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 29 int 30 xfs_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 81 int 82 xfs_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; 219 220 out_trans_cancel: 221 xfs_trans_cancel(tp); 222 out_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 } 232 out_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 */ 251 STATIC int 252 xfs_inactive_symlink_rmt( 253 struct xfs_inode *ip) 254 { 255 struct xfs_mount *mp = ip->i_mount; 256 struct xfs_trans *tp; 257 int error; 258 259 ASSERT(!xfs_need_iread_extents(&ip->i_df)); 260 /* 261 * We're freeing a symlink that has some 262 * blocks allocated to it. Free the 263 * blocks here. We know that we've got 264 * either 1 or 2 extents and that we can 265 * free them all in one bunmapi call. 266 */ 267 ASSERT(ip->i_df.if_nextents > 0 && ip->i_df.if_nextents <= 2); 268 269 error = xfs_trans_alloc(mp, &M_RES(mp)->tr_itruncate, 0, 0, 0, &tp); 270 if (error) 271 return error; 272 273 xfs_ilock(ip, XFS_ILOCK_EXCL); 274 xfs_trans_ijoin(tp, ip, 0); 275 276 /* 277 * Lock the inode, fix the size, turn it into a regular file and join it 278 * to the transaction. Hold it so in the normal path, we still have it 279 * locked for the second transaction. In the error paths we need it 280 * held so the cancel won't rele it, see below. 281 */ 282 ip->i_disk_size = 0; 283 VFS_I(ip)->i_mode = (VFS_I(ip)->i_mode & ~S_IFMT) | S_IFREG; 284 xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE); 285 286 error = xfs_symlink_remote_truncate(tp, ip); 287 if (error) 288 goto error_trans_cancel; 289 290 error = xfs_trans_commit(tp); 291 if (error) { 292 ASSERT(xfs_is_shutdown(mp)); 293 goto error_unlock; 294 } 295 296 /* 297 * Remove the memory for extent descriptions (just bookkeeping). 298 */ 299 if (ip->i_df.if_bytes) 300 xfs_idata_realloc(ip, -ip->i_df.if_bytes, XFS_DATA_FORK); 301 ASSERT(ip->i_df.if_bytes == 0); 302 303 xfs_iunlock(ip, XFS_ILOCK_EXCL); 304 return 0; 305 306 error_trans_cancel: 307 xfs_trans_cancel(tp); 308 error_unlock: 309 xfs_iunlock(ip, XFS_ILOCK_EXCL); 310 return error; 311 } 312 313 /* 314 * xfs_inactive_symlink - free a symlink 315 */ 316 int 317 xfs_inactive_symlink( 318 struct xfs_inode *ip) 319 { 320 struct xfs_mount *mp = ip->i_mount; 321 int pathlen; 322 323 trace_xfs_inactive_symlink(ip); 324 325 if (xfs_is_shutdown(mp)) 326 return -EIO; 327 328 xfs_ilock(ip, XFS_ILOCK_EXCL); 329 pathlen = (int)ip->i_disk_size; 330 ASSERT(pathlen); 331 332 if (pathlen <= 0 || pathlen > XFS_SYMLINK_MAXLEN) { 333 xfs_alert(mp, "%s: inode (0x%llx) bad symlink length (%d)", 334 __func__, (unsigned long long)ip->i_ino, pathlen); 335 xfs_iunlock(ip, XFS_ILOCK_EXCL); 336 ASSERT(0); 337 xfs_inode_mark_sick(ip, XFS_SICK_INO_SYMLINK); 338 return -EFSCORRUPTED; 339 } 340 341 /* 342 * Inline fork state gets removed by xfs_difree() so we have nothing to 343 * do here in that case. 344 */ 345 if (ip->i_df.if_format == XFS_DINODE_FMT_LOCAL) { 346 xfs_iunlock(ip, XFS_ILOCK_EXCL); 347 return 0; 348 } 349 350 xfs_iunlock(ip, XFS_ILOCK_EXCL); 351 352 /* remove the remote symlink */ 353 return xfs_inactive_symlink_rmt(ip); 354 } 355