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airweenairween
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Merge pull request owasp-modsecurity#334 from airween/fix_response_body
fix: response body (based on owasp-modsecurity#326)
2 parents ef64996 + ae30826 commit fb678c5

10 files changed

+176
-96
lines changed

‎src/ngx_http_modsecurity_body_filter.c‎

Lines changed: 78 additions & 38 deletions
Original file line numberDiff line numberDiff line change
@@ -33,12 +33,14 @@ ngx_http_modsecurity_body_filter_init(void)
3333

3434
return NGX_OK;
3535
}
36-
3736
ngx_int_t
3837
ngx_http_modsecurity_body_filter(ngx_http_request_t *r, ngx_chain_t *in)
3938
{
40-
ngx_chain_t *chain = in;
4139
ngx_http_modsecurity_ctx_t *ctx = NULL;
40+
ngx_chain_t *chain = in;
41+
ngx_int_t ret;
42+
ngx_pool_t *old_pool;
43+
ngx_int_t is_request_processed = 0;
4244
#if defined(MODSECURITY_SANITY_CHECKS) && (MODSECURITY_SANITY_CHECKS)
4345
ngx_http_modsecurity_conf_t *mcf;
4446
ngx_list_part_t *part = &r->headers_out.headers.part;
@@ -47,14 +49,18 @@ ngx_http_modsecurity_body_filter(ngx_http_request_t *r, ngx_chain_t *in)
4749
#endif
4850

4951
if (in == NULL) {
52+
ngx_log_debug0(NGX_LOG_DEBUG_HTTP, r->connection->log, 0, "MDS input chain is null");
53+
5054
return ngx_http_next_body_filter(r, in);
5155
}
5256

53-
ctx = ngx_http_get_module_ctx(r, ngx_http_modsecurity_module);
54-
57+
/* get context for request */
58+
ctx = ngx_http_modsecurity_get_module_ctx(r);
5559
dd("body filter, recovering ctx: %p", ctx);
5660

57-
if (ctx == NULL) {
61+
if (ctx == NULL || r->filter_finalize || ctx->response_body_filtered) {
62+
if (ctx && ctx->response_body_filtered)
63+
r->filter_finalize = 1;
5864
return ngx_http_next_body_filter(r, in);
5965
}
6066

@@ -140,47 +146,81 @@ ngx_http_modsecurity_body_filter(ngx_http_request_t *r, ngx_chain_t *in)
140146
}
141147
#endif
142148

143-
int is_request_processed = 0;
144-
for (; chain != NULL; chain = chain->next)
145-
{
146-
u_char *data = chain->buf->pos;
147-
int ret;
149+
for (chain = in; chain != NULL; chain = chain->next) {
148150

