fs/xfs/libxfs/xfs_symlink_remote.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (c) 2000-2006 Silicon Graphics, Inc.
   4  * Copyright (c) 2012-2013 Red Hat, Inc.
   5  * All rights reserved.
   6  */
   7 #include "xfs.h"
   8 #include "xfs_fs.h"
   9 #include "xfs_format.h"
  10 #include "xfs_log_format.h"
  11 #include "xfs_shared.h"
  12 #include "xfs_trans_resv.h"
  13 #include "xfs_mount.h"
  14 #include "xfs_bmap_btree.h"
  15 #include "xfs_inode.h"
  16 #include "xfs_error.h"
  17 #include "xfs_trace.h"
  18 #include "xfs_symlink.h"
  19 #include "xfs_cksum.h"
  20 #include "xfs_trans.h"
  21 #include "xfs_buf_item.h"
  22 #include "xfs_log.h"
  23
  24
  25 /*
  26  * Each contiguous block has a header, so it is not just a simple pathlen
  27  * to FSB conversion.
  28  */
  29 int
  30 xfs_symlink_blocks(
  31         struct xfs_mount *mp,
  32         int             pathlen)
  33 {
  34         int buflen = XFS_SYMLINK_BUF_SPACE(mp, mp->m_sb.sb_blocksize);
  35
  36         return (pathlen + buflen - 1) / buflen;
  37 }
  38
  39 int
  40 xfs_symlink_hdr_set(
  41         struct xfs_mount        *mp,
  42         xfs_ino_t               ino,
  43         uint32_t                offset,
  44         uint32_t                size,
  45         struct xfs_buf          *bp)
  46 {
  47         struct xfs_dsymlink_hdr *dsl = bp->b_addr;
  48
  49         if (!xfs_sb_version_hascrc(&mp->m_sb))
  50                 return 0;
  51
  52         memset(dsl, 0, sizeof(struct xfs_dsymlink_hdr));
  53         dsl->sl_magic = cpu_to_be32(XFS_SYMLINK_MAGIC);
  54         dsl->sl_offset = cpu_to_be32(offset);
  55         dsl->sl_bytes = cpu_to_be32(size);
  56         uuid_copy(&dsl->sl_uuid, &mp->m_sb.sb_meta_uuid);
  57         dsl->sl_owner = cpu_to_be64(ino);
  58         dsl->sl_blkno = cpu_to_be64(bp->b_bn);
  59         bp->b_ops = &xfs_symlink_buf_ops;
  60
  61         return sizeof(struct xfs_dsymlink_hdr);
  62 }
  63
  64 /*
  65  * Checking of the symlink header is split into two parts. the verifier does
  66  * CRC, location and bounds checking, the unpacking function checks the path
  67  * parameters and owner.
  68  */
  69 bool
  70 xfs_symlink_hdr_ok(
  71         xfs_ino_t               ino,
  72         uint32_t                offset,
  73         uint32_t                size,
  74         struct xfs_buf          *bp)
  75 {
  76         struct xfs_dsymlink_hdr *dsl = bp->b_addr;
  77
  78         if (offset != be32_to_cpu(dsl->sl_offset))
  79                 return false;
  80         if (size != be32_to_cpu(dsl->sl_bytes))
  81                 return false;
  82         if (ino != be64_to_cpu(dsl->sl_owner))
  83                 return false;
  84
  85         /* ok */
  86         return true;
  87 }
  88
  89 static xfs_failaddr_t
  90 xfs_symlink_verify(
  91         struct xfs_buf          *bp)
  92 {
  93         struct xfs_mount        *mp = bp->b_target->bt_mount;
  94         struct xfs_dsymlink_hdr *dsl = bp->b_addr;
  95
  96         if (!xfs_sb_version_hascrc(&mp->m_sb))
  97                 return __this_address;
  98         if (!xfs_verify_magic(bp, dsl->sl_magic))
  99                 return __this_address;
 100         if (!uuid_equal(&dsl->sl_uuid, &mp->m_sb.sb_meta_uuid))
 101                 return __this_address;
 102         if (bp->b_bn != be64_to_cpu(dsl->sl_blkno))
 103                 return __this_address;
 104         if (be32_to_cpu(dsl->sl_offset) +
 105                                 be32_to_cpu(dsl->sl_bytes) >= XFS_SYMLINK_MAXLEN)
 106                 return __this_address;
 107         if (dsl->sl_owner == 0)
 108                 return __this_address;
 109         if (!xfs_log_check_lsn(mp, be64_to_cpu(dsl->sl_lsn)))
 110                 return __this_address;
 111
 112         return NULL;
 113 }
 114
 115 static void
 116 xfs_symlink_read_verify(
 117         struct xfs_buf  *bp)
