The BPF_FUNC_sk_lookup_xxx helpers return RET_PTR_TO_SOCKET_OR_NULL.
Meaning a fullsock ptr and its fullsock's fields in bpf_sock can be
accessed, e.g. type, protocol, mark and priority.
Some new helper, like bpf_sk_storage_get(), also expects
ARG_PTR_TO_SOCKET is a fullsock.
bpf_sk_lookup() currently calls sk_to_full_sk() before returning.
However, the ptr returned from sk_to_full_sk() is not guaranteed
to be a fullsock. For example, it cannot get a fullsock if sk
is in TCP_TIME_WAIT.
This patch checks for sk_fullsock() before returning. If it is not
a fullsock, sock_gen_put() is called if needed and then returns NULL.
Fixes: 6acc9b432e67 ("bpf: Add helper to retrieve socket in BPF")
Cc: Joe Stringer <joe@xxxxxxxxxxxxx>
Signed-off-by: Martin KaFai Lau <kafai@xxxxxx>
---
net/core/filter.c | 16 ++++++++++++++--
1 file changed, 14 insertions(+), 2 deletions(-)
diff --git a/net/core/filter.c b/net/core/filter.c
index 55bfc941d17a..85def5a20aaf 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -5337,8 +5337,14 @@ __bpf_sk_lookup(struct sk_buff *skb, struct bpf_sock_tuple *tuple, u32 len,
struct sock *sk = __bpf_skc_lookup(skb, tuple, len, caller_net,
ifindex, proto, netns_id, flags);
- if (sk)
+ if (sk) {
sk = sk_to_full_sk(sk);
+ if (!sk_fullsock(sk)) {
+ if (!sock_flag(sk, SOCK_RCU_FREE))
+ sock_gen_put(sk);
+ return NULL;
+ }
+ }
return sk;
}
@@ -5369,8 +5375,14 @@ bpf_sk_lookup(struct sk_buff *skb, struct bpf_sock_tuple *tuple, u32 len,
struct sock *sk = bpf_skc_lookup(skb, tuple, len, proto, netns_id,
flags);
- if (sk)
+ if (sk) {
sk = sk_to_full_sk(sk);
+ if (!sk_fullsock(sk)) {
+ if (!sock_flag(sk, SOCK_RCU_FREE))
+ sock_gen_put(sk);
+ return NULL;
+ }
+ }
return sk;
}
--
2.17.1
