对于ModSecurity-nginx源代码的阅读

2 年 ago

新, 韵

5 minutes

首先

我已经写了一篇关于阅读ModSecurity-nginx源代码的文章。与Apache的模块类似，我认为Nginx也是通过钩子与之连接。我目前的理解就是这个水平。我将从Nginx和libmodsecurity.so.3.0.6的连接器的源代码开始阅读。由于连接器是接受Nginx钩子的部分，所以我想这应该会比较容易理解。

Nginx的挂钩阶段(Nginx de guà jiē

我认为我们可以了解在哪个阶段ModSecurity的处理程序被调用。

NGX_HTTP_LOG_PHASE

Nginx模块的结构体

ngx_http_core_main_conf_t

暂时先在Nginx的钩子阶段尝试进行grep。

看起来，已经注册了NGX_HTTP_REWRITE_PHASE、NGX_HTTP_PREACCESS_PHASE和NGX_HTTP_LOG_PHASE的处理程序。

$ grep NGX_HTTP_ /home/ec2-user/download/ModSecurity-nginx/src/* | grep _PHASE
/home/ec2-user/download/ModSecurity-nginx/src/ngx_http_modsecurity_module.c:     * NGX_HTTP_FIND_CONFIG_PHASE. it does not seems to
/home/ec2-user/download/ModSecurity-nginx/src/ngx_http_modsecurity_module.c:     * TODO: check if we can hook prior to NGX_HTTP_REWRITE_PHASE phase.
/home/ec2-user/download/ModSecurity-nginx/src/ngx_http_modsecurity_module.c:    h_rewrite = ngx_array_push(&cmcf->phases[NGX_HTTP_REWRITE_PHASE].handlers);
/home/ec2-user/download/ModSecurity-nginx/src/ngx_http_modsecurity_module.c:        dd("Not able to create a new NGX_HTTP_REWRITE_PHASE handle");
/home/ec2-user/download/ModSecurity-nginx/src/ngx_http_modsecurity_module.c:    h_preaccess = ngx_array_push(&cmcf->phases[NGX_HTTP_PREACCESS_PHASE].handlers);
/home/ec2-user/download/ModSecurity-nginx/src/ngx_http_modsecurity_module.c:        dd("Not able to create a new NGX_HTTP_PREACCESS_PHASE handle");
/home/ec2-user/download/ModSecurity-nginx/src/ngx_http_modsecurity_module.c:    h_log = ngx_array_push(&cmcf->phases[NGX_HTTP_LOG_PHASE].handlers);
/home/ec2-user/download/ModSecurity-nginx/src/ngx_http_modsecurity_module.c:        dd("Not able to create a new NGX_HTTP_LOG_PHASE handle");
/home/ec2-user/download/ModSecurity-nginx/src/ngx_http_modsecurity_rewrite.c:         * we have to hook into NGX_HTTP_FIND_CONFIG_PHASE, it seems to be the

尝试在Nginx模块的结构体中使用grep。

$ grep ngx_http_module_t  /home/ec2-user/download/ModSecurity-nginx/src/*
/home/ec2-user/download/ModSecurity-nginx/src/ngx_http_modsecurity_module.c:static ngx_http_module_t ngx_http_modsecurity_ctx = {
$ grep ngx_http_handler_pt /home/ec2-user/download/ModSecurity-nginx/src/*
/home/ec2-user/download/ModSecurity-nginx/src/ngx_http_modsecurity_module.c:    ngx_http_handler_pt *h_rewrite;
/home/ec2-user/download/ModSecurity-nginx/src/ngx_http_modsecurity_module.c:    ngx_http_handler_pt *h_preaccess;
/home/ec2-user/download/ModSecurity-nginx/src/ngx_http_modsecurity_module.c:    ngx_http_handler_pt *h_log;
$ grep ngx_http_core_main_conf_t  /home/ec2-user/download/ModSecurity-nginx/src/*
/home/ec2-user/download/ModSecurity-nginx/src/ngx_http_modsecurity_module.c:    ngx_http_core_main_conf_t *cmcf;

