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From: Matthew Garrett <matthewgarrett@google.com>
To: jmorris@namei.org
Cc: linux-security@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-api@vger.kernel.org, David Howells <dhowells@redhat.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Matthew Garrett <mjg59@google.com>, Jiri Slaby <jslaby@suse.com>,
	linux-serial@vger.kernel.org
Subject: [PATCH V33 19/30] Lock down TIOCSSERIAL
Date: Thu, 20 Jun 2019 18:19:30 -0700	[thread overview]
Message-ID: <20190621011941.186255-20-matthewgarrett@google.com> (raw)
In-Reply-To: <20190621011941.186255-1-matthewgarrett@google.com>

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>
Signed-off-by: Matthew Garrett <mjg59@google.com>
cc: Jiri Slaby <jslaby@suse.com>
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 <linux/serial_core.h>
 #include <linux/delay.h>
 #include <linux/mutex.h>
+#include <linux/security.h>
 
 #include <linux/irq.h>
 #include <linux/uaccess.h>
@@ -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


  parent reply	other threads:[~2019-06-21  1:20 UTC|newest]

Thread overview: 58+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-06-21  1:19 [PATCH V33 00/30] Lockdown as an LSM Matthew Garrett
2019-06-21  1:19 ` [PATCH V33 01/30] security: Support early LSMs Matthew Garrett
2019-06-21  3:21   ` Kees Cook
2019-06-21 19:26     ` Matthew Garrett
2019-06-21  5:23   ` Andy Lutomirski
2019-06-21 19:27     ` Matthew Garrett
2019-06-21  1:19 ` [PATCH V33 02/30] security: Add a "locked down" LSM hook Matthew Garrett
2019-06-21  3:23   ` Kees Cook
2019-06-21 19:29     ` Matthew Garrett
2019-06-21  1:19 ` [PATCH V33 03/30] security: Add a static lockdown policy LSM Matthew Garrett
2019-06-21  3:44   ` Kees Cook
2019-06-21 19:37     ` Matthew Garrett
2019-06-21 21:04       ` Matthew Garrett
2019-06-21 22:31   ` Mimi Zohar
2019-06-21  1:19 ` [PATCH V33 04/30] Enforce module signatures if the kernel is locked down Matthew Garrett
2019-06-21  3:46   ` Kees Cook
2019-06-21  1:19 ` [PATCH V33 05/30] Restrict /dev/{mem,kmem,port} when " Matthew Garrett
2019-06-21  1:19 ` [PATCH V33 06/30] kexec_load: Disable at runtime if " Matthew Garrett
2019-06-21  1:19 ` [PATCH V33 07/30] Copy secure_boot flag in boot params across kexec reboot Matthew Garrett
2019-06-21  1:19 ` [PATCH V33 08/30] kexec_file: split KEXEC_VERIFY_SIG into KEXEC_SIG and KEXEC_SIG_FORCE Matthew Garrett
2019-06-21  1:19 ` [PATCH V33 09/30] kexec_file: Restrict at runtime if the kernel is locked down Matthew Garrett
2019-06-21  1:19 ` [PATCH V33 10/30] hibernate: Disable when " Matthew Garrett
2019-06-21  1:19 ` [PATCH V33 11/30] uswsusp: " Matthew Garrett
2019-06-21  1:19 ` [PATCH V33 12/30] PCI: Lock down BAR access " Matthew Garrett
2019-06-21  1:19 ` [PATCH V33 13/30] x86: Lock down IO port " Matthew Garrett
2019-06-21  1:19 ` [PATCH V33 14/30] x86/msr: Restrict MSR " Matthew Garrett
2019-06-21  1:19 ` [PATCH V33 15/30] ACPI: Limit access to custom_method " Matthew Garrett
2019-06-21  1:19 ` [PATCH V33 16/30] acpi: Ignore acpi_rsdp kernel param when the kernel has been " Matthew Garrett
2019-06-21  1:19 ` [PATCH V33 17/30] acpi: Disable ACPI table override if the kernel is " Matthew Garrett
2019-06-21  1:19 ` [PATCH V33 18/30] Prohibit PCMCIA CIS storage when " Matthew Garrett
2019-06-21  1:19 ` Matthew Garrett [this message]
2019-06-21  1:19 ` [PATCH V33 20/30] Lock down module params that specify hardware parameters (eg. ioport) Matthew Garrett
2019-06-21  1:19 ` [PATCH V33 21/30] x86/mmiotrace: Lock down the testmmiotrace module Matthew Garrett
2019-06-26 12:46   ` Steven Rostedt
2019-06-21  1:19 ` [PATCH V33 22/30] Lock down /proc/kcore Matthew Garrett
2019-06-21  1:19 ` [PATCH V33 23/30] Lock down tracing and perf kprobes when in confidentiality mode Matthew Garrett
2019-06-21  1:19 ` [PATCH V33 24/30] bpf: Restrict bpf when kernel lockdown is " Matthew Garrett
2019-06-21  5:22   ` Andy Lutomirski
2019-06-21 20:05     ` Matthew Garrett
2019-06-26 20:22     ` James Morris
2019-06-27  0:57       ` Andy Lutomirski
2019-06-27 14:35         ` Stephen Smalley
2019-06-27 18:06           ` James Morris
2019-06-27 20:16             ` Stephen Smalley
2019-06-27 23:16               ` Matthew Garrett
2019-06-27 23:23                 ` Andy Lutomirski
2019-06-27 23:27           ` Andy Lutomirski
2019-06-28 18:47             ` Matthew Garrett
2019-06-29 23:47               ` Andy Lutomirski
2019-06-21  1:19 ` [PATCH V33 25/30] Lock down perf when " Matthew Garrett
2019-06-21  1:19 ` [PATCH V33 26/30] kexec: Allow kexec_file() with appropriate IMA policy when locked down Matthew Garrett
2019-06-21  1:19 ` [PATCH V33 27/30] lockdown: Print current->comm in restriction messages Matthew Garrett
2019-06-21  4:09   ` Kees Cook
2019-06-21  1:19 ` [PATCH V33 28/30] debugfs: Restrict debugfs when the kernel is locked down Matthew Garrett
2019-06-21  1:19 ` [PATCH V33 29/30] tracefs: Restrict tracefs " Matthew Garrett
2019-06-26 13:07   ` Steven Rostedt
2019-06-26 19:39     ` Matthew Garrett
2019-06-21  1:19 ` [PATCH V33 30/30] efi: Restrict efivar_ssdt_load " Matthew Garrett

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