[V36,24/29] Lock down perf when in confidentiality mode

Message ID	20190718194415.108476-25-matthewgarrett@google.com (mailing list archive)
State	New, archived
Headers	show Return-Path: <linux-security-module-owner@kernel.org> Date: Thu, 18 Jul 2019 12:44:10 -0700 In-Reply-To: <20190718194415.108476-1-matthewgarrett@google.com> Message-Id: <20190718194415.108476-25-matthewgarrett@google.com> Mime-Version: 1.0 References: <20190718194415.108476-1-matthewgarrett@google.com> Subject: [PATCH V36 24/29] Lock down perf when in confidentiality mode 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, David Howells <dhowells@redhat.com>, Matthew Garrett <mjg59@google.com>, Kees Cook <keescook@chromium.org>, Peter Zijlstra <peterz@infradead.org>, Ingo Molnar <mingo@redhat.com>, Arnaldo Carvalho de Melo <acme@kernel.org> Content-Type: text/plain; charset="UTF-8" Sender: owner-linux-security-module@vger.kernel.org Precedence: bulk
Series	security: Add kernel lockdown functionality \| expand [V36,00/29] security: Add kernel lockdown functionality [V36,01/29] security: Support early LSMs [V36,02/29] security: Add a "locked down" LSM hook [V36,03/29] security: Add a static lockdown policy LSM [V36,04/29] Enforce module signatures if the kernel is locked down [V36,05/29] Restrict /dev/{mem,kmem,port} when the kernel is locked down [V36,06/29] kexec_load: Disable at runtime if the kernel is locked down [V36,07/29] Copy secure_boot flag in boot params across kexec reboot [V36,08/29] kexec_file: split KEXEC_VERIFY_SIG into KEXEC_SIG and KEXEC_SIG_FORCE [V36,09/29] kexec_file: Restrict at runtime if the kernel is locked down [V36,10/29] hibernate: Disable when the kernel is locked down [V36,11/29] PCI: Lock down BAR access when the kernel is locked down [V36,12/29] x86: Lock down IO port access when the kernel is locked down [V36,13/29] x86/msr: Restrict MSR access when the kernel is locked down [V36,14/29] ACPI: Limit access to custom_method when the kernel is locked down [V36,15/29] acpi: Ignore acpi_rsdp kernel param when the kernel has been locked down [V36,16/29] acpi: Disable ACPI table override if the kernel is locked down [V36,17/29] Prohibit PCMCIA CIS storage when the kernel is locked down [V36,18/29] Lock down TIOCSSERIAL [V36,19/29] Lock down module params that specify hardware parameters (eg. ioport) [V36,20/29] x86/mmiotrace: Lock down the testmmiotrace module [V36,21/29] Lock down /proc/kcore [V36,22/29] Lock down tracing and perf kprobes when in confidentiality mode [V36,23/29] bpf: Restrict bpf when kernel lockdown is in confidentiality mode [V36,24/29] Lock down perf when in confidentiality mode [V36,25/29] kexec: Allow kexec_file() with appropriate IMA policy when locked down [V36,26/29] debugfs: Restrict debugfs when the kernel is locked down [V36,27/29] tracefs: Restrict tracefs when the kernel is locked down [V36,28/29] efi: Restrict efivar_ssdt_load when the kernel is locked down [V36,29/29] lockdown: Print current->comm in restriction messages

Message ID

20190718194415.108476-25-matthewgarrett@google.com (mailing list archive)

State

New, archived

Headers

Date: Thu, 18 Jul 2019 12:44:10 -0700
In-Reply-To: <20190718194415.108476-1-matthewgarrett@google.com>
Message-Id: <20190718194415.108476-25-matthewgarrett@google.com>
Mime-Version: 1.0
References: <20190718194415.108476-1-matthewgarrett@google.com>
Subject: [PATCH V36 24/29] Lock down perf when in confidentiality mode
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,
        David Howells <dhowells@redhat.com>,
        Matthew Garrett <mjg59@google.com>,
        Kees Cook <keescook@chromium.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@redhat.com>,
        Arnaldo Carvalho de Melo <acme@kernel.org>
Content-Type: text/plain; charset="UTF-8"
Sender: owner-linux-security-module@vger.kernel.org
Precedence: bulk

Series

security: Add kernel lockdown functionality | expand

Commit Message

Matthew Garrett July 18, 2019, 7:44 p.m. UTC

From: David Howells <dhowells@redhat.com>

Disallow the use of certain perf facilities that might allow userspace to
access kernel data.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Matthew Garrett <mjg59@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
---
 include/linux/security.h     | 1 +
 kernel/events/core.c         | 7 +++++++
 security/lockdown/lockdown.c | 1 +
 3 files changed, 9 insertions(+)

diff --git a/include/linux/security.h b/include/linux/security.h
index 8dd1741a52cd..8ef366de70b0 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -119,6 +119,7 @@  enum lockdown_reason {
 	LOCKDOWN_KCORE,
 	LOCKDOWN_KPROBES,
 	LOCKDOWN_BPF_READ,
+	LOCKDOWN_PERF,
 	LOCKDOWN_CONFIDENTIALITY_MAX,
 };
 
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 785d708f8553..738d6f1cf5ec 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -10806,6 +10806,13 @@  SYSCALL_DEFINE5(perf_event_open,
 	    perf_paranoid_kernel() && !capable(CAP_SYS_ADMIN))
 		return -EACCES;
 
+	err = security_locked_down(LOCKDOWN_PERF);
+	if (err && (attr.sample_type & PERF_SAMPLE_REGS_INTR))
+		/* REGS_INTR can leak data, lockdown must prevent this */
+		return err;
+
+	err = 0;
+
 	/*
 	 * In cgroup mode, the pid argument is used to pass the fd
 	 * opened to the cgroup directory in cgroupfs. The cpu argument
diff --git a/security/lockdown/lockdown.c b/security/lockdown/lockdown.c
index 1b89d3e8e54d..fb437a7ef5f2 100644
--- a/security/lockdown/lockdown.c
+++ b/security/lockdown/lockdown.c
@@ -34,6 +34,7 @@  static char *lockdown_reasons[LOCKDOWN_CONFIDENTIALITY_MAX+1] = {
 	[LOCKDOWN_KCORE] = "/proc/kcore access",
 	[LOCKDOWN_KPROBES] = "use of kprobes",
 	[LOCKDOWN_BPF_READ] = "use of bpf to read kernel RAM",
+	[LOCKDOWN_PERF] = "unsafe use of perf",
 	[LOCKDOWN_CONFIDENTIALITY_MAX] = "confidentiality",
 };

[V36,24/29] Lock down perf when in confidentiality mode

Commit Message

Patch