ModSecurity的初始化

static ngx_int_t
ngx_http_modsecurity_init(ngx_conf_t *cf)
{
    ngx_http_handler_pt *h_rewrite;
    ngx_http_handler_pt *h_preaccess;
    ngx_http_handler_pt *h_log;
    ngx_http_core_main_conf_t *cmcf;
    int rc = 0;

    cmcf = ngx_http_conf_get_module_main_conf(cf, ngx_http_core_module);
    if (cmcf == NULL)
    {
        dd("We are not sure how this returns, NGINX doesn't seem to think it will ever be null");
        return NGX_ERROR;
    }
省略
    h_rewrite = ngx_array_push(&cmcf->phases[NGX_HTTP_REWRITE_PHASE].handlers);
    if (h_rewrite == NULL)
    {
        dd("Not able to create a new NGX_HTTP_REWRITE_PHASE handle");
        return NGX_ERROR;
    }
    *h_rewrite = ngx_http_modsecurity_rewrite_handler;  ←REWRITEフェーズのハンドラ登録
省略
    h_preaccess = ngx_array_push(&cmcf->phases[NGX_HTTP_PREACCESS_PHASE].handlers);
    if (h_preaccess == NULL)
    {
        dd("Not able to create a new NGX_HTTP_PREACCESS_PHASE handle");
        return NGX_ERROR;
    }
    *h_preaccess = ngx_http_modsecurity_pre_access_handler;　←PREACCESSフェーズのハンドラ登録
省略
    h_log = ngx_array_push(&cmcf->phases[NGX_HTTP_LOG_PHASE].handlers);
    if (h_log == NULL)
    {
        dd("Not able to create a new NGX_HTTP_LOG_PHASE handle");
        return NGX_ERROR;
    }
    *h_log = ngx_http_modsecurity_log_handler; ←LOGフェーズのハンドラ登録

用grep在已注册的处理程序名称下进行搜索。

$ grep ngx_http_modsecurity_rewrite_handler /home/ec2-user/download/ModSecurity-nginx/src/*
/home/ec2-user/download/ModSecurity-nginx/src/ngx_http_modsecurity_common.h:ngx_int_t ngx_http_modsecurity_rewrite_handler(ngx_http_request_t *r);
/home/ec2-user/download/ModSecurity-nginx/src/ngx_http_modsecurity_module.c:    *h_rewrite = ngx_http_modsecurity_rewrite_handler;
/home/ec2-user/download/ModSecurity-nginx/src/ngx_http_modsecurity_rewrite.c:ngx_http_modsecurity_rewrite_handler(ngx_http_request_t *r)

$ grep ngx_http_modsecurity_pre_access_handler /home/ec2-user/download/ModSecurity-nginx/src/*
/home/ec2-user/download/ModSecurity-nginx/src/ngx_http_modsecurity_common.h:ngx_int_t ngx_http_modsecurity_pre_access_handler(ngx_http_request_t *r);
/home/ec2-user/download/ModSecurity-nginx/src/ngx_http_modsecurity_module.c:    *h_preaccess = ngx_http_modsecurity_pre_access_handler;
/home/ec2-user/download/ModSecurity-nginx/src/ngx_http_modsecurity_pre_access.c:ngx_http_modsecurity_pre_access_handler(ngx_http_request_t *r)

$ grep ngx_http_modsecurity_log_handler /home/ec2-user/download/ModSecurity-nginx/src/*
/home/ec2-user/download/ModSecurity-nginx/src/ngx_http_modsecurity_common.h:ngx_int_t ngx_http_modsecurity_log_handler(ngx_http_request_t *r);
/home/ec2-user/download/ModSecurity-nginx/src/ngx_http_modsecurity_log.c:ngx_http_modsecurity_log_handler(ngx_http_request_t *r)
/home/ec2-user/download/ModSecurity-nginx/src/ngx_http_modsecurity_module.c:            ngx_http_modsecurity_log_handler(r);
/home/ec2-user/download/ModSecurity-nginx/src/ngx_http_modsecurity_module.c:    *h_log = ngx_http_modsecurity_log_handler;

首先