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/**
* BPF Simulator
*
* Copyright (c) 2012 Red Hat <pmoore@redhat.com>
* Author: Paul Moore <paul@paul-moore.com>
*/
/*
* This library is free software; you can redistribute it and/or modify it
* under the terms of version 2.1 of the GNU Lesser General Public License as
* published by the Free Software Foundation.
*
* This library is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
* for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this library; if not, see <http://www.gnu.org/licenses>.
*/
#include <elf.h>
#include <errno.h>
#include <fcntl.h>
#include <inttypes.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <linux/audit.h>
#include <sys/types.h>
#include <sys/stat.h>
#include "bpf.h"
#include "util.h"
#define BPF_PRG_MAX_LEN 4096
/**
* BPF simulator machine state
*/
struct sim_state {
uint32_t acc;
uint32_t temp[BPF_SCRATCH_SIZE];
};
struct bpf_program {
size_t i_cnt;
bpf_instr_raw *i;
};
static unsigned int opt_verbose = 0;
/**
* Print the usage information to stderr and exit
* @param program the name of the current program being invoked
*
* Print the usage information and exit with EINVAL.
*
*/
static void exit_usage(const char *program)
{
fprintf(stderr,
"usage: %s -f <bpf_file> [-v] [-h]"
" -a <arch> -s <syscall_num> [-0 <a0>] ... [-5 <a5>]\n",
program);
exit(EINVAL);
}
/**
* Handle a simulator fault
* @param rc the error or return code
*
* Print a "FAULT" to stderr to indicate a simulator fault, and an errno value
* if the simulator is running in verbose mode, then exit with EFAULT.
*
*/
static void exit_fault(unsigned int rc)
{
if (opt_verbose)
fprintf(stderr, "FAULT: errno = %d\n", rc);
else
fprintf(stderr, "FAULT\n");
exit(EFAULT);
}
/**
* Handle a BPF program error
* @param rc the error or return code
* @param line the line number
*
* Print an "ERROR" to stderr to indicate a program error, and an errno value
* if the simulator is running in verbose mode, then exit with ENOEXEC.
*
*/
static void exit_error(unsigned int rc, unsigned int line)
{
if (opt_verbose)
fprintf(stderr, "ERROR: errno = %d, line = %d\n", rc, line);
else
fprintf(stderr, "ERROR\n");
exit(ENOEXEC);
}
/**
* Handle a simulator return/action
* @param action the return value
* @param line the line number
*
* Display the action to stdout and exit with 0.
*
*/
static void end_action(uint32_t action, unsigned int line)
{
uint32_t act = action & SECCOMP_RET_ACTION_FULL;
uint32_t data = action & SECCOMP_RET_DATA;
switch (act) {
case SECCOMP_RET_KILL_PROCESS:
fprintf(stdout, "KILL_PROCESS\n");
break;
case SECCOMP_RET_KILL_THREAD:
fprintf(stdout, "KILL\n");
break;
case SECCOMP_RET_TRAP:
fprintf(stdout, "TRAP\n");
break;
case SECCOMP_RET_ERRNO:
fprintf(stdout, "ERRNO(%u)\n", data);
break;
case SECCOMP_RET_TRACE:
fprintf(stdout, "TRACE(%u)\n", data);
break;
case SECCOMP_RET_LOG:
fprintf(stdout, "LOG\n");
break;
case SECCOMP_RET_ALLOW:
fprintf(stdout, "ALLOW\n");
break;
default:
exit_error(EDOM, line);
}
exit(0);
}
/**
* Execute a BPF program
* @param prg the loaded BPF program
* @param sys_data the syscall record being tested
*
* Simulate the BPF program with the given syscall record.
*
*/
static void bpf_execute(const struct bpf_program *prg,
const struct seccomp_data *sys_data)
{
unsigned int ip, ip_c;
struct sim_state state;
bpf_instr_raw *bpf;
unsigned char *sys_data_b = (unsigned char *)sys_data;
uint16_t code;
uint8_t jt;
uint8_t jf;
uint32_t k;
/* initialize the machine state */
ip_c = 0;
ip = 0;
memset(&state, 0, sizeof(state));
while (ip < prg->i_cnt) {
/* get the instruction and bump the ip */
ip_c = ip;
bpf = &prg->i[ip++];
code = ttoh16(arch, bpf->code);
jt = bpf->jt;
jf = bpf->jf;
k = ttoh32(arch, bpf->k);
switch (code) {
case BPF_LD+BPF_W+BPF_ABS:
if (k < BPF_SYSCALL_MAX) {
uint32_t val = *((uint32_t *)&sys_data_b[k]);
state.acc = ttoh32(arch, val);
} else
exit_error(ERANGE, ip_c);
break;
case BPF_ALU+BPF_OR+BPF_K:
state.acc |= k;
break;
case BPF_ALU+BPF_AND+BPF_K:
state.acc &= k;
break;
