Lock down kprobes

Disallow the creation of kprobes when the kernel is locked down by
preventing their registration.  This prevents kprobes from being used to
access kernel memory, either to make modifications or to steal crypto data.

Reported-by: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Gbp-Pq: Topic features/all/lockdown
Gbp-Pq: Name 0024-Lock-down-kprobes.patch

diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 2504c269e6583546b83f9a6b0218d29cb0110332..55c6349a20041cf9597f59bb67bb8aa96c1627c4 100644 (file)
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -1556,6 +1556,9 @@ int register_kprobe(struct kprobe *p)
        struct module *probed_mod;
        kprobe_opcode_t *addr;
 
+       if (kernel_is_locked_down("Use of kprobes"))
+               return -EPERM;
+
        /* Adjust probe address from symbol */
        addr = kprobe_addr(p);
        if (IS_ERR(addr))