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Implement a (bounded) buffer of request body data to provide a limited

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but safe fix for the mod_ssl renegotiation-vs-requests-with-bodies
bug:

* modules/ssl/ssl_private.h (ssl_io_buffer_fill): Add prototype.

* modules/ssl/ssl_engine_io.c (ssl_io_buffer_fill,
ssl_io_filter_buffer): New functions.

* modules/ssl/ssl_engine_kernel.c (ssl_hook_Access): If a
renegotiation is needed, and the request has a non-zero
content-length, or a t-e header (and 100-continue was not requested),
call ssl_io_buffer_fill to set aside the request body data if
possible, then proceed with the negotiation.

PR: 12355


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@290965 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Joe Orton
2005-09-22 15:38:14 +00:00
parent 62b4528015
commit 23a3c20db2
3 changed files with 216 additions and 65 deletions
Download Patch File Download Diff File Expand all files Collapse all files

185
modules/ssl/ssl_engine_io.c
View File

@@ -882,6 +882,7 @@ static apr_status_t ssl_io_filter_error(ap_filter_t *f,
}
static const char ssl_io_filter[] = "SSL/TLS Filter";
static const char ssl_io_buffer[] = "SSL/TLS Buffer";
/*
* Close the SSL part of the socket connection
@@ -1446,6 +1447,187 @@ static apr_status_t ssl_io_filter_output(ap_filter_t *f,
return status;
}
/* 128K maximum buffer size by default. */
#ifndef SSL_MAX_IO_BUFFER
#define SSL_MAX_IO_BUFFER (128 * 1024)
#endif
struct modssl_buffer_ctx {
apr_bucket_brigade *bb;
apr_pool_t *pool;
};
int ssl_io_buffer_fill(request_rec *r)
{
conn_rec *c = r->connection;
struct modssl_buffer_ctx *ctx;
apr_bucket_brigade *tempb;
apr_off_t total = 0; /* total length buffered */
int eos = 0; /* non-zero once EOS is seen */
/* Create the context which will be passed to the input filter;
* containing a setaside pool and a brigade which constrain the
* lifetime of the buffered data. */
ctx = apr_palloc(r->pool, sizeof *ctx);
apr_pool_create(&ctx->pool, r->pool);
ctx->bb = apr_brigade_create(ctx->pool, c->bucket_alloc);
/* ... and a temporary brigade. */
tempb = apr_brigade_create(r->pool, c->bucket_alloc);
ap_log_cerror(APLOG_MARK, APLOG_DEBUG, 0, c, "filling buffer");
do {
apr_status_t rv;
apr_bucket *e, *next;
/* The request body is read from the protocol-level input
* filters; the buffering filter will reinject it from that
* level, allowing content/resource filters to run later, if
* necessary. */
rv = ap_get_brigade(r->proto_input_filters, tempb, AP_MODE_READBYTES,
APR_BLOCK_READ, 8192);
if (rv) {
ap_log_rerror(APLOG_MARK, APLOG_ERR, rv, r,
"could not read request body for SSL buffer");
return HTTP_INTERNAL_SERVER_ERROR;
}
/* Iterate through the returned brigade: setaside each bucket
* into the context's pool and move it into the brigade. */
for (e = APR_BRIGADE_FIRST(tempb);
e != APR_BRIGADE_SENTINEL(tempb) && !eos; e = next) {
const char *data;
apr_size_t len;
next = APR_BUCKET_NEXT(e);
if (APR_BUCKET_IS_EOS(e)) {
eos = 1;
} else if (!APR_BUCKET_IS_METADATA(e)) {
rv = apr_bucket_read(e, &data, &len, APR_BLOCK_READ);
if (rv != APR_SUCCESS) {
ap_log_rerror(APLOG_MARK, APLOG_ERR, rv, r,
"could not read bucket for SSL buffer");
return HTTP_INTERNAL_SERVER_ERROR;
}
total += len;
}
