fs/xfs/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 #include "xfs_fs.h"
  21 #include "xfs_format.h"
  22 #include "xfs_log.h"
  23 #include "xfs_trans.h"
  24 #include "xfs_ag.h"
  25 #include "xfs_sb.h"
  26 #include "xfs_mount.h"
  27 #include "xfs_bmap_btree.h"
  28 #include "xfs_inode.h"
  29 #include "xfs_error.h"
  30 #include "xfs_trace.h"
  31 #include "xfs_symlink.h"
  32 #include "xfs_cksum.h"
  33 #include "xfs_buf_item.h"
  34
  35
  36 /*
  37  * Each contiguous block has a header, so it is not just a simple pathlen
  38  * to FSB conversion.
  39  */
  40 int
  41 xfs_symlink_blocks(
  42         struct xfs_mount *mp,
  43         int             pathlen)
  44 {
  45         int buflen = XFS_SYMLINK_BUF_SPACE(mp, mp->m_sb.sb_blocksize);
  46
  47         return (pathlen + buflen - 1) / buflen;
  48 }
  49
  50 int
  51 xfs_symlink_hdr_set(
  52         struct xfs_mount        *mp,
  53         xfs_ino_t               ino,
  54         uint32_t                offset,
  55         uint32_t                size,
  56         struct xfs_buf          *bp)
  57 {
  58         struct xfs_dsymlink_hdr *dsl = bp->b_addr;
  59
  60         if (!xfs_sb_version_hascrc(&mp->m_sb))
  61                 return 0;
  62
  63         dsl->sl_magic = cpu_to_be32(XFS_SYMLINK_MAGIC);
  64         dsl->sl_offset = cpu_to_be32(offset);
  65         dsl->sl_bytes = cpu_to_be32(size);
  66         uuid_copy(&dsl->sl_uuid, &mp->m_sb.sb_uuid);
  67         dsl->sl_owner = cpu_to_be64(ino);
  68         dsl->sl_blkno = cpu_to_be64(bp->b_bn);
  69         bp->b_ops = &xfs_symlink_buf_ops;
  70
  71         return sizeof(struct xfs_dsymlink_hdr);
  72 }
  73
  74 /*
  75  * Checking of the symlink header is split into two parts. the verifier does
  76  * CRC, location and bounds checking, the unpacking function checks the path
  77  * parameters and owner.
  78  */
  79 bool
  80 xfs_symlink_hdr_ok(
  81         struct xfs_mount        *mp,
  82         xfs_ino_t               ino,
  83         uint32_t                offset,
  84         uint32_t                size,
  85         struct xfs_buf          *bp)
  86 {
  87         struct xfs_dsymlink_hdr *dsl = bp->b_addr;
  88
  89         if (offset != be32_to_cpu(dsl->sl_offset))
  90                 return false;
  91         if (size != be32_to_cpu(dsl->sl_bytes))
  92                 return false;
  93         if (ino != be64_to_cpu(dsl->sl_owner))
  94                 return false;
  95
  96         /* ok */
  97         return true;
  98 }
  99
 100 static bool
 101 xfs_symlink_verify(
 102         struct xfs_buf          *bp)
 103 {
 104         struct xfs_mount        *mp = bp->b_target->bt_mount;
 105         struct xfs_dsymlink_hdr *dsl = bp->b_addr;
 106
 107         if (!xfs_sb_version_hascrc(&mp->m_sb))
 108                 return false;
 109         if (dsl->sl_magic != cpu_to_be32(XFS_SYMLINK_MAGIC))
 110                 return false;
 111         if (!uuid_equal(&dsl->sl_uuid, &mp->m_sb.sb_uuid))
 112                 return false;
 113         if (bp->b_bn != be64_to_cpu(dsl->sl_blkno))
 114                 return false;
 115         if (be32_to_cpu(dsl->sl_offset) +
 116                                 be32_to_cpu(dsl->sl_bytes) >= MAXPATHLEN)
 117                 return false;
 118         if (dsl->sl_owner == 0)
 119                 return false;
 120
 121         return true;
 122 }
 123
 124 static void
 125 xfs_symlink_read_verify(
 126         struct xfs_buf  *bp)
 127 {
 128         struct xfs_mount *mp = bp->b_target->bt_mount;
 129
 130         /* no verification of non-crc buffers */
 131         if (!xfs_sb_version_hascrc(&mp->m_sb))
 132                 return;
 133
 134         if (!xfs_verify_cksum(bp->b_addr, BBTOB(bp->b_length),
 135                                   offsetof(struct xfs_dsymlink_hdr, sl_crc)) ||
 136             !xfs_symlink_verify(bp)) {
 137                 XFS_CORRUPTION_ERROR(__func__, XFS_ERRLEVEL_LOW, mp, bp->b_addr);
 138                 xfs_buf_ioerror(bp, EFSCORRUPTED);
 139         }
 140 }
 141
 142 static void
 143 xfs_symlink_write_verify(
 144         struct xfs_buf  *bp)
 145 {
 146         struct xfs_mount *mp = bp->b_target->bt_mount;
 147         struct xfs_buf_log_item *bip = bp->b_fspriv;
 148
 149         /* no verification of non-crc buffers */
 150         if (!xfs_sb_version_hascrc(&mp->m_sb))
 151                 return;
 152
 153         if (!xfs_symlink_verify(bp)) {
 154                 XFS_CORRUPTION_ERROR(__func__, XFS_ERRLEVEL_LOW, mp, bp->b_addr);
 155                 xfs_buf_ioerror(bp, EFSCORRUPTED);
 156                 return;
 157         }
 158
 159         if (bip) {
 160                 struct xfs_dsymlink_hdr *dsl = bp->b_addr;
 161                 dsl->sl_lsn = cpu_to_be64(bip->bli_item.li_lsn);
 162         }
 163         xfs_update_cksum(bp->b_addr, BBTOB(bp->b_length),
 164                          offsetof(struct xfs_dsymlink_hdr, sl_crc));
 165 }
 166
 167 const struct xfs_buf_ops xfs_symlink_buf_ops = {
 168         .verify_read = xfs_symlink_read_verify,
 169         .verify_write = xfs_symlink_write_verify,
 170 };
 171
 172 void
 173 xfs_symlink_local_to_remote(
 174         struct xfs_trans        *tp,
 175         struct xfs_buf          *bp,
 176         struct xfs_inode        *ip,
 177         struct xfs_ifork        *ifp)
 178 {
 179         struct xfs_mount        *mp = ip->i_mount;
 180         char                    *buf;
 181
 182         if (!xfs_sb_version_hascrc(&mp->m_sb)) {
 183                 bp->b_ops = NULL;
 184                 memcpy(bp->b_addr, ifp->if_u1.if_data, ifp->if_bytes);
 185                 return;
 186         }
 187
 188         /*
 189          * As this symlink fits in an inode literal area, it must also fit in
 190          * the smallest buffer the filesystem supports.
 191          */
 192         ASSERT(BBTOB(bp->b_length) >=
 193                         ifp->if_bytes + sizeof(struct xfs_dsymlink_hdr));
 194
 195         bp->b_ops = &xfs_symlink_buf_ops;
 196
 197         buf = bp->b_addr;
 198         buf += xfs_symlink_hdr_set(mp, ip->i_ino, 0, ifp->if_bytes, bp);
 199         memcpy(buf, ifp->if_u1.if_data, ifp->if_bytes);
 200 }