Mercurial > hg > nginx
view src/http/modules/ngx_http_not_modified_filter_module.c @ 7629:f47f7d3d1bfa
Mp4: fixed possible chunk offset overflow.
In "co64" atom chunk start offset is a 64-bit unsigned integer. When trimming
the "mdat" atom, chunk offsets are casted to off_t values which are typically
64-bit signed integers. A specially crafted mp4 file with huge chunk offsets
may lead to off_t overflow and result in negative trim boundaries.
The consequences of the overflow are:
- Incorrect Content-Length header value in the response.
- Negative left boundary of the response file buffer holding the trimmed "mdat".
This leads to pread()/sendfile() errors followed by closing the client
connection.
On rare systems where off_t is a 32-bit integer, this scenario is also feasible
with the "stco" atom.
The fix is to add checks which make sure data chunks referenced by each track
are within the mp4 file boundaries. Additionally a few more checks are added to
ensure mp4 file consistency and log errors.
author | Roman Arutyunyan <arut@nginx.com> |
---|---|
date | Wed, 26 Feb 2020 15:10:46 +0300 |
parents | 8b6fa4842133 |
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> static ngx_uint_t ngx_http_test_if_unmodified(ngx_http_request_t *r); static ngx_uint_t ngx_http_test_if_modified(ngx_http_request_t *r); static ngx_uint_t ngx_http_test_if_match(ngx_http_request_t *r, ngx_table_elt_t *header, ngx_uint_t weak); static ngx_int_t ngx_http_not_modified_filter_init(ngx_conf_t *cf); static ngx_http_module_t ngx_http_not_modified_filter_module_ctx = { NULL, /* preconfiguration */ ngx_http_not_modified_filter_init, /* 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_not_modified_filter_module = { NGX_MODULE_V1, &ngx_http_not_modified_filter_module_ctx, /* module context */ NULL, /* 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_http_output_header_filter_pt ngx_http_next_header_filter; static ngx_int_t ngx_http_not_modified_header_filter(ngx_http_request_t *r) { if (r->headers_out.status != NGX_HTTP_OK || r != r->main || r->disable_not_modified) { return ngx_http_next_header_filter(r); } if (r->headers_in.if_unmodified_since && !ngx_http_test_if_unmodified(r)) { return ngx_http_filter_finalize_request(r, NULL, NGX_HTTP_PRECONDITION_FAILED); } if (r->headers_in.if_match && !ngx_http_test_if_match(r, r->headers_in.if_match, 0)) { return ngx_http_filter_finalize_request(r, NULL, NGX_HTTP_PRECONDITION_FAILED); } if (r->headers_in.if_modified_since || r->headers_in.if_none_match) { if (r->headers_in.if_modified_since && ngx_http_test_if_modified(r)) { return ngx_http_next_header_filter(r); } if (r->headers_in.if_none_match && !ngx_http_test_if_match(r, r->headers_in.if_none_match, 1)) { return ngx_http_next_header_filter(r); } /* not modified */ r->headers_out.status = NGX_HTTP_NOT_MODIFIED; r->headers_out.status_line.len = 0; r->headers_out.content_type.len = 0; ngx_http_clear_content_length(r); ngx_http_clear_accept_ranges(r); if (r->headers_out.content_encoding) { r->headers_out.content_encoding->hash = 0; r->headers_out.content_encoding = NULL; } return ngx_http_next_header_filter(r); } return ngx_http_next_header_filter(r); } static ngx_uint_t ngx_http_test_if_unmodified(ngx_http_request_t *r) { time_t iums; if (r->headers_out.last_modified_time == (time_t) -1) { return 0; } iums = ngx_parse_http_time(r->headers_in.if_unmodified_since->value.data, r->headers_in.if_unmodified_since->value.len); ngx_log_debug2(NGX_LOG_DEBUG_HTTP, r->connection->log, 0, "http iums:%T lm:%T", iums, r->headers_out.last_modified_time); if (iums >= r->headers_out.last_modified_time) { return 1; } return 0; } static ngx_uint_t ngx_http_test_if_modified(ngx_http_request_t *r) { time_t ims; ngx_http_core_loc_conf_t *clcf; if (r->headers_out.last_modified_time == (time_t) -1) { return 1; } clcf = ngx_http_get_module_loc_conf(r, ngx_http_core_module); if (clcf->if_modified_since == NGX_HTTP_IMS_OFF) { return 1; } ims = ngx_parse_http_time(r->headers_in.if_modified_since->value.data, r->headers_in.if_modified_since->value.len); ngx_log_debug2(NGX_LOG_DEBUG_HTTP, r->connection->log, 0, "http ims:%T lm:%T", ims, r->headers_out.last_modified_time); if (ims == r->headers_out.last_modified_time) { return 0; } if (clcf->if_modified_since == NGX_HTTP_IMS_EXACT || ims < r->headers_out.last_modified_time) { return 1; } return 0; } static ngx_uint_t ngx_http_test_if_match(ngx_http_request_t *r, ngx_table_elt_t *header, ngx_uint_t weak) { u_char *start, *end, ch; ngx_str_t etag, *list; list = &header->value; if (list->len == 1 && list->data[0] == '*') { return 1; } if (r->headers_out.etag == NULL) { return 0; } etag = r->headers_out.etag->value; ngx_log_debug2(NGX_LOG_DEBUG_HTTP, r->connection->log, 0, "http im:\"%V\" etag:%V", list, &etag); if (weak && etag.len > 2 && etag.data[0] == 'W' && etag.data[1] == '/') { etag.len -= 2; etag.data += 2; } start = list->data; end = list->data + list->len; while (start < end) { if (weak && end - start > 2 && start[0] == 'W' && start[1] == '/') { start += 2; } if (etag.len > (size_t) (end - start)) { return 0; } if (ngx_strncmp(start, etag.data, etag.len) != 0) { goto skip; } start += etag.len; while (start < end) { ch = *start; if (ch == ' ' || ch == '\t') { start++; continue; } break; } if (start == end || *start == ',') { return 1; } skip: while (start < end && *start != ',') { start++; } while (start < end) { ch = *start; if (ch == ' ' || ch == '\t' || ch == ',') { start++; continue; } break; } } return 0; } static ngx_int_t ngx_http_not_modified_filter_init(ngx_conf_t *cf) { ngx_http_next_header_filter = ngx_http_top_header_filter; ngx_http_top_header_filter = ngx_http_not_modified_header_filter; return NGX_OK; }