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haproxy/include/haproxy/filters.h
Christopher Faulet 401e6dbff3 BUG/MAJOR: filters: Always keep all offsets up to date during data filtering 
When at least one data filter is registered on a channel, the offsets of all
filters must be kept up to date. For data filters but also for others. It is
safer to do it in that way. Indirectly, this patch fixes 2 hidden bugs
revealed by the commit 22fca1f2c ("BUG/MEDIUM: filters: Forward all filtered
data at the end of http filtering").

The first one, the worst of both, happens at the end of http filtering when
at least one data filtered is registered on the channel. We call the
http_end() callback function on the filters, when defined, to finish the
http filtering. But it is performed for all filters. Before the commit
22fca1f2c, the only risk was to call the http_end() callback function
unexpectedly on a filter. Now, we may have an overflow on the offset
variable, used at the end to forward all filtered data. Of course, from the
moment we forward an arbitrary huge amount of data, all kinds of bad things
may happen. So offset computation is performed for all filters and
http_end() callback function is called only for data filters.

The other one happens when a data filter alter the data of a channel, it
must update the offsets of all previous filters. But the offset of non-data
filters must be up to date, otherwise, here too we may have an integer
overflow.

Another way to fix these bugs is to always ignore non-data filters from the
offsets computation. But this patch is safer and probably easier to
maintain.

This patch must be backported in all versions where the above commit is. So
as far as 2.0.
2020-11-24 14:17:32 +01:00

