Mercurial > hg > nginx
view src/http/modules/ngx_http_upstream_least_conn_module.c @ 7060:1adc6b0d5eaa stable-1.12
Range filter: protect from total size overflows.
The overflow can be used to circumvent the restriction on total size of
ranges introduced in c2a91088b0c0 (1.1.2). Additionally, overflow
allows producing ranges with negative start (such ranges can be created
by using a suffix, "bytes=-100"; normally this results in 200 due to
the total size check). These can result in the following errors in logs:
[crit] ... pread() ... failed (22: Invalid argument)
[alert] ... sendfile() failed (22: Invalid argument)
When using cache, it can be also used to reveal cache file header.
It is believed that there are no other negative effects, at least with
standard nginx modules.
In theory, this can also result in memory disclosure and/or segmentation
faults if multiple ranges are allowed, and the response is returned in a
single in-memory buffer. This never happens with standard nginx modules
though, as well as known 3rd party modules.
Fix is to properly protect from possible overflow when incrementing size.
author | Maxim Dounin <mdounin@mdounin.ru> |
---|---|
date | Tue, 11 Jul 2017 16:06:23 +0300 |
parents | 29bf0dbc0a77 |
children |
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/* * Copyright (C) Maxim Dounin * Copyright (C) Nginx, Inc. */ #include <ngx_config.h> #include <ngx_core.h> #include <ngx_http.h> static ngx_int_t ngx_http_upstream_init_least_conn_peer(ngx_http_request_t *r, ngx_http_upstream_srv_conf_t *us); static ngx_int_t ngx_http_upstream_get_least_conn_peer( ngx_peer_connection_t *pc, void *data); static char *ngx_http_upstream_least_conn(ngx_conf_t *cf, ngx_command_t *cmd, void *conf); static ngx_command_t ngx_http_upstream_least_conn_commands[] = { { ngx_string("least_conn"), NGX_HTTP_UPS_CONF|NGX_CONF_NOARGS, ngx_http_upstream_least_conn, 0, 0, NULL }, ngx_null_command }; static ngx_http_module_t ngx_http_upstream_least_conn_module_ctx = { NULL, /* preconfiguration */ NULL, /* postconfiguration */ NULL, /* create main configuration */ NULL, /* init main configuration */ NULL, /* create server configuration */ NULL, /* merge server configuration */ NULL, /* create location configuration */ NULL /* merge location configuration */ }; ngx_module_t ngx_http_upstream_least_conn_module = { NGX_MODULE_V1, &ngx_http_upstream_least_conn_module_ctx, /* module context */ ngx_http_upstream_least_conn_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_upstream_init_least_conn(ngx_conf_t *cf, ngx_http_upstream_srv_conf_t *us) { ngx_log_debug0(NGX_LOG_DEBUG_HTTP, cf->log, 0, "init least conn"); if (ngx_http_upstream_init_round_robin(cf, us) != NGX_OK) { return NGX_ERROR; } us->peer.init = ngx_http_upstream_init_least_conn_peer; return NGX_OK; } static ngx_int_t ngx_http_upstream_init_least_conn_peer(ngx_http_request_t *r, ngx_http_upstream_srv_conf_t *us) { ngx_log_debug0(NGX_LOG_DEBUG_HTTP, r->connection->log, 0, "init least conn peer"); if (ngx_http_upstream_init_round_robin_peer(r, us) != NGX_OK) { return NGX_ERROR; } r->upstream->peer.get = ngx_http_upstream_get_least_conn_peer; return NGX_OK; } static ngx_int_t ngx_http_upstream_get_least_conn_peer(ngx_peer_connection_t *pc, void *data) { ngx_http_upstream_rr_peer_data_t *rrp = data; time_t now; uintptr_t m; ngx_int_t rc, total; ngx_uint_t i, n, p, many; ngx_http_upstream_rr_peer_t *peer, *best; ngx_http_upstream_rr_peers_t *peers; ngx_log_debug1(NGX_LOG_DEBUG_HTTP, pc->log, 