Mercurial > hg > nginx
view src/http/modules/ngx_http_flv_module.c @ 7054:e02555553d0b
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 | 99934aade555 |
children | 7a55311b0dc3 |
line wrap: on
line source
/* * Copyright (C) Igor Sysoev * Copyright (C) Nginx, Inc. */ #include <ngx_config.h> #include <ngx_core.h> #include <ngx_http.h> static char *ngx_http_flv(ngx_conf_t *cf, ngx_command_t *cmd, void *conf); static ngx_command_t ngx_http_flv_commands[] = { { ngx_string("flv"), NGX_HTTP_LOC_CONF|NGX_CONF_NOARGS, ngx_http_flv, 0, 0, NULL }, ngx_null_command }; static u_char ngx_flv_header[] = "FLV\x1\x5\0\0\0\x9\0\0\0\0"; static ngx_http_module_t ngx_http_flv_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_flv_module = { NGX_MODULE_V1, &ngx_http_flv_module_ctx, /* module context */ ngx_http_flv_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_flv_handler(ngx_http_request_t *r) { u_char *last; off_t start, len; size_t root; ngx_int_t rc; ngx_uint_t level, i; ngx_str_t path, value; ngx_log_t *log; ngx_buf_t *b; ngx_chain_t out[2]; ngx_open_file_info_t of; ngx_http_core_loc_conf_t *clcf; if (!(r->method & (NGX_HTTP_GET|NGX_HTTP_HEAD))) { return NGX_HTTP_NOT_ALLOWED; } if (r->uri.data[r->uri.len - 1] == '/') { return NGX_DECLINED; } rc = ngx_http_discard_request_body(r); if (rc != NGX_OK) { return rc; } last = ngx_http_map_uri_to_path(r, &path, &root, 0); if (last == NULL) { return NGX_HTTP_INTERNAL_SERVER_ERROR; } log = r->connection->log; path.len = last - path.data; ngx_log_debug1(NGX_LOG_DEBUG_HTTP, log, 0, "http flv filename: \"%V\"", &path); clcf = ngx_http_get_module_loc_conf(r, ngx_http_core_module); ngx_memzero(&of, sizeof(ngx_open_file_info_t)); of.read_ahead = clcf->read_ahead; of.directio = clcf->directio; of.valid = clcf->open_file_cache_valid; of.min_uses = clcf->open_file_cache_min_uses; of.errors = clcf->open_file_cache_errors; of.events = clcf->open_file_cache_events; if (ngx_http_set_disable_symlinks(r, clcf, &path, &of) != NGX_OK) { return NGX_HTTP_INTERNAL_SERVER_ERROR; } if (ngx_open_cached_file(clcf->open_file_cache, &path, &of, r->pool) != NGX_OK) { switch (of.err) { case 0: return NGX_HTTP_INTERNAL_SERVER_ERROR; case NGX_ENOENT: case NGX_ENOTDIR: case NGX_ENAMETOOLONG: level = NGX_LOG_ERR; rc = NGX_HTTP_NOT_FOUND; break; case NGX_EACCES: #if (NGX_HAVE_OPENAT) case NGX_EMLINK: case NGX_ELOOP: #endif level = NGX_LOG_ERR; rc = NGX_HTTP_FORBIDDEN; break; default: level = NGX_LOG_CRIT; rc = NGX_HTTP_INTERNAL_SERVER_ERROR; break; } if (rc != NGX_HTTP_NOT_FOUND || clcf->log_not_found) { ngx_log_error(level, log, of.err, "%s \"%s\" failed", of.failed, path.data); } return rc; } if (!of.is_file) { if (ngx_close_file(of.fd) == NGX_FILE_ERROR) { ngx_log_error(NGX_LOG_ALERT, log, ngx_errno, ngx_close_file_n " \"%s\" failed", path.data); } return NGX_DECLINED; } r->root_tested = !r->error_page; start = 0; len = of.size; i = 1; if (r->args.len) { if (ngx_http_arg(r, (u_char *) "start", 5, &value) == NGX_OK) { start = ngx_atoof(value.data, value.len); if (start == NGX_ERROR || start >= len) { start = 0; } if (start) { len = sizeof(ngx_flv_header) - 1 + len - start; i = 0; } } } log->action = "sending flv to client"; r->headers_out.status = NGX_HTTP_OK; r->headers_out.content_length_n = len; r->headers_out.last_modified_time = of.mtime; if (ngx_http_set_etag(r) != NGX_OK) { return NGX_HTTP_INTERNAL_SERVER_ERROR; } if (ngx_http_set_content_type(r) != NGX_OK) { return NGX_HTTP_INTERNAL_SERVER_ERROR; } if (i == 0) { b = ngx_calloc_buf(r->pool); if (b == NULL) { return NGX_HTTP_INTERNAL_SERVER_ERROR; } b->pos = ngx_flv_header; b->last = ngx_flv_header + sizeof(ngx_flv_header) - 1; b->memory = 1; out[0].buf = b; out[0].next = &out[1]; } b = ngx_calloc_buf(r->pool); if (b == NULL) { return NGX_HTTP_INTERNAL_SERVER_ERROR; } b->file = ngx_pcalloc(r->pool, sizeof(ngx_file_t)); if (b->file == NULL) { return NGX_HTTP_INTERNAL_SERVER_ERROR; } r->allow_ranges = 1; rc = ngx_http_send_header(r); if (rc == NGX_ERROR || rc > NGX_OK || r->header_only) { return rc; } b->file_pos = start; b->file_last = of.size; b->in_file = b->file_last ? 1: 0; b->last_buf = (r == r->main) ? 1 : 0; b->last_in_chain = 1; b->file->fd = of.fd; b->file->name = path; b->file->log = log; b->file->directio = of.is_directio; out[1].buf = b; out[1].next = NULL; return ngx_http_output_filter(r, &out[i]); } static char * ngx_http_flv(ngx_conf_t *cf, ngx_command_t *cmd, void *conf) { ngx_http_core_loc_conf_t *clcf; clcf = ngx_http_conf_get_module_loc_conf(cf, ngx_http_core_module); clcf->handler = ngx_http_flv_handler; return NGX_CONF_OK; }