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view src/mail/ngx_mail_ssl_module.c @ 7119:fef61d26da39

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Fixed buffer overread with unix sockets after accept(). Some OSes (notably macOS, NetBSD, and Solaris) allow unix socket addresses larger than struct sockaddr_un. Moreover, some of them (macOS, Solaris) return socklen of the socket address before it was truncated to fit the buffer provided. As such, on these systems socklen must not be used without additional check that it is within the buffer provided. Appropriate checks added to ngx_event_accept() (after accept()), ngx_event_recvmsg() (after recvmsg()), and ngx_set_inherited_sockets() (after getsockname()). We also obtain socket addresses via getsockname() in ngx_connection_local_sockaddr(), but it does not need any checks as it is only used for INET and INET6 sockets (as there can be no wildcard unix sockets).
author Maxim Dounin <mdounin@mdounin.ru>
date Wed, 04 Oct 2017 21:19:33 +0300
parents 08dc60979133
children 0d8c72ff62dd
line wrap: on
line source


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


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


#define NGX_DEFAULT_CIPHERS     "HIGH:!aNULL:!MD5"
#define NGX_DEFAULT_ECDH_CURVE  "auto"


static void *ngx_mail_ssl_create_conf(ngx_conf_t *cf);
static char *ngx_mail_ssl_merge_conf(ngx_conf_t *cf, void *parent, void *child);

static char *ngx_mail_ssl_enable(ngx_conf_t *cf, ngx_command_t *cmd,
    void *conf);
static char *ngx_mail_ssl_starttls(ngx_conf_t *cf, ngx_command_t *cmd,
    void *conf);
static char *ngx_mail_ssl_password_file(ngx_conf_t *cf, ngx_command_t *cmd,
    void *conf);
static char *ngx_mail_ssl_session_cache(ngx_conf_t *cf, ngx_command_t *cmd,
    void *conf);


static ngx_conf_enum_t  ngx_mail_starttls_state[] = {
    { ngx_string("off"), NGX_MAIL_STARTTLS_OFF },
    { ngx_string("on"), NGX_MAIL_STARTTLS_ON },
    { ngx_string("only"), NGX_MAIL_STARTTLS_ONLY },
    { ngx_null_string, 0 }
};



static ngx_conf_bitmask_t  ngx_mail_ssl_protocols[] = {
    { ngx_string("SSLv2"), NGX_SSL_SSLv2 },
    { ngx_string("SSLv3"), NGX_SSL_SSLv3 },
    { ngx_string("TLSv1"), NGX_SSL_TLSv1 },
    { ngx_string("TLSv1.1"), NGX_SSL_TLSv1_1 },
    { ngx_string("TLSv1.2"), NGX_SSL_TLSv1_2 },
    { ngx_string("TLSv1.3"), NGX_SSL_TLSv1_3 },
    { ngx_null_string, 0 }
};


static ngx_conf_enum_t  ngx_mail_ssl_verify[] = {
    { ngx_string("off"), 0 },
    { ngx_string("on"), 1 },
    { ngx_string("optional"), 2 },
    { ngx_string("optional_no_ca"), 3 },
    { ngx_null_string, 0 }
};


static ngx_command_t  ngx_mail_ssl_commands[] = {

    { ngx_string("ssl"),
      NGX_MAIL_MAIN_CONF|NGX_MAIL_SRV_CONF|NGX_CONF_FLAG,
      ngx_mail_ssl_enable,
      NGX_MAIL_SRV_CONF_OFFSET,
      offsetof(ngx_mail_ssl_conf_t, enable),
      NULL },

    { ngx_string("starttls"),
      NGX_MAIL_MAIN_CONF|NGX_MAIL_SRV_CONF|NGX_CONF_TAKE1,
      ngx_mail_ssl_starttls,
      NGX_MAIL_SRV_CONF_OFFSET,
      offsetof(ngx_mail_ssl_conf_t, starttls),
      ngx_mail_starttls_state },