0, "get least conn peer, try: %ui", pc->tries); if (rrp->peers->single) { return ngx_http_upstream_get_round_robin_peer(pc, rrp); } pc->cached = 0; pc->connection = NULL; now = ngx_time(); peers = rrp->peers; ngx_http_upstream_rr_peers_wlock(peers); best = NULL; total = 0; #if (NGX_SUPPRESS_WARN) many = 0; p = 0; #endif for (peer = peers->peer, i = 0; peer; peer = peer->next, i++) { n = i / (8 * sizeof(uintptr_t)); m = (uintptr_t) 1 << i % (8 * sizeof(uintptr_t)); if (rrp->tried[n] & m) { continue; } if (peer->down) { continue; } if (peer->max_fails && peer->fails >= peer->max_fails && now - peer->checked <= peer->fail_timeout) { continue; } if (peer->max_conns && peer->conns >= peer->max_conns) { continue; } /* * select peer with least number of connections; if there are * multiple peers with the same number of connections, select * based on round-robin */ if (best == NULL || peer->conns * best->weight < best->conns * peer->weight) { best = peer; many = 0; p = i; } else if (peer->conns * best->weight == best->conns * peer->weight) { many = 1; } } if (best == NULL) { ngx_log_debug0(NGX_LOG_DEBUG_HTTP, pc->log, 0, "get least conn peer, no peer found"); goto failed; } if (many) { ngx_log_debug0(NGX_LOG_DEBUG_HTTP, pc->log, 0, "get least conn peer, many"); for (peer = best, i = p; peer; peer = peer->next, i++) { n = i / (8 * sizeof(uintptr_t)); m = (uintptr_t) 1 << i % (8 * sizeof(uintptr_t)); if (rrp->tried[n] & m) { continue; } if (peer->down) { continue; } if (peer->conns * best->weight != best->conns * peer->weight) { continue; } if (peer->max_fails && peer->fails >= peer->max_fails && now - peer->checked <= peer->fail_timeout) { continue; } if (peer->max_conns && peer->conns >= peer->max_conns) { continue; } peer->current_weight += peer->effective_weight; total += peer->effective_weight; if (peer->effective_weight < peer->weight) { peer->effective_weight++; } if (peer->current_weight > best->current_weight) { best = peer; p = i; } } } best->current_weight -= total; if (now - best->checked > best->fail_timeout) { best->checked = now; } pc->sockaddr = best->sockaddr; pc->socklen = best->socklen; pc->name = &best->name; best->conns++; rrp->current = best; n = p / (8 * sizeof(uintptr_t)); m = (uintptr_t) 1 << p % (8 * sizeof(uintptr_t)); rrp->tried[n] |= m; ngx_http_upstream_rr_peers_unlock(peers); return NGX_OK; failed: if (peers->next) { ngx_log_debug0(NGX_LOG_DEBUG_HTTP, pc->log, 0, "get least conn peer, backup servers"); rrp->peers = peers->next; n = (rrp->peers->number + (8 * sizeof(uintptr_t) - 1)) / (8 * sizeof(uintptr_t)); for (i = 0; i < n; i++) { rrp->tried[i] = 0; } ngx_http_upstream_rr_peers_unlock(peers); rc = ngx_http_upstream_get_least_conn_peer(pc, rrp); if (rc != NGX_BUSY) { return rc; } ngx_http_upstream_rr_peers_wlock(peers); } ngx_http_upstream_rr_peers_unlock(peers); pc->name = peers->name; return NGX_BUSY; } static char * ngx_http_upstream_least_conn(ngx_conf_t *cf, ngx_command_t *cmd, void *conf) { ngx_http_upstream_srv_conf_t *uscf; uscf = ngx_http_conf_get_module_srv_conf(cf, ngx_http_upstream_module); if (uscf->peer.init_upstream) { ngx_conf_log_error(NGX_LOG_WARN, cf, 0, "load balancing method redefined"); } uscf->peer.init_upstream = ngx_http_upstream_init_least_conn; uscf->flags = NGX_HTTP_UPSTREAM_CREATE |NGX_HTTP_UPSTREAM_WEIGHT |NGX_HTTP_UPSTREAM_MAX_CONNS |NGX_HTTP_UPSTREAM_MAX_FAILS |NGX_HTTP_UPSTREAM_FAIL_TIMEOUT |NGX_HTTP_UPSTREAM_DOWN |NGX_HTTP_UPSTREAM_BACKUP; return NGX_CONF_OK; }