[PATCH V35 23/29] bpf: Restrict bpf when kernel lockdown is in confidentiality mode

@@ -118,6 +118,7 @@ enum lockdown_reason {
 	LOCKDOWN_INTEGRITY_MAX,
 	LOCKDOWN_KCORE,
 	LOCKDOWN_KPROBES,
+	LOCKDOWN_BPF_READ,
 	LOCKDOWN_CONFIDENTIALITY_MAX,
 };
 

@@ -142,7 +142,12 @@ BPF_CALL_3(bpf_probe_read, void *, dst, u32, size, const void *, unsafe_ptr)
 {
 	int ret;
 
+	ret = security_locked_down(LOCKDOWN_BPF_READ);
+	if (ret)
+		goto out;
+
 	ret = probe_kernel_read(dst, unsafe_ptr, size);
+out:
 	if (unlikely(ret < 0))
 		memset(dst, 0, size);
 

@@ -569,6 +574,10 @@ BPF_CALL_3(bpf_probe_read_str, void *, dst, u32, size,
 {
 	int ret;
 
+	ret = security_locked_down(LOCKDOWN_BPF_READ);
+	if (ret)
+		goto out;
+
 	/*
 	 * The strncpy_from_unsafe() call will likely not fill the entire
 	 * buffer, but that's okay in this circumstance as we're probing

@@ -579,6 +588,7 @@ BPF_CALL_3(bpf_probe_read_str, void *, dst, u32, size,
 	 * is returned that can be used for bpf_perf_event_output() et al.
 	 */
 	ret = strncpy_from_unsafe(dst, unsafe_ptr, size);
+out:
 	if (unlikely(ret < 0))
 		memset(dst, 0, size);
 

@@ -33,6 +33,7 @@ static char *lockdown_reasons[LOCKDOWN_CONFIDENTIALITY_MAX+1] = {
 	[LOCKDOWN_INTEGRITY_MAX] = "integrity",
 	[LOCKDOWN_KCORE] = "/proc/kcore access",
 	[LOCKDOWN_KPROBES] = "use of kprobes",
+	[LOCKDOWN_BPF_READ] = "use of bpf to read kernel RAM",
 	[LOCKDOWN_CONFIDENTIALITY_MAX] = "confidentiality",
 };