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[209.132.180.67]) by mx.google.com with ESMTP id c12si959012pgq.533.2019.06.20.18.22.14; Thu, 20 Jun 2019 18:22:29 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; dkim=pass header.i=@google.com header.s=20161025 header.b=mwxX56tG; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=google.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726783AbfFUBUp (ORCPT + 99 others); Thu, 20 Jun 2019 21:20:45 -0400 Received: from mail-vs1-f73.google.com ([209.85.217.73]:38080 "EHLO mail-vs1-f73.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726739AbfFUBUg (ORCPT ); Thu, 20 Jun 2019 21:20:36 -0400 Received: by mail-vs1-f73.google.com with SMTP id k10so1582805vso.5 for ; Thu, 20 Jun 2019 18:20:35 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=U3fhGq6r/NgiqaQQyES6rVTVBeVN4SZv/SOjn2ijb/0=; b=mwxX56tGc5bdcrdp7LPWQyAEQAkbcg1Xa55uNakzWLnArZGhBBM8/YfLo+cMRh8DtX vrRS8xRv6wDsAXxkkRDUDDVNLABwTIvD4/R8eu1g/4B6DSNeabRlbKD5wdkCofA6OqW5 o7rwM1e2Ldf/n4PStpf+Oap3yTX6pey52rRx0bREIBZQlH0Ww2HvIWgFDLUON8aYKoFf cammmjj5lURN9Kg8tm6kUiGfHzhJos5AkiV7C8gf92EvHRMDyBjJSyrQ5ou0+kiCOfIx k2fZHvDVdKvEIx5adFMh/J1O/CMWdgiKHgmxhucHEyq/Iu4snxTqdhosWJ74AdacIcvV TaTQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=U3fhGq6r/NgiqaQQyES6rVTVBeVN4SZv/SOjn2ijb/0=; b=Eo3qCweSVBxi1hdutP2o+8f6b5hJ9L6JvpIqEBF05I6yN7YzJx+SFvYjtZL/GF4h4l v61Rw8j9PAV0uJXMWmIO+rqLVHiWR1Qf7XSe+YDEAURGUdiHXia4t4A7cWI0K9fMncdh /MXgUjhSLGEiD0WD4nC1cbJB1HCwYoe675jSg520F9pLggKdMFHItc/ZLbfuyyM3Xt3G AdnLF+4SftQrlEsaNDRkeA2ZgbIw3PUOieM94crmdplo08jlNQCl+vVAKDiCxv+cBEmA kkH7pPFXrKNJmtZM5GzU7l+r6iCzO/F1/OmlCmYwPzqEJs4Ub2QC/tUeToenKAE4rsGR K5mg== X-Gm-Message-State: APjAAAVLhnmJqvuyNSzN2D+dxcxbVHKxYWeNqOXJCkLu1Vj48LVDEbhr w07F7XlQ/XROeb7lgXjPgKlKNVoKGaeAF70Jovd3fA== X-Received: by 2002:ab0:2994:: with SMTP id u20mr5795117uap.114.1561080035406; Thu, 20 Jun 2019 18:20:35 -0700 (PDT) Date: Thu, 20 Jun 2019 18:19:30 -0700 In-Reply-To: <20190621011941.186255-1-matthewgarrett@google.com> Message-Id: <20190621011941.186255-20-matthewgarrett@google.com> Mime-Version: 1.0 References: <20190621011941.186255-1-matthewgarrett@google.com> X-Mailer: git-send-email 2.22.0.410.gd8fdbe21b5-goog Subject: [PATCH V33 19/30] Lock down TIOCSSERIAL From: Matthew Garrett To: jmorris@namei.org Cc: linux-security@vger.kernel.org, linux-kernel@vger.kernel.org, linux-api@vger.kernel.org, David Howells , Greg Kroah-Hartman , Matthew Garrett , Jiri Slaby , linux-serial@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: David Howells Lock down TIOCSSERIAL as that can be used to change the ioport and irq settings on a serial port. This only appears to be an issue for the serial drivers that use the core serial code. All other drivers seem to either ignore attempts to change port/irq or give an error. Reported-by: Greg Kroah-Hartman Signed-off-by: David Howells Signed-off-by: Matthew Garrett cc: Jiri Slaby Cc: linux-serial@vger.kernel.org --- drivers/tty/serial/serial_core.c | 7 +++++++ include/linux/security.h | 1 + security/lockdown/lockdown.c | 1 + 3 files changed, 9 insertions(+) diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c index 351843f847c0..2dbef7dc23f6 100644 --- a/drivers/tty/serial/serial_core.c +++ b/drivers/tty/serial/serial_core.c @@ -22,6 +22,7 @@ #include #include #include +#include #include #include @@ -852,6 +853,12 @@ static int uart_set_info(struct tty_struct *tty, struct tty_port *port, new_flags = (__force upf_t)new_info->flags; old_custom_divisor = uport->custom_divisor; + if ((change_port || change_irq) && + security_is_locked_down(LOCKDOWN_TIOCSSERIAL)) { + retval = -EPERM; + goto exit; + } + if (!capable(CAP_SYS_ADMIN)) { retval = -EPERM; if (change_irq || change_port || diff --git a/include/linux/security.h b/include/linux/security.h index 87c433f1e7db..cb5d74f9b9ff 100644 --- a/include/linux/security.h +++ b/include/linux/security.h @@ -91,6 +91,7 @@ enum lockdown_reason { LOCKDOWN_MSR, LOCKDOWN_ACPI_TABLES, LOCKDOWN_PCMCIA_CIS, + LOCKDOWN_TIOCSSERIAL, LOCKDOWN_INTEGRITY_MAX, LOCKDOWN_CONFIDENTIALITY_MAX, }; diff --git a/security/lockdown/lockdown.c b/security/lockdown/lockdown.c index ced4ddbb36b4..c6456f300220 100644 --- a/security/lockdown/lockdown.c +++ b/security/lockdown/lockdown.c @@ -27,6 +27,7 @@ static char *lockdown_reasons[LOCKDOWN_CONFIDENTIALITY_MAX+1] = { [LOCKDOWN_MSR] = "raw MSR access", [LOCKDOWN_ACPI_TABLES] = "modified ACPI tables", [LOCKDOWN_PCMCIA_CIS] = "direct PCMCIA CIS storage", + [LOCKDOWN_TIOCSSERIAL] = "reconfiguration of serial port IO", [LOCKDOWN_INTEGRITY_MAX] = "integrity", [LOCKDOWN_CONFIDENTIALITY_MAX] = "confidentiality", }; -- 2.22.0.410.gd8fdbe21b5-goog