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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 3e0d3b3 commit c972e53

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7 files changed

+258
-4
lines changed

7 files changed

+258
-4
lines changed

‎ext/libxml/config.w32

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -12,7 +12,7 @@ if (PHP_LIBXML == "yes") {
1212
if (GREP_HEADER("libxml/xmlversion.h", "#define\\s+LIBXML_VERSION\\s+(\\d+)", PHP_PHP_BUILD + "\\include\\libxml2") &&
1313
+RegExp.$1 >= 20904) {
1414

15-
EXTENSION("libxml", "libxml.c mime_sniff.c", false /* never shared */, "/DZEND_ENABLE_STATIC_TSRMLS_CACHE=1");
15+
EXTENSION("libxml", "libxml.c mime_sniff.c image_svg.c", false /* never shared */, "/DZEND_ENABLE_STATIC_TSRMLS_CACHE=1");
1616
AC_DEFINE("HAVE_LIBXML", 1, "Define to 1 if the PHP extension 'libxml' is available.");
1717
ADD_FLAG("CFLAGS_LIBXML", "/D LIBXML_STATIC /D LIBXML_STATIC_FOR_DLL /D HAVE_WIN32_THREADS ");
1818
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: 148 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,148 @@
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 [0-9a-zA-Z] */
41+
static bool php_libxml_valid_dimension(const xmlChar *input)
42+
{
43+
while (*input) {
44+
if (!((*input >= '0' && *input <= '9') || (*input >= 'a' && *input <= 'z') || (*input >= 'A' && *input <= 'Z'))) {
45+
return false;
46+
}
47+
input++;
48+
}
49+
return true;
50+
}
51+
52+
zend_result php_libxml_svg_image_handle(php_stream *stream, struct php_gfxinfo **result)
53+
{
54+
if (php_stream_rewind(stream)) {
55+
return FAILURE;
56+
}
57+
58+
/* Early check before doing more expensive work */
59+
if (php_stream_getc(stream) != '<') {
60+
return FAILURE;
61+
}
62+
63+
if (php_stream_rewind(stream)) {
64+
return FAILURE;
65+
}
66+
67+
PHP_LIBXML_SANITIZE_GLOBALS(reader_for_stream);
68+
xmlTextReaderPtr reader = xmlReaderForIO(
69+
php_libxml_svg_stream_read,
70+
NULL,
71+
stream,
72+
NULL,
73+
NULL,
74+
XML_PARSE_NOWARNING | XML_PARSE_NOERROR | XML_PARSE_NONET
75+
);
76+
PHP_LIBXML_RESTORE_GLOBALS(reader_for_stream);
77+
78+
if (!reader) {
79+
return FAILURE;
80+
}
81+
82+
bool is_svg = false;
83+
while (xmlTextReaderRead(reader) == 1) {
84+
if (xmlTextReaderNodeType(reader) == XML_READER_TYPE_ELEMENT) {
85+
/* Root must be an svg element */
86+
const xmlChar *name = xmlTextReaderConstLocalName(reader);
87+
if (!name || strcasecmp((const char *) name, "svg") != 0) {
88+
break;
89+
}
90+
91+
xmlChar *width = xmlTextReaderGetAttribute(reader, BAD_CAST "width");
92+
xmlChar *height = xmlTextReaderGetAttribute(reader, BAD_CAST "height");
93+
if (!width || !height || !php_libxml_valid_dimension(width) || !php_libxml_valid_dimension(height)) {
94+
xmlFree(width);
95+
xmlFree(height);
96+
break;
97+
}
98+
99+
is_svg = true;
100+
if (result) {
101+
*result = ecalloc(1, sizeof(**result));
102+
(*result)->width_str = zend_string_init((const char *) width, xmlStrlen(width), false);
103+
(*result)->height_str = zend_string_init((const char *) height, xmlStrlen(height), false);
104+
}
105+
106+
xmlFree(width);
107+
xmlFree(height);
108+
break;
109+
}
110+
}
111+
112+
xmlFreeTextReader(reader);
113+
114+
return is_svg ? SUCCESS : FAILURE;
115+
}
116+
117+
zend_result php_libxml_svg_image_identify(php_stream *stream)
118+
{
119+
return php_libxml_svg_image_handle(stream, NULL);
120+
}
121+
122+
struct php_gfxinfo *php_libxml_svg_image_get_info(php_stream *stream)
123+
{
124+
struct php_gfxinfo *result = NULL;
125+
zend_result status = php_libxml_svg_image_handle(stream, &result);
126+
ZEND_ASSERT((status == SUCCESS) == (result != NULL));
127+
return result;
128+
}
129+
130+
static const struct php_image_handler svg_image_handler = {
131+
"image/svg+xml",
132+
".svg",
133+
PHP_IMAGE_CONST_NAME("SVG"),
134+
php_libxml_svg_image_identify,
135+
php_libxml_svg_image_get_info,
136+
};
137+
138+
void php_libxml_register_image_svg_handler(void)
139+
{
140+
svg_image_type_id = php_image_register_handler(&svg_image_handler);
141+
}
142+
143+
zend_result php_libxml_unregister_image_svg_handler(void)
144+
{
145+
return php_image_unregister_handler(svg_image_type_id);
146+
}
147+
148+
#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