rv = apr_bucket_setaside(e, ctx->pool);
if (rv != APR_SUCCESS) {
ap_log_rerror(APLOG_MARK, APLOG_ERR, rv, r,
"could not setaside bucket for SSL buffer");
return HTTP_INTERNAL_SERVER_ERROR;
}
APR_BUCKET_REMOVE(e);
APR_BRIGADE_INSERT_TAIL(ctx->bb, e);
}
ap_log_cerror(APLOG_MARK, APLOG_DEBUG, 0, c,
"total of %" APR_OFF_T_FMT " bytes in buffer, eos=%d",
total, eos);
/* Fail if this exceeds the maximum buffer size. */
if (total > SSL_MAX_IO_BUFFER) {
ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
"request body exceeds maximum size for SSL buffer");
return HTTP_REQUEST_ENTITY_TOO_LARGE;
}
} while (!eos);
apr_brigade_destroy(tempb);
/* Insert the filter which will supply the buffered data. */
ap_add_input_filter(ssl_io_buffer, ctx, r, c);
return 0;
}
/* This input filter supplies the buffered request body to the caller
* from the brigade stored in f->ctx. */
static apr_status_t ssl_io_filter_buffer(ap_filter_t *f,
apr_bucket_brigade *bb,
ap_input_mode_t mode,
apr_read_type_e block,
apr_off_t bytes)
{
struct modssl_buffer_ctx *ctx = f->ctx;
apr_status_t rv;
ap_log_cerror(APLOG_MARK, APLOG_DEBUG, 0, f->c,
"read from buffered SSL brigade, mode %d, "
"%" APR_OFF_T_FMT " bytes",
mode, bytes);
if (mode != AP_MODE_READBYTES && mode != AP_MODE_GETLINE) {
return APR_ENOTIMPL;
}
if (mode == AP_MODE_READBYTES) {
apr_bucket *e;
/* Partition the buffered brigade. */
rv = apr_brigade_partition(ctx->bb, bytes, &e);
if (rv && rv != APR_INCOMPLETE) {
ap_log_cerror(APLOG_MARK, APLOG_ERR, rv, f->c,
"could not partition buffered SSL brigade");
ap_remove_input_filter(f);
return rv;
}
/* If the buffered brigade contains less then the requested
* length, just pass it all back. */
if (rv == APR_INCOMPLETE) {
APR_BRIGADE_CONCAT(bb, ctx->bb);
} else {
apr_bucket *d = APR_BRIGADE_FIRST(ctx->bb);
e = APR_BUCKET_PREV(e);
/* Unsplice the partitioned segment and move it into the
* passed-in brigade; no convenient way to do this with
* the APR_BRIGADE_* macros. */
APR_RING_UNSPLICE(d, e, link);
APR_RING_SPLICE_HEAD(&bb->list, d, e, apr_bucket, link);
APR_BRIGADE_CHECK_CONSISTENCY(bb);
APR_BRIGADE_CHECK_CONSISTENCY(ctx->bb);
}
}
else {
/* Split a line into the passed-in brigade. */
rv = apr_brigade_split_line(bb, ctx->bb, mode, bytes);
if (rv) {
ap_log_cerror(APLOG_MARK, APLOG_ERR, rv, f->c,
"could not split line from buffered SSL brigade");
ap_remove_input_filter(f);
return rv;
}
}
if (APR_BRIGADE_EMPTY(ctx->bb)) {
apr_bucket *e = APR_BRIGADE_LAST(bb);
/* Ensure that the brigade is terminated by an EOS if the
* buffered request body has been entirely consumed. */
if (e == APR_BRIGADE_SENTINEL(bb) || !APR_BUCKET_IS_EOS(e)) {
e = apr_bucket_eos_create(f->c->bucket_alloc);
APR_BRIGADE_INSERT_TAIL(bb, e);
}
ap_log_cerror(APLOG_MARK, APLOG_DEBUG, 0, f->c,
"buffered SSL brigade now exhausted; removing filter");
ap_remove_input_filter(f);
}
return APR_SUCCESS;
}
static void ssl_io_input_add_filter(ssl_filter_ctx_t *filter_ctx, conn_rec *c,
SSL *ssl)
{
@@ -1508,6 +1690,9 @@ void ssl_io_filter_register(apr_pool_t *p)
ap_register_input_filter (ssl_io_filter, ssl_io_filter_input, NULL, AP_FTYPE_CONNECTION + 5);
ap_register_output_filter (ssl_io_filter, ssl_io_filter_output, NULL, AP_FTYPE_CONNECTION + 5);
ap_register_input_filter (ssl_io_buffer, ssl_io_filter_buffer, NULL, AP_FTYPE_PROTOCOL - 1);
return;
}

