Commit c2e39c6b authored by Florent Revest's avatar Florent Revest Committed by Alexei Starovoitov
Browse files

selftests/bpf: Add a series of tests for bpf_snprintf 



The "positive" part tests all format specifiers when things go well.

The "negative" part makes sure that incorrect format strings fail at
load time.

Signed-off-by: default avatarFlorent Revest <revest@chromium.org>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210419155243.1632274-7-revest@chromium.org
parent 58c2b1f5

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

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// SPDX-License-Identifier: GPL-2.0

/* Copyright (c) 2021 Google LLC. */



#include <test_progs.h>

#include "test_snprintf.skel.h"

#include "test_snprintf_single.skel.h"



#define EXP_NUM_OUT  "-8 9 96 -424242 1337 DABBAD00"

#define EXP_NUM_RET  sizeof(EXP_NUM_OUT)



#define EXP_IP_OUT   "127.000.000.001 0000:0000:0000:0000:0000:0000:0000:0001"

#define EXP_IP_RET   sizeof(EXP_IP_OUT)



/* The third specifier, %pB, depends on compiler inlining so don't check it */

#define EXP_SYM_OUT  "schedule schedule+0x0/"

#define MIN_SYM_RET  sizeof(EXP_SYM_OUT)



/* The third specifier, %p, is a hashed pointer which changes on every reboot */

#define EXP_ADDR_OUT "0000000000000000 ffff00000add4e55 "

#define EXP_ADDR_RET sizeof(EXP_ADDR_OUT "unknownhashedptr")



#define EXP_STR_OUT  "str1 longstr"

#define EXP_STR_RET  sizeof(EXP_STR_OUT)



#define EXP_OVER_OUT "%over"

#define EXP_OVER_RET 10



#define EXP_PAD_OUT "    4 000"

#define EXP_PAD_RET 900007



#define EXP_NO_ARG_OUT "simple case"

#define EXP_NO_ARG_RET 12



#define EXP_NO_BUF_RET 29



void test_snprintf_positive(void)

{

	char exp_addr_out[] = EXP_ADDR_OUT;

	char exp_sym_out[]  = EXP_SYM_OUT;

	struct test_snprintf *skel;



	skel = test_snprintf__open_and_load();

	if (!ASSERT_OK_PTR(skel, "skel_open"))

		return;



	if (!ASSERT_OK(test_snprintf__attach(skel), "skel_attach"))

		goto cleanup;



	/* trigger tracepoint */

	usleep(1);



	ASSERT_STREQ(skel->bss->num_out, EXP_NUM_OUT, "num_out");

	ASSERT_EQ(skel->bss->num_ret, EXP_NUM_RET, "num_ret");



	ASSERT_STREQ(skel->bss->ip_out, EXP_IP_OUT, "ip_out");

	ASSERT_EQ(skel->bss->ip_ret, EXP_IP_RET, "ip_ret");



	ASSERT_OK(memcmp(skel->bss->sym_out, exp_sym_out,

			 sizeof(exp_sym_out) - 1), "sym_out");

	ASSERT_LT(MIN_SYM_RET, skel->bss->sym_ret, "sym_ret");



	ASSERT_OK(memcmp(skel->bss->addr_out, exp_addr_out,

			 sizeof(exp_addr_out) - 1), "addr_out");

	ASSERT_EQ(skel->bss->addr_ret, EXP_ADDR_RET, "addr_ret");



	ASSERT_STREQ(skel->bss->str_out, EXP_STR_OUT, "str_out");

	ASSERT_EQ(skel->bss->str_ret, EXP_STR_RET, "str_ret");



	ASSERT_STREQ(skel->bss->over_out, EXP_OVER_OUT, "over_out");

	ASSERT_EQ(skel->bss->over_ret, EXP_OVER_RET, "over_ret");



	ASSERT_STREQ(skel->bss->pad_out, EXP_PAD_OUT, "pad_out");

	ASSERT_EQ(skel->bss->pad_ret, EXP_PAD_RET, "pad_ret");



	ASSERT_STREQ(skel->bss->noarg_out, EXP_NO_ARG_OUT, "no_arg_out");

	ASSERT_EQ(skel->bss->noarg_ret, EXP_NO_ARG_RET, "no_arg_ret");



	ASSERT_EQ(skel->bss->nobuf_ret, EXP_NO_BUF_RET, "no_buf_ret");



cleanup:

	test_snprintf__destroy(skel);

}



#define min(a, b) ((a) < (b) ? (a) : (b))



/* Loads an eBPF object calling bpf_snprintf with up to 10 characters of fmt */

static int load_single_snprintf(char *fmt)