149-
msc_append_response_body(ctx->modsec_transaction, data, chain->buf->last - data);
150-
ret = ngx_http_modsecurity_process_intervention(ctx->modsec_transaction, r, 0);
151+
ngx_buf_t *copy_buf;
152+
ngx_chain_t* copy_chain;
153+
is_request_processed = chain->buf->last_buf;
154+
u_char *data = chain->buf->pos;
155+
msc_append_response_body(ctx->modsec_transaction, data,
156+
chain->buf->last - data);
157+
ret = ngx_http_modsecurity_process_intervention(ctx->modsec_transaction,
158+
r, 0);
151159
if (ret > 0) {
152160
return ngx_http_filter_finalize_request(r,
153161
&ngx_http_modsecurity_module, ret);
154162
}
155-
156-
/* XXX: chain->buf->last_buf || chain->buf->last_in_chain */
157-
is_request_processed = chain->buf->last_buf;
158-
159-
if (is_request_processed) {
160-
ngx_pool_t *old_pool;
161-
162-
old_pool = ngx_http_modsecurity_pcre_malloc_init(r->pool);
163-
msc_process_response_body(ctx->modsec_transaction);
164-
ngx_http_modsecurity_pcre_malloc_done(old_pool);
165-
166-
/* XXX: I don't get how body from modsec being transferred to nginx's buffer. If so - after adjusting of nginx's
167-
XXX: body we can proceed to adjust body size (content-length). see xslt_body_filter() for example */
168-
ret = ngx_http_modsecurity_process_intervention(ctx->modsec_transaction, r, 0);
169-
if (ret > 0) {
170-
return ret;
163+
if (!chain->buf->last_buf){
164+
copy_chain = ngx_alloc_chain_link(r->pool);
165+
if (copy_chain == NULL) {
166+
return NGX_ERROR;
171167
}
172-
else if (ret < 0) {
173-
return ngx_http_filter_finalize_request(r,
174-
&ngx_http_modsecurity_module, NGX_HTTP_INTERNAL_SERVER_ERROR);
175-
168+
copy_buf = ngx_calloc_buf(r->pool);
169+
if (copy_buf == NULL) {
170+
return NGX_ERROR;
176171
}
172+
copy_buf->pos = chain->buf->pos ;
173+
copy_buf->end = chain->buf->end;
174+
copy_buf->last = chain->buf->last;
175+
copy_buf->temporary = (chain->buf->temporary == 1) ? 1 : 0;
176+
copy_buf->memory = (chain->buf->memory == 1) ? 1 : 0;
177+
copy_chain->buf = copy_buf;
178+
copy_chain->buf->last_buf = chain->buf->last_buf;
179+
copy_chain->next = NULL;
180+
chain->buf->pos = chain->buf->last;
177181
}
178-
}
179-
if (!is_request_processed)
180-
{
181-
dd("buffer was not fully loaded! ctx: %p", ctx);
182+
else
183+
copy_chain = chain;
184+
if (ctx->temp_chain == NULL) {
185+
ctx->temp_chain = copy_chain;
186+
} else {
187+
if (ctx->current_chain == NULL) {
188+
ctx->temp_chain->next = copy_chain;
189+
ctx->temp_chain->buf->last_buf = 0;
190+
} else {
191+
ctx->current_chain->next = copy_chain;
192+
ctx->current_chain->buf->last_buf = 0;
193+
}
194+
ctx->current_chain = copy_chain;
195+
}
196+
182197
}
183198

184-
/* XXX: xflt_filter() -- return NGX_OK here */
185-
return ngx_http_next_body_filter(r, in);
199+
if (is_request_processed) {
200+
old_pool = ngx_http_modsecurity_pcre_malloc_init(r->pool);
201+
msc_process_response_body(ctx->modsec_transaction);
202+
ngx_http_modsecurity_pcre_malloc_done(old_pool);
203+
ret = ngx_http_modsecurity_process_intervention(ctx->modsec_transaction, r, 0);
204+
if (ret > 0) {
205+
if (ret < NGX_HTTP_BAD_REQUEST && ctx->header_pt != NULL){
206+
ctx->header_pt(r);
207+
}
208+
else {
209+
ctx->response_body_filtered = 1;
210+
return ngx_http_filter_finalize_request(r,
211+
&ngx_http_modsecurity_module
212+
, ret);
213+
}
214+
} else if (ret < 0) {
215+
ctx->response_body_filtered = 1;
216+
return ngx_http_filter_finalize_request(r,
217+
&ngx_http_modsecurity_module, NGX_HTTP_INTERNAL_SERVER_ERROR);
218+
}
219+
ctx->response_body_filtered = 1;
220+
if (ctx->header_pt != NULL)
221+
ctx->header_pt(r);
222+
return ngx_http_next_body_filter(r, ctx->temp_chain);
223+
} else {
224+
return NGX_AGAIN;
225+
}
186226
}

‎src/ngx_http_modsecurity_common.h‎

Lines changed: 6 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -76,7 +76,6 @@ typedef struct {
7676
ngx_str_t value;
7777
} ngx_http_modsecurity_header_t;
7878

79-
8079
typedef struct {
8180
ngx_http_request_t *r;
8281
Transaction *modsec_transaction;
@@ -97,8 +96,13 @@ typedef struct {
9796
unsigned waiting_more_body:1;
9897
unsigned body_requested:1;
9998
unsigned processed:1;
99+
ngx_http_output_header_filter_pt header_pt;
100+
ngx_chain_t* temp_chain;
101+
ngx_chain_t* current_chain;
102+
unsigned response_body_filtered:1;
100103
unsigned logged:1;
101104
unsigned intervention_triggered:1;
105+
unsigned request_body_processed:1;
102106
} ngx_http_modsecurity_ctx_t;
103107

