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view src/mail/ngx_mail_pop3_handler.c @ 6874:7cc2d3a96ea3

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Fixed trailer construction with limit on FreeBSD and macOS. The ngx_chain_coalesce_file() function may produce more bytes to send then requested in the limit passed, as it aligns the last file position to send to memory page boundary. As a result, (limit - send) may become negative. This resulted in big positive number when converted to size_t while calling ngx_output_chain_to_iovec(). Another part of the problem is in ngx_chain_coalesce_file(): it changes cl to the next chain link even if the current buffer is only partially sent due to limit. Therefore, if a file buffer was not expected to be fully sent due to limit, and was followed by a memory buffer, nginx called sendfile() with a part of the file buffer, and the memory buffer in trailer. If there were enough room in the socket buffer, this resulted in a part of the file buffer being skipped, and corresponding part of the memory buffer sent instead. The bug was introduced in 8e903522c17a (1.7.8). Configurations affected are ones using limits, that is, limit_rate and/or sendfile_max_chunk, and memory buffers after file ones (may happen when using subrequests or with proxying with disk buffering). Fix is to explicitly check if (send < limit) before constructing trailer with ngx_output_chain_to_iovec(). Additionally, ngx_chain_coalesce_file() was modified to preserve unfinished file buffers in cl.
author Maxim Dounin <mdounin@mdounin.ru>
date Fri, 20 Jan 2017 21:12:48 +0300
parents b2915d99ee8d
children ab6257dac2a8
line wrap: on
line source


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


#include <ngx_config.h>
#include <ngx_core.h>
#include <ngx_event.h>
#include <ngx_mail.h>
#include <ngx_mail_pop3_module.h>


static ngx_int_t ngx_mail_pop3_user(ngx_mail_session_t *s, ngx_connection_t *c);
static ngx_int_t ngx_mail_pop3_pass(ngx_mail_session_t *s, ngx_connection_t *c);
static ngx_int_t ngx_mail_pop3_capa(ngx_mail_session_t *s, ngx_connection_t *c,
    ngx_int_t stls);
static ngx_int_t ngx_mail_pop3_stls(ngx_mail_session_t *s, ngx_connection_t *c);
static ngx_int_t ngx_mail_pop3_apop(ngx_mail_session_t *s, ngx_connection_t *c);
static ngx_int_t ngx_mail_pop3_auth(ngx_mail_session_t *s, ngx_connection_t *c);


static u_char  pop3_greeting[] = "+OK POP3 ready" CRLF;
static u_char  pop3_ok[] = "+OK" CRLF;
static u_char  pop3_next[] = "+ " CRLF;
static u_char  pop3_username[] = "+ VXNlcm5hbWU6" CRLF;
static u_char  pop3_password[] = "+ UGFzc3dvcmQ6" CRLF;
static u_char  pop3_invalid_command[] = "-ERR invalid command" CRLF;


void
ngx_mail_pop3_init_session(ngx_mail_session_t *s, ngx_connection_t *c)
{
    u_char                    *p;
    ngx_mail_core_srv_conf_t  *cscf;
    ngx_mail_pop3_srv_conf_t  *pscf;

    pscf = ngx_mail_get_module_srv_conf(s, ngx_mail_pop3_module);
    cscf = ngx_mail_get_module_srv_conf(s, ngx_mail_core_module);

    if (pscf->auth_methods
        & (NGX_MAIL_AUTH_APOP_ENABLED|NGX_MAIL_AUTH_CRAM_MD5_ENABLED))
    {
        if (ngx_mail_salt(s, c, cscf) != NGX_OK) {
            ngx_mail_session_internal_server_error(s);
            return;
        }

        s->out.data = ngx_pnalloc(c->pool, sizeof(pop3_greeting) + s->salt.len);
        if (s->out.data == NULL) {
            ngx_mail_session_internal_server_error(s);
            return;
        }

        p = ngx_cpymem(s->out.data, pop3_greeting, sizeof(pop3_greeting) - 3);
        *p++ = ' ';
        p = ngx_cpymem(p, s->salt.data, s->salt.len);

        s->out.len = p - s->out.data;

