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SSL: disabled renegotiation detection in client mode. CVE-2009-3555 is no longer relevant and mitigated by the renegotiation info extension (secure renegotiation). On the other hand, unexpected renegotiation still introduces potential security risks, and hence we do not allow renegotiation on the server side, as we never request renegotiation. On the client side the situation is different though. There are backends which explicitly request renegotiation, and disabled renegotiation introduces interoperability problems. This change allows renegotiation on the client side, and fixes interoperability problems as observed with such backends (ticket #872). Additionally, with TLSv1.3 the SSL_CB_HANDSHAKE_START flag is currently set by OpenSSL when receiving a NewSessionTicket message, and was detected by nginx as a renegotiation attempt. This looks like a bug in OpenSSL, though this change also allows better interoperability till the problem is fixed.
author Sergey Kandaurov <pluknet@nginx.com>
date Tue, 18 Apr 2017 16:08:44 +0300
parents bcb107bb89cd
children 6a81d96d3733
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>
#include <ngx_mail_imap_module.h>
#include <ngx_mail_smtp_module.h>


ngx_int_t
ngx_mail_pop3_parse_command(ngx_mail_session_t *s)
{
    u_char      ch, *p, *c, c0, c1, c2, c3;
    ngx_str_t  *arg;
    enum {
        sw_start = 0,
        sw_spaces_before_argument,
        sw_argument,
        sw_almost_done
    } state;

    state = s->state;

    for (p = s->buffer->pos; p < s->buffer->last; p++) {
        ch = *p;

        switch (state) {

        /* POP3 command */
        case sw_start:
            if (ch == ' ' || ch == CR || ch == LF) {
                c = s->buffer->start;

                if (p - c == 4) {

                    c0 = ngx_toupper(c[0]);
                    c1 = ngx_toupper(c[1]);
                    c2 = ngx_toupper(c[2]);
                    c3 = ngx_toupper(c[3]);

                    if (c0 == 'U' && c1 == 'S' && c2 == 'E' && c3 == 'R')
                    {
                        s->command = NGX_POP3_USER;

                    } else if (c0 == 'P' && c1 == 'A' && c2 == 'S' && c3 == 'S')
                    {
                        s->command = NGX_POP3_PASS;

                    } else if (c0 == 'A' && c1 == 'P' && c2 == 'O' && c3 == 'P')
                    {
                        s->command = NGX_POP3_APOP;

                    } else if (c0 == 'Q' && c1 == 'U' && c2 == 'I' && c3 == 'T')
                    {
                        s->command = NGX_POP3_QUIT;

                    } else if (c0 == 'C' && c1 == 'A' && c2 == 'P' && c3 == 'A')
                    {
                        s->command = NGX_POP3_CAPA;

                    } else if (c0 == 'A' && c1 == 'U' && c2 == 'T' && c3 == 'H')
                    {
                        s->command = NGX_POP3_AUTH;

                    } else if (c0 == 'N' && c1 == 'O' && c2 == 'O' && c3 == 'P')
                    {
                        s->command = NGX_POP3_NOOP;
#if (NGX_MAIL_SSL)
                    } else if (c0 == 'S' && c1 == 'T' && c2 == 'L' && c3 == 'S')
                    {
                        s->command = NGX_POP3_STLS;
#endif
                    } else {
                        goto invalid;
                    }

                } else {
                    goto invalid;
                }

                switch (ch) {
                case ' ':
                    state = sw_spaces_before_argument;
                    break;
                case CR:
                    state = sw_almost_done;
                    break;
                case LF:
                    goto done;
                }
                break;
            }

            if ((ch < 'A' || ch > 'Z') && (ch < 'a' || ch > 'z')) {
                goto invalid;
            }

            break;

        case sw_spaces_before_argument:
            switch (ch) {
            case ' ':
                break;
            case CR:
                state = sw_almost_done;
                s->arg_end = p;
                break;
            case LF:
                s->arg_end = p;
                goto done;
            default:
                if (s->args.nelts <= 2) {
                    state = sw_argument;
                    s->arg_start = p;
                    break;
                }
                goto invalid;
            }
            break;

        case sw_argument:
            switch (ch) {

            case ' ':

