1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Copyright (c) 2000-2006 Silicon Graphics, Inc.
4 * Copyright (c) 2012-2013 Red Hat, Inc.
5 * All rights reserved.
6 */
7 #include "xfs.h"
8 #include "xfs_shared.h"
9 #include "xfs_fs.h"
10 #include "xfs_format.h"
11 #include "xfs_log_format.h"
12 #include "xfs_trans_resv.h"
13 #include "xfs_bit.h"
14 #include "xfs_mount.h"
15 #include "xfs_dir2.h"
16 #include "xfs_inode.h"
17 #include "xfs_bmap.h"
18 #include "xfs_bmap_btree.h"
19 #include "xfs_quota.h"
20 #include "xfs_symlink.h"
21 #include "xfs_trans_space.h"
22 #include "xfs_trace.h"
23 #include "xfs_trans.h"
24 #include "xfs_ialloc.h"
25 #include "xfs_error.h"
26 #include "xfs_health.h"
27 #include "xfs_symlink_remote.h"
28 #include "xfs_parent.h"
29 #include "xfs_defer.h"
30
31 int
xfs_readlink(struct xfs_inode * ip,char * link)32 xfs_readlink(
33 struct xfs_inode *ip,
34 char *link)
35 {
36 struct xfs_mount *mp = ip->i_mount;
37 xfs_fsize_t pathlen;
38 int error;
39
40 trace_xfs_readlink(ip);
41
42 if (xfs_is_shutdown(mp))
43 return -EIO;
44 if (xfs_ifork_zapped(ip, XFS_DATA_FORK))
45 return -EIO;
46
47 xfs_ilock(ip, XFS_ILOCK_SHARED);
48
49 pathlen = ip->i_disk_size;
50 if (!pathlen)
51 goto out_corrupt;
52
53 if (pathlen < 0 || pathlen > XFS_SYMLINK_MAXLEN) {
54 xfs_alert(mp, "%s: inode (%llu) bad symlink length (%lld)",
55 __func__, (unsigned long long) ip->i_ino,
56 (long long) pathlen);
57 ASSERT(0);
58 goto out_corrupt;
59 }
60
61 if (ip->i_df.if_format == XFS_DINODE_FMT_LOCAL) {
62 /*
63 * The VFS crashes on a NULL pointer, so return -EFSCORRUPTED
64 * if if_data is junk.
65 */
66 if (XFS_IS_CORRUPT(ip->i_mount, !ip->i_df.if_data))
67 goto out_corrupt;
68
69 memcpy(link, ip->i_df.if_data, pathlen + 1);
70 error = 0;
71 } else {
72 error = xfs_symlink_remote_read(ip, link);
73 }
74
75 xfs_iunlock(ip, XFS_ILOCK_SHARED);
76 return error;
77 out_corrupt:
78 xfs_iunlock(ip, XFS_ILOCK_SHARED);
79 xfs_inode_mark_sick(ip, XFS_SICK_INO_SYMLINK);
80 return -EFSCORRUPTED;
81 }
82
83 int
xfs_symlink(struct mnt_idmap * idmap,struct xfs_inode * dp,struct xfs_name * link_name,const char * target_path,umode_t mode,struct xfs_inode ** ipp)84 xfs_symlink(
85 struct mnt_idmap *idmap,
86 struct xfs_inode *dp,
87 struct xfs_name *link_name,
88 const char *target_path,
89 umode_t mode,
90 struct xfs_inode **ipp)
91 {
92 struct xfs_mount *mp = dp->i_mount;
93 struct xfs_icreate_args args = {
94 .idmap = idmap,
95 .pip = dp,
96 .mode = S_IFLNK | (mode & ~S_IFMT),
97 };
98 struct xfs_dir_update du = {
99 .dp = dp,
100 .name = link_name,
101 };
102 struct xfs_trans *tp = NULL;
103 int error = 0;
104 int pathlen;
105 bool unlock_dp_on_error = false;
106 xfs_filblks_t fs_blocks;
107 struct xfs_dquot *udqp;
108 struct xfs_dquot *gdqp;
109 struct xfs_dquot *pdqp;
110 uint resblks;
111 xfs_ino_t ino;
112
113 *ipp = NULL;
114
115 trace_xfs_symlink(dp, link_name);
116
117 if (xfs_is_shutdown(mp))
118 return -EIO;
119
120 /*
121 * Check component lengths of the target path name.
