Messages in this thread | | | Date | Tue, 17 Jan 2023 09:24:56 -0800 | Subject | Re: [PATCH] bpf: security enhancement by limiting the offensive eBPF helpers | From | Yonghong Song <> |
| |
On 1/17/23 7:12 AM, WritePaper wrote: > The bpf_send_singal and bpf_override_return is similar to > bpf_write_user and can affect userspace processes. Thus, these two > helpers should also be constraint by security lockdown. > > Signed-off-by: WritePaper <clangllvm@126.com> > --- > include/linux/security.h | 3 +++ > kernel/trace/bpf_trace.c | 6 ++++-- > 2 files changed, 7 insertions(+), 2 deletions(-) > > diff --git a/include/linux/security.h b/include/linux/security.h > index 5b67f208f..cb90b2860 100644 > --- a/include/linux/security.h > +++ b/include/linux/security.h > @@ -123,6 +123,9 @@ enum lockdown_reason { > LOCKDOWN_DEBUGFS, > LOCKDOWN_XMON_WR, > LOCKDOWN_BPF_WRITE_USER, > + LOCKDOWN_BPF_SEND_SIGNAL, > + LOCKDOWN_BPF_OVERRIDE_RETURN, > + LOCKDOWN_OFFENSIVE_BPF_MAX,
LOCKDOWN_OFFENSIVE_BPF_MAX is not used.
> LOCKDOWN_DBG_WRITE_KERNEL, > LOCKDOWN_RTAS_ERROR_INJECTION, > LOCKDOWN_INTEGRITY_MAX, > diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c > index 3bbd3f0c8..3a80f4b6f 100644 > --- a/kernel/trace/bpf_trace.c > +++ b/kernel/trace/bpf_trace.c > @@ -1463,7 +1463,8 @@ bpf_tracing_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) > return &bpf_cgrp_storage_delete_proto; > #endif > case BPF_FUNC_send_signal: > - return &bpf_send_signal_proto; > + return security_locked_down(LOCKDOWN_BPF_SEND_SIGNAL) < 0 ? > + NULL : &bpf_send_signal_proto;
You should add the same security_locked_down(LOCKDOWN_BPF_SEND_SIGNAL) check with below bpf_send_signal_thread() helper.
> case BPF_FUNC_send_signal_thread: > return &bpf_send_signal_thread_proto; > case BPF_FUNC_perf_event_read_value: > @@ -1531,7 +1532,8 @@ kprobe_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) > return &bpf_get_stack_proto; > #ifdef CONFIG_BPF_KPROBE_OVERRIDE > case BPF_FUNC_override_return: > - return &bpf_override_return_proto; > + return security_locked_down(LOCKDOWN_BPF_OVERRIDE_RETURN) < 0 ? > + NULL : &bpf_override_return_proto; > #endif > case BPF_FUNC_get_func_ip: > return prog->expected_attach_type == BPF_TRACE_KPROBE_MULTI ?
| |