[Libguestfs] [PATCH v8 1/3] New API: internal_filesystem_walk

Matteo Cafasso
2016-06-13T16:50:52Z

- generator: Added tsk_dirent struct

The tsk_dirent struct contains the information gathered via TSK APIs.

The struct contains the following fields:
 * tsk_inode: inode of a file
 * tsk_type: type of file such as for dirwalk command
 * tsk_size: file size in bytes
 * tsk_name: path relative to its disk partition
 * tsk_flags: bitfield containing extra information

 - configure: Added libtsk compile-time check

Ensure libtsk is available at compile time.
If not, daemon routines depending on it won't be available.

 - API: internal_filesystem_walk

The internal_filesystem_walk command walks through the FS structures
of a disk partition and returns all the files or directories
which could be found.

The command is able to retrieve information regarding deleted
or unaccessible files where other commands such as stat or find
would fail.

The gathered list of tsk_dirent structs is serialised into XDR format
and written to a file by the appliance.

Signed-off-by: Matteo Cafasso <noxdafox@gmail.com>
---
 daemon/Makefile.am        |   4 +-
 daemon/tsk.c              | 249 ++++++++++++++++++++++++++++++++++++++++++++++
 docs/guestfs-building.pod |   4 +
 generator/actions.ml      |   9 ++
 generator/structs.ml      |  13 +++
 m4/guestfs_daemon.m4      |   8 ++
 src/MAX_PROC_NR           |   2 +-
 7 files changed, 287 insertions(+), 2 deletions(-)
 create mode 100644 daemon/tsk.c

diff --git a/daemon/Makefile.am b/daemon/Makefile.am
index fe155e5..b77d1e7 100644
--- a/daemon/Makefile.am
+++ b/daemon/Makefile.am
@@ -179,6 +179,7 @@ guestfsd_SOURCES = \
 	sync.c \
 	syslinux.c \
 	tar.c \
 	truncate.c \
+	tsk.c \
 	umask.c \
 	upload.c \
@@ -209,7 +210,8 @@ guestfsd_LDADD = \
 	$(LIB_CLOCK_GETTIME) \
 	$(LIBINTL) \
 	$(SERVENT_LIB) \
-	$(PCRE_LIBS)
+	$(PCRE_LIBS) \
+	$(TSK_LIBS)

