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dotdot: introducing dot file path cleanup

Browse Source 
RFC3986 details how a path part passed in as part of a URI should be
"cleaned" from dot sequences before getting used. The described
algorithm is now implemented in lib/dotdot.c with the accompanied test
case in test 1395.

Bug: http://curl.haxx.se/bug/view.cgi?id=1200
Reported-by: Alex Vinnik
This commit is contained in:
Daniel Stenberg 2013-06-15 23:47:02 +02:00
parent ec248b590d
commit 7877619f85
9 changed files with 402 additions and 14 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
lib/Makefile.inc
View File

@ -25,7 +25,7 @@ CSOURCES = file.c timeval.c base64.c hostip.c progress.c formdata.c \
http_proxy.c non-ascii.c asyn-ares.c asyn-thread.c curl_gssapi.c \
curl_ntlm.c curl_ntlm_wb.c curl_ntlm_core.c curl_ntlm_msgs.c \
curl_sasl.c curl_schannel.c curl_multibyte.c curl_darwinssl.c \
hostcheck.c bundles.c conncache.c pipeline.c
hostcheck.c bundles.c conncache.c pipeline.c dotdot.c
HHEADERS = arpa_telnet.h netrc.h file.h timeval.h qssl.h hostip.h \
progress.h formdata.h cookie.h http.h sendf.h ftp.h url.h dict.h \
@ -44,4 +44,4 @@ HHEADERS = arpa_telnet.h netrc.h file.h timeval.h qssl.h hostip.h \
asyn.h curl_ntlm.h curl_gssapi.h curl_ntlm_wb.h curl_ntlm_core.h \
curl_ntlm_msgs.h curl_sasl.h curl_schannel.h curl_multibyte.h \
curl_darwinssl.h hostcheck.h bundles.h conncache.h curl_setup_once.h \
multihandle.h setup-vms.h pipeline.h
multihandle.h setup-vms.h pipeline.h dotdot.h

