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
 29int
 30xfs_readlink(
 31	struct xfs_inode	*ip,
 32	char			*link)
 33{
 34	struct xfs_mount	*mp = ip->i_mount;
 35	xfs_fsize_t		pathlen;
 36	int			error;
 37
 38	trace_xfs_readlink(ip);
 39
 40	if (xfs_is_shutdown(mp))
 41		return -EIO;
 42	if (xfs_ifork_zapped(ip, XFS_DATA_FORK))
 43		return -EIO;
 44
 45	xfs_ilock(ip, XFS_ILOCK_SHARED);
 46
 47	pathlen = ip->i_disk_size;
 48	if (!pathlen)
 49		goto out_corrupt;
 50
 51	if (pathlen < 0 || pathlen > XFS_SYMLINK_MAXLEN) {
 52		xfs_alert(mp, "%s: inode (%llu) bad symlink length (%lld)",
 53			 __func__, (unsigned long long) ip->i_ino,
 54			 (long long) pathlen);
 55		ASSERT(0);
 56		goto out_corrupt;
 57	}
 58
 59	if (ip->i_df.if_format == XFS_DINODE_FMT_LOCAL) {
 60		/*
 61		 * The VFS crashes on a NULL pointer, so return -EFSCORRUPTED
 62		 * if if_data is junk.
 63		 */
 64		if (XFS_IS_CORRUPT(ip->i_mount, !ip->i_df.if_data))
 65			goto out_corrupt;
 66
 67		memcpy(link, ip->i_df.if_data, pathlen + 1);
 68		error = 0;
 69	} else {
 70		error = xfs_symlink_remote_read(ip, link);
 71	}
 72
 73	xfs_iunlock(ip, XFS_ILOCK_SHARED);
 74	return error;
 75 out_corrupt:
 76	xfs_iunlock(ip, XFS_ILOCK_SHARED);
 77	xfs_inode_mark_sick(ip, XFS_SICK_INO_SYMLINK);
 78	return -EFSCORRUPTED;
 79}
 80
 81int
 82xfs_symlink(
 83	struct mnt_idmap	*idmap,
 84	struct xfs_inode	*dp,
 85	struct xfs_name		*link_name,
 86	const char		*target_path,
 87	umode_t			mode,
 88	struct xfs_inode	**ipp)
 89{
 90	struct xfs_mount	*mp = dp->i_mount;
 91	struct xfs_trans	*tp = NULL;
 92	struct xfs_inode	*ip = NULL;
 93	int			error = 0;
 94	int			pathlen;
 95	bool                    unlock_dp_on_error = false;
 96	xfs_filblks_t		fs_blocks;
 97	prid_t			prid;
 98	struct xfs_dquot	*udqp = NULL;
 99	struct xfs_dquot	*gdqp = NULL;
100	struct xfs_dquot	*pdqp = NULL;
101	uint			resblks;
102	xfs_ino_t		ino;
103
104	*ipp = NULL;
105
106	trace_xfs_symlink(dp, link_name);
107
108	if (xfs_is_shutdown(mp))
109		return -EIO;
110
111	/*
112	 * Check component lengths of the target path name.
113	 */
114	pathlen = strlen(target_path);
115	if (pathlen >= XFS_SYMLINK_MAXLEN)      /* total string too long */
116		return -ENAMETOOLONG;
117	ASSERT(pathlen > 0);
118
119	prid = xfs_get_initial_prid(dp);
120
121	/*
122	 * Make sure that we have allocated dquot(s) on disk.
123	 */
124	error = xfs_qm_vop_dqalloc(dp, mapped_fsuid(idmap, &init_user_ns),
125			mapped_fsgid(idmap, &init_user_ns), prid,
126			XFS_QMOPT_QUOTALL | XFS_QMOPT_INHERIT,
127			&udqp, &gdqp, &pdqp);
128	if (error)
129		return error;
130
131	/*
132	 * The symlink will fit into the inode data fork?
133	 * There can't be any attributes so we get the whole variable part.
134	 */
135	if (pathlen <= XFS_LITINO(mp))
136		fs_blocks = 0;
137	else
138		fs_blocks = xfs_symlink_blocks(mp, pathlen);
139	resblks = XFS_SYMLINK_SPACE_RES(mp, link_name->len, fs_blocks);
140
141	error = xfs_trans_alloc_icreate(mp, &M_RES(mp)->tr_symlink, udqp, gdqp,
142			pdqp, resblks, &tp);
143	if (error)
144		goto out_release_dquots;
145
146	xfs_ilock(dp, XFS_ILOCK_EXCL | XFS_ILOCK_PARENT);
147	unlock_dp_on_error = true;
148
149	/*
150	 * Check whether the directory allows new symlinks or not.