 guestfsd_CPPFLAGS = \
 	-I$(top_srcdir)/gnulib/lib \
diff --git a/daemon/tsk.c b/daemon/tsk.c
new file mode 100644
index 0000000..7ca6ef6
--- /dev/null
+++ b/daemon/tsk.c
@@ -0,0 +1,249 @@
+/* libguestfs - the guestfsd daemon
+ * Copyright (C) 2016 Red Hat Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301
USA.
+ */
+
+#include <config.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <inttypes.h>
+#include <string.h>
+#include <unistd.h>
+#include <rpc/xdr.h>
+#include <rpc/types.h>
+
+#include "guestfs_protocol.h"
+#include "daemon.h"
+#include "actions.h"
+#include "optgroups.h"
+
+#ifdef HAVE_LIBTSK
+
+#include <tsk/libtsk.h>
+
+enum tsk_dirent_flags {
+  DIRENT_UNALLOC = 0x00,
+  DIRENT_ALLOC = 0x01,
+  DIRENT_REALLOC = 0x02
+};
+
+static int open_filesystem (const char *, TSK_IMG_INFO **, TSK_FS_INFO **);
+static TSK_WALK_RET_ENUM fswalk_callback (TSK_FS_FILE *, const char *, void *);
+static char file_type (TSK_FS_FILE *);
+static int file_flags (TSK_FS_FILE *fsfile);
+static int send_dirent_info (guestfs_int_tsk_dirent *);
+static void reply_with_tsk_error (const char *);
+
+int
+do_internal_filesystem_walk (const mountable_t *mountable)
+{
+  int ret = -1;
+  TSK_FS_INFO *fs = NULL;
+  TSK_IMG_INFO *img = NULL;  /* Used internally by tsk_fs_dir_walk */
+  int flags = TSK_FS_DIR_WALK_FLAG_ALLOC | TSK_FS_DIR_WALK_FLAG_UNALLOC |
+    TSK_FS_DIR_WALK_FLAG_RECURSE | TSK_FS_DIR_WALK_FLAG_NOORPHAN;
+
+  ret = open_filesystem (mountable->device, &img, &fs);
+  if (ret < 0)
+    return ret;
+
+  reply (NULL, NULL);  /* Reply message. */
+
+  ret = tsk_fs_dir_walk (fs, fs->root_inum, flags, fswalk_callback, NULL);
+  if (ret == 0)
+    ret = send_file_end (0);  /* File transfer end. */
+  else
+    send_file_end (1);  /* Cancel file transfer. */
+
+  fs->close (fs);
+  img->close (img);
+
+  return ret;
+}
+
+/* Inspect the device and initialises the img and fs structures.
+ * Return 0 on success, -1 on error.
+ */
+static int
+open_filesystem (const char *device, TSK_IMG_INFO **img, TSK_FS_INFO **fs)
+{
+  const char *images[] = { device };
+
+  *img = tsk_img_open (1, images, TSK_IMG_TYPE_DETECT, 0);
+  if (*img == NULL) {
+    reply_with_tsk_error ("tsk_image_open");
+    return -1;
+  }
+
+  *fs = tsk_fs_open_img (*img, 0, TSK_FS_TYPE_DETECT);
+  if (*fs == NULL) {
+    reply_with_tsk_error ("tsk_fs_open_img");
+    (*img)->close (*img);
+    return -1;
+  }
+
+  return 0;
+}
+
+/* Filesystem walk callback, it gets called on every FS node.
+ * Parse the node, encode it into an XDR structure and send it to the
appliance.
+ * Return TSK_WALK_CONT on success, TSK_WALK_ERROR on error.
+ */
+static TSK_WALK_RET_ENUM
+fswalk_callback (TSK_FS_FILE *fsfile, const char *path, void *data)
+{
+  int ret = 0;
+  CLEANUP_FREE char *fname = NULL;
+  struct guestfs_int_tsk_dirent dirent;
+
+  /* Ignore ./ and ../ */
+  ret = TSK_FS_ISDOT (fsfile->name->name);
+  if (ret != 0)
+    return TSK_WALK_CONT;
+
+  /* Build the full relative path of the entry */
+  ret = asprintf (&fname, "%s%s", path,
fsfile->name->name);
+  if (ret < 0) {
+    perror ("asprintf");
+    return TSK_WALK_ERROR;
+  }
+
+  dirent.tsk_inode = fsfile->name->meta_addr;
+  dirent.tsk_type = file_type (fsfile);
+  dirent.tsk_size = (fsfile->meta != NULL) ? fsfile->meta->size : -1;
+  dirent.tsk_name = fname;
+  dirent.tsk_flags = file_flags (fsfile);
+
+  ret = send_dirent_info (&dirent);
+  ret = (ret == 0) ? TSK_WALK_CONT : TSK_WALK_ERROR;
+
+  return ret;
+}
+
+/* Inspect fsfile to identify its type. */
+static char
+file_type (TSK_FS_FILE *fsfile)
+{
+  if (fsfile->name->type < TSK_FS_NAME_TYPE_STR_MAX)
+    switch (fsfile->name->type) {
+    case TSK_FS_NAME_TYPE_UNDEF: return 'u';
+    case TSK_FS_NAME_TYPE_FIFO: return 'f';
+    case TSK_FS_NAME_TYPE_CHR: return 'c';
+    case TSK_FS_NAME_TYPE_DIR: return 'd';
+    case TSK_FS_NAME_TYPE_BLK: return 'b';
+    case TSK_FS_NAME_TYPE_REG: return 'r';
+    case TSK_FS_NAME_TYPE_LNK: return 'l';
+    case TSK_FS_NAME_TYPE_SOCK: return 's';
+    case TSK_FS_NAME_TYPE_SHAD: return 'h';
+    case TSK_FS_NAME_TYPE_WHT: return 'w';
+    case TSK_FS_NAME_TYPE_VIRT: return 'u';  /* Temp files created by
TSK */
+    }
+  else if (fsfile->meta != NULL &&
+           fsfile->meta->type < TSK_FS_META_TYPE_STR_MAX)
+    switch (fsfile->name->type) {
+    case TSK_FS_NAME_TYPE_UNDEF: return 'u';
+    case TSK_FS_META_TYPE_REG: return 'r';
+    case TSK_FS_META_TYPE_DIR: return 'd';
+    case TSK_FS_META_TYPE_FIFO: return 'f';
+    case TSK_FS_META_TYPE_CHR: return 'c';
+    case TSK_FS_META_TYPE_BLK: return 'b';
+    case TSK_FS_META_TYPE_LNK: return 'l';
+    case TSK_FS_META_TYPE_SHAD: return 'h';
+    case TSK_FS_META_TYPE_SOCK: return 's';
+    case TSK_FS_META_TYPE_WHT: return 'w';
+    case TSK_FS_META_TYPE_VIRT: return 'u';  /* Temp files created by
TSK */
+    }
+
+  return 'u';
+}
+
+/* Inspect fsfile to retrieve the file allocation state. */
+static int
+file_flags (TSK_FS_FILE *fsfile)
+{
+  int flags = DIRENT_UNALLOC;
+
+  if (fsfile->name->flags & TSK_FS_NAME_FLAG_UNALLOC) {
+    if (fsfile->meta && fsfile->meta->flags &
TSK_FS_META_FLAG_ALLOC)
+      flags |= DIRENT_REALLOC;
+  }
+  else
+    flags |= DIRENT_ALLOC;
+
+  return flags;
+}
+
+/* Serialise dirent into XDR stream and send it to the appliance.
+ * Return 0 on success, -1 on error.
+ */
+static int
+send_dirent_info (guestfs_int_tsk_dirent *dirent)
+{
+  XDR xdr;
+  size_t len = 0;
+  bool_t ret = FALSE;
+  CLEANUP_FREE char *buf = NULL;
+
+  buf = malloc (GUESTFS_MAX_CHUNK_SIZE);
+  if (buf == NULL) {
+    perror ("malloc");
+    return -1;
+  }
+
+  /* Serialise tsk_dirent struct. */
+  xdrmem_create (&xdr, buf, GUESTFS_MAX_CHUNK_SIZE, XDR_ENCODE);
+
+  ret = xdr_guestfs_int_tsk_dirent (&xdr, dirent);
+  if (ret == FALSE) {
+    perror ("xdr_guestfs_int_tsk_dirent");
+    return -1;
+  }
+  len = xdr_getpos (&xdr);
+
+  xdr_destroy (&xdr);
+
+  /* Send serialised tsk_dirent out. */
+  return send_file_write (buf, len);
+}
+
+/* Parse TSK error and send it to the appliance. */
+static void
+reply_with_tsk_error (const char *funcname)
+{
+  int ret = 0;
+  const char *buf = NULL;
+
+  ret = tsk_error_get_errno ();
+  if (ret != 0) {
+    buf = tsk_error_get ();
+    reply_with_error ("%s: %s", funcname, buf);
+  }
+  else
+    reply_with_error ("%s: unknown error", funcname);
+}
+
+int
+optgroup_libtsk_available (void)
+{
+  return 1;
+}
+
+#else   /* !HAVE_LIBTSK */
+
+OPTGROUP_LIBTSK_NOT_AVAILABLE
+
+#endif  /* !HAVE_LIBTSK */
diff --git a/docs/guestfs-building.pod b/docs/guestfs-building.pod
index 28256c4..3fe1d41 100644
--- a/docs/guestfs-building.pod
+++ b/docs/guestfs-building.pod
@@ -395,6 +395,10 @@ Optional.