    } else {
        ngx_str_set(&s->out, pop3_greeting);
    }

    c->read->handler = ngx_mail_pop3_init_protocol;

    ngx_add_timer(c->read, cscf->timeout);

    if (ngx_handle_read_event(c->read, 0) != NGX_OK) {
        ngx_mail_close_connection(c);
    }

    ngx_mail_send(c->write);
}


void
ngx_mail_pop3_init_protocol(ngx_event_t *rev)
{
    ngx_connection_t    *c;
    ngx_mail_session_t  *s;

    c = rev->data;

    c->log->action = "in auth state";

    if (rev->timedout) {
        ngx_log_error(NGX_LOG_INFO, c->log, NGX_ETIMEDOUT, "client timed out");
        c->timedout = 1;
        ngx_mail_close_connection(c);
        return;
    }

    s = c->data;

    if (s->buffer == NULL) {
        if (ngx_array_init(&s->args, c->pool, 2, sizeof(ngx_str_t))
            == NGX_ERROR)
        {
            ngx_mail_session_internal_server_error(s);
            return;
        }

        s->buffer = ngx_create_temp_buf(c->pool, 128);
        if (s->buffer == NULL) {
            ngx_mail_session_internal_server_error(s);
            return;
        }
    }

    s->mail_state = ngx_pop3_start;
    c->read->handler = ngx_mail_pop3_auth_state;

    ngx_mail_pop3_auth_state(rev);
}


void
ngx_mail_pop3_auth_state(ngx_event_t *rev)
{
    ngx_int_t            rc;
    ngx_connection_t    *c;
    ngx_mail_session_t  *s;

    c = rev->data;
    s = c->data;

    ngx_log_debug0(NGX_LOG_DEBUG_MAIL, c->log, 0, "pop3 auth state");

    if (rev->timedout) {
        ngx_log_error(NGX_LOG_INFO, c->log, NGX_ETIMEDOUT, "client timed out");
        c->timedout = 1;
        ngx_mail_close_connection(c);
        return;
    }

    if (s->out.len) {
        ngx_log_debug0(NGX_LOG_DEBUG_MAIL, c->log, 0, "pop3 send handler busy");
        s->blocked = 1;
        return;
    }

    s->blocked = 0;

    rc = ngx_mail_read_command(s, c);

    if (rc == NGX_AGAIN || rc == NGX_ERROR) {
        return;
    }

    ngx_str_set(&s->out, pop3_ok);

    if (rc == NGX_OK) {
        switch (s->mail_state) {

        case ngx_pop3_start:

            switch (s->command) {

            case NGX_POP3_USER:
                rc = ngx_mail_pop3_user(s, c);
                break;

            case NGX_POP3_CAPA:
                rc = ngx_mail_pop3_capa(s, c, 1);
                break;

            case NGX_POP3_APOP:
                rc = ngx_mail_pop3_apop(s, c);
                break;

            case NGX_POP3_AUTH:
                rc = ngx_mail_pop3_auth(s, c);
                break;

            case NGX_POP3_QUIT:
                s->quit = 1;
                break;

            case NGX_POP3_NOOP:
                break;

            case NGX_POP3_STLS:
                rc = ngx_mail_pop3_stls(s, c);
                break;

            default:
                rc = NGX_MAIL_PARSE_INVALID_COMMAND;
                break;
            }

            break;

        case ngx_pop3_user:

            switch (s->command) {

            case NGX_POP3_PASS:
                rc = ngx_mail_pop3_pass(s, c);
                break;

            case NGX_POP3_CAPA:
                rc = ngx_mail_pop3_capa(s, c, 0);
                break;

            case NGX_POP3_QUIT:
                s->quit = 1;
                break;

            case NGX_POP3_NOOP:
                break;

            default:
                rc = NGX_MAIL_PARSE_INVALID_COMMAND;
                break;
            }

            break;

