* [PATCH v7 bpf-next 0/2] bpf: add cg_skb_is_valid_access
@ 2018-10-19 16:27 Song Liu
2018-10-19 16:27 ` [PATCH v7 bpf-next 1/2] bpf: add cg_skb_is_valid_access for BPF_PROG_TYPE_CGROUP_SKB Song Liu
2018-10-19 16:27 ` [PATCH v7 bpf-next 2/2] bpf: add tests for direct packet access from CGROUP_SKB Song Liu
0 siblings, 2 replies; 4+ messages in thread
From: Song Liu @ 2018-10-19 16:27 UTC (permalink / raw)
To: netdev; +Cc: ast, daniel, kernel-team, edumazet, Song Liu
Changes v6 -> v7:
1. Make dummy sk a global variable (test_run_sk).
Changes v5 -> v6:
1. Fixed dummy sk in bpf_prog_test_run_skb() as suggested by Eric Dumazet.
Changes v4 -> v5:
1. Replaced bpf_compute_and_save_data_pointers() with
bpf_compute_and_save_data_end();
Replaced bpf_restore_data_pointers() with bpf_restore_data_end().
2. Fixed indentation in test_verifier.c
Changes v3 -> v4:
1. Fixed crash issue reported by Alexei.
Changes v2 -> v3:
1. Added helper function bpf_compute_and_save_data_pointers() and
bpf_restore_data_pointers().
Changes v1 -> v2:
1. Updated the list of read-only fields, and read-write fields.
2. Added dummy sk to bpf_prog_test_run_skb().
This set enables BPF program of type BPF_PROG_TYPE_CGROUP_SKB to access
some __skb_buff data directly.
Song Liu (2):
bpf: add cg_skb_is_valid_access for BPF_PROG_TYPE_CGROUP_SKB
bpf: add tests for direct packet access from CGROUP_SKB
include/linux/filter.h | 21 +++
kernel/bpf/cgroup.c | 6 +
net/bpf/test_run.c | 8 +
net/core/filter.c | 36 ++++-
tools/testing/selftests/bpf/test_verifier.c | 171 ++++++++++++++++++++
5 files changed, 241 insertions(+), 1 deletion(-)
^ permalink raw reply [flat|nested] 4+ messages in thread
* [PATCH v7 bpf-next 1/2] bpf: add cg_skb_is_valid_access for BPF_PROG_TYPE_CGROUP_SKB
2018-10-19 16:27 [PATCH v7 bpf-next 0/2] bpf: add cg_skb_is_valid_access Song Liu
@ 2018-10-19 16:27 ` Song Liu
2018-10-19 16:27 ` [PATCH v7 bpf-next 2/2] bpf: add tests for direct packet access from CGROUP_SKB Song Liu
1 sibling, 0 replies; 4+ messages in thread
From: Song Liu @ 2018-10-19 16:27 UTC (permalink / raw)
To: netdev; +Cc: ast, daniel, kernel-team, edumazet, Song Liu
BPF programs of BPF_PROG_TYPE_CGROUP_SKB need to access headers in the
skb. This patch enables direct access of skb for these programs.
Two helper functions bpf_compute_and_save_data_end() and
bpf_restore_data_end() are introduced. There are used in
__cgroup_bpf_run_filter_skb(), to compute proper data_end for the
BPF program, and restore original data afterwards.
Signed-off-by: Song Liu <songliubraving@fb.com>
---
include/linux/filter.h | 21 +++++++++++++++++++++
kernel/bpf/cgroup.c | 6 ++++++
net/core/filter.c | 36 +++++++++++++++++++++++++++++++++++-
3 files changed, 62 insertions(+), 1 deletion(-)
diff --git a/include/linux/filter.h b/include/linux/filter.h
index 5771874bc01e..91b4c934f02e 100644
--- a/include/linux/filter.h
+++ b/include/linux/filter.h
@@ -548,6 +548,27 @@ static inline void bpf_compute_data_pointers(struct sk_buff *skb)
cb->data_end = skb->data + skb_headlen(skb);
}
+/* Similar to bpf_compute_data_pointers(), except that save orginal
+ * data in cb->data and cb->meta_data for restore.
