[Libguestfs] [PATCH 11/14] hivex: Complete the implementation of adding child nodes.
Richard Jones
rjones at redhat.com
Fri Feb 5 13:07:04 UTC 2010
---
hivex/example5 | 54 ++++++++++
hivex/hivex.c | 287 +++++++++++++++++++++++++++++++++++++++++++++++++++-
hivex/hivex.pod | 19 +++-
hivex/hivexsh.c | 16 +++-
hivex/hivexsh.pod | 14 +++
5 files changed, 378 insertions(+), 12 deletions(-)
create mode 100755 hivex/example5
diff --git a/hivex/example5 b/hivex/example5
new file mode 100755
index 0000000..ccf711c
--- /dev/null
+++ b/hivex/example5
@@ -0,0 +1,54 @@
+#!/bin/bash -
+# Copyright (C) 2009-2010 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., 675 Mass Ave, Cambridge, MA 02139, USA.
+
+set -e
+
+# This script adds a new node under \Microsoft in an existing software
+# hive.
+
+if [ $# -ne 2 ]; then
+ echo "$0 software software.new"
+ exit 1
+fi
+
+d=`dirname $0`
+
+$d/hivexsh -w <<EOF
+load $1
+cd \Microsoft
+add TestNode
+cd TestNode
+add Test1
+add Test2
+add Test3
+add Test4
+add Test5
+cd Test1
+setval 2
+@
+string:This is the default key of Test1
+ThisIsTest1
+dword:0x12345678
+cd ..
+cd Test5
+setval 2
+@
+string:This is the default key of Test5
+ThisIsTest5
+dword:0x87654321
+commit $2
+EOF
\ No newline at end of file
diff --git a/hivex/hivex.c b/hivex/hivex.c
index 2a094b8..148d837 100644
--- a/hivex/hivex.c
+++ b/hivex/hivex.c
@@ -34,6 +34,7 @@
#include <sys/stat.h>
#include <assert.h>
+#include "c-ctype.h"
#include "full-read.h"
#include "full-write.h"
@@ -49,7 +50,7 @@
//#define STRCASEEQLEN(a,b,n) (strncasecmp((a),(b),(n)) == 0)
//#define STRNEQLEN(a,b,n) (strncmp((a),(b),(n)) != 0)
//#define STRCASENEQLEN(a,b,n) (strncasecmp((a),(b),(n)) != 0)
-//#define STRPREFIX(a,b) (strncmp((a),(b),strlen((b))) == 0)
+#define STRPREFIX(a,b) (strncmp((a),(b),strlen((b))) == 0)
#include "hivex.h"
#include "byte_conversions.h"
@@ -1987,7 +1988,117 @@ hivex_commit (hive_h *h, const char *filename, int flags)
return 0;
}
-#if 0
+/* Calculate the hash for a lf or lh record offset.
+ */
+static void
+calc_hash (const char *type, const char *name, char *ret)
+{
+ size_t len = strlen (name);
+
+ if (STRPREFIX (type, "lf"))
+ /* Old-style, not used in current registries. */
+ memcpy (ret, name, len < 4 ? len : 4);
+ else {
+ /* New-style for lh-records. */
+ size_t i, c;
+ uint32_t h = 0;
+ for (i = 0; i < len; ++i) {
+ c = c_toupper (name[i]);
+ h *= 37;
+ h += c;
+ }
+ *((uint32_t *) ret) = htole32 (h);
+ }
+}
+
+/* Create a completely new lh-record containing just the single node. */
+static size_t
+new_lh_record (hive_h *h, const char *name, hive_node_h node)
+{
+ static const char id[2] = { 'l', 'h' };
+ size_t seg_len = sizeof (struct ntreg_lf_record);
+ size_t offset = allocate_block (h, seg_len, id);
+ if (offset == 0)
+ return 0;
+
+ struct ntreg_lf_record *lh = (struct ntreg_lf_record *) (h->addr + offset);
+ lh->nr_keys = htole16 (1);
+ lh->keys[0].offset = htole32 (node - 0x1000);
+ calc_hash ("lh", name, lh->keys[0].hash);
+
+ return offset;
+}
+
+/* Insert node into existing lf/lh-record at position.
+ * This allocates a new record and marks the old one as unused.
+ */
+static size_t
+insert_lf_record (hive_h *h, size_t old_offs, size_t posn,
+ const char *name, hive_node_h node)
+{
+ assert (IS_VALID_BLOCK (h, old_offs));
+
+ /* Work around C stupidity.
