/*
* Extract component parts of various MS XML files (e.g. MS Office 2003 XML Documents)
*
* Copyright (C) 2013-2019 Cisco Systems, Inc. and/or its affiliates. All rights reserved.
* Copyright (C) 2007-2013 Sourcefire, Inc.
*
* Authors: Kevin Lin
*
* This program is free software; you can redistribute it and/or modify it under
* the terms of the GNU General Public License version 2 as published by the
* Free Software Foundation.
*
* 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.
*/
#if HAVE_CONFIG_H
#include "clamav-config.h"
#endif
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include "clamav.h"
#include "others.h"
#include "conv.h"
#include "scanners.h"
#include "json_api.h"
#include "msxml_parser.h"
#if HAVE_LIBXML2
#include <libxml/xmlreader.h>
#define MSXML_VERBIOSE 0
#if MSXML_VERBIOSE
#define cli_msxmlmsg(...) cli_dbgmsg(__VA_ARGS__)
#else
#define cli_msxmlmsg(...)
#endif
#define check_state(state) \
do { \
if (state == -1) { \
cli_warnmsg("check_state[msxml]: CL_EPARSE @ ln%d\n", __LINE__); \
return CL_EPARSE; \
} else if (state == 0) { \
cli_dbgmsg("check_state[msxml]: CL_BREAK @ ln%d\n", __LINE__); \
return CL_BREAK; \
} \
} while (0)
#define track_json(mxctx) (mxctx->ictx->flags & MSXML_FLAG_JSON)
struct msxml_ictx {
cli_ctx *ctx;
uint32_t flags;
const struct key_entry *keys;
size_t num_keys;
#if HAVE_JSON
json_object *root;
int toval;
#endif
};
struct key_entry blank_key = {NULL, NULL, 0};
static const struct key_entry *msxml_check_key(struct msxml_ictx *ictx, const xmlChar *key, size_t keylen)
{
unsigned i;
if (keylen > MSXML_JSON_STRLEN_MAX - 1) {
cli_dbgmsg("msxml_check_key: key name too long\n");
return &blank_key;
}
for (i = 0; i < ictx->num_keys; ++i) {
if (keylen == strlen(ictx->keys[i].key) && !strncasecmp((char *)key, ictx->keys[i].key, keylen)) {
return &ictx->keys[i];
}
}
return &blank_key;
}
static void msxml_error_handler(void *arg, const char *msg, xmlParserSeverities severity, xmlTextReaderLocatorPtr locator)
{
int line = xmlTextReaderLocatorLineNumber(locator);
xmlChar *URI = xmlTextReaderLocatorBaseURI(locator);
UNUSEDPARAM(arg);
switch (severity) {
case XML_PARSER_SEVERITY_WARNING:
case XML_PARSER_SEVERITY_VALIDITY_WARNING:
cli_dbgmsg("%s:%d: parser warning : %s", (char *)URI, line, msg);
break;
case XML_PARSER_SEVERITY_ERROR:
case XML_PARSER_SEVERITY_VALIDITY_ERROR:
cli_dbgmsg("%s:%d: parser error : %s", (char *)URI, line, msg);
break;
default:
cli_dbgmsg("%s:%d: unknown severity : %s", (char *)URI, line, msg);
break;
}
free(URI);
}
#if HAVE_JSON
static int msxml_is_int(const char *value, size_t len, int32_t *val)
{
long val2;
char *endptr = NULL;
val2 = strtol(value, &endptr, 10);
if (endptr != value + len) {
return 0;
}
*val = (int32_t)(val2 & 0x0000ffff);
return 1;
}
static int msxml_parse_value(json_object *wrkptr, const char *arrname, const xmlChar *node_value)
{
json_object *newobj, *arrobj;
int val;
if (!wrkptr)
return CL_ENULLARG;
