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bpf: add tests for direct packet access from CGROUP_SKB
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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>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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@liu-song-6
liu-song-6 authored and Alexei Starovoitov committed Oct 19, 2018
1 parent b39b5f4 commit 2cb494a
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15 changes: 15 additions & 0 deletions net/bpf/test_run.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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])
Expand Down Expand Up @@ -115,6 +117,7 @@ int bpf_prog_test_run_skb(struct bpf_prog *prog, const union bpf_attr *kattr,
u32 retval, duration;
int hh_len = ETH_HLEN;
struct sk_buff *skb;
struct sock *sk;
void *data;
int ret;

Expand All @@ -137,11 +140,21 @@ int bpf_prog_test_run_skb(struct bpf_prog *prog, const union bpf_attr *kattr,
break;
}

sk = kzalloc(sizeof(struct sock), GFP_USER);
if (!sk) {
kfree(data);
return -ENOMEM;
}
sock_net_set(sk, current->nsproxy->net_ns);
sock_init_data(NULL, sk);

skb = build_skb(data, 0);
if (!skb) {
kfree(data);
kfree(sk);
return -ENOMEM;
}
skb->sk = sk;

skb_reserve(skb, NET_SKB_PAD + NET_IP_ALIGN);
__skb_put(skb, size);
Expand All @@ -159,6 +172,7 @@ int bpf_prog_test_run_skb(struct bpf_prog *prog, const union bpf_attr *kattr,

if (pskb_expand_head(skb, nhead, 0, GFP_USER)) {
kfree_skb(skb);
kfree(sk);
return -ENOMEM;
}
}
Expand All @@ -171,6 +185,7 @@ int bpf_prog_test_run_skb(struct bpf_prog *prog, const union bpf_attr *kattr,
size = skb_headlen(skb);
ret = bpf_test_finish(kattr, uattr, skb->data, size, retval, duration);
kfree_skb(skb);
kfree(sk);
return ret;
}

Expand Down
171 changes: 171 additions & 0 deletions tools/testing/selftests/bpf/test_verifier.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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 = {
Expand Down

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