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From: Kees Cook <keescook@chromium.org>
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,
	David Howells <dhowells@redhat.com>,
	Matthew Garrett <mjg59@google.com>
Subject: Re: [PATCH V34 21/29] Lock down /proc/kcore
Date: Sat, 22 Jun 2019 17:05:29 -0700	[thread overview]
Message-ID: <201906221705.258B22D1@keescook> (raw)
In-Reply-To: <20190622000358.19895-22-matthewgarrett@google.com>

On Fri, Jun 21, 2019 at 05:03:50PM -0700, Matthew Garrett wrote:
> From: David Howells <dhowells@redhat.com>
> 
> Disallow access to /proc/kcore when the kernel is locked down to prevent
> access to cryptographic data. This is limited to lockdown
> confidentiality mode and is still permitted in integrity mode.
> 
> Signed-off-by: David Howells <dhowells@redhat.com>
> Signed-off-by: Matthew Garrett <mjg59@google.com>
> ---
>  fs/proc/kcore.c              | 5 +++++
>  include/linux/security.h     | 1 +
>  security/lockdown/lockdown.c | 1 +
>  3 files changed, 7 insertions(+)
> 
> diff --git a/fs/proc/kcore.c b/fs/proc/kcore.c
> index d29d869abec1..4e95edb1e282 100644
> --- a/fs/proc/kcore.c
> +++ b/fs/proc/kcore.c
> @@ -31,6 +31,7 @@
>  #include <linux/ioport.h>
>  #include <linux/memory.h>
>  #include <linux/sched/task.h>
> +#include <linux/security.h>
>  #include <asm/sections.h>
>  #include "internal.h"
>  
> @@ -545,6 +546,10 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos)
>  
>  static int open_kcore(struct inode *inode, struct file *filp)
>  {
> +	int ret = security_locked_down(LOCKDOWN_KCORE);
> +
> +	if (ret)
> +		return ret;
>  	if (!capable(CAP_SYS_RAWIO))
>  		return -EPERM;

Another capable() check ordering fix needed. With that:

Reviewed-by: Kees Cook <keescook@chromium.org>

-Kees

>  
> diff --git a/include/linux/security.h b/include/linux/security.h
> index c649cb91e762..3875f6df2ecc 100644
> --- a/include/linux/security.h
> +++ b/include/linux/security.h
> @@ -95,6 +95,7 @@ enum lockdown_reason {
>  	LOCKDOWN_MODULE_PARAMETERS,
>  	LOCKDOWN_MMIOTRACE,
>  	LOCKDOWN_INTEGRITY_MAX,
> +	LOCKDOWN_KCORE,
>  	LOCKDOWN_CONFIDENTIALITY_MAX,
>  };
>  
> diff --git a/security/lockdown/lockdown.c b/security/lockdown/lockdown.c
> index cd86ed9f4d4b..4c9b324dfc55 100644
> --- a/security/lockdown/lockdown.c
> +++ b/security/lockdown/lockdown.c
> @@ -31,6 +31,7 @@ static char *lockdown_reasons[LOCKDOWN_CONFIDENTIALITY_MAX+1] = {
>  	[LOCKDOWN_MODULE_PARAMETERS] = "unsafe module parameters",
>  	[LOCKDOWN_MMIOTRACE] = "unsafe mmio",
>  	[LOCKDOWN_INTEGRITY_MAX] = "integrity",
> +	[LOCKDOWN_KCORE] = "/proc/kcore access",
>  	[LOCKDOWN_CONFIDENTIALITY_MAX] = "confidentiality",
>  };
>  
> -- 
> 2.22.0.410.gd8fdbe21b5-goog
> 

-- 
Kees Cook

  reply	other threads:[~2019-06-23  0:05 UTC|newest]

Thread overview: 80+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-06-22  0:03 [PATCH V34 00/29] Lockdown as an LSM Matthew Garrett
2019-06-22  0:03 ` [PATCH V34 01/29] security: Support early LSMs Matthew Garrett
2019-06-22 23:36   ` Kees Cook
2019-06-22  0:03 ` [PATCH V34 02/29] security: Add a "locked down" LSM hook Matthew Garrett
2019-06-22 23:37   ` Kees Cook
2019-06-22  0:03 ` [PATCH V34 03/29] security: Add a static lockdown policy LSM Matthew Garrett
2019-06-22 23:37   ` Kees Cook
2019-06-22  0:03 ` [PATCH V34 04/29] Enforce module signatures if the kernel is locked down Matthew Garrett
2019-06-22 23:48   ` Kees Cook
2019-06-22  0:03 ` [PATCH V34 05/29] Restrict /dev/{mem,kmem,port} when " Matthew Garrett
2019-06-22 23:52   ` Kees Cook
2019-06-22  0:03 ` [PATCH V34 06/29] kexec_load: Disable at runtime if " Matthew Garrett
2019-06-22 23:52   ` Kees Cook
2019-06-22  0:03 ` [PATCH V34 07/29] Copy secure_boot flag in boot params across kexec reboot Matthew Garrett
2019-06-22 23:53   ` Kees Cook
2019-06-22  0:03 ` [PATCH V34 08/29] kexec_file: split KEXEC_VERIFY_SIG into KEXEC_SIG and KEXEC_SIG_FORCE Matthew Garrett
2019-06-24  2:01   ` Dave Young
2019-06-25  2:35     ` Dave Young
2019-06-22  0:03 ` [PATCH V34 09/29] kexec_file: Restrict at runtime if the kernel is locked down Matthew Garrett
2019-06-22 23:54   ` Kees Cook
2019-06-27  4:59   ` James Morris
2019-06-27 15:28     ` Matthew Garrett
2019-06-27 18:14       ` James Morris
2019-06-27 23:17         ` Matthew Garrett
2019-06-22  0:03 ` [PATCH V34 10/29] hibernate: Disable when " Matthew Garrett
2019-06-22 17:52   ` Pavel Machek
2019-06-24 13:21     ` Jiri Kosina
2019-07-10 15:26       ` Joey Lee
2019-07-11  4:11       ` joeyli
2019-06-22 23:55   ` Kees Cook
2019-06-22  0:03 ` [PATCH V34 11/29] PCI: Lock down BAR access " Matthew Garrett
2019-06-22 23:55   ` Kees Cook
2019-06-22  0:03 ` [PATCH V34 12/29] x86: Lock down IO port " Matthew Garrett
2019-06-22 23:58   ` Kees Cook
2019-06-22  0:03 ` [PATCH V34 13/29] x86/msr: Restrict MSR " Matthew Garrett
2019-06-22  0:03 ` [PATCH V34 14/29] ACPI: Limit access to custom_method " Matthew Garrett
2019-06-22 23:59   ` Kees Cook
2019-06-22  0:03 ` [PATCH V34 15/29] acpi: Ignore acpi_rsdp kernel param when the kernel has been " Matthew Garrett
2019-06-22 23:59   ` Kees Cook
2019-06-22  0:03 ` [PATCH V34 16/29] acpi: Disable ACPI table override if the kernel is " Matthew Garrett
2019-06-23  0:00   ` Kees Cook
2019-06-22  0:03 ` [PATCH V34 17/29] Prohibit PCMCIA CIS storage when " Matthew Garrett
2019-06-23  0:00   ` Kees Cook
2019-06-22  0:03 ` [PATCH V34 18/29] Lock down TIOCSSERIAL Matthew Garrett
2019-06-23  0:01   ` Kees Cook
2019-06-22  0:03 ` [PATCH V34 19/29] Lock down module params that specify hardware parameters (eg. ioport) Matthew Garrett
2019-06-23  0:04   ` Kees Cook
2019-06-27  1:49   ` Daniel Axtens
2019-06-27 15:30     ` Matthew Garrett
2019-06-22  0:03 ` [PATCH V34 20/29] x86/mmiotrace: Lock down the testmmiotrace module Matthew Garrett
2019-06-23  0:04   ` Kees Cook
2019-06-23 11:08   ` Thomas Gleixner
2019-06-22  0:03 ` [PATCH V34 21/29] Lock down /proc/kcore Matthew Garrett
2019-06-23  0:05   ` Kees Cook [this message]
2019-06-22  0:03 ` [PATCH V34 22/29] Lock down tracing and perf kprobes when in confidentiality mode Matthew Garrett
2019-06-23  0:09   ` Kees Cook
2019-06-23  1:57   ` Masami Hiramatsu
2019-06-22  0:03 ` [PATCH V34 23/29] bpf: Restrict bpf when kernel lockdown is " Matthew Garrett
2019-06-23  0:09   ` Kees Cook
2019-06-24 15:15   ` Daniel Borkmann
2019-06-24 19:54     ` Matthew Garrett
2019-06-24 20:08       ` Andy Lutomirski
2019-06-24 20:15         ` Matthew Garrett
2019-06-24 20:59         ` Daniel Borkmann
2019-06-24 21:30           ` Matthew Garrett
2019-06-22  0:03 ` [PATCH V34 24/29] Lock down perf when " Matthew Garrett
2019-06-23  0:12   ` Kees Cook
2019-06-22  0:03 ` [PATCH V34 25/29] kexec: Allow kexec_file() with appropriate IMA policy when locked down Matthew Garrett
2019-06-22  0:03 ` [PATCH V34 26/29] debugfs: Restrict debugfs when the kernel is " Matthew Garrett
2019-06-22  0:03 ` [PATCH V34 27/29] tracefs: Restrict tracefs " Matthew Garrett
2019-06-22  0:03 ` [PATCH V34 28/29] efi: Restrict efivar_ssdt_load " Matthew Garrett
2019-06-23  0:14   ` Kees Cook
2019-06-25 15:00   ` Ard Biesheuvel
2019-06-22  0:03 ` [PATCH V34 29/29] lockdown: Print current->comm in restriction messages Matthew Garrett
2019-06-23  0:25   ` Kees Cook
2019-06-24 23:01 ` [PATCH V34 00/29] Lockdown as an LSM James Morris
2019-06-24 23:47   ` Casey Schaufler
2019-06-24 23:56   ` Matthew Garrett
2019-06-25  6:04     ` James Morris
2019-06-25  8:16   ` John Johansen

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