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nielsdosnielsdos
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Implement SVG image handler
This implements an SVG handler using the libxml reader API. This does not parse the entire document but instead uses a pull parser to locate the root element, check whether it's an svg root, do some extra sanity checks on the attribute, and fill in the php_gfxinfo structure.
1 parent 8db883c commit 0962c32

27 files changed

+565
-65
lines changed

‎ext/libxml/config.w32

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -11,7 +11,7 @@ if (PHP_LIBXML == "yes") {
1111
if (GREP_HEADER("libxml/xmlversion.h", "#define\\s+LIBXML_VERSION\\s+(\\d+)", PHP_PHP_BUILD + "\\include\\libxml2") &&
1212
+RegExp.$1 >= 20904) {
1313

14-
EXTENSION("libxml", "libxml.c mime_sniff.c", false /* never shared */, "/DZEND_ENABLE_STATIC_TSRMLS_CACHE=1");
14+
EXTENSION("libxml", "libxml.c mime_sniff.c image_svg.c", false /* never shared */, "/DZEND_ENABLE_STATIC_TSRMLS_CACHE=1");
1515
AC_DEFINE("HAVE_LIBXML", 1, "Define to 1 if the PHP extension 'libxml' is available.");
1616
ADD_FLAG("CFLAGS_LIBXML", "/D LIBXML_STATIC /D LIBXML_STATIC_FOR_DLL /D HAVE_WIN32_THREADS ");
1717
if (!PHP_LIBXML_SHARED) {

‎ext/libxml/config0.m4

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -12,7 +12,7 @@ if test "$PHP_LIBXML" != "no"; then
1212
AC_DEFINE([HAVE_LIBXML], [1],
1313
[Define to 1 if the PHP extension 'libxml' is available.])
1414
PHP_NEW_EXTENSION([libxml],
15-
[libxml.c mime_sniff.c],
15+
[libxml.c mime_sniff.c image_svg.c],
1616
[$ext_shared],,
1717
[-DZEND_ENABLE_STATIC_TSRMLS_CACHE=1])
1818
PHP_INSTALL_HEADERS([ext/libxml], [php_libxml.h])