+ */
+static inline void bpf_compute_and_save_data_end(
+ struct sk_buff *skb, void **saved_data_end)
+{
+ struct bpf_skb_data_end *cb = (struct bpf_skb_data_end *)skb->cb;
+
+ *saved_data_end = cb->data_end;
+ cb->data_end = skb->data + skb_headlen(skb);
+}
+
+/* Restore data saved by bpf_compute_data_pointers(). */
+static inline void bpf_restore_data_end(
+ struct sk_buff *skb, void *saved_data_end)
+{
+ struct bpf_skb_data_end *cb = (struct bpf_skb_data_end *)skb->cb;
+
+ cb->data_end = saved_data_end;
+}
+
static inline u8 *bpf_skb_cb(struct sk_buff *skb)
{
/* eBPF programs may read/write skb->cb[] area to transfer meta
diff --git a/kernel/bpf/cgroup.c b/kernel/bpf/cgroup.c
index 00f6ed2e4f9a..9425c2fb872f 100644
--- a/kernel/bpf/cgroup.c
+++ b/kernel/bpf/cgroup.c
@@ -553,6 +553,7 @@ int __cgroup_bpf_run_filter_skb(struct sock *sk,
{
unsigned int offset = skb->data - skb_network_header(skb);
struct sock *save_sk;
+ void *saved_data_end;
struct cgroup *cgrp;
int ret;
@@ -566,8 +567,13 @@ int __cgroup_bpf_run_filter_skb(struct sock *sk,
save_sk = skb->sk;
skb->sk = sk;
__skb_push(skb, offset);
+
+ /* compute pointers for the bpf prog */
+ bpf_compute_and_save_data_end(skb, &saved_data_end);
+
ret = BPF_PROG_RUN_ARRAY(cgrp->bpf.effective[type], skb,
bpf_prog_run_save_cb);
+ bpf_restore_data_end(skb, saved_data_end);
__skb_pull(skb, offset);
skb->sk = save_sk;
return ret == 1 ? 0 : -EPERM;
diff --git a/net/core/filter.c b/net/core/filter.c
index 1a3ac6c46873..e3ca30bd6840 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -5346,6 +5346,40 @@ static bool sk_filter_is_valid_access(int off, int size,
return bpf_skb_is_valid_access(off, size, type, prog, info);
}
+static bool cg_skb_is_valid_access(int off, int size,
+ enum bpf_access_type type,
+ const struct bpf_prog *prog,
+ struct bpf_insn_access_aux *info)
+{
+ switch (off) {
+ case bpf_ctx_range(struct __sk_buff, tc_classid):
+ case bpf_ctx_range(struct __sk_buff, data_meta):
+ case bpf_ctx_range(struct __sk_buff, flow_keys):
+ return false;
+ }
+ if (type == BPF_WRITE) {
+ switch (off) {
+ case bpf_ctx_range(struct __sk_buff, mark):
+ case bpf_ctx_range(struct __sk_buff, priority):
+ case bpf_ctx_range_till(struct __sk_buff, cb[0], cb[4]):
+ break;
+ default:
+ return false;
+ }
+ }
+
+ switch (off) {
+ case bpf_ctx_range(struct __sk_buff, data):
+ info->reg_type = PTR_TO_PACKET;
+ break;
+ case bpf_ctx_range(struct __sk_buff, data_end):
+ info->reg_type = PTR_TO_PACKET_END;
+ break;
+ }
+
+ return bpf_skb_is_valid_access(off, size, type, prog, info);
+}
+
static bool lwt_is_valid_access(int off, int size,
enum bpf_access_type type,
const struct bpf_prog *prog,
@@ -7038,7 +7072,7 @@ const struct bpf_prog_ops xdp_prog_ops = {
const struct bpf_verifier_ops cg_skb_verifier_ops = {
.get_func_proto = cg_skb_func_proto,
- .is_valid_access = sk_filter_is_valid_access,
+ .is_valid_access = cg_skb_is_valid_access,
.convert_ctx_access = bpf_convert_ctx_access,
};
--
2.17.1
^ permalink raw reply related [flat|nested] 4+ messages in thread
* [PATCH v7 bpf-next 2/2] bpf: add tests for direct packet access from CGROUP_SKB
2018-10-19 16:27 [PATCH v7 bpf-next 0/2] bpf: add cg_skb_is_valid_access Song Liu
2018-10-19 16:27 ` [PATCH v7 bpf-next 1/2] bpf: add cg_skb_is_valid_access for BPF_PROG_TYPE_CGROUP_SKB Song Liu
@ 2018-10-19 16:27 ` Song Liu
2018-10-19 16:38 ` Eric Dumazet
1 sibling, 1 reply; 4+ messages in thread
From: Song Liu @ 2018-10-19 16:27 UTC (permalink / raw)
To: netdev; +Cc: ast, daniel, kernel-team, edumazet, Song Liu
Tests are added to make sure CGROUP_SKB cannot access:
tc_classid, data_meta, flow_keys
and can read and write:
mark, prority, and cb[0-4]
and can read other fields.
