From: Cong Wang <cong.w...@bytedance.com>
Currently TCP_SKB_CB() is hard-coded in skmsg code, it certainly
does not work for any other non-TCP protocols. We can move them to
skb ext, but it introduces a memory allocation on fast path.
Fortunately, we only need to a word-size to store all the information,
because the flags actually only contains 1 bit so can be just packed
into the lowest bit of the "pointer", which is stored as unsigned
long.
Inside struct sk_buff, '_skb_refdst' can be reused because skb dst is
no longer needed after ->sk_data_ready() so we can just drop it.
Cc: Daniel Borkmann <dan...@iogearbox.net>
Cc: Jakub Sitnicki <ja...@cloudflare.com>
Cc: Lorenz Bauer <l...@cloudflare.com>
Acked-by: John Fastabend <john.fastab...@gmail.com>
Signed-off-by: Cong Wang <cong.w...@bytedance.com>
---
include/linux/skbuff.h | 3 +++
include/linux/skmsg.h | 35 +++++++++++++++++++++++++++++++++++
include/net/tcp.h | 19 -------------------
net/core/skmsg.c | 32 ++++++++++++++++++++------------
net/core/sock_map.c | 8 ++------
5 files changed, 60 insertions(+), 37 deletions(-)
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 6d0a33d1c0db..bd84f799c952 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -755,6 +755,9 @@ struct sk_buff {
void (*destructor)(struct sk_buff *skb);
};
struct list_head tcp_tsorted_anchor;
+#ifdef CONFIG_NET_SOCK_MSG
+ unsigned long _sk_redir;
+#endif
};
#if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
diff --git a/include/linux/skmsg.h b/include/linux/skmsg.h
index e3bb712af257..fc234d507fd7 100644
--- a/include/linux/skmsg.h
+++ b/include/linux/skmsg.h
@@ -459,4 +459,39 @@ static inline bool sk_psock_strp_enabled(struct sk_psock
*psock)
return false;
return !!psock->saved_data_ready;
}
+
+#if IS_ENABLED(CONFIG_NET_SOCK_MSG)
+static inline bool skb_bpf_ingress(const struct sk_buff *skb)
+{
+ unsigned long sk_redir = skb->_sk_redir;
+
+ return sk_redir & BPF_F_INGRESS;
+}
+
+static inline void skb_bpf_set_ingress(struct sk_buff *skb)
+{
+ skb->_sk_redir |= BPF_F_INGRESS;
+}
+
+static inline void skb_bpf_set_redir(struct sk_buff *skb, struct sock
*sk_redir,
+ bool ingress)
+{
+ skb->_sk_redir = (unsigned long)sk_redir;
+ if (ingress)
+ skb->_sk_redir |= BPF_F_INGRESS;
+}
+
+static inline struct sock *skb_bpf_redirect_fetch(const struct sk_buff *skb)
+{
+ unsigned long sk_redir = skb->_sk_redir;
+
+ sk_redir &= ~0x1UL;
+ return (struct sock *)sk_redir;
+}
+
+static inline void skb_bpf_redirect_clear(struct sk_buff *skb)
+{
+ skb->_sk_redir = 0;
+}
+#endif /* CONFIG_NET_SOCK_MSG */
#endif /* _LINUX_SKMSG_H */
diff --git a/include/net/tcp.h b/include/net/tcp.h
index 947ef5da6867..075de26f449d 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -883,30 +883,11 @@ struct tcp_skb_cb {
struct inet6_skb_parm h6;
#endif
} header; /* For incoming skbs */
- struct {
- __u32 flags;
- struct sock *sk_redir;
- } bpf;
};
};
#define TCP_SKB_CB(__skb) ((struct tcp_skb_cb *)&((__skb)->cb[0]))
-static inline bool tcp_skb_bpf_ingress(const struct sk_buff *skb)
-{
- return TCP_SKB_CB(skb)->bpf.flags & BPF_F_INGRESS;
-}
-
-static inline struct sock *tcp_skb_bpf_redirect_fetch(struct sk_buff *skb)
-{
- return TCP_SKB_CB(skb)->bpf.sk_redir;
-}
-
-static inline void tcp_skb_bpf_redirect_clear(struct sk_buff *skb)
-{
- TCP_SKB_CB(skb)->bpf.sk_redir = NULL;
-}
-
extern const struct inet_connection_sock_af_ops ipv4_specific;
#if IS_ENABLED(CONFIG_IPV6)
diff --git a/net/core/skmsg.c b/net/core/skmsg.c
index 2d8bbb3fd87c..05b5af09ff42 100644
--- a/net/core/skmsg.c
+++ b/net/core/skmsg.c
@@ -494,6 +494,8 @@ static int sk_psock_skb_ingress_self(struct sk_psock
*psock, struct sk_buff *skb
static int sk_psock_handle_skb(struct sk_psock *psock, struct sk_buff *skb,
u32 off, u32 len, bool ingress)
{
+ skb_bpf_redirect_clear(skb);
+
if (!ingress) {
if (!sock_writeable(psock->sk))
return -EAGAIN;
@@ -525,7 +527,7 @@ static void sk_psock_backlog(struct work_struct *work)
len = skb->len;
off = 0;
start:
- ingress = tcp_skb_bpf_ingress(skb);
+ ingress = skb_bpf_ingress(skb);
do {
ret = -EIO;
if (likely(psock->sk->sk_socket))
@@ -631,7 +633,12 @@ void __sk_psock_purge_ingress_msg(struct sk_psock *psock)
static void sk_psock_zap_ingress(struct sk_psock *psock)
{
- __skb_queue_purge(&psock->ingress_skb);
+ struct sk_buff *skb;
+
+ while ((skb = __skb_dequeue(&psock->ingress_skb)) != NULL) {
+ skb_bpf_redirect_clear(skb);
+ kfree_skb(skb);
+ }
__sk_psock_purge_ingress_msg(psock);
}
@@ -752,7 +759,7 @@ static void sk_psock_skb_redirect(struct sk_buff *skb)
struct sk_psock *psock_other;
struct sock *sk_other;
- sk_other = tcp_skb_bpf_redirect_fetch(skb);
+ sk_other = skb_bpf_redirect_fetch(skb);
/* This error is a buggy BPF program, it returned a redirect
* return code, but then didn't set a redirect interface.
*/
@@ -802,9 +809,10 @@ int sk_psock_tls_strp_read(struct sk_psock *psock, struct
sk_buff *skb)
* TLS context.
*/
skb->sk = psock->sk;
- tcp_skb_bpf_redirect_clear(skb);
+ skb_dst_drop(skb);
+ skb_bpf_redirect_clear(skb);
ret = sk_psock_bpf_run(psock, prog, skb);
- ret = sk_psock_map_verd(ret, tcp_skb_bpf_redirect_fetch(skb));
+ ret = sk_psock_map_verd(ret, skb_bpf_redirect_fetch(skb));
skb->sk = NULL;
}
sk_psock_tls_verdict_apply(skb, psock->sk, ret);
@@ -816,7 +824,6 @@ EXPORT_SYMBOL_GPL(sk_psock_tls_strp_read);
static void sk_psock_verdict_apply(struct sk_psock *psock,
struct sk_buff *skb, int verdict)
{
- struct tcp_skb_cb *tcp;
struct sock *sk_other;
int err = -EIO;
@@ -828,8 +835,7 @@ static void sk_psock_verdict_apply(struct sk_psock *psock,
goto out_free;
}
- tcp = TCP_SKB_CB(skb);
- tcp->bpf.flags |= BPF_F_INGRESS;
+ skb_bpf_set_ingress(skb);
/* If the queue is empty then we can submit directly
* into the msg queue. If its not empty we have to
@@ -890,9 +896,10 @@ static void sk_psock_strp_read(struct strparser *strp,
struct sk_buff *skb)
skb_set_owner_r(skb, sk);
prog = READ_ONCE(psock->progs.skb_verdict);
if (likely(prog)) {
- tcp_skb_bpf_redirect_clear(skb);
+ skb_dst_drop(skb);
+ skb_bpf_redirect_clear(skb);
ret = sk_psock_bpf_run(psock, prog, skb);
- ret = sk_psock_map_verd(ret, tcp_skb_bpf_redirect_fetch(skb));
+ ret = sk_psock_map_verd(ret, skb_bpf_redirect_fetch(skb));
}
sk_psock_verdict_apply(psock, skb, ret);
out:
@@ -1005,9 +1012,10 @@ static int sk_psock_verdict_recv(read_descriptor_t
*desc, struct sk_buff *skb,
skb_set_owner_r(skb, sk);
prog = READ_ONCE(psock->progs.skb_verdict);
if (likely(prog)) {
- tcp_skb_bpf_redirect_clear(skb);
+ skb_dst_drop(skb);
+ skb_bpf_redirect_clear(skb);
ret = sk_psock_bpf_run(psock, prog, skb);
- ret = sk_psock_map_verd(ret, tcp_skb_bpf_redirect_fetch(skb));
+ ret = sk_psock_map_verd(ret, skb_bpf_redirect_fetch(skb));
}
sk_psock_verdict_apply(psock, skb, ret);
out:
diff --git a/net/core/sock_map.c b/net/core/sock_map.c
index 1a28a5c2c61e..dbfcd7006338 100644
--- a/net/core/sock_map.c
+++ b/net/core/sock_map.c
@@ -657,7 +657,6 @@ const struct bpf_func_proto bpf_sock_map_update_proto = {
BPF_CALL_4(bpf_sk_redirect_map, struct sk_buff *, skb,
struct bpf_map *, map, u32, key, u64, flags)
{
- struct tcp_skb_cb *tcb = TCP_SKB_CB(skb);
struct sock *sk;
if (unlikely(flags & ~(BPF_F_INGRESS)))
@@ -667,8 +666,7 @@ BPF_CALL_4(bpf_sk_redirect_map, struct sk_buff *, skb,
if (unlikely(!sk || !sock_map_redirect_allowed(sk)))
return SK_DROP;
- tcb->bpf.flags = flags;
- tcb->bpf.sk_redir = sk;
+ skb_bpf_set_redir(skb, sk, flags & BPF_F_INGRESS);
return SK_PASS;
}
@@ -1250,7 +1248,6 @@ const struct bpf_func_proto bpf_sock_hash_update_proto = {
BPF_CALL_4(bpf_sk_redirect_hash, struct sk_buff *, skb,
struct bpf_map *, map, void *, key, u64, flags)
{
- struct tcp_skb_cb *tcb = TCP_SKB_CB(skb);
struct sock *sk;
if (unlikely(flags & ~(BPF_F_INGRESS)))
@@ -1260,8 +1257,7 @@ BPF_CALL_4(bpf_sk_redirect_hash, struct sk_buff *, skb,
if (unlikely(!sk || !sock_map_redirect_allowed(sk)))
return SK_DROP;
- tcb->bpf.flags = flags;
- tcb->bpf.sk_redir = sk;
+ skb_bpf_set_redir(skb, sk, flags & BPF_F_INGRESS);
return SK_PASS;
}
--
2.25.1
