[18/27] Lock down TIOCSSERIAL

Message ID	20190325220954.29054-19-matthewgarrett@google.com (mailing list archive)
State	New, archived
Headers	show Return-Path: <linux-security-module-owner@kernel.org> Date: Mon, 25 Mar 2019 15:09:45 -0700 In-Reply-To: <20190325220954.29054-1-matthewgarrett@google.com> Message-Id: <20190325220954.29054-19-matthewgarrett@google.com> Mime-Version: 1.0 References: <20190325220954.29054-1-matthewgarrett@google.com> Subject: [PATCH 18/27] Lock down TIOCSSERIAL From: Matthew Garrett <matthewgarrett@google.com> To: jmorris@namei.org Cc: linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org, dhowells@redhat.com, Greg Kroah-Hartman <gregkh@linuxfoundation.org>, Jiri Slaby <jslaby@suse.com>, linux-serial@vger.kernel.org, Matthew Garrett <matthewgarrett@google.com> Content-Type: text/plain; charset="UTF-8" Sender: owner-linux-security-module@vger.kernel.org Precedence: bulk
Series	[PULL,REQUEST] Lockdown patches for 5.2 \| expand [PULL,REQUEST] Lockdown patches for 5.2 [02/27] Enforce module signatures if the kernel is locked down [03/27] Restrict /dev/{mem,kmem,port} when the kernel is locked down [04/27] kexec_load: Disable at runtime if the kernel is locked down [05/27] Copy secure_boot flag in boot params across kexec reboot [06/27] kexec_file: split KEXEC_VERIFY_SIG into KEXEC_SIG and KEXEC_SIG_FORCE [07/27] kexec_file: Restrict at runtime if the kernel is locked down [08/27] hibernate: Disable when the kernel is locked down [09/27] uswsusp: Disable when the kernel is locked down [10/27] PCI: Lock down BAR access when the kernel is locked down [11/27] x86: Lock down IO port access when the kernel is locked down [12/27] x86/msr: Restrict MSR access when the kernel is locked down [13/27] ACPI: Limit access to custom_method when the kernel is locked down [14/27] acpi: Ignore acpi_rsdp kernel param when the kernel has been locked down [15/27] acpi: Disable ACPI table override if the kernel is locked down [16/27] acpi: Disable APEI error injection if the kernel is locked down [17/27] Prohibit PCMCIA CIS storage when the kernel is locked down [18/27] Lock down TIOCSSERIAL [19/27] Lock down module params that specify hardware parameters (eg. ioport) [20/27] x86/mmiotrace: Lock down the testmmiotrace module [21/27] Lock down /proc/kcore [22/27] Lock down kprobes [23/27] bpf: Restrict kernel image access functions when the kernel is locked down [24/27] Lock down perf [25/27] debugfs: Restrict debugfs when the kernel is locked down [26/27] lockdown: Print current->comm in restriction messages [27/27] kexec: Allow kexec_file() with appropriate IMA policy when locked down

Message ID

20190325220954.29054-19-matthewgarrett@google.com (mailing list archive)

State

New, archived

Headers

Date: Mon, 25 Mar 2019 15:09:45 -0700
In-Reply-To: <20190325220954.29054-1-matthewgarrett@google.com>
Message-Id: <20190325220954.29054-19-matthewgarrett@google.com>
Mime-Version: 1.0
References: <20190325220954.29054-1-matthewgarrett@google.com>
Subject: [PATCH 18/27] Lock down TIOCSSERIAL
From: Matthew Garrett <matthewgarrett@google.com>
To: jmorris@namei.org
Cc: linux-security-module@vger.kernel.org,
        linux-kernel@vger.kernel.org, dhowells@redhat.com,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Jiri Slaby <jslaby@suse.com>, linux-serial@vger.kernel.org,
        Matthew Garrett <matthewgarrett@google.com>
Content-Type: text/plain; charset="UTF-8"
Sender: owner-linux-security-module@vger.kernel.org
Precedence: bulk

Series

[PULL,REQUEST] Lockdown patches for 5.2 | expand

Commit Message

Matthew Garrett March 25, 2019, 10:09 p.m. UTC

From: David Howells <dhowells@redhat.com>

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 <gregkh@linuxfoundation.org>
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Jiri Slaby <jslaby@suse.com>
Cc: linux-serial@vger.kernel.org
Signed-off-by: Matthew Garrett <matthewgarrett@google.com>
---
 drivers/tty/serial/serial_core.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index d4cca5bdaf1c..04534877b575 100644
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -842,6 +842,12 @@  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) &&
+	    kernel_is_locked_down("Using TIOCSSERIAL to change device addresses, irqs and dma channels")) {
+		retval = -EPERM;
+		goto exit;
+	}
+
 	if (!capable(CAP_SYS_ADMIN)) {
 		retval = -EPERM;
 		if (change_irq || change_port ||

[18/27] Lock down TIOCSSERIAL

Commit Message

Patch