151	 */
152	if (dp->i_diflags & XFS_DIFLAG_NOSYMLINKS) {
153		error = -EPERM;
154		goto out_trans_cancel;
155	}
156
157	/*
158	 * Allocate an inode for the symlink.
159	 */
160	error = xfs_dialloc(&tp, dp->i_ino, S_IFLNK, &ino);
161	if (!error)
162		error = xfs_init_new_inode(idmap, tp, dp, ino,
163				S_IFLNK | (mode & ~S_IFMT), 1, 0, prid,
164				false, &ip);
165	if (error)
166		goto out_trans_cancel;
167
168	/*
169	 * Now we join the directory inode to the transaction.  We do not do it
170	 * earlier because xfs_dir_ialloc might commit the previous transaction
171	 * (and release all the locks).  An error from here on will result in
172	 * the transaction cancel unlocking dp so don't do it explicitly in the
173	 * error path.
174	 */
175	xfs_trans_ijoin(tp, dp, XFS_ILOCK_EXCL);
176	unlock_dp_on_error = false;
177
178	/*
179	 * Also attach the dquot(s) to it, if applicable.
180	 */
181	xfs_qm_vop_create_dqattach(tp, ip, udqp, gdqp, pdqp);
182
183	resblks -= XFS_IALLOC_SPACE_RES(mp);
184	error = xfs_symlink_write_target(tp, ip, target_path, pathlen,
185			fs_blocks, resblks);
186	if (error)
187		goto out_trans_cancel;
188	resblks -= fs_blocks;
189	i_size_write(VFS_I(ip), ip->i_disk_size);
190
191	/*
192	 * Create the directory entry for the symlink.
193	 */
194	error = xfs_dir_createname(tp, dp, link_name, ip->i_ino, resblks);
195	if (error)
196		goto out_trans_cancel;
197	xfs_trans_ichgtime(tp, dp, XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);
198	xfs_trans_log_inode(tp, dp, XFS_ILOG_CORE);
199	xfs_dir_update_hook(dp, ip, 1, link_name);
200
201	/*
202	 * If this is a synchronous mount, make sure that the
203	 * symlink transaction goes to disk before returning to
204	 * the user.
205	 */
206	if (xfs_has_wsync(mp) || xfs_has_dirsync(mp))
207		xfs_trans_set_sync(tp);
208
209	error = xfs_trans_commit(tp);
210	if (error)
211		goto out_release_inode;
212
213	xfs_qm_dqrele(udqp);
214	xfs_qm_dqrele(gdqp);
215	xfs_qm_dqrele(pdqp);
216
217	*ipp = ip;
218	return 0;
219
220out_trans_cancel:
221	xfs_trans_cancel(tp);
222out_release_inode:
223	/*
224	 * Wait until after the current transaction is aborted to finish the
225	 * setup of the inode and release the inode.  This prevents recursive
226	 * transactions and deadlocks from xfs_inactive.
227	 */
228	if (ip) {
229		xfs_finish_inode_setup(ip);
230		xfs_irele(ip);
231	}
232out_release_dquots:
233	xfs_qm_dqrele(udqp);
234	xfs_qm_dqrele(gdqp);
235	xfs_qm_dqrele(pdqp);
236
237	if (unlock_dp_on_error)
238		xfs_iunlock(dp, XFS_ILOCK_EXCL);
239	return error;
240}
241
242/*
243 * Free a symlink that has blocks associated with it.
244 *
245 * Note: zero length symlinks are not allowed to exist. When we set the size to
246 * zero, also change it to a regular file so that it does not get written to
247 * disk as a zero length symlink. The inode is on the unlinked list already, so
248 * userspace cannot find this inode anymore, so this change is not user visible
249 * but allows us to catch corrupt zero-length symlinks in the verifiers.
250 */
251STATIC int
252xfs_inactive_symlink_rmt(
253	struct xfs_inode *ip)
254{
255	struct xfs_buf	*bp;
256	int		done;
257	int		error;
258	int		i;
259	xfs_mount_t	*mp;
260	xfs_bmbt_irec_t	mval[XFS_SYMLINK_MAPS];
261	int		nmaps;
262	int		size;
263	xfs_trans_t	*tp;
264
265	mp = ip->i_mount;
266	ASSERT(!xfs_need_iread_extents(&ip->i_df));
267	/*
268	 * We're freeing a symlink that has some
269	 * blocks allocated to it.  Free the
270	 * blocks here.  We know that we've got
271	 * either 1 or 2 extents and that we can
272	 * free them all in one bunmapi call.
