| Message ID | 20190820001805.241928-24-matthewgarrett@google.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Add kernel lockdown functionality | expand |
Matthew Garrett <matthewgarrett@google.com> wrote: > From: David Howells <dhowells@redhat.com> > > bpf_read() and bpf_read_str() could potentially be abused to (eg) allow > private keys in kernel memory to be leaked. Disable them if the kernel > has been locked down in confidentiality mode. > > Suggested-by: Alexei Starovoitov <alexei.starovoitov@gmail.com> > Signed-off-by: Matthew Garrett <mjg59@google.com> > Reviewed-by: Kees Cook <keescook@chromium.org> > cc: netdev@vger.kernel.org > cc: Chun-Yi Lee <jlee@suse.com> > cc: Alexei Starovoitov <alexei.starovoitov@gmail.com> > Cc: Daniel Borkmann <daniel@iogearbox.net> > Signed-off-by: James Morris <jmorris@namei.org> Signed-off-by: David Howells <dhowells@redhat.com>
diff --git a/include/linux/security.h b/include/linux/security.h index 0b2529dbf0f4..e604f4c67f03 100644 --- a/include/linux/security.h +++ b/include/linux/security.h @@ -118,6 +118,7 @@ enum lockdown_reason { LOCKDOWN_INTEGRITY_MAX, LOCKDOWN_KCORE, LOCKDOWN_KPROBES, + LOCKDOWN_BPF_READ, LOCKDOWN_CONFIDENTIALITY_MAX, }; diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index 1c9a4745e596..33a954c367f3 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -139,8 +139,13 @@ 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 < 0) + goto out; + ret = probe_kernel_read(dst, unsafe_ptr, size); if (unlikely(ret < 0)) +out: memset(dst, 0, size); return ret; @@ -566,6 +571,10 @@ BPF_CALL_3(bpf_probe_read_str, void *, dst, u32, size, { int ret; + ret = security_locked_down(LOCKDOWN_BPF_READ); + if (ret < 0) + 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 @@ -577,6 +586,7 @@ BPF_CALL_3(bpf_probe_read_str, void *, dst, u32, size, */ ret = strncpy_from_unsafe(dst, unsafe_ptr, size); if (unlikely(ret < 0)) +out: memset(dst, 0, size); return ret; diff --git a/security/lockdown/lockdown.c b/security/lockdown/lockdown.c index 27b2cf51e443..2397772c56bd 100644 --- a/security/lockdown/lockdown.c +++ b/security/lockdown/lockdown.c @@ -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", };