‎ext/libxml/image_svg.c

Lines changed: 178 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,178 @@
1+
/*
2+
+----------------------------------------------------------------------+
3+
| Copyright (c) The PHP Group |
4+
+----------------------------------------------------------------------+
5+
| This source file is subject to version 3.01 of the PHP license, |
6+
| that is bundled with this package in the file LICENSE, and is |
7+
| available through the world-wide-web at the following url: |
8+
| https://www.php.net/license/3_01.txt |
9+
| If you did not receive a copy of the PHP license and are unable to |
10+
| obtain it through the world-wide-web, please send a note to |
11+
| [email protected] so we can mail you a copy immediately. |
12+
+----------------------------------------------------------------------+
13+
| Authors: Niels Dossche <[email protected]> |
14+
+----------------------------------------------------------------------+
15+
*/
16+
17+
#ifdef HAVE_CONFIG_H
18+
#include "config.h"
19+
#endif
20+
21+
#include "php.h"
22+
#include "image_svg.h"
23+
#include "php_libxml.h"
24+
25+
#include "ext/standard/php_image.h"
26+
27+
#include <libxml/xmlreader.h>
28+
29+
#ifdef HAVE_LIBXML
30+
31+
static int svg_image_type_id;
32+
33+
static int php_libxml_svg_stream_read(void *context, char *buffer, int len)
34+
{
35+
return php_stream_read(context, buffer, len);
36+
}
37+
38+
/* Sanity check that the input only contains characters valid for a dimension (numbers with units, e.g. 5cm).
39+
* This also protects the user against injecting XSS.
40+
* Only accept [0-9]+[a-zA-Z]* */
41+
static bool php_libxml_parse_dimension(const xmlChar *input, const xmlChar **unit_position)
42+
{
43+
if (!(*input >= '0' && *input <= '9')) {
44+
return false;
45+
}
46+
47+
input++;
48+
49+
while (*input) {
50+
if (!(*input >= '0' && *input <= '9')) {
51+
if ((*input >= 'a' && *input <= 'z') || (*input >= 'A' && *input <= 'Z')) {
52+
break;
53+
}
54+
return false;
55+
}
56+
input++;
57+
}
58+
59+
*unit_position = input;
60+
61+
while (*input) {
62+
if (!((*input >= 'a' && *input <= 'z') || (*input >= 'A' && *input <= 'Z'))) {
63+
return false;
64+
}
65+
input++;
66+
}
67+
68+
return true;
69+
}
70+
71+
zend_result php_libxml_svg_image_handle(php_stream *stream, struct php_gfxinfo **result)
72+
{
73+
if (php_stream_rewind(stream)) {
74+
return FAILURE;
75+
}
76+
77+
/* Early check before doing more expensive work */
78+
if (php_stream_getc(stream) != '<') {
79+
return FAILURE;
80+
}
81+
82+
if (php_stream_rewind(stream)) {
83+
return FAILURE;
84+
}
85+
86+
PHP_LIBXML_SANITIZE_GLOBALS(reader_for_stream);
87+
xmlTextReaderPtr reader = xmlReaderForIO(
88+
php_libxml_svg_stream_read,
89+
NULL,
90+
stream,
91+
NULL,
92+
NULL,
93+
XML_PARSE_NOWARNING | XML_PARSE_NOERROR | XML_PARSE_NONET
94+
);
95+
PHP_LIBXML_RESTORE_GLOBALS(reader_for_stream);
96+
97+
if (!reader) {
98+
return FAILURE;
99+
}
100+
101+
bool is_svg = false;
102+
while (xmlTextReaderRead(reader) == 1) {
103+
if (xmlTextReaderNodeType(reader) == XML_READER_TYPE_ELEMENT) {
104+
/* Root must be an svg element */
105+
const xmlChar *name = xmlTextReaderConstLocalName(reader);
106+
if (!name || strcasecmp((const char *) name, "svg") != 0) {
107+
break;
108+
}
109+
110+
xmlChar *width = xmlTextReaderGetAttribute(reader, BAD_CAST "width");
111+
xmlChar *height = xmlTextReaderGetAttribute(reader, BAD_CAST "height");
112+
const xmlChar *width_unit_position, *height_unit_position;
113+
if (!width || !height
114+
|| !php_libxml_parse_dimension(width, &width_unit_position)
115+
|| !php_libxml_parse_dimension(height, &height_unit_position)) {
116+
xmlFree(width);
117+
xmlFree(height);
118+
break;
119+
}
120+
121+
is_svg = true;
122+
if (result) {
123+
*result = ecalloc(1, sizeof(**result));
124+
(*result)->width = ZEND_STRTOL((const char *) width, NULL, 10);
125+
(*result)->height = ZEND_STRTOL((const char *) height, NULL, 10);
126+
if (*width_unit_position) {
127+
(*result)->width_unit = zend_string_init((const char*) width_unit_position,
128+
xmlStrlen(width_unit_position), false);
129+
}
130+
if (*height_unit_position) {
131+
(*result)->height_unit = zend_string_init((const char*) height_unit_position,
132+
xmlStrlen(height_unit_position), false);
133+
}
134+
}
135+
136+
xmlFree(width);
137+
xmlFree(height);
138+
break;
139+
}
140+
}
141+
142+
xmlFreeTextReader(reader);
143+
144+
return is_svg ? SUCCESS : FAILURE;
145+
}
146+
147+
zend_result php_libxml_svg_image_identify(php_stream *stream)
148+
{
149+
return php_libxml_svg_image_handle(stream, NULL);
150+
}
151+
152+
struct php_gfxinfo *php_libxml_svg_image_get_info(php_stream *stream)
153+
{
154+
struct php_gfxinfo *result = NULL;
155+
zend_result status = php_libxml_svg_image_handle(stream, &result);
156+
ZEND_ASSERT((status == SUCCESS) == (result != NULL));
157+
return result;
158+
}
159+
160+
static const struct php_image_handler svg_image_handler = {
161+
"image/svg+xml",
162+
".svg",
163+
PHP_IMAGE_CONST_NAME("SVG"),
164+
php_libxml_svg_image_identify,
165+
php_libxml_svg_image_get_info,
166+
};
167+
168+
void php_libxml_register_image_svg_handler(void)
169+
{
170+
svg_image_type_id = php_image_register_handler(&svg_image_handler);
171+
}
172+
173+
zend_result php_libxml_unregister_image_svg_handler(void)
174+
{
175+
return php_image_unregister_handler(svg_image_type_id);
176+
}
177+
178+
#endif

‎ext/libxml/image_svg.h

Lines changed: 25 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,25 @@
1+
/*
2+
+----------------------------------------------------------------------+
3+
| Copyright (c) The PHP Group |
4+
+----------------------------------------------------------------------+
5+
| This source file is subject to version 3.01 of the PHP license, |
6+
| that is bundled with this package in the file LICENSE, and is |
7+
| available through the world-wide-web at the following url: |
8+
| https://www.php.net/license/3_01.txt |
9+
| If you did not receive a copy of the PHP license and are unable to |
10+
| obtain it through the world-wide-web, please send a note to |
11+
| [email protected] so we can mail you a copy immediately. |
12+
+----------------------------------------------------------------------+
13+
| Authors: Niels Dossche <[email protected]> |
14+
+----------------------------------------------------------------------+
15+
*/
16+
17+
#ifndef LIBXML_IMAGE_SVG
18+
#define LIBXML_IMAGE_SVG
19+
20+
#include "zend.h"
21+
22+
void php_libxml_register_image_svg_handler(void);
23+
zend_result php_libxml_unregister_image_svg_handler(void);
24+
25+
#endif

‎ext/libxml/libxml.c

Lines changed: 11 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -43,6 +43,7 @@
4343
#endif
4444

4545
#include "php_libxml.h"
46+
#include "image_svg.h"
4647

4748
#define PHP_LIBXML_LOADED_VERSION ((char *)xmlParserVersion)
4849

@@ -84,8 +85,14 @@ static zend_long php_libxml_default_dump_doc_to_file(const char *filename, xmlDo
8485