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/*
* include/haproxy/filters.h
* This file defines function prototypes for stream filters management.
*
* Copyright (C) 2015 Qualys Inc., Christopher Faulet <cfaulet@qualys.com>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation, version 2.1
* exclusively.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#ifndef _HAPROXY_FILTERS_H
#define _HAPROXY_FILTERS_H
#include <haproxy/channel.h>
#include <haproxy/filters-t.h>
#include <haproxy/http_ana-t.h>
#include <haproxy/proxy-t.h>
#include <haproxy/stream-t.h>
extern const char *trace_flt_id;
extern const char *http_comp_flt_id;
extern const char *cache_store_flt_id;
extern const char *spoe_filter_id;
extern const char *fcgi_flt_id;
#define FLT_ID(flt) (flt)->config->id
#define FLT_CONF(flt) (flt)->config->conf
#define FLT_OPS(flt) (flt)->config->ops
/* Useful macros to access per-channel values. It can be safely used inside
* filters. */
#define CHN_IDX(chn) (((chn)->flags & CF_ISRESP) == CF_ISRESP)
#define FLT_STRM_OFF(s, chn) (strm_flt(s)->offset[CHN_IDX(chn)])
#define FLT_OFF(flt, chn) ((flt)->offset[CHN_IDX(chn)])
#define HAS_FILTERS(strm) ((strm)->strm_flt.flags & STRM_FLT_FL_HAS_FILTERS)
#define HAS_REQ_DATA_FILTERS(strm) ((strm)->strm_flt.nb_req_data_filters != 0)
#define HAS_RSP_DATA_FILTERS(strm) ((strm)->strm_flt.nb_rsp_data_filters != 0)
#define HAS_DATA_FILTERS(strm, chn) (((chn)->flags & CF_ISRESP) ? HAS_RSP_DATA_FILTERS(strm) : HAS_REQ_DATA_FILTERS(strm))
#define IS_REQ_DATA_FILTER(flt) ((flt)->flags & FLT_FL_IS_REQ_DATA_FILTER)
#define IS_RSP_DATA_FILTER(flt) ((flt)->flags & FLT_FL_IS_RSP_DATA_FILTER)
#define IS_DATA_FILTER(flt, chn) (((chn)->flags & CF_ISRESP) ? IS_RSP_DATA_FILTER(flt) : IS_REQ_DATA_FILTER(flt))
#define FLT_STRM_CB(strm, call) \
do { \
if (HAS_FILTERS(strm)) { call; } \
} while (0)
#define FLT_STRM_DATA_CB_IMPL_1(strm, chn, call, default_ret) \
(HAS_DATA_FILTERS(strm, chn) ? call : default_ret)
#define FLT_STRM_DATA_CB_IMPL_2(strm, chn, call, default_ret, on_error) \
({ \
int _ret; \
if (HAS_DATA_FILTERS(strm, chn)) { \
_ret = call; \
if (_ret < 0) { on_error; } \
} \
else \
_ret = default_ret; \
_ret; \
})
#define FLT_STRM_DATA_CB_IMPL_3(strm, chn, call, default_ret, on_error, on_wait) \
({ \
int _ret; \
if (HAS_DATA_FILTERS(strm, chn)) { \
_ret = call; \
if (_ret < 0) { on_error; } \
if (!_ret) { on_wait; } \
} \
else \
_ret = default_ret; \
_ret; \
})
#define FLT_STRM_DATA_CB_IMPL_X(strm, chn, call, A, B, C, DATA_CB_IMPL, ...) \
DATA_CB_IMPL
#define FLT_STRM_DATA_CB(strm, chn, call, ...) \
FLT_STRM_DATA_CB_IMPL_X(strm, chn, call, ##__VA_ARGS__, \
FLT_STRM_DATA_CB_IMPL_3(strm, chn, call, ##__VA_ARGS__), \
FLT_STRM_DATA_CB_IMPL_2(strm, chn, call, ##__VA_ARGS__), \
FLT_STRM_DATA_CB_IMPL_1(strm, chn, call, ##__VA_ARGS__))
void flt_deinit(struct proxy *p);
int flt_check(struct proxy *p);
int flt_stream_start(struct stream *s);
void flt_stream_stop(struct stream *s);
int flt_set_stream_backend(struct stream *s, struct proxy *be);
int flt_stream_init(struct stream *s);
void flt_stream_release(struct stream *s, int only_backend);
void flt_stream_check_timeouts(struct stream *s);
int flt_http_payload(struct stream *s, struct http_msg *msg, unsigned int len);
int flt_http_end(struct stream *s, struct http_msg *msg);
void flt_http_reset(struct stream *s, struct http_msg *msg);
void flt_http_reply(struct stream *s, short status, const struct buffer *msg);
int flt_start_analyze(struct stream *s, struct channel *chn, unsigned int an_bit);
int flt_pre_analyze(struct stream *s, struct channel *chn, unsigned int an_bit);
int flt_post_analyze(struct stream *s, struct channel *chn, unsigned int an_bit);
int flt_analyze_http_headers(struct stream *s, struct channel *chn, unsigned int an_bit);
int flt_end_analyze(struct stream *s, struct channel *chn, unsigned int an_bit);
int flt_xfer_data(struct stream *s, struct channel *chn, unsigned int an_bit);
void flt_register_keywords(struct flt_kw_list *kwl);
struct flt_kw *flt_find_kw(const char *kw);
void flt_dump_kws(char **out);
void list_filters(FILE *out);
/* Helper function that returns the "global" state of filters attached to a
* stream. */
static inline struct strm_flt *
strm_flt(struct stream *s)
{
return &s->strm_flt;
}
/* Registers a filter to a channel. If a filter was already registered, this
* function do nothing. Once registered, the filter becomes a "data" filter for
* this channel. */
static inline void
register_data_filter(struct stream *s, struct channel *chn, struct filter *filter)
{
if (!IS_DATA_FILTER(filter, chn)) {
if (chn->flags & CF_ISRESP) {
filter->flags |= FLT_FL_IS_RSP_DATA_FILTER;
strm_flt(s)->nb_rsp_data_filters++;
}
else {
filter->flags |= FLT_FL_IS_REQ_DATA_FILTER;
strm_flt(s)->nb_req_data_filters++;
}
}
}
/* Unregisters a "data" filter from a channel. */
static inline void
unregister_data_filter(struct stream *s, struct channel *chn, struct filter *filter)
{
if (IS_DATA_FILTER(filter, chn)) {
if (chn->flags & CF_ISRESP) {
filter->flags &= ~FLT_FL_IS_RSP_DATA_FILTER;
strm_flt(s)->nb_rsp_data_filters--;
}
else {
filter->flags &= ~FLT_FL_IS_REQ_DATA_FILTER;
strm_flt(s)->nb_req_data_filters--;
}
}
}
/* This function must be called when a filter alter payload data. It updates
* offsets of all previous filters. Do not call this function when a filter
* change the size of payload data leads to an undefined behavior.
*
* This is the filter's responsiblitiy to update data itself.
*/
static inline void
flt_update_offsets(struct filter *filter, struct channel *chn, int len)
{
struct stream *s = chn_strm(chn);
struct filter *f;
list_for_each_entry(f, &strm_flt(s)->filters, list) {
if (f == filter)
break;
FLT_OFF(f, chn) += len;
}
}
#endif /* _HAPROXY_FILTERS_H */
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