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 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 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 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 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