        /* suppress warnings */
        case ngx_pop3_passwd:
            break;

        case ngx_pop3_auth_login_username:
            rc = ngx_mail_auth_login_username(s, c, 0);

            ngx_str_set(&s->out, pop3_password);
            s->mail_state = ngx_pop3_auth_login_password;
            break;

        case ngx_pop3_auth_login_password:
            rc = ngx_mail_auth_login_password(s, c);
            break;

        case ngx_pop3_auth_plain:
            rc = ngx_mail_auth_plain(s, c, 0);
            break;

        case ngx_pop3_auth_cram_md5:
            rc = ngx_mail_auth_cram_md5(s, c);
            break;

        case ngx_pop3_auth_external:
            rc = ngx_mail_auth_external(s, c, 0);
            break;
        }
    }

    switch (rc) {

    case NGX_DONE:
        ngx_mail_auth(s, c);
        return;

    case NGX_ERROR:
        ngx_mail_session_internal_server_error(s);
        return;

    case NGX_MAIL_PARSE_INVALID_COMMAND:
        s->mail_state = ngx_pop3_start;
        s->state = 0;

        ngx_str_set(&s->out, pop3_invalid_command);

        /* fall through */

    case NGX_OK:

        s->args.nelts = 0;
        s->buffer->pos = s->buffer->start;
        s->buffer->last = s->buffer->start;

        if (s->state) {
            s->arg_start = s->buffer->start;
        }

        ngx_mail_send(c->write);
    }
}

static ngx_int_t
ngx_mail_pop3_user(ngx_mail_session_t *s, ngx_connection_t *c)
{
    ngx_str_t  *arg;

#if (NGX_MAIL_SSL)
    if (ngx_mail_starttls_only(s, c)) {
        return NGX_MAIL_PARSE_INVALID_COMMAND;
    }
#endif

    if (s->args.nelts != 1) {
        return NGX_MAIL_PARSE_INVALID_COMMAND;
    }

    arg = s->args.elts;
    s->login.len = arg[0].len;
    s->login.data = ngx_pnalloc(c->pool, s->login.len);
    if (s->login.data == NULL) {
        return NGX_ERROR;
    }

    ngx_memcpy(s->login.data, arg[0].data, s->login.len);

    ngx_log_debug1(NGX_LOG_DEBUG_MAIL, c->log, 0,
                   "pop3 login: \"%V\"", &s->login);

    s->mail_state = ngx_pop3_user;

    return NGX_OK;
}


static ngx_int_t
ngx_mail_pop3_pass(ngx_mail_session_t *s, ngx_connection_t *c)
{
    ngx_str_t  *arg;

    if (s->args.nelts != 1) {
        return NGX_MAIL_PARSE_INVALID_COMMAND;
    }

    arg = s->args.elts;
    s->passwd.len = arg[0].len;
    s->passwd.data = ngx_pnalloc(c->pool, s->passwd.len);
    if (s->passwd.data == NULL) {
        return NGX_ERROR;
    }

    ngx_memcpy(s->passwd.data, arg[0].data, s->passwd.len);

#if (NGX_DEBUG_MAIL_PASSWD)
    ngx_log_debug1(NGX_LOG_DEBUG_MAIL, c->log, 0,
                   "pop3 passwd: \"%V\"", &s->passwd);
#endif

    return NGX_DONE;
}


static ngx_int_t
ngx_mail_pop3_capa(ngx_mail_session_t *s, ngx_connection_t *c, ngx_int_t stls)
{
    ngx_mail_pop3_srv_conf_t  *pscf;

    pscf = ngx_mail_get_module_srv_conf(s, ngx_mail_pop3_module);

#if (NGX_MAIL_SSL)

    if (stls && c->ssl == NULL) {
        ngx_mail_ssl_conf_t  *sslcf;

        sslcf = ngx_mail_get_module_srv_conf(s, ngx_mail_ssl_module);

        if (sslcf->starttls == NGX_MAIL_STARTTLS_ON) {
            s->out = pscf->starttls_capability;
            return NGX_OK;
        }

        if (sslcf->starttls == NGX_MAIL_STARTTLS_ONLY) {
            s->out = pscf->starttls_only_capability;
            return NGX_OK;
        }
    }

#endif

    s->out = pscf->capability;
    return NGX_OK;
}


static ngx_int_t
ngx_mail_pop3_stls(ngx_mail_session_t *s, ngx_connection_t *c)
{
#if (NGX_MAIL_SSL)
    ngx_mail_ssl_conf_t  *sslcf;

    if (c->ssl == NULL) {
        sslcf = ngx_mail_get_module_srv_conf(s, ngx_mail_ssl_module);
        if (sslcf->starttls) {
            c->read->handler = ngx_mail_starttls_handler;
            return NGX_OK;
        }
    }