170
lib/dotdot.c Normal file
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@ -0,0 +1,170 @@
/***************************************************************************
* _ _ ____ _
* Project ___| | | | _ \| |
* / __| | | | |_) | |
* | (__| |_| | _ <| |___
* \___|\___/|_| \_\_____|
*
* Copyright (C) 1998 - 2013, Daniel Stenberg, <daniel@haxx.se>, et al.
*
* This software is licensed as described in the file COPYING, which
* you should have received as part of this distribution. The terms
* are also available at http://curl.haxx.se/docs/copyright.html.
*
* You may opt to use, copy, modify, merge, publish, distribute and/or sell
* copies of the Software, and permit persons to whom the Software is
* furnished to do so, under the terms of the COPYING file.
*
* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
* KIND, either express or implied.
*
***************************************************************************/
#include "curl_setup.h"
#include "dotdot.h"
#include "curl_memory.h"
/* The last #include file should be: */
#include "memdebug.h"
/*
* "Remove Dot Segments"
* http://tools.ietf.org/html/rfc3986#section-5.2.4
*/
/*
* Curl_dedotdotify()
*
* This function gets a zero-terminated path with dot and dotdot sequences
* passed in and strips them off according to the rules in RFC 3986 section
* 5.2.5.
*
* The function handles a query part ('?' + stuff) appended but it expects
* that fragments ('#' + stuff) have already been cut off.
*
* RETURNS
*
* an allocated dedotdotified output string
*/
char *Curl_dedotdotify(char *input)
{
size_t inlen = strlen(input);
char *clone;
size_t clen = inlen; /* the length of the cloned input */
char *out = malloc(inlen+1);
char *outp;
char *orgclone;
char *queryp;
if(!out)
return NULL; /* out of memory */
/* get a cloned copy of the input */
clone = strdup(input);
if(!clone) {
free(out);
return NULL;
}
orgclone = clone;
outp = out;
/*
* To handle query-parts properly, we must find it and remove it during the
* dotdot-operation and then append it again at the end to the output
* string.
*/
queryp = strchr(clone, '?');
if(queryp)
*queryp = 0;
do {
/* A. If the input buffer begins with a prefix of "../" or "./", then
remove that prefix from the input buffer; otherwise, */
if(!strncmp("./", clone, 2)) {
clone+=2;
clen-=2;
}
else if(!strncmp("../", clone, 3)) {
clone+=3;
clen-=3;
}
/* B. if the input buffer begins with a prefix of "/./" or "/.", where
"." is a complete path segment, then replace that prefix with "/" in
the input buffer; otherwise, */
else if(!strncmp("/./", clone, 3)) {
clone+=2;
clen-=2;
}
else if(!strcmp("/.", clone)) {
clone[1]='/';
clone++;
clen-=1;
}
/* C. if the input buffer begins with a prefix of "/../" or "/..", where
".." is a complete path segment, then replace that prefix with "/" in
the input buffer and remove the last segment and its preceding "/" (if
any) from the output buffer; otherwise, */
else if(!strncmp("/../", clone, 4)) {
clone+=3;
clen-=3;
/* remove the last segment from the output buffer */
while(outp > out) {
outp--;
if(*outp == '/')
break;
}
*outp = 0; /* zero-terminate where it stops */
}
else if(!strcmp("/..", clone)) {
clone[2]='/';
clone+=2;
clen-=2;
/* remove the last segment from the output buffer */
while(outp > out) {
outp--;
if(*outp == '/')
break;
}
*outp = 0; /* zero-terminate where it stops */
}
/* D. if the input buffer consists only of "." or "..", then remove
that from the input buffer; otherwise, */
else if(!strcmp(".", clone) || !strcmp("..", clone)) {
*clone=0;
}
else {
/* E. move the first path segment in the input buffer to the end of
the output buffer, including the initial "/" character (if any) and
any subsequent characters up to, but not including, the next "/"
character or the end of the input buffer. */
do {
*outp++ = *clone++;
clen--;
} while(*clone && (*clone != '/'));
*outp=0;
}
} while(*clone);
if(queryp) {
size_t qlen;
/* There was a query part, append that to the output. The 'clone' string
may now have been altered so we copy from the original input string
from the correct index. */
size_t oindex = queryp - orgclone;
qlen = strlen(&input[oindex]);
memcpy(outp, &input[oindex], qlen+1); /* include the ending zero byte */
}
free(orgclone);
return out;
}

25
lib/dotdot.h Normal file
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@ -0,0 +1,25 @@
#ifndef HEADER_CURL_DOTDOT_H
#define HEADER_CURL_DOTDOT_H
/***************************************************************************
* _ _ ____ _
* Project ___| | | | _ \| |
* / __| | | | |_) | |
* | (__| |_| | _ <| |___
* \___|\___/|_| \_\_____|
*
* Copyright (C) 1998 - 2013, Daniel Stenberg, <daniel@haxx.se>, et al.
*
* This software is licensed as described in the file COPYING, which
* you should have received as part of this distribution. The terms
* are also available at http://curl.haxx.se/docs/copyright.html.
*
* You may opt to use, copy, modify, merge, publish, distribute and/or sell
* copies of the Software, and permit persons to whom the Software is
* furnished to do so, under the terms of the COPYING file.
*
* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
* KIND, either express or implied.
*
***************************************************************************/
char *Curl_dedotdotify(char *input);
#endif