122 */
123 pathlen = strlen(target_path);
124 if (pathlen >= XFS_SYMLINK_MAXLEN) /* total string too long */
125 return -ENAMETOOLONG;
126 ASSERT(pathlen > 0);
127
128 /* Make sure that we have allocated dquot(s) on disk. */
129 error = xfs_icreate_dqalloc(&args, &udqp, &gdqp, &pdqp);
130 if (error)
131 return error;
132
133 /*
134 * The symlink will fit into the inode data fork?
135 * If there are no parent pointers, then there wont't be any attributes.
136 * So we get the whole variable part, and do not need to reserve extra
137 * blocks. Otherwise, we need to reserve the blocks.
138 */
139 if (pathlen <= XFS_LITINO(mp) && !xfs_has_parent(mp))
140 fs_blocks = 0;
141 else
142 fs_blocks = xfs_symlink_blocks(mp, pathlen);
143 resblks = xfs_symlink_space_res(mp, link_name->len, fs_blocks);
144
145 error = xfs_parent_start(mp, &du.ppargs);
146 if (error)
147 goto out_release_dquots;
148
149 error = xfs_trans_alloc_icreate(mp, &M_RES(mp)->tr_symlink, udqp, gdqp,
150 pdqp, resblks, &tp);
151 if (error)
152 goto out_parent;
153
154 xfs_ilock(dp, XFS_ILOCK_EXCL | XFS_ILOCK_PARENT);
155 unlock_dp_on_error = true;
156
157 /*
158 * Check whether the directory allows new symlinks or not.
159 */
160 if (dp->i_diflags & XFS_DIFLAG_NOSYMLINKS) {
161 error = -EPERM;
162 goto out_trans_cancel;
163 }
164
165 /*
166 * Allocate an inode for the symlink.
167 */
168 error = xfs_dialloc(&tp, &args, &ino);
169 if (!error)
170 error = xfs_icreate(tp, ino, &args, &du.ip);
171 if (error)
172 goto out_trans_cancel;
173
174 /*
175 * Now we join the directory inode to the transaction. We do not do it
176 * earlier because xfs_dir_ialloc might commit the previous transaction
177 * (and release all the locks). An error from here on will result in
178 * the transaction cancel unlocking dp so don't do it explicitly in the
179 * error path.
180 */
181 xfs_trans_ijoin(tp, dp, 0);
182
183 /*
184 * Also attach the dquot(s) to it, if applicable.
185 */
186 xfs_qm_vop_create_dqattach(tp, du.ip, udqp, gdqp, pdqp);
187
188 resblks -= XFS_IALLOC_SPACE_RES(mp);
189 error = xfs_symlink_write_target(tp, du.ip, du.ip->i_ino, target_path,
190 pathlen, fs_blocks, resblks);
191 if (error)
192 goto out_trans_cancel;
193 resblks -= fs_blocks;
194 i_size_write(VFS_I(du.ip), du.ip->i_disk_size);
195
196 /*
197 * Create the directory entry for the symlink.
198 */
199 error = xfs_dir_create_child(tp, resblks, &du);
200 if (error)
201 goto out_trans_cancel;
202
203 /*
204 * If this is a synchronous mount, make sure that the
205 * symlink transaction goes to disk before returning to
206 * the user.
207 */
208 if (xfs_has_wsync(mp) || xfs_has_dirsync(mp))
209 xfs_trans_set_sync(tp);
210
211 error = xfs_trans_commit(tp);
212 if (error)
213 goto out_release_inode;
214
215 xfs_qm_dqrele(udqp);
216 xfs_qm_dqrele(gdqp);
217 xfs_qm_dqrele(pdqp);
218
219 *ipp = du.ip;
220 xfs_iunlock(du.ip, XFS_ILOCK_EXCL);
221 xfs_iunlock(dp, XFS_ILOCK_EXCL);
222 xfs_parent_finish(mp, du.ppargs);
223 return 0;
224
225 out_trans_cancel:
226 xfs_trans_cancel(tp);
227 out_release_inode:
228 /*
229 * Wait until after the current transaction is aborted to finish the
230 * setup of the inode and release the inode. This prevents recursive
231 * transactions and deadlocks from xfs_inactive.
232 */
233 if (du.ip) {
234 xfs_iunlock(du.ip, XFS_ILOCK_EXCL);
235 xfs_finish_inode_setup(du.ip);
236 xfs_irele(du.ip);
237 }
238 out_parent:
239 xfs_parent_finish(mp, du.ppargs);
240 out_release_dquots:
241 xfs_qm_dqrele(udqp);
242 xfs_qm_dqrele(gdqp);
243 xfs_qm_dqrele(pdqp);
244
245 if (unlock_dp_on_error)
246 xfs_iunlock(dp, XFS_ILOCK_EXCL);
247 return error;
248 }
249
250 /*
251 * Free a symlink that has blocks associated with it.