case BPF_JMP+BPF_JA:
ip += k;
break;
case BPF_JMP+BPF_JEQ+BPF_K:
if (state.acc == k)
ip += jt;
else
ip += jf;
break;
case BPF_JMP+BPF_JGT+BPF_K:
if (state.acc > k)
ip += jt;
else
ip += jf;
break;
case BPF_JMP+BPF_JGE+BPF_K:
if (state.acc >= k)
ip += jt;
else
ip += jf;
break;
case BPF_RET+BPF_K:
end_action(k, ip_c);
break;
default:
/* since we don't support the full bpf language just
* yet, this could be either a fault or an error, we'll
* treat it as a fault until we provide full support */
exit_fault(EOPNOTSUPP);
}
}
/* if we've reached here there is a problem with the program */
exit_error(ERANGE, ip_c);
}
/**
* main
*/
int main(int argc, char *argv[])
{
int opt;
int iter;
char *opt_file = NULL;
FILE *file;
size_t file_read_len;
struct seccomp_data sys_data;
struct bpf_program bpf_prg;
/* initialize the syscall record */
memset(&sys_data, 0, sizeof(sys_data));
/* parse the command line */
while ((opt = getopt(argc, argv, "a:f:hs:v0:1:2:3:4:5:")) > 0) {
switch (opt) {
case 'a':
if (strcmp(optarg, "x86") == 0)
arch = AUDIT_ARCH_I386;
else if (strcmp(optarg, "x86_64") == 0)
arch = AUDIT_ARCH_X86_64;
else if (strcmp(optarg, "x32") == 0)
arch = AUDIT_ARCH_X86_64;
else if (strcmp(optarg, "arm") == 0)
arch = AUDIT_ARCH_ARM;
else if (strcmp(optarg, "aarch64") == 0)
arch = AUDIT_ARCH_AARCH64;
else if (strcmp(optarg, "mips") == 0)
arch = AUDIT_ARCH_MIPS;
else if (strcmp(optarg, "mipsel") == 0)
arch = AUDIT_ARCH_MIPSEL;
else if (strcmp(optarg, "mips64") == 0)
arch = AUDIT_ARCH_MIPS64;
else if (strcmp(optarg, "mipsel64") == 0)
arch = AUDIT_ARCH_MIPSEL64;
else if (strcmp(optarg, "mips64n32") == 0)
arch = AUDIT_ARCH_MIPS64N32;
else if (strcmp(optarg, "mipsel64n32") == 0)
arch = AUDIT_ARCH_MIPSEL64N32;
else if (strcmp(optarg, "parisc") == 0)
arch = AUDIT_ARCH_PARISC;
else if (strcmp(optarg, "parisc64") == 0)
arch = AUDIT_ARCH_PARISC64;
else if (strcmp(optarg, "ppc") == 0)
arch = AUDIT_ARCH_PPC;
else if (strcmp(optarg, "ppc64") == 0)
arch = AUDIT_ARCH_PPC64;
else if (strcmp(optarg, "ppc64le") == 0)
arch = AUDIT_ARCH_PPC64LE;
else if (strcmp(optarg, "s390") == 0)
arch = AUDIT_ARCH_S390;
else if (strcmp(optarg, "s390x") == 0)
arch = AUDIT_ARCH_S390X;
else if (strcmp(optarg, "riscv64") == 0)
arch = AUDIT_ARCH_RISCV64;
else
exit_fault(EINVAL);
break;
case 'f':
if (opt_file)
exit_fault(EINVAL);
opt_file = strdup(optarg);
if (opt_file == NULL)
exit_fault(ENOMEM);
break;
case 's':
sys_data.nr = strtol(optarg, NULL, 0);
break;
case 'v':
opt_verbose = 1;
break;
case '0':
sys_data.args[0] = strtoull(optarg, NULL, 0);
break;
case '1':
sys_data.args[1] = strtoull(optarg, NULL, 0);
break;
case '2':
sys_data.args[2] = strtoull(optarg, NULL, 0);
break;
case '3':
sys_data.args[3] = strtoull(optarg, NULL, 0);
break;
case '4':
sys_data.args[4] = strtoull(optarg, NULL, 0);
break;
case '5':
sys_data.args[5] = strtoull(optarg, NULL, 0);
break;
case 'h':
default:
/* usage information */
exit_usage(argv[0]);
}
}
/* adjust the endianess of sys_data to match the target */
sys_data.nr = htot32(arch, sys_data.nr);
sys_data.arch = htot32(arch, arch);
sys_data.instruction_pointer = htot64(arch,
sys_data.instruction_pointer);
for (iter = 0; iter < BPF_SYS_ARG_MAX; iter++)
sys_data.args[iter] = htot64(arch, sys_data.args[iter]);
/* allocate space for the bpf program */
/* XXX - we should make this dynamic */
bpf_prg.i_cnt = 0;
bpf_prg.i = calloc(BPF_PRG_MAX_LEN, sizeof(*bpf_prg.i));
if (bpf_prg.i == NULL)
exit_fault(ENOMEM);
/* load the bpf program */
if (opt_file == NULL)
exit_usage(argv[0]);
file = fopen(opt_file, "r");
if (file == NULL)
exit_fault(errno);
do {
file_read_len = fread(&(bpf_prg.i[bpf_prg.i_cnt]),
sizeof(*bpf_prg.i), 1, file);
if (file_read_len == 1)
bpf_prg.i_cnt++;
/* check the size */
if (bpf_prg.i_cnt == BPF_PRG_MAX_LEN)
exit_fault(E2BIG);
} while (file_read_len > 0);
fclose(file);
/* execute the bpf program */
bpf_execute(&bpf_prg, &sys_data);
/* we should never reach here */
exit_fault(EFAULT);
return 0;
}
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