[PATCH v3 bpf-next 07/15] bpf: Initialize the bpf_run_ctx in bpf_iter_run_prog()

[Martin KaFai Lau <kafai@fb.com>]

The bpf-iter-prog for tcp and unix sk can do bpf_setsockopt()
which needs has_current_bpf_ctx() to decide if it is called by a
bpf prog.  This patch initializes the bpf_run_ctx in
bpf_iter_run_prog() for the has_current_bpf_ctx() to use.

Signed-off-by: Martin KaFai Lau <kafai@fb.com>
---
 include/linux/bpf.h   | 2 +-
 kernel/bpf/bpf_iter.c | 5 +++++
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 0a600b2013cc..15ab980e9525 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -1967,7 +1967,7 @@ static inline bool unprivileged_ebpf_enabled(void)
 }
 
 /* Not all bpf prog type has the bpf_ctx.
- * Only trampoline and cgroup-bpf have it.
+ * Only trampoline, cgroup-bpf, and iter have it.
  * For the bpf prog type that has initialized the bpf_ctx,
  * this function can be used to decide if a kernel function
  * is called by a bpf program.
diff --git a/kernel/bpf/bpf_iter.c b/kernel/bpf/bpf_iter.c
index 4b112aa8bba3..6476b2c03527 100644
--- a/kernel/bpf/bpf_iter.c
+++ b/kernel/bpf/bpf_iter.c
@@ -685,19 +685,24 @@ struct bpf_prog *bpf_iter_get_info(struct bpf_iter_meta *meta, bool in_stop)
 
 int bpf_iter_run_prog(struct bpf_prog *prog, void *ctx)
 {
+	struct bpf_run_ctx run_ctx, *old_run_ctx;
 	int ret;
 
 	if (prog->aux->sleepable) {
 		rcu_read_lock_trace();
 		migrate_disable();
 		might_fault();
+		old_run_ctx = bpf_set_run_ctx(&run_ctx);
 		ret = bpf_prog_run(prog, ctx);
+		bpf_reset_run_ctx(old_run_ctx);
 		migrate_enable();
 		rcu_read_unlock_trace();
 	} else {
 		rcu_read_lock();
 		migrate_disable();
+		old_run_ctx = bpf_set_run_ctx(&run_ctx);
 		ret = bpf_prog_run(prog, ctx);
+		bpf_reset_run_ctx(old_run_ctx);
 		migrate_enable();
 		rcu_read_unlock();
 	}
-- 
2.30.2