view src/stream/ngx_stream_limit_conn_module.c @ 7360:8f25a44d9add

SSL: logging level of "no suitable key share". The "no suitable key share" errors are reported by OpenSSL 1.1.1 when using TLSv1.3 if there are no shared groups (that is, elliptic curves). In particular, it is easy enough to trigger by using only a single curve in ssl_ecdh_curve: ssl_ecdh_curve secp384r1; and using a different curve in the client: openssl s_client -connect 127.0.0.1:443 -curves prime256v1 On the client side it is seen as "sslv3 alert handshake failure", "SSL alert number 40": 0:error:14094410:SSL routines:ssl3_read_bytes:sslv3 alert handshake failure:ssl/record/rec_layer_s3.c:1528:SSL alert number 40 It can be also triggered with default ssl_ecdh_curve by using a curve which is not in the default list (X25519, prime256v1, X448, secp521r1, secp384r1): openssl s_client -connect 127.0.0.1:8443 -curves brainpoolP512r1 Given that many clients hardcode prime256v1, these errors might become a common problem with TLSv1.3 if ssl_ecdh_curve is redefined. Previously this resulted in not using ECDH with such clients, but with TLSv1.3 it is no longer possible and will result in a handshake failure. The SSL_R_NO_SHARED_GROUP error is what BoringSSL returns in the same situation. Seen at: https://serverfault.com/questions/932102/nginx-ssl-handshake-error-no-suitable-key-share
author Maxim Dounin <mdounin@mdounin.ru>
date Tue, 25 Sep 2018 13:59:53 +0300
parents 3908156a51fa
children 359b0ea2b067
line wrap: on
line source


/*
 * Copyright (C) Igor Sysoev
 * Copyright (C) Nginx, Inc.
 */


#include <ngx_config.h>
#include <ngx_core.h>
#include <ngx_stream.h>


typedef struct {
    u_char                       color;
    u_char                       len;
    u_short                      conn;
    u_char                       data[1];
} ngx_stream_limit_conn_node_t;


typedef struct {
    ngx_shm_zone_t              *shm_zone;
    ngx_rbtree_node_t           *node;
} ngx_stream_limit_conn_cleanup_t;


typedef struct {
    ngx_rbtree_t                *rbtree;
    ngx_stream_complex_value_t   key;
} ngx_stream_limit_conn_ctx_t;


typedef struct {
    ngx_shm_zone_t              *shm_zone;
    ngx_uint_t                   conn;
} ngx_stream_limit_conn_limit_t;


typedef struct {
    ngx_array_t                  limits;
    ngx_uint_t                   log_level;
} ngx_stream_limit_conn_conf_t;


static ngx_rbtree_node_t *ngx_stream_limit_conn_lookup(ngx_rbtree_t *rbtree,
    ngx_str_t *key, uint32_t hash);
static void ngx_stream_limit_conn_cleanup(void *data);
static ngx_inline void ngx_stream_limit_conn_cleanup_all(ngx_pool_t *pool);

static void *ngx_stream_limit_conn_create_conf(ngx_conf_t *cf);
static char *ngx_stream_limit_conn_merge_conf(ngx_conf_t *cf, void *parent,
    void *child);
static char *ngx_stream_limit_conn_zone(ngx_conf_t *cf, ngx_command_t *cmd,
    void *conf);
static char *ngx_stream_limit_conn(ngx_conf_t *cf, ngx_command_t *cmd,
    void *conf);
static ngx_int_t ngx_stream_limit_conn_init(ngx_conf_t *cf);


static ngx_conf_enum_t  ngx_stream_limit_conn_log_levels[] = {
    { ngx_string("info"), NGX_LOG_INFO },
    { ngx_string("notice"), NGX_LOG_NOTICE },
    { ngx_string("warn"), NGX_LOG_WARN },
    { ngx_string("error"), NGX_LOG_ERR },
    { ngx_null_string, 0 }
};


static ngx_command_t  ngx_stream_limit_conn_commands[] = {

    { ngx_string("limit_conn_zone"),
      NGX_STREAM_MAIN_CONF|NGX_CONF_TAKE2,
      ngx_stream_limit_conn_zone,
      0,
      0,
      NULL },

    { ngx_string("limit_conn"),
      NGX_STREAM_MAIN_CONF|NGX_STREAM_SRV_CONF|NGX_CONF_TAKE2,
      ngx_stream_limit_conn,
      NGX_STREAM_SRV_CONF_OFFSET,
      0,
      NULL },

    { ngx_string("limit_conn_log_level"),
      NGX_STREAM_MAIN_CONF|NGX_STREAM_SRV_CONF|NGX_CONF_TAKE1,
      ngx_conf_set_enum_slot,
      NGX_STREAM_SRV_CONF_OFFSET,
      offsetof(ngx_stream_limit_conn_conf_t, log_level),
      &ngx_stream_limit_conn_log_levels },

      ngx_null_command
};


static ngx_stream_module_t  ngx_stream_limit_conn_module_ctx = {
    NULL,                                  /* preconfiguration */
    ngx_stream_limit_conn_init,            /* postconfiguration */

    NULL,                                  /* create main configuration */
    NULL,                                  /* init main configuration */

    ngx_stream_limit_conn_create_conf,     /* create server configuration */
    ngx_stream_limit_conn_merge_conf       /* merge server configuration */
};


ngx_module_t  ngx_stream_limit_conn_module = {
    NGX_MODULE_V1,
    &ngx_stream_limit_conn_module_ctx,     /* module context */
    ngx_stream_limit_conn_commands,        /* module directives */
    NGX_STREAM_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_stream_limit_conn_handler(ngx_stream_session_t *s)
{
    size_t                            n;
    uint32_t                          hash;
    ngx_str_t                         key;
    ngx_uint_t                        i;
    ngx_slab_pool_t                  *shpool;
    ngx_rbtree_node_t                *node;
    ngx_pool_cleanup_t               *cln;
    ngx_stream_limit_conn_ctx_t      *ctx;
    ngx_stream_limit_conn_node_t     *lc;
    ngx_stream_limit_conn_conf_t     *lccf;
    ngx_stream_limit_conn_limit_t    *limits;
    ngx_stream_limit_conn_cleanup_t  *lccln;

    lccf = ngx_stream_get_module_srv_conf(s, ngx_stream_limit_conn_module);
    limits = lccf->limits.elts;

    for (i = 0; i < lccf->limits.nelts; i++) {
        ctx = limits[i].shm_zone->data;

        if (ngx_stream_complex_value(s, &ctx->key, &key) != NGX_OK) {
            return NGX_ERROR;
        }

        if (key.len == 0) {
            continue;
        }

        if (key.len > 255) {
            ngx_log_error(NGX_LOG_ERR, s->connection->log, 0,
                          "the value of the \"%V\" key "
                          "is more than 255 bytes: \"%V\"",
                          &ctx->key.value, &key);
            continue;
        }

        hash = ngx_crc32_short(key.data, key.len);

        shpool = (ngx_slab_pool_t *) limits[i].shm_zone->shm.addr;

        ngx_shmtx_lock(&shpool->mutex);

        node = ngx_stream_limit_conn_lookup(ctx->rbtree, &key, hash);

        if (node == NULL) {

            n = offsetof(ngx_rbtree_node_t, color)
                + offsetof(ngx_stream_limit_conn_node_t, data)
                + key.len;

            node = ngx_slab_alloc_locked(shpool, n);

            if (node == NULL) {
                ngx_shmtx_unlock(&shpool->mutex);
                ngx_stream_limit_conn_cleanup_all(s->connection->pool);
                return NGX_STREAM_SERVICE_UNAVAILABLE;
            }

            lc = (ngx_stream_limit_conn_node_t *) &node->color;

            node->key = hash;
            lc->len = (u_char) key.len;
            lc->conn = 1;
            ngx_memcpy(lc->data, key.data, key.len);

            ngx_rbtree_insert(ctx->rbtree, node);