                /*
                 * the space should be considered as part of the at username
                 * or password, but not of argument in other commands
                 */

                if (s->command == NGX_POP3_USER
                    || s->command == NGX_POP3_PASS)
                {
                    break;
                }

                /* fall through */

            case CR:
            case LF:
                arg = ngx_array_push(&s->args);
                if (arg == NULL) {
                    return NGX_ERROR;
                }
                arg->len = p - s->arg_start;
                arg->data = s->arg_start;
                s->arg_start = NULL;

                switch (ch) {
                case ' ':
                    state = sw_spaces_before_argument;
                    break;
                case CR:
                    state = sw_almost_done;
                    break;
                case LF:
                    goto done;
                }
                break;

            default:
                break;
            }
            break;

        case sw_almost_done:
            switch (ch) {
            case LF:
                goto done;
            default:
                goto invalid;
            }
        }
    }

    s->buffer->pos = p;
    s->state = state;

    return NGX_AGAIN;

done:

    s->buffer->pos = p + 1;

    if (s->arg_start) {
        arg = ngx_array_push(&s->args);
        if (arg == NULL) {
            return NGX_ERROR;
        }
        arg->len = s->arg_end - s->arg_start;
        arg->data = s->arg_start;
        s->arg_start = NULL;
    }

    s->state = (s->command != NGX_POP3_AUTH) ? sw_start : sw_argument;

    return NGX_OK;

invalid:

    s->state = sw_start;
    s->arg_start = NULL;

    return NGX_MAIL_PARSE_INVALID_COMMAND;
}


ngx_int_t
ngx_mail_imap_parse_command(ngx_mail_session_t *s)
{
    u_char      ch, *p, *c;
    ngx_str_t  *arg;
    enum {
        sw_start = 0,
        sw_spaces_before_command,
        sw_command,
        sw_spaces_before_argument,
        sw_argument,
        sw_backslash,
        sw_literal,
        sw_no_sync_literal_argument,
        sw_start_literal_argument,
        sw_literal_argument,
        sw_end_literal_argument,
        sw_almost_done
    } state;

    state = s->state;

    for (p = s->buffer->pos; p < s->buffer->last; p++) {
        ch = *p;

        switch (state) {

        /* IMAP tag */
        case sw_start:
            switch (ch) {
            case ' ':
                s->tag.len = p - s->buffer->start + 1;
                s->tag.data = s->buffer->start;
                state = sw_spaces_before_command;
                break;
            case CR:
                s->state = sw_start;
                return NGX_MAIL_PARSE_INVALID_COMMAND;
            case LF:
                s->state = sw_start;
                return NGX_MAIL_PARSE_INVALID_COMMAND;
            }
            break;

        case sw_spaces_before_command:
            switch (ch) {
            case ' ':
                break;
            case CR:
                s->state = sw_start;
                return NGX_MAIL_PARSE_INVALID_COMMAND;
            case LF:
                s->state = sw_start;
                return NGX_MAIL_PARSE_INVALID_COMMAND;
            default:
                s->cmd_start = p;
                state = sw_command;
                break;
            }
            break;

        case sw_command:
            if (ch == ' ' || ch == CR || ch == LF) {

                c = s->cmd_start;

                switch (p - c) {

                case 4:
                    if ((c[0] == 'N' || c[0] == 'n')
                        && (c[1] == 'O'|| c[1] == 'o')
                        && (c[2] == 'O'|| c[2] == 'o')
                        && (c[3] == 'P'|| c[3] == 'p'))
                    {
                        s->command = NGX_IMAP_NOOP;

