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view src/http/ngx_http_spdy_module.c @ 6359:dac6eda40475 stable-1.8

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Resolver: fixed use-after-free memory accesses with CNAME. When several requests were waiting for a response, then after getting a CNAME response only the last request's context had the name updated. Contexts of other requests had the wrong name. This name was used by ngx_resolve_name_done() to find the node to remove the request context from. When the name was wrong, the request could not be properly cancelled, its context was freed but stayed linked to the node's waiting list. This happened e.g. when the first request was aborted or timed out before the resolving completed. When it completed, this triggered a use-after-free memory access by calling ctx->handler of already freed request context. The bug manifests itself by "could not cancel <name> resolving" alerts in error_log. When a request was responded with a CNAME, the request context kept the pointer to the original node's rn->u.cname. If the original node expired before the resolving timed out or completed with an error, this would trigger a use-after-free memory access via ctx->name in ctx->handler(). The fix is to keep ctx->name unmodified. The name from context is no longer used by ngx_resolve_name_done(). Instead, we now keep the pointer to resolver node to which this request is linked. Keeping the original name intact also improves logging.
author Roman Arutyunyan <arut@nginx.com>
date Tue, 26 Jan 2016 16:46:59 +0300
parents 02ee639d18a8
children
line wrap: on
line source


/*
 * Copyright (C) Nginx, Inc.
 * Copyright (C) Valentin V. Bartenev
 */


#include <ngx_config.h>
#include <ngx_core.h>
#include <ngx_http.h>
#include <ngx_http_spdy_module.h>


static ngx_int_t ngx_http_spdy_add_variables(ngx_conf_t *cf);

static ngx_int_t ngx_http_spdy_variable(ngx_http_request_t *r,
    ngx_http_variable_value_t *v, uintptr_t data);
static ngx_int_t ngx_http_spdy_request_priority_variable(ngx_http_request_t *r,
    ngx_http_variable_value_t *v, uintptr_t data);

static ngx_int_t ngx_http_spdy_module_init(ngx_cycle_t *cycle);

static void *ngx_http_spdy_create_main_conf(ngx_conf_t *cf);
static char *ngx_http_spdy_init_main_conf(ngx_conf_t *cf, void *conf);
static void *ngx_http_spdy_create_srv_conf(ngx_conf_t *cf);
static char *ngx_http_spdy_merge_srv_conf(ngx_conf_t *cf, void *parent,
    void *child);
static void *ngx_http_spdy_create_loc_conf(ngx_conf_t *cf);
static char *ngx_http_spdy_merge_loc_conf(ngx_conf_t *cf, void *parent,
    void *child);

static char *ngx_http_spdy_recv_buffer_size(ngx_conf_t *cf, void *post,
    void *data);
static char *ngx_http_spdy_pool_size(ngx_conf_t *cf, void *post, void *data);
static char *ngx_http_spdy_streams_index_mask(ngx_conf_t *cf, void *post,
    void *data);
static char *ngx_http_spdy_chunk_size(ngx_conf_t *cf, void *post, void *data);


static ngx_conf_num_bounds_t  ngx_http_spdy_headers_comp_bounds = {
    ngx_conf_check_num_bounds, 0, 9
};

static ngx_conf_post_t  ngx_http_spdy_recv_buffer_size_post =
    { ngx_http_spdy_recv_buffer_size };
static ngx_conf_post_t  ngx_http_spdy_pool_size_post =
    { ngx_http_spdy_pool_size };
static ngx_conf_post_t  ngx_http_spdy_streams_index_mask_post =
    { ngx_http_spdy_streams_index_mask };
static ngx_conf_post_t  ngx_http_spdy_chunk_size_post =
    { ngx_http_spdy_chunk_size };


static ngx_command_t  ngx_http_spdy_commands[] = {

    { ngx_string("spdy_recv_buffer_size"),
      NGX_HTTP_MAIN_CONF|NGX_CONF_TAKE1,
      ngx_conf_set_size_slot,
      NGX_HTTP_MAIN_CONF_OFFSET,
      offsetof(ngx_http_spdy_main_conf_t, recv_buffer_size),
      &ngx_http_spdy_recv_buffer_size_post },

    { ngx_string("spdy_pool_size"),
      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_CONF_TAKE1,
      ngx_conf_set_size_slot,
      NGX_HTTP_SRV_CONF_OFFSET,
      offsetof(ngx_http_spdy_srv_conf_t, pool_size),
      &ngx_http_spdy_pool_size_post },

    { ngx_string("spdy_max_concurrent_streams"),
      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_CONF_TAKE1,
      ngx_conf_set_num_slot,
      NGX_HTTP_SRV_CONF_OFFSET,
      offsetof(ngx_http_spdy_srv_conf_t, concurrent_streams),
      NULL },

