Mercurial > hg > nginx
view src/http/modules/ngx_http_random_index_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 | 47daf95d0138 |
children | 061ec464813f |
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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 { ngx_flag_t enable; } ngx_http_random_index_loc_conf_t; #define NGX_HTTP_RANDOM_INDEX_PREALLOCATE 50 static ngx_int_t ngx_http_random_index_error(ngx_http_request_t *r, ngx_dir_t *dir, ngx_str_t *name); static ngx_int_t ngx_http_random_index_init(ngx_conf_t *cf); static void *ngx_http_random_index_create_loc_conf(ngx_conf_t *cf); static char *ngx_http_random_index_merge_loc_conf(ngx_conf_t *cf, void *parent, void *child); static ngx_command_t ngx_http_random_index_commands[] = { { ngx_string("random_index"), NGX_HTTP_LOC_CONF|NGX_CONF_FLAG, ngx_conf_set_flag_slot, NGX_HTTP_LOC_CONF_OFFSET, offsetof(ngx_http_random_index_loc_conf_t, enable), NULL }, ngx_null_command }; static ngx_http_module_t ngx_http_random_index_module_ctx = { NULL, /* preconfiguration */ ngx_http_random_index_init, /* postconfiguration */ NULL, /* create main configuration */ NULL, /* init main configuration */ NULL, /* create server configuration */ NULL, /* merge server configuration */ ngx_http_random_index_create_loc_conf, /* create location configuration */ ngx_http_random_index_merge_loc_conf /* merge location configuration */ }; ngx_module_t ngx_http_random_index_module = { NGX_MODULE_V1, &ngx_http_random_index_module_ctx, /* module context */ ngx_http_random_index_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_random_index_handler(ngx_http_request_t *r) { u_char *last, *filename; size_t len, allocated, root; ngx_err_t err; ngx_int_t rc; ngx_str_t path, uri, *name; ngx_dir_t dir; ngx_uint_t n, level; ngx_array_t names; ngx_http_random_index_loc_conf_t *rlcf; if (r->uri.data[r->uri.len - 1] != '/') { return NGX_DECLINED; } if (!(r->method & (NGX_HTTP_GET|NGX_HTTP_HEAD|NGX_HTTP_POST))) { return NGX_DECLINED; } rlcf = ngx_http_get_module_loc_conf(r, ngx_http_random_index_module); if (!rlcf->enable) { return NGX_DECLINED; } #if (NGX_HAVE_D_TYPE) len = NGX_DIR_MASK_LEN; #else len = NGX_HTTP_RANDOM_INDEX_PREALLOCATE; #endif last = ngx_http_map_uri_to_path(r, &path, &root, len); if (last == NULL) { return NGX_HTTP_INTERNAL_SERVER_ERROR; } allocated = path.len; path.len = last - path.data - 1; path.data[path.len] = '\0'; ngx_log_debug1(NGX_LOG_DEBUG_HTTP, r->connection->log, 0, "http random index: \"%s\"", path.data); if (ngx_open_dir(&path, &dir) == NGX_ERROR) { err = ngx_errno; if (err == NGX_ENOENT || err == NGX_ENOTDIR || err == NGX_ENAMETOOLONG) { level = NGX_LOG_ERR; rc = NGX_HTTP_NOT_FOUND; } else if (err == NGX_EACCES) { level = NGX_LOG_ERR; rc = NGX_HTTP_FORBIDDEN; } else { level = NGX_LOG_CRIT; rc = NGX_HTTP_INTERNAL_SERVER_ERROR; } ngx_log_error(level, r->connection->log, err, ngx_open_dir_n " \"%s\" failed", path.data); return rc; } if (ngx_array_init(&names, r->pool, 32, sizeof(ngx_str_t)) != NGX_OK) { return ngx_http_random_index_error(r, &dir, &path); } filename = path.data; filename[path.len] = '/'; for ( ;; ) { ngx_set_errno(0); if (ngx_read_dir(&dir) == NGX_ERROR) { err = ngx_errno; if (err != NGX_ENOMOREFILES) { ngx_log_error(NGX_LOG_CRIT, r->connection->log, err, ngx_read_dir_n " \"%V\" failed", &path); return ngx_http_random_index_error(r, &dir, &path); } break; } ngx_log_debug1(NGX_LOG_DEBUG_HTTP, r->connection->log, 0, "http random index file: \"%s\"", ngx_de_name(&dir)); if (ngx_de_name(&dir)[0] == '.') { continue; } len = ngx_de_namelen(&dir); if (dir.type == 0 || ngx_de_is_link(&dir)) { /* 1 byte for '/' and 1 byte for terminating '\0' */ if (path.len + 1 + len + 1 > allocated) { allocated = path.len + 1 + len + 1 + NGX_HTTP_RANDOM_INDEX_PREALLOCATE; filename = ngx_pnalloc(r->pool, allocated); if (filename == NULL) { return ngx_http_random_index_error(r, &dir, &path); } last = ngx_cpystrn(filename, path.data, path.len + 1); *last++ = '/'; } ngx_cpystrn(last, ngx_de_name(&dir), len + 1); if (ngx_de_info(filename, &dir) == NGX_FILE_ERROR) { err = ngx_errno; if (err != NGX_ENOENT) { ngx_log_error(NGX_LOG_CRIT, r->connection->log, err, ngx_de_info_n " \"%s\" failed", filename); return ngx_http_random_index_error(r, &dir, &path); } if (ngx_de_link_info(filename, &dir) == NGX_FILE_ERROR) { ngx_log_error(NGX_LOG_CRIT, r->connection->log, ngx_errno, ngx_de_link_info_n " \"%s\" failed", filename); return ngx_http_random_index_error(r, &dir, &path); } } } if (!ngx_de_is_file(&dir)) { continue; } name = ngx_array_push(&names); if (name == NULL) { return ngx_http_random_index_error(r, &dir, &path); } name->len = len; name->data = ngx_pnalloc(r->pool, len); if (name->data == NULL) { return ngx_http_random_index_error(r, &dir, &path); } ngx_memcpy(name->data, ngx_de_name(&dir), len); } if (ngx_close_dir(&dir) == NGX_ERROR) { ngx_log_error(NGX_LOG_ALERT, r->connection->log, ngx_errno, ngx_close_dir_n " \"%V\" failed", &path); } n = names.nelts; if (n == 0) { return NGX_DECLINED; } name = names.elts; n = (ngx_uint_t) (((uint64_t) ngx_random() * n) / 0x80000000); uri.len = r->uri.len + name[n].len; uri.data = ngx_pnalloc(r->pool, uri.len); if (uri.data == NULL) { return NGX_HTTP_INTERNAL_SERVER_ERROR; } last = ngx_copy(uri.data, r->uri.data, r->uri.len); ngx_memcpy(last, name[n].data, name[n].len); return ngx_http_internal_redirect(r, &uri, &r->args); } static ngx_int_t ngx_http_random_index_error(ngx_http_request_t *r, ngx_dir_t *dir, ngx_str_t *name) { if (ngx_close_dir(dir) == NGX_ERROR) { ngx_log_error(NGX_LOG_ALERT, r->connection->log, ngx_errno, ngx_close_dir_n " \"%V\" failed", name); } return NGX_HTTP_INTERNAL_SERVER_ERROR; } static void * ngx_http_random_index_create_loc_conf(ngx_conf_t *cf) { ngx_http_random_index_loc_conf_t *conf; conf = ngx_palloc(cf->pool, sizeof(ngx_http_random_index_loc_conf_t)); if (conf == NULL) { return NULL; } conf->enable = NGX_CONF_UNSET; return conf; } static char * ngx_http_random_index_merge_loc_conf(ngx_conf_t *cf, void *parent, void *child) { ngx_http_random_index_loc_conf_t *prev = parent; ngx_http_random_index_loc_conf_t *conf = child; ngx_conf_merge_value(conf->enable, prev->enable, 0); return NGX_CONF_OK; } static ngx_int_t ngx_http_random_index_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_CONTENT_PHASE].handlers); if (h == NULL) { return NGX_ERROR; } *h = ngx_http_random_index_handler; return NGX_OK; }