104108

@@ -139,6 +143,7 @@ extern ngx_module_t ngx_http_modsecurity_module;
139143
/* ngx_http_modsecurity_module.c */
140144
int ngx_http_modsecurity_process_intervention (Transaction *transaction, ngx_http_request_t *r, ngx_int_t early_log);
141145
ngx_http_modsecurity_ctx_t *ngx_http_modsecurity_create_ctx(ngx_http_request_t *r);
146+
ngx_http_modsecurity_ctx_t *ngx_http_modsecurity_get_module_ctx(ngx_http_request_t *r);
142147
char *ngx_str_to_char(ngx_str_t a, ngx_pool_t *p);
143148
#if (NGX_PCRE2)
144149
#define ngx_http_modsecurity_pcre_malloc_init(x) NULL

‎src/ngx_http_modsecurity_header_filter.c‎

Lines changed: 23 additions & 16 deletions
Original file line numberDiff line numberDiff line change
@@ -109,7 +109,7 @@ ngx_http_modsecurity_store_ctx_header(ngx_http_request_t *r, ngx_str_t *name, ng
109109
ngx_http_modsecurity_conf_t *mcf;
110110
ngx_http_modsecurity_header_t *hdr;
111111

112-
ctx = ngx_http_get_module_ctx(r, ngx_http_modsecurity_module);
112+
ctx = ngx_http_modsecurity_get_module_ctx(r);
113113
if (ctx == NULL || ctx->sanity_headers_out == NULL) {
114114
return NGX_ERROR;
115115
}
@@ -152,7 +152,7 @@ ngx_http_modsecurity_resolv_header_server(ngx_http_request_t *r, ngx_str_t name,
152152
ngx_str_t value;
153153

154154
clcf = ngx_http_get_module_loc_conf(r, ngx_http_core_module);
155-
ctx = ngx_http_get_module_ctx(r, ngx_http_modsecurity_module);
155+
ctx = ngx_http_modsecurity_get_module_ctx(r);
156156

157157
if (r->headers_out.server == NULL) {
158158
if (clcf->server_tokens) {
@@ -186,7 +186,7 @@ ngx_http_modsecurity_resolv_header_date(ngx_http_request_t *r, ngx_str_t name, o
186186
ngx_http_modsecurity_ctx_t *ctx = NULL;
187187
ngx_str_t date;
188188

189-
ctx = ngx_http_get_module_ctx(r, ngx_http_modsecurity_module);
189+
ctx = ngx_http_modsecurity_get_module_ctx(r);
190190

191191
if (r->headers_out.date == NULL) {
192192
date.data = ngx_cached_http_time.data;
@@ -216,7 +216,7 @@ ngx_http_modsecurity_resolv_header_content_length(ngx_http_request_t *r, ngx_str
216216
ngx_str_t value;
217217
char buf[NGX_INT64_LEN+2];
218218

219-
ctx = ngx_http_get_module_ctx(r, ngx_http_modsecurity_module);
219+
ctx = ngx_http_modsecurity_get_module_ctx(r);
220220

221221
if (r->headers_out.content_length_n > 0)
222222
{
@@ -243,7 +243,7 @@ ngx_http_modsecurity_resolv_header_content_type(ngx_http_request_t *r, ngx_str_t
243243
{
244244
ngx_http_modsecurity_ctx_t *ctx = NULL;
245245

246-
ctx = ngx_http_get_module_ctx(r, ngx_http_modsecurity_module);
246+
ctx = ngx_http_modsecurity_get_module_ctx(r);
247247

248248
if (r->headers_out.content_type.len > 0)
249249
{
@@ -270,7 +270,7 @@ ngx_http_modsecurity_resolv_header_last_modified(ngx_http_request_t *r, ngx_str_
270270
u_char buf[1024], *p;
271271
ngx_str_t value;
272272