                    } else {
                        goto invalid;
                    }
                    break;

                case 5:
                    if ((c[0] == 'L'|| c[0] == 'l')
                        && (c[1] == 'O'|| c[1] == 'o')
                        && (c[2] == 'G'|| c[2] == 'g')
                        && (c[3] == 'I'|| c[3] == 'i')
                        && (c[4] == 'N'|| c[4] == 'n'))
                    {
                        s->command = NGX_IMAP_LOGIN;

                    } else {
                        goto invalid;
                    }
                    break;

                case 6:
                    if ((c[0] == 'L'|| c[0] == 'l')
                        && (c[1] == 'O'|| c[1] == 'o')
                        && (c[2] == 'G'|| c[2] == 'g')
                        && (c[3] == 'O'|| c[3] == 'o')
                        && (c[4] == 'U'|| c[4] == 'u')
                        && (c[5] == 'T'|| c[5] == 't'))
                    {
                        s->command = NGX_IMAP_LOGOUT;

                    } else {
                        goto invalid;
                    }
                    break;

#if (NGX_MAIL_SSL)
                case 8:
                    if ((c[0] == 'S'|| c[0] == 's')
                        && (c[1] == 'T'|| c[1] == 't')
                        && (c[2] == 'A'|| c[2] == 'a')
                        && (c[3] == 'R'|| c[3] == 'r')
                        && (c[4] == 'T'|| c[4] == 't')
                        && (c[5] == 'T'|| c[5] == 't')
                        && (c[6] == 'L'|| c[6] == 'l')
                        && (c[7] == 'S'|| c[7] == 's'))
                    {
                        s->command = NGX_IMAP_STARTTLS;

                    } else {
                        goto invalid;
                    }
                    break;
#endif

                case 10:
                    if ((c[0] == 'C'|| c[0] == 'c')
                        && (c[1] == 'A'|| c[1] == 'a')
                        && (c[2] == 'P'|| c[2] == 'p')
                        && (c[3] == 'A'|| c[3] == 'a')
                        && (c[4] == 'B'|| c[4] == 'b')
                        && (c[5] == 'I'|| c[5] == 'i')
                        && (c[6] == 'L'|| c[6] == 'l')
                        && (c[7] == 'I'|| c[7] == 'i')
                        && (c[8] == 'T'|| c[8] == 't')
                        && (c[9] == 'Y'|| c[9] == 'y'))
                    {
                        s->command = NGX_IMAP_CAPABILITY;

                    } else {
                        goto invalid;
                    }
                    break;

                case 12:
                    if ((c[0] == 'A'|| c[0] == 'a')
                        && (c[1] == 'U'|| c[1] == 'u')
                        && (c[2] == 'T'|| c[2] == 't')
                        && (c[3] == 'H'|| c[3] == 'h')
                        && (c[4] == 'E'|| c[4] == 'e')
                        && (c[5] == 'N'|| c[5] == 'n')
                        && (c[6] == 'T'|| c[6] == 't')
                        && (c[7] == 'I'|| c[7] == 'i')
                        && (c[8] == 'C'|| c[8] == 'c')
                        && (c[9] == 'A'|| c[9] == 'a')
                        && (c[10] == 'T'|| c[10] == 't')
                        && (c[11] == 'E'|| c[11] == 'e'))
                    {
                        s->command = NGX_IMAP_AUTHENTICATE;

                    } else {
                        goto invalid;
                    }
                    break;

                default:
                    goto invalid;
                }

                switch (ch) {
                case ' ':
                    state = sw_spaces_before_argument;
                    break;
                case CR:
                    state = sw_almost_done;
                    break;
                case LF:
                    goto done;
                }
                break;
            }

            if ((ch < 'A' || ch > 'Z') && (ch < 'a' || ch > 'z')) {
                goto invalid;
            }

            break;

