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/*
* Copyright (C) 2015 John Crispin <blogic@openwrt.org>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License version 2.1
* as published by the Free Software Foundation
*
* This program 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 General Public License for more details.
*/
#define _GNU_SOURCE
#include <stddef.h>
#include <sys/ptrace.h>
#include <sys/types.h>
#include <sys/user.h>
#include <sys/wait.h>
#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include <string.h>
#include <syslog.h>
#include <libubox/uloop.h>
#include <libubox/blobmsg.h>
#include <libubox/blobmsg_json.h>
#include "../syscall-names.h"
#define _offsetof(a, b) __builtin_offsetof(a,b)
#define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]))
#ifdef __amd64__
#define reg_syscall_nr _offsetof(struct user, regs.orig_rax)
#elif defined(__i386__)
#define reg_syscall_nr _offsetof(struct user, regs.orig_eax)
#elif defined(__mips)
# ifndef EF_REG2
# define EF_REG2 8
# endif
#define reg_syscall_nr (EF_REG2 / 4)
#else
#error tracing is not supported on this architecture
#endif
#define INFO(fmt, ...) do { \
fprintf(stderr, "utrace: "fmt, ## __VA_ARGS__); \
} while (0)
#define ERROR(fmt, ...) do { \
syslog(0, "utrace: "fmt, ## __VA_ARGS__); \
fprintf(stderr, "utrace: "fmt, ## __VA_ARGS__); \
} while (0)
static struct uloop_process tracer;
static int *syscall_count;
static struct blob_buf b;
static int syscall_max;
static int in_syscall;
static int debug;
static int max_syscall = ARRAY_SIZE(syscall_names);
static void set_syscall(const char *name, int val)
{
int i;
for (i = 0; i < max_syscall; i++)
if (syscall_names[i] && !strcmp(syscall_names[i], name)) {
syscall_count[i] = val;
return;
}
}
static void print_syscalls(int policy, const char *json)
{
void *c;
int i;
set_syscall("rt_sigaction", 1);
set_syscall("sigreturn", 1);
set_syscall("rt_sigreturn", 1);
set_syscall("exit_group", 1);
set_syscall("exit", 1);
blob_buf_init(&b, 0);
c = blobmsg_open_array(&b, "whitelist");
for (i = 0; i < ARRAY_SIZE(syscall_names); i++) {
if (!syscall_count[i])
continue;
if (syscall_names[i]) {
if (debug)
printf("syscall %d (%s) was called %d times\n",
i, syscall_names[i], syscall_count[i]);
blobmsg_add_string(&b, NULL, syscall_names[i]);
} else {
ERROR("no name found for syscall(%d)\n", i);
}
}
blobmsg_close_array(&b, c);
blobmsg_add_u32(&b, "policy", policy);
if (json) {
FILE *fp = fopen(json, "w");
if (fp) {
fprintf(fp, "%s", blobmsg_format_json_indent(b.head, true, 0));
fclose(fp);
INFO("saving syscall trace to %s\n", json);
} else {
ERROR("failed to open %s\n", json);
}
} else {
printf("%s\n",
blobmsg_format_json_indent(b.head, true, 0));
}
}
static void tracer_cb(struct uloop_process *c, int ret)
{
if (WIFSTOPPED(ret) && WSTOPSIG(ret) & 0x80) {
if (!in_syscall) {
int syscall = ptrace(PTRACE_PEEKUSER, c->pid, reg_syscall_nr);
if (syscall < syscall_max) {
syscall_count[syscall]++;
if (debug)
fprintf(stderr, "%s()\n", syscall_names[syscall]);
} else if (debug) {
fprintf(stderr, "syscal(%d)\n", syscall);
}
}
in_syscall = !in_syscall;
} else if (WIFEXITED(ret)) {
uloop_end();
return;
}
ptrace(PTRACE_SYSCALL, c->pid, 0, 0);
uloop_process_add(&tracer);
}
int main(int argc, char **argv, char **envp)
{
char *json = NULL;
int status, ch, policy = EPERM;
pid_t child;
while ((ch = getopt(argc, argv, "f:p:")) != -1) {
switch (ch) {
case 'f':
json = optarg;
break;
case 'p':
policy = atoi(optarg);
break;
}
}
argc -= optind;
argv += optind;
if (!argc)
return -1;
if (getenv("TRACE_DEBUG"))
debug = 1;
unsetenv("TRACE_DEBUG");
child = fork();
if (child == 0) {
char **_argv = calloc(argc + 1, sizeof(char *));
char **_envp;
char preload[] = "LD_PRELOAD=/lib/libpreload-trace.so";
int envc = 1;
int ret;
memcpy(_argv, argv, argc * sizeof(char *));
while (envp[envc++])
;
_envp = calloc(envc, sizeof(char *));
memcpy(&_envp[1], _envp, envc * sizeof(char *));
*envp = preload;
ret = execve(_argv[0], _argv, envp);
ERROR("failed to exec %s: %s\n", _argv[0], strerror(errno));
return ret;
}
if (child < 0)
return -1;
syscall_max = ARRAY_SIZE(syscall_names);
syscall_count = calloc(syscall_max, sizeof(int));
waitpid(child, &status, 0);
if (!WIFSTOPPED(status)) {
ERROR("failed to start %s\n", *argv);
return -1;
}
ptrace(PTRACE_SETOPTIONS, child, 0, PTRACE_O_TRACESYSGOOD);
ptrace(PTRACE_SYSCALL, child, 0, 0);
uloop_init();
tracer.pid = child;
tracer.cb = tracer_cb;
uloop_process_add(&tracer);
uloop_run();
uloop_done();
if (!json)
if (asprintf(&json, "/tmp/%s.%u.json", basename(*argv), child) < 0)
ERROR("failed to allocate output path: %s\n", strerror(errno));
print_syscalls(policy, json);
return 0;
}
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