#endif

    return NGX_MAIL_PARSE_INVALID_COMMAND;
}


static ngx_int_t
ngx_mail_pop3_apop(ngx_mail_session_t *s, ngx_connection_t *c)
{
    ngx_str_t                 *arg;
    ngx_mail_pop3_srv_conf_t  *pscf;

#if (NGX_MAIL_SSL)
    if (ngx_mail_starttls_only(s, c)) {
        return NGX_MAIL_PARSE_INVALID_COMMAND;
    }
#endif

    if (s->args.nelts != 2) {
        return NGX_MAIL_PARSE_INVALID_COMMAND;
    }

    pscf = ngx_mail_get_module_srv_conf(s, ngx_mail_pop3_module);

    if (!(pscf->auth_methods & NGX_MAIL_AUTH_APOP_ENABLED)) {
        return NGX_MAIL_PARSE_INVALID_COMMAND;
    }

    arg = s->args.elts;

    s->login.len = arg[0].len;
    s->login.data = ngx_pnalloc(c->pool, s->login.len);
    if (s->login.data == NULL) {
        return NGX_ERROR;
    }

    ngx_memcpy(s->login.data, arg[0].data, s->login.len);

    s->passwd.len = arg[1].len;
    s->passwd.data = ngx_pnalloc(c->pool, s->passwd.len);
    if (s->passwd.data == NULL) {
        return NGX_ERROR;
    }

    ngx_memcpy(s->passwd.data, arg[1].data, s->passwd.len);

    ngx_log_debug2(NGX_LOG_DEBUG_MAIL, c->log, 0,
                   "pop3 apop: \"%V\" \"%V\"", &s->login, &s->passwd);

    s->auth_method = NGX_MAIL_AUTH_APOP;

    return NGX_DONE;
}


static ngx_int_t
ngx_mail_pop3_auth(ngx_mail_session_t *s, ngx_connection_t *c)
{
    ngx_int_t                  rc;
    ngx_mail_pop3_srv_conf_t  *pscf;

#if (NGX_MAIL_SSL)
    if (ngx_mail_starttls_only(s, c)) {
        return NGX_MAIL_PARSE_INVALID_COMMAND;
    }
#endif

    pscf = ngx_mail_get_module_srv_conf(s, ngx_mail_pop3_module);

    if (s->args.nelts == 0) {
        s->out = pscf->auth_capability;
        s->state = 0;

        return NGX_OK;
    }

    rc = ngx_mail_auth_parse(s, c);

    switch (rc) {

    case NGX_MAIL_AUTH_LOGIN:

        ngx_str_set(&s->out, pop3_username);
        s->mail_state = ngx_pop3_auth_login_username;

        return NGX_OK;

    case NGX_MAIL_AUTH_LOGIN_USERNAME:

        ngx_str_set(&s->out, pop3_password);
        s->mail_state = ngx_pop3_auth_login_password;

        return ngx_mail_auth_login_username(s, c, 1);

    case NGX_MAIL_AUTH_PLAIN:

        ngx_str_set(&s->out, pop3_next);
        s->mail_state = ngx_pop3_auth_plain;

        return NGX_OK;

    case NGX_MAIL_AUTH_CRAM_MD5:

        if (!(pscf->auth_methods & NGX_MAIL_AUTH_CRAM_MD5_ENABLED)) {
            return NGX_MAIL_PARSE_INVALID_COMMAND;
        }

        if (ngx_mail_auth_cram_md5_salt(s, c, "+ ", 2) == NGX_OK) {
            s->mail_state = ngx_pop3_auth_cram_md5;
            return NGX_OK;
        }

        return NGX_ERROR;

    case NGX_MAIL_AUTH_EXTERNAL:

        if (!(pscf->auth_methods & NGX_MAIL_AUTH_EXTERNAL_ENABLED)) {
            return NGX_MAIL_PARSE_INVALID_COMMAND;
        }

        ngx_str_set(&s->out, pop3_username);
        s->mail_state = ngx_pop3_auth_external;

        return NGX_OK;
    }

    return rc;
}