    { ngx_string("ssl_certificate"),
      NGX_MAIL_MAIN_CONF|NGX_MAIL_SRV_CONF|NGX_CONF_TAKE1,
      ngx_conf_set_str_array_slot,
      NGX_MAIL_SRV_CONF_OFFSET,
      offsetof(ngx_mail_ssl_conf_t, certificates),
      NULL },

    { ngx_string("ssl_certificate_key"),
      NGX_MAIL_MAIN_CONF|NGX_MAIL_SRV_CONF|NGX_CONF_TAKE1,
      ngx_conf_set_str_array_slot,
      NGX_MAIL_SRV_CONF_OFFSET,
      offsetof(ngx_mail_ssl_conf_t, certificate_keys),
      NULL },

    { ngx_string("ssl_password_file"),
      NGX_MAIL_MAIN_CONF|NGX_MAIL_SRV_CONF|NGX_CONF_TAKE1,
      ngx_mail_ssl_password_file,
      NGX_MAIL_SRV_CONF_OFFSET,
      0,
      NULL },

    { ngx_string("ssl_dhparam"),
      NGX_MAIL_MAIN_CONF|NGX_MAIL_SRV_CONF|NGX_CONF_TAKE1,
      ngx_conf_set_str_slot,
      NGX_MAIL_SRV_CONF_OFFSET,
      offsetof(ngx_mail_ssl_conf_t, dhparam),
      NULL },

    { ngx_string("ssl_ecdh_curve"),
      NGX_MAIL_MAIN_CONF|NGX_MAIL_SRV_CONF|NGX_CONF_TAKE1,
      ngx_conf_set_str_slot,
      NGX_MAIL_SRV_CONF_OFFSET,
      offsetof(ngx_mail_ssl_conf_t, ecdh_curve),
      NULL },

    { ngx_string("ssl_protocols"),
      NGX_MAIL_MAIN_CONF|NGX_MAIL_SRV_CONF|NGX_CONF_1MORE,
      ngx_conf_set_bitmask_slot,
      NGX_MAIL_SRV_CONF_OFFSET,
      offsetof(ngx_mail_ssl_conf_t, protocols),
      &ngx_mail_ssl_protocols },

    { ngx_string("ssl_ciphers"),
      NGX_MAIL_MAIN_CONF|NGX_MAIL_SRV_CONF|NGX_CONF_TAKE1,
      ngx_conf_set_str_slot,
      NGX_MAIL_SRV_CONF_OFFSET,
      offsetof(ngx_mail_ssl_conf_t, ciphers),
      NULL },

    { ngx_string("ssl_prefer_server_ciphers"),
      NGX_MAIL_MAIN_CONF|NGX_MAIL_SRV_CONF|NGX_CONF_FLAG,
      ngx_conf_set_flag_slot,
      NGX_MAIL_SRV_CONF_OFFSET,
      offsetof(ngx_mail_ssl_conf_t, prefer_server_ciphers),
      NULL },

    { ngx_string("ssl_session_cache"),
      NGX_MAIL_MAIN_CONF|NGX_MAIL_SRV_CONF|NGX_CONF_TAKE12,
      ngx_mail_ssl_session_cache,
      NGX_MAIL_SRV_CONF_OFFSET,
      0,
      NULL },

    { ngx_string("ssl_session_tickets"),
      NGX_MAIL_MAIN_CONF|NGX_MAIL_SRV_CONF|NGX_CONF_FLAG,
      ngx_conf_set_flag_slot,
      NGX_MAIL_SRV_CONF_OFFSET,
      offsetof(ngx_mail_ssl_conf_t, session_tickets),
      NULL },

    { ngx_string("ssl_session_ticket_key"),
      NGX_MAIL_MAIN_CONF|NGX_MAIL_SRV_CONF|NGX_CONF_TAKE1,
      ngx_conf_set_str_array_slot,
      NGX_MAIL_SRV_CONF_OFFSET,
      offsetof(ngx_mail_ssl_conf_t, session_ticket_keys),
      NULL },

