Re: [PATCH 22/27] Lock down kprobes
From: Masami Hiramatsu <mhiramat@kernel.org>
Date: 2019-03-26 12:30:05
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On Mon, 25 Mar 2019 15:09:49 -0700 Matthew Garrett [off-list ref] wrote:
From: David Howells <dhowells@redhat.com> 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.
Hmm, if you enforce signature check of modules, those modules should be allowed to use kprobes? I think we should introduce some kind of trust inheritance from signed (trusted) modules. Thank you,
quoted hunk ↗ jump to hunk
Reported-by: Alexei Starovoitov <redacted> Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Matthew Garrett <redacted> Cc: Naveen N. Rao <redacted> Cc: Anil S Keshavamurthy <redacted> Cc: davem@davemloft.net Cc: Masami Hiramatsu <mhiramat@kernel.org> --- kernel/kprobes.c | 3 +++ 1 file changed, 3 insertions(+)diff --git a/kernel/kprobes.c b/kernel/kprobes.c index f4ddfdd2d07e..6f66cca8e2c6 100644 --- a/kernel/kprobes.c +++ b/kernel/kprobes.c@@ -1552,6 +1552,9 @@ 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))-- 2.21.0.392.gf8f6787159e-goog
-- Masami Hiramatsu [off-list ref]