@@ -88,8 +89,14 @@ static zend_long php_libxml_default_dump_doc_to_file(const char *filename, xmlDo
8889

8990
/* }}} */
9091

92+
static const zend_module_dep libxml_deps[] = {
93+
ZEND_MOD_REQUIRED("standard")
94+
ZEND_MOD_END
95+
};
96+
9197
zend_module_entry libxml_module_entry = {
92-
STANDARD_MODULE_HEADER,
98+
STANDARD_MODULE_HEADER_EX, NULL,
99+
libxml_deps,
93100
"libxml", /* extension name */
94101
ext_functions, /* extension function list */
95102
PHP_MINIT(libxml), /* extension-wide startup function */
@@ -967,6 +974,8 @@ static PHP_MINIT_FUNCTION(libxml)
967974
xmlOutputBufferCreateFilenameDefault(php_libxml_output_buffer_create_filename);
968975
}
969976

977+
php_libxml_register_image_svg_handler();
978+
970979
return SUCCESS;
971980
}
972981

@@ -1008,7 +1017,7 @@ static PHP_MSHUTDOWN_FUNCTION(libxml)
10081017
}
10091018
php_libxml_shutdown();
10101019

1011-
return SUCCESS;
1020+
return php_libxml_unregister_image_svg_handler();
10121021
}
10131022

10141023
static zend_result php_libxml_post_deactivate(void)

‎ext/libxml/tests/image/getimagesize.phpt

Lines changed: 56 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,56 @@
1+
--TEST--
2+
getimagesize() with svg input
3+
--EXTENSIONS--
4+
libxml
5+
--FILE--
6+
<?php
7+
8+
$inputs = [
9+
"<?xml version=\"1.0\"?>",
10+
"svg width=\"1\" height=\"1\"",
11+
<<<XML
12+
<?xml version="1.0" standalone="yes"?>
13+
<!-- foo <svg width="1" height="1"/> -->
14+
<x:svg width='4cm' height="8cm" xmlns:x="http://www.w3.org/2000/svg">
15+
XML,
16+
"<SVG width='1' height=\"1\"/>",
17+
"<SVG width=\"é\" height='1'/>",
18+
"<foo width='1' height=\"1\"/>",
19+
"<foo foo='1' height=\"1\"/>",
20+
];
21+
22+
foreach ($inputs as $input) {
23+
var_dump(getimagesizefromstring($input));
24+
}
25+
26+
?>
27+
--EXPECTF--
28+
bool(false)
29+
bool(false)
30+
array(5) {
31+
[0]=>
32+
string(3) "4cm"
33+
[1]=>
34+
string(3) "8cm"
35+
[2]=>
36+
int(%d)
37+
[3]=>
38+
string(24) "width="4cm" height="8cm""
39+
["mime"]=>
40+
string(13) "image/svg+xml"
41+
}
42+
array(5) {
43+
[0]=>
44+
string(1) "1"
45+
[1]=>
46+
string(1) "1"
47+
[2]=>
48+
int(%d)
49+
[3]=>
50+
string(20) "width="1" height="1""
51+
["mime"]=>
52+
string(13) "image/svg+xml"
53+
}
54+
bool(false)
55+
bool(false)
56+
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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