252 *
253 * Note: zero length symlinks are not allowed to exist. When we set the size to
254 * zero, also change it to a regular file so that it does not get written to
255 * disk as a zero length symlink. The inode is on the unlinked list already, so
256 * userspace cannot find this inode anymore, so this change is not user visible
257 * but allows us to catch corrupt zero-length symlinks in the verifiers.
258 */
259 STATIC int
xfs_inactive_symlink_rmt(struct xfs_inode * ip)260 xfs_inactive_symlink_rmt(
261 struct xfs_inode *ip)
262 {
263 struct xfs_mount *mp = ip->i_mount;
264 struct xfs_trans *tp;
265 int error;
266
267 ASSERT(!xfs_need_iread_extents(&ip->i_df));
268 /*
269 * We're freeing a symlink that has some
270 * blocks allocated to it. Free the
271 * blocks here. We know that we've got
272 * either 1 or 2 extents and that we can
273 * free them all in one bunmapi call.
274 */
275 ASSERT(ip->i_df.if_nextents > 0 && ip->i_df.if_nextents <= 2);
276
277 error = xfs_trans_alloc(mp, &M_RES(mp)->tr_itruncate, 0, 0, 0, &tp);
278 if (error)
279 return error;
280
281 xfs_ilock(ip, XFS_ILOCK_EXCL);
282 xfs_trans_ijoin(tp, ip, 0);
283
284 /*
285 * Lock the inode, fix the size, turn it into a regular file and join it
286 * to the transaction. Hold it so in the normal path, we still have it
287 * locked for the second transaction. In the error paths we need it
288 * held so the cancel won't rele it, see below.
289 */
290 ip->i_disk_size = 0;
291 VFS_I(ip)->i_mode = (VFS_I(ip)->i_mode & ~S_IFMT) | S_IFREG;
292 xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
293
294 error = xfs_symlink_remote_truncate(tp, ip);
295 if (error)
296 goto error_trans_cancel;
297
298 error = xfs_trans_commit(tp);
299 if (error) {
300 ASSERT(xfs_is_shutdown(mp));
301 goto error_unlock;
302 }
303
304 /*
305 * Remove the memory for extent descriptions (just bookkeeping).
306 */
307 if (ip->i_df.if_bytes)
308 xfs_idata_realloc(ip, -ip->i_df.if_bytes, XFS_DATA_FORK);
309 ASSERT(ip->i_df.if_bytes == 0);
310
311 xfs_iunlock(ip, XFS_ILOCK_EXCL);
312 return 0;
313
314 error_trans_cancel:
315 xfs_trans_cancel(tp);
316 error_unlock:
317 xfs_iunlock(ip, XFS_ILOCK_EXCL);
318 return error;
319 }
320
321 /*
322 * xfs_inactive_symlink - free a symlink
323 */
324 int
xfs_inactive_symlink(struct xfs_inode * ip)325 xfs_inactive_symlink(
326 struct xfs_inode *ip)
327 {
328 struct xfs_mount *mp = ip->i_mount;
329 int pathlen;
330
331 trace_xfs_inactive_symlink(ip);
332
333 if (xfs_is_shutdown(mp))
334 return -EIO;
335
336 xfs_ilock(ip, XFS_ILOCK_EXCL);
337 pathlen = (int)ip->i_disk_size;
338 ASSERT(pathlen);
339
340 if (pathlen <= 0 || pathlen > XFS_SYMLINK_MAXLEN) {
341 xfs_alert(mp, "%s: inode (0x%llx) bad symlink length (%d)",
342 __func__, (unsigned long long)ip->i_ino, pathlen);
343 xfs_iunlock(ip, XFS_ILOCK_EXCL);
344 ASSERT(0);
345 xfs_inode_mark_sick(ip, XFS_SICK_INO_SYMLINK);
346 return -EFSCORRUPTED;
347 }
348
349 /*
350 * Inline fork state gets removed by xfs_difree() so we have nothing to
351 * do here in that case.
352 */
353 if (ip->i_df.if_format == XFS_DINODE_FMT_LOCAL) {
354 xfs_iunlock(ip, XFS_ILOCK_EXCL);
355 return 0;
356 }
357
358 xfs_iunlock(ip, XFS_ILOCK_EXCL);
359
360 /* remove the remote symlink */
361 return xfs_inactive_symlink_rmt(ip);
362 }
363