        } else {

            lc = (ngx_stream_limit_conn_node_t *) &node->color;

            if ((ngx_uint_t) lc->conn >= limits[i].conn) {

                ngx_shmtx_unlock(&shpool->mutex);

                ngx_log_error(lccf->log_level, s->connection->log, 0,
                              "limiting connections by zone \"%V\"",
                              &limits[i].shm_zone->shm.name);

                ngx_stream_limit_conn_cleanup_all(s->connection->pool);
                return NGX_STREAM_SERVICE_UNAVAILABLE;
            }

            lc->conn++;
        }

        ngx_log_debug2(NGX_LOG_DEBUG_STREAM, s->connection->log, 0,
                       "limit conn: %08Xi %d", node->key, lc->conn);

        ngx_shmtx_unlock(&shpool->mutex);

        cln = ngx_pool_cleanup_add(s->connection->pool,
                                   sizeof(ngx_stream_limit_conn_cleanup_t));
        if (cln == NULL) {
            return NGX_ERROR;
        }

        cln->handler = ngx_stream_limit_conn_cleanup;
        lccln = cln->data;

        lccln->shm_zone = limits[i].shm_zone;
        lccln->node = node;
    }

    return NGX_DECLINED;
}


static void
ngx_stream_limit_conn_rbtree_insert_value(ngx_rbtree_node_t *temp,
    ngx_rbtree_node_t *node, ngx_rbtree_node_t *sentinel)
{
    ngx_rbtree_node_t             **p;
    ngx_stream_limit_conn_node_t   *lcn, *lcnt;

    for ( ;; ) {

        if (node->key < temp->key) {

            p = &temp->left;

        } else if (node->key > temp->key) {

            p = &temp->right;

        } else { /* node->key == temp->key */

            lcn = (ngx_stream_limit_conn_node_t *) &node->color;
            lcnt = (ngx_stream_limit_conn_node_t *) &temp->color;

            p = (ngx_memn2cmp(lcn->data, lcnt->data, lcn->len, lcnt->len) < 0)
                ? &temp->left : &temp->right;
        }

        if (*p == sentinel) {
            break;
        }

        temp = *p;
    }

    *p = node;
    node->parent = temp;
    node->left = sentinel;
    node->right = sentinel;
    ngx_rbt_red(node);
}


static ngx_rbtree_node_t *
ngx_stream_limit_conn_lookup(ngx_rbtree_t *rbtree, ngx_str_t *key,
    uint32_t hash)
{
    ngx_int_t                      rc;
    ngx_rbtree_node_t             *node, *sentinel;
    ngx_stream_limit_conn_node_t  *lcn;

    node = rbtree->root;
    sentinel = rbtree->sentinel;

    while (node != sentinel) {

        if (hash < node->key) {
            node = node->left;
            continue;
        }

        if (hash > node->key) {
            node = node->right;
            continue;
        }

        /* hash == node->key */

        lcn = (ngx_stream_limit_conn_node_t *) &node->color;

        rc = ngx_memn2cmp(key->data, lcn->data, key->len, (size_t) lcn->len);

        if (rc == 0) {
            return node;
        }

        node = (rc < 0) ? node->left : node->right;
    }

    return NULL;
}


static void
ngx_stream_limit_conn_cleanup(void *data)
{
    ngx_stream_limit_conn_cleanup_t  *lccln = data;

    ngx_slab_pool_t               *shpool;
    ngx_rbtree_node_t             *node;
    ngx_stream_limit_conn_ctx_t   *ctx;
    ngx_stream_limit_conn_node_t  *lc;

    ctx = lccln->shm_zone->data;
    shpool = (ngx_slab_pool_t *) lccln->shm_zone->shm.addr;
    node = lccln->node;
    lc = (ngx_stream_limit_conn_node_t *) &node->color;

    ngx_shmtx_lock(&shpool->mutex);

    ngx_log_debug2(NGX_LOG_DEBUG_STREAM, lccln->shm_zone->shm.log, 0,
                   "limit conn cleanup: %08Xi %d", node->key, lc->conn);

    lc->conn--;

    if (lc->conn == 0) {
        ngx_rbtree_delete(ctx->rbtree, node);
        ngx_slab_free_locked(shpool, node);
    }

