This patch changes the behavior of how BPF_PROG_RUN treats tracing
(fentry/fexit) programs. Previously only a return value is injected
but the actual program was not run. New behavior mirrors that of
running raw tracepoint BPF programs which actually runs the
instructions of the program via `bpf_prog_run()`
Tracing programs only needs to support an input context so we validate
that non-relevant attributes are not set.
Changes v1 -> v2:
- Fixed unused variable and logic for how the fmod_ret test is handled
Signed-off-by: Grant Seltzer <grantseltzer@xxxxxxxxx>
---
net/bpf/test_run.c | 77 +++++++++++++++++++++++++++++++++++++++++-----
1 file changed, 70 insertions(+), 7 deletions(-)
diff --git a/net/bpf/test_run.c b/net/bpf/test_run.c
index 8da0d73b368e..0c36ed7dd88e 100644
--- a/net/bpf/test_run.c
+++ b/net/bpf/test_run.c
@@ -794,14 +794,34 @@ static void *bpf_test_init(const union bpf_attr *kattr, u32 user_size,
return data;
}
+struct bpf_tracing_test_run_info {
+ struct bpf_prog *prog;
+ void *ctx;
+ u32 retval;
+};
+
+static void
+__bpf_prog_test_run_tracing(void *data)
+{
+ struct bpf_tracing_test_run_info *info = data;
+
+ rcu_read_lock();
+ info->retval = bpf_prog_run(info->prog, info->ctx);
+ rcu_read_unlock();
+}
+
int bpf_prog_test_run_tracing(struct bpf_prog *prog,
const union bpf_attr *kattr,
union bpf_attr __user *uattr)
{
struct bpf_fentry_test_t arg = {};
- u16 side_effect = 0, ret = 0;
- int b = 2, err = -EFAULT;
- u32 retval = 0;
+ int b = 2, err = -EFAULT, current_cpu;
+
+ void __user *ctx_in = u64_to_user_ptr(kattr->test.ctx_in);
+ __u32 ctx_size_in = kattr->test.ctx_size_in;
+ struct bpf_tracing_test_run_info info;
+ int cpu = kattr->test.cpu;
+ u16 side_effect = 0;
if (kattr->test.flags || kattr->test.cpu || kattr->test.batch_size)
return -EINVAL;
@@ -820,7 +840,7 @@ int bpf_prog_test_run_tracing(struct bpf_prog *prog,
goto out;
break;
case BPF_MODIFY_RETURN:
- ret = bpf_modify_return_test(1, &b);
+ bpf_modify_return_test(1, &b);
if (b != 2)
side_effect = 1;
break;
@@ -828,11 +848,54 @@ int bpf_prog_test_run_tracing(struct bpf_prog *prog,
goto out;
}
- retval = ((u32)side_effect << 16) | ret;
- if (copy_to_user(&uattr->test.retval, &retval, sizeof(retval)))
- goto out;
+ /* doesn't support data_in/out, ctx_out, duration, or repeat */
+ if (kattr->test.data_in || kattr->test.data_out ||
+ kattr->test.ctx_out || kattr->test.duration ||
+ kattr->test.repeat || kattr->test.batch_size)
+ return -EINVAL;
+
+ if (ctx_size_in < prog->aux->max_ctx_offset ||
+ ctx_size_in > MAX_BPF_FUNC_ARGS * sizeof(u64))
+ return -EINVAL;
+
+ if ((kattr->test.flags & BPF_F_TEST_RUN_ON_CPU) == 0 && cpu != 0)
+ return -EINVAL;
+
+ if (ctx_size_in) {
+ info.ctx = memdup_user(ctx_in, ctx_size_in);
+ if (IS_ERR(info.ctx))
+ return PTR_ERR(info.ctx);
+ } else {
+ info.ctx = NULL;
+ }
err = 0;
+ info.prog = prog;
+
+ current_cpu = get_cpu();
+ if ((kattr->test.flags & BPF_F_TEST_RUN_ON_CPU) == 0 ||
+ cpu == current_cpu) {
+ __bpf_prog_test_run_tracing(&info);
+ } else if (cpu >= nr_cpu_ids || !cpu_online(cpu)) {
+ /* smp_call_function_single() also checks cpu_online()
+ * after csd_lock(). However, since cpu is from user
+ * space, let's do an extra quick check to filter out
+ * invalid value before smp_call_function_single().
+ */
+ err = -ENXIO;
+ } else {
+ err = smp_call_function_single(cpu, __bpf_prog_test_run_tracing,
+ &info, 1);
+ }
+ put_cpu();
+
+ info.retval = ((u32)side_effect << 16) | info.retval;
+ if (!err &&
+ copy_to_user(&uattr->test.retval, &info.retval, sizeof(u32)))
+ err = -EFAULT;
+
+ kfree(info.ctx);
+
out:
trace_bpf_test_finish(&err);
return err;
--
2.39.1
