On 1/17/23 4:54 PM, Yi He wrote:
The bpf_send_singal, bpf_send_singal_thread and bpf_override_return
is similar to bpf_write_user and can affect userspace processes.
Thus, these three helpers should also be restricted by security lockdown.
Signed-off-by: Yi He <clangllvm@xxxxxxx>
---
V1 -> V2: add security lockdown to bpf_send_singal_thread and remove
the unused LOCKDOWN_OFFENSIVE_BPF_MAX.
include/linux/security.h | 2 ++
kernel/trace/bpf_trace.c | 9 ++++++---
2 files changed, 8 insertions(+), 3 deletions(-)
diff --git a/include/linux/security.h b/include/linux/security.h
index 5b67f208f..42420e620 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -123,6 +123,8 @@ enum lockdown_reason {
LOCKDOWN_DEBUGFS,
LOCKDOWN_XMON_WR,
LOCKDOWN_BPF_WRITE_USER,
+ LOCKDOWN_BPF_SEND_SIGNAL,
+ LOCKDOWN_BPF_OVERRIDE_RETURN,
LOCKDOWN_DBG_WRITE_KERNEL,
LOCKDOWN_RTAS_ERROR_INJECTION,
LOCKDOWN_INTEGRITY_MAX,
Also, do you need to add an entry in lockdown_reasons in
security/security.c?
Also add linux-security-module@xxxxxxxxxxxxxxx so security experts can
chime in as well.
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 3bbd3f0c8..fdb94868d 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -1463,9 +1463,11 @@ 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;
case BPF_FUNC_send_signal_thread:
- return &bpf_send_signal_thread_proto;
+ return security_locked_down(LOCKDOWN_BPF_SEND_SIGNAL) < 0 ?
+ NULL : &bpf_send_signal_thread_proto;
case BPF_FUNC_perf_event_read_value:
return &bpf_perf_event_read_value_proto;
case BPF_FUNC_get_ns_current_pid_tgid:
@@ -1531,7 +1533,8 @@ 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 ?
