From: Martin KaFai Lau <ka...@fb.com>
This patch adds a new bpf helper BPF_FUNC_tcp_enter_cwr
"int bpf_tcp_enter_cwr(struct bpf_tcp_sock *tp)".
It is added to BPF_PROG_TYPE_CGROUP_SKB which can be attached
to the egress path where the bpf prog is called by
ip_finish_output() or ip6_finish_output(). The verifier
ensures that the parameter must be a tcp_sock.
This helper makes a tcp_sock enter CWR state. It can be used
by a bpf_prog to manage egress network bandwidth limit per
cgroupv2. A later patch will have a sample program to
show how it can be used to limit bandwidth usage per cgroupv2.
To ensure it is only called from BPF_CGROUP_INET_EGRESS, the
attr->expected_attach_type must be specified as BPF_CGROUP_INET_EGRESS
during load time if the prog uses this new helper.
The newly added prog->enforce_expected_attach_type bit will also be set
if this new helper is used. This bit is for backward compatibility reason
because currently prog->expected_attach_type has been ignored in
BPF_PROG_TYPE_CGROUP_SKB. During attach time,
prog->expected_attach_type is only enforced if the
prog->enforce_expected_attach_type bit is set.
i.e. prog->expected_attach_type is only enforced if this new helper
is used by the prog.
Signed-off-by: Lawrence Brakmo <bra...@fb.com>
Signed-off-by: Martin KaFai Lau <ka...@fb.com>
---
include/linux/bpf.h | 1 +
include/linux/filter.h | 3 ++-
include/uapi/linux/bpf.h | 9 ++++++++-
kernel/bpf/syscall.c | 12 ++++++++++++
kernel/bpf/verifier.c | 4 ++++
net/core/filter.c | 25 +++++++++++++++++++++++++
6 files changed, 52 insertions(+), 2 deletions(-)
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index d5ba2fc01af3..2d54ba7cf9dd 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -195,6 +195,7 @@ enum bpf_arg_type {
ARG_PTR_TO_SOCKET, /* pointer to bpf_sock */
ARG_PTR_TO_SPIN_LOCK, /* pointer to bpf_spin_lock */
ARG_PTR_TO_SOCK_COMMON, /* pointer to sock_common */
+ ARG_PTR_TO_TCP_SOCK, /* pointer to tcp_sock */
};
/* type of values returned from helper functions */
diff --git a/include/linux/filter.h b/include/linux/filter.h
index f32b3eca5a04..c6e878bdc5a6 100644
--- a/include/linux/filter.h
+++ b/include/linux/filter.h
@@ -510,7 +510,8 @@ struct bpf_prog {
blinded:1, /* Was blinded */
is_func:1, /* program is a bpf function */
kprobe_override:1, /* Do we override a kprobe?
*/
- has_callchain_buf:1; /* callchain buffer
allocated? */
+ has_callchain_buf:1, /* callchain buffer
allocated? */
+ enforce_expected_attach_type:1; /* Enforce
expected_attach_type checking at attach time */
enum bpf_prog_type type; /* Type of BPF program */
enum bpf_attach_type expected_attach_type; /* For some prog types */
u32 len; /* Number of filter blocks */
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index bcdd2474eee7..95b5058fa945 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -2359,6 +2359,12 @@ union bpf_attr {
* Return
* A **struct bpf_tcp_sock** pointer on success, or NULL in
* case of failure.
+ *
+ * int bpf_tcp_enter_cwr(struct bpf_tcp_sock *tp)
+ * Description
+ * Make a tcp_sock enter CWR state.
+ * Return
+ * 0 on success, or a negative error in case of failure.
*/
#define __BPF_FUNC_MAPPER(FN) \
FN(unspec), \
@@ -2457,7 +2463,8 @@ union bpf_attr {
FN(spin_lock), \
FN(spin_unlock), \
FN(sk_fullsock), \
- FN(tcp_sock),
+ FN(tcp_sock), \
+ FN(tcp_enter_cwr),
/* integer value in 'imm' field of BPF_CALL instruction selects which helper
* function eBPF program intends to call
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index ec7c552af76b..9a478f2875cd 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -1482,6 +1482,14 @@ bpf_prog_load_check_attach_type(enum bpf_prog_type
prog_type,
default:
return -EINVAL;
}
+ case BPF_PROG_TYPE_CGROUP_SKB:
+ switch (expected_attach_type) {
+ case BPF_CGROUP_INET_INGRESS:
+ case BPF_CGROUP_INET_EGRESS:
+ return 0;
+ default:
+ return -EINVAL;
+ }
default:
return 0;
}
@@ -1725,6 +1733,10 @@ static int bpf_prog_attach_check_attach_type(const
struct bpf_prog *prog,
case BPF_PROG_TYPE_CGROUP_SOCK:
case BPF_PROG_TYPE_CGROUP_SOCK_ADDR:
return attach_type == prog->expected_attach_type ? 0 : -EINVAL;
+ case BPF_PROG_TYPE_CGROUP_SKB:
+ return prog->enforce_expected_attach_type &&
+ prog->expected_attach_type != attach_type ?
+ -EINVAL : 0;
default:
return 0;
}
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 1b9496c41383..95fb385c6f3c 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -2424,6 +2424,10 @@ static int check_func_arg(struct bpf_verifier_env *env,
u32 regno,
return -EFAULT;
}
meta->ptr_id = reg->id;
+ } else if (arg_type == ARG_PTR_TO_TCP_SOCK) {
+ expected_type = PTR_TO_TCP_SOCK;
+ if (type != expected_type)
+ goto err_type;
} else if (arg_type == ARG_PTR_TO_SPIN_LOCK) {
if (meta->func_id == BPF_FUNC_spin_lock) {
if (process_spin_lock(env, regno, true))
diff --git a/net/core/filter.c b/net/core/filter.c
index 97916eedfe69..ca57ef25279c 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -5426,6 +5426,24 @@ static const struct bpf_func_proto bpf_tcp_sock_proto = {
.arg1_type = ARG_PTR_TO_SOCK_COMMON,
};
+BPF_CALL_1(bpf_tcp_enter_cwr, struct tcp_sock *, tp)
+{
+ struct sock *sk = (struct sock *)tp;
+
+ if (sk->sk_state == TCP_ESTABLISHED) {
+ tcp_enter_cwr(sk);
+ return 0;
+ }
+
+ return -EINVAL;
+}
+
+static const struct bpf_func_proto bpf_tcp_enter_cwr_proto = {
+ .func = bpf_tcp_enter_cwr,
+ .gpl_only = false,
+ .ret_type = RET_INTEGER,
+ .arg1_type = ARG_PTR_TO_TCP_SOCK,
+};
#endif /* CONFIG_INET */
bool bpf_helper_changes_pkt_data(void *func)
@@ -5585,6 +5603,13 @@ cg_skb_func_proto(enum bpf_func_id func_id, struct
bpf_prog *prog)
#ifdef CONFIG_INET
case BPF_FUNC_tcp_sock:
return &bpf_tcp_sock_proto;
+ case BPF_FUNC_tcp_enter_cwr:
+ if (prog->expected_attach_type == BPF_CGROUP_INET_EGRESS) {
+ prog->enforce_expected_attach_type = 1;
+ return &bpf_tcp_enter_cwr_proto;
+ } else {
+ return NULL;
+ }
#endif
default:
return sk_filter_func_proto(func_id, prog);
--
2.17.1