 118 {
 119         struct xfs_mount *mp = bp->b_target->bt_mount;
 120         xfs_failaddr_t  fa;
 121
 122         /* no verification of non-crc buffers */
 123         if (!xfs_sb_version_hascrc(&mp->m_sb))
 124                 return;
 125
 126         if (!xfs_buf_verify_cksum(bp, XFS_SYMLINK_CRC_OFF))
 127                 xfs_verifier_error(bp, -EFSBADCRC, __this_address);
 128         else {
 129                 fa = xfs_symlink_verify(bp);
 130                 if (fa)
 131                         xfs_verifier_error(bp, -EFSCORRUPTED, fa);
 132         }
 133 }
 134
 135 static void
 136 xfs_symlink_write_verify(
 137         struct xfs_buf  *bp)
 138 {
 139         struct xfs_mount *mp = bp->b_target->bt_mount;
 140         struct xfs_buf_log_item *bip = bp->b_log_item;
 141         xfs_failaddr_t          fa;
 142
 143         /* no verification of non-crc buffers */
 144         if (!xfs_sb_version_hascrc(&mp->m_sb))
 145                 return;
 146
 147         fa = xfs_symlink_verify(bp);
 148         if (fa) {
 149                 xfs_verifier_error(bp, -EFSCORRUPTED, fa);
 150                 return;
 151         }
 152
 153         if (bip) {
 154                 struct xfs_dsymlink_hdr *dsl = bp->b_addr;
 155                 dsl->sl_lsn = cpu_to_be64(bip->bli_item.li_lsn);
 156         }
 157         xfs_buf_update_cksum(bp, XFS_SYMLINK_CRC_OFF);
 158 }
 159
 160 const struct xfs_buf_ops xfs_symlink_buf_ops = {
 161         .name = "xfs_symlink",
 162         .magic = { 0, cpu_to_be32(XFS_SYMLINK_MAGIC) },
 163         .verify_read = xfs_symlink_read_verify,
 164         .verify_write = xfs_symlink_write_verify,
 165         .verify_struct = xfs_symlink_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                 xfs_trans_log_buf(tp, bp, 0, ifp->if_bytes - 1);
 184                 return;
 185         }
 186
 187         /*
 188          * As this symlink fits in an inode literal area, it must also fit in
 189          * the smallest buffer the filesystem supports.
 190          */
 191         ASSERT(BBTOB(bp->b_length) >=
 192                         ifp->if_bytes + sizeof(struct xfs_dsymlink_hdr));
 193
 194         bp->b_ops = &xfs_symlink_buf_ops;
 195
 196         buf = bp->b_addr;
 197         buf += xfs_symlink_hdr_set(mp, ip->i_ino, 0, ifp->if_bytes, bp);
 198         memcpy(buf, ifp->if_u1.if_data, ifp->if_bytes);
 199         xfs_trans_log_buf(tp, bp, 0, sizeof(struct xfs_dsymlink_hdr) +
 200                                         ifp->if_bytes - 1);
 201 }
 202
 203 /*
 204  * Verify the in-memory consistency of an inline symlink data fork. This
 205  * does not do on-disk format checks.
 206  */
 207 xfs_failaddr_t
 208 xfs_symlink_shortform_verify(
 209         struct xfs_inode        *ip)
 210 {
 211         char                    *sfp;
 212         char                    *endp;
 213         struct xfs_ifork        *ifp;
 214         int                     size;
 215
 216         ASSERT(ip->i_d.di_format == XFS_DINODE_FMT_LOCAL);
 217         ifp = XFS_IFORK_PTR(ip, XFS_DATA_FORK);
 218         sfp = (char *)ifp->if_u1.if_data;
 219         size = ifp->if_bytes;
 220         endp = sfp + size;
 221
 222         /*
 223          * Zero length symlinks should never occur in memory as they are
 224          * never alllowed to exist on disk.
 225          */
 226         if (!size)
 227                 return __this_address;
 228
 229         /* No negative sizes or overly long symlink targets. */
 230         if (size < 0 || size > XFS_SYMLINK_MAXLEN)
 231                 return __this_address;
 232
 233         /* No NULLs in the target either. */
 234         if (memchr(sfp, 0, size - 1))
 235                 return __this_address;
 236
 237         /* We /did/ null-terminate the buffer, right? */
 238         if (*endp != 0)
 239                 return __this_address;
 240         return NULL;
 241 }