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
 31int
 32xfs_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
 83int
 84xfs_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
225out_trans_cancel:
226	xfs_trans_cancel(tp);
227out_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	}
238out_parent:
239	xfs_parent_finish(mp, du.ppargs);
240out_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 */
259STATIC int
260xfs_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
314error_trans_cancel:
315	xfs_trans_cancel(tp);
316error_unlock:
317	xfs_iunlock(ip, XFS_ILOCK_EXCL);
318	return error;
319}
320
321/*
322 * xfs_inactive_symlink - free a symlink
323 */
324int
325xfs_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}