arrobj = cli_jsonarray(wrkptr, arrname);
if (arrobj == NULL) {
return CL_EMEM;
}
if (msxml_is_int((const char *)node_value, xmlStrlen(node_value), &val)) {
newobj = json_object_new_int(val);
} else if (!xmlStrcmp(node_value, (const xmlChar *)"true")) {
newobj = json_object_new_boolean(1);
} else if (!xmlStrcmp(node_value, (const xmlChar *)"false")) {
newobj = json_object_new_boolean(0);
} else {
newobj = json_object_new_string((const char *)node_value);
}
if (NULL == newobj) {
cli_errmsg("msxml_parse_value: no memory for json value for [%s]\n", arrname);
return CL_EMEM;
}
json_object_array_add(arrobj, newobj);
return CL_SUCCESS;
}
#endif /* HAVE_JSON */
#define MAX_ATTRIBS 20
static int msxml_parse_element(struct msxml_ctx *mxctx, xmlTextReaderPtr reader, int rlvl, void *jptr)
{
const xmlChar *element_name = NULL;
const xmlChar *node_name = NULL, *node_value = NULL;
const struct key_entry *keyinfo;
struct attrib_entry attribs[MAX_ATTRIBS];
int ret, virus = 0, state, node_type, endtag = 0, num_attribs = 0;
cli_ctx *ctx = mxctx->ictx->ctx;
#if HAVE_JSON
json_object *root = mxctx->ictx->root;
json_object *parent = (json_object *)jptr;
json_object *thisjobj = NULL;
#else
void *parent = NULL;
void *thisjobj = NULL;
#endif
cli_msxmlmsg("in msxml_parse_element @ layer %d\n", rlvl);
/* check recursion level */
if (rlvl >= MSXML_RECLEVEL_MAX) {
cli_dbgmsg("msxml_parse_element: reached msxml json recursion limit\n");
#if HAVE_JSON
if (track_json(mxctx)) {
int tmp = cli_json_parse_error(root, "MSXML_RECURSIVE_LIMIT");
if (tmp != CL_SUCCESS)
return tmp;
}
#endif
/* skip it */
state = xmlTextReaderNext(reader);
check_state(state);
return CL_SUCCESS;
}
/* acquire element type */
node_type = xmlTextReaderNodeType(reader);
if (node_type == -1)
return CL_EPARSE;
node_name = xmlTextReaderConstLocalName(reader);
node_value = xmlTextReaderConstValue(reader);
/* branch on node type */
switch (node_type) {
case XML_READER_TYPE_ELEMENT:
cli_msxmlmsg("msxml_parse_element: ELEMENT %s [%d]: %s\n", node_name, node_type, node_value);
/* storing the element name for verification/collection */
element_name = node_name;
if (!element_name) {
cli_dbgmsg("msxml_parse_element: element tag node nameless\n");
#if HAVE_JSON
if (track_json(mxctx)) {
int tmp = cli_json_parse_error(root, "MSXML_NAMELESS_ELEMENT");
if (tmp != CL_SUCCESS)
return tmp;
}
#endif
return CL_EPARSE; /* no name, nameless */
}
/* determine if the element is interesting */
keyinfo = msxml_check_key(mxctx->ictx, element_name, xmlStrlen(element_name));
cli_msxmlmsg("key: %s\n", keyinfo->key);
cli_msxmlmsg("name: %s\n", keyinfo->name);
cli_msxmlmsg("type: 0x%x\n", keyinfo->type);
/* element and contents are ignored */
if (keyinfo->type & MSXML_IGNORE_ELEM) {
cli_msxmlmsg("msxml_parse_element: IGNORING ELEMENT %s\n", keyinfo->name);
state = xmlTextReaderNext(reader);
check_state(state);
return CL_SUCCESS;
}
#if HAVE_JSON