        case sw_spaces_before_argument:
            switch (ch) {
            case ' ':
                break;
            case CR:
                state = sw_almost_done;
                s->arg_end = p;
                break;
            case LF:
                s->arg_end = p;
                goto done;
            case '"':
                if (s->args.nelts <= 2) {
                    s->quoted = 1;
                    s->arg_start = p + 1;
                    state = sw_argument;
                    break;
                }
                goto invalid;
            case '{':
                if (s->args.nelts <= 2) {
                    state = sw_literal;
                    break;
                }
                goto invalid;
            default:
                if (s->args.nelts <= 2) {
                    s->arg_start = p;
                    state = sw_argument;
                    break;
                }
                goto invalid;
            }
            break;

        case sw_argument:
            if (ch == ' ' && s->quoted) {
                break;
            }

            switch (ch) {
            case '"':
                if (!s->quoted) {
                    break;
                }
                s->quoted = 0;
                /* fall through */
            case ' ':
            case CR:
            case LF:
                arg = ngx_array_push(&s->args);
                if (arg == NULL) {
                    return NGX_ERROR;
                }
                arg->len = p - s->arg_start;
                arg->data = s->arg_start;
                s->arg_start = NULL;

                switch (ch) {
                case '"':
                case ' ':
                    state = sw_spaces_before_argument;
                    break;
                case CR:
                    state = sw_almost_done;
                    break;
                case LF:
                    goto done;
                }
                break;
            case '\\':
                if (s->quoted) {
                    s->backslash = 1;
                    state = sw_backslash;
                }
                break;
            }
            break;

        case sw_backslash:
            switch (ch) {
            case CR:
            case LF:
                goto invalid;
            default:
                state = sw_argument;
            }
            break;

        case sw_literal:
            if (ch >= '0' && ch <= '9') {
                s->literal_len = s->literal_len * 10 + (ch - '0');
                break;
            }
            if (ch == '}') {
                state = sw_start_literal_argument;
                break;
            }
            if (ch == '+') {
                state = sw_no_sync_literal_argument;
                break;
            }
            goto invalid;

        case sw_no_sync_literal_argument:
            if (ch == '}') {
                s->no_sync_literal = 1;
                state = sw_start_literal_argument;
                break;
            }
            goto invalid;

        case sw_start_literal_argument:
            switch (ch) {
            case CR:
                break;
            case LF:
                s->buffer->pos = p + 1;
                s->arg_start = p + 1;
                if (s->no_sync_literal == 0) {
                    s->state = sw_literal_argument;
                    return NGX_IMAP_NEXT;
                }
                state = sw_literal_argument;
                s->no_sync_literal = 0;
                break;
            default:
                goto invalid;
            }
            break;

        case sw_literal_argument:
            if (s->literal_len && --s->literal_len) {
                break;
            }

            arg = ngx_array_push(&s->args);
            if (arg == NULL) {
                return NGX_ERROR;
            }
            arg->len = p + 1 - s->arg_start;
            arg->data = s->arg_start;
            s->arg_start = NULL;
            state = sw_end_literal_argument;

            break;

        case sw_end_literal_argument:
            switch (ch) {
            case '{':
                if (s->args.nelts <= 2) {
                    state = sw_literal;
                    break;
                }
                goto invalid;
            case CR:
                state = sw_almost_done;
                break;
            case LF:
                goto done;
            default:
                state = sw_spaces_before_argument;
                break;
            }
            break;

        case sw_almost_done:
            switch (ch) {
            case LF:
                goto done;
            default:
                goto invalid;
            }
        }
    }

    s->buffer->pos = p;
    s->state = state;

    return NGX_AGAIN;

done:

    s->buffer->pos = p + 1;

    if (s->arg_start) {
        arg = ngx_array_push(&s->args);
        if (arg == NULL) {
            return NGX_ERROR;
        }
        arg->len = s->arg_end - s->arg_start;
        arg->data = s->arg_start;

        s->arg_start = NULL;
        s->cmd_start = NULL;
        s->quoted = 0;
        s->no_sync_literal = 0;
        s->literal_len = 0;
    }