To make selftest with skb->sk work, a dummy sk is added in
bpf_prog_test_run_skb().
Signed-off-by: Song Liu <songliubraving@fb.com>
---
net/bpf/test_run.c | 8 +
tools/testing/selftests/bpf/test_verifier.c | 171 ++++++++++++++++++++
2 files changed, 179 insertions(+)
diff --git a/net/bpf/test_run.c b/net/bpf/test_run.c
index 0c423b8cd75c..ae2ab89a9291 100644
--- a/net/bpf/test_run.c
+++ b/net/bpf/test_run.c
@@ -10,6 +10,8 @@
#include <linux/etherdevice.h>
#include <linux/filter.h>
#include <linux/sched/signal.h>
+#include <net/sock.h>
+#include <net/tcp.h>
static __always_inline u32 bpf_test_run_one(struct bpf_prog *prog, void *ctx,
struct bpf_cgroup_storage *storage[MAX_BPF_CGROUP_STORAGE_TYPE])
@@ -106,6 +108,8 @@ static void *bpf_test_init(const union bpf_attr *kattr, u32 size,
return data;
}
+static struct sock test_run_sk = {0};
+
int bpf_prog_test_run_skb(struct bpf_prog *prog, const union bpf_attr *kattr,
union bpf_attr __user *uattr)
{
@@ -137,11 +141,15 @@ int bpf_prog_test_run_skb(struct bpf_prog *prog, const union bpf_attr *kattr,
break;
}
+ sock_net_set(&test_run_sk, current->nsproxy->net_ns);
+ sock_init_data(NULL, &test_run_sk);
+
skb = build_skb(data, 0);
if (!skb) {
kfree(data);
return -ENOMEM;
}
+ skb->sk = &test_run_sk;
skb_reserve(skb, NET_SKB_PAD + NET_IP_ALIGN);
__skb_put(skb, size);
diff --git a/tools/testing/selftests/bpf/test_verifier.c b/tools/testing/selftests/bpf/test_verifier.c
index cf4cd32b6772..f1ae8d09770f 100644
--- a/tools/testing/selftests/bpf/test_verifier.c
+++ b/tools/testing/selftests/bpf/test_verifier.c
@@ -4862,6 +4862,177 @@ static struct bpf_test tests[] = {
.result = REJECT,
.flags = F_NEEDS_EFFICIENT_UNALIGNED_ACCESS,
},
+ {
+ "direct packet read test#1 for CGROUP_SKB",
+ .insns = {
+ BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_1,
+ offsetof(struct __sk_buff, data)),
+ BPF_LDX_MEM(BPF_W, BPF_REG_3, BPF_REG_1,
+ offsetof(struct __sk_buff, data_end)),
+ BPF_LDX_MEM(BPF_W, BPF_REG_4, BPF_REG_1,
+ offsetof(struct __sk_buff, len)),
+ BPF_LDX_MEM(BPF_W, BPF_REG_5, BPF_REG_1,
+ offsetof(struct __sk_buff, pkt_type)),
+ BPF_LDX_MEM(BPF_W, BPF_REG_6, BPF_REG_1,
+ offsetof(struct __sk_buff, mark)),
+ BPF_STX_MEM(BPF_W, BPF_REG_1, BPF_REG_6,
+ offsetof(struct __sk_buff, mark)),
+ BPF_LDX_MEM(BPF_W, BPF_REG_7, BPF_REG_1,
+ offsetof(struct __sk_buff, queue_mapping)),
+ BPF_LDX_MEM(BPF_W, BPF_REG_8, BPF_REG_1,
+ offsetof(struct __sk_buff, protocol)),
+ BPF_LDX_MEM(BPF_W, BPF_REG_9, BPF_REG_1,
+ offsetof(struct __sk_buff, vlan_present)),
