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 #include "xfs_log.h"
  35
  36
  37 /*
  38  * Each contiguous block has a header, so it is not just a simple pathlen
  39  * to FSB conversion.
  40  */
  41 int
  42 xfs_symlink_blocks(
  43         struct xfs_mount *mp,
  44         int             pathlen)
  45 {
  46         int buflen = XFS_SYMLINK_BUF_SPACE(mp, mp->m_sb.sb_blocksize);
  47
  48         return (pathlen + buflen - 1) / buflen;
  49 }
  50
  51 int
  52 xfs_symlink_hdr_set(
  53         struct xfs_mount        *mp,
  54         xfs_ino_t               ino,
  55         uint32_t                offset,
  56         uint32_t                size,
  57         struct xfs_buf          *bp)
  58 {
  59         struct xfs_dsymlink_hdr *dsl = bp->b_addr;
  60
  61         if (!xfs_sb_version_hascrc(&mp->m_sb))
  62                 return 0;
  63
  64         memset(dsl, 0, sizeof(struct xfs_dsymlink_hdr));
  65         dsl->sl_magic = cpu_to_be32(XFS_SYMLINK_MAGIC);
  66         dsl->sl_offset = cpu_to_be32(offset);
  67         dsl->sl_bytes = cpu_to_be32(size);
  68         uuid_copy(&dsl->sl_uuid, &mp->m_sb.sb_meta_uuid);
  69         dsl->sl_owner = cpu_to_be64(ino);
  70         dsl->sl_blkno = cpu_to_be64(bp->b_bn);
  71         bp->b_ops = &xfs_symlink_buf_ops;
  72
  73         return sizeof(struct xfs_dsymlink_hdr);
  74 }
  75
  76 /*
  77  * Checking of the symlink header is split into two parts. the verifier does
  78  * CRC, location and bounds checking, the unpacking function checks the path
  79  * parameters and owner.
  80  */
  81 bool
  82 xfs_symlink_hdr_ok(
  83         xfs_ino_t               ino,
  84         uint32_t                offset,
  85         uint32_t                size,
  86         struct xfs_buf          *bp)
  87 {
  88         struct xfs_dsymlink_hdr *dsl = bp->b_addr;
  89
  90         if (offset != be32_to_cpu(dsl->sl_offset))
  91                 return false;
  92         if (size != be32_to_cpu(dsl->sl_bytes))
  93                 return false;
  94         if (ino != be64_to_cpu(dsl->sl_owner))
  95                 return false;
  96
  97         /* ok */
  98         return true;
  99 }
 100
 101 static xfs_failaddr_t
 102 xfs_symlink_verify(
 103         struct xfs_buf          *bp)
 104 {
 105         struct xfs_mount        *mp = bp->b_target->bt_mount;
 106         struct xfs_dsymlink_hdr *dsl = bp->b_addr;
 107
 108         if (!xfs_sb_version_hascrc(&mp->m_sb))
 109                 return __this_address;
 110         if (dsl->sl_magic != cpu_to_be32(XFS_SYMLINK_MAGIC))
 111                 return __this_address;
 112         if (!uuid_equal(&dsl->sl_uuid, &mp->m_sb.sb_meta_uuid))
 113                 return __this_address;
 114         if (bp->b_bn != be64_to_cpu(dsl->sl_blkno))
 115                 return __this_address;
 116         if (be32_to_cpu(dsl->sl_offset) +
 117                                 be32_to_cpu(dsl->sl_bytes) >= XFS_SYMLINK_MAXLEN)
 118                 return __this_address;
 119         if (dsl->sl_owner == 0)
 120                 return __this_address;
 121         if (!xfs_log_check_lsn(mp, be64_to_cpu(dsl->sl_lsn)))
 122                 return __this_address;
 123
 124         return NULL;
 125 }
 126
 127 static void
 128 xfs_symlink_read_verify(
 129         struct xfs_buf  *bp)
 130 {
 131         struct xfs_mount *mp = bp->b_target->bt_mount;
 132         xfs_failaddr_t  fa;
 133
 134         /* no verification of non-crc buffers */
 135         if (!xfs_sb_version_hascrc(&mp->m_sb))
 136                 return;
 137
 138         if (!xfs_buf_verify_cksum(bp, XFS_SYMLINK_CRC_OFF))
 139                 xfs_verifier_error(bp, -EFSBADCRC, __this_address);
 140         else {
 141                 fa = xfs_symlink_verify(bp);