    { ngx_string("ssl_session_timeout"),
      NGX_MAIL_MAIN_CONF|NGX_MAIL_SRV_CONF|NGX_CONF_TAKE1,
      ngx_conf_set_sec_slot,
      NGX_MAIL_SRV_CONF_OFFSET,
      offsetof(ngx_mail_ssl_conf_t, session_timeout),
      NULL },

    { ngx_string("ssl_verify_client"),
      NGX_MAIL_MAIN_CONF|NGX_MAIL_SRV_CONF|NGX_CONF_TAKE1,
      ngx_conf_set_enum_slot,
      NGX_MAIL_SRV_CONF_OFFSET,
      offsetof(ngx_mail_ssl_conf_t, verify),
      &ngx_mail_ssl_verify },

    { ngx_string("ssl_verify_depth"),
      NGX_MAIL_MAIN_CONF|NGX_MAIL_SRV_CONF|NGX_CONF_TAKE1,
      ngx_conf_set_num_slot,
      NGX_MAIL_SRV_CONF_OFFSET,
      offsetof(ngx_mail_ssl_conf_t, verify_depth),
      NULL },

    { ngx_string("ssl_client_certificate"),
      NGX_MAIL_MAIN_CONF|NGX_MAIL_SRV_CONF|NGX_CONF_TAKE1,
      ngx_conf_set_str_slot,
      NGX_MAIL_SRV_CONF_OFFSET,
      offsetof(ngx_mail_ssl_conf_t, client_certificate),
      NULL },

    { ngx_string("ssl_trusted_certificate"),
      NGX_MAIL_MAIN_CONF|NGX_MAIL_SRV_CONF|NGX_CONF_TAKE1,
      ngx_conf_set_str_slot,
      NGX_MAIL_SRV_CONF_OFFSET,
      offsetof(ngx_mail_ssl_conf_t, trusted_certificate),
      NULL },

    { ngx_string("ssl_crl"),
      NGX_MAIL_MAIN_CONF|NGX_MAIL_SRV_CONF|NGX_CONF_TAKE1,
      ngx_conf_set_str_slot,
      NGX_MAIL_SRV_CONF_OFFSET,
      offsetof(ngx_mail_ssl_conf_t, crl),
      NULL },

      ngx_null_command
};


static ngx_mail_module_t  ngx_mail_ssl_module_ctx = {
    NULL,                                  /* protocol */

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

    ngx_mail_ssl_create_conf,              /* create server configuration */
    ngx_mail_ssl_merge_conf                /* merge server configuration */
};


ngx_module_t  ngx_mail_ssl_module = {
    NGX_MODULE_V1,
    &ngx_mail_ssl_module_ctx,              /* module context */
    ngx_mail_ssl_commands,                 /* module directives */
    NGX_MAIL_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_str_t ngx_mail_ssl_sess_id_ctx = ngx_string("MAIL");


static void *
ngx_mail_ssl_create_conf(ngx_conf_t *cf)
{
    ngx_mail_ssl_conf_t  *scf;

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

    /*
     * set by ngx_pcalloc():
     *
     *     scf->protocols = 0;
     *     scf->dhparam = { 0, NULL };
     *     scf->ecdh_curve = { 0, NULL };
     *     scf->client_certificate = { 0, NULL };
     *     scf->trusted_certificate = { 0, NULL };
     *     scf->crl = { 0, NULL };
     *     scf->ciphers = { 0, NULL };
     *     scf->shm_zone = NULL;
     */

    scf->enable = NGX_CONF_UNSET;
    scf->starttls = NGX_CONF_UNSET_UINT;
    scf->certificates = NGX_CONF_UNSET_PTR;
    scf->certificate_keys = NGX_CONF_UNSET_PTR;
    scf->passwords = NGX_CONF_UNSET_PTR;
    scf->prefer_server_ciphers = NGX_CONF_UNSET;
    scf->verify = NGX_CONF_UNSET_UINT;
    scf->verify_depth = NGX_CONF_UNSET_UINT;
    scf->builtin_session_cache = NGX_CONF_UNSET;
    scf->session_timeout = NGX_CONF_UNSET;
    scf->session_tickets = NGX_CONF_UNSET;
    scf->session_ticket_keys = NGX_CONF_UNSET_PTR;

