From: Matthew Garrett <matthewgarrett@google.com>
To: jmorris@namei.org
Cc: linux-security-module@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-api@vger.kernel.org,
Matthew Garrett <mjg59@srcf.ucam.org>,
David Howells <dhowells@redhat.com>,
Matthew Garrett <mjg59@google.com>,
Kees Cook <keescook@chromium.org>,
x86@kernel.org
Subject: [PATCH V37 05/29] Restrict /dev/{mem,kmem,port} when the kernel is locked down
Date: Wed, 31 Jul 2019 15:15:53 -0700 [thread overview]
Message-ID: <20190731221617.234725-6-matthewgarrett@google.com> (raw)
In-Reply-To: <20190731221617.234725-1-matthewgarrett@google.com>
From: Matthew Garrett <mjg59@srcf.ucam.org>
Allowing users to read and write to core kernel memory makes it possible
for the kernel to be subverted, avoiding module loading restrictions, and
also to steal cryptographic information.
Disallow /dev/mem and /dev/kmem from being opened this when the kernel has
been locked down to prevent this.
Also disallow /dev/port from being opened to prevent raw ioport access and
thus DMA from being used to accomplish the same thing.
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Matthew Garrett <mjg59@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Cc: x86@kernel.org
---
drivers/char/mem.c | 7 +++++--
include/linux/security.h | 1 +
security/lockdown/lockdown.c | 1 +
3 files changed, 7 insertions(+), 2 deletions(-)
diff --git a/drivers/char/mem.c b/drivers/char/mem.c
index b08dc50f9f26..d0148aee1aab 100644
--- a/drivers/char/mem.c
+++ b/drivers/char/mem.c
@@ -29,8 +29,8 @@
#include <linux/export.h>
#include <linux/io.h>
#include <linux/uio.h>
-
#include <linux/uaccess.h>
+#include <linux/security.h>
#ifdef CONFIG_IA64
# include <linux/efi.h>
@@ -786,7 +786,10 @@ static loff_t memory_lseek(struct file *file, loff_t offset, int orig)
static int open_port(struct inode *inode, struct file *filp)
{
- return capable(CAP_SYS_RAWIO) ? 0 : -EPERM;
+ if (!capable(CAP_SYS_RAWIO))
+ return -EPERM;
+
+ return security_locked_down(LOCKDOWN_DEV_MEM);
}
#define zero_lseek null_lseek
diff --git a/include/linux/security.h b/include/linux/security.h
index 8e70063074a1..9458152601b5 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -104,6 +104,7 @@ enum lsm_event {
enum lockdown_reason {
LOCKDOWN_NONE,
LOCKDOWN_MODULE_SIGNATURE,
+ LOCKDOWN_DEV_MEM,
LOCKDOWN_INTEGRITY_MAX,
LOCKDOWN_CONFIDENTIALITY_MAX,
};
diff --git a/security/lockdown/lockdown.c b/security/lockdown/lockdown.c
index 2c53fd9f5c9b..d2ef29d9f0b2 100644
--- a/security/lockdown/lockdown.c
+++ b/security/lockdown/lockdown.c
@@ -19,6 +19,7 @@ static enum lockdown_reason kernel_locked_down;
static char *lockdown_reasons[LOCKDOWN_CONFIDENTIALITY_MAX+1] = {
[LOCKDOWN_NONE] = "none",
[LOCKDOWN_MODULE_SIGNATURE] = "unsigned module loading",
+ [LOCKDOWN_DEV_MEM] = "/dev/mem,kmem,port",
[LOCKDOWN_INTEGRITY_MAX] = "integrity",
[LOCKDOWN_CONFIDENTIALITY_MAX] = "confidentiality",
};
--
2.22.0.770.g0f2c4a37fd-goog
next prev parent reply other threads:[~2019-07-31 22:19 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-31 22:15 [PATCH V37 00/29] security: Add support for locking down the kernel Matthew Garrett
2019-07-31 22:15 ` [PATCH V37 01/29] security: Support early LSMs Matthew Garrett
2019-07-31 22:15 ` [PATCH V37 02/29] security: Add a "locked down" LSM hook Matthew Garrett