273	 */
274	ASSERT(ip->i_df.if_nextents > 0 && ip->i_df.if_nextents <= 2);
275
276	error = xfs_trans_alloc(mp, &M_RES(mp)->tr_itruncate, 0, 0, 0, &tp);
277	if (error)
278		return error;
279
280	xfs_ilock(ip, XFS_ILOCK_EXCL);
281	xfs_trans_ijoin(tp, ip, 0);
282
283	/*
284	 * Lock the inode, fix the size, turn it into a regular file and join it
285	 * to the transaction.  Hold it so in the normal path, we still have it
286	 * locked for the second transaction.  In the error paths we need it
287	 * held so the cancel won't rele it, see below.
288	 */
289	size = (int)ip->i_disk_size;
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	 * Find the block(s) so we can inval and unmap them.
295	 */
296	done = 0;
297	nmaps = ARRAY_SIZE(mval);
298	error = xfs_bmapi_read(ip, 0, xfs_symlink_blocks(mp, size),
299				mval, &nmaps, 0);
300	if (error)
301		goto error_trans_cancel;
302	/*
303	 * Invalidate the block(s). No validation is done.
304	 */
305	for (i = 0; i < nmaps; i++) {
306		error = xfs_trans_get_buf(tp, mp->m_ddev_targp,
307				XFS_FSB_TO_DADDR(mp, mval[i].br_startblock),
308				XFS_FSB_TO_BB(mp, mval[i].br_blockcount), 0,
309				&bp);
310		if (error)
311			goto error_trans_cancel;
312		xfs_trans_binval(tp, bp);
313	}
314	/*
315	 * Unmap the dead block(s) to the dfops.
316	 */
317	error = xfs_bunmapi(tp, ip, 0, size, 0, nmaps, &done);
318	if (error)
319		goto error_trans_cancel;
320	ASSERT(done);
321
322	/*
323	 * Commit the transaction. This first logs the EFI and the inode, then
324	 * rolls and commits the transaction that frees the extents.
325	 */
326	xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
327	error = xfs_trans_commit(tp);
328	if (error) {
329		ASSERT(xfs_is_shutdown(mp));
330		goto error_unlock;
331	}
332
333	/*
334	 * Remove the memory for extent descriptions (just bookkeeping).
335	 */
336	if (ip->i_df.if_bytes)
337		xfs_idata_realloc(ip, -ip->i_df.if_bytes, XFS_DATA_FORK);
338	ASSERT(ip->i_df.if_bytes == 0);
339
340	xfs_iunlock(ip, XFS_ILOCK_EXCL);
341	return 0;
342
343error_trans_cancel:
344	xfs_trans_cancel(tp);
345error_unlock:
346	xfs_iunlock(ip, XFS_ILOCK_EXCL);
347	return error;
348}
349
350/*
351 * xfs_inactive_symlink - free a symlink
352 */
353int
354xfs_inactive_symlink(
355	struct xfs_inode	*ip)
356{
357	struct xfs_mount	*mp = ip->i_mount;
358	int			pathlen;
359
360	trace_xfs_inactive_symlink(ip);
361
362	if (xfs_is_shutdown(mp))
363		return -EIO;
364
365	xfs_ilock(ip, XFS_ILOCK_EXCL);
366	pathlen = (int)ip->i_disk_size;
367	ASSERT(pathlen);
368
369	if (pathlen <= 0 || pathlen > XFS_SYMLINK_MAXLEN) {
370		xfs_alert(mp, "%s: inode (0x%llx) bad symlink length (%d)",
371			 __func__, (unsigned long long)ip->i_ino, pathlen);
372		xfs_iunlock(ip, XFS_ILOCK_EXCL);
373		ASSERT(0);
374		xfs_inode_mark_sick(ip, XFS_SICK_INO_SYMLINK);
375		return -EFSCORRUPTED;
376	}
377
378	/*
379	 * Inline fork state gets removed by xfs_difree() so we have nothing to
380	 * do here in that case.
381	 */
382	if (ip->i_df.if_format == XFS_DINODE_FMT_LOCAL) {
383		xfs_iunlock(ip, XFS_ILOCK_EXCL);
384		return 0;
385	}
386
387	xfs_iunlock(ip, XFS_ILOCK_EXCL);
388
389	/* remove the remote symlink */
390	return xfs_inactive_symlink_rmt(ip);
391}