    { ngx_string("spdy_streams_index_size"),
      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_CONF_TAKE1,
      ngx_conf_set_num_slot,
      NGX_HTTP_SRV_CONF_OFFSET,
      offsetof(ngx_http_spdy_srv_conf_t, streams_index_mask),
      &ngx_http_spdy_streams_index_mask_post },

    { ngx_string("spdy_recv_timeout"),
      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_CONF_TAKE1,
      ngx_conf_set_msec_slot,
      NGX_HTTP_SRV_CONF_OFFSET,
      offsetof(ngx_http_spdy_srv_conf_t, recv_timeout),
      NULL },

    { ngx_string("spdy_keepalive_timeout"),
      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_CONF_TAKE1,
      ngx_conf_set_msec_slot,
      NGX_HTTP_SRV_CONF_OFFSET,
      offsetof(ngx_http_spdy_srv_conf_t, keepalive_timeout),
      NULL },

    { ngx_string("spdy_headers_comp"),
      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_CONF_TAKE1,
      ngx_conf_set_num_slot,
      NGX_HTTP_SRV_CONF_OFFSET,
      offsetof(ngx_http_spdy_srv_conf_t, headers_comp),
      &ngx_http_spdy_headers_comp_bounds },

    { ngx_string("spdy_chunk_size"),
      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_TAKE1,
      ngx_conf_set_size_slot,
      NGX_HTTP_LOC_CONF_OFFSET,
      offsetof(ngx_http_spdy_loc_conf_t, chunk_size),
      &ngx_http_spdy_chunk_size_post },

      ngx_null_command
};


static ngx_http_module_t  ngx_http_spdy_module_ctx = {
    ngx_http_spdy_add_variables,           /* preconfiguration */
    NULL,                                  /* postconfiguration */

    ngx_http_spdy_create_main_conf,        /* create main configuration */
    ngx_http_spdy_init_main_conf,          /* init main configuration */

    ngx_http_spdy_create_srv_conf,         /* create server configuration */
    ngx_http_spdy_merge_srv_conf,          /* merge server configuration */

    ngx_http_spdy_create_loc_conf,         /* create location configuration */
    ngx_http_spdy_merge_loc_conf           /* merge location configuration */
};


ngx_module_t  ngx_http_spdy_module = {
    NGX_MODULE_V1,
    &ngx_http_spdy_module_ctx,             /* module context */
    ngx_http_spdy_commands,                /* module directives */
    NGX_HTTP_MODULE,                       /* module type */
    NULL,                                  /* init master */
    ngx_http_spdy_module_init,             /* init module */
    NULL,                                  /* init process */
    NULL,                                  /* init thread */
    NULL,                                  /* exit thread */
    NULL,                                  /* exit process */
    NULL,                                  /* exit master */
    NGX_MODULE_V1_PADDING
};


static ngx_http_variable_t  ngx_http_spdy_vars[] = {

    { ngx_string("spdy"), NULL,
      ngx_http_spdy_variable, 0, 0, 0 },

    { ngx_string("spdy_request_priority"), NULL,
      ngx_http_spdy_request_priority_variable, 0, 0, 0 },

    { ngx_null_string, NULL, NULL, 0, 0, 0 }
};


static ngx_int_t
ngx_http_spdy_add_variables(ngx_conf_t *cf)
{
   ngx_http_variable_t  *var, *v;

    for (v = ngx_http_spdy_vars; v->name.len; v++) {
        var = ngx_http_add_variable(cf, &v->name, v->flags);
        if (var == NULL) {
            return NGX_ERROR;
        }

        var->get_handler = v->get_handler;
        var->data = v->data;
    }

    return NGX_OK;
}


static ngx_int_t
ngx_http_spdy_variable(ngx_http_request_t *r,
    ngx_http_variable_value_t *v, uintptr_t data)
{
    if (r->spdy_stream) {
        v->len = sizeof("3.1") - 1;
        v->valid = 1;
        v->no_cacheable = 0;
        v->not_found = 0;
        v->data = (u_char *) "3.1";

        return NGX_OK;
    }

    *v = ngx_http_variable_null_value;

    return NGX_OK;
}


static ngx_int_t
ngx_http_spdy_request_priority_variable(ngx_http_request_t *r,
    ngx_http_variable_value_t *v, uintptr_t data)
{
    if (r->spdy_stream) {
        v->len = 1;
        v->valid = 1;
        v->no_cacheable = 0;
        v->not_found = 0;

        v->data = ngx_pnalloc(r->pool, 1);
        if (v->data == NULL) {
            return NGX_ERROR;
        }

        v->data[0] = '0' + (u_char) r->spdy_stream->priority;

        return NGX_OK;
    }

    *v = ngx_http_variable_null_value;

    return NGX_OK;
}


static ngx_int_t
ngx_http_spdy_module_init(ngx_cycle_t *cycle)
{
    ngx_http_spdy_request_headers_init();

    return NGX_OK;
}


static void *
ngx_http_spdy_create_main_conf(ngx_conf_t *cf)
{
    ngx_http_spdy_main_conf_t  *smcf;

