kernel/fs/xfs/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 #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_error.h"
  29 #include "xfs_trace.h"
  30 #include "xfs_symlink.h"
  31 #include "xfs_cksum.h"
  32 #include "xfs_trans.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         xfs_ino_t               ino,
  82         uint32_t                offset,
  83         uint32_t                size,
  84         struct xfs_buf          *bp)
  85 {
  86         struct xfs_dsymlink_hdr *dsl = bp->b_addr;
  87
  88         if (offset != be32_to_cpu(dsl->sl_offset))
  89                 return false;
  90         if (size != be32_to_cpu(dsl->sl_bytes))
  91                 return false;
  92         if (ino != be64_to_cpu(dsl->sl_owner))
  93                 return false;
  94
  95         /* ok */
  96         return true;
  97 }
  98
  99 static bool
 100 xfs_symlink_verify(
 101         struct xfs_buf          *bp)
 102 {
 103         struct xfs_mount        *mp = bp->b_target->bt_mount;
 104         struct xfs_dsymlink_hdr *dsl = bp->b_addr;
 105
 106         if (!xfs_sb_version_hascrc(&mp->m_sb))
 107                 return false;
 108         if (dsl->sl_magic != cpu_to_be32(XFS_SYMLINK_MAGIC))
 109                 return false;
 110         if (!uuid_equal(&dsl->sl_uuid, &mp->m_sb.sb_uuid))
 111                 return false;
 112         if (bp->b_bn != be64_to_cpu(dsl->sl_blkno))
 113                 return false;
 114         if (be32_to_cpu(dsl->sl_offset) +
 115                                 be32_to_cpu(dsl->sl_bytes) >= MAXPATHLEN)
 116                 return false;
 117         if (dsl->sl_owner == 0)
 118                 return false;
 119
 120         return true;
 121 }
 122
 123 static void
 124 xfs_symlink_read_verify(
 125         struct xfs_buf  *bp)
 126 {
 127         struct xfs_mount *mp = bp->b_target->bt_mount;
 128
 129         /* no verification of non-crc buffers */
 130         if (!xfs_sb_version_hascrc(&mp->m_sb))
 131                 return;
 132
 133         if (!xfs_buf_verify_cksum(bp, XFS_SYMLINK_CRC_OFF))
 134                 xfs_buf_ioerror(bp, -EFSBADCRC);
 135         else if (!xfs_symlink_verify(bp))
 136                 xfs_buf_ioerror(bp, -EFSCORRUPTED);
 137
 138         if (bp->b_error)
 139                 xfs_verifier_error(bp);
 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_buf_ioerror(bp, -EFSCORRUPTED);
 155                 xfs_verifier_error(bp);
 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_buf_update_cksum(bp, XFS_SYMLINK_CRC_OFF);
 164 }
 165
 166 const struct xfs_buf_ops xfs_symlink_buf_ops = {
 167         .verify_read = xfs_symlink_read_verify,
 168         .verify_write = xfs_symlink_write_verify,
 169 };
 170
 171 void
 172 xfs_symlink_local_to_remote(
 173         struct xfs_trans        *tp,
 174         struct xfs_buf          *bp,
 175         struct xfs_inode        *ip,
 176         struct xfs_ifork        *ifp)
 177 {
 178         struct xfs_mount        *mp = ip->i_mount;
 179         char                    *buf;
 180
 181         xfs_trans_buf_set_type(tp, bp, XFS_BLFT_SYMLINK_BUF);
 182
 183         if (!xfs_sb_version_hascrc(&mp->m_sb)) {
 184                 bp->b_ops = NULL;
 185                 memcpy(bp->b_addr, ifp->if_u1.if_data, ifp->if_bytes);
 186                 return;
 187         }
 188
 189         /*
 190          * As this symlink fits in an inode literal area, it must also fit in
 191          * the smallest buffer the filesystem supports.
 192          */
 193         ASSERT(BBTOB(bp->b_length) >=
 194                         ifp->if_bytes + sizeof(struct xfs_dsymlink_hdr));
 195
 196         bp->b_ops = &xfs_symlink_buf_ops;
 197
 198         buf = bp->b_addr;
 199         buf += xfs_symlink_hdr_set(mp, ip->i_ino, 0, ifp->if_bytes, bp);
 200         memcpy(buf, ifp->if_u1.if_data, ifp->if_bytes);
 201 }