Add new cgroup based program type, BPF_PROG_TYPE_CGROUP_SOCK. Similar to
BPF_PROG_TYPE_CGROUP_SKB programs can be attached to a cgroup and run
any time a process in the cgroup opens an AF_INET or AF_INET6 socket.
Currently only sk_bound_dev_if is exported to userspace for modification
by a bpf program.
This allows a cgroup to be configured such that AF_INET{6} sockets opened
by processes are automatically bound to a specific device. In turn, this
enables the running of programs that do not support SO_BINDTODEVICE in a
specific VRF context / L3 domain.
Signed-off-by: David Ahern <d...@cumulusnetworks.com>
---
v3
- reverted to new prog type BPF_PROG_TYPE_CGROUP_SOCK
- dropped the subtype
v2
- dropped the bpf_sock_store_u32 helper
- dropped the new prog type BPF_PROG_TYPE_CGROUP_SOCK
- moved valid access and context conversion to use subtype
- dropped CREATE from BPF_CGROUP_INET_SOCK and related function names
- moved running of filter from sk_alloc to inet{6}_create
include/linux/bpf-cgroup.h | 11 ++++++++
include/linux/filter.h | 2 +-
include/uapi/linux/bpf.h | 6 +++++
kernel/bpf/cgroup.c | 9 +++++++
kernel/bpf/syscall.c | 5 +++-
net/core/filter.c | 65 ++++++++++++++++++++++++++++++++++++++++++++++
net/ipv4/af_inet.c | 12 ++++++++-
net/ipv6/af_inet6.c | 8 ++++++
8 files changed, 115 insertions(+), 3 deletions(-)
diff --git a/include/linux/bpf-cgroup.h b/include/linux/bpf-cgroup.h
index ec80d0c0953e..2ca529664c8b 100644
--- a/include/linux/bpf-cgroup.h
+++ b/include/linux/bpf-cgroup.h
@@ -64,6 +64,16 @@ int __cgroup_bpf_run_filter(struct sock *sk,
__ret; \
})
+#define BPF_CGROUP_RUN_PROG_INET_SOCK(sk) \
+({ \
+ int __ret = 0; \
+ if (cgroup_bpf_enabled && sk) { \
+ __ret = __cgroup_bpf_run_filter(sk, NULL, \
+ BPF_CGROUP_INET_SOCK); \
+ } \
+ __ret; \
+})
+
#else
struct cgroup_bpf {};
@@ -73,6 +83,7 @@ static inline void cgroup_bpf_inherit(struct cgroup *cgrp,
#define BPF_CGROUP_RUN_PROG_INET_INGRESS(sk,skb) ({ 0; })
#define BPF_CGROUP_RUN_PROG_INET_EGRESS(sk,skb) ({ 0; })
+#define BPF_CGROUP_RUN_PROG_INET_SOCK(sk) ({ 0; })
#endif /* CONFIG_CGROUP_BPF */
diff --git a/include/linux/filter.h b/include/linux/filter.h
index 1f09c521adfe..808e158742a2 100644
--- a/include/linux/filter.h
+++ b/include/linux/filter.h
@@ -408,7 +408,7 @@ struct bpf_prog {
enum bpf_prog_type type; /* Type of BPF program */
struct bpf_prog_aux *aux; /* Auxiliary fields */
struct sock_fprog_kern *orig_prog; /* Original BPF program */
- unsigned int (*bpf_func)(const struct sk_buff *skb,
+ unsigned int (*bpf_func)(const void *ctx,
const struct bpf_insn *filter);
/* Instructions for interpreter */
union {
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 1370a9d1456f..8f410ecdaac4 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -101,11 +101,13 @@ enum bpf_prog_type {
BPF_PROG_TYPE_XDP,
BPF_PROG_TYPE_PERF_EVENT,
BPF_PROG_TYPE_CGROUP_SKB,
+ BPF_PROG_TYPE_CGROUP_SOCK,
};
enum bpf_attach_type {
BPF_CGROUP_INET_INGRESS,
BPF_CGROUP_INET_EGRESS,
+ BPF_CGROUP_INET_SOCK,
__MAX_BPF_ATTACH_TYPE
};
@@ -537,6 +539,10 @@ struct bpf_tunnel_key {
__u32 tunnel_label;
};
+struct bpf_sock {
+ __u32 bound_dev_if;
+};
+
/* User return codes for XDP prog type.