    s->state = (s->command != NGX_IMAP_AUTHENTICATE) ? sw_start : sw_argument;

    return NGX_OK;

invalid:

    s->state = sw_start;
    s->quoted = 0;
    s->no_sync_literal = 0;
    s->literal_len = 0;

    return NGX_MAIL_PARSE_INVALID_COMMAND;
}


ngx_int_t
ngx_mail_smtp_parse_command(ngx_mail_session_t *s)
{
    u_char      ch, *p, *c, c0, c1, c2, c3;
    ngx_str_t  *arg;
    enum {
        sw_start = 0,
        sw_command,
        sw_invalid,
        sw_spaces_before_argument,
        sw_argument,
        sw_almost_done
    } state;

    state = s->state;

    for (p = s->buffer->pos; p < s->buffer->last; p++) {
        ch = *p;

        switch (state) {

        /* SMTP command */
        case sw_start:
            s->cmd_start = p;
            state = sw_command;

            /* fall through */

        case sw_command:
            if (ch == ' ' || ch == CR || ch == LF) {
                c = s->cmd_start;

                if (p - c == 4) {

                    c0 = ngx_toupper(c[0]);
                    c1 = ngx_toupper(c[1]);
                    c2 = ngx_toupper(c[2]);
                    c3 = ngx_toupper(c[3]);

                    if (c0 == 'H' && c1 == 'E' && c2 == 'L' && c3 == 'O')
                    {
                        s->command = NGX_SMTP_HELO;

                    } else if (c0 == 'E' && c1 == 'H' && c2 == 'L' && c3 == 'O')
                    {
                        s->command = NGX_SMTP_EHLO;

                    } else if (c0 == 'Q' && c1 == 'U' && c2 == 'I' && c3 == 'T')
                    {
                        s->command = NGX_SMTP_QUIT;

                    } else if (c0 == 'A' && c1 == 'U' && c2 == 'T' && c3 == 'H')
                    {
                        s->command = NGX_SMTP_AUTH;

                    } else if (c0 == 'N' && c1 == 'O' && c2 == 'O' && c3 == 'P')
                    {
                        s->command = NGX_SMTP_NOOP;

                    } else if (c0 == 'M' && c1 == 'A' && c2 == 'I' && c3 == 'L')
                    {
                        s->command = NGX_SMTP_MAIL;

                    } else if (c0 == 'R' && c1 == 'S' && c2 == 'E' && c3 == 'T')
                    {
                        s->command = NGX_SMTP_RSET;

                    } else if (c0 == 'R' && c1 == 'C' && c2 == 'P' && c3 == 'T')
                    {
                        s->command = NGX_SMTP_RCPT;

                    } else if (c0 == 'V' && c1 == 'R' && c2 == 'F' && c3 == 'Y')
                    {
                        s->command = NGX_SMTP_VRFY;

                    } else if (c0 == 'E' && c1 == 'X' && c2 == 'P' && c3 == 'N')
                    {
                        s->command = NGX_SMTP_EXPN;

                    } else if (c0 == 'H' && c1 == 'E' && c2 == 'L' && c3 == 'P')
                    {
                        s->command = NGX_SMTP_HELP;

                    } else {
                        goto invalid;
                    }
#if (NGX_MAIL_SSL)
                } else if (p - c == 8) {

                    if ((c[0] == 'S'|| c[0] == 's')
                        && (c[1] == 'T'|| c[1] == 't')
                        && (c[2] == 'A'|| c[2] == 'a')
                        && (c[3] == 'R'|| c[3] == 'r')
                        && (c[4] == 'T'|| c[4] == 't')
                        && (c[5] == 'T'|| c[5] == 't')
                        && (c[6] == 'L'|| c[6] == 'l')
                        && (c[7] == 'S'|| c[7] == 's'))
                    {
                        s->command = NGX_SMTP_STARTTLS;

