff Layton6de0ec02007-10-18 03:05:20 -0700168 mode_t mode = inode->i_mode;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700169 int error;
170 struct timespec now;
171 unsigned int ia_valid = attr->ia_valid;
172
Miklos Szeredibeb29e02008-07-01 15:01:29 +0200173 if (ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID | ATTR_TIMES_SET)) {
174 if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
175 return -EPERM;
176 }
177
Linus Torvalds1da177e2005-04-16 15:20:36 -0700178 now = current_fs_time(inode->i_sb);
179
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;
Serge E. Hallynb5376772007-10-16 23:31:36 -0700185 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);
189 if (error > 0)
190 error = security_inode_killpriv(dentry);
191 if (error)
192 return error;
193 }
Jeff Layton6de0ec02007-10-18 03:05:20 -0700194
195 /*
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.
201 */
202 if ((ia_valid & (ATTR_KILL_SUID|ATTR_KILL_SGID)) &&
203 (ia_valid & ATTR_MODE))
204 BUG();
205
Linus Torvalds1da177e2005-04-16 15:20:36 -0700206 if (ia_valid & ATTR_KILL_SUID) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700207 if (mode & S_ISUID) {
Jeff Layton6de0ec02007-10-18 03:05:20 -0700208 ia_valid = attr->ia_valid |= ATTR_MODE;
209 attr->ia_mode = (inode->i_mode & ~S_ISUID);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700210 }
211 }
212 if (ia_valid & ATTR_KILL_SGID) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700213 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;
217 }
218 attr->ia_mode &= ~S_ISGID;
219 }
220 }
Jeff Layton6de0ec02007-10-18 03:05:20 -0700221 if (!(attr->ia_valid & ~(ATTR_KILL_SUID | ATTR_KILL_SGID)))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700222 return 0;
223
Miklos Szeredia77b72d2008-07-30 14:06:22 +0200224 error = security_inode_setattr(dentry, attr);
225 if (error)
226 return error;
227
Linus Torvalds1da177e2005-04-16 15:20:36 -0700228 if (ia_valid & ATTR_SIZE)
229 down_write(&dentry->d_inode->i_alloc_sem);
230
Christoph Hellwigeef23802010-06-04 11:30:01 +0200231 if (inode->i_op->setattr)
Miklos Szeredia77b72d2008-07-30 14:06:22 +0200232 error = inode->i_op->setattr(dentry, attr);
Christoph Hellwigeef23802010-06-04 11:30:01 +0200233 else
234 error = simple_setattr(dentry, attr);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700235
236 if (ia_valid & ATTR_SIZE)
237 up_write(&dentry->d_inode->i_alloc_sem);
238
Robert Love0eeca282005-07-12 17:06:03 -0400239 if (!error)
240 fsnotify_change(dentry, ia_valid);
241
Linus Torvalds1da177e2005-04-16 15:20:36 -0700242 return error;
243}
244
245EXPORT_SYMBOL(notify_change);