8586
/* }}} */
8687

88+
static const zend_module_dep libxml_deps[] = {
89+
ZEND_MOD_REQUIRED("standard")
90+
ZEND_MOD_END
91+
};
92+
8793
zend_module_entry libxml_module_entry = {
88-
STANDARD_MODULE_HEADER,
94+
STANDARD_MODULE_HEADER_EX, NULL,
95+
libxml_deps,
8996
"libxml", /* extension name */
9097
ext_functions, /* extension function list */
9198
PHP_MINIT(libxml), /* extension-wide startup function */
@@ -969,6 +976,8 @@ static PHP_MINIT_FUNCTION(libxml)
969976
xmlOutputBufferCreateFilenameDefault(php_libxml_output_buffer_create_filename);
970977
}
971978

979+
php_libxml_register_image_svg_handler();
980+
972981
return SUCCESS;
973982
}
974983

@@ -1010,7 +1019,7 @@ static PHP_MSHUTDOWN_FUNCTION(libxml)
10101019
}
10111020
php_libxml_shutdown();
10121021

1013-
return SUCCESS;
1022+
return php_libxml_unregister_image_svg_handler();
10141023
}
10151024

10161025
static zend_result php_libxml_post_deactivate(void)

‎ext/libxml/tests/image/getimagesize.phpt

Lines changed: 98 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,98 @@
1+
--TEST--
2+
getimagesize() with svg input
3+
--EXTENSIONS--
4+
libxml
5+
--FILE--
6+
<?php
7+
8+
$inputs = [
9+
"<?xml version=\"1.0\"?>",
10+
"svg width=\"1\" height=\"1\"",
11+
<<<XML
12+
<?xml version="1.0" standalone="yes"?>
13+
<!-- foo <svg width="1" height="1"/> -->
14+
<x:svg width='4cm' height="8cm" xmlns:x="http://www.w3.org/2000/svg">
15+
XML,
16+
"<SVG width='1' height=\"1\"/>",
17+
"<SVG width='1px' height=\"1\"/>",
18+
"<SVG width='1' height=\"1mm\"/>",
19+
"<SVG width='1' height=\"cm\"/>",
20+
"<SVG width='' height=\"\"/>",
21+
"<SVG width=\"é\" height='1'/>",
22+
"<foo width='1' height=\"1\"/>",
23+
"<foo foo='1' height=\"1\"/>",
24+
];
25+
26+
foreach ($inputs as $input) {
27+
var_dump(getimagesizefromstring($input));
28+
}
29+
30+
?>
31+
--EXPECTF--
32+
bool(false)
33+
bool(false)
34+
array(6) {
35+
[0]=>
36+
int(4)
37+
[1]=>
38+
int(8)
39+
[2]=>
40+
int(%d)
41+
["mime"]=>
42+
string(13) "image/svg+xml"
43+
["width_unit"]=>
44+
string(2) "cm"
45+
["height_unit"]=>
46+
string(2) "cm"
47+
}
48+
array(7) {
49+
[0]=>
50+
int(1)
51+
[1]=>
52+
int(1)
53+
[2]=>
54+
int(%d)
55+
[3]=>
56+
string(20) "width="1" height="1""
57+
["mime"]=>
58+
string(13) "image/svg+xml"
59+
["width_unit"]=>
60+
string(2) "px"
61+
["height_unit"]=>
62+
string(2) "px"
63+
}
64+
array(7) {
65+
[0]=>
66+
int(1)
67+
[1]=>
68+
int(1)
69+
[2]=>
70+
int(%d)
71+
[3]=>
72+
string(20) "width="1" height="1""
73+
["mime"]=>
74+
string(13) "image/svg+xml"
75+
["width_unit"]=>
76+
string(2) "px"
77+
["height_unit"]=>
78+
string(2) "px"
79+
}
80+
array(6) {
81+
[0]=>
82+
int(1)
83+
[1]=>
84+
int(1)
85+
[2]=>
86+
int(%d)
87+
["mime"]=>
88+
string(13) "image/svg+xml"
89+
["width_unit"]=>
90+
string(2) "px"
91+
["height_unit"]=>
92+
string(2) "mm"
93+
}
94+
bool(false)
95+
bool(false)
96+
bool(false)
97+
bool(false)
98+
bool(false)

‎ext/libxml/tests/image/imagetype_svg.phpt

Lines changed: 16 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,16 @@
1+
--TEST--
2+
imagetype API with svg extension
3+
--EXTENSIONS--
4+
libxml
5+
--FILE--
6+
<?php
7+
8+
var_dump(IMAGETYPE_COUNT > IMAGETYPE_SVG);
9+
var_dump(image_type_to_extension(IMAGETYPE_SVG));
10+
var_dump(image_type_to_mime_type(IMAGETYPE_SVG));
11+
12+
?>
13+
--EXPECT--
14+
bool(true)
15+
string(4) ".svg"
16+
string(13) "image/svg+xml"

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