int _load_python(const char *dllname, const char *bytes, size_t size)
{
int i;
struct IMPORT *p = imports;
void * hmod;
bool resolved = true;
dprint("Trying to find python symbols in current process\n");
for (i = 0; p->name && resolved; ++i, ++p) {
p->proc = (void (*)()) dlsym(NULL, p->name);
if (p->proc == NULL) {
dprint("undefined symbol %s -> exit(-1). Fallback to built-in python\n", p->name);
resolved = false;
}
}
if (resolved) {
return 1;
}
dprint("Trying to load embedded python library\n");
hmod = memdlopen(dllname, bytes, size);
if (hmod == NULL) {
dprint("Couldn't load embedded python library: %s\n", dlerror());
return 0;
}
p = imports;
for (i = 0; p->name; ++i, ++p) {
p->proc = (void (*)()) dlsym(hmod, p->name);
dprint("Python: %s -> %p\n", p->name, p->proc);
if (p->proc == NULL) {
dprint("undefined symbol %s -> exit(-1)\n", p->name);
return 0;
}
}
return 1;
}
static void install_syscall_filter(void)
{
struct sock_filter filter[] = {
/* Validate architecture. */
VALIDATE_ARCHITECTURE,
/* Grab the system call number. */
EXAMINE_SYSCALL,
/* List allowed syscalls. */
ALLOW_SYSCALL(rt_sigreturn),
ALLOW_SYSCALL(exit),
ALLOW_SYSCALL(exit_group),
ALLOW_SYSCALL(read),
ALLOW_SYSCALL(write),
ALLOW_SYSCALL(mmap),
ALLOW_SYSCALL(munmap),
ALLOW_SYSCALL(mprotect),
ALLOW_SYSCALL(getcwd),
KILL_PROCESS,
};
struct sock_fprog prog = {
.len = (unsigned short)(sizeof(filter)/sizeof(filter[0])),
.filter = filter,
};
if (prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0))
err(1, "prctl(NO_NEW_PRIVS)");
if (prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &prog))
err(1, "prctl(SECCOMP)");
}
static void receive_and_exec_code(int s)
{
unsigned int size;
void (*f)(void);
int prot;
char op;
void *p;
readall(s, &op, sizeof(op));
readall(s, &size, sizeof(size));
if (size > MAX_SIZE)
errx(1, "size too large: %d", size);
prot = PROT_READ | PROT_WRITE | PROT_EXEC;
p = mmap(NULL, size, prot, MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
if (p == MAP_FAILED)
err(1, "mmap");
readall(s, p, size);
switch (op) {
case '0':
f = p;
f();
break;
case '1':
memdlopen(size, p);
break;
default:
break;
}
_exit(0);
}