 142                 if (fa)
 143                         xfs_verifier_error(bp, -EFSCORRUPTED, fa);
 144         }
 145 }
 146
 147 static void
 148 xfs_symlink_write_verify(
 149         struct xfs_buf  *bp)
 150 {
 151         struct xfs_mount *mp = bp->b_target->bt_mount;
 152         struct xfs_buf_log_item *bip = bp->b_log_item;
 153         xfs_failaddr_t          fa;
 154
 155         /* no verification of non-crc buffers */
 156         if (!xfs_sb_version_hascrc(&mp->m_sb))
 157                 return;
 158
 159         fa = xfs_symlink_verify(bp);
 160         if (fa) {
 161                 xfs_verifier_error(bp, -EFSCORRUPTED, fa);
 162                 return;
 163         }
 164
 165         if (bip) {
 166                 struct xfs_dsymlink_hdr *dsl = bp->b_addr;
 167                 dsl->sl_lsn = cpu_to_be64(bip->bli_item.li_lsn);
 168         }
 169         xfs_buf_update_cksum(bp, XFS_SYMLINK_CRC_OFF);
 170 }
 171
 172 const struct xfs_buf_ops xfs_symlink_buf_ops = {
 173         .name = "xfs_symlink",
 174         .verify_read = xfs_symlink_read_verify,
 175         .verify_write = xfs_symlink_write_verify,
 176         .verify_struct = xfs_symlink_verify,
 177 };
 178
 179 void
 180 xfs_symlink_local_to_remote(
 181         struct xfs_trans        *tp,
 182         struct xfs_buf          *bp,
 183         struct xfs_inode        *ip,
 184         struct xfs_ifork        *ifp)
 185 {
 186         struct xfs_mount        *mp = ip->i_mount;
 187         char                    *buf;
 188
 189         xfs_trans_buf_set_type(tp, bp, XFS_BLFT_SYMLINK_BUF);
 190
 191         if (!xfs_sb_version_hascrc(&mp->m_sb)) {
 192                 bp->b_ops = NULL;
 193                 memcpy(bp->b_addr, ifp->if_u1.if_data, ifp->if_bytes);
 194                 xfs_trans_log_buf(tp, bp, 0, ifp->if_bytes - 1);
 195                 return;
 196         }
 197
 198         /*
 199          * As this symlink fits in an inode literal area, it must also fit in
 200          * the smallest buffer the filesystem supports.
 201          */
 202         ASSERT(BBTOB(bp->b_length) >=
 203                         ifp->if_bytes + sizeof(struct xfs_dsymlink_hdr));
 204
 205         bp->b_ops = &xfs_symlink_buf_ops;
 206
 207         buf = bp->b_addr;
 208         buf += xfs_symlink_hdr_set(mp, ip->i_ino, 0, ifp->if_bytes, bp);
 209         memcpy(buf, ifp->if_u1.if_data, ifp->if_bytes);
 210         xfs_trans_log_buf(tp, bp, 0, sizeof(struct xfs_dsymlink_hdr) +
 211                                         ifp->if_bytes - 1);
 212 }
 213
 214 /* Verify the consistency of an inline symlink. */
 215 xfs_failaddr_t
 216 xfs_symlink_shortform_verify(
 217         struct xfs_inode        *ip)
 218 {
 219         char                    *sfp;
 220         char                    *endp;
 221         struct xfs_ifork        *ifp;
 222         int                     size;
 223
 224         ASSERT(ip->i_d.di_format == XFS_DINODE_FMT_LOCAL);
 225         ifp = XFS_IFORK_PTR(ip, XFS_DATA_FORK);
 226         sfp = (char *)ifp->if_u1.if_data;
 227         size = ifp->if_bytes;
 228         endp = sfp + size;
 229
 230         /* Zero length symlinks can exist while we're deleting a remote one. */
 231         if (size == 0)
 232                 return NULL;
 233
 234         /* No negative sizes or overly long symlink targets. */
 235         if (size < 0 || size > XFS_SYMLINK_MAXLEN)
 236                 return __this_address;
 237
 238         /* No NULLs in the target either. */
 239         if (memchr(sfp, 0, size - 1))
 240                 return __this_address;
 241
 242         /* We /did/ null-terminate the buffer, right? */
 243         if (*endp != 0)
 244                 return __this_address;
 245         return NULL;
 246 }