Commit 87ab8194 authored by Daniel Borkmann's avatar Daniel Borkmann Committed by Alexei Starovoitov
Browse files

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



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: default avatarDaniel Borkmann <daniel@iogearbox.net>
Acked-by: default avatarAlexei Starovoitov <ast@kernel.org>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent 07aee943

lib/test_bpf.c

+43 −0
Original line number Diff line number Diff line
@@ -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;

tools/testing/selftests/bpf/test_verifier.c

+24 −0
Original line number Diff line number Diff line
@@ -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 = {

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