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[Libguestfs] [Hivex][PATCH v2] Report last-modified time of hive root and nodes



The infrastructure for modified-time reporting has been essentially
unused.  These changes report the registry time by treating the
time fields as Windows filetime fields stored in little-Endian
(which means they can be treated as a single 64-bit little-Endian
integer).

This patch adds the node_mtime function to the visitor API.

Signed-off-by: Alex Nelson <ajnelson cs ucsc edu>
---
 generator/generator.ml |    3 ++
 lib/hivex.c            |   95 ++++++++++++++++++++++++++++++++++++++++++++++--
 xml/hivexml.c          |   18 +++++++++-
 3 files changed, 112 insertions(+), 4 deletions(-)

diff --git a/generator/generator.ml b/generator/generator.ml
index 31478cd..36615f7 100755
--- a/generator/generator.ml
+++ b/generator/generator.ml
@@ -772,6 +772,7 @@ struct hivex_visitor {
   int (*value_none) (hive_h *, void *opaque, hive_node_h, hive_value_h, hive_type t, size_t len, const char *key, const char *value);
   int (*value_other) (hive_h *, void *opaque, hive_node_h, hive_value_h, hive_type t, size_t len, const char *key, const char *value);
   int (*value_any) (hive_h *, void *opaque, hive_node_h, hive_value_h, hive_type t, size_t len, const char *key, const char *value);
+  int (*node_mtime) (hive_h *h, void *writer_v, hive_node_h node, const char *last_modified);
 };
 
 #define HIVEX_VISIT_SKIP_BAD 1
@@ -1134,6 +1135,8 @@ all, set the function pointer to NULL.
     */
    int (*value_any) (hive_h *, void *opaque, hive_node_h, hive_value_h,
          hive_type t, size_t len, const char *key, const char *value);
+   int (*node_mtime) (hive_h *h, void *writer_v, hive_node_h node,
+         const char *last_modified)
  };
 
 =over 4
diff --git a/lib/hivex.c b/lib/hivex.c
index fedbb6c..4f3dcb1 100644
--- a/lib/hivex.c
+++ b/lib/hivex.c
@@ -33,6 +33,7 @@
 #include <sys/mman.h>
 #include <sys/stat.h>
 #include <assert.h>
+#include <time.h>
 
 #include "c-ctype.h"
 #include "full-read.h"
@@ -93,6 +94,7 @@ struct hive_h {
   /* Fields from the header, extracted from little-endianness hell. */
   size_t rootoffs;              /* Root key offset (always an nk-block). */
   size_t endpages;              /* Offset of end of pages. */
+  char *last_modified;          /* mtime of base block. */
 
   /* For writing. */
   size_t endblocks;             /* Offset to next block allocation (0
@@ -104,7 +106,7 @@ struct ntreg_header {
   char magic[4];                /* "regf" */
   uint32_t sequence1;
   uint32_t sequence2;
-  char last_modified[8];
+  uint64_t last_modified;
   uint32_t major_ver;           /* 1 */
   uint32_t minor_ver;           /* 3 */
   uint32_t unknown5;            /* 0 */
@@ -173,7 +175,7 @@ struct ntreg_nk_record {
   int32_t seg_len;              /* length (always -ve because used) */
   char id[2];                   /* "nk" */
   uint16_t flags;
-  char timestamp[8];
+  uint64_t timestamp;
   uint32_t unknown1;
   uint32_t parent;              /* offset of owner/parent */
   uint32_t nr_subkeys;          /* number of subkeys */
@@ -265,7 +267,34 @@ header_checksum (const hive_h *h)
   return sum;
 }
 
