From: David Howells <dhowells@redhat.com>
Date: Mon, 18 Feb 2019 12:45:02 +0000 (+0000)
Subject: Lock down perf
X-Git-Tag: archive/raspbian/5.2.17-1+rpi1^2~35
X-Git-Url: https://dgit.raspbian.org/?a=commitdiff_plain;h=1d729dde37f697c3187d4db9495b160b0a42bb5a;p=linux.git

Lock down perf

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

Signed-off-by: David Howells <dhowells@redhat.com>

Gbp-Pq: Topic features/all/lockdown
Gbp-Pq: Name 0026-Lock-down-perf.patch
---

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 1a8eb4dd99b..f30bce79d61 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -10824,6 +10824,11 @@ SYSCALL_DEFINE5(perf_event_open,
 			return -EINVAL;
 	}
 
+	if ((attr.sample_type & PERF_SAMPLE_REGS_INTR) &&
+	    kernel_is_locked_down("PERF_SAMPLE_REGS_INTR"))
+		/* REGS_INTR can leak data, lockdown must prevent this */
+		return -EPERM;
+
 	/* Only privileged users can get physical addresses */
 	if ((attr.sample_type & PERF_SAMPLE_PHYS_ADDR) &&
 	    perf_paranoid_kernel() && !capable(CAP_SYS_ADMIN))