{

	struct test_snprintf_single *skel;

	int ret;



	skel = test_snprintf_single__open();

	if (!skel)

		return -EINVAL;



	memcpy(skel->rodata->fmt, fmt, min(strlen(fmt) + 1, 10));



	ret = test_snprintf_single__load(skel);

	test_snprintf_single__destroy(skel);



	return ret;

}



void test_snprintf_negative(void)

{

	ASSERT_OK(load_single_snprintf("valid %d"), "valid usage");



	ASSERT_ERR(load_single_snprintf("0123456789"), "no terminating zero");

	ASSERT_ERR(load_single_snprintf("%d %d"), "too many specifiers");

	ASSERT_ERR(load_single_snprintf("%pi5"), "invalid specifier 1");

	ASSERT_ERR(load_single_snprintf("%a"), "invalid specifier 2");

	ASSERT_ERR(load_single_snprintf("%"), "invalid specifier 3");

	ASSERT_ERR(load_single_snprintf("%12345678"), "invalid specifier 4");

	ASSERT_ERR(load_single_snprintf("%--------"), "invalid specifier 5");

	ASSERT_ERR(load_single_snprintf("\x80"), "non ascii character");

	ASSERT_ERR(load_single_snprintf("\x1"), "non printable character");

}



void test_snprintf(void)

{

	if (test__start_subtest("snprintf_positive"))

		test_snprintf_positive();

	if (test__start_subtest("snprintf_negative"))

		test_snprintf_negative();

}

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

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// SPDX-License-Identifier: GPL-2.0

/* Copyright (c) 2021 Google LLC. */



#include <linux/bpf.h>

#include <bpf/bpf_helpers.h>

#include <bpf/bpf_tracing.h>



char num_out[64] = {};

long num_ret = 0;



char ip_out[64] = {};

long ip_ret = 0;



char sym_out[64] = {};

long sym_ret = 0;



char addr_out[64] = {};

long addr_ret = 0;



char str_out[64] = {};

long str_ret = 0;



char over_out[6] = {};

long over_ret = 0;



char pad_out[10] = {};

long pad_ret = 0;



char noarg_out[64] = {};

long noarg_ret = 0;



long nobuf_ret = 0;



extern const void schedule __ksym;



SEC("raw_tp/sys_enter")

int handler(const void *ctx)

{

	/* Convenient values to pretty-print */

	const __u8 ex_ipv4[] = {127, 0, 0, 1};

	const __u8 ex_ipv6[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1};

	static const char str1[] = "str1";

	static const char longstr[] = "longstr";



	/* Integer types */

	num_ret  = BPF_SNPRINTF(num_out, sizeof(num_out),

				"%d %u %x %li %llu %lX",

				-8, 9, 150, -424242, 1337, 0xDABBAD00);

	/* IP addresses */

	ip_ret   = BPF_SNPRINTF(ip_out, sizeof(ip_out), "%pi4 %pI6",

				&ex_ipv4, &ex_ipv6);

	/* Symbol lookup formatting */

	sym_ret  = BPF_SNPRINTF(sym_out,  sizeof(sym_out), "%ps %pS %pB",

				&schedule, &schedule, &schedule);

	/* Kernel pointers */

	addr_ret = BPF_SNPRINTF(addr_out, sizeof(addr_out), "%pK %px %p",

				0, 0xFFFF00000ADD4E55, 0xFFFF00000ADD4E55);

	/* Strings embedding */

	str_ret  = BPF_SNPRINTF(str_out, sizeof(str_out), "%s %+05s",

				str1, longstr);

	/* Overflow */

	over_ret = BPF_SNPRINTF(over_out, sizeof(over_out), "%%overflow");

	/* Padding of fixed width numbers */

	pad_ret = BPF_SNPRINTF(pad_out, sizeof(pad_out), "%5d %0900000X", 4, 4);

	/* No args */

	noarg_ret = BPF_SNPRINTF(noarg_out, sizeof(noarg_out), "simple case");

	/* No buffer */

	nobuf_ret = BPF_SNPRINTF(NULL, 0, "only interested in length %d", 60);



	return 0;

}



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

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

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// SPDX-License-Identifier: GPL-2.0

/* Copyright (c) 2021 Google LLC. */



#include <linux/bpf.h>

#include <bpf/bpf_helpers.h>



/* The format string is filled from the userspace such that loading fails */

static const char fmt[10];



SEC("raw_tp/sys_enter")

int handler(const void *ctx)

{

	unsigned long long arg = 42;



	bpf_snprintf(NULL, 0, fmt, &arg, sizeof(arg));



	return 0;

}



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