if (track_json(mxctx) && (keyinfo->type & MSXML_JSON_TRACK)) {
if (keyinfo->type & MSXML_JSON_ROOT)
thisjobj = cli_jsonobj(root, keyinfo->name);
else if (keyinfo->type & MSXML_JSON_WRKPTR)
thisjobj = cli_jsonobj(parent, keyinfo->name);
if (!thisjobj) {
return CL_EMEM;
}
cli_msxmlmsg("msxml_parse_element: generated json object [%s]\n", keyinfo->name);
/* count this element */
if (thisjobj && (keyinfo->type & MSXML_JSON_COUNT)) {
json_object *counter = NULL;
if (!json_object_object_get_ex(thisjobj, "Count", &counter)) { /* object not found */
cli_jsonint(thisjobj, "Count", 1);
} else {
int value = json_object_get_int(counter);
cli_jsonint(thisjobj, "Count", value + 1);
}
cli_msxmlmsg("msxml_parse_element: retrieved json object [Count]\n");
}
/* check if multiple entries are allowed */
if (thisjobj && (keyinfo->type & MSXML_JSON_MULTI)) {
/* replace this object with an array entry object */
json_object *multi = cli_jsonarray(thisjobj, "Multi");
if (!multi) {
return CL_EMEM;
}
cli_msxmlmsg("msxml_parse_element: generated or retrieved json multi array\n");
thisjobj = cli_jsonobj(multi, NULL);
if (!thisjobj)
return CL_EMEM;
cli_msxmlmsg("msxml_parse_element: generated json multi entry object\n");
}
/* handle attributes */
if (thisjobj && (keyinfo->type & MSXML_JSON_ATTRIB)) {
state = xmlTextReaderHasAttributes(reader);
if (state == 1) {
json_object *attributes;
const xmlChar *name, *value;
attributes = cli_jsonobj(thisjobj, "Attributes");
if (!attributes) {
return CL_EPARSE;
}
cli_msxmlmsg("msxml_parse_element: retrieved json object [Attributes]\n");
while (xmlTextReaderMoveToNextAttribute(reader) == 1) {
name = xmlTextReaderConstLocalName(reader);
value = xmlTextReaderConstValue(reader);
cli_msxmlmsg("\t%s: %s\n", name, value);
cli_jsonstr(attributes, (char *)name, (const char *)value);
}
} else if (state == -1)
return CL_EPARSE;
}
}
#endif
/* populate attributes for scanning callback - BROKEN, probably from the fact the reader is pointed to the attribute from previously parsing attributes */
if ((keyinfo->type & MSXML_SCAN_CB) && mxctx->scan_cb) {
state = xmlTextReaderHasAttributes(reader);
if (state == 0) {
state = xmlTextReaderMoveToFirstAttribute(reader);
if (state == 1) {
/* read first attribute (current head) */
attribs[num_attribs].key = (const char *)xmlTextReaderConstLocalName(reader);
attribs[num_attribs].value = (const char *)xmlTextReaderConstValue(reader);
num_attribs++;
} else if (state == -1) {
return CL_EPARSE;
}
}
/* start reading attributes or read remainder of attributes */
if (state == 1) {
cli_msxmlmsg("msxml_parse_element: adding attributes to scanning context\n");
while ((num_attribs < MAX_ATTRIBS) && (xmlTextReaderMoveToNextAttribute(reader) == 1)) {
attribs[num_attribs].key = (const char *)xmlTextReaderConstLocalName(reader);
attribs[num_attribs].value = (const char *)xmlTextReaderConstValue(reader);
num_attribs++;
}
} else if (state == -1) {
return CL_EPARSE;
}
}
/* check self-containment */