+ * http://www.redhat.com/archives/libguestfs/2010-February/msg00056.html
+ */
+ int test = BLOCK_ID_EQ (h, old_offs, "lf") || BLOCK_ID_EQ (h, old_offs, "lh");
+ assert (test);
+
+ struct ntreg_lf_record *old_lf =
+ (struct ntreg_lf_record *) (h->addr + old_offs);
+ size_t nr_keys = le16toh (old_lf->nr_keys);
+
+ nr_keys++; /* in new record ... */
+
+ size_t seg_len = sizeof (struct ntreg_lf_record) + (nr_keys-1) * 8;
+ size_t new_offs = allocate_block (h, seg_len, old_lf->id);
+ if (new_offs == 0)
+ return 0;
+
+ struct ntreg_lf_record *new_lf =
+ (struct ntreg_lf_record *) (h->addr + new_offs);
+ new_lf->nr_keys = htole16 (nr_keys);
+
+ /* Copy the keys until we reach posn, insert the new key there, then
+ * copy the remaining keys.
+ */
+ size_t i;
+ for (i = 0; i < posn; ++i)
+ new_lf->keys[i] = old_lf->keys[i];
+
+ new_lf->keys[i].offset = htole32 (node - 0x1000);
+ calc_hash (new_lf->id, name, new_lf->keys[i].hash);
+
+ for (i = posn+1; i < nr_keys; ++i)
+ new_lf->keys[i] = old_lf->keys[i-1];
+
+ /* Old block is unused, return new block. */
+ mark_block_unused (h, old_offs);
+ return new_offs;
+}
+
+/* Compare name with name in nk-record. */
+static int
+compare_name_with_nk_name (hive_h *h, const char *name, hive_node_h nk_offs)
+{
+ assert (IS_VALID_BLOCK (h, nk_offs));
+ assert (BLOCK_ID_EQ (h, nk_offs, "nk"));
+
+ /* Name in nk is not necessarily nul-terminated. */
+ char *nname = hivex_node_name (h, nk_offs);
+
+ /* Unfortunately we don't have a way to return errors here. */
+ if (!nname) {
+ perror ("compare_name_with_nk_name");
+ return 0;
+ }
+
+ int r = strcasecmp (name, nname);
+ free (nname);
+
+ return r;
+}
+
hive_node_h
hivex_node_add_child (hive_h *h, hive_node_h parent, const char *name)
{
@@ -1998,21 +2109,185 @@ hivex_node_add_child (hive_h *h, hive_node_h parent, const char *name)
if (!IS_VALID_BLOCK (h, parent) || !BLOCK_ID_EQ (h, parent, "nk")) {
errno = EINVAL;
- return -1;
+ return 0;
}
- if (name == NULL) {
+ if (name == NULL || strlen (name) == 0) {
errno = EINVAL;
- return -1;
+ return 0;
+ }
+
+ if (hivex_node_get_child (h, parent, name) != 0) {
+ errno = EEXIST;
+ return 0;
}
+ /* Create the new nk-record. */
+ static const char nk_id[2] = { 'n', 'k' };
+ size_t seg_len = sizeof (struct ntreg_nk_record) + strlen (name);
+ hive_node_h node = allocate_block (h, seg_len, nk_id);
+ if (node == 0)
+ return 0;
+
+ if (h->msglvl >= 2)
+ fprintf (stderr, "hivex_node_add_child: allocated new nk-record for child at 0x%zx\n", node);
+
+ struct ntreg_nk_record *nk = (struct ntreg_nk_record *) (h->addr + node);
+ nk->flags = htole16 (0x0020); /* key is ASCII. */
+ nk->parent = htole32 (parent - 0x1000);
+ nk->subkey_lf = htole32 (0xffffffff);
+ nk->subkey_lf_volatile = htole32 (0xffffffff);
+ nk->vallist = htole32 (0xffffffff);
+ nk->classname = htole32 (0xffffffff);
+ nk->name_len = htole16 (strlen (name));
+ strcpy (nk->name, name);
+
+ /* Inherit parent sk. */
+ struct ntreg_nk_record *parent_nk =
+ (struct ntreg_nk_record *) (h->addr + parent);
+ size_t parent_sk_offset = le32toh (parent_nk->sk);
+ parent_sk_offset += 0x1000;
+ if (!IS_VALID_BLOCK (h, parent_sk_offset) ||
+ !BLOCK_ID_EQ (h, parent_sk_offset, "sk")) {
+ if (h->msglvl >= 2)
+ fprintf (stderr, "hivex_node_add_child: returning EFAULT because parent sk is not a valid block (%zu)\n",
+ parent_sk_offset);
+ errno = EFAULT;
+ return 0;
+ }
+ struct ntreg_sk_record *sk =
+ (struct ntreg_sk_record *) (h->addr + parent_sk_offset);
+ sk->refcount = htole32 (le32toh (sk->refcount) + 1);
+ nk->sk = htole32 (parent_sk_offset - 0x1000);
+
+ /* Inherit parent timestamp. */
+ memcpy (nk->timestamp, parent_nk->timestamp, sizeof (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
+ * subkey in a non-sorted position (eg. just add it at the end) then
+ * Windows won't see the subkey _and_ Windows will corrupt the hive
+ * itself when it modifies or saves it.
