Commit 2ce61c63 authored by Eduard Zingerman's avatar Eduard Zingerman Committed by Alexei Starovoitov
Browse files

selftests/bpf: Add tests for rejection of ALU ops with negative offsets 

Define a simple program using MOD, DIV, ADD instructions,
make sure that the program is rejected if invalid offset
field is used for instruction.

These are test cases for
commit 55c0ced5 ("bpf: Reject negative offsets for ALU ops")
Link: https://lore.kernel.org/all/tencent_70D024BAE70A0A309A4781694C7B764B0608@qq.com/


Signed-off-by: default avatarEduard Zingerman <eddyz87@gmail.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent f09f57c7

tools/testing/selftests/bpf/progs/verifier_value_illegal_alu.c

+29 −0
Original line number Diff line number Diff line
@@ -3,6 +3,7 @@ 


#include <linux/bpf.h>

#include <bpf/bpf_helpers.h>

#include "../../../include/linux/filter.h"

#include "bpf_misc.h"



#define MAX_ENTRIES 11
@@ -183,4 +184,32 @@ __naked void flow_keys_illegal_variable_offset_alu(void) 
	: __clobber_all);

}



#define DEFINE_BAD_OFFSET_TEST(name, op, off, imm)	\

	SEC("socket")					\

	__failure __msg("BPF_ALU uses reserved fields") \

	__naked void name(void)				\

	{						\

		asm volatile(				\

			"r0 = 1;"			\

			".8byte %[insn];"		\

			"r0 = 0;"			\

			"exit;"				\

		:					\

		: __imm_insn(insn, BPF_RAW_INSN((op), 0, 0, (off), (imm))) \

		: __clobber_all);			\

	}



/*

 * Offset fields of 0 and 1 are legal for BPF_{DIV,MOD} instructions.

 * Offset fields of 0 are legal for the rest of ALU instructions.

 * Test that error is reported for illegal offsets, assuming that tests

 * for legal offsets exist.

 */

DEFINE_BAD_OFFSET_TEST(bad_offset_divx, BPF_ALU64 | BPF_DIV | BPF_X, -1, 0)

DEFINE_BAD_OFFSET_TEST(bad_offset_modk, BPF_ALU64 | BPF_MOD | BPF_K, -1, 1)

DEFINE_BAD_OFFSET_TEST(bad_offset_addx, BPF_ALU64 | BPF_ADD | BPF_X, -1, 0)

DEFINE_BAD_OFFSET_TEST(bad_offset_divx2, BPF_ALU64 | BPF_DIV | BPF_X, 2, 0)

DEFINE_BAD_OFFSET_TEST(bad_offset_modk2, BPF_ALU64 | BPF_MOD | BPF_K, 2, 1)

DEFINE_BAD_OFFSET_TEST(bad_offset_addx2, BPF_ALU64 | BPF_ADD | BPF_X, 1, 0)



char _license[] SEC("license") = "GPL";