36
lib/url.c
View File

@ -124,6 +124,7 @@ int curl_win32_idn_to_ascii(const char *in, char **out);
#include "conncache.h"
#include "multihandle.h"
#include "pipeline.h"
#include "dotdot.h"
#define _MPRINTF_REPLACE /* use our functions only */
#include <curl/mprintf.h>
@ -3674,7 +3675,7 @@ static CURLcode parseurlandfillconn(struct SessionHandle *data,
char protobuf[16];
const char *protop;
CURLcode result;
bool fix_slash = FALSE;
bool rebuild_url = FALSE;
*prot_missing = FALSE;
@ -3825,14 +3826,14 @@ static CURLcode parseurlandfillconn(struct SessionHandle *data,
memcpy(path+1, query, hostlen);
path[0]='/'; /* prepend the missing slash */
fix_slash = TRUE;
rebuild_url = TRUE;
*query=0; /* now cut off the hostname at the ? */
}
else if(!path[0]) {
/* if there's no path set, use a single slash */
strcpy(path, "/");
fix_slash = TRUE;
rebuild_url = TRUE;
}
/* If the URL is malformatted (missing a '/' after hostname before path) we
@ -3845,17 +3846,30 @@ static CURLcode parseurlandfillconn(struct SessionHandle *data,
is bigger than the path. Use +1 to move the zero byte too. */
memmove(&path[1], path, strlen(path)+1);
path[0] = '/';
fix_slash = TRUE;
rebuild_url = TRUE;
}
else {
/* sanitise paths and remove ../ and ./ sequences according to RFC3986 */
char *newp = Curl_dedotdotify(path);
if(strcmp(newp, path)) {
rebuild_url = TRUE;
free(data->state.pathbuffer);
data->state.pathbuffer = newp;
data->state.path = newp;
path = newp;
}
else
free(newp);
}
/*
* "fix_slash" means that the URL was malformatted so we need to generate an
* updated version with the new slash inserted at the right place! We need
* the corrected URL when communicating over HTTP proxy and we don't know at
* this point if we're using a proxy or not.
* "rebuild_url" means that one or more URL components have been modified so
* we need to generate an updated full version. We need the corrected URL
* when communicating over HTTP proxy and we don't know at this point if
* we're using a proxy or not.
*/
if(fix_slash) {
if(rebuild_url) {
char *reurl;
size_t plen = strlen(path); /* new path, should be 1 byte longer than
@ -3878,6 +3892,8 @@ static CURLcode parseurlandfillconn(struct SessionHandle *data,
data->change.url_alloc = FALSE;
}
infof(data, "Rebuilt URL to: %s\n", reurl);
data->change.url = reurl;
data->change.url_alloc = TRUE; /* free this later */
}

2
tests/data/Makefile.am
View File

@ -93,7 +93,7 @@ test1200 test1201 test1202 test1203 test1204 test1205 test1206 test1207 \
test1208 test1209 test1210 test1211 test1212 test1213 test1214 test1215 \
test1216 test1217 test1218 test1219 \
test1220 test1221 test1222 test1223 test1224 test1225 test1226 test1227 \
test1228 test1229 test1230 \
test1228 test1229 test1230 test1231 \
\
test1300 test1301 test1302 test1303 test1304 test1305 test1306 test1307 \
test1308 test1309 test1310 test1311 test1312 test1313 test1314 test1315 \

61
tests/data/test1231 Normal file
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@ -0,0 +1,61 @@
<testcase>
<info>
<keywords>
HTTP
HTTP GET
dotdot removal
</keywords>
</info>
#
# Server-side
<reply name="1">
<data>
HTTP/1.1 200 OK
Content-Length: 6
Connection: close
-foo-
</data>
<data1>
HTTP/1.1 200 OK
Content-Length: 7
Connection: close
-cool-
</data1>
</reply>
#
# Client-side
<client>
<server>
http
</server>
<name>
HTTP URL with dotdot removal from path
</name>
<command>
http://%HOSTIP:%HTTPPORT/../../hej/but/who/../1231?stupid=me/../1231#soo/../1231 http://%HOSTIP:%HTTPPORT/../../hej/but/who/../12310001#/../12310001
</command>
</client>
#
# Verify data after the test has been "shot"
<verify>
<strip>
^User-Agent:.*
</strip>
<protocol>
GET /hej/but/1231?stupid=me/../1231 HTTP/1.1
Host: %HOSTIP:%HTTPPORT
Accept: */*
GET /hej/but/12310001 HTTP/1.1
Host: %HOSTIP:%HTTPPORT
Accept: */*
</protocol>
</verify>
</testcase>