* A valid XDP program must return one of these defined values. All other
* return codes are reserved for future use. Unknown return codes will result
diff --git a/kernel/bpf/cgroup.c b/kernel/bpf/cgroup.c
index d5746aec8f34..796e39aa28f5 100644
--- a/kernel/bpf/cgroup.c
+++ b/kernel/bpf/cgroup.c
@@ -117,6 +117,12 @@ void __cgroup_bpf_update(struct cgroup *cgrp,
}
}
+static int __cgroup_bpf_run_filter_sock(struct sock *sk,
+ struct bpf_prog *prog)
+{
+ return prog->bpf_func(sk, prog->insnsi) == 1 ? 0 : -EPERM;
+}
+
static int __cgroup_bpf_run_filter_skb(struct sk_buff *skb,
struct bpf_prog *prog)
{
@@ -171,6 +177,9 @@ int __cgroup_bpf_run_filter(struct sock *sk,
case BPF_CGROUP_INET_EGRESS:
ret = __cgroup_bpf_run_filter_skb(skb, prog);
break;
+ case BPF_CGROUP_INET_SOCK:
+ ret = __cgroup_bpf_run_filter_sock(sk, prog);
+ break;
/* make gcc happy else complains about missing enum value */
default:
return 0;
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index c2bce596e842..f5247901a4cc 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -856,7 +856,9 @@ static int bpf_prog_attach(const union bpf_attr *attr)
case BPF_CGROUP_INET_EGRESS:
ptype = BPF_PROG_TYPE_CGROUP_SKB;
break;
-
+ case BPF_CGROUP_INET_SOCK:
+ ptype = BPF_PROG_TYPE_CGROUP_SOCK;
+ break;
default:
return -EINVAL;
}
@@ -892,6 +894,7 @@ static int bpf_prog_detach(const union bpf_attr *attr)
switch (attr->attach_type) {
case BPF_CGROUP_INET_INGRESS:
case BPF_CGROUP_INET_EGRESS:
+ case BPF_CGROUP_INET_SOCK:
cgrp = cgroup_get_from_fd(attr->target_fd);
if (IS_ERR(cgrp))
return PTR_ERR(cgrp);
diff --git a/net/core/filter.c b/net/core/filter.c
index ea315af56511..593b6b664c0c 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -2645,6 +2645,12 @@ cg_skb_func_proto(enum bpf_func_id func_id)
}
}
+static const struct bpf_func_proto *
+cg_sock_func_proto(enum bpf_func_id func_id)
+{
+ return NULL;
+}
+
static bool __is_valid_access(int off, int size, enum bpf_access_type type)
{
if (off < 0 || off >= sizeof(struct __sk_buff))
@@ -2682,6 +2688,29 @@ static bool sk_filter_is_valid_access(int off, int size,
return __is_valid_access(off, size, type);
}
+static bool sock_filter_is_valid_access(int off, int size,
+ enum bpf_access_type type,
+ enum bpf_reg_type *reg_type)
+{
+ if (type == BPF_WRITE) {
+ switch (off) {
+ case offsetof(struct bpf_sock, bound_dev_if):
+ break;
+ default:
+ return false;
+ }
+ }
+
+ if (off < 0 || off + size > sizeof(struct bpf_sock))
+ return false;
+
+ /* The verifier guarantees that size > 0. */
+ if (off % size != 0)
+ return false;
+
+ return true;
+}
+
static int tc_cls_act_prologue(struct bpf_insn *insn_buf, bool direct_write,
const struct bpf_prog *prog)
{
@@ -2940,6 +2969,30 @@ static u32 sk_filter_convert_ctx_access(enum