273-
ctx = ngx_http_get_module_ctx(r, ngx_http_modsecurity_module);
273+
ctx = ngx_http_modsecurity_get_module_ctx(r);
274274

275275
if (r->headers_out.last_modified_time == -1) {
276276
return 1;
@@ -302,7 +302,7 @@ ngx_http_modsecurity_resolv_header_connection(ngx_http_request_t *r, ngx_str_t n
302302
ngx_str_t value;
303303

304304
clcf = ngx_http_get_module_loc_conf(r, ngx_http_core_module);
305-
ctx = ngx_http_get_module_ctx(r, ngx_http_modsecurity_module);
305+
ctx = ngx_http_modsecurity_get_module_ctx(r);
306306

307307
if (r->headers_out.status == NGX_HTTP_SWITCHING_PROTOCOLS) {
308308
connection = "upgrade";
@@ -353,7 +353,7 @@ ngx_http_modsecurity_resolv_header_transfer_encoding(ngx_http_request_t *r, ngx_
353353
if (r->chunked) {
354354
ngx_str_t value = ngx_string("chunked");
355355

356-
ctx = ngx_http_get_module_ctx(r, ngx_http_modsecurity_module);
356+
ctx = ngx_http_modsecurity_get_module_ctx(r);
357357

358358
#if defined(MODSECURITY_SANITY_CHECKS) && (MODSECURITY_SANITY_CHECKS)
359359
ngx_http_modsecurity_store_ctx_header(r, &name, &value);
@@ -380,7 +380,7 @@ ngx_http_modsecurity_resolv_header_vary(ngx_http_request_t *r, ngx_str_t name, o
380380
if (r->gzip_vary && clcf->gzip_vary) {
381381
ngx_str_t value = ngx_string("Accept-Encoding");
382382

383-
ctx = ngx_http_get_module_ctx(r, ngx_http_modsecurity_module);
383+
ctx = ngx_http_modsecurity_get_module_ctx(r);
384384

385385
#if defined(MODSECURITY_SANITY_CHECKS) && (MODSECURITY_SANITY_CHECKS)
386386
ngx_http_modsecurity_store_ctx_header(r, &name, &value);
@@ -422,7 +422,7 @@ ngx_http_modsecurity_header_filter(ngx_http_request_t *r)
422422

423423
/* XXX: if NOT_MODIFIED, do we need to process it at all? see xslt_header_filter() */
424424

425-
ctx = ngx_http_get_module_ctx(r, ngx_http_modsecurity_module);
425+
ctx = ngx_http_modsecurity_get_module_ctx(r);
426426

427427
dd("header filter, recovering ctx: %p", ctx);
428428

@@ -551,10 +551,17 @@ ngx_http_modsecurity_header_filter(ngx_http_request_t *r)
551551
*
552552
*/
553553

554-
/*
555-
* The line below is commented to make the spdy test to work
556-
*/
557-
//r->headers_out.content_length_n = -1;
558-
559-
return ngx_http_next_header_filter(r);
554+
/*
555+
* The line below is commented to make the spdy test to work
556+
*/
557+
//r->headers_out.content_length_n = -1;
558+
559+
if (ctx->response_body_filtered){
560+
return ngx_http_next_header_filter(r);
561+
}
562+
else {
563+
ctx->header_pt = ngx_http_next_header_filter;
564+
r->headers_out.content_length_n = -1;
565+
return NGX_AGAIN;
566+
}
560567
}

‎src/ngx_http_modsecurity_log.c‎

Lines changed: 3 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -60,13 +60,13 @@ ngx_http_modsecurity_log_handler(ngx_http_request_t *r)
6060
return NGX_OK;
6161
}
6262
*/
63-
ctx = ngx_http_get_module_ctx(r, ngx_http_modsecurity_module);
63+
ctx = ngx_http_modsecurity_get_module_ctx(r);
6464

6565
dd("recovering ctx: %p", ctx);
6666

6767
if (ctx == NULL) {
68-
dd("something really bad happened here. returning NGX_ERROR");
69-
return NGX_ERROR;
68+
dd("ModSecurity not enabled or error occurred");
69+
return NGX_OK;
7070
}
7171

