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 "libxfs_priv.h"
  20 #include "xfs_fs.h"
  21 #include "xfs_format.h"
  22 #include "xfs_log_format.h"
  23 #include "xfs_shared.h"
  24 #include "xfs_trans_resv.h"
  25 #include "xfs_mount.h"
  26 #include "xfs_bmap_btree.h"
  27 #include "xfs_inode.h"
  28 #include "xfs_trace.h"
  29 #include "xfs_cksum.h"
  30 #include "xfs_trans.h"
  31
  32
  33 /*
  34  * Each contiguous block has a header, so it is not just a simple pathlen
  35  * to FSB conversion.
  36  */
  37 int
  38 xfs_symlink_blocks(
  39         struct xfs_mount *mp,
  40         int             pathlen)
  41 {
  42         int buflen = XFS_SYMLINK_BUF_SPACE(mp, mp->m_sb.sb_blocksize);
  43
  44         return (pathlen + buflen - 1) / buflen;
  45 }
  46
  47 int
  48 xfs_symlink_hdr_set(
  49         struct xfs_mount        *mp,
  50         xfs_ino_t               ino,
  51         uint32_t                offset,
  52         uint32_t                size,
  53         struct xfs_buf          *bp)
  54 {
  55         struct xfs_dsymlink_hdr *dsl = bp->b_addr;
  56
  57         if (!xfs_sb_version_hascrc(&mp->m_sb))
  58                 return 0;
  59
  60         dsl->sl_magic = cpu_to_be32(XFS_SYMLINK_MAGIC);
  61         dsl->sl_offset = cpu_to_be32(offset);
  62         dsl->sl_bytes = cpu_to_be32(size);
  63         uuid_copy(&dsl->sl_uuid, &mp->m_sb.sb_meta_uuid);
  64         dsl->sl_owner = cpu_to_be64(ino);
  65         dsl->sl_blkno = cpu_to_be64(bp->b_bn);
  66         bp->b_ops = &xfs_symlink_buf_ops;
  67
  68         return sizeof(struct xfs_dsymlink_hdr);
  69 }
  70
  71 /*
  72  * Checking of the symlink header is split into two parts. the verifier does
  73  * CRC, location and bounds checking, the unpacking function checks the path
  74  * parameters and owner.
  75  */
  76 bool
  77 xfs_symlink_hdr_ok(
  78         xfs_ino_t               ino,
  79         uint32_t                offset,
  80         uint32_t                size,
  81         struct xfs_buf          *bp)
  82 {
  83         struct xfs_dsymlink_hdr *dsl = bp->b_addr;
  84
  85         if (offset != be32_to_cpu(dsl->sl_offset))
  86                 return false;
  87         if (size != be32_to_cpu(dsl->sl_bytes))
  88                 return false;
  89         if (ino != be64_to_cpu(dsl->sl_owner))
  90                 return false;
  91
  92         /* ok */
  93         return true;
  94 }
  95
  96 static bool
  97 xfs_symlink_verify(
  98         struct xfs_buf          *bp)
  99 {
 100         struct xfs_mount        *mp = bp->b_target->bt_mount;
 101         struct xfs_dsymlink_hdr *dsl = bp->b_addr;
 102
 103         if (!xfs_sb_version_hascrc(&mp->m_sb))
 104                 return false;
 105         if (dsl->sl_magic != cpu_to_be32(XFS_SYMLINK_MAGIC))
 106                 return false;
 107         if (!uuid_equal(&dsl->sl_uuid, &mp->m_sb.sb_meta_uuid))
 108                 return false;
 109         if (bp->b_bn != be64_to_cpu(dsl->sl_blkno))
 110                 return false;
 111         if (be32_to_cpu(dsl->sl_offset) +
 112                                 be32_to_cpu(dsl->sl_bytes) >= MAXPATHLEN)
 113                 return false;
 114         if (dsl->sl_owner == 0)
 115                 return false;
 116
 117         return true;
 118 }
 119
 120 static void
 121 xfs_symlink_read_verify(
 122         struct xfs_buf  *bp)
 123 {
 124         struct xfs_mount *mp = bp->b_target->bt_mount;
 125
 126         /* no verification of non-crc buffers */
 127         if (!xfs_sb_version_hascrc(&mp->m_sb))
 128                 return;
 129
 130         if (!xfs_buf_verify_cksum(bp, XFS_SYMLINK_CRC_OFF))
 131                 xfs_buf_ioerror(bp, -EFSBADCRC);
 132         else if (!xfs_symlink_verify(bp))
 133                 xfs_buf_ioerror(bp, -EFSCORRUPTED);
 134
 135         if (bp->b_error)
 136                 xfs_verifier_error(bp);
 137 }
 138
 139 static void
 140 xfs_symlink_write_verify(
 141         struct xfs_buf  *bp)
 142 {
 143         struct xfs_mount *mp = bp->b_target->bt_mount;
 144         struct xfs_buf_log_item *bip = bp->b_fspriv;
 145
 146         /* no verification of non-crc buffers */
 147         if (!xfs_sb_version_hascrc(&mp->m_sb))
 148                 return;
 149
 150         if (!xfs_symlink_verify(bp)) {
 151                 xfs_buf_ioerror(bp, -EFSCORRUPTED);
 152                 xfs_verifier_error(bp);
 153                 return;
 154         }
 155
 156         if (bip) {
 157                 struct xfs_dsymlink_hdr *dsl = bp->b_addr;
 158                 dsl->sl_lsn = cpu_to_be64(bip->bli_item.li_lsn);
 159         }
 160         xfs_buf_update_cksum(bp, XFS_SYMLINK_CRC_OFF);
 161 }
 162
 163 const struct xfs_buf_ops xfs_symlink_buf_ops = {
 164         .verify_read = xfs_symlink_read_verify,
 165         .verify_write = xfs_symlink_write_verify,
 166 };
 167
 168 void
 169 xfs_symlink_local_to_remote(
 170         struct xfs_trans        *tp,
 171         struct xfs_buf          *bp,
 172         struct xfs_inode        *ip,
 173         struct xfs_ifork        *ifp)
 174 {
 175         struct xfs_mount        *mp = ip->i_mount;
 176         char                    *buf;
 177
 178         xfs_trans_buf_set_type(tp, bp, XFS_BLFT_SYMLINK_BUF);
 179
 180         if (!xfs_sb_version_hascrc(&mp->m_sb)) {
 181                 bp->b_ops = NULL;
 182                 memcpy(bp->b_addr, ifp->if_u1.if_data, ifp->if_bytes);
 183                 return;
 184         }
 185
 186         /*
 187          * As this symlink fits in an inode literal area, it must also fit in
 188          * the smallest buffer the filesystem supports.
 189          */
 190         ASSERT(BBTOB(bp->b_length) >=
 191                         ifp->if_bytes + sizeof(struct xfs_dsymlink_hdr));
 192
 193         bp->b_ops = &xfs_symlink_buf_ops;
 194
 195         buf = bp->b_addr;
 196         buf += xfs_symlink_hdr_set(mp, ip->i_ino, 0, ifp->if_bytes, bp);
 197         memcpy(buf, ifp->if_u1.if_data, ifp->if_bytes);
 198 }