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>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Matthew Garrett <mjg59@google.com>, Jiri Slaby <jslaby@suse.com>,
linux-serial@vger.kernel.org
Subject: Re: [PATCH V34 18/29] Lock down TIOCSSERIAL
Date: Sat, 22 Jun 2019 17:01:05 -0700 [thread overview]
Message-ID: <201906221700.852B22FCE0@keescook> (raw)
In-Reply-To: <20190622000358.19895-19-matthewgarrett@google.com>
On Fri, Jun 21, 2019 at 05:03:47PM -0700, Matthew Garrett wrote:
> From: David Howells <dhowells@redhat.com>
>
> Lock down TIOCSSERIAL as that can be used to change the ioport and irq
> settings on a serial port. This only appears to be an issue for the serial
> drivers that use the core serial code. All other drivers seem to either
> ignore attempts to change port/irq or give an error.
>
> Reported-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Signed-off-by: David Howells <dhowells@redhat.com>
> Signed-off-by: Matthew Garrett <mjg59@google.com>
> cc: Jiri Slaby <jslaby@suse.com>
> Cc: linux-serial@vger.kernel.org
> ---
> drivers/tty/serial/serial_core.c | 5 +++++
> include/linux/security.h | 1 +
> security/lockdown/lockdown.c | 1 +
> 3 files changed, 7 insertions(+)
>
> diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
> index 351843f847c0..a84f231a5df4 100644
> --- a/drivers/tty/serial/serial_core.c
> +++ b/drivers/tty/serial/serial_core.c
> @@ -22,6 +22,7 @@
> #include <linux/serial_core.h>
> #include <linux/delay.h>
> #include <linux/mutex.h>
> +#include <linux/security.h>
>
> #include <linux/irq.h>
> #include <linux/uaccess.h>
> @@ -852,6 +853,10 @@ static int uart_set_info(struct tty_struct *tty, struct tty_port *port,
> new_flags = (__force upf_t)new_info->flags;
> old_custom_divisor = uport->custom_divisor;
>
> + retval = security_locked_down(LOCKDOWN_TIOCSSERIAL);
> + if (retval && (change_port || change_irq))
> + goto exit;
> +
> if (!capable(CAP_SYS_ADMIN)) {
> retval = -EPERM;
> if (change_irq || change_port ||
This should be moved after the capable test. With that fixed:
Reviewed-by: Kees Cook <keescook@chromium.org>
-Kees
> diff --git a/include/linux/security.h b/include/linux/security.h
> index 03c125b277ca..61e3f4a62d16 100644
> --- a/include/linux/security.h
> +++ b/include/linux/security.h
> @@ -91,6 +91,7 @@ enum lockdown_reason {
> LOCKDOWN_MSR,
> LOCKDOWN_ACPI_TABLES,
> LOCKDOWN_PCMCIA_CIS,
> + LOCKDOWN_TIOCSSERIAL,
> LOCKDOWN_INTEGRITY_MAX,
> LOCKDOWN_CONFIDENTIALITY_MAX,
> };
> diff --git a/security/lockdown/lockdown.c b/security/lockdown/lockdown.c
> index 7be3e8fb5847..c89046dc2155 100644
> --- a/security/lockdown/lockdown.c
> +++ b/security/lockdown/lockdown.c
> @@ -27,6 +27,7 @@ static char *lockdown_reasons[LOCKDOWN_CONFIDENTIALITY_MAX+1] = {
> [LOCKDOWN_MSR] = "raw MSR access",
> [LOCKDOWN_ACPI_TABLES] = "modified ACPI tables",
> [LOCKDOWN_PCMCIA_CIS] = "direct PCMCIA CIS storage",
> + [LOCKDOWN_TIOCSSERIAL] = "reconfiguration of serial port IO",
> [LOCKDOWN_INTEGRITY_MAX] = "integrity",
> [LOCKDOWN_CONFIDENTIALITY_MAX] = "confidentiality",
> };
> --
> 2.22.0.410.gd8fdbe21b5-goog
>
--
Kees Cook
next prev parent reply other threads:[~2019-06-23 0:01 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 [this message]
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
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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