+ BPF_MOV64_REG(BPF_REG_0, BPF_REG_2),
+ BPF_ALU64_IMM(BPF_ADD, BPF_REG_0, 8),
+ BPF_JMP_REG(BPF_JGT, BPF_REG_0, BPF_REG_3, 1),
+ BPF_LDX_MEM(BPF_B, BPF_REG_0, BPF_REG_2, 0),
+ BPF_MOV64_IMM(BPF_REG_0, 0),
+ BPF_EXIT_INSN(),
+ },
+ .result = ACCEPT,
+ .prog_type = BPF_PROG_TYPE_CGROUP_SKB,
+ },
+ {
+ "direct packet read test#2 for CGROUP_SKB",
+ .insns = {
+ BPF_LDX_MEM(BPF_W, BPF_REG_4, BPF_REG_1,
+ offsetof(struct __sk_buff, vlan_tci)),
+ BPF_LDX_MEM(BPF_W, BPF_REG_5, BPF_REG_1,
+ offsetof(struct __sk_buff, vlan_proto)),
+ BPF_LDX_MEM(BPF_W, BPF_REG_6, BPF_REG_1,
+ offsetof(struct __sk_buff, priority)),
+ BPF_STX_MEM(BPF_W, BPF_REG_1, BPF_REG_6,
+ offsetof(struct __sk_buff, priority)),
+ BPF_LDX_MEM(BPF_W, BPF_REG_7, BPF_REG_1,
+ offsetof(struct __sk_buff,
+ ingress_ifindex)),
+ BPF_LDX_MEM(BPF_W, BPF_REG_8, BPF_REG_1,
+ offsetof(struct __sk_buff, tc_index)),
+ BPF_LDX_MEM(BPF_W, BPF_REG_9, BPF_REG_1,
+ offsetof(struct __sk_buff, hash)),
+ BPF_MOV64_IMM(BPF_REG_0, 0),
+ BPF_EXIT_INSN(),
+ },
+ .result = ACCEPT,
+ .prog_type = BPF_PROG_TYPE_CGROUP_SKB,
+ },
+ {
+ "direct packet read test#3 for CGROUP_SKB",
+ .insns = {
+ BPF_LDX_MEM(BPF_W, BPF_REG_4, BPF_REG_1,
+ offsetof(struct __sk_buff, cb[0])),
+ BPF_LDX_MEM(BPF_W, BPF_REG_5, BPF_REG_1,
+ offsetof(struct __sk_buff, cb[1])),
+ BPF_LDX_MEM(BPF_W, BPF_REG_6, BPF_REG_1,
+ offsetof(struct __sk_buff, cb[2])),
+ BPF_LDX_MEM(BPF_W, BPF_REG_7, BPF_REG_1,
+ offsetof(struct __sk_buff, cb[3])),
+ BPF_LDX_MEM(BPF_W, BPF_REG_8, BPF_REG_1,
+ offsetof(struct __sk_buff, cb[4])),
+ BPF_LDX_MEM(BPF_W, BPF_REG_9, BPF_REG_1,
+ offsetof(struct __sk_buff, napi_id)),
+ BPF_STX_MEM(BPF_W, BPF_REG_1, BPF_REG_4,
+ offsetof(struct __sk_buff, cb[0])),
+ BPF_STX_MEM(BPF_W, BPF_REG_1, BPF_REG_5,
+ offsetof(struct __sk_buff, cb[1])),
+ BPF_STX_MEM(BPF_W, BPF_REG_1, BPF_REG_6,
+ offsetof(struct __sk_buff, cb[2])),
+ BPF_STX_MEM(BPF_W, BPF_REG_1, BPF_REG_7,
+ offsetof(struct __sk_buff, cb[3])),
+ BPF_STX_MEM(BPF_W, BPF_REG_1, BPF_REG_8,
+ offsetof(struct __sk_buff, cb[4])),
+ BPF_MOV64_IMM(BPF_REG_0, 0),
+ BPF_EXIT_INSN(),
+ },
+ .result = ACCEPT,
+ .prog_type = BPF_PROG_TYPE_CGROUP_SKB,
+ },
+ {
+ "direct packet read test#4 for CGROUP_SKB",
+ .insns = {
+ BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_1,
+ offsetof(struct __sk_buff, family)),
+ BPF_LDX_MEM(BPF_W, BPF_REG_3, BPF_REG_1,
+ offsetof(struct __sk_buff, remote_ip4)),
+ BPF_LDX_MEM(BPF_W, BPF_REG_4, BPF_REG_1,
+ offsetof(struct __sk_buff, local_ip4)),
+ BPF_LDX_MEM(BPF_W, BPF_REG_5, BPF_REG_1,
