From b6ec5483008fb57c727d64409b2a42c48c118430 Mon Sep 17 00:00:00 2001 From: Aurora Date: Wed, 10 Apr 2024 16:32:54 +0800 Subject: [PATCH] Reading unbounded number of HTTP/2 CONTINUATION frames to cause excessive CPU usage Signed-off-by: Aurora Change-Id: I75034195506a0704fb659cee4b26fbc9b2f99150 --- doc/Makefile.am | 1 + lib/includes/nghttp2/nghttp2.h | 18 +++++++++++++++++- lib/nghttp2_helper.c | 2 ++ lib/nghttp2_option.c | 5 +++++ lib/nghttp2_option.h | 5 +++++ lib/nghttp2_session.c | 11 +++++++++++ lib/nghttp2_session.h | 10 ++++++++++ 7 files changed, 51 insertions(+), 1 deletion(-) diff --git a/doc/Makefile.am b/doc/Makefile.am index 96f449ff..5636a137 100644 --- a/doc/Makefile.am +++ b/doc/Makefile.am @@ -73,6 +73,7 @@ APIDOCS= \ nghttp2_option_set_peer_max_concurrent_streams.rst \ nghttp2_option_set_server_fallback_rfc7540_priorities.rst \ nghttp2_option_set_user_recv_extension_type.rst \ + nghttp2_option_set_max_continuations.rst \ nghttp2_option_set_max_outbound_ack.rst \ nghttp2_option_set_max_settings.rst \ nghttp2_option_set_stream_reset_rate_limit.rst \ diff --git a/lib/includes/nghttp2/nghttp2.h b/lib/includes/nghttp2/nghttp2.h index fa22081c..4d3339b5 100644 --- a/lib/includes/nghttp2/nghttp2.h +++ b/lib/includes/nghttp2/nghttp2.h @@ -440,7 +440,12 @@ typedef enum { * exhaustion on server side to send these frames forever and does * not read network. */ - NGHTTP2_ERR_FLOODED = -904 + NGHTTP2_ERR_FLOODED = -904, + /** + * When a local endpoint receives too many CONTINUATION frames + * following a HEADER frame. + */ + NGHTTP2_ERR_TOO_MANY_CONTINUATIONS = -905, } nghttp2_error; /** @@ -2773,6 +2778,17 @@ NGHTTP2_EXTERN void nghttp2_option_set_stream_reset_rate_limit(nghttp2_option *option, uint64_t burst, uint64_t rate); +/** + * @function + * + * This function sets the maximum number of CONTINUATION frames + * following an incoming HEADER frame. If more than those frames are + * received, the remote endpoint is considered to be misbehaving and + * session will be closed. The default value is 8. + */ +NGHTTP2_EXTERN void nghttp2_option_set_max_continuations(nghttp2_option *option, + size_t val); + /** * @function * diff --git a/lib/nghttp2_helper.c b/lib/nghttp2_helper.c index 93dd4754..b3563d98 100644 --- a/lib/nghttp2_helper.c +++ b/lib/nghttp2_helper.c @@ -336,6 +336,8 @@ const char *nghttp2_strerror(int error_code) { "closed"; case NGHTTP2_ERR_TOO_MANY_SETTINGS: return "SETTINGS frame contained more than the maximum allowed entries"; + case NGHTTP2_ERR_TOO_MANY_CONTINUATIONS: + return "Too many CONTINUATION frames following a HEADER frame"; default: return "Unknown error code"; } diff --git a/lib/nghttp2_option.c b/lib/nghttp2_option.c index 43d4e952..53144b9b 100644 --- a/lib/nghttp2_option.c +++ b/lib/nghttp2_option.c @@ -150,3 +150,8 @@ void nghttp2_option_set_stream_reset_rate_limit(nghttp2_option *option, option->stream_reset_burst = burst; option->stream_reset_rate = rate; } + +void nghttp2_option_set_max_continuations(nghttp2_option *option, size_t val) { + option->opt_set_mask |= NGHTTP2_OPT_MAX_CONTINUATIONS; + option->max_continuations = val; +} diff --git a/lib/nghttp2_option.h