[Libguestfs] [PATCH v3 2/6] New API: yara_load

Matteo Cafasso
2016-12-18T10:47:07Z

The yara_load API allows to load a set of Yara rules contained within a
file on the host.

Rules can be in binary format, as when compiled with yarac command, or
in source code format. In the latter case, the rules will be first
compiled and then loaded.

Subsequent calls of the yara_load API will result in the discard of the
previously loaded rules.

Signed-off-by: Matteo Cafasso <noxdafox@gmail.com>
---
 daemon/Makefile.am   |   1 +
 daemon/cleanups.c    |   9 +++
 daemon/cleanups.h    |   2 +
 daemon/yara.c        | 201 +++++++++++++++++++++++++++++++++++++++++++++++++++
 generator/actions.ml |  20 +++++
 gobject/Makefile.inc |   6 +-
 src/MAX_PROC_NR      |   2 +-
 7 files changed, 238 insertions(+), 3 deletions(-)
 create mode 100644 daemon/yara.c

diff --git a/daemon/Makefile.am b/daemon/Makefile.am
index 3a25f43..c385edc 100644
--- a/daemon/Makefile.am
+++ b/daemon/Makefile.am
@@ -200,6 +200,7 @@ guestfsd_SOURCES = \
 	wc.c \
 	xattr.c \
 	xfs.c \
+	yara.c \
 	zero.c \
 	zerofree.c

diff --git a/daemon/cleanups.c b/daemon/cleanups.c
index 092e493..3102cf9 100644
--- a/daemon/cleanups.c
+++ b/daemon/cleanups.c
@@ -62,6 +62,15 @@ cleanup_close (void *ptr)
 }

 void
+cleanup_fclose (void *ptr)
+{
+  FILE *f = * (FILE **) ptr;
+
+  if (f)
+    fclose (f);
+}
+
+void
 cleanup_aug_close (void *ptr)
 {
   augeas *aug = * (augeas **) ptr;
diff --git a/daemon/cleanups.h b/daemon/cleanups.h
index 6746e27..a791244 100644
--- a/daemon/cleanups.h
+++ b/daemon/cleanups.h
@@ -26,6 +26,7 @@ extern void cleanup_free (void *ptr);
 extern void cleanup_free_string_list (void *ptr);
 extern void cleanup_unlink_free (void *ptr);
 extern void cleanup_close (void *ptr);
+extern void cleanup_fclose (void *ptr);
 extern void cleanup_aug_close (void *ptr);
 extern void cleanup_free_stringsbuf (void *ptr);

