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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>,
	Thomas Gleixner <tglx@linutronix.de>,
	Matthew Garrett <mjg59@google.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	Ingo Molnar <mingo@kernel.org>, "H. Peter Anvin" <hpa@zytor.com>,
	x86@kernel.org
Subject: [PATCH V33 21/30] x86/mmiotrace: Lock down the testmmiotrace module
Date: Thu, 20 Jun 2019 18:19:32 -0700	[thread overview]
Message-ID: <20190621011941.186255-22-matthewgarrett@google.com> (raw)
In-Reply-To: <20190621011941.186255-1-matthewgarrett@google.com>

From: David Howells <dhowells@redhat.com>

The testmmiotrace module shouldn't be permitted when the kernel is locked
down as it can be used to arbitrarily read and write MMIO space. This is
a runtime check rather than buildtime in order to allow configurations
where the same kernel may be run in both locked down or permissive modes
depending on local policy.

Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: David Howells <dhowells@redhat.com
Signed-off-by: Matthew Garrett <mjg59@google.com>
cc: Thomas Gleixner <tglx@linutronix.de>
cc: Steven Rostedt <rostedt@goodmis.org>
cc: Ingo Molnar <mingo@kernel.org>
cc: "H. Peter Anvin" <hpa@zytor.com>
cc: x86@kernel.org
---
 arch/x86/mm/testmmiotrace.c  | 3 +++
 include/linux/security.h     | 1 +
 security/lockdown/lockdown.c | 1 +
 3 files changed, 5 insertions(+)

diff --git a/arch/x86/mm/testmmiotrace.c b/arch/x86/mm/testmmiotrace.c
index f6ae6830b341..a6b204f9f505 100644
--- a/arch/x86/mm/testmmiotrace.c
+++ b/arch/x86/mm/testmmiotrace.c
@@ -115,6 +115,9 @@ static int __init init(void)
 {
 	unsigned long size = (read_far) ? (8 << 20) : (16 << 10);
 
+	if (security_is_locked_down(LOCKDOWN_MMIOTRACE))
+		return -EPERM;
+
 	if (mmio_address == 0) {
 		pr_err("you have to use the module argument mmio_address.\n");
 		pr_err("DO NOT LOAD THIS MODULE UNLESS YOU REALLY KNOW WHAT YOU ARE DOING!\n");
diff --git a/include/linux/security.h b/include/linux/security.h
index 47ca04ac00f6..89b7adfae525 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -93,6 +93,7 @@ enum lockdown_reason {
 	LOCKDOWN_PCMCIA_CIS,
 	LOCKDOWN_TIOCSSERIAL,
 	LOCKDOWN_MODULE_PARAMETERS,
+	LOCKDOWN_MMIOTRACE,
 	LOCKDOWN_INTEGRITY_MAX,
 	LOCKDOWN_CONFIDENTIALITY_MAX,
 };
diff --git a/security/lockdown/lockdown.c b/security/lockdown/lockdown.c
index 0788d4805449..215615e67237 100644
--- a/security/lockdown/lockdown.c
+++ b/security/lockdown/lockdown.c
@@ -29,6 +29,7 @@ static char *lockdown_reasons[LOCKDOWN_CONFIDENTIALITY_MAX+1] = {
 	[LOCKDOWN_PCMCIA_CIS] = "direct PCMCIA CIS storage",
 	[LOCKDOWN_TIOCSSERIAL] = "reconfiguration of serial port IO",
 	[LOCKDOWN_MODULE_PARAMETERS] = "unsafe module parameters",
+	[LOCKDOWN_MMIOTRACE] = "unsafe mmio",
 	[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 ` [PATCH V33 19/30] Lock down TIOCSSERIAL Matthew Garrett
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 ` Matthew Garrett [this message]
2019-06-26 12:46   ` [PATCH V33 21/30] x86/mmiotrace: Lock down the testmmiotrace module 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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