diff options
Diffstat (limited to '')
-rw-r--r-- | fs/xfs/xfs_symlink.c | 512 |
1 files changed, 512 insertions, 0 deletions
diff --git a/fs/xfs/xfs_symlink.c b/fs/xfs/xfs_symlink.c new file mode 100644 index 000000000..8389f3ef8 --- /dev/null +++ b/fs/xfs/xfs_symlink.c @@ -0,0 +1,512 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (c) 2000-2006 Silicon Graphics, Inc. + * Copyright (c) 2012-2013 Red Hat, Inc. + * All rights reserved. + */ +#include "xfs.h" +#include "xfs_shared.h" +#include "xfs_fs.h" +#include "xfs_format.h" +#include "xfs_log_format.h" +#include "xfs_trans_resv.h" +#include "xfs_bit.h" +#include "xfs_mount.h" +#include "xfs_dir2.h" +#include "xfs_inode.h" +#include "xfs_bmap.h" +#include "xfs_bmap_btree.h" +#include "xfs_quota.h" +#include "xfs_symlink.h" +#include "xfs_trans_space.h" +#include "xfs_trace.h" +#include "xfs_trans.h" +#include "xfs_ialloc.h" +#include "xfs_error.h" + +/* ----- Kernel only functions below ----- */ +int +xfs_readlink_bmap_ilocked( + struct xfs_inode *ip, + char *link) +{ + struct xfs_mount *mp = ip->i_mount; + struct xfs_bmbt_irec mval[XFS_SYMLINK_MAPS]; + struct xfs_buf *bp; + xfs_daddr_t d; + char *cur_chunk; + int pathlen = ip->i_disk_size; + int nmaps = XFS_SYMLINK_MAPS; + int byte_cnt; + int n; + int error = 0; + int fsblocks = 0; + int offset; + + ASSERT(xfs_isilocked(ip, XFS_ILOCK_SHARED | XFS_ILOCK_EXCL)); + + fsblocks = xfs_symlink_blocks(mp, pathlen); + error = xfs_bmapi_read(ip, 0, fsblocks, mval, &nmaps, 0); + if (error) + goto out; + + offset = 0; + for (n = 0; n < nmaps; n++) { + d = XFS_FSB_TO_DADDR(mp, mval[n].br_startblock); + byte_cnt = XFS_FSB_TO_B(mp, mval[n].br_blockcount); + + error = xfs_buf_read(mp->m_ddev_targp, d, BTOBB(byte_cnt), 0, + &bp, &xfs_symlink_buf_ops); + if (error) + return error; + byte_cnt = XFS_SYMLINK_BUF_SPACE(mp, byte_cnt); + if (pathlen < byte_cnt) + byte_cnt = pathlen; + + cur_chunk = bp->b_addr; + if (xfs_has_crc(mp)) { + if (!xfs_symlink_hdr_ok(ip->i_ino, offset, + byte_cnt, bp)) { + error = -EFSCORRUPTED; + xfs_alert(mp, +"symlink header does not match required off/len/owner (0x%x/Ox%x,0x%llx)", + offset, byte_cnt, ip->i_ino); + xfs_buf_relse(bp); + goto out; + + } + + cur_chunk += sizeof(struct xfs_dsymlink_hdr); + } + + memcpy(link + offset, cur_chunk, byte_cnt); + + pathlen -= byte_cnt; + offset += byte_cnt; + + xfs_buf_relse(bp); + } + ASSERT(pathlen == 0); + + link[ip->i_disk_size] = '\0'; + error = 0; + + out: + return error; +} + +int +xfs_readlink( + struct xfs_inode *ip, + char *link) +{ + struct xfs_mount *mp = ip->i_mount; + xfs_fsize_t pathlen; + int error = -EFSCORRUPTED; + + trace_xfs_readlink(ip); + + if (xfs_is_shutdown(mp)) + return -EIO; + + xfs_ilock(ip, XFS_ILOCK_SHARED); + + pathlen = ip->i_disk_size; + if (!pathlen) + goto out; + + if (pathlen < 0 || pathlen > XFS_SYMLINK_MAXLEN) { + xfs_alert(mp, "%s: inode (%llu) bad symlink length (%lld)", + __func__, (unsigned long long) ip->i_ino, + (long long) pathlen); + ASSERT(0); + goto out; + } + + if (ip->i_df.if_format == XFS_DINODE_FMT_LOCAL) { + /* + * The VFS crashes on a NULL pointer, so return -EFSCORRUPTED + * if if_data is junk. + */ + if (XFS_IS_CORRUPT(ip->i_mount, !ip->i_df.if_u1.if_data)) + goto