state = xmlTextReaderMoveToElement(reader);
if (state == -1)
return CL_EPARSE;
state = xmlTextReaderIsEmptyElement(reader);
if (state == 1) {
cli_msxmlmsg("msxml_parse_element: SELF-CLOSING\n");
state = xmlTextReaderNext(reader);
check_state(state);
return CL_SUCCESS;
} else if (state == -1)
return CL_EPARSE;
/* advance to first content node */
state = xmlTextReaderRead(reader);
check_state(state);
while (!endtag) {
#if HAVE_JSON
if (track_json(mxctx) && (cli_json_timeout_cycle_check(ctx, &(mxctx->ictx->toval)) != CL_SUCCESS))
return CL_ETIMEOUT;
#endif
node_type = xmlTextReaderNodeType(reader);
if (node_type == -1)
return CL_EPARSE;
switch (node_type) {
case XML_READER_TYPE_ELEMENT:
ret = msxml_parse_element(mxctx, reader, rlvl + 1, thisjobj ? thisjobj : parent);
if (ret != CL_SUCCESS || (!SCAN_ALLMATCHES && ret == CL_VIRUS)) {
return ret;
} else if (SCAN_ALLMATCHES && ret == CL_VIRUS) {
virus = 1;
}
break;
case XML_READER_TYPE_TEXT:
node_value = xmlTextReaderConstValue(reader);
cli_msxmlmsg("TEXT: %s\n", node_value);
#if HAVE_JSON
if (thisjobj && (keyinfo->type & MSXML_JSON_VALUE)) {
ret = msxml_parse_value(thisjobj, "Value", node_value);
if (ret != CL_SUCCESS)
return ret;
cli_msxmlmsg("msxml_parse_element: added json value [%s: %s]\n", keyinfo->name, (const char *)node_value);
}
#endif
/* callback-based scanning mechanism for embedded objects (used by HWPML) */
if ((keyinfo->type & MSXML_SCAN_CB) && mxctx->scan_cb) {
char name[1024];
char *tempfile = name;
int of;
size_t vlen = strlen((const char *)node_value);
cli_msxmlmsg("BINARY CALLBACK DATA!\n");
if ((ret = cli_gentempfd(ctx->engine->tmpdir, &tempfile, &of)) != CL_SUCCESS) {
cli_warnmsg("msxml_parse_element: failed to create temporary file %s\n", tempfile);
return ret;
}
if (cli_writen(of, (char *)node_value, vlen) != vlen) {
close(of);
if (!(ctx->engine->keeptmp))
cli_unlink(tempfile);
free(tempfile);
return CL_EWRITE;
}
cli_dbgmsg("msxml_parse_element: extracted binary data to %s\n", tempfile);
ret = mxctx->scan_cb(of, tempfile, ctx, num_attribs, attribs, mxctx->scan_data);
close(of);
if (!(ctx->engine->keeptmp))
cli_unlink(tempfile);
free(tempfile);
if (ret != CL_SUCCESS && (ret != CL_VIRUS || (!SCAN_ALLMATCHES && ret == CL_VIRUS))) {
return ret;
} else if (SCAN_ALLMATCHES && ret == CL_VIRUS) {
virus = 1;
}
}
/* scanning protocol for embedded objects encoded in base64 (used by MSXML) */
if (keyinfo->type & MSXML_SCAN_B64) {
char name[1024];
char *decoded, *tempfile = name;
size_t decodedlen;
int of;
cli_msxmlmsg("BINARY DATA!\n");
decoded = (char *)cl_base64_decode((char *)node_value, strlen((const char *)node_value), NULL, &decodedlen, 0);
if (!decoded) {
cli_warnmsg("msxml_parse_element: failed to decode base64-encoded binary data\n");
state = xmlTextReaderRead(reader);
check_state(state);
break;
}
if ((ret = cli_gentempfd(ctx->engine->tmpdir, &tempfile, &of)) != CL_SUCCESS) {