+ offsetof(struct __sk_buff, remote_ip6[0])),
+ BPF_LDX_MEM(BPF_W, BPF_REG_5, BPF_REG_1,
+ offsetof(struct __sk_buff, remote_ip6[1])),
+ BPF_LDX_MEM(BPF_W, BPF_REG_5, BPF_REG_1,
+ offsetof(struct __sk_buff, remote_ip6[2])),
+ BPF_LDX_MEM(BPF_W, BPF_REG_5, BPF_REG_1,
+ offsetof(struct __sk_buff, remote_ip6[3])),
+ BPF_LDX_MEM(BPF_W, BPF_REG_6, BPF_REG_1,
+ offsetof(struct __sk_buff, local_ip6[0])),
+ BPF_LDX_MEM(BPF_W, BPF_REG_6, BPF_REG_1,
+ offsetof(struct __sk_buff, local_ip6[1])),
+ BPF_LDX_MEM(BPF_W, BPF_REG_6, BPF_REG_1,
+ offsetof(struct __sk_buff, local_ip6[2])),
+ BPF_LDX_MEM(BPF_W, BPF_REG_6, BPF_REG_1,
+ offsetof(struct __sk_buff, local_ip6[3])),
+ BPF_LDX_MEM(BPF_W, BPF_REG_7, BPF_REG_1,
+ offsetof(struct __sk_buff, remote_port)),
+ BPF_LDX_MEM(BPF_W, BPF_REG_8, BPF_REG_1,
+ offsetof(struct __sk_buff, local_port)),
+ BPF_MOV64_IMM(BPF_REG_0, 0),
+ BPF_EXIT_INSN(),
+ },
+ .result = ACCEPT,
+ .prog_type = BPF_PROG_TYPE_CGROUP_SKB,
+ },
+ {
+ "invalid access of tc_classid for CGROUP_SKB",
+ .insns = {
+ BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_1,
+ offsetof(struct __sk_buff, tc_classid)),
+ BPF_MOV64_IMM(BPF_REG_0, 0),
+ BPF_EXIT_INSN(),
+ },
+ .result = REJECT,
+ .errstr = "invalid bpf_context access",
+ .prog_type = BPF_PROG_TYPE_CGROUP_SKB,
+ },
+ {
+ "invalid access of data_meta for CGROUP_SKB",
+ .insns = {
+ BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_1,
+ offsetof(struct __sk_buff, data_meta)),
+ BPF_MOV64_IMM(BPF_REG_0, 0),
+ BPF_EXIT_INSN(),
+ },
+ .result = REJECT,
+ .errstr = "invalid bpf_context access",
+ .prog_type = BPF_PROG_TYPE_CGROUP_SKB,
+ },
+ {
+ "invalid access of flow_keys for CGROUP_SKB",
+ .insns = {
+ BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_1,
+ offsetof(struct __sk_buff, flow_keys)),
+ BPF_MOV64_IMM(BPF_REG_0, 0),
+ BPF_EXIT_INSN(),
+ },
+ .result = REJECT,
+ .errstr = "invalid bpf_context access",
+ .prog_type = BPF_PROG_TYPE_CGROUP_SKB,
+ },
+ {
+ "invalid write access to napi_id for CGROUP_SKB",
+ .insns = {
+ BPF_LDX_MEM(BPF_W, BPF_REG_9, BPF_REG_1,
+ offsetof(struct __sk_buff, napi_id)),
+ BPF_STX_MEM(BPF_W, BPF_REG_1, BPF_REG_9,
+ offsetof(struct __sk_buff, napi_id)),
+ BPF_MOV64_IMM(BPF_REG_0, 0),
+ BPF_EXIT_INSN(),
+ },
+ .result = REJECT,
+ .errstr = "invalid bpf_context access",
+ .prog_type = BPF_PROG_TYPE_CGROUP_SKB,
+ },
{
"valid cgroup storage access",
.insns = {
--
2.17.1
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH v7 bpf-next 2/2] bpf: add tests for direct packet access from CGROUP_SKB