    ngx_shmtx_unlock(&shpool->mutex);
}


static ngx_inline void
ngx_stream_limit_conn_cleanup_all(ngx_pool_t *pool)
{
    ngx_pool_cleanup_t  *cln;

    cln = pool->cleanup;

    while (cln && cln->handler == ngx_stream_limit_conn_cleanup) {
        ngx_stream_limit_conn_cleanup(cln->data);
        cln = cln->next;
    }

    pool->cleanup = cln;
}


static ngx_int_t
ngx_stream_limit_conn_init_zone(ngx_shm_zone_t *shm_zone, void *data)
{
    ngx_stream_limit_conn_ctx_t  *octx = data;

    size_t                        len;
    ngx_slab_pool_t              *shpool;
    ngx_rbtree_node_t            *sentinel;
    ngx_stream_limit_conn_ctx_t  *ctx;

    ctx = shm_zone->data;

    if (octx) {
        if (ctx->key.value.len != octx->key.value.len
            || ngx_strncmp(ctx->key.value.data, octx->key.value.data,
                           ctx->key.value.len)
               != 0)
        {
            ngx_log_error(NGX_LOG_EMERG, shm_zone->shm.log, 0,
                          "limit_conn_zone \"%V\" uses the \"%V\" key "
                          "while previously it used the \"%V\" key",
                          &shm_zone->shm.name, &ctx->key.value,
                          &octx->key.value);
            return NGX_ERROR;
        }

        ctx->rbtree = octx->rbtree;

        return NGX_OK;
    }

    shpool = (ngx_slab_pool_t *) shm_zone->shm.addr;

    if (shm_zone->shm.exists) {
        ctx->rbtree = shpool->data;

        return NGX_OK;
    }

    ctx->rbtree = ngx_slab_alloc(shpool, sizeof(ngx_rbtree_t));
    if (ctx->rbtree == NULL) {
        return NGX_ERROR;
    }

    shpool->data = ctx->rbtree;

    sentinel = ngx_slab_alloc(shpool, sizeof(ngx_rbtree_node_t));
    if (sentinel == NULL) {
        return NGX_ERROR;
    }

    ngx_rbtree_init(ctx->rbtree, sentinel,
                    ngx_stream_limit_conn_rbtree_insert_value);

    len = sizeof(" in limit_conn_zone \"\"") + shm_zone->shm.name.len;

    shpool->log_ctx = ngx_slab_alloc(shpool, len);
    if (shpool->log_ctx == NULL) {
        return NGX_ERROR;
    }

    ngx_sprintf(shpool->log_ctx, " in limit_conn_zone \"%V\"%Z",
                &shm_zone->shm.name);

    return NGX_OK;
}


static void *
ngx_stream_limit_conn_create_conf(ngx_conf_t *cf)
{
    ngx_stream_limit_conn_conf_t  *conf;

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

    /*
     * set by ngx_pcalloc():
     *
     *     conf->limits.elts = NULL;
     */

    conf->log_level = NGX_CONF_UNSET_UINT;

    return conf;
}


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

    if (conf->limits.elts == NULL) {
        conf->limits = prev->limits;
    }

    ngx_conf_merge_uint_value(conf->log_level, prev->log_level, NGX_LOG_ERR);

    return NGX_CONF_OK;
}


static char *
ngx_stream_limit_conn_zone(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
{
    u_char                              *p;
    ssize_t                              size;
    ngx_str_t                           *value, name, s;
    ngx_uint_t                           i;
    ngx_shm_zone_t                      *shm_zone;
    ngx_stream_limit_conn_ctx_t         *ctx;
    ngx_stream_compile_complex_value_t   ccv;

    value = cf->args->elts;

    ctx = ngx_pcalloc(cf->pool, sizeof(ngx_stream_limit_conn_ctx_t));
    if (ctx == NULL) {
        return NGX_CONF_ERROR;
    }

    ngx_memzero(&ccv, sizeof(ngx_stream_compile_complex_value_t));

    ccv.cf = cf;
    ccv.value = &value[1];
    ccv.complex_value = &ctx->key;

