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#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;
}
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