26
tests/data/test1395 Normal file
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@ -0,0 +1,26 @@
<testcase>
<info>
<keywords>
unittest
</keywords>
</info>
#
# Client-side
<client>
<server>
none
</server>
<features>
unittest
</features>
<name>
Curl_dedotdotify
</name>
<tool>
unit1395
</tool>
</client>
</testcase>

5
tests/unit/Makefile.inc
View File

@ -6,7 +6,7 @@ UNITFILES = curlcheck.h \
# These are all unit test programs
UNITPROGS = unit1300 unit1301 unit1302 unit1303 unit1304 unit1305 unit1307 \
unit1308 unit1309 unit1330 unit1394 unit1396
unit1308 unit1309 unit1330 unit1394 unit1395 unit1396
unit1300_SOURCES = unit1300.c $(UNITFILES)
unit1300_CPPFLAGS = $(AM_CPPFLAGS)
@ -44,5 +44,8 @@ unit1394_LDADD = @LIBMETALINK_LIBS@ $(top_builddir)/lib/libcurl.la @LIBCURL_LIBS
unit1394_LDFLAGS = @LIBMETALINK_LDFLAGS@ $(top_builddir)/src/libcurltool.la
unit1394_LIBS =
unit1395_SOURCES = unit1395.c $(UNITFILES)
unit1395_CPPFLAGS = $(AM_CPPFLAGS)
unit1396_SOURCES = unit1396.c $(UNITFILES)
unit1396_CPPFLAGS = $(AM_CPPFLAGS)

87
tests/unit/unit1395.c Normal file
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@ -0,0 +1,87 @@
/***************************************************************************
* _ _ ____ _
* Project ___| | | | _ \| |
* / __| | | | |_) | |
* | (__| |_| | _ <| |___
* \___|\___/|_| \_\_____|
*
* Copyright (C) 1998 - 2013, Daniel Stenberg, <daniel@haxx.se>, et al.
*
* This software is licensed as described in the file COPYING, which
* you should have received as part of this distribution. The terms
* are also available at http://curl.haxx.se/docs/copyright.html.
*
* You may opt to use, copy, modify, merge, publish, distribute and/or sell
* copies of the Software, and permit persons to whom the Software is
* furnished to do so, under the terms of the COPYING file.
*
* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
* KIND, either express or implied.
*
***************************************************************************/
#include "curlcheck.h"
#include "dotdot.h"
#include "memdebug.h"
static CURLcode unit_setup(void)
{
return CURLE_OK;
}
static void unit_stop(void)
{
}
struct dotdot {
const char *input;
const char *output;
};
UNITTEST_START
unsigned int i;
int fails=0;
struct dotdot pairs[] = {
{ "/a/b/c/./../../g", "/a/g" },
{ "mid/content=5/../6", "mid/6" },
{ "/hello/../moo", "/moo" },
{ "/1/../1", "/1" },
{ "/1/./1", "/1/1" },
{ "/1/..", "/" },
{ "/1/.", "/1/" },
{ "/1/./..", "/" },
{ "/1/./../2", "/2" },
{ "/hello/1/./../2", "/hello/2" },
{ "test/this", "test/this" },
{ "test/this/../now", "test/now" },
{ "/1../moo../foo", "/1../moo../foo"},
{ "/../../moo", "/moo"},
{ "/../../moo?andnot/../yay", "/moo?andnot/../yay"},
{ "/123?foo=/./&bar=/../", "/123?foo=/./&bar=/../"},
{ "/../moo/..?what", "/?what" },
};
for(i=0; i < sizeof(pairs)/sizeof(pairs[0]); i++) {
char *out = Curl_dedotdotify((char *)pairs[i].input);
if(strcmp(out, pairs[i].output)) {
fprintf(stderr, "Test %d: '%s' gave '%s' instead of '%s'\n",
i, pairs[i].input, out, pairs[i].output);
fail("Test case output mismatched");
fails++;
}
else
fprintf(stderr, "Test %d: OK\n", i);
free(out);
}
return fails;
UNITTEST_STOP