[PATCH bpf-next 2/7] bpf: add bpf_skc_to_mptcp_sock_proto

Mat Martineau
2022-04-20T22:25:20Z

From: Geliang Tang <geliang.tang@suse.com>

This patch implements a new struct bpf_func_proto, named
bpf_skc_to_mptcp_sock_proto. Define a new bpf_id BTF_SOCK_TYPE_MPTCP,
and a new helper bpf_skc_to_mptcp_sock(), which invokes another new
helper bpf_mptcp_sock_from_subflow() in net/mptcp/bpf.c to get struct
mptcp_sock from a given subflow socket.

Co-developed-by: Nicolas Rybowski <nicolas.rybowski@tessares.net>
Signed-off-by: Nicolas Rybowski <nicolas.rybowski@tessares.net>
Co-developed-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Geliang Tang <geliang.tang@suse.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
---
include/linux/btf_ids.h | 3 ++-
include/net/mptcp.h | 6 ++++++
include/uapi/linux/bpf.h | 7 +++++++
net/core/filter.c | 17 +++++++++++++++++
net/mptcp/Makefile | 4 ++++
net/mptcp/bpf.c | 22 ++++++++++++++++++++++
scripts/bpf_doc.py | 2 ++
tools/include/uapi/linux/bpf.h | 7 +++++++
8 files changed, 67 insertions(+), 1 deletion(-)
create mode 100644 net/mptcp/bpf.c

diff --git a/include/linux/btf_ids.h b/include/linux/btf_ids.h
index bc5d9cc34e4c..335a19092368 100644
--- a/include/linux/btf_ids.h
+++ b/include/linux/btf_ids.h
@@ -178,7 +178,8 @@ extern struct btf_id_set name;
BTF_SOCK_TYPE(BTF_SOCK_TYPE_TCP6, tcp6_sock) \
BTF_SOCK_TYPE(BTF_SOCK_TYPE_UDP, udp_sock) \
BTF_SOCK_TYPE(BTF_SOCK_TYPE_UDP6, udp6_sock) \
- BTF_SOCK_TYPE(BTF_SOCK_TYPE_UNIX, unix_sock)
+ BTF_SOCK_TYPE(BTF_SOCK_TYPE_UNIX, unix_sock) \
+ BTF_SOCK_TYPE(BTF_SOCK_TYPE_MPTCP, mptcp_sock)

enum {
#define BTF_SOCK_TYPE(name, str) name,
diff --git a/include/net/mptcp.h b/include/net/mptcp.h
index 0a3b0fb04a3b..5b3a6f783182 100644
--- a/include/net/mptcp.h
+++ b/include/net/mptcp.h
@@ -283,4 +283,10 @@ static inline int mptcpv6_init(void) { return 0; }
static inline void mptcpv6_handle_mapped(struct sock *sk, bool mapped) { }
#endif

+#if defined(CONFIG_MPTCP) && defined(CONFIG_BPF_JIT) && defined(CONFIG_BPF_SYSCALL)
+struct mptcp_sock *bpf_mptcp_sock_from_subflow(struct sock *sk);
+#else
+static inline struct mptcp_sock *bpf_mptcp_sock_from_subflow(struct sock *sk) { return NULL; }
+#endif
+
#endif /* __NET_MPTCP_H */
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 9ef1f3e1c22f..785f2cb15495 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -5143,6 +5143,12 @@ union bpf_attr {
* The **hash_algo** is returned on success,
* **-EOPNOTSUP** if the hash calculation failed or **-EINVAL** if
* invalid arguments are passed.
+ *
+ * struct mptcp_sock *bpf_skc_to_mptcp_sock(void *sk)
+ * Description
+ * Dynamically cast a *sk* pointer to a *mptcp_sock* pointer.
+ * Return
+ * *sk* if casting is valid, or **NULL** otherwise.
*/
#define __BPF_FUNC_MAPPER(FN) \
FN(unspec), \
@@ -5339,6 +5345,7 @@ union bpf_attr {
FN(copy_from_user_task), \
FN(skb_set_tstamp), \
FN(ima_file_hash), \
+ FN(skc_to_mptcp_sock), \
/* */

/* integer value in 'imm' field of BPF_CALL instruction selects which helper
diff --git a/net/core/filter.c b/net/core/filter.c
index 7b1867f1f422..4081c55f6f78 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -78,6 +78,7 @@
#include <linux/btf_ids.h>
#include <net/tls.h>
#include <net/xdp.h>
+#include <net/mptcp.h>

static const struct bpf_func_proto *
bpf_sk_base_func_proto(enum bpf_func_id func_id);
@@ -11279,6 +11280,19 @@ const struct bpf_func_proto bpf_skc_to_unix_sock_proto = {
.ret_btf_id = &btf_sock_ids[BTF_SOCK_TYPE_UNIX],
};