b/lib/nghttp2_option.h index 2259e184..c89cb97f 100644 --- a/lib/nghttp2_option.h +++ b/lib/nghttp2_option.h @@ -71,6 +71,7 @@ typedef enum { NGHTTP2_OPT_SERVER_FALLBACK_RFC7540_PRIORITIES = 1 << 13, NGHTTP2_OPT_NO_RFC9113_LEADING_AND_TRAILING_WS_VALIDATION = 1 << 14, NGHTTP2_OPT_STREAM_RESET_RATE_LIMIT = 1 << 15, + NGHTTP2_OPT_MAX_CONTINUATIONS = 1 << 16, } nghttp2_option_flag; /** @@ -98,6 +99,10 @@ struct nghttp2_option { * NGHTTP2_OPT_MAX_SETTINGS */ size_t max_settings; + /** + * NGHTTP2_OPT_MAX_CONTINUATIONS + */ + size_t max_continuations; /** * Bitwise OR of nghttp2_option_flag to determine that which fields * are specified. diff --git a/lib/nghttp2_session.c b/lib/nghttp2_session.c index ec5024d0..ced7517b 100644 --- a/lib/nghttp2_session.c +++ b/lib/nghttp2_session.c @@ -496,6 +496,7 @@ static int session_new(nghttp2_session **session_ptr, (*session_ptr)->max_send_header_block_length = NGHTTP2_MAX_HEADERSLEN; (*session_ptr)->max_outbound_ack = NGHTTP2_DEFAULT_MAX_OBQ_FLOOD_ITEM; (*session_ptr)->max_settings = NGHTTP2_DEFAULT_MAX_SETTINGS; + (*session_ptr)->max_continuations = NGHTTP2_DEFAULT_MAX_CONTINUATIONS; if (option) { if ((option->opt_set_mask & NGHTTP2_OPT_NO_AUTO_WINDOW_UPDATE) && @@ -584,6 +585,10 @@ static int session_new(nghttp2_session **session_ptr, option->stream_reset_burst, option->stream_reset_rate); } + + if (option->opt_set_mask & NGHTTP2_OPT_MAX_CONTINUATIONS) { + (*session_ptr)->max_continuations = option->max_continuations; + } } rv = nghttp2_hd_deflate_init2(&(*session_ptr)->hd_deflater, @@ -6778,6 +6783,8 @@ ssize_t nghttp2_session_mem_recv(nghttp2_session *session, const uint8_t *in, } } session_inbound_frame_reset(session); + + session->num_continuations = 0; } break; } @@ -6899,6 +6906,10 @@ ssize_t nghttp2_session_mem_recv(nghttp2_session *session, const uint8_t *in, } #endif /* DEBUGBUILD */ + if (++session->num_continuations > session->max_continuations) { + return NGHTTP2_ERR_TOO_MANY_CONTINUATIONS; + } + readlen = inbound_frame_buf_read(iframe, in, last); in += readlen; diff --git a/lib/nghttp2_session.h b/lib/nghttp2_session.h index b119329a..ef8f7b27 100644 --- a/lib/nghttp2_session.h +++ b/lib/nghttp2_session.h @@ -110,6 +110,10 @@ typedef struct { #define NGHTTP2_DEFAULT_STREAM_RESET_BURST 1000 #define NGHTTP2_DEFAULT_STREAM_RESET_RATE 33 +/* The default max number of CONTINUATION frames following an incoming + HEADER frame. */ +#define NGHTTP2_DEFAULT_MAX_CONTINUATIONS 8 + /* Internal state when receiving incoming frame */ typedef enum { /* Receiving frame header */ @@ -290,6 +294,12 @@ struct nghttp2_session { size_t max_send_header_block_length; /* The maximum number of settings accepted per SETTINGS frame. */ size_t max_settings; + /* The maximum number of CONTINUATION frames following an incoming + HEADER frame. */ + size_t max_continuations; + /* The number of CONTINUATION frames following an incoming HEADER + frame. This variable is reset when END_HEADERS flag is seen. */ + size_t num_continuations; /* Next Stream ID. Made unsigned int to detect >= (1 << 31). */ uint32_t next_stream_id; /* The last stream ID this session initiated. For client session,