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Date: Tue, 25 Oct 2016 15:30:12 -0700
From: David Ahern <dsa@...ulusnetworks.com>
To: netdev@...r.kernel.org
Cc: daniel@...que.org, ast@...com, daniel@...earbox.net,
David Ahern <dsa@...ulusnetworks.com>
Subject: [PATCH net-next 2/3] bpf: Add new cgroups prog type to enable sock modifications
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 <dsa@...ulusnetworks.com>
---
include/linux/filter.h | 2 +-
include/uapi/linux/bpf.h | 15 ++++++++
kernel/bpf/cgroup.c | 9 +++++
kernel/bpf/syscall.c | 4 +++
net/core/filter.c | 92 ++++++++++++++++++++++++++++++++++++++++++++++++
net/core/sock.c | 7 ++++
6 files changed, 128 insertions(+), 1 deletion(-)
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 6b62ee9a2f78..ce5283f221e7 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -99,11 +99,13 @@ 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_CREATE,
__MAX_BPF_ATTACH_TYPE
};
@@ -449,6 +451,15 @@ enum bpf_func_id {
*/
BPF_FUNC_get_numa_node_id,
+ /**
+ * sock_store_u32(sk, offset, val) - store bytes into sock
+ * @sk: pointer to sock
+ * @offset: offset within sock
+ * @val: value to write
+ * Return: 0 on success
+ */
+ BPF_FUNC_sock_store_u32,
+
__BPF_FUNC_MAX_ID,
};
@@ -524,6 +535,10 @@ 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 918c01a6f129..4fcb58013a3a 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_sk_create(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_CREATE:
+ ret = __cgroup_bpf_run_filter_sk_create(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 9abc88deabbc..3b7e30e28cd3 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -844,6 +844,9 @@ static int bpf_prog_attach(const union bpf_attr *attr)
ptype = BPF_PROG_TYPE_CGROUP_SKB;
break;
+ case BPF_CGROUP_INET_SOCK_CREATE:
+ ptype = BPF_PROG_TYPE_CGROUP_SOCK;
+ break;
default:
return -EINVAL;
}
@@ -879,6 +882,7 @@ 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_CREATE:
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 4552b8c93b99..775802881b01 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -2482,6 +2482,27 @@ static const struct bpf_func_proto bpf_xdp_event_output_proto = {
.arg5_type = ARG_CONST_STACK_SIZE,
};
+BPF_CALL_3(bpf_sock_store_u32, struct sock *, sk, u32, offset, u32, val)
+{
+ u8 *ptr = (u8 *)sk;
+
+ if (unlikely(offset > sizeof(*sk)))
+ return -EFAULT;
+
+ *((u32 *)ptr) = val;
+
+ return 0;
+}
+
+static const struct bpf_func_proto bpf_sock_store_u32_proto = {
+ .func = bpf_sock_store_u32,
+ .gpl_only = true,
+ .ret_type = RET_INTEGER,
+ .arg1_type = ARG_PTR_TO_CTX,
+ .arg2_type = ARG_ANYTHING,
+ .arg3_type = ARG_ANYTHING,
+};
+
static const struct bpf_func_proto *
sk_filter_func_proto(enum bpf_func_id func_id)
{
@@ -2593,6 +2614,17 @@ 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)
+{
+ switch (func_id) {
+ case BPF_FUNC_sock_store_u32:
+ return &bpf_sock_store_u32_proto;
+ default:
+ return NULL;
+ }
+}
+
static bool __is_valid_access(int off, int size, enum bpf_access_type type)
{
if (off < 0 || off >= sizeof(struct __sk_buff))
@@ -2630,6 +2662,30 @@ 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 >= sizeof(struct bpf_sock))
+ return false;
+ /* The verifier guarantees that size > 0. */
+ if (off % size != 0)
+ return false;
+ if (size != sizeof(__u32))
+ return false;
+
+ return true;
+}
+
static int tc_cls_act_prologue(struct bpf_insn *insn_buf, bool direct_write,
const struct bpf_prog *prog)
{
@@ -2888,6 +2944,30 @@ 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,
@@ -2961,6 +3041,12 @@ 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,
@@ -2986,6 +3072,11 @@ 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);
@@ -2993,6 +3084,7 @@ 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/core/sock.c b/net/core/sock.c
index d8e4532e89e7..936f221cc6c6 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -1404,6 +1404,13 @@ struct sock *sk_alloc(struct net *net, int family, gfp_t priority,
cgroup_sk_alloc(&sk->sk_cgrp_data);
sock_update_classid(&sk->sk_cgrp_data);
sock_update_netprioidx(&sk->sk_cgrp_data);
+
+ if (!kern &&
+ cgroup_bpf_run_filter(sk, NULL,
+ BPF_CGROUP_INET_SOCK_CREATE)) {
+ sk_free(sk);
+ sk = NULL;
+ }
}
return sk;
--
2.1.4
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