cli_warnmsg("msxml_parse_element: failed to create temporary file %s\n", tempfile);
free(decoded);
return ret;
}
if (cli_writen(of, decoded, decodedlen) != decodedlen) {
free(decoded);
close(of);
if (!(ctx->engine->keeptmp))
cli_unlink(tempfile);
free(tempfile);
return CL_EWRITE;
}
free(decoded);
cli_dbgmsg("msxml_parse_element: extracted binary data to %s\n", tempfile);
ret = cli_magic_scandesc(of, tempfile, ctx);
close(of);
if (!(ctx->engine->keeptmp))
cli_unlink(tempfile);
free(tempfile);
if (ret != CL_SUCCESS && (ret != CL_VIRUS || (!SCAN_ALLMATCHES && ret == CL_VIRUS))) {
return ret;
} else if (SCAN_ALLMATCHES && ret == CL_VIRUS) {
virus = 1;
}
}
/* advance to next node */
state = xmlTextReaderRead(reader);
check_state(state);
break;
case XML_READER_TYPE_COMMENT:
node_value = xmlTextReaderConstValue(reader);
cli_msxmlmsg("COMMENT: %s\n", node_value);
/* callback-based scanning mechanism for comments (used by MHTML) */
if ((keyinfo->type & MSXML_COMMENT_CB) && mxctx->comment_cb) {
#if HAVE_JSON
ret = mxctx->comment_cb((const char *)node_value, ctx, thisjobj, mxctx->comment_data);
#else
ret = mxctx->comment_cb((const char *)node_value, ctx, NULL, mxctx->comment_data);
#endif
if (ret != CL_SUCCESS && (ret != CL_VIRUS || (!SCAN_ALLMATCHES && ret == CL_VIRUS))) {
return ret;
} else if (SCAN_ALLMATCHES && ret == CL_VIRUS) {
virus = 1;
}
}
/* advance to next node */
state = xmlTextReaderRead(reader);
check_state(state);
break;
case XML_READER_TYPE_SIGNIFICANT_WHITESPACE:
/* advance to next node */
state = xmlTextReaderRead(reader);
check_state(state);
break;
case XML_READER_TYPE_END_ELEMENT:
cli_msxmlmsg("in msxml_parse_element @ layer %d closed\n", rlvl);
node_name = xmlTextReaderConstLocalName(reader);
if (!node_name) {
cli_dbgmsg("msxml_parse_element: element end tag node nameless\n");
return CL_EPARSE; /* no name, nameless */
}
if (xmlStrcmp(element_name, node_name)) {
cli_dbgmsg("msxml_parse_element: element tag does not match end tag %s != %s\n", element_name, node_name);
return CL_EFORMAT;
}
/* advance to next element tag */
state = xmlTextReaderRead(reader);
check_state(state);
endtag = 1;
break;
default:
node_name = xmlTextReaderConstLocalName(reader);
node_value = xmlTextReaderConstValue(reader);
cli_dbgmsg("msxml_parse_element: unhandled xml secondary node %s [%d]: %s\n", node_name, node_type, node_value);
state = xmlTextReaderRead(reader);
check_state(state);
}
}
break;
case XML_READER_TYPE_PROCESSING_INSTRUCTION:
cli_msxmlmsg("msxml_parse_element: PROCESSING INSTRUCTION %s [%d]: %s\n", node_name, node_type, node_value);
break;
case XML_READER_TYPE_SIGNIFICANT_WHITESPACE:
cli_msxmlmsg("msxml_parse_element: SIGNIFICANT WHITESPACE %s [%d]: %s\n", node_name, node_type, node_value);
break;
case XML_READER_TYPE_END_ELEMENT:
cli_msxmlmsg("msxml_parse_element: END ELEMENT %s [%d]: %s\n", node_name, node_type, node_value);
return (virus ? CL_VIRUS : CL_SUCCESS);
default:
cli_dbgmsg("msxml_parse_element: unhandled xml primary node %s [%d]: %s\n", node_name, node_type, node_value);
}
return (virus ? CL_VIRUS : CL_SUCCESS);
}
/* reader initialization and closing handled by caller */
int cli_msxml_parse_document(cli_ctx *ctx, xmlTextReaderPtr reader, const struct key_entry *keys, const size_t num_keys, uint32_t flags, struct msxml_ctx *mxctx)
{
struct msxml_ctx reserve;
struct msxml_ictx ictx;
int state, virus = 0, ret = CL_SUCCESS;
if (!ctx)
return CL_ENULLARG;
if (!mxctx) {
memset(&reserve, 0, sizeof(reserve));
mxctx = &reserve;
}
ictx.ctx = ctx;
ictx.flags = flags;
ictx.keys = keys;
ictx.num_keys = num_keys;
#if HAVE_JSON
if (flags & MSXML_FLAG_JSON) {
ictx.root = ctx->wrkproperty;
/* JSON Sanity Check */
if (!ictx.root)
ictx.flags &= ~MSXML_FLAG_JSON;
ictx.toval = 0;
}
#else
ictx.flags &= ~MSXML_FLAG_JSON;
#endif
mxctx->ictx = &ictx;
/* Error Handler (setting handler on tree walker causes segfault) */
if (!(flags & MSXML_FLAG_WALK))
//xmlTextReaderSetErrorHandler(reader, NULL, NULL); /* xml default handler */
xmlTextReaderSetErrorHandler(reader, msxml_error_handler, NULL);
/* Main Processing Loop */
while ((state = xmlTextReaderRead(reader)) == 1) {
#if HAVE_JSON
if ((ictx.flags & MSXML_FLAG_JSON) && (cli_json_timeout_cycle_check(ictx.ctx, &(ictx.toval)) != CL_SUCCESS))
return CL_ETIMEOUT;
ret = msxml_parse_element(mxctx, reader, 0, ictx.root);
#else
ret = msxml_parse_element(mxctx, reader, 0, NULL);
#endif
if (ret == CL_SUCCESS)
;
else if (SCAN_ALLMATCHES && ret == CL_VIRUS) {
/* non-allmatch simply propagates it down to return through ret */
virus = 1;
} else if (ret == CL_VIRUS || ret == CL_ETIMEOUT || ret == CL_BREAK) {
cli_dbgmsg("cli_msxml_parse_document: encountered halt event in parsing xml document\n");
break;
} else {
cli_warnmsg("cli_msxml_parse_document: encountered issue in parsing xml document\n");
break;
}
}
if (state == -1)
ret = CL_EPARSE;
#if HAVE_JSON
/* Parse General Error Handler */
if (ictx.flags & MSXML_FLAG_JSON) {
int tmp = CL_SUCCESS;
switch (ret) {
case CL_SUCCESS:
case CL_BREAK: /* OK */
break;
case CL_VIRUS:
tmp = cli_json_parse_error(ictx.root, "MSXML_INTR_VIRUS");
break;
case CL_ETIMEOUT:
tmp = cli_json_parse_error(ictx.root, "MSXML_INTR_TIMEOUT");
break;
case CL_EPARSE:
tmp = cli_json_parse_error(ictx.root, "MSXML_ERROR_XMLPARSER");
break;
case CL_EMEM:
tmp = cli_json_parse_error(ictx.root, "MSXML_ERROR_OUTOFMEM");
break;
case CL_EFORMAT:
tmp = cli_json_parse_error(ictx.root, "MSXML_ERROR_MALFORMED");
break;
default:
tmp = cli_json_parse_error(ictx.root, "MSXML_ERROR_OTHER");
break;
}
if (tmp)
return tmp;
}
#endif
/* non-critical return suppression */
if (ret == CL_ETIMEOUT || ret == CL_BREAK)
ret = CL_SUCCESS;
/* important but non-critical suppression */
if (ret == CL_EPARSE) {
cli_dbgmsg("cli_msxml_parse_document: suppressing parsing error to continue scan\n");
ret = CL_SUCCESS;
}
return (virus ? CL_VIRUS : ret);
}
#endif /* HAVE_LIBXML2 */