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Message-Id: <1480610888-31082-3-git-send-email-dsa@cumulusnetworks.com>
Date: Thu, 1 Dec 2016 08:48:04 -0800
From: David Ahern <dsa@...ulusnetworks.com>
To: netdev@...r.kernel.org
Cc: daniel@...que.org, ast@...com, daniel@...earbox.net,
maheshb@...gle.com, tgraf@...g.ch,
David Ahern <dsa@...ulusnetworks.com>
Subject: [PATCH v7 net-next 2/6] bpf: Add new cgroup attach 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>
---
v7
- no change
v6
- added size check to sock_filter_is_valid_access; accesses must be u32
v5
- no change
v4
- dropped tweak to bpf_func signature
- dropped cg_sock_func_proto in favor of sk_filter_func_proto
- new __cgroup_bpf_run_filter_sk versus overloading __cgroup_bpf_run_filter
- reverted BPF_CGROUP_INET_SOCK to BPF_CGROUP_INET_SOCK_CREATE
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 | 14 +++++++++++
include/uapi/linux/bpf.h | 6 +++++
kernel/bpf/cgroup.c | 33 ++++++++++++++++++++++++
kernel/bpf/syscall.c | 5 +++-
net/core/filter.c | 62 ++++++++++++++++++++++++++++++++++++++++++++++
net/ipv4/af_inet.c | 12 ++++++++-
net/ipv6/af_inet6.c | 8 ++++++
7 files changed, 138 insertions(+), 2 deletions(-)
diff --git a/include/linux/bpf-cgroup.h b/include/linux/bpf-cgroup.h
index af2ca8b432c0..7b6e5d168c95 100644
--- a/include/linux/bpf-cgroup.h
+++ b/include/linux/bpf-cgroup.h
@@ -40,6 +40,9 @@ int __cgroup_bpf_run_filter_skb(struct sock *sk,
struct sk_buff *skb,
enum bpf_attach_type type);
+int __cgroup_bpf_run_filter_sk(struct sock *sk,
+ enum bpf_attach_type type);
+
/* Wrappers for __cgroup_bpf_run_filter_skb() guarded by cgroup_bpf_enabled. */
#define BPF_CGROUP_RUN_PROG_INET_INGRESS(sk, skb) \
({ \
@@ -63,6 +66,16 @@ int __cgroup_bpf_run_filter_skb(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(sk, \
+ BPF_CGROUP_INET_SOCK_CREATE); \
+ } \
+ __ret; \
+})
+
#else
struct cgroup_bpf {};
@@ -72,6 +85,7 @@ 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/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 1370a9d1456f..75964e00d947 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_CREATE,
__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 8fe55ffd109d..a515f7b007c6 100644
--- a/kernel/bpf/cgroup.c
+++ b/kernel/bpf/cgroup.c
@@ -165,3 +165,36 @@ int __cgroup_bpf_run_filter_skb(struct sock *sk,
return ret;
}
EXPORT_SYMBOL(__cgroup_bpf_run_filter_skb);
+
+/**
+ * __cgroup_bpf_run_filter_sk() - Run a program on a sock
+ * @sk: sock structure to manipulate
+ * @type: The type of program to be exectuted
+ *
+ * socket is passed is expected to be of type INET or INET6.
+ *
+ * The program type passed in via @type must be suitable for sock
+ * filtering. No further check is performed to assert that.
+ *
+ * This function will return %-EPERM if any if an attached program was found
+ * and if it returned != 1 during execution. In all other cases, 0 is returned.
+ */
+int __cgroup_bpf_run_filter_sk(struct sock *sk,
+ enum bpf_attach_type type)
+{
+ struct cgroup *cgrp = sock_cgroup_ptr(&sk->sk_cgrp_data);
+ struct bpf_prog *prog;
+ int ret = 0;
+
+
+ rcu_read_lock();
+
+ prog = rcu_dereference(cgrp->bpf.effective[type]);
+ if (prog)
+ ret = BPF_PROG_RUN(prog, sk) == 1 ? 0 : -EPERM;
+
+ rcu_read_unlock();
+
+ return ret;
+}
+EXPORT_SYMBOL(__cgroup_bpf_run_filter_sk);
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 5518a6839ab1..85af86c496cd 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -869,7 +869,9 @@ 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_CREATE:
+ ptype = BPF_PROG_TYPE_CGROUP_SOCK;
+ break;
default:
return -EINVAL;
}
@@ -905,6 +907,7 @@ 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 698a262b8ebb..5ee722dc097d 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -2676,6 +2676,32 @@ 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;
+
+ 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)
{
@@ -2934,6 +2960,30 @@ 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,
@@ -3007,6 +3057,12 @@ 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 = sk_filter_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,
@@ -3032,6 +3088,11 @@ 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);
@@ -3039,6 +3100,7 @@ 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
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