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
Subject: [PATCH 04/27] Restrict /dev/{mem,kmem,port} when the kernel is locked down
Date: Thu, 28 Feb 2019 15:11:40 -0800 [thread overview]
Message-ID: <20190228231203.212359-4-matthewgarrett@google.com> (raw)
In-Reply-To: <20190228231203.212359-1-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: Matthew Garrett <mjg59@srcf.ucam.org>
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: "Lee, Chun-Yi" <jlee@suse.com>
---
drivers/char/mem.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/drivers/char/mem.c b/drivers/char/mem.c
index b08dc50f9f26..0a2f2e75d5f4 100644
--- a/drivers/char/mem.c
+++ b/drivers/char/mem.c
@@ -786,6 +786,8 @@ static loff_t memory_lseek(struct file *file, loff_t offset, int orig)
static int open_port(struct inode *inode, struct file *filp)
{
+ if (kernel_is_locked_down("/dev/mem,kmem,port"))
+ return -EPERM;
return capable(CAP_SYS_RAWIO) ? 0 : -EPERM;
}
--
2.21.0.352.gf09ad66450-goog
next prev parent reply other threads:[~2019-02-28 23:12 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-28 21:28 [PULL REQUEST] Lock down patches Matthew Garrett
2019-02-28 22:20 ` Mimi Zohar
2019-02-28 23:13 ` Matthew Garrett
2019-03-01 0:05 ` Mimi Zohar
2019-03-01 1:01 ` Matthew Garrett
2019-03-01 1:44 ` Mimi Zohar
2019-03-01 3:33 ` Matthew Garrett
2019-03-01 4:16 ` Mimi Zohar
2019-02-28 22:44 ` [PATCH 01/27] Add the ability to lock down access to the running kernel image Matthew Garrett
2019-02-28 22:44 ` [PATCH 02/27] Add a SysRq option to lift kernel lockdown Matthew Garrett
2019-02-28 23:10 ` [PATCH 01/27] Add the ability to lock down access to the running kernel image Matthew Garrett
2019-02-28 23:10 ` [PATCH 02/27] Add a SysRq option to lift kernel lockdown Matthew Garrett
2019-02-28 23:11 ` [PATCH 01/27] Add the ability to lock down access to the running kernel image Matthew Garrett
2019-02-28 23:11 ` [PATCH 02/27] Add a SysRq option to lift kernel lockdown Matthew Garrett
2019-02-28 23:11 ` [PATCH 01/27] Add the ability to lock down access to the running kernel image Matthew Garrett
2019-02-28 23:11 ` [PATCH 02/27] Add a SysRq option to lift kernel lockdown Matthew Garrett
2019-02-28 23:11 ` [PATCH 03/27] Enforce module signatures if the kernel is locked down Matthew Garrett
2019-02-28 23:11 ` Matthew Garrett [this message]
2019-02-28 23:11 ` [PATCH 05/27] kexec_load: Disable at runtime " Matthew Garrett
2019-02-28 23:11 ` [PATCH 06/27] Copy secure_boot flag in boot params across kexec reboot Matthew Garrett
2019-02-28 23:11 ` [PATCH 07/27] kexec_file: split KEXEC_VERIFY_SIG into KEXEC_SIG and KEXEC_SIG_FORCE Matthew Garrett
2019-02-28 23:11 ` [PATCH 08/27] kexec_file: Restrict at runtime if the kernel is locked down Matthew Garrett
2019-03-01 2:05 ` Mimi Zohar
2019-02-28 23:11 ` [PATCH 09/27] hibernate: Disable when " Matthew Garrett
2019-03-19 22:15 ` Pavel Machek
2019-02-28 23:11 ` [PATCH 10/27] uswsusp: " Matthew Garrett
2019-02-28 23:11 ` [PATCH 11/27] PCI: Lock down BAR access " Matthew Garrett
2019-02-28 23:11 ` [PATCH 12/27] x86: Lock down IO port " Matthew Garrett
2019-02-28 23:11 ` [PATCH 13/27] x86/msr: Restrict MSR " Matthew Garrett
2019-02-28 23:11 ` [PATCH 14/27] ACPI: Limit access to custom_method " Matthew Garrett
2019-02-28 23:11 ` [PATCH 15/27] acpi: Ignore acpi_rsdp kernel param when the kernel has been " Matthew Garrett
2019-02-28 23:11 ` [PATCH 16/27] acpi: Disable ACPI table override if the kernel is " Matthew Garrett
2019-02-28 23:11 ` [PATCH 17/27] acpi: Disable APEI error injection " Matthew Garrett
2019-02-28 23:11 ` [PATCH 18/27] Prohibit PCMCIA CIS storage when " Matthew Garrett
2019-02-28 23:11 ` [PATCH 19/27] Lock down TIOCSSERIAL Matthew Garrett
2019-02-28 23:11 ` [PATCH 20/27] Lock down module params that specify hardware parameters (eg. ioport) Matthew Garrett
2019-02-28 23:11 ` [PATCH 21/27] x86/mmiotrace: Lock down the testmmiotrace module Matthew Garrett
2019-02-28 23:11 ` [PATCH 22/27] Lock down /proc/kcore Matthew Garrett
2019-02-28 23:11 ` [PATCH 23/27] Lock down kprobes Matthew Garrett
2019-02-28 23:12 ` [PATCH 24/27] bpf: Restrict kernel image access functions when the kernel is locked down Matthew Garrett
2019-02-28 23:12 ` [PATCH 25/27] Lock down perf Matthew Garrett
2019-02-28 23:12 ` [PATCH 26/27] debugfs: Restrict debugfs when the kernel is locked down Matthew Garrett
2019-02-28 23:12 ` [PATCH 27/27] lockdown: Print current->comm in restriction messages Matthew Garrett
2019-02-28 23:24 ` [PULL REQUEST] Lock down patches Randy Dunlap
2019-03-04 22:10 ` Matthew Garrett
2019-03-06 23:58 [PULL REQUEST] Kernel lockdown patches for 5.2 Matthew Garrett
2019-03-06 23:58 ` [PATCH 04/27] Restrict /dev/{mem,kmem,port} when the kernel is locked down Matthew Garrett
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20190228231203.212359-4-matthewgarrett@google.com \
--to=matthewgarrett@google.com \
--cc=dhowells@redhat.com \
--cc=jmorris@namei.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-security-module@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).