NTFS: Detect the case when Windows has been suspended to disk on the volume

      to be mounted and if this is the case do not allow (re)mounting
      read-write.  This is done by parsing hiberfil.sys if present.

Signed-off-by: Anton Altaparmakov <aia21@cantab.net>

1 files changed, 168 insertions, 11 deletions

diff --git a/fs/ntfs/super.c b/fs/ntfs/super.c
index 92e1d28219b3..41aa8eb6755b 100644
--- a/fs/ntfs/super.c
+++ b/fs/ntfs/super.c
@@ -1156,6 +1156,124 @@ static BOOL load_and_check_logfile(ntfs_volume *vol)
         return TRUE;
 }
 
+#define NTFS_HIBERFIL_HEADER_SIZE       4096
+
+/**
+ * check_windows_hibernation_status - check if Windows is suspended on a volume
+ * @vol:        ntfs super block of device to check
+ *
+ * Check if Windows is hibernated on the ntfs volume @vol.  This is done by
+ * looking for the file hiberfil.sys in the root directory of the volume.  If
+ * the file is not present Windows is definitely not suspended.
+ *
+ * If hiberfil.sys exists and is less than 4kiB in size it means Windows is
+ * definitely suspended (this volume is not the system volume).  Caveat:  on a
+ * system with many volumes it is possible that the < 4kiB check is bogus but
+ * for now this should do fine.
+ *
+ * If hiberfil.sys exists and is larger than 4kiB in size, we need to read the
+ * hiberfil header (which is the first 4kiB).  If this begins with "hibr",
+ * Windows is definitely suspended.  If it is completely full of zeroes,
+ * Windows is definitely not hibernated.  Any other case is treated as if
+ * Windows is suspended.  This caters for the above mentioned caveat of a
+ * system with many volumes where no "hibr" magic would be present and there is
+ * no zero header.
+ *
+ * Return 0 if Windows is not hibernated on the volume, >0 if Windows is
+ * hibernated on the volume, and -errno on error.
+ */
+static int check_windows_hibernation_status(ntfs_volume *vol)
+{
+        MFT_REF mref;
+        struct inode *vi;
+        ntfs_inode *ni;
+        struct page *page;
+        u32 *kaddr, *kend;
+        ntfs_name *name = NULL;
+        int ret = 1;
+        static const ntfschar hiberfil[13] = { const_cpu_to_le16('h'),
+                        const_cpu_to_le16('i'), const_cpu_to_le16('b'),
+                        const_cpu_to_le16('e'), const_cpu_to_le16('r'),
+                        const_cpu_to_le16('f'), const_cpu_to_le16('i'),
+                        const_cpu_to_le16('l'), const_cpu_to_le16('.'),
+                        const_cpu_to_le16('s'), const_cpu_to_le16('y'),
+                        const_cpu_to_le16('s'), 0 };
+
+        ntfs_debug("Entering.");
+        /*
+         * Find the inode number for the hibernation file by looking up the
+         * filename hiberfil.sys in the root directory.
+         */
+        down(&vol->root_ino->i_sem);
+        mref = ntfs_lookup_inode_by_name(NTFS_I(vol->root_ino), hiberfil, 12,
+                        &name);
+        up(&vol->root_ino->i_sem);
+        if (IS_ERR_MREF(mref)) {
+                ret = MREF_ERR(mref);
+                /* If the file does not exist, Windows is not hibernated. */
+                if (ret == -ENOENT) {
+                        ntfs_debug("hiberfil.sys not present.  Windows is not "
+                                        "hibernated on the volume.");
+                        return 0;
+                }
+                /* A real error occured. */
+                ntfs_error(vol->sb, "Failed to find inode number for "
+                                "hiberfil.sys.");
+                return ret;
+        }
+        /* We do not care for the type of match that was found. */
+        kfree(name);
+        /* Get the inode. */
+        vi = ntfs_iget(vol->sb, MREF(mref));
+        if (IS_ERR(vi) || is_bad_inode(vi)) {
+                if (!IS_ERR(vi))
+                        iput(vi);
+                ntfs_error(vol->sb, "Failed to load hiberfil.sys.");
+                return IS_ERR(vi) ? PTR_ERR(vi) : -EIO;
+        }
+        if (unlikely(i_size_read(vi) < NTFS_HIBERFIL_HEADER_SIZE)) {
+                ntfs_debug("hiberfil.sys is smaller than 4kiB (0x%llx).  "
+                                "Windows is hibernated on the volume.  This "
+                                "is not the system volume.", i_size_read(vi));
+                goto iput_out;
+        }
+        ni = NTFS_I(vi);
+        page = ntfs_map_page(vi->i_mapping, 0);
+        if (IS_ERR(page)) {
+                ntfs_error(vol->sb, "Failed to read from hiberfil.sys.");
+                ret = PTR_ERR(page);
+                goto iput_out;
+        }
+        kaddr = (u32*)page_address(page);
+        if (*(le32*)kaddr == const_cpu_to_le32(0x72626968)/*'hibr'*/) {
+                ntfs_debug("Magic \"hibr\" found in hiberfil.sys.  Windows is "
+                                "hibernated on the volume.  This is the "
+                                "system volume.");
+                goto unm_iput_out;
+        }
+        kend = kaddr + NTFS_HIBERFIL_HEADER_SIZE/sizeof(*kaddr);
+        do {
+                if (unlikely(*kaddr)) {
+                        ntfs_debug("hiberfil.sys is larger than 4kiB "
+                                        "(0x%llx), does not contain the "
+                                        "\"hibr\" magic, and does not have a "
+                                        "zero header.  Windows is hibernated "
+                                        "on the volume.  This is not the "
+                                        "system volume.", i_size_read(vi));
+                        goto unm_iput_out;
+                }
+        } while (++kaddr < kend);
+        ntfs_debug("hiberfil.sys contains a zero header.  Windows is not "
+                        "hibernated on the volume.  This is the system "
+                        "volume.");
+        ret = 0;
+unm_iput_out:
+        ntfs_unmap_page(page);
+iput_out:
+        iput(vi);
+        return ret;
+}
+
 /**
  * load_and_init_quota - load and setup the quota file for a volume if present
  * @vol:        ntfs super block describing device whose quota file to load
@@ -1570,6 +1688,9 @@ static BOOL load_system_files(ntfs_volume *vol)
         MFT_RECORD *m;
         VOLUME_INFORMATION *vi;
         ntfs_attr_search_ctx *ctx;
+#ifdef NTFS_RW
+        int err;
+#endif /* NTFS_RW */
 