    return scf;
}


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

    char                *mode;
    ngx_pool_cleanup_t  *cln;

    ngx_conf_merge_value(conf->enable, prev->enable, 0);
    ngx_conf_merge_uint_value(conf->starttls, prev->starttls,
                         NGX_MAIL_STARTTLS_OFF);

    ngx_conf_merge_value(conf->session_timeout,
                         prev->session_timeout, 300);

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

    ngx_conf_merge_bitmask_value(conf->protocols, prev->protocols,
                         (NGX_CONF_BITMASK_SET|NGX_SSL_TLSv1
                          |NGX_SSL_TLSv1_1|NGX_SSL_TLSv1_2));

    ngx_conf_merge_uint_value(conf->verify, prev->verify, 0);
    ngx_conf_merge_uint_value(conf->verify_depth, prev->verify_depth, 1);

    ngx_conf_merge_ptr_value(conf->certificates, prev->certificates, NULL);
    ngx_conf_merge_ptr_value(conf->certificate_keys, prev->certificate_keys,
                         NULL);

    ngx_conf_merge_ptr_value(conf->passwords, prev->passwords, NULL);

    ngx_conf_merge_str_value(conf->dhparam, prev->dhparam, "");

    ngx_conf_merge_str_value(conf->ecdh_curve, prev->ecdh_curve,
                         NGX_DEFAULT_ECDH_CURVE);

    ngx_conf_merge_str_value(conf->client_certificate,
                         prev->client_certificate, "");
    ngx_conf_merge_str_value(conf->trusted_certificate,
                         prev->trusted_certificate, "");
    ngx_conf_merge_str_value(conf->crl, prev->crl, "");

    ngx_conf_merge_str_value(conf->ciphers, prev->ciphers, NGX_DEFAULT_CIPHERS);


    conf->ssl.log = cf->log;

    if (conf->enable) {
        mode = "ssl";

    } else if (conf->starttls != NGX_MAIL_STARTTLS_OFF) {
        mode = "starttls";

    } else {
        mode = "";
    }

    if (conf->file == NULL) {
        conf->file = prev->file;
        conf->line = prev->line;
    }

    if (*mode) {

        if (conf->certificates == NULL) {
            ngx_log_error(NGX_LOG_EMERG, cf->log, 0,
                          "no \"ssl_certificate\" is defined for "
                          "the \"%s\" directive in %s:%ui",
                          mode, conf->file, conf->line);
            return NGX_CONF_ERROR;
        }

        if (conf->certificate_keys == NULL) {
            ngx_log_error(NGX_LOG_EMERG, cf->log, 0,
                          "no \"ssl_certificate_key\" is defined for "
                          "the \"%s\" directive in %s:%ui",
                          mode, conf->file, conf->line);
            return NGX_CONF_ERROR;
        }

        if (conf->certificate_keys->nelts < conf->certificates->nelts) {
            ngx_log_error(NGX_LOG_EMERG, cf->log, 0,
                          "no \"ssl_certificate_key\" is defined "
                          "for certificate \"%V\" and "
                          "the \"ssl\" directive in %s:%ui",
                          ((ngx_str_t *) conf->certificates->elts)
                          + conf->certificates->nelts - 1,
                          conf->file, conf->line);
            return NGX_CONF_ERROR;
        }

