selftests/bpf: add a test for verifier logs

LDLIBS += -lcap -lelf

TEST_GEN_PROGS = test_verifier test_tag test_maps test_lru_map test_lpm_map test_progs \

	test_align

	test_align test_verifier_log

TEST_GEN_FILES = test_pkt_access.o test_xdp.o test_l4lb.o test_tcp_estats.o test_obj_id.o \

	test_pkt_md_access.o test_xdp_redirect.o test_xdp_meta.o sockmap_parse_prog.o     \

#include <errno.h>

#include <stdlib.h>

#include <stdio.h>

#include <string.h>

#include <unistd.h>

#include <linux/bpf.h>

#include <linux/filter.h>

#include <linux/unistd.h>

#include <bpf/bpf.h>

#define LOG_SIZE (1 << 20)

#define err(str...)	printf("ERROR: " str)

static const struct bpf_insn code_sample[] = {

	/* We need a few instructions to pass the min log length */

	BPF_MOV64_IMM(BPF_REG_0, 0),

	BPF_MOV64_IMM(BPF_REG_0, 0),

	BPF_MOV64_IMM(BPF_REG_0, 0),

	BPF_MOV64_IMM(BPF_REG_0, 0),

	BPF_MOV64_IMM(BPF_REG_0, 0),

	BPF_MOV64_IMM(BPF_REG_0, 0),

	BPF_MOV64_IMM(BPF_REG_0, 0),

	BPF_MOV64_IMM(BPF_REG_0, 0),

	BPF_MOV64_IMM(BPF_REG_0, 0),

	BPF_MOV64_IMM(BPF_REG_0, 0),

	BPF_MOV64_IMM(BPF_REG_0, 0),

	BPF_MOV64_IMM(BPF_REG_0, 0),

	BPF_MOV64_IMM(BPF_REG_0, 0),

	BPF_MOV64_IMM(BPF_REG_0, 0),

	BPF_MOV64_IMM(BPF_REG_0, 0),

	BPF_MOV64_IMM(BPF_REG_0, 0),

	BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0,

		     BPF_FUNC_map_lookup_elem),

	BPF_EXIT_INSN(),

};

static inline __u64 ptr_to_u64(const void *ptr)

{

	return (__u64) (unsigned long) ptr;

}

static int load(char *log, size_t log_len, int log_level)

{

	union bpf_attr attr;

	bzero(&attr, sizeof(attr));

	attr.prog_type = BPF_PROG_TYPE_SOCKET_FILTER;

	attr.insn_cnt = (__u32)(sizeof(code_sample) / sizeof(struct bpf_insn));

	attr.insns = ptr_to_u64(code_sample);

	attr.license = ptr_to_u64("GPL");

	attr.log_buf = ptr_to_u64(log);

	attr.log_size = log_len;

	attr.log_level = log_level;

	return syscall(__NR_bpf, BPF_PROG_LOAD, &attr, sizeof(attr));

}

static void check_ret(int ret, int exp_errno)

{

	if (ret > 0) {

		close(ret);

		err("broken sample loaded successfully!?\n");

		exit(1);

	}

	if (!ret || errno != exp_errno) {

		err("Program load returned: ret:%d/errno:%d, expected ret:%d/errno:%d\n",

		    ret, errno, -1, exp_errno);

		exit(1);

	}

}

static void check_ones(const char *buf, size_t len, const char *msg)

{

	while (len--)

		if (buf[len] != 1) {

			err("%s", msg);

			exit(1);

		}

}

static void test_log_good(char *log, size_t buf_len, size_t log_len,

			  size_t exp_len, int exp_errno, const char *full_log)

{

	size_t len;

	int ret;

	memset(log, 1, buf_len);

	ret = load(log, log_len, 1);

	check_ret(ret, exp_errno);

	len = strnlen(log, buf_len);

	if (len == buf_len) {

		err("verifier did not NULL terminate the log\n");

		exit(1);

	}

	if (exp_len && len != exp_len) {

		err("incorrect log length expected:%zd have:%zd\n",

		    exp_len, len);

		exit(1);

	}

	if (strchr(log, 1)) {

		err("verifier leaked a byte through\n");

		exit(1);

	}

	check_ones(log + len + 1, buf_len - len - 1,

		   "verifier wrote bytes past NULL termination\n");

	if (memcmp(full_log, log, LOG_SIZE)) {

		err("log did not match expected output\n");

		exit(1);

	}

}

static void test_log_bad(char *log, size_t log_len, int log_level)

{

	int ret;

	ret = load(log, log_len, log_level);

	check_ret(ret, EINVAL);

	if (log)

		check_ones(log, LOG_SIZE,

			   "verifier touched log with bad parameters\n");

}

int main(int argc, char **argv)

{

	char full_log[LOG_SIZE];

	char log[LOG_SIZE];

	size_t want_len;

	int i;

	memset(log, 1, LOG_SIZE);

	/* Test incorrect attr */

	printf("Test log_level 0...\n");

	test_log_bad(log, LOG_SIZE, 0);

	printf("Test log_size < 128...\n");

	test_log_bad(log, 15, 1);

	printf("Test log_buff = NULL...\n");

	test_log_bad(NULL, LOG_SIZE, 1);

	/* Test with log big enough */

	printf("Test oversized buffer...\n");

	test_log_good(full_log, LOG_SIZE, LOG_SIZE, 0, EACCES, full_log);

	want_len = strlen(full_log);

	printf("Test exact buffer...\n");

	test_log_good(log, LOG_SIZE, want_len + 2, want_len, EACCES, full_log);

	printf("Test undersized buffers...\n");

	for (i = 0; i < 64; i++) {

		full_log[want_len - i + 1] = 1;

		full_log[want_len - i] = 0;

		test_log_good(log, LOG_SIZE, want_len + 1 - i, want_len - i,

			      ENOSPC, full_log);

	}

	printf("test_verifier_log: OK\n");

	return 0;

}