90
modules/ssl/ssl_engine_kernel.c
View File

@@ -490,73 +490,35 @@ int ssl_hook_Access(request_rec *r)
}
#endif /* HAVE_SSL_SET_CERT_STORE */
/*
* SSL renegotiations in conjunction with HTTP
* requests using the POST method are not supported.
/* If a renegotiation is now required for this location, and the
* request includes a message body (and the client has not
* requested a "100 Continue" response), then the client will be
* streaming the request body over the wire already. In that
* case, it is not possible to stop and perform a new SSL
* handshake immediately; once the SSL library moves to the
* "accept" state, it will reject the SSL packets which the client
* is sending for the request body.
*
* Background:
*
* 1. When the client sends a HTTP/HTTPS request, Apache's core code
* reads only the request line ("METHOD /path HTTP/x.y") and the
* attached MIME headers ("Foo: bar") up to the terminating line ("CR
* LF"). An attached request body (for instance the data of a POST
* method) is _NOT_ read. Instead it is read by mod_cgi's content
* handler and directly passed to the CGI script.
*
* 2. mod_ssl supports per-directory re-configuration of SSL parameters.
* This is implemented by performing an SSL renegotiation of the
* re-configured parameters after the request is read, but before the
* response is sent. In more detail: the renegotiation happens after the
* request line and MIME headers were read, but _before_ the attached
* request body is read. The reason simply is that in the HTTP protocol
* usually there is no acknowledgment step between the headers and the
* body (there is the 100-continue feature and the chunking facility
* only), so Apache has no API hook for this step.
*
* 3. the problem now occurs when the client sends a POST request for
* URL /foo via HTTPS the server and the server has SSL parameters
* re-configured on a per-URL basis for /foo. Then mod_ssl has to
* perform an SSL renegotiation after the request was read and before
* the response is sent. But the problem is the pending POST body data
* in the receive buffer of SSL (which Apache still has not read - it's
* pending until mod_cgi sucks it in). When mod_ssl now tries to perform
* the renegotiation the pending data leads to an I/O error.
*
* Solution Idea:
*
* There are only two solutions: Either to simply state that POST
* requests to URLs with SSL re-configurations are not allowed, or to
* renegotiate really after the _complete_ request (i.e. including
* the POST body) was read. Obviously the latter would be preferred,
* but it cannot be done easily inside Apache, because as already
* mentioned, there is no API step between the body reading and the body
* processing. And even when we mod_ssl would hook directly into the
* loop of mod_cgi, we wouldn't solve the problem for other handlers, of
* course. So the only general solution is to suck in the pending data
* of the request body from the OpenSSL BIO into the Apache BUFF. Then
* the renegotiation can be done and after this step Apache can proceed
* processing the request as before.
*
* Solution Implementation:
*
* We cannot simply suck in the data via an SSL_read-based loop because of
* HTTP chunking. Instead we _have_ to use the Apache API for this step which
* is aware of HTTP chunking. So the trick is to suck in the pending request
* data via the Apache API (which uses Apache's BUFF code and in the
* background mod_ssl's I/O glue code) and re-inject it later into the Apache
* BUFF code again. This way the data flows twice through the Apache BUFF, of
* course. But this way the solution doesn't depend on any Apache specifics
* and is fully transparent to Apache modules.
*
* !! BUT ALL THIS IS STILL NOT RE-IMPLEMENTED FOR APACHE 2.0 !!
* To allow authentication to complete in this auth hook, the
* solution used here is to fill a (bounded) buffer with the
* request body, and then to reinject that request body later.
*/
if (renegotiate && !renegotiate_quick && (r->method_number == M_POST)) {
ap_log_error(APLOG_MARK, APLOG_ERR, 0, r->server,
"SSL Re-negotiation in conjunction "
"with POST method not supported! "
"hint: try SSLOptions +OptRenegotiate");
if (renegotiate && !renegotiate_quick
&& (apr_table_get(r->headers_in, "transfer-encoding")
|| (apr_table_get(r->headers_in, "content-length")
&& strcmp(apr_table_get(r->headers_in, "content-length"), "0")))
&& !r->expecting_100) {
int rv;
return HTTP_METHOD_NOT_ALLOWED;
/* Fill the I/O buffer with the request body if possible. */
rv = ssl_io_buffer_fill(r);
if (rv) {
ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
"could not buffer message body to allow "
"SSL renegotiation to proceed");
return rv;
}
}
/*

4
modules/ssl/ssl_private.h
View File

@@ -595,6 +595,10 @@ void ssl_io_filter_init(conn_rec *, SSL *);
void ssl_io_filter_register(apr_pool_t *);
long ssl_io_data_cb(BIO *, int, MODSSL_BIO_CB_ARG_TYPE *, int, long, long);
/* ssl_io_buffer_fill fills the setaside buffering of the HTTP request
* to allow an SSL renegotiation to take place. */
int ssl_io_buffer_fill(request_rec *r);
/** PRNG */
int ssl_rand_seed(server_rec *, apr_pool_t *, ssl_rsctx_t, char *);