[PATCH net-next 24/24] net: bpf: Add lockdep assert for the redirect process.

[Sebastian Andrzej Siewior]

The users of bpf_redirect_info should lock the access by acquiring the
nested BH-lock bpf_run_lock.redirect_lock. This lock should be acquired
before the first usage (bpf_prog_run_xdp()) and dropped after the last
user in the context (xdp_do_redirect()).

Current user in tree have been audited and updated.

Add lockdep annonation to ensure new user acquire the lock.

Cc: Alexei Starovoitov <ast@xxxxxxxxxx>
Cc: Andrii Nakryiko <andrii@xxxxxxxxxx>
Cc: Hao Luo <haoluo@xxxxxxxxxx>
Cc: Jesper Dangaard Brouer <hawk@xxxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: John Fastabend <john.fastabend@xxxxxxxxx>
Cc: KP Singh <kpsingh@xxxxxxxxxx>
Cc: Martin KaFai Lau <martin.lau@xxxxxxxxx>
Cc: Song Liu <song@xxxxxxxxxx>
Cc: Stanislav Fomichev <sdf@xxxxxxxxxx>
Cc: Yonghong Song <yonghong.song@xxxxxxxxx>
Cc: bpf@xxxxxxxxxxxxxxx
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
---
 include/net/xdp.h |  1 +
 net/core/filter.c | 11 +++++++++++
 2 files changed, 12 insertions(+)

diff --git a/include/net/xdp.h b/include/net/xdp.h
index 349c36fb5fd8f..cdeab175abf18 100644
--- a/include/net/xdp.h
+++ b/include/net/xdp.h
@@ -493,6 +493,7 @@ static inline void xdp_clear_features_flag(struct net_device *dev)
 static __always_inline u32 bpf_prog_run_xdp(const struct bpf_prog *prog,
 					    struct xdp_buff *xdp)
 {
+	lockdep_assert_held(this_cpu_ptr(&bpf_run_lock.redirect_lock));
 	/* Driver XDP hooks are invoked within a single NAPI poll cycle and thus
 	 * under local_bh_disable(), which provides the needed RCU protection
 	 * for accessing map entries.
diff --git a/net/core/filter.c b/net/core/filter.c
index 72a7812f933a1..a2f97503ed578 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -2495,6 +2495,7 @@ int skb_do_redirect(struct sk_buff *skb)
 	struct net_device *dev;
 	u32 flags = ri->flags;
 
+	lockdep_assert_held(this_cpu_ptr(&bpf_run_lock.redirect_lock));
 	dev = dev_get_by_index_rcu(net, ri->tgt_index);
 	ri->tgt_index = 0;
 	ri->flags = 0;
@@ -2525,6 +2526,8 @@ BPF_CALL_2(bpf_redirect, u32, ifindex, u64, flags)
 {
 	struct bpf_redirect_info *ri = this_cpu_ptr(&bpf_redirect_info);
 
+	lockdep_assert_held(this_cpu_ptr(&bpf_run_lock.redirect_lock));
+
 	if (unlikely(flags & (~(BPF_F_INGRESS) | BPF_F_REDIRECT_INTERNAL)))
 		return TC_ACT_SHOT;
 
@@ -2546,6 +2549,8 @@ BPF_CALL_2(bpf_redirect_peer, u32, ifindex, u64, flags)
 {
 	struct bpf_redirect_info *ri = this_cpu_ptr(&bpf_redirect_info);
 
+	lockdep_assert_held(this_cpu_ptr(&bpf_run_lock.redirect_lock));
+
 	if (unlikely(flags))
 		return TC_ACT_SHOT;
 
@@ -2568,6 +2573,8 @@ BPF_CALL_4(bpf_redirect_neigh, u32, ifindex, struct bpf_redir_neigh *, params,
 {
 	struct bpf_redirect_info *ri = this_cpu_ptr(&bpf_redirect_info);
 
+	lockdep_assert_held(this_cpu_ptr(&bpf_run_lock.redirect_lock));
+
 	if (unlikely((plen && plen < sizeof(*params)) || flags))
 		return TC_ACT_SHOT;
 
@@ -4287,6 +4294,8 @@ u32 xdp_master_redirect(struct xdp_buff *xdp)
 	struct net_device *master, *slave;
 	struct bpf_redirect_info *ri = this_cpu_ptr(&bpf_redirect_info);
 
+	lockdep_assert_held(this_cpu_ptr(&bpf_run_lock.redirect_lock));
+
 	master = netdev_master_upper_dev_get_rcu(xdp->rxq->dev);
 	slave = master->netdev_ops->ndo_xdp_get_xmit_slave(master, xdp);
 	if (slave && slave != xdp->rxq->dev) {
@@ -4394,6 +4403,7 @@ int xdp_do_redirect(struct net_device *dev, struct xdp_buff *xdp,
 	struct bpf_redirect_info *ri = this_cpu_ptr(&bpf_redirect_info);
 	enum bpf_map_type map_type = ri->map_type;
 
+	lockdep_assert_held(this_cpu_ptr(&bpf_run_lock.redirect_lock));
 	if (map_type == BPF_MAP_TYPE_XSKMAP)
 		return __xdp_do_redirect_xsk(ri, dev, xdp, xdp_prog);
 
@@ -4408,6 +4418,7 @@ int xdp_do_redirect_frame(struct net_device *dev, struct xdp_buff *xdp,
 	struct bpf_redirect_info *ri = this_cpu_ptr(&bpf_redirect_info);
 	enum bpf_map_type map_type = ri->map_type;
 
+	lockdep_assert_held(this_cpu_ptr(&bpf_run_lock.redirect_lock));
 	if (map_type == BPF_MAP_TYPE_XSKMAP)
 		return __xdp_do_redirect_xsk(ri, dev, xdp, xdp_prog);
 
-- 
2.43.0