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