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         memset(dsl, 0, sizeof(struct xfs_dsymlink_hdr));
  61         dsl->sl_magic = cpu_to_be32(XFS_SYMLINK_MAGIC);
  62         dsl->sl_offset = cpu_to_be32(offset);
  63         dsl->sl_bytes = cpu_to_be32(size);
  64         uuid_copy(&dsl->sl_uuid, &mp->m_sb.sb_meta_uuid);
  65         dsl->sl_owner = cpu_to_be64(ino);
  66         dsl->sl_blkno = cpu_to_be64(bp->b_bn);
  67         bp->b_ops = &xfs_symlink_buf_ops;
  68
  69         return sizeof(struct xfs_dsymlink_hdr);
  70 }
  71
  72 /*
  73  * Checking of the symlink header is split into two parts. the verifier does
  74  * CRC, location and bounds checking, the unpacking function checks the path
  75  * parameters and owner.
  76  */
  77 bool
  78 xfs_symlink_hdr_ok(
  79         xfs_ino_t               ino,
  80         uint32_t                offset,
  81         uint32_t                size,
  82         struct xfs_buf          *bp)
  83 {
  84         struct xfs_dsymlink_hdr *dsl = bp->b_addr;
  85
  86         if (offset != be32_to_cpu(dsl->sl_offset))
  87                 return false;
  88         if (size != be32_to_cpu(dsl->sl_bytes))
  89                 return false;
  90         if (ino != be64_to_cpu(dsl->sl_owner))
  91                 return false;
  92
  93         /* ok */
  94         return true;
  95 }
  96
  97 static xfs_failaddr_t
  98 xfs_symlink_verify(
  99         struct xfs_buf          *bp)
 100 {
 101         struct xfs_mount        *mp = bp->b_target->bt_mount;
 102         struct xfs_dsymlink_hdr *dsl = bp->b_addr;
 103
 104         if (!xfs_sb_version_hascrc(&mp->m_sb))
 105                 return __this_address;
 106         if (dsl->sl_magic != cpu_to_be32(XFS_SYMLINK_MAGIC))
 107                 return __this_address;
 108         if (!uuid_equal(&dsl->sl_uuid, &mp->m_sb.sb_meta_uuid))
 109                 return __this_address;
 110         if (bp->b_bn != be64_to_cpu(dsl->sl_blkno))
 111                 return __this_address;
 112         if (be32_to_cpu(dsl->sl_offset) +
 113                                 be32_to_cpu(dsl->sl_bytes) >= XFS_SYMLINK_MAXLEN)
 114                 return __this_address;
 115         if (dsl->sl_owner == 0)
 116                 return __this_address;
 117         if (!xfs_log_check_lsn(mp, be64_to_cpu(dsl->sl_lsn)))
 118                 return __this_address;
 119
 120         return NULL;
 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         xfs_failaddr_t  fa;
 129
 130         /* no verification of non-crc buffers */
 131         if (!xfs_sb_version_hascrc(&mp->m_sb))
 132                 return;
 133
 134         if (!xfs_buf_verify_cksum(bp, XFS_SYMLINK_CRC_OFF))
 135                 xfs_verifier_error(bp, -EFSBADCRC, __this_address);
 136         else {
 137                 fa = xfs_symlink_verify(bp);
 138                 if (fa)
 139                         xfs_verifier_error(bp, -EFSCORRUPTED, fa);
 140         }
 141 }
 142
 143 static void
 144 xfs_symlink_write_verify(
 145         struct xfs_buf  *bp)
 146 {
 147         struct xfs_mount *mp = bp->b_target->bt_mount;
 148         struct xfs_buf_log_item *bip = bp->b_log_item;
 149         xfs_failaddr_t          fa;
 150
 151         /* no verification of non-crc buffers */
 152         if (!xfs_sb_version_hascrc(&mp->m_sb))
 153                 return;
 154
 155         fa = xfs_symlink_verify(bp);
 156         if (fa) {
 157                 xfs_verifier_error(bp, -EFSCORRUPTED, fa);
 158                 return;
 159         }
 160
 161         if (bip) {
 162                 struct xfs_dsymlink_hdr *dsl = bp->b_addr;
 163                 dsl->sl_lsn = cpu_to_be64(bip->bli_item.li_lsn);
 164         }
 165         xfs_buf_update_cksum(bp, XFS_SYMLINK_CRC_OFF);
 166 }
 167
 168 const struct xfs_buf_ops xfs_symlink_buf_ops = {
 169         .name = "xfs_symlink",
 170         .verify_read = xfs_symlink_read_verify,
 171         .verify_write = xfs_symlink_write_verify,
 172         .verify_struct = xfs_symlink_verify,
 173 };
 174
 175 void
 176 xfs_symlink_local_to_remote(
 177         struct xfs_trans        *tp,
 178         struct xfs_buf          *bp,
 179         struct xfs_inode        *ip,
 180         struct xfs_ifork        *ifp)
 181 {
 182         struct xfs_mount        *mp = ip->i_mount;
 183         char                    *buf;
 184
 185         xfs_trans_buf_set_type(tp, bp, XFS_BLFT_SYMLINK_BUF);
 186
 187         if (!xfs_sb_version_hascrc(&mp->m_sb)) {
 188                 bp->b_ops = NULL;
 189                 memcpy(bp->b_addr, ifp->if_u1.if_data, ifp->if_bytes);
 190                 xfs_trans_log_buf(tp, bp, 0, ifp->if_bytes - 1);
 191                 return;
 192         }
 193
 194         /*
 195          * As this symlink fits in an inode literal area, it must also fit in
 196          * the smallest buffer the filesystem supports.
 197          */
 198         ASSERT(BBTOB(bp->b_length) >=
 199                         ifp->if_bytes + sizeof(struct xfs_dsymlink_hdr));
 200
 201         bp->b_ops = &xfs_symlink_buf_ops;
 202
 203         buf = bp->b_addr;
 204         buf += xfs_symlink_hdr_set(mp, ip->i_ino, 0, ifp->if_bytes, bp);
 205         memcpy(buf, ifp->if_u1.if_data, ifp->if_bytes);
 206         xfs_trans_log_buf(tp, bp, 0, sizeof(struct xfs_dsymlink_hdr) +
 207                                         ifp->if_bytes - 1);
 208 }
 209
 210 /* Verify the consistency of an inline symlink. */
 211 xfs_failaddr_t
 212 xfs_symlink_shortform_verify(
 213         struct xfs_inode        *ip)
 214 {
 215         char                    *sfp;
 216         char                    *endp;
 217         struct xfs_ifork        *ifp;
 218         int                     size;
 219
 220         ASSERT(ip->i_d.di_format == XFS_DINODE_FMT_LOCAL);
 221         ifp = XFS_IFORK_PTR(ip, XFS_DATA_FORK);
 222         sfp = (char *)ifp->if_u1.if_data;
 223         size = ifp->if_bytes;
 224         endp = sfp + size;
 225
 226         /* Zero length symlinks can exist while we're deleting a remote one. */
 227         if (size == 0)
 228                 return NULL;
 229
 230         /* No negative sizes or overly long symlink targets. */
 231         if (size < 0 || size > XFS_SYMLINK_MAXLEN)
 232                 return __this_address;
 233
 234         /* No NULLs in the target either. */
 235         if (memchr(sfp, 0, size - 1))
 236                 return __this_address;
 237
 238         /* We /did/ null-terminate the buffer, right? */
 239         if (*endp != 0)
 240                 return __this_address;
 241         return NULL;
 242 }