@@ -35,6 +36,7 @@ extern void cleanup_free_stringsbuf (void *ptr);
     __attribute__((cleanup(cleanup_free_string_list)))
 #define CLEANUP_UNLINK_FREE __attribute__((cleanup(cleanup_unlink_free)))
 #define CLEANUP_CLOSE __attribute__((cleanup(cleanup_close)))
+#define CLEANUP_FCLOSE __attribute__((cleanup(cleanup_fclose)))
 #define CLEANUP_AUG_CLOSE __attribute__((cleanup(cleanup_aug_close)))
 #define CLEANUP_FREE_STRINGSBUF
__attribute__((cleanup(cleanup_free_stringsbuf)))
 #else
diff --git a/daemon/yara.c b/daemon/yara.c
new file mode 100644
index 0000000..0e4128a
--- /dev/null
+++ b/daemon/yara.c
@@ -0,0 +1,201 @@
+/* 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 <fcntl.h>
+#include <stdlib.h>
+#include <inttypes.h>
+#include <string.h>
+#include <unistd.h>
+#include <stdbool.h>
+#include <rpc/xdr.h>
+#include <rpc/types.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+
+#include "daemon.h"
+#include "actions.h"
+#include "optgroups.h"
+#include "guestfs_protocol.h"
+
+#ifdef HAVE_YARA
+
+#include <yara.h>
+
+#define CLEANUP_DESTROY_YARA_COMPILER                           \
+  __attribute__((cleanup(cleanup_destroy_yara_compiler)))
+
+struct write_callback_data {
+  int fd;
+  uint64_t written;
+};
+
+/* Yara compiled rules. */
+static YR_RULES *rules = NULL;
+static bool initialized = false;
+
+static int compile_rules_file (const char *, const char *);
+static void compile_error_callback (int, const char *, int, const char *, void
*);
+static void cleanup_destroy_yara_compiler (void *ptr);
+
+/* Has one FileIn parameter.
+ * Takes optional arguments, consult optargs_bitmask.
+ */
+int
+do_yara_load (const char *namespace)
+{
+  int ret = 0;
+  CLEANUP_CLOSE int fd = -1;
+  char tmpfile[] = "/tmp/yaraXXXXXX";
+
+  fd = mkstemp (tmpfile);
+  if (fd == -1) {
+    reply_with_perror ("mkstemp");
+    return -1;
+  }
+
+  ret = upload_to_fd (fd);
+  if (ret < 0) {
+    unlink (tmpfile);
+    return -1;
+  }
+
+  /* Initialize yara only once. */
+  if (!initialized) {
+    ret = yr_initialize ();
+    if (ret != ERROR_SUCCESS) {
+      reply_with_error ("failed initializing yara");
+      unlink (tmpfile);
+      return -1;
+    }
+
+    initialized = true;
+  }
+
+  /* Clear namespace if no optional parameter is given. */
+  if (!(optargs_bitmask & GUESTFS_YARA_LOAD_NAMESPACE_BITMASK))
+    namespace = NULL;
+
+  /* Try to load the rules as compiled.
+   * If their are in source code format, compile them first.
+   */
+  ret = yr_rules_load (tmpfile, &rules);
+  if (ret == ERROR_INVALID_FILE)
+    ret = compile_rules_file (tmpfile, namespace);
+
+  unlink (tmpfile);
+
+  return (ret == ERROR_SUCCESS) ? 0 : -1;
+}
+
+/* Compile source code rules and load them.
+ * Return ERROR_SUCCESS on success, Yara error code type on error.
+ */
+static int
+compile_rules_file (const char *rules_path, const char *namespace)
+{
+  int ret = 0;
+  CLEANUP_FCLOSE FILE *rule_file = NULL;
+  CLEANUP_DESTROY_YARA_COMPILER YR_COMPILER *compiler = NULL;
+
+  ret = yr_compiler_create (&compiler);
+  if (ret != ERROR_SUCCESS) {
+    reply_with_error ("yr_compiler_create");
+    return ret;
+  }
+
+  yr_compiler_set_callback (compiler, compile_error_callback, NULL);
+
+  rule_file = fopen (rules_path, "r");
+  if (rule_file == NULL) {
+    reply_with_error ("unable to open rules file");
+    return ret;
+  }
+
+  ret = yr_compiler_add_file (compiler, rule_file, namespace, NULL);
+  if (ret > 0)
+    return ret;
+
+  ret = yr_compiler_get_rules (compiler, &rules);
+  if (ret == ERROR_INSUFICIENT_MEMORY) {
+    errno = ENOMEM;
+    reply_with_perror ("yr_compiler_get_rules");
+  }
+
+  return ret;
+}
+
+/* Yara compilation error callback.
+ * Reports back the compilation error message.
+ * Prints compilation warnings if verbose.
+ */
+static void
+compile_error_callback(int level, const char *name, int line,
+                       const char *message, void *data)
+{
+  if (level == YARA_ERROR_LEVEL_ERROR)
+    reply_with_error ("Yara error (line %d): %s", line, message);
+  else if (verbose)
+    fprintf (stderr, "Yara warning (line %d): %s\n", line, message);
+}
+
+/* Clean up yara handle on daemon exit. */
+void yara_finalize (void) __attribute__((destructor));
+
+void
+yara_finalize (void)
+{
+  int ret = 0;
+
+  if (!initialized)
+    return;
+
+  if (rules != NULL) {
+    yr_rules_destroy (rules);
+    rules = NULL;
+  }
+
+  ret = yr_finalize ();
+  if (ret != ERROR_SUCCESS)
+    perror ("yr_finalize");
+
+  initialized = false;
+}
+
+static void
+cleanup_destroy_yara_compiler (void *ptr)
+{
+  YR_COMPILER *compiler = * (YR_COMPILER **) ptr;
+
+  if (compiler != NULL)
+    yr_compiler_destroy (compiler);
+}
+
+int
+optgroup_libyara_available (void)
+{
+  return 1;
+}
+
+#else   /* !HAVE_YARA */
+
+OPTGROUP_YARA_NOT_AVAILABLE
+
+#endif  /* !HAVE_YARA */
diff --git a/generator/actions.ml b/generator/actions.ml
index fb896f5..c5ffc4d 100644
--- a/generator/actions.ml
+++ b/generator/actions.ml
@@ -13266,6 +13266,26 @@ is removed." };
     shortdesc = "search the entries associated to the given inode";
     longdesc = "Internal function for find_inode." };

+  { defaults with
+    name = "yara_load"; added = (1, 35, 19);
+    style = RErr, [FileIn "filename";], [OString
"namespace"];
+    proc_nr = Some 471;
+    progress = true; cancellable = true;
+    optional = Some "libyara";
+    shortdesc = "load yara rules within libguestfs";
+    longdesc = "\
+Load a set of Yara rules from F<filename> within libguestfs appliance.
+
+Rules can be in binary format, as when compiled with yarac command, or
+in source code format. In the latter case, the rules will be first
+compiled and then loaded.
+
+Rules in source code format cannot include external files. In such cases,
+it is recommended to compile them first.
+
+Different rules files can be loaded sequentially. The optional parameter
+C<namespace> can be used to distinguish rules with the same identifier
+but belonging to different files." };
 ]

 (* Non-API meta-commands available only in guestfish.
diff --git a/gobject/Makefile.inc b/gobject/Makefile.inc
index 149e4c6..a41a552 100644
--- a/gobject/Makefile.inc
+++ b/gobject/Makefile.inc
@@ -110,7 +110,8 @@ guestfs_gobject_headers= \
   include/guestfs-gobject/optargs-umount_local.h \
   include/guestfs-gobject/optargs-xfs_admin.h \
   include/guestfs-gobject/optargs-xfs_growfs.h \
-  include/guestfs-gobject/optargs-xfs_repair.h
+  include/guestfs-gobject/optargs-xfs_repair.h \
+  include/guestfs-gobject/optargs-yara_load.h

 guestfs_gobject_sources= \
   src/session.c \
@@ -201,4 +202,5 @@ guestfs_gobject_sources= \
   src/optargs-umount_local.c \
   src/optargs-xfs_admin.c \
   src/optargs-xfs_growfs.c \
-  src/optargs-xfs_repair.c
+  src/optargs-xfs_repair.c \
+  src/optargs-yara_load.c
diff --git a/src/MAX_PROC_NR b/src/MAX_PROC_NR
index 5f476b6..c305aa5 100644
--- a/src/MAX_PROC_NR
+++ b/src/MAX_PROC_NR
@@ -1 +1 @@
-470
+471
--
2.10.2