+ *
+ * So use get_children() to get a list of intermediate
+ * lf/lh-records. get_children() returns these in reading order
+ * (which is sorted), so we look for the lf/lh-records in sequence
+ * until we find the key name just after the one we are inserting,
+ * and we insert the subkey just before it.
+ *
+ * The only other case is the no-subkeys case, where we have to
+ * create a brand new lh-record.
+ */
+ hive_node_h *unused;
+ size_t *blocks;
+
+ if (get_children (h, parent, &unused, &blocks, 0) == -1)
+ return 0;
+ free (unused);
+
+ size_t i, j;
+ size_t nr_subkeys_in_parent_nk = le32toh (parent_nk->nr_subkeys);
+ if (nr_subkeys_in_parent_nk == 0) { /* No subkeys case. */
+ /* Free up any existing intermediate blocks. */
+ for (i = 0; blocks[i] != 0; ++i)
+ mark_block_unused (h, blocks[i]);
+ size_t lh_offs = new_lh_record (h, name, node);
+ if (lh_offs == 0) {
+ free (blocks);
+ return 0;
+ }
+
+ if (h->msglvl >= 2)
+ fprintf (stderr, "hivex_node_add_child: no keys, allocated new lh-record at 0x%zx\n", lh_offs);
+
+ parent_nk->subkey_lf = htole32 (lh_offs - 0x1000);
+ }
+ else { /* Insert subkeys case. */
+ size_t old_offs = 0, new_offs = 0;
+ struct ntreg_lf_record *old_lf = NULL;
+
+ /* Find lf/lh key name just after the one we are inserting. */
+ for (i = 0; blocks[i] != 0; ++i) {
+ if (BLOCK_ID_EQ (h, blocks[i], "lf") ||
+ BLOCK_ID_EQ (h, blocks[i], "lh")) {
+ old_offs = blocks[i];
+ old_lf = (struct ntreg_lf_record *) (h->addr + old_offs);
+ for (j = 0; j < le16toh (old_lf->nr_keys); ++j) {
+ hive_node_h nk_offs = le32toh (old_lf->keys[j].offset);
+ nk_offs += 0x1000;
+ if (compare_name_with_nk_name (h, name, nk_offs) < 0)
+ goto insert_it;
+ }
+ }
+ }
+
+ /* Insert it at the end.
+ * old_offs points to the last lf record, set j.
+ */
+ assert (old_offs != 0); /* should never happen if nr_subkeys > 0 */
+ j = le16toh (old_lf->nr_keys);
+
+ /* Insert it. */
+ insert_it:
+ if (h->msglvl >= 2)
+ fprintf (stderr, "hivex_node_add_child: insert key in existing lh-record at 0x%zx, posn %zu\n", old_offs, j);
+
+ new_offs = insert_lf_record (h, old_offs, j, name, node);
+ if (new_offs == 0) {
+ free (blocks);
+ return 0;
+ }
+
+ if (h->msglvl >= 2)
+ fprintf (stderr, "hivex_node_add_child: new lh-record at 0x%zx\n",
+ new_offs);
+
+ /* If the lf/lh-record was directly referenced by the parent nk,
+ * then update the parent nk.
+ */
+ if (le32toh (parent_nk->subkey_lf) + 0x1000 == old_offs)
+ parent_nk->subkey_lf = htole32 (new_offs - 0x1000);
+ /* Else we have to look for the intermediate ri-record and update
+ * that in-place.