    } else {

        if (conf->certificates == NULL) {
            return NGX_CONF_OK;
        }

        if (conf->certificate_keys == NULL
            || conf->certificate_keys->nelts < conf->certificates->nelts)
        {
            ngx_log_error(NGX_LOG_EMERG, cf->log, 0,
                          "no \"ssl_certificate_key\" is defined "
                          "for certificate \"%V\"",
                          ((ngx_str_t *) conf->certificates->elts)
                          + conf->certificates->nelts - 1);
            return NGX_CONF_ERROR;
        }
    }

    if (ngx_ssl_create(&conf->ssl, conf->protocols, NULL) != NGX_OK) {
        return NGX_CONF_ERROR;
    }

    cln = ngx_pool_cleanup_add(cf->pool, 0);
    if (cln == NULL) {
        return NGX_CONF_ERROR;
    }

    cln->handler = ngx_ssl_cleanup_ctx;
    cln->data = &conf->ssl;

    if (ngx_ssl_certificates(cf, &conf->ssl, conf->certificates,
                             conf->certificate_keys, conf->passwords)
        != NGX_OK)
    {
        return NGX_CONF_ERROR;
    }

    if (conf->verify) {

        if (conf->client_certificate.len == 0 && conf->verify != 3) {
            ngx_log_error(NGX_LOG_EMERG, cf->log, 0,
                          "no ssl_client_certificate for ssl_client_verify");
            return NGX_CONF_ERROR;
        }

        if (ngx_ssl_client_certificate(cf, &conf->ssl,
                                       &conf->client_certificate,
                                       conf->verify_depth)
            != NGX_OK)
        {
            return NGX_CONF_ERROR;
        }

        if (ngx_ssl_trusted_certificate(cf, &conf->ssl,
                                        &conf->trusted_certificate,
                                        conf->verify_depth)
            != NGX_OK)
        {
            return NGX_CONF_ERROR;
        }

        if (ngx_ssl_crl(cf, &conf->ssl, &conf->crl) != NGX_OK) {
            return NGX_CONF_ERROR;
        }
    }

    if (ngx_ssl_ciphers(cf, &conf->ssl, &conf->ciphers,
                        conf->prefer_server_ciphers)
        != NGX_OK)
    {
        return NGX_CONF_ERROR;
    }

    if (ngx_ssl_dhparam(cf, &conf->ssl, &conf->dhparam) != NGX_OK) {
        return NGX_CONF_ERROR;
    }

    if (ngx_ssl_ecdh_curve(cf, &conf->ssl, &conf->ecdh_curve) != NGX_OK) {
        return NGX_CONF_ERROR;
    }

    ngx_conf_merge_value(conf->builtin_session_cache,
                         prev->builtin_session_cache, NGX_SSL_NONE_SCACHE);

    if (conf->shm_zone == NULL) {
        conf->shm_zone = prev->shm_zone;
    }

    if (ngx_ssl_session_cache(&conf->ssl, &ngx_mail_ssl_sess_id_ctx,
                              conf->builtin_session_cache,
                              conf->shm_zone, conf->session_timeout)
        != NGX_OK)
    {
        return NGX_CONF_ERROR;
    }

    ngx_conf_merge_value(conf->session_tickets,
                         prev->session_tickets, 1);

#ifdef SSL_OP_NO_TICKET
    if (!conf->session_tickets) {
        SSL_CTX_set_options(conf->ssl.ctx, SSL_OP_NO_TICKET);
    }
#endif

    ngx_conf_merge_ptr_value(conf->session_ticket_keys,
                         prev->session_ticket_keys, NULL);

    if (ngx_ssl_session_ticket_keys(cf, &conf->ssl, conf->session_ticket_keys)
        != NGX_OK)
    {
        return NGX_CONF_ERROR;
    }

    return NGX_CONF_OK;
}


static char *
ngx_mail_ssl_enable(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
{
    ngx_mail_ssl_conf_t  *scf = conf;

    char  *rv;

    rv = ngx_conf_set_flag_slot(cf, cmd, conf);

    if (rv != NGX_CONF_OK) {
        return rv;
    }

    if (scf->enable && (ngx_int_t) scf->starttls > NGX_MAIL_STARTTLS_OFF) {
        ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                           "\"starttls\" directive conflicts with \"ssl on\"");
        return NGX_CONF_ERROR;
    }

    scf->file = cf->conf_file->file.name.data;
    scf->line = cf->conf_file->line;

    return NGX_CONF_OK;
}


static char *
ngx_mail_ssl_starttls(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
{
    ngx_mail_ssl_conf_t  *scf = conf;

