/* Find and execute hook. */
int tracy_execute_hook(struct tracy *t, char *syscall, struct tracy_event *e) {
struct tracy_ll_item *item;
int hash;
union {
void *pvoid;
tracy_hook_func pfunc;
} _hax;
if (TRACY_PRINT_SYSCALLS(t))
printf(_y("%04d System call: %s (%ld) Pre: %d")"\n",
e->child->pid, get_syscall_name_abi(e->syscall_num, e->abi),
e->syscall_num, e->child->pre_syscall);
hash = hash_syscall(syscall, e->abi);
item = ll_find(t->hooks, hash);
if (item) {
/* printf("Executing hook for: %s\n", syscall); */
/* ANSI C has some disadvantages too ... */
_hax.pvoid = item->data;
return _hax.pfunc(e);
}
if (t->defhook)
return t->defhook(e);
return TRACY_HOOK_NOHOOK;
}
static int redirect_file_access(struct tracy_event *e, int argpos,
bool resolve_symlinks)
{
struct tracy_sc_args a;
int rc = TRACY_HOOK_CONTINUE;
char *path = NULL;
tracy_child_addr_t devname_new = NULL;
struct fstab_rec *fstabrec;
long *argptr;
struct multiboot_child_data *mbc = e->child->custom;
// call hook_open
if (e->syscall_num == get_syscall_number_abi("open", e->abi)
|| e->syscall_num == get_syscall_number_abi("openat", e->abi)) {
int rc_open = hook_open(e, argpos, resolve_symlinks);
if (rc_open)
return rc_open;
}
if (e->child->pre_syscall) {
// get path
argptr = &e->args.a0;
path = get_patharg(e->child, argptr[argpos], resolve_symlinks);
if (!path) {
rc = TRACY_HOOK_ABORT;
goto out;
}
// check if we need to redirect this file
fstabrec = get_fstab_rec(path);
if (!fstabrec) {
goto out;
}
// ignore symlinks for calls which don't resolve them
struct stat sb;
if (!resolve_symlinks && !lstat(path, &sb)
&& S_ISLNK(sb.st_mode)) {
goto out;
}
char *replacement =
fstabrec->replacement_bind ? fstabrec->
stub_device : fstabrec->replacement_device;
DEBUG("%s(%s): redirect %s->%s arg=%d\n", __func__,
get_syscall_name_abi(e->syscall_num, e->abi), path,
replacement, argpos);
// copy new devname
devname_new = copy_patharg(e->child, replacement);
if (!devname_new) {
kperror("copy_patharg");
rc = TRACY_HOOK_ABORT;
goto out;
}
// copy args
memcpy(&a, &(e->args), sizeof(struct tracy_sc_args));
// modify args
argptr = &a.a0;
argptr[argpos] = (long)devname_new;
// write new args
if (tracy_modify_syscall_args(e->child, a.syscall, &a)) {
kperror("tracy_modify_syscall_args");
rc = TRACY_HOOK_ABORT;
goto out;
}
// set devname so we can free it later
mbc->memory = devname_new;
} else {
// free previous data
if (mbc->memory) {
free_patharg(e->child, mbc->memory);
mbc->memory = NULL;
}
}
out:
if (path)
free(path);
if (devname_new && rc)
free_patharg(e->child, devname_new);
return rc;
}