7272
if (ctx->logged) {

‎src/ngx_http_modsecurity_module.c‎

Lines changed: 23 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -149,7 +149,7 @@ ngx_http_modsecurity_process_intervention (Transaction *transaction, ngx_http_re
149149

150150
dd("processing intervention");
151151

152-
ctx = ngx_http_get_module_ctx(r, ngx_http_modsecurity_module);
152+
ctx = ngx_http_modsecurity_get_module_ctx(r);
153153
if (ctx == NULL)
154154
{
155155
return NGX_HTTP_INTERNAL_SERVER_ERROR;
@@ -292,6 +292,7 @@ ngx_http_modsecurity_create_ctx(ngx_http_request_t *r)
292292

293293
dd("transaction created");
294294

295+
ctx->response_body_filtered = 0;
295296
ngx_http_set_ctx(r, ctx, ngx_http_modsecurity_module);
296297

297298
cln = ngx_pool_cleanup_add(r->pool, sizeof(ngx_http_modsecurity_ctx_t));
@@ -313,6 +314,27 @@ ngx_http_modsecurity_create_ctx(ngx_http_request_t *r)
313314
return ctx;
314315
}
315316

317+
ngx_inline ngx_http_modsecurity_ctx_t *
318+
ngx_http_modsecurity_get_module_ctx(ngx_http_request_t *r)
319+
{
320+
ngx_http_modsecurity_ctx_t *ctx;
321+
ctx = ngx_http_get_module_ctx(r, ngx_http_modsecurity_module);
322+
if (ctx == NULL) {
323+
/*
324+
* refer <nginx>/src/http/modules/ngx_http_realip_module.c
325+
* if module context was reset, the original address
326+
* can still be found in the cleanup handler
327+
*/
328+
ngx_pool_cleanup_t *cln;
329+
for (cln = r->pool->cleanup; cln; cln = cln->next) {
330+
if (cln->handler == ngx_http_modsecurity_cleanup) {
331+
ctx = cln->data;
332+
break;
333+
}
334+
}
335+
}
336+
return ctx;
337+
}
316338

317339
char *
318340
ngx_conf_set_rules(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)

‎src/ngx_http_modsecurity_pre_access.c‎

Lines changed: 8 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -27,7 +27,7 @@ ngx_http_modsecurity_request_read(ngx_http_request_t *r)
2727
{
2828
ngx_http_modsecurity_ctx_t *ctx;
2929

30-
ctx = ngx_http_get_module_ctx(r, ngx_http_modsecurity_module);
30+
ctx = ngx_http_modsecurity_get_module_ctx(r);
3131

3232
#if defined(nginx_version) && nginx_version >= 8011
3333
r->main->count--;
@@ -70,7 +70,7 @@ ngx_http_modsecurity_pre_access_handler(ngx_http_request_t *r)
7070
}
7171
*/
7272

73-
ctx = ngx_http_get_module_ctx(r, ngx_http_modsecurity_module);
73+
ctx = ngx_http_modsecurity_get_module_ctx(r);
7474

7575
dd("recovering ctx: %p", ctx);
7676

@@ -80,6 +80,11 @@ ngx_http_modsecurity_pre_access_handler(ngx_http_request_t *r)
8080
return NGX_HTTP_INTERNAL_SERVER_ERROR;
8181
}
8282

83+
if (ctx->request_body_processed) {
84+
// should we use r->internal or r->filter_finalize?
85+
return NGX_DECLINED;
86+
}
87+
8388
if (ctx->intervention_triggered) {
8489
return NGX_DECLINED;
8590
}
@@ -212,6 +217,7 @@ ngx_http_modsecurity_pre_access_handler(ngx_http_request_t *r)
212217

213218
old_pool = ngx_http_modsecurity_pcre_malloc_init(r->pool);
214219
msc_process_request_body(ctx->modsec_transaction);
220+
ctx->request_body_processed = 1;
215221
ngx_http_modsecurity_pcre_malloc_done(old_pool);
216222

217223
ret = ngx_http_modsecurity_process_intervention(ctx->modsec_transaction, r, 0);

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