+ */
+ else {
+ for (i = 0; blocks[i] != 0; ++i) {
+ if (BLOCK_ID_EQ (h, blocks[i], "ri")) {
+ struct ntreg_ri_record *ri =
+ (struct ntreg_ri_record *) (h->addr + blocks[i]);
+ for (j = 0; j < le16toh (ri->nr_offsets); ++j)
+ if (le32toh (ri->offset[j] + 0x1000) == old_offs) {
+ ri->offset[j] = htole32 (new_offs - 0x1000);
+ goto found_it;
+ }
+ }
+ }
+ /* Not found .. This is an internal error. */
+ if (h->msglvl >= 2)
+ fprintf (stderr, "hivex_node_add_child: returning ENOTSUP because could not find ri->lf link\n");
+ errno = ENOTSUP;
+ free (blocks);
+ return 0;
+
+ found_it:
+ ;
+ }
+ }
+ free (blocks);
+ /* Update nr_subkeys in parent nk. */
+ nr_subkeys_in_parent_nk++;
+ parent_nk->nr_subkeys = htole32 (nr_subkeys_in_parent_nk);
+ /* Update max_subkey_name_len in parent nk. */
+ uint16_t max = le16toh (parent_nk->max_subkey_name_len);
+ if (max < strlen (name) * 2) /* *2 because "recoded" in UTF16-LE. */
+ parent_nk->max_subkey_name_len = htole16 (strlen (name) * 2);
+ return node;
}
-#endif
/* Decrement the refcount of an sk-record, and if it reaches zero,
* unlink it from the chain and delete it.
diff --git a/hivex/hivex.pod b/hivex/hivex.pod
index 34ff253..275eb42 100644
--- a/hivex/hivex.pod
+++ b/hivex/hivex.pod
@@ -383,9 +383,12 @@ C<hivex_close> after this.
Add a new child node named C<name> to the existing node C<parent>.
The new child initially has no subnodes and contains no keys or
-values. The parent must not have an existing child called C<name>, so
-if you want to overwrite an existing child, call
-C<hivex_node_delete_child> first.
+values. The sk-record (security descriptor) is inherited from
+the parent.
+
+The parent must not have an existing child called C<name>, so if you
+want to overwrite an existing child, call C<hivex_node_delete_child>
+first.
Returns the node handle. On error this returns 0 and sets errno.
@@ -460,8 +463,10 @@ Modifying or deleting single values at a node.
=item *
-Modifying security key (sk) records or classnames. These are not
-well understood.
+Modifying security key (sk) records or classnames.
+Previously we did not understand these records. However now they
+are well-understood and we could add support if it was required
+(but nothing much really uses them).
=back
@@ -591,6 +596,10 @@ Registry contains cycles.
Field in the registry out of range.
+=item EEXIST
+
+Registry key already exists.
+
=item EROFS
Tried to write to a registry which is not opened for writing.
diff --git a/hivex/hivexsh.c b/hivex/hivexsh.c
index d5d9ada..9c54536 100644
--- a/hivex/hivexsh.c
+++ b/hivex/hivexsh.c
@@ -76,6 +76,7 @@ static char *rl_gets (const char *prompt_string);
static void sort_strings (char **strings, int len);
static int get_xdigit (char c);
static int dispatch (char *cmd, char *args);
+static int cmd_add (char *name);
static int cmd_cd (char *path);
static int cmd_close (char *path);
static int cmd_commit (char *path);
@@ -411,7 +412,9 @@ dispatch (char *cmd, char *args)
return -1;
}
- if (STRCASEEQ (cmd, "cd"))
+ if (STRCASEEQ (cmd, "add"))
+ return cmd_add (args);
+ else if (STRCASEEQ (cmd, "cd"))
return cmd_cd (args);
else if (STRCASEEQ (cmd, "close") || STRCASEEQ (cmd, "unload"))
return cmd_close (args);
@@ -1077,3 +1080,14 @@ cmd_del (char *args)
set_prompt_string ();
return 0;
}
+
+static int
+cmd_add (char *name)
+{
+ hive_node_h node = hivex_node_add_child (h, cwd, name);
+ if (node == 0) {
+ perror ("hivexsh: add");
+ return -1;
+ }
+ return 0;
+}
diff --git a/hivex/hivexsh.pod b/hivex/hivexsh.pod
index 9336798..a31d9e0 100644
--- a/hivex/hivexsh.pod
+++ b/hivex/hivexsh.pod
@@ -79,6 +79,20 @@ If this option is not given, then write commands are disabled.
=over 4
+=item B<add> name
+
+Add a subkey named C<name> below the current node. The name may
+contain spaces and punctuation characters, and does not need to be
+quoted.
+
+The new key will have no subkeys and no values (see C<setval>).
+
+There must be no existing subkey called C<name>, or this command will
+fail. To replace an existing subkey, delete it first like this:
+
+ cd name
+ del
+
=item B<cd> path
Change to the subkey C<path>. Use Windows-style backslashes to
--
1.6.5.2
More information about the Libguestfs
mailing list