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bpf: add test case for ld_abs and helper changing pkt data

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Add a test that i) uses LD_ABS, ii) zeroing R6 before call, iii) calls
a helper that triggers reload of cached skb data, iv) uses LD_ABS again.
It's added for test_bpf in order to do runtime testing after JITing as
well as test_verifier to test that the sequence is allowed.

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Daniel Borkmann 2017-12-14 21:07:27 +01:00 committed by Alexei Starovoitov
parent 07aee94394
commit 87ab819430
2 changed files with 67 additions and 0 deletions
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43
lib/test_bpf.c
View File

@ -435,6 +435,41 @@ loop:
return 0;
}
static int bpf_fill_ld_abs_vlan_push_pop2(struct bpf_test *self)
{
struct bpf_insn *insn;
insn = kmalloc_array(16, sizeof(*insn), GFP_KERNEL);
if (!insn)
return -ENOMEM;
/* Due to func address being non-const, we need to
* assemble this here.
*/
insn[0] = BPF_MOV64_REG(R6, R1);
insn[1] = BPF_LD_ABS(BPF_B, 0);
insn[2] = BPF_LD_ABS(BPF_H, 0);
insn[3] = BPF_LD_ABS(BPF_W, 0);
insn[4] = BPF_MOV64_REG(R7, R6);
insn[5] = BPF_MOV64_IMM(R6, 0);
insn[6] = BPF_MOV64_REG(R1, R7);
insn[7] = BPF_MOV64_IMM(R2, 1);
insn[8] = BPF_MOV64_IMM(R3, 2);
insn[9] = BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0,
bpf_skb_vlan_push_proto.func - __bpf_call_base);
insn[10] = BPF_MOV64_REG(R6, R7);
insn[11] = BPF_LD_ABS(BPF_B, 0);
insn[12] = BPF_LD_ABS(BPF_H, 0);
insn[13] = BPF_LD_ABS(BPF_W, 0);
insn[14] = BPF_MOV64_IMM(R0, 42);
insn[15] = BPF_EXIT_INSN();
self->u.ptr.insns = insn;
self->u.ptr.len = 16;
return 0;
}
static int bpf_fill_jump_around_ld_abs(struct bpf_test *self)
{
unsigned int len = BPF_MAXINSNS;
@ -6066,6 +6101,14 @@ static struct bpf_test tests[] = {
{},
{ {0x1, 0x42 } },
},
{
"LD_ABS with helper changing skb data",
{ },
INTERNAL,
{ 0x34 },
{ { ETH_HLEN, 42 } },
.fill_helper = bpf_fill_ld_abs_vlan_push_pop2,
},
};
static struct net_device dev;

24
tools/testing/selftests/bpf/test_verifier.c
View File

@ -6116,6 +6116,30 @@ static struct bpf_test tests[] = {
},
.result = ACCEPT,
},
{
"ld_abs: tests on r6 and skb data reload helper",
.insns = {
BPF_MOV64_REG(BPF_REG_6, BPF_REG_1),
BPF_LD_ABS(BPF_B, 0),
BPF_LD_ABS(BPF_H, 0),
BPF_LD_ABS(BPF_W, 0),
BPF_MOV64_REG(BPF_REG_7, BPF_REG_6),
BPF_MOV64_IMM(BPF_REG_6, 0),
BPF_MOV64_REG(BPF_REG_1, BPF_REG_7),
BPF_MOV64_IMM(BPF_REG_2, 1),
BPF_MOV64_IMM(BPF_REG_3, 2),
BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0,
BPF_FUNC_skb_vlan_push),
BPF_MOV64_REG(BPF_REG_6, BPF_REG_7),
BPF_LD_ABS(BPF_B, 0),
BPF_LD_ABS(BPF_H, 0),
BPF_LD_ABS(BPF_W, 0),
BPF_MOV64_IMM(BPF_REG_0, 42),
BPF_EXIT_INSN(),
},
.prog_type = BPF_PROG_TYPE_SCHED_CLS,
.result = ACCEPT,
},
{
"ld_ind: check calling conv, r1",
.insns = {