2018-10-19 16:27 ` [PATCH v7 bpf-next 2/2] bpf: add tests for direct packet access from CGROUP_SKB Song Liu
@ 2018-10-19 16:38 ` Eric Dumazet
0 siblings, 0 replies; 4+ messages in thread
From: Eric Dumazet @ 2018-10-19 16:38 UTC (permalink / raw)
To: Song Liu, netdev; +Cc: ast, daniel, kernel-team, edumazet
On 10/19/2018 09:27 AM, Song Liu wrote:
> Tests are added to make sure CGROUP_SKB cannot access:
> tc_classid, data_meta, flow_keys
>
> and can read and write:
> mark, prority, and cb[0-4]
>
> and can read other fields.
>
> To make selftest with skb->sk work, a dummy sk is added in
> bpf_prog_test_run_skb().
>
> Signed-off-by: Song Liu <songliubraving@fb.com>
> ---
> net/bpf/test_run.c | 8 +
> tools/testing/selftests/bpf/test_verifier.c | 171 ++++++++++++++++++++
> 2 files changed, 179 insertions(+)
>
> diff --git a/net/bpf/test_run.c b/net/bpf/test_run.c
> index 0c423b8cd75c..ae2ab89a9291 100644
> --- a/net/bpf/test_run.c
> +++ b/net/bpf/test_run.c
> @@ -10,6 +10,8 @@
> #include <linux/etherdevice.h>
> #include <linux/filter.h>
> #include <linux/sched/signal.h>
> +#include <net/sock.h>
> +#include <net/tcp.h>
>
> static __always_inline u32 bpf_test_run_one(struct bpf_prog *prog, void *ctx,
> struct bpf_cgroup_storage *storage[MAX_BPF_CGROUP_STORAGE_TYPE])
> @@ -106,6 +108,8 @@ static void *bpf_test_init(const union bpf_attr *kattr, u32 size,
> return data;
> }
>
> +static struct sock test_run_sk = {0};
No need for the {0} : bss is guaranteed to be zero.
> +
> int bpf_prog_test_run_skb(struct bpf_prog *prog, const union bpf_attr *kattr,
> union bpf_attr __user *uattr)
> {
> @@ -137,11 +141,15 @@ int bpf_prog_test_run_skb(struct bpf_prog *prog, const union bpf_attr *kattr,
> break;
> }
>
> + sock_net_set(&test_run_sk, current->nsproxy->net_ns);
> + sock_init_data(NULL, &test_run_sk);
> +
>
Can bpf_prog_test_run_skb() be used in parallel from different CPUS/threads ?
If yes, this looks racy, and I would suggest to use a kzalloc()ed socket just to be safe.
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2018-10-20 0:45 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2018-10-19 16:27 [PATCH v7 bpf-next 0/2] bpf: add cg_skb_is_valid_access Song Liu
2018-10-19 16:27 ` [PATCH v7 bpf-next 1/2] bpf: add cg_skb_is_valid_access for BPF_PROG_TYPE_CGROUP_SKB Song Liu
2018-10-19 16:27 ` [PATCH v7 bpf-next 2/2] bpf: add tests for direct packet access from CGROUP_SKB Song Liu
2018-10-19 16:38 ` Eric Dumazet
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