                    } else {
                        goto invalid;
                    }
#endif
                } else {
                    goto invalid;
                }

                s->cmd.data = s->cmd_start;
                s->cmd.len = p - s->cmd_start;

                switch (ch) {
                case ' ':
                    state = sw_spaces_before_argument;
                    break;
                case CR:
                    state = sw_almost_done;
                    break;
                case LF:
                    goto done;
                }
                break;
            }

            if ((ch < 'A' || ch > 'Z') && (ch < 'a' || ch > 'z')) {
                goto invalid;
            }

            break;

        case sw_invalid:
            goto invalid;

        case sw_spaces_before_argument:
            switch (ch) {
            case ' ':
                break;
            case CR:
                state = sw_almost_done;
                s->arg_end = p;
                break;
            case LF:
                s->arg_end = p;
                goto done;
            default:
                if (s->args.nelts <= 10) {
                    state = sw_argument;
                    s->arg_start = p;
                    break;
                }
                goto invalid;
            }
            break;

        case sw_argument:
            switch (ch) {
            case ' ':
            case CR:
            case LF:
                arg = ngx_array_push(&s->args);
                if (arg == NULL) {
                    return NGX_ERROR;
                }
                arg->len = p - s->arg_start;
                arg->data = s->arg_start;
                s->arg_start = NULL;

                switch (ch) {
                case ' ':
                    state = sw_spaces_before_argument;
                    break;
                case CR:
                    state = sw_almost_done;
                    break;
                case LF:
                    goto done;
                }
                break;

            default:
                break;
            }
            break;

        case sw_almost_done:
            switch (ch) {
            case LF:
                goto done;
            default:
                goto invalid;
            }
        }
    }

    s->buffer->pos = p;
    s->state = state;

    return NGX_AGAIN;

done:

    s->buffer->pos = p + 1;

    if (s->arg_start) {
        arg = ngx_array_push(&s->args);
        if (arg == NULL) {
            return NGX_ERROR;
        }
        arg->len = s->arg_end - s->arg_start;
        arg->data = s->arg_start;
        s->arg_start = NULL;
    }

    s->state = (s->command != NGX_SMTP_AUTH) ? sw_start : sw_argument;

    return NGX_OK;

invalid:

    s->state = sw_invalid;
    s->arg_start = NULL;

    /* skip invalid command till LF */

    for (p = s->buffer->pos; p < s->buffer->last; p++) {
        if (*p == LF) {
            s->state = sw_start;
            p++;
            break;
        }
    }

    s->buffer->pos = p;

    return NGX_MAIL_PARSE_INVALID_COMMAND;
}


ngx_int_t
ngx_mail_auth_parse(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 == 0) {
        return NGX_MAIL_PARSE_INVALID_COMMAND;
    }

    arg = s->args.elts;

    if (arg[0].len == 5) {

        if (ngx_strncasecmp(arg[0].data, (u_char *) "LOGIN", 5) == 0) {

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

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

            return NGX_MAIL_PARSE_INVALID_COMMAND;
        }

        if (ngx_strncasecmp(arg[0].data, (u_char *) "PLAIN", 5) == 0) {

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

            if (s->args.nelts == 2) {
                return ngx_mail_auth_plain(s, c, 1);
            }
        }

        return NGX_MAIL_PARSE_INVALID_COMMAND;
    }

    if (arg[0].len == 8) {

        if (ngx_strncasecmp(arg[0].data, (u_char *) "CRAM-MD5", 8) == 0) {

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

            return NGX_MAIL_AUTH_CRAM_MD5;
        }

        if (ngx_strncasecmp(arg[0].data, (u_char *) "EXTERNAL", 8) == 0) {

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

            if (s->args.nelts == 2) {
                return ngx_mail_auth_external(s, c, 1);
            }
        }

        return NGX_MAIL_PARSE_INVALID_COMMAND;
    }

    return NGX_MAIL_PARSE_INVALID_COMMAND;
}