    if (ngx_stream_compile_complex_value(&ccv) != NGX_OK) {
        return NGX_CONF_ERROR;
    }

    size = 0;
    name.len = 0;

    for (i = 2; i < cf->args->nelts; i++) {

        if (ngx_strncmp(value[i].data, "zone=", 5) == 0) {

            name.data = value[i].data + 5;

            p = (u_char *) ngx_strchr(name.data, ':');

            if (p == NULL) {
                ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                                   "invalid zone size \"%V\"", &value[i]);
                return NGX_CONF_ERROR;
            }

            name.len = p - name.data;

            s.data = p + 1;
            s.len = value[i].data + value[i].len - s.data;

            size = ngx_parse_size(&s);

            if (size == NGX_ERROR) {
                ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                                   "invalid zone size \"%V\"", &value[i]);
                return NGX_CONF_ERROR;
            }

            if (size < (ssize_t) (8 * ngx_pagesize)) {
                ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                                   "zone \"%V\" is too small", &value[i]);
                return NGX_CONF_ERROR;
            }

            continue;
        }

        ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                           "invalid parameter \"%V\"", &value[i]);
        return NGX_CONF_ERROR;
    }

    if (name.len == 0) {
        ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                           "\"%V\" must have \"zone\" parameter",
                           &cmd->name);
        return NGX_CONF_ERROR;
    }

    shm_zone = ngx_shared_memory_add(cf, &name, size,
                                     &ngx_stream_limit_conn_module);
    if (shm_zone == NULL) {
        return NGX_CONF_ERROR;
    }

    if (shm_zone->data) {
        ctx = shm_zone->data;

        ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                           "%V \"%V\" is already bound to key \"%V\"",
                           &cmd->name, &name, &ctx->key.value);
        return NGX_CONF_ERROR;
    }

    shm_zone->init = ngx_stream_limit_conn_init_zone;
    shm_zone->data = ctx;

    return NGX_CONF_OK;
}


static char *
ngx_stream_limit_conn(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
{
    ngx_shm_zone_t                 *shm_zone;
    ngx_stream_limit_conn_conf_t   *lccf = conf;
    ngx_stream_limit_conn_limit_t  *limit, *limits;

    ngx_str_t   *value;
    ngx_int_t    n;
    ngx_uint_t   i;

    value = cf->args->elts;

    shm_zone = ngx_shared_memory_add(cf, &value[1], 0,
                                     &ngx_stream_limit_conn_module);
    if (shm_zone == NULL) {
        return NGX_CONF_ERROR;
    }

    limits = lccf->limits.elts;

    if (limits == NULL) {
        if (ngx_array_init(&lccf->limits, cf->pool, 1,
                           sizeof(ngx_stream_limit_conn_limit_t))
            != NGX_OK)
        {
            return NGX_CONF_ERROR;
        }
    }

    for (i = 0; i < lccf->limits.nelts; i++) {
        if (shm_zone == limits[i].shm_zone) {
            return "is duplicate";
        }
    }

    n = ngx_atoi(value[2].data, value[2].len);
    if (n <= 0) {
        ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                           "invalid number of connections \"%V\"", &value[2]);
        return NGX_CONF_ERROR;
    }

    if (n > 65535) {
        ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                           "connection limit must be less 65536");
        return NGX_CONF_ERROR;
    }

    limit = ngx_array_push(&lccf->limits);
    if (limit == NULL) {
        return NGX_CONF_ERROR;
    }

    limit->conn = n;
    limit->shm_zone = shm_zone;

    return NGX_CONF_OK;
}


static ngx_int_t
ngx_stream_limit_conn_init(ngx_conf_t *cf)
{
    ngx_stream_handler_pt        *h;
    ngx_stream_core_main_conf_t  *cmcf;

    cmcf = ngx_stream_conf_get_module_main_conf(cf, ngx_stream_core_module);

    h = ngx_array_push(&cmcf->phases[NGX_STREAM_PREACCESS_PHASE].handlers);
    if (h == NULL) {
        return NGX_ERROR;
    }

    *h = ngx_stream_limit_conn_handler;

    return NGX_OK;
}