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Subject[PATCH bpf-next v2 1/9] bpf: sockmap: only check ULP for TCP sockets
Date
The sock map code checks that a socket does not have an active upper
layer protocol before inserting it into the map. This requires casting
via inet_csk, which isn't valid for UDP sockets.

Guard checks for ULP by checking inet_sk(sk)->is_icsk first.

Signed-off-by: Lorenz Bauer <lmb@cloudflare.com>
---
include/linux/skmsg.h | 8 +++++++-
net/core/sock_map.c | 11 +++++++----
2 files changed, 14 insertions(+), 5 deletions(-)

diff --git a/include/linux/skmsg.h b/include/linux/skmsg.h
index 112765bd146d..54a9a3e36b29 100644
--- a/include/linux/skmsg.h
+++ b/include/linux/skmsg.h
@@ -360,7 +360,13 @@ static inline void sk_psock_restore_proto(struct sock *sk,
struct sk_psock *psock)
{
sk->sk_prot->unhash = psock->saved_unhash;
- tcp_update_ulp(sk, psock->sk_proto, psock->saved_write_space);
+ if (inet_sk(sk)->is_icsk) {
+ tcp_update_ulp(sk, psock->sk_proto, psock->saved_write_space);
+ } else {
+ sk->sk_write_space = psock->saved_write_space;
+ /* Pairs with lockless read in sk_clone_lock() */
+ WRITE_ONCE(sk->sk_prot, psock->sk_proto);
+ }
}

static inline void sk_psock_set_state(struct sk_psock *psock,
diff --git a/net/core/sock_map.c b/net/core/sock_map.c
index 2e0f465295c3..695ecacc7afa 100644
--- a/net/core/sock_map.c
+++ b/net/core/sock_map.c
@@ -94,6 +94,11 @@ static void sock_map_sk_release(struct sock *sk)
release_sock(sk);
}

+static bool sock_map_sk_has_ulp(struct sock *sk)
+{
+ return inet_sk(sk)->is_icsk && !!inet_csk(sk)->icsk_ulp_ops;
+}
+
static void sock_map_add_link(struct sk_psock *psock,
struct sk_psock_link *link,
struct bpf_map *map, void *link_raw)
@@ -384,7 +389,6 @@ static int sock_map_update_common(struct bpf_map *map, u32 idx,
struct sock *sk, u64 flags)
{
struct bpf_stab *stab = container_of(map, struct bpf_stab, map);
- struct inet_connection_sock *icsk = inet_csk(sk);
struct sk_psock_link *link;
struct sk_psock *psock;
struct sock *osk;
@@ -395,7 +399,7 @@ static int sock_map_update_common(struct bpf_map *map, u32 idx,
return -EINVAL;
if (unlikely(idx >= map->max_entries))
return -E2BIG;
- if (unlikely(rcu_access_pointer(icsk->icsk_ulp_data)))
+ if (sock_map_sk_has_ulp(sk))
return -EINVAL;

link = sk_psock_init_link();
@@ -738,7 +742,6 @@ static int sock_hash_update_common(struct bpf_map *map, void *key,
struct sock *sk, u64 flags)
{
struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
- struct inet_connection_sock *icsk = inet_csk(sk);
u32 key_size = map->key_size, hash;
struct bpf_htab_elem *elem, *elem_new;
struct bpf_htab_bucket *bucket;
@@ -749,7 +752,7 @@ static int sock_hash_update_common(struct bpf_map *map, void *key,
WARN_ON_ONCE(!rcu_read_lock_held());
if (unlikely(flags > BPF_EXIST))
return -EINVAL;
- if (unlikely(icsk->icsk_ulp_data))
+ if (sock_map_sk_has_ulp(sk))
return -EINVAL;

link = sk_psock_init_link();
--
2.20.1
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