[PATCH 23/24] Lock down perf

[David Howells]

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

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

 kernel/events/core.c |    5 +++++
 1 file changed, 5 insertions(+)

diff --git a/kernel/events/core.c b/kernel/events/core.c
index fc1c330c6bd6..1922f2e0980a 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -10407,6 +10407,11 @@ 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))