bpf: introduce bpf_get_current_task() helper
over time there were multiple requests to access different data
structures and fields of task_struct current, so finally add
the helper to access 'current' as-is. Tracing bpf programs will do
the rest of walking the pointers via bpf_probe_read().
Note that current can be null and bpf program has to deal it with,
but even dumb passing null into bpf_probe_read() is still safe.
Suggested-by: Brendan Gregg <brendan.d.gregg@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index c14ca1c..262a7e8 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -357,6 +357,13 @@
*/
BPF_FUNC_get_hash_recalc,
+ /**
+ * u64 bpf_get_current_task(void)
+ * Returns current task_struct
+ * Return: current
+ */
+ BPF_FUNC_get_current_task,
+
__BPF_FUNC_MAX_ID,
};
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 19c5b4a..094c716 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -312,6 +312,17 @@
return &bpf_event_output_proto;
}
+static u64 bpf_get_current_task(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
+{
+ return (long) current;
+}
+
+static const struct bpf_func_proto bpf_get_current_task_proto = {
+ .func = bpf_get_current_task,
+ .gpl_only = true,
+ .ret_type = RET_INTEGER,
+};
+
static const struct bpf_func_proto *tracing_func_proto(enum bpf_func_id func_id)
{
switch (func_id) {
@@ -329,6 +340,8 @@
return &bpf_tail_call_proto;
case BPF_FUNC_get_current_pid_tgid:
return &bpf_get_current_pid_tgid_proto;
+ case BPF_FUNC_get_current_task:
+ return &bpf_get_current_task_proto;
case BPF_FUNC_get_current_uid_gid:
return &bpf_get_current_uid_gid_proto;
case BPF_FUNC_get_current_comm: