From: Cong Wang <cong.w...@bytedance.com>
Currently TCP_SKB_CB() is hard-coded in skmsg code, it certainly
won't work for any other non-TCP protocols. We can move them to
skb ext instead of playing with skb cb, which is harder to make
correct.
Of course, except ->data_end, which is used by
sk_skb_convert_ctx_access() to adjust compile-time constant offset.
Fortunately, we can reuse the anonymous union where the field
'tcp_tsorted_anchor' is and save/restore the overwritten part
before/after a brief use.
Cc: John Fastabend <john.fastab...@gmail.com>
Cc: Daniel Borkmann <dan...@iogearbox.net>
Cc: Jakub Sitnicki <ja...@cloudflare.com>
Cc: Lorenz Bauer <l...@cloudflare.com>
Signed-off-by: Cong Wang <cong.w...@bytedance.com>
---
include/linux/skbuff.h | 4 ++++
include/linux/skmsg.h | 45 ++++++++++++++++++++++++++++++++++++++++++
include/net/tcp.h | 25 -----------------------
net/Kconfig | 1 +
net/core/filter.c | 3 +--
net/core/skbuff.c | 7 +++++++
net/core/skmsg.c | 44 ++++++++++++++++++++++++++++-------------
net/core/sock_map.c | 12 +++++------
8 files changed, 94 insertions(+), 47 deletions(-)
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 46f901adf1a8..12a28268233a 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -755,6 +755,7 @@ struct sk_buff {
void (*destructor)(struct sk_buff *skb);
};
struct list_head tcp_tsorted_anchor;
+ void *data_end;
};
#if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
@@ -4166,6 +4167,9 @@ enum skb_ext_id {
#endif
#if IS_ENABLED(CONFIG_MPTCP)
SKB_EXT_MPTCP,
+#endif
+#if IS_ENABLED(CONFIG_NET_SOCK_MSG)
+ SKB_EXT_BPF,
#endif
SKB_EXT_NUM, /* must be last */
};
diff --git a/include/linux/skmsg.h b/include/linux/skmsg.h
index 56d641df3b0c..e212b0d1ba35 100644
--- a/include/linux/skmsg.h
+++ b/include/linux/skmsg.h
@@ -438,4 +438,49 @@ static inline bool sk_psock_strp_enabled(struct sk_psock
*psock)
return false;
return psock->bpf_running;
}
+
+struct skb_bpf_ext {
+ __u32 flags;
+ struct sock *sk_redir;
+};
+
+static inline void bpf_compute_data_end_sk_skb(struct sk_buff *skb)
+{
+ skb->data_end = skb->data + skb_headlen(skb);
+}
+
+#if IS_ENABLED(CONFIG_NET_SOCK_MSG)
+static inline
+bool skb_bpf_ext_ingress(const struct sk_buff *skb)
+{
+ struct skb_bpf_ext *ext = skb_ext_find(skb, SKB_EXT_BPF);
+
+ return ext->flags & BPF_F_INGRESS;
+}
+
+static inline
+void skb_bpf_ext_set_ingress(const struct sk_buff *skb)
+{
+ struct skb_bpf_ext *ext = skb_ext_find(skb, SKB_EXT_BPF);
+
+ ext->flags |= BPF_F_INGRESS;
+}
+
+static inline
+struct sock *skb_bpf_ext_redirect_fetch(struct sk_buff *skb)
+{
+ struct skb_bpf_ext *ext = skb_ext_find(skb, SKB_EXT_BPF);
+
+ return ext->sk_redir;
+}
+
+static inline
+void skb_bpf_ext_redirect_clear(struct sk_buff *skb)
+{
+ struct skb_bpf_ext *ext = skb_ext_find(skb, SKB_EXT_BPF);
+
+ ext->flags = 0;
+ ext->sk_redir = NULL;
+}
+#endif /* CONFIG_NET_SOCK_MSG */
#endif /* _LINUX_SKMSG_H */
diff --git a/include/net/tcp.h b/include/net/tcp.h
index be66571ad122..f7591768525d 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -882,36 +882,11 @@ struct tcp_skb_cb {
struct inet6_skb_parm h6;
#endif
} header; /* For incoming skbs */
- struct {
- __u32 flags;
- struct sock *sk_redir;
- void *data_end;
- } bpf;
};
};
#define TCP_SKB_CB(__skb) ((struct tcp_skb_cb *)&((__skb)->cb[0]))
-static inline void bpf_compute_data_end_sk_skb(struct sk_buff *skb)
-{
- TCP_SKB_CB(skb)->bpf.data_end = skb->data + skb_headlen(skb);
-}
-
-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/Kconfig b/net/Kconfig
index 0cc0805a8127..1e45bcaa23f1 100644
--- a/net/Kconfig
+++ b/net/Kconfig
@@ -422,6 +422,7 @@ config SOCK_VALIDATE_XMIT
config NET_SOCK_MSG
bool
+ select SKB_EXTENSIONS
default n
help
The NET_SOCK_MSG provides a framework for plain sockets (e.g. TCP) or
diff --git a/net/core/filter.c b/net/core/filter.c
index e15d4741719a..c1a19a663630 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -9532,8 +9532,7 @@ static u32 sk_skb_convert_ctx_access(enum bpf_access_type
type,
case offsetof(struct __sk_buff, data_end):
off = si->off;
off -= offsetof(struct __sk_buff, data_end);
- off += offsetof(struct sk_buff, cb);
- off += offsetof(struct tcp_skb_cb, bpf.data_end);
+ off += offsetof(struct sk_buff, data_end);
*insn++ = BPF_LDX_MEM(BPF_SIZEOF(void *), si->dst_reg,
si->src_reg, off);
break;
