From: "Rafael J. Wysocki" <rjw@rjwysocki.net>
To: Matthew Garrett <matthewgarrett@google.com>
Cc: jmorris@namei.org, linux-security-module@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-api@vger.kernel.org,
Matthew Garrett <mjg59@srcf.ucam.org>,
Matthew Garrett <mjg59@google.com>,
David Howells <dhowells@redhat.com>,
Kees Cook <keescook@chromium.org>,
linux-acpi@vger.kernel.org
Subject: Re: [PATCH V40 14/29] ACPI: Limit access to custom_method when the kernel is locked down
Date: Wed, 21 Aug 2019 00:07:10 +0200 [thread overview]
Message-ID: <2669800.DxYg3DGudY@kreacher> (raw)
In-Reply-To: <20190820001805.241928-15-matthewgarrett@google.com>
On Tuesday, August 20, 2019 2:17:50 AM CEST Matthew Garrett wrote:
> From: Matthew Garrett <mjg59@srcf.ucam.org>
>
> custom_method effectively allows arbitrary access to system memory, making
> it possible for an attacker to circumvent restrictions on module loading.
> Disable it if the kernel is locked down.
>
> Signed-off-by: Matthew Garrett <mjg59@google.com>
> Signed-off-by: David Howells <dhowells@redhat.com>
> Reviewed-by: Kees Cook <keescook@chromium.org>
> cc: linux-acpi@vger.kernel.org
> Signed-off-by: James Morris <jmorris@namei.org>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> ---
> drivers/acpi/custom_method.c | 6 ++++++
> include/linux/security.h | 1 +
> security/lockdown/lockdown.c | 1 +
> 3 files changed, 8 insertions(+)
>
> diff --git a/drivers/acpi/custom_method.c b/drivers/acpi/custom_method.c
> index b2ef4c2ec955..7031307becd7 100644
> --- a/drivers/acpi/custom_method.c
> +++ b/drivers/acpi/custom_method.c
> @@ -9,6 +9,7 @@
> #include <linux/uaccess.h>
> #include <linux/debugfs.h>
> #include <linux/acpi.h>
> +#include <linux/security.h>
>
> #include "internal.h"
>
> @@ -29,6 +30,11 @@ static ssize_t cm_write(struct file *file, const char __user * user_buf,
>
> struct acpi_table_header table;
> acpi_status status;
> + int ret;
> +
> + ret = security_locked_down(LOCKDOWN_ACPI_TABLES);
> + if (ret)
> + return ret;
>
> if (!(*ppos)) {
> /* parse the table header to get the table length */
> diff --git a/include/linux/security.h b/include/linux/security.h
> index 010637a79eac..390e39395112 100644
> --- a/include/linux/security.h
> +++ b/include/linux/security.h
> @@ -110,6 +110,7 @@ enum lockdown_reason {
> LOCKDOWN_PCI_ACCESS,
> LOCKDOWN_IOPORT,
> LOCKDOWN_MSR,
> + LOCKDOWN_ACPI_TABLES,
> LOCKDOWN_INTEGRITY_MAX,
> LOCKDOWN_CONFIDENTIALITY_MAX,
> };
> diff --git a/security/lockdown/lockdown.c b/security/lockdown/lockdown.c
> index b1c1c72440d5..6d44db0ddffa 100644
> --- a/security/lockdown/lockdown.c
> +++ b/security/lockdown/lockdown.c
> @@ -25,6 +25,7 @@ static char *lockdown_reasons[LOCKDOWN_CONFIDENTIALITY_MAX+1] = {
> [LOCKDOWN_PCI_ACCESS] = "direct PCI access",
> [LOCKDOWN_IOPORT] = "raw io port access",
> [LOCKDOWN_MSR] = "raw MSR access",
> + [LOCKDOWN_ACPI_TABLES] = "modifying ACPI tables",
> [LOCKDOWN_INTEGRITY_MAX] = "integrity",
> [LOCKDOWN_CONFIDENTIALITY_MAX] = "confidentiality",
> };
>
next prev parent reply other threads:[~2019-08-20 22:07 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-20 0:17 [PATCH V40 00/29] Add kernel lockdown functionality Matthew Garrett
2019-08-20 0:17 ` [PATCH V40 01/29] security: Support early LSMs Matthew Garrett
2019-08-20 0:17 ` [PATCH V40 02/29] security: Add a "locked down" LSM hook Matthew Garrett
2019-08-20 0:17 ` [PATCH V40 03/29] security: Add a static lockdown policy LSM Matthew Garrett
2019-08-20 0:17 ` [PATCH V40 04/29] lockdown: Enforce module signatures if the kernel is locked down Matthew Garrett
