libxfs/xfs_symlink_remote.c

   1 /*
   2  * Copyright (c) 2000-2006 Silicon Graphics, Inc.
   3  * Copyright (c) 2012-2013 Red Hat, Inc.
   4  * All rights reserved.
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License as
   8  * published by the Free Software Foundation.
   9  *
  10  * This program is distributed in the hope that it would be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program; if not, write the Free Software Foundation,
  17  * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  18  */
  19 #include <xfs.h>
  20
  21 /*
  22  * Each contiguous block has a header, so it is not just a simple pathlen
  23  * to FSB conversion.
  24  */
  25 int
  26 xfs_symlink_blocks(
  27         struct xfs_mount *mp,
  28         int             pathlen)
  29 {
  30         int buflen = XFS_SYMLINK_BUF_SPACE(mp, mp->m_sb.sb_blocksize);
  31
  32         return (pathlen + buflen - 1) / buflen;
  33 }
  34
  35 int
  36 xfs_symlink_hdr_set(
  37         struct xfs_mount        *mp,
  38         xfs_ino_t               ino,
  39         uint32_t                offset,
  40         uint32_t                size,
  41         struct xfs_buf          *bp)
  42 {
  43         struct xfs_dsymlink_hdr *dsl = bp->b_addr;
  44
  45         if (!xfs_sb_version_hascrc(&mp->m_sb))
  46                 return 0;
  47
  48         dsl->sl_magic = cpu_to_be32(XFS_SYMLINK_MAGIC);
  49         dsl->sl_offset = cpu_to_be32(offset);
  50         dsl->sl_bytes = cpu_to_be32(size);
  51         uuid_copy(&dsl->sl_uuid, &mp->m_sb.sb_uuid);
  52         dsl->sl_owner = cpu_to_be64(ino);
  53         dsl->sl_blkno = cpu_to_be64(bp->b_bn);
  54         bp->b_ops = &xfs_symlink_buf_ops;
  55
  56         return sizeof(struct xfs_dsymlink_hdr);
  57 }
  58
  59 /*
  60  * Checking of the symlink header is split into two parts. the verifier does
  61  * CRC, location and bounds checking, the unpacking function checks the path
  62  * parameters and owner.
  63  */
  64 bool
  65 xfs_symlink_hdr_ok(
  66         struct xfs_mount        *mp,
  67         xfs_ino_t               ino,
  68         uint32_t                offset,
  69         uint32_t                size,
  70         struct xfs_buf          *bp)
  71 {
  72         struct xfs_dsymlink_hdr *dsl = bp->b_addr;
  73
  74         if (offset != be32_to_cpu(dsl->sl_offset))
  75                 return false;
  76         if (size != be32_to_cpu(dsl->sl_bytes))
  77                 return false;
  78         if (ino != be64_to_cpu(dsl->sl_owner))
  79                 return false;
  80
  81         /* ok */
  82         return true;
  83 }
  84
  85 static bool
  86 xfs_symlink_verify(
  87         struct xfs_buf          *bp)
  88 {
  89         struct xfs_mount        *mp = bp->b_target->bt_mount;
  90         struct xfs_dsymlink_hdr *dsl = bp->b_addr;
  91
  92         if (!xfs_sb_version_hascrc(&mp->m_sb))
  93                 return false;
  94         if (dsl->sl_magic != cpu_to_be32(XFS_SYMLINK_MAGIC))
  95                 return false;
  96         if (!uuid_equal(&dsl->sl_uuid, &mp->m_sb.sb_uuid))
  97                 return false;
  98         if (bp->b_bn != be64_to_cpu(dsl->sl_blkno))
  99                 return false;
 100         if (be32_to_cpu(dsl->sl_offset) +
 101                                 be32_to_cpu(dsl->sl_bytes) >= MAXPATHLEN)
 102                 return false;
 103         if (dsl->sl_owner == 0)
 104                 return false;
 105
 106         return true;
 107 }
 108
 109 static void
 110 xfs_symlink_read_verify(
 111         struct xfs_buf  *bp)
 112 {
 113         struct xfs_mount *mp = bp->b_target->bt_mount;
 114
 115         /* no verification of non-crc buffers */
 116         if (!xfs_sb_version_hascrc(&mp->m_sb))
 117                 return;
 118
 119         if (!xfs_verify_cksum(bp->b_addr, BBTOB(bp->b_length),
 120                                   offsetof(struct xfs_dsymlink_hdr, sl_crc)) ||
 121             !xfs_symlink_verify(bp)) {
 122                 XFS_CORRUPTION_ERROR(__func__, XFS_ERRLEVEL_LOW, mp, bp->b_addr);
 123                 xfs_buf_ioerror(bp, EFSCORRUPTED);
 124         }
 125 }
 126
 127 static void
 128 xfs_symlink_write_verify(
 129         struct xfs_buf  *bp)
 130 {
 131         struct xfs_mount *mp = bp->b_target->bt_mount;
 132         struct xfs_buf_log_item *bip = bp->b_fspriv;
 133
 134         /* no verification of non-crc buffers */
 135         if (!xfs_sb_version_hascrc(&mp->m_sb))
 136                 return;
 137
 138         if (!xfs_symlink_verify(bp)) {
 139                 XFS_CORRUPTION_ERROR(__func__, XFS_ERRLEVEL_LOW, mp, bp->b_addr);
 140                 xfs_buf_ioerror(bp, EFSCORRUPTED);
 141                 return;
 142         }
 143
 144         if (bip) {
 145                 struct xfs_dsymlink_hdr *dsl = bp->b_addr;
 146                 dsl->sl_lsn = cpu_to_be64(bip->bli_item.li_lsn);
 147         }
 148         xfs_update_cksum(bp->b_addr, BBTOB(bp->b_length),
 149                          offsetof(struct xfs_dsymlink_hdr, sl_crc));
 150 }
 151
 152 const struct xfs_buf_ops xfs_symlink_buf_ops = {
 153         .verify_read = xfs_symlink_read_verify,
 154         .verify_write = xfs_symlink_write_verify,
 155 };
 156
 157 void
 158 xfs_symlink_local_to_remote(
 159         struct xfs_trans        *tp,
 160         struct xfs_buf          *bp,
 161         struct xfs_inode        *ip,
 162         struct xfs_ifork        *ifp)
 163 {
 164         struct xfs_mount        *mp = ip->i_mount;
 165         char                    *buf;
 166
 167         if (!xfs_sb_version_hascrc(&mp->m_sb)) {
 168                 bp->b_ops = NULL;
 169                 memcpy(bp->b_addr, ifp->if_u1.if_data, ifp->if_bytes);
 170                 return;
 171         }
 172
 173         /*
 174          * As this symlink fits in an inode literal area, it must also fit in
 175          * the smallest buffer the filesystem supports.
 176          */
 177         ASSERT(BBTOB(bp->b_length) >=
 178                         ifp->if_bytes + sizeof(struct xfs_dsymlink_hdr));
 179
 180         bp->b_ops = &xfs_symlink_buf_ops;
 181
 182         buf = bp->b_addr;
 183         buf += xfs_symlink_hdr_set(mp, ip->i_ino, 0, ifp->if_bytes, bp);
 184         memcpy(buf, ifp->if_u1.if_data, ifp->if_bytes);
 185 }