    smcf = ngx_pcalloc(cf->pool, sizeof(ngx_http_spdy_main_conf_t));
    if (smcf == NULL) {
        return NULL;
    }

    smcf->recv_buffer_size = NGX_CONF_UNSET_SIZE;

    return smcf;
}


static char *
ngx_http_spdy_init_main_conf(ngx_conf_t *cf, void *conf)
{
    ngx_http_spdy_main_conf_t *smcf = conf;

    ngx_conf_init_size_value(smcf->recv_buffer_size, 256 * 1024);

    return NGX_CONF_OK;
}


static void *
ngx_http_spdy_create_srv_conf(ngx_conf_t *cf)
{
    ngx_http_spdy_srv_conf_t  *sscf;

    sscf = ngx_pcalloc(cf->pool, sizeof(ngx_http_spdy_srv_conf_t));
    if (sscf == NULL) {
        return NULL;
    }

    sscf->pool_size = NGX_CONF_UNSET_SIZE;

    sscf->concurrent_streams = NGX_CONF_UNSET_UINT;
    sscf->streams_index_mask = NGX_CONF_UNSET_UINT;

    sscf->recv_timeout = NGX_CONF_UNSET_MSEC;
    sscf->keepalive_timeout = NGX_CONF_UNSET_MSEC;

    sscf->headers_comp = NGX_CONF_UNSET;

    return sscf;
}


static char *
ngx_http_spdy_merge_srv_conf(ngx_conf_t *cf, void *parent, void *child)
{
    ngx_http_spdy_srv_conf_t *prev = parent;
    ngx_http_spdy_srv_conf_t *conf = child;

    ngx_conf_merge_size_value(conf->pool_size, prev->pool_size, 4096);

    ngx_conf_merge_uint_value(conf->concurrent_streams,
                              prev->concurrent_streams, 100);

    ngx_conf_merge_uint_value(conf->streams_index_mask,
                              prev->streams_index_mask, 32 - 1);

    ngx_conf_merge_msec_value(conf->recv_timeout,
                              prev->recv_timeout, 30000);
    ngx_conf_merge_msec_value(conf->keepalive_timeout,
                              prev->keepalive_timeout, 180000);

    ngx_conf_merge_value(conf->headers_comp, prev->headers_comp, 0);

    return NGX_CONF_OK;
}


static void *
ngx_http_spdy_create_loc_conf(ngx_conf_t *cf)
{
    ngx_http_spdy_loc_conf_t  *slcf;

    slcf = ngx_pcalloc(cf->pool, sizeof(ngx_http_spdy_loc_conf_t));
    if (slcf == NULL) {
        return NULL;
    }

    slcf->chunk_size = NGX_CONF_UNSET_SIZE;

    return slcf;
}


static char *
ngx_http_spdy_merge_loc_conf(ngx_conf_t *cf, void *parent, void *child)
{
    ngx_http_spdy_loc_conf_t *prev = parent;
    ngx_http_spdy_loc_conf_t *conf = child;

    ngx_conf_merge_size_value(conf->chunk_size, prev->chunk_size, 8 * 1024);

    return NGX_CONF_OK;
}


static char *
ngx_http_spdy_recv_buffer_size(ngx_conf_t *cf, void *post, void *data)
{
    size_t *sp = data;

    if (*sp <= 2 * NGX_SPDY_STATE_BUFFER_SIZE) {
        return "value is too small";
    }

    return NGX_CONF_OK;
}


static char *
ngx_http_spdy_pool_size(ngx_conf_t *cf, void *post, void *data)
{
    size_t *sp = data;

    if (*sp < NGX_MIN_POOL_SIZE) {
        ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                           "the pool size must be no less than %uz",
                           NGX_MIN_POOL_SIZE);
        return NGX_CONF_ERROR;
    }

    if (*sp % NGX_POOL_ALIGNMENT) {
        ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                           "the pool size must be a multiple of %uz",
                           NGX_POOL_ALIGNMENT);
        return NGX_CONF_ERROR;
    }

    return NGX_CONF_OK;
}


static char *
ngx_http_spdy_streams_index_mask(ngx_conf_t *cf, void *post, void *data)
{
    ngx_uint_t *np = data;

    ngx_uint_t  mask;

    mask = *np - 1;

    if (*np == 0 || (*np & mask)) {
        return "must be a power of two";
    }

    *np = mask;

    return NGX_CONF_OK;
}


static char *
ngx_http_spdy_chunk_size(ngx_conf_t *cf, void *post, void *data)
{
    size_t *sp = data;

    if (*sp == 0) {
        ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                           "the spdy chunk size cannot be zero");
        return NGX_CONF_ERROR;
    }

    if (*sp > NGX_SPDY_MAX_FRAME_SIZE) {
        *sp = NGX_SPDY_MAX_FRAME_SIZE;
    }

    return NGX_CONF_OK;
}