bpf_access_type type, int dst_reg,
return insn - insn_buf;
}
+static u32 sock_filter_convert_ctx_access(enum bpf_access_type type,
+ int dst_reg, int src_reg,
+ int ctx_off,
+ struct bpf_insn *insn_buf,
+ struct bpf_prog *prog)
+{
+ struct bpf_insn *insn = insn_buf;
+
+ switch (ctx_off) {
+ case offsetof(struct bpf_sock, bound_dev_if):
+ BUILD_BUG_ON(FIELD_SIZEOF(struct sock, sk_bound_dev_if) != 4);
+
+ if (type == BPF_WRITE)
+ *insn++ = BPF_STX_MEM(BPF_W, dst_reg, src_reg,
+ offsetof(struct sock, sk_bound_dev_if));
+ else
+ *insn++ = BPF_LDX_MEM(BPF_W, dst_reg, src_reg,
+ offsetof(struct sock, sk_bound_dev_if));
+ break;
+ }
+
+ return insn - insn_buf;
+}
+
static u32 tc_cls_act_convert_ctx_access(enum bpf_access_type type, int
dst_reg,
int src_reg, int ctx_off,
struct bpf_insn *insn_buf,
@@ -3013,6 +3066,12 @@ static const struct bpf_verifier_ops cg_skb_ops = {
.convert_ctx_access = sk_filter_convert_ctx_access,
};
+static const struct bpf_verifier_ops cg_sock_ops = {
+ .get_func_proto = cg_sock_func_proto,
+ .is_valid_access = sock_filter_is_valid_access,
+ .convert_ctx_access = sock_filter_convert_ctx_access,
+};
+
static struct bpf_prog_type_list sk_filter_type __read_mostly = {
.ops = &sk_filter_ops,
.type = BPF_PROG_TYPE_SOCKET_FILTER,
@@ -3038,6 +3097,11 @@ static struct bpf_prog_type_list cg_skb_type
__read_mostly = {
.type = BPF_PROG_TYPE_CGROUP_SKB,
};
+static struct bpf_prog_type_list cg_sock_type __read_mostly = {
+ .ops = &cg_sock_ops,
+ .type = BPF_PROG_TYPE_CGROUP_SOCK
+};
+
static int __init register_sk_filter_ops(void)
{
bpf_register_prog_type(&sk_filter_type);
@@ -3045,6 +3109,7 @@ static int __init register_sk_filter_ops(void)
bpf_register_prog_type(&sched_act_type);
bpf_register_prog_type(&xdp_type);
bpf_register_prog_type(&cg_skb_type);
+ bpf_register_prog_type(&cg_sock_type);
return 0;
}
diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c
index 5ddf5cda07f4..24d2550492ee 100644
--- a/net/ipv4/af_inet.c
+++ b/net/ipv4/af_inet.c
@@ -374,8 +374,18 @@ static int inet_create(struct net *net, struct socket
*sock, int protocol,
if (sk->sk_prot->init) {
err = sk->sk_prot->init(sk);
- if (err)
+ if (err) {
+ sk_common_release(sk);
+ goto out;
+ }
+ }
+
+ if (!kern) {
+ err = BPF_CGROUP_RUN_PROG_INET_SOCK(sk);
+ if (err) {
sk_common_release(sk);
+ goto out;
+ }
}
out:
return err;
diff --git a/net/ipv6/af_inet6.c b/net/ipv6/af_inet6.c
index d424f3a3737a..237e654ba717 100644
--- a/net/ipv6/af_inet6.c
+++ b/net/ipv6/af_inet6.c
@@ -258,6 +258,14 @@ static int inet6_create(struct net *net, struct socket
*sock, int protocol,
goto out;
}
}
+
+ if (!kern) {
+ err = BPF_CGROUP_RUN_PROG_INET_SOCK(sk);
+ if (err) {
+ sk_common_release(sk);
+ goto out;
+ }
+ }
out:
return err;
out_rcu_unlock:
--
2.1.4