2019-08-20 0:17 ` [PATCH V40 05/29] lockdown: Restrict /dev/{mem,kmem,port} when " Matthew Garrett
2019-08-20 0:17 ` [PATCH V40 06/29] kexec_load: Disable at runtime if " Matthew Garrett
2019-08-20 0:17 ` [PATCH V40 07/29] lockdown: Copy secure_boot flag in boot params across kexec reboot Matthew Garrett
2019-08-20 0:17 ` [PATCH V40 08/29] kexec_file: split KEXEC_VERIFY_SIG into KEXEC_SIG and KEXEC_SIG_FORCE Matthew Garrett
2019-08-30 14:26 ` Philipp Rudo
2019-08-20 0:17 ` [PATCH V40 09/29] kexec_file: Restrict at runtime if the kernel is locked down Matthew Garrett
2019-08-20 0:17 ` [PATCH V40 10/29] hibernate: Disable when " Matthew Garrett
2019-08-20 21:43 ` Rafael J. Wysocki
2019-08-25 9:51 ` Pavel Machek
2019-08-20 0:17 ` [PATCH V40 11/29] PCI: Lock down BAR access " Matthew Garrett
2019-08-20 19:45 ` Bjorn Helgaas
2019-08-20 21:04 ` Matthew Garrett
2019-08-20 0:17 ` [PATCH V40 12/29] x86: Lock down IO port " Matthew Garrett
2022-01-05 6:25 ` Kai-Heng Feng
2022-01-05 6:48 ` Matthew Garrett
2022-01-05 6:57 ` Kai-Heng Feng
2022-01-05 7:20 ` Matthew Garrett
2022-01-05 10:05 ` Kai-Heng Feng
2022-01-05 10:14 ` Matthew Garrett
2019-08-20 0:17 ` [PATCH V40 13/29] x86/msr: Restrict MSR " Matthew Garrett
2019-08-20 0:17 ` [PATCH V40 14/29] ACPI: Limit access to custom_method " Matthew Garrett
2019-08-20 22:07 ` Rafael J. Wysocki [this message]
2019-08-20 0:17 ` [PATCH V40 15/29] acpi: Ignore acpi_rsdp kernel param when the kernel has been " Matthew Garrett
2019-08-20 22:08 ` Rafael J. Wysocki
2019-08-20 0:17 ` [PATCH V40 16/29] acpi: Disable ACPI table override if the kernel is " Matthew Garrett
2019-08-20 22:08 ` Rafael J. Wysocki
2019-08-20 0:17 ` [PATCH V40 17/29] lockdown: Prohibit PCMCIA CIS storage when " Matthew Garrett
2019-08-20 0:17 ` [PATCH V40 18/29] lockdown: Lock down TIOCSSERIAL Matthew Garrett
2019-08-20 0:17 ` [PATCH V40 19/29] lockdown: Lock down module params that specify hardware parameters (eg. ioport) Matthew Garrett
2019-08-20 16:39 ` Jessica Yu
2019-08-20 0:17 ` [PATCH V40 20/29] x86/mmiotrace: Lock down the testmmiotrace module Matthew Garrett
2019-08-20 0:17 ` [PATCH V40 21/29] lockdown: Lock down /proc/kcore Matthew Garrett
2019-08-20 0:17 ` [PATCH V40 22/29] lockdown: Lock down tracing and perf kprobes when in confidentiality mode Matthew Garrett
2019-08-20 0:17 ` [PATCH V40 23/29] bpf: Restrict bpf when kernel lockdown is " Matthew Garrett
2019-08-20 0:18 ` [PATCH V40 24/29] lockdown: Lock down perf when " Matthew Garrett
2019-08-20 0:18 ` [PATCH V40 25/29] kexec: Allow kexec_file() with appropriate IMA policy when locked down Matthew Garrett
2019-08-20 0:18 ` [PATCH V40 26/29] debugfs: Restrict debugfs when the kernel is " Matthew Garrett
2019-08-20 0:18 ` [PATCH V40 27/29] tracefs: Restrict tracefs " Matthew Garrett
2019-08-20 0:18 ` [PATCH V40 28/29] efi: Restrict efivar_ssdt_load " Matthew Garrett
2019-08-20 0:18 ` [PATCH V40 29/29] lockdown: Print current->comm in restriction messages Matthew Garrett
2019-08-20 6:45 ` [PATCH V40 00/29] Add kernel lockdown functionality James Morris
2019-08-30 16:28 ` [PATCH V40 03/29] security: Add a static lockdown policy LSM David Howells
2019-09-04 16:51 ` Matthew Garrett
2019-09-10 10:06 ` Matthew Garrett
2019-08-30 16:31 ` [PATCH V40 04/29] lockdown: Enforce module signatures if the kernel is locked down David Howells
2019-09-04 16:57 ` Matthew Garrett
2019-08-30 16:32 ` [PATCH V40 23/29] bpf: Restrict bpf when kernel lockdown is in confidentiality mode David Howells
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