    char  *rv;

    rv = ngx_conf_set_enum_slot(cf, cmd, conf);

    if (rv != NGX_CONF_OK) {
        return rv;
    }

    if (scf->enable == 1 && (ngx_int_t) scf->starttls > NGX_MAIL_STARTTLS_OFF) {
        ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                           "\"ssl\" directive conflicts with \"starttls\"");
        return NGX_CONF_ERROR;
    }

    scf->file = cf->conf_file->file.name.data;
    scf->line = cf->conf_file->line;

    return NGX_CONF_OK;
}


static char *
ngx_mail_ssl_password_file(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
{
    ngx_mail_ssl_conf_t  *scf = conf;

    ngx_str_t  *value;

    if (scf->passwords != NGX_CONF_UNSET_PTR) {
        return "is duplicate";
    }

    value = cf->args->elts;

    scf->passwords = ngx_ssl_read_password_file(cf, &value[1]);

    if (scf->passwords == NULL) {
        return NGX_CONF_ERROR;
    }

    return NGX_CONF_OK;
}


static char *
ngx_mail_ssl_session_cache(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
{
    ngx_mail_ssl_conf_t  *scf = conf;

    size_t       len;
    ngx_str_t   *value, name, size;
    ngx_int_t    n;
    ngx_uint_t   i, j;

    value = cf->args->elts;

    for (i = 1; i < cf->args->nelts; i++) {

        if (ngx_strcmp(value[i].data, "off") == 0) {
            scf->builtin_session_cache = NGX_SSL_NO_SCACHE;
            continue;
        }

        if (ngx_strcmp(value[i].data, "none") == 0) {
            scf->builtin_session_cache = NGX_SSL_NONE_SCACHE;
            continue;
        }

        if (ngx_strcmp(value[i].data, "builtin") == 0) {
            scf->builtin_session_cache = NGX_SSL_DFLT_BUILTIN_SCACHE;
            continue;
        }

        if (value[i].len > sizeof("builtin:") - 1
            && ngx_strncmp(value[i].data, "builtin:", sizeof("builtin:") - 1)
               == 0)
        {
            n = ngx_atoi(value[i].data + sizeof("builtin:") - 1,
                         value[i].len - (sizeof("builtin:") - 1));

            if (n == NGX_ERROR) {
                goto invalid;
            }

            scf->builtin_session_cache = n;

            continue;
        }

        if (value[i].len > sizeof("shared:") - 1
            && ngx_strncmp(value[i].data, "shared:", sizeof("shared:") - 1)
               == 0)
        {
            len = 0;

            for (j = sizeof("shared:") - 1; j < value[i].len; j++) {
                if (value[i].data[j] == ':') {
                    break;
                }

                len++;
            }

            if (len == 0) {
                goto invalid;
            }

            name.len = len;
            name.data = value[i].data + sizeof("shared:") - 1;

            size.len = value[i].len - j - 1;
            size.data = name.data + len + 1;

            n = ngx_parse_size(&size);

            if (n == NGX_ERROR) {
                goto invalid;
            }

            if (n < (ngx_int_t) (8 * ngx_pagesize)) {
                ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                                   "session cache \"%V\" is too small",
                                   &value[i]);

                return NGX_CONF_ERROR;
            }

            scf->shm_zone = ngx_shared_memory_add(cf, &name, n,
                                                   &ngx_mail_ssl_module);
            if (scf->shm_zone == NULL) {
                return NGX_CONF_ERROR;
            }

            scf->shm_zone->init = ngx_ssl_session_cache_init;

            continue;
        }

        goto invalid;
    }

    if (scf->shm_zone && scf->builtin_session_cache == NGX_CONF_UNSET) {
        scf->builtin_session_cache = NGX_SSL_NO_BUILTIN_SCACHE;
    }

    return NGX_CONF_OK;

invalid:

    ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                       "invalid session cache \"%V\"", &value[i]);

    return NGX_CONF_ERROR;
}