out; + + memcpy(link, ip->i_df.if_u1.if_data, pathlen + 1); + error = 0; + } else { + error = xfs_readlink_bmap_ilocked(ip, link); + } + + out: + xfs_iunlock(ip, XFS_ILOCK_SHARED); + return error; +} + +int +xfs_symlink( + struct user_namespace *mnt_userns, + struct xfs_inode *dp, + struct xfs_name *link_name, + const char *target_path, + umode_t mode, + struct xfs_inode **ipp) +{ + struct xfs_mount *mp = dp->i_mount; + struct xfs_trans *tp = NULL; + struct xfs_inode *ip = NULL; + int error = 0; + int pathlen; + bool unlock_dp_on_error = false; + xfs_fileoff_t first_fsb; + xfs_filblks_t fs_blocks; + int nmaps; + struct xfs_bmbt_irec mval[XFS_SYMLINK_MAPS]; + xfs_daddr_t d; + const char *cur_chunk; + int byte_cnt; + int n; + struct xfs_buf *bp; + prid_t prid; + struct xfs_dquot *udqp = NULL; + struct xfs_dquot *gdqp = NULL; + struct xfs_dquot *pdqp = NULL; + uint resblks; + xfs_ino_t ino; + + *ipp = NULL; + + trace_xfs_symlink(dp, link_name); + + if (xfs_is_shutdown(mp)) + return -EIO; + + /* + * Check component lengths of the target path name. + */ + pathlen = strlen(target_path); + if (pathlen >= XFS_SYMLINK_MAXLEN) /* total string too long */ + return -ENAMETOOLONG; + ASSERT(pathlen > 0); + + prid = xfs_get_initial_prid(dp); + + /* + * Make sure that we have allocated dquot(s) on disk. + */ + error = xfs_qm_vop_dqalloc(dp, mapped_fsuid(mnt_userns, &init_user_ns), + mapped_fsgid(mnt_userns, &init_user_ns), prid, + XFS_QMOPT_QUOTALL | XFS_QMOPT_INHERIT, + &udqp, &gdqp, &pdqp); + if (error) + return error; + + /* + * The symlink will fit into the inode data fork? + * There can't be any attributes so we get the whole variable part. + */ + if (pathlen <= XFS_LITINO(mp)) + fs_blocks = 0; + else + fs_blocks = xfs_symlink_blocks(mp, pathlen); + resblks = XFS_SYMLINK_SPACE_RES(mp, link_name->len, fs_blocks); + + error = xfs_trans_alloc_icreate(mp, &M_RES(mp)->tr_symlink, udqp, gdqp, + pdqp, resblks, &tp); + if (error) + goto out_release_dquots; + + xfs_ilock(dp, XFS_ILOCK_EXCL | XFS_ILOCK_PARENT); + unlock_dp_on_error = true; + + /* + * Check whether the directory allows new symlinks or not. + */ + if (dp->i_diflags & XFS_DIFLAG_NOSYMLINKS) { + error = -EPERM; + goto out_trans_cancel; + } + + /* + * Allocate an inode for the symlink. + */ + error = xfs_dialloc(&tp, dp->i_ino, S_IFLNK, &ino); + if (!error) + error = xfs_init_new_inode(mnt_userns, tp, dp, ino, + S_IFLNK | (mode & ~S_IFMT), 1, 0, prid, + false, &ip); + if (error) + goto out_trans_cancel; + + /* + * Now we join the directory inode to the transaction. We do not do it + * earlier because xfs_dir_ialloc might commit the previous transaction + * (and release all the locks). An error from here on will result in + * the transaction cancel unlocking dp so don't do it explicitly in the + * error path. + */ + xfs_trans_ijoin(tp, dp, XFS_ILOCK_EXCL); + unlock_dp_on_error = false; + + /* + * Also attach the dquot(s) to it, if applicable. + */ + xfs_qm_vop_create_dqattach(tp, ip, udqp, gdqp, pdqp); + + resblks -= XFS_IALLOC_SPACE_RES(mp); + /* + * If the symlink will fit into the inode, write it inline. + */ + if (pathlen <= xfs_inode_data_fork_size(ip)) { + xfs_init_local_fork(ip, XFS_DATA_FORK, target_path, pathlen); + + ip->i_disk_size = pathlen; + ip->i_df.if_format = XFS_DINODE_FMT_LOCAL; + xfs_trans_log_inode(tp, ip, XFS_ILOG_DDATA | XFS_ILOG_CORE); + } else { + int offset; + + first_fsb = 0; + nmaps = XFS_SYMLINK_MAPS; + + error = xfs_bmapi_write(tp, ip, first_fsb, fs_blocks, + XFS_BMAPI_METADATA, resblks, mval, &nmaps); + if (error) + goto out_trans_cancel; + + resblks -= fs_blocks; + ip->i_disk_size = pathlen; + xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE); + + cur_chunk = target_path; + offset = 0; + for (n = 0; n < nmaps; n++) { + char *buf; + + d = XFS_FSB_TO_DADDR(mp, mval[n].br_startblock); + byte_cnt = XFS_FSB_TO_B(mp, mval[n].br_blockcount); + error = xfs_trans_get_buf(tp, mp->m_ddev_targp, d, + BTOBB(byte_cnt), 0, &bp); + if (error) + goto out_trans_cancel; + bp->b_ops = &xfs_symlink_buf_ops; + + byte_cnt = XFS_SYMLINK_BUF_SPACE(mp, byte_cnt); + byte_cnt = min(byte_cnt, pathlen); + + buf = bp->b_addr; + buf += xfs_symlink_hdr_set(mp, ip->i_ino, offset, + byte_cnt, bp); + + memcpy(buf, cur_chunk, byte_cnt); + + cur_chunk += byte_cnt; + pathlen -= byte_cnt; + offset += byte_cnt; + + xfs_trans_buf_set_type(tp, bp, XFS_BLFT_SYMLINK_BUF); + xfs_trans_log_buf(tp, bp, 0, (buf + byte_cnt - 1) - + (char *)bp->b_addr); + } + ASSERT(pathlen == 0); + } + i_size_write(VFS_I(ip), ip->i_disk_size); + + /* + * Create the directory entry for the symlink. + */ + error = xfs_dir_createname(tp, dp, link_name, ip->i_ino, resblks); + if (error) + goto out_trans_cancel; + xfs_trans_ichgtime(tp, dp, XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG); + xfs_trans_log_inode(tp, dp, XFS_ILOG_CORE); + + /* + * If this is a synchronous mount, make sure that the + * symlink transaction goes to disk before returning to + * the user. + */ + if (xfs_has_wsync(mp) || xfs_has_dirsync(mp)) + xfs_trans_set_sync(tp); + + error = xfs_trans_commit(tp); + if (error) + goto out_release_inode; + + xfs_qm_dqrele(udqp); + xfs_qm_dqrele(gdqp); + xfs_qm_dqrele(pdqp); + + *ipp = ip; + return 0; + +out_trans_cancel: + xfs_trans_cancel(tp); +out_release_inode: + /* + * Wait until after the current transaction is aborted to finish the + * setup of the inode and release the inode. This prevents recursive + * transactions and deadlocks from xfs_inactive. + */ + if (ip) { + xfs_finish_inode_setup(ip); + xfs_irele(ip); + } +out_release_dquots: + xfs_qm_dqrele(udqp); + xfs_qm_dqrele(gdqp); + xfs_qm_dqrele(pdqp); + + if (unlock_dp_on_error) + xfs_iunlock(dp, XFS_ILOCK_EXCL); + return error; +} + +/* + * Free a symlink that has blocks associated with it. + * + * Note: zero length symlinks are not allowed to exist. When we set the size to + * zero, also change it to a regular file so that it does not get written to + * disk as a zero length symlink. The inode is on the unlinked list already, so + * userspace cannot find this inode anymore, so this change is not user visible + * but allows us to catch corrupt zero-length symlinks in the verifiers. + */ +STATIC int +xfs_inactive_symlink_rmt( + struct xfs_inode *ip) +{ + struct xfs_buf *bp; + int done; + int error; + int i; + xfs_mount_t *mp; + xfs_bmbt_irec_t mval[XFS_SYMLINK_MAPS]; + int nmaps; + int size; + xfs_trans_t *tp; + + mp = ip->i_mount; + ASSERT(!xfs_need_iread_extents(&ip->i_df)); + /* + * We're freeing a symlink that has some + * blocks allocated to it. Free the + * blocks here. We know that we've got + * either 1 or 2 extents and that we can + * free them all in one bunmapi call. + */ + ASSERT(ip->i_df.if_nextents > 0 && ip->i_df.if_nextents <= 2); + + error = xfs_trans_alloc(mp, &M_RES(mp)->tr_itruncate, 0, 0, 0, &tp); + if (error) + return error; + + xfs_ilock(ip, XFS_ILOCK_EXCL); + xfs_trans_ijoin(tp, ip, 0); + + /* + * Lock the inode, fix the size, turn it into a regular file and join it + * to the transaction. Hold it so in the normal path, we still have it + * locked for the second transaction. In the error paths we need it + * held so the cancel won't rele it, see below. + */ + size = (int)ip->i_disk_size; + ip->i_disk_size = 0; + VFS_I(ip)->i_mode = (VFS_I(ip)->i_mode & ~S_IFMT) | S_IFREG; + xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE); + /* + * Find the block(s) so we can inval and unmap them. + */ + done = 0; + nmaps = ARRAY_SIZE(mval); + error = xfs_bmapi_read(ip, 0, xfs_symlink_blocks(mp, size), + mval, &nmaps, 0); + if (error) + goto error_trans_cancel; + /* + * Invalidate the block(s). No validation is done. + */ + for (i = 0; i < nmaps; i++) { + error = xfs_trans_get_buf(tp, mp->m_ddev_targp, + XFS_FSB_TO_DADDR(mp, mval[i].br_startblock), + XFS_FSB_TO_BB(mp, mval[i].br_blockcount), 0, + &bp); + if (error) + goto error_trans_cancel; + xfs_trans_binval(tp, bp); + } + /* + * Unmap the dead block(s) to the dfops. + */ + error = xfs_bunmapi(tp, ip, 0, size, 0, nmaps, &done); + if (error) + goto error_trans_cancel; + ASSERT(done); + + /* + * Commit the transaction. This first logs the EFI and the inode, then + * rolls and commits the transaction that frees the extents. + */ + xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE); + error = xfs_trans_commit(tp); + if (error) { + ASSERT(xfs_is_shutdown(mp)); + goto error_unlock; + } + + /* + * Remove the memory for extent descriptions (just bookkeeping). + */ + if (ip->i_df.if_bytes) + xfs_idata_realloc(ip, -ip->i_df.if_bytes, XFS_DATA_FORK); + ASSERT(ip->i_df.if_bytes == 0); + + xfs_iunlock(ip, XFS_ILOCK_EXCL); + return 0; + +error_trans_cancel: + xfs_trans_cancel(tp); +error_unlock: + xfs_iunlock(ip, XFS_ILOCK_EXCL); + return error; +} + +/* + * xfs_inactive_symlink - free a symlink + */ +int +xfs_inactive_symlink( + struct xfs_inode *ip) +{ + struct xfs_mount *mp = ip->i_mount; + int pathlen; + + trace_xfs_inactive_symlink(ip); + + if (xfs_is_shutdown(mp)) + return -EIO; + + xfs_ilock(ip, XFS_ILOCK_EXCL); + pathlen = (int)ip->i_disk_size; + ASSERT(pathlen); + + if (pathlen <= 0 || pathlen > XFS_SYMLINK_MAXLEN) { + xfs_alert(mp, "%s: inode (0x%llx) bad symlink length (%d)", + __func__, (unsigned long long)ip->i_ino, pathlen); + xfs_iunlock(ip, XFS_ILOCK_EXCL); + ASSERT(0); + return -EFSCORRUPTED; + } + + /* + * Inline fork state gets removed by xfs_difree() so we have nothing to + * do here in that case. + */ + if (ip->i_df.if_format == XFS_DINODE_FMT_LOCAL) { + xfs_iunlock(ip, XFS_ILOCK_EXCL); + return 0; + } + + xfs_iunlock(ip, XFS_ILOCK_EXCL); + + /* remove the remote symlink */ + return xfs_inactive_symlink_rmt(ip); +} |