118 lines
3 KiB
C++
118 lines
3 KiB
C++
// Copyright 2015 The Chromium Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#include "sandbox/linux/services/namespace_utils.h"
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#include <fcntl.h>
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#include <sched.h>
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#include <stddef.h>
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#include <sys/stat.h>
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#include <sys/types.h>
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#include <unistd.h>
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#include <string>
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#include "base/files/file_path.h"
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#include "base/files/file_util.h"
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#include "base/files/scoped_file.h"
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#include "base/logging.h"
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#include "base/posix/eintr_wrapper.h"
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#include "base/process/launch.h"
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#include "base/strings/safe_sprintf.h"
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#include "base/third_party/valgrind/valgrind.h"
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namespace sandbox {
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namespace {
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bool IsRunningOnValgrind() {
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return RUNNING_ON_VALGRIND;
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}
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const char kProcSelfSetgroups[] = "/proc/self/setgroups";
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} // namespace
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// static
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bool NamespaceUtils::WriteToIdMapFile(const char* map_file, generic_id_t id) {
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// This function needs to be async-signal-safe, as it may be called in between
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// fork and exec.
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int fd = HANDLE_EINTR(open(map_file, O_WRONLY));
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if (fd == -1) {
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return false;
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}
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const generic_id_t inside_id = id;
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const generic_id_t outside_id = id;
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char mapping[64];
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const ssize_t len =
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base::strings::SafeSPrintf(mapping, "%d %d 1\n", inside_id, outside_id);
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const ssize_t rc = HANDLE_EINTR(write(fd, mapping, len));
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RAW_CHECK(IGNORE_EINTR(close(fd)) == 0);
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return rc == len;
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}
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// static
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bool NamespaceUtils::KernelSupportsUnprivilegedNamespace(int type) {
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// Valgrind will let clone(2) pass-through, but doesn't support unshare(),
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// so always consider namespaces unsupported there.
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if (IsRunningOnValgrind()) {
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return false;
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}
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// As of Linux 3.8, /proc/self/ns/* files exist for all namespace types. Since
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// user namespaces were added in 3.8, it is OK to rely on the existence of
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// /proc/self/ns/*.
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if (!base::PathExists(base::FilePath("/proc/self/ns/user"))) {
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return false;
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}
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const char* path;
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switch (type) {
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case CLONE_NEWUSER:
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return true;
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case CLONE_NEWIPC:
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path = "/proc/self/ns/ipc";
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break;
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case CLONE_NEWNET:
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path = "/proc/self/ns/net";
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break;
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case CLONE_NEWNS:
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path = "/proc/self/ns/mnt";
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break;
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case CLONE_NEWPID:
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path = "/proc/self/ns/pid";
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break;
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case CLONE_NEWUTS:
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path = "/proc/self/ns/uts";
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break;
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default:
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NOTREACHED();
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return false;
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}
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return base::PathExists(base::FilePath(path));
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}
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// static
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bool NamespaceUtils::KernelSupportsDenySetgroups() {
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return base::PathExists(base::FilePath(kProcSelfSetgroups));
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}
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// static
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bool NamespaceUtils::DenySetgroups() {
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// This function needs to be async-signal-safe.
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int fd = HANDLE_EINTR(open(kProcSelfSetgroups, O_WRONLY));
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if (fd == -1) {
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return false;
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}
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static const char kDeny[] = "deny";
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const ssize_t len = sizeof(kDeny) - 1;
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const ssize_t rc = HANDLE_EINTR(write(fd, kDeny, len));
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RAW_CHECK(IGNORE_EINTR(close(fd)) == 0);
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return rc == len;
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}
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} // namespace sandbox
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