Mercurial > hg > nginx
view src/http/modules/ngx_http_degradation_module.c @ 7674:7731c710796f
Memcached: protect from too long responses.
If a memcached response was followed by a correct trailer, and then
the NUL character followed by some extra data - this was accepted by
the trailer checking code. This in turn resulted in ctx->rest underflow
and caused negative size buffer on the next reading from the upstream,
followed by the "negative size buf in writer" alert.
Fix is to always check for too long responses, so a correct trailer cannot
be followed by extra data.
author | Maxim Dounin <mdounin@mdounin.ru> |
---|---|
date | Mon, 06 Jul 2020 18:36:17 +0300 |
parents | 67653855682e |
children |
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/* * Copyright (C) Igor Sysoev * Copyright (C) Nginx, Inc. */ #include <ngx_config.h> #include <ngx_core.h> #include <ngx_http.h> typedef struct { size_t sbrk_size; } ngx_http_degradation_main_conf_t; typedef struct { ngx_uint_t degrade; } ngx_http_degradation_loc_conf_t; static ngx_conf_enum_t ngx_http_degrade[] = { { ngx_string("204"), 204 }, { ngx_string("444"), 444 }, { ngx_null_string, 0 } }; static void *ngx_http_degradation_create_main_conf(ngx_conf_t *cf); static void *ngx_http_degradation_create_loc_conf(ngx_conf_t *cf); static char *ngx_http_degradation_merge_loc_conf(ngx_conf_t *cf, void *parent, void *child); static char *ngx_http_degradation(ngx_conf_t *cf, ngx_command_t *cmd, void *conf); static ngx_int_t ngx_http_degradation_init(ngx_conf_t *cf); static ngx_command_t ngx_http_degradation_commands[] = { { ngx_string("degradation"), NGX_HTTP_MAIN_CONF|NGX_CONF_TAKE1, ngx_http_degradation, NGX_HTTP_MAIN_CONF_OFFSET, 0, NULL }, { ngx_string("degrade"), NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_TAKE1, ngx_conf_set_enum_slot, NGX_HTTP_LOC_CONF_OFFSET, offsetof(ngx_http_degradation_loc_conf_t, degrade), &ngx_http_degrade }, ngx_null_command }; static ngx_http_module_t ngx_http_degradation_module_ctx = { NULL, /* preconfiguration */ ngx_http_degradation_init, /* postconfiguration */ ngx_http_degradation_create_main_conf, /* create main configuration */ NULL, /* init main configuration */ NULL, /* create server configuration */ NULL, /* merge server configuration */ ngx_http_degradation_create_loc_conf, /* create location configuration */ ngx_http_degradation_merge_loc_conf /* merge location configuration */ }; ngx_module_t ngx_http_degradation_module = { NGX_MODULE_V1, &ngx_http_degradation_module_ctx, /* module context */ ngx_http_degradation_commands, /* module directives */ NGX_HTTP_MODULE, /* module type */ NULL, /* init master */ NULL, /* init module */ NULL, /* init process */ NULL, /* init thread */ NULL, /* exit thread */ NULL, /* exit process */ NULL, /* exit master */ NGX_MODULE_V1_PADDING }; static ngx_int_t ngx_http_degradation_handler(ngx_http_request_t *r) { ngx_http_degradation_loc_conf_t *dlcf; dlcf = ngx_http_get_module_loc_conf(r, ngx_http_degradation_module); if (dlcf->degrade && ngx_http_degraded(r)) { return dlcf->degrade; } return NGX_DECLINED; } ngx_uint_t ngx_http_degraded(ngx_http_request_t *r) { time_t now; ngx_uint_t log; static size_t sbrk_size; static time_t sbrk_time; ngx_http_degradation_main_conf_t *dmcf; dmcf = ngx_http_get_module_main_conf(r, ngx_http_degradation_module); if (dmcf->sbrk_size) { log = 0; now = ngx_time(); /* lock mutex */ if (now != sbrk_time) { /* * ELF/i386 is loaded at 0x08000000, 128M * ELF/amd64 is loaded at 0x00400000, 4M * * use a function address to subtract the loading address */ sbrk_size = (size_t) sbrk(0) - ((uintptr_t) ngx_palloc & ~0x3FFFFF); sbrk_time = now; log = 1; } /* unlock mutex */ if (sbrk_size >= dmcf->sbrk_size) { if (log) { ngx_log_error(NGX_LOG_NOTICE, r->connection->log, 0, "degradation sbrk:%uzM", sbrk_size / (1024 * 1024)); } return 1; } } return 0; } static void * ngx_http_degradation_create_main_conf(ngx_conf_t *cf) { ngx_http_degradation_main_conf_t *dmcf; dmcf = ngx_pcalloc(cf->pool, sizeof(ngx_http_degradation_main_conf_t)); if (dmcf == NULL) { return NULL; } return dmcf; } static void * ngx_http_degradation_create_loc_conf(ngx_conf_t *cf) { ngx_http_degradation_loc_conf_t *conf; conf = ngx_palloc(cf->pool, sizeof(ngx_http_degradation_loc_conf_t)); if (conf == NULL) { return NULL; } conf->degrade = NGX_CONF_UNSET_UINT; return conf; } static char * ngx_http_degradation_merge_loc_conf(ngx_conf_t *cf, void *parent, void *child) { ngx_http_degradation_loc_conf_t *prev = parent; ngx_http_degradation_loc_conf_t *conf = child; ngx_conf_merge_uint_value(conf->degrade, prev->degrade, 0); return NGX_CONF_OK; } static char * ngx_http_degradation(ngx_conf_t *cf, ngx_command_t *cmd, void *conf) { ngx_http_degradation_main_conf_t *dmcf = conf; ngx_str_t *value, s; value = cf->args->elts; if (ngx_strncmp(value[1].data, "sbrk=", 5) == 0) { s.len = value[1].len - 5; s.data = value[1].data + 5; dmcf->sbrk_size = ngx_parse_size(&s); if (dmcf->sbrk_size == (size_t) NGX_ERROR) { ngx_conf_log_error(NGX_LOG_EMERG, cf, 0, "invalid sbrk size \"%V\"", &value[1]); return NGX_CONF_ERROR; } return NGX_CONF_OK; } ngx_conf_log_error(NGX_LOG_EMERG, cf, 0, "invalid parameter \"%V\"", &value[1]); return NGX_CONF_ERROR; } static ngx_int_t ngx_http_degradation_init(ngx_conf_t *cf) { ngx_http_handler_pt *h; ngx_http_core_main_conf_t *cmcf; cmcf = ngx_http_conf_get_module_main_conf(cf, ngx_http_core_module); h = ngx_array_push(&cmcf->phases[NGX_HTTP_PREACCESS_PHASE].handlers); if (h == NULL) { return NGX_ERROR; } *h = ngx_http_degradation_handler; return NGX_OK; }