From: David Howells <dhowells@redhat.com>
Date: Mon, 19 Aug 2019 17:17:58 -0700
Subject: lockdown: Lock down tracing and perf kprobes when in confidentiality
mode
Patch-mainline: v5.4-rc1
Git-commit: a94549dd87f5ea4ca50fee493df08a2dc6256b53
References: jsc#SLE-9870
Disallow the creation of perf and ftrace kprobes when the kernel is
locked down in confidentiality mode by preventing their registration.
This prevents kprobes from being used to access kernel memory to steal
crypto data, but continues to allow the use of kprobes from signed
modules.
Reported-by: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Matthew Garrett <mjg59@google.com>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Cc: Naveen N. Rao <naveen.n.rao@linux.ibm.com>
Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Cc: davem@davemloft.net
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: James Morris <jmorris@namei.org>
Acked-by: Lee, Chun-Yi <jlee@suse.com>
---
include/linux/security.h | 1 +
kernel/trace/trace_kprobe.c | 5 +++++
security/lockdown/lockdown.c | 1 +
3 files changed, 7 insertions(+)
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -117,6 +117,7 @@ enum lockdown_reason {
LOCKDOWN_MMIOTRACE,
LOCKDOWN_INTEGRITY_MAX,
LOCKDOWN_KCORE,
+ LOCKDOWN_KPROBES,
LOCKDOWN_CONFIDENTIALITY_MAX,
};
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -11,6 +11,7 @@
#include <linux/uaccess.h>
#include <linux/rculist.h>
#include <linux/error-injection.h>
+#include <linux/security.h>
#include <asm/setup.h> /* for COMMAND_LINE_SIZE */
@@ -389,6 +390,10 @@ static int __register_trace_kprobe(struc
{
int i, ret;
+ ret = security_locked_down(LOCKDOWN_KPROBES);
+ if (ret)
+ return ret;
+
if (trace_kprobe_is_registered(tk))
return -EINVAL;
--- a/security/lockdown/lockdown.c
+++ b/security/lockdown/lockdown.c
@@ -32,6 +32,7 @@ static char *lockdown_reasons[LOCKDOWN_C
[LOCKDOWN_MMIOTRACE] = "unsafe mmio",
[LOCKDOWN_INTEGRITY_MAX] = "integrity",
[LOCKDOWN_KCORE] = "/proc/kcore access",
+ [LOCKDOWN_KPROBES] = "use of kprobes",
[LOCKDOWN_CONFIDENTIALITY_MAX] = "confidentiality",
};