         ntfs_debug("Entering.");
 #ifdef NTFS_RW
@@ -1746,6 +1867,50 @@ get_ctx_vol_failed:
                 /* This will prevent a read-write remount. */
                 NVolSetErrors(vol);
         }
+#endif /* NTFS_RW */
+        /* Get the root directory inode so we can do path lookups. */
+        vol->root_ino = ntfs_iget(sb, FILE_root);
+        if (IS_ERR(vol->root_ino) || is_bad_inode(vol->root_ino)) {
+                if (!IS_ERR(vol->root_ino))
+                        iput(vol->root_ino);
+                ntfs_error(sb, "Failed to load root directory.");
+                goto iput_logfile_err_out;
+        }
+#ifdef NTFS_RW
+        /*
+         * Check if Windows is suspended to disk on the target volume.  If it
+         * is hibernated, we must not write *anything* to the disk so set
+         * NVolErrors() without setting the dirty volume flag and mount
+         * read-only.  This will prevent read-write remounting and it will also
+         * prevent all writes.
+         */
+        err = check_windows_hibernation_status(vol);
+        if (unlikely(err)) {
+                static const char *es1a = "Failed to determine if Windows is "
+                                "hibernated";
+                static const char *es1b = "Windows is hibernated";
+                static const char *es2 = ".  Run chkdsk.";
+                const char *es1;
+
+                es1 = err < 0 ? es1a : es1b;
+                /* If a read-write mount, convert it to a read-only mount. */
+                if (!(sb->s_flags & MS_RDONLY)) {
+                        if (!(vol->on_errors & (ON_ERRORS_REMOUNT_RO |
+                                        ON_ERRORS_CONTINUE))) {
+                                ntfs_error(sb, "%s and neither on_errors="
+                                                "continue nor on_errors="
+                                                "remount-ro was specified%s",
+                                                es1, es2);
+                                goto iput_root_err_out;
+                        }
+                        sb->s_flags |= MS_RDONLY | MS_NOATIME | MS_NODIRATIME;
+                        ntfs_error(sb, "%s.  Mounting read-only%s", es1, es2);
+                } else
+                        ntfs_warning(sb, "%s.  Will not be able to remount "
+                                        "read-write%s", es1, es2);
+                /* This will prevent a read-write remount. */
+                NVolSetErrors(vol);
+        }
         /* If (still) a read-write mount, mark the volume dirty. */
         if (!(sb->s_flags & MS_RDONLY) &&
                         ntfs_set_volume_flags(vol, VOLUME_IS_DIRTY)) {
@@ -1759,7 +1924,7 @@ get_ctx_vol_failed:
                         ntfs_error(sb, "%s and neither on_errors=continue nor "
                                         "on_errors=remount-ro was specified%s",
                                         es1, es2);
-                        goto iput_logfile_err_out;
+                        goto iput_root_err_out;
                 }
                 ntfs_error(sb, "%s.  Mounting read-only%s", es1, es2);
                 sb->s_flags |= MS_RDONLY | MS_NOATIME | MS_NODIRATIME;
@@ -1786,7 +1951,7 @@ get_ctx_vol_failed:
                         ntfs_error(sb, "%s and neither on_errors=continue nor "
                                         "on_errors=remount-ro was specified%s",
                                         es1, es2);
-                        goto iput_logfile_err_out;
+                        goto iput_root_err_out;
                 }
                 ntfs_error(sb, "%s.  Mounting read-only%s", es1, es2);
                 sb->s_flags |= MS_RDONLY | MS_NOATIME | MS_NODIRATIME;
@@ -1805,21 +1970,13 @@ get_ctx_vol_failed:
                         ntfs_error(sb, "%s and neither on_errors=continue nor "
                                         "on_errors=remount-ro was specified%s",
                                         es1, es2);
-                        goto iput_logfile_err_out;
+                        goto iput_root_err_out;
                 }
                 ntfs_error(sb, "%s.  Mounting read-only%s", es1, es2);
                 sb->s_flags |= MS_RDONLY | MS_NOATIME | MS_NODIRATIME;
                 NVolSetErrors(vol);
         }
 #endif /* NTFS_RW */
-        /* Get the root directory inode. */
-        vol->root_ino = ntfs_iget(sb, FILE_root);
-        if (IS_ERR(vol->root_ino) || is_bad_inode(vol->root_ino)) {
-                if (!IS_ERR(vol->root_ino))
-                        iput(vol->root_ino);
-                ntfs_error(sb, "Failed to load root directory.");
-                goto iput_logfile_err_out;
-        }
         /* If on NTFS versions before 3.0, we are done. */
         if (unlikely(vol->major_ver < 3))
                 return TRUE;