 Optional.  For tab-completion of commands in bash.

+=item libtsk
+
+Optional.  Library for filesystem forensics analysis.
+
 =back

 =head1 BUILDING FROM GIT
diff --git a/generator/actions.ml b/generator/actions.ml
index a40dbdc..10a6043 100644
--- a/generator/actions.ml
+++ b/generator/actions.ml
@@ -12989,6 +12989,15 @@ Show all the devices where the filesystems in
C<device> is spanned over.
 If not all the devices for the filesystems are present, then this function
 fails and the C<errno> is set to C<ENODEV>." };

+  { defaults with
+    name = "internal_filesystem_walk"; added = (1, 33, 37);
+    style = RErr, [Mountable "device"; FileOut "filename"],
[];
+    proc_nr = Some 466;
+    visibility = VInternal;
+    optional = Some "libtsk";
+    shortdesc = "walk through the filesystem content";
+    longdesc = "Internal function for filesystem_walk." };
+
 ]

 (* Non-API meta-commands available only in guestfish.
diff --git a/generator/structs.ml b/generator/structs.ml
index 6017ba6..3c2cc61 100644
--- a/generator/structs.ml
+++ b/generator/structs.ml
@@ -444,6 +444,19 @@ let structs = [
     ];
     s_camel_name = "InternalMountable";
   };
+
+  (* The Sleuth Kit directory entry information. *)
+  { defaults with
+    s_name = "tsk_dirent";
+    s_cols = [
+    "tsk_inode", FUInt64;
+    "tsk_type", FChar;
+    "tsk_size", FInt64;
+    "tsk_name", FString;
+    "tsk_flags", FUInt32;
+    ];
+    s_camel_name = "TSKDirent" };
+
 ] (* end of structs *)

 let lookup_struct name diff --git a/m4/guestfs_daemon.m4 b/m4/guestfs_daemon.m4
index 88936b2..192583b 100644
--- a/m4/guestfs_daemon.m4
+++ b/m4/guestfs_daemon.m4
@@ -118,3 +118,11 @@ PKG_CHECK_MODULES([SD_JOURNAL], [libsystemd],[
         AC_MSG_WARN([systemd journal library not found, some features will be
disabled])
     ])
 ])
+
+dnl libtsk sleuthkit library (optional)
+AC_CHECK_LIB([tsk],[tsk_version_print],[
+    AC_CHECK_HEADER([tsk/libtsk.h],[
+        AC_SUBST([TSK_LIBS], [-ltsk])
+        AC_DEFINE([HAVE_LIBTSK], [1], [Define to 1 if The Sleuth Kit library
(libtsk) is available.])
+    ], [])
+],[AC_MSG_WARN([The Sleuth Kit library (libtsk) not found])])
diff --git a/src/MAX_PROC_NR b/src/MAX_PROC_NR
index 073c57b..f27d46f 100644
--- a/src/MAX_PROC_NR
+++ b/src/MAX_PROC_NR
@@ -1 +1 @@
-465
+466
--
2.8.1