From 6dafcdebde58577f4fcb190be46a0eb910cf1b96 Mon Sep 17 00:00:00 2001 From: Maxim Dounin Date: Wed, 19 May 2021 03:13:31 +0300 Subject: [PATCH 1/1] Mail: max_errors directive. Similarly to smtpd_hard_error_limit in Postfix and smtp_max_unknown_commands in Exim, specifies the number of errors after which the connection is closed. --- end of original header --- CVE: CVE-2021-3618 Upstream-Status: Backport https://github.com/nginx/nginx.git commit 173f16f736c10eae46cd15dd861b04b82d91a37a Signed-off-by: Joe Slater --- src/mail/ngx_mail.h | 3 +++ src/mail/ngx_mail_core_module.c | 10 ++++++++++ src/mail/ngx_mail_handler.c | 15 ++++++++++++++- 3 files changed, 27 insertions(+), 1 deletion(-) diff --git a/src/mail/ngx_mail.h b/src/mail/ngx_mail.h index b865a3b9..76cae37a 100644 --- a/src/mail/ngx_mail.h +++ b/src/mail/ngx_mail.h @@ -115,6 +115,8 @@ typedef struct { ngx_msec_t timeout; ngx_msec_t resolver_timeout; + ngx_uint_t max_errors; + ngx_str_t server_name; u_char *file_name; @@ -231,6 +233,7 @@ typedef struct { ngx_uint_t command; ngx_array_t args; + ngx_uint_t errors; ngx_uint_t login_attempt; /* used to parse POP3/IMAP/SMTP command */ diff --git a/src/mail/ngx_mail_core_module.c b/src/mail/ngx_mail_core_module.c index 40831242..115671ca 100644 --- a/src/mail/ngx_mail_core_module.c +++ b/src/mail/ngx_mail_core_module.c @@ -85,6 +85,13 @@ static ngx_command_t ngx_mail_core_commands[] = { offsetof(ngx_mail_core_srv_conf_t, resolver_timeout), NULL }, + { ngx_string("max_errors"), + NGX_MAIL_MAIN_CONF|NGX_MAIL_SRV_CONF|NGX_CONF_TAKE1, + ngx_conf_set_num_slot, + NGX_MAIL_SRV_CONF_OFFSET, + offsetof(ngx_mail_core_srv_conf_t, max_errors), + NULL }, + ngx_null_command }; @@ -163,6 +170,8 @@ ngx_mail_core_create_srv_conf(ngx_conf_t *cf) cscf->timeout = NGX_CONF_UNSET_MSEC; cscf->resolver_timeout = NGX_CONF_UNSET_MSEC; + cscf->max_errors = NGX_CONF_UNSET_UINT; + cscf->resolver = NGX_CONF_UNSET_PTR; cscf->file_name = cf->conf_file->file.name.data; @@ -182,6 +191,7 @@ ngx_mail_core_merge_srv_conf(ngx_conf_t *cf, void *parent, void *child) ngx_conf_merge_msec_value(conf->resolver_timeout, prev->resolver_timeout, 30000); + ngx_conf_merge_uint_value(conf->max_errors, prev->max_errors, 5); ngx_conf_merge_str_value(conf->server_name, prev->server_name, ""); diff --git a/src/mail/ngx_mail_handler.c b/src/mail/ngx_mail_handler.c index 0aaa0e78..71b81512 100644 --- a/src/mail/ngx_mail_handler.c +++ b/src/mail/ngx_mail_handler.c @@ -871,7 +871,20 @@ ngx_mail_read_command(ngx_mail_session_t *s, ngx_connection_t *c) return NGX_MAIL_PARSE_INVALID_COMMAND; } - if (rc == NGX_IMAP_NEXT || rc == NGX_MAIL_PARSE_INVALID_COMMAND) { + if (rc == NGX_MAIL_PARSE_INVALID_COMMAND) { + + s->errors++; + + if (s->errors >= cscf->max_errors) { + ngx_log_error(NGX_LOG_INFO, c->log, 0, + "client sent too many invalid commands"); + s->quit = 1; + } + + return rc; + } + + if (rc == NGX_IMAP_NEXT) { return rc; } -- 2.25.1