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 145503d3f06b..7695a2b65832 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -60,6 +60,7 @@
#include <linux/prefetch.h>
#include <linux/if_vlan.h>
#include <linux/mpls.h>
+#include <linux/skmsg.h>
#include <net/protocol.h>
#include <net/dst.h>
@@ -4259,6 +4260,9 @@ static const u8 skb_ext_type_len[] = {
#if IS_ENABLED(CONFIG_MPTCP)
[SKB_EXT_MPTCP] = SKB_EXT_CHUNKSIZEOF(struct mptcp_ext),
#endif
+#if IS_ENABLED(CONFIG_NET_SOCK_MSG)
+ [SKB_EXT_BPF] = SKB_EXT_CHUNKSIZEOF(struct skb_bpf_ext),
+#endif
};
static __always_inline unsigned int skb_ext_total_length(void)
@@ -4275,6 +4279,9 @@ static __always_inline unsigned int
skb_ext_total_length(void)
#endif
#if IS_ENABLED(CONFIG_MPTCP)
skb_ext_type_len[SKB_EXT_MPTCP] +
+#endif
+#if IS_ENABLED(CONFIG_NET_SOCK_MSG)
+ skb_ext_type_len[SKB_EXT_BPF] +
#endif
0;
}
diff --git a/net/core/skmsg.c b/net/core/skmsg.c
index f72fcb03d25c..2b5b8f05187a 100644
--- a/net/core/skmsg.c
+++ b/net/core/skmsg.c
@@ -525,7 +525,8 @@ static void sk_psock_backlog(struct work_struct *work)
len = skb->len;
off = 0;
start:
- ingress = tcp_skb_bpf_ingress(skb);
+ ingress = skb_bpf_ext_ingress(skb);
+ skb_ext_del(skb, SKB_EXT_BPF);
do {
ret = -EIO;
if (likely(psock->sk->sk_socket))
@@ -746,8 +747,13 @@ EXPORT_SYMBOL_GPL(sk_psock_msg_verdict);
static int sk_psock_bpf_run(struct sk_psock *psock, struct bpf_prog *prog,
struct sk_buff *skb)
{
- bpf_compute_data_end_sk_skb(skb);
- return bpf_prog_run_pin_on_cpu(prog, skb);
+ int ret;
+
+ tcp_skb_tsorted_save(skb) {
+ bpf_compute_data_end_sk_skb(skb);
+ ret = bpf_prog_run_pin_on_cpu(prog, skb);
+ } tcp_skb_tsorted_restore(skb);
+ return ret;
}
static void sk_psock_skb_redirect(struct sk_buff *skb)
@@ -755,7 +761,7 @@ 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_ext_redirect_fetch(skb);
/* This error is a buggy BPF program, it returned a redirect
* return code, but then didn't set a redirect interface.
*/
@@ -797,6 +803,9 @@ int sk_psock_tls_strp_read(struct sk_psock *psock, struct
sk_buff *skb)
struct bpf_prog *prog;
int ret = __SK_PASS;
+ if (!skb_ext_add(skb, SKB_EXT_BPF))
+ return __SK_DROP;
+
rcu_read_lock();
prog = READ_ONCE(psock->progs.skb_verdict);
if (likely(prog)) {
@@ -805,9 +814,9 @@ 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_bpf_ext_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_ext_redirect_fetch(skb));
skb->sk = NULL;
}
sk_psock_tls_verdict_apply(skb, psock->sk, ret);
@@ -819,7 +828,6 @@ 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;
@@ -831,9 +839,7 @@ 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_ext_set_ingress(skb);
/* If the queue is empty then we can submit directly
* into the msg queue. If its not empty we have to
* queue work otherwise we may get OOO data. Otherwise,
@@ -873,11 +879,15 @@ static void sk_psock_strp_read(struct strparser *strp,
struct sk_buff *skb)
goto out;
}
skb_set_owner_r(skb, sk);
+ if (!skb_ext_add(skb, SKB_EXT_BPF)) {
+ kfree_skb(skb);
+ goto out;
+ }
prog = READ_ONCE(psock->progs.skb_verdict);
if (likely(prog)) {
- tcp_skb_bpf_redirect_clear(skb);
+ skb_bpf_ext_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_ext_redirect_fetch(skb));
}
sk_psock_verdict_apply(psock, skb, ret);
out:
@@ -949,11 +959,17 @@ static int sk_psock_verdict_recv(read_descriptor_t *desc,
struct sk_buff *skb,
goto out;
}
skb_set_owner_r(skb, sk);
+ if (!skb_ext_add(skb, SKB_EXT_BPF)) {
+ len = 0;
+ kfree_skb(skb);
+ goto out;
+ }
+
prog = READ_ONCE(psock->progs.skb_verdict);
if (likely(prog)) {
- tcp_skb_bpf_redirect_clear(skb);
+ skb_bpf_ext_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_ext_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 37ff8e13e4cc..7b70fa290836 100644
--- a/net/core/sock_map.c
+++ b/net/core/sock_map.c
@@ -657,7 +657,7 @@ 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 skb_bpf_ext *ext = skb_ext_find(skb, SKB_EXT_BPF);
struct sock *sk;
if (unlikely(flags & ~(BPF_F_INGRESS)))
@@ -667,8 +667,8 @@ 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;
+ ext->flags = flags;
+ ext->sk_redir = sk;
return SK_PASS;
}
@@ -1250,7 +1250,7 @@ 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 skb_bpf_ext *ext = skb_ext_find(skb, SKB_EXT_BPF);
struct sock *sk;
if (unlikely(flags & ~(BPF_F_INGRESS)))
@@ -1260,8 +1260,8 @@ 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;
+ ext->flags = flags;
+ ext->sk_redir = sk;
return SK_PASS;
}
--
2.25.1
