From: David Howells <dhowe...@redhat.com> Disallow the use of certain perf facilities that might allow userspace to access kernel data.
Signed-off-by: David Howells <dhowe...@redhat.com> Signed-off-by: Matthew Garrett <mj...@google.com> Reviewed-by: Kees Cook <keesc...@chromium.org> Cc: Peter Zijlstra <pet...@infradead.org> Cc: Ingo Molnar <mi...@redhat.com> Cc: Arnaldo Carvalho de Melo <a...@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 d14b89784412..e43c9d001e49 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", }; -- 2.22.0.510.g264f2c817a-goog