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// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include <dirent.h>
#include <errno.h>
#include <fcntl.h>
#include <stdarg.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <unistd.h>
#include "sandbox/linux/seccomp-bpf/sandbox_bpf.h"
#include "sandbox/linux/seccomp-bpf/util.h"
namespace playground2 {
bool Util::SendFds(int transport, const void *buf, size_t len, ...) {
int count = 0;
va_list ap;
va_start(ap, len);
while (va_arg(ap, int) >= 0) {
++count;
}
va_end(ap);
if (!count) {
return false;
}
char cmsg_buf[CMSG_SPACE(count*sizeof(int))];
memset(cmsg_buf, 0, sizeof(cmsg_buf));
struct iovec iov[2] = { { 0 } };
struct msghdr msg = { 0 };
int dummy = 0;
iov[0].iov_base = &dummy;
iov[0].iov_len = sizeof(dummy);
if (buf && len > 0) {
iov[1].iov_base = const_cast<void *>(buf);
iov[1].iov_len = len;
}
msg.msg_iov = iov;
msg.msg_iovlen = (buf && len > 0) ? 2 : 1;
msg.msg_control = cmsg_buf;
msg.msg_controllen = CMSG_LEN(count*sizeof(int));
struct cmsghdr *cmsg = CMSG_FIRSTHDR(&msg);
cmsg->cmsg_level = SOL_SOCKET;
cmsg->cmsg_type = SCM_RIGHTS;
cmsg->cmsg_len = CMSG_LEN(count*sizeof(int));
va_start(ap, len);
for (int i = 0, fd; (fd = va_arg(ap, int)) >= 0; ++i) {
(reinterpret_cast<int *>(CMSG_DATA(cmsg)))[i] = fd;
}
return sendmsg(transport, &msg, 0) ==
static_cast<ssize_t>(sizeof(dummy) + ((buf && len > 0) ? len : 0));
}
bool Util::GetFds(int transport, void *buf, size_t *len, ...) {
int count = 0;
va_list ap;
va_start(ap, len);
for (int *fd; (fd = va_arg(ap, int *)) != NULL; ++count) {
*fd = -1;
}
va_end(ap);
if (!count) {
return false;
}
char cmsg_buf[CMSG_SPACE(count*sizeof(int))];
memset(cmsg_buf, 0, sizeof(cmsg_buf));
struct iovec iov[2] = { { 0 } };
struct msghdr msg = { 0 };
int err;
iov[0].iov_base = &err;
iov[0].iov_len = sizeof(int);
if (buf && len && *len > 0) {
iov[1].iov_base = buf;
iov[1].iov_len = *len;
}
msg.msg_iov = iov;
msg.msg_iovlen = (buf && len && *len > 0) ? 2 : 1;
msg.msg_control = cmsg_buf;
msg.msg_controllen = CMSG_LEN(count*sizeof(int));
ssize_t bytes = recvmsg(transport, &msg, 0);
if (len) {
*len = bytes > static_cast<int>(sizeof(int)) ? bytes - sizeof(int) : 0;
}
if (bytes != static_cast<ssize_t>(sizeof(int) + iov[1].iov_len)) {
if (bytes >= 0) {
errno = 0;
}
return false;
}
if (err) {
// "err" is the first four bytes of the payload. If these are non-zero,
// the sender on the other side of the socketpair sent us an errno value.
// We don't expect to get any file handles in this case.
errno = err;
return false;
}
struct cmsghdr *cmsg = CMSG_FIRSTHDR(&msg);
if ((msg.msg_flags & (MSG_TRUNC|MSG_CTRUNC)) ||
!cmsg ||
cmsg->cmsg_level != SOL_SOCKET ||
cmsg->cmsg_type != SCM_RIGHTS ||
cmsg->cmsg_len != CMSG_LEN(count*sizeof(int))) {
errno = EBADF;
return false;
}
va_start(ap, len);
for (int *fd, i = 0; (fd = va_arg(ap, int *)) != NULL; ++i) {
*fd = (reinterpret_cast<int *>(CMSG_DATA(cmsg)))[i];
}
va_end(ap);
return true;
}
void Util::CloseAllBut(int fd, ...) {
int proc_fd;
int fdir;
if ((proc_fd = Sandbox::proc_fd()) < 0 ||
(fdir = openat(proc_fd, "self/fd", O_RDONLY|O_DIRECTORY)) < 0) {
SANDBOX_DIE("Cannot access \"/proc/self/fd\"");
}
int dev_null = open("/dev/null", O_RDWR);
DIR *dir = fdopendir(fdir);
struct dirent de, *res;
while (!readdir_r(dir, &de, &res) && res) {
if (res->d_name[0] < '0') {
continue;
}
int i = atoi(res->d_name);
if (i >= 0 && i != dirfd(dir) && i != dev_null) {
va_list ap;
va_start(ap, fd);
for (int f = fd;; f = va_arg(ap, int)) {
if (f < 0) {
if (i <= 2) {
// Never ever close 0..2. If we cannot redirect to /dev/null,
// then we are better off leaving the standard descriptors open.
if (dev_null >= 0) {
if (HANDLE_EINTR(dup2(dev_null, i))) {
SANDBOX_DIE("Cannot dup2()");
}
}
} else {
if (HANDLE_EINTR(close(i))) { }
}
break;
} else if (i == f) {
break;
}
}
va_end(ap);
}
}
closedir(dir);
if (dev_null >= 0) {
if (HANDLE_EINTR(close(dev_null))) { }
}
return;
}
} // namespace
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