Commit 0869e507 authored by Alexei Starovoitov's avatar Alexei Starovoitov Committed by Andrii Nakryiko
Browse files

selftests/bpf: Add a testcase for 64-bit bounds propagation issue. 



./test_progs-no_alu32 -vv -t twfw

Before the 64-bit_into_32-bit fix:
19: (25) if r1 > 0x3f goto pc+6
 R1_w=inv(id=0,umax_value=63,var_off=(0x0; 0xff),s32_max_value=255,u32_max_value=255)

and eventually:

invalid access to map value, value_size=8 off=7 size=8
R6 max value is outside of the allowed memory range
libbpf: failed to load object 'no_alu32/twfw.o'

After the fix:
19: (25) if r1 > 0x3f goto pc+6
 R1_w=inv(id=0,umax_value=63,var_off=(0x0; 0x3f))

verif_twfw:OK

Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Acked-by: default avatarYonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20211101222153.78759-3-alexei.starovoitov@gmail.com
parent 388e2c0b

tools/testing/selftests/bpf/prog_tests/bpf_verif_scale.c

+5 −0
Original line number Diff line number Diff line
@@ -202,3 +202,8 @@ void test_verif_scale_seg6_loop() 
{

	scale_test("test_seg6_loop.o", BPF_PROG_TYPE_LWT_SEG6LOCAL, false);

}



void test_verif_twfw()

{

	scale_test("twfw.o", BPF_PROG_TYPE_CGROUP_SKB, false);

}

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

0 → 100644
+58 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0

/* Copyright (c) 2021 Facebook */

#include <linux/types.h>

#include <bpf/bpf_helpers.h>

#include <linux/bpf.h>

#include <stdint.h>



#define TWFW_MAX_TIERS (64)

/*

 * load is successful

 * #define TWFW_MAX_TIERS (64u)$

 */



struct twfw_tier_value {

	unsigned long mask[1];

};



struct rule {

	uint8_t seqnum;

};



struct rules_map {

	__uint(type, BPF_MAP_TYPE_ARRAY);

	__type(key, __u32);

	__type(value, struct rule);

	__uint(max_entries, 1);

};



struct tiers_map {

	__uint(type, BPF_MAP_TYPE_ARRAY);

	__type(key, __u32);

	__type(value, struct twfw_tier_value);

	__uint(max_entries, 1);

};



struct rules_map rules SEC(".maps");

struct tiers_map tiers SEC(".maps");



SEC("cgroup_skb/ingress")

int twfw_verifier(struct __sk_buff* skb)

{

	const uint32_t key = 0;

	const struct twfw_tier_value* tier = bpf_map_lookup_elem(&tiers, &key);

	if (!tier)

		return 1;



	struct rule* rule = bpf_map_lookup_elem(&rules, &key);

	if (!rule)

		return 1;



	if (rule && rule->seqnum < TWFW_MAX_TIERS) {

		/* rule->seqnum / 64 should always be 0 */

		unsigned long mask = tier->mask[rule->seqnum / 64];

		if (mask)

			return 0;

	}

	return 1;

}