+#define WINDOWS_TICK 10000000LL
+#define SEC_TO_UNIX_EPOCH 11644473600LL
+/**
+ * Convert Windows filetime to ISO 8601 format.
+ * Source for filetime->time_t conversion:  http://stackoverflow.com/questions/6161776/convert-windows-filetime-to-second-in-unix-linux/6161842#6161842
+ * Source for time_t->char* conversion:  Fiwalk version 0.6.14's fiwalk.cpp.
+ * @param windows_ticks Expected to not have any remaining Endian issues.
+ */
+int
+filetime_to_8601 (char *buf, int bufsize, uint64_t windows_ticks)
+{
+  if (buf == NULL) {
+    fprintf (stderr, "filetime_to_8601: Received null output buffer, unable to proceed.\n");
+    return -1;
+  }
+  uint64_t nanos = windows_ticks % WINDOWS_TICK;
+  time_t tt = (windows_ticks / WINDOWS_TICK - SEC_TO_UNIX_EPOCH);
+  struct tm time_tm;
+  if (gmtime_r (&tt, &time_tm) == NULL) {
+    fprintf (stderr, "filetime_to_8601: Error running gmtime_r on timestamp (decimal hundreds of ns: %" PRIu64 ").\n", windows_ticks);
+    return -1;
+  }
+  strftime(buf, bufsize, "%FT%TZ", &time_tm);
+  return 0;
+}
+
 #define HIVEX_OPEN_MSGLVL_MASK (HIVEX_OPEN_VERBOSE|HIVEX_OPEN_DEBUG)
+#define TIMESTAMP_BUF_LEN 32
 
 hive_h *
 hivex_open (const char *filename, int flags)
@@ -359,6 +388,15 @@ hivex_open (const char *filename, int flags)
     goto error;
   }
 
+  /* Last-modified time. */
+  h->last_modified = (char *) calloc(1 + TIMESTAMP_BUF_LEN, sizeof(char));
+  int ft_rc = filetime_to_8601(h->last_modified, TIMESTAMP_BUF_LEN, le64toh ((uint64_t) h->hdr->last_modified));
+  if (ft_rc) {
+    fprintf (stderr, "hivex: failed to parse time value\n");
+    free(h->last_modified);
+    h->last_modified = NULL;
+  }
+
   if (h->msglvl >= 2) {
     char *name = windows_utf16_to_utf8 (h->hdr->name, 64);
 
@@ -367,6 +405,8 @@ hivex_open (const char *filename, int flags)
              "  file version             %" PRIu32 ".%" PRIu32 "\n"
              "  sequence nos             %" PRIu32 " %" PRIu32 "\n"
              "    (sequences nos should match if hive was synched at shutdown)\n"
+             "  last modified            %s\n"
+             "    (decimal, 100 ns)      %" PRIu64 "\n"
              "  original file name       %s\n"
              "    (only 32 chars are stored, name is probably truncated)\n"
              "  root offset              0x%x + 0x1000\n"
@@ -374,6 +414,8 @@ hivex_open (const char *filename, int flags)
              "  checksum                 0x%x (calculated 0x%x)\n",
              major_ver, le32toh (h->hdr->minor_ver),
              le32toh (h->hdr->sequence1), le32toh (h->hdr->sequence2),
+             h->last_modified,
+             le64toh (h->hdr->last_modified),
              name ? name : "(conversion failed)",
              le32toh (h->hdr->offset),
              le32toh (h->hdr->blocks), h->size,
@@ -541,6 +583,10 @@ hivex_close (hive_h *h)
   if (h->msglvl >= 1)
     fprintf (stderr, "hivex_close\n");
 
+  if (h->last_modified) {
+    free (h->last_modified);
+    h->last_modified = NULL;
+  }
   free (h->bitmap);
   if (!h->writable)
     munmap (h->addr, h->size);
@@ -608,6 +654,33 @@ hivex_node_name (hive_h *h, hive_node_h node)
   return ret;
 }
 
+/* Caller responsible for freeing returned char* if non-null. */
+char *
+hivex_node_mtime (hive_h *h, hive_node_h node)
+{
+  int ft_rc;
+  if (!IS_VALID_BLOCK (h, node) || !BLOCK_ID_EQ (h, node, "nk")) {
+    errno = EINVAL;
+    return NULL;
+  }
+
+  struct ntreg_nk_record *nk = (struct ntreg_nk_record *) (h->addr + node);
+
+  char *ret = calloc (32 + 1, sizeof(char));
+  if (ret == NULL)
+    return ret;
+  ft_rc = filetime_to_8601 (ret, 32, le64toh (nk->timestamp));
+  if (h->msglvl >= 2) {
+    fprintf(stderr, "hivex_node_mtime: nk->timestamp: %" PRIu64 "\n", nk->timestamp);
+    fprintf(stderr, "hivex_node_mtime: ret: %s\n", ret);
+  }
+  if (ft_rc) {
+    free(ret);
+    ret = NULL;
+  }
+  return ret;
+}
+
 #if 0
 /* I think the documentation for the sk and classname fields in the nk
  * record is wrong, or else the offset field is in the wrong place.
@@ -1560,6 +1633,7 @@ hivex__visit_node (hive_h *h, hive_node_h node,
 {
   int skip_bad = flags & HIVEX_VISIT_SKIP_BAD;
   char *name = NULL;
+  char *last_modified = NULL;
   hive_value_h *values = NULL;
   hive_node_h *children = NULL;
   char *key = NULL;
@@ -1584,10 +1658,24 @@ hivex__visit_node (hive_h *h, hive_node_h node,
   BITMAP_CLR (unvisited, node);
 
   name = hivex_node_name (h, node);
+  last_modified = hivex_node_mtime (h, node);
+  if (h->msglvl >= 2)
+    fprintf(stderr, "hivex__visit_node: last_modified: %s\n", last_modified ? last_modified : "NULL" );
   if (!name) return skip_bad ? 0 : -1;
+
+  /* Report extra for hive's root node. */
+  if (node == hivex_root (h)) {
+    //Produce mtime for hive, not present node
+    if (vtor->node_mtime && vtor->node_mtime (h, opaque, node, h->last_modified) == -1)
+      goto error;
+  }
+
   if (vtor->node_start && vtor->node_start (h, opaque, node, name) == -1)
     goto error;
 
+  if (vtor->node_mtime && vtor->node_mtime (h, opaque, node, last_modified) == -1)
+    goto error;
+
   values = hivex_node_values (h, node);
   if (!values) {
     ret = skip_bad ? 0 : -1;
@@ -1764,6 +1852,7 @@ hivex__visit_node (hive_h *h, hive_node_h node,
 
  error:
   free (name);
+  free (last_modified);
   free (values);
   free (children);
   free (key);
@@ -2264,7 +2353,7 @@ hivex_node_add_child (hive_h *h, hive_node_h parent, const char *name)
   nk->sk = htole32 (parent_sk_offset - 0x1000);
 
   /* Inherit parent timestamp. */
-  memcpy (nk->timestamp, parent_nk->timestamp, sizeof (parent_nk->timestamp));
+  nk->timestamp = parent_nk->timestamp;
 
   /* What I found out the hard way (not documented anywhere): the
    * subkeys in lh-records must be kept sorted.  If you just add a
diff --git a/xml/hivexml.c b/xml/hivexml.c
index 90cb22b..25e8cd9 100644
--- a/xml/hivexml.c
+++ b/xml/hivexml.c
@@ -50,6 +50,7 @@ static int value_qword (hive_h *, void *, hive_node_h, hive_value_h, hive_type t
 static int value_binary (hive_h *, void *, hive_node_h, hive_value_h, hive_type t, size_t len, const char *key, const char *value);
 static int value_none (hive_h *, void *, hive_node_h, hive_value_h, hive_type t, size_t len, const char *key, const char *value);
 static int value_other (hive_h *, void *, hive_node_h, hive_value_h, hive_type t, size_t len, const char *key, const char *value);
+static int node_mtime (hive_h *h, void *writer_v, hive_node_h node, const char *last_modified);
 
 static struct hivex_visitor visitor = {
   .node_start = node_start,
@@ -61,7 +62,8 @@ static struct hivex_visitor visitor = {
   .value_qword = value_qword,
   .value_binary = value_binary,
   .value_none = value_none,
-  .value_other = value_other
+  .value_other = value_other,
+  .node_mtime = node_mtime
 };
 
 #define XML_CHECK(proc, args)                                           \
@@ -142,6 +144,20 @@ main (int argc, char *argv[])
 }
 
 static int
+node_mtime (hive_h *h, void *writer_v, hive_node_h node, const char *last_modified)
+{
+  if (!last_modified) {
+    fprintf(stderr, "node_mtime:  last_modified came across NULL.\n");
+    return -1;
+  }
+  xmlTextWriterPtr writer = (xmlTextWriterPtr) writer_v;
+  XML_CHECK (xmlTextWriterStartElement, (writer, BAD_CAST "mtime"));
+  XML_CHECK (xmlTextWriterWriteString, (writer, BAD_CAST last_modified));
+  XML_CHECK (xmlTextWriterEndElement, (writer));
+  return 0;
+}
+
+static int
 node_start (hive_h *h, void *writer_v, hive_node_h node, const char *name)
 {
   xmlTextWriterPtr writer = (xmlTextWriterPtr) writer_v;
-- 
1.7.6




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