2019-07-31 22:15 ` [PATCH V37 03/29] security: Add a static lockdown policy LSM Matthew Garrett
2019-07-31 22:15 ` [PATCH V37 04/29] Enforce module signatures if the kernel is locked down Matthew Garrett
2019-08-01 14:21 ` Jessica Yu
2019-08-01 20:42 ` Matthew Garrett
2019-08-08 10:01 ` Jessica Yu
2019-08-08 18:31 ` Matthew Garrett
2019-08-08 22:43 ` James Morris
2019-08-09 20:59 ` [PATCH V39] " Matthew Garrett
2019-07-31 22:15 ` Matthew Garrett [this message]
2019-07-31 22:15 ` [PATCH V37 06/29] kexec_load: Disable at runtime " Matthew Garrett
2019-07-31 22:15 ` [PATCH V37 07/29] Copy secure_boot flag in boot params across kexec reboot Matthew Garrett
2019-07-31 22:15 ` [PATCH V37 08/29] kexec_file: split KEXEC_VERIFY_SIG into KEXEC_SIG and KEXEC_SIG_FORCE Matthew Garrett
2019-07-31 22:15 ` [PATCH V37 09/29] kexec_file: Restrict at runtime if the kernel is locked down Matthew Garrett
2019-07-31 22:15 ` [PATCH V37 10/29] hibernate: Disable when " Matthew Garrett
2019-07-31 22:15 ` [PATCH V37 11/29] PCI: Lock down BAR access " Matthew Garrett
2019-07-31 22:16 ` [PATCH V37 12/29] x86: Lock down IO port " Matthew Garrett
2019-07-31 22:16 ` [PATCH V37 13/29] x86/msr: Restrict MSR " Matthew Garrett
2019-07-31 22:16 ` [PATCH V37 14/29] ACPI: Limit access to custom_method " Matthew Garrett
2019-07-31 22:16 ` [PATCH V37 15/29] acpi: Ignore acpi_rsdp kernel param when the kernel has been " Matthew Garrett
2019-07-31 22:16 ` [PATCH V37 16/29] acpi: Disable ACPI table override if the kernel is " Matthew Garrett
2019-07-31 22:16 ` [PATCH V37 17/29] Prohibit PCMCIA CIS storage when " Matthew Garrett
2019-07-31 22:16 ` [PATCH V37 18/29] Lock down TIOCSSERIAL Matthew Garrett
2019-07-31 22:16 ` [PATCH V37 19/29] Lock down module params that specify hardware parameters (eg. ioport) Matthew Garrett
2019-08-01 16:19 ` Jessica Yu
2019-08-01 20:44 ` Matthew Garrett
2019-07-31 22:16 ` [PATCH V37 20/29] x86/mmiotrace: Lock down the testmmiotrace module Matthew Garrett
2019-07-31 22:16 ` [PATCH V37 21/29] Lock down /proc/kcore Matthew Garrett
2019-07-31 22:16 ` [PATCH V37 22/29] Lock down tracing and perf kprobes when in confidentiality mode Matthew Garrett
2019-07-31 22:16 ` [PATCH V37 23/29] bpf: Restrict bpf when kernel lockdown is " Matthew Garrett
2019-07-31 22:16 ` [PATCH V37 24/29] Lock down perf when " Matthew Garrett
2019-07-31 22:16 ` [PATCH V37 25/29] kexec: Allow kexec_file() with appropriate IMA policy when locked down Matthew Garrett
2019-07-31 22:16 ` [PATCH V37 26/29] debugfs: Restrict debugfs when the kernel is " Matthew Garrett
2019-07-31 22:16 ` [PATCH V37 27/29] tracefs: Restrict tracefs " Matthew Garrett
[not found] ` <CGME20190813061053eucas1p1b6945259d9663b743e7cb32521d041e7@eucas1p1.samsung.com>
2019-08-13 6:10 ` Marek Szyprowski
[not found] ` <CGME20190813072111eucas1p2b87f3f8d16c22a0a3d024bc5ebcc8bcc@eucas1p2.samsung.com>
2019-08-13 7:21 ` Marek Szyprowski
[not found] ` <CGME20190814061246eucas1p128cae99a14f27bc79fa2aa72084a0413@eucas1p1.samsung.com>
2019-08-14 6:12 ` [PATCH] tracefs: Fix NULL pointer dereference when no lockdown is used Marek Szyprowski
2019-07-31 22:16 ` [PATCH V37 28/29] efi: Restrict efivar_ssdt_load when the kernel is locked down Matthew Garrett
2019-07-31 22:16 ` [PATCH V37 29/29] lockdown: Print current->comm in restriction messages Matthew Garrett
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