+BPF_CALL_1(bpf_skc_to_mptcp_sock, struct sock *, sk)
+{
+ return (unsigned long)bpf_mptcp_sock_from_subflow(sk);
+}
+
+static const struct bpf_func_proto bpf_skc_to_mptcp_sock_proto = {
+ .func = bpf_skc_to_mptcp_sock,
+ .gpl_only = false,
+ .ret_type = RET_PTR_TO_BTF_ID_OR_NULL,
+ .arg1_type = ARG_PTR_TO_SOCK_COMMON,
+ .ret_btf_id = &btf_sock_ids[BTF_SOCK_TYPE_MPTCP],
+};
+
BPF_CALL_1(bpf_sock_from_file, struct file *, file)
{
return (unsigned long)sock_from_file(file);
@@ -11321,6 +11335,9 @@ bpf_sk_base_func_proto(enum bpf_func_id func_id)
case BPF_FUNC_skc_to_unix_sock:
func = &bpf_skc_to_unix_sock_proto;
break;
+ case BPF_FUNC_skc_to_mptcp_sock:
+ func = &bpf_skc_to_mptcp_sock_proto;
+ break;
case BPF_FUNC_ktime_get_coarse_ns:
return &bpf_ktime_get_coarse_ns_proto;
default:
diff --git a/net/mptcp/Makefile b/net/mptcp/Makefile
index e54daceac58b..168c55d1c917 100644
--- a/net/mptcp/Makefile
+++ b/net/mptcp/Makefile
@@ -10,3 +10,7 @@ obj-$(CONFIG_INET_MPTCP_DIAG) += mptcp_diag.o
mptcp_crypto_test-objs := crypto_test.o
mptcp_token_test-objs := token_test.o
obj-$(CONFIG_MPTCP_KUNIT_TEST) += mptcp_crypto_test.o mptcp_token_test.o
+
+ifeq ($(CONFIG_BPF_JIT),y)
+obj-$(CONFIG_BPF_SYSCALL) += bpf.o
+endif
diff --git a/net/mptcp/bpf.c b/net/mptcp/bpf.c
new file mode 100644
index 000000000000..535602ba2582
--- /dev/null
+++ b/net/mptcp/bpf.c
@@ -0,0 +1,22 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Multipath TCP
+ *
+ * Copyright (c) 2020, Tessares SA.
+ * Copyright (c) 2022, SUSE.
+ *
+ * Author: Nicolas Rybowski <nicolas.rybowski@tessares.net>
+ */
+
+#define pr_fmt(fmt) "MPTCP: " fmt
+
+#include <linux/bpf.h>
+#include "protocol.h"
+
+struct mptcp_sock *bpf_mptcp_sock_from_subflow(struct sock *sk)
+{
+ if (sk && sk_fullsock(sk) && sk->sk_protocol == IPPROTO_TCP && sk_is_mptcp(sk))
+ return mptcp_sk(mptcp_subflow_ctx(sk)->conn);
+
+ return NULL;
+}
+EXPORT_SYMBOL(bpf_mptcp_sock_from_subflow);
diff --git a/scripts/bpf_doc.py b/scripts/bpf_doc.py
index 096625242475..d5452f7eb996 100755
--- a/scripts/bpf_doc.py
+++ b/scripts/bpf_doc.py
@@ -633,6 +633,7 @@ class PrinterHelpers(Printer):
'struct socket',
'struct file',
'struct bpf_timer',
+ 'struct mptcp_sock',
]
known_types = {
'...',
@@ -682,6 +683,7 @@ class PrinterHelpers(Printer):
'struct socket',
'struct file',
'struct bpf_timer',
+ 'struct mptcp_sock',
}
mapped_types = {
'u8': '__u8',
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 9ef1f3e1c22f..785f2cb15495 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -5143,6 +5143,12 @@ union bpf_attr {
* The **hash_algo** is returned on success,
* **-EOPNOTSUP** if the hash calculation failed or **-EINVAL** if
* invalid arguments are passed.
+ *
+ * struct mptcp_sock *bpf_skc_to_mptcp_sock(void *sk)
+ * Description
+ * Dynamically cast a *sk* pointer to a *mptcp_sock* pointer.
+ * Return
+ * *sk* if casting is valid, or **NULL** otherwise.
*/
#define __BPF_FUNC_MAPPER(FN) \
FN(unspec), \
@@ -5339,6 +5345,7 @@ union bpf_attr {
FN(copy_from_user_task), \
FN(skb_set_tstamp), \
FN(ima_file_hash), \
+ FN(skc_to_mptcp_sock), \
/* */